[0001] The present invention relates to a refrigerant evaporator for evaporating a refrigerant
of a refrigerant cycle apparatus.
[0002] A refrigerant evaporator is, for example, described in Japanese Unexamined Patent
Application Publication No.
2001-324290 (
USP6,339,937). In the described refrigerant evaporator, a core as a heat exchanging part includes
a plurality of tubes extending in an up and down direction. The tubes are stacked
in a horizontal direction (e.g., a core width direction) and arranged in two rows
with respect to a flow direction of air. An upper tank is disposed at upper ends of
the tubes of each row, and a lower tank is disposed at lower ends of the tubes of
each row. Further, separators are provided in the upper tanks.
[0003] In the described refrigerant evaporator, a refrigerant inlet is disposed at an end
of the upper tank that is in communication with the tubes in a downstream row (hereinafter,
air-downstream row) with respect to the air flow, and a refrigerant outlet is disposed
at an end of the other upper tank that is in communication with the tubes in an upstream
row (hereinafter, air-upstream row) with respect to the air flow. The refrigerant
inlet and the refrigerant outlet are disposed on the same side of the refrigerant
evaporator with respect to the core width direction. Thus, a refrigerant flows through
the tubes of the air-downstream row while making U-turn through the lower tank that
is in communication with the tubes of the air-downstream row, and then flows through
the tubes of the air-upstream row while making U-turn through the other lower tank
that is in communication with the tubes of the air-upstream row. Namely, the evaporator
is configured such that two U-turn paths of the refrigerant are provided. The refrigerant
is discharged from the refrigerant outlet. The refrigerant is evaporated while flowing
through the tubes by exchanging heat with the air flowing outside of the tubes.
[0004] In a refrigerant evaporator, it has been recently required to reduce a thickness
of a core in order to reduce an installation space and a weight. However, in a refrigerant
evaporator in which tubes are stacked in plural rows with respect to an air flow,
in a case where a thickness of a core, that is, a dimension of the core with respect
to an air flow direction is reduced, for example, to equal to or smaller than 50 mm,
heat capacity is reduced. In a case where such a refrigerant evaporator is employed
to a refrigerant cycle apparatus, liquid refrigerant is likely to stagnate in the
core due to the lack of heat capacity when an operation of a refrigerant compressor
of the refrigerant cycle apparatus is transferred from an ON state to an OFF state.
Also, it is difficult to clear the stagnation of the liquid refrigerant even after
the refrigerant compressor switched to the ON state.
[0005] The present invention is made in view of the foregoing matter, and it is an object
of the present invention to provide a refrigerant evaporator, capable of reducing
stagnation of liquid refrigerant therein.
[0006] According to an aspect of the present invention, a refrigerant evaporator includes
a core, a first header tank, a second header tank, a refrigerant inlet, a refrigerant
outlet. The core includes a plurality of tubes. The tubes are arranged in a core width
direction and at least in two rows including a first row and a second row, the first
row being located downstream of the second row with respect to a flow direction of
an external fluid. The first header tank includes a first upper tank portion and a
first lower tank portion. The first upper tank portion is in communication with upper
ends of the tubes of the first row, and the first lower tank portion is in communication
with lower ends of the tubes of the first row. The second header tank includes a second
upper tank portion and a second lower tank portion. The second upper tank portion
is in communication with upper ends of the tubes of the second row, and the second
lower tank portion is in communication with lower ends of the tubes of the second
row. The refrigerant inlet is disposed at an end of the first header tank. The refrigerant
outlet disposed at an end of the second header tank. The end of the second header
tank and the end of the first header tank are on the same side with respect to the
core width direction. A first separation member is disposed in the first header tank
such that a first upward path through which the refrigerant flows in an upward direction
and a first downward path through which the refrigerant flows in a downward direction
are provided by the tubes of the first row. The first upward path and the first downward
path are adjacent to each other with respect to the core width direction. A second
separation member is disposed in the second header tank such that a second upward
path through which the refrigerant flows in the upward direction and a second downward
path through which the refrigerant flows in the downward direction are provided by
the tubes of the second row. The second upward path and the second downward path are
adjacent to each other with respect to the core width direction. The core has a thickness
equal to or less than 50 mm with respect to the flow direction of the external fluid.
The core has a width equal to or greater than 220 mm with respect to the core width
direction. The first upward path is located further than the first downward path with
respect to the refrigerant inlet, and a width of the first upward path with respect
to the core width direction is equal to or less than 95 mm.
[0007] In the above construction, since the width of the core is equal to or greater than
220 mm, an increase in pressure loss is slight and a decrease in heat exchange efficiency
is suppressed. Although heat capacity is reduced due to the reduction of the thickness
of the core, since the core has the width equal to or greater than 220 mm and the
first upward path, which is the furthest from the refrigerant inlet in the paths provided
by the tubes of the first row, has the width equal to or less than 95 mm, stagnation
of the liquid refrigerant around a lower portion of the first upward path is easily
cleared.
[0008] Other objects, features and advantages of the present invention will become more
apparent from the following detailed description made with reference to the accompanying
drawings, in which like parts are designated by like reference numbers and in which:
Fig. 1 is a perspective view of a refrigerant evaporator according to an embodiment
of the present invention;
Fig. 2 is an enlarged view of a part of a core of the refrigerant evaporator according
to the embodiment;
Fig. 3 is a schematic view for showing a general flow of a refrigerant inside of the
refrigerant evaporator according to the embodiment;
Fig. 4 is a schematic view of an evaporator as a comparative example for showing a
change of surface temperature of tubes in an air-downstream row as a time elapses
since a refrigerant compressor is switched to an OFF state;
Fig. 5 is a schematic view of the evaporator as the comparative example for showing
a change of surface temperature of the tubes in the air-downstream row as a time elapses
since the compressor is switched to an ON state;
Fig. 6 is a graph showing a relationship between a width of a third path of an air-downstream
row and efficiency of heat exchange of the evaporator according to the embodiment
of the present invention;
Fig. 7 is a graph showing a relationship between a fin height and efficiency of heat
exchange of the evaporator according to the embodiment of the present invention;
Fig. 8 is a graph showing a relationship between a core thickness and an increase
in temperature of the evaporators during a transitional period of ON and OFF states
of a refrigerant compressor based on a fin thermister;
Fig. 9 is a graph showing a relationship between a core thickness and an increase
in temperature of the evaporators during the transitional period of the ON and OFF
states of the refrigerant compressor based on an air thermister;
Fig. 10 is a chart showing a sensory evaluation relative to a variation in temperature
of air at an air outlet and a variation in temperature of air downstream of an evaporator;
Fig. 11 is a schematic view of an evaporator and a general flow of a refrigerant therein
according to another embodiment of the present invention;
Fig. 12 is a schematic view of an evaporator and a general flow of a refrigerant therein
according to further another embodiment of the present invention; and
Fig. 13 is a schematic view of an evaporator and a general flow of a refrigerant therein
according to still another embodiment of the present invention.
