TECHNICAL FIELD
[0001] The present disclosure relates to a refrigeration cycle apparatus.
BACKGROUND ART
[0002] There is known a refrigeration cycle apparatus which includes a supercooler for supercooling
refrigerant condensed in a condenser (for example, see
Japanese Patent Laying-Open No. 2018-091502 (PTL 1)). The supercooler includes a plurality of refrigerant flow paths through
which the refrigerant flows. In the supercooler, the refrigerant flowing inside the
plurality of refrigerant flow paths is supercooled by heat exchange with a heat medium
(a cold source) flowing outside the plurality of refrigerant flow paths.
CITATION LIST
PATENT LITERATURE
SUMMARY OF INVENTION
TECHNICAL PROBLEM
[0004] As the refrigerant flows through the supercooler, a saturation temperature of the
refrigerant decreases due to a pressure loss of the refrigerant. As a result, when
the degree of supercooling of the refrigerant flowing into the supercooler is small,
the refrigerant is converted into gas-liquid two-phase refrigerant as it flows through
the supercooler.
[0005] Since the pressure loss of the gas-liquid two-phase refrigerant is greater than the
pressure loss of the liquid-phase refrigerant, the saturation temperature of the gas-liquid
two-phase refrigerant is likely to decrease lower than the saturation temperature
of the liquid-phase refrigerant. Therefore, when the refrigerant is converted into
the gas-liquid two-phase refrigerant as it flows through the supercooler, the temperature
difference between the gas-liquid two-phase refrigerant and the heat medium (the cold
source) decreases toward the downstream side of the plurality of refrigerant flow
paths. In this case, the supercooler cannot supercool the refrigerant, and the refrigerant
flows out from the supercooler as the gas-liquid two-phase refrigerant. Thus, as compared
with the case where the liquid-phase refrigerant having a degree of supercooling flows
through the expansion valve, the flow rate of the refrigerant expanded by the expansion
valve is reduced, which deteriorates the capacity of the refrigeration cycle apparatus.
[0006] A main object of the present disclosure is to provide a refrigeration cycle apparatus
which prevents the capacity thereof from being deteriorated by the conversion of refrigerant
into gas-liquid two-phase refrigerant in a supercooler.
SOLUTION TO PROBLEM
[0007] The refrigeration cycle apparatus according to the present disclosure includes a
refrigerant circuit which includes a compressor, a condenser, a supercooler, an expansion
valve, and an evaporator, and circulates refrigerant in the order of the compressor,
the condenser, the supercooler, the expansion valve, and the evaporator. The supercooler
includes a plurality of refrigerant flow paths through which refrigerant flows. The
plurality of refrigerant flow paths includes a plurality of first refrigerant flow
paths disposed at the most upstream side of the refrigerant circuit among the plurality
of refrigerant flow paths, and a plurality of second refrigerant flow paths through
which the refrigerant that has flowed through each of the plurality of first refrigerant
flow paths flows. The total flow path cross-sectional area of the plurality of first
refrigerant flow paths is greater than the total flow path cross-sectional area of
the plurality of second refrigerant flow paths.
ADVANTAGEOUS EFFECTS OF INVENTION
[0008] According to the present disclosure, it is possible to provide a refrigeration cycle
apparatus which prevents the capacity thereof from being deteriorated by the conversion
of refrigerant into gas-liquid two-phase refrigerant in a supercooler.
BRIEF DESCRIPTION OF DRAWINGS
[0009]
Fig. 1 is a block diagram illustrating a refrigeration cycle apparatus according to
a first embodiment;
Fig. 2 is a diagram illustrating an example supercooler of the refrigeration cycle
apparatus according to the first embodiment;
Fig. 3 is a graph illustrating a change in the temperature of refrigerant flowing
from a refrigerant inflow portion into a refrigerant outflow portion and a change
in the saturation temperature of the refrigerant in the supercooler according to the
first embodiment;
Fig. 4 is a block diagram illustrating a modification of the refrigeration cycle apparatus
according to the first embodiment;
Fig. 5 is a block diagram illustrating another modification of the refrigeration cycle
apparatus according to the first embodiment;
Fig. 6 is a block diagram illustrating yet another modification of the refrigeration
cycle apparatus according to the first embodiment;
Fig. 7 is a block diagram illustrating a modification of the supercooler according
to the first embodiment;
Fig. 8 is a block diagram illustrating a refrigeration cycle apparatus according to
a second embodiment;
Fig. 9 is a block diagram illustrating a modification of the refrigeration cycle apparatus
according to the second embodiment;
Fig. 10 is a graph illustrating a change in the temperature of the refrigerant flowing
from a refrigerant inflow portion into a refrigerant outflow portion and a change
in the saturation temperature of the refrigerant in a supercooler according to a comparative
example.
DESCRIPTION OF EMBODIMENTS
[0010] Hereinafter, embodiments of the present invention will now be described with reference
to the accompanying drawings. In the following drawings, the same or equivalent portions
will be denoted by the same reference numerals, and the description thereof will not
be repeated.
First Embodiment
<Configuration of Refrigeration Cycle Apparatus>
[0011] As illustrated in Fig. 1, a refrigeration cycle apparatus 100 according to a first
embodiment includes a refrigerant circuit which includes a compressor 1, a condenser
2, a receiver 3, a supercooler 4, an expansion valve 5, and an evaporator 6, and circulates
refrigerant. The refrigerant flows through the refrigerant circuit in the order of
the compressor 1, the condenser 2, the receiver 3, the supercooler 4, the expansion
valve 5, and the evaporator 6.
