Transcritical CO2 heat pump heating performance improving system and method

Abstract

The invention relates to a transcritical CO2 heat pump heating performance improving system and method, and the system comprises a refrigerant side loop which is characterized in that the output end of a gas-liquid separator communicates with the gas input end of a gas cooler through a compressor; the gas output end of the gas cooler is communicated with the first input end of the intermediate heat exchanger; the first output end of the intermediate heat exchanger is communicated with the input end of the evaporator, and the second output end is communicated with the input end of the gas-liquid separator; the output end of the evaporator communicates with the second input end of the intermediate heat exchanger; according to the refrigerant side loop, the cooling liquid input end of a gas cooler is communicated with the water return end, and the cooling liquid output end of the gas cooler is communicated with the water supply end. By the adoption of the technical scheme, the return water temperature can be reduced through evaporation heat absorption, then the refrigerant temperature before throttling is reduced, the refrigerant flow is increased, the evaporation temperature is increased, and meanwhile the energy utilization efficiency is further improved while the heating stability is guaranteed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of building energy saving, and in particular to a transcritical CO2 heat pump heating performance improvement system and method. BACKGROUND

[0002] In the field of building energy saving, transcritical CO2 heat pump heating systems are widely concerned due to their environmental protection and high efficiency. They use CO2 as a refrigerant and realize the conversion of low-grade heat energy to high-grade heat energy through a compressor drive, which can meet the demand for building heating in winter. However, the system efficiency and stability are significantly affected by factors such as ambient temperature and return water temperature. How to optimize the cycle process to improve performance has become a key direction for the development of this technology. Among them, heat pipe heat exchangers, with their high-efficiency phase-change heat transfer capacity and compact structure, provide a feasible path to solve the problems of energy loss and frosting, and promote the coupling application research of transcritical CO2 heat pump and heat pipe technology.

[0003] In the prior art, the return water temperature in the traditional transcritical CO2 heat pump heating system is high, which will cause the throttling loss to increase and reduce the heating efficiency. When the return water temperature is high, the CO2 temperature at the outlet of the gas cooler rises, and during the throttling and pressure reduction process of the electronic expansion valve, the entropy increases significantly and the flash steam increases, which not only consumes additional energy, but also reduces the coefficient of performance (COP) of the system. For example, when the return water temperature rises from 20℃ to 50℃, the throttling loss increases significantly and the COP decreases substantially. Moreover, the evaporator is prone to frosting at low temperature, which affects the stability of the system. When the outdoor temperature is low, the frost layer on the surface of the evaporator will deteriorate the heat transfer effect, resulting in reduced refrigerant flow and decreased heating capacity. At the same time, the compression ratio of the compressor increases, which aggravates the wear of the parts and the increase of the exhaust temperature, and in severe cases, it even affects the normal operation of the unit.

[0004] It should be noted that the information disclosed in the above background section is only used to strengthen the understanding of the background of the present disclosure, and therefore can include information that does not constitute prior art known to those of ordinary skill in the art. SUMMARY

[0005] To solve the above problems, the present application provides a transcritical CO2 heat pump heating performance improvement system and method, which can reduce the return water temperature through evaporation heat absorption, thereby reducing the refrigerant temperature before throttling, and increasing the refrigerant flow and improving the evaporation temperature. At the same time, while ensuring the stability of heating, the energy utilization efficiency is further improved.

[0006] To achieve the purpose of the present application, the present application provides the following technical solutions:

[0007] In a first aspect, the present application provides a transcritical CO2 heat pump heating performance improvement system, comprising:

[0008] A refrigerant side circuit comprising: a compressor, a gas cooler, an intermediate heat exchanger, an evaporator and a gas-liquid separator;

[0009] An output of the gas-liquid separator is in communication with a gas input of the gas cooler via the compressor;

[0010] A gas output of the gas cooler is in communication with a first input of the intermediate heat exchanger;

[0011] A first output of the intermediate heat exchanger is in communication with an input of the evaporator and a second output is in communication with an input of the gas-liquid separator;

[0012] An output of the evaporator is in communication with a second input of the intermediate heat exchanger;

[0013] A water side circuit comprising: a water supply end and a water return end; a cooling liquid input of the gas cooler is in communication with the water return end and a cooling liquid output of the gas cooler is in communication with the water supply end.

[0014] In a possible implementation, a first temperature sensor is provided on the water return end for detecting a water return temperature.