[0009] Exemplary embodiments of the present invention will now be described with reference
to the accompanying drawings.
[0010] Figs. 1 to 3 show an embodiment of the present invention. In the present embodiment,
a refrigerant evaporator 1 (hereinafter, simply referred to as the evaporator 1) is,
for example, employed to a refrigerant cycle apparatus for a vehicular air conditioner.
In the refrigerant cycle apparatus, a refrigerant is compressed into a high temperature,
high pressure refrigerant by a refrigerant compressor. The high temperature, high
pressure refrigerant is cooled through a radiator, and is decompressed into a low
temperature, low pressure refrigerant by a decompressing device. The low temperature,
low pressure refrigerant is evaporated in the evaporator 1. In the present embodiment,
the refrigerant is, for example, R134a. The radiator serves as a condenser for condensing
the refrigerant discharged from the refrigerant compressor.
[0011] The evaporator 1 generally includes a core 2 as a heat exchanging part, an upper
header tank 3, a lower header tank 4, and the like. The core 2 includes a plurality
of tubes 20, a plurality of outer fins 26 and side plates 28. The tubes 20 and the
outer fins 26 are alternately staked in a substantially horizontal direction. The
side plates 28 are disposed along the outer fins 26 that are stacked in outermost
layers. The outer fins 26 serve as heat exchanging fins. Hereinafter, a direction
in which the tubes 20 and the outer fins 26 are stacked is referred to as a stacking
direction. Also, a width W of the core 2 is measured in the stacking direction. Thus,
the stacking direction is also referred to as a core width direction.
[0012] The tubes 20 are generally flat pipe members. For example, the tubes 20 are made
by bending thin aluminum belt-like plate members. Although not illustrated, inner
fins are provided inside of the tubes 20, and are joined to inner surfaces of the
tubes 20.
[0013] In the core 2, the tubes 20 extend in an up and down direction. The tubes 20 are
arranged in two rows, such as a first tube row 21 (e.g., air-downstream row) and a
second tube row 22 (e.g., air-upstream row), with respect to a flow of air as an external
fluid. The first tube row is disposed downstream of the second tube row 22 with respect
to the air flow. In other words, the core 2 is disposed such that the first tube row
21 and the second tube row 22 are overlapped with each other with respect to an air
flow direction. Hereinafter, the tubes 20 in the first tube row 21 are also referred
to as tubes 20A, and the tubes 20 in the second tube row 22 are also referred to as
tubes 208.
[0014] The outer fins 26 are, for example, corrugate fins that are made by shaping thin
aluminum belt-like plate members into a corrugate shape. The outer fins 26 are formed
with louvers on the surfaces for increasing efficiency of heat exchange. The outer
fins 26 are brazed with outer surfaces of the tubs 20.
[0015] The side plates 28 serve as reinforcement members of the core 2. The side plates
28 are, for example, formed by pressing aluminum flat plate members. Ends of each
side plate 28 with respect to a longitudinal direction are flat, and a main portion
of each side plate 28 other than the ends has a substantially U-shape in a cross-section
defined perpendicular to a longitudinal direction of the side plate 28. The side plate
28 is brazed to the outer fin 26 such that an opening of the U-shape faces outside
of the core 2 with respect to the stacking direction.
[0016] The upper header tank 3 generally includes a tank header, a plate header and a cap.
The tank header and the plate header are joined to each other with respect to a longitudinal
direction of the tubes 20. The plate header is disposed adjacent to the tubes 20,
and the tank header is disposed opposite to the tubes 20 with respect to the plate
header.
[0017] Each of the tank header and the plate header is formed into a predetermined shape
from an aluminum plate member such as by pressing, for example. The tank header has
two continuous semi-circular shape or two continuous U-shape in a cross-section defined
perpendicular to its longitudinal direction. Also, the plate header has two continuous
semi-circular shape or two continuous U-shape in a cross-section defined perpendicular
to its longitudinal direction. The tank header and the plate header are engaged and
joined to each other such that a first upper-tank inner space and a second upper-tank
inner space are provided between them. The first upper-tank inner space is provided
downstream of the second upper-tank inner space with respect to the air flow direction.
[0018] The cap is disposed to cover an open end of a generally tubular body constructed
of the tank header and the plate header. The cap is, for example, made by shaping
an aluminum flat plate member such as by pressing. The cap is brazed with the end
of the tubular body with respect to a longitudinal direction of the tubular body.
[0019] Further, the upper header tank 3 is provided with two separators 33, 34. The separator
33 is disposed in the first upper-tank inner space such that the first upper-tank
inner space is separated into two chambers with respect to the longitudinal direction
of the upper header tank 3, such as in a right and left direction of Fig. 3. The separator
34 is disposed in the second upper-tank inner space such that the second upper-tank
inner space is separated into two chambers with respect to the longitudinal direction
of the upper header tank 3, such as in the right and left direction of Fig. 3. The
separators 33, 34 are brazed inside of the upper header tank 3. One of the chambers
of the first upper-tank inner space (e.g., first upper chamber), which is located
on a right side of the separator 33 in Fig. 3, is in communication with one of the
chambers of the second upper-tank inner space (e,g., second upper chamber), which
is located on a right side of the separator 34 in Fig. 3, through first communication
holes 36.
[0020] The lower header tank 4 has a generally similar shape as the upper header tank 3.
The lower header tank 4 includes a tank header, a plate header and caps. The tank
header and the plate header form a generally tubular body. The caps are disposed at
open ends of the tubular body with respect to a longitudinal direction of the lower
header tank 4.
[0021] The lower header tank 4 forms a first lower-tank inner space and a second lower-tank
inner space with respect to the air flow direction. The first lower-tank inner space
is provided downstream of the second lower-tank inner space with respect to the air
flow direction. Separators 43, 44 are brazed inside of the lower header tank 4. The
separator 43 is provided in the first lower-tank inner space such that the first lower-tank
inner space is separated into two chambers with respect to the longitudinal direction
of the lower header tank 4. The separator 44 is provided in the second lower-tank
inner space such that the second lower-tank inner space is separated into two chambers
with respect to the longitudinal direction of the lower header tank 4. One of the
chambers of the first lower-tank inner space, which is located on the right side of
the separator 43 in Fig. 3, is in communication with one of the chambers of the second
lower-tank inner space, which is located on the right side of the separator 44 in
Fig. 3, through second communication holes 46.
