Heat pump system and waste water tank

Abstract

The invention provides a heat pump system and a waste water tank. The heat pump system comprises a main loop which is connected with a compressor, a first heat exchanger, a throttling device and a refrigerant pipeline of a second heat exchanger; the wastewater tank is used for receiving and storing domestic wastewater; the waste water heat recovery loop is connected with a driving device, a first heat exchange unit and a defrosting pipeline of the second heat exchanger, the second heat exchanger is a three-medium fluid heat exchanger, the defrosting pipeline and the refrigerant pipeline are thermally coupled with each other, and the first heat exchange unit is thermally coupled with the waste water tank; the heat pump system comprises a rapid defrosting mode, and in the rapid defrosting mode, the waste water heat recovery loop conveys waste heat of waste water in the waste water tank to the second heat exchanger so as to accelerate defrosting. According to the device provided by the embodiment of the invention, the efficiency of the heat pump system is effectively improved.

Description

Technical Field

[0001] The present invention relates to the field of heat pump devices, and more particularly to a wastewater tank and a heat pump system for recovering domestic wastewater and utilizing the residual heat therein. Background Art

[0002] For ordinary families, domestic wastewater is generated every day. In winter, the discharged domestic wastewater may still have a temperature of 20-30°C, which is significantly different from the outdoor temperature (which may be below zero).

[0003] On the other hand, the heat pump system usually works in heating mode in winter, and the outdoor heat exchanger is used as an evaporator to absorb heat by evaporation, making the temperature therein lower than the ambient temperature and prone to frost. The heat pump system usually has a defrost mode, which usually uses a four-way valve to adjust the refrigerant at the compressor outlet to the outdoor heat exchanger for defrosting. However, the defrost mode will cause the indoor heating to be interrupted and has a great impact on the performance of the heat pump system. Summary of the invention

[0004] The purpose of this application is to solve or at least alleviate the problems existing in the prior art.

[0005] According to one aspect of the present invention, there is provided a heat pump system, comprising: A main circuit, wherein the main circuit connects a compressor, a first heat exchanger, a throttling device and a refrigerant pipeline of a second heat exchanger, wherein when the heat pump system performs a heating mode, the first heat exchanger serves as a condenser and the second heat exchanger serves as an evaporator; A wastewater tank, the wastewater tank receiving and storing domestic wastewater; a wastewater heat recovery circuit, the wastewater heat recovery circuit being connected to a drive device, a first heat exchange unit and a defrost pipeline of the second heat exchanger, wherein the second heat exchanger is a three-medium fluid heat exchanger, the defrost pipeline and the refrigerant pipeline are thermally coupled to each other, and the first heat exchange unit is thermally coupled to the wastewater tank; Wherein, the heat pump system includes a rapid defrost mode, in which the wastewater heat recovery circuit transfers the waste heat of the wastewater in the wastewater tank to the second heat exchanger to accelerate defrosting.

[0006] Optionally, in an embodiment of the heat pump system, a second heat exchange unit is further provided in the waste water tank, and the second heat exchange unit is connected between the first heat exchanger and the throttling element in the main circuit.

[0007] Optionally, in an embodiment of the heat pump system, the heat pump system further includes: a first bypass branch connected in parallel with the second heat exchange unit and a first control valve, the first control valve being configured to selectively allow the refrigerant at the outlet of the first heat exchanger to pass through the second heat exchange unit or the first bypass branch based on the temperature of the domestic wastewater stored in the wastewater tank and the temperature of the refrigerant at the outlet of the first heat exchanger.

[0008] Optionally, in an embodiment of the heat pump system, the wastewater tank also includes a discharge passage, a discharge valve is provided on the discharge passage, and the discharge valve is configured to release part of the domestic wastewater when the temperature of the domestic wastewater in the wastewater tank is lower than a first threshold value, and the first threshold value is between 2°C-8°C.

[0009] Optionally, in an embodiment of the heat pump system, the three-medium fluid heat exchanger further includes a fan to exchange heat with ambient air, and in the rapid defrost mode, the fan is turned off.

[0010] Optionally, in an embodiment of the heat pump system, the wastewater heat recovery loop further includes an electric heater, and the heat pump system further includes a continuous heating mode, in which the electric heater is started to heat the heat transfer medium in the wastewater heat recovery loop.

