JP2814697B2 - Refrigeration cycle device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigeration cycle device for obtaining a higher or lower temperature, such as a heating and cooling device, a hot water supply device, or an ultra-low temperature device.

2. Description of the Related Art Conventionally, when a temperature difference between a low temperature side and a high temperature side is large, such as a refrigeration cycle of a low-temperature refrigerator or a water heater, a compression stage is called a two-stage compression refrigeration cycle (not shown). Many refrigeration cycles have been used to improve the efficiency of the compressor and reduce the temperature of the refrigerant discharged from the compressor.

In addition, a device called a binary refrigeration cycle is often used for an ultra-low temperature refrigerator or the like in which the temperature difference between the low temperature side and the high temperature side becomes larger. The configuration will be described below with reference to FIG. As shown in the drawing, a high-temperature cycle in which the high-temperature compressor 1, the condenser 2, the high-temperature throttling device 3, and the evaporator 4 are connected, and the low-temperature compressor 5, the condenser 6, the low-temperature throttling device 7, and the evaporator 8 Is connected to the low-temperature side cycle. By exchanging heat between the low-temperature side evaporator 4 and the low-temperature side condenser 6, the low-temperature side refrigerant is condensed and the high-temperature side refrigerant is evaporated. .

Also, for ultra-low temperature refrigerators requiring -50 ° C or lower, a low-boiling refrigerant such as R-13 is sealed on the low-temperature side, and a relatively high-boiling refrigerant such as R-22 is sealed on the high-temperature side. General.

However, in the two-stage compression refrigeration cycle, when the temperature on the low-temperature side is very low, the specific capacity of the suction refrigerant of the low-temperature side compressor 5 increases, so that the necessary capacity is secured. However, there is a problem that the compressor becomes large and the pressure becomes too high when the temperature on the high temperature side is high.

Further, the two-way refrigeration cycle is effective when the temperature condition is constant, such as when a low temperature is always required as in an ultra-low temperature refrigerator. When the temperature changes greatly depending on the load, or when the operation is repeatedly performed, the selection of the refrigerant is very difficult.For example, when R-13 is used as the low-temperature side refrigerant, when the ambient temperature is 30 ° C. When stopped, the temperature exceeds the critical temperature, the pressure becomes 40 atm or more, and there is a problem that a very dangerous state is expected.

SUMMARY OF THE INVENTION An object of the present invention is to provide a refrigeration cycle apparatus capable of obtaining a required capacity even under a wide range of operating conditions and performing a safe operation, while keeping in mind the above conventional problems.

Means for Solving the Problems In order to achieve the above object, a refrigeration cycle of the present invention comprises:
A non-azeotropic mixed refrigerant is sealed, and a low-stage compressor, a high-stage compressor, a condenser, an on-off valve, a main throttle device, and an evaporator are sequentially connected to form a main circuit of a two-stage compression refrigeration cycle. A rectifying separator connected to the condenser outlet via a first auxiliary throttle device is provided, and a bottom of the rectifying separator is connected to a suction side of the high-stage compressor via a first refrigerant heat exchanger. And a flow path switching valve is provided between the low-stage compressor and the high-stage compressor, one of the flow path switching valves being on the suction side of the high-stage compressor and the other being the second refrigerant. Connected via a heat exchanger to the inlet side of the main throttle device and via a second auxiliary throttle device to the top of the rectifier separator, and further connected the top of the rectifier separator to the inlet side of the evaporator This is a circuit configuration connected to.

Operation The present invention has the above-described structure, and operates the two-stage compression refrigeration cycle based on the composition of the enclosed non-azeotropic refrigerant mixture and the rectifier according to the operating temperature conditions, thereby increasing the high-temperature side cycle by operating the rectification separator. The boiling point refrigerant can be switched to a binary refrigeration cycle in which the low-temperature side cycle has a large amount of low boiling point refrigerant, and the coefficient of performance can be improved under a wide range of operating conditions.

Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 shows an embodiment of a refrigeration cycle apparatus of the present invention, in which 9 is a low-stage compressor, 10 is a high-stage compressor, 11 is a condenser, 12 is an on-off valve, 13 Is a main throttle device, and 14 is an evaporator.
It constitutes the main circuit of the stage compression refrigeration cycle. Also, 15
Is a rectifying separator, which is connected to the outlet of the condenser 11 via a first auxiliary throttle device 16. Further, the bottom of the rectification separator 15 is connected to the suction side of the high-stage compressor 10 via a first refrigerant heat exchanger 17 and a check valve 18, and the low-stage compressor 9
A flow switching valve 19 is provided on the discharge side of the compressor. One of the flow switching valves 19 is provided on the suction side of the high-stage compressor 10, and the other is provided via a second refrigerant heat exchanger 20. It is connected to the inlet side of the expansion device 13 and to the top of the rectifying separator 15 via a second auxiliary expansion device 21. Further, the top of the fractionator 15 is connected to the inlet side of the evaporator 14 via a third auxiliary throttle device 22.

In such a refrigeration cycle, a non-azeotropic refrigerant mixture in which, for example, R-22 is mixed as a high-boiling refrigerant and R-13 is mixed as a low-boiling refrigerant is sealed.

Next, the operation in the case of driving will be described. First,
When the temperature difference between the high temperature side and the low temperature side is not so large, the operation is performed as a two-stage compression refrigeration cycle. That is, the flow path switching valve 19 is set in the illustrated direction, the on-off valve 12 is opened, and the second
The auxiliary throttle device 21 adjusts so that the refrigerant does not flow. Before the start of operation, the composition of the mixed refrigerant in the refrigeration cycle remains as it is, and by starting operation of the low-stage compressor 9 and the high-stage compressor 10, the high-stage compression is started. The high-temperature and high-pressure refrigerant gas discharged from the machine 10 is cooled by the condenser 11 and is condensed.
The pressure is expanded to the evaporation pressure at 13, and the pressure is expanded to the evaporator 14, where it is absorbed, evaporated and vaporized and sucked into the low-stage compressor 9. Here, the refrigerant compressed to the intermediate pressure is mixed with the liquid refrigerant guided through the bottom of the rectification separator 15, the first refrigerant heat exchanger 17, and the check valve 18 via the first auxiliary expansion device 16. As a result, the liquid refrigerant is cooled by the latent heat of evaporation of the liquid refrigerant, and is sucked into the high-stage compressor 10. In this manner, a refrigeration cycle of two-stage compression and one-stage expansion using the mixed refrigerant having the enclosed composition is realized. In the one-stage compression, the compression ratio becomes too large, and the temperature is high even under a temperature condition in which an extreme decrease in efficiency occurs. The efficiency can be maintained.

Further, when the temperature difference between the high temperature side and the low temperature side becomes large and it becomes difficult to maintain the capacity and efficiency in the two-stage compression refrigeration cycle, the two-stage compression refrigeration cycle is operated as a binary refrigeration cycle. That is, the flow path switching valve 19 is rotated by 90 ° in the direction of the arrow in the figure, the on-off valve 12 is closed, and the first auxiliary throttle device 16 and the second auxiliary throttle device are rotated.
21 and the third auxiliary aperture device 22 are adjusted appropriately. As a result, the high-temperature and high-pressure refrigerant gas discharged from the high-stage compressor 10 is cooled by the condenser 11 and condensed and liquefied. And is led to the bottom of the rectification separator 15. Here, the gas refrigerant having a high concentration of R-13, which is a low-boiling refrigerant, rises in the rectification separator 15, and the liquid refrigerant having a high concentration of R-22, which is a high-boiling refrigerant, passes through the first refrigerant heat exchanger 17. Be guided. On the other hand, the intermediate-pressure refrigerant discharged from the low-stage compressor 9 is supplied to the passage switching valve.
19, to the second refrigerant heat exchanger 20, where the first refrigerant heat exchanger 20
By exchanging heat with the liquid refrigerant flowing through the refrigerant heat exchanger 17, the liquid refrigerant evaporates and evaporates, condenses and liquefies itself, is reduced in pressure to the evaporation pressure by the main throttle device 13, and is guided to the evaporator 14. At the lower stage side compressor 9. In addition, a part of the liquid refrigerant condensed in the second refrigerant heat exchanger 20 is supplied to the top of the rectifying separator 15 through the second auxiliary expansion device 21 and rises into the rectifying separator 15. The gas refrigerant has a rectification effect due to sufficient gas-liquid contact, and the rising gas increases the concentration of the low-boiling refrigerant R-13, while the descending liquid increases the concentration of the high-boiling refrigerant R22. Will be. In this way, the gaseous refrigerant having a high concentration of the low-boiling-point refrigerant R-13 is guided from the top of the rectifying separator 15 to the inlet side of the evaporator 14 via the third auxiliary expansion device 22, and is supplied to the high-boiling-point refrigerant R-13. The liquid refrigerant having an increased concentration of R-22 is supplied to the rectification separator 15
At the bottom thereof is mixed with the liquid refrigerant supplied from the first auxiliary expansion device 16 and guided to the first refrigerant heat exchanger 17. By continuing such an operation, the refrigerant evaporated in the evaporator 14 and drawn into the low-stage compressor 9 has a very high concentration of R-13, which is a low-boiling-point refrigerant, and the high-stage compressor Compressed with 10 condenser
The refrigerant condensed in 11 has a very high concentration of R-22, which is a high-boiling refrigerant, realizing a refrigeration cycle similar to a binary refrigeration cycle in which the type of refrigerant is changed between a low-temperature cycle and a high-temperature cycle. Is done. It is possible to maintain high efficiency and capacity even under operating conditions where the temperature difference is so large that the capacity and efficiency cannot be maintained by two-stage compression.

