JP2010249444A - Freezer-refrigerator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a freezer-refrigerator capable of reducing power consumption. <P>SOLUTION: This freezer-refrigerator comprises a refrigeration compartment 2 for refrigerating and storing an object to be stored, a freezing compartment 4 for freezing and storing an object to be stored, a first compressor 11 for operating a first refrigeration cycle 10 in which a first refrigerant flows, a first radiator 12 disposed on a high-temperature section of the first refrigeration cycle 10, a first evaporator 14 disposed on a low-temperature section of the first refrigeration cycle 10, a second compressor 21 for operating a second refrigeration cycle 20 in which a second refrigerant flows, a second evaporator 24 disposed on a low-temperature section of the second refrigeration cycle 20, and an intermediate heat exchanger 31 for performing heat exchange between the low-temperature section of the first refrigeration cycle 10 and a high-temperature section of the second refrigeration cycle 20. The first evaporator 14 cools the refrigeration compartment 2, and the second evaporator 24 cools the freezing compartment 4. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a refrigerator-freezer provided with first and second evaporators for cooling a refrigerator compartment and a freezer compartment, respectively. Moreover, it is related with the refrigerator provided with the 1st, 2nd cooling chamber from which temperature differs.

  In a conventional refrigerator-freezer, an evaporator is disposed in a low temperature part of a single refrigeration cycle operated by a compressor. The evaporator is installed behind the freezer compartment, and cold air exchanged with the evaporator is sent to the refrigerator compartment and the freezer compartment. Thereby, a refrigerator compartment and a freezer compartment are cooled.

  Patent Documents 1 and 2 disclose a dual refrigeration cycle having first and second refrigeration cycles operated by first and second compressors, respectively. The dual refrigeration cycle is provided with an intermediate heat exchanger that performs heat exchange between the low temperature portion of the first refrigeration cycle and the high temperature portion of the second refrigeration cycle. An evaporator is disposed in the low temperature part of the second refrigeration cycle.

  The intermediate heat exchanger in the low temperature part of the first refrigeration cycle is maintained at a low temperature by driving the first compressor. By driving the second compressor, the refrigerant in the second refrigeration cycle dissipates heat in the intermediate heat exchanger and is condensed, and the evaporator in the low temperature part of the second refrigeration cycle is maintained at a lower temperature than the intermediate heat exchanger. Therefore, the cryogenic cold air heat-exchanged with the evaporator can be supplied to the storage chamber.

  In addition, the second refrigeration cycle of the dual refrigeration cycle of Patent Document 2 is provided with a receiver after the intermediate heat exchanger. The receiver performs gas-liquid separation of the refrigerant flowing out from the intermediate heat exchanger of the second refrigeration cycle, and discharges the liquid refrigerant. Thereby, the bubble contained in the refrigerant | coolant which flows into an evaporator can be reduced, the circulation amount of a refrigerant | coolant can be ensured, and the fall of a cooling capability can be prevented.

Japanese Patent Application Laid-Open No. 2004-279014 (page 2 to page 8, FIG. 1) Japanese Utility Model Publication No. 5-36258 (pages 5-6, FIG. 1)

  A single refrigeration cycle mounted on a conventional refrigerator-freezer is configured such that an evaporator serving as a cooler simultaneously cools a freezer compartment and a refrigerator compartment having different temperature zones. For this reason, for example, in order to maintain a freezer compartment temperature of −20 ° C., it is necessary to reduce the evaporation temperature of the evaporator to −20 ° C. or lower and circulate cold air of −20 ° C. or lower to the freezer compartment. At this time, the refrigerating room maintained at 0 to 5 ° C., for example, is simultaneously cooled with cold air of −20 ° C. or less.

  However, cooling of the refrigerator compartment maintained at 0 to 5 ° C. does not require cold air of −20 ° C. or lower, and can be sufficiently cooled even with cold air that is several degrees lower than the set temperature of the refrigerator compartment. When generating the same amount of cold air, the lower the temperature of the cold air, the more energy required such as electric power. Therefore, since the temperature difference between the refrigerator compartment and the evaporator is large, the COP (Coefficient Of Performance) of the refrigeration cycle is low, and there is a problem that the power consumption of the refrigerator-freezer is large.

  Similarly, when the dual refrigeration cycle of Patent Documents 1 and 2 is mounted on a refrigerator-freezer, the temperature difference between the refrigerator compartment and the evaporator increases because the evaporator is maintained at a very low temperature.

  An object of this invention is to provide the freezer refrigerator and refrigerator which can reduce power consumption.

  In order to achieve the above object, the refrigerator-freezer of the present invention includes a refrigerating room for storing stored items in a refrigerator, a freezing chamber for storing stored items in a frozen state, and a first compression that operates a first refrigeration cycle through which a first refrigerant flows. A first evaporator that is disposed in a low temperature part of the first refrigeration cycle and cools the refrigerator compartment, a second compressor that operates a second refrigeration cycle through which a second refrigerant flows, and a first refrigeration cycle A second evaporator disposed in a low temperature part of the second refrigeration cycle that is maintained at a lower temperature than the low temperature part to cool the freezer compartment; and between a low temperature part of the first refrigeration cycle and a high temperature part of the second refrigeration cycle. An intermediate heat exchanger for exchanging heat with the first heat exchanger, and a receiver that is disposed on the first refrigeration cycle side of the intermediate heat exchanger and separates the gas-liquid of the first refrigerant and discharges the gas refrigerant. It is said.

