Air source heat pump system and defrosting control method thereof

Abstract

The invention belongs to the related technical field of heat pump systems, and discloses an air source heat pump system and a defrosting control method thereof.The system comprises a circulation loop formed by a compressor, a four-way valve, an indoor heat exchanger, an electronic expansion valve and an outdoor heat exchanger, and further comprises a first bypass, a second bypass, a bypass valve and an electromagnetic valve. The first end of the first bypass is connected between the four-way valve and the indoor heat exchanger, the second end of the first bypass is connected between the electronic expansion valve and the outdoor heat exchanger, the first end of the second bypass is connected between the indoor heat exchanger and the electronic expansion valve, and the second end of the second bypass is connected between the outdoor heat exchanger and the four-way valve. A first bypass valve and a second bypass valve are arranged on the first bypass and the second bypass respectively, and the electromagnetic valve is arranged between the first end of the first bypass and the indoor heat exchanger. In the defrosting mode, the first bypass valve and the second bypass valve are opened, the electromagnetic valve and the electronic expansion valve are closed, the four-way valve is not reversed, heat is not taken from a room during defrosting, a refrigerant of the compressor is effectively supplemented, and the defrosting speed is increased.

Description

Technical Field

[0001] The present invention belongs to the technical field related to heat pump systems, and more specifically, relates to an air source heat pump system and a defrosting control method thereof. Background Art

[0002] When the surface temperature of the outdoor heat exchanger of the air source heat pump is lower than the dew point of the humid air and lower than 0°C, frost will form, causing the performance of the air source heat pump system to decline. This is because the frost layer will increase the thermal resistance on the outdoor heat exchanger on the one hand, and increase the air flow resistance in the heat exchanger on the other hand, reducing the air volume and causing the heat exchange to weaken.

[0003] In the prior art, the solutions for defrosting the outdoor heat exchanger are reverse cycle defrosting and hot gas bypass defrosting. Reverse cycle defrosting requires absorbing heat from the room, which greatly affects the indoor comfort. Hot gas bypass defrosting is to bypass part or all of the exhaust gas of the compressor to the outdoor heat exchanger for defrosting. When part of the exhaust gas of the compressor is bypassed to the outdoor heat exchanger for defrosting during the defrosting process, part of the refrigerant will flow into the indoor heat exchanger for indoor heating, reducing the heat supply for defrosting and the defrosting effect will be worse; when all the exhaust gas of all compressors is bypassed to the outdoor heat exchanger for defrosting during the defrosting process, but the refrigerant stored in the indoor heat exchanger and the liquid storage tank (if any) is not used to supplement the refrigerant circulating in the system during the defrosting process, the refrigerant circulating in the system during the defrosting process will be reduced, and the defrosting effect will be poor. In addition, as the defrosting process proceeds, the refrigerant flow rate will become smaller and smaller, resulting in a decrease in the compressor power, making the defrosting speed slower and the defrosting effect unsatisfactory. Summary of the invention

[0004] In view of the above defects or improvement needs of the prior art, the present invention provides an air source heat pump system and a defrost control method thereof, which are used to solve the problems that the existing solutions for defrosting the outdoor heat exchanger have slow defrosting speed and unsatisfactory defrosting effect.

[0005] To achieve the above-mentioned purpose, according to one aspect of the present invention, an air source heat pump system is provided, comprising a heat pump circulation loop formed by connecting a compressor, a four-way valve, an indoor heat exchanger, an electronic expansion valve and an outdoor heat exchanger, and also comprising a first bypass, a second bypass, a bypass valve and a solenoid valve, wherein a first end of the first bypass is connected to a pipeline between the four-way valve and the indoor heat exchanger, and a second end is connected to a pipeline between the electronic expansion valve and the outdoor heat exchanger, a first end of the second bypass is connected to a pipeline between the indoor heat exchanger and the electronic expansion valve, and a second end is connected to a pipeline between the outdoor heat exchanger and the four-way valve, a first bypass valve is provided on the first bypass, a second bypass valve is provided on the second bypass, and the solenoid valve is provided between the first end of the first bypass and the indoor heat exchanger; during defrosting, the first bypass valve and the second bypass valve on the first bypass and the second bypass are opened, the solenoid valve and the electronic expansion valve are closed, and the four-way valve does not reverse.

