JPH0875290A - Heat pump type air conditioner - Google Patents

Abstract

PURPOSE: To improve capability during a heating operation and a capability during a cooling operation and further to improve a coefficient of work by providing an auxiliary heat exchanger for heat exchanging between refrigerant between an indoor- outdoor connecting liquid pipe of a heat pump type air conditioner which encloses non-azeotropic mixture refrigerant and refrigerant sucked into a compressor. CONSTITUTION: In a heat pump type air conditioner which encloses non-azeotropic mixture refrigerant, an auxiliary heat exchanger 10 performs a heat exchanging operation between a liquid cooling refrigerant pipe 11 between a pipe coupler 6a and an electric expansion valve 7 and a low pressure pipe 12 between a four-way valve 2 and a compressor 1. The auxiliary heat exchanger 10 is of a double-pipe type in which the low pressure pipe 12 is applied as an inner pipe and the liquid refrigerant pipe 11 is applied as an outer pipe. An outer circumference of the outer pipe is covered by a heat insulating material. In order to promote a heat transfer, an inner surface of the pipe and an outer surface of the pipe are provided with helical grooves. In addition, in order to promote a heat transfer, the liquid refrigerant pipe 11 and the low pressure pipe 12 having helical grooves at their inner surfaces are made to approach other and connected to each other and they are covered by the heat insulating material and they may be heat exchanged from each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat pump type air conditioner using a non-azeotropic mixed refrigerant.

[0002]

2. Description of the Related Art In addition to CFCs for protecting the ozone layer,
Regulations on HCFCs are being tightened. HCFC22 is
At present, it is widely used as a refrigerant for air conditioning refrigeration equipment.
HFCs that do not destroy the ozone layer as alternatives to HCFC22
Among these, a non-azeotropic mixed refrigerant in which HFC32, HFC125, HFC134a, etc. are mixed is considered. Currently, an evaluation test is being performed when a non-azeotropic mixed refrigerant is used in a conventional HCFC22 device. Evaluation test results are published by The Japan Refrigeration Association, Refrigeration Vol. 69, No. 795, 1994.
It is described on pages 100 to 111 of the monthly issue.

[0003]

[Problems to be Solved by the Invention] HCFC which is a conventional machine
When a non-azeotropic mixed refrigerant which is a substitute candidate is used for the heat pump type air conditioner for 22, the capacity and the coefficient of performance (COP) are lower than those of the HCFC22 during the heating operation and the cooling operation. The non-azeotropic mixed refrigerant has a characteristic of causing a temperature change in the evaporation and condensation processes, and it is considered that this is a factor of reducing the performance of the heat exchanger and reducing the COP.

An object of the present invention is to improve the capacity and COP of a heat pump type air conditioner using a non-azeotropic mixed refrigerant both during heating operation and during cooling operation.

[0005]

[Means for Solving the Problems] The first aspect of the invention is to connect a compressor, a four-way valve, an indoor / outdoor connecting gas pipe, an indoor heat exchanger, an indoor / outdoor connecting liquid pipe, a pressure reducer, and an outdoor heat exchanger. In a heat pump type air conditioner in which a boiling mixed refrigerant is enclosed, an auxiliary heat exchanger for exchanging heat between the refrigerant between the indoor / outdoor connecting liquid pipe and the pressure reducer and the refrigerant sucked into the compressor is provided.

The second invention is a heat pump type air conditioner in which a compressor, a four-way valve, an indoor heat exchanger, a pressure reducer and an outdoor heat exchanger are connected and a non-azeotropic mixed refrigerant is enclosed. A pressure reducer and a second pressure reducer are provided, and an auxiliary heat exchanger for exchanging heat between the refrigerant between the first pressure reducer and the second pressure reducer and the refrigerant sucked into the compressor is provided.

A third invention is a heat pump type air conditioner in which a compressor, a four-way valve, an indoor heat exchanger, a liquid receiver, a decompressor and an outdoor heat exchanger are connected to each other and a non-azeotropic mixed refrigerant is enclosed in the expansion valve. The refrigerant in the liquid receiver provided on the inflow side and the refrigerant sucked into the compressor are heat-exchanged.