  According to this configuration, the first and second refrigeration cycles are operated by the first and second compressors, and the first and second refrigerants are circulated to form the low temperature portion and the high temperature portion of the first and second refrigeration cycles, respectively. Is done. The first low-temperature and low-pressure refrigerant flows into the first evaporator and the intermediate heat exchanger in the low temperature part of the first refrigeration cycle, and the refrigerator compartment is cooled by the cold air cooled by the first evaporator. A high temperature and high pressure second refrigerant flows into the high temperature part of the second refrigeration cycle and is absorbed by the intermediate heat exchanger to dissipate heat. The low-temperature and low-pressure second refrigerant flows into the second evaporator in the low-temperature part of the second refrigeration cycle, and the freezer compartment is cooled by the cold air cooled by the second evaporator. The first refrigerant flowing into the intermediate heat exchanger exchanges heat with the second refrigerant in a gas-liquid mixed state, and then the gas-state first refrigerant separated by the receiver exchanges heat with the second refrigerant and absorbs heat.

  Further, according to the present invention, in the refrigerator with the above configuration, the intermediate heat exchanger exchanges heat between the upstream side of the first refrigeration cycle and the downstream side of the second refrigeration cycle, and the downstream side of the first refrigeration cycle and the second refrigeration cycle. It is characterized by heat exchange with the upstream side of the cycle. According to this configuration, the first refrigerant in the gas-liquid mixed state flowing into the intermediate heat exchanger exchanges heat with the second refrigerant radiated by the intermediate heat exchanger. The gas-state first refrigerant that has passed through the receiver exchanges heat with the high-temperature second refrigerant that has flowed into the intermediate heat exchanger.

  Further, the present invention provides the refrigerator with the above configuration, wherein the intermediate heat exchanger mainly takes latent heat from the second refrigerant upstream of the receiver of the first refrigeration cycle to give latent heat to the first refrigerant. And a sensible heat exchange section that mainly takes sensible heat from the second refrigerant downstream of the receiver of the first refrigeration cycle and applies sensible heat to the first refrigerant. According to this configuration, the first refrigerant in the gas-liquid mixed state flowing into the intermediate heat exchanger takes the condensation heat (latent heat) of the second refrigerant and vaporizes it. The first refrigerant in the gas state that has passed through the receiver takes up the sensible heat of the high-temperature second refrigerant and rises in temperature.

  The present invention further includes a first refrigerator and a second radiator disposed in the high-temperature portions of the first and second refrigeration cycles in the refrigerator-freezer having the above-described configuration, and the intermediate heat exchanger is provided at the subsequent stage of the second radiator. It is characterized by the arrangement. According to this configuration, the first refrigerant radiates heat in the first radiator by driving the first compressor, and then flows through the first evaporator and the intermediate heat exchanger in the low temperature part. When the second compressor is driven, the second refrigerant radiates heat at the second radiator and drops in temperature, and then flows into the intermediate heat exchanger to exchange heat with the first refrigerant.

  In the refrigerator having the above-described configuration, the second refrigerant that has flowed out of the second evaporator performs heat exchange with the second refrigerant that has flowed out of the intermediate heat exchanger. It is characterized in that heat exchange is performed with the first refrigerant that has flowed out. According to this configuration, the second refrigerant flowing out from the intermediate heat exchanger is absorbed by the low-temperature second refrigerant flowing out from the second evaporator, and the enthalpy is reduced. Further, the first refrigerant flowing out from the first radiator is absorbed by the low-temperature second refrigerant flowing out from the second evaporator, and the enthalpy is lowered. Thereby, the 1st, 2nd refrigerant | coolant with high cooling capacity flows in into a 1st, 2nd evaporator.

  According to the present invention, in the refrigerator-freezer configured as described above, the first and second refrigerants are made of isobutane.

  Moreover, the present invention is characterized in that, in the refrigerator-freezer configured as described above, the boiling point of the first refrigerant is higher than the boiling point of the second refrigerant.

  According to the present invention, in the refrigerator-freezer configured as described above, the first refrigerant is made of isobutane and the second refrigerant is made of propane or carbon dioxide.

  Moreover, the refrigerator of the present invention is arranged in the first and second cooling chambers, the first compressor that operates the first refrigeration cycle in which the first refrigerant flows, and the low temperature portion of the first refrigeration cycle, so that the first cooling is performed. A first evaporator that cools the chamber, a second compressor that operates a second refrigeration cycle through which the second refrigerant flows, and a low temperature part of the second refrigeration cycle that is maintained at a lower temperature than the low temperature part of the first refrigeration cycle A second evaporator for cooling the second cooling chamber, an intermediate heat exchanger for exchanging heat between the low temperature part of the first refrigeration cycle and the high temperature part of the second refrigeration cycle, and the intermediate heat exchange And a receiver that separates the gas-liquid of the first refrigerant and discharges the gas refrigerant.