[0012] The compressor 1 sucks in the refrigerant evaporated by the evaporator 6, compresses
the refrigerant, and discharges the compressed refrigerant. The compressor 1 is, for
example, an inverter-controlled compressor capable of changing the capacity thereof
by changing the operating frequency.
[0013] The refrigerant discharged from the compressor 1 is condensed in the condenser 2
by exchanging heat with a heat medium such as air. The refrigerant condensed in the
condenser 2 is temporarily stored in the receiver 3 as a saturated liquid. Even when
liquid-phase refrigerant having a degree of supercooling flows from the condenser
2 into the receiver 3, the liquid-phase refrigerant cools the vapor-phase refrigerant
in the receiver 3, and thereby the degree of supercooling is lost. The receiver 3
has a refrigerant outlet 30 through which the refrigerant flows out. The refrigerant
that flows out from the refrigerant outlet 30 of the receiver 3 and flows into the
supercooler 4 is a saturated liquid having no degree of supercooling.
[0014] The refrigerant flowing out from the receiver 3 is supercooled in the supercooler
4 by exchanging heat with a heat medium (hereinafter referred to as a cold source)
such as air. The supercooler 4 includes a refrigerant inflow portion 41 through which
the refrigerant flows in, a refrigerant outflow portion 42 through which refrigerant
flows out, and a plurality of refrigerant flow paths disposed between the refrigerant
inflow portion 41 and the refrigerant outflow portion 42 for the refrigerant to flow
through. The plurality of refrigerant flow paths are provided in such a manner that
the refrigerant flowing through the plurality of refrigerant flow paths exchanges
heat with a cold source flowing outside the plurality of refrigerant flow paths. The
refrigerant flowing from the supercooler 4 into the expansion valve 5 is liquid-phase
refrigerant having a degree of supercooling. The detailed configuration of the supercooler
4 will be described later.
[0015] The liquid-phase refrigerant which flowing out from the supercooler 4 and has a degree
of supercooling is decompressed in the expansion valve 5 and is converted into a gas-liquid
two-phase refrigerant. The expansion valve 5 may be replaced by any decompressing
device such as a capillary tube capable of decompressing the refrigerant.
[0016] The refrigerant decompressed by the expansion valve 5 is evaporated in the evaporator
6 by exchanging heat with a heat medium such as air.
<Configuration of Supercooler>
[0017] As illustrated in Fig. 2, the supercooler 4 includes, for example, a single heat
exchanger. The supercooler 4 is, for example, a parallel flow type (PFC) heat exchanger.
The supercooler 4 includes a refrigerant inflow portion 41, a refrigerant outflow
portion 42, a plurality of heat transfer tubes 43, a first header 44, and a second
header 45.
[0018] The plurality of heat transfer tubes 43 are disposed in parallel to each other. The
plurality of heat transfer tubes 43 includes a plurality of first heat transfer tubes
43A and a plurality of second heat transfer tubes 43B. The flow path cross-sectional
area of each of the plurality of first heat transfer tubes 43A is equal to each other,
for example. The flow path cross-sectional area of each of the plurality of second
heat transfer tubes 43B is equal to each other, for example. The flow path cross-sectional
area of each of the plurality of first heat transfer tubes 43A is equal to the flow
path cross-sectional area of each of the plurality of second heat transfer tubes 43B,
for example.
[0019] One end of each of the plurality of first heat transfer tubes 43A and one end of
each of the plurality of second heat transfer tubes 43B are connected to the first
header 44. The other end of each of the plurality of second heat transfer tubes 43B
is connected to the second header 45. The length of each of the plurality of first
heat transfer tubes 43A in the extending direction is equal to each other, for example.
The length of each of the plurality of second heat transfer tubes 43B in the extending
direction is equal to each other, for example. The length of each of the plurality
of first heat transfer tubes 43A in the extending direction is equal to the length
of each of the plurality of second heat transfer tubes 43B in the extending direction,
for example.
[0020] The plurality of heat transfer tubes 43 are disposed in such a manner that the plurality
of heat transfer tubes 43 extend in the horizontal direction and are separated from
each other with an interval in the vertical direction, for example. The plurality
of first heat transfer tubes 43A are disposed in such a manner that the plurality
of first heat transfer tubes 43A are separated from each other with an interval in
the vertical direction. The plurality of second heat transfer tubes 43B are disposed
in such a manner that the plurality of second heat transfer tubes 43B are separated
from each other with an interval in the vertical direction. The plurality of first
heat transfer tubes 43A are disposed above the plurality of second heat transfer tubes
43B, for example. A first heat transfer tube 43A, which is disposed at the lowest
position among the plurality of first heat transfer tubes 43A, is disposed above a
second heat transfer tube 43B, which is disposed at the highest position among the
plurality of second heat transfer tubes 43B.
[0021] Each of the plurality of refrigerant flow paths is formed inside a corresponding
one of the plurality of heat transfer tubes 43. The air serving as a cold source flows
outside the plurality of heat transfer tubes 43. The plurality of refrigerant flow
paths are provided in such a manner that the refrigerant flowing inside the plurality
of heat transfer tubes 43 exchanges heat with the cold source flowing outside the
plurality of heat transfer tubes 43.
