The present disclosure relates to a refrigeration circuit and a refrigeration device.
A refrigeration circuit includes a heat exchanger for cooling circulating refrigerant so as to obtain the temperature of the refrigerant required at an evaporator. For example, PTL 1 discloses a refrigeration circuit including a flow divider for separating gas and liquid, and a double tube heat exchanger for exchanging heat between the vapor phase refrigerant flowed out from the flow divider, and the liquid phase refrigerant flowed out from the flow divider and the refrigerant returning to the compressor from the evaporator.
In refrigeration circuits, lower temperatures may be required depending on the object to be cooled. This requires enhancement in heat exchanging efficiency, but the increase in size of the heat exchanger and in number of heat exchangers may cause a problem in terms of the mounting space of the heat exchanger.
To solve the known problems of the related art, an object of the present disclosure is to reduce the size of a heat exchanger and improve the heat exchanging efficiency in a refrigeration circuit and a refrigeration device.
To achieve the above-mentioned object, a refrigeration circuit in the present disclosure includes: a gas-liquid separator into which a gas-liquid two-phase refrigerant flowed out from a condenser flows, the gas-liquid separator being configured to separate the gas-liquid two-phase refrigerant into a vapor phase refrigerant and a liquid phase refrigerant; and a plate heat exchanger including a first heat exchanging part and a second heat exchanging part, the first heat exchanging part being a part where the vapor phase refrigerant flowed out from the gas-liquid separator and the liquid phase refrigerant flowed out from the gas-liquid separator exchange heat, the second heat exchanging part being a part where the vapor phase refrigerant flowed out from the first heat exchanging part and a returning refrigerant flowed out from an evaporator exchange heat.
In addition, to achieve the above-mentioned object, a refrigeration device in the present disclosure includes the above-described refrigeration circuit.
With the refrigeration circuit and the refrigeration device according to embodiments of the present disclosure, it is possible to reduce the size of the heat exchanger and improve the heat exchanging efficiency.
Refrigeration circuit 1 according to an embodiment of the present disclosure is described below with reference to the drawings. Refrigeration circuit 1 is used for a refrigeration device such as an ultra-low-temperature freezer. As illustrated in
A gas-liquid two-phase refrigerant, which is a mixture of a vapor phase refrigerant and a liquid phase refrigerant, enters gas-liquid separator 13, and gas-liquid separator 13 separates the gas-liquid two-phase refrigerant into a vapor phase refrigerant and a liquid phase refrigerant. The vapor phase refrigerant flows out from the upper part of gas-liquid separator 13. The liquid phase refrigerant flows out from the lower part of gas-liquid separator 13. First decompressor 14 is a capillary tube, for example.
Plate heat exchanger 20 includes first heat exchanging part 20a and second heat exchanging part 20b. First heat exchanging part 20a exchanges heat between the vapor phase refrigerant flowed out from gas-liquid separator 13, and a mixed refrigerant of a returning refrigerant and the liquid phase refrigerant flowed out from gas-liquid separator 13. The returning refrigerant is a refrigerant flowing out from evaporator 17 and returning to compressor 10.
Second heat exchanging part 20b exchanges heat between the vapor phase refrigerant flowed out from first heat exchanging part 20a and the returning refrigerant flowed out from evaporator 17. Details of plate heat exchanger 20 are described later.
The inner pipe of double tube heat exchanger 16 is second decompressor 15. Second decompressor 15 is a capillary tube, for example. The returning refrigerant flowed out from evaporator 17 flows through outer pipe 16a of double tube heat exchanger 16. That is, in double tube heat exchanger 16, the returning refrigerant and the refrigerant flowing through second decompressor 15 exchange heat.
The above-described devices are connected by pipe 18 such that the refrigerant ejected from compressor 10 returns to compressor 10 again.
