BACKGROUND OF THE INVENTION
[0001] The present invention relates to a heat exchanger. The present invention more particularly
relates to a heat exchanger for use in a refrigeration cycle (vapor-compression refrigeration
cycle) device in which a refrigerant circuit including a compressor, a condenser (or
gas cooler or condensing heat exchanger or gas cooling heat exchanger), a throttling
means and an evaporator is constituted and in which carbon dioxide is introduced as
a refrigerant, and a refrigeration cycle device using the heat exchanger.
[0002] Heretofore, in a refrigeration cycle device in which a refrigerant circuit including
a compressor, a condenser, a throttling means and an evaporator is constituted, a
fluorocarbon-based refrigerant has broadly been used. However, in recent years, this
type of refrigerant cannot be used owing to global environment problems such as prevention
of ozone layer destruction and prevention of global warming, and attempts to use carbon
dioxide as the refrigerant instead of the fluorocarbon-based refrigerant have been
made.
[0003] In a refrigeration cycle device in which a carbon dioxide refrigerant is used, a
pressure of the refrigerant circuit remarkably increases as compared with a case where
the conventional fluorocarbon-based refrigerant is used. Therefore, as each unit (the
compressor, the condenser, the throttling means, the evaporator and the like) constituting
the refrigerant circuit, a unit capable of bearing such a high pressure needs to be
used. On the other hand, a theoretical coefficient of performance of the carbon dioxide
refrigerant in the refrigerant circuit is remarkably lower than that of the conventional
fluorocarbon-based refrigerant. Therefore, a heat exchanger having a high thermal
performance is demanded (see, e.g.,
Japanese Patent Application Laid-Open No. 2005-37054).
[0004] However, to bear such a high pressure of the carbon dioxide refrigerant, a thickness
of each member constituting the heat exchanger needs to be increased, but this causes
a problem of an increasing thermal conduction loss. Especially, in a case where the
heat exchanger is constituted of an evaporator to cool an object to be cooled stored
in a cooling vessel from the outside of the cooling vessel, it has been difficult
for such a structure of the heat exchanger to bear the high pressure of the carbon
dioxide refrigerant and secure the high thermal performance. That is, when the member
constituting the evaporator is thickened so as to bear the high pressure of the carbon
dioxide refrigerant, the thermal conduction loss further increases. As a result, a
problem occurs that the thermal performance remarkably deteriorates as compared with
the evaporator in which the conventional refrigerant is used.
[0005] Moreover, as another method of securing a high pressure resistance, it is considered
that a round tube formed so as to have an excellent strength is used as a refrigerant
passage of the evaporator. However, in a portion where the round tube comes into contact
with the cooling vessel in which the object to be cooled is stored, a contact heat
resistance increases. Therefore, such remarkable deterioration of the thermal performance
cannot be avoided.
SUNIMARY OF THE INVENTION
[0006] Therefore, the present invention has been developed to solve a problem of such a
conventional technology, and an object thereof is to improve a pressure resistance
and a thermal performance of a heat exchanger and to provide the heat exchanger suitable
for use in a refrigeration cycle device in which carbon dioxide is used as a refrigerant.
[0007] A heat exchanger of a first invention is characterized by comprising: a pair of plate
materials, the whole periphery of a peripheral portion of at least one of the plate
materials is secured to the other plate material to constitute a sealed refrigerant
passage space between the plate materials, a portion of the one plate material other
than the peripheral portion is provided with a plurality of secured inner portions
which are secured at predetermined intervals to the other plate material, and a plurality
of refrigerant inlet tubes and refrigerant outlet tubes are attached so as to communicate
with the refrigerant passage space.
[0008] Moreover, the heat exchanger of a second invention is characterized in that in the
above invention, the secured inner portions are arranged at the predetermined intervals
in a checkered form or a zigzag form.
[0009] The heat exchanger of a third invention is characterized in that in the above inventions,
the refrigerant inlet tubes communicate with the refrigerant passage space in the
center of the refrigerant passage space, and the refrigerant outlet tubes communicate
with the refrigerant passage space in a peripheral portion of the refrigerant passage
space.
[0010] A refrigeration cycle device of a fourth invention is characterized in that a refrigerant
circuit including a compressor, a condenser, a throttling means and an evaporator
is constituted, the heat exchanger according to any one of the first to third inventions
is used as the evaporator, carbon dioxide is introduced as a refrigerant, and a supercritical
pressure is obtained on a high-pressure side.
[0011] The refrigeration cycle device of a fifth invention is characterized in that in the
fourth invention, the surface of the other plate material opposite to the one plate
material constitutes a wall surface of a predetermined space to be cooled, and the
surface of the one plate material opposite to the other plate material is provided
with a predetermined insulation structure.
[0012] According to the present invention, the heat exchanger comprises a pair of plate
materials. The whole periphery of the peripheral portion of at least one of the plate
materials is secured to the other plate material to constitute the sealed refrigerant
passage space between the plate materials. Moreover, the portion of the one plate
material other than the peripheral portion is provided with the plurality of secured
inner portions which are secured at the predetermined intervals to the other plate
material. Therefore, for example, after the whole periphery of the peripheral portion
of the one plate material is secured to the other plate material, a pressure is applied
between the plate materials. In consequence, the refrigerant passage space is swelled
and formed between the plate materials. Therefore, where a pressure resistance of
the heat exchanger is secured, a thermal performance of the refrigerant can be improved.
[0013] Moreover, since the plurality of refrigerant inlet tubes and refrigerant outlet tubes
are attached so as to communicate with the refrigerant passage space, pressure losses
of the refrigerant at an inlet and an outlet of the heat exchanger can be reduced
while securing the pressure resistance of portions of the heat exchanger bonded to
the refrigerant inlet tubes and the refrigerant outlet tubes.
[0014] Furthermore, when the secured inner portions are arranged at the predetermined intervals
in the checkered form or the zigzag form, the pressure resistance of the heat exchanger
can be improved without increasing thicknesses of the one plate material and the other
plate material.
[0015] In addition, according to the present invention, the refrigerant inlet tubes communicate
with the refrigerant passage space in the center of the refrigerant passage space,
and the refrigerant outlet tubes communicate with the refrigerant passage space in
the peripheral portion of the refrigerant passage space. Therefore, since the refrigerant
entering the refrigerant passage space from the center flows so as to spread to the
peripheral portion, the refrigerant obtains a satisfactory diversion property. Stagnation
of the refrigerant in the heat exchanger can be prevented or eliminated as much as
possible.
[0016] Since the heat exchanger of the present invention has an excellent pressure resistance,
the heat exchanger can be used as the evaporator of the refrigeration cycle device
in which carbon dioxide is introduced as the refrigerant. In consequence, it is possible
to improve a performance of the refrigeration cycle device in which the carbon dioxide
refrigerant is used.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017]
FIG. 1 is a schematic constitution diagram of a refrigeration cycle device of one
embodiment to which the present invention is applied;
FIG. 2 is a sectional view showing a schematic structure of a cooling vessel;
FIG. 3 is a sectional view showing a schematic structure of an evaporator formed integrally
with the cooling vessel;
FIG. 4 is a schematic constitution diagram of the evaporator;
FIG. 5 is a schematic constitution diagram of a refrigeration cycle device according
to another embodiment of the present invention;
FIG. 6 is a schematic constitution diagram of an evaporator according to another embodiment
of the present invention; and
FIG. 7 is a diagram showing one example of a result of a destructive pressure test.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0018] Embodiments of a heat exchanger of the present invention and a refrigeration cycle
device including the heat exchanger will hereinafter be described in detail with reference
to the drawings.
(Embodiment 1)
[0019] A refrigeration cycle device of the present embodiment is one example applied to
a device which cools and insulates milk immediately after drawn until the milk is
shipped. FIG. 1 is a schematic constitution diagram of the refrigeration cycle device
of one embodiment to which the present invention is applied. A refrigeration cycle
device 1 of the present embodiment is provided with a refrigerant circuit 2 constituted
by connecting a compressor 10, a condenser (condensing heat exchanger or gas cooler
or gas cooling heat exchanger) 11, an expansion valve 14 as a throttling means and
an evaporator 16 in an annular form via pipes so as to form a closed circuit. That
is, a high-pressure refrigerant pipe 40 connected to the compressor 10 on a discharge
side is connected to an inlet of the condenser 11. The condenser 11 is a heat exchanger
which performs heat exchange between a refrigerant and a heat medium to release heat
of the refrigerant to the heat medium. It is assumed in the present embodiment that
air is used as the heat medium and that the heat exchange between air blown by a fan
11F and the refrigerant is performed.
[0020] Moreover, a refrigerant pipe 41 connected to an outlet of the condenser 11 is connected
to an inlet of the expansion valve 14. The expansion valve 14 is the throttling means
to reduce a pressure of the refrigerant which has rejected (transferred) the heat
in the condenser 11, and a refrigerant pipe 42 connected to an outlet of the expansion
valve 14 is connected to an inlet of the evaporator 16. Moreover, an outlet of the
evaporator 16 is connected to one end of a suction pipe 45, and the other end of the
suction pipe 45 is connected to the compressor 10 on a low-pressure side (a suction
portion). Along the suction pipe 45 which connects the evaporator 16 to the compressor
10 on the low-pressure side, an accumulator 17 is interposed which protects the compressor
from a disadvantage that a liquid refrigerant is sucked into the compressor 10 to
damage the compressor or the like. Furthermore, between the evaporator 16 of the suction
pipe 45 and the accumulator 17, a check valve 18 is disposed in which a compressor
10 side (an accumulator 17 side) is a forward direction in order to prevent a disadvantage
that the refrigerant flows back to the evaporator 16 from the refrigerant circuit
2 on a high-pressure side.
[0021] Furthermore, a discharge temperature sensor T1 which detects a temperature of the
high-temperature high-pressure refrigerant discharged from the compressor 10 is disposed
at the high-pressure refrigerant pipe 40. An evaporation temperature sensor T5 which
detects an evaporation temperature of the refrigerant in the evaporator 16 is disposed
at the evaporator 16 or the refrigerant pipe 42. Furthermore, a sucked refrigerant
temperature sensor T7 which detects a temperature of the refrigerant entering the
compressor 10 from the evaporator 16 is disposed at the suction pipe 45.
[0022] In addition, carbon dioxide which is a natural refrigerant is introduced as the refrigerant
in the refrigerant circuit 2. Since the pressure of the refrigerant circuit 2 on the
high-pressure side rises in excess of a critical pressure, the refrigerant cycle is
a trans-critical cycle. As a lubricant of the compressor 10, for example, mineral
oil, alkyl benzene oil, ether oil, ester oil, polyalkylene glycol (PAG), polyol ether
(POE) or the like is used.
[0023] On the other hand, the evaporator 16 is a heat exchanger which cools an object to
be cooled (milk in the present embodiment) stored in an inner tank 70 of a cooling
vessel 7, and is formed integrally with this cooling vessel 7. Here, the cooling vessel
7 of the present embodiment will be described in detail with reference to FIGS. 2
to 4. FIG. 2 is a sectional view showing a schematic structure of the cooling vessel
7; FIG. 3 is a sectional view showing a schematic structure of the evaporator 16 formed
integrally with the cooling vessel 7; and FIG. 4 is a schematic constitution diagram
of the evaporator 16, respectively. The cooling vessel 7 is provided with the inner
tank 70 having a predetermined space to be cooled in which the object to be cooled
(the milk) is stored in an outer tank 72 constituting an outer shell of the cooling
vessel 7. An outer plate (one plate material) 76 constituted of a plate material having
a high thermal conductivity is disposed on an outer surface (a bottom surface 70B
in the present embodiment) of the inner tank 70. The whole periphery of a peripheral
portion of the outer plate 76 is secured to the other plate material constituting
the bottom surface 70B, and a sealed refrigerant passage space 77 is constituted between
the plate materials (the bottom surface 70B of the inner tank 70 and the outer plate
76). It is assumed that this space is a refrigerant channel of the evaporator 16 (FIG.
3).
[0024] In this case, the surface of the other plate material (the bottom surface) 70B opposite
to the outer plate (the one plate material) 76 constitutes a wall surface of the predetermined
space to be cooled in which the object to be cooled (the milk) is stored, and the
surface of the outer plate 76 opposite to the bottom surface 70B as the other plate
material is provided with a predetermined insulation structure. That is, in cooling
vessel 7 of the present embodiment, a space between the inner tank 70 including the
surface opposite to the bottom surface 70B of the outer plate 76 and the outer tank
72 is filled with the an insulation material 74 constituted of a foaming material
such as urethane. After securing the outer plate 76 to the inner tank 70 and further
assembling the outer tank 72 on an outer side of the outer plate, the insulation material
74 is injected into the space between the inner tank 70 and the outer tank 72.
[0025] Moreover, a portion of the outer plate 76 other than the peripheral portion is provided
with a plurality of secured inner portions 78 which are secured at predetermined intervals
to the bottom surface 70B (FIGS. 3 and 4). Specifically, the whole periphery of the
peripheral portion of the outer plate 76 is secured to the bottom surface of the inner
tank 70 by seam welding, and the portion other than the peripheral portion is secured
at predetermined intervals in a checkered form or a zigzag form by spot welding (the
portions secured by the spot welding are the secured inner portions 78).
[0026] Here, the refrigerant channel (the refrigerant passage space 77) of the evaporator
16 is processed by pressurizing. Specifically, after the whole periphery of the peripheral
portion of the outer plate 76 and the secured inner portions 78 are secured to a bottom
portion of the inner tank 70 as described above, a pressure is applied between the
inner tank 70 and the outer plate 76. In consequence, the refrigerant passage space
77 is expanded and formed between the inner tank 70 and the outer plate 76. Therefore,
portions other than the secured inner portions 78 of the outer plate 76 swell outwards
substantially into circular sections (downwards in FIGS. 2 and 3), and a large number
of swelled portions are continuously formed in the checkered form or the zigzag form.