[0022] The plurality of refrigerant flow paths includes a plurality of first refrigerant
flow paths P1, each of which is formed inside a corresponding one of the plurality
of first heat transfer tubes 43A, and a plurality of second refrigerant flow paths
P2, each of which is formed inside a corresponding one of the plurality of second
heat transfer tubes 43B.
[0023] In other words, the plurality of refrigerant flow paths includes a plurality of first
refrigerant flow paths P1 disposed at the most upstream side of the refrigerant circuit
among the plurality of refrigerant flow paths, and a plurality of second refrigerant
flow paths P2 through which the refrigerant that has flowed through each of the plurality
of first refrigerant flow paths P1 flows. The flow path cross-sectional area of each
of the plurality of first refrigerant flow paths P1 is equal to the flow path cross-sectional
area of each of the plurality of second refrigerant flow paths P2.
[0024] An upstream end of each of the plurality of first refrigerant flow paths P1 is connected
to the first header 44. A downstream end of each of the plurality of first refrigerant
flow paths P1 is connected to the second header 45. The plurality of first refrigerant
flow paths P1 are connected in parallel to each other between the first header 44
and the second header 45.
[0025] An upstream end of each of the plurality of second refrigerant flow paths P2 is connected
to the second header 45. A downstream end of each of the plurality of second refrigerant
flow paths P2 is connected to the first header 44. The plurality of second refrigerant
flow paths P2 are connected in parallel to each other between the first header 44
and the second header 45. Each of the plurality of second refrigerant flow paths P2
is connected in series with each of the plurality of first refrigerant flow paths
P 1.
[0026] The total flow path cross-sectional area of the plurality of first heat transfer
tubes 43A is greater than the total flow path cross-sectional area of the plurality
of second heat transfer tubes 43B. The number of the first heat transfer tubes 43A
is greater than the number of the second heat transfer tubes 43B. In other words,
the total flow path cross-sectional area of the plurality of first refrigerant flow
paths P1 is greater than the total flow path cross-sectional area of the plurality
of second refrigerant flow paths P2. The number of the plurality of first refrigerant
flow paths P1 is greater than the number of the plurality of second refrigerant flow
paths P2. Preferably, the total flow path cross-sectional area of the plurality of
first refrigerant flow paths P1 is 1.4 times or more and 2 times or less as great
as the total flow path cross-sectional area of the plurality of second refrigerant
flow paths P2. Preferably, the number of the plurality of first refrigerant flow paths
P1 is 1.4 times or more and 2 times or less as great as the number of the plurality
of second refrigerant flow paths P2.
[0027] The first header 44 includes a first space 44A that is contiguous to the upstream
end of each of the plurality of first refrigerant flow paths P1, a second space 44B
that is contiguous to the downstream end of each of the plurality of second refrigerant
flow paths P2, and a partition 46 that partitions the first space 44A and the second
space 44B. The first space 44A is contiguous to the refrigerant inflow portion 41.
The second space 44B is contiguous to the refrigerant outflow portion 42. The first
space 44A and the second space 44B are formed inside the first header 44. The partition
46 is fixed inside the first header 44.
[0028] The second header 45 has an internal space that is contiguous to both the downstream
end of each of the plurality of first refrigerant flow paths P1 and the upstream end
of each of the plurality of second refrigerant flow paths P2.
[0029] The refrigerant flowing from the refrigerant inflow portion 41 into the first space
44A of the first header 44 is distributed to each of the plurality of first refrigerant
flow paths P1. The refrigerant flowing through each of the plurality of first refrigerant
flow paths P1 merges in the inner space of the second header 45, and then is distributed
to each of the plurality of second refrigerant flow paths P2. The refrigerant flowing
through each of the plurality of second refrigerant flow paths P2 merges in the second
space 44B of the first header 44, and then flows out from the refrigerant outflow
portion 42.
[0030] The supercooler 4 further includes a plurality of fins 47. Each of the fins 47 is
a corrugate fin. Each of the fins 47 is connected to an outer peripheral surface of
each of the heat transfer tubes 43. Each of the fins 47 faces the flow path of the
cold source. The direction in which the cold source flows intersects the extending
direction of each of the plurality of heat transfer tubes 43. Each of the fins 47
is disposed, for example, between two of the first heat transfer tubes 43A adjacent
to each other in the vertical direction, or between two of the second heat transfer
tubes 43B adjacent to each other in the vertical direction, or between a first heat
transfer tube 43A disposed at the lowest position among the plurality of first heat
transfer tubes 43A and a second heat transfer tube 43B disposed at the highest position
among the plurality of second heat transfer tubes 43B.
[0031] The supercooler 4 includes a first heat exchange unit 4A which exchanges heat between
the refrigerant flowing inside the plurality of first heat transfer tubes 43A and
the cold source such as air flowing outside the plurality of first heat transfer tubes
43A, and a second heat exchange unit 4B which exchanges heat between the refrigerant
flowing inside the plurality of second heat transfer tubes 43B and the cold source
such as air flowing outside the plurality of second heat transfer tubes 43B. In the
refrigerant circuit, the first heat exchange unit 4A is disposed upstream of the second
heat exchange unit 4B and is connected in series with the second heat exchange unit
4B. Each of the first heat exchange unit 4A and the second heat exchange unit 4B is
formed as a part of a single heat exchanger.