  According to the present invention, there is provided an intermediate heat exchanger for exchanging heat between the low temperature part of the first refrigeration cycle operated by the first compressor and the high temperature part of the second refrigeration cycle operated by the second compressor. In the two-stage refrigeration cycle type refrigerator-freezer, the refrigerator compartment is cooled by the first evaporator provided in the first refrigeration cycle, and the freezer compartment is cooled by the second evaporator provided in the second refrigeration cycle. For this reason, the temperature difference between the first evaporator and the refrigerator compartment can be reduced, and the first and second compressors can be operated with high efficiency. Therefore, the COP (Coefficient Of Performance) of the refrigeration cycle is improved, and the power consumption of the refrigerator-freezer can be reduced.

  In addition, since the receiver is provided on the first refrigeration cycle side of the intermediate heat exchanger, the first refrigerant of the gas refrigerant exchanges heat with the second refrigerant even if the heat load of the refrigerator-freezer fluctuates. Thereby, the temperature of the first refrigerant is surely raised and sent to the first compressor, and the capability of the intermediate heat exchanger can be maintained. In addition, since the first refrigerant of the gas refrigerant flowing out from the receiver absorbs heat and is heated up, it flows into the first compressor, so that it is possible to reduce the heat loss.

Side surface sectional drawing which shows the refrigerator-freezer of embodiment of this invention The figure which shows the refrigerating cycle of the refrigerator-freezer of embodiment of this invention. The figure which shows the detail of the intermediate heat exchanger of the refrigerating cycle of the refrigerator-freezer of embodiment of this invention PH diagram of the refrigerator-freezer of the embodiment of the present invention Diagram showing the relationship between adiabatic compression efficiency and compression ratio of positive displacement compressors The figure which shows the relationship between the position and temperature of the intermediate heat exchanger of the refrigerating cycle of the refrigerator-freezer of embodiment of this invention. The figure which shows the refrigerating cycle of a comparative example The figure which shows the relationship between the position and temperature of the intermediate heat exchanger of the refrigerating cycle of a comparative example

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a side sectional view showing a refrigerator-freezer according to an embodiment. The refrigerator-freezer 1 is provided with a refrigerator compartment 2 for storing stored items in a refrigerator. Below the refrigerator compartment 2 is provided a vegetable compartment 3 which is maintained at a temperature higher than that of the refrigerator compartment 2 and suitable for storage of vegetables. A freezer compartment 4 for storing stored items in a frozen state is disposed at the bottom of the freezer 1. The front surface of the refrigerator compartment 2 is opened and closed by a rotating heat insulating door 2a. The front surfaces of the vegetable compartment 3 and the freezer compartment 4 are opened and closed by drawer-type heat insulating doors 3a and 4a integrated with the storage cases 3b and 4b, respectively.

  A machine room 5 is provided behind the freezer room 4. First and second compressors 11 and 21 for operating first and second refrigeration cycles 10 and 20 (see FIG. 2), which will be described in detail later, are disposed in the machine room 5. A first evaporator 14 connected to the first compressor 11 is disposed on the back surface of the refrigerator compartment 2, and a refrigerator refrigerator 15 is disposed above the first evaporator 14. A second evaporator 24 connected to the second compressor 21 is disposed on the back surface of the freezer compartment 4, and a freezer compartment blower 25 is disposed above the second evaporator 24.

  Cold air cooled by exchanging heat with the first evaporator 14 is discharged to the refrigerator compartment 2 by the refrigerator refrigerator 15. The cold air flows through the refrigerator compartment 2 and flows into the vegetable compartment 3 communicating with the refrigerator compartment 2. The cold air that has flowed into the vegetable compartment 3 flows through the vegetable compartment 3 and returns to the first evaporator 14. Thereby, the refrigerator compartment 2 and the vegetable compartment 3 are cooled. The cold air cooled by exchanging heat with the second evaporator 24 is discharged to the freezer compartment 4 by the freezer blower 25. The cold air discharged into the freezer compartment 4 flows through the freezer compartment 4 and returns to the second evaporator 24. Thereby, the freezer compartment 4 is cooled.

  FIG. 2 shows the refrigeration cycle of the refrigerator 1. The refrigeration cycle 30 of the refrigerator 1 is a cascade type dual refrigeration cycle in which the first and second refrigeration cycles 10 and 20 are connected by an intermediate heat exchanger 31. That is, the first refrigeration cycle 10 forms a high temperature cycle, and the second refrigeration cycle 20 forms a low temperature cycle. Then, heat exchange is performed between the low temperature part of the first refrigeration cycle 10 and the high temperature part of the second refrigeration cycle 20 by the intermediate heat exchanger 31. Accordingly, the low temperature part of the second refrigeration cycle 20 is maintained at a lower temperature than the low temperature part of the first refrigeration cycle 10.