[0006] According to the air source heat pump system provided by the present invention, the first interface of the four-way valve is connected to the exhaust port of the compressor, the second interface of the four-way valve is connected to the first end of the indoor heat exchanger, the third interface of the four-way valve is connected to the intake port of the compressor, the second end of the indoor heat exchanger is connected to the electronic expansion valve, the electronic expansion valve is connected to the first end of the outdoor heat exchanger, and the second end of the outdoor heat exchanger is connected to the fourth interface of the four-way valve.

[0007] According to the air source heat pump system provided by the present invention, the air intake port of the compressor is also connected to a gas-liquid separator; a liquid storage tank is also provided between the indoor heat exchanger and the electronic expansion valve, and accordingly, the first end of the second bypass is connected to the pipeline between the liquid storage tank and the electronic expansion valve.

[0008] According to the air source heat pump system provided by the present invention, the indoor heat exchanger is further provided with an electric heating device and an indoor fan, and the outdoor heat exchanger is further provided with an outdoor fan.

[0009] According to the air source heat pump system provided by the present invention, the first bypass valve and the second bypass valve are solenoid valves.

[0010] According to another aspect of the present invention, a defrost control method for an air source heat pump system is provided. Based on any of the above air source heat pump systems, the defrost control method comprises:

[0011] When the air source heat pump system works in the defrosting mode, the first bypass valve and the second bypass valve on the first bypass and the second bypass are controlled to be opened, and the solenoid valve and the electronic expansion valve are controlled to be closed for defrosting. The four-way valve does not switch, the exhaust gas of the compressor does not pass through the indoor heat exchanger, and the exhaust gas of the compressor does not release heat into the room.

[0012] According to the defrost control method of the air source heat pump system provided by the present invention, the indoor heat exchanger is further provided with an indoor fan, the outdoor heat exchanger is further provided with an outdoor fan, and the defrost control method further comprises:

[0013] During defrosting, the indoor fan is controlled to reduce the wind speed and the outdoor fan is controlled to be turned off.

[0014] According to the defrost control method of the air source heat pump system provided by the present invention, the indoor heat exchanger is also provided with an electric heating device, and the defrost control method further comprises:

[0015] During defrosting, the electric heating device is turned on to maintain the indoor temperature.

[0016] The defrost control method of the air source heat pump system provided by the present invention further includes:

[0017] When defrosting is finished, the solenoid valve and the electronic expansion valve are controlled to open, and the first bypass valve and the second bypass valve on the first bypass and the second bypass are controlled to close, and the air source heat pump system resumes the heating mode.

[0018] In general, compared with the prior art, the above technical solutions conceived by the present invention provide an air source heat pump system and a defrosting control method thereof:

[0019] 1. The air source heat pump system can achieve defrosting by setting a first bypass. During the defrosting period, the first bypass valve on the first bypass is opened, and the solenoid valve and the electronic expansion valve are closed. During defrosting, the four-way valve does not reverse, the exhaust gas of the compressor does not pass through the indoor heat exchanger, and the exhaust gas of the compressor does not release heat to the indoor room. The system has small pressure fluctuations, which can reduce the time for the system to reach pressure balance again, improve efficiency, and will not generate noise caused by the reversal of the four-way valve. Moreover, no heat is taken from the room during defrosting, which is conducive to maintaining indoor comfort. At the same time, the system is set with a second bypass. During the defrosting period, the second bypass valve of the second bypass is opened, so that the refrigerant of the compressor can be effectively supplemented. Compared with hot gas bypass defrosting, the refrigerant flow is increased, the compressor power is increased, the defrosting speed is faster, and the defrosting effect is better.

