JPH04324072A - Refrigeration circuit for non-azeotropic refrigerant - Google Patents

Abstract

PURPOSE:To provide a refrigeration circuit for non-azeotropic refrigerant, which is capable of preventing the deterioration of a freezing capacity due to the generation of flush gas. CONSTITUTION:A refrigeration circuit for non-azeotropic refrigerant, which is equipped with a compressor 1, a condenser 2, a gas/liquid separater 3, a first expanding means 4 for high-boiling point refrigerant, a heat exchanger 5 for effecting heat exchange between low-boiling point refrigerant and high-boiling point refrigerant mutually, a second expanding means 6 for low-boiling point refrigerant and an evaporator 7, is provided with a second heat exchanger 8 effecting heat exchange between liquidous high-boiling point refrigerant sent from the gas/liquid separater 3 into a first expanding means 4 and high-boiling point refrigerant returned from the heat exchanger 5 into the compressor 1 mutually. Accordingly, the liquidous high-boiling point refrigerant, sent into the first expanding means 4, is cooled by the second heat exchanger 8 to provide it with an adequate overcooling degree. Accordingly, flush gas will never be generated even when there is temperature-rise or a pressure drop on the half way of the feeding and evacuating operation while reducing/operation in a first expanding means 4 and heat exchanging effect in the heat exchanger 5 are effected optimally whereby the deterioration of refrigerating capacity can be prevented.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigeration circuit using a non-azeotropic refrigerant mixture.

0002

2. Description of the Related Art Conventionally, a refrigeration circuit shown in FIG. 2 is known in which a two-fluid non-azeotropic refrigerant mixture (a mixture of two refrigerants having different boiling points) is compressed by a single-stage compressor. In the figure, 21 is a compressor, 22 is a condenser, 23 is a gas-liquid separator, 24 is a first expansion valve for high boiling point refrigerant, 25 is a double pipe heat exchanger, and 26 is a first expansion valve for low boiling point refrigerant. 2 expansion valve, 2
7 is an evaporator.

As shown by the arrow in the figure, the non-azeotropic mixed refrigerant discharged from the compressor 21 is partially condensed in the condenser 22 and sent to the gas-liquid separator 23.
A gaseous low boiling point refrigerant is contained in the upper layer, and a liquid high boiling point refrigerant is contained in the lower layer.

The liquid high boiling point refrigerant is fed from the lower layer of the gas-liquid separator 23 to the first expansion valve 24 to be depressurized, and then fed into the flow path 25a of the heat exchanger 25, and is then fed into the other flow path 25.
It evaporates through mutual heat exchange with b and returns to the compressor 21. On the other hand, the gaseous low boiling point refrigerant is sent from the upper layer of the gas-liquid separator 23 to the flow path 25b of the heat exchanger 25, and after being condensed by mutual heat exchange with the other flow path 25a, the second expansion valve 26 where the pressure is reduced, and further into the evaporator 27 where it is evaporated and returned to the compressor 21.

[0005] In the above-mentioned refrigeration circuit, condensation and evaporation can be performed in a wide temperature range by the Lorentz cycle, and cooling can be performed with a good coefficient of performance (COP).
Ultra-low temperature cooling below 0°C can be achieved.

[0006]

However, in the above-mentioned refrigeration circuit, the first expansion valve 24 is
Since the liquid high boiling point refrigerant sent to the refrigerant is in a saturated state and has a supercooling degree of 0°C, flash gas is likely to be generated if there is a temperature rise or pressure drop during the delivery, and the pressure reducing effect at the first expansion valve 24 Another drawback is that the heat exchange action in the heat exchanger 25 cannot be performed sufficiently, resulting in a reduction in refrigerating capacity.

The present invention has been made in view of the above-mentioned problems, and its purpose is to provide a refrigeration circuit for non-azeotropic mixed refrigerants that can prevent a reduction in refrigeration capacity due to the generation of flash gas. be.