  The first refrigeration cycle 10 operated by the first compressor 11 has a first radiator 12, a first decompressor 13, and a first evaporator 14 connected by a refrigerant pipe 16. A first refrigerant such as isobutane flows in the refrigerant pipe 16 in the direction of the arrow S1. That is, the first refrigerant circulates through the first compressor 11, the first radiator 12, the first decompressor 13, the first evaporator 14, the intermediate heat exchanger 31, and the first compressor 11 in this order. A first receiver 17 that separates gas and liquid, stores liquid refrigerant, and discharges gas refrigerant is provided on the first refrigeration cycle 10 side of the intermediate heat exchanger 31. The first receiver 17 prevents the liquid refrigerant from flowing into the first compressor 11.

  The second refrigeration cycle 20 operated by the second compressor 21 has a second radiator 22, a second decompressor 23, and a second evaporator 24 connected by a refrigerant pipe 26. A second refrigerant such as isobutane flows in the refrigerant pipe 26 in the direction of the arrow S2. That is, the second refrigerant circulates through the second compressor 21, the second radiator 22, the intermediate heat exchanger 31, the second decompressor 23, the second evaporator 24, and the second compressor 21 in this order. A second receiver 27 that separates gas and liquid, stores liquid refrigerant, and discharges gas refrigerant is provided downstream of the second evaporator 24. The second receiver 27 prevents the liquid refrigerant from flowing into the second compressor 21.

  FIG. 2 is a diagram showing details of the intermediate heat exchanger 31. The intermediate heat exchanger 31 is formed such that the heat exchanging parts 31a and 31b provided in the first refrigeration cycle 10 and the heat exchanging parts 31c and 31d provided in the second refrigeration cycle 20 are adjacent to each other and can exchange heat via wall surfaces. Is done. The heat exchanging part 31 a is arranged downstream of the first evaporator 14, and the heat exchanging part 31 d is arranged downstream of the second radiator 22.

  On the first refrigeration cycle 10 side of the intermediate heat exchanger 31, heat exchange units 31a and 31b are provided upstream and downstream of the first receiver 17, respectively. As a result, the heat exchange unit 31a is vaporized by the vaporization (latent heat) of the first refrigerant mixed with the gas and liquid, and the heat exchange unit 31b is heated by the sensible heat of the first refrigerant in the gas state.

  The heat exchange unit 31 a on the upstream side of the first refrigeration cycle 1 performs heat exchange adjacent to the heat exchange unit 31 c on the downstream side of the second refrigeration cycle 20. Further, the heat exchanging portion 31 b on the downstream side of the first refrigeration cycle 1 performs heat exchange adjacent to the heat exchanging portion 31 d on the upstream side of the second refrigeration cycle 20. At this time, the heat exchange unit 31d mainly releases sensible heat from the high-temperature second refrigerant, and the second refrigerant cooled by the heat exchange unit 31d mainly releases the condensation heat (latent heat) at the heat exchange unit 31c. The length of the heat exchange parts 31c and 31d is set. Therefore, the heat exchange units 31a and 31c constitute a latent heat exchange unit that gives the latent heat of the second refrigerant as the latent heat of the first refrigerant, and the heat exchange units 31b and 31d convert the sensible heat of the second refrigerant to the sensible heat of the first refrigerant. The sensible heat exchange section given as

  The first and second refrigeration cycles 10 and 20 are provided with first and second internal heat exchangers 32 and 33, respectively. The first internal heat exchanger 32 is formed so that the heat exchanging part 32a provided in the first refrigeration cycle 10 and the heat exchanging part 32b provided in the second refrigeration cycle 20 are adjacent to each other and can exchange heat via wall surfaces. .

  The second internal heat exchanger 33 adjoins the heat exchange part 33a arranged downstream of the intermediate heat exchanger 31 and the heat exchange part 33b arranged downstream of the second evaporator 24, and heats them through the wall surfaces. Formed interchangeably. The second refrigerant before flowing out from the intermediate heat exchanger 31 and flowing into the second evaporator flows through the heat exchanger 33a, and the second refrigerant after flowing out of the second evaporator 24 flows through the heat exchanger 33b. To do. In the case where the second decompression device 23 is made of a capillary tube, the heat exchanging portion 33a may also serve as the second decompression device 23.

  The heat exchanging part 32a of the first internal heat exchanger 32 is arranged at the rear stage of the first radiator 12, and the first refrigerant before flowing into the first evaporator 14 flows therethrough. The heat exchanging part 32b is arranged downstream of the heat exchanging part 33b of the second internal heat exchanger 33, and the second refrigerant after flowing out of the second internal heat exchanger 33 flows therethrough. In the case where the first pressure reducing device 13 is formed of a capillary tube, the heat exchanging portion 32 a may also serve as the first pressure reducing device 13.

  In the refrigerator-freezer 1 having the above configuration, the first and second refrigerants flow through the refrigerant pipes 16 and 26 by driving the first and second compressors 11 and 21, respectively. The first and second compressors 11 and 21 compress the first and second refrigerants to high temperature and high pressure, and the first and second decompression devices 13 and 23 decompress and expand the first and second refrigerants at low temperature and low pressure. To.