[0015] In a possible implementation, a dry filter is provided on a communication conduit between the gas output of the gas cooler and the first input of the intermediate heat exchanger.

[0016] In a possible implementation, an electronic expansion valve is provided on a communication conduit between the first output of the intermediate heat exchanger and the input of the evaporator.

[0017] In a possible implementation, a first electromagnetic valve is provided on a communication conduit between the water return end and the cooling liquid input of the gas cooler.

[0018] In a possible implementation, the transcritical CO2 heat pump heating performance improvement system further comprises:

[0019] A heat pipe heat exchanger circuit comprising a heat pipe heat exchanger, the water return end and the cooling liquid input of the gas cooler are further in communication via a spiral coil, the spiral coil is in heat exchange connection with a cold end of the heat pipe heat exchanger.

[0020] In a possible implementation, a second electromagnetic valve is provided on the spiral coil.

[0021] In a possible implementation, an output of the gas-liquid separator is further in communication with the input of the evaporator via the compressor.

[0022] In a possible implementation, a communication pipe between the compressor and the evaporator is provided with a third electromagnetic valve, and the coil pipe of the evaporator is further provided with a second temperature sensor.

[0023] In a second aspect, the application further provides a transcritical CO2 heat pump heating system performance improvement method, which is used for controlling the transcritical CO2 heat pump heating performance improvement system.

[0024] When the temperature of the return water end is less than a preset value, the first electromagnetic valve is opened, and the second electromagnetic valve and the third electromagnetic valve are closed.

[0025] When the temperature of the return water end is greater than or equal to the preset value, the second electromagnetic valve is opened, and the first electromagnetic valve and the third electromagnetic valve are closed.

[0026] When the temperature of the evaporator coil pipe is less than a second preset value, timing is performed, when the cumulative time exceeds a preset period, and the temperature of the evaporator coil pipe is lower than a third preset value, the second electromagnetic valve and the third electromagnetic valve are opened, and the first electromagnetic valve is closed.

[0027] The technical scheme provided by the application can include the following beneficial effects:

[0028] Through the transcritical CO2 heat pump heating performance improvement system and method, the cold end of the heat pipe heat exchanger and the return water heat exchange are utilized, the return water temperature is reduced through evaporation heat absorption, and then the refrigerant temperature before throttling is reduced; and the hot end of the heat pipe heat exchanger is combined with the gas-liquid separator, the internal refrigerant is heated through heat release, part of the liquid refrigerant is vaporized to participate in circulation, the refrigerant flow is increased, and the evaporation temperature is improved; at the same time, through the cooperative control of the electromagnetic valve and the temperature sensor, automatic switching of three modes of normal heating, heat recovery and defrosting is realized, the process can be dynamically adjusted according to the return water temperature and the coil pipe temperature, the energy utilization efficiency is further improved while the heating stability is ensured.

[0029] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0030] The accompanying drawings are used to provide a further understanding of the present application, and constitute a part of the specification, which are used to explain the present application together with embodiments of the present application, and do not constitute a limitation to the present application. Obviously, the drawings in the following description are only some embodiments of the present disclosure, and other drawings can be obtained by those skilled in the art without creative labor.

[0031] Figure 1 A transcritical CO2 heat pump heating performance improvement system provided by the embodiments of the present application is shown in the structural schematic diagram;

[0032] Figure 2 A flowchart of a transcritical CO2 heat pump heating performance improvement method provided for an embodiment of the present application;

[0033] Figure 3 A control logic diagram of a transcritical CO2 heat pump heating performance improvement method provided for an embodiment of the present application;

[0034] Figure 4 A transcritical CO2 heat pump heating performance improvement method provided for an embodiment of the present application. The pressure-enthalpy diagram comparison diagram of the regular heating mode and the heat recovery mode;

[0035] Figure 5 A transcritical CO2 heat pump heating performance improvement system provided for an embodiment of the present application. The comparison diagram of the evaporator fin temperature change over time of the unit;

[0036] Figure 6 A transcritical CO2 heat pump heating performance improvement system provided for an embodiment of the present application. The comparison diagram of the COP change over time of the unit.