[0020] 2. During defrosting, the indoor heating is ensured by turning on the electric heating;

[0021] 3. The present invention only adds a small amount of pipelines and valves, has a simple structure, low modification cost, and little impact on the unit volume. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the overall structure of the air source heat pump system provided by the present invention;

[0023] Figure 2It is a schematic diagram of the refrigerant flow direction in the heating mode of the air source heat pump system provided by the present invention;

[0024] Figure 3 It is a schematic diagram of the refrigerant flow in the defrost mode of the air source heat pump system provided by the present invention. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0026] See also Figure 1 The present invention provides an air source heat pump system, which includes a heat pump circulation loop formed by connecting a compressor, a four-way valve, an indoor heat exchanger, an electronic expansion valve and an outdoor heat exchanger. The heat pump circulation loop can be switched between a cooling mode and a heating mode by reversing the four-way valve.

[0027] The air source heat pump system further comprises a first bypass, a second bypass and a solenoid valve, wherein the first end of the first bypass is connected to the pipeline between the four-way valve and the indoor heat exchanger, and the second end is connected to the pipeline between the electronic expansion valve and the outdoor heat exchanger, the first end of the second bypass is connected to the pipeline between the indoor heat exchanger and the electronic expansion valve, and the second end is connected to the pipeline between the outdoor heat exchanger and the four-way valve, the first bypass and the second bypass are respectively provided with a bypass valve, the solenoid valve is provided between the first end of the first bypass and the indoor heat exchanger, the first bypass valve and the second bypass valve are opened during defrosting, and the solenoid valve and the electronic expansion valve are closed during defrosting. The four-way valve does not reverse, the exhaust gas of the compressor does not pass through the indoor heat exchanger, and the exhaust gas of the compressor does not release heat to the indoor room.

[0028] In this embodiment, a first bypass is provided. During defrosting, a first bypass valve on the first bypass is opened, and the solenoid valve and the electronic expansion valve are closed. This allows all high-temperature refrigerant discharged from the compressor exhaust port to flow into the outdoor heat exchanger through the first bypass, thereby achieving defrosting of the outdoor heat exchanger, which is beneficial to increasing the defrosting speed. At the same time, the high-temperature refrigerant stored in the indoor heat exchanger can help maintain the indoor temperature and maintain indoor comfort.

[0029] Furthermore, this embodiment takes into account that in the existing hot gas bypass defrosting, when part of the exhaust gas of the compressor is bypassed to the outdoor heat exchanger for defrosting during the defrosting process, part of the refrigerant will flow into the indoor heat exchanger for indoor heating, reducing the heat supply for defrosting and causing poor defrosting effect; when all the exhaust gas of the compressor is bypassed to the outdoor heat exchanger for defrosting during the defrosting process, but the refrigerant stored in the indoor heat exchanger and the liquid storage tank (if any) is not used to supplement the refrigerant circulating in the system during the defrosting process, the refrigerant circulating in the system during the defrosting process will be reduced, resulting in poor defrosting effect. Moreover, as the defrosting process proceeds, the refrigerant flow rate used for outdoor defrosting will become smaller and smaller due to condensation in the outdoor heat exchanger, resulting in very limited defrosting effect in the middle and late stages of defrosting and a slow defrosting speed. Based on this, this embodiment further proposes to set up a second bypass on the basis of closing the solenoid valve and the electronic expansion valve, and open the second bypass valve on the second bypass during defrosting, so that the high-temperature and high-pressure refrigerant flowing out of the indoor heat exchanger flows through the second bypass and mixes with the refrigerant flowing out of the outdoor heat exchanger, thereby replenishing the refrigerant in the circuit and increasing the compressor power, which is beneficial to speed up the defrosting speed and improve the defrosting efficiency.

[0030] Specifically, the first interface of the four-way valve is connected to the exhaust port of the compressor, the second interface of the four-way valve is connected to the first end of the indoor heat exchanger, the third interface of the four-way valve is connected to the intake port of the compressor, the second end of the indoor heat exchanger is connected to the electronic expansion valve, the electronic expansion valve is connected to the first end of the outdoor heat exchanger, and the second end of the outdoor heat exchanger is connected to the fourth interface of the four-way valve.

