Ventilation air conditioning system

Abstract

To obtain a ventilation air conditioning system which can prevent reduction of the volume of ventilating air caused by freezing in a heat exchanger and enables reduction of a heating load.SOLUTION: A ventilation air conditioning system 100 includes: an air conditioner 1 having an outdoor unit 12 which heats a refrigerant, and an indoor unit 11 including a first condenser 21 which heats air to be sent to an indoor space by the refrigerant; a ventilation device 3 having a heat exchanger 31 which conducts heat exchange between air to be supplied from an outdoor space to an indoor space and air discharged from the indoor space to the outdoor space, the ventilation device 3 configured to supply air to the indoor space and exhaust air from the indoor space; a second condenser 22 which heats the heat exchanger 31 with the refrigerant; and a refrigerant circulation circuit part 20 forming a passage of the refrigerant which is transported from the outdoor unit 12 to each of the first condenser 21 and the second condenser 22 and returned to the outdoor unit 12.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a ventilation and air-conditioning system including an air conditioner having an outdoor unit and an indoor unit, and a ventilation device having a heat exchanger. [Background technology]

[0002] A ventilation device is known that includes an intake fan that sends air taken in from an outdoor inlet to an indoor outlet, an exhaust fan that sends air taken in from an indoor inlet to an outdoor outlet, and a heat exchanger. In the heat exchanger, heat is exchanged between air flowing from the outdoor inlet to the indoor outlet and air flowing from the indoor inlet to the outdoor outlet. In such a ventilation device, when the outdoor air temperature drops significantly, the indoor air taken in from the indoor inlet is cooled by the outdoor air taken in from the outdoor inlet, and water vapor contained in the indoor air may freeze in the heat exchanger. For this reason, a problem with conventional ventilation devices that include a heat exchanger is that the ventilation air volume may decrease due to freezing in the heat exchanger.

[0003] Patent Document 1 discloses a ventilation device in which a first set temperature and a second set temperature lower than the first set temperature are set, and when the outside air temperature is equal to or lower than the first set temperature and higher than the second set temperature, the supply air blower operates intermittently, and when the outside air temperature is equal to or lower than the second set temperature, the supply air blower is stopped to perform type 3 ventilation. The ventilation device disclosed in Patent Document 1 can prevent a decrease in ventilation air volume due to freezing on the heat exchanger by warming the heat exchanger with air taken in from the indoor intake port when the outside air temperature is equal to or lower than the second set temperature. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 4656777 Summary of the Invention [Problem to be solved by the invention]

[0005] In the conventional technology disclosed in Patent Document 1, depending on the outdoor temperature conditions, the operation of the supply air blower is stopped for a certain period of time, and the volume of supply air in the room is not secured. The shortage of the volume of supply air in the room is made up through the opening of the building. In this case, the outside air flows into the room at the same temperature as the outside, so the heating load increases significantly compared to when supply air is provided with heat exchange.

[0006] The present disclosure has been made in consideration of the above, and aims to provide a ventilation and air-conditioning system that can prevent a decrease in ventilation air volume due to freezing in the heat exchanger and can reduce the heating load. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems and achieve the object, the ventilation and air conditioning system of the present disclosure comprises an air conditioning device having an outdoor unit that heats a refrigerant and an indoor unit including a first condenser that heats air to be sent into the room with the refrigerant, a ventilation device that has a heat exchanger that performs heat exchange between air supplied from the outside to the room and air exhausted from the room to the outside, and supplies air to the room and exhausts air from the room, a second condenser that heats the heat exchanger with refrigerant, and a refrigerant circulation circuit section that forms a flow path for refrigerant that is transported from the outdoor unit to each of the first condenser and the second condenser and returned to the outdoor unit. Effect of the Invention

[0008] The ventilation and air-conditioning system according to the present disclosure has the advantage that it is possible to prevent a decrease in ventilation air volume due to freezing in the heat exchanger, and to reduce the heating load. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a first diagram showing a configuration example of a ventilation air-conditioning system according to a first embodiment; [Diagram 2] FIG. 2 is a second diagram showing a configuration example of a ventilation air-conditioning system according to embodiment 1. [Diagram 3] FIG. 3 is a third diagram showing an example of the configuration of the ventilation air-conditioning system according to the first embodiment. [Figure 4] A flowchart showing the procedure of the operation of the ventilation air-conditioning system according to the first embodiment. [Diagram 5] FIG. 1 is a diagram showing an example of the configuration of a control circuit according to a first embodiment; [Figure 6] FIG. 1 is a diagram showing an example of the configuration of a dedicated hardware circuit according to a first embodiment; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A ventilation air-conditioning system according to an embodiment will be described in detail below with reference to the drawings.

[0011] Embodiment 1 Fig. 1 is a first diagram showing an example configuration of a ventilating air-conditioning system 100 according to embodiment 1. The ventilating air-conditioning system 100 is a system that performs indoor ventilation and indoor air conditioning. The ventilating air-conditioning system 100 includes an air conditioner 1 that performs indoor air conditioning, and a ventilator 3 that performs indoor ventilation.

[0012] The air conditioner 1 includes an indoor unit 11 that uses the heat of a refrigerant to send warmed air into the room of the building 4, and an outdoor unit 12 that heats the refrigerant. The ventilation device 3 ventilates the room of the building 4 by discharging indoor air to the outside, that is, outside the building 4, and sending outdoor air into the room. The ventilation device 3 has a heat exchanger 31 that exchanges heat between air supplied from the outside to the room and air discharged from the room to the outside, and supplies air to the room and exhausts air from the room.

[0013] 1, two rooms 48 in a building 4 are subject to ventilation and air conditioning by the ventilation and air conditioning system 100. In the first embodiment, the interior of the building 4 refers to the inside of each room 48. Note that the number of rooms 48 subject to ventilation and air conditioning by the ventilation and air conditioning system 100 is not limited to two, and may be one, or three or more.

[0014] The outdoor unit 12 includes an expansion valve 121, an evaporator 122, a compressor 123, and a refrigerant circuit section 124. The expansion valve 121 reduces the pressure of the refrigerant to expand the refrigerant. The evaporator 122 absorbs heat from outside air into the refrigerant. The compressor 123 pressurizes the refrigerant.

[0015] The refrigerant circuit section 124 is a flow path of the refrigerant in the outdoor unit 12. The refrigerant circuit section 124 has two connection ports 124a, 124b. The connection port 124a is an inlet of the refrigerant circuit section 124. The connection port 124b is an outlet of the refrigerant. The refrigerant flows into the outdoor unit 12 from the connection port 124a. The refrigerant that flows into the outdoor unit 12 travels through the refrigerant circuit section 124, passing through the expansion valve 121, the evaporator 122, and the compressor 123 in this order, before reaching the connection port 124b.