<Effects>
[0032] The effects of the refrigeration cycle apparatus 100 will be described on the basis
of a comparison with comparative example 1 or 2. A refrigeration cycle apparatus according
to comparative example 1 or 2 is different from the refrigeration cycle apparatus
100 only in that the refrigeration cycle apparatus according to comparative example
1 or 2 is provided with a supercooler in which the total flow path cross-sectional
area of the refrigerant flow paths located at the upstream side (hereinafter referred
to as the upstream refrigerant flow paths) is equal to the total flow path cross-sectional
area of the refrigerant flow paths located at the downstream side (hereinafter referred
to as the downstream refrigerant flow paths).
[0033] In the supercooler of comparative example 1, the total flow path cross-sectional
area of the upstream refrigerant flow paths is equal to the total flow path cross-sectional
area of the downstream refrigerant flow paths. The total flow path cross-sectional
area of the downstream refrigerant flow paths of the supercooler of comparative example
1 is equal to the total flow path cross-sectional area of the plurality of second
refrigerant flow paths P2 of the supercooler 4. The total flow path cross-sectional
area of the upstream refrigerant flow paths of the supercooler of comparative example
1 is smaller than the total flow path cross-sectional area of the plurality of first
refrigerant flow paths P1 of the supercooler 4. In other words, the pressure loss
of the refrigerant in the plurality of first refrigerant flow paths P1 of the supercooler
4 is smaller than the pressure loss of the refrigerant in the upstream refrigerant
flow path of the supercooler of comparative example 1.
[0034] In the supercooler of comparative example 2, the total flow path cross-sectional
area of the upstream refrigerant flow paths is equal to the total flow path cross-sectional
area of the downstream refrigerant flow paths. The total flow path cross-sectional
area of the upstream refrigerant flow paths of the supercooler of comparative example
2 is equal to the total flow path cross-sectional area of the plurality of first refrigerant
flow paths P1 of the supercooler 4. The total flow path cross-sectional area of the
downstream refrigerant flow paths of the supercooler of comparative example 2 is greater
than the total flow path cross-sectional area of the plurality of second refrigerant
flow paths P2 of the supercooler 4. In other words, the flow velocity of the refrigerant
flowing through the plurality of second refrigerant flow paths P2 of the supercooler
4 is higher than the flow velocity of the refrigerant flowing through the downstream
refrigerant flow paths of the supercooler of comparative example 2.
[0035] Firstly, the supercooler 4 is compared with the supercooler of comparative example
1. Assume that the refrigerant flowing through the supercooler 4 has the same type,
the same flow rate and the same saturation temperature as the refrigerant flowing
through the supercooler of comparative example 1. In each of the supercooler 4 and
the supercooler of comparative example 1, the refrigerant which is a saturated liquid
having no degree of supercooling flows from the refrigerant inflow portion into the
plurality of first refrigerant flow paths or the upstream refrigerant flow paths.
In each of the supercooler 4 and the supercooler of comparative example 1, the refrigerant
flows through the plurality of first refrigerant flow paths or the upstream refrigerant
flow paths to exchange heat with the heat medium (the cold source). At the same time,
when the refrigerant flows through the plurality of first refrigerant flow paths or
the upstream refrigerant flow paths, a pressure loss occurs in the refrigerant. Since
the saturation temperature of the refrigerant corresponds to the pressure of the refrigerant,
the greater the pressure loss of the refrigerant is, the lower the saturation temperature
of the refrigerant will be.
[0036] Fig. 3 is a graph illustrating a change in the temperature of the refrigerant flowing
from the refrigerant inflow portion 41 into the refrigerant outflow portion 42 and
a change in the saturation temperature of the refrigerant in the supercooler 4. Fig.
10 is a graph illustrating a change in the temperature of the refrigerant flowing
from the refrigerant inflow portion into the refrigerant outflow portion and a change
in the saturation temperature of the refrigerant in the supercooler of comparative
example 1. In Figs. 3 and 10, a solid line indicates a change in the temperature of
the refrigerant, and a dotted line indicates a change in the saturation temperature
of the refrigerant.
[0037] As illustrated in Fig. 10, since the pressure loss of the refrigerant is relatively
large as the refrigerant flows through the upstream refrigerant flow path of the supercooler
of comparative example 1, the refrigerant is likely to be converted into gas-liquid
two-phase refrigerant during the flowing. In other words, it is likely that the gas-liquid
two-phase refrigerant flows in the downstream refrigerant flow path of the supercooler
of comparative example 1.
[0038] The higher the dryness of the refrigerant is, the greater the pressure loss of the
refrigerant will be. Therefore, the pressure loss of the gas-liquid two-phase refrigerant
flowing through the downstream refrigerant flow path is greater than the pressure
loss of the refrigerant flowing through the upstream refrigerant flow path before
it is converted to the gas-liquid two-phase refrigerant. Thus, the saturation temperature
of the gas-liquid two-phase refrigerant flowing through the downstream refrigerant
flow path is likely to become lower than that of the refrigerant flowing through the
upstream refrigerant flow path before it is converted to the gas-liquid two-phase
refrigerant. Therefore, the temperature difference between the refrigerant flowing
through the downstream refrigerant flow path and the heat medium (the cold source)
is smaller than the temperature difference between the refrigerant flowing through
the upstream refrigerant flow path and the heat medium, and becomes smaller as the
refrigerant flows toward the refrigerant outflow portion. Therefore, in the supercooler
of comparative example 1, the gas-liquid two-phase refrigerant flows out from the
refrigerant outflow portion without being supercooled.
