CO2 unit and CO2 heat pump system

Abstract

The utility model relates to the technical field of air conditioners, in particular to a CO2 unit and a CO2 heat pump system. The CO2 heat pump unit aims at solving the problems that the exhaust temperature of a compressor of the CO2 heat pump unit is too high under the low environment temperature, and the heat pump performance is reduced when the return water temperature of an air cooler is high. In order to achieve the purpose, the CO2 unit comprises a compressor, an air cooler, a throttling element, an evaporator and an air preheater. Wherein the evaporator is an air cooling evaporator, the air preheater is arranged on the upstream side of the air inlet direction of the evaporator, a first port of the air preheater is communicated with a heat supply and water return connector of the CO2 unit, and a second port of the air preheater is communicated with a first liquid port of the air cooler. According to the CO2 unit, the problems that the exhaust temperature of the compressor of the CO2 heat pump unit is too high at the low environment temperature and the heat pump performance is reduced when the return water temperature of the air cooler is high can be solved at the same time, the operation stability and the heating capacity in the low-temperature environment are improved, and meanwhile the heating performance in the heating scene is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of air conditioners, and particularly relates to a CO2 unit and a CO2 heat pump system. Background Technique

[0002] As a natural refrigerant, CO2 (carbon dioxide) is very suitable as a refrigerant substitute for air conditioners due to its low cost, zero ODP value (ozone depletion potential value), low GWP value (global warming potential value), non-toxic, non-flammable, and high heat transfer coefficient. Among them, the high heat transfer coefficient of CO2 determines that it is very suitable for the application scenario of heating operation.

[0003] In practical applications, CO2 heat pump units based on heating and hot water supply requirements face two key technical problems: On the one hand, at low ambient temperatures, the evaporation temperature and evaporation pressure of the refrigerant in the evaporator become lower, resulting in a larger compression ratio of the compressor and an increase in the exhaust temperature of the compressor. If the exhaust temperature is too high, the compressor cannot operate normally. In addition, the lower evaporation temperature also leads to a large specific volume of the suction gas of the compressor (i.e., a decrease in density), a decrease in the mass flow rate of the refrigerant circulation, and a small heating capacity of the system, unable to meet the user's needs. On the other hand, in the heating scenario, the temperature difference between the inlet and outlet water temperatures of the heating terminal is small. Usually, the inlet water temperature is about 40°C and the outlet water temperature is about 35°C. At this time, the return water temperature of the gas cooler (i.e., the outlet water temperature of the heating terminal) is relatively high, so the refrigerant temperature at the outlet of the gas cooler is also high. This means that the dryness of the refrigerant at the inlet of the evaporator is relatively large, the heat pump system absorbs less heat from the environment, the heating capacity of the gas cooler decreases, the advantage of the large temperature span of the CO2 refrigerant cannot be exerted, and the performance of the heat pump decreases.

[0004] To solve the above two technical problems, the utility model patent with the publication number CN205807620U discloses a circulating water heating system based on a carbon dioxide heat pump. This patent increases a second heat exchanger to heat the low-temperature carbon dioxide in the carbon dioxide heat pump system by using the waste heat of the circulating return water, so as to improve the evaporation efficiency of carbon dioxide, and then ensure the stable compression efficiency of the compressor. At the same time, it can also reduce the temperature of the circulating return water, make full use of the heat energy, ensure continuous, stable and high-efficiency heat exchange in the first heat exchanger, and make the entire heating system more energy-saving and stable, with high heating efficiency.

[0005] However, through actual tests, the applicant found that the technical solution of the above patent cannot solve the above two technical problems simultaneously. The reasons are as follows: In this technical solution, the cold source for cooling the circulating return water is the cold energy of the refrigerant between the outlet of the evaporator and the suction port of the compressor. Although the temperature of the refrigerant is relatively low in this state, its state is saturated gaseous, and its heat capacity is small. After heat exchange with the circulating return water, the temperature will increase significantly, resulting in too high a temperature of the refrigerant entering the compressor, and the exhaust temperature of the compressor will further increase. That is to say, although this solution alleviates the problem of reduced system performance caused by the high temperature of the circulating return water, another problem will become more prominent due to the further increase in the exhaust temperature of the compressor.

[0006] Correspondingly, a new technical solution is needed in the art to solve the above problems. Utility Model Content

[0007] To solve at least one of the above problems in the prior art, that is, to solve the problems of too high exhaust temperature of the compressor in the CO2 heat pump unit under low ambient temperature and reduced heat pump performance when the return water temperature of the gas cooler is relatively high, the present application provides a CO2 unit, and the CO2 unit includes:

[0008] A compressor;

[0009] A gas cooler, the gas cooler includes a first refrigerant port, a second refrigerant port, a first liquid port and a second liquid port. A first heat exchange channel is formed between the first refrigerant port and the second refrigerant port, and a second heat exchange channel is formed between the first liquid port and the second liquid port. Heat exchange can be carried out between the first heat exchange channel and the second heat exchange channel, wherein the first refrigerant port is communicated with the exhaust port of the compressor, and the second liquid port is communicated with the heating water outlet interface of the CO2 unit;

[0010] A throttling element, the first port of the throttling element is communicated with the second refrigerant port;

[0011] An evaporator, the evaporator is an air-cooled evaporator, and the first port of the evaporator is communicated with the second port of the throttling element, and the second port of the evaporator is communicated with the suction port of the compressor;

[0012] An air preheater, the air preheater is arranged on the upstream side in the air inlet direction of the evaporator, the first port of the air preheater is communicated with the heating return water interface of the CO2 unit, and the second port is communicated with the first liquid port.

