CN203719237U - Dual-temperature heat source heat pump system - Google Patents

Abstract

The utility model discloses a dual-temperature heat source heat pump system, which comprises a compressor connected through pipelines, a gas-liquid separator, and a four-way valve, and also includes a water source heat exchanger, an exhaust air heat exchanger and a dual-temperature heat exchanger , the dual-temperature heat exchanger includes a first air-handling heat exchanger and a second air-handling heat exchanger. The heat pump evaporator and condenser of the utility model both adopt two sets of heat exchangers, and the two sets of heat exchangers can operate as evaporators/condensers in different cooling and heating modes, and operate at different temperatures, so that the heat pump The heat transfer temperature difference between the working fluid and the ambient medium is reduced, and the pressure difference between the high and low temperature heat sources of the heat pump is reduced, which can realize independent control of temperature and humidity, independent treatment of heat and humidity loads, and full heat recovery of exhaust air, etc., thereby improving the efficiency of heat pump air-conditioning refrigeration. , heating, ventilation and object heating, cooling, drying and dehumidification efficiency.

Description

A dual temperature heat source heat pump system

technical field

The utility model relates to a heat pump system, in particular to a dual-temperature heat source heat pump system which can be used for building heating, air conditioning, ventilation, heating, cooling, drying and dehumidification of objects and the like.

Background technique

A heat pump is a heat engine that works in a reverse cycle. It only needs to input a small amount of high-grade energy to absorb heat from a low-temperature environment and release several times the heat to a high-temperature environment. It has cooling and heating functions and has been widely used in house heating and air conditioning. etc., is an efficient heating device. Most of the current heat pumps work on a single-temperature cold and heat source, which makes the heat pump used for heating, air conditioning, object heating, cooling, drying and dehumidification, etc., the heat transfer temperature difference between the heat pump working fluid and the environmental medium is large, and the heat pump is high, The pressure difference between the low temperature heat sources is high, which affects the energy efficiency of the heat pump.

People have carried out some research and development, such as: utility model patent ZL200410054061.2 proposes a semi-cascade heat pump cooling and heating system, which can realize independent control of temperature and humidity, independent treatment of heat and humidity, and improve the adaptability of the heat pump system to the environment. However, the secondary heat pump unit in this utility model uses a series evaporator/condenser, which is not conducive to the uniform distribution of refrigerant, and the air treatment process is still a conventional cooling and dehumidification coupling process, and the efficiency is still not high.

Another example: utility model patent ZL200510029140.2 proposes a heat pump air-conditioning system with solution absorption and drying function, which can achieve high-efficiency dehumidification, but the solution dehumidification equipment is large in size, the system process is long and complicated, and the solution is corrosive, which requires more equipment. High disadvantages affect the actual effect of its engineering application.

Contents of the invention

The technical problem to be solved by the utility model is to provide a dual-temperature heat source heat pump system, which can operate as an evaporator/condenser in different cooling and heating modes through two sets of heat exchangers, and operate at different temperatures, so that the operation When the heat transfer temperature difference between the heat pump working fluid and the environmental medium is reduced, the pressure difference between the high and low temperature heat sources of the heat pump is reduced, which can realize independent control of temperature and humidity, independent treatment of heat and humidity loads, and full heat recovery of exhaust air, thereby improving the efficiency of heat pump air conditioning. Efficiency of refrigeration, heating, ventilation and object heating, cooling, drying and dehumidification.

In order to solve the above technical problems, the utility model adopts the following technical solutions: a dual-temperature heat source heat pump system, including a compressor connected through pipelines, a gas-liquid separator, and a four-way valve, and also includes a water source heat exchanger, an exhaust A heat exchanger and a dual-temperature heat exchanger, the dual-temperature heat exchanger includes a first air-handling heat exchanger and a second air-handling heat exchanger; between the intermediate air outlet of the compressor and the first air-handling heat exchanger Regulating valves (including regulating valves for cooling and regulating valves for heating) are respectively installed on the pipelines between the liquid receiver and the intermediate air inlet of the compressor; the cooling outlet ports of the water source heat exchanger and the exhaust air heat exchanger Throttling elements (including throttling elements for refrigeration and throttling elements for heating) are respectively installed on the pipelines between the first air handling heat exchanger and the cooling inlet ends of the second air handling heat exchanger; There are one-way valves for cooling and one-way valves for heating respectively connected in parallel on the flow elements; in the cooling state, the regulating valve, throttling element and heating The flow element and the one-way valve for refrigeration do not work.