[0039] In other words, in the supercooler of comparative example 1, the refrigerant is likely
to be converted into gas-liquid two-phase refrigerant, and the gas-liquid two-phase
refrigerant flows out without being supercooled. In the refrigeration cycle apparatus
according to comparative example 1, since the gas-liquid two-phase refrigerant flowing
out from the supercooler flows into the expansion valve, the flow rate of the refrigerant
expanded in the expansion valve is reduced as compared with the case where the liquid-phase
refrigerant having a degree of supercooling flows into the expansion valve, and thereby,
the capacity of the refrigeration cycle apparatus is deteriorated.
[0040] On the other hand, the total flow path cross-sectional area of the plurality of first
refrigerant flow paths P1 of the supercooler 4 is greater than the total flow path
cross-sectional area of the upstream refrigerant flow paths of the supercooler of
comparative example 1. Therefore, as illustrated in Fig. 3, the pressure loss of the
refrigerant as it flows through each first refrigerant flow path P1 of the supercooler
4 is smaller than the pressure loss of the refrigerant as it flows through the upstream
refrigerant flow path of the supercooler of comparative example 1. As illustrated
in Figs. 3 and 10, the amount of decrease in the saturation temperature of the refrigerant
as it flows through each first refrigerant flow path P1 is smaller than the amount
of decrease in the saturation temperature of the refrigerant as it flows through the
upstream refrigerant flow path.
[0041] Thus, as compared with the case where the refrigerant flows through the upstream
refrigerant flow path of comparative example 1, as the refrigerant flows through each
first refrigerant flow path P1, the refrigerant is less likely to be converted into
gas-liquid two-phase refrigerant, and thereby, the pressure loss of the refrigerant
is smaller and the amount of decrease in the saturated temperature of the refrigerant
is smaller. Therefore, as the refrigerant flows through each first refrigerant flow
path P1, the refrigerant is sufficiently supercooled as compared with the case where
the refrigerant flows through the upstream refrigerant flow path of comparative example
1. As a result, in the supercooler 4, the liquid-phase refrigerant having a degree
of supercooling flows from each first refrigerant flow path P1 into each second refrigerant
flow path P2. As illustrated in Fig. 10, for example, the temperature of the refrigerant
flowing into each of the second refrigerant flow paths P2 may be lower than the saturation
temperature of the refrigerant flowing out from the refrigerant outflow portion 42.
[0042] The total flow path cross-sectional area of the plurality of second refrigerant flow
paths P2 of the supercooler 4 is equal to the total flow path cross-sectional area
of the downstream refrigerant flow paths of the supercooler of comparative example
1. However, as described above, since the pressure loss of the liquid-phase refrigerant
is smaller than the pressure loss of the gas-liquid two-phase refrigerant, as the
liquid-phase refrigerant flows through the plurality of second refrigerant flow paths
P2, the saturation temperature of the liquid-phase refrigerant is less likely to decrease
lower than the saturation temperature of the gas-liquid two-phase refrigerant as the
gas-liquid two-phase refrigerant flows through the downstream refrigerant flow path
of comparative example 1. Therefore, in the supercooler 4, the liquid-phase refrigerant
flowing into the plurality of second refrigerant flow paths P2 is not converted into
the gas-liquid two-phase refrigerant, but flows out from the refrigerant outflow portion
42 while maintaining the degree of supercooling.
[0043] In other words, in the supercooler 4, the refrigerant is prevented from being converted
into the gas-liquid two-phase refrigerant as it flows through each of the plurality
of first refrigerant flow paths P1 and each of the plurality of second refrigerant
flow paths P2, and thereby, the refrigerant having a degree of supercooling flows
out from the refrigerant outflow portion 42. In the refrigeration cycle apparatus
100 including the supercooler 4, since the refrigerant flowing out from the supercooler
4 into the expansion valve 5 is liquid-phase refrigerant, the capacity of the refrigeration
cycle apparatus 100 is improved as compared with the refrigeration cycle apparatus
according to comparative example 1.
[0044] Since the total flow path cross-sectional area of the plurality of second refrigerant
flow paths P2 is smaller than the total flow path cross-sectional area of the plurality
of first refrigerant flow paths P1, the pressure loss of the refrigerant as it flows
through each of the second refrigerant flow paths P2 is greater than the pressure
loss of the refrigerant as it flows through each of the first refrigerant flow paths
P1. Therefore, in the supercooler 4, the saturation temperature of the refrigerant
as it flows through each of the second refrigerant flow paths P2 is smaller than the
saturation temperature of the refrigerant as it flows through each of the first refrigerant
flow paths P1. However, in the supercooler 4, since the degree of supercooling of
the refrigerant flowing into each of the second refrigerant flow paths P2 can be made
sufficiently large, it is possible to ensure the degree of supercooling of the refrigerant
flowing out from the refrigerant outflow portion 42. As a result, in the refrigeration
cycle apparatus 100 including the supercooler 4, since the refrigerant flowing out
from the supercooler 4 into the expansion valve 5 is liquid-phase refrigerant, the
capacity of the refrigeration cycle apparatus is prevented from being deteriorated
by the gas-liquid two-phase refrigerant flowing into the expansion valve.
[0045] Next, the supercooler 4 is compared with the supercooler of comparative example 2.