[0016] The ventilation and air-conditioning system 100 includes a refrigerant circulation circuit section 20. The refrigerant circulation circuit section 20 constitutes a flow path for the refrigerant that is transported from the outdoor unit 12 to each of the first condenser 21 and the second condenser 22 and returned to the outdoor unit 12. The first condenser 21 and the second condenser 22 will be described in detail later. The refrigerant circulation circuit section 20 is made up of a plurality of pipes. Each of the plurality of pipes that constitute the refrigerant circulation circuit section 20 is a steel pipe. By wrapping each pipe with a heat insulating material, the heat radiation loss of the refrigerant in the refrigerant circulation circuit section 20 is reduced.

[0017] In the first embodiment, the ventilation device 3 is installed in a living space in a building 4. The building 4 is provided with an outdoor intake port 41 for taking in air outside the building 4, and an outdoor outlet port 42 for discharging air outside the building 4. An indoor outlet port 43 for supplying air to the room is provided in the ceiling of each living room 48. The building 4 is provided with an outdoor air duct 44, an exhaust duct 45, and an air supply duct 46. The building 4 is provided with a return air duct 47 through which air returns from each living room 48 to the ventilation device 3 and the indoor unit 11.

[0018] The ventilation device 3 is not limited to being installed in a living space. The ventilation device 3 may be installed in any space in the building 4, such as under the floor, in the ceiling, in a machine room, or in the attic.

[0019] One end of the outdoor air duct 44 is connected to the outdoor intake port 41. The other end of the outdoor air duct 44 is connected to the outdoor air duct 32 in the ventilation device 3. One end of the exhaust duct 45 is connected to the outdoor air outlet 42. The other end of the exhaust duct 45 is connected to the exhaust air duct 33 in the ventilation device 3. The supply air duct 46 is connected to the indoor unit 11 and the indoor air outlets 43 of each room 48. The supply air duct 46 constitutes an air duct through which air sent from the indoor unit 11 to the room passes.

[0020] In the example shown in Fig. 1, the indoor unit 11 and the ventilation device 3 are adjacent to each other. The indoor unit 11 is connected to an intake air duct 34 in the ventilation device 3. Air blown out from the intake air duct 34 is taken into the indoor unit 11. In addition, air is taken into the indoor unit 11 from a return air duct 47.

[0021] The indoor unit 11 includes a first condenser 21 and a blower 111. The first condenser 21 heats the air sent into the room with a refrigerant. The blower 111 sends the air taken into the indoor unit 11 from both the ventilation device 3 and the return air duct 47 to the supply air duct 46. By operating the blower 111, air is taken into the indoor unit 11 from both the ventilation device 3 and the return air duct 47. The air taken into the indoor unit 11 from both the ventilation device 3 and the return air duct 47 is mixed in the indoor unit 11 and blown out to the supply air duct 46.

[0022] The outside air duct 32, the exhaust air duct 33, the supply air duct 34, and the return air duct 35 are provided in the housing 30 of the ventilation device 3. The heat exchanger 31 is housed in the housing 30. Arranged in the housing 30 are an intake air blower 36 that sends air taken in from the outside into the room, and an exhaust air blower 37 that sends air taken in from the room to the outside. The intake air blower 36 is arranged in the outside air duct 32. The exhaust air blower 37 is arranged in the exhaust air duct 33.

[0023] The supply air blower 36 generates an supply air flow that passes through the outdoor air inlet 41 and the outdoor air duct 44 and enters the housing 30. The supply air flow passes through the outdoor air duct 32, the heat exchanger 31, and the supply air duct 34 in this order within the housing 30. The supply air flow that has passed through the housing 30 passes through the indoor unit 11, the supply air duct 46, and the indoor air outlet 43, and is blown out into the room.

[0024] Exhaust fan 37 generates an exhaust flow that passes through return air duct 47 and enters housing 30. The exhaust flow passes through return air duct 35, heat exchanger 31, and exhaust air duct 33 in this order within housing 30. The exhaust flow that has passed through housing 30 passes through exhaust duct 45 and exterior air outlet 42 and is blown out to the outside.

[0025] Each of the intake air blower 36 and the exhaust air blower 37 may be disposed outside the housing 30. Two or more intake air blowers 36 may be disposed in the ventilation device 3, and two or more exhaust air blowers 37 may be disposed.

[0026] In FIG. 1, the white arrow marked "OA" represents the state where air outside the building 4 is sucked into the outdoor air inlet 41. In FIG. 1, the white arrow marked "EA" represents the state where air is blown out of the building 4 from the outdoor air outlet 42. In FIG. 1, the white arrow marked "SA1" represents the state where air flows from the supply air duct 34 of the ventilation device 3 to the indoor unit 11. In FIG. 1, the white arrow marked "SA2" represents the state where air is blown out from the indoor air outlet 43 into the room. In FIG. 1, the white arrow marked "RA1" represents the state where indoor air is sucked into the return air duct 47. In FIG. 1, the white arrow marked "RA2" represents the state where air in the return air duct 47 is sucked into each of the indoor unit 11 and the return air duct 35 of the ventilation device 3.

[0027] The heat exchanger 31 has a primary air passage through which the exhaust air flows and a secondary air passage through which the intake air flows. In the heat exchanger 31, the primary air passage and the secondary air passage are perpendicular to each other. The primary air passage and the secondary air passage are formed in a laminated body formed by alternately bonding sheet materials and spacing materials. The sheet material is, for example, flat paperboard that has been processed to be flat. The spacing material is, for example, corrugated paperboard. The corrugated paperboard is paper that has been given a corrugated unevenness. In the heat exchanger 31, total heat exchange between the exhaust air flow and the intake air flow is performed via the flat paperboard. Note that the primary air passage and the secondary air passage are not shown in FIG. 1.

[0028] In the laminate, corrugated paperboards are alternately stacked with flat paperboards sandwiched between them, with the corrugated paperboards oriented in different directions so that the fold directions of the corrugations are perpendicular to each other. As a result, primary air passages and secondary air passages are alternately provided in the heat exchanger 31 in the stacking direction. In the flat paperboards, sensible heat exchange and latent heat exchange are performed between the intake airflow and the exhaust airflow without mixing the intake airflow and the exhaust airflow. Note that the heat exchanger 31 may perform only one of sensible heat exchange and latent heat exchange.

[0029] Here, the heat exchanger 31 is an orthogonal type heat exchanger in which the intake air flow direction and the exhaust air flow direction are perpendicular to each other, but the present invention is not limited to this. The heat exchanger 31 may be a counterflow type heat exchanger in which the intake air flow direction and the exhaust air flow direction are 180 degrees different from each other. The shape of the spacing member may be sawtooth, sinusoidal, rectangular, or any of these shapes that have been modified. The spacing member may be a combination of multiple plate pieces.

[0030] The first condenser 21 has two connection ports 21a and 21b. The refrigerant flows into the first condenser 21 from the connection port 21a or the connection port 21b. When the refrigerant flows into the first condenser 21 from the connection port 21a, the refrigerant in the first condenser 21 flows out of the first condenser 21 through the connection port 21b. When the refrigerant flows into the first condenser 21 from the connection port 21b, the refrigerant in the first condenser 21 flows out of the first condenser 21 through the connection port 21a. In the first condenser 21, the heat of the refrigerant in the first condenser 21 is transferred to the heat medium, which is the air in the indoor unit 11. As a result, the first condenser 21 heats the air sent into the room.