[0008]

[Means for Solving the Problems] In order to achieve the above object, claim 1 provides a compressor, a condenser for condensing a non-azeotropic mixed refrigerant discharged from the compressor, and a refrigerant condensed in the condenser. a gas-liquid separator that separates the refrigerant into a gaseous low-boiling refrigerant and a liquid high-boiling refrigerant; a first expansion means that depressurizes the liquid high-boiling refrigerant sent from the gas-liquid separator; and a high-boiling refrigerant after depressurization. A heat exchanger that mutually exchanges heat with a gaseous low boiling point refrigerant, a second expansion means that reduces the pressure of the low boiling point refrigerant after heat exchange, and an evaporator that evaporates the low boiling point refrigerant after the pressure reduction,
In a refrigeration circuit for a non-azeotropic mixed refrigerant, the high boiling point refrigerant after heat exchange and the low boiling point refrigerant after evaporation are returned to the compressor.
A second heat exchanger is provided for mutually exchanging heat between the liquid high-boiling refrigerant sent from the gas-liquid separator to the first expansion means and the high-boiling refrigerant returned from the heat exchanger to the compressor.

[0009] Also, in claim 2, the compressor, the condenser for condensing the non-azeotropic mixed refrigerant discharged from the compressor, and the refrigerant condensed in the condenser are combined with a gaseous low boiling point refrigerant and a liquid high boiling point refrigerant. a gas-liquid separator that separates the boiling-point refrigerant; a first expansion means that reduces the pressure of the liquid high-boiling refrigerant sent out from the gas-liquid separator;
A heat exchanger that mutually exchanges heat between a high boiling point refrigerant after being decompressed and a gaseous low boiling point refrigerant, a second expansion means that depressurizes the low boiling point refrigerant after heat exchange, and evaporating the low boiling point refrigerant after being depressurized. In a refrigeration circuit for a non-azeotropic mixed refrigerant that is equipped with an evaporator and returns the high boiling point refrigerant after heat exchange and the low boiling point refrigerant after evaporation to the compressor, the liquid high boiling point refrigerant sent from the gas-liquid separator is a flow divider that divides the boiling point refrigerant into two; a third expansion means that reduces the pressure of the liquid high boiling point refrigerant sent from one branch side of the flow divider; A second heat exchanger is provided for mutually exchanging heat between the boiling point refrigerant and the high boiling point refrigerant whose pressure has been reduced by the third expansion means, and compressing the high boiling point refrigerant on the one branch side that has undergone heat exchange with the second heat exchanger. I'm trying to get it back on the machine.

0010

In the refrigeration circuit according to claim 1, the liquid high-boiling refrigerant sent from the gas-liquid separator to the first expansion means and the high-boiling refrigerant returned to the compressor from the heat exchanger are transferred to the second heat exchanger. By exchanging heat with each other, the liquid high-boiling point refrigerant fed into the first expansion means can be cooled and given an appropriate degree of supercooling, and even if there is a temperature rise or pressure drop during feeding, it will not flash. Gas is difficult to generate.

In the refrigeration circuit according to the second aspect of the invention, the liquid high boiling point refrigerant sent out from the gas-liquid separator is divided into two by a flow divider,
After the pressure of the liquid high-boiling refrigerant sent from one branch side of the flow divider is reduced by the third expansion means, the reduced pressure high-boiling refrigerant and the liquid high-boiling refrigerant sent from the other flow side of the flow divider to the first expansion means are combined. By mutually exchanging heat with the boiling point refrigerant in the second heat exchanger, the liquid high boiling point refrigerant sent to the first expansion means can be cooled and given an appropriate degree of supercooling. Flash gas is difficult to generate even if there is a temperature rise or pressure drop.

0012

[Embodiment] Fig. 1 is a refrigeration circuit diagram showing one embodiment of the present invention, in which 1 is a compressor, 2 is a condenser, 3 is a gas-liquid separator, and 4 is a first expansion for high boiling point refrigerant. The valves 5 are a double-tube type first heat exchanger, 6 is a second expansion valve for a low boiling point refrigerant, 7 is an evaporator, and 8 is a double-tube type second heat exchanger.

A discharge port of the compressor 1 is connected to an inlet of a condenser 2, and an outlet of the condenser 2 is connected to an inlet of a gas-liquid separator 3. The low boiling point refrigerant outlet of the gas-liquid separator 3 is connected to the inlet of the second expansion valve 6 via one flow path 5a of the first heat exchanger 5, and the outlet of the second expansion valve 6 is connected to the inlet of the second expansion valve 6. The outlet of the evaporator 7 is connected to the inlet of the compressor 1.