Assume that the refrigerant flowing through the supercooler 4 has the same type, the
same flow rate and the same saturation temperature as the refrigerant flowing through
the supercooler of comparative example 2. Similar to the refrigerant flowing through
the plurality of first refrigerant flow paths P 1 of the supercooler 4, as the refrigerant
flows through the upstream refrigerant flow path of the supercooler of comparative
example 2, the refrigerant is sufficiently supercooled, and thereby, the liquid-phase
refrigerant having a degree of supercooling flows into the downstream refrigerant
flow path. However, since the total flow path cross-sectional area of the downstream
refrigerant flow paths of comparative example 2 is greater than the total flow path
cross-sectional area of the downstream refrigerant flow paths of comparative example
1, the flow velocity of the liquid-phase refrigerant flowing through the downstream
refrigerant flow paths of comparative example 2 is slower than the flow velocity of
the gas-liquid two-phase refrigerant flowing through the downstream refrigerant flow
paths of comparative example 1. Since the heat transfer coefficient of the downstream
refrigerant flow paths of comparative example 2 is low, it is difficult to encure
the degree of supercooling of the refrigerant flowing out from the refrigerant outflow
portion.
[0046] On the contrary, in the supercooler 4, the number of the second refrigerant flow
paths P2 is smaller than the number of the first refrigerant flow paths P1, and is
smaller than the number of the downstream refrigerant flow paths of comparative example
2. Therefore, the flow velocity of the refrigerant flowing through the plurality of
second refrigerant flow paths P2 is higher than the flow velocity of the refrigerant
flowing through the plurality of first refrigerant flow paths P1, and is higher than
the flow velocity of the refrigerant flowing through the downstream refrigerant flow
paths of comparative example 2. As a result, in the supercooler 4, the heat transfer
coefficient in each of the second refrigerant flow paths P2 is sufficiently high,
which makes it possible to ensure the degree of supercooling of the refrigerant flowing
out from the refrigerant outflow portion 42. As a result, in the refrigeration cycle
apparatus 100 including the supercooler 4, since the refrigerant flowing out from
the supercooler 4 into the expansion valve 5 is liquid-phase refrigerant, the capacity
of the refrigeration cycle apparatus is prevented from being deteriorated by the gas-liquid
two-phase refrigerant flowing into the expansion valve.
<Modifications>
[0047] Figs. 4 to 6 are block diagrams, each of which illustrates a modification of the
refrigeration cycle apparatus 100.
[0048] As illustrated in Fig. 4, the supercooler 4 may include two or more heat exchangers.
Each of the first heat exchange unit 4A and the second heat exchange unit 4B may be
a single heat exchanger. Since a refrigeration cycle apparatus 101 illustrated in
Fig. 4 has substantially the same configuration as the refrigeration cycle apparatus
100, it can obtain the same effects as the refrigeration cycle apparatus 100.
[0049] It should be noted that each of the first heat exchange unit 4A and the second heat
exchange unit 4B is not limited to a PFC type heat exchanger, and may be any heat
exchanger. Each of the first heat exchange unit 4A and the second heat exchange unit
4B may be, for example, a heat exchanger including a plurality of heat transfer tubes
43 and a plurality of plate fins.
[0050] Further, each of the first heat exchange unit 4A and the second heat exchange unit
4B may be a plate heat exchanger including a plurality of heat transfer plates stacked
on each other to replace the plurality of heat transfer tubes 43. In this case, the
plurality of first refrigerant flow paths P1 are formed between two heat transfer
plates adjacent to each other in the stacking direction of the plurality of heat transfer
plates, and are alternately arranged with the flow paths of the plurality of cold
sources in the stacking direction. Similarly, the plurality of second refrigerant
flow paths P2 are formed between two heat transfer plates adjacent to each other in
the stacking direction of the plurality of heat transfer plates, and are alternately
arranged with the flow paths of the plurality of cold sources in the stacking direction.
[0051] As illustrated in Fig. 5, a refrigeration cycle apparatus 102 may further include
an injection flow path 11. The injection flow path 11 includes an injection expansion
valve 7. One end of the injection flow path 11 is connected to a refrigerant path
located between the supercooler 4 and the expansion valve 5 in the refrigerant circuit
10. The other end of the injection flow path 11 is connected to an intermediate pressure
port of the compressor 1.
[0052] As illustrated in Fig. 5, the supercooler 4 may be provided as an internal heat exchanger
which exchanges heat between the refrigerant flowing between the receiver 3 and the
expansion valve 5 and the refrigerant flowing between the injection expansion valve
7 and the compressor 1 in the injection flow path 11. In this case, each of the plurality
of first refrigerant flow paths P 1 and the plurality of second refrigerant flow paths
P2 is disposed downstream of the receiver 3 and upstream of the one end of the injection
flow path 11 in the refrigerant circuit 10. The refrigerant flowing between the injection
expansion valve 7 and the compressor 1 in the injection flow path 11 serves as a cold
source.
[0053] The supercooler 4 illustrated in Fig. 5 includes, for example, a first heat exchange
unit 4A and a second heat exchange unit 4B. Each of the first heat exchange unit 4A
and the second heat exchange unit 4B is, for example, a plate heat exchanger as described
above.
[0054] Since the refrigeration cycle apparatus 102 illustrated in Fig. 5 has substantially
the same configuration as the refrigeration cycle apparatus 100, it can obtain the
same effects as the refrigeration cycle apparatus 100.