[0031] The second condenser 22 is attached to the heat exchanger 31. The second condenser 22 heats the heat exchanger 31 with the refrigerant. FIG. 1 shows the second condenser 22 attached to the heat exchanger 31 in a schematic manner. The second condenser 22 has two connection ports 22a and 22b. The refrigerant flows into the second condenser 22 from the connection port 22a or the connection port 22b. When the refrigerant flows into the second condenser 22 from the connection port 22a, the refrigerant in the second condenser 22 flows out of the second condenser 22 through the connection port 22b. When the refrigerant flows into the second condenser 22 from the connection port 22b, the refrigerant in the second condenser 22 flows out of the second condenser 22 through the connection port 22a.

[0032] When the refrigerant is transported from the outdoor unit 12 to the second condenser 22 in the refrigerant circulation circuit section 20, heat of the refrigerant in the second condenser 22 is transferred to the heat exchanger 31. The heat of the refrigerant is transferred to the heat exchanger 31, whereby the heat exchanger 31 is heated. The ventilation air-conditioning system 100 melts ice adhering to the heat exchanger 31 by heating the heat exchanger 31. Furthermore, the ventilation air-conditioning system 100 suppresses the progression of freezing in the heat exchanger 31 by heating the heat exchanger 31. The ventilation air-conditioning system 100 can ensure the ventilation air volume of the ventilation device 3 by melting ice adhering to the heat exchanger 31 or by suppressing the progression of freezing in the heat exchanger 31.

[0033] The second condenser 22 is disposed with a metal tube constituting the second condenser 22 in contact with the exhaust flow inlet of the heat exchanger 31. The position of the second condenser 22 in the heat exchanger 31 and the shape of the second condenser 22 are both arbitrary. When a material such as a metal having high thermal conductivity is used for the heat exchanger 31, the entire heat exchanger 31 may be heated by bringing the metal tube of the second condenser 22 into contact with an arbitrary position of the material.

[0034] The ventilation and air-conditioning system 100 switches the refrigerant circulation circuit unit 20 between a first state in which the transport of refrigerant to the second condenser 22 is stopped, and a second state in which the refrigerant is transported to the second condenser 22. The refrigerant circulation circuit unit 20 has a first flow path 25 and a second flow path 26. The first flow path 25 is a flow path through which the refrigerant that flows out of the first condenser 21 passes when returning to the outdoor unit 12 in the first state. The second flow path 26 is a flow path that transports the refrigerant to the second condenser 22 in the second state.

[0035] The ventilation and air-conditioning system 100 includes a flow path switching valve 23 which is a first valve, and a directional control valve 24 which is a second valve. The flow path switching valve 23 switches the flow path of the refrigerant between a first flow path 25 and a second flow path 26. The flow path switching valve 23 functions as a switching unit which switches the refrigerant circulation circuit unit 20 between a first state in which the transport of the refrigerant to the second condenser 22 is stopped, and a second state in which the refrigerant is transported to the second condenser 22. The flow path switching valve 23 has three connection ports 23a, 23b, and 23c.

[0036] The directional control valve 24 switches the direction in which the refrigerant flows in the refrigerant circulation circuit section 20. In the second state, the directional control valve 24 switches the direction in which the refrigerant flows between a direction in which the refrigerant that flows from the outdoor unit 12 to the first condenser 21 passes through the second condenser 22 and returns to the outdoor unit 12, and a direction in which the refrigerant that flows from the outdoor unit 12 to the second condenser 22 passes through the first condenser 21 and returns to the outdoor unit 12. The directional control valve 24 has four connection ports 24a, 24b, 24c, and 24d.

[0037] The connection port 23a of the flow path switching valve 23 is connected to the connection port 21b of the first condenser 21 via a pipe. The connection port 23b of the flow path switching valve 23 is connected to the connection port 24c of the direction switching valve 24 via a pipe. The connection port 23c of the flow path switching valve 23 is connected to the connection port 22a of the second condenser 22 via a pipe. The connection port 24a of the direction switching valve 24 is connected to the connection port 124b of the outdoor unit 12 via a pipe. The connection port 24b of the direction switching valve 24 is connected to the connection port 21a of the first condenser 21 via a pipe. The connection port 24d of the direction switching valve 24 is connected to the connection port 124a of the outdoor unit 12 via a pipe. The connection port 22b of the second condenser 22 is connected to a connection point 27 via a pipe. The connection point 27 is provided in the pipe between the connection port 23b of the flow path switching valve 23 and the connection port 24c of the direction switching valve 24. The first flow path 25 is a flow path between the connection port 23b of the flow path switching valve 23 and the connection point 27. The second flow path 26 is a flow path between the connection port 23c of the flow path switching valve 23 and the connection port 22a of the second condenser 22, and a flow path between the connection port 22b of the second condenser 22 and the connection point 27.

[0038] The ventilation air-conditioning system 100 includes a control device 5 that controls the ventilation air-conditioning system 100. The control device 5 is connected to each of the ventilation device 3, the indoor unit 11, the outdoor unit 12, the flow path switching valve 23, and the directional control valve 24 by communication lines. In Fig. 1, the dashed lines between each of the indoor unit 11, the flow path switching valve 23, and the directional control valve 24 and the control device 5 represent communication lines. Note that in Fig. 1, the communication lines connecting each of the ventilation device 3 and the outdoor unit 12 to the control device 5 are omitted.

[0039] The control device 5 instructs the flow path switching valve 23 to switch the flow path by sending a control signal to the flow path switching valve 23. The flow path switching valve 23 performs an operation to switch the flow path in accordance with the control signal sent from the control device 5. The control device 5 instructs the direction switching valve 24 to switch the flow path by sending a control signal to the direction switching valve 24. The direction switching valve 24 performs an operation to switch the flow path in accordance with the control signal sent from the control device 5. The direction switching valve 24 switches the flow path, thereby switching the direction in which the refrigerant flows in the refrigerant circulation circuit unit 20.

[0040] The control device 5 functions as a freezing detection unit that detects freezing in the heat exchanger 31. The flow path switching valve 23 switches the refrigerant circulation circuit unit 20 between a first state in which the transfer of the refrigerant to the second condenser 22 is stopped and a second state in which the refrigerant is transferred to the second condenser 22, based on the detection result by the control device 5 that is the freezing detection unit.

[0041] Here, first to third methods will be described as examples of methods for detecting icing by the control device 5. Whichever of the first to third methods is applied, the ventilation air-conditioning system 100 can detect icing in the heat exchanger 31 with a simple configuration. Note that the method for detecting icing by the control device 5 is not limited to the first to third methods described below, but may be any method.