[0027] The bottom surface 70B of the inner tank 70 secured to the outer plate 76 is constituted
of a material having a high thermal conductivity in the same manner as in the outer
plate 76 so that heat exchange between the refrigerant flowing through the refrigerant
channel (the refrigerant passage space 77) of the evaporator 16 and the object to
be cooled (the milk) stored in the inner tank 70 is easily performed. It is preferable
that a material of the inner tank 70, the outer plate 76 and the outer tank 72 is
selected in consideration of corrosion, durability and the like. For example, as the
material of the inner tank 70, the outer plate 76 and the outer tank 72, a stainless
steel may be used.
[0028] Moreover, as a shape of the cooling vessel 7, various shapes such as a columnar shape,
a horizontally disposed elliptic columnar shape and a rectangular parallelepiped shape
are considered, but it is assumed in the present embodiment that the cooling vessel
has the horizontally disposed elliptic columnar shape. It has been described in the
present embodiment that the outer plate 76 is disposed on the bottom surface 70B of
the inner tank 70 to form the refrigerant channel (the refrigerant passage space 77)
of the evaporator 16 so that the object to be cooled (the milk) can efficiently be
cooled, but the outer plate may further be formed on a side surface of the inner tank
70 if necessary. It is to be noted that as not shown in FIG. 2 for the sake of simplicity
of the drawing, the cooling vessel 7 is provided with an introduction port 7A for
introducing the object to be cooled (the milk) and a takeout port 7B for taking out
the object to be cooled (the milk) (FIG. 1).
[0029] Furthermore, a plurality of refrigerant inlet tubes 16A and refrigerant outlet tubes
16B are attached to the refrigerant passage space 77 (the refrigerant channel of the
evaporator 16) formed between the bottom surface 70B of the inner tank 70 and the
outer plate 76 so that the tubes communicate with the refrigerant passage space 77.
The refrigerant inlet tubes 16A allow the refrigerant to enter the evaporator 16 (the
refrigerant passage space 77), and one end of each refrigerant inlet tube is connected
to the refrigerant passage space 577. The other end of the refrigerant inlet tube
16A is connected to the refrigerant pipe 42 so that the refrigerant is branched from
the refrigerant pipe 42 to the refrigerant passage space 77. The refrigerant outlet
tubes 16B discharge the refrigerant from the evaporator 16 (the refrigerant passage
space 77), and one end of each refrigerant outlet tube is connected to the refrigerant
passage space 77. The other end of the refrigerant outlet tubes 16B is connected to
the suction pipe 45 so as to combine the refrigerant from the refrigerant outlet tubes
16B.
[0030] In the cooling vessel 7 of the present embodiment, the inner tank 70 has a plate
thickness of 2 mm, and the outer plate 76 has a plate thickness of 1 mm. Each of the
spot-welded portions (secured inner portions 78) has a diameter of 6 mm, and it is
preferable to set a spot pitch (an interval from the center of a certain secured inner
portion 78 to the center of another secured inner portion 78 adjacent to the certain
secured inner portion 78) to 20 mm or less so as to bear use of the carbon dioxide
refrigerant. A specific method of determining the spot pitch will be described later.
In the present embodiment, the spot pitch is set to 18.5 mm. It is preferable that
an outer diameter of each of the refrigerant inlet tube 16A and the refrigerant outlet
tube 16B is 1/2 or less of the spot pitch in order to prevent deterioration of strength
of a tube bonding portion. In the present embodiment, the outer diameter is set to
φ6.35 mm (1/4 inch), and the plate thickness is set to 1.0 mm.
[0031] Moreover, in the present embodiment, as shown in FIG. 4, the refrigerant passage
space 77 is constituted of two parallel refrigerant channels obtained by dividing
a region into two regions at the center by seam welding. That is, the vicinity of
the center of the outer plate 76 is secured to the bottom surface 70B of the inner
tank 70 by the seam welding so that the refrigerant passage space 77 formed by securing
the whole periphery of the peripheral portion of the outer plate 76 to the bottom
surface 70B of the inner tank 70 by the seam welding as described above is divided
into two independent regions (two upper and lower regions in FIG. 4). In consequence,
the refrigerant passage space 77 is formed into two parallel refrigerant passages,
and the refrigerant from the refrigerant pipe 42 is branched via the refrigerant inlet
tubes 16A to enter the refrigerant passages.
[0032] It is to be noted that the refrigerant passage space 77 constituting the refrigerant
channels of the evaporator 16 is divided by the seam welding and can arbitrarily be
constituted. In the present embodiment, the region is divided in the vicinity of the
center to form the refrigerant passage space into two paths (two refrigerant passages).
However, the region may constitute one path without being divided as in the present
embodiment. As another method, the region may finely be divided to constitute three,
four or more paths. Furthermore, the refrigerant passage may be formed into a meandering
form or a spiral form by the seam welding.
[0033] Next, a processing method of the evaporator 16 will be described in detail. First,
a flat plate material as a material of the inner tank 70 is pressed and cut into a
predetermined size. Similarly, a flat plate material as a material of the outer plate
76 is pressed and cut into a predetermined size.
[0034] Next, a plurality of holes are processed beforehand in the outer plate 76, the holes
constituting refrigerant inlets to be connected to the refrigerant inlet tubes 16A
and refrigerant outlets to be connected to the refrigerant outlet tubes 16B. The outer
plates 76 are superimposed upon a position where the bottom surface 70B of the plate
material of the inner tank is to be formed. The outer plate 76 is secured by the spot
welding with spots made at the predetermined intervals in the checkered form and zigzag
form. In consequence, the outer plate 76 is provided with the plurality of secured
inner portions 78 secured at the predetermined intervals to the plate material constituting
a bottom portion of the inner tank 70. Subsequently, the whole periphery of the peripheral
portion of the outer plate 76 is secured to the bottom portion of the inner tank 70
by the seam welding, and further secured by the seam welding so as to form predetermined
refrigerant passages as needed. In the present embodiment, as described above, the
vicinity of the center of the outer plate 76 is secured to the plate material constituting
the bottom surface 70B of the inner tank 70 by the seam welding to form two parallel
refrigerant passages.
[0035] Next, the plate material of the inner tank 70 to which the outer plate 76 is attached
is formed into such a predetermined shape to form the inner tank 70 by roll processing
or press processing. In the present embodiment, since the inner tank has a horizontally
disposed elliptic columnar shape as described above, the flat plate material is rolled
and bent by the roll processing. Subsequently, the material is welded and bonded to
another member processed into a predetermined shape to form the inner tank 70.
[0036] One end of each of the refrigerant inlet tubes 16A and refrigerant outlet tubes 16B
is welded and bonded to each of the plurality of refrigerant inlet and outlet holes
made beforehand in the outer plate 76 attached to the inner tank 70 processed into
a predetermined tank shape as described above. Secured inner portions 78P closest
to bonded portions of these refrigerant inlet tubes 16A and refrigerant outlet tubes
16B are again welded from an outer plate 76 side to reinforce the tank.
[0037] It is to be noted that the refrigerant inlet tubes 16A or the refrigerant outlet
tubes 16B are substantially bonded between the spots welded at the predetermined intervals
in the checkered form or the zigzag form. Therefore, four secured inner portions 78P
for reinforcing the tank as described above are disposed for each of the refrigerant
inlet tubes 16A or the refrigerant outlet tubes 16B (FIG. 4).
[0038] Subsequently, a pressurizing fluid is injected from the refrigerant inlet tubes 16A
or the refrigerant outlet tubes 16B to apply a pressure to a space formed between
the inner tank 70 and the outer plate 76. In consequence, the portion of the outer
plate 76 other than the secured inner portions 78 is deformed outwards into a substantially
circular sectional shape to form the refrigerant passage space 77. Here, in a case
where a plurality of (two paths in the present embodiment) refrigerant passages of
the evaporator 16 are formed as in the present embodiment, it is preferable to simultaneously
apply the pressures to all of the refrigerant passages in order to prevent deviating
deformation.
[0039] It is to be noted that it has been described in the present embodiment that the inner
tank 70 is secured to the outer plate 76 by the spot welding and the seam welding,
but a securing method is not limited to this example. The securing can be performed
by another method such as laser welding.
[0040] On the other hand, an introduction pipe (not shown) is detachably connected to the
introduction port 7A of the cooling vessel 7 into which the object to be cooled (the
milk) is introduced via an introduction port valve. Similarly, a takeout pipe for
taking out the milk is detachably connected to the takeout port 7B via a takeout valve.
Moreover, the introduction pipe is attached to the introduction port 7A in an only
case where the object to be cooled (the milk) is introduced into the inner tank 70
of the cooling vessel 7. In another case, the pipe is detached from the introduction
port 7A, and the introduction port 7A is hermetically closed. Similarly, the takeout
pipe is attached to the takeout port 7B in an only case where the object to be cooled
(the milk) is taken out of the inner tank 70 of the cooling vessel 7. In another case,
the pipe is detached from the takeout port 7B, and the takeout port 7B is hermetically
closed.
[0041] Moreover, the cooled object temperature sensor T5 for detecting the temperature of
the object to be cooled (the milk) is attached to the outer peripheral surface of
the inner tank 70 of the cooling vessel 7. Furthermore, the cooling vessel 7 is provided
with a stirrer (not shown) which stirs the object to be cooled (the milk) in order
to promote heat conduction during cooling, reduce temperature unevenness of the object
to be cooled (the milk) stored in the inner tank 70 and perform correct temperature
measurement.
[0042] Next, an operation of the refrigeration cycle device 1 of the present embodiment
constituted as described above will be described.
(1) Operation during Cooling Operation
[0043] First, an operation to cool the milk as the object to be cooled during a cooling
operation will be described. A milking pipeline connected to a milking machine (not
shown) is connected to the introduction port 7A of the cooling vessel 7 via an introduction
pipe (not shown), the introduction port valve is opened, and the milk immediately
after drawn is introduced into the cooling vessel 7. At this time, the takeout valve
is completely closed, and the takeout port 7B is also hermetically closed. A temperature
of the milk immediately after drawn is substantially equal to or slightly lower than
a body temperature of a cow, and is specifically in a range of about 35°C to 38°C.
Then, the refrigerant circuit 2 is operated to cool and insulate the milk for the
purpose of preventing generation of bacteria and maintaining a quality of the milk.
[0044] After starting the milking (after starting the introduction of the milk), the compressor
10 of the refrigerant circuit 2 is driven, and the stirrer (not shown) is simultaneously
driven. Usually, it is assumed that after a predetermined amount of milk is stored
in the cooling vessel 7, the compressor 10 is driven to start the cooling operation.
However, the cooling operation may be started simultaneously with the start of the
introduction of the milk or before the introduction of the milk as long as careful
consideration is given so as to prevent freezing and idling of the stirrer is prevented.
[0045] When the compressor 10 is driven, a low-temperature low-pressure refrigerant gas
is sucked and compressed on the low-pressure side (the suction portion) of the compressor
10 from the suction pipe 45. In consequence, the refrigerant gas which has obtained
a high temperature and a high pressure enters the high-pressure refrigerant pipe 40
from the discharge side, and is discharged from the compressor 10. At this time, the
refrigerant is compressed under an appropriate supercritical pressure.
[0046] The high-temperature high-pressure refrigerant discharged from the compressor 10
enters the condenser 11 via the high-pressure refrigerant pipe 40. Here, the refrigerant
releases the heat to air, and is cooled at a low temperature by ventilation of the
fan 11F. At this time, since the pressure of the refrigerant is not less than a supercritical
pressure in the condenser 11, the refrigerant is not condensed. Therefore, the temperature
of the refrigerant gradually lowers from the inlet toward the outlet of the condenser
11 as the heat is rejected to the air. Moreover, at the outlet of the condenser 11,
the refrigerant is brought into a liquid-phase state usually having the pressure which
is not less than the critical pressure (or above the critical pressure).
[0047] Moreover, the low-temperature high-pressure refrigerant discharged from the condenser
11 passes through the refrigerant pipe 41. The pressure of the refrigerant is reduced
by the expansion valve 14. The refrigerant expands to obtain a low pressure, is then
branched to flow through the refrigerant inlet tubes 16A via the refrigerant pipe
42, and reaches the evaporator 16. It is to be noted that the refrigerant at the inlet
of the evaporator 16 has a two-phase mixed state in which the liquid refrigerant is
mixed with a vapor refrigerant. Moreover, when the liquid-phase refrigerant absorbs
the heat from the milk as the object to be cooled in the evaporator 16, the refrigerant
evaporates to form the vapor refrigerant. At this time, the milk is cooled by the
heat absorption.
[0048] Furthermore, the refrigerant evaporated in the evaporator 16 repeats a cycle of exiting
from the evaporator 16 via the refrigerant outlet tubes 16B to combine and enter the
suction pipe 45 and being again sucked from the low-pressure side to the compressor
10 via the check valve 18 and the accumulator 17. When the above cycle is repeated,
the milk is cooled by the heat absorption of the refrigerant in the evaporator 16.
[0049] When the milking is completed, the introduction of the milk into the cooling vessel
7 is completed. However, the above cooling operation is continued until the milk reaches
a predetermined temperature. Here, the temperature of the milk is detected by the
cooled object temperature sensor T5 attached to the outer peripheral surface of the
inner tank 70. The predetermined temperature at which the cooling operation ends is
set from a viewpoint that the generation of the bacteria in the milk be inhibited
and the quality be maintained, and is specifically about 4°C.
[0050] Furthermore, during the cooling operation, an open degree of the expansion valve
14 is adjusted so that a difference between the temperature of the refrigerant entering
the compressor 10 from the evaporator 16 detected by the sucked refrigerant temperature
sensor T7 disposed at the suction pipe 45 of the refrigerant circuit 2 and the evaporation
temperature of the refrigerant detected by the evaporation temperature sensor T6 disposed
at the evaporator 16 or the refrigerant pipe 42, that is, a so-called superheat degree
indicates a predetermined value. That is, when the superheat degree is larger than
the predetermined value, the open degree of the expansion valve 14 is enlarged. Conversely,
when the superheat degree is smaller than the predetermined value, the open degree
of the expansion valve 14 is reduced.
