JP2009156543A - Refrigeration system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a refrigeration system improving a coefficient of performance (COP) and as a result, refrigeration capacity in a refrigeration system using a non-azeotropic mixed refrigerant. <P>SOLUTION: When using the non-azeotropic mixed refrigerant as a refrigerant, a state of the refrigerant in an evaporator outlet side (point A) is brought within a saturated steam zone. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a refrigeration system using a non-azeotropic refrigerant mixture.

In recent years, for example, in the field of stationary air conditioning equipment, refrigeration systems using non-azeotropic refrigerant mixtures have been developed.
In such a refrigeration system, the non-azeotropic refrigerant mixture has a characteristic that the saturation temperature changes depending on the dryness of the refrigerant even in a state of constant pressure in the saturated vapor region. The phenomenon peculiar to is generally called temperature slip.

However, when such a temperature slip occurs, in a heat exchanger such as a condenser or an evaporator, the temperature difference between the refrigerant and the heat source medium becomes small along with the flow of the refrigerant, and the performance of the heat exchanger is deteriorated. is there.
Therefore, in order to solve such a problem, in the field of stationary air conditioning equipment, for example, the flow of the refrigerant and the flow of the heat source medium are made to counterflow, so that the performance of the heat exchanger is improved (patent document). 1).
JP 7-208822 A

Recently, the use of a non-azeotropic refrigerant mixture has been studied not only in the field of stationary air conditioners but also in the field of vehicle air conditioners.
However, in the field of vehicle air-conditioning equipment, there are large installation space and structural restrictions, and it is difficult to adopt a method in which the refrigerant flow and the heat source medium flow are opposed to each other as disclosed in Patent Document 1 above. It is often unrealistic.

For this reason, for example, an internal heat exchanger is provided so that heat can be exchanged between the high-temperature refrigerant on the condenser outlet side and the low-temperature refrigerant on the evaporator outlet side, and the action of the internal heat exchanger causes the refrigerant in the evaporator to be exchanged. A refrigeration system having a configuration that ensures an enthalpy difference has been proposed.
However, in such a refrigeration system using an internal heat exchanger, the refrigerant suction temperature of the compressor rises, resulting in an increase in discharge temperature, a decrease in volumetric efficiency, and the like. There is a problem that it does not lead to improvement.

  The present invention has been made in view of such a problem, and an object of the present invention is to provide a refrigeration system that improves the coefficient of performance (COP) and thus the refrigeration capacity in a refrigeration system using a non-azeotropic refrigerant mixture. To do.

  In order to achieve the above object, a refrigeration system according to claim 1 includes a compressor that sucks and compresses a refrigerant, a radiator that dissipates and cools the compressed refrigerant, and a decompressor that decompresses the cooled refrigerant. A refrigeration system comprising an evaporator for evaporating the decompressed refrigerant, wherein a non-azeotropic refrigerant mixture is used as the refrigerant, and the state of the refrigerant on the evaporator outlet side is in a saturated vapor region, To do.

According to a second aspect of the present invention, the refrigeration system according to the first aspect includes an internal heat exchanger for exchanging heat between the refrigerant on the condenser outlet side and the refrigerant on the evaporator outlet side.
According to a third aspect of the present invention, in the refrigeration system according to the first or second aspect, an evaporator outlet temperature detecting means for detecting a refrigerant temperature on the evaporator outlet side, and a decompressor control means for controlling an opening area of the decompressor. The decompressor control means controls the opening area of the decompressor according to the refrigerant temperature information from the evaporator outlet temperature detection means, and sets the state of the refrigerant on the evaporator outlet side in the saturated vapor region. It is characterized by keeping at.

  According to a fourth aspect of the present invention, there is provided the refrigeration system according to the second aspect, wherein in the second aspect, the internal heat exchanger outlet temperature detecting means for detecting the refrigerant temperature on the evaporator outlet side and on the internal heat exchanger outlet side, A pressure reducer control means for controlling the area, the pressure reducer control means controls an opening area of the pressure reducer according to refrigerant temperature information from the internal heat exchanger outlet temperature detection means, and the internal heat The superheat degree of the refrigerant on the outlet side of the exchanger is suppressed within a predetermined range.