[0042] In the first method, a wind speed sensor 39 is disposed in the ventilation device 3, and the control device 5 detects freezing based on the wind speed detected by the wind speed sensor 39. That is, in the first method, the control device 5 detects freezing in the heat exchanger 31 based on the detection result by the wind speed sensor 39. The wind speed sensor 39 detects the wind speed of the air discharged from the inside of the room to the outside of the room in the ventilation device 3. FIG. 1 shows an example in which the wind speed sensor 39 is disposed in the return air duct 35 in the ventilation device 3. When the wind speed sensor 39 is disposed, the control device 5 is connected to the wind speed sensor 39 by a communication line. In FIG. 1, the communication line connecting the wind speed sensor 39 and the control device 5 is omitted. The wind speed sensor 39 outputs a signal indicating the detected wind speed to the control device 5 via the communication line.

[0043] When the heat exchanger 31 is frozen, the ice adhering to the heat exchanger 31 blocks the airflow, and the exhaust airflow of the ventilation device 3 decreases compared to when there is no ice. The control device 5 determines that the heat exchanger 31 is frozen when the wind speed value detected by the wind speed sensor 39 is smaller than a preset threshold value. According to the first method, the control device 5 can reliably determine whether or not the exhaust airflow is secured by detecting the wind speed. This allows the ventilation air-conditioning system 100 to accurately detect the icing in the heat exchanger 31.

[0044] In the second method, the control device 5 detects icing in the heat exchanger 31 based on the load on the exhaust fan 37. When the air flow is blocked by icing, causing an increase in pressure loss and a decrease in the exhaust air volume, the pressure decreases near the impeller of the exhaust fan 37, reducing the load on the impeller of the exhaust fan 37. As the load on the impeller of the exhaust fan 37 decreases, the driving force of the motor that drives the impeller decreases.

[0045] When the heat exchanger 31 is frozen, the load on the exhaust fan 37 is smaller than when there is no ice. That is, when the heat exchanger 31 is frozen, the driving force of the motor of the exhaust fan 37 is smaller than when there is no ice. The control device 5 detects the load on the exhaust fan 37 by measuring the driving force of the motor of the exhaust fan 37. When the value of the driving force is smaller than a preset threshold value, the control device 5 determines that there is ice on the heat exchanger 31. According to the second method, the control device 5 does not need to place a component for detecting ice in the air passage. This allows the ventilation air-conditioning system 100 to detect ice on the heat exchanger 31 without increasing the airflow resistance of the ventilation device 3.

[0046] In the third method, the control device 5 detects freezing by detecting the temperature difference between the outdoor air and the air sent from the ventilation device 3 to the room. FIG. 1 shows an example in which two outdoor air temperature detectors 51, 52 that detect the outdoor air temperature, which is the temperature of the outdoor air, and a supply air temperature detector 53 that detects the supply air temperature, which is the temperature of the air sent from the ventilation device 3 to the room, are arranged. When the outdoor air temperature detectors 51, 52 and the supply air temperature detector 53 are arranged, the control device 5 is connected to each of the outdoor air temperature detectors 51, 52 and the supply air temperature detector 53 by a communication line. Each of the outdoor air temperature detectors 51, 52 and the supply air temperature detector 53 outputs a signal indicating the detected temperature to the control device 5 via communication. Note that in FIG. 1, the communication lines connecting the control device 5 to each of the outdoor air temperature detectors 51, 52 and the supply air temperature detector 53 are omitted.

[0047] The outdoor air temperature detector 51 is disposed in the outdoor air duct 32 in the ventilation device 3. The outdoor air temperature detector 51 detects the outdoor air temperature by detecting the temperature of air passing through the outdoor air duct 32. The outdoor air temperature detector 52 is disposed in the outdoor unit 12. The outdoor air temperature detector 52 detects the outdoor air temperature in the outdoor unit 12. The supply air temperature detector 53 is disposed in the supply air duct 34 in the ventilation device 3. The supply air temperature detector 53 detects the supply air temperature by detecting the temperature of air passing through the supply air duct 34.

[0048] When the heat exchanger 31 is frozen, the difference between the outside air temperature and the supply air temperature is smaller than when there is no freezing. The control device 5 determines that the heat exchanger 31 is frozen when the difference between the outside air temperature and the supply air temperature is smaller than a preset threshold value. In the third method, the state of heat transfer from the heat exchanger 31 to the supply air flow is known from the temperature difference between the outdoor air and the air sent from the ventilation device 3 to the room. The control device 5 can determine that the heat exchanger 31 is frozen when no heat is provided from the heat exchanger 31 to the supply air flow or when the heat provided from the heat exchanger 31 to the supply air flow is insufficient. This allows the ventilation air-conditioning system 100 to accurately detect freezing in the heat exchanger 31.

[0049] In the case of the third method, the ventilation and air-conditioning system 100 may have only one of the two outdoor temperature detectors 51, 52. The ventilation and air-conditioning system 100 may use one of the two outdoor temperature detectors 51, 52 as a main outdoor temperature detector and the other as an auxiliary outdoor temperature detector. The control device 5 may obtain temperature information based on a signal from the main outdoor temperature detector, and when a signal cannot be obtained from the main outdoor temperature detector, obtain outdoor temperature information based on a signal from the auxiliary outdoor temperature detector. The ventilation and air-conditioning system 100 may obtain information indicating the outdoor temperature from a temperature detection means other than the outdoor temperature detectors 51, 52.

[0050] 1 shows wind speed sensor 39, outside air temperature detectors 51 and 52, and supply air temperature detector 53, but if the first method is not implemented, wind speed sensor 39 may be omitted. If the third method is not implemented, outside air temperature detectors 51 and 52, and supply air temperature detector 53 may be omitted. Ventilation and air conditioning system 100 may be provided with any configuration used in a method for detecting freezing.

[0051] The control device 5 functions as a measurement unit that measures the elapsed time, which is the time since freezing in the heat exchanger 31 is detected. The control device 5 starts counting the elapsed time when freezing begins to be detected. The control device 5 continues counting the elapsed time while the state in which freezing is detected continues. After starting to count the elapsed time, the control device 5 stops counting the elapsed time when freezing is no longer detected.

[0052] In the above description, the air conditioner 1 sends air heated by using a refrigerant in the indoor unit 11 into the room, but is not limited to this. The air conditioner 1 may send a heat medium heated by using a refrigerant in the indoor unit 11 to a radiator provided in each room 48. In this case, the air conditioner 1 performs air conditioning in the room by releasing heat of the heat medium from the radiator into the room.

[0053] Next, an operation of the ventilation air-conditioning system 100 will be described. While the operation of the ventilation device 3 continues, the control device 5 monitors the presence or absence of icing in the heat exchanger 31. When icing in the heat exchanger 31 is detected, the control device 5 compares the elapsed time from when the icing was detected with a preset first time.