[0008]

With the above construction, the inlet dryness of the heat exchanger functioning as an evaporator can be made smaller than before in both heating operation and cooling operation. The pressure can be increased. Therefore, due to the increase in the evaporation pressure, the specific volume of the compressor suction gas refrigerant decreases, and the heating capacity and the cooling capacity can be increased.
Further, the increase of the evaporation pressure reduces the compression work per unit mass, which improves the COP on the Mollier diagram, and the reduction of the compression ratio improves the total adiabatic efficiency of the compressor.
Therefore, the CO of the air conditioner during heating operation and cooling operation
P can be improved.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a heat pump type air conditioner according to a first embodiment of the present invention. 4 and 5 show the operating states of the heat pump type air conditioner of the present invention during the heating operation and the cooling operation, respectively, on the Mollier diagram.

In FIG. 1, 1 is a compressor for compressing a refrigerant, 2 is a four-way valve for switching between hot and cold switching, 3a is a pipe joint, 3 is an indoor / outdoor connecting gas pipe, 3b is a pipe joint, 4 is an indoor heat exchanger. 5 is a blower for an indoor heat exchanger, 6b is a pipe joint, 6 is an indoor / outdoor connecting liquid pipe, 6a is a pipe joint, 7 is an electric expansion valve as a pressure reducer, 8 is an outdoor heat exchanger, and 9 is an outdoor heat exchanger. The blower 10 is an auxiliary heat exchanger, and is provided with a liquid refrigerant pipe 11 between the pipe joint 6a and the electric expansion valve 7 and a low pressure pipe 12 between the four-way valve 2 and the compressor 1 so that heat can be exchanged. A, B
Indicates an outdoor unit and an indoor unit, respectively. A non-azeotropic mixed refrigerant is enclosed as a refrigerant, and flows in a solid arrow direction during heating operation and flows in a broken arrow direction during cooling operation.

A specific structure of the auxiliary heat exchanger 10 is shown in FIG. The low-pressure pipe 12 is an inner pipe, and the liquid refrigerant pipe 11 is an outer pipe, which is a double pipe type, and the outer periphery of the outer pipe is a heat insulating material 13.
Covered with. Helical grooves are provided on the inner surface and the outer surface of the inner tube to promote heat transfer. Also, FIG.
As shown in, the liquid refrigerant pipe 11 and the low-pressure pipe 12 each having a spiral groove on the inner surface for advancing heat transfer are brought close to each other and joined,
It may be covered with the heat insulating material 13 to allow heat exchange. In order to accelerate the heat transfer of the heat transfer tube, a spiral groove for improving the heat transfer characteristics by the stirring effect of the refrigerant may be provided, and protrusions having the same effect or fins for expanding the heat transfer area may be provided.

The operation state of the heat pump type air conditioner thus configured will be described separately for the heating operation and the cooling operation. First, the operating state during the heating operation will be described with reference to FIGS. The gas refrigerant having the pressure P1 and the enthalpy h1 is compressed by the compressor 1 to become the pressure P2 and the enthalpy h2, and the four-way valve 2 and the pipe joint 3 are provided as indicated by the solid arrow in FIG.
a, the indoor / outdoor connection gas pipe 3, the pipe joint 3b, the indoor heat exchanger 4, and the heat sent to the air sent by the indoor heat exchanger blower 5 is condensed and condensed into the pressure P2, the enthalpy h3.
It becomes the liquid refrigerant of. This high-temperature liquid refrigerant passes through the pipe joint 6b, the indoor / outdoor connecting liquid pipe 6, and the pipe joint 6a, and then the liquid refrigerant pipe 1
1, the auxiliary heat exchanger 10 exchanges heat with the low-temperature liquid gas two-phase refrigerant in the low-pressure pipe 12 and is cooled to become enthalpy h4. Next, this liquid refrigerant is decompressed to P1 by the electric expansion valve 7 to become a liquid gas two-phase refrigerant, and enters the outdoor heat exchanger 8,
The air sent from the outdoor heat exchanger blower 9 absorbs heat from the air and evaporates to become enthalpy h5. The low-temperature liquid-gas two-phase refrigerant that has exited the outdoor heat exchanger 8 enters the low-pressure pipe 12 via the four-way valve 2 and is heated in the auxiliary heat exchanger 10 by exchanging heat with the high-temperature liquid refrigerant in the liquid-refrigerant pipe 11. It becomes enthalpy h1 and returns to compressor 1. In this embodiment, the state of the refrigerant at each position is specifically described as a liquid refrigerant, a liquid gas two-phase refrigerant, and a gas refrigerant, but the state of the refrigerant changes depending on the operating state.