[0022] Each of the upper and lower header tanks 3, 4 has insertion openings on a wall that
faces the core 2. Ends of the tubes 20 and the ends of the side plates 28 are inserted
to the insertion openings and brazed with the upper and lower header tanks 3, 4. Thus,
the tubes 20 are in communication with the upper and lower header tanks 3, 4, and
the ends of the side plates 28 are supported by the upper and lower header tanks 3,
4.
[0023] The upper header tank 3 includes a first upper tank 31 and a second upper tank 32.
The first upper tank 31 is disposed downstream of the second upper tank 32 with respect
to the air flow direction. The first upper tank 31 provides the first upper-tank inner
space therein, and the second upper tank 32 provides the second upper-tank inner space
therein.
[0024] The lower header tank 4 provides a first lower tank 41 and a second lower tank 42.
The first lower tank 41 is disposed downstream of the second lower tank 42 with respect
to the air flow direction. The first lower tank 41 provides the first lower-tank inner
space therein, and the second lower tank 42 provides the second lower-tank inner space
therein.
[0025] The upper ends of the tubes 20A of the first tube row 21 are connected to the first
upper tank 31. The lower ends of the tubes 20A of the first tube row 21 are connected
to the first lower tank 41. The first upper tank 31 and the first lower tank 41 constitute
a first header tank 11 for distributing and collecting the refrigerant into and from
the tubes 20A of the first tube row 21.
[0026] The upper ends of the tubes 20B of the second tube row 22 are connected to the second
upper tank 32. The lower ends of the tubes 20B of the second tube row 22 are connected
to the second lower tank 42. The second upper tank 32 and the second lower tank 42
constitute a second header tank 12 for distributing and collecting the refrigerant
into and from the tubes 20B of the second tube row 22.
[0027] A connector 5 is brazed with an end of the upper header tank 3, such as a left end
in Fig. 3. The connector 5 has a refrigerant inlet 51 as a refrigerant introducing
portion for introducing the refrigerant into the evaporator 1 and a refrigerant outlet
52 as a refrigerant discharging portion for discharging the refrigerant from the evaporator
1. The refrigerant inlet 51 is in communication with an end (e.g., left end in Fig.
3) of the first lower tank 41 through a side passage 210. The refrigerant outlet 52
is in communication with an end (e.g., left end in Fig. 3) of the second upper tank
32.
[0028] That is, the first header tank 11 is provided with the refrigerant inlet 51 for introducing
the refrigerant into the evaporator 1, and the second header tank 12 is provided with
the refrigerant outlet 52 for discharging the refrigerant from the evaporator 1. Further,
the refrigerant inlet 51 and the refrigerant outlet 52 are disposed on the ends of
the first and second header tanks 11, 12, the ends being on the same side of the evaporator
1with respect to the stacking direction, that is, the core width direction.
[0029] In the present embodiment, the refrigerant flows in the chamber of the first lower
tank 41 from the refrigerant inlet 51 through the side passage 210, the chamber being
on the left side of the separator 43 in Fig. 3. The refrigerant flows through the
tubes 20A of the first tube row 21 in a generally S-shape or meandering manner while
changing directions in the up and down direction. Further, the refrigerant is introduced
into the tubes 20B of the second tube row 21 through the right chambers of the upper
header tank 3. The refrigerant flows through the tubes 20B of the second tube row
22 in a generally S-shape or meandering manner while changing directions in the up
and down direction. Then, the refrigerant is discharged from the refrigerant outlet
52. While flowing in the evaporator 1 in the above manner, the refrigerant is evaporated
and thus the air is cooled by latent heat of evaporation.
[0030] The flow of the refrigerant in the evaporator 1 is described more in detail with
reference to Fig. 3. The first tube row 21 is separated into three refrigerant paths
by means of the separators 33, 43. Also, the second tube row 22 is separated into
three refrigerant paths by means of the separators 34, 44.
[0031] As shown in Fig. 3, the refrigerant, which has been introduced in the first lower
tank 41 through the side passage 210, passes through a first path 211 of the first
tube row 21 in an upward direction as shown by an arrow P1. The refrigerant turns
through the first upper tank 31 and flows into a second path 212 of the first tube
row 21 in a downward direction as shown by an arrow P2. A part of the refrigerant,
which has passed through the second path 212, turns through the first lower tank 41
and flows into a third path 213 of the first tube row 21 in the upward direction as
shown by an arrow P3. The remaining refrigerant, which has passed through the second
path 212, is introduced into the second lower tank 42 from the first lower tank 41
through the second communication holes 46 as shown by an arrow P4, and flows into
a first path 221 of the second tube row 22 in the upward direction as shown by an
arrow P5.
[0032] The refrigerant, which has passed through the third path 213 of the first tube row
21 in the upward direction, is introduced into the second upper tank 32 from the first
upper tank 31 through the first communication holes 36 as shown by an arrow P6, and
is merged with the refrigerant that has passed through the first path 221 of the second
tube row 22 in the upward direction. As such, the third path 213 of the first tube
row 21 and the first path 221 of the second tube row 22 are configured such that the
refrigerant flows therein in parallel with each other.
[0033] The refrigerant, which has merged in the second upper tank 32, flows into a second
path 222 of the second tube row 22 in the downward direction as shown by an arrow
P7. Further, the refrigerant turns through the second lower tank 42 and flows into
a third path 223 of the second tube row 22 in the upward direction as shown by an
arrow P8. Thereafter, the refrigerant is discharged from the second upper tank 32.
[0034] As described in the above, the separators 33, 43 are respectively disposed in the
first upper and lower tanks 31, 41 such that the first path 211 of the first tube
row 21 provides a refrigerant upward current, the second path 212, which is adjacent
to the first path 211, provides a refrigerant downward current, and the third path
213, which is adjacent to the second path 212, provides a refrigerant upward current.
The separators 33, 43 serve as a first separation member.
[0035] On the other hand, the separators 34, 44 are respectively disposed in the second
upper and lower tanks 32, 42 such that the first path 221 of the second tube row 22
provides a refrigerant upward current, the second path 222, which is adjacent to the
first path 221, provides a refrigerant downward current, and the third path 223, which
is adjacent to the second path 222, provides a refrigerant upward current. The separators
34, 44 serve as a second separation member.