[0054] The control device 5 instructs the flow path switching valve 23 to open the first flow path 25 and close the second flow path 26 when freezing in the heat exchanger 31 is not detected or when the elapsed time from when freezing in the heat exchanger 31 began to be detected is less than a first time. The flow path switching valve 23 opens the first flow path 25 and closes the second flow path 26 when freezing in the heat exchanger 31 is not detected or when the elapsed time is less than the first time. In other words, when freezing is not detected or when the elapsed time is less than the first time, the flow path switching valve 23 puts the refrigerant circulation circuit unit 20 into a first state in which the transport of the refrigerant to the second condenser 22 is stopped.

[0055] In the example shown in FIG. 1, the flow path switching valve 23 opens the first flow path 25 by opening the connection port 23a and the connection port 23b, and closes the second flow path 26 by closing the connection port 23c.

[0056] Furthermore, when freezing in the heat exchanger 31 is not detected or when the elapsed time from when freezing in the heat exchanger 31 was first detected is less than a first time, the control device 5 instructs the directional control valve 24 to pass the refrigerant between the connection port 24a and the connection port 24b and between the connection port 24c and the connection port 24d. When freezing is not detected or when the elapsed time is less than a first time, the directional control valve 24 passes the refrigerant between the connection port 24a and the connection port 24b and passes the refrigerant between the connection port 24c and the connection port 24d. As a result, the directional control valve 24 changes the flow direction of the refrigerant in the refrigerant circulation circuit section 20 so that the refrigerant that has flowed from the outdoor unit 12 to the first condenser 21 returns to the outdoor unit 12 through the connection point 27.

[0057] 1 shows the ventilation air-conditioning system 100 when the refrigerant circulation circuit unit 20 is in a first state. The straight arrows shown in FIG.

[0058] When the refrigerant circulation circuit section 20 is in the first state, the refrigerant flowing out of the connection port 124b of the outdoor unit 12 passes through the connection port 24a and the connection port 24b of the directional control valve 24 and heads toward the first condenser 21. The refrigerant flows into the first condenser 21 from the connection port 21a of the first condenser 21. After heat is removed from the refrigerant in the first condenser 21, the refrigerant flows out of the first condenser 21 through the connection port 21b. The refrigerant that flows out of the first condenser 21 passes through the connection port 23a and the connection port 23b of the flow path switching valve 23, and reaches the connection port 24c of the direction switching valve 24 via the connection point 27. That is, the refrigerant passes through the first flow path 25 and reaches the connection port 24c of the direction switching valve 24. The refrigerant passes through the connection port 24c and the connection port 24d of the direction switching valve 24 and reaches the connection port 124a of the outdoor unit 12. The refrigerant that flows into the outdoor unit 12 from the connection port 124a of the outdoor unit 12 is heated in the outdoor unit 12 and flows out of the outdoor unit 12 again from the connection port 124b of the outdoor unit 12.

[0059] 1, the dashed line in flow path switching valve 23 indicates that the refrigerant passes between connection port 23a and connection port 23b in flow path switching valve 23. In Fig. 1, one of the two dashed lines in direction switching valve 24 indicates that the refrigerant passes between connection port 24a and connection port 24b in direction switching valve 24, and the other of the two dashed lines in direction switching valve 24 indicates that the refrigerant passes between connection port 24c and connection port 24d in direction switching valve 24.

[0060] When the elapsed time from when freezing in the heat exchanger 31 is first detected exceeds a first time, the control device 5 instructs the flow path switching valve 23 to close the first flow path 25 and open the second flow path 26. When the elapsed time exceeds the first time, the flow path switching valve 23 closes the first flow path 25 and opens the second flow path 26. In other words, when the elapsed time exceeds the first time, the flow path switching valve 23 puts the refrigerant circulation circuit unit 20 into a second state in which the refrigerant is transported to the second condenser 22.

[0061] Furthermore, when the elapsed time from when freezing begins to be detected exceeds the first time, the control device 5 compares the elapsed time with the second time. The second time is a time longer than the first time and is a preset time. When the elapsed time does not reach the second time, the control device 5 instructs the directional control valve 24 to pass the refrigerant between the connection port 24a and the connection port 24b and between the connection port 24c and the connection port 24d. When the elapsed time does not reach the second time, the directional control valve 24 passes the refrigerant between the connection port 24a and the connection port 24b and passes the refrigerant between the connection port 24c and the connection port 24d. As a result, the directional control valve 24 changes the flow direction of the refrigerant in the refrigerant circulation circuit section 20 so that the refrigerant that flows from the outdoor unit 12 to the first condenser 21 passes through the second condenser 22 and returns to the outdoor unit 12.

[0062] When the elapsed time from when freezing was first detected exceeds a second time, the control device 5 instructs the directional control valve 24 to pass the refrigerant between the connection port 24a and the connection port 24c and between the connection port 24b and the connection port 24d. When the elapsed time exceeds the second time, the directional control valve 24 passes the refrigerant between the connection port 24a and the connection port 24c and passes the refrigerant between the connection port 24b and the connection port 24d. As a result, the directional control valve 24 changes the flow direction of the refrigerant in the refrigerant circulation circuit section 20 so that the refrigerant that has flowed from the outdoor unit 12 to the second condenser 22 passes through the first condenser 21 and returns to the outdoor unit 12.

[0063] Fig. 2 is a second diagram showing an example configuration of the ventilation air-conditioning system 100 according to Embodiment 1. Fig. 2 shows the ventilation air-conditioning system 100 when the refrigerant circulation circuit unit 20 is in a second state and the time that has elapsed since freezing began to be detected is less than a second time. The straight arrows and broken line arrows shown in Fig. 2 indicate the direction in which the refrigerant flows in the refrigerant circulation circuit unit 20.

[0064] When the refrigerant circulation circuit section 20 is in the second state and the elapsed time from when freezing started to be detected is less than the second time, the flow path of the refrigerant from the connection port 124b of the outdoor unit 12 to the connection port 23a of the flow path switching valve 23 is the same as that shown in FIG. 1. The refrigerant passes through the connection port 23a and the connection port 23c of the flow path switching valve 23 toward the second condenser 22. The refrigerant flows into the second condenser 22 from the connection port 22a of the second condenser 22. After heat is removed in the second condenser 22, the refrigerant flows out of the second condenser 22 through the connection port 22b. The refrigerant that flows out of the second condenser 22 reaches the connection port 24c of the directional control valve 24 through the connection point 27. That is, the refrigerant passes through the second flow path 26 and reaches the connection port 24c of the directional control valve 24. The refrigerant passes through connection port 24c and connection port 24d in the directional control valve 24, and reaches connection port 124a of the outdoor unit 12. The refrigerant that flows into the outdoor unit 12 from connection port 124a of the outdoor unit 12 is heated in the outdoor unit 12, and flows out of the outdoor unit 12 again from connection port 124b of the outdoor unit 12.

[0065] 2, the dashed line in flow path switching valve 23 indicates that the refrigerant passes between connection port 23a and connection port 23c in flow path switching valve 23. In Fig. 2, one of the two dashed lines in direction switching valve 24 indicates that the refrigerant passes between connection port 24a and connection port 24b in direction switching valve 24, and the other of the two dashed lines in direction switching valve 24 indicates that the refrigerant passes between connection port 24c and connection port 24d in direction switching valve 24.