[0051] It is to be noted that the compressor 10 during the cooling operation may have the
constant number of rotations. Alternatively, a frequency may be adjusted by an inverter
or the like. In the present embodiment, a required cooling capacity is calculated
from a change of the temperature of the milk with time, the temperature being detected
by the cooled object temperature sensor T5 attached to the outer peripheral surface
of the inner tank 70, and the number of the rotations of the compressor 10 is controlled
so as to obtain the operation frequency according to the calculation result. In consequence,
a cooling efficiency can be improved.
[0052] Here, the above control will be described in detail. As described above, the predetermined
temperature at which the milk is cooled in the cooling vessel 7 is determined from
a viewpoint of the maintenance of the quality of the milk as the object to be cooled.
For a similar reason, a required time for cooling the milk at the predetermined temperature
is determined. Since a cow farming scale differs with a farm, a device to cool the
milk is selected in accordance with each farming scale so as to complete the cooling
at the predetermined temperature within a predetermined time. However, since a milking
amount fluctuates even in the same farm daily, milk quality control is usually prioritized,
and the refrigeration cycle device having a sufficiently large cooling capacity is
used. Therefore, when the number of the rotations of the device during the cooling
operation is set to be constant, an excessively large cooling capacity is required
during an actual cooling operation, and the operation cannot necessarily be said to
be efficient.
[0053] To solve the problem, in the present embodiment, a cooling speed is calculated from
the change of the temperature of the milk with time, detected by the cooled object
temperature sensor T5 attached to the outer portion of the inner tank 70 as described
above. The number of the rotations of the compressor 10 is adjusted so as to complete
the cooling operation within a preset required cooling time, and the cooling capacity
is controlled. That is, according to a calculation result, in a case where it is judged
that a small amount of the milk is to be cooled and that the cooling at the predetermined
temperature is completed within a time which is shorter than the predetermined required
time, control is executed so as to reduce the number of the rotations of the compressor
10. In consequence, the evaporation temperature can be raised, and the efficiency
can be improved. Therefore, while a predetermined cooling capacity is satisfied and
the quality of the milk is secured, energy consumption during the cooling operation
can be reduced.
[0054] It is to be noted that the operation at a frequency at which the highest efficiency
is obtained may be prioritized in consideration of the operation efficiency of the
compressor 10, a conversion efficiency of the inverter and the like. In this case,
the cooling operation is sometimes completed within the time shorter than the predetermined
required time on conditions that the amount of the milk is sufficiently small.
[0055] As described above, during the cooling operation of the refrigeration cycle device
1 of the present embodiment, when the milk immediately after drawn is introduced into
the cooling vessel 7, the milk can be cooled at the predetermined temperature in order
to maintain the quality of the milk.
(2) Operation during Cold Insulating Operation
[0056] When the temperature of the milk reaches the predetermined value during the above
cooling operation, the compressor 10 is stopped, the expansion valve 14 is completely
closed and the stirrer (not shown) is stopped to end the cooling operation, and a
cold insulating operation of the milk stored in the cooling vessel 7 is performed.
In this case, the cooling vessel 7 is insulated by the insulation material 74 as described
above, but the temperature of the milk rises owing to the heat entering from the outside
during storage for a long time.
[0057] To solve the problem, even when the compressor 10 and the like are stopped during
the cold insulating operation, the milk temperature sensor T5 continuously detects
the temperature of the milk stored in the cooling vessel 7 (this state will hereinafter
be referred to as a standby state). When the milk temperature reaches the predetermined
value or more, the cooling operation is started again to cool the milk. Moreover,
when the milk is cooled at the predetermined temperature by the cooling operation
during the cold insulating operation, the cooling operation is stopped, and the device
is brought into the standby state again. The predetermined temperature at which the
cooling operation is started during the cold insulating operation is specifically
about 4.5°C, and the predetermined temperature at which the cooling operation is stopped
is about 4°C.
[0058] Moreover, the expansion valve 14 is completely closed in the standby state in order
to prevent a refrigerant backflow from the high-pressure side of the refrigerant circuit
2 to the evaporator 16 and suppress the incoming heat into the milk as the object
to be cooled in combination with the function of the check valve 18 disposed between
the evaporator 16 and the accumulator 17 along the suction pipe 45. It is to be noted
that even in a case where a block valve or the like is disposed at the suction pipe
45 instead of the check valve 18 or at the refrigerant pipe 42 or 41 instead of the
expansion valve 14 and the block valve is closed in the standby state during the cold
insulating operation, a similar effect can be obtained.
[0059] Here, it is assumed that the stirrer is driven intermittently at a constant interval
in the standby state during the cold insulating operation. It is assumed that a stirring
operation is performed for, for example, two minutes at an interval of 30 minutes.
The stirrer is intermittently driven in this manner in order to prevent a disadvantage
that a temperature distribution is stratificationally generated in the cooling vessel
7 owing to a temperature difference of the milk during cold storage for a long time
and that correct temperature measurement cannot be performed.
[0060] Since an operation of the refrigerant circuit 2 is similar to the above cooling operation
during the milking, detailed description is omitted here. It is assumed that during
the cold insulating operation, the compressor 10 is controlled to operate with the
number of the rotations with the best efficiency irrespective of the amount of the
milk.
(3) Operation Patterns of Cooling Operation and Cold Insulating Operation in general
Farm
[0061] The cooling operation and the cold insulating operation of the introduced milk during
the milking have been described above. Next, operation patterns of the cooling operation
and the cold insulating operation in a general farm will be described.
[0062] In the general farm, the milking is performed about twice or three times a day. During
and after the second milking, the milk immediately after drawn is additionally introduced
into the cooling vessel 7 in which the cooled and insulated milk is stored. As a result,
since the milk temperature in the cooling vessel 7 rises, the cooling operation is
started. When the temperature reaches the predetermined temperature, the cooling operation
is stopped to perform the cold insulating operation as described above.
[0063] Moreover, there is a case where the milk is taken out of the cooling vessel 7 (milk
cargo collection) every day or every other day. Therefore, from the first milking
till the milk cargo collection, the cooling operation and the cold insulating operation
of the introduced milk are repeatedly performed twice to six times.
(4) Regarding Refrigerant Inlet Tubes 16A and Refrigerant Outlet Tubes 16B
[0064] Next, a relation between sizes and spot pitches of the refrigerant inlet tubes 16A
and refrigerant outlet tubes 16B, and a relation between the number of the refrigerant
inlet tubes 16A and the refrigerant outlet tubes 16B and the capacity of the cooling
vessel 7 will be described in more detail.
[0065] Since carbon dioxide is used as the refrigerant in the refrigerant circuit 2 of the
present embodiment, the refrigerant pressure in the evaporator 16 during the cooling
operation is as high as about 3 MPa to 5MPa as compared with a conventional fluorocarbon-based
refrigerant. Therefore, a pressure resistance in excess of at least 20 MPa is considered
to be necessary in consideration of safety during the operation of the compressor
10. Furthermore, it is preferable to secure a pressure resistance of about 25 MPa
or more in consideration of a pressure rise during stopping of the compressor 10.
[0066] Especially, the pressure resistances of the bonded portions of the refrigerant inlet
tubes 16A and the refrigerant outlet tubes 16B of the evaporator 16 differ with outer
dimensions and the spot pitches of the refrigerant inlet tubes 16A and the refrigerant
outlet tubes 16B. Therefore, the dimensions and the spot pitches need to be set so
that the pressure resistance suitable for the use of carbon dioxide can be secured.
[0067] To solve the pressure, a destructive pressure test was conducted using the evaporator
having variously changed spot pitches. FIG. 7 shows one example of a result of the
destructive pressure test, the abscissa indicates the spot pitch of each spot welding
(an interval between the center of the certain secured inner portion 78 and the center
of the secured inner portion 78 adjacent to the certain secured inner portion 78,
i.e., a distance between spots), and the ordinate shows a destructive pressure. According
to the test result shown in FIG. 7, it has been found that the destructive pressure
depends on the spot pitch and that, if the spot pitch exceeds 20 mm, it is difficult
to secure the pressure resistance of 25 MPa or more. Therefore, it is preferable to
set the spot pitch to 20 mm or less. In the present embodiment, the spot pitch is
set to 18.5 mm as described above.
[0068] However, here, it has been found that, when a tube having a dimension (especially,
an outer diameter) substantially equal to that of the refrigerant pipe 42 or the suction
pipe 45 is used as the refrigerant inlet tubes 16A and the refrigerant outlet tubes
16B as in a conventional example, the pressure resistances of the bonded portions
of the refrigerant inlet tubes 16A and the refrigerant outlet tubes 16B remarkably
deteriorate owing to the heat during the welding. Then, the destructive pressure test
was performed on conditions that shapes and tube dimensions of the refrigerant inlet
tubes 16A and the refrigerant outlet tubes 16B were changed. It has been found that,
when the outer diameter of each of the refrigerant inlet tubes 16A and the refrigerant
outlet tubes 16B is set to be 1/2 or less of the spot pitch, deterioration of strength
of each bonded portion of the tubes 16A, 16B can be prevented. Therefore, it is assumed
in the present embodiment that as the refrigerant inlet tubes 16A and the refrigerant
outlet tubes 16B, the pipe having an outer diameter of φ6.35 mm (1/4 inch) and a plate
thickness of 1.0 mm is used.
[0069] Furthermore, even in a case where the refrigerant inlet tubes 16A and the refrigerant
outlet tubes 16B each having an outer diameter smaller than that of the refrigerant
pipe 42 or the suction pipe 45 are used, when one refrigerant inlet tube 16A and one
refrigerant outlet tube 16B are connected to one refrigerant passage of the evaporator
as in a conventional case, pressure losses of the refrigerant at the refrigerant inlet
and outlet of the evaporator 16 increase. This has incurred the deterioration of the
efficiently of the refrigeration cycle device 1.
[0070] To solve the problem, as a result of investigation of the number of the refrigerant
inlet tubes 16A, the number of the refrigerant outlet tubes 16B and the capacity of
the cooling vessel 7, it has been concluded that it is possible to secure the numbers
of the refrigerant inlet tubes 16A and the refrigerant outlet tubes 16B, which are
not less than at least a value obtained by the following equation (1):

in which NT is the number (tubes) of the refrigerant inlet tubes 16A or the refrigerant
outlet tubes 16B of the evaporator 16, V is a rated capacity (L) of the cooling vessel
7 and N is the number of times of milking every cargo collection.
[0071] Since the evaporator 16 of the present invention performs heat exchange between the
object to be cooled (the milk) and the refrigerant via the only inner tank 70, a thermal
performance of the refrigerant improves, and a temperature difference between the
object to be cooled (the milk) and the refrigerant can remarkably be reduced. As a
result, it is possible to obtain an effect that the evaporation temperature and an
evaporation pressure increase and that the efficiency of the refrigeration cycle device
1 improves. However, if the number of the refrigerant inlet tubes 16A or the refrigerant
outlet tubes 16B is smaller than that obtained by Equation (1), the pressure losses
of the refrigerant at the inlet and the outlet of the evaporator 16 increases, and
the efficiency deteriorates. Therefore, the above excellent effect of the thermal
performance is offset.
[0072] That is, when the pressure losses of the refrigerant in the evaporator 16 increase,
a suction pressure of the compressor 10 drops, and an amount (a refrigerant circulation
amount) of the refrigerant to be circulated through the refrigerant circuit 2 decreases.
Therefore, a disadvantage occurs that the cooling capacity of the evaporator 16 deteriorates,
a pressure difference of the compressor 10 further increases, and the efficiency of
the refrigeration cycle device 1 deteriorates.
[0073] In the present embodiment, the cooling vessel 7 having a rated capacity of 1150 liters
is used, and the number of the milking times per cargo collection is twice. Therefore,
NT (the number of the refrigerant inlet tubes 16A or the refrigerant outlet tubes
16B) calculated from Equation (1) is 3.7, and four refrigerant inlet tubes 16A and
four refrigerant outlet tubes 16B of the evaporator 16 are used. It is to be noted
that in the present embodiment, the evaporator 16 has two paths of the refrigerant
passages as described above. Therefore, the refrigerant from the refrigerant pipe
42 is branched through the four refrigerant inlet tubes 16A, and the refrigerant enters
either of two refrigerant passages of the evaporator 16 from each refrigerant inlet
tube 16A. In consequence, two refrigerant inlet tubes 16A are connected to one refrigerant
passage, and two refrigerant outlet tubes 16B are similarly connected to the passage.
[0074] Next, a flow of the refrigerant in one refrigerant passage of the evaporator 16 will
be described. The refrigerant entering one refrigerant passage of the evaporator 16
from two refrigerant inlet tubes 16A is combined in the one refrigerant passage, absorbs
the heat by the heat exchange between the refrigerant and the object to be cooled
(the milk), evaporates, is then branched into two flows to enter the refrigerant outlet
tubes 16B, exits from the evaporator 16, and is then combined to flow through the
suction pipe 45.
[0075] Next, an area of the outer plate 76 will be described. Since the refrigerant passage
space 77 constituted between the inner tank 70 and the outer plate 76 is the refrigerant
passage of the evaporator 16 as described above, it is considered that the area of
the outer plate 76 is substantially equal to a heat conduction area of the evaporator
16. Therefore, the area of the outer plate 76 should be determined in consideration
of a required cooling capacity in accordance with the capacity of the cooling vessel
7 (the inner tank 70). Specifically, it is preferable to set the area to be not less
than an area obtained by Equation (2):

in which A is an area (m
2) of the outer plate, V is a rated capacity (L) of the cooling vessel 7, and N is
the number of the milking times every cargo collection.
[0076] When the area of the outer plate 76 is set to be smaller than the value calculated
by Equation (2), a temperature difference between the object to be cooled and the
refrigerant in the evaporator 16, and the evaporation pressure drops. As a result,
the cooling capacity and the efficiency deteriorate, and an highly efficient cooling
operation cannot be performed.
[0077] It is to be noted that, needless to say, the area of the outer plate, that is, the
heat conduction area can easily be secured, depending on the shape of the cooling
vessel (the inner tank). In this case, the outer plate having an area larger than
the value obtained by Equation (2) may be used. In the present embodiment, as described
above, the cooling vessel 7 having a rated capacity of 1150 liters is used, and the
number of the milking times per cargo collection is twice. Therefore, A (the area
of the outer plate 76) calculated from Equation (2) is 1.15. However, the area can
further be enlarged in consideration of the shape of the inner tank 70 of the present
embodiment. Therefore, the area of the outer plate 76 is set to 1.6 m
2.