  Accordingly, the first and second refrigeration cycles 10 and 20 until the first and second refrigerants flow out of the first and second compressors 11 and 21 and flow into the first and second decompression devices 13 and 23. It becomes the high temperature part. The low temperature of the first and second refrigeration cycles 10 and 20 until the first and second refrigerant flows out of the first and second decompression devices 13 and 23 and flows into the first and second compressors 11 and 21. Part.

  The high-temperature and high-pressure first refrigerant compressed by the first compressor 11 is deprived of heat by the first radiator 12 and condensed. The first refrigerant liquefied by the first radiator 12 is deprived of heat by the first refrigerant in the low temperature part of the second refrigeration cycle 20 by the first internal heat exchanger 32 and further cooled. The liquid first refrigerant cooled by the first internal heat exchanger 32 and having a high degree of supercooling flows into the first pressure reducing device 13. The first refrigerant is decompressed and expanded by the first decompression device 13, and becomes a low-temperature wet steam having a low dryness.

  The first refrigerant that has become low-temperature wet steam flows into the first evaporator 14, takes heat from the cold air in the refrigerator compartment 2, evaporates, and becomes wet steam with higher dryness. The first refrigerant in a wet vapor state flowing out from the first evaporator 14 flows into the heat exchange part 31 a of the intermediate heat exchanger 31. The first refrigerant evaporates while taking away the latent heat of the second refrigerant in the heat exchanging part 31 c in the heat exchanging part 31 a and flows into the first receiver 17.

  The first refrigerant flowing into the first receiver 17 is gas-liquid separated, and the liquid refrigerant is stored and the gas refrigerant is discharged. The first refrigerant in a gas state discharged from the first receiver 17 is heated to become superheated steam while taking mainly sensible heat of the heat exchange part 31d in the heat exchange part 31b. The first refrigerant that has become superheated steam returns to the first compressor 11. As a result, the first refrigerant circulates and the first refrigeration cycle 10 is operated.

  The high-temperature and high-pressure second refrigerant compressed by the second compressor 21 is deprived of the ambient air by the second radiator 22. The second refrigerant lowered in temperature by the second radiator 22 flows into the heat exchange part 31d of the intermediate heat exchanger 31. The second refrigerant that has flowed into the heat exchanging portion 31d is further cooled by mainly taking sensible heat from the first refrigerant in the heat exchanging portion 31b. The temperature-reduced second refrigerant in the gas state flows into the heat exchanging part 31c, and is mainly deprived of latent heat and condensed by the first refrigerant in the heat exchanging part 31a. The condensed second refrigerant is further lowered in temperature by the second internal heat exchanger 33 where heat is taken away by the second refrigerant in the low temperature portion of the second refrigeration cycle 20.

  The second refrigerant in a liquid state cooled by the second internal heat exchanger 33 and having a high degree of supercooling flows into the second decompression device 23. The second refrigerant is decompressed and expanded by the second decompression device 23, and becomes low-temperature wet steam. The second refrigerant that has become low-temperature wet steam flows into the second evaporator 24, takes heat from the cold air in the freezer compartment 4 and evaporates to become wet steam.

  The second refrigerant in the wet vapor state flowing out from the second evaporator 24 is guided to the second internal heat exchanger 33 and the first internal heat exchanger 32, and takes heat from the high-temperature second refrigerant and the first refrigerant and overheats. It becomes steam. The second refrigerant that has become superheated steam returns to the second compressor 21. As a result, the second refrigerant circulates and the second refrigeration cycle 20 is operated.

  The second compressor 21 is driven after the temperature of the intermediate heat exchanger 31 is lowered after the first compressor 11 is driven. And the temperature difference between the temperature of the refrigerator compartment 2 and the freezer compartment 4, and the heat exchange parts 31a and 31b of the intermediate heat exchanger 31, and the heat exchange parts 31c and 31d is monitored. The rotation speeds of the first and second compressors 11 and 21 are controlled by inverter control so that these become predetermined values.

  FIG. 4 shows a pressure-enthalpy diagram (PH diagram) of the refrigeration cycle 30. The vertical axis represents pressure, and the horizontal axis represents enthalpy. Also, in the figure, each point A, B, C, D, E, E ′, F, a, b, b ′, b ″ c, d, e, and f are the points of the refrigeration cycle shown in FIG. It corresponds.

  In the case of the first refrigeration cycle 10 (A-B-C-D-E-E'-F-A), A-B represents a process in the first compressor 11. B-C represents a process in the first radiator 12. CD represents the process in the heat exchange part 32a of the first internal heat exchanger 32. DE represents the process in the first pressure reducing device 13. E-E ′ represents a process in the first evaporator 14. E′-F represents a process in the heat exchange part 31 a of the intermediate heat exchanger 31. F-A represents a process in the heat exchange part 31b of the intermediate heat exchanger 31.