The specific pipeline connections are as follows: the air outlets of the first air treatment heat exchanger and the second air treatment heat exchanger are respectively connected to the air inlets of the compressors through pipelines, and the air outlets of the compressors are connected to the air inlets of the compressors through pipelines. The air inlets of the water source heat exchanger and the exhaust air heat exchanger are respectively connected, and the liquid outlets of the water source heat exchanger and the exhaust air heat exchanger are connected to the first air treatment heat exchanger and the second air treatment heat exchanger through pipelines. The liquid inlets of the air handling heat exchangers are connected to each other respectively.

Both the heat pump evaporator and the condenser of the utility model adopt two sets of heat exchangers, and the two sets of heat exchangers can operate as evaporators/condensers in different cooling and heating modes, and operate at different temperatures. One group is the water source heat exchanger and the exhaust air heat exchanger, and the other group is the first air treatment heat exchanger and the second air treatment heat exchanger. As a dual-temperature heat exchanger, the two sets of heat exchangers , Under different heating modes, it can operate as an evaporator/condenser and operate at different temperatures. One of the heat exchangers is connected to the air inlet (discharge) port in the middle of the compressor. When the air conditioner is cooling, this heat exchanger operates as an evaporator, working at a higher evaporation pressure and evaporation temperature; in heating mode, this heat exchanger Operate as a condenser and work at a lower condensation temperature. The other set of heat exchangers is connected to the suction port/exhaust port of the compressor. When the air conditioner is cooling, this heat exchanger operates as an evaporator, working at a lower evaporation pressure and evaporation temperature; in heating mode, this heat exchanger The condenser operates as a condenser, works at a higher condensation temperature, and can also work at the same temperature as another group of condensers. Due to the adoption of a dual-temperature evaporator (condenser), the utility model can reduce the heat transfer temperature difference and compression ratio of the heat pump, thereby improving energy efficiency.

The pipes between the outlet ends of the water source heat exchanger and the exhaust air heat exchanger and the inlet end of the dual temperature heat exchanger are respectively equipped with two-temperature heat exchangers from the water source heat exchanger and the exhaust air heat exchanger to the dual temperature heat exchanger. The one-way valve opened by the dual-temperature heat exchanger, and the pipeline between the outlet end of the dual-temperature heat exchanger and the inlet end of the compressor is respectively installed with a one-way valve opened by the dual-temperature heat exchanger to the compressor.

Specifically, the pipeline between the water source heat exchanger and the exhaust heat exchanger and the dual-temperature heat exchanger is installed with a liquid reservoir and a dry filter, and the water source heat exchanger and the exhaust heat exchanger The outlet end of the liquid reservoir is connected to the inlet end of the liquid reservoir through a pipeline, the outlet end of the liquid reservoir is connected to the inlet end of the dry filter through a pipeline, and the outlet end of the dry filter is connected to the inlet end of the dry filter through a pipeline. The inlet end of the dual-temperature heat exchanger is connected, and the outlet end of the dual-temperature heat exchanger is connected with the inlet end of the liquid reservoir; the outlet end of the water source heat exchanger and the exhaust air heat exchanger are connected with the reservoir A one-way valve opened from the water source heat exchanger and the exhaust air heat exchanger to the liquid reservoir is installed on the pipeline between the inlet ends of the liquid container, and the outlet end of the dry filter is connected to the dual temperature heat exchanger. A one-way valve opened by the dry filter to the dual-temperature heat exchanger is installed on the pipeline between the inlet ends, and a one-way valve is installed on the pipeline between the outlet end of the dual-temperature heat exchanger and the inlet end of the liquid reservoir. There is a one-way valve opened by the dual temperature heat exchanger to the liquid reservoir.

A gas-liquid separator is installed on the pipeline between the water source heat exchanger, the exhaust air heat exchanger and the compressor, and the inlet end of the gas-liquid separator is connected to the water source heat exchanger and the exhaust gas through the pipeline. The outlet end of the air heat exchanger is connected, and the outlet end of the gas-liquid separator is connected with the suction port of the compressor through a pipeline. The pipeline between the exhaust port of the compressor, the inlet end of the water source heat exchanger and the exhaust air heat exchanger, the outlet end of the dual-temperature heat exchanger, and the inlet end of the gas-liquid separator A four-way valve is installed on it.

Adjusting valves are respectively installed on the pipelines between the compressor and the water source heat exchanger and exhaust air heat exchanger, and between the liquid receiver and the compressor.

Throttle elements are respectively installed on the pipes between the outlet ends of the water source heat exchanger and the exhaust heat exchanger and the inlet ends of the two groups of heat exchangers; The one-way valve opened by the water source heat exchanger and the exhaust air heat exchanger to the compressor, the one-way valve opened by the water source heat exchanger and the exhaust air heat exchanger to the compressor, and the one-way valve opened by the water source heat exchanger The one-way valve that opens the heat exchanger and the exhaust air heat exchanger to the dual-temperature heat exchanger.

Specifically, between the outlet end of the dry filter and the inlet ends of the first air treatment heat exchanger and the second air treatment heat exchanger, the outlet ends of the water source heat exchanger and the exhaust air heat exchanger Throttle elements are respectively installed on the pipelines between the inlet ends of the liquid storage tanks. The throttling element is respectively connected in parallel with a one-way valve opened from the water source heat exchanger and exhaust air heat exchanger to the dry filter, and a check valve opened from the water source heat exchanger and exhaust air heat exchanger to the The one-way valve opened by the drying filter and the one-way valve opened by the water source heat exchanger and the exhaust air heat exchanger to the liquid reservoir.

The reservoir may be a two-way flow reservoir.

The throttling element can be a capillary or an expansion valve. The expansion valve can be a thermal expansion valve or an electronic expansion valve.

Preferably, an auxiliary compressor is connected in series on the gas outlet pipeline of the compressor. Use two compressors in series to replace the compressor with the middle suction port.

Preferably, the pipes at both ends of the first air-handling heat exchanger and the second air-handling heat exchanger are connected in parallel with a third air-handling heat exchanger. In order to realize low-temperature air supply, only two air treatment heat exchangers can be used, but if the third air treatment heat exchanger is connected in parallel as a reheat heat exchanger, the utility model can also be realized.

Preferably, the installation height of the exhaust air heat exchanger is lower than that of the first air treatment heat exchanger and the second air treatment heat exchanger. The exhaust air heat exchanger can be installed under the first air treatment heat exchanger and the second air treatment heat exchanger. The heat exchanger (acting as an evaporator) evaporates on the surface for full heat recovery.

Or preferably, the installation height of the exhaust air heat exchanger is higher than the first air treatment heat exchanger and the second air treatment heat exchanger, and the first air treatment heat exchanger and the second air treatment heat exchanger are connected to the exhaust air heat exchanger. A pump is installed between the tanks. The exhaust air heat exchanger can also be installed above the first air treatment heat exchanger and the second air treatment heat exchanger, and the condensed water produced by the first air treatment heat exchanger and the second air treatment heat exchanger is pumped (as a lift pump) spray or distribute to the surface of the exhaust air heat exchanger for evaporation to achieve full heat recovery.

The utility model can operate as an evaporator/condenser in different cooling and heating modes through two sets of heat exchangers, and operate at different temperatures, so that the heat transfer temperature difference between the heat pump working medium and the environmental medium is reduced during operation, and the heat pump is high and stable. The pressure difference between low-temperature heat sources is reduced, thereby improving the efficiency of heat pump air conditioning refrigeration, heating, ventilation and object heating, cooling, drying and dehumidification.

Description of drawings

Below in conjunction with accompanying drawing and specific embodiment the utility model is further described:

Figure 1 is a schematic diagram of the overall structure of Embodiment 1 of the dual-temperature heat source heat pump system of the present invention;

Figure 2 is a schematic diagram of the overall structure of Embodiment 2 of the dual-temperature heat source heat pump system of the present invention;

Fig. 3 is a schematic diagram of the overall structure of Embodiment 3 of the dual-temperature heat source heat pump system of the present invention;

Fig. 4 is a schematic diagram of the positional relationship between the exhaust heat exchanger and the dual-temperature heat exchanger in Embodiment 4 of the dual-temperature heat source heat pump system of the present invention;

Fig. 5 is a spray schematic diagram of the positional relationship between the exhaust air heat exchanger and the dual-temperature heat exchanger in Embodiment 5 of the dual-temperature heat source heat pump system of the present invention;

Fig. 6 is a schematic diagram showing the positional relationship between the exhaust air heat exchanger and the dual-temperature heat exchanger in Embodiment 5 of the dual-temperature heat source heat pump system of the present invention.

Detailed ways

As shown in Figure 1, it is an embodiment 1 of a dual-temperature heat source heat pump system of the present invention, which includes a compressor 1, a gas-liquid separator 2, and a four-way valve 4 connected by pipelines, and also includes a water source heat exchanger 9, a drain Air heat exchanger 10 and double-temperature heat exchanger, described double-temperature heat exchanger comprises the first air treatment heat exchanger 11 and the second air treatment heat exchanger 12; The middle air outlet of compressor 1 and the first air treatment Adjusting valves 6 and 7 are respectively installed on the pipelines between the heat exchangers 11 and between the liquid accumulator 25 and the intermediate air inlet of the compressor 1; Throttle elements 22, 20, 18, 16 are respectively installed on the pipelines between the refrigeration inlet ends of the first air handling heat exchanger 11 and the second air handling heat exchanger 12; the throttling elements 22, 20, 18 and 16 are respectively connected in parallel with one-way valves 21 and 19 for cooling and one-way valves 17 and 15 for heating; 15 does not work; in the heating state, the regulating valve 6, the throttling elements 18, 16 and the one-way valves 21, 19 for refrigeration do not work.

A third air treatment heat exchanger 13 is connected in parallel to pipes at both ends of the first air treatment heat exchanger 11 and the second air treatment heat exchanger 12 .

A liquid reservoir 25 and a dry filter 26 are installed on the pipeline between the water source heat exchanger 9, the exhaust air heat exchanger 10 and the dual-temperature heat exchanger, and the water source heat exchanger 9, exhaust air exchanger The outlet end of the heater 10 is connected to the inlet end of the liquid storage 25 through a pipeline, and the outlet end of the liquid storage 25 is connected to the inlet end of the dry filter 26 through a pipeline. The outlet end is connected to the inlet end of the dual-temperature heat exchanger through a pipeline, and the outlet end of the dual-temperature heat exchanger is connected to the inlet end of the liquid reservoir 25; the water source heat exchanger 9, the exhaust air exchanger A one-way valve 23 opened to the liquid reservoir 25 by the water source heat exchanger 9 and the exhaust air heat exchanger 10 is installed on the pipeline between the outlet end of the heat exchanger 10 and the inlet end of the liquid reservoir 25. A check valve 28 opened by the dry filter 26 to the dual-temperature heat exchanger is installed on the pipeline between the outlet end of the dry filter 26 and the inlet end of the dual-temperature heat exchanger, and the dual-temperature heat exchanger A one-way valve 24 opened to the liquid storage 25 by the dual-temperature heat exchanger is installed on the pipeline between the outlet end of the liquid storage tank 25 and the inlet end of the liquid storage tank 25 .

Between the outlet end of the dry filter 26 and the inlet ends of the first air treatment heat exchanger 11 and the second air treatment heat exchanger 12, between the water source heat exchanger 9 and the exhaust air heat exchanger 10 Throttle elements 18 , 16 , 22 , 20 are respectively installed on the pipelines between the outlet end and the inlet end of the liquid reservoir 25 .

The throttling elements 18, 16, 22, 20 are respectively connected in parallel with a heating check valve 17 opened by the first air treatment heat exchanger 11 to the dry filter 26, and a heating check valve 17 opened by the second air The heating check valve 15 opened from the treatment heat exchanger 12 to the dry filter 26, the cooling check valve 21 opened from the water source heat exchanger 9 to the liquid receiver 25, and the drain valve 21 opened from the exhaust filter 26. The check valve 19 for cooling that opens the wind heat exchanger 10 to the accumulator 25 .

A gas-liquid separator 2 is installed on the pipeline between the water source heat exchanger 9, the exhaust heat exchanger 10 and the compressor 1, and the inlet end of the gas-liquid separator 2 is connected to the water source through the pipeline. The outlet ends of the heat exchanger 9 and the exhaust air heat exchanger 10 are connected, and the outlet end of the gas-liquid separator 2 is connected with the suction port of the compressor 1 through a pipeline.

At the exhaust port of the compressor 1, the inlet end of the water source heat exchanger 9, the exhaust air heat exchanger 10, the outlet end of the dual-temperature heat exchanger, and the inlet end of the gas-liquid separator 2 Four-way valve 4 is installed on the pipeline between.

Adjusting valves 6 and 7 are respectively installed on the pipelines between the compressor 1 and the first air treatment heat exchanger 11 and between the liquid reservoir 25 and the compressor 1 .

In the cooling mode, the regulating valves 5 and 7 are closed, and the regulating valves 3, 6 and 8 are opened. Part of the high-temperature and high-pressure gas discharged from the compressor 1 enters the third air treatment heat exchanger 13 (as a condenser) through the regulating valve 3 to condense and release heat, so that it passes through the first air treatment heat exchanger 11 and the second air treatment heat exchanger. 12 (as an evaporator) the treated air in a low-temperature and low-humidity state is reheated to prevent condensation at the indoor air supply port; another part of high-temperature and high-pressure gas enters the water source heat exchanger 9 (as a condenser), respectively through the four-way valve 4 The exhaust air heat exchanger 10 (as a condenser) turns into a liquid after condensing and releasing heat, respectively passes through the one-way valves 19 and 21 for cooling, and then enters the liquid receiver 25 through the one-way valve 23, and then passes through the dry filter 26 , one-way valve 28, and then enter the first air treatment heat exchanger 11 and the second air treatment heat exchanger 12 (as an evaporator) through the throttling elements 16 and 18 to evaporate and absorb heat, and return air (indoor air) or Fresh air, or a mixture of fresh air and return air, cools down and dehumidifies. The first air treatment heat exchanger 11 (as an evaporator) works at a relatively high evaporation temperature, pre-cools and dehumidifies the return air (indoor air) or fresh air, or the mixed air of fresh air and return air, and the refrigerant evaporates in it It enters the middle air inlet of the compressor through the regulating valve 6; the second air treatment heat exchanger 12 (as an evaporator) works at a lower evaporation temperature, and the return air (indoor air) or fresh air, or the mixture of fresh air and return air The wind further cools down and dehumidifies, and the refrigerant vaporizes in it and enters the gas-liquid separator 2 through the four-way valve 4, and then enters the compressor 1, and is compressed to a high temperature and high pressure state before being discharged.

In the heating mode, the regulating valves 6 and 8 are closed, and the regulating valves 3, 5 and 7 are opened. Part of the high-temperature and high-pressure gas discharged from the compressor 1 enters the third air treatment heat exchanger 13 (as a condenser) through the regulating valve 3 to condense and release heat, and passes through the first air treatment heat exchanger 11 and the second air treatment heat exchanger. 12 (as an evaporator) the heated air is further heated. Another part of high-temperature and high-pressure gas passes through the four-way valve 4, and then enters the first air treatment heat exchanger 11 (as a condenser) through the regulating valve 5 all the way to condense and release heat, preheat return air (indoor air) or fresh air, or fresh air , the mixed air of the return air, and the other way enters the second air treatment heat exchanger 12 (as a condenser) to heat the return air (indoor air) or fresh air preheated by the first air treatment heat exchanger 11 (as a condenser), Or a mixed wind of fresh air and return air. After the high-temperature and high-pressure refrigerant gas condenses and releases heat in the first air treatment heat exchanger 11, the second air treatment heat exchanger 12 and the third air treatment heat exchanger 13 to become liquid, it passes through the heating check valve 17 respectively. , 15, and 14 converge and then enter the liquid reservoir 25 through the check valve 24, then pass through the dry filter 26 and the check valve 27, and then divide into two paths, one way enters the water source heat exchanger 9 through the throttling element 22 (as an evaporation The water source heat exchanger 9 works at a relatively high evaporation temperature and can absorb heat from various water sources such as other air-conditioning circuits. The refrigerant vaporizes in it and enters the middle air inlet of the compressor 1 through the regulating valve 6; The other path enters the exhaust air heat exchanger (as an evaporator) through the throttling element 20. The exhaust air heat exchanger 9 works at a lower evaporation temperature and can absorb heat from the exhaust air to realize energy recovery. After the refrigerant is vaporized in it, It enters the gas-liquid separator 2 through the four-way valve 4, and then enters the compression compressor 1, and is discharged after being compressed to high temperature and high pressure.

As shown in Fig. 2, it is Embodiment 2 of a dual-temperature heat source heat pump system of the present invention. The difference from Embodiment 1 is that an auxiliary compressor 29 is connected in series on the air outlet pipeline of compressor 1 . Use two compressors in series to replace the compressor with the middle suction port.

As shown in Figure 3, it is Embodiment 3 of a dual-temperature heat source heat pump system of the present invention. The difference from Embodiment 1 is that in order to realize low-temperature air supply, the third air-handling heat exchanger 13 (as a condenser) is removed. Regulating valve 3, one-way valve 14 on its subsidiary pipeline.

As shown in Fig. 4, it is an embodiment 4 of a dual-temperature heat source heat pump system of the present invention, which differs from embodiment 1 in that the installation height of the exhaust air heat exchanger 10 is lower than that of the first air treatment heat Two air handling heat exchangers 12 . The exhaust air heat exchanger 10 can be installed below the first air treatment heat exchanger 11 and the second air treatment heat exchanger 12, and the condensation generated during the work of the first air treatment heat exchanger 11 and the second air treatment heat exchanger 12 Water self-flows to the surface of the exhaust air heat exchanger 10 (as an evaporator) and evaporates to realize total heat recovery.

As shown in Figures 5 and 6, it is Embodiment 5 of a dual-temperature heat source heat pump system of the present invention. The difference from Embodiment 1 is that the installation height of the exhaust air heat exchanger 10 is higher than that of the first air treatment heat exchanger 11 And the second air treatment heat exchanger 12 , a pump 30 is installed between the first air treatment heat exchanger 11 , the second air treatment heat exchanger 12 and the exhaust air heat exchanger 10 . The exhaust air heat exchanger 10 can also be installed above the first air treatment heat exchanger 11 and the second air treatment heat exchanger 12, and the first air treatment heat exchanger 11 and the second air treatment heat exchanger 12 generate The condensed water is sprayed or distributed to the surface of the exhaust air heat exchanger 10 by the pump 30 (as a lift pump) to evaporate to realize full heat recovery.

The above is only a specific embodiment of the utility model, but the technical characteristics of the utility model are not limited thereto, and any changes or modifications made by those skilled in the art within the scope of the utility model are all covered by the utility model. In the scope of the new patent.

Claims (5)

1. A dual-temperature heat source heat pump system, including a compressor (1), a gas-liquid separator (2), and a four-way valve (4) connected through pipelines, characterized in that it also includes a water source heat exchanger (9 ), an exhaust air heat exchanger (10) and a dual-temperature heat exchanger, the dual-temperature heat exchanger includes a first air-handling heat exchanger (11) and a second air-handling heat exchanger (12); a compressor ( Regulating valves (6, 7); between the cooling outlet of the water source heat exchanger (9) and the exhaust air heat exchanger (10) and the cooling inlet of the first air treatment heat exchanger (11) and the second air treatment heat exchanger (12) Throttle elements (22, 20, 18, 16) are respectively installed on the pipelines between them; said throttling elements (22, 20, 18, 16) are respectively connected in parallel with one-way valves (21, 19) for refrigeration, Check valves (17, 15) for heating; in cooling state, regulating valve (7), throttling element (22, 20) and heating check valve (17, 15) do not work; in heating state , regulating valve (6), throttling element (18,16) and refrigeration check valve (21,19) do not work. 2. The dual-temperature heat source heat pump system according to claim 1, characterized in that: an auxiliary compressor (29) is connected in series on the gas outlet pipeline of the compressor (1). 3. The dual-temperature heat source heat pump system according to claim 1, characterized in that: the pipes at both ends of the first air treatment heat exchanger (11) and the second air treatment heat exchanger (12) are connected in parallel with third Air handling heat exchanger (13). 4. The dual-temperature heat source heat pump system according to claim 1, characterized in that: the installation height of the exhaust air heat exchanger (10) is lower than that of the first air treatment heat exchanger (11) and the second air treatment heat exchanger device (12). 5. The dual-temperature heat source heat pump system according to claim 1, characterized in that: the installation height of the exhaust air heat exchanger (10) is higher than that of the first air treatment heat exchanger (11) and the second air treatment heat exchanger A pump (30) is installed between the first air treatment heat exchanger (11), the second air treatment heat exchanger (12) and the exhaust air heat exchanger (10).