[0078] As described above in detail, in the present embodiment, the portions of the refrigerant
passage space 77 between the inner tank 70 and the outer plate 76 constituting the
evaporator 16 are bonded at an interval of 20 mm or less in the checkered form or
the zigzag form. Therefore, the pressure resistance of the evaporator 16 can be improved
without increasing the plate thicknesses of the inner tank 70 and the outer plate
76. The outer diameter of the refrigerant inlet tube 16A which allows the refrigerant
to enter the evaporator 16 is set to be smaller than that of the refrigerant pipe
42, and 1/2 or less of the spot pitch. The plurality of refrigerant inlet tubes 16A
are connected to the refrigerant passage (the refrigerant passage space 77) of the
evaporator 16. In consequence, when the refrigerant inlet tubes 16A are connected
to the evaporator 16, the deterioration of the strength of the bonded portion of the
refrigerant inlet tube 16A due to the welding can be prevented to the utmost. Moreover,
the pressure losses of the refrigerant can be reduced.
[0079] Similarly, the outer diameter of the refrigerant outlet tube 16B which allows the
refrigerant to exit from the evaporator 16 is set to be smaller than that of the suction
pipe 45, and 1/2 or less of the spot pitch. Moreover, the plurality of refrigerant
outlet tubes 16B are connected to the refrigerant passage (the refrigerant passage
space 77) of the evaporator 16. In consequence, when the refrigerant outlet tubes
16B are connected to the evaporator 16, the deterioration of the strength of the bonded
portion of the refrigerant outlet tube 16B due to the welding can be prevented to
the utmost. Moreover, the pressure losses of the refrigerant can be reduced.
[0080] Furthermore, since the pressure resistance of the evaporator 16 can be secured without
increasing the plate thicknesses of the inner tank 70 and the outer plate 76 constituting
the evaporator 16 as described above, the heat exchange between the object to be cooled
and the refrigerant flowing through the evaporator 16 is performed via the only inner
tank 70. Therefore, the thermal performance of the evaporator 16 can be improved.
[0081] As a result, the temperature difference between the object to be cooled and the refrigerant
during the cooling operation can further be reduced. In consequence, since the evaporation
temperature and the evaporation pressure rise and the refrigerant circulation amount
of the refrigerant circuit 2 increases, the pressure difference can be reduced. As
described above, while the pressure resistance of the heat exchanger (the evaporator
16) is secured in the refrigeration cycle device using carbon dioxide, the cooling
capacity and the efficiency can be improved.
(Embodiment 2)
[0082] Next, a refrigeration cycle device of another embodiment to which the present invention
is applied will be described. FIG. 5 is a schematic constitution diagram of the refrigeration
cycle device of the embodiment to which the present invention is applied. The refrigeration
cycle device of the present embodiment cools and insulates milk (an object to be cooled)
immediately after drawn in a cooling vessel. Moreover, the device generates hot water
by heat obtained by cooling the milk, and uses the hot water in automatic washing
of the cooling vessel. It is to be noted that in the following drawing, components
denoted with the same reference numerals as those of FIGS. 1 to 4 produce the same
or similar function and effect, and detailed description thereof is therefore omitted.
A refrigeration cycle device 200 shown in FIG. 5 is provided with a refrigerant circuit
2 including a compressor 10, a condenser 21, an expansion valve 14 as a throttling
means and an evaporator 16; a second refrigerant circuit 8 including a second compressor
80, a second condenser 81, an expansion valve 84 as a throttling means and an evaporator
86; a hot water supply circuit 3 including a hot water storage tank 30; and an automatic
washing unit 9 described later.
[0083] The refrigerant circuit 2 is constituted so that the compressor 10, the condenser
21, the expansion valve 14 and the evaporator 16 are successively connected to one
another in an annular form via pipes to form a closed circuit. Specifically, a high-pressure
refrigerant pipe 40 connected to the compressor 10 on a discharge side is connected
to an inlet of the condenser 21. The condenser 21 is a refrigerant passage constituting
a part of a heat exchanger 13, and disposed so that heat exchange between the condenser
and a water passage 12 of the hot water supply circuit 3 can be performed. This heat
exchanger 13 is a heat exchanger of heat exchange between water and a refrigerant,
which performs the heat exchange between the condenser 21 and the water stored in
the hot water storage tank 30 of the hot water supply circuit 3. The heat exchanger
is constituted of the refrigerant passage as the condenser 21 and the water passage
12 of the hot water supply circuit 3. One end of the heat exchanger 13 is provided
with an inlet of the refrigerant passage of the condenser 21 and an outlet of the
water passage 12, and the other end of the heat exchanger is provided with an outlet
of the refrigerant passage of the condenser 21 and an inlet of the water passage 12.
Therefore, in the heat exchanger 13, a high-temperature high-pressure refrigerant
discharged from the compressor 10 and flowing through the condenser 21 and the water
flowing through the water passage 12 form a counterflow.
[0084] On the other hand, a refrigerant pipe 41 connected to the outlet of the condenser
21 is connected to an inlet of the expansion valve 14. A refrigerant pipe 42 connected
to an outlet of the expansion valve 14 is connected to an inlet of the evaporator
16. Moreover, an outlet of the evaporator 16 is connected to one end of a suction
pipe 45, and the other end of the suction pipe 45 is connected to the compressor 10
on a low-pressure side (a suction portion). Along the suction pipe 45 which connects
the evaporator 16 to the compressor 10 on the low-pressure side, an accumulator 17
is interposed which protects the compressor 10 from a disadvantage that a liquid refrigerant
is sucked into the compressor 10 to damage the compressor or the like. Furthermore,
at the suction pipe 45 between the evaporator 16 and the accumulator 17, a check valve
18 is disposed in which a compressor 10 side (an accumulator 17 side) is a forward
direction in order to prevent backflow of the refrigerant from a high-pressure side
of the refrigerant circuit 2 to the evaporator 16.
[0085] Moreover, a discharge temperature sensor T1 which detects a temperature of the high-temperature
high-pressure refrigerant discharged from the compressor 10 is disposed at the high-pressure
refrigerant pipe 40 of the refrigerant circuit 2.
[0086] Furthermore, carbon dioxide which is a natural refrigerant is introduced as the refrigerant
in the refrigerant circuit 2 in the same manner as in the refrigerant circuit 2 of
Embodiment 1. Moreover, since the pressure of the refrigerant circuit 2 on the high-pressure
side rises in excess of a critical pressure, the refrigerant circuit 2 constitutes
a trans-critical cycle. As a lubricant of the compressor 10, for example, mineral
oil, alkyl benzene oil, ether oil, ester oil, polyalkylene glycol (PAG), polyol ether
(POE) or the like is used.
[0087] On the other hand, the evaporator 16 is a heat exchanger which cools the object to
be cooled (the milk in the present embodiment) stored in an inner tank 70 of a cooling
vessel 7, and is formed integrally with this cooling vessel 7. Since a basic constitution
of the cooling vessel 7 is similar to that of the cooling vessel 7 of Embodiment 1
shown in FIGS. 2 to 4, detailed description thereof is omitted.
[0088] As shown in FIG. 5, the cooling vessel 7 is provided with an introduction port 7A
for introducing the object to be cooled (the milk) and a takeout port (not shown)
for taking out the object to be cooled (the milk). An introduction pipe 50 is detachably
connected to the introduction port 7A via an introduction port valve 50B. Furthermore,
a takeout pipe 52 for taking out the milk is detachably connected to the milk takeout
port via a takeout valve 52B. Moreover, the milk introduction pipe 50 is attached
to the milk introduction port 7A in an only case where the milk is introduced into
the inner tank 70 of the cooling vessel 7. In another case, the pipe is detached from
the milk introduction port 7A, and the milk introduction port 7A is hermetically closed.
Similarly, the milk takeout pipe 52 is attached to the milk takeout port in an only
case where the milk is taken out of the inner tank 70 of the cooling vessel 7. In
another case, the pipe is detached from the milk takeout port, and the milk takeout
port is hermetically closed.
[0089] Moreover, a milk temperature sensor T5 for detecting a temperature of the milk as
the object to be cooled is attached to an outer peripheral surface of the inner tank
70 of the cooling vessel 7. Furthermore, the cooling vessel 7 is provided with a stirrer
75 which stirs the milk in order to promote heat conduction during the cooling and
correctly measure the temperature with reduced temperature unevenness. The stirrer
75 is constituted of a stirring blade, a stirring motor and a shaft which connects
the blade to the motor.
[0090] On the other hand, the second refrigerant circuit 8 is constituted so that the compressor
80, the condenser 81, the expansion valve 84 and the evaporator 86 are successively
connected to one another in an annular form via pipes to form a closed circuit. Specifically,
a high-pressure refrigerant pipe 90 connected to the compressor 80 on the discharge
side is connected to an inlet of the condenser 81. The condenser 81 is a refrigerant
passage constituting a part of a heat exchanger 83, and disposed so that heat exchange
between the condenser and a second water passage 82 of the hot water supply circuit
3 can be performed. This heat exchanger 83 is a heat exchanger of heat exchange between
water and a refrigerant, which performs the heat exchange between the condenser 81
and the water stored in the hot water storage tank 30 of the hot water supply circuit
3. The heat exchanger is constituted of the refrigerant passage as the condenser 81
and the water passage 82 of the hot water supply circuit 3. One end of the heat exchanger
83 is provided with an inlet of the refrigerant passage of the condenser 81 and an
outlet of the water passage 82, and the other end of the heat exchanger is provided
with an outlet of the refrigerant passage of the condenser 81 and an inlet of the
water passage 82. Therefore, in the heat exchanger 83, a high-temperature high-pressure
refrigerant discharged from the compressor 80 and flowing through the condenser 81
and the water flowing through the water passage 82 form a counterflow.
[0091] On the other hand, a refrigerant pipe 91 connected to the outlet of the condenser
81 is connected to an inlet of the expansion valve 84. The expansion valve 84 is a
throttling means to reduce the pressure of the refrigerant which has rejected the
heat in the condenser 81, and a refrigerant pipe 92 connected to an outlet of the
expansion valve 84 is connected to an inlet of the evaporator 86. The evaporator 86
is, for example, a tube and fin type heat exchanger, and constituted of a copper tube
and a thermal conduction promoting aluminum fin disposed at this copper tube. Moreover,
in the copper tube, a channel is constituted through which the refrigerant from the
expansion valve 84 flows. In the vicinity of the evaporator 86, a fan 86F and a fan
motor 86M which drives the fan 86F are installed. The fan supplies, to the evaporator
86, atmospheric air (air) as a heat source to be subjected to heat exchange between
the air and the refrigerant flowing through the copper tube. It is to be noted that
the heat source of the evaporator 86 is not limited to the atmospheric air, and another
heat source such as water, drain, solar heat or underground water may be used.
[0092] Moreover, an outlet of the evaporator 86 is connected to one end of a suction pipe
95, and the other end of the suction pipe 95 is connected to the compressor 80 on
the low-pressure side (the suction portion). Along the suction pipe 95 which connects
the evaporator 86 to the compressor 80 on the low-pressure side, an accumulator 87
is interposed which protects the compressor 80 from a disadvantage that a liquid refrigerant
is sucked into the compressor 80 to damage the compressor or the like.
[0093] Furthermore, the high-pressure refrigerant pipe 90 of the second refrigerant circuit
8 is provided with a discharge temperature sensor T8 which detects a temperature the
high-temperature high-pressure refrigerant discharged from the compressor 80.
[0094] It is to be noted that carbon dioxide which is a natural refrigerant is introduced
as the refrigerant in the second refrigerant circuit 8 in the same manner as in the
refrigerant circuit 2. Moreover, since the pressure of the second refrigerant circuit
8 on the high-pressure side rises in excess of the critical pressure, the second refrigerant
circuit 8 constitutes a trans-critical cycle.
[0095] On the other hand, the hot water supply circuit 3 is constituted of a hot water storage
circuit 5 which receives the heat from the refrigerant flowing through the condenser
21 of the refrigerant circuit 2 or the refrigerant flowing through the condenser 81
of the second refrigerant circuit 8 to heat the water and generate the high-temperature
water and which stores the hot water in the hot water storage tank 30; a water supply
unit 32 which supplies water into the hot water storage tank 30; a hot water supply
unit 34 which supplies the hot water stored in the hot water storage tank 30 to the
automatic washing unit 9 and another hot water supply load facility; and a discharge
unit 36 described later.
[0096] The hot water storage tank 30 is a tank in which the high-temperature water generated
by the heat rejected from the condenser 21 in the heat exchanger 13 or the condenser
81 in the heat exchanger 83 is stored. The whole outer peripheral surface of the tank
is covered with an insulation material, and the tank is structured so that the stored
hot water does not easily cool.
[0097] Moreover, a lower portion of the hot water storage tank 30 is connected to a low-temperature
pipe 47 which takes out low-temperature water (the water) stored in the hot water
storage tank 30 from below the hot water storage tank 30. The low-temperature pipe
47 is connected to the inlet of the water passage 12 formed at the other end of the
heat exchanger 13 via a circulation pump 31 and a flow rate adjustment valve 35. The
circulation pump 31 circulates the water through the hot water storage circuit 5.
The circulation pump 31 of the present embodiment discharges the water taken from
the lower portion of the hot water storage tank 30 on a heat exchanger 13 side or
a heat exchanger 83 side, and circulates the water through the hot water storage circuit
5 so that a water flow in the water passage 12 or 82 of the heat exchanger 13 or 83
forms a counterflow against a refrigerant flow in the condenser 21 or 81 as described
above (circulates the water in a clockwise direction in FIG. 5). The flow rate adjustment
valve 35 is a valve unit which adjusts a flow rate of the warm water circulated through
the hot water storage circuit 5 by the circulation pump 31.
