초록
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An air-conditioning apparatus that can prevent freezing of a heat transfer medium even when using a non-azeotropic refrigerant mixture. The air-conditioning apparatus is designed such that when a heat exchanger serves as a cooler that cools a heat transfer medium, it controls a heat medium passage reversing device. This is so that, when a heat transfer medium flowing through a heat medium flow passage will not be frozen, a refrigerant flowing through a refrigerant flow passage and the heat transfer medium flowing through the heat medium flow passage are ...
An air-conditioning apparatus that can prevent freezing of a heat transfer medium even when using a non-azeotropic refrigerant mixture. The air-conditioning apparatus is designed such that when a heat exchanger serves as a cooler that cools a heat transfer medium, it controls a heat medium passage reversing device. This is so that, when a heat transfer medium flowing through a heat medium flow passage will not be frozen, a refrigerant flowing through a refrigerant flow passage and the heat transfer medium flowing through the heat medium flow passage are in counter flow. It is also to control the heat medium passage reversing device so that, when there is a possibility of freezing the heat transfer medium flowing through the heat medium flow passage, the refrigerant flowing through the refrigerant flow passage and the heat transfer medium flowing through the heat medium flow passage are in parallel flow.
대표
청구항
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1. An air-conditioning apparatus comprising: a refrigerant circuit in which a compressor, a refrigerant passage switching device that switches a passage of a refrigerant discharged from the compressor, a first heat exchanger, a first expansion device, and a refrigerant flow passage of a second heat exchanger are connected via a refrigerant pipe through which the refrigerant is distributed;a heat transfer medium circuit in which a heat transfer medium flow passage of the second heat exchanger and a heat transfer medium sending device are connected via a h...
1. An air-conditioning apparatus comprising: a refrigerant circuit in which a compressor, a refrigerant passage switching device that switches a passage of a refrigerant discharged from the compressor, a first heat exchanger, a first expansion device, and a refrigerant flow passage of a second heat exchanger are connected via a refrigerant pipe through which the refrigerant is distributed;a heat transfer medium circuit in which a heat transfer medium flow passage of the second heat exchanger and a heat transfer medium sending device are connected via a heat transfer medium pipe through which a heat transfer medium is distributed, and to which a use side heat exchanger is connected;a heat transfer medium passage reversing device that is disposed in the heat transfer medium circuit and that is configured to switch a direction of the heat transfer medium flowing through the heat transfer medium flow passage of the second heat exchanger between a normal direction and a reverse direction;a controller configured to control the heat transfer medium passage reversing device to switch the direction of the heat transfer medium flowing through the heat transfer medium flow passage of the second heat exchanger; anda freezing determination processor configured to determine whether or not there is a possibility of freezing of the heat transfer medium flowing through the heat transfer medium flow passage of the second heat exchanger,wherein the refrigerant flowing through the refrigerant circuit is a non-azeotropic refrigerant mixture including a plurality of components and having a temperature glide between a saturated gas temperature and a saturated liquid temperature at the same pressure, andwherein in a condition where the second heat exchanger serves as a cooler that cools the heat transfer medium, the controller is configured to control the heat transfer medium passage reversing device so that, when the freezing determination processor determines that the heat transfer medium flowing through the heat transfer medium flow passage of the second heat exchanger will not be frozen, the refrigerant flowing through the refrigerant flow passage of the second heat exchanger and the heat transfer medium flowing through the heat transfer medium flow passage of the second heat exchanger are in counter flow, andcontrol the heat transfer medium passage reversing device so that, when the freezing determination processor determines that there is a possibility of freezing of the heat transfer medium flowing through the heat transfer medium flow passage of the second heat exchanger, the refrigerant flowing through the refrigerant flow passage of the second heat exchanger and the heat transfer medium flowing through the heat transfer medium flow passage of the second heat exchanger are in parallel flow. 2. The air-conditioning apparatus of claim 1, further comprising: at least one of a first temperature sensor disposed on one of an inlet side and an outlet side of the refrigerant flow passage of the second heat exchanger, a second temperature sensor disposed on the other of the inlet side and the outlet side of the refrigerant flow passage of the second heat exchanger, a third temperature sensor disposed on an inlet side of the heat transfer medium flow passage of the second heat exchanger or on an outlet side of the use side heat exchanger, a fourth temperature sensor disposed on an outlet side of the heat transfer medium flow passage of the second heat exchanger or on an inlet