[0055] As illustrated in Fig. 6, a refrigeration cycle apparatus 103 may further include
a second refrigerant circuit 12. The second refrigerant circuit 12 circulates a refrigerant
different from that circulated in the refrigerant circuit 10. The second refrigerant
circuit 12 includes a second compressor 13, a second condenser 14, a second expansion
valve 15, and a supercooler 4 that functions as an evaporator in the second refrigerant
circuit 12. In the second refrigerant circuit 12, the refrigerant decompressed by
the second expansion valve 15 serves as a cold source of the supercooler 4.
[0056] The supercooler 4 illustrated in Fig. 6 includes, for example, a first heat exchange
unit 4A and a second heat exchange unit 4B. Each of the first heat exchange unit 4A
and the second heat exchange unit 4B is, for example, a plate heat exchanger as described
above.
[0057] Since the refrigeration cycle apparatus 103 illustrated in Fig. 6 has substantially
the same configuration as the refrigeration cycle apparatus 100, it can obtain the
same effects as the refrigeration cycle apparatus 100.
[0058] Fig. 7 is a diagram illustrating a modification of the supercooler 4. The supercooler
4 illustrated in Fig. 7 further includes a plurality of connection members 50, each
of which connects a downstream end of each of two first refrigerant flow paths P1
to an upstream end of one second refrigerant flow path P2. In other words, in the
supercooler 4 illustrated in Fig. 7, each of the plurality of first refrigerant flow
paths P1 and each of the plurality of second refrigerant flow paths P2 are connected
in series via the plurality of connection members 50 instead of the second header
45 illustrated in Fig. 2.
[0059] Each of the connection members 50 is provided as, for example, a branched pipe. Each
of the connection members 50 may be provided in any means as long as it can connect
a downstream end of each of at least two first refrigerant flow paths P1 to an upstream
end of at least one second refrigerant flow path P2. The supercooler 4 may include
at least one connection member 50.
Second Embodiment
[0060] As illustrated in Fig. 8, a refrigeration cycle apparatus 104 according to a second
embodiment has substantially the same configuration as the refrigeration cycle apparatus
100 according to the first embodiment, but is different from the refrigeration cycle
apparatus 100 in that the refrigerant circuit 10 of the refrigeration cycle apparatus
104 further includes a booster unit configured to boost the refrigerant flowing from
the refrigerant outlet 30 of the receiver 3 into the refrigerant inflow portion 41
of the supercooler 4.
[0061] The refrigerant circuit 10 of the refrigeration cycle apparatus 104 illustrated in
Fig. 8 includes a descending pipe line 10A as the booster unit. One end of the descending
pipe line 10A is disposed at the upstream side of the refrigerant circuit 10, and
the other end thereof is disposed at the downstream side of the refrigerant circuit
10. The one end of the descending pipe line 10A is disposed above the other end of
the descending pipe line 10A.
[0062] In other words, the refrigeration cycle apparatus 104 differs from the refrigeration
cycle apparatus 100 in that the refrigerant outlet 30 of the receiver 3 is disposed
above the refrigerant inflow portion 41 of the supercooler 4.
[0063] Since the refrigeration cycle apparatus 104 has substantially the same configuration
as the refrigeration cycle apparatus 100, it can obtain the same effects as the refrigeration
cycle apparatus 100. Further, in the refrigeration cycle apparatus 104, the refrigerant
flowing out from the refrigerant outlet 30 of the receiver 3 is boosted by the descending
pipe line 10A, and then flows into the refrigerant inflow portion 41 of the supercooler
4. Therefore, the saturation temperature of the refrigerant flowing through the plurality
of first refrigerant flow paths P1 in the refrigeration cycle apparatus 104 is higher
than the saturation temperature of the refrigerant flowing through the plurality of
first refrigerant flow paths P1 in the refrigeration cycle apparatus 100. As a result,
the degree of supercooling of the refrigerant flowing out from the refrigerant outflow
portion 42 in the refrigeration cycle apparatus 104 is further higher than the degree
of supercooling of the refrigerant flowing out from the refrigerant outflow portion
42 in the refrigeration cycle apparatus 100. Therefore, it is more reliably to prevent
the capacity of the refrigeration cycle apparatus 104 from being deteriorated by the
conversion of refrigerant into gas-liquid two-phase refrigerant in the supercooler
4.
[0064] In the refrigeration cycle apparatus according to the second embodiment, the booster
unit may have any configuration as long as it can boost the refrigerant flowing from
the refrigerant outlet 30 of the receiver 3 into the refrigerant inflow portion 41
of the supercooler 4.
[0065] The refrigerant circuit 10 of a refrigeration cycle apparatus 105 illustrated in
Fig. 9 includes a booster pump 8 as the booster unit. Similar to the descending pipe
line 10A, the booster pump 8 boosts the refrigerant flowing from the refrigerant outlet
30 of the receiver 3 into the refrigerant inflow portion 41 of the supercooler 4.
The booster pump 8 may have any configuration as long as it can boost the refrigerant
that flows out from the refrigerant outlet 30 of the receiver 3 as a saturated liquid
having no degree of supercooling, and it may be, for example, a reciprocating pump
that includes a cylinder and a piston which reciprocates inside the cylinder.
[0066] As described above, since the refrigeration cycle apparatus 105 has substantially
the same configuration as the refrigeration cycle apparatus 104, it can obtain the
same effects as the refrigeration cycle apparatus 104.