The refrigerant illustrated in
The vapor phase refrigerant flowed out from gas-liquid separator 13 flows through first heat exchanging part 20a, second heat exchanging part 20b, second decompressor 15 and evaporator 17 in this order. Further, the returning refrigerant flowed out from evaporator 17 flows through outer pipe 16a of double tube heat exchanger 16 and second heat exchanging part 20b in this order. The returning refrigerant flowed out from second heat exchanging part 20b flows out from gas-liquid separator 13, merges at confluence part 18a with the liquid phase refrigerant flowed through first decompressor 14, and returns to compressor 10 through first heat exchanging part 20a.
Note that the gas-liquid two-phase refrigerant is a mixture of a vapor phase refrigerant and a liquid phase refrigerant. More specifically, the gas-liquid two-phase refrigerant is a mixture of one or more refrigerants respectively selected from among the liquid phase refrigerant listed in the group A and the vapor phase refrigerant listed in the group B shown in Table 1. Note that the liquid phase refrigerant is a refrigerant with a boiling point of −55° C. or higher, and liquefies before flowing into gas-liquid separator 13. In addition, the vapor phase refrigerant is a refrigerant with a boiling point lower than −55° C.
Next, details of plate heat exchanger 20 are described with reference to
Plate heat exchanger 20 is a brazed plate heat exchanger. Plate heat exchanger 20 includes a plurality of heat transfer plates 21 and cover plates 22. Twelve heat transfer plates 21 are provided in the present embodiment. Heat transfer plate 21 and cover plate 22 are examples of “plate”. Heat transfer plate 21 and cover plate 22 are plate members with a rectangular shape in front view.
The plurality of heat transfer plates 21 is disposed side by side along the front-rear direction with their plate surfaces parallel to each other and with a predetermined distance therebetween (
In addition, second channel R2 and fourth channel R4 are formed so as to be communicated with each other (
Through hole 21c2 is communicated with through hole 21d1 formed in fourth heat transfer plate 21d. In addition, the peripheries of through holes 21c2 and 21d1 are in contact with each other and welded. In this manner, second channel R2 and fourth channel R4 communicate with each other, and do not communicate with third channel R3 located between second and fourth channels R2 and R4.
In addition, with similar configurations, channels R adjacent to each other in fourth, sixth, eighth, tenth channels R4, R6, R8 and R10 are configured to communicate with each other. Further, with similar configurations, channels R adjacent to each other in first, third and fifth channels R1, R3 and R5 are configured to communicate with each other. Further, with similar configurations, channels R adjacent to each other in seventh, ninth and eleventh channels R7, R9 and R11 are configured to communicate with each other. Note that the above-described channels R adjacent to each other are configured to communicate with each other on the upper side and lower side of heat transfer plate 21, except between sixth channel R6 and eighth channel R8. The part between sixth channel R6 and eighth channel R8 are configured to communicate on the upper side of heat transfer plate 21.
Cover plate 22 is disposed at the front ends and rear ends of the plurality of heat transfer plates 21 disposed side by side. Each cover plate 22 is disposed such that the plate surfaces of each cover plate 22 and opposite heat transfer plate 21 are in contact with each other.
In addition, first connection pipe 23a, second connection pipe 23b and third connection pipe 23c are disposed at the plate surface of first cover plate 22a. First and second connection pipes 23a and 23b are disposed side by side in the left-right direction on the lower side of first cover plate 22a. Third connection pipe 23c is disposed on the upper side of second connection pipe 23b. First connection pipe 23a is an example of “vapor phase refrigerant inflow part”. Second connection pipe 23b is an example of “liquid phase refrigerant inflow part”. Third connection pipe 23c is an example of “liquid phase refrigerant outflow part”.
Further, fourth connection pipe 23d, fifth connection pipe 23e and sixth connection pipe 23f are disposed at the plate surface of second cover plate 22b. Fourth and fifth connection pipes 23d and 23e are disposed side by side in the left-right direction on the lower side of second cover plate 22b. Sixth connection pipe 23f is disposed on the upper side of fifth connection pipe 23e. Fourth connection pipe 23d is an example of “vapor phase refrigerant outflow part”. Fifth connection pipe 23e is an example of “returning refrigerant inflow part”. Sixth connection pipe 23f is an example of “returning refrigerant outflow part”.