  The refrigeration system according to a fifth aspect is characterized in that the refrigeration system according to any one of the first to fourth aspects is used for a vehicle air conditioner.

  According to the refrigeration system of claim 1, when the non-azeotropic refrigerant mixture is used as the refrigerant, the state of the refrigerant on the evaporator outlet side is set in the saturated vapor region. As described above, a temperature slip phenomenon occurs in which the saturation temperature changes depending on the dryness of the refrigerant even in a state of constant pressure in the saturated vapor region. However, such a temperature slip (temperature gradient) occurs. However, by setting the state of the refrigerant on the outlet side of the evaporator within the saturated vapor region, it is possible to minimize the temperature difference between the refrigerant and the heat source medium, and to suppress overheating (superheat) of the refrigerant, so that the refrigerant of the compressor An increase in inhalation temperature can be prevented.

Thereby, even when a non-azeotropic refrigerant mixture is used as the refrigerant, it is possible to prevent a reduction in the efficiency of the compressor, and it is possible to improve the coefficient of performance (COP) and thus the refrigeration capacity.
According to the refrigeration system of claim 2, even when the refrigerant on the condenser outlet side and the refrigerant on the evaporator outlet side are heat-exchanged by the internal heat exchanger, the state of the refrigerant on the evaporator outlet side In the saturated vapor region, the temperature difference between the refrigerant and the heat source medium can be kept as small as possible, and the refrigerant intake temperature can be prevented by preventing the refrigerant from overheating (superheat). (COP) As a result, the refrigerating capacity can be improved.

  According to the refrigeration system of claim 3, when a non-azeotropic refrigerant mixture is used, a temperature change of the refrigerant on the evaporator outlet side can be detected in the saturated vapor region using a temperature slip (temperature gradient). Therefore, the evaporator outlet temperature detecting means detects the refrigerant temperature on the evaporator outlet side, and the opening area of the decompressor is controlled according to the refrigerant temperature information from the evaporator outlet temperature detecting means. It is possible to easily maintain the state of the refrigerant on the side in the saturated vapor region.

  According to the refrigeration system of claim 4, the opening area of the decompressor is controlled according to the refrigerant temperature information from the internal heat exchanger outlet temperature detection means, and the refrigerant is overheated on the evaporator outlet side and the internal heat exchanger outlet side. By keeping the temperature within the specified range, the degree of superheating of the refrigerant at the outlet side of the internal heat exchanger that has passed through the evaporator can be made appropriate, and the refrigerant intake temperature of the compressor can be increased by suppressing the superheating of the refrigerant. Thus, the temperature difference between the refrigerant and the heat source medium can be kept as small as possible by making the state of the refrigerant on the evaporator outlet side in the saturated vapor region.

  According to the refrigeration system of claim 5, even when a non-azeotropic refrigerant mixture is used for the vehicle air conditioner, the efficiency of the compressor can be prevented from being reduced without any restrictions on installation space or structure, and the coefficient of performance (COP) ) As a result, the refrigeration capacity can be improved.

Embodiments of the present invention will be described below with reference to the drawings.
First, Example 1 will be described.
FIG. 1 shows a schematic configuration diagram of a refrigeration system according to Embodiment 1 of the present invention, and the configuration of the refrigeration system according to Embodiment 1 will be described below based on the same drawing.
The refrigeration system according to the present invention is applied to a refrigeration / air conditioning cycle of a vehicle air conditioner, and particularly uses a non-azeotropic refrigerant mixture (for example, R407C) as a refrigerant.

  As shown in the figure, the refrigeration system according to the first embodiment of the present invention is mounted on a vehicle, and includes a compressor 10 that compresses refrigerant, a radiator 12 that radiates and cools the boosted refrigerant, and a radiator. An expansion valve (decompressor) 14 that is located downstream of the refrigerant 12 and decompresses and expands the refrigerant cooled by the radiator 12 and an evaporator 16 that evaporates the refrigerant depressurized and expanded by the expansion valve 14 are sequentially connected by piping. Configured.