[0031] Furthermore, a gas-liquid separator is connected to the air intake of the compressor. A liquid storage tank is also provided between the indoor heat exchanger and the electronic expansion valve, that is, the defrosting system formed by the first bypass, the second bypass and the solenoid valve provided in this embodiment is applicable to both heat pump circulation loops without a liquid storage tank and heat pump circulation loops with a liquid storage tank. Correspondingly, when a liquid storage tank is provided, the first end of the second bypass is connected to the pipeline between the liquid storage tank and the electronic expansion valve.

[0032] Furthermore, the indoor heat exchanger is also provided with an electric heating device and an indoor fan, and the outdoor heat exchanger is also provided with an outdoor fan.

[0033] Specifically, the bypass valve is a solenoid valve.

[0034] This embodiment further provides a defrost control method for an air source heat pump system. The defrost control method is based on any of the above-mentioned air source heat pump systems. The defrost control method includes:

[0035] When the air source heat pump system works in the defrosting mode, the first bypass valve and the second bypass valve on the first bypass and the second bypass are controlled to be opened, and the solenoid valve and the electronic expansion valve are controlled to be closed for defrosting. The four-way valve is controlled not to be reversed, the exhaust gas of the compressor does not pass through the indoor heat exchanger, and the exhaust gas of the compressor does not release heat into the room.

[0036] Furthermore, the indoor heat exchanger is further provided with an indoor fan, the outdoor heat exchanger is further provided with an outdoor fan, and the defrost control method further comprises:

[0037] During defrosting, the indoor fan is controlled to reduce the wind speed appropriately, and the outdoor fan is controlled to be turned off. Reducing the wind speed of the indoor fan is conducive to maintaining the indoor temperature to ensure comfort, and turning off the outdoor fan is conducive to reducing the heat exchange between the refrigerant and the outdoor air, which is conducive to fully utilizing the temperature of the refrigerant for defrosting.

[0038] Furthermore, the indoor heat exchanger is also provided with an electric heating device, and the defrost control method further comprises:

[0039] During defrosting, the electric heating device is turned on to maintain the indoor temperature.

[0040] Furthermore, the defrost control method further includes:

[0041] When defrosting is finished, the solenoid valve and the electronic expansion valve are controlled to open, the first bypass valve on the first bypass and the second bypass valve on the second bypass are controlled to close, and the air source heat pump system resumes the heating mode.

[0042] like Figure 1 As shown, the system consists of a compressor, a four-way valve, an indoor heat exchanger, a liquid storage tank (set as needed), an electronic expansion valve, a solenoid valve, two bypass valves, an outdoor heat exchanger, a gas-liquid separator, and an electric heating device. Compared with the traditional refrigeration system, the system adds two bypasses with bypass valves. Both bypasses work in defrosting mode: one end of the first bypass is connected between the indoor heat exchanger and the four-way valve, and the other end is connected between the outdoor heat exchanger and the electronic expansion valve; one end of the second bypass is connected between the liquid storage tank (the indoor heat exchanger when there is no liquid storage tank) and the electronic expansion valve, and the other end is connected between the outdoor heat exchanger and the four-way valve. The system also adds a solenoid valve to the main circuit, which is located between the indoor heat exchanger of the main circuit and the first end of the first bypass to control the refrigerant not to pass through the indoor heat exchanger during defrosting. In addition, the system is also equipped with an electric heating device at the indoor heat exchanger for heating during defrosting.

[0043] like Figure 2As shown in the figure, in the heating mode, the solenoid valve and the electronic expansion valve are open, and the first bypass valve and the second bypass valve are closed. After being compressed by the compressor, the refrigerant flows into the indoor heat exchanger through the four-way valve to release heat for heating, and is throttled by the electronic expansion valve to reduce temperature and pressure, and then flows into the outdoor heat exchanger to absorb heat and condense, and finally flows back to the compressor through the four-way valve and the gas-liquid separator.