[0066] 2, the flow path switching valve 23 opens the second flow path 26 by opening the connection port 23a and the connection port 23c, and closes the first flow path 25 by closing the connection port 23b. The directional control valve 24 passes the refrigerant between the connection port 24a and the connection port 24b and passes the refrigerant between the connection port 24c and the connection port 24d, thereby changing the flow direction of the refrigerant from the outdoor unit 12 to the first condenser 21 to return to the outdoor unit 12 through the second condenser 22.

[0067] Fig. 3 is a third diagram showing an example configuration of the ventilation air-conditioning system 100 according to the first embodiment. Fig. 3 shows the ventilation air-conditioning system 100 when the refrigerant circulation circuit unit 20 is in the second state and the time that has elapsed since freezing began to be detected exceeds the second time. The straight arrows and broken line arrows shown in Fig. 3 indicate the direction in which the refrigerant flows in the refrigerant circulation circuit unit 20.

[0068] When the refrigerant circulation circuit section 20 is in the second state and the temperature detected by the outdoor air temperature detector 51 is equal to or lower than the second temperature, the refrigerant flowing out of the connection port 124b of the outdoor unit 12 passes through the connection port 24a and the connection port 24c in the directional control valve 24, and passes through the connection point 27 to the second condenser 22. The refrigerant flows into the second condenser 22 from the connection port 22b of the second condenser 22. After heat is removed in the second condenser 22, the refrigerant flows out of the second condenser 22 through the connection port 22a. The refrigerant that has flowed out of the second condenser 22 passes through the connection port 23c and the connection port 23a in the flow path switching valve 23 to the first condenser 21. The refrigerant flows into the first condenser 21 from the connection port 21b of the first condenser 21. The refrigerant from which heat has been removed in the first condenser 21 passes through the connection port 21a and flows out of the first condenser 21. The refrigerant that has flowed out of the first condenser 21 passes through the connection port 24b and the connection port 24d in the directional control valve 24, and reaches the connection port 124a of the outdoor unit 12. The refrigerant that has flowed into the outdoor unit 12 from the connection port 124a of the outdoor unit 12 is heated in the outdoor unit 12, and flows out of the outdoor unit 12 again from the connection port 124b of the outdoor unit 12.

[0069] 3, the dashed line in flow path switching valve 23 indicates that the refrigerant passes between connection port 23a and connection port 23c in flow path switching valve 23. In Fig. 3, one of the two dashed lines in direction switching valve 24 indicates that the refrigerant passes between connection port 24a and connection port 24c in direction switching valve 24, and the other of the two dashed lines in direction switching valve 24 indicates that the refrigerant passes between connection port 24b and connection port 24d in direction switching valve 24.

[0070] 3, the flow path switching valve 23 opens the second flow path 26 by opening the connection port 23a and the connection port 23c, and closes the first flow path 25 by closing the connection port 23b. The directional control valve 24 passes the refrigerant between the connection port 24a and the connection port 24c and passes the refrigerant between the connection port 24b and the connection port 24d, so that the refrigerant flows in a direction in which the refrigerant that has flowed from the outdoor unit 12 to the second condenser 22 passes through the first condenser 21 and returns to the outdoor unit 12. In FIG. 3, the flow direction of the refrigerant in the refrigerant circulation circuit section 20 is opposite to that shown in FIG. 2.

[0071] As described above, the flow path switching valve 23 sets the refrigerant circulation circuit section 20 to the first state when freezing in the heat exchanger 31 is not detected or when the elapsed time from when freezing began to be detected is less than the first time. The flow path switching valve 23 sets the refrigerant circulation circuit section 20 to the second state when the elapsed time from when freezing began to be detected exceeds the first time. In this way, the flow path switching valve 23 switches the refrigerant circulation circuit section 20 between the first state and the second state based on whether freezing has been detected and the elapsed time from when freezing began to be detected. The ventilation and air conditioning system 100 can switch between heating the heat exchanger 31 and stopping the heating of the heat exchanger 31 depending on the state of freezing in the heat exchanger 31.

[0072] Fig. 4 is a flowchart showing the procedure of the operation of the ventilating air-conditioning system 100 according to Embodiment 1. A program for realizing the procedure shown in Fig. 4 is stored in the control device 5.

[0073] In step S1, the ventilation air-conditioning system 100 starts operation of the ventilation device 3. The control device 5 starts operation of the ventilation device 3 by sending a control signal to the ventilation device 3. The outdoor unit 12 does not need to be in a powered state at the time of step S1.

[0074] In step S2, the control device 5 determines whether or not icing has been detected in the heat exchanger 31. If the outdoor air temperature detector 52 is not used to detect icing, the outdoor unit 12 does not need to be in a powered state at the time of step S1. If the outdoor air temperature detector 52 is used to detect icing, the outdoor unit 12 is in a powered state at the time of step S2. The outdoor air temperature detector 52 detects the outdoor air temperature when the outdoor unit 12 is in a powered state.

[0075] If no freezing is detected in the heat exchanger 31 (step S2, No), in step S3, the control device 5 resets the value of the elapsed time. The control device 5 resets the value of the elapsed time by setting the value of the counter that counts the elapsed time to zero. After completing step S3, the control device 5 sends a control signal to the flow path switching valve 23 to instruct the flow path switching valve 23 to open the first flow path 25 and close the second flow path 26. The ventilation and air conditioning system 100 proceeds to the procedure of step S4.

[0076] If freezing in the heat exchanger 31 is detected (step S2, Yes), the control device 5 counts the time that has elapsed since freezing began to be detected. In step S6, the control device 5 determines whether the time that has elapsed since freezing began to be detected has exceeded a first time. If the elapsed time has not exceeded the first time (step S6, No), the control device 5 instructs the flow path switching valve 23 to open the first flow path 25 and close the second flow path 26. The ventilation and air-conditioning system 100 proceeds to step S4.

[0077] In step S4, the flow path switching valve 23 opens the first flow path 25 and closes the second flow path 26 in accordance with an instruction from the control device 5. In this way, when freezing in the heat exchanger 31 is not detected, or when freezing in the heat exchanger 31 is detected and the elapsed time does not exceed the first time, the refrigerant circulation circuit unit 20 enters the first state in which the transport of the refrigerant to the second condenser 22 is stopped.

[0078] Following step S4, the control device 5 instructs the directional control valve 24 to pass the refrigerant between the connection port 24a and the connection port 24b and between the connection port 24c and the connection port 24d. In accordance with the instruction from the control device 5, the directional control valve 24 passes the refrigerant between the connection port 24a and the connection port 24b and passes the refrigerant between the connection port 24c and the connection port 24d. As a result, in step S5, the directional control valve 24 changes the flow direction of the refrigerant in the refrigerant circulation circuit section 20 to a direction in which the refrigerant that has flowed from the outdoor unit 12 to the first condenser 21 returns to the outdoor unit 12 through the connection point 27. When the outdoor unit 12 is operated, the refrigerant flows through the refrigerant circulation circuit section 20 and is transported to the second condenser 22 as shown in FIG.