[0036] The third path 213 is in communication with the right chamber (e.g., first upper
chamber) of the first upper tank 31, and the first path 221 is in communication with
the right chamber (e.g., second upper chamber) of the second upper tank 32. The first
communication holes 36 are disposed at a connecting portion between the right chamber
of the first upper tank 31 and the right chamber of the second upper tank 32, as first
communication portions. The third path 213 is in communication with the right chamber
of the first lower tank 41, and the first path 221 of the second lower tank 42 is
in communication with the right chamber of the second lower tank 42. The second communication
holes 46 are disposed at a connecting portion between the right chamber of the first
lower tank 41 and the right chamber of the second lower tank 42, as second communication
portions.
[0037] In the present embodiment, a thickness D of the core 2 with respect to the air flow
direction is equal to or less than 50 mm, and a width W of the core 2 with respect
to the stacking direction, that is, in the longitudinal direction of the header tanks
3, 4, is equal to or greater than 220 mm. For example, the thickness D is 38 mm. Further,
the third path 213 of the first tube row 21, which is the furthest path in the first
tube row 21 from the refrigerant inlet 51, is configured such that the refrigerant
flows in the upward direction. In addition, a width L1 of the third path 213 with
respect to the stacking direction is equal to or less than 95 mm. The third path 213
of the first tube row 21 serves as a first furthest section in the core 2.
[0038] Also, the first path 221 of the second tube row 22, which is the furthest path in
the second tube row 22 from the refrigerant outlet 52, is configured such that the
refrigerant flows in the upward direction. In addition, a width L2 of the first path
221 with respect to the stacking direction is equal to the width L1 of the third path
213. The first path 221 of the second tube row 22 serves as a second furthest section
in the core 2.
[0039] In the above structure, since the third path 213 provides the upward refrigerant
current and the width L1 of the third path 213 is equal to or less than 95 mm, stagnation
of the refrigerant in the core 2 is reduced.
[0040] In an evaporator in which a refrigerant inlet and a refrigerant outlet are located
at the same side with respect to a stacking direction of tubes, a refrigerant is likely
to be excessively heated (super heated) in a third path of a second tube row, which
is close to the refrigerant outlet. On the other hand, a liquid refrigerant is likely
to be easily stagnated in a lower portion of a third path of the first tube row, which
is the furthest portion in the core from the refrigerant inlet and outlet and where
the air which has been cooled through the second tube row passes.
[0041] An evaporator having a conventional refrigerant flow pattern as a comparative example
is employed to a refrigerant cycle apparatus, and a change of surface temperature
of tubes in a first tube row (air-downstream row) when an operation of a refrigerant
compressor is switched is examined. Fig. 4 shows the change of surface temperature
as a time elapses since the refrigerant compressor is switched to OFF. Fig. 5 shows
the change of temperature as a time elapses since the refrigerant compressor is switched
to ON.
[0042] As shown in Fig. 4, after the compressor is switched to OFF, the surface temperature
of the tubes in the air-downstream row gradually increases. However, a low temperature
area remains in a lower portion of a second path, which is the furthest section in
a core. That is, it is realized that stagnation of the liquid refrigerant occurs in
the low temperature area.
[0043] As shown in Fig. 5, after the compressor is switched to ON and a refrigerant supply
begun, the refrigerant is supplied into a near portion of the core 2 while urging
the stagnated liquid refrigerant toward a further end with respect to the longitudinal
direction of the header tank.
[0044] In an initial stage of the refrigerant supply, the refrigerant is mainly in a gas
phase and the specific gravity of the gas refrigerant is small. Therefore, it is difficult
to introduce the refrigerant into the tubes while entirely sweeping the liquid refrigerant.
In a case where the thickness of the core is reduced, for example, equal to or less
than 50 mm, the liquid refrigerant is likely to stagnate in the furthest path of the
core from the refrigerant inlet due to the lack of heat capacity when the refrigerant
compressor is switched to OFF. Further, it is difficult to clear the stagnated liquid
refrigerant even after the refrigerant compressor is restarted. Also, the stagnation
of the liquid refrigerant causes an increase in temperature during the transitional
period of the ON and OFF of the refrigerant compressor.
[0045] As show in Fig. 5, it is realized that the gas refrigerant smoothly flows in a region
within a width of 95 mm in the furthest path while urging the liquid refrigerant upward
immediately after the refrigerant supply begun.
[0046] In the present embodiment, since the width W of the core 2 is equal to or greater
than 220 mm, an increase in pressure loss is slight and a decrease in efficiency of
heat exchange is easily suppressed. Although heat capacity is reduced due to the decrease
in the thickness D of the core 2, such as equal to or smaller than 50 mm, since the
width W of the core 2 is equal to or greater than 220 mm and the width L1 of the third
path 213 of the first tube row 21 is equal to or less than 95 mm, the liquid refrigerant,
which is stagnated in the lower portion of the third path 213, is smoothly introduced
upward when the refrigerant supply is restarted. As such, the stagnation of the refrigerant
is easily solved.
[0047] In general, in a cooling cycle apparatus of a vehicle air conditioner, a thermister
is used as a temperature detecting device in order to reduce frost of the evaporator
due to excess decrease in the temperature of the evaporator. For example, refrigerant
supply is controlled in a manner that when the temperature of the evaporator detected
by the thermister is excessively decreased, the refrigerant supply is stopped, and
when the temperature of the evaporator increases to a predetermined level, the refrigerant
supply is restarted. As examples of the thermister, a fin thermister and an air thermister
are generally used. The fin thermister is interposed between the fins to directly
contact the fin or tube and detects the temperature in a direct manner. The air thermister
is disposed to detect the temperature of air after heat exchange in the evaporator.
[0048] In a case where the liquid refrigerant is stagnated in the core due to repetition
of the ON and OFF of the compressor, it is difficult to clear the stagnation of the
liquid refrigerant even when the refrigerant supply is stopped. In such a case, a
region of the core where the refrigerant is not stagnated is increased in the temperature
due to the air although the detected temperature of the fin thermister will not increase.
As a result, the temperature of the core is likely to be increased entirely. In a
case where the air thermister is used, if frost is generated and is grown due to evaporation
of the stagnated liquid refrigerant, a region in which air is difficult to pass is
increased in the core. Therefore, it is difficult to detect the temperature of the
core. As a result, it is difficult to detect the frost.
[0049] On the other hand, in the core 2 of the present embodiment, since the stagnation
of the liquid refrigerant is easily cleared, temperature distribution (transitional
temperature difference) during the transitional period between ON and OFF of the refrigerant
compressor is reduced. Thus, when the evaporator 1 of the present embodiment is employed
to a vehicular air conditioner, air conditioning comfort of a passenger improves.