The first end of first connection pipe 23a is connected to pipe 18 connected to the upper part of gas-liquid separator 13. The second end of first connection pipe 23a is open to second channel R2. The first end of second connection pipe 23b is connected to the first end of sixth connection pipe 23f through pipe 18. The second end of second connection pipe 23b is open to first channel R1.
The first end of third connection pipe 23c is connected to pipe 18 connected to compressor 10. The second end of third connection pipe 23c is open to first channel R1. The first end of fourth connection pipe 23d is connected to pipe 18 connected to second decompressor 15. The second end of fourth connection pipe 23d is open at tenth channel R10.
The first end of fifth connection pipe 23e is connected to pipe 18 connected to outer pipe 16a of double tube heat exchanger 16. The second end of fifth connection pipe 23e is open to eleventh channel R11. The first end of sixth connection pipe 23f is connected to the first end of second connection pipe 23b as described above. The second end of sixth connection pipe 23f is open at eleventh channel R11.
First heat exchanging part 20a is composed of first cover plate 22a, first to sixth heat transfer plates 21a to 21f, and first to third connection pipes 23a to 23c.
Second heat exchanging part 20b is composed of second cover plate 22b, seventh to twelfth heat transfer plates 21g to 21l, and fourth to sixth connection pipes 23d to 23f. First heat exchanging part 20a and second heat exchanging part 20b are integrally formed.
Next, heat exchange at first heat exchanging part 20a is described.
The vapor phase refrigerant flowed out from gas-liquid separator 13 flows through channel R of first heat exchanging part 20a as indicated with the solid line arrow illustrated in
On the other hand, the refrigerant (hereinafter referred to as merged refrigerant) composed of the returning refrigerant flowed out from sixth connection pipe 23f and the liquid phase refrigerant flowed out from gas-liquid separator 13 that are merged with each other at confluence part 18a flows through channel R of first heat exchanging part 20a as indicated with the broken line arrow illustrated in
In this manner, refrigerants with temperatures different from each other flow in channels R adjacent to each other with second to sixth heat transfer plates 23b to 21f therebetween. In this manner, the vapor phase refrigerant and the merged refrigerant exchange heat through second to sixth heat transfer plates 23b to 21f.
Next, heat exchange at second heat exchanging part 20b is described.
The vapor phase refrigerant flowed into eighth channel R8 from the upper side flows through channel R of second heat exchanging part 20b as indicated with the solid line arrow illustrated in
On the other hand, the returning refrigerant flowed out from outer pipe 16a of double tube heat exchanger 16 flows through channel R of second heat exchanging part 20b as indicated with the broken line arrow illustrated in
In this manner, refrigerants with temperatures different from each other flow in channels R adjacent to each other with seventh to eleventh heat transfer plates 21g to 21k therebetween. In this manner, the vapor phase refrigerant and the returning refrigerant exchange heat through seventh to eleventh heat transfer plates 21g to 21k.
According to the present embodiment, refrigeration circuit 1 includes gas-liquid separator 13 into which the gas-liquid two-phase refrigerant flowed out from condenser 11 flows, and plate heat exchanger 20 including first heat exchanging part 20a where the vapor phase refrigerant flowed out from gas-liquid separator 13 and the liquid phase refrigerant flowed out from gas-liquid separator 13 exchange heat, and second heat exchanging part 20b where the vapor phase refrigerant flowed out from first heat exchanging part 20a and the returning refrigerant flowed out from evaporator 17 exchange heat. Gas-liquid separator 13 separates the gas-liquid two-phase refrigerant into a vapor phase refrigerant and a liquid phase refrigerant
In this manner, refrigeration circuit 1 performs two-stage heat exchange by using one plate heat exchanger 20 for the refrigerant flowing from condenser 11 toward evaporator 17. Thus, the size of the heat exchanger can be reduced, and the low temperature required at evaporator 17 can be obtained in such a manner that the refrigerant flowing toward evaporator 17 efficiently exchanges heat.