[0079] If the time that has elapsed since the freezing started to be detected exceeds the first time (Yes in step S6), the control device 5 instructs the flow path switching valve 23 to close the first flow path 25 and open the second flow path 26. In step S7, the flow path switching valve 23 follows the instruction from the control device 5 to close the first flow path 25 and open the second flow path 26.

[0080] Following step S7, in step S8, the control device 5 judges whether the elapsed time from when freezing started to be detected has exceeded the second time. If the elapsed time has not exceeded the second time (step S8, No), the control device 5 instructs the directional control valve 24 to pass the refrigerant between the connection port 24a and the connection port 24b and between the connection port 24c and the connection port 24d. In accordance with the instruction from the control device 5, the directional control valve 24 passes the refrigerant between the connection port 24a and the connection port 24b and passes the refrigerant between the connection port 24c and the connection port 24d. As a result, in step S9, the directional control valve 24 changes the flow direction of the refrigerant in the refrigerant circulation circuit section 20 so that the refrigerant that has flowed from the outdoor unit 12 to the first condenser 21 passes through the second condenser 22 and returns to the outdoor unit 12. When the outdoor unit 12 is in operation, the refrigerant flows through the refrigerant circulation circuit section 20 and is transported to the first condenser 21 and the second condenser 22 as shown in FIG.

[0081] If the elapsed time exceeds the second time (step S8, Yes), the control device 5 instructs the directional control valve 24 to pass the refrigerant between the connection port 24a and the connection port 24c and between the connection port 24b and the connection port 24d. The directional control valve 24, in accordance with the instruction from the control device 5, passes the refrigerant between the connection port 24a and the connection port 24c and passes the refrigerant between the connection port 24b and the connection port 24d. As a result, in step S10, the directional control valve 24 changes the flow direction of the refrigerant in the refrigerant circulation circuit section 20 to a direction in which the refrigerant that has flowed from the outdoor unit 12 to the second condenser 22 passes through the first condenser 21 and returns to the outdoor unit 12. When the outdoor unit 12 is operated, the refrigerant flows through the refrigerant circulation circuit section 20 and is transported to the second condenser 22 and the first condenser 21 as shown in FIG.

[0082] With the above, the ventilating and air-conditioning system 100 ends the operation according to the procedure shown in Fig. 4. While the ventilation device 3 continues to operate, the ventilating and air-conditioning system 100 repeats the operations from step S2 to step S5, step S9, or step S10.

[0083] When the time elapsed since the freezing started to be detected is less than the first time, the freezing in the heat exchanger 31 is deemed to be of a degree that does not pose a problem in terms of ensuring the ventilation air volume. When freezing is not detected or when the time elapsed is less than the first time, the flow path switching valve 23 puts the refrigerant circulation circuit section 20 into the first state in which the transfer of the refrigerant to the second condenser 22 is stopped. When freezing is not detected or when the time elapsed is less than the first time, the ventilation air conditioning system 100 can prevent a decrease in the ventilation air volume due to freezing in the heat exchanger 31 even if the transfer of the refrigerant to the second condenser 22 is stopped. In addition, the ventilation air conditioning system 100 can reduce the energy consumption of the outdoor unit 12 by stopping the transfer of the refrigerant to the second condenser 22.

[0084] When the time that has elapsed since freezing began to be detected exceeds a first time, it becomes difficult to ensure the ventilation air volume due to freezing in the heat exchanger 31 unless heating is performed by the second condenser 22. When the time that has elapsed exceeds the first time, the flow path switching valve 23 puts the refrigerant circulation circuit section 20 into a second state in which the refrigerant is transported to the second condenser 22. When the time that has elapsed exceeds the first time, the ventilation air conditioning system 100 can prevent a decrease in the ventilation air volume due to freezing in the heat exchanger 31 by transporting the refrigerant to the second condenser 22.

[0085] When the time that has elapsed since freezing began to be detected is less than the second time, the directional control valve 24 changes the flow direction of the refrigerant in the refrigerant circulation circuit section 20 so that the refrigerant that has flowed from the outdoor unit 12 to the first condenser 21 passes through the second condenser 22 and returns to the outdoor unit 12. In this case, the refrigerant that leaves the outdoor unit 12 is transported to the first condenser 21 before the second condenser 22. By transporting the refrigerant that has undergone heat dissipation in the first condenser 21 to the second condenser 22, the ventilation and air-conditioning system 100 can efficiently use the thermal energy generated in the outdoor unit 12 to heat the air passing through the outdoor air duct 32.

[0086] When the time elapsed since the freezing started to be detected exceeds the second time, the directional control valve 24 changes the flow direction of the refrigerant in the refrigerant circulation circuit section 20 so that the refrigerant that has flowed from the outdoor unit 12 to the second condenser 22 passes through the first condenser 21 and returns to the outdoor unit 12. In this case, the refrigerant that has left the outdoor unit 12 is transported to the second condenser 22 before the first condenser 21. The ventilation and air-conditioning system 100 can secure a large amount of thermal energy to be transferred to the heat exchanger 31 regardless of the heating load in the room. This allows the ventilation and air-conditioning system 100 to reduce freezing in the heat exchanger 31 when the outside air temperature drops significantly. The ventilation and air-conditioning system 100 can prevent a decrease in the ventilation air volume due to freezing in the heat exchanger 31 by reducing freezing in the heat exchanger 31.

[0087] According to the first embodiment, the ventilation air-conditioning system 100 includes the second condenser 22 that heats the heat exchanger 31 with a refrigerant, and a refrigerant circulation circuit unit 20 that configures a flow path of the refrigerant that is transported from the outdoor unit 12 to each of the first condenser 21 and the second condenser 22 and returned to the outdoor unit 12. The ventilation air-conditioning system 100 can prevent a decrease in ventilation air volume due to freezing in the heat exchanger 31 by heating the heat exchanger 31 with the second condenser 22. The ventilation air-conditioning system 100 can ensure the supply air volume in the room because it continues to supply air by the ventilation device 3 regardless of the outdoor temperature condition. The ventilation air-conditioning system 100 can reduce the heating load compared to when the third type ventilation is performed because it continues to supply air accompanied by heat exchange by the ventilation device 3.

[0088] In the first embodiment, the ventilation air-conditioning system 100 is configured to include one first condenser 21 and one second condenser 22. Also, in the first embodiment, the ventilation air-conditioning system 100 is configured to include one ventilation device 3. The ventilation air-conditioning system 100 may be configured to include one first condenser 21 and a plurality of second condensers 22, a plurality of first condensers 21 and one second condenser 22, or a plurality of first condensers 21 and a plurality of second condensers 22. Alternatively, the ventilation air-conditioning system 100 may be configured to include a plurality of ventilation devices 3.