[0098] Furthermore, a three-way valve 47A is disposed on an upstream side of the circulation
pump 31 of the low-temperature pipe 47, and connected to one end of a bypass pipe
49 so that the pipe is branched from the low-temperature pipe 47 via the three-way
valve 47A. The other end of the bypass pipe 49 is connected to a middle portion of
a high-temperature pipe 48. Moreover, the three-way valve 47A can be switched to thereby
selectively switch whether the water is passed through the circulation pump 31 from
below the hot water storage tank 30, or the hot water (the water) passed through the
heat exchanger 13 or the hot water (the water) passed through the heat exchanger 83
is passed through the circulation pump 31.
[0099] In addition, a three-way valve 47B is disposed on a downstream side of the flow rate
adjustment valve 35 of the low-temperature pipe 47, and connected to a low-temperature
pipe 97 so that the pipe is branched from the low-temperature pipe 47 via the three-way
valve 47B. The low-temperature pipe 97 is connected to an inlet of the water passage
82 formed at the other end of the heat exchanger 83. The three-way valve 47B can selectively
switch whether the water passed through the flow rate adjustment valve 35 is passed
through the heat exchanger 13 or 83.
[0100] Moreover, one end of a high-temperature pipe 98 is connected to an outlet of the
water passage 82 formed at one end of the heat exchanger 83, and the other end of
the high-temperature pipe 98 is connected to a middle portion of the high-temperature
pipe 48.
[0101] On the other hand, an outlet of the water passage 12 formed at one end of the heat
exchanger 13 is connected to one end of the high-temperature pipe 48, and the other
end of the high-temperature pipe 48 is connected to an upper portion (an upper end
in the present embodiment) of the hot water storage tank 30. On a downstream side
of a connection point of this high-temperature pipe 48 to the high-temperature pipe
98, a hot water temperature sensor T2 is disposed which detects a temperature of the
high-temperature water generated by the heat rejected from the condenser 21 in the
heat exchanger 13 or the heat rejected from the condenser 81 in the heat exchanger
83 and entering the hot water storage tank 30.
[0102] Moreover, the upper portion of the hot water storage tank 30 is connected to the
high-temperature pipe 48, and provided with a high-temperature water takeout port
37 which takes the high-temperature water out of the hot water storage tank 30. The
high-temperature water takeout port 37 is connected to a high-temperature water takeout
pipe 34A of the hot water supply unit 34. The lower portion of the hot water storage
tank 30 is connected to the low-temperature pipe 47, and provided with a low-temperature
water takeout port 38 which takes the low-temperature water out of the hot water storage
tank 30. This low-temperature water takeout port 38 is connected to a low-temperature
water takeout pipe 34B of the hot water supply unit 34.
[0103] Furthermore, the high-temperature water takeout pipe 34A is connected to a washing
hot water supply pipe 60, and the high-temperature water taken out of the hot water
storage tank 30 via the high-temperature water takeout port 37 is supplied to the
automatic washing unit 9 via the washing hot water supply pipe 60. The automatic washing
unit 9 is a unit for washing the cooling vessel 7, and the high-temperature water
stored in the hot water storage tank 30 is taken from the washing hot water supply
pipe 60 for use as water for washing the cooling vessel 7. The washing hot water supply
pipe 60 is provided with a check valve 61 for preventing a disadvantage that the hot
water flowing through the washing hot water supply pipe 60 flows back to the hot water
storage tank 30; and a water supply valve (a hot water supply valve) 62 for supplying
the hot water as the washing water. It is to be noted that although not shown in FIG.
5, the washing hot water supply pipe 60 may be provided with a temperature sensor
which detects a temperature of the hot water flowing through the washing hot water
supply pipe 60; a flow rate sensor which detects an amount of the hot water; a flow
switch or the like if necessary.
[0104] In addition, it is assumed in the present embodiment that the high-temperature water
supplied from the washing hot water supply pipe 60 is used in washing the cooling
vessel 7. However, the washing hot water supply pipe 60 may be connected to, for example,
a washing unit for washing a unit such as a milking machine or a milking pipeline
other than the cooling vessel 7 (not shown: with the proviso that a part of the machine
or the pipeline is connected to the milk introduction pipe 50) to use the hot water
in washing the machine or the pipeline.
[0105] Moreover, in FIG. 5, a mixture valve 65 mixes the high-temperature water taken out
of the hot water storage tank 30 via the high-temperature water takeout pipe 34A with
the low-temperature water taken out of the hot water storage tank 30 via the low-temperature
water takeout pipe 34B or the water supplied from the water supply unit 32 via the
low-temperature water takeout pipe 34B, adjusts a temperature of the mixed water into
an optimum temperature and supplies the water to the hot water supply load facility
for use in an application other than the washing application. The mixture valve 65
is connected to each hot water supply load facility for use in an application other
than the washing application. Moreover, the hot water is supplied to the hot water
supply load facility for the application other than the washing application by operating
a hot water supply valve (not shown). The high-temperature water takeout pipe 34A
and the low-temperature water takeout pipe 34B connected to the mixture valve 65 are
provided with check valves 67 for preventing a disadvantage that the hot water taken
out of the hot water storage tank 30 from the high-temperature water takeout pipe
34A or the low-temperature water takeout pipe 34B flows back to the hot water storage
tank 30, respectively.
[0106] Furthermore, a hot water supply pipe 68 leading from the mixture valve 65 to the
hot water supply valve of each hot water supply load facility is provided with a check
valve 68B for preventing the backflow to the hot water storage tank 30; and a temperature
sensor T3 for use in hot water supply control. Moreover, a temperature of the hot
water to be supplied to the hot water supply load facility is detected by the temperature
sensor T3. It is to be noted that the hot water supply valve is, for example, a faucet
for hot water supply or the like, and the number of the valves is not limited to one.
A plurality of hot water supply valves may be disposed. The hot water supply pipe
68 may be provided with a flow rate sensor and a flow switch (both are not shown)
if necessary.
[0107] In addition, the lower portion of the hot water storage tank 30 is connected to a
water supply pipe 32A of the water supply unit 32 via a pressure reduction valve 32B.
The water supply unit 32 supplies water into the hot water storage tank 30. Water
such as city water having an amount corresponding to an amount of the hot water of
the hot water storage tank 30 to be used is supplied into the hot water storage tank
30 via the water supply pipe 32A. A water supply valve (not shown) is interposed along
this water supply pipe 32A, and the water supply valve is usually constantly brought
into an open state.
[0108] Moreover, the lower portion of the hot water storage tank 30 is connected to a discharge
pipe 69A via a discharge valve 69B. The discharge pipe discharges the hot water from
the hot water storage tank 30, when the hot water storage tank 30 is unused.
[0109] Here, the discharge unit 36 discharges the water (the hot water) from the hot water
storage tank 30, and is disposed below the high-temperature water takeout port 37
and above the low-temperature water takeout port 38. In the present embodiment, a
hot water discharge pipe 36A of the discharge unit 36 is connected to a portion of
the hot water storage tank 30 below the high-temperature water takeout port 37 and
above the low-temperature water takeout port 38 via a hot water discharge valve 36B.
Since the discharge unit 36 is disposed below the high-temperature water takeout port
37 and above the low-temperature water takeout port 38 in this manner, the hot water
taken out of the hot water storage tank 30 by the discharge unit 36 is medium-temperature
water having a temperature which is lower than that of the hot water taken from the
high-temperature water takeout port 37 and higher than the water taken from the low-temperature
water takeout port 38. Therefore, when the hot water discharge valve 36B is opened
as needed, the medium-temperature water can be discharged from the hot water storage
tank 30.
[0110] On the other hand, an outer surface of the hot water storage tank 30 is provided
with a plurality of stored hot water sensors T4 arranged at appropriate intervals
from the upper portion to the lower portion. The stored hot water sensors T4 are sensors
which detect temperatures of portions of the hot water stored in the hot water storage
tank 30 and which detect whether or not there is hot water. Since the plurality of
stored hot water sensors T4 are arranged at varied heights to detect the temperatures
of the portions in this manner, it is possible to detect the amount of the hot water
stored in the hot water storage tank 30 while grasping a temperature distribution
from the upper portion to the lower portion of the hot water storage tank 30.
[0111] It is to be noted that a capacity of the hot water storage tank 30 needs to be determined
in due consideration of an amount of the milk as the object to be cooled, introduced
into the cooling vessel 7; and an assumed hot water supply load. That is, during a
cooling operation, if the high-temperature water is taken from the lower portion of
the hot water storage tank 530 instead of the low-temperature water and the water
enters the water passage 12 of the heat exchanger 13, an amount of the heat to be
rejected from the condenser 21 remarkably decreases. As a result, a cooling capacity
and COP of the refrigerant circuit 2 deteriorate. Therefore, when the capacity of
the hot water storage tank 30 is considered, the tank should have a sufficient volume
so that the low-temperature water can constantly be taken from the lower portion of
the hot water storage tank 30, and passed through the water passage 12 of the heat
exchanger 13.
[0112] Specifically, each capacity needs to be investigated individually in accordance with
use conditions. For example, in a case where the hot water is not used simultaneously
with the cooling operation, it is preferable to use the hot water storage tank having
a capacity which equals or exceeds the maximum amount of the milk as the object to
be cooled, supposed to be introduced into the cooling vessel 7 during one cooling
operation. For example, in a case where 500 liters of the object to be cooled (the
milk) is introduced into the cooling vessel 7, it is preferable that the capacity
of the hot water storage tank 30 equals or exceeds about 500 liters. In a case where
it is assumed that the hot water is used during the cooling operation, the capacity
of the hot water storage tank 30 can be set to be smaller than the above capacity.
[0113] Moreover, the automatic washing unit 9 is constituted of a circulation washing circuit
100 constituted by successively connecting a washing circulation pump 101, a washing
pipe 102, the cooling vessel 7, the takeout valve 52B, a circulation changeover valve
104 and a washing return pipe 105; a washing water discharge passage 110 connected
to the washing return pipe 105 of the circulation washing circuit 100 via a washing
discharge valve 110B; and a washing buffer tank 115 connected to the washing return
pipe 105 of the circulation washing circuit 100.
[0114] The washing buffer tank 115 is connected to at least one or more detergent supply
pipes 116 for supplying a detergent or a germicide; a water supply pipe 117 for supplying
the washing water (the city water in the present embodiment); and the washing hot
water supply pipe 60 for supplying the hot water for washing from the hot water supply
circuit 3. The water supply pipe 117 is provided with a water supply valve 117B, and
the water supply to the buffer tank 115 for washing is controlled by the water supply
valve 117B. The detergent supply pipe 116 is provided with a detergent supply pump
(not shown) for supplying the detergent, and the other end of the detergent supply
pipe 116 is connected to a detergent vessel (not shown).
[0115] An operation of the refrigeration cycle device 200 of the present embodiment constituted
as described above will be described.
(1) Cooling Operation of Object (Milk) to be cooled
[0116] First, an operation to cool the milk as the object to be cooled during the cooling
operation will be described. The milking pipeline connected to the milking machine
(not shown) is connected to the cooling vessel 7 via the milk introduction pipe 50,
the introduction port valve 50B is opened, and the milk immediately after drawn is
introduced into the cooling vessel 7. At this time, the milk takeout valve 52B is
closed. A temperature of the milk immediately after drawn is substantially equal to
or slightly lower than a body temperature of a cow, and is specifically in a range
of about 35°C to 38°C. Then, the refrigerant circuit 2 is operated to cool and insulate
the milk for the purpose of preventing generation of bacteria and maintaining a quality
of the milk.
[0117] After starting the milking (after starting the introduction of the milk), the compressor
10 of the refrigerant circuit 2 is driven, and the stirrer 75 is simultaneously driven.
Usually, it is assumed that after a predetermined amount of milk is stored in the
cooling vessel 7, the compressor 10 is driven to start the cooling operation. However,
the cooling operation may be started simultaneously with the start of the introduction
of the milk or before the introduction of the milk as long as careful consideration
is given so as to prevent freezing and idling of the stirrer 75 is prevented.
[0118] When the compressor 10 is driven, a low-temperature low-pressure refrigerant gas
is sucked and compressed on the low-pressure side (the suction portion) of the compressor
10 from the suction pipe 45. In consequence, the refrigerant gas which has obtained
a high temperature and a high pressure enters the high-pressure refrigerant pipe 40
from the discharge side, and is discharged from the compressor 10. At this time, the
refrigerant is compressed under an appropriate supercritical pressure.
[0119] The high-temperature high-pressure refrigerant discharged from the compressor 10
enters the heat exchanger 13 from the inlet of the condenser 21 via the high-pressure
refrigerant pipe 40. Moreover, while passing through the condenser 21 of the heat
exchanger 13, the high-temperature high-pressure refrigerant gas releases the heat
to the water of the hot water storage circuit 5 flowing through the water passage
12 disposed so as to perform the heat exchange between the water and the condenser
21. In consequence, the gas obtains a low temperature. On the other hand, the water
flowing through the water passage 12 is heated by a heat radiation function of this
condenser 21, and the high-temperature water is generated.
[0120] In the present embodiment, carbon dioxide is used as the refrigerant, and the refrigerant
pressure in the condenser 21 is not less than a critical pressure. Therefore, since
condensation of the refrigerant does not occur in the condenser 21, the temperature
of the refrigerant gradually drops from the inlet toward the outlet of the condenser
21 as the heat is rejected to the water flowing through the water passage 12. On the
other hand, from the inlet to the outlet of the water passage 12 of the heat exchanger
13, the temperature of the water gradually rises as the heat is absorbed from the
refrigerant. Since the refrigerant pressure of the condenser 21 is set to be not less
than the critical pressure by use of the carbon dioxide refrigerant in this manner,
the heat exchange can highly efficiently be performed and the high-temperature water
can be generated as compared with condensation heat radiation of a conventional refrigerant
such as an HFC-based refrigerant at a constant temperature. In the heat exchanger
13, the refrigerant passage and the water passage 12 constituting the condenser 21
are arranged so as to form the counterflow as described above. Therefore, the heat
exchange between the water and the refrigerant can further efficiently be performed.