[0013] For the CO2 unit of this application, by providing an air preheater and locating it on the upstream side in the air inlet direction of the evaporator, it can simultaneously solve the problems of high compressor discharge temperature in the CO2 heat pump unit at low ambient temperatures and reduced heat pump performance when the return water temperature of the gas cooler is relatively high, improve the operating stability and heating capacity at low ambient temperatures, and at the same time improve the heating performance in heating scenarios.

[0014] Specifically, the first port of the air preheater is connected to the heating return water interface, and the second port is connected to the first liquid port, enabling the utilization of the waste heat of the heating return water. By using the heat exchange between the low-temperature cold air and the air preheater, the return water temperature entering the gas cooler is reduced, thereby making full use of the large temperature glide characteristics of the CO2 refrigerant and improving the heating performance of the CO2 unit. Moreover, after the low-temperature cold air exchanges heat with the air preheater, its temperature rises, which can increase the temperature of the air blown into the evaporator, thereby increasing the evaporation temperature and evaporation pressure, reducing the compression ratio and discharge temperature of the compressor, enabling the system to still stably heat at low ambient temperatures. At the same time, the increase in the evaporation temperature can increase the mass flow rate of the refrigerant circulation and increase the heating capacity at low ambient temperatures.

[0015] Compared with the utility model patent described in the background art, the cold source for precooling the heating return water in this application is low-temperature cold air rather than the refrigerant, so it will not cause the compressor suction temperature to rise, nor will it cause a further increase in the discharge temperature. In addition, after the cold air is preheated and exchanges heat with the evaporator, it can increase the evaporation temperature of the refrigerant rather than the temperature of the refrigerant itself. The increase in the evaporation temperature can reduce the compression ratio of the compressor, and at this time, the discharge temperature of the compressor can also be reduced, thus simultaneously solving the two technical problems in the background art.

[0016] In the preferred technical solution of the above CO2 unit, the air preheater and the evaporator are independently arranged; or

[0017] The air preheater and the evaporator are different pipe sections of the same heat exchanger.

[0018] In the preferred technical solution of the above CO2 unit, the air preheater and the evaporator are arranged side by side.

[0019] In the preferred technical solution of the above CO2 unit, the CO2 unit further includes a first electrically controlled three-way valve and a second electrically controlled three-way valve. The first interface of the first electrically controlled three-way valve is connected to the heating return water interface, the second interface of the first electrically controlled three-way valve is connected to the first port of the air preheater, the first interface of the second electrically controlled three-way valve is connected to the second liquid port, the second interface of the second electrically controlled three-way valve is connected to the heating outlet water interface, and the third port of the second electrically controlled three-way valve is connected to the third port of the first electrically controlled three-way valve.

[0020] By setting the first electrically controlled three-way valve and the second electrically controlled three-way valve, the flow direction of the heating return water and the flow rate in each flow direction can be adjusted by using the two valves, so as to realize the precise adjustment of the temperatures of the first liquid port of the air cooler and the heating water outlet interface.

[0021] In the preferred technical solution of the above CO2 unit, the CO2 unit further includes a first pump body, the liquid return port of the first pump body is communicated with the second liquid port, and the liquid discharge port of the first pump body is communicated with the heating water outlet interface.

[0022] In the preferred technical solution of the above CO2 unit, the CO2 unit further includes a four-way valve, and the four interfaces of the four-way valve are respectively communicated with the exhaust port of the compressor, the first refrigerant interface, the second port of the evaporator and the suction port of the compressor.

[0023] This application also provides a CO2 heat pump system, including:

[0024] A heat cycle component;

[0025] The CO2 unit according to any one of the above technical solutions, and the heat cycle component is respectively communicated with the heating water outlet interface and the heating return water interface.

[0026] The CO2 heat pump system of this application, by setting the above CO2 unit, can simultaneously solve the problems that the exhaust temperature of the compressor of the CO2 heat pump unit is too high at low ambient temperatures and the heat pump performance is reduced when the return water temperature of the air cooler is relatively high, improve the operation stability and heating capacity at low ambient temperatures, and at the same time improve the heating performance in the heating scenario.