  The same applies to the second refrigeration cycle 20 (ab-b'-b "-cd-fa), where ab represents the process in the second compressor 21. b -B 'represents the process in the second heat radiator 22. b'-b "represents the process in the heat exchange part 31d of the intermediate heat exchanger 31. b ″ -c represents a process in the heat exchange part 31c of the intermediate heat exchanger 31. cd represents a process in the heat exchange part 33a of the second internal heat exchanger 33. de represents the first. 2 represents the process in the decompression device 23. ef represents the process in the second evaporator 24. fa represents the heat exchange section 33b and the first internal heat exchanger of the second internal heat exchanger 33. The process in 32 heat-exchange parts 32b is represented.

  Since the same refrigerant (for example, isobutane) is sealed in the first and second refrigeration cycles 10 and 20, the temperature relationship and the pressure relationship of the first and second refrigeration cycles 10 and 20 are found on the PH diagram. It has become easier. For example, the pressure PA at the point A of the first refrigeration cycle 10 is slightly lower than the pressure Pb at the point b of the second refrigeration cycle 20. This is because the first refrigeration cycle 10 takes heat from the second refrigeration cycle 20.

  In the case of the conventional single refrigeration cycle, if the freezer compartment 4 has the same set temperature, the evaporating temperatures of the first and second evaporators for cooling the refrigerator compartment 2 and the freezer compartment 4 respectively are ef in FIG. It is the level expressed by. On the other hand, the evaporation temperature of the first evaporator 14 for cooling the refrigerator compartment 2 of the present embodiment is represented by E-E 'in FIG. In the wet steam region of the refrigerant, the higher the pressure P, the higher the temperature, so that the evaporation temperature of the first evaporator 14 becomes higher than in the case of a single refrigeration cycle.

  Thereby, in the case of the conventional single refrigeration cycle, the temperature difference between the first evaporator 14 and the refrigerator compartment 2 which has been 20 ° C., for example, can be remarkably reduced to, for example, 5 ° C. or less. Therefore, the highly efficient refrigerator-freezer 1 can be provided without using wasteful energy for cooling the refrigerator compartment 2.

  Further, in the case of the conventional single refrigeration cycle, if the temperature setting conditions are the same, the condensation pressure becomes the pressure PB at the point B, and the evaporation pressure becomes the pressure Pa at the point a. For this reason, the compression ratio of the compressor is PB / Pa. On the other hand, in the present embodiment, the compression ratio of the first refrigeration cycle 10 is PB / PA, and the compression ratio of the second refrigeration cycle 20 is Pb / Pa. For this reason, all become smaller than the compression ratio of a single refrigeration cycle.

  Fig. 5 shows the relationship between adiabatic compression efficiency and compression ratio of positive displacement compressors according to ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) "Guide and Data Book" (1961, p498). Show. The vertical axis represents adiabatic compression efficiency, and the horizontal axis represents the compression ratio. Note that most of the compressors currently used in ordinary refrigerator-freezers are of the positive displacement type. Although the refrigerant is experimental data of R12 and R22, it can be said that other refrigerants have the same tendency. According to the figure, the smaller the compression ratio of the compressor, the higher the adiabatic compression efficiency of the compressor.

  When the ambient temperature is 25 ° C., the temperature in the refrigerator compartment 2 is 3 ° C., the temperature in the freezer compartment 4 is −18 ° C., and the first and second refrigerants are commonly used isobutane, The compression ratio is about 8. On the other hand, the compression ratios of the first and second refrigeration cycles 10 and 20 are about 2 to 3, respectively. Therefore, since the compression ratios of the first and second refrigeration cycles 10 and 20 are both smaller than the conventional one, the first and second compressors 11 and 21 can be operated with high efficiency.

  FIG. 6 is a diagram showing the relationship between the position of the intermediate heat exchanger 31 and the temperature. For comparison, FIG. 8 shows the relationship between the position of the intermediate heat exchanger 31 and the temperature of the refrigeration cycle 30 'shown in FIG. In the refrigeration cycle 30 ′ of the comparative example, the first receiver 17 is arranged at the rear stage of the intermediate heat exchanger 31. Other portions are the same as those of the refrigeration cycle 30 shown in FIG. 6 and 8, the vertical axis indicates the temperature, and the horizontal axis indicates the position of the intermediate heat exchanger 31. In the drawing, each point A, F, E ', b', b ", c corresponds to each point of the refrigeration cycles 30, 30 'shown in Figs.

  On the second refrigeration cycle 20 side of the intermediate heat exchanger 31 of the comparative example, the second refrigerant dissipates heat in the heat exchange part 31d (b'-b ") and is condensed in the heat exchange part 31c (b" -c). Further, on the first refrigeration cycle 10 side of the intermediate heat exchanger 31, the first refrigerant evaporates in the heat exchange unit 31a (E'-F), and also evaporates in the heat exchange unit 31b (FA).

  For this reason, the temperature difference of the 1st, 2nd refrigerant | coolant in the heat exchange part 31b becomes large, and the loss by heat exchange is large. Further, since the first refrigerant of the gas refrigerant flowing out from the first receiver 17 does not absorb heat from the second refrigeration cycle 20, it flows into the first compressor 1 at the evaporation temperature. Therefore, the heat loss is likely to occur.