The outlet pipe of the radiator 12 is provided with a receiver 13 that stores excess refrigerant. The outlet pipe of the evaporator 16 is an evaporator that detects the temperature of the refrigerant on the outlet side of the evaporator 16. An evaporator outlet temperature sensor (evaporator outlet temperature detecting means) 18 is provided.
The expansion valve 14 has a control mechanism capable of adjusting the degree of pressure reduction by opening and closing the valve body and varying the opening area, and opens and closes the valve body based on temperature information from the evaporator outlet temperature sensor 18. The opening area is configured so that the opening area can be appropriately controlled by a control mechanism.

Hereinafter, the effect of the refrigeration system according to the first embodiment of the present invention configured as described above will be described.
FIG. 2 shows a ph diagram (Mollier diagram) of the refrigeration system according to the first embodiment of the present invention, which will be described below with reference to FIG.
As shown in FIG. 2, in a refrigeration system using a non-azeotropic refrigerant mixture, even if the pressure is constant in the saturated vapor region, this is called a characteristic that the refrigerant temperature rises with an increase in dryness, that is, temperature slip. It has the characteristics that indicate the phenomenon.

  Therefore, in the case of a refrigeration system using a single refrigerant or an azeotropic refrigerant (for example, R134a, R410A, etc.), if the pressure loss is ignored, the heat exchanger such as the radiator 12 or the evaporator 16 is in the saturated vapor region. While the temperature difference between the refrigerant and the heat source medium is kept constant, in the case of a non-azeotropic refrigerant mixture, the temperature of the refrigerant increases in the evaporator 16 as it progresses in the refrigerant flow direction. In this case, the temperature of the refrigerant decreases, and in either case, the temperature difference between the refrigerant and the heat source medium tends to be small.

In the refrigeration / air conditioning cycle of the air conditioner, the saturated vapor region is often exceeded, that is, superheated with a degree of superheat. In this way, the refrigerant, the heat source medium, The above-mentioned tendency for the temperature difference to become smaller becomes more remarkable, and there arises a problem that the refrigerant suction temperature of the compressor 10 rises.
However, as described above, in the non-azeotropic refrigerant mixture, a phenomenon of temperature slip occurs even if the pressure is constant in the saturated vapor region. Therefore, evaporation occurs in the saturated vapor region using this temperature slip (temperature gradient). The temperature change of the refrigerant on the outlet side of the vessel 16 can be detected. Therefore, the evaporator outlet temperature sensor 18 detects the refrigerant temperature on the outlet side of the evaporator 16, and the opening area of the expansion valve 14 is controlled by the control mechanism according to the refrigerant temperature information. It is possible to easily maintain the state of the refrigerant, i.e., the dryness of the refrigerant, in the saturated vapor region (reducer control means).

For this reason, the valve element of the expansion valve 14 is operated to open and close based on the temperature information from the evaporator outlet temperature sensor 18, and the opening area is manipulated, as shown in FIG. Control is performed so that the state of the refrigerant at point A), that is, the dryness of the refrigerant falls within the saturated vapor region.
When the state of the refrigerant on the outlet side of the evaporator 16 is controlled in this way, the refrigerant temperature inside the evaporator 16 is generally low if the pressure is the same as compared with the case where the superheat degree is given as described above. Thus, the temperature difference between the refrigerant flowing in the evaporator 16 and the heat source medium is enlarged, and the temperature difference can be kept as small as possible, and the refrigerant suction temperature of the compressor 10 can be kept low.

Thereby, the fall of the heat exchange efficiency of the evaporator 16 can be prevented, and a coefficient of performance (COP) and by extension, a refrigerating capacity can be aimed at.
In addition, although the liquid back to the compressor 10 may occur because the state of the refrigerant on the outlet side of the evaporator 16 is in the saturated vapor region, in a vehicle air conditioner, components are generally connected. Since the piping is exposed to the high temperature in the engine room, the refrigerant is in the process from the outlet of the evaporator 16 to the inlet of the compressor 10 even if the state of the refrigerant is in the saturated vapor region on the outlet side of the evaporator 16. It is heated by heat exchange with ambient air and becomes superheated steam at the inlet of the compressor 10. Even in this case, since the degree of superheat of the refrigerant is very small, the refrigerant suction temperature of the compressor 10 and thus the refrigerant discharge temperature can be sufficiently reduced.