[0044] like Figure 3 As shown, in defrost mode, the first bypass valve and the second bypass valve are open, the solenoid valve and the electronic expansion valve are closed, the outdoor fan is closed, the wind speed of the indoor fan is reduced, and the four-way valve does not reverse. During defrosting, the refrigerant is compressed by the compressor and flows into the first bypass through the four-way valve, flows through the first bypass valve to the outdoor heat exchanger to release heat for defrosting, and then flows back to the compressor through the four-way valve and the gas-liquid separator. At the same time, the high-temperature and high-pressure refrigerant stored in the indoor heat exchanger and the liquid storage tank (if any) flows to the outdoor heat exchanger outlet through the second bypass valve on the second bypass, which effectively replenishes the refrigerant and speeds up the defrosting speed.

[0045] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An air source heat pump system, characterized in that: The invention comprises a heat pump circulation loop formed by connecting a compressor, a four-way valve, an indoor heat exchanger, an electronic expansion valve and an outdoor heat exchanger, and also comprises a first bypass, a second bypass, a bypass valve and a solenoid valve, wherein a first end of the first bypass is connected to a pipeline between the four-way valve and the indoor heat exchanger, and a second end is connected to a pipeline between the electronic expansion valve and the outdoor heat exchanger, a first end of the second bypass is connected to a pipeline between the indoor heat exchanger and the electronic expansion valve, and a second end is connected to a pipeline between the outdoor heat exchanger and the four-way valve, a first bypass valve is arranged on the first bypass, a second bypass valve is arranged on the second bypass, and the solenoid valve is arranged between the first end of the first bypass and the indoor heat exchanger; during defrosting, the first bypass valve and the second bypass valve on the first bypass and the second bypass are opened, the solenoid valve and the electronic expansion valve are closed, and the four-way valve does not reverse.

2. The air source heat pump system according to claim 1, characterized in that: The first interface of the four-way valve is connected to the exhaust port of the compressor, the second interface of the four-way valve is connected to the first end of the indoor heat exchanger, the third interface of the four-way valve is connected to the suction port of the compressor, the second end of the indoor heat exchanger is connected to the electronic expansion valve, the electronic expansion valve is connected to the first end of the outdoor heat exchanger, and the second end of the outdoor heat exchanger is connected to the fourth interface of the four-way valve.

3. The air source heat pump system according to claim 1, characterized in that: The air intake of the compressor is also connected to a gas-liquid separator; a liquid storage tank is also provided between the indoor heat exchanger and the electronic expansion valve, and accordingly, the first end of the second bypass is connected to the pipeline between the liquid storage tank and the electronic expansion valve.

4. The air source heat pump system according to any one of claims 1 to 3, characterized in that: The indoor heat exchanger is also provided with an electric heating device and an indoor fan, and the outdoor heat exchanger is also provided with an outdoor fan.

5. The air source heat pump system according to any one of claims 1 to 3, characterized in that: The first bypass valve and the second bypass valve are solenoid valves.

6. A defrosting control method for an air source heat pump system, characterized in that: Based on the air source heat pump system described in any one of claims 1 to 5 above, the defrost control method comprises: When the air source heat pump system operates in the defrost mode, the first bypass valve and the second bypass valve on the first bypass and the second bypass are controlled to be opened, and the solenoid valve and the electronic expansion valve are controlled to be closed for defrosting.

7. The defrosting control method of the air source heat pump system according to claim 6, characterized in that: The indoor heat exchanger is also provided with an indoor fan, and the outdoor heat exchanger is also provided with an outdoor fan. The defrost control method further includes: During defrosting, the indoor fan is controlled to reduce the wind speed and the outdoor fan is controlled to be turned off.

8. The defrosting control method of the air source heat pump system according to claim 6, characterized in that: The indoor heat exchanger is also provided with an electric heating device, and the defrosting control method further comprises: During defrosting, the electric heating device is turned on to maintain the indoor temperature.

9. The defrost control method of the air source heat pump system according to claim 6, characterized in that: Also includes: When defrosting is finished, the solenoid valve and the electronic expansion valve are controlled to open, and the first bypass valve and the second bypass valve on the first bypass and the second bypass are controlled to close, and the air source heat pump system resumes the heating mode.

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