Further, the high boiling point refrigerant outlet of the gas-liquid separator 3 is connected to the inlet of the first expansion valve 4 via one flow path 8a of the second heat exchanger 8, and the outlet of the first expansion valve 4 are the other flow path 5b of the first heat exchanger 5 and the other flow path 8b of the second heat exchanger 8.
are connected to the suction port of the compressor 1 through the .

As shown by the arrow in the figure, the non-azeotropic mixed refrigerant discharged from the compressor 1 is partially condensed in the condenser 2 and sent to the gas-liquid separator 3. A gaseous low boiling point refrigerant is contained in the upper layer, and a liquid high boiling point refrigerant is contained in the lower layer. In reality, the high boiling point refrigerant cannot be completely condensed in the condenser 2, so some high boiling point refrigerant gas is mixed in the upper layer of the gas-liquid separator 3, and some low boiling point refrigerant liquid is mixed in the lower layer. .

The liquid high-boiling refrigerant is sent from the high-boiling refrigerant outlet of the gas-liquid separator 3 to the flow path 8a of the second heat exchanger 8, and is cooled by mutual heat exchange with the other flow path 8b. The high boiling point refrigerant that has been condensed in the second heat exchanger 8 is depressurized in the first expansion valve 4 and then sent into the flow path 5b of the first heat exchanger 5, where it is mutually heat exchanged with the other flow path 5a. and evaporate. The high boiling point refrigerant after evaporating in the first heat exchanger 5 is transferred to the second heat exchanger 8
It is sent into the flow path 8b, exchanges heat with the other flow path 8a, and returns to the compressor 1.

On the other hand, the gaseous low boiling point refrigerant is sent from the low boiling point refrigerant outlet of the gas-liquid separator 3 to the flow path 5a of the first heat exchanger 5, and is cooled by mutual heat exchange with the other flow path 5b. After being condensed, it is sent to the second expansion valve 6 where the pressure is reduced, and further sent to the evaporator 7 where it is evaporated and returned to the compressor 1.

In this refrigeration circuit, the liquid high boiling point refrigerant sent out from the high boiling point refrigerant outlet of the gas-liquid separator 3 and the high boiling point refrigerant returned to the compressor 1 from the first heat exchanger 5 are transferred to the second heat exchanger 3. By exchanging heat with each other in step 8, the liquid high-boiling point refrigerant fed into the first expansion means 4 can be cooled and given an appropriate degree of supercooling, so even if there is a temperature rise or pressure drop during feeding, it will not flash. No gas is generated. This makes it possible to properly perform the pressure reduction action in the first expansion valve 4 and the heat exchange action in the first heat exchanger 5 to prevent a decrease in refrigerating capacity. Refrigeration capacity can be improved by that amount.

FIG. 3 is a refrigeration circuit diagram showing another embodiment of the present invention, in which 11 is a compressor, 12 is a condenser,
13 is a gas-liquid separator, 14 is a first expansion valve for high boiling point refrigerant,
15 is a double tube type first heat exchanger, 16 is a second expansion valve for low boiling point refrigerant, 17 is an evaporator, 18 is a flow divider, 19 is a third expansion valve for high boiling point refrigerant, 20 is 2 This is a double-tube type second heat exchanger.

A discharge port of the compressor 11 is connected to an inlet of a condenser 12, and an outlet of the condenser 12 is connected to an inlet of a gas-liquid separator 13. The low boiling point refrigerant outlet of the gas-liquid separator 13 is connected to the inlet of the second expansion valve 16 via one flow path 15a of the first heat exchanger 15, and the outlet of the second expansion valve 16 is connected to the inlet of the second expansion valve 16. The outlet of the evaporator 17 is connected to the inlet of the compressor 11.

Further, the high boiling point refrigerant outlet of the gas-liquid separator 13 is connected to the inlet of a flow divider 18, and one outlet of the flow divider 18 (upper side in the figure) is connected to one flow path of the second heat exchanger 20. 20a
The outlet of the first expansion valve 14 is connected to the suction port of the compressor 1 via the other flow path 15b of the first heat exchanger 15. Further, the other (lower side in the figure) outlet of the flow divider 18 is connected to the inlet of a third expansion valve 19, and the outlet of the third expansion valve 19 is connected to the other flow path 20b of the second heat exchanger 20. and is connected to the suction port of the compressor 1.