Next, Example 2 will be described.
FIG. 3 shows a schematic configuration diagram of the refrigeration system according to the second embodiment of the present invention. The configuration of the refrigeration system according to the second embodiment will be described below with reference to FIG.
The second embodiment is different from the first embodiment in that the internal heat exchanger 20 is provided. Hereinafter, the description of the common parts with the first embodiment will be omitted, and only the different parts will be described.

  As shown in the figure, the refrigeration system according to the second embodiment of the present invention includes a pipe connecting the outlet side of the radiator 12 and the inlet side of the expansion valve 14, the outlet side of the evaporator 16, and the inlet of the compressor 10. It comprises an internal heat exchanger 20 that makes contact with a pipe communicating with the side. Thus, in the refrigeration system according to the second embodiment, the internal heat exchanger 20 can exchange heat between the refrigerant on the outlet side of the radiator 12 and the refrigerant on the outlet side of the evaporator 16.

Hereinafter, the operation and effect of the refrigeration system according to the second embodiment of the present invention configured as described above will be described.
In FIG. 4, the ph diagram (Mollier diagram) of the refrigeration system according to Example 2 of the present invention is shown in comparison with the refrigeration cycle (broken line) using the conventional internal heat exchanger, This will be described below with reference to FIG.

As shown in the figure, the enthalpy at the inlet of the evaporator 16 is reduced by exchanging heat between the refrigerant on the outlet side of the radiator 12 and the refrigerant on the outlet side of the evaporator 16 by the internal heat exchanger 20. .
As described above, in the non-azeotropic refrigerant mixture, the temperature of the refrigerant decreases as the dryness decreases even at the same pressure in the saturated vapor region. Therefore, by reducing the enthalpy at the inlet of the evaporator 16 in this way, the temperature difference with the heat source medium in the evaporator 16 is expanded, the heat exchange efficiency of the evaporator 16 is improved, and the coefficient of performance (COP) and thus the refrigerating capacity are improved. Can be improved.

Further, similarly to the above, based on the temperature information from the evaporator outlet temperature sensor 18, the valve body of the expansion valve 14 is opened and closed to manipulate the opening area, and as shown in FIG. Control is performed so that the state of the refrigerant at point B) in FIG. 4, that is, the dryness of the refrigerant falls within the saturated vapor region.
Thereby, also in the case of Example 2, the effect similar to the above is produced, the fall of the heat exchange efficiency of the evaporator 16 can be prevented, and the coefficient of performance (COP) and thus the refrigerating capacity can be further improved.

Next, Example 3 will be described.
FIG. 5 shows a schematic configuration diagram of a refrigeration system according to a third embodiment of the present invention. Hereinafter, the configuration of the refrigeration system according to the third embodiment will be described with reference to FIG.
In the third embodiment, the position of the temperature sensor is different from that of the second embodiment. Hereinafter, the description of the common parts with the first and second embodiments is omitted, and only the different parts are described.

  As shown in the figure, the refrigeration system according to the third embodiment of the present invention is similar to the second embodiment described above, the pipe connecting the outlet side of the radiator 12 and the inlet side of the expansion valve 14 and the outlet of the evaporator 16. The evaporator outlet temperature sensor 18 detects the temperature of the refrigerant on the outlet side of the evaporator 16, but includes an internal heat exchanger 20 that makes contact with the pipe that communicates the inlet side with the inlet side of the compressor 10. Instead, an internal heat exchanger outlet temperature sensor (internal heat exchanger outlet temperature detection means) 19 for detecting the temperature of the refrigerant on the outlet side of the evaporator 16 and on the outlet side of the internal heat exchanger 20 is provided. Yes.