[0011] Optionally, in an embodiment of the heat pump system, the wastewater heat recovery circuit also includes a second bypass branch connected in parallel with the first heat exchange unit and a second control valve, and the second control valve is configured to selectively allow the heat transfer medium in the wastewater heat recovery circuit to pass through the first heat exchange unit or the second bypass branch based on the temperature of the domestic wastewater stored in the wastewater tank.

[0012] Optionally, in an embodiment of the heat pump system, in the fast defrost mode, the refrigerant at the compressor outlet is delivered to the second heat exchanger for defrosting.

[0013] Optionally, in an embodiment of the heat pump system, the heat pump system also includes a high-performance heating mode, in which the four-way valve is in a position in the heating mode, and the wastewater heat recovery circuit transfers the waste heat of the wastewater in the wastewater tank to the second heat exchanger for increasing the evaporation temperature.

[0014] According to another aspect, there is provided a wastewater tank, the wastewater tank comprising: an inlet port for receiving domestic wastewater; Tanks for storing domestic wastewater; A first heat exchange unit and a second heat exchange unit are disposed in the wastewater tank, each of the first heat exchange unit and the second heat exchange unit comprising an inlet port and an outlet port to allow a first external fluid and a second external fluid to pass therethrough and exchange heat with domestic wastewater in the wastewater tank; and A discharge passage is provided with a discharge valve.

[0015] Optionally, in an embodiment of the wastewater tank, the wastewater tank further includes a temperature sensor and a liquid level sensor, and the discharge valve is controlled to release the domestic wastewater in the wastewater tank based on the liquid level in the wastewater tank and the temperature of the domestic wastewater in the wastewater tank.

[0016] The device according to the embodiment of the present invention effectively improves the efficiency of the heat pump system. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The disclosure of the present application will become more easily understood with reference to the accompanying drawings. It is easy for those skilled in the art to understand that these drawings are only for illustrative purposes and are not intended to limit the scope of protection of the present application. Additionally, like numerals are used to denote like parts in the drawings, wherein: Figure 1 A schematic structural diagram of a heat pump system according to an embodiment of the present invention is shown; and Figure 2 A schematic structural diagram of an exemplary three-medium fluid heat exchanger is shown. DETAILED DESCRIPTION

[0018] First reference Figure 1 The heat pump system according to an embodiment of the present invention is described below. The heat pump system includes: a main circuit 1, the main circuit 1 is connected to a compressor 11, a first heat exchanger 12, a throttling device 13 and a refrigerant circuit 141 of a second heat exchanger 14. The first heat exchanger 12 is, for example, an indoor heat exchanger and the second heat exchanger 14 is, for example, an outdoor heat exchanger. Although not shown, the heat pump system also includes a switching component, such as a four-way valve, to switch between a cooling mode and a heating mode. Figure 1 In the illustrated view, the heat pump system is in heating mode, the first heat exchanger 12 is connected to the outlet of the compressor 11 and acts as a condenser, and the second heat exchanger 14 is connected to the inlet of the compressor 11 and acts as an evaporator. It should be understood that in cooling mode or normal defrost mode, the second heat exchanger 14 is connected to the outlet of the compressor 11 and acts as a condenser.

[0019] The heat pump system further includes a wastewater tank 3, which is used to receive and store domestic wastewater. Domestic wastewater is generated by a wastewater source 4, which may include water for showering, washing machines, washing, kitchens, etc. Although in the illustrated embodiment, the wastewater source 4 is directly connected to the inlet port 30 of the wastewater tank 3, in an alternative embodiment, a discharge passage may be provided between the wastewater source 4 and the inlet port 30 of the wastewater tank 3 to selectively deliver domestic wastewater to the wastewater tank 3 or discharge it directly, for example, based on the wastewater temperature, the temperature and liquid level of domestic water stored in the wastewater tank 3, etc. More specifically, in a simple embodiment, the wastewater is delivered to the wastewater tank 3 when the temperature is higher than a predetermined value, otherwise it is discharged directly.