[0089] When the outside temperature drops significantly, the ventilation air-conditioning system 100 can effectively prevent a decrease in ventilation air volume due to freezing in the heat exchanger 31. The ventilation air-conditioning system 100 is applied, for example, to indoor ventilation and indoor air conditioning in cold regions.

[0090] Next, a hardware configuration for realizing the control device 5 according to the first embodiment will be described. The control device 5 is realized by a processing circuit. The processing circuit may be a circuit in which a processor executes software, or may be a dedicated circuit.

[0091] When the processing circuit is realized by software, the processing circuit is, for example, a control circuit 60 shown in Fig. 5. Fig. 5 is a diagram showing an example of the configuration of the control circuit 60 according to the first embodiment. The control circuit 60 includes an input unit 61, a processor 62, a memory 63, and an output unit 64. The input unit 61 is an interface circuit that receives data input from outside the control circuit 60 and provides the data to the processor 62. The output unit 64 is an interface circuit that transmits data from the processor 62 or the memory 63 to outside the control circuit 60.

[0092] The processor 62 is a CPU (Central Processing Unit). The processor 62 may be a central processing unit, a processing unit, an arithmetic unit, a microprocessor, a microcomputer, a processor, or a DSP (Digital Signal Processor). The memory 63 may be, for example, a random access memory (RAM), a read only memory (ROM), a flash memory, an erasable programmable read only memory (EPROM), an electrically erasable programmable read only memory (EEPROM (registered trademark)), or other non-volatile or volatile semiconductor memory, a magnetic disk, a flexible disk, an optical disk, a compact disk, a mini disk, or a digital versatile disk (DVD).

[0093] Fig. 5 shows an example of hardware in which the functions of the control device 5 are realized by a general-purpose processor 62 and a memory 63, but the functions of the control device 5 may be realized by a dedicated hardware circuit. Fig. 6 is a diagram showing an example of the configuration of a dedicated hardware circuit 65 according to the first embodiment.

[0094] The dedicated hardware circuit 65 includes an input unit 61, an output unit 64, and a processing circuit 66. The processing circuit 66 is a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a circuit that combines these. The control device 5 may be realized by the processing circuit 66 for each function, or the functions of the control device 5 may be realized collectively by the processing circuit 66. The control device 5 may be realized by combining the control circuit 60 and the hardware circuit 65.

[0095] The configurations shown in the above embodiments are examples of the contents of the present disclosure. The configurations of the embodiments can be combined with other known technologies. Part of the configurations of the embodiments can be omitted or modified without departing from the gist of the present disclosure. [Explanation of symbols]

[0096] 1 air conditioner, 3 ventilation device, 4 building, 5 control device, 11 indoor unit, 12 outdoor unit, 20 refrigerant circulation circuit section, 21 first condenser, 21a, 21b, 22a, 22b, 23a, 23b, 23c, 24a, 24b, 24c, 24d, 124a, 124b connection port, 22 second condenser, 23 flow path switching valve, 24 directional control valve, 25 first flow path, 26 second flow path, 27 connection point, 30 housing, 31 heat exchanger, 32 outdoor air duct, 33 exhaust air duct, 34 supply air duct, 35, 47 return air duct, 36 supply air blower, 37 exhaust air blower, 39 wind speed sensor, 41 outdoor intake port, 42 outdoor air outlet, 43 indoor air outlet, 44 Outdoor air duct, 45 exhaust duct, 46 supply air duct, 48 living room, 51, 52 outdoor air temperature detector, 53 supply air temperature detector, 60 control circuit, 61 input section, 62 processor, 63 memory, 64 output section, 65 hardware circuit, 66 processing circuit, 100 ventilation and air conditioning system, 111 blower, 121 expansion valve, 122 evaporator, 123 compressor, 124 refrigerant circuit section.

Claims

1. an air conditioner having an outdoor unit that heats a refrigerant and an indoor unit including a first condenser that heats air to be sent into a room with the refrigerant; a ventilation device having a heat exchanger for performing heat exchange between air supplied from the outside of the room to the room and air exhausted from the room to the outside, the ventilation device supplying air into the room and exhausting air from the room; a second condenser for heating the heat exchanger with the refrigerant; a refrigerant circulation circuit portion that configures a flow path of the refrigerant that is transported from the outdoor unit to each of the first condenser and the second condenser and returned to the outdoor unit. A ventilation and air conditioning system characterized by the above.

2. A freezing detection unit that detects freezing in the heat exchanger; a switching unit that switches the refrigerant circulation circuit unit between a first state in which the transfer of the refrigerant to the second condenser is stopped and a second state in which the refrigerant is transferred to the second condenser based on a detection result by the freezing detection unit.

2. The ventilation air-conditioning system according to claim 1 .

3. When freezing in the heat exchanger is not detected, or when an elapsed time from when freezing in the heat exchanger is first detected is shorter than a first time set in advance, the switching unit sets the refrigerant circulation circuit unit to the first state, When the elapsed time exceeds the first time, the switching unit switches the refrigerant circulation circuit unit to the second state.

3. The ventilation air-conditioning system according to claim 2.

4. The refrigerant circulation circuit section includes: a first flow path through which the refrigerant flowing out of the first condenser returns to the outdoor unit in the first state; a second flow path that transports the refrigerant to the second condenser in the second state, The switching unit is a first valve that switches a flow path of the refrigerant between the first flow path and the second flow path, when ice is not detected in the heat exchanger or when the elapsed time is less than the first time, the first valve opens the first flow path and closes the second flow path; When the elapsed time exceeds the first time, the first valve closes the first flow path and opens the second flow path.

4. The ventilation air-conditioning system according to claim 3.

5. a second valve that switches a flow direction of the refrigerant in the refrigerant circulation circuit portion, When the elapsed time is less than a second time longer than the first time, the second valve changes the flow direction of the refrigerant so that the refrigerant that has flowed from the outdoor unit to the first condenser passes through the second condenser and returns to the outdoor unit, When the elapsed time exceeds the second time, the second valve changes the flow direction of the refrigerant so that the refrigerant that has flowed from the outdoor unit to the second condenser passes through the first condenser and returns to the outdoor unit.

5. The ventilation air-conditioning system according to claim 4.

6. a wind speed sensor that detects the wind speed of air discharged from the room to the outside in the ventilation device; The freezing detection unit detects freezing in the heat exchanger based on a detection result by the air velocity sensor.

6. The ventilation air-conditioning system according to claim 2, wherein the ventilation air-conditioning system comprises:

7. The ventilation device includes an exhaust fan that sends air taken in from inside the room to the outside of the room, The icing detection unit detects icing in the heat exchanger based on a load of the exhaust fan.

6. The ventilation air-conditioning system according to claim 2, wherein the ventilation air-conditioning system comprises:

8. The frost detection unit detects frost in the heat exchanger by detecting a temperature difference between the air outside the room and the air sent into the room from the ventilation device.

6. The ventilation air-conditioning system according to claim 2, wherein the ventilation air-conditioning system comprises:

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