  In contrast, on the first refrigeration cycle 10 side of the intermediate heat exchanger 31 of the present embodiment, the first refrigerant evaporates in the heat exchange unit 31a (E′-F), and in the heat exchange unit 31b (FA). It absorbs heat. For this reason, in the intermediate heat exchanger 31, latent heat exchange and sensible heat exchange are performed in matching. Therefore, the temperature difference required for heat exchange can be minimized, and loss of effective energy due to heat exchange can be reduced. Further, since the first refrigerant absorbs heat and is heated to flow into the first compressor 11, the heat loss can be reduced.

  According to the present embodiment, the heat exchange is performed between the low temperature part of the first refrigeration cycle 10 operated by the first compressor 11 and the high temperature part of the second refrigeration cycle 20 operated by the second compressor 21. In the refrigerator-freezer 1 of the two-stage refrigeration cycle type provided with the heat exchanger 31, the second evaporation provided in the second refrigeration cycle 20 by cooling the refrigerator compartment 2 by the first evaporator 14 provided in the first refrigeration cycle 10. The freezer compartment 4 is cooled by the vessel 24. For this reason, the temperature difference between the first evaporator 14 and the refrigerator compartment 2 can be reduced, and the first and second compressors 11 and 21 can be operated with high efficiency. Therefore, the COP of the refrigeration cycle 30 is improved as compared with the conventional case, and the power consumption of the refrigerator-freezer 1 can be reduced.

  Moreover, since the 1st receiver 17 was provided in the 1st freezing cycle 10 side of the intermediate heat exchanger 31, even if the heat load of the refrigerator-freezer 1 fluctuates, the 1st refrigerant | coolant of a gas refrigerant exchanges heat with a 2nd refrigerant | coolant. Thereby, the temperature of the first refrigerant is reliably raised and sent to the first compressor 11, and the capability of the intermediate heat exchanger 31 can be maintained. In addition, since the first refrigerant of the gas refrigerant that has flowed out of the first receiver 17 absorbs heat and then rises in temperature, it flows into the first compressor 11, so that the heat loss can be reduced.

  In addition, the intermediate heat exchanger 31 exchanges heat between the heat exchanging portion 31 a on the upstream side of the first refrigeration cycle 10 and the heat exchanging portion 31 c on the downstream side of the second refrigeration cycle 20. Since the heat exchanging part 31b and the heat exchanging part 31d on the upstream side of the second refrigeration cycle 20 exchange heat, the first refrigerant in the gas state flowing out of the first receiver 17 exchanges heat with the high-temperature second refrigerant. Thereby, the sensible heat by the heat radiation of the second refrigerant is used for the sensible heat for raising the temperature of the first refrigerant, and the temperature difference in heat exchange between the first and second refrigerants can be reduced. Therefore, the loss of effective energy due to heat exchange can be reduced, and the power consumption of the refrigerator-freezer 1 can be further reduced.

  In addition, the first refrigerant mainly takes latent heat from the second refrigerant in the latent heat exchanger (31a, 31c), and the first refrigerant mainly receives sensible heat from the second refrigerant in the sensible heat exchanger (31b, 31d). Therefore, the latent heat exchange and the sensible heat exchange of the first and second refrigerants are performed in matching, and the temperature difference between the two can be further reduced.

  In addition, since the first and second radiators 12 and 22 are provided in the high temperature portions of the first and second refrigeration cycles 10 and 20, respectively, the heat radiation temperature of the entire first and second refrigeration cycles 10 and 20 is further lowered. be able to. Therefore, the COP of the refrigeration cycle 30 is improved. In addition, since the intermediate heat exchanger 31 is arranged at the subsequent stage of the second radiator 22, the second refrigerant flows through the second radiator 22 before the heat is taken away by the first refrigerant by the intermediate heat exchanger 31. Thereby, since the 2nd refrigerant | coolant after heat-exchanging with the 2nd heat radiator 22 and thermally radiating is cooled by the intermediate heat exchanger 31, heat exchange can be performed more efficiently.

  In addition, after the second refrigerant flowing out from the second evaporator 24 in the second internal heat exchanger 33 exchanges heat with the second refrigerant flowing out from the intermediate heat exchanger 31, the first internal heat exchanger Since heat exchange is performed with the first refrigerant flowing out of the first radiator 12 at 32, the enthalpies of the first and second refrigerants flowing into the first and second evaporators 14 and 24 can be reduced. . Therefore, the cooling capacity of the first and second refrigerants flowing into the first and second evaporators 14 and 24 can be further improved.

  In the present embodiment, the same refrigerant such as isobutane is used for the first and second refrigerants, but different refrigerants may be used. At this time, the boiling point of the first refrigerant may be higher than the boiling point of the second refrigerant. Thereby, since the vapor density of the second refrigerant is higher than that of the first refrigerant and the performance of the second refrigeration cycle 20 can be further improved, it is further preferable.