[0020] The heat pump system further includes: a wastewater heat recovery loop 2, which connects the drive device 21, the first heat exchange unit 31 and the defrost pipeline 22 of the second heat exchanger. The drive device 21, the first heat exchange unit 31 and the defrost pipeline 22 can be connected in series to form a loop, and the first heat exchange unit 31 is thermally coupled with the wastewater tank 3. For example, in the embodiment shown, the first heat exchange unit 31 is a coil disposed in the wastewater tank 3 or at least partially disposed in the wastewater tank 3. In addition, the second heat exchanger 14 is a three-medium fluid heat exchanger, including a thermally coupled defrost pipeline 22 and a refrigerant pipeline 141. The heat pump system includes a fast defrost mode. In the fast defrost mode, in addition to the refrigerant at the compressor outlet being transported to the refrigerant pipeline 141 of the second heat exchanger 14, the wastewater heat recovery loop 2 transports the waste heat of the wastewater in the wastewater tank 3 to the second heat exchanger 14 for accelerating defrosting. Through this arrangement, in the fast defrost mode, the heat transfer medium (such as water or antifreeze) in the wastewater heat recovery loop 2 transfers the residual heat in the wastewater to the second heat exchanger 14, which is simultaneously implemented by switching the four-way valve to transfer the hot steam at the compressor outlet to the second heat exchanger 14, so that the frost in the second heat exchanger 14 can be eliminated more quickly, thereby speeding up the defrost process, saving the time required for defrosting, and thus improving the efficiency of the heat pump system.

[0021] In some embodiments, a second heat exchange unit 32 is further provided in the wastewater tank 3, and the second heat exchange unit 32 is connected between the first heat exchanger 12 and the throttling element 13 in the main circuit 1, so that the refrigerant at the outlet of the condenser can be used to exchange heat with the domestic wastewater in the wastewater tank 3. The second heat exchange unit 32 can also be a coil located in the wastewater tank 3. In some embodiments, the heat pump system further includes: a first bypass branch 15 and a first control valve 16 connected in parallel with the second heat exchange unit 32, and the first control valve 16 is configured to selectively allow the refrigerant at the outlet of the first heat exchanger to pass through the second heat exchange unit 32 or the first bypass branch 15 based on the temperature of the domestic wastewater stored in the wastewater tank 3 and the temperature of the refrigerant at the outlet of the first heat exchanger. For example, if the temperature of the domestic wastewater stored in the wastewater tank 3 is lower than the temperature of the refrigerant at the outlet of the condenser, the refrigerant can be passed through the second heat exchange unit 32, thereby heating the temperature of the domestic wastewater in the wastewater tank 3 for subsequent defrosting, and increasing the subcooling degree of the refrigerant, thereby further improving the overall efficiency of the heat pump system; otherwise, the refrigerant is passed through the first bypass branch 15. In the illustrated embodiment, the first control valve 16 is a three-way valve. In an alternative embodiment, the first control valve 16 may also include two independent valves located on the branch where the second heat exchange unit 32 is located and the first bypass branch 15, or other valves for controlling fluids in the art.

[0022] In some embodiments, the wastewater tank 3 further includes a discharge passage 33, on which a discharge valve 34 is provided, and the discharge valve 34 is configured to release part of the domestic wastewater when the temperature of the domestic wastewater in the wastewater tank 3 is lower than a first threshold value. For example, the first threshold value may be taken in the range of 2°C-8°C, for example, the first threshold value is 5°C. When the temperature of the domestic wastewater in the wastewater tank 3 decreases, ice may form in the wastewater tank. In order to prevent this from happening, part of the domestic wastewater is released when the temperature of the domestic wastewater in the wastewater tank is low to reduce the liquid level of the domestic wastewater stored in the wastewater tank 3. At the same time, as described above, the refrigerant at the outlet of the condenser in the main circuit is used to heat the wastewater in the wastewater tank 3. Since the water level of the wastewater tank has been reduced at this time, it is easier to heat the wastewater stored in the wastewater tank to the desired temperature to avoid ice forming in the wastewater tank 3.

[0023] In some embodiments, the wastewater heat recovery loop 2 may further include an electric heater 25. In addition, the heat pump system may further include a continuous heating mode, in which the electric heater 25 is started to heat the heat transfer medium in the wastewater heat recovery loop, thereby maintaining a higher evaporation temperature of the second heat exchanger 14 to avoid frost therein, thereby ensuring that the system does not need to execute a defrost mode and the heat pump system can continue to operate in the heating mode. However, enabling the electric heater 25 may increase the overall energy consumption of the heat pump system, so the continuous heating mode may be enabled based on the user's choice or enabled during the low-peak electricity price period to take into account comfort and use costs. In some embodiments, the wastewater heat recovery loop 2 also includes a second bypass branch 23 connected in parallel with the first heat exchange unit 31 and a second control valve 24, and the second control valve 24 is configured to selectively allow the heat transfer medium in the wastewater heat recovery loop to pass from the first heat exchange unit 31 or the second bypass branch 23 based on the temperature of the domestic wastewater stored in the wastewater tank 3. For example, when the electric heater 25 is enabled, if the temperature of the heat transfer medium in the wastewater heat recovery loop 2 is higher than the temperature of the domestic wastewater in the wastewater tank 3, the heat transfer medium can be passed through the second bypass branch 23; otherwise, the heat transfer medium passes through the wastewater tank 3 to absorb the heat of the domestic wastewater therein. In the illustrated embodiment, the second control valve 24 is a three-way valve. In alternative embodiments, the second control valve 24 may also include two independent valves or other valves for controlling fluids in the art. In some embodiments, the electric heater 25 may also be turned on in the aforementioned fast defrosting mode.