[0027] In the preferred technical solution of the above CO2 heat pump system, the heat cycle component includes a hot water tank and a heating pipeline. A heat exchange pipe is arranged in the hot water tank. The first end of the heat exchange pipe and the first end of the heating pipeline are both communicated with the heating water outlet interface, and the second end of the heat exchange pipe and the second end of the heating pipeline are both communicated with the heating return water interface.

[0028] The above setting method can simultaneously realize the combined supply of hot water and heating in the CO2 heat pump system.

[0029] In the preferred technical solution of the above CO2 heat pump system, the heat cycle component further includes a buffer water tank and a third electrically controlled three-way valve. The buffer water tank has a first inlet, a second inlet and a first outlet. The first inlet is communicated with the heating water outlet interface, the first outlet is communicated with the first end of the heating pipeline, the first interface of the third electrically controlled three-way valve is communicated with the second end of the heating pipeline, the second interface of the third electrically controlled three-way valve is communicated with the heating return water interface, and the third interface of the third electrically controlled three-way valve is communicated with the second inlet of the buffer water tank.

[0030] By setting the third electric control three-way valve and the buffer water tank, the buffer water tank can be used to adjust the water temperature entering the heating pipeline, achieving more accurate and stable control.

[0031] In the preferred technical solution of the above CO2 heat pump system, the heat cycle assembly further includes a fourth electric control three-way valve. The first interface of the fourth electric control three-way valve is communicated with the second end of the heat exchange pipe. The second interface of the fourth electric control three-way valve is communicated with the heating return water interface. The third interface of the fourth electric control three-way valve is communicated with the second inlet of the buffer water tank; and / or

[0032] The heat cycle assembly further includes a second pump body. The liquid discharge port of the second pump body is communicated with the second inlet of the buffer water tank.

[0033] By setting the fourth electric control three-way valve, the water discharged from the heat exchange pipe can be used to enter the buffer water tank to adjust the water temperature in the buffer water tank, realizing the hierarchical utilization of heat and improving the system energy efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The present application will be described below with reference to the accompanying drawings. In the drawings:

[0035] Figure 1 is the system diagram of the CO2 heat pump system of the present application.

[0036] List of Reference Numerals

[0037] 10. CO2 unit; 11. Compressor; 12. Air cooler; 13. Throttling element; 14. Evaporator; 141. Fan; 15. Air preheater; 161. First electric control three-way valve; 162. Second electric control three-way valve; 17. First pump body; 18. Four-way valve; 191. Heating return water interface; 192. Heating outlet water interface;

[0038] 20. Heat cycle assembly; 21. Hot water supply tank; 22. Heating pipeline; 23. Heat exchange pipe; 24. Buffer water tank; 251. Third electric control three-way valve; 252. Fourth electric control three-way valve; 26. Second pump body; 271. First on-off valve; 272. Second on-off valve. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0039] The preferred embodiments of the present application will be described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are only used to explain the technical principle of the present application and are not intended to limit the protection scope of the present application.

[0040] It should be noted that in the description of the present application, the terms indicating the direction or positional relationship such as "upper", "lower", "left", "right", "inner", "outer", etc. are based on the direction or positional relationship shown in the drawings. This is only for the convenience of description and does not indicate or imply that the device or component must have a specific orientation, be constructed and operated in a specific orientation, so it should not be construed as a limitation to the present application. In addition, the terms "first", "second", "third", "fourth" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0041] In addition, it should also be noted that in the description of the present application, unless otherwise clearly specified and defined, the terms "installed", "connected", "connected to" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those skilled in the art, the specific meanings of the above terms in the present application can be understood according to specific situations.

[0042] First, refer to Figure 1 to briefly introduce the CO2 unit of the present application. Figure 1 In

[0043] As shown in Figure 1 , in order to solve the problems that the exhaust temperature of the compressor of the CO2 heat pump unit is too high at low ambient temperatures and the heat pump performance decreases when the return water temperature of the air cooler is relatively high, the CO2 unit 10 of the present application includes a compressor 11, an air cooler 12, a throttling element 13, an evaporator 14, and an air preheater 15. The air cooler 12 includes a first refrigerant port ( Figure 1 the lower left port in Figure 1 ), a second refrigerant port ( Figure 1 the upper left port in Figure 1 ), a first liquid port ( Figure 1 the upper right port in Figure 1 ), and a second liquid port ( Figure 1 the lower right port in Figure 1 ). A first heat exchange channel is formed between the first refrigerant port and the second refrigerant port, a second heat exchange channel is formed between the first liquid port and the second liquid port, and heat exchange can be carried out between the first heat exchange channel and the second heat exchange channel. Among them, the first refrigerant port is communicated with the exhaust port of the compressor 11, and the second liquid port is communicated with the heating water outlet interface 192 of the CO2 unit 10. The first port ( Figure 1 the right port in Figure 1 of the throttling element 13 is communicated with the second refrigerant port, the evaporator 14 is an air-cooled evaporator 14, and the first port ( Figure 1 the upper side port in Figure 1 of the evaporator 14 is communicated with the second port ( Figure 1 the left port in Figure 1The lower middle side port) is communicated with the suction port of the compressor 11. Among them, the throttling element 13 can be an electronic expansion valve or a capillary tube, etc.