side of the use side heat exchanger, and a fifth temperature sensor configured to detect an ambient air temperature of the first heat exchanger,wherein the freezing determination processor is configured to determine that there is the possibility of freezing of the heat transfer medium flowing through the heat transfer medium flow passage of the second heat exchanger when at least one condition is established among: a case where a detection value of at least one of the first temperature sensor and the second temperature sensor is less than or equal to a first set temperature, a case where a detection value of at least one of the third temperature sensor and the fourth temperature sensor is less than or equal to a second set temperature, and a case where a detection value of the fifth temperature sensor is less than or equal to a third set temperature. 3. The air-conditioning apparatus of claim 2, wherein in a condition where the second heat exchanger serves as a cooler that cools the heat transfer medium, the controller is configured to set the first set temperature on the basis of the composition of the refrigerant or a temperature glide between a saturated gas temperature and a saturated liquid temperature at the same pressure of the refrigerant, which is calculated based on the composition. 4. The air-conditioning apparatus of claim 3, further comprising: a refrigerant circulation composition sensor configured to detect a composition of the refrigerant that circulates the refrigerant circuit,wherein the refrigerant circulation composition sensor at least includes a low-pressure side pressure sensor configured to detect a low-pressure side pressure of the compressor,a high-low pressure bypass pipe that connects a discharge-side passage of the compressor and a suction-side passage of the compressor,a second expansion device disposed in the high-low pressure bypass pipe,a high-pressure side temperature sensor disposed in the high-low pressure bypass pipe on an inlet side of the second expansion device,a low-pressure side temperature sensor disposed in the high-low pressure bypass pipe on an outlet side of the second expansion device, anda refrigerant-refrigerant heat exchanger configured to cause heat exchange between refrigerants flowing through pipes located before and after the second expansion device, andwherein the controller is configured tocalculate a composition of the refrigerant or the temperature glide of the refrigerant using at least the pressure detected by the low-pressure side pressure sensor, a temperature detected by the high-pressure side temperature sensor, and a temperature detected by the low-pressure side temperature sensor. 5. The air-conditioning apparatus of claim 1, wherein in a condition where the second heat exchanger serves as a heater that heats the heat transfer medium, the controller is configured to control the heat transfer medium passage reversing device so that the refrigerant flowing through the refrigerant flow passage of the second heat exchanger and the heat transfer medium flowing through the heat transfer medium flow passage of the second heat exchanger are in counter flow. 6. The air-conditioning apparatus of claim 1, further comprising: a third temperature sensor disposed on the inlet side of the heat transfer medium flow passage of the second heat exchanger or on an outlet side of the use side heat exchanger; anda fourth temperature sensor disposed on the outlet side of the heat transfer medium flow passage of the second heat exchanger or on the inlet side of the use side heat exchanger,wherein the controller is configured toset a first target value on the basis of the composition of the refrigerant or the temperature glide between the saturated gas temperature and the saturated liquid temperature at the same pressure of the refrigerant, which is calculated based on the composition, the first target value being a control target value of a temperature difference between the third temperature sensor and the fourth sensor. 7. The air-conditioning apparatus of claim 6, wherein the controller includes a first controller and a second controller,wherein the compressor, the refrigerant passage switching device, the first heat exchanger, and the first controller are included in an outdoor unit,wherein the first expansion device, the second heat exchanger, the heat transfer medium sending device, and the second controller are included in a heat transfer medium relay unit,wherein the first controller and the second controller are connected via wire or wirelessly so as to be capable of communicating with each other,wherein the first controller is configured to transmit the composition of the refrigerant or the temperature glide between the saturated gas temperature and the saturated liquid temperature at the same pressure of the refrigerant, which is calculated based on the composition, to the second controller, andwherein the second controller is configured to set the control target value on the basis of the composition of the refrigerant or the temperature glide, which has been transmitted. 