[0024] In some embodiments, the heat pump system further includes a high-performance heating mode, in which the wastewater heat recovery loop 2 transfers the waste heat of the wastewater in the wastewater tank to the second heat exchanger for increasing the evaporation temperature, that is, when the main loop performs a heating cycle, the heat of the wastewater in the wastewater tank is transferred to the evaporator to increase the evaporation temperature. This mode can be executed when the ambient temperature is high and there is no risk of frost on the evaporator 14, thereby improving the overall efficiency of the system, and / or this mode can be executed when the wastewater temperature in the wastewater tank is high and the storage volume is high, at which time the waste heat of domestic wastewater is used to improve the overall efficiency of the system.

[0025] In some embodiments, in a three-medium fluid heat exchanger, the defrost line 22 is thermally coupled to the refrigerant line 141, and the three-medium fluid heat exchanger also includes a fan to exchange heat with ambient air, wherein, in the fast defrost mode, the fan is turned off so that both the defrost line 22 and the refrigerant line 141 exchange heat. Figure 1 FIG. 1 shows an embodiment of a three-medium fluid heat exchanger, wherein the defrost pipe 22 and the refrigerant pipe 141 are arranged alternately and adjacently (black and white pipes in the figure), thereby allowing the defrost pipe 22 to fully exchange heat with the refrigerant pipe 141. Figure 2, which shows another exemplary second heat exchanger. In the three-medium fluid heat exchanger, the defrost line 22 is wrapped around the outside of a partial section of the refrigerant line 141, and a heat dissipation fin 142 is provided in the effective heat exchange section, which defines the air flow path. It should be understood that the specific structure of the three-medium fluid heat exchanger can be different from the structure shown, for example, the defrost line 22 can be thermally coupled with the refrigerant line 141 in other ways, for example, the lines of both can be spirally wound or formed as different parts of multiple microchannels, etc.

[0026] According to another aspect, the present invention also provides a wastewater tank 3, which includes: an inlet port 30 for receiving domestic wastewater; a box body for storing domestic wastewater; a first heat exchange unit 31 and a second heat exchange unit 32 arranged in the wastewater tank, each of which includes an inlet port and an outlet port to allow a first external fluid and a second external fluid to pass through and exchange heat with the domestic wastewater in the wastewater tank 3; and a discharge passage 33, on which a discharge valve 34 is arranged. In some embodiments, the wastewater tank 3 also includes a temperature sensor and a liquid level sensor to detect the temperature and liquid level of the domestic wastewater in the wastewater tank 3, and the discharge valve 34 releases the domestic wastewater in the wastewater tank based on the liquid in the wastewater tank and the temperature of the domestic wastewater in the wastewater tank. In addition, the above-mentioned liquid level signal and temperature signal can also be provided to the controller of the heat pump system so as to perform other controls on the heat pump system based on the above-mentioned signals, such as the positions of the above-mentioned first control valve 16 and the second control valve 24, etc. By providing a wastewater tank in the heat pump system, domestic wastewater can be stored, and the waste heat of the domestic wastewater can be used to speed up the defrosting process when defrosting is required. In addition, the wastewater tank body can be made of heat-insulating materials to prevent the loss of wastewater heat as much as possible. The wastewater tank can be optionally set indoors to prevent the loss of wastewater heat, and alternatively, the wastewater tank can also be set outdoors to save indoor space.

[0027] The device according to the embodiment of the present invention effectively improves the efficiency of the heat pump system. More specifically, when the outdoor temperature is between -20 and -15°C, in the fast defrost mode, the use of waste water waste heat can increase the COP by at least 7% compared to conventional reverse defrosting using a four-way valve alone; compared to defrosting using pure electric heating, the COP can be increased by 10%-20%. On the other hand, the heat pump system can support a continuous heating mode when an electric heater is provided, thereby improving comfort.