[0044] The air preheater 15 is arranged on the upstream side in the air inlet direction of the evaporator 14. The first port of the air preheater 15 ( Figure 1 The upper middle side port) is communicated with the heat supply return water interface 191 of the CO2 unit 10, and the second port ( Figure 1 The lower middle side port) is communicated with the first liquid port.

[0045] Among them, the heat supply outlet water interface 192 and the heat supply return water interface 191 described in this application refer to the interfaces where the CO2 unit 10 is connected to the heat circulation component 20. Usually, in actual products, the heat supply outlet water interface 192 and the heat supply return water interface 191 are arranged on the outer shell of the device. By connecting the total water inlet pipe and the total water outlet pipe in the pipeline of the heat circulation component 20 to the heat supply outlet water interface 192 and the heat supply return water interface 191 respectively, the construction of the whole system is realized.

[0046] In the case of the above setting method, when the CO2 unit 10 operates, on the one hand, the CO2 refrigerant discharged by the compressor 11 sequentially passes through the gas cooler 12, the throttling element 13 and the evaporator 14 and returns to the compressor 11, forming a refrigerant cycle. The CO2 refrigerant releases heat when passing through the gas cooler 12 and absorbs heat when passing through the evaporator 14. On the other hand, the heat-conducting medium in the heat circulation component 20 (such as water, ethylene glycol or a mixture of the two, etc.) exchanges heat with the refrigerant in the gas cooler 12 and thus the temperature rises. The heat-conducting medium after heat exchange is discharged from the CO2 unit 10 through the heat supply outlet water interface 192 and enters the heat circulation component 20 to provide heat for users (such as providing domestic hot water, heating water, etc.) and the temperature drops. The heat-conducting medium with the temperature dropped enters the CO2 unit 10 through the heat supply return water interface 191, and when passing through the air preheater 15, exchanges heat with the outdoor air and the temperature further drops. Finally, the heat-conducting medium with the further dropped temperature enters the gas cooler 12 to participate in the heat exchange again. And the cold air with the temperature rising after exchanging heat with the air preheater 15 continues to exchange heat with the evaporator 14.

[0047] For the CO2 unit 10 of this application, by arranging the air preheater 15 and being located on the upstream side in the air inlet direction of the evaporator 14, the problems that the exhaust temperature of the compressor 11 is too high in the CO2 heat pump unit 10 at low ambient temperature and the heat pump performance is reduced when the return water temperature of the gas cooler 12 is relatively high can be solved simultaneously, the operation stability and the heat output at low temperature environment are improved, and the heating performance in the heating scenario is improved at the same time.

[0048] Specifically, the first port of the air preheater 15 is communicated with the heating return water interface 191, and the second port is communicated with the first liquid port, which can realize the waste heat utilization of the heating return water. By using the heat exchange between the low-temperature cold air and the air preheater 15, the temperature of the return water entering the gas cooler 12 can be reduced, so as to make full use of the large temperature difference and slip characteristics of the CO2 refrigerant, and improve the heating performance of the CO2 unit 10. Moreover, the temperature of the low-temperature cold air increases after exchanging heat with the air preheater 15, which can increase the temperature of the air blown into the evaporator 14, thereby increasing the evaporation temperature and evaporation pressure, reducing the compression ratio and exhaust temperature of the compressor 11, and enabling the system to still stably heat at low ambient temperatures. At the same time, the increase in the evaporation temperature can increase the mass flow rate of the refrigerant circulation and increase the heating capacity at low ambient temperatures.

[0049] Compared with the utility model patent in the background art, the cold source for precooling the heating return water in this application is low-temperature cold air rather than the refrigerant. Therefore, it will not cause the suction temperature of the compressor 11 to increase, nor will it cause a further increase in the exhaust temperature. In addition, the cold air is preheated and then exchanges heat with the evaporator 14, which can increase the evaporation temperature of the refrigerant rather than the temperature of the refrigerant itself. The increase in the evaporation temperature can reduce the compression ratio of the compressor 11, and at this time, the exhaust temperature of the compressor 11 can also be reduced, thus solving the two technical problems in the background art simultaneously.

[0050] Next, further refer to Figure 1 , and introduce a possible implementation manner of the CO2 unit 10 of this application.

[0051] As Figure 1 shown, in a specific implementation manner, the CO2 unit 10 includes a compressor 11, a four-way valve 18, a gas cooler 12, a throttling element 13, an evaporator 14, an air preheater 15, a first pump body 17, a first electrically controlled three-way valve 161, and a second electrically controlled three-way valve 162.