[0121] The low-temperature high-pressure refrigerant cooled by the condenser 21 exits from
the heat exchanger 13 via the outlet of the condenser 21, passes through the refrigerant
pipe 41, expands at the expansion valve 14 to obtain a low pressure and reaches the
evaporator 16 via the refrigerant pipe 42. It is to be noted that the refrigerant
at the inlet of the evaporator 16 has a two-phase mixed state in which the liquid
refrigerant is mixed with a vapor refrigerant. Moreover, when the liquid-phase refrigerant
absorbs the heat from the milk as the object to be cooled in the evaporator 16, the
refrigerant evaporates to form the vapor refrigerant. At this time, the milk is cooled
by the heat absorption.
[0122] Moreover, the refrigerant evaporated in the evaporator 16 repeats a cycle of exiting
from the evaporator 16 to enter the suction pipe 45 and being again sucked from the
low-pressure side (the suction portion) to the compressor 10 via the check valve 18
and the accumulator 17. When the above cycle is repeated, the milk is cooled by the
heat absorption of the evaporator 16. Moreover, the hot water is generated by the
heat rejected from the condenser 21.
[0123] When the milking is completed, the introduction of the milk into the cooling vessel
7 is completed. However, the above cooling operation is continued until the milk reaches
a predetermined temperature. Here, the temperature of the milk is detected by the
milk temperature sensor T5 attached to the outer peripheral surface of the inner tank
70. The predetermined temperature at which the cooling operation ends is set from
a viewpoint that the generation of the bacteria in the milk be inhibited and the quality
be maintained, and is specifically about 4°C.
[0124] Furthermore, an open degree of the expansion valve 14 is adjusted so that the temperature
of the discharged refrigerant detected by the discharge temperature sensor T1 disposed
at the high-pressure refrigerant pipe 40 of the refrigerant circuit 2 is a predetermined
temperature during the cooling operation. Specifically, when the refrigerant temperature
detected by the discharge temperature sensor T1 rises above the predetermined value,
the open degree of the expansion valve 14 is enlarged. Conversely, when the refrigerant
temperature detected by the discharge temperature sensor T1 drops below the predetermined
value, the open degree of the expansion valve 14 is reduced. In consequence, a highly
efficient operation can be performed on conditions preferable for an operation of
generating the high-temperature water suitable for the washing application.
[0125] It is to be noted that the compressor 10 during the cooling operation may have the
constant number of rotations. Alternatively, a frequency may be adjusted by an inverter
or the like. Since the number of the rotations is controlled in the same manner as
in Embodiment 1 described above, detailed description is omitted.
(2) Operation of Hot Water Supply Circuit 3 during Cooling Operation
[0126] Next, the operation of the hot water supply circuit 3 during the cooling operation
will be described. First, the three-way valve 47A is switched so that the water flows
through the circulation pump 31 from the lower portion of the hot water storage tank
30, and the three-way valve 47B is switched so that the water passed through the flow
rate adjustment valve 35 flows through the heat exchanger 13 of the refrigerant circuit
2 (the refrigerant circuit 2 for cooling the milk).
[0127] Moreover, when the above cooling operation is started, the circulation pump 31 of
the hot water supply circuit 3 is started. The low-temperature water or the water
(hereinafter referred to simply as the water) is sucked from the lower portion of
the hot water storage tank 30 to the circulation pump 31 via the low-temperature pipe
47, and pushed out to the low-temperature pipe 47 connected to the outlet of the circulation
pump 31 on the heat exchanger 13 side. In consequence, the water pushed out of the
circulation pump 31 enters the heat exchanger 13 from the inlet of the water passage
12 via the flow rate adjustment valve 35. In the heat exchanger 13, as described above,
the water flowing through the water passage 12 receives the heat from the condenser
21 by the heat exchange between the water and the refrigerant flowing through the
condenser 21, and is heated. In consequence, the high-temperature water is generated.
Moreover, the high-temperature water discharged from the heat exchanger 13 via the
outlet of the water passage 12 passes through the high-temperature pipe 48 of the
hot water storage circuit 5, and is injected into the hot water storage tank 30 from
the upper portion (the upper end) of the hot water storage tank 30. The high-temperature
water generated by the heat exchanger 13 is injected into the upper portion of the
hot water storage tank 30, and the water is taken from the lower portion of the tank.
Therefore, the high-temperature water is stored in an upper part of the tank and the
low-temperature water is stored in a lower part of the tank by use of a density difference
due to a water temperature difference.
[0128] Furthermore, the flow rate adjustment valve 35 adjusts the flow rate of the water
so that the temperature of the hot water at the outlet of the water passage 12 of
the heat exchanger 13 indicates a predetermined value. In the present embodiment,
the flow rate adjustment valve 35 is controlled based on the temperature of the hot
water at the outlet of the water passage 12 of the heat exchanger 13 detected by the
hot water temperature sensor T2. That is, when the temperature of the hot water at
the outlet of the water passage 12 detected by the hot water temperature sensor T2
is higher than the predetermined temperature, the open degree of the flow rate adjustment
valve 35 is enlarged. In consequence, an amount (the flow rate) of the water to be
circulated through the hot water storage circuit 5 can be increased.
[0129] On the other hand, when the temperature of the hot water at the outlet of the water
passage 12 detected by the hot water temperature sensor T2 is lower than the predetermined
temperature, the open degree of the flow rate adjustment valve 35 is reduced. In consequence,
the amount (the flow rate) of the water to be circulated through the hot water storage
circuit 5 can be reduced. It is to be noted that in the present embodiment, the temperature
of the hot water at the outlet of the water passage 12 is detected by the hot water
temperature sensor T2 installed at the middle portion of the high-temperature pipe
48. However, the present invention is not limited to this example. Needless to say,
the temperature of the hot water at the outlet of the water passage 12 may be detected
by a temperature sensor disposed at the outlet of the water passage 12 of the heat
exchanger 13. It is preferable to set the predetermined temperature to a temperature
suitable for an application of hot water supply (including a washing application),
specifically in a range of about 50°C to 85°C in accordance with a use application.
[0130] As described above, during the cooling operation of the refrigeration cycle device
200 of the present embodiment, when the milk immediately after drawn is introduced
into the cooling vessel 7, the milk is cooled at the predetermined temperature in
order to maintain the quality of the milk. Moreover, the high-temperature water is
generated by the heat rejected from the refrigerant circuit 2 on the high-pressure
side, and the hot water can be stored in the hot water storage tank 30.
(3) Operation during Cold Insulating Operation
[0131] In the refrigeration cycle device 200, when the temperature of the milk reaches the
predetermined value during the above cooling operation, a cold insulating operation
to insulate the milk is executed in the same manner as in the refrigeration cycle
device 1 of Embodiment 1. Since operation conditions, an operation method and the
like during the cold insulating operation are similar to those of Embodiment 1, detailed
description thereof is omitted. A function of the refrigerant circuit 2, an operation
of the hot water supply circuit 3 and the like during the cold insulating operation
are similar to those during the above cooling operation. It is to be noted that in
the refrigeration cycle device 200 of the present embodiment, even in the cooling
operation during the cold insulating operation, simultaneously with the cooling of
the milk, the hot water can be stored by effectively using discharged heat during
the cooling.
[0132] It is to be noted that since operation patterns of the cooling operation and the
cold insulating operation in a general farm are the same as described above in Embodiment
1, detailed description thereof is omitted.
(4) Washing Operation
[0133] Next, a washing operation will be described. As described above, the milk cooled
and insulated in the cooling vessel 7 as described above is taken from the takeout
port during the milk cargo collection. Specifically, the milk takeout valve 52B is
connected to the milk takeout pipe 52, the milk takeout valve 52B is opened and the
milk is taken out of the cooling vessel 7. Moreover, after the milk is taken out,
the washing operation is performed by the automatic washing unit 9 in order to keep
the inside of the cooling vessel 7 to be clean, inhibit propagation of the bacteria
and secure the quality of the milk.
[0134] Usually, the washing of the cooling vessel 7 is performed after taking the milk out
of the cooling vessel 7. Therefore, in a case where the cargo is collected every day,
the washing is performed once a day. When the cargo is collected every other day,
the washing is performed once every two days. In the present embodiment, the hot water
for washing can be supplied even for the washing of the milking machine or the milking
pipeline (not shown). However, since the milking machine and the milking pipeline
are washed every time the milking is completed, the washing is performed twice or
three times a day.
[0135] Washing steps in a case where the cooling vessel 7 is washed are basically the same
as those in a case where the milking pipeline or the like is washed. That is, a rinsing
step with the water, a rinsing step with the hot water, a washing step with a plurality
of types of detergents such as an alkaline detergent and an acid detergent and a sterilization
step with a germicide are performed. In each of such steps, the hot water or the water
is supplied, predetermined amounts of predetermined types of detergent and germicide
are supplied, then a washing liquid (a mixture liquid of the hot water or the water
and the detergent and the like) is circulated through the device (through the circulation
washing circuit 100 in a case where the cooling vessel 7 is washed) for a predetermined
time if necessary, and the washing liquid is then discharged.
[0136] Moreover, the above steps are performed in a predetermined order the necessary number
of times. For example, first the rinsing step with the water is performed. Subsequently,
another rinsing step with the hot water, an alkali washing step with the hot water
and the alkaline detergent, still another rinsing step with the hot water, an acid
washing step with the hot water and the acid detergent and a further rinsing step
with the water are performed. Subsequently, the sterilization step with the germicide
is performed.
[0137] When the milk cargo collection is completed, prior to the washing, first the milk
takeout pipe 52 is detached from the takeout valve 52B so that the washing water flows
through the washing return pipe 105 via the takeout valve 52B, and the takeout valve
52B is opened. In the rinsing step with the water, the discharge valve 110B for washing
and the circulation changeover valve 104 are closed, and the circulation pump 101
for washing is stopped. In this state, the water supply valve 117B is opened, and
the predetermined amount of the washing water is supplied to the buffer tank 115 for
washing via the water supply pipe 117. It is to be noted that it can be judged with,
for example, a floating type level switch or the like whether or not an amount of
the water in the buffer tank 115 for washing reaches a predetermined value.
[0138] Moreover, when the amount of the water in the buffer tank 115 for washing reaches
the predetermined value, the water supply valve 117B is closed, and the circulation
pump 101 is brought into an operative state. In consequence, the water passes through
the washing pipe 102 from the buffer tank 115 for washing, and is supplied into the
cooling vessel 7. To inject the water into the cooling vessel 7 from the washing pipe
102, the water is jetted from nozzles and sprayed into each portion of the cooling
vessel 7 without unevenness so that efficient washing can be performed. If necessary,
the stirrer 75 may be operated.
[0139] If the water in the buffer tank 115 for washing is used up, the operation of the
circulation pump 101 for washing is stopped, the circulation changeover valve 104
and the discharge valve 110B for washing are opened, and the rinsing water is discharged
from the washing water discharge passage 110. One rinsing step with the water has
been described above. The predetermined number of the steps are repeatedly performed
as needed.
[0140] On the other hand, the rinsing step with the hot water is basically an operation
similar to that of the above rinsing step with the water, and is different only in
that the high-temperature water is supplied instead of the water. That is, in the
rinsing step with the water, the water supply valve 117B is opened to supply the water.
However, in the rinsing step with the hot water, the hot water supply valve 62 is
opened to thereby supply the high-temperature water stored in the hot water storage
tank 30 to the buffer tank 115 for washing via the hot water supply pipe 60 for washing.
Description of another similar operation is omitted.
[0141] In the washing step with the detergent, the discharge valve 110B for washing and
the circulation changeover valve 104 are closed, and the circulation pump 101 for
washing is stopped. In this state, the water supply valve 62 is opened, and a predetermined
amount of the hot water is supplied to the buffer tank 115 for washing via the hot
water supply pipe 60 for washing. Moreover, a detergent supply pump (not shown) is
driven to supply the predetermined amount of the predetermined type of detergent to
the buffer tank 115 for washing via the detergent supply pipe 116. The type and the
amount of the supplied detergent are determined beforehand in accordance with the
steps, and the amount of the detergent is adjusted in accordance with a driving time
of the detergent supply pump (not shown).
[0142] Moreover, when the amount of the hot water (the mixture liquid of the hot water and
the detergent) in the buffer tank 115 for washing reaches a predetermined value, the
water supply valve 62 is closed, and the circulation pump 101 is brought into the
operative state. In consequence, the detergent passes through the washing pipe 102
from the buffer tank 115 for washing, and is supplied into the cooling vessel 7. To
inject the washing liquid into the cooling vessel 7 from the washing pipe 102, the
washing liquid is jetted from nozzles and sprayed into each portion of the cooling
vessel 7 without unevenness so that the efficient washing can be performed. If necessary,
the stirrer 75 may be operated.
[0143] If the washing liquid in the buffer tank 115 for washing is used up, the operation
of the circulation pump 101 for washing is stopped. The circulation changeover valve
104 and the discharge valve 110B for washing remain to be closed until the predetermined
amount of the washing liquid is stored in the cooling vessel 7. The water supply valve
62 is opened again, and the predetermined amount of the hot water is supplied into
the buffer tank 115 for washing. Subsequently, the water supply valve 62 is closed,
the circulation pump 101 is driven, and the hot water is supplied into the cooling
vessel 7. This operation is repeated. Here, the amount of the hot water supplied and
stored in the cooling vessel 7 can be known from the capacity of the buffer tank 115
and the number of the repeated operations. Therefore, in a case where the number of
the times when the hot water is stored in the buffer tank 115 is determined beforehand,
an appropriate amount can be controlled.
[0144] After the predetermined amount of the washing liquid (the mixture liquid of the hot
water and the detergent) is stored in the cooling vessel 7, the circulation changeover
valve 104 is opened, and the circulation pump 101 for washing is driven for a predetermined
time. The washing liquid from the cooling vessel 7 successively flows through the
takeout valve 52B, the circulation changeover valve 104, the washing return pipe 105,
the washing circulation pump 101 and the washing pipe 102 to return to the cooling
vessel 7, and circulates through the circulation washing circuit 100. In consequence,
dirt of the milk in the cooling vessel 7 can be removed. It is to be noted that to
inject the washing liquid into the cooling vessel 7 from the washing pipe 102, the
washing liquid is jetted from nozzles and sprayed into each portion of the cooling
vessel 7 without unevenness so that efficient washing can be performed. If necessary,
the stirrer 75 may be operated.