Also, the frost of the evaporator 1 is reduced, and hence a cooling operation improves.
[0050] In an evaporator in which a thickness of a core with respect to the air flow direction
is equal to or less than 50 mm, pressure loss is likely to be relatively increased.
On the other hand, in the present embodiment, the chamber of the first upper tank
31, which is in communication with the third path 213 of the first tube row 21, is
in communication with the chamber of the second upper tank 32, which is in communication
with the first path 221 of the second tube row 22, through the first communication
holes 36. Also, the chamber of the first lower tank 41, which is in communication
with the third path 213 of the first tube row 21, is in communication with the first
path 221 of the second tube row 22, through the second communication holes 46. As
such, the refrigerant flows through the third path 213 of the first tube row 21 and
the first path 221 of the second tube row 22 in the upward direction and in parallel
with each other. Therefore, even when the thickness D of the core 2 is equal to or
less than 50 mm, pressure loss of the refrigerant is reduced.
[0051] In a case where the core 2 has only two rows of the tubes, the width W of the core
2 can be at least 220 mm and at most 350 mm (220 mm ≤ W ≤ 350 mm), and the width L1
of the third path 213 can be at least 50 mm and at most 95 mm (50 mm ≤ L1 ≤ 95 mm).
[0052] As shown in Fig. 6, when the width L1 is in a range between 50 mm and 110 mm, heat
exchanging performance is maintained equal to or more than 95 % relative to the maximum
performance. Thus, by setting the width L1 in the range between 50 mm and 95 mm in
the evaporator in which the width W of the core 2 is in the range between 220 mm and
350 mm, the stagnation of the refrigerant is reduced and the heat exchanging performance
is improved.
[0053] With regard to the size of the communication holes 36, 46, each of the communication
holes 36, 46 has an equivalent diameter d that is at least 0.55 mm and at most 3 mm
(0.55 mm ≤ d ≤ 3 mm). In the case where the equivalent diameter d of each communication
hole 36, 46 is equal to or greater than 0.55 mm, clogging is reduced. In the case
where the equivalent diameter d of each communication hole 36, 46 is equal to or less
than 3 mm, resistance to pressure is sufficiently maintained.
[0054] In a case where a total opening area (e.g., total cross-sectional area) of the first
communication holes 36 is greater than a total opening area (e.g., total cross-sectional
area) of the second communication holes 46, the refrigerant is more introduced to
the third path 213 of the first tube row 21 than to the first path 221 of the second
tube row 22. In this case, therefore, temperature distribution is improved.
[0055] In a case where the total opening area of the first communication holes 36 is smaller
than a total opening area of the second communication holes 46, the refrigerant is
more introduced to the first path 221 of the second tube row 22 than to the third
path 213 of the first tube row 21. In this case, therefore, the efficiency of heat
exchange improves.
[0056] In the above example, the width L1 of the third path 213 of the first tube row 21
is equal to the width L2 of the first path 221 of the second tube row 22. Alternatively,
the width L1 of the third path 213 can be smaller than the width L2 of the first path
221 (L1 ≤ L2). In this case, since the amount of refrigerant passing through the first
path 221 of the second tube row 22 is greater than the amount of refrigerant passing
through the third path 213 of the first tube row 21. Because the degree of heat exchange
in the second tube row 22 is larger than that of the first tube row 21, the efficiency
of heat exchange is improved.
[0057] As another example, the width L1 of the third path 213 can be larger than the width
L2 of the first path 221 (L1 ≥ L2). In this case, areas where the temperature distribution
is deteriorated are complemented between the first tube row 21 and the second tube
row 22. In general, the liquid refrigerant is more distributed to a further position
than a near position due to the inertial force when being introduced into tubes in
the upward direction from a chamber of a lower tank. For example, when the refrigerant
is introduced into the third path 213 of the first tube row 21, the liquid refrigerant
is more introduced to the further tubes 20A, which are further from the second path
222, than to the near tubes 20A, which are near to the second path 222. Also, the
liquid refrigerant easily drops to a near position due to the gravity when being introduced
into tubes in the downward direction from a chamber of an upper tank. For example,
when the liquid refrigerant is introduced into the second path 222 from the first
path 221, the liquid refrigerant is more introduced to the near tubes 20B, which are
near to the first path 221, than to the further tubes 20B, which are further from
the first path 221. As such, in the case where the width L2 is smaller than the width
L1, a portion of the third path 213 where the liquid refrigerant is less introduced
is overlapped with a portion of the second path 222 where the liquid refrigerant is
more introduced. As such, uneven distribution of the liquid refrigerant is complemented
between the first tube row 21 and the second tube row 22.
[0058] In the present embodiment, the second tube row 22 provides the three refrigerant
paths 221, 222, 223. The first and third paths 221, 223 provide the refrigerant upward
currents and the second path 222 provides the refrigerant downward current.
[0059] In an evaporator, an effect of the pressure loss of the refrigerant is increased
as a distance from a refrigerant outlet is reduced. Therefore, it is preferable that
the refrigerant that has finished the heat exchange exists close to the refrigerant
outlet 52 in view of the performance. Since the refrigerant outlet 52 is located at
the end of the second upper tank 32, the third path 223 of the second tube row 22,
which is the last path, is configured to provide the refrigerant upward current. Since
the first path 221, which is the furthest path from the refrigerant outlet 52, also
provides the refrigerant upward current, the second path 222 between the first path
221 and the third path 223 is configured to provide the refrigerant downward current.
Accordingly, the second tube row 22 is configured to have the three paths 221, 222,
223.
[0060] For example, the width L1 of the third path 213 of the first tube row 21 and the
width L2 of the first path 221 of the second tube row 22 are set such that the sum
of the widths L1 and L2 and the width W of the core 2 satisfy a relationship of 0.24
x W ≤ L1 + L2 ≤ 0.36 W.
[0061] Under a representative condition in summer, the quality of vapor (dryness) of the
refrigerant flowing into the third path 213 of the first tube row 21 and the first
path 221 of the second tube row 22 is approximately 0.6, and the specific volume of
the refrigerant is approximately 0.043. Further, the quality of vapor of the refrigerant
flowing out of the third path 213 of the first tube row 21 and the first path 221
of the second tube row 22 is approximately 0.75, and the specific volume of the refrigerant
is approximately 0.055. On the other hand, the specific volume of the refrigerant
at the refrigerant outlet 52 is approximately 0.080.