[0052] The four-way valve 18 has four interfaces a, b, c, and d. The gas cooler 12 is a liquid-cooled heat exchanger, which includes a first refrigerant port, a second refrigerant port, a first liquid port, and a second liquid port. A first heat exchange channel is formed between the first refrigerant port and the second refrigerant port, and a second heat exchange channel is formed between the first liquid port and the second liquid port. Heat exchange can be carried out between the first heat exchange channel and the second heat exchange channel. The evaporator 14 is an air-cooled evaporator 14, such as a finned heat exchanger, etc., and is configured with a fan 141, and the fan 141 is arranged on the air outlet side of the evaporator 14.

[0053] Among them, the exhaust port of the compressor 11 is communicated with the interface a of the four-way valve 18, the interface b of the four-way valve 18 is communicated with the first refrigerant port of the air cooler 12, the second refrigerant port of the air cooler 12 is communicated with the first port of the throttling element 13, the second port of the throttling element 13 is communicated with the first port of the evaporator 14, the second port of the evaporator 14 is communicated with the interface c of the four-way valve 18, and the interface d of the four-way valve 18 is communicated with the suction port of the compressor 11. In this way, a refrigerant cycle is formed among the compressor 11, the four-way valve 18, the air cooler 12, the throttling element 13 and the evaporator 14. The working principle of this refrigerant cycle is common knowledge in the art and will not be elaborated in this application.

[0054] The air preheater 15 is an air-cooled heat exchanger, which is independently arranged from the evaporator 14 and is arranged side by side on the air inlet side of the evaporator 14. When the fan 141 is started, outdoor air sequentially passes through the air preheater 15 and the evaporator 14 and exchanges heat with the air preheater 15 and the evaporator 14 successively.

[0055] The first interface ( Figure 1 right interface) of the first electric control three-way valve 161 is communicated with the heating return water interface 191, and the second interface ( Figure 1 left interface) of the first electric control three-way valve 161 is communicated with the first port of the air preheater 15. The first interface ( Figure 1 left interface) of the second electric control three-way valve 162 is communicated with the second liquid port of the air cooler 12, and the second interface ( Figure 1 right interface) of the second electric control three-way valve 162 is communicated with the heating outlet water interface 192. The third port ( Figure 1 upper interface) of the second electric control three-way valve 162 is communicated with the third port ( Figure 1 lower interface) of the first electric control three-way valve 161. Among them, the first electric control three-way valve 161 and the second electric control three-way valve 162 can be electromagnetic control valves or electric control valves, and both the first electric control three-way valve 161 and the second electric control three-way valve 162 can achieve flow splitting control. Taking the first electric control three-way valve 161 as an example, by controlling the valve core of the first electric control three-way valve 161, the separate communication between its first interface and the second interface can be achieved, the separate communication between the first interface and the third interface can also be achieved, or the first interface can be simultaneously communicated with the second interface and the third interface, and the outlet flow rates of the second interface and the third interface can be adjusted by changing the position of the valve core.

[0056] The first pump body 17 is a water pump. The liquid return port of the water pump is communicated with the second liquid port, and the liquid discharge port of the first pump body 17 is communicated with the first interface of the second electric control three-way valve 162.

[0057] By setting the four-way valve 18, multi-mode operation of the CO2 unit 10 can be achieved. By setting the air preheater 15 and the evaporator 14 independently of each other, it is beneficial to reduce the design and installation difficulty. By arranging the air preheater 15 and the evaporator 14 side by side, it is beneficial to improve the heat exchange effect of the air flow. By setting the first electric control three-way valve 161 and the second electric control three-way valve 162, the flow direction of the heating return water and the flow rate in each flow direction can be adjusted by the two, so as to achieve precise temperature regulation of the first liquid port of the air cooler 12 and the heating water outlet interface 192.

[0058] The following combines Figure 1 , and introduces the CO2 heat pump system of the present application.

[0059] As Figure 1 shown, the CO2 heat pump system of the present application includes a heat cycle component 20 and the CO2 unit 10 in the above embodiment, wherein the heat cycle component 20 is respectively communicated with the heating water outlet interface 192 and the heating water return interface 191.

[0060] In a specific implementation manner, the heat cycle component 20 includes a hot water supply tank 21, a buffer tank 24, a heating pipeline 22, a second pump body 26, a third electric control three-way valve 251, and a fourth electric control three-way valve 252.

[0061] The hot water supply tank 21 is used to provide domestic water for users, and a heat exchange tube 23 is arranged therein. The first end ( Figure 1 the upper end in Figure 1 ) of the heat exchange tube 23 is communicated with the heating water outlet interface 192 through a first on-off valve 271, and the second end ( Figure 1 the lower end in Figure 1 ) of the heat exchange tube 23 is communicated with the first interface ( Figure 1 the right interface in Figure 1 ) of the fourth electric control three-way valve 252. The second interface ( Figure 1 the lower end in Figure 1 ) of the heating pipeline 22 is communicated with the first interface ( Figure 1 the right interface in Figure 1The left interface on the middle) is connected to the heating return water interface 191. Among them, both the first on-off valve 271 and the second on-off valve 272 adopt solenoid valves. The third electrically controlled three-way valve 251 and the fourth electrically controlled three-way valve 252 are similar to the above-mentioned first electrically controlled three-way valve 161 and the second electrically controlled three-way valve 162, and can both achieve flow splitting control, which will not be elaborated here.