[0145] Moreover, after the washing liquid is circulated for a predetermined time, the circulation
pump 101 for washing is stopped, the discharge valve 110B for washing is opened, and
the washing liquid is discharged from the circulation washing circuit 100 via the
discharge passage 110 for washing.
[0146] An operation of the sterilization step is basically similar to that of the washing
step with the detergent, and is different only in that the detergent to be injected
is the germicide, the water is used instead of the hot water and a different time
for circulation or the like is set. The sterilization step is performed in accordance
with the next use time, and a germicide liquid (a mixture liquid of the germicide
and the water) is held in systems of the cooling vessel 7 and the circulation washing
circuit 100 and left to stand for a predetermined time to improve a sterilization
effect. Detailed description of an operation common to that of the rinsing step or
the washing step with the detergent is omitted.
[0147] It is to be noted that in the standby state of the cold insulating operation, the
expansion valve 14 is completely closed in order to reduce thermal losses due to the
entering refrigerant in the evaporator 16. However, during the washing operation,
especially when the washing with the hot water is performed, it is preferable to bring
the expansion valve 14 into an open state in order to avoid an abnormally high pressure
in the evaporator 16.
[0148] Moreover, in a case where a large hot water supply load is required and the supply
of the only amount of the hot water generated by cooling the milk is insufficient,
the hot water may be generated by performing the cooling operation even during the
washing operation. For example, in the sterilization step, while the germicide liquid
is held in the cooling vessel 7, the cooling operation is performed. In consequence,
a hot water supply operation (a heat pump operation) can highly efficiently be performed
using the germicide liquid as a heat source. Furthermore, if necessary, the water
can additionally be introduced as the heat source into the cooling vessel 7 to perform
the cooling operation (the hot water supply operation).
(5) Hot Water Supply Operation for Application other than Washing Application
[0149] Next, an operation of supplying the hot water to an application other than the above
washing application will be described. The hot water is supplied to a hot water supply
load for the application other than the washing application by opening the hot water
supply valve. When the hot water supply valve is opened, the high-temperature water
stored in the hot water storage tank 30 flows through the mixture valve 65 from the
upper portion of the hot water storage tank 30 via the high-temperature water takeout
pipe 34A. Moreover, the water from the water supply unit 32, or the low-temperature
water from the lower portion of the hot water storage tank 30 flows through the mixture
valve 65 via the low-temperature water takeout pipe 34B connected to the lower portion
of the hot water storage tank 30. Moreover, the mixture valve 65 mixes the high-temperature
water and the water or the low-temperature water. After the temperature is adjusted
into a predetermined temperature, the hot water is supplied to each hot water supply
load facility via the hot water supply valve.
[0150] It is to be noted that the temperature of the hot water to be supplied is detected
by the temperature sensor T3 disposed at the pipe 68 which connects the mixture valve
65 to the hot water supply valve. It is to be noted that since the water supply valve
(not shown) of the water supply unit 32 is usually constantly opened, the city water
having an amount corresponding to the amount of the hot water supplied to another
hot water supply load facility (the hot water supply load facility other than the
automatic washing unit 9) is supplied into the hot water storage tank 30 of the hot
water supply circuit 3 from the water supply pipe 32A of the water supply unit 32.
[0151] As described above, according to the refrigeration cycle device 200 of the present
embodiment, at the same time the milk as the object to be cooled is cooled, the hot
water is generated by effectively using the heat of the high-temperature side of the
refrigerant circuit 2 generated in the cooling process. Moreover, the high-temperature
water can be supplied by using the trans-critical cycle by use of the carbon dioxide
refrigerant. This hot water can be used in washing the cooling vessel 7 and the like.
Therefore, as compared with a conventional case in which the water is boiled with
a boiler or the like to supply the hot water for the washing application, energy to
be consumed can largely be reduced. Since the heat released from the high-temperature
side of the refrigerant circuit 2 to the atmospheric air can be reduced, a rise of
an ambient temperature can be inhibited.
(6) Hot Water Supply Operation by use of Second Refrigerant Circuit 8
[0152] Next, an operation of the second refrigerant circuit 8 will be described. The second
refrigerant circuit 8 is disposed so as to perform a hot water supply operation (the
heat pump operation) of absorbing the heat from a heat source such as air other than
the milk in a case where a large hot water supply load is required and the supply
of the only hot water obtained by cooling the milk is insufficient.
[0153] Since the operation of the second refrigerant circuit 8 is substantially the same
as that of the refrigerant circuit 2, detailed description thereof is omitted. The
operation is different from that of the refrigerant circuit 2 only in that the refrigerant
in the evaporator 86 absorbs the heat from the atmospheric air. That is, in the evaporator
86, the refrigerant absorbs the heat from the atmospheric air, and the heat is rejected
to the water passage 82 disposed so that the heat exchange between the water and the
condenser 81 is performed in the heat exchanger 83. In consequence, the water flowing
through the water passage 82 is heated, and the high-temperature water is generated.
[0154] During the hot water supply operation, the open degree of the expansion valve 84
is adjusted so that the temperature of the discharged refrigerant detected by the
discharge temperature sensor T8 disposed at the high-pressure refrigerant pipe 90
of the second refrigerant circuit 8 indicates a predetermined value. Specifically,
when the refrigerant temperature detected by the discharge temperature sensor T8 rises
above the predetermined value, the open degree of the expansion valve 84 is enlarged.
Conversely, when the refrigerant temperature detected by the discharge temperature
sensor T8 drops below the predetermined value, the open degree of the expansion valve
84 is reduced. In consequence, a highly efficient operation can be performed on conditions
preferable for an operation of generating the high-temperature water suitable for
the washing application.
[0155] Next, an operation of the hot water supply circuit 3 during the hot water supply
operation will be described. In this case, the three-way valve 47A is switched so
that the water flows through the circulation pump 31 from the lower portion of the
hot water storage tank 30, and the three-way valve 47B is switched so that the water
passed through the flow rate adjustment valve 35 flows through the heat exchanger
83. During the hot water supply operation, the circulation pump 31 of the hot water
supply circuit 3 is operated, and the low-temperature water or the water from the
lower portion of the hot water storage tank 30 flows through the low-temperature pipe
47, the circulation pump 31, the flow rate adjustment valve 35 and the low-temperature
pipe 97 to enter the inlet of the water passage 82 of the heat exchanger 83. In the
heat exchanger 83, as described above, the water flowing through the water passage
82 is heated by the heat exchange between the water and the refrigerant flowing through
the condenser 81 to generate the high-temperature water. Moreover, the high-temperature
water exiting from the water passage 82 of the heat exchanger 83 successively flows
through the high-temperature pipes 98 and 48, and is injected into the hot water storage
tank 30 from the upper portion of the hot water storage tank 30. The high-temperature
water is injected from the upper portion of the hot water storage tank 30, and the
low-temperature water is taken from the lower portion of the tank. Therefore, the
high-temperature water is stored in an upper part of the hot water storage tank 30
and the low-temperature water is stored in a lower part of the tank by use of a density
difference due to a water temperature difference.
[0156] Moreover, the flow rate adjustment valve 35 adjusts the flow rate of the water so
that the temperature of the hot water at the outlet of the water passage 82 of the
heat exchanger 83 indicates a predetermined value. Specifically, when the temperature
of the hot water at the outlet of the water passage 82 is higher than the predetermined
temperature, the open degree of the flow rate adjustment valve 35 is enlarged to increase
the flow rate of the water. Conversely, when the temperature of the hot water at the
outlet of the water passage 82 is lower than the predetermined temperature, the open
degree of the flow rate adjustment valve 35 is reduced to decrease the flow rate of
the water. The temperature of the hot water at the outlet of the water passage 82
is detected by the hot water temperature sensor T2 attached to the high-temperature
pipe 48. Moreover, the predetermined temperature is a temperature suitable for the
washing application or another hot water supply application. Specifically, it is preferable
to set the temperature in a range of about 50 to 85°C in accordance with a use application.
[0157] As described above, the hot water supply operation of the second refrigerant circuit
8 is performed in a case where the amount of the hot water generated by the milk cooling
operation falls short with respect to the required hot water supply load. A length
of time when the hot water supply operation is performed, that is, the amount of the
hot water to be generated is determined in accordance with the required amount of
the hot water. However, when the hot water storage tank 30 is completely filled with
the high-temperature water, the high-temperature water flows through the heat exchanger
13 from the lower portion of the hot water storage tank 30 during the cooling operation.
The cooling capacity and efficiency remarkably deteriorate, and it is difficult to
cool the milk. Therefore, during the hot water supply operation, the hot water storage
tank 30 is not completely filled with the high-temperature water, and it is necessary
to surely secure a cold water portion (a portion of water having a low temperature)
having an amount corresponding to an amount for use during the cooling operation in
the lower part of the hot water storage tank 30.
[0158] The amount of the hot water to be stored in the hot water storage tank 30 during
the hot water supply operation of the second refrigerant circuit 8 depends on conditions
on which the refrigeration cycle device 200 is used, that is, the amount (a farming
scale) of the milk, the amount of the hot water for use and the like. For example,
when the amount of the hot water is 1/5 or less of that in the hot water storage tank
30, the hot water supply operation is started by the second refrigerant circuit 8.
When the amount is 1/2 or more, the hot water supply operation of the second refrigerant
circuit 8 is stopped. Such control is considered. It is to be noted that the amount
of the hot water stored in the hot water storage tank 30 can be grasped by the stored
hot water sensors T4.
[0159] As described above, the refrigeration cycle device 200 of the present embodiment
includes the second refrigerant circuit 8. Therefore, when the required hot water
supply load cannot be covered only with the hot water generated during the cooling
of the milk, the hot water supply operation is performed using the atmospheric air
as the heat source. In consequence, the hot water can be generated to compensate for
shortage. Therefore, an auxiliary boiler or the like for the additional hot water
supply is not required. Moreover, heat pump hot water supply is highly efficiently
performed. Therefore, energy consumption is further reduced.
(7) Changeover Operation of Three-Way Valve 47A
[0160] Next, an operation of the three-way valve 47A will be described. The three-way valve
47A prevents the low-temperature water from being passed through the upper portion
of the hot water storage tank 30 to disturb thermal stratification in the hot water
storage tank 30 during the starting and stopping of the cooling operation and the
hot water supply operation. For a predetermined time TL1 after the start of the cooling
operation or the hot water supply operation, the three-way valve 47A is blocked on
a hot water storage tank 30 side, and switched so as to pass the hot water (or the
water) through the circulation pump 31 from the bypass pipe 49. In consequence, for
the predetermined time TL1 from the start of the cooling operation or the hot water
supply operation, the hot water passed through the water passage 12 of the heat exchanger
13 or the water passage 82 of the heat exchanger 83 of the second refrigerant circuit
8 does not enter the hot water storage tank 30. The hot water flows through the closed
circuit from the high-temperature pipe 48 via the bypass pipe 49, the three-way valve
47A and the circulation pump 31 to return to the water passage 12 of the heat exchanger
13 or the water passage 82 of the heat exchanger 83 of the second refrigerant circuit
8.
[0161] In addition, for a predetermined time TL2 from the start of the cooling operation
or the hot water supply operation, the open degree of the flow rate adjustment valve
35 is fixed to a predetermined open degree so as to secure a sufficient flow rate.
After elapse of the predetermined time TL2, the open degree is gradually reduced to
decrease the flow rate. Finally, the open degree is adjusted so that the hot water
temperature sensor T2 attached to the high-temperature pipe 48 indicates the predetermined
value.
[0162] After elapse of the predetermined time TL1, the three-way valve 47A is blocked on
a bypass pipe 49 side, and switched so as to pass the water through the circulation
pump 31 from the lower portion of the hot water storage tank 30. As a result, the
hot water generated by the water passage 12 of the heat exchanger 13 or the water
passage 82 of the heat exchanger 83 of the second refrigerant circuit 8 enters the
hot water storage tank 30.
[0163] As the predetermined times TL1 and TL2, a certain time may be determined beforehand.
Alternatively, the operation may be performed based on the temperature of the hot
water at the outlet of the heat exchanger 13 or the heat exchanger 83 of the second
refrigerant circuit 8, detected by the hot water temperature sensor T2. That is, at
the start of the cooling operation, the flow rate adjustment valve 35 is fixed to
the predetermined open degree. When the hot water temperature rises to a predetermined
value or more, the open degree of the flow rate adjustment valve 35 is gradually reduced.
Furthermore, when the hot water temperature rises to a second predetermined temperature,
the three-way valve 47A may be blocked on the bypass pipe 49 side, and switched so
as to pass the water through the circulation pump 31 from the lower portion of the
hot water storage tank 30.
[0164] As described above, it is possible to avoid a problem that the thermal stratification
of the hot water already stored in the hot water storage tank 30 is disturbed to lower
the temperature of the stored hot water. As a result, the thermal loss of the stored
hot water can be reduced, and the hot water can effectively be used.
[0165] Moreover, as described above, the flow rate adjustment valve 35 is fixed to the predetermined
open degree so that the sufficient flow rate can be secured for the predetermined
time TL2 after the start of the cooling operation or the hot water supply operation.
In consequence, it is possible to avoid an abnormal discharge temperature rise and
an abnormally high pressure immediately after the compressor 10 (or the compressor
80) is started.
[0166] On the other hand, even immediately after the stopping of the cooling operation or
the hot water supply operation, when a predetermined time elapses after the stopping
of the operation of the compressor 10 (or the compressor 80) or the hot water indicates
the predetermined value or less, the three-way valve 47A is blocked on the hot water
storage tank 30 side, and switched so as to pass the hot water (or the water) through
the circulation pump 31 from the bypass pipe 49. Subsequently, the circulation pump
31 is operated for a predetermined time. In consequence, the hot water passed through
the water passage 12 of the heat exchanger 13 or the water passage 82 of the heat
exchanger 83 of the second refrigerant circuit 8 does not enter the hot water storage
tank 30. The hot water flows through the closed circuit from the high-temperature
pipe 48 via the bypass pipe 49, the three-way valve 47A and the circulation pump 31
to return to the water passage 12 of the heat exchanger 13 or the water passage 82
of the heat exchanger 83 of the second refrigerant circuit 8.