As shown by the arrow in the figure, the non-azeotropic mixed refrigerant discharged from the compressor 11 is partially condensed in the condenser 12 and sent to the gas-liquid separator 13.
A gaseous low boiling point refrigerant is contained in the upper layer, and a liquid high boiling point refrigerant is contained in the lower layer. In reality, the high boiling point refrigerant cannot be completely condensed in the condenser 12, so some high boiling point refrigerant gas is mixed in the upper layer of the gas-liquid separator 13, and some low boiling point refrigerant liquid is mixed in the lower layer. .

The liquid high-boiling refrigerant is sent from the high-boiling refrigerant outlet of the gas-liquid separator 13 to the flow divider 18 and divided into two parts. The liquid high boiling point refrigerant sent out from the upper outlet of the flow divider 18 is sent into the flow path 20a of the second heat exchanger 20,
It is cooled by mutual heat exchange with the other flow path 20b. After being cooled in the second heat exchanger 20, the high boiling point refrigerant is depressurized in the first expansion valve 14 and then sent into the flow path 15b of the first heat exchanger 15, where it exchanges heat with the other flow path 15a. It evaporates during exchange and returns to compressor 1. Further, the liquid high boiling point refrigerant sent out from the lower outlet of the flow divider 18 is depressurized by the third expansion valve 19 and then sent into the flow path 20b of the second heat exchanger 20,
It exchanges heat with the other flow path 20a, evaporates, and returns to the compressor 1.

On the other hand, the gaseous low boiling point refrigerant flows from the low boiling point refrigerant outlet of the gas-liquid separator 13 to the flow path 15 of the first heat exchanger 15.
a, is cooled and condensed by heat exchange with the other flow path 15b, and then sent to the second expansion valve 16 to be depressurized, and further sent to the evaporator 17, where it evaporates and becomes the compressor 11.
Return to

In this refrigeration circuit, the liquid high boiling point refrigerant sent out from the gas-liquid separator 13 is divided into two by the flow divider 18, and the liquid high boiling point refrigerant sent out from the lower outlet of the flow divider 18 is subjected to a third expansion. After the pressure is reduced by the means 19, the high boiling point refrigerant after the pressure reduction and the liquid high boiling point refrigerant sent out from the upper outlet of the flow divider 18 are exchanged with each other in the second heat exchanger 20. Since the liquid high boiling point refrigerant fed into the refrigerant 14 can be cooled and given an appropriate degree of supercooling, flash gas will not be generated even if there is a temperature rise or pressure drop during the feeding. This makes it possible to appropriately perform the pressure reduction action in the first expansion valve 14 and the heat exchange action in the first heat exchanger 15 to prevent a decrease in refrigerating capacity, and also to prevent the refrigerating capacity from decreasing due to the supercooling obtained in the second heat exchanger 20. Refrigeration capacity can be improved by that amount.

The double tube type heat exchangers shown in the examples may be of other types as long as they can exchange heat between the refrigerants, and if necessary, the compressor An accumulator may be provided on the suction port side of the pump, or a condenser blower or an evaporator blower may be installed.

[0027]

As described in detail above, according to the refrigeration circuit according to claim 1, the liquid high-boiling refrigerant sent out from the gas-liquid separator and the high-boiling refrigerant returned to the compressor from the heat exchanger can be combined. The second heat exchanger exchanges heat with each other and cools the liquid high-boiling refrigerant fed into the first expansion means to give it an appropriate degree of supercooling, so there is no temperature rise or pressure drop during feeding. Even if there is, no flash gas is generated,
In addition to being able to properly perform the pressure reduction action in the first expansion means and the heat exchange action in the heat exchanger to prevent a decrease in refrigeration capacity, the advantage is that the refrigeration capacity can be improved by the amount of supercooling obtained by the second heat exchanger. There is.