[0028] The specific embodiments described above in this application are only for more clearly describing the principles of this application, wherein each component is clearly shown or described to make the principles of the present invention easier to understand. Without departing from the scope of this application, those skilled in the art can easily make various modifications or changes to this application. Therefore, it should be understood that these modifications or changes should be included in the scope of patent protection of this application.

Claims

1. A heat pump system, comprising: A main circuit, wherein the main circuit connects a compressor, a first heat exchanger, a throttling device and a refrigerant pipeline of a second heat exchanger, wherein when the heat pump system performs a heating mode, the first heat exchanger serves as a condenser and the second heat exchanger serves as an evaporator; A wastewater tank, the wastewater tank receiving and storing domestic wastewater; a wastewater heat recovery circuit, the wastewater heat recovery circuit being connected to a drive device, a first heat exchange unit and a defrost pipeline of the second heat exchanger, wherein the second heat exchanger is a three-medium fluid heat exchanger, the defrost pipeline and the refrigerant pipeline are thermally coupled to each other, and the first heat exchange unit is thermally coupled to the wastewater tank; Wherein, the heat pump system includes a rapid defrost mode, in which the wastewater heat recovery circuit transfers the waste heat of the wastewater in the wastewater tank to the second heat exchanger to accelerate defrosting.

2. The heat pump system according to claim 1, characterized in that: A second heat exchange unit is also provided in the waste water tank, and the second heat exchange unit is connected between the first heat exchanger and the throttling element in the main circuit.

3. The heat exchange system according to claim 2, characterized in that: The heat pump system also includes: a first bypass branch connected in parallel with the second heat exchange unit and a first control valve, wherein the first control valve is configured to selectively allow the refrigerant at the outlet of the first heat exchanger to pass through the second heat exchange unit or the first bypass branch based on the temperature of the domestic wastewater stored in the wastewater tank and the temperature of the refrigerant at the outlet of the first heat exchanger.

4. The heat pump system according to any one of claims 1 to 3, characterized in that: The wastewater tank further comprises a discharge passage, on which a discharge valve is arranged, and the discharge valve is configured to release part of the domestic wastewater when the temperature of the domestic wastewater in the wastewater tank is lower than a first threshold value, and the first threshold value is between 2°C and 8°C.

5. The heat pump system according to any one of claims 1 to 3, characterized in that: The three-media fluid heat exchanger further includes a fan for exchanging heat with ambient air, wherein in the fast defrost mode, the fan is turned off.

6. The heat pump system according to any one of claims 1 to 3, characterized in that: The wastewater heat recovery loop further includes an electric heater, and the heat pump system further includes a continuous heating mode, in which the electric heater is started to heat the heat transfer medium in the wastewater heat recovery loop.

7. The heat pump system according to claim 6, characterized in that: The wastewater heat recovery loop also includes a second bypass branch connected in parallel with the first heat exchange unit and a second control valve, wherein the second control valve is configured to selectively allow the heat transfer medium in the wastewater heat recovery loop to pass through the first heat exchange unit or the second bypass branch based on the temperature of the domestic wastewater stored in the wastewater tank.

8. The heat pump system according to any one of claims 1 to 3, characterized in that: The heat pump system also includes a high-performance heating mode, in which the four-way valve is in a heating mode position, and the wastewater heat recovery circuit transfers waste heat of the wastewater in the wastewater tank to the second heat exchanger for increasing the evaporation temperature.

9. A wastewater tank, characterized in that: The waste water tank comprises: an inlet port for receiving domestic wastewater; Tanks for storing domestic wastewater; A first heat exchange unit and a second heat exchange unit are disposed in the wastewater tank, each of the first heat exchange unit and the second heat exchange unit comprising an inlet port and an outlet port to allow a first external fluid and a second external fluid to pass therethrough and exchange heat with domestic wastewater in the wastewater tank; and A discharge passage is provided with a discharge valve.

10. The waste water tank according to claim 9, characterized in that: The wastewater tank further includes a temperature sensor and a liquid level sensor, and the discharge valve is controlled to release the domestic wastewater in the wastewater tank based on the liquid level in the wastewater tank and the temperature of the domestic wastewater in the wastewater tank.

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