[0037] Reference signs:

[0038] 1, compressor; 2, gas cooler; 3, intermediate heat exchanger; 4, evaporator; 5, gas-liquid separator; 6, heat pipe heat exchanger; 7, water supply end; 8, return water end; 9, dry filter; 10, electronic expansion valve; 11, first solenoid valve; 12, first temperature sensor; 13, second solenoid valve; 14, third solenoid valve; 15, second temperature sensor. DETAILED DESCRIPTION

[0039] Example implementations will now be described more fully with reference to the accompanying drawings. Example implementations may, however, be implemented in many different forms and should not be construed as limited to the examples set forth herein; rather, these implementations are provided so that this disclosure will be thorough and complete, and will fully convey the scope of example implementations to those skilled in the art. The described features, structures, or characteristics can be combined in one or more implementations.

[0040] In the present example implementation, a dynamic interference power management transcritical CO2 heat pump heating performance improvement system under feedback sparsity and observation missing conditions is first provided. Referring to FIG. 1, the transcritical CO2 heat pump heating performance improvement system includes a refrigerant side circuit and a refrigerant side circuit; wherein: Figure 1 The refrigerant side circuit includes a compressor 1, a gas cooler 2, an intermediate heat exchanger 3, an evaporator 4, and a gas-liquid separator 5.

[0041]

[0042] ​The output end of the gas-liquid separator 5 is connected to the gas input end of the gas cooler 2 through the compressor 1;

[0043] The gas output end of the gas cooler 2 is connected to the first input end of the intermediate heat exchanger 3;

[0044] The first output end of the intermediate heat exchanger 3 is connected to the input end of the evaporator 4, and the second output end is connected to the input end of the gas-liquid separator 5;

[0045] The output end of the evaporator 4 is connected to the second input end of the intermediate heat exchanger 3;

[0046] The water side circuit includes: a water supply end 7 and a water return end 8; the coolant input end of the gas cooler 2 is connected to the water return end 8, and the coolant output end of the gas cooler 2 is connected to the water supply end 7.

[0047] In a possible embodiment, the return water end 8 is provided with a first temperature sensor 12 for detecting the return water temperature.

[0048] It can be understood that the first temperature sensor 12 can monitor the return water temperature in real time, and the system can accurately determine whether the current operating conditions meet the start-up conditions of conventional heating or heat recovery mode, ensuring that the conventional heating mode is used first when the return water temperature is lower than the preset value, and switching to the heat recovery mode when it is higher than or equal to the preset value, thereby realizing dynamic regulation of the system operation status and improving the targeted energy utilization.

[0049] In a possible embodiment, a drying filter 9 is provided on the communication pipe between the gas output end of the gas cooler 2 and the first input end of the intermediate heat exchanger 3 .

[0050] It's understood that the primary function of the filter drier 9 is to remove moisture and impurities from the refrigerant. During the refrigerant circulation process, moisture may enter due to system leaks or environmental factors. Moisture can easily freeze at low temperatures, clogging pipes or the electronic expansion valve. Impurities can also cause wear and tear on components like the compressor. The presence of the filter drier 9 effectively mitigates these issues, ensuring smooth refrigerant circuit operation and long-term stable equipment operation.

[0051] In a possible embodiment, an electronic expansion valve 10 is provided on the communication pipe between the first output end of the intermediate heat exchanger 3 and the input end of the evaporator 4 .

[0052] It can be understood that the electronic expansion valve 10 controls the flow and pressure drop of the refrigerant by adjusting the opening degree, so that the high-pressure refrigerant flowing out of the intermediate heat exchanger 3 is throttled and converted into a low-pressure gas-liquid mixture, which is convenient for absorbing heat in the air in the evaporator 4. The precise regulation capability can adapt to the refrigerant demand under different working conditions, further optimizing the heating efficiency and stability of the system.

[0053] In one possible implementation, a first electromagnetic valve 11 is arranged on the communication pipeline between the water return end 8 and the cooling liquid input end of the gas cooler 2.

[0054] It can be understood that when the system is in a normal heating mode, the first electromagnetic valve 11 is opened, so that the return water directly enters the gas cooler 2 to exchange heat with the refrigerant, ensuring that hot water is quickly supplied; and in other modes, the first electromagnetic valve 11 is closed, avoiding the return water directly entering the gas cooler without being cooled by the heat pipe heat exchanger, ensuring the energy saving effect of the heat recovery and defrosting modes.

[0055] Further, in one possible implementation, the transcritical CO2 heat pump heating performance improvement system further comprises:

[0056] A heat pipe heat exchanger circuit comprising the heat pipe heat exchanger 6, the water return end 8 and the cooling liquid input end of the gas cooler 2 are further communicated through a spiral coil, and the spiral coil is in heat exchange connection with the cold end of the heat pipe heat exchanger 6.

[0057] Further, a second electromagnetic valve 13 is arranged on the spiral coil.

[0058] In one possible implementation, the output end of the gas-liquid separator 5 is further communicated with the input end of the evaporator 4 through the compressor 1.

[0059] It can be understood that the communication path provides an additional circulation channel for the refrigerant in the defrosting mode. In the defrosting mode, part of the high-temperature and high-pressure refrigerant can bypass the gas cooler 2 and be directly delivered to the evaporator 4 through the compressor 1, so as to melt the frost layer on the surface of the evaporator by using the high temperature of the refrigerant, greatly improving the defrosting efficiency, and avoiding the problem of interruption of indoor heating caused by defrosting.

[0060] In one possible implementation, a third electromagnetic valve 14 is arranged on the communication pipeline between the compressor 1 and the evaporator 4, and a second temperature sensor 15 is further arranged on the coil of the evaporator 4.

[0061] It can be understood that the third electromagnetic valve 14 is used to control the shunt path of the refrigerant in the defrosting mode, and is only opened during defrosting, ensuring that the high-temperature refrigerant accurately flows to the evaporator 4 to achieve rapid defrosting; the second temperature sensor 15 monitors the evaporator coil temperature to provide a basis for defrosting timing and mode switching, and triggers defrosting when the coil temperature is lower than the set value and meets the time length condition, and stops when the temperature rises to the threshold value, ensuring the intelligence and energy saving of the defrosting process.

[0062] Further, in the example embodiment, a transcritical CO2 heat pump heating system performance improvement method is also provided for controlling the transcritical CO2 heat pump heating performance improvement system described above. Referring to Figure 2 the method can include:

[0063] Step S100, when the temperature of the return water end 8 is less than the preset value, the first electromagnetic valve 11 is opened, and the second electromagnetic valve 13 and the third electromagnetic valve 14 are closed.

[0064] Step S200, when the temperature of the return water end 8 is greater than or equal to the preset value, the second electromagnetic valve 13 is opened, and the first electromagnetic valve 11 and the third electromagnetic valve 14 are closed.

[0065] Step S300, when the temperature of the evaporator 4 coil is less than the second preset value, timing is performed, and when the cumulative time exceeds the preset period and the evaporator coil temperature is lower than the third preset value, the second electromagnetic valve 13 and the third electromagnetic valve 14 are opened, and the first electromagnetic valve 11 is closed.

[0066] It should be noted that when the temperature of the return water end 8 is less than the first preset value (such as 30°C), it is a normal heating mode, the first electromagnetic valve 11 is opened, and the second electromagnetic valve 13 and the third electromagnetic valve 14 are closed. In this mode:

[0067] Refrigerant side circuit: CO2 refrigerant is compressed into high-temperature and high-pressure by the compressor 1, exchanges heat with water through the jacketed gas cooler 2, passes through the drying filter 9, the intermediate heat exchanger 3, and then enters the evaporator 4 after being throttled and pressure-reduced by the electronic expansion valve 10, absorbs heat from the air, and then enters the gas-liquid separator 5 after the heat exchanger, and the gas returns to the compressor 1.

[0068] Water side circuit: The hot water discharged from the water supply end 7 of the gas cooler 2 releases heat to the user, and then the temperature of the return water entering the return water end 8 decreases, and the return water enters the gas cooler 2 through the first electromagnetic valve 11 to exchange heat with CO2, and the temperature rises to obtain hot water discharged from the water supply end 7.

[0069] And when the temperature of the return water end 8 is greater than or equal to the first preset value (such as 30°C), it is a heat recovery mode, the second electromagnetic valve 13 is opened, and the first electromagnetic valve 11 and the third electromagnetic valve 14 are closed. In this mode:

[0070] Refrigerant side circuit: CO2 refrigerant is compressed by compressor 1 into high temperature and high pressure, exchanges heat with water through the sleeve type gas cooler 2, passes through the drying filter 9, the intermediate heat exchanger 3, and then enters the evaporator 4 after being throttled and decompressed by the electronic expansion valve 10, absorbs the heat in the air, and then enters the gas-liquid separator 5 after the heat exchanger 3, and the gas returns to the compressor 1.

[0071] Water side circuit: The hot water discharged from the water supply end 7 of the gas cooler 2 releases heat to the user, and the temperature decreases, that is, the return water enters from the return water end 8, the return water further reduces the temperature through the second electromagnetic valve 13 and the cold end of the U-shaped heat pipe heat exchanger, and then enters the gas cooler 2 to exchange heat with CO2, and the temperature rises, that is, the hot water discharged from the water supply end 7.

[0072] Heat pipe heat exchanger 6 circuit: The heat exchanger one section exchanges heat with the return water through the spiral coil, absorbs heat, and the hot end is connected with the gas-liquid separator, which releases heat through the hot end, heats the refrigerant in the gas-liquid separator, and makes part of the liquid gasify, thereby making more refrigerant participate in the system circulation, thereby improving the evaporation temperature, delaying frosting, and improving energy efficiency.

[0073] At the same time, as shown in Figure 3 When the temperature (te) of the evaporator 4 coil is less than the second preset value (such as 3°C), the unit starts to defrost, when the cumulative time exceeds the set defrosting period, and the coil temperature is lower than the third preset value (such as -3°C), the unit enters the defrosting mode, during the defrosting process, when the coil temperature is not lower than the fourth preset value (such as 20°C), the unit stops defrosting and restores the normal heating mode or the heat recovery mode, adopts temperature-time control defrosting, the second electromagnetic valve 13 and the third electromagnetic valve 14 are opened, and the first electromagnetic valve 11 is closed. In this mode:

[0074] Refrigerant side circuit: CO2 refrigerant is compressed by compressor 1 into high temperature and high pressure, is divided into two paths, one path exchanges heat with water through the sleeve type gas cooler 2, passes through the drying filter 9, the intermediate heat exchanger 3, and then enters the evaporator 4 after being throttled and decompressed by the electronic expansion valve 10, absorbs the heat in the air, and then enters the gas-liquid separator 5 after the heat exchanger 3, and the gas returns to the compressor 1. The other path enters the evaporator 4 after being mixed with the refrigerant throttled by the third electromagnetic valve 14 and the electronic expansion valve 10.

[0075] Water side circuit: The hot water discharged from the water supply end 7 of the gas cooler 2 releases heat to the user, and the temperature decreases, that is, the return water enters from the return water end 8, the return water further reduces the temperature through the second electromagnetic valve 13 and the cold end of the U-shaped heat pipe heat exchanger, and then enters the gas cooler 2 to exchange heat with CO2, and the temperature rises, that is, the hot water discharged from the water supply end 7.

[0076] The heat pipe heat exchanger 6 circuit: the heat exchanger one section and the return water pass through the spiral coil to carry out heat exchange, absorb heat, the hot end is connected with the gas-liquid separator, heat is released through the hot end, heats the refrigerant in the gas-liquid separator, makes part of liquid gasify, further makes more refrigerant participate in the defrosting mode cycle, further improves the evaporation temperature, improves the defrosting rate.

[0077] Further, as shown in Figure 4 The conventional heating mode heating capacity Q1: Q1=h2-h3

[0078] The compressor specific work w1: w1=h2-h1;

[0079] The heat recovery mode heating capacity Q2: Q2=h 2′ -h 3′ ;

[0080] The compressor specific work w2: w2=h 2′ -h 1′ ;

[0081] From the figure, it can be seen that:

[0082] Q1<Q2

[0083] w1<w2

[0084] Therefore:

[0085]

[0086] The defrosting mode pressure-enthalpy diagram is similar to the heat recovery mode, and will not be repeated.

[0087] Further, for the prior art unit and the unit of the present application, under the condition that the dry-bulb temperature is-5℃ and the air relative humidity is 90%, the fin temperature of the evaporator changes with time during the frosting process.

[0088] As Figure 5As shown, with the extension of the frosting time, the surface temperature of the evaporator fins shows an overall downward trend. The fin temperature of the prior art unit drops from -10.9°C to -13.5°C. Within 31 minutes of frosting, the fin temperature drop rate is small. As the frosting time increases, the frost layer grows from the initial granular ice crystals to needle-shaped frost crystals, growing in a direction perpendicular to the fin surface, and then changes from needle-shaped frost crystals to feather-shaped. The growth rate becomes faster, and the rate of decrease of the fin temperature accelerates. The fin temperature of the unit of the present application drops from -6.6°C to -8.2°C. Within 60 minutes of frosting, the fin temperature drop rate is slow. As time goes by, the fin temperature drops to -8.2°C, the heating performance of the unit decreases, and the system starts intelligent defrosting. By comparing the two figures, it can be found that the fin temperature of the unit of the present application is higher than that of the prior art unit, which is conducive to delaying the growth of the frost layer.

[0089] Furthermore, the changes in the theoretical cycle coefficient of performance (COP) of the prior art unit and the unit of the present application were compared in the heating mode at a dry bulb temperature of 5° C. and a relative air humidity of 90%.

[0090] like Figure 6 As shown in the figure, when tested under the working conditions of dry bulb temperature of 5℃ and relative humidity of 90%, the COP increased from 3.185 to 3.209, and the evaporation temperature increased by about 4-5℃.

[0091] Those skilled in the art will readily appreciate other embodiments of the present disclosure after considering the specification and practicing the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present disclosure that follow the general principles of the present disclosure and include common knowledge or customary techniques in the art not disclosed herein. The description and examples are to be considered as exemplary only, with the true scope and spirit of the present disclosure being indicated by the appended claims.

[0092] The above embodiments are intended only to illustrate the technical solutions of the present application and are not intended to limit them. The present application is not limited to the precise structures described above and illustrated in the accompanying drawings, and it cannot be assumed that the specific implementation of the present application is limited to these descriptions. For those skilled in the art of the present application, any changes and modifications made without departing from the concept of the present application should be deemed to fall within the scope of protection of the present application.

Claims

1. A transcritical CO2 heat pump heating performance improvement system, characterized in that: include: Refrigerant side circuit, including: compressor, gas cooler, intermediate heat exchanger, evaporator and gas-liquid separator; The output end of the gas-liquid separator is connected to the gas input end of the gas cooler through the compressor; The gas output end of the gas cooler is in communication with the first input end of the intermediate heat exchanger; The first output end of the intermediate heat exchanger is connected to the input end of the evaporator, and the second output end is connected to the input end of the gas-liquid separator; The output end of the evaporator is connected to the second input end of the intermediate heat exchanger; The water side circuit includes: a water supply end and a water return end; the cooling liquid input end of the gas cooler is connected to the water return end, and the cooling liquid output end of the gas cooler is connected to the water supply end.

2. The transcritical CO2 heat pump heating performance improvement system according to claim 1, characterized in that: The return water end is provided with a first temperature sensor for detecting the return water temperature.

3. The transcritical CO2 heat pump heating performance improvement system according to claim 1, characterized in that: A drying filter is provided on the communication pipe between the gas output end of the gas cooler and the first input end of the intermediate heat exchanger.

4. The transcritical CO2 heat pump heating performance improvement system according to claim 1, characterized in that: An electronic expansion valve is provided on the communication pipe between the first output end of the intermediate heat exchanger and the input end of the evaporator.

5. The transcritical CO2 heat pump heating performance improvement system according to claim 1, characterized in that: A first solenoid valve is provided on the communication pipe between the return water end and the coolant input end of the gas cooler.

6. The transcritical CO2 heat pump heating performance improvement system according to claim 5, characterized in that: Also includes: The heat pipe heat exchanger circuit includes a heat pipe heat exchanger, wherein the return water end and the coolant input end of the gas cooler are connected through a spiral coil, and the spiral coil is connected to the cold end of the heat pipe heat exchanger for heat exchange.

7. The transcritical CO2 heat pump heating performance improvement system according to claim 6, characterized in that: The spiral coil is provided with a second solenoid valve.

8. The transcritical CO2 heat pump heating performance improvement system according to claim 7, characterized in that: The output end of the gas-liquid separator is also connected to the input end of the evaporator through the compressor.

9. The transcritical CO2 heat pump heating performance improvement system according to claim 8, characterized in that: A third solenoid valve is provided on the connecting pipe between the compressor and the evaporator, and a second temperature sensor is provided on the coil of the evaporator.

10. A method for improving the performance of a transcritical CO2 heat pump heating system, characterized in that: The method is used to control the transcritical CO2 heat pump heating performance improvement system according to claim 9, and the method comprises: When the temperature of the return water end is lower than a first preset value, the first solenoid valve is opened, and the second solenoid valve and the third solenoid valve are closed; When the temperature of the return water end is greater than or equal to the first preset value, the second solenoid valve is opened, and the first solenoid valve and the third solenoid valve are closed; When the temperature of the evaporator coil is lower than the second preset value, timing is performed. When the accumulated time exceeds the preset period and the evaporator coil temperature is lower than the third preset value, the second solenoid valve and the third solenoid valve are opened and the first solenoid valve is closed.

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