Furthermore, according to the refrigeration circuit according to claim 2,
The liquid high-boiling point refrigerant sent out from the gas-liquid separator is divided into two by a flow divider, and the liquid high-boiling point refrigerant sent out from the one branch side of the flow divider is depressurized by the third expansion means, and then the high-boiling point refrigerant and the high-boiling point refrigerant are separated. A second heat exchanger mutually exchanges heat with the liquid high-boiling refrigerant sent from the other branch side of the divider, and cools the saturated liquid of the high-boiling refrigerant sent to the first expansion means to achieve appropriate supercooling. Since the temperature is given a certain temperature, flash gas will not be generated even if there is a temperature rise or pressure drop during feeding, and the pressure reduction action in the first expansion means and the heat exchange action in the heat exchanger are performed appropriately. In addition to being able to prevent a decrease in capacity, there is an advantage that refrigeration capacity can be improved by the amount of supercooling obtained by the second heat exchanger.

[Brief explanation of drawings]

[Fig. 1] Refrigeration circuit diagram showing one embodiment of the present invention

[Figure 2] Refrigeration circuit diagram showing a conventional example

[Fig. 3] Refrigeration circuit diagram showing another embodiment of the present invention

[Explanation of symbols]

1... Compressor, 2... Condenser, 3... Gas-liquid separator, 4... First expansion valve, 5... First heat exchanger, 6... Second expansion valve, 7... Evaporator, 8... Second heat exchanger vessel, 11...compressor, 12...condenser, 1
3... Gas-liquid separator, 14... First expansion valve, 15... First heat exchanger, 16... Second expansion valve, 17... Evaporator, 18... Flow divider,
19... Third expansion valve, 20... Second heat exchanger.

Claims (2)

[Claims] Claim 1: A compressor, a condenser for condensing a non-azeotropic mixed refrigerant discharged from the compressor, and separating the refrigerant condensed by the condenser into a gaseous low boiling point refrigerant and a liquid high boiling point refrigerant. A gas-liquid separator, a first expansion means for reducing the pressure of the liquid high-boiling refrigerant sent from the gas-liquid separator, and a heat exchanger for mutually exchanging heat between the high-boiling refrigerant after depressurization and the gaseous low-boiling refrigerant. , a second expansion means for reducing the pressure of the low boiling point refrigerant after heat exchange, and an evaporator for evaporating the low boiling point refrigerant after pressure reduction, and compressing the high boiling point refrigerant after heat exchange and the low boiling point refrigerant after evaporation. In a refrigeration circuit for a non-azeotropic mixed refrigerant that is returned to the compressor, the liquid high-boiling refrigerant sent from the gas-liquid separator to the first expansion means and the high-boiling refrigerant returned to the compressor from the heat exchanger are mutually connected. A refrigeration circuit for a non-azeotropic mixed refrigerant, characterized in that a second heat exchanger is provided for exchanging heat with the refrigerant. Claim 2: A compressor, a condenser for condensing a non-azeotropic mixed refrigerant discharged from the compressor, and separating the refrigerant condensed in the condenser into a gaseous low boiling point refrigerant and a liquid high boiling point refrigerant. A gas-liquid separator, a first expansion means for reducing the pressure of the liquid high-boiling refrigerant sent from the gas-liquid separator, and a heat exchanger for mutually exchanging heat between the high-boiling refrigerant after depressurization and the gaseous low-boiling refrigerant. , a second expansion means for reducing the pressure of the low boiling point refrigerant after heat exchange, and an evaporator for evaporating the low boiling point refrigerant after pressure reduction, and compressing the high boiling point refrigerant after heat exchange and the low boiling point refrigerant after evaporation. In a refrigeration circuit for non-azeotropic mixed refrigerant that is returned to the machine, there is a flow divider that divides the liquid high-boiling refrigerant sent out from the gas-liquid separator into two, and a liquid high-boiling point refrigerant sent out from one branch side of the flow divider. A third expansion means for reducing the pressure of the refrigerant, a liquid high boiling point refrigerant sent from the other branch side of the flow divider to the first expansion means, and a third expansion means for reducing the pressure of the refrigerant.
A second heat exchanger is provided to mutually exchange heat with the high boiling point refrigerant whose pressure has been reduced by the expansion means, and the high boiling point refrigerant on the one branch side that has been heat exchanged with the second heat exchanger is returned to the compressor. A refrigeration circuit for a non-azeotropic mixed refrigerant characterized by: