Air conditioning device

Abstract

To provide an air conditioning device that can save energy.SOLUTION: An air conditioning device 1 comprises an outdoor side unit 2 incorporating at least a compressor 20 and an outdoor side heat exchanger 24, an indoor side unit 3 incorporating at least a condenser 30 and an evaporator 31, and a high-pressure gas pipe 5, a low-pressure gas pipe 6, and a liquid pipe 7 connected between the outdoor side unit 2 and the indoor side unit 3, and also comprises exhaust means 44 for taking air in an indoor space R and discharging it to an outdoor space, and an exhaust side heat exchanger 40 for exchanging heat between the taken air A3 in the indoor space and a heat medium. The exhaust side heat exchanger 40 is communicably connected to the high-pressure gas pipe 5, the low-pressure gas pipe 6, and the liquid pipe 7.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an air conditioner that conditions indoor air, and more particularly to an air conditioner that is capable of performing a reheat dehumidification operation. [Background technology]

[0002] Air conditioners used for air conditioning in various industrial fields are equipped with a heat pump that is mainly composed of a compressor, a condenser, an expansion valve, and an evaporator. Some of these air conditioners are of the separate type, in which the heat pump is divided into an outdoor unit installed outdoors and an indoor unit installed in the room to be air-conditioned, and the efficiency of indoor air conditioning is improved by discharging heat outdoors.

[0003] For example, an air-conditioning device such as that described in Patent Document 1 is mainly composed of an outdoor unit equipped with a compressor and an outdoor heat exchanger, and an indoor unit equipped with a condenser and an evaporator, which are connected by high-pressure gas pipes, low-pressure gas pipes, and liquid pipes.

[0004] The high-pressure gas pipe is a pipe through which a high-temperature, high-pressure gaseous heat medium (hereinafter referred to as "high-pressure gas heat medium") discharged from the compressor flows. The low-pressure gas pipe is a pipe through which a low-temperature, low-pressure gaseous heat medium (hereinafter referred to as "low-pressure gas heat medium") sucked into the compressor flows. The liquid pipe is a pipe through which a low-temperature, high-pressure liquid heat medium (hereinafter referred to as "liquid heat medium") that has been cooled from the high-pressure gas heat medium flows. The condenser is connected to the high-pressure gas pipe and the liquid pipe so that they can communicate with each other, and the evaporator is connected to the liquid pipe and the low-pressure gas pipe so that they can communicate with each other.

[0005] Such an air conditioner can perform a reheat dehumidification operation by distributing the high-temperature gas heat transfer medium to the condenser side and the outdoor heat exchanger side, and by reducing the pressure of both the liquid heat transfer medium after passing through the condenser and the liquid heat transfer medium after passing through the outdoor heat exchanger and passing them through the evaporator. In the reheat dehumidification operation, the air before air conditioning is cooled by heat exchange through the evaporator, and the moisture contained therein is discharged to produce dehumidified air. The dehumidified air can then be heated to an appropriate temperature by heat exchange through the condenser and supplied to the room as conditioned air. In addition, by passing the heat transfer medium only through the condenser, a heating operation can be performed in which the air before air conditioning is heated and supplied to the room as conditioned air. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2001-227841 A (Pages 3 and 4, Figure 1) Summary of the Invention [Problem to be solved by the invention]

[0007] In this way, in an air conditioner such as that described in Patent Document 1, the air before conditioning can be heated using a heat pump, and therefore energy saving can be achieved compared to a case where the air before conditioning is heated using an electric heater or the like. In recent years, energy saving is a permanent issue, as represented by the SDGs (Sustainable Development Goals). As a result of extensive research, the inventors have found a method for achieving further energy saving.

[0008] The present invention has been made in consideration of such problems, and has an object to provide an air conditioner that is capable of saving energy. [Means for solving the problem]

[0009] In order to solve the above problems, the air conditioning device of the present invention comprises: an outdoor unit incorporating at least a compressor and an outdoor heat exchanger; An indoor unit incorporating at least a condenser and an evaporator; An air conditioning apparatus comprising a high-pressure gas pipe, a low-pressure gas pipe, and a liquid pipe connected across the outdoor unit and the indoor unit, An exhaust means for taking in indoor air and discharging it to the outside of the room; The present invention further includes an exhaust-side heat exchanger for exchanging heat between the air taken in from the room and a heat medium, The exhaust heat exchanger is connected to the high pressure gas pipe, the low pressure gas pipe, and the liquid pipe so as to be able to communicate with each other. According to this feature, by exchanging heat between the heat medium and the indoor air, the energy required to operate the compressor can be reduced, thereby achieving energy saving.

[0010] The exhaust means and the exhaust-side heat exchanger are built into an exhaust-side unit having an intake port for taking in air from within the room and an exhaust port for discharging the taken-in air. According to this feature, heat can be efficiently exchanged between the taken-in indoor air and the heat medium inside the exhaust side unit, which is independent from the indoor space and other units.

[0011] The indoor unit and the exhaust side unit are each provided in a single housing separated by a partition material. According to this feature, the configuration of the air conditioning apparatus can be simplified.

[0012] an expansion valve is provided between the exhaust heat exchanger and the liquid pipe; The expansion valve is characterized in that its opening degree is adjusted in accordance with the degree of superheat or subcooling of the heat medium that has passed through the exhaust-side heat exchanger. According to this feature, it is possible to ensure that the state of the entire amount of heat medium passing through the exhaust side heat exchanger is changed.

[0013] A temperature sensor is provided downstream of the exhaust heat exchanger, The expansion valve is characterized in that its opening degree is adjusted in accordance with the temperature detected by the temperature sensor. According to this feature, it is possible to prevent the pressure of the heat medium from falling below a predetermined value with simple control.

[0014] The exhaust-side heat exchanger is connected to the low-pressure gas pipe and the high-pressure gas pipe via an on-off valve so as to be able to communicate with each other. According to this feature, the flow path can be configured according to the operating state through simple control.

[0015] The on-off valve is characterized in that, during heating operation, the low pressure gas pipe side is opened and the high pressure gas pipe side is closed. According to this feature, the pressure of the low pressure gas heat transfer medium can be increased. This allows the pressure ratio of the heat transfer medium to be reduced, so that the energy required to operate the compressor can be reduced. In addition, the frequency of defrost operation can be reduced.

[0016] The on-off valve is characterized in that, when the pressure of the heat medium reaches or exceeds a specific value during the heating operation, the low-pressure gas pipe side is closed and the high-pressure gas pipe side is opened. According to this feature, the exhaust side heat exchanger that had been functioning as an evaporator can be made to function as a condenser, so that excessively high pressure of the heat transfer medium can be reduced while continuing heating operation.

[0017] The expansion valve provided between the exhaust heat exchanger and the liquid pipe is characterized in that it is closed when the pressure of the heat medium approaches the specific value and is opened when the pressure of the heat medium reaches or exceeds the specific value. According to this feature, before the exhaust heat exchanger that has been functioning as an evaporator is made to function as a condenser, the heat exchange between the indoor air and the heat medium through the exhaust heat exchanger can be stopped while preventing liquid sealing. This makes it possible to prevent a sudden change in pressure of the heat medium. In addition, it is possible to suppress the occurrence of overshoot and undershoot.

[0018] The on-off valve is characterized in that, during a dehumidifying operation, the high pressure gas pipe side is opened and the low pressure gas pipe side is closed. According to this feature, the pressure of the high pressure gas heat transfer medium can be reduced, and therefore the pressure ratio of the heat transfer medium can be reduced, and therefore the energy required to operate the compressor can be reduced.

[0019] The on-off valve is characterized in that, during the dehumidifying operation, when the pressure of the heat medium falls below a predetermined value, the high-pressure gas pipe side is closed and the low-pressure gas pipe side is opened. According to this feature, the exhaust side heat exchanger that had been functioning as a condenser can be made to function as an evaporator, so that the pressure of the heat transfer medium that has dropped too much can be increased while continuing the dehumidification operation.

[0020] the on-off valve closes the high pressure gas pipe side and the low pressure gas pipe side when the pressure of the heat medium approaches the predetermined value, The expansion valve provided between the exhaust side heat exchanger and the liquid pipe is characterized in that it is throttled when the pressure of the heat transfer medium approaches the predetermined value and is opened when the pressure of the heat transfer medium falls below the predetermined value. According to this feature, before the exhaust heat exchanger that has been functioning as a condenser is made to function as an evaporator, the heat exchange between the indoor air and the heat medium through the exhaust heat exchanger can be stopped while preventing liquid sealing. This makes it possible to prevent a sudden change in pressure of the heat medium. In addition, it is possible to suppress the occurrence of overshoot and undershoot. [Brief description of the drawings]

[0021] [Figure 1] FIG. 1 is a block diagram showing a heating operation in an air conditioner according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a block diagram showing a reheat dehumidification operation in the air conditioner of the first embodiment according to the present invention. [Diagram 3]FIG. 11 is a block diagram showing a state in which an exhaust-side heat exchanger in an air-conditioning apparatus according to a second embodiment of the present invention is in an evaporator mode in a high-load state during heating operation and in a low-load state. [Figure 4] FIG. 4 is a block diagram showing a state in which the exhaust-side heat exchanger is in an air blowing mode under a low load condition during heating operation, similar to FIG. 3 . [Diagram 5] FIG. 4 is a block diagram showing a state in which the exhaust-side heat exchanger is in a condenser mode during heating operation, similar to FIG. 3 . [Figure 6] FIG. 11 is a block diagram showing a state in which an exhaust-side heat exchanger in an air-conditioning apparatus according to a second embodiment of the present invention is in a high-load state during reheat dehumidification operation and in a condenser mode in a low-load state. [Figure 7] FIG. 7 is a block diagram showing a state in which the exhaust heat exchanger is in an air blowing mode under a low load condition during the reheat dehumidification operation, similar to FIG. 6. [Figure 8] FIG. 7 is a block diagram showing a state in which the exhaust heat exchanger is in an evaporator mode under a low load condition during the reheat dehumidification operation, similar to FIG. 6. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An air conditioning apparatus according to an embodiment of the present invention will be described below with reference to the accompanying drawings. EXAMPLES

[0023] An air conditioner according to a first embodiment will be described with reference to Figures 1 and 2. The air conditioner 1 of this embodiment is configured to be switchable between a heating operation and a reheat dehumidification operation.

[0024] 1, the air conditioner 1 is a so-called outdoor air handling unit (OHU) that is used for adjusting humidity in indoor spaces that require humidity control, such as offices, workshops, etc., as well as indoor spaces that are the target of air conditioning, particularly hospitals, libraries, art museums, etc. The air conditioner may also be an air handling unit (AHU) that circulates indoor air to perform indoor air conditioning processing.

[0025] The air conditioner 1 is mainly composed of an outdoor unit 2 installed outside a building, an indoor unit 3 that processes the air outside the building taken inside (hereinafter referred to as "outside air") and supplies it to the room R to be air-conditioned, an exhaust side unit 4 that takes in the air inside the room R (hereinafter referred to as "inside air") and exhausts it outdoors after heat exchange, a high-pressure gas pipe 5 through which a high-pressure gas heat medium flows, a low-pressure gas pipe 6 through which a low-pressure gas heat medium flows, a liquid pipe 7 through which a liquid heat medium flows, and a control device 10. The indoor unit may be configured to take in inside air and supply it to the room, or may be configured to take in both outside and inside air and supply it to the room.

[0026] First, the outdoor unit 2 will be described. The outdoor unit 2 mainly includes an inverter-driven compressor 20 that compresses the low-pressure gas heat medium, an oil separator 21 that recovers mist-like lubricating oil mixed in the high-pressure gas heat medium, a first four-way valve 22 and a second four-way valve 23 that switch the flow of the heat medium, a first outdoor heat exchanger 24 and a second outdoor heat exchanger 25 that exchange heat between the heat medium and the outside air, a first outdoor expansion valve 26 and a second outdoor expansion valve 27 that can reduce the pressure of the heat medium, a receiver 28 that stores the liquid heat medium, and an accumulator 29 that recovers the liquid heat medium from the low-pressure gas heat medium.

[0027] The outdoor unit 2 also includes a discharge pipe 50 and an outdoor high-pressure gas branch pipe 51 as flow paths through which the high-pressure gas heat transfer medium flows. The discharge pipe 50 is connected to the compressor 20 and the oil separator 21. The outdoor high-pressure gas branch pipe 51 is branched and connected to the oil separator 21, the four-way valves 22 and 23, and the high-pressure gas pipe 5.

[0028] The outdoor unit 2 also includes an outdoor low-pressure gas branch pipe 60 and a suction pipe 61 as flow paths through which the low-pressure gas heat transfer medium flows. The outdoor low-pressure gas branch pipe 60 is branched and connected to the accumulator 29, the four-way valves 22 and 23, and the low-pressure gas pipe 6. The suction pipe 61 is connected to the accumulator 29 and the compressor 20.

[0029] The outdoor unit 2 also includes an outdoor liquid branch pipe 70 and an outdoor liquid pipe 71 as flow paths through which the liquid heat transfer medium flows. The outdoor liquid branch pipe 70 is branched and connected to the outdoor expansion valves 26, 27 and the receiver 28. The outdoor liquid pipe 71 is connected to the receiver 28 and the liquid pipe 7.

[0030] The outdoor unit 2 also includes a first four-way valve side pipe 80, a second four-way valve side pipe 81, a first expansion valve side pipe 82, and a second expansion valve side pipe 83 as piping through which the state of the heat medium passing through can change depending on the operating state. The first four-way valve side pipe 80 is connected to the first four-way valve 22 and the first outdoor heat exchanger 24. The second four-way valve side pipe 81 is connected to the second four-way valve 23 and the second outdoor heat exchanger 25. The first expansion valve side pipe 82 is connected to the first outdoor heat exchanger 24 and the first outdoor expansion valve 26. The second expansion valve side pipe 83 is connected to the second outdoor heat exchanger 25 and the second outdoor expansion valve 27.

[0031] A first capillary tube 84 is connected to the first four-way valve 22 and the first four-way valve side pipe 80. A second capillary tube 85 is connected to the second four-way valve 23 and the second four-way valve side pipe 81.

[0032] Next, we will explain the indoor unit 3 and the exhaust side unit 4. The indoor unit 3 and the exhaust side unit 4 are provided in a single housing 9 that is installed outdoors and sandwiched between a wall facing the room R to be air-conditioned. The housing 9 is made of insulating material to prevent heat exchange between the air inside the housing and the outside air.

[0033] The inside of the housing 9 is airtightly partitioned by a partition material 92 made of a heat insulating material, and is divided into a lower space 90 in which the indoor unit 3 is provided and an upper space 91 in which the exhaust side unit 4 is provided. In addition, the indoor high-pressure gas branch pipe 52, the indoor low-pressure gas branch pipe 62, and the indoor liquid branch pipe 72 described below extend through the partition material 92, and the gaps between them are sealed. Note that the indoor high-pressure gas branch pipe 52, the indoor low-pressure gas branch pipe 62, and the indoor liquid branch pipe 72 may be provided so as to penetrate the wall material of the housing 9 and bypass the outside, and the gaps between them may be sealed.

[0034] This prevents the air in the lower space 90 and the air in the upper space 91 from being mixed together, and also prevents heat exchange between these air spaces.

[0035] The housing 9 is provided with an outside air inlet 93 that communicates with the outdoors and the lower space 90, and a delivery path 94 that communicates with the lower space 90 and the room R and with an outlet of the indoor fan 34 described below. The delivery path 94 communicates with an intake air vent 95 formed in the wall facing the room R. That is, the indoor fan 34 is positioned so as to be able to deliver conditioned air A2 into the room R.

[0036] The housing 9 is also provided with an intake passage 96 that communicates with the room R and the upper space 91, and an exhaust-side through-hole 97 that communicates with the upper space 91 and the outdoors and through which an outlet 44a of the exhaust-side blower 44, which will be described later, communicates. The intake passage 96 communicates with an exhaust-side vent 98 serving as an intake formed in a wall facing the room R. The exhaust-side blower 44 is also disposed so as to be able to send the exhaust gas A4 outdoors, and the outlet 44a is exposed to the outdoors. In this embodiment, the outlet 44a functions as an exhaust outlet.

[0037] The housing 9 is not limited to being installed outdoors as in this embodiment, but may be installed in an adjacent room separated by a wall from the room R to be air-conditioned, or may be installed in a location away from the room R. In other words, the housing 9 only needs to be installed in a location isolated from the room R to be air-conditioned.

[0038] Also, the lower space 90 and the upper space 91 may be directly connected to the room R without using a duct or the like. Furthermore, each vent is not limited to being formed in a wall, but may be formed in a ceiling or a floor, or may be modified as appropriate. In this way, the communication structure between the lower space 90 and the upper space 91 and the room R may be modified as appropriate.

[0039] Furthermore, the indoor unit 3 and the exhaust side unit 4 are not limited to being provided in one housing 9 as in this embodiment, and may be provided in separate housings or ducts, or may be installed in a separate room other than the room to be air-conditioned, or a room other than the room to be air-conditioned may be partitioned to provide a space for installing the indoor unit 3 and a space for installing the exhaust side unit 4. In other words, the locations where the indoor unit 3 and the exhaust side unit 4 are installed may be changed as appropriate as long as they are partitioned so that the air of each unit does not mix and heat exchange does not occur.

[0040] The indoor unit 3 and the exhaust side unit 4 are not limited to being arranged one above the other, but may be arranged front to back or left to right. Furthermore, the indoor unit 3 may be arranged in different locations, such as on the ground and the exhaust side unit 4 on the roof.

[0041] In addition, the air outlet 44a may be connected to a duct that is connected to the outdoors, and the opening of the duct may be the exhaust port, and the configuration of the exhaust port may be changed as appropriate as long as it is open to a space isolated from the room R.

[0042] The indoor unit 3 mainly comprises a condenser 30 that exchanges heat between the pre-conditioning air A1 (outside air) and the heat medium, an evaporator 31 that exchanges heat between the pre-conditioning air A1 and the heat medium, a condenser-side valve 32 that controls the amount of heat medium passing through, an evaporator-side expansion valve 33 that can reduce the pressure of the heat medium, an indoor blower 34 that sends out the conditioned air A2 into the room R, and an indoor thermometer 35 that measures the temperature of the pre-conditioning air A1.

[0043] The exhaust side unit 4 mainly comprises an exhaust side heat exchanger 40 which exchanges heat between the heat medium and the return air A3, which is the inside air taken in through the exhaust side vent 98, a high pressure side solenoid valve 41 and a low pressure side solenoid valve 42 which serve as opening and closing valves for opening and closing the flow path, an exhaust side expansion valve 43 which can reduce the pressure of the heat medium, an exhaust side blower 44 which serves as exhaust means for sending out the exhaust air A4, an exhaust side thermometer 45 which measures the temperature of the exhaust air A4, and heat medium thermometers 46, 47 which measure the temperature of the heat medium.

[0044] In addition, the indoor unit 3 and the exhaust side unit 4 are equipped with an indoor high-pressure gas branch pipe 52 as a flow path through which the high-pressure gas heat transfer medium flows, and the indoor high-pressure gas branch pipe 52 is branched and connected to the high-pressure gas pipe 5, the condenser 30, and the high-pressure side solenoid valve 41.

[0045] In addition, the indoor unit 3 and the exhaust side unit 4 are provided with an indoor low-pressure gas branch pipe 62 as a flow path through which the low-pressure gas heat transfer medium flows. The indoor low-pressure gas branch pipe 62 is branched and connected to the low-pressure gas pipe 6, the evaporator 31, and a low-pressure side solenoid valve 42 described later.

[0046] In addition, the indoor unit 3 and the exhaust unit 4 are provided with an indoor liquid branch pipe 72 as a flow path through which the liquid heat transfer medium flows. The indoor liquid branch pipe 72 is branched and connected to the liquid pipe 7, the condenser side valve 32, the evaporator side expansion valve 33, and the exhaust side expansion valve 43 described later.

[0047] The indoor unit 3 and the exhaust unit 4 are provided with a condenser-side pipe 86, an evaporator-side pipe 87, a solenoid valve-side branch pipe 88, and an expansion valve-side pipe 89 as piping through which the state of the heat medium passing through can change depending on the operating state. The condenser-side pipe 86 is connected to the condenser 30 and the condenser-side valve 32. The evaporator-side pipe 87 is connected to the evaporator 31 and the evaporator-side expansion valve 33. The solenoid valve-side branch pipe 88 is connected to the exhaust-side heat exchanger 40, the high-pressure side solenoid valve 41, and the low-pressure side solenoid valve 42. The expansion valve-side pipe 89 is connected to the exhaust-side heat exchanger 40 and the exhaust-side expansion valve 43.

[0048] In addition, the solenoid valve side branch pipe 88 has a solenoid valve side heat medium thermometer 46 provided near the exhaust side heat exchanger 40, and the expansion valve side pipe 89 has an expansion valve side heat medium thermometer 47 provided near the exhaust side heat exchanger 40.

[0049] The control device 10 is provided in the outdoor unit 2 and is electrically connected to the compressor 20, four-way valves 22, 23, expansion valves 26, 27, 32, 33, 43, blowers 34, 44, solenoid valves 41, 42, thermometers 35, 45, 46, 47, an indoor thermometer 11 provided in the room R, an indoor hygrometer 12, etc. via communication lines.

[0050] In order to simplify the illustration, the only communication lines shown for transmitting electrical signals are the communication line 13 electrically connecting the control device 10 and the exhaust side thermometer 45, the communication line 14 electrically connecting the control device 10 and the exhaust side expansion valve 43, the communication line 15 electrically connecting the control device 10 and the solenoid valve side heat medium thermometer 46, and the communication line 16 electrically connecting the control device 10 and the expansion valve side heat medium thermometer 47.

[0051] Next, the heating operation by the air conditioner 1 will be described.

[0052] As shown in Fig. 1, the pre-conditioning air A1 sucked into the lower space 90 by the indoor blower 34 passes through the evaporator 31 and then the condenser 30, as indicated by the outlined arrow in Fig. 1. The pre-conditioning air A1 is heated by heat exchange with the condenser 30, and is sent into the room R as temperature-adjusted conditioned air A2. As a result, the temperature of the indoor air is raised or maintained at a temperature higher than the outside air temperature.

[0053] Next, the flow of the heat medium during heating operation will be described. In the outdoor unit 2, the controller 10 controls the valve position of the first four-way valve 22 to communicate the outdoor high-pressure gas branch pipe 51 with the first capillary tube 84 and to communicate the outdoor low-pressure gas branch pipe 60 with the first four-way valve side pipe 80. The controller 10 also controls the valve position of the second four-way valve 23 to communicate the outdoor high-pressure gas branch pipe 51 with the second capillary tube 85 and to communicate the outdoor low-pressure gas branch pipe 60 with the second four-way valve side pipe 81. The controller 10 also sets the first outdoor expansion valve 26 and the second outdoor expansion valve 27 to a throttled state.

[0054] Almost the entire amount of the high-pressure gas heat transfer medium discharged from the compressor 20 flows into the high-pressure gas pipe 5 side, as shown by the black arrow in FIG.

[0055] In this embodiment, the open state refers to a state where the valve opening is adjusted to allow the heat transfer medium to pass with little or no pressure reduction. In addition, the throttling state refers to a state where the valve opening is adjusted to allow the heat transfer medium to be decompressed. In addition, the closed state refers to a state where the valve opening is adjusted to allow the heat transfer medium to be stopped or almost stopped from passing.

[0056] The control device 10 opens the condenser side valve 32 and closes the evaporator side expansion valve 33 in the indoor side unit 3.

[0057] In the exhaust side unit 4, the control device 10 closes the high pressure side solenoid valve 41, opens the low pressure side solenoid valve 42, and throttles or closes the exhaust side expansion valve 43.

[0058] The high-pressure gas heat transfer medium that has flowed into the high-pressure gas pipe 5 flows into the condenser 30 through the indoor-side high-pressure gas branch pipe 52, as shown by the black arrow in Fig. 1. When passing through the condenser 30, the high-pressure gas heat transfer medium exchanges heat with the pre-air-conditioning air A1 sucked in by the indoor-side blower 34, and changes state to a liquid heat transfer medium.

[0059] The control device 10 can adjust the amount of heat transfer medium passing through the condenser 30 per unit time by controlling the valve opening of the condenser-side valve 32 based on the temperature of the pre-conditioning air A1 and the temperature of the inside air obtained from the thermometers 11, 35. This allows the control device 10 to adjust the degree of heating of the conditioned air A2.

[0060] The liquid heat transfer medium that has passed through condenser 30 flows into indoor side liquid branch pipe 72 as indicated by the black arrows in FIG. 1, and is distributed to the liquid pipe 7 side and the exhaust side expansion valve 43 side.

[0061] The control device 10, which will be described in more detail later, controls the valve opening of the exhaust side expansion valve 43 based on the temperature of the exhaust A4 obtained from the exhaust side thermometer 45, and can adjust the amount of heat transfer medium flowing into the exhaust side expansion valve 43 side and the amount of heat transfer medium flowing into the liquid pipe 7 side per unit time.

[0062] The heat medium that has passed through the exhaust side expansion valve 43 is decompressed according to the valve opening of the exhaust side expansion valve 43, becomes a gas-liquid mixed state, and flows into the exhaust side heat exchanger 40 through the expansion valve side pipe 89. When passing through the exhaust side heat exchanger 40, the heat medium in the gas-liquid mixed state exchanges heat with the return air A3 sucked in by the exhaust side blower 44, and changes state to a low-pressure gas heat medium.

[0063] Thereafter, the low-pressure gas heat transfer medium passes through the solenoid valve side branch pipe 88, the low-pressure side solenoid valve 42, the indoor low-pressure gas branch pipe 62, the low-pressure gas pipe 6, the outdoor low-pressure gas branch pipe 60, the accumulator 29, and the suction pipe 61, in that order, as shown by the black arrows in Figure 1, and is recovered in the compressor 20.

[0064] 1, the liquid heat transfer medium that has flowed into the liquid pipe 7 passes through the liquid pipe 7, the outdoor liquid pipe 71, the receiver 28, and the outdoor liquid branch pipe 70 in that order, and is reduced in pressure by passing through the outdoor expansion valves 26, 27, becoming a gas-liquid mixed state, and flows into the outdoor heat exchangers 24, 25 through the expansion valve side pipes 82, 83. The gas-liquid mixed state heat transfer medium changes state to a low-pressure gas heat transfer medium by passing through the outdoor heat exchangers 24, 25, and then passes through the four-way valve side pipes 80, 81, the four-way valves 22, 23, the outdoor low-pressure gas branch pipe 60, the accumulator 29, and the suction pipe 61 in that order, and is recovered in the compressor 20.

[0065] Heating operation is generally performed in winter and other seasons when the outside air temperature is low. The temperature of the conditioned air A2 is adjusted by the condenser 30 to a temperature sufficiently higher than the outside air temperature, and the temperature of the room R can be raised to a temperature higher than the outside air. The inside air may be heated not only by the conditioned air A2, but also by other air conditioners, the body temperature of the user, heat radiation from various devices, and the like.

[0066] 1, the inside air that has been sufficiently heated in this manner is sucked into the upper space 91 as return air A3, and passes through the exhaust-side heat exchanger 40. The heat transfer medium can recover heat from the return air A3.

[0067] The return air A3 is cooled by exchanging heat with the exhaust-side heat exchanger 40, and is sent outdoors as low-temperature exhaust air A4. This makes it possible to prevent the exhaust air A4 that is colder than room temperature from flowing into the room R.

[0068] Incidentally, during periods when heating operation is performed, in order to recover thermal energy from the outside air only through the outdoor heat exchangers 24, 25, increase the specific enthalpy of the heat medium, and change the state of all of it to a low-pressure gas heat medium, it is necessary to reduce the pressure of the heat medium using the outdoor expansion valves 26, 27 and make its temperature lower than the outside air temperature.

[0069] Furthermore, in order to heat the pre-conditioning air A1, which is low-temperature outside air, through the condenser 30 to a temperature higher than the room temperature, it is necessary to compress the heat medium by the compressor 20 to make its temperature higher than the temperature of the room R. The pressure of the high-pressure gas heat medium is determined according to the set temperature of the inside air set by the user, etc.

[0070] In other words, the lower the outside air temperature, the lower the pressure of the low-pressure gas heat medium, and the higher the pressure ratio between the low-pressure gas heat medium and the high-pressure gas heat medium. It is a well-known fact that the higher the pressure ratio, the lower the volumetric efficiency, mechanical efficiency, and adiabatic efficiency, and the more electricity the compressor 20 consumes. In other words, the higher the pressure of the low-pressure gas heat medium, the smaller the pressure ratio, and the more electricity the compressor 20 consumes.

[0071] Furthermore, when the surface temperature of the outdoor heat exchangers 24, 25 falls below the frost point temperature of the outdoor air, frost forms on the surfaces of the outdoor heat exchangers 24, 25. As the frost progresses, the heat exchange efficiency decreases, and defrost operation becomes necessary. During the defrost operation, the supply of high-pressure gas heat medium to the condenser 30 is stopped, and the operation of the indoor blower 34 is also stopped, resulting in a decrease in air conditioning efficiency.

[0072] In the air conditioning apparatus 1 of this embodiment, during heating operation, heat can be recovered not only to the heat medium through the outdoor heat exchangers 24, 25 on the outdoor unit 2 side, but also to the heat medium through the exhaust side heat exchanger 40.

[0073] Here, the return air A3 contains at least a portion of the conditioned air A2 and has been heated. In the exhaust heat exchanger 40, the heat medium is exchanged with the return air A3 (e.g., 22°C) which has a higher temperature than the outside air (e.g., 0°C). In other words, the temperature of the heat medium immediately before flowing into the exhaust heat exchanger 40 can be made higher than the temperature of the heat medium immediately before flowing into the outdoor heat exchangers 24, 25.

[0074] In other words, the pressure of the heat medium immediately before flowing into the exhaust heat exchanger 40 can be made higher than the pressure of the heat medium immediately before flowing into the outdoor heat exchangers 24, 25, so that the pressure of the low-pressure gas heat medium after passing through the exhaust heat exchanger 40 can be made higher than the pressure of the low-pressure gas heat medium after passing through the outdoor heat exchangers 24, 25. By joining these heat mediums in the outdoor low-pressure gas branch pipe 60, the pressure of the low-pressure gas heat medium can be made appropriate.

[0075] In addition, the specific enthalpy of the heat medium immediately before flowing into the exhaust heat exchanger 40 can be made higher than the specific enthalpy of the heat medium immediately before flowing into the outdoor heat exchangers 24, 25, so that the specific enthalpy of the heat medium after passing through the exhaust heat exchanger 40 can be made higher than the specific enthalpy of the heat medium after passing through the outdoor heat exchangers 24, 25. By joining these heat mediums in the outdoor low-pressure gas branch pipe 60, the specific enthalpy of the low-pressure gas heat medium can be made appropriate. Therefore, it is possible to reduce the degree of pressure reduction by the outdoor expansion valves 26, 27.

[0076] In addition, it is possible to reduce the amount of heat medium per unit time passing through the outdoor heat exchangers 24, 25. As a result, it is possible to reduce the frequency of defrosting, compared to a configuration in which heat is exchanged only by the outdoor heat exchangers 24, 25.

[0077] As described above, during heating operation, the air conditioner 1 of this embodiment is designed to easily increase the pressure of the low-pressure gas heat medium before it is sucked into the compressor 20. This reduces the pressure ratio, making it possible to reduce the amount of power consumed by the compressor 20.

[0078] When a heating operation test was carried out using the air conditioner 1 of this embodiment, when the outdoor heat exchangers 24, 25 and the exhaust side heat exchanger 40 were used in combination, the pressure of the low pressure gas heat medium could be increased by about 70% compared to when only the outdoor heat exchangers 24, 25 were used. In addition, if the COP (Coefficient of Performance) when only the outdoor heat exchangers 24, 25 were used was set at 100, the COP when the outdoor heat exchangers 24, 25 and the exhaust side heat exchanger 40 were used in combination was about 145. In this way, the energy saving effect was confirmed.

[0079] Furthermore, the air conditioning device 1 can adjust the opening of the exhaust side expansion valve 43 according to the degree of superheat of the heat medium that has passed through the exhaust side heat exchanger 40 and the temperature of the exhaust A4 measured by the exhaust side thermometer 45. For example, by widening the opening of the exhaust side expansion valve 43, the degree of pressure reduction of the heat medium passing through can be reduced, and the pressure of the low-pressure gas heat medium can be increased. This makes it possible to prevent the pressure of the low-pressure gas heat medium immediately before being sucked into the compressor 20 from falling below a predetermined value. In other words, the exhaust side expansion valve 43 also functions as a temperature control valve. Note that a temperature control valve may be provided separately from the exhaust side expansion valve 43.

[0080] In more detail regarding the adjustment of the opening degree of the exhaust side expansion valve 43, the control device 10 acquires the evaporation temperature from the expansion valve side heat medium thermometer 47, acquires the superheated steam temperature from the solenoid valve side heat medium thermometer 46, and calculates the degree of superheat, which is the difference between the evaporation temperature and the superheated steam temperature. Note that the superheated steam temperature may be measured by measuring the temperature of the heat medium immediately before it flows into the compressor 20, or the location of measurement may be changed as appropriate.

[0081] The control device 10 compares the calculated degree of superheat with a preset superheat setting value, and if it determines that the calculated degree of superheat is smaller than the superheat setting value, it adjusts the opening of the exhaust side expansion valve 43 so that the degree of superheat is greater than the superheat setting value. This increases the specific enthalpy of the heat medium after passing through the exhaust side heat exchanger 40, and the entire amount can be changed into a low-pressure gas heat medium.

[0082] Furthermore, if it is determined that the calculated degree of superheat is greater than the set degree of superheat by a certain value or more, the opening degree of the exhaust side expansion valve 43 is adjusted according to the difference between the temperature of the exhaust air A4 measured by the exhaust side thermometer 45 and the target temperature. The target temperature is set to a value according to the temperature obtained from the thermometers 11, 35. Note that the target temperature may be set based on the temperature of the heat medium immediately after passing through the outdoor heat exchangers 24, 25 and the temperature of the heat medium immediately after passing through the exhaust side heat exchanger 40, and the setting method may be changed as appropriate.

[0083] For example, if the target temperature of the exhaust air A4 is 5 degrees but the temperature of the exhaust air A4 is 0°C, it is considered that the heat transfer medium is too depressurized by the exhaust side expansion valve 43. In such a case, the valve opening of the exhaust side expansion valve 43 is widened so that the temperature of the exhaust air A4 becomes 5 degrees, thereby decreasing the degree of pressure reduction, and thereby the pressure of the low-pressure gas heat transfer medium can be increased.

[0084] Furthermore, if the target temperature of the exhaust air A4 is 5 degrees but the temperature of the exhaust air A4 is 10°C, it is considered that the heat transfer medium has not been sufficiently depressurized by the exhaust side expansion valve 43. In such a case, the valve opening of the exhaust side expansion valve 43 is narrowed so that the temperature of the exhaust air A4 becomes 5 degrees, the degree of depressurization is increased, and the specific enthalpy can be increased.

[0085] In this way, by ensuring that the entire amount of heat medium passing through the exhaust side heat exchanger 40 is changed to a low-pressure gas heat medium, and by simply controlling the opening of the exhaust side expansion valve 43 so as to bring the temperature of the exhaust A4 closer to the target temperature, it is possible to more reliably prevent the pressure of the low-pressure gas heat medium just before it is sucked into the compressor 20 from falling below a predetermined value.

[0086] Moreover, if the pressure of the low-pressure gas heat medium rises excessively, the pressure of the high-pressure gas heat medium also rises excessively, and there is a risk of overloading each device. To prevent such a situation, when the pressure of the low-pressure gas heat medium detected by a pressure gauge (not shown) rises to or above a specific low-pressure value, the control device 10 closes the exhaust-side expansion valve 43 to stop heat exchange by the exhaust-side heat exchanger 40. This allows heat exchange only by the outdoor heat exchangers 24, 25, and reduces the pressure of the low-pressure gas heat medium.

[0087] Furthermore, when the indoor air temperature obtained from the indoor thermometer 11 is lower than the outside air temperature obtained from an outdoor thermometer (not shown) or the indoor thermometer 35, for example, immediately after the air conditioning device 1 starts operating, the control device 10 closes the exhaust side expansion valve 43 to stop heat exchange by the exhaust side heat exchanger 40. This allows heat exchange only by the outdoor heat exchangers 24, 25, and makes it possible to maintain the pressure of the low-pressure gas heat medium at or above a predetermined low pressure value.

[0088] In this embodiment, the pressure of the low-pressure gas heat transfer medium is adjusted by adjusting the valve opening of the exhaust side expansion valve 43, but the amount of air blown by the exhaust side blower 44 may also be adjusted, or these may be used in combination.

[0089] Next, there will be explained the reheat dehumidification operation by the air conditioner 1. Note that explanations that overlap with the heating operation will be omitted or simplified.

[0090] As shown in Fig. 2, the pre-conditioning air A1 sucked into the lower space 90 by the indoor blower 34 passes through the evaporator 31 and then the condenser 30, as indicated by the outlined arrow in Fig. 2. As a result, the pre-conditioning air A1 is cooled by heat exchange with the heat medium through the evaporator 31, and moisture contained in the pre-conditioning air A1 is discharged as water droplets, turning into dehumidified air with a reduced absolute humidity.

[0091] Thereafter, the dehumidified air is reheated and temperature-adjusted by heat exchange with the condenser 30, and the amount of saturated water vapor increases to become conditioned air A2 with a lowered relative humidity, which is then sent into the room R as shown by the double-lined arrow in Fig. 2. This makes it possible to lower the relative humidity while maintaining the room temperature of the room R.

[0092] Next, the flow of the heat medium during the reheat dehumidification operation will be described. In the outdoor unit 2, the controller 10 controls the valve position of the first four-way valve 22 to communicate the outdoor high-pressure gas branch pipe 51 with the first four-way valve side pipe 80 and to communicate the outdoor low-pressure gas branch pipe 60 with the first capillary tube 84. The controller 10 also controls the valve position of the second four-way valve 23 to communicate the outdoor high-pressure gas branch pipe 51 with the second capillary tube 85 and to communicate the outdoor low-pressure gas branch pipe 60 with the second four-way valve side pipe 81. The controller 10 also opens the first outdoor expansion valve 26 and closes the second outdoor expansion valve 27.

[0093] The high-pressure gas heat transfer medium discharged from the compressor 20 is distributed between the part that flows into the high-pressure gas pipe 5 and the part that flows into the first four-way valve side pipe 80, as shown by the black arrows in FIG.

[0094] The control device 10 sets the condenser-side valve 32 in the indoor unit 3 to an open state, and sets the evaporator-side expansion valve 33 in a throttle state.

[0095] In the exhaust side unit 4, the control device 10 opens the high pressure side solenoid valve 41, closes the low pressure side solenoid valve 42, and opens or closes the exhaust side expansion valve 43.

[0096] The high-pressure gas heat transfer medium that flows into the high-pressure gas pipe 5 side is distributed, as shown by the black arrows in Figure 2, into one that flows into the condenser 30 through the indoor high-pressure gas branch pipe 52, and into the exhaust side heat exchanger 40 through the indoor high-pressure gas branch pipe 52 and the solenoid valve side branch pipe 88.

[0097] The control device 10 controls the valve opening of the condenser-side valve 32 based on the temperature of the pre-conditioning air A1 and the temperature of the inside air obtained from the thermometers 11 and 35, and the humidity of the inside air obtained from the hygrometer 12, and can adjust the amount of heat medium flowing into the condenser 30 and the amount of heat medium flowing into the exhaust-side heat exchanger 40 per unit time. This enables the control device 10 to adjust the degree of reheating of the dehumidified air.

[0098] The high pressure gas heat transfer medium that has passed through the condenser 30 changes state to a liquid heat transfer medium, passes through the condenser side valve 32 and flows into the indoor side liquid branch pipe 72 .

[0099] The control device 10, which will be described in detail later, controls the valve opening of the exhaust side expansion valve 43 based on the temperature of the exhaust air A4 obtained from the exhaust side thermometer 45, and can adjust the amount of heat medium flowing into the exhaust side expansion valve 43 per unit time. The high-pressure gas heat medium that has passed through the exhaust side heat exchanger 40 exchanges heat with the return air A3 sucked in by the exhaust side blower 44 and changes state to a liquid heat medium, which passes through the expansion valve side pipe 89 and the exhaust side expansion valve 43 and flows into the indoor side liquid branch pipe 72.

[0100] On the other hand, the high-pressure gas heat transfer medium that has flowed into the first four-way valve side pipe 80 flows into the first outdoor heat exchanger 24, as indicated by the black arrows in Fig. 2. This high-pressure gas heat transfer medium exchanges heat with the outside air while passing through the first outdoor heat exchanger 24, changing its state to a liquid heat transfer medium, and passes through the first expansion valve side pipe 82, the first outdoor expansion valve 26, the outdoor liquid branch pipe 70, the receiver 28, the outdoor liquid pipe 71, and the liquid pipe 7, in that order, before flowing into the indoor liquid branch pipe 72.

[0101] 2, the liquid heat transfer medium that has flowed into the indoor liquid branch pipe 72 is decompressed according to the valve opening of the evaporator-side expansion valve 33 so that the entire liquid heat transfer medium changes state to a low-pressure gas heat transfer medium as it passes through the evaporator 31, and the liquid heat transfer medium changes state to a gas-liquid mixture and flows into the evaporator 31 through the evaporator-side pipe 87. When passing through the evaporator 31, this heat transfer medium exchanges heat with the pre-air-conditioning air A1 sucked in by the indoor blower 34, and changes state to a low-pressure gas heat transfer medium.

[0102] The control device 10 can adjust the amount of heat transfer medium flowing into the evaporator 31 per unit time by controlling the valve opening of the evaporator-side expansion valve 33 based on the temperature of the pre-conditioning air A1 obtained from the thermometers 11 and 35, the temperature of the inside air, and the humidity of the inside air obtained from the hygrometer 12. This enables the control device 10 to adjust the degree of cooling of the pre-conditioning air A1, in other words, the degree of dehumidification.

[0103] The low-pressure gas heat transfer medium then passes through the indoor low-pressure gas branch pipe 62, the low-pressure gas pipe 6, the outdoor low-pressure gas branch pipe 60, the accumulator 29, and the suction pipe 61, in that order, as indicated by the black arrows in Figure 2, and is recovered in the compressor 20.

[0104] Reheat dehumidification operation is generally performed in the summer or other seasons when the outside air is hot and humid. The temperature of the conditioned air A2 is adjusted to a temperature sufficiently lower than the outside air temperature while being reheated by the condenser 30, and the temperature of the room R can be lowered to a temperature lower than the outside air. The inside air may be cooled not only by the conditioned air A2, but also by other air conditioners.

[0105] The inside air that has been sufficiently cooled in this manner is sucked into the upper space 91 as return air A3, as indicated by the outlined arrow in Fig. 2, and passes through the exhaust-side heat exchanger 40. The heat transfer medium can release heat to the return air A3.

[0106] The return air A3 is heated by exchanging heat with the exhaust-side heat exchanger 40, and is sent outside as high-temperature exhaust air A4. This makes it possible to prevent the exhaust air A4 hotter than room temperature from flowing into the room R.

[0107] Incidentally, in order to release the heat of the heat medium only through the outdoor heat exchanger 24 during periods when reheat dehumidification operation is performed, thereby lowering the specific enthalpy of the heat medium and making the heat medium supercooled, it is necessary to compress the heat medium using the compressor 20 and make the temperature of the high-pressure gas heat medium higher than the temperature of the outside air.

[0108] Furthermore, in order to cool the pre-conditioning air A1, which is high-temperature and high-humidity outdoor air, through the evaporator 31 to a temperature lower than the dew point temperature, it is necessary to reduce the pressure of the heat medium using the evaporator-side expansion valve 33 to a temperature lower than the dew point temperature of the pre-conditioning air A1. The pressure of the heat medium after passing through the evaporator-side expansion valve 33 is determined according to the humidity of the inside air set by the user, etc.

[0109] In other words, the higher the outside air temperature, the higher the pressure of the high-pressure gas heat medium, and the larger the pressure ratio between the low-pressure gas heat medium and the high-pressure gas heat medium, which increases the amount of power consumed by the compressor 20. In other words, the more the pressure of the high-pressure gas heat medium is reduced, the smaller the pressure ratio becomes, and the amount of power consumed by the compressor 20 can be reduced.

[0110] In the air conditioning apparatus 1 of this embodiment, during reheat dehumidification operation, it is possible to release heat from the heat medium not only through the outdoor heat exchanger 24 on the outdoor unit 2 side, but also through the exhaust side heat exchanger 40.

[0111] Here, the return air A3 contains at least a portion of the conditioned air A2 and is cooled. In the exhaust heat exchanger 40, the heat medium is exchanged with the return air A3 (e.g., 28°C) which has a lower temperature than the outside air (e.g., 35°C). In other words, the temperature of the heat medium after passing through the exhaust heat exchanger 40 can be made lower than the temperature of the heat medium after passing through the outdoor heat exchanger 24.

[0112] In other words, the specific enthalpy of the heat medium after passing through the exhaust heat exchanger 40 can be made lower than the specific enthalpy of the heat medium after passing through the outdoor heat exchanger 24. In other words, even if the degree of compression by the compressor 20 is reduced, the specific enthalpy of the liquid heat medium joined in the indoor liquid branch pipe 72 can be made appropriate.

[0113] It is also possible to reduce the amount of heat medium passing through the first outdoor heat exchanger 24 per unit time. From this point of view, it is also possible to reduce the degree of compression by the compressor 20.

[0114] As described above, the air conditioning device 1 of this embodiment is able to easily reduce the pressure of the high-pressure gas heat transfer medium discharged from the compressor 20 during reheat dehumidification operation. This reduces the pressure ratio, thereby making it possible to reduce the amount of power consumed by the compressor 20.

[0115] When a reheat dehumidification operation test was conducted using the air conditioner 1 of this embodiment, when the outdoor heat exchanger 24 and the exhaust side heat exchanger 40 were used in combination, the pressure of the high-pressure gas heat medium could be reduced by about 20% compared to when only the outdoor heat exchanger 24 was used. In addition, if the COP when only the outdoor heat exchanger 24 was used was taken as 100, the COP when the outdoor heat exchanger 24 and the exhaust side heat exchanger 40 were used in combination was about 120. In this way, the energy saving effect was confirmed.

[0116] Furthermore, the air conditioning device 1 can adjust the opening of the exhaust side expansion valve 43 according to the degree of supercooling of the heat medium that has passed through the exhaust side heat exchanger 40 and the temperature of the exhaust A4 measured by the exhaust side thermometer 45. For example, by narrowing the opening of the exhaust side expansion valve 43, the temperature of the liquid heat medium flowing into the evaporator side expansion valve 33 can be adjusted so as not to drop excessively. This prevents the liquid heat medium from becoming excessively supercooled, which would require a large degree of pressure reduction by the evaporator side expansion valve 33 to turn the entire amount into a low-pressure gas heat medium, and prevents the pressure of the low-pressure gas heat medium from falling below a predetermined low pressure value.

[0117] More specifically, the control device 10 obtains the condensation temperature from the solenoid valve side heat medium thermometer 46 and the subcooled liquid temperature from the expansion valve side heat medium thermometer 47, and calculates the degree of subcooling, which is the difference between these temperatures. Note that the subcooled liquid temperature may be measured by measuring the temperature of the heat medium immediately before it flows into the evaporator side expansion valve 33, or the location of measurement may be changed as appropriate.

[0118] The control device 10 compares the calculated degree of supercooling with a preset degree of supercooling set value, and if it determines that the calculated degree of supercooling is greater than the preset value, it adjusts the opening of the exhaust side expansion valve 43 so that the degree of supercooling becomes smaller than the preset value. This reduces the specific enthalpy of the heat medium after passing through the exhaust side heat exchanger 40, and allows the entire amount to change into a liquid heat medium state.

[0119] In addition, if it is determined that the calculated degree of subcooling is smaller than the set subcooling degree value by a certain value or more, the opening degree of the exhaust side expansion valve 43 is adjusted according to the difference between the temperature of the exhaust A4 measured by the exhaust side thermometer 45 and a preset target temperature.

[0120] For example, if the target temperature of the exhaust air A4 is 40 degrees but the temperature of the exhaust air A4 is 45°C, it is considered that the amount of high-pressure gas heat transfer medium supplied to the exhaust air heat exchanger 40 per unit time is too large, that is, the opening degree of the exhaust air expansion valve 43 is too wide. In such a case, the degree of supercooling can be adjusted to an appropriate level by narrowing the valve opening degree of the exhaust air expansion valve 43 so that the temperature of the exhaust air A4 becomes 40 degrees.

[0121] Furthermore, if the target temperature of the exhaust air A4 is 40 degrees but the temperature of the exhaust air A4 is 35°C, it is considered that the amount of high-pressure gas heat medium supplied per unit time by the exhaust side expansion valve 43 to the exhaust side heat exchanger 40 is too small, in other words, the aperture of the exhaust side expansion valve 43 is too narrow. In such a case, the degree of supercooling can be adjusted to an appropriate level by widening the valve aperture of the exhaust side expansion valve 43 so that the temperature of the exhaust air A4 becomes 40 degrees.

[0122] In this way, by ensuring that the entire amount of heat transfer medium passing through the exhaust side heat exchanger 40 is changed to a liquid heat transfer medium, and by simply controlling the opening of the exhaust side expansion valve 43 so as to bring the temperature of the exhaust A4 closer to the target temperature, it is possible to more reliably prevent the pressure of the low-pressure gas heat transfer medium just before it is sucked into the compressor 20 from falling below a predetermined value.

[0123] Moreover, if the pressure of the low-pressure gas heat medium drops excessively, the amount of power consumed by the compressor 20 increases. To prevent such a situation, when the pressure of the low-pressure gas heat medium detected by a pressure gauge (not shown) drops below a special low-pressure value, the control device 10 closes the exhaust-side expansion valve 43 to stop heat exchange by the exhaust-side heat exchanger 40. This allows heat exchange only in the first outdoor heat exchanger 24, and increases the specific enthalpy of the liquid heat medium in the indoor-side liquid branch pipe 72, thereby increasing the pressure of the low-pressure gas heat medium after passing through the evaporator 31.

[0124] Furthermore, when the indoor air temperature obtained from the indoor thermometer 11 is higher than the outside air temperature obtained from an outdoor thermometer (not shown) or an indoor thermometer 35, for example, immediately after the air conditioning apparatus 1 starts operating, the control device 10 closes the exhaust side expansion valve 43 to stop heat exchange by the exhaust side heat exchanger 40. This allows heat exchange only by the first outdoor heat exchanger 24, making it possible to lower the pressure of the high-pressure gas heat medium.

[0125] In this embodiment, the valve opening of the exhaust side expansion valve 43 is adjusted to adjust the degree of supercooling of the liquid heat transfer medium, but this is not limited to this, and the amount of air blown by the exhaust side blower 44 may also be adjusted, or these may be used in combination.

[0126] Furthermore, in this embodiment, the control device 10 has been described as being configured to set the first outdoor expansion valve 26 to an open state and the second outdoor expansion valve 27 to a closed state during reheat dehumidification operation, but this is not limited to this, and the first outdoor expansion valve 26 may be set to a closed state and the second outdoor expansion valve 27 to an open state, or both the first outdoor expansion valve 26 and the second outdoor expansion valve 27 may be set to an open state.

[0127] As described above, the air conditioner 1 of this embodiment can reduce the energy required to operate the compressor 20 and achieve energy savings by exchanging heat between the heat medium and the return air A3.

[0128] Furthermore, in the air conditioning device 1, the outdoor heat exchangers 24, 25 and the exhaust heat exchanger 40 are arranged in separate spaces that may have different temperature environments, making it possible to adjust the amount of heat medium passing through the exhaust heat exchanger 40 per unit time and the pressure ratio of the heat medium according to the temperature environment of each space. This makes it possible to stably achieve energy savings.

[0129] Furthermore, the air conditioner 1 can prevent the pressure of the heat medium from falling below a predetermined value through simple control of adjusting the opening degree of the exhaust side expansion valve 43 in accordance with the temperature of the exhaust air A4.

[0130] Furthermore, the air conditioner 1 gradually adjusts the opening degree of the exhaust side expansion valve 43. This makes it possible to prevent shocks caused by a sudden change in the amount of heat medium supplied.

[0131] Furthermore, the air conditioner 1 can configure a flow path according to the operating state by simple control of appropriately switching the solenoid valves 41, . EXAMPLES

[0132] Next, an air conditioner according to a second embodiment will be described with reference to Fig. 3 to Fig. 8. Note that a description of configurations that are the same as those in the above embodiment and overlap with each other will be omitted.

[0133] 3 to 8, the air conditioner 101 of this embodiment is configured to be able to switch the function of the exhaust heat exchanger 40 between heating operation and reheat dehumidification operation.

[0134] The air conditioner 101 is equipped with a high-pressure pressure gauge 150 provided downstream of the compressor 20, and a low-pressure pressure gauge 160 provided upstream of the compressor 20. These pressure gauges 150, 160 are electrically connected to the control device 110 via communication lines 17, 18.

[0135] First, the heating operation by the air conditioner 101 will be described. With reference to Fig. 3 to Fig. 5, the control device 110 is capable of switching between a high-load state and a low-load state during heating operation. For example, when the temperature difference between the outside air temperature and the set temperature is large, such as when the outside air temperature is -5 degrees and the inside air set temperature is 22 degrees, the operation control is performed in the high-load state.

[0136] 3, in a high-load state, because the temperature difference between the temperature of the pre-conditioning air A1 and the set temperature is large, the control device 110 increases the amount of heat medium passing through the condenser 30 per unit time. As a result, a large amount of heat is transferred from the heat medium to the pre-conditioning air A1, so that conditioned air A2, which has a higher temperature than the pre-conditioning air A1, can be supplied to the room R.

[0137] Under high load conditions, as in the heating operation of the first embodiment, the exhaust side heat exchanger 40 functions as an evaporator, and the heat transfer medium passing through the exhaust side heat exchanger 40 recovers heat from the return air A3, which has a temperature higher than the outside air temperature, making it easier to increase the pressure of the low-pressure gas heat transfer medium before it is sucked into the compressor 20.

[0138] In a high load state during heating operation, the control device 110 controls the valve opening of the exhaust side expansion valve 43 based on the temperature of the exhaust air A4 obtained from the exhaust side thermometer 45 so that the heat transfer medium is at an appropriate degree of pressure reduction.

[0139] The control device 110 performs operation control in a low load state when the temperature difference between the outside air and the set temperature is small, for example, when the outside air temperature is 18 degrees and the inside air set temperature is 22 degrees, such as during the intermediate season.

[0140] In a low load state, because the temperature difference between the temperature of the pre-conditioning air A1 and the set temperature is small, the control device 110 reduces the amount of heat medium passing through the condenser 30 per unit time. This reduces the amount of heat transferred from the heat medium to the pre-conditioning air A1, making it possible to supply conditioned air A2, which has a slightly higher temperature than the pre-conditioning air A1, to the room R.

[0141] In a low load state, the control device 110 selects and controls the exhaust side unit 4 in one of an evaporator mode, a blower mode, and a condenser mode. As shown in FIG. 3, in the evaporator mode, the exhaust side heat exchanger 40 functions as an evaporator, similarly to a high load state. As shown in FIG. 4, in the blower mode, the supply of heat medium to the exhaust side heat exchanger 40 is stopped. As shown in FIG. 5, in the condenser mode, the exhaust side heat exchanger 40 functions as a condenser. Hereinafter, the switching between the modes will be described.

[0142] If the pressure of the low-pressure gas heat medium detected by the low-pressure pressure gauge 160 in the low-load state is less than the first low-pressure specific value, i.e., within the normal range, the control device 110 sets the exhaust side unit 4 to the evaporator mode as shown in Fig. 3. As a result, in the evaporator mode, as in the high-load state, the heat medium passing through the exhaust side heat exchanger 40 recovers heat from the return air A3, which has a temperature slightly higher than the outside air temperature, making it easier to increase the pressure of the low-pressure gas heat medium before it is sucked into the compressor 20.

[0143] In a low load state, the amount of heat medium passing through the condenser 30 per unit time is small, and therefore the amount of heat released through the condenser 30 is small. Also, the smaller the difference between the temperature of the outside air and the temperature of the inside air, in other words, the higher the temperature of the outside air, the more heat is recovered from the outside air through the outdoor heat exchangers 24, 25. Since this is in addition to the amount of heat recovered through the exhaust side heat exchanger 40 in the evaporator mode described above, heat dissipation becomes insufficient, and further, heat recovery becomes excessive, which may result in an increase in the pressure of the low-pressure gas heat medium.

[0144] When the control device 110 determines that the pressure of the low-pressure gas heat medium detected by the low-pressure pressure gauge 160 has risen to or above the first low-pressure specific value, it closes the exhaust-side expansion valve 43 and switches the exhaust-side unit 4 to the blowing mode, as shown in Fig. 4. This stops the liquid heat medium that has passed through the condenser-side valve 32 from flowing into the exhaust-side heat exchanger 40, and stops the heat recovery from the return air A3. In addition, since the amount of heat medium that recovers heat from the outside air through the outdoor heat exchangers 24, 25 increases, it is easier to lower the pressure of the low-pressure gas heat medium than in the evaporator mode.

[0145] In addition, in the blowing mode, the low pressure side solenoid valve 42 remains open. This makes it possible to prevent liquid sealing between the high pressure side solenoid valve 41 and the low pressure side solenoid valve 42 and the exhaust side expansion valve 43.

[0146] In addition, in the air blowing mode, the supply of the conditioned air A2 to the room R and the blowing by the exhaust side blower 44 continue. This makes it possible to keep the pressure in the room R constant while continuing the heating operation.

[0147] When the control device 110 determines that the pressure of the low-pressure gas heat transfer medium detected by the low-pressure pressure gauge 160 has fallen below the first low-pressure specific value, it opens the exhaust side expansion valve 43 and switches the exhaust side unit 4 to the evaporator mode (see Figure 3).

[0148] On the other hand, depending on factors such as high outdoor temperature or rainy weather, even in the fan mode, the amount of heat recovered through the outdoor heat exchangers 24, 25 may increase, and the pressure of the low-pressure gas heat medium may continue to increase.

[0149] When the control device 110 determines that the pressure of the low-pressure gas heat medium detected by the low-pressure pressure gauge 160 has reached or exceeded a second low-pressure specific value that is higher than the first low-pressure specific value, it switches the exhaust side unit 4 to a condenser mode by opening the high-pressure side solenoid valve 41, closing the low-pressure side solenoid valve 42, and opening the exhaust side expansion valve 43, as shown in Fig. 5. In the condenser mode during heating operation, the control device 110 controls the valve opening degree of the exhaust side expansion valve 43 based on the temperature of the exhaust air A4 obtained from the exhaust side thermometer 45 so that the heat medium is appropriately supercooled.

[0150] In the condenser mode, the high-pressure gas heat transfer medium sent from the compressor 20 is divided between the exhaust heat exchanger 40 and the condenser 30. This allows the heat transfer medium other than that required for heating the pre-air-conditioning air A1 to be supplied to the exhaust heat exchanger 40, and heat to be released to the return air A3. In other words, since it becomes possible to release excess heat, the pressure of the low-pressure gas heat transfer medium can be efficiently reduced.

[0151] In the condenser mode, the supply of conditioned air A2 to the room R and the blowing by the exhaust-side blower 44 continue. This makes it possible to maintain a constant pressure in the room R while continuing the heating operation. Furthermore, since the exhaust air A4 after passing through the exhaust-side heat exchanger 40 is sent outdoors, it is possible to prevent the exhaust air A4 hotter than room temperature from flowing into the room R.

[0152] When the control device 110 determines that the pressure of the low-pressure gas heat medium detected by the low-pressure pressure gauge 160 has fallen below the second low-pressure specific value, it switches to the blowing mode by closing the high-pressure side solenoid valve 41, opening the low-pressure side solenoid valve 42, and closing the exhaust side expansion valve 43 (see Figure 4).

[0153] As described above, in the air conditioning apparatus 101 of this embodiment, when the pressure of the heat medium reaches or exceeds a specific value during heating operation, the exhaust side heat exchanger 40, which had been functioning as an evaporator, can be made to function as a condenser, so that the excessively high pressure of the heat medium can be reduced while continuing the heating operation of the room R.

[0154] Furthermore, during heating operation, the air conditioning device 101 can stop heat exchange by the exhaust heat exchanger 40, which has been functioning as an evaporator, before causing the exhaust heat exchanger 40 to function as a condenser, thereby preventing a sudden change in pressure of the heat medium. In addition, the occurrence of overshoot and undershoot can be suppressed.

[0155] Furthermore, the air conditioner 101 switches the function of the exhaust heat exchanger 40 based on the pressure of the low-pressure gas heat medium detected by the low-pressure pressure gauge 160, so that stable heating operation can be continued.

[0156] Next, the reheat dehumidification operation by the air conditioner 101 will be described. With reference to Fig. 6 to Fig. 8, the control device 110 is capable of switching between a high-load state and a low-load state in the reheat dehumidification operation. When there is a large temperature difference between the outside air and the set temperature, for example when the outside air temperature is 35 degrees and the set temperature of the inside air is 25 degrees, and further when there is a large humidity difference between the outside air and the set humidity, for example when the relative humidity of the outside air is 80% and the set humidity of the inside air is 55%, the control device 110 performs operation in the high-load state.

[0157] 6, in a high-load state, the control device 110 increases the amount of heat transfer medium passing through the evaporator 31 per unit time because the difference in humidity between the relative humidity of the pre-conditioning air A1 and the set humidity is large. This allows a large amount of heat to be transferred from the pre-conditioning air A1 to the heat transfer medium, increasing the degree of cooling of the dehumidified air, in other words, the degree of dehumidification. This makes it possible to supply conditioned air A2, which has a lower relative humidity than the pre-conditioning air A1, to the room R.

[0158] In a high load state, as in the reheat dehumidification operation of the first embodiment, the exhaust heat exchanger 40 functions as a condenser and the heat medium passing through the exhaust heat exchanger 40 releases heat to the return air A3, which has a lower temperature than the outside air temperature, making it easier to reduce the pressure of the low-pressure gas heat medium. As described above, by reducing the pressure of the low-pressure gas heat medium, the pressure of the high-pressure gas heat medium can also be reduced. Hereinafter, it will be simply described as "reducing the pressure of the high-pressure gas heat medium".

[0159] In a high-load state during reheat dehumidification operation, the control device 110 controls the valve opening of the exhaust side expansion valve 43 based on the temperature of the exhaust air A4 obtained from the exhaust side thermometer 45 so that the heat transfer medium is appropriately supercooled.

[0160] The control device 110 performs operation control in a low load state when the temperature difference between the outside air and the set temperature is small, for example, during the intermediate season when the outside air temperature is 27 degrees and the set indoor temperature is 25 degrees, and when the humidity difference between the outside air and the set humidity is small, for example, when the relative humidity of the outside air is 60% and the set indoor humidity is 55%.

[0161] In a low load state, the control device 110 reduces the amount of heat medium passing through the evaporator 31 per unit time because the difference in humidity between the relative humidity of the pre-conditioning air A1 and the set humidity is small. This reduces the amount of heat transferred from the pre-conditioning air A1 to the heat medium, making it possible to reduce the degree of cooling of the dehumidified air, in other words, the degree of dehumidification. This makes it possible to supply conditioned air A2, which has a slightly lower relative humidity than the pre-conditioning air A1, to the room R.

[0162] In a low load state, the control device 110 selects and controls the exhaust side unit 4 in one of a condenser mode, a blower mode, and an evaporator mode. As shown in FIG. 6, in the condenser mode, the exhaust side heat exchanger 40 is made to function as a condenser, similarly to the high load state. As shown in FIG. 7, in the blower mode, the supply of heat medium to the exhaust side heat exchanger 40 is stopped. As shown in FIG. 8, in the evaporator mode, the exhaust side heat exchanger 40 is made to function as an evaporator. Hereinafter, the switching between the modes will be described.

[0163] If the pressure of the high-pressure gas heat medium detected by the high-pressure pressure gauge 150 in the low load state exceeds the first predetermined high-pressure value, i.e., if it is within the normal range, the control device 110 sets the exhaust side unit 4 to the condenser mode as shown in Fig. 6. As a result, in the condenser mode, as in the high-load state, the heat medium passing through the exhaust side heat exchanger 40 releases heat to the return air A3, which has a temperature slightly lower than the outside air temperature, making it easier to reduce the pressure of the high-pressure gas heat medium sent out from the compressor 20.

[0164] In a low load state, the amount of heat recovered through the evaporator 31 decreases. Also, the smaller the difference between the outside air temperature and the inside air temperature, in other words, the lower the outside air temperature, the more heat is released through the outdoor heat exchangers 24, 25. Since this also includes the amount of heat released through the exhaust side heat exchanger 40 in the condenser mode described above, the heat recovery becomes insufficient and the heat dissipation becomes excessive, which may cause a drop in the pressure of the high-pressure gas heat transfer medium.

[0165] When the control device 110 determines that the pressure of the high-pressure gas heat medium detected by the high-pressure pressure gauge 150 has fallen below the first predetermined high-pressure value, it closes the high-pressure side solenoid valve 41 and switches the exhaust side unit 4 to the blowing mode, as shown in Fig. 7. This stops the high-pressure gas heat medium sent out from the compressor 20 from flowing into the exhaust side heat exchanger 40, and stops the release of heat to the return air A3. In addition, by causing most or all of the heat medium that had flowed into the exhaust side heat exchanger 40 to flow into the outdoor heat exchangers 24, 25, the amount of heat medium that releases heat to the outside air increases, making it easier to increase the pressure of the high-pressure gas heat medium.

[0166] In addition, in the blowing mode, the exhaust side expansion valve 43 is narrowed down to a slightly open state, which prevents the heat medium that has passed through the condenser side valve 32 from flowing into the exhaust side heat exchanger 40, while preventing liquid sealing between the high pressure side solenoid valve 41 and the low pressure side solenoid valve 42 and the exhaust side expansion valve 43.

[0167] In addition, in the air blowing mode, the supply of the conditioned air A2 to the room R and the blowing by the exhaust side blower 44 continue. This makes it possible to keep the pressure in the room R constant while continuing the reheat dehumidification operation.

[0168] When the control device 110 determines that the pressure of the high-pressure gas heat transfer medium detected by the high-pressure pressure gauge 150 has exceeded the high-pressure first predetermined value, it opens the high-pressure side solenoid valve 41 and the exhaust side expansion valve 43 and switches the exhaust side unit 4 to condenser mode (see Figure 6).

[0169] On the other hand, depending on factors such as high outside temperature or rainy weather, even in the fan mode, the amount of heat released through the outdoor heat exchangers 24, 25 may increase, causing the pressure of the high-pressure gas heat transfer medium to continue to decrease.

[0170] When the control device 110 determines that the pressure of the high-pressure gas heat medium detected by the high-pressure pressure gauge 150 has become equal to or lower than a second predetermined high-pressure value lower than the first predetermined high-pressure value, it switches the exhaust side unit 4 to an evaporator mode by closing the high-pressure side solenoid valve 41, opening the low-pressure side solenoid valve 42, and opening the exhaust side expansion valve 43, as shown in Fig. 8. In the evaporator mode during reheat dehumidification operation, the control device 110 controls the valve opening of the exhaust side expansion valve 43 based on the temperature of the exhaust air A4 obtained from the exhaust side thermometer 45 so that the heat medium is appropriately decompressed.

[0171] In the evaporator mode, the liquid heat transfer medium that has passed through the condenser-side valve 32 is divided between the exhaust-side heat exchanger 40 and the evaporator 31. This makes it possible to supply heat transfer medium other than that required for cooling the pre-air-conditioning air A1 to the exhaust-side heat exchanger 40, and recover heat from the return air A3. In other words, it becomes possible to recover the insufficient amount of heat, and therefore the pressure of the high-pressure gas heat transfer medium can be increased efficiently.

[0172] In the evaporator mode, the supply of conditioned air A2 to the room R and the blowing by the exhaust side blower 44 continue. This makes it possible to maintain a constant pressure in the room R while continuing the reheat dehumidification operation. Furthermore, since the exhaust air A4 after passing through the exhaust side heat exchanger 40 is sent outdoors, it is possible to prevent the exhaust air A4 that is cooler than room temperature from flowing into the room R.

[0173] When the control device 110 determines that the pressure of the high-pressure gas heat transfer medium detected by the high-pressure pressure gauge 150 has exceeded the second predetermined low-pressure value, it switches to the blowing mode by closing the high-pressure side solenoid valve 41, closing the low-pressure side solenoid valve 42, and throttling the exhaust side expansion valve 43 (see Figure 7).

[0174] As described above, in the air conditioning apparatus 101 of this embodiment, when the pressure of the heat medium falls below a predetermined value during reheat dehumidification operation, the exhaust side heat exchanger 40, which had been functioning as a condenser, can be made to function as an evaporator, so that the pressure of the heat medium that has dropped too much can be increased while continuing the reheat dehumidification operation in the room R.

[0175] Furthermore, during reheat dehumidification operation, the air conditioner 101 stops heat exchange by the exhaust heat exchanger 40 before causing the exhaust heat exchanger 40, which had been functioning as a condenser, to function as an evaporator, thereby making it possible to prevent a sudden change in pressure of the heat medium. In addition, it is possible to prevent the occurrence of overshoot and undershoot.

[0176] Furthermore, the air conditioner 101 switches the function of the exhaust heat exchanger 40 based on the pressure of the high-pressure gas heat medium detected by the high-pressure pressure gauge 150, so that stable reheat dehumidification operation can be continued.

[0177] Although the embodiments of the present invention have been described above with reference to the drawings, the specific configuration is not limited to these embodiments, and the present invention also includes modifications and additions that do not deviate from the gist of the present invention.

[0178] For example, in the above-mentioned Examples 1 and 2, a configuration has been described in which one outdoor unit, one indoor unit, and one exhaust side unit are provided, but this is not limited to this, and there may be multiple and equal numbers of outdoor units, indoor units, and exhaust side units, and the numbers of outdoor units, indoor units, and exhaust side units do not have to be equal as long as they are one or more.

[0179] In addition, in the above-mentioned first and second embodiments, the opening degree of the exhaust side expansion valve is adjusted according to the degree of superheat or subcooling of the heat medium that has passed through the exhaust side heat exchanger and the measured exhaust temperature. However, the present invention is not limited to this, and the opening degree of the exhaust side expansion valve may be adjusted only according to the degree of superheat or subcooling of the heat medium that has passed through the exhaust side heat exchanger.

[0180] In addition, in the first and second embodiments, the on-off valve is described as being a solenoid valve, but this is not limited thereto, and the on-off valve may be a manually operated on-off valve, or may be modified as appropriate as long as it is a valve that can be opened and closed. [Explanation of symbols]

[0181] 1. Air conditioning equipment 2. Outdoor unit 3 Indoor unit 4 Exhaust side unit 5. High pressure gas pipes 6. Low pressure gas pipes 7 Liquid Pipe 9. Cabinet 10 Control device 20 Compressor 24 1st outdoor heat exchanger 25 2nd outdoor heat exchanger 30 Condenser 31 Evaporator 40 Exhaust side heat exchanger 41 High pressure side solenoid valve (on-off valve) 42 Low pressure side solenoid valve (on-off valve) 43 Exhaust side expansion valve 44 Exhaust side fan (exhaust means) 44a Air outlet (exhaust port) 45 Exhaust temperature gauge 46 Solenoid valve side heat medium temperature gauge 47 Expansion valve side heat transfer medium thermometer 92 Partition material 98 Exhaust side vent (intake) 101 Air conditioning equipment 110 Control device A1 Air before air conditioning A2 Conditioned air A3 Return air (taken in indoor air) A4 exhaust R Indoor

Claims

1. an outdoor unit incorporating at least a compressor and an outdoor heat exchanger; An indoor unit incorporating at least a condenser and an evaporator; An air conditioning apparatus comprising a high-pressure gas pipe, a low-pressure gas pipe, and a liquid pipe connected across the outdoor unit and the indoor unit, An exhaust means for taking in indoor air and discharging it to the outside of the room; The present invention further includes an exhaust-side heat exchanger for exchanging heat between the air taken in from the room and a heat medium, The air conditioner according to claim 1, wherein the exhaust side heat exchanger is connected to the high pressure gas pipe, the low pressure gas pipe, and the liquid pipe so as to be able to communicate with each other.

2. The air conditioning apparatus according to claim 1, characterized in that the exhaust means and the exhaust side heat exchanger are built into an exhaust side unit having an intake port for taking in air from the room and an exhaust port for discharging the taken-in air.

3. 3. The air conditioner according to claim 2, wherein the indoor unit and the exhaust unit are each provided in a single housing separated by a partition material.

4. an expansion valve is provided between the exhaust heat exchanger and the liquid pipe; 2. The air conditioner according to claim 1, wherein the opening degree of the expansion valve is adjusted according to the degree of superheat or subcooling of the heat medium that has passed through the exhaust-side heat exchanger.

5. A temperature sensor is provided downstream of the exhaust heat exchanger, 5. The air conditioner according to claim 4, wherein the expansion valve has an opening adjusted in response to the temperature detected by the temperature sensor.

6. 6. The air conditioner according to claim 1, wherein the exhaust heat exchanger is connected to the low pressure gas pipe and the high pressure gas pipe via an on-off valve so as to be able to communicate with each other.

7. 7. The air conditioner according to claim 6, wherein the on-off valve is opened on the side of the low-pressure gas pipe and closed on the side of the high-pressure gas pipe during heating operation.

8. The air-conditioning apparatus according to claim 7, characterized in that, when the pressure of the heat medium reaches or exceeds a specific value during the heating operation, the on-off valve closes the low-pressure gas pipe side and opens the high-pressure gas pipe side.

9. The air conditioning apparatus according to claim 8, characterized in that an expansion valve provided between the exhaust side heat exchanger and the liquid pipe is closed when the pressure of the heat medium approaches the specific value, and is opened when the pressure of the heat medium becomes equal to or greater than the specific value.

10. 7. The air conditioner according to claim 6, wherein the on-off valve is opened on the side of the high pressure gas pipe and closed on the side of the low pressure gas pipe during a dehumidifying operation.

11. The air-conditioning apparatus according to claim 10, characterized in that, when the pressure of the heat medium falls below a predetermined value during the dehumidification operation, the on-off valve closes the high-pressure gas pipe side and opens the low-pressure gas pipe side.

12. the on-off valve closes the high pressure gas pipe side and the low pressure gas pipe side when the pressure of the heat medium approaches the predetermined value, The air conditioning apparatus according to claim 11, characterized in that an expansion valve provided between the exhaust side heat exchanger and the liquid pipe is throttled when the pressure of the heat medium approaches the predetermined value, and is opened when the pressure of the heat medium falls below the predetermined value.

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