In addition, when the operation is stopped, the refrigerant in the apparatus becomes a mixed refrigerant having a composition that is mixed and enclosed. Therefore, even when a low-boiling refrigerant such as R-13 is used, the pressure is abnormally increased and a danger is caused. Can be prevented.

Effect of the Invention As is clear from the above description, the refrigeration cycle apparatus of the present invention encloses a non-azeotropic mixed refrigerant, and includes a low-stage compressor, a high-stage compressor, a condenser, an on-off valve, and a main throttle device. , An evaporator is sequentially connected to form a main circuit of a two-stage compression refrigerant cycle, and a rectifier connected to the condenser outlet via a first auxiliary throttle device is provided, and a bottom portion of the rectifier is provided. Is connected to the suction side of the high-stage compressor via a first refrigerant heat exchanger, and a flow path switching valve is provided between the low-stage compressor and the high-stage compressor. One of the valves is on the suction side of the high-stage compressor, and the other is on the inlet side of the main throttle device via a second refrigerant heat exchanger, and on the inlet side of the main throttle device, and via the second auxiliary throttle device. Connected to the top, and the top of the fractionator is connected to the inlet side of the evaporator. From, according to the operating temperature conditions, a two-stage compression refrigeration cycle by the composition of the enclosed non-azeotropic mixed refrigerant,
By operating the rectification separator, it is possible to switch to a binary refrigeration cycle that has more high-boiling refrigerant for the high-temperature cycle and low-boiling refrigerant for the low-temperature cycle. It is possible to improve the coefficient and secure the necessary capacity.

In addition, when the operation is stopped, the refrigerant in the apparatus becomes a mixed refrigerant having a composition that is mixed and enclosed. Therefore, even when a low-boiling refrigerant such as R-13 is used, the pressure is abnormally increased and a danger is caused. Thus, the present invention exerts a great effect in practical use, for example, it can be prevented from being in a bad state.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a refrigeration cycle apparatus according to one embodiment of the present invention, and FIG. 2 is a circuit diagram of a conventional binary refrigeration cycle apparatus. 9 low-stage compressor, 10 high-stage compressor, 11 condenser, 12 on-off valve, 13 main throttle device, 14 evaporator,
15 rectifying separator, 16 first auxiliary throttle device, 17 first refrigerant heat exchanger, 19 flow path switching valve, 20 second refrigerant heat exchanger, 21 second Auxiliary throttle device, 22... Third auxiliary throttle device.

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Shozo Funakura 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (58) Field surveyed (Int. Cl. ⁶ , DB name) F25B 1/00- 7/00

Claims (1)

(57) [Claims] A non-azeotropic mixed refrigerant is charged, and a low-stage compressor is provided.
A high-stage compressor, a condenser, an on-off valve, a main throttle device, and an evaporator are sequentially connected to form a main circuit of a two-stage compression refrigeration cycle,
A rectifying separator connected to the condenser outlet via a first auxiliary throttle device is provided, and a bottom of the rectifying separator is connected to a suction side of the high-stage compressor via a first refrigerant heat exchanger. And a flow path switching valve is provided between the low-stage compressor and the high-stage compressor, one of the flow path switching valves being on the suction side of the high-stage compressor and the other being the second refrigerant. Connected via a heat exchanger to the inlet side of the main throttle device and via a second auxiliary throttle device to the top of the rectifier separator, and further connected the top of the rectifier separator to the inlet side of the evaporator Refrigeration cycle device connected to.