8. The air-conditioning apparatus of claim 7, further comprising: a refrigerant circulation composition sensor configured to detect a composition of the refrigerant that circulates in the refrigerant circuit,wherein the refrigerant circulation composition sensor at least includes a low-pressure side pressure sensor configured to detect a low-pressure side pressure of the compressor,a high-low pressure bypass pipe connected between (1) a passage between a discharge side of the compressor and the refrigerant passage switching device, and (2) a passage between a suction side of the compressor and the refrigerant passage switching device,a second expansion device disposed in the high-low pressure bypass pipe,a high-pressure side temperature sensor disposed in the high-low pressure bypass pipe on an inlet side of the second expansion device,a low-pressure side temperature sensor disposed in the high-low pressure bypass pipe on an outlet side of the second expansion device, anda refrigerant-refrigerant heat exchanger configured to cause heat exchange between refrigerants flowing through pipes located before and after the second expansion device, andwherein the first controller is configured to calculate a composition of the refrigerant or the temperature glide of the refrigerant using at least the pressure detected by the low-pressure side pressure sensor, a temperature detected by the high-pressure side temperature sensor, and a temperature detected by the low-pressure side temperature sensor, andtransmit the circulation composition of the refrigerant or the temperature glide of the refrigerant to the second controller. 9. The air-conditioning apparatus of claim 7, wherein the heat transfer medium passage reversing device is included in the heat transfer medium relay unit. 10. The air-conditioning apparatus of claim 6, wherein in a condition where the second heat exchanger serves as a cooler that cools the heat transfer medium and the refrigerant flowing through the refrigerant flow passage of the second heat exchanger and the heat transfer medium flowing through the heat transfer medium flow passage of the second heat exchanger are in parallel flow, if a detection value of the third temperature sensor or a detection value of the fourth sensor is less than or equal to a fourth set temperature,the controllersets the control target value of the temperature difference between the third temperature sensor and the fourth temperature sensor to a second target value lower than the first target value, instead of the first target value. 11. The air-conditioning apparatus of claim 6, wherein the control target value for the second heat exchanger or the use side heat exchanger when the second heat exchanger serves as a heater that heats the heat transfer medium is larger than the control target value for the second heat exchanger or the use side heat exchanger when the second heat exchanger serves as a cooler that cools the heat transfer medium. 12. The air-conditioning apparatus of claim 1, wherein the air-conditioning apparatus comprises a plurality of second heat exchangers, each being the second heat exchanger, and a plurality of heat transfer medium sending devices, each being the heat transfer medium sending device,wherein the air-conditioning apparatus further comprises first heat transfer medium passage switching devices each connected to a passage on an outlet side of one of the plurality of second heat exchangers, each of the first heat transfer medium passage switching devices configured to select one of the second heat exchangers which communicates with a passage on the inlet side of the use side heat exchanger, andwherein the air-conditioning apparatus further comprises second heat transfer medium passage switching devices each connected to the passage on the inlet side of one of the plurality of second heat exchangers, each of the second heat transfer medium passage switching devices configured to select one of the second heat exchangers which communicates with the passage on the outlet side of the use side heat exchanger. 13. The air-conditioning apparatus of claim 12, further comprising second heat transfer medium passage switching devices each connected to the passage on the inlet side of one of the plurality of second heat exchangers, each of the second heat transfer medium passage switching devices configured to select one of the second heat exchangers which communicates with the passage on the outlet side of the use side heat exchanger. 14. The air-conditioning apparatus of claim 1, wherein the heat transfer medium passage reversing device is a three-way valve or a plurality of two-way valves disposed at each of one end and the other end of the heat transfer medium passage of the second heat exchanger. 15. The air-conditioning apparatus of claim 14, wherein the heat transfer medium passage reversing device includes a first heat transfer medium passage reversing device disposed at the one end of the heat transfer medium passage of the second heat exchanger and connected to the other end of the heat transfer medium passage of the second heat exchanger by pipes at a first connection port, anda second heat transfer medium passage reversing device disposed at the other end of the heat transfer medium passage of the second heat exchanger and connected to the one end of the heat transfer medium passage of the second heat exchanger by pipes at a second connection port,wherein the first connection port is disposed in a passage between the other end of the heat transfer medium passage of the second heat exchanger and the second heat transfer medium passage reversing device, andwherein the second connection port is disposed in a passage between the one end of the heat transfer medium passage of the second heat exchanger and the first heat transfer medium passage reversing device. 16. The air-conditioning apparatus of claim 1, wherein the refrigerant is a refrigerant mixture containing at least tetrafluoropropene and R32. 17. The air-conditioning apparatus of claim 16, wherein the refrigerant is a refrigerant mixture containing at least HFO1234yf and R32, and R32 is mixed at a proportion ranging from 3 mass % to 45 mass %.