Hereinafter, the operation and effect of the refrigeration system according to Embodiment 3 of the present invention configured as above will be described.
Also in the third embodiment, as in the second embodiment, the enthalpy at the inlet of the evaporator 16 is reduced by the action of the internal heat exchanger 20, thereby reducing the heat exchange efficiency of the evaporator 16. It is possible to improve and improve the coefficient of performance (COP) and thus the refrigerating capacity.

  On the other hand, in the third embodiment, the opening area is manipulated by opening and closing the valve body of the expansion valve 14 based on the temperature information from the internal heat exchanger outlet temperature sensor 19 instead of the temperature information from the evaporator outlet temperature sensor 18. As shown in FIG. 4, the degree of superheat of the refrigerant on the outlet side (point C in FIG. 4) of the internal heat exchanger 20 on the low-pressure side that has passed through the evaporator 16 falls within a predetermined range (for example, 10 ° C.). To control.

In this way, the degree of superheat on the outlet side of the low-pressure side internal heat exchanger 20 can be properly controlled, and the refrigerant superheat (superheat) that occurs in a refrigeration system using a conventional internal heat exchanger can be controlled. ) And the rise of the refrigerant suction temperature at the compressor inlet can be reliably prevented.
In this case, similarly to the above, the refrigerant on the inlet side of the low-pressure side internal heat exchanger 20, that is, the outlet side of the evaporator 16, can be kept in the saturated vapor region, and the temperature difference between the refrigerant and the heat source medium can be kept. It can be made as small as possible.

Thereby, the fall of the heat exchange efficiency of the evaporator 16 can be prevented satisfactorily, and the coefficient of performance (COP) and thus the refrigerating capacity can be further improved.
The description of one embodiment of the present invention has been completed above, but the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, in the above embodiment, the receiver 13 is provided, but may be omitted as necessary.

1 is a schematic configuration diagram of a refrigeration system according to Embodiment 1 of the present invention. It is a ph diagram of the refrigeration system concerning Example 1 of the present invention. It is a schematic block diagram of the refrigeration system which concerns on Example 2 of this invention. It is a ph diagram of a refrigeration system concerning Examples 2 and 3 of the present invention. It is a schematic block diagram of the refrigeration system which concerns on Example 3 of this invention.

Explanation of symbols

10 Compressor 12 Radiator 14 Expansion Valve (Decompressor)
16 Evaporator 18 Evaporator outlet temperature sensor (Evaporator outlet temperature detection means)
19 Internal heat exchanger outlet temperature sensor (Internal heat exchanger outlet temperature detection means)
20 Internal heat exchanger

Claims (5)

A refrigerating machine comprising a compressor that sucks and compresses a refrigerant, a radiator that radiates and cools the compressed refrigerant, a decompressor that decompresses the cooled refrigerant, and an evaporator that evaporates the decompressed refrigerant. In the system,
Use a non-azeotropic refrigerant mixture as the refrigerant,
A refrigeration system characterized in that the state of the refrigerant on the outlet side of the evaporator is in a saturated vapor region.   The refrigeration system according to claim 1, further comprising an internal heat exchanger that exchanges heat between the refrigerant at the condenser outlet side and the refrigerant at the evaporator outlet side. An evaporator outlet temperature detecting means for detecting the refrigerant temperature on the evaporator outlet side, and a decompressor control means for controlling an opening area of the decompressor;
The decompressor control means controls the opening area of the decompressor according to the refrigerant temperature information from the evaporator outlet temperature detection means, and keeps the state of the refrigerant on the evaporator outlet side in the saturated vapor region. The refrigeration system according to claim 1 or 2, characterized by the above. An internal heat exchanger outlet temperature detecting means for detecting a refrigerant temperature on the evaporator outlet side and on the internal heat exchanger outlet side, and a decompressor control means for controlling an opening area of the decompressor,
The pressure reducer control means controls the opening area of the pressure reducer according to the refrigerant temperature information from the internal heat exchanger outlet temperature detection means, and the degree of superheat of the refrigerant on the internal heat exchanger outlet side is within a predetermined range. The refrigeration system according to claim 2, wherein   The refrigeration system according to any one of claims 1 to 4, wherein the refrigeration system is used in a vehicle air conditioner.

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