[0062] Furthermore, the third interface of the third electrically controlled three-way valve 251 and the third interface of the fourth electrically controlled three-way valve 252 are jointly connected to the liquid return port of the second pump body 26, and the liquid discharge port of the second pump body 26 is connected to the second inlet of the buffer water tank 24.

[0063] In the CO2 heat pump system of the present application, by setting the above-mentioned CO2 unit 10, the problems that the exhaust temperature of the compressor 11 of the CO2 heat pump unit 10 is too high at low ambient temperatures and the heat pump performance decreases when the return water temperature of the air cooler 12 is relatively high can be solved simultaneously, improving the operating stability and heating capacity at low ambient temperatures, and at the same time improving the heating performance in the heating scenario. The hot water circulation component 20 includes both a hot water tank 21 and a heating pipeline 22, and can simultaneously achieve the combined supply of hot water and heating of the CO2 heat pump system. By setting the third electrically controlled three-way valve 251 and the buffer water tank 24, the buffer water tank 24 can be used to adjust the water temperature entering the heating pipeline 22 to achieve more accurate and stable control. By setting the fourth electrically controlled three-way valve 252, the water discharged from the heat exchange pipe 23 can enter the buffer water tank 24 to adjust the water temperature in the buffer water tank 24, realizing the hierarchical utilization of heat and improving the energy efficiency of the system.

[0064] The following combines Figure 1 to introduce the working principle of the CO2 heat pump system of the present application.

[0065] As Figure 1 shown, in a specific working process, the compressor 11, the fan 141, the first pump body 17 and the second pump body 26 are started and operated, the first on-off valve 271 and the second on-off valve 272 are opened, and the valve cores of the first electrically controlled three-way valve 161, the second electrically controlled three-way valve 162, the third electrically controlled three-way valve 251 and the fourth electrically controlled three-way valve 252 all move to the flow splitting position. At this time, the system conducts two independent cycles: the refrigerant cycle and the medium cycle.

[0066] In the refrigerant cycle, the CO2 refrigerant discharged by the compressor 11 sequentially passes through the four-way valve 18, the air cooler 12, the throttling element 13, the evaporator 14 and the four-way valve 18 and returns to the compressor 11. The CO2 refrigerant releases heat when passing through the air cooler 12 and absorbs heat when passing through the evaporator 14.

[0067] In the medium circulation, the heat-conducting medium exchanges heat with the refrigerant in the air cooler 12 and thus its temperature rises. After heat exchange, the heat-conducting medium enters the second electronically controlled three-way valve 162 under the pumping of the first pump body 17. After being mixed and temperature-adjusted with the heat-conducting medium flowing back from the first electronically controlled three-way valve 161, it is discharged from the CO2 unit 10 through the heating water outlet interface 192 and enters the thermal cycle assembly 20. Among the heat-conducting medium entering the thermal cycle assembly 20, a part passes through the first on-off valve 271 and enters the hot water storage tank 21 to exchange heat with the water in the hot water storage tank 21 and its temperature drops. The heat-conducting medium with the reduced temperature flows to the fourth electronically controlled three-way valve 252 and is divided into two branches after the fourth electronically controlled three-way valve 252. One branch flows back to the CO2 unit 10 through the heating return water interface 191, and the other branch enters the buffer tank 24 through the second pump body 26. Among the heat-conducting medium entering the thermal cycle assembly 20, another part passes through the second on-off valve 272 and enters the buffer tank 24. After being mixed and temperature-adjusted with the low-temperature heat-conducting medium pumped into the buffer tank 24 by the second pump body 26, it enters the heating pipeline 22 to exchange heat with the indoor air and its temperature drops. The heat-conducting medium with the reduced temperature enters the third electronically controlled three-way valve 251 and is divided into two branches after the third electronically controlled three-way valve 251. One branch flows back to the CO2 unit 10 through the heating return water interface 191, and the other branch enters the buffer tank 24 through the second pump body 26. The heat-conducting medium entering the CO2 unit 10 through the heating return water interface 191 is also divided into two branches. The heat-conducting medium in one branch flows to the second electronically controlled three-way valve 162, is mixed and temperature-adjusted with the heat-conducting medium from the air cooler 12, and then is discharged from the CO2 unit 10. The heat-conducting medium in the other branch enters the air preheater 15. Under the action of the fan 141, the outdoor cold air first passes through the air preheater 15 to exchange heat with the heat-conducting medium. As a result, the temperature of the heat-conducting medium further drops, while the temperature of the exchanged air rises. The heat-conducting medium with the further reduced temperature enters the air cooler 12 to participate in heat exchange again. At this time, the temperature difference between the first liquid port and the second liquid port of the air cooler 12 is relatively large, and the large temperature span advantage of the CO2 refrigerant can be fully utilized to improve the heating performance of the system. And the cold air with the increased temperature after exchanging heat with the air preheater 15 continues to exchange heat with the evaporator 14, which can increase the evaporation temperature and evaporation pressure, reduce the compression ratio and exhaust temperature of the compressor 11, enable the system to still stably heat at low ambient temperature. At the same time, the increase in the evaporation temperature can increase the mass flow rate of the refrigerant cycle and increase the heating capacity at low ambient temperature.