[0067] The refrigerant circuit 10 of the refrigeration cycle apparatus 105 may further include
a descending pipe line 10A as the booster unit. The booster pump 8 and the descending
pipe line 10A are connected in series in the refrigerant circuit 10. The booster pump
8 is disposed, for example, on the downstream side of the descending pipe line 10A.
The booster pump 8 may be disposed, for example, on the downstream side of the descending
pipe line 10A.
[0068] The supercooler 4 of the refrigeration cycle apparatus 104 or 105 according to the
second embodiment may have the same configuration as the supercooler 4 illustrated
in Figs. 4 to 7. Further, the refrigerant circuit 10 in each of the refrigeration
cycle apparatuses 100 to 105 according to the first or second embodiment may not include
the receiver 3. In this case, since the liquid-phase refrigerant having a degree of
supercooling can flow from the condenser 2 into the supercooler 4, it is more reliably
to prevent the capacity from being deteriorated by the conversion of refrigerant into
gas-liquid two-phase refrigerant in the supercooler 4 than the refrigeration cycle
apparatuses 100 to 105 described above.
[0069] The supercooler 4 in each of the refrigeration cycle apparatuses 100 to 105 according
to the first or second embodiment may include at least one second refrigerant flow
path P2.
[0070] Although the embodiments of the present disclosure have been described above, the
above-described embodiments may be modified in various ways. The scope of the present
disclosure is not limited to the above-described embodiments. The scope of the present
disclosure is defined by the claims, rather than the description above, and is intended
to include any modifications within the meaning and scope equivalent to the claims.
REFERENCE SIGNS LIST
[0071] 1: compressor; 2: condenser; 3: receiver; 4: supercooler; 4A: first heat exchange
unit; 4B: second heat exchange unit; 5: expansion valve; 6: evaporator; 7: injection
expansion valve; 8: booster pump; 10: refrigerant circuit; 10A: descending pipe line;
11: injection flow path; 12: second refrigerant circuit; 13: second compressor; 14:
second condenser; 15: second expansion valve; 30: refrigerant outlet; 41: refrigerant
inflow portion; 42: refrigerant outflow portion; 43: heat transfer tube; 43A: first
heat transfer tube; 43B: second heat transfer tube; 44: first header; 44A: first space;
44B: second space; 45: second header; 46: partition; 47: fin; 50: connection member;
100, 101, 102, 103, 104, 105: refrigeration cycle apparatus
1. A refrigeration cycle apparatus comprising:
a refrigerant circuit which includes a compressor, a condenser, a supercooler, an
expansion valve, and an evaporator, and circulates refrigerant in the order of the
compressor, the condenser, the supercooler, the expansion valve, and the evaporator,
wherein the supercooler includes a plurality of refrigerant flow paths through which
the refrigerant flows,
the plurality of refrigerant flow paths includes a plurality of first refrigerant
flow paths disposed at the most upstream side of the refrigerant circuit among the
plurality of refrigerant flow paths, and at least one second refrigerant flow path
through which the refrigerant that has flowed through each of the plurality of first
refrigerant flow paths flows, and
a total flow path cross-sectional area of the plurality of first refrigerant flow
paths is greater than a total flow path cross-sectional area of the at least one second
refrigerant flow path.
2. The refrigeration cycle apparatus according to claim 1, wherein
the refrigerant circuit further includes a receiver that is disposed between the condenser
and the supercooler so as to store the refrigerant condensed in the condenser,
the receiver includes a refrigerant outlet through which the refrigerant flows out,
and
each of the plurality of first refrigerant flow paths is disposed lower than the refrigerant
outlet of the receiver.
3. The refrigeration cycle apparatus according to claim 2, wherein
the refrigerant circuit further includes a booster unit that is disposed between the
receiver and the supercooler so as to boost the refrigerant flowing out from the receiver,
and
the refrigerant boosted by the booster unit flows into each of the plurality of first
refrigerant flow paths.
4. The refrigeration cycle apparatus according to any one of claims 1 to 3, wherein
the at least one second refrigerant flow path includes a plurality of second refrigerant
flow paths,
the supercooler further includes:
a first header to which an upstream end of each of the plurality of first refrigerant
flow paths and a downstream end of each of the plurality of second refrigerant flow
paths are connected; and
a second header to which a downstream end of each of the plurality of first refrigerant
flow paths and an upstream end of each of the plurality of second refrigerant flow
paths are connected,
the first header includes:
a first space that is contiguous to the upstream end of each of the plurality of first
refrigerant flow paths;
a second space that is contiguous to the downstream end of each of the plurality of
second refrigerant flow paths; and
a partition that partitions the first space and the second space.
5. The refrigeration cycle apparatus according to any one of claims 1 to 3, wherein
the supercooler further includes at least one connection member that connects a downstream
end of each of the plurality of first refrigerant flow paths and an upstream end of
the at least one second refrigerant flow path, and
a total flow path cross-sectional area of the plurality of first refrigerant flow
paths connected to the at least one connection member is greater than a total flow
path cross-sectional area of the at least one second refrigerant flow path connected
to the at least one connection member.
6. The refrigeration cycle apparatus according to any one of claims 1 to 3, wherein
the supercooler includes a first supercooling section that includes the plurality
of first refrigerant flow paths and a second supercooling section that includes the
at least one second refrigerant flow path, and
the first supercooling section is separated from the second supercooling section.
7. The refrigeration cycle apparatus according to any one of claims 1 to 6, wherein
the number of the plurality of first refrigerant flow paths is greater than the number
of the at least one second refrigerant flow path.