[0062] As such, the average of the specific volume in the third path 213 of the first tube
row 21 and the first path 221 of the second tube row 22 is 0.049, and the average
of the specific volume in the second path 222 and the third path 223 of the second
tube row 22 is 0.0675. The second and third paths 222, 223 provide two refrigerant
paths and has the relationship of 0.049 : 0.0675 x 2 = 1: 2.76 with respect to the
core width direction. Based on this relationship, the sum of the width L1 and the
width L2 and the width W of the core 2 satisfy a relationship of L1 + L2 = (1/2,76)
x W ≈ 0.36 x W.
[0063] Under the representative condition in winter, the average of the specific volume
in the third path 213 of the first tube row 21 and the first path 221 of the second
tube row 22 is 0.03. The average of the specific volume in the second and third paths
222, 223 of the second tube row 22 is 0.0625, As such, the sum of the width L1 and
the width L2 and the width W satisfy a relationship of L1 + L2 = (1/4.17) x W ≈ 0.24
x W.
[0064] Accordingly, the sum of the width L1 and the width L2 can be set to satisfy a relationship
of 0.24 x W ≤ L1 + L2 ≤ 0.36 x W, relative to the width W of the core 2.
[0065] For example, a dimension FH (Fig. 2) of the outer fin 26 with respect to the core
width direction is at least 3 mm and at most 7 mm (3 mm ≤ FH ≤ 7 mm), and a dimension
TH (Fig. 2) of the tube 20 with respect to the core width direction is at least 1.1
mm and at most 2.3 mm (1.1 mm ≤ TH ≤ 2.3 mm). Hereinafter, the dimension FH is referred
to as the fin height FH, and the dimension TH is referred to as the tube height TH.
[0066] Fig. 7 shows the performance when the fin height FH and the tube height TH are varied
in the core 2 having the thickness of 38 mm. In Fig. 7, the performance of a first
example core having the thickness of 58 mm, which is an ordinary thickness, is defined
as a reference performance. In a second example core in which only the thickness of
the core is modified to 38 mm relative to the first example core, 92 % of the reference
performance is provided.
[0067] As shown in Fig. 7, when the fin height FH is in the range between 3 mm and 7 mm
and the tube height TH is in the range between 1.1 mm and 2.3 mm, the performance
of the core 2 exceeds the performance of the second example core. In Fig. 7, FP represents
a pitch of the outer fins 26, TWT represents a wall thickness of the tube 20, and
IFT represents a wall thickness of the inner fin.
[0068] Figs. 8 and 9 show the relationship between the core thickness D and an increase
in temperature during the transitional period, that is, between ON and OFF of the
refrigerant compressor. Fig. 8 shows the evaluation result in a refrigerant cycle
apparatus in which a fin thermister is attached to the outer fin 26 and the operation
(i.e., on and off) of the compressor is switched based on a temperature of a core
outer surface detected by the fin thermister, Fig. 9 shows the evaluation result in
a refrigerant cycle apparatus in which an air thermister (i.e., evaporator downstream
thermister) is disposed at a position downstream of the evaporator with respect to
the air flow and the operation of the compressor is switched based on a temperature
of the air detected by the air thermister.
[0069] In Figs. 8 and 9, lines E1 and E2 show the results of the evaporator 1 of the present
embodiment, and lines C1, C2 show the results of an evaporator as a comparative example.
Also, the lines E1 and C1 show the result of an intermediate load condition of the
refrigerant cycle apparatus, and the lines E2 and C2 show the result of a high load
condition of the refrigerant cycle apparatus, in which a load is higher than that
in the intermediate load condition.
[0070] As shown in Fig. 8, in a vehicular air conditioner having the fin thermister-type
refrigerant cycle apparatus in which the evaporator 1 of the present embodiment is
employed, the increase in temperature satisfies a first target level TL1 when the
core thickness D is equal to or greater than 12 mm. Also, the increase in temperature
satisfies a second target level TL2 when the core thickness D is equal to or greater
than 20 mm. Further, the increase in temperature satisfies a third target level TL3
when the core thickness D is equal to or greater than 37 mm. Here, the first target
level TL1 is, for example, a level that is required in the latest vehicle model. The
second target level TL2 is a level in which a person hardly feels a variation in temperature
in a sensory evaluation. The third target level TL3 is a level in which a person does
not feel the variation in temperature in the sensory evaluation.
[0071] As shown in Fig. 10, the second target level TL2 corresponds to a case where a variation
in temperature of air at an air outlet in a passenger compartment is equal to or less
than 5 degrees Celsius. In this case, a variation in temperature of air discharged
from the evaporator needs to be equal to or less than 7 degrees Celsius. The third
target level TL3 corresponds to a case where the variation in temperature of air at
the air outlet in the passenger compartment is equal to or less than 3 degrees Celsius.
In this case, a variation in temperature of air discharged from the evaporator needs
to be equal to or less than 5 degrees Celsius.
[0072] That is, in the fin thermister-type apparatus, the evaporator 1 having the core thickness
D in the range between 12 mm and 50 mm satisfies the first target level TL1 at least.
The evaporator 1 having the core thickness D in the range between 20 mm and 50 mm
reduces the variation in temperature to a level where a person hardly feels the change
of temperature of air blown from the air outlet. Further, the evaporator 1 having
the core thickness D in the range between 37 mm and 50 mm reduces the variation in
temperature to a level where a person does not feel the change of temperature of air
blown from the air outlet.
[0073] On the other hand, with regard to the evaporator of the comparative example, the
core thickness D needs to be greater than approximately 53 mm so as to satisfy the
first target level TL1 at least.
[0074] As shown in Fig. 9, in an air conditioner having the air thermister-type refrigerant
cycle apparatus in which the evaporator 1 of the present embodiment is employed, the
increase in temperature satisfies the first target level TL1, which exemplarily corresponds
to a level required in a next vehicle model, when the core thickness D is equal to
or greater than 22 mm. The increase in temperature satisfies the second target level
TL2 when the core thickness D is equal to or greater than 31 mm. The increase in temperature
satisfies the third target level TL3 when the core thickness D is equal to or greater
than 48 mm.
[0075] On the other hand, with regard to the evaporator of the comparative example, the
core thickness D needs to be increased greater than approximately 58 mm so as to satisfy
the first target level TL1 at least.
[0076] That is, in the air thermister-type apparatus, the evaporator 1 having the core thickness
D in the range between 22 mm and 50 mm satisfies the first target level TL1 at least.
The evaporator 1 having the core thickness D in the range between 31 mm and 50 mm
reduces the variation in temperature to a level where a person hardly feels the change
of temperature of air blown from the air outlet. Further, the evaporator 1 having
the core thickness D in the range between 48 mm and 50 mm reduces the variation in
temperature to a level where a person does not feet the change of temperature of air
blown from the air outlet.