[0068] Of course, the above working principle only introduces a possible working process of the CO2 heat pump system. Those skilled in the art can adjust the working states of various components therein so that this application is applicable to more specific application scenarios. For example, those skilled in the art can adjust the opening and closing of the first on-off valve 271 and the second on-off valve 272 so that the CO2 heat pump system only operates in one of the hot water heating and heating modes. Again, those skilled in the art can also adjust the spool positions of the first electronically controlled three-way valve 161, the second electronically controlled three-way valve 162, the third electronically controlled three-way valve 251, and the fourth electronically controlled three-way valve 252 to adjust the flow direction of the heat transfer medium, etc.

[0069] It should also be noted that the above embodiments of the CO2 unit 10 and the CO2 heat pump system are only used to illustrate the principle of this application and are not intended to limit the protection scope of this application. Without departing from the principle of this application, those skilled in the art can adjust the above setting methods so that this application can be applicable to more specific application scenarios.

[0070] For example, in an alternative embodiment, although the above air preheater 15 and evaporator 14 are introduced by taking the combination and independent setting of each other as an example, the setting method between the two is not unique. On the premise of ensuring that the air preheater 15 is arranged on the upstream side of the evaporator 14, those skilled in the art can adjust the setting method of the two. For example, the air preheater 15 and the evaporator 14 can be set as different pipe sections of the same heat exchanger. For example, the first row of pipes on the windward side of the three-row finned heat exchanger is used as the air preheater 15, and the remaining two rows of pipes are used as the evaporator 14.

[0071] Again, in another alternative embodiment, the fact that the air preheater 15 and the evaporator 14 are arranged side by side with each other is only one possible embodiment. In other embodiments, those skilled in the art can adjust this setting method, such as arranging the air preheater 15 and the evaporator 14 in the same air duct and spacing them apart by a certain distance.

[0072] Again, in another alternative embodiment, the first electronically controlled three-way valve 161, the second electronically controlled three-way valve 162, the third electronically controlled three-way valve 251, and the fourth electronically controlled three-way valve 252 can all be omitted, or only one or several of them can be set, or the above one or several can be replaced with two-way valves. This adjustment only has a certain impact on the control accuracy of the CO2 heat pump system, but does not deviate from the principle of this application.

[0073] For another example, in another alternative embodiment, although in the above embodiment, the first electric three-way valve 161 and the second electric three-way valve 162 are provided in the CO2 unit 10, and the third electric three-way valve 251 and the fourth electric three-way valve 252 are provided in the heat cycle assembly 20 as an example for introduction, the installation positions of the first electric three-way valve 161, the second electric three-way valve 162, the third electric three-way valve 251 and the fourth electric three-way valve 252 are not fixed. Those skilled in the art can adjust their installation positions. For example, all four electric three-way valves can be provided in the CO2 unit 10 at the same time, or can be provided in the heat cycle assembly 20 at the same time, or the four electric three-way valves can be arbitrarily distributed between the CO2 unit 10 and the heat cycle assembly 20.

[0074] For another example, in another alternative embodiment, although the above embodiment is introduced by taking the CO2 unit 10 provided with the first pump body 17 and the four-way valve 18 as an example, the installation of the first pump body 17 and the four-way valve 18 is not necessary. Those skilled in the art can selectively omit one or both of them.

[0075] For another example, in another alternative embodiment, the heat cycle assembly 20 is introduced by taking the combination of the hot water supply tank 21, the heating pipeline 22 and the buffer tank 24 as an example. However, the specific composition mode of the heat cycle assembly 20 is not fixed. Those skilled in the art can make a choice based on the specific application scenario. For example, the heat cycle assembly 20 can be provided with only the hot water supply tank 21 or the heating pipeline 22, or the hot water supply tank 21 and the heating pipeline 22 can be provided at the same time but the buffer tank 24 can be omitted. Or, the hot water supply tank 21 and the heating pipeline 22 can also be connected in series, and the hot water supply tank 21 can be arranged on the upstream side of the heating pipeline 22, etc.

[0076] For another example, in another alternative embodiment, although the above embodiment is introduced by taking the first on-off valve 271 and the second on-off valve 272 as an example, the installation of the first on-off valve 271 and the second on-off valve 272 is not necessary. In some embodiments, either one or both of them can also be omitted. In addition, in addition to solenoid valves, the first on-off valve 271 and the second on-off valve 272 can also adopt other forms of electric control valves or even manual valves.