As compared with the conventional example shown by the broken line in FIG.
In the present invention, during the heating operation, the dryness of the refrigerant at the inlet of the outdoor heat exchanger 8 serving as an evaporator can be reduced, and the evaporation pressure can be increased when the same inlet temperature is used. Therefore, due to the increase in the evaporation pressure, the specific volume of the compressor suction gas refrigerant decreases, and the heating capacity can be increased. Further, the increase of the evaporation pressure reduces the compression work per unit mass, the COP on the Mollier diagram is improved, and the reduction of the compression ratio improves the total adiabatic efficiency of the compressor. Therefore, the COP of the air conditioner during the heating operation can be improved.

Next, the operation of the heat pump type air conditioner during the cooling operation will be described with reference to FIGS. The gas refrigerant having the pressure P1 and the enthalpy h1 is compressed by the compressor 1 to become the pressure P2 and the enthalpy h2, and enters the outdoor heat exchanger 8 through the four-way valve 2 as shown by the broken line arrow in FIG. Heat is radiated to the air sent by 9 and condensed to become a liquid refrigerant having a pressure P2 and an enthalpy h3. This liquid refrigerant is decompressed to P3 by the electric expansion valve 7 to become a medium-temperature liquid gas two-phase refrigerant, enters the liquid refrigerant pipe 11, and the auxiliary heat exchanger 10 heats the low-temperature liquid gas two-phase refrigerant in the low-pressure pipe 12. It is exchanged and cooled to become enthalpy h4. This liquid gas two-phase refrigerant becomes P1 due to pressure loss in the indoor / outdoor connecting liquid pipe 6, enters the indoor heat exchanger 4, and blows indoor heat exchanger blower 5
Heat is absorbed from the air sent by and evaporated to become enthalpy h5. The low-temperature liquid-gas two-phase refrigerant that has exited the indoor heat exchanger 4 enters the low-pressure pipe 12 through the indoor / outdoor connecting gas pipe 3 and the four-way valve 2, and the auxiliary heat exchanger 10 causes the medium-temperature liquid gas in the pipe 11 to flow. It is heat-exchanged with the two-phase refrigerant and heated to become enthalpy h1 and returns to compressor 1.

As compared with the conventional example shown by the broken line in FIG.
Although the effect is smaller than that during the heating operation, the dryness of the inlet of the indoor heat exchanger 4 that functions as an evaporator during the cooling operation can be reduced, and when the same inlet temperature is used, the evaporation pressure can be increased.
Therefore, as in the heating operation, the specific volume of the compressor suction gas refrigerant decreases due to the increase in the evaporation pressure, and the cooling capacity can be increased. Also, due to the increase in evaporation pressure,
The compression work per unit mass is reduced, the COP on the Mollier diagram is improved, and the total adiabatic efficiency of the compressor is improved due to the reduction of the compression ratio. Therefore, the COP of the air conditioner during the cooling operation can be improved.

As described above, in the first embodiment, the heat pump type air conditioner using the non-azeotropic mixed refrigerant can improve the capacity and COP both during the heating operation and the cooling operation.