In addition, in first heat exchanging part 20a, the heat is exchanged between the vapor phase refrigerant flowed out from gas-liquid separator 13, and the mixed refrigerant of the liquid phase refrigerant flowed out from gas-liquid separator 13 and the returning refrigerant flowed out from second heat exchanging part 20b.
In this manner, at first heat exchanging part 20a, the heat can be exchanged by using the refrigerant of the mixture of the liquid phase refrigerant and the returning refrigerant.
In addition, in plate heat exchanger 20, the plurality of cover plates 22 and the plurality of heat transfer plates 21 are disposed side by side such that their plate surfaces face each other. At the plate surface of first cover plate 22a disposed at the first end of plate heat exchanger 20, first connection pipe 23a into which the vapor phase refrigerant flows, second connection pipe 23b into which the liquid phase refrigerant flows, and the third connection pipe 23c from which the liquid phase refrigerant flows out are disposed. At the plate surface of second cover plate 22b disposed at the second end of plate heat exchanger 20, fourth connection pipe 23d from which the vapor phase refrigerant flows out, fifth connection pipe 23e into which the returning refrigerant flows, and sixth connection pipe 23f from which the returning refrigerant flows out are disposed.
This increases the ease of the routing of pipe 18.
In addition, refrigeration circuit 1 further includes double tube heat exchanger 16 including the inner pipe into which the vapor phase refrigerant flowed out from second heat exchanging part 20b flows and outer pipe 16a through which the returning refrigerant that flows into second heat exchanging part 20b flows.
In this manner, with double tube heat exchanger 16, the temperature of the refrigerant supplied to evaporator 17 can be further reduced. Moreover, a countercurrent heat exchanger can be made up of the entirety of the heat exchanger system composed of first heat exchanging part 20a, second heat exchanging part 20b and double tube heat exchanger 16. Thus, the required ultra-low temperature can be obtained by efficiently exchanging heat while making the entirety of the heat exchanger system compact.
The above description of one or more forms of refrigeration circuits is based on the embodiment, but this disclosure is not limited to this embodiment. As long as the main purpose of this disclosure is not departed from, various variations that one skilled in the art can conceive of are applied to this embodiment, and embodiments constructed by combining components in different embodiments may also be included within the scope of one or more embodiments.
Instead of the above-described configuration in which the merged refrigerant and the vapor phase refrigerant flowed out from gas-liquid separator 13 exchange heat in first heat exchanging part 20a, pipe 118 may be configured such that the vapor phase refrigerant flowed out from gas-liquid separator 13 and the liquid phase refrigerant flowed out from gas-liquid separator 13 exchange heat. In this case, as illustrated in
In addition, heat transfer plate 21 may be formed such that the plate surface has a wave shape. In this manner, the flow of the refrigerant can be more easily made turbulent in comparison with the case where the plate surface has a planar shape, and thus the heat exchange efficiency can be improved.
In addition, refrigeration circuit 1 may not include double tube heat exchanger 16. In this case, the refrigerant flowed out from second heat exchanging part 20b flows through second decompressor 15 and evaporator 17 in this order. Further, the returning refrigerant flowed out from evaporator 17 flows into second heat exchanging part 20b.
In addition, in plate heat exchanger 20, channel R through which vapor phase refrigerant flows may be configured as illustrated in
In this manner, the vapor phase refrigerant flowed out from gas-liquid separator 13 flows through channel R of first heat exchanging part 20a as indicated with the solid line arrow illustrated in
Further, the vapor phase refrigerant flowed through fourth channel R4 flows through channel R of second heat exchanging part 20b as indicated with the solid line arrow illustrated in
This application is entitled to and claims the benefit of Japanese Patent Application No. 2021-004787 filed on Jan. 15, 2021, the disclosure each of which including the specification, drawings and abstract is incorporated herein by reference in its entirety.
The refrigeration circuit and the refrigeration device of the present disclosure are widely applicable to ultra-low-temperature freezers and refrigerators.
Number | Date | Country | Kind |
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2021-004787 | Jan 2021 | JP | national |
Number | Date | Country | |
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Parent | PCT/JP2021/045834 | Dec 2021 | US |
Child | 18108973 | US |