[0077] For another example, in another alternative embodiment, the installation of the second pump body 26 is not necessary. Those skilled in the art can choose whether to install the second pump body 26 based on the specific application scenario.

[0078] Of course, the above alternative embodiments can be used in cross combination with each other, and between the alternative embodiments and the preferred embodiments, so as to combine new embodiments to be applicable to more specific application scenarios.

[0079] Those skilled in the art will understand that although some of the embodiments described herein include certain features included in other embodiments rather than other features, the combination of features of different embodiments means that it is within the scope of this application and forms different embodiments. For example, in the claims of this application, any one of the claimed embodiments can be used in any combination.

[0080] So far, the technical solutions of this application have been described in conjunction with the preferred embodiments shown in the drawings. However, it is easy for those skilled in the art to understand that the protection scope of this application is obviously not limited to these specific embodiments. Without departing from the principle of this application, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the protection scope of this application.

Claims

1. A CO2 unit, characterized in that: The CO2 unit comprises: compressor; An air cooler, the air cooler comprising a first refrigerant port, a second refrigerant port, a first liquid port and a second liquid port, a first heat exchange channel is formed between the first refrigerant port and the second refrigerant port, a second heat exchange channel is formed between the first liquid port and the second liquid port, heat exchange can be performed between the first heat exchange channel and the second heat exchange channel, wherein the first refrigerant port is communicated with the exhaust port of the compressor, and the second liquid port is communicated with the heating water outlet interface of the CO2 unit; A throttling element, wherein a first port of the throttling element is in communication with the second refrigerant port; An evaporator, wherein the evaporator is an air-cooled evaporator, and a first port of the evaporator is in communication with a second port of the throttling element, and a second port of the evaporator is in communication with a suction port of the compressor; An air preheater is arranged on the upstream side of the evaporator in the air inlet direction, a first port of the air preheater is connected to the heat supply return water interface of the CO2 unit, and a second port is connected to the first liquid port.

2. The CO2 unit according to claim 1, characterized in that: The air preheater and the evaporator are arranged independently of each other; or The air preheater and the evaporator are different pipe sections of the same heat exchanger.

3. The CO2 unit according to claim 1, characterized in that: The air preheater and the evaporator are arranged side by side with each other.

4. The CO2 unit according to claim 1, characterized in that: The CO2 unit also includes a first electrically controlled three-way valve and a second electrically controlled three-way valve, wherein the first interface of the first electrically controlled three-way valve is connected to the heating return water interface, the second interface of the first electrically controlled three-way valve is connected to the first port of the air preheater, the first interface of the second electrically controlled three-way valve is connected to the second liquid port, the second interface of the second electrically controlled three-way valve is connected to the heating water outlet interface, and the third port of the second electrically controlled three-way valve is connected to the third port of the first electrically controlled three-way valve.

5. The CO2 unit according to claim 1, characterized in that: The CO2 unit further comprises a first pump body, a liquid return port of the first pump body is in communication with the second liquid port, and a liquid discharge port of the first pump body is in communication with the heating water outlet interface.

6. The CO2 unit according to claim 1, characterized in that: The CO2 unit also includes a four-way valve, and four interfaces of the four-way valve are respectively connected to the exhaust port of the compressor, the first refrigerant port, the second port of the evaporator and the suction port of the compressor.

7. A CO2 heat pump system, characterized in that: include: Thermal cycle components; The CO2 unit according to any one of claims 1 to 6, wherein the heat cycle component is respectively connected to the heating water outlet interface and the heating water return interface.

8. The CO2 heat pump system according to claim 7, characterized in that: The thermal circulation component includes a hot water tank and a heating pipeline. A heat exchange tube is arranged in the hot water tank. The first end of the heat exchange tube and the first end of the heating pipeline are both connected to the heating water outlet interface, and the second end of the heat exchange tube and the second end of the heating pipeline are both connected to the heating water return interface.

9. The CO2 heat pump system according to claim 8, characterized in that: The thermal circulation component also includes a buffer water tank and a third electrically controlled three-way valve, the buffer water tank having a first inlet, a second inlet and a first outlet, the first inlet being connected to the heating water outlet interface, the first outlet being connected to the first end of the heating pipeline, the first interface of the third electrically controlled three-way valve being connected to the second end of the heating pipeline, the second interface of the third electrically controlled three-way valve being connected to the heating return water interface, and the third interface of the third electrically controlled three-way valve being connected to the second inlet of the buffer water tank.

10. The CO2 heat pump system according to claim 9, characterized in that: The thermal cycle component further includes a fourth electrically controlled three-way valve, a first interface of the fourth electrically controlled three-way valve being connected to the second end of the heat exchange tube, a second interface of the fourth electrically controlled three-way valve being connected to the heating return interface, and a third interface of the fourth electrically controlled three-way valve being connected to the second inlet of the buffer water tank; and / or The thermal cycle assembly further comprises a second pump body, wherein a discharge port of the second pump body is in communication with a second inlet port of the buffer water tank.

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