[0077] In the evaporator 1 of the present embodiment, in a case where a total cross-sectional
area (passage area) of the third path 213 of the first tube row 21 is set smaller
than a total cross-sectional area (passage area) of the first lower tank 41, the stagnation
of the liquid refrigerant is further reduced.
[0078] On the other hand, in a case where the total cross-sectional area (passage area)
of the third path 213 of the first tube row 21 is set greater than the total cross-sectional
area (passage area) of the first lower tank 41, the performance of the heat exchange
is improved.
(Other embodiments)
[0079] In the above embodiment, the refrigerant inlet 51 is in communication with the end
of the first lower tank 41 through the side passage 210, and the refrigerant outlet
52 is in communication with the end of the second upper tank 32. The refrigerant inlet
51 and the refrigerant outlet 52 are located on the same end of the evaporator 1 with
respect to the core width direction. However, the arrangement of the refrigerant inlet
51 and the refrigerant outlet 52 is not limited to the above arrangement.
[0080] The refrigerant inlet 51 can be provided to be in communication with the first header
tank 11, and the refrigerant outlet 52 can be provided to be in communication with
the second header tank 12 as long as the refrigerant inlet 51 and the refrigerant
outlet 52 are located on the same end of the evaporator 1 with respect to the core
width direction.
[0081] For example, as shown in Fig. 11, the refrigerant inlet 51 can be provided to be
directly in communication with the first lower tank 41 of the first header tank 11,
and the refrigerant outlet 52 can be provided to be directly in communication with
the second upper tank 32 of the second header tank 12. Also in this case, the refrigerant
inlet 51 and the refrigerant outlet 52 are provided on the same end of the evaporator
1 with respect to the core width direction.
[0082] In the above embodiment, the third path 213 of the first tube row 21 and the first
path 221 of the second tube row 22 are configured to provide the parallel upward currents.
However, the flow pattern of the refrigerant in the third path 213 and the first path
221 is not limited to the above pattern as long as the first furthest path of the
first tube row 21 provides the refrigerant upward current. Also, the number of paths
in each of the first and second tube rows 21, 22 is not limited to three.
[0083] In the above embodiment, the core 2 has two rows of the tubes 20 with respect to
the air flow direction. However, the number of rows of the tubes 20 is not limited
to two rows. For example, the core 2 can have three or more rows of the tubes 20.
[0084] The present invention is effectively employed to the refrigerant evaporator having
the core in which the first tube row 21 is located on a downstream-most side of the
core 2, the second tube row 22 is located on an upstream-most side of the core 2,
and the first tube row 21 and the second tube row 22 are overlapped with each other
with respect to the air flow direction.
[0085] The first communication portion and the second communication portion can be constructed
of any structures, other than the first communication holes 36 and the second communication
holes 46, respectively.
[0086] For example, as shown in Fig. 12, the first communication portion can be constructed
of the first communication holes 36, and the second communication portion can be constructed
of a second communication member 462, such as a pipe, defining a second communication
passage 362 therein, in place of the second communication holes 46.
[0087] As another example, as shown in Fig. 13, the first communication portion can be constructed
of a first communication member 461, such as a pipe, defining a first communication
passage 361 therein, in place of the first communication holes 36. Also in this case,
the second communication portion can be constructed of the second communication member
462, similar to the example shown in Fig. 12. Alternatively, the second communication
portion can be constructed of the second communication holes 46, similar to the embodiment
shown in Fig. 3.
[0088] In the above embodiment, the outer fins 26 are provided between the tubes 20 and
are joined to the adjacent tubes 20. However, the structure of the core 2 is not limited
to the above structure.
[0089] For example, the core 2 can be a finless core without having the outer fins 26 between
the tubes 20. As another example, the core 2 can be a finless core that have projections
between the tubes 20, in place of the outer fins 26, and the projections are, for
example, made of cutting and moving portions of the tubes 20. As further another example,
the core 2 can be constructed of the tubes 20 and outer fins, each of which is in
contact with the tube 20 on one side. In these cores 2, because condensation generated
on outer surfaces of the core 2 is effectively discharged, the temperature of the
core 2 is properly detected. As such, effective response is provided.
[0090] The refrigerant is not limited to the R134a, but may be any other substances. In
a case where the refrigerant is other than the R134a, the evaporator 1 provides the
similar effects as described above. In the case where the refrigerant is the R134a,
the above described effects are effectively provided.
[0091] In the above embodiment, the evaporator 1 is exemplarily employed to the refrigerant
cycle of the vehicular air conditioner. However, the evaporator 1 can be employed
to a refrigerant cycle apparatus for any other purposes.
[0092] Additional advantages and modifications will readily occur to those skilled in the
art. The invention in its broader term is therefore not limited to the specific details,
representative apparatus, and illustrative examples shown and described.
1. A refrigerant evaporator for performing heat exchange between a refrigerant and an
external fluid, the refrigerant evaporator comprising:
a core (2) including a plurality of tubes (20, 20A, 20B), the tubes (20, 20A, 20B)
arranged in a core width direction and at least in two rows including a first row
(21) and a second row (22), the first row (21) being located downstream of the second
row (22) with respect to a flow direction of the external fluid;
a first header tank (11) including a first upper tank portion (31) and a first lower
tank portion (41), the first upper tank portion (31) being in communication with upper
ends of the tubes (20A) of the first row (21), the first lower tank portion (41) being
in communication with lower ends of the tubes (20A) of the first row (21);
a second header tank (12) including a second upper tank portion (32) and a second
lower tank portion (42), the second upper tank portion (32) being in communication
with upper ends of the tubes (20B) of the second row (22), the second lower tank portion
(32) being in communication with lower ends of the tubes (20B) of the second row (22);
a refrigerant inlet (51) disposed at an end of the first header tank (11);
a refrigerant outlet (52) disposed at an end of the second header tank (12), the end
of the second header tank (12) and the end of the first header tank (11) being on
a same side with respect to the core width direction;
a first separation member (33, 43) disposed in the first header tank (11) such that
a first upward path (213) through which the refrigerant flows in an upward direction
and a first downward path (212) through which the refrigerant flows in a downward
direction are provided by the tubes (20A) of the first row (21), the first upward
path (213) and the first downward path (212) being adjacent to each other with respect
to the core width direction; and
a second separation member (34, 44) disposed in the second header tank (12) such that
a second upward path (221) through which the refrigerant flows in the upward direction
and a second downward path (222) through which the refrigerant flows in the downward
direction are provided by the tubes (20B) of the second row (22), the second upward
path (221) and the second downward path (222) being adjacent to each other with respect
to the core width direction, wherein
a thickness (D) of the core (2) with respect to the flow direction of the external
fluid is equal to or less than 50 mm,
a width (W) of the core (2) with respect to the core width direction is equal to or
greater than 220 mm,
the first upward path (213) is located further than the first downward path (212)
with respect to the refrigerant inlet (51), and
a width (L1) of the first upward path (213) with respect to the core width direction
is equal to or less than 95 mm.