FIG. 6 is a block diagram of the heat pump type air conditioner of the second embodiment of the present invention, and FIG. 7 is a Mollier diagram showing its operating state. In FIG. 6, the electric expansion valve 7 of FIG. 1 is used as a first pressure reducer, and a capillary tube 20 as a second pressure reducer is added. The Mollier diagram of FIG. 7 shows both operating states during the heating operation and the cooling operation.

During heating operation, the pressure P leaving the indoor heat exchanger 4
2. The enthalpy h3 liquid refrigerant passes through the indoor / outdoor connection liquid pipe 6, is depressurized to P3 by the capillary tube 20 and becomes a medium temperature liquid gas two-phase refrigerant, enters the pipe 11, and is in the low pressure pipe 12 in the auxiliary heat exchanger 10. Is cooled by exchanging heat with the low-temperature liquid-gas two-phase refrigerant of enthalpy h4. This pressure P
3, the liquid refrigerant of enthalpy h4 is P1 by the electric expansion valve 7.
It is decompressed to become a liquid gas two-phase refrigerant. Further, the low-temperature liquid gas two-phase refrigerant having the pressure P1 and the enthalpy h5 exiting the outdoor heat exchanger 8 enters the low-pressure pipe 12 through the four-way valve 2 and enters the auxiliary heat exchanger 10 at the medium temperature liquid in the pipe 11. Heat is exchanged with the gas two-phase refrigerant to be heated to become enthalpy h1.

On the other hand, during the cooling operation, the liquid refrigerant having pressure P2 and enthalpy h3 that has exited the outdoor heat exchanger 8 is decompressed to P3 by the electric expansion valve 7 to become a medium temperature liquid gas two-phase refrigerant, and enters the pipe 11. The auxiliary heat exchanger 10 exchanges heat with the low-temperature liquid-gas two-phase refrigerant in the low-pressure pipe 12 to cool the enthalpy h4.
Becomes The liquid refrigerant having the pressure P3 and the enthalpy h4 is depressurized to P1 by the capillary tube 20 and the indoor / outdoor connection liquid pipe 6, and becomes a liquid gas two-phase refrigerant. In addition, the indoor heat exchanger 4
The low-temperature liquid-gas two-phase refrigerant having the pressure P1 and the enthalpy h5 exiting the inside enters the low-pressure pipe 12 through the indoor / outdoor connection gas pipe 3 and the four-way valve 2, and the medium temperature liquid in the pipe 11 in the auxiliary heat exchanger 10. Heat is exchanged with the gas two-phase refrigerant to be heated to become enthalpy h1.

In the second embodiment described above, the dryness of the inlet of the heat exchanger functioning as an evaporator can be reduced to the same extent in both heating operation and cooling operation, and the evaporation pressure can be increased.
Therefore, due to the effects described in the first embodiment, it is possible to improve the capacity and COP to the same extent both during the heating operation and during the cooling operation. In the present embodiment, the capillary tube 20 as the second pressure reducer is arranged between the indoor / outdoor connecting liquid pipe 6 and the electric expansion valve 7 as the first pressure reducer. Even if it is arranged between the indoor / outdoor connecting liquid pipe 6, the same effect can be obtained. Further, in this embodiment, the separate type heat pump type air conditioner including the outdoor unit A and the indoor unit B has been described, but it is also applicable to the indoor / outdoor integrated unit type.

A system diagram of the heat pump type air conditioner of the third embodiment of the present invention is shown in FIG. FIG. 8 uses an electric expansion valve 21 instead of the capillary tube 20 of FIG. In this embodiment, 7 is called a first electric expansion valve and 21 is called a second electric expansion valve. It is assumed that the first electric expansion valve 7 and the second electric expansion valve 21 have almost no valve path resistance when the opening is fully opened. During the heating operation, the opening degree of the second electric expansion valve 21 is fully opened, and the first electric expansion valve 7 is throttled to reduce the pressure of the refrigeration cycle. During the cooling operation,
The opening degree of the first electric expansion valve 7 is fully opened, and the second electric expansion valve 21 is throttled to decompress the refrigeration cycle. With such a configuration, the operating state can be represented by the Mollier diagram shown in FIG. 4 both during the heating operation and during the cooling operation. Therefore, in both the heating operation and the cooling operation, the inlet dryness of the heat exchanger that functions as an evaporator can be made sufficiently small and the evaporation pressure can be made high. As a result, the capacity and COP can be significantly improved both during the heating operation and the cooling operation.