[0167] Therefore, it is possible to prevent the low-temperature water from being passed
from the upper portion of the hot water storage tank 30 into the hot water storage
tank 30 to disturb the thermal stratification in the hot water storage tank 30. Moreover,
the heat exchanger 13 or the heat exchanger 83 of the second refrigerant circuit 8
can appropriately be cooled.
[0168] It is to be noted that, when the usual cooling operation or hot water supply operation
is performed except during the starting and stopping, the three-way valve 47A is blocked
on the bypass pipe 49 side, and switched so as to pass the water through the circulation
pump 31 from the lower portion of the hot water storage tank 30. When the cooling
operation or the hot water supply operation is not performed, the three-way valve
47A is blocked on the hot water storage tank 30 side, and switched so as to communicate
on the bypass pipe 49 side. When the cooling operation or the hot water supply operation
is not performed, the valve is switched to the above state. In consequence, in a case
where the high-temperature water is supplied to the washing application or the like,
it is possible to avoid a problem that the cold water entering the lower portion of
the hot water storage tank 30 from the water supply unit 32 flows through the hot
water storage circuit 5 on the heat exchanger 13 side or the side of the heat exchanger
83 of the second refrigerant circuit 8 to enter the upper portion of the hot water
storage tank 30 and lower the temperature of the hot water to be supplied.
(8) Operation of Discharge Unit 36
[0169] In addition, in the refrigeration cycle device 200, a disadvantage occurs that the
excessively large amount of the high-temperature water is stored in the hot water
storage tank 30 owing to increase of the cooling load during the cooling operation
or decrease of a hot water supply load, then the temperature of the hot water taken
from the lower portion of the hot water storage tank 30 also rises and consequently
the high-temperature water enters the heat exchanger 13.
[0170] When the high-temperature water enters the heat exchanger 13, in the condenser 21
of the heat exchanger 13, the amount of the heat to be rejected from the refrigerant
flowing through the condenser 21 to the water flowing through the water passage 12
remarkably drops or falls short. In consequence, since the refrigerant cannot be cooled
at a low temperature in the condenser 21, a problem occurs that a specific enthalpy
of the refrigerant flowing through the evaporator 16 rises, a cooling capacity of
the evaporator 16 and the efficiency of the refrigeration cycle device 200 remarkably
deteriorate and the cooling of the object to be cooled in the evaporator 16 is hindered.
[0171] To solve such a problem, according to the refrigeration cycle device 200 of the present
embodiment, in a case where the temperature of the water stored in the hot water storage
tank 30, the temperature of the water to be circulated through the heat exchanger
13 for the heat exchange between the condenser 21 and the water stored in the hot
water storage tank 30, the temperature in the condenser 21 or the temperature of the
refrigerant discharged from the condenser 21 rises to a predetermined value or more,
the discharge unit 36 discharges the water from the hot water storage tank 30.
[0172] Here, an operation of discharging the water from the hot water storage tank 30 by
the discharge unit 36 will be described. It is assumed that in the refrigeration cycle
device 200 of the present embodiment, when the temperature of the water to be circulated
through the heat exchanger 13 for the heat exchange between the condenser 21 and the
water stored in the hot water storage tank 30 rises to a predetermined value or more,
for example, 25°C to 30°C or more, the water is discharged from the hot water storage
tank 30 by the discharge unit 36. It is to be noted that the temperature at which
the water is discharged from the hot water storage tank 30 by the discharge unit 36
is not limited to the temperature of the water to be circulated through the heat exchanger
13 for the heat exchange between the condenser 21 and the water stored in the hot
water storage tank 30 as in the present embodiment. The temperature may be the temperature
of the water stored in the hot water storage tank 30, detected by the stored hot water
sensors T4, the temperature of the refrigerant in the condenser 21 of the heat exchanger
13 or the temperature of the refrigerant discharged from the condenser 21.
[0173] Moreover, it is assumed that the hot water discharge valve 36B disposed at the hot
water discharge pipe 36A of the discharge unit 36 is usually closed, and in this state
the water is not discharged from the hot water storage tank 30 via the hot water discharge
pipe 36A.
[0174] Furthermore, during the cooling operation, when the temperature (the temperature
of the water at the inlet of the water passage 12 of the heat exchanger 13) of the
water to be circulated through the heat exchanger 13 for the heat exchange between
the condenser 21 and the water stored in the hot water storage tank 30 rises to the
predetermined value or more, the hot water discharge valve 36B of the hot water discharge
pipe 36A is opened. In consequence, the medium-temperature water having a temperature
which is lower than that of the hot water taken from the high-temperature water takeout
port 37 of the hot water storage tank 30 and higher than the water taken from the
low-temperature water takeout port 38 is discharged from the hot water storage tank
30 via the hot water discharge pipe 36A.
[0175] Simultaneously with the discharge of the hot water via the hot water discharge pipe
36A, the amount of cold water corresponding the amount of the discharged hot water
is supplied into the hot water storage tank 30 from the water supply pipe 32A of the
water supply unit 32. It is to be noted that the hot water discharged from the hot
water storage tank 30 via the hot water discharge pipe 36A may be used for an appropriate
application if any.
[0176] When the hot water is discharged from the hot water storage tank 30 via the hot water
discharge pipe 36A and the amount of the cold water corresponding to the amount of
the discharged hot water is simultaneously supplied into the hot water storage tank
30 in this manner, the temperature of the hot water stored in the lower part of the
hot water storage tank 30 can be lowered. The hot water stored in the lower part of
the hot water storage tank 30 and having the lowered temperature, or the cold water
supplied into the hot water storage tank 30 by the water supply unit 32 can be supplied
to the heat exchanger 13.
[0177] In consequence, in the heat exchanger 13, it is possible to secure the amount of
the heat rejected from the refrigerant, required for the evaporator 16 to maintain
the cooling function. That is, in the heat exchanger 13, the heat of the refrigerant
flowing through the condenser 21 is sufficiently released to the water flowing through
the water passage 12, and the temperature of the refrigerant can be lowered. Therefore,
the cooling capacity of the evaporator 16 can be maintained and the object to be cooled
can securely be cooled.
(Embodiment 3)
[0178] It has been described in the above embodiments (Embodiments 1 and 2) that a cooling
vessel 7 having a horizontally disposed elliptic columnar shape is used as a vessel
to cool and insulate an object to be cooled. However, as described above, the shape
of the cooling vessel may be another shape. Therefore, in the present embodiment,
a case where a cooling vessel having a columnar shape is used will be described. It
is to be noted that the present embodiment is different from the above embodiments
only in the shape of the cooling vessel. Therefore, an only different constitution
will be described. Since another constitution is the same as or similar to that of
the above embodiments, description thereof is omitted.
[0179] FIG. 6 is a schematic constitution diagram of an evaporator 316 of the present embodiment
as viewed from a bottom surface of an inner tank 370. A cooling vessel 307 of the
present embodiment has a vertically disposed columnar shape, a bottom surface 370B
(the other plate material) of the inner tank 370 substantially has a circular shape.
An outer plate 376 (one plate material) secured to the bottom surface 370B substantially
has a circular shape.
[0180] As shown in FIG. 6, the whole periphery of a peripheral portion of the outer plate
376 is secured to the bottom surface 370B of the inner tank 370 by seam welding, a
sealed refrigerant passage space 377 is constituted between the plate materials (between
the bottom surface 370B of the inner tank 370 and the outer plate 376), and this space
is used as a refrigerant channel of the evaporator 316.
[0181] Moreover, a portion of the outer plate 376 other than the peripheral portion is provided
with a plurality of secured inner portions 378 secured to the bottom surface 370B
of the inner tank 370 at predetermined intervals. Specifically, the whole periphery
of the peripheral portion of the outer plate 376 is secured to the bottom surface
of the inner tank 370 by the seam welding, and the portion other than the peripheral
portion is secured with spot at predetermined intervals in a checkered form or a zigzag
form by spot welding (portions secured by the spot welding are the secured inner portions
378).
[0182] Furthermore, a plurality of refrigerant inlet tubes 316A and refrigerant outlet tubes
316B are attached to the refrigerant passage space 377 (a refrigerant channel of the
evaporator 316) formed between the bottom surface 370B of the inner tank 370 and the
outer plate 376. Moreover, as shown in FIG. 6, one end of each of the plurality of
refrigerant inlet tubes 316A communicates with the refrigerant passage space 377 in
the center of the refrigerant passage space 377, and one end of each refrigerant outlet
tube 316B communicates with the refrigerant passage space 377 in the peripheral portion
of the refrigerant passage space 377.
[0183] The refrigerant inlet tubes 316A have an arrangement concentric with the outer plate
376 substantially having a circular shape, and are connected to the center of the
refrigerant passage space 377 at substantially equal intervals. The refrigerant outlet
tubes 316B have an arrangement concentric with the outer plate 376 substantially having
a circular shape, and are connected to the peripheral portion of the refrigerant passage
space 377 at substantially equal intervals.
[0184] On the other hand, the other end of the refrigerant inlet tube 316A is connected
to a refrigerant pipe 42 so that the refrigerant from the refrigerant pipe 42 is branched
to flow through the refrigerant passage space 377. Moreover, the other end of the
refrigerant outlet tube 316B is connected to a suction pipe 45 so that the refrigerants
from the refrigerant outlet tubes 316B are combined.
[0185] Moreover, even in the present embodiment, in the same manner as in the above embodiments,
the inner tank 370 has a plate thickness of 2 mm, and the outer plate 376 has a plate
thickness of 1 mm. Spot-welded portions (the secured inner portion 78) have a diameter
of 6 mm, and a spot pitch of 18.5 mm. The refrigerant inlet tubes 316A and the refrigerant
outlet tubes 316B have an outer diameter of φ6.35 mm (1/4 inch), and the refrigerant
inlet tubes 316A and the refrigerant outlet tubes 316B have a plate thickness of 1.0
mm.
[0186] As described above in Embodiment 1, the number of the refrigerant inlet tubes 316A
or the refrigerant outlet tubes 316B, and an area of the outer plate 376 can be calculated
from Equations (1) and (2) described above. IN the present embodiment, the cooling
vessel 307 having a rated capacity of 1000 liters is used, and the number of milking
times per cargo collection is two. Therefore, NT (the number of the refrigerant inlet
tubes 316A or the refrigerant outlet tubes 316B of the evaporator 316) calculated
from Equation (1) is 3.25, and four refrigerant inlet tubes 316A and four refrigerant
outlet tubes 316B are used. Since A (the area of the outer plate 376) calculated from
Equation (2) is 1, an area of the outer plate 376 is set to 1.13 m
2 of the present embodiment.
[0187] In the present embodiment, the evaporator 316 has one path, four refrigerant inlet
tubes 316A and four refrigerant outlet tubes 316B. Therefore, the refrigerant from
the refrigerant pipe 42 is branched into four flows, flows through the refrigerant
inlet tubes 316A, and enters the refrigerant passage (the center of the refrigerant
passage space 77) of the evaporator 316 from each refrigerant inlet tube 316A. Moreover,
the refrigerants entering the center of the evaporator 316 from the refrigerant inlet
tubes 316A are once combined in the evaporator 316, and flows from the center in a
circumferential direction. In this process, the refrigerant absorbs heat by heat exchange
between the refrigerant and the object to be cooled. and evaporates. The evaporated
refrigerant is branched into four flows to enter the refrigerant outlet tubes 316B,
flows out of the evaporator 316 via the refrigerant outlet tubes 316B, and is combined
to flow through the suction pipe 45.
[0188] As described above in detail, in the evaporator 316 of the present embodiment, the
refrigerant inlet tubes 316A communicate with the refrigerant passage space 377 in
the center of the refrigerant passage space 377. Moreover, the refrigerant outlet
tubes 316B communicate with the refrigerant passage space 377 in the peripheral portion
of the refrigerant passage space 377. Therefore, the refrigerant entering the evaporator
316 from the vicinity of the center flows so as to spread in the circumferential direction.
It is therefore possible to inhibit a disadvantage that pressure losses increase as
the refrigerant evaporates.
[0189] That is, as the refrigerant evaporates, a specific volume increases. Therefore, in
a case where the area of the refrigerant passage is set to be equal from a refrigerant
inlet to an outlet of the evaporator 316, as the refrigerant evaporates, the pressure
losses increase. However, as in the present embodiment, the refrigerant inlet tubes
316A are arranged in the center of the refrigerant passage space 377, and the refrigerant
outlet tubes 316B are arranged in the peripheral portion of the refrigerant passage
space 377. In consequence, a refrigerant passage area of the evaporator 316 is smallest
at the inlet of the evaporator 316, gradually increases toward the outlet, and is
maximized at the outlet of the evaporator 316. Therefore, such pressure losses can
further be reduced.
[0190] Furthermore, according to such a structure, a branching property of the refrigerant
improves. Therefore, stagnation of the refrigerant in the evaporator 316 can be prevented,
and improvement of a thermal performance can be expected.
[0191] It is to be noted that it is assumed in each embodiment that the heat exchanger of
the present invention is used as the evaporator. However, the present invention is
not limited to this example. The heat exchanger may be used as a condenser. When the
heat exchanger of the present invention is used as the condenser, a heat exchange
capability of the condenser can be enhanced.
[0192] Moreover, as the invention that can be grasped from the above description, in addition
to the inventions described in claims, the following is considered. That is, the first
invention is also directed to a heat exchanger characterized in that after the whole
periphery of the peripheral portion of the one plate material is secured to the other
plate material, a pressure is applied between the plate materials to thereby swell
and form the refrigerant passage space between the plate materials.
[0193] The present invention is usable in not only the device which cools and insulates
the milk immediately after drawn as in the above embodiments but also another industrial
field such as a device related to processing of food and the like or an automatic
dispenser in which cooling and cold storage are demanded.