2. The refrigerant evaporator according to claim 1, wherein
the second upward path (221) is located further than the second downward path (222)
with respect to the refrigerant outlet (52),
the first upper tank portion (31) includes a first upper chamber that is in communication
with the first upward path (213),
the first lower tank portion (41) includes a first lower chamber that is in communication
with the first upward path (213),
the second upper tank portion (32) includes a second upper chamber that is in communication
with the second upward path (221), and
the second lower tank portion (42) includes a second lower chamber that is in communication
with the second upward path (221),
the refrigerant evaporator further comprising:
a first communication portion (36) configured to allow communication between the first
upper chamber and the second upper chamber; and
a second communication portion (46) configured to allow communication between the
first lower chamber and the second lower chamber.
3. The refrigerant evaporator according to claim 2, wherein
the tubes (20) are arranged only in the first row (21) and the second row (22),
the width (W) of the core is at least 220 mm and at most 350 mm, and
the width (L1) of the first upward path (213) is at least 50 mm and at most 95 mm.
4. The refrigerant evaporator according to claim 3, wherein
the first communication portion (36) is provided by a first communication member (362)
defining a first communication passage (361) therein, and
the second communication portion is provided by a second communication member (462)
defining a second communication passage (461) therein.
5. The refrigerant evaporator according to claim 3, wherein
the first upper tank portion (31) and the second upper tank portion (32) are disposed
adjacent to each other with respect to the flow direction of the external fluid,
the first lower tank portion (41) and the second lower tank portion (42) are disposed
adjacent to each other with respect to the flow direction of the external fluid,
the first communication portion (36) defines a first communication opening (36) between
the first upper tank portion (31) and the second upper tank portion (32), and
the second communication portion (46) defines a second communication opening (46)
between the first lower tank portion (32) and the second lower tank portion (42).
6. The refrigerant evaporator according to claim 5, wherein
each of the first communication opening (36) and the second communication opening
(46) has an equivalent diameter that is at least 0.55 mm and at most 3 mm.
7. The refrigerant evaporator according to any one of claims 3 to 6, wherein
the first communication portion (36) provides a passage area greater than that of
the second communication portion (46).
8. The refrigerant evaporator according to any one of claims 3 to 6, wherein
the first communication portion (36) provides a passage area smaller than that of
the second communication portion (46).
9. The refrigerant evaporator according any one of claims 3 to 8, wherein
the second upward path (221) has a width (L2) that is equal to or greater than the
width (L1) of the first upward path (213) with respect to the core width direction.
10. The refrigerant evaporator according to any one of claims 3 to 8, wherein
the second upward path (221) has a width (L2) that is equal to or less than the width
(L1) of the first upward path (213) with respect to the core width direction.
11. The refrigerant evaporator according to any one of claims 3 to 10, wherein
the second separation member (46) is disposed in the second header tank (12) such
that the tubes (20B) of the second row (22) provide the second upward path (221),
the second downward path (222) and a third upward path (223) through which the refrigerant
flows in the upstream direction, and
the third upward path (223) is located adjacent to the refrigerant outlet (52), the
second upward path (221) is located furthest from the refrigerant outlet (52) and
the second downward path (222) is located between the second upward path (221) and
the third upward path (223).
12. The refrigerant evaporator according to claim 11, wherein
when the width of the first upward path (213) is defined as L1, a width of the second
upward path (221) with respect to the core width direction is defined as L2, and the
width of the core (2) is defined as W, a sum of the width of the first upward path
(213) and the width of the second upward path (221) satisfy a relationship of 0.24
x W ≤ L1 + L2 ≤ 0.36 x W.
13. The refrigerant evaporator according to claim 11 or 12, wherein
the core (2) further includes outer fins (26) between the adjacent tubes (20, 20A,
20B),
a dimension (FH) of each fin (26) with respect to the core width direction is at least
3 mm and at most 7 mm, and
a dimension (TH) of each tube (20, 20A, 20B) with respect to the core width direction
is at least 1.1 mm and at most 2.3 mm.
14. The refrigerant evaporator according to any one of claims 1 to 13 for being employed
in a refrigerant cycle apparatus having a compressor whose operation is controlled
based on a temperature of an outer surface of the core (2), wherein the thickness
of the core (2) is at least 12 mm and at most 50 mm.
15. The refrigerant evaporator according to any one of claims 1 to 13 for being employed
in a refrigerant cycle apparatus having a compressor whose operation is controlled
based on a temperature of an outer surface of the core (2), wherein the thickness
of the core (2) is at least 20 mm and at most 50 mm.
16. The refrigerant evaporator according to any one of claims 1 to 13 for being employed
in a refrigerant cycle apparatus having a compressor whose operation is controlled
based on a temperature of an outer surface of the core (2), wherein the thickness
of the core (2) is at least 37 mm and at most 50 mm.
17. The refrigerant evaporator according to any one of claims 1 to 13 for being employed
in a refrigerant cycle apparatus having a compressor whose operation is controlled
based on a temperature of air downstream of the core (2), wherein the thickness of
the core (2) is at least 22 mm and at most 50 mm.
18. The refrigerant evaporator according to any one of claims 1 to 13 for being employed
in a refrigerant cycle apparatus having a compressor whose operation is controlled
based on a temperature of air downstream of the core (2), wherein the thickness of
the core (2) is at least 31 mm and at most 50 mm.
19. The refrigerant evaporator according to any one of claims 1 to 18, wherein a total
passage area of the first upward path (213) is smaller than a passage area of the
first lower tank portion (32).
20. The refrigerant evaporator according to any one of claims 1 to 18, wherein a total
passage area of the first upward path (213) is greater than a passage area of the
first lower tank portion (32).
21. The refrigerant evaporator according to any one of claims 1 to 12 and 13 to 20, wherein
the core (2) is a finless-type without having outer fins between the tubes (20, 20A,
20B).
22. The refrigerant evaporator according to any one of claims 1 to 20, wherein the core
(2) includes fins (26) between the adjacent tubes (20, 20A, 20B), and each of the
fins (26) is in contact with one of the adjacent tubes (20, 20A, 20B).