  For example, it can be easily realized by using isobutane (boiling point −12 ° C.) as the first refrigerant and propane (boiling point −40.09 ° C.) or carbon dioxide (boiling point −78.5 ° C.) as the second refrigerant. . All of these refrigerants are natural refrigerants that use substances that exist in large quantities in nature. Therefore, the environmental load of the refrigerator-freezer 1 can be further reduced by increasing the cooling efficiency of the refrigeration cycle using the natural refrigerant.

  In addition, as long as it is a refrigerator equipped with a two-way refrigeration cycle in which the first and second evaporators 14 and 24 are arranged in the first and second cooling chambers having different room temperatures, the same applies to any one. Applicable. In other words, the present invention can be applied to refrigeration cycle application equipment centered on a domestic refrigerator-freezer 1.

  According to this invention, it can utilize for the refrigerator refrigerator provided with the 1st, 2nd evaporator which cools a refrigerator compartment and a freezer compartment, respectively. Moreover, it can utilize for the refrigerator provided with the 1st, 2nd evaporator which cools the 1st, 2nd cooling chamber from which temperature differs, respectively.

DESCRIPTION OF SYMBOLS 1 Refrigerator Refrigerator 2 Refrigerated room 3 Vegetable room 4 Freezer room 10 1st freezing cycle 11 1st compressor 12 1st heat radiator 13 1 decompression device 14 1st evaporator 15 Cold room fan 16, 26 Refrigerant tube 17 1st receiver 20 2nd refrigeration cycle 21 2nd compressor 22 2nd radiator 23 2nd decompression device 24 2nd evaporator 25 freezer compartment blower 27 2nd receiver 30, 30 'refrigeration cycle 31 intermediate heat exchanger 31a, 31c heat exchange part (Latent heat exchanger)
31b, 31d Heat exchange part (sensible heat exchange part)
32 1st internal heat exchanger 33 2nd internal heat exchanger

Claims (9)

  It is arranged in a cold room for storing stored items in a refrigerator, a freezing chamber for storing stored items in a frozen state, a first compressor for operating a first refrigeration cycle through which a first refrigerant flows, and a low temperature part of the first refrigeration cycle. A first evaporator that cools the refrigerating chamber, a second compressor that operates a second refrigeration cycle through which a second refrigerant flows, and a second refrigeration cycle that is maintained at a lower temperature than a low temperature portion of the first refrigeration cycle. A second evaporator arranged in a low temperature section for cooling the freezer compartment, an intermediate heat exchanger for exchanging heat between the low temperature section of the first refrigeration cycle and the high temperature section of the second refrigeration cycle, and the intermediate heat A refrigerator-freezer comprising a receiver that is disposed on the first refrigeration cycle side of the exchanger and that separates the gas-liquid of the first refrigerant and discharges the gas refrigerant.   The intermediate heat exchanger exchanges heat between the upstream side of the first refrigeration cycle and the downstream side of the second refrigeration cycle, and exchanges heat between the downstream side of the first refrigeration cycle and the upstream side of the second refrigeration cycle. The refrigerator-freezer according to claim 1.   The intermediate heat exchanger has a latent heat exchange section that mainly takes latent heat from the second refrigerant upstream of the receiver of the first refrigeration cycle and applies latent heat to the first refrigerant, and more than the receiver of the first refrigeration cycle. The refrigerator-freezer according to claim 2, further comprising a sensible heat exchange section that draws sensible heat mainly from the second refrigerant and applies sensible heat to the first refrigerant downstream.   The first and second radiators respectively disposed in the high-temperature portions of the first and second refrigeration cycles are provided, and the intermediate heat exchanger is arranged at the subsequent stage of the second radiator. Item 4. The refrigerator-freezer according to any one of Items 3.   The second refrigerant flowing out from the second evaporator exchanges heat with the second refrigerant flowing out from the intermediate heat exchanger, and then exchanges heat with the first refrigerant flowing out from the first radiator. It performs, The refrigerator-freezer of Claim 4 characterized by the above-mentioned.   6. The refrigerator-freezer according to claim 1, wherein the first and second refrigerants are made of isobutane.   The refrigerator according to any one of claims 1 to 5, wherein the boiling point of the first refrigerant is higher than the boiling point of the second refrigerant.   The refrigerator-freezer according to claim 7, wherein the first refrigerant is made of isobutane and the second refrigerant is made of propane or carbon dioxide.   First and second cooling chambers, a first compressor that operates a first refrigeration cycle through which a first refrigerant flows, and a first evaporator that is disposed in a low temperature portion of the first refrigeration cycle and cools the first cooling chamber And a second compressor operating the second refrigeration cycle through which the second refrigerant flows, and a second cooling chamber disposed in a low temperature part of the second refrigeration cycle maintained at a lower temperature than the low temperature part of the first refrigeration cycle A second evaporator that cools the refrigerant, an intermediate heat exchanger that exchanges heat between the low temperature portion of the first refrigeration cycle and the high temperature portion of the second refrigeration cycle, and the first refrigeration cycle side of the intermediate heat exchanger And a receiver for separating the gas-liquid of the first refrigerant and discharging the gas refrigerant.

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