A system diagram of the heat pump type air conditioner of the fourth embodiment of the present invention is shown in FIG. Reference numeral 30 is a check valve, and 31 is a liquid receiver for accumulating excess refrigerant during operation. The four check valves 30 are used for the liquid receiver 3 during both heating operation and cooling operation.
1 is always arranged on the inflow side of the expansion valve 7. The liquid receiver 31 is provided so as to be able to exchange heat with the low-pressure pipe 12. With the above configuration, since the non-azeotropic mixed refrigerant in the liquid receiver 31 is in a liquid gas two-phase state with a small dryness, the composition of the liquid refrigerant staying in the liquid receiver 31 and the refrigerant flowing into the liquid receiver 31. The difference from the composition is small, and the change of the circulating composition from the enclosed composition due to the retention of the liquid refrigerant can be suppressed to be small. Further, since the high-temperature accumulated liquid refrigerant in the receiver 31 exchanges heat with the low-temperature liquid-gas two-phase refrigerant in the low-pressure pipe 12, the enthalpy at the outlet of the receiver 31 can be reduced, and therefore, as an evaporator. The dryness at the inlet of the working heat exchanger is reduced, and the evaporation pressure can be increased. Therefore, capacity and C
OP can be significantly improved during heating operation and during cooling operation. The operating state of this embodiment can be represented by the Mollier diagram of FIG. 4 both during the heating operation and during the cooling operation.

[0024]

According to the present invention, the dryness of the inlet of the heat exchanger functioning as an evaporator can be made smaller than that of the conventional one during heating operation and cooling operation. The evaporation pressure can be increased. Therefore, due to the increase in the evaporation pressure, the specific volume of the compressor suction gas refrigerant decreases, and the heating capacity and the cooling capacity can be increased. Further, the increase of the evaporation pressure reduces the compression work per unit mass, which improves the COP on the Mollier diagram, and the reduction of the compression ratio improves the total adiabatic efficiency of the compressor. Therefore, the COP of the air conditioner during the heating operation and the cooling operation can be improved.

[Brief description of drawings]

FIG. 1 is a system diagram of a heat pump type air conditioner according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of an auxiliary heat exchanger according to the first embodiment of the present invention.

FIG. 3 is another explanatory view of the auxiliary heat exchanger according to the first embodiment of the present invention.

FIG. 4 is a Mollier diagram during heating operation according to the first embodiment of the present invention.

FIG. 5 is a Mollier diagram during cooling operation according to the first embodiment of the present invention.

FIG. 6 is a system diagram of a heat pump type air conditioner according to a second embodiment of the present invention.

FIG. 7 is a Mollier diagram of the second embodiment of the present invention.

FIG. 8 is a system diagram of a heat pump type air conditioner according to a third embodiment of the present invention.

FIG. 9 is a system diagram of a heat pump type air conditioner according to a fourth embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Compressor, 2 ... Four-way valve, 3 ... Gas piping, 4 ... Indoor heat exchanger, 6 ... Liquid piping, 7,21 ... Electric expansion valve, 8 ... Outdoor heat exchanger, 10 ... Auxiliary heat exchanger, 30 ... check valve, 31 ... receiver.

Claims (1)

[Claims] 1. A heat pump type air conditioner in which a compressor, a four-way valve, an indoor / outdoor connecting gas pipe, an indoor heat exchanger, an indoor / outdoor connecting liquid pipe, a pressure reducer and an outdoor heat exchanger are connected and a non-azeotropic mixed refrigerant is sealed. The heat pump type air conditioner, wherein the apparatus is provided with an auxiliary heat exchanger for exchanging heat between the refrigerant between the indoor / outdoor connection liquid pipe and the pressure reducer and the refrigerant sucked into the compressor.