CN110579033B - Transcritical CO based on double four-way reversing valve2Triple co-generation comfort system - Google Patents

Abstract

The invention discloses a trans-critical CO ₂ triple supply comfort system based on a double four-way reversing valve. The invention consists of a non-azeotropic working medium mechanical supercooling auxiliary system and a transcritical CO ₂ refrigerating and heating integrated system, and also comprises two four-way reversing valves, a controller, a buffer water tank, a domestic hot water tank, an indoor fan coil, a floor heating coil, an expansion water tank and a plurality of control valves. By using two four-way reversing valves to respectively switch and control the auxiliary system and the trans-critical CO ₂ system, the supercooling of CO ₂ fluid in winter and summer is respectively met by one set of equipment, the utilization rate of the equipment is improved, and the energy efficiency of the system is obviously improved. And meanwhile, heat at the side of a heat exchanger in the system operation is recovered and used for heating domestic hot water, triple supply of an air conditioner, a heat pump and a water heater is realized, the number and the volume of equipment are reduced, and the flexibility of energy utilization is improved.

Description

Transcritical CO2 trigeneration comfort system based on double four-way reversing valve

Technical Field

The present invention relates to the technical field of refrigeration heat pumps, and in particular to a transcritical _CO2 trigeneration comfort system based on a double four-way reversing valve and a control method thereof.

Background technique

As people's living standards improve, the requirements for cold and hot comfort are getting higher and higher, and air conditioning and heating are becoming more and more popular. In order to meet this demand, a large number of air conditioners and heat pump products with high GWP have emerged. As environmental problems such as global warming and ozone layer depletion become increasingly prominent, the Kigali Amendment to the Montreal Protocol reached in October 2016 proposed to focus on reducing HFC compounds. At the same time, in order to control the more serious haze phenomenon in northern regions in winter, the government proposed measures such as coal-to-electricity to solve the problem of winter heating in the north. Therefore, in order to replace CFCs, HCFCs, HFCs and other working fluids that have a high GWP and damage the ozone layer and produce a greenhouse effect, finding new friendly natural working fluids has become a research focus in the field of heat pump refrigeration and air conditioning.

_CO2 has attracted widespread attention due to its advantages such as being non-toxic, non-flammable, safe and environmentally friendly. However, _CO2 has a low critical temperature and high critical pressure, resulting in large throttling losses and low energy efficiency during use. If a transcritical _CO2 system is used to meet the needs of cooling and heating, the _CO2 at the outlet of the gas cooler can be supercooled, which can be achieved through internal heat exchangers, mechanical supercooling, thermoelectric supercooling, etc. If mechanical supercooling is used, as the degree of supercooling increases, the throttling loss decreases. While ensuring the safety and environmental protection of the system, the cycle refrigeration capacity increases, the cycle COP is improved, and the compressor exhaust pressure is reduced, the service life of the compressor is extended, and efficient cooling and heating of the system is achieved. However, the optimal degree of mechanical supercooling is high, resulting in a large temperature difference between the refrigerant and the _CO2 fluid in the cooling evaporator, resulting in a large irreversible loss of heat exchange, affecting the efficiency of the system.

Most of the heating and cooling equipment currently on the market cannot meet the needs of heating, cooling and domestic hot water supply at the same time. If heating, cooling or domestic hot water are produced separately, it will not only cause energy waste, but also have numerous equipment and take up space, and there will be heat waste. The energy consumption in the refrigeration industry increases year by year, so considering the recovery and utilization of heat is also a top priority for the rational operation of the system.

Summary of the invention

In order to solve the above-mentioned problems, the purpose of the present invention is to provide a transcritical _CO2 trigeneration comfort system based on a double four-way reversing valve.

The system uses natural working fluid _CO2 and non-azeotropic working fluids with large temperature glide and low GWP, such as R1234ze(E)/CO2, R1234ze(Z)/CO2, R1234yf/CO2, R1234ze(E)/R41, R1234ze(Z)/R41, R1234yf/R41, R1234ze(E)/R32, R1234ze(Z)/R32, R1234yf/R32 and other non-azeotropic mixed working fluids. The CO ₂ at the outlet of the gas cooler in the transcritical CO ₂ system is supercooled by a non-azeotropic working fluid mechanical subcooling auxiliary system. Two four-way reversing valves are used to switch and control the auxiliary system and the transcritical CO ₂ system respectively, so that a set of equipment can meet the requirements of supercooling the CO ₂ fluid in winter and summer. Based on the concept of the Lorenz cycle, the temperature glide during the phase change of the non-azeotropic refrigerant is used, that is, the phase change process in the condenser and the cooling evaporator has a high temperature glide, which meets the requirements of reducing throttling losses and improving the overall energy efficiency of the system. The heat generated on the heat exchanger side during the operation of the system is recovered and used to heat domestic hot water and stored in the domestic hot water tank, realizing the trigeneration of air conditioning-heat pump-water heater, the equipment works efficiently, and the flexibility of energy utilization is improved. The system can be used in civil and commercial buildings that require both cooling and heating. Therefore, it provides a better system for buildings such as family villas, rural buildings, shopping malls and supermarkets, which can simultaneously achieve winter heating, summer cooling and provide hot water required for daily life.

The technical solution adopted by the present invention is:

A transcritical _CO2 trigeneration comfort system based on a double four-way reversing valve is mainly composed of a non-azeotropic working medium mechanical subcooling auxiliary system and a transcritical _CO2 refrigeration and heating integrated system. The non-azeotropic working medium mechanical subcooling auxiliary system consists of a compressor, a condenser, a throttle valve and a cooling evaporator. The transcritical _CO2 refrigeration and heating integrated system consists of a compressor, a gas cooler, an evaporator, a throttle valve and a cooling evaporator. Compressor 2 is connected to cooling evaporator and three-way reversing valve a respectively, three-way reversing valve a is connected to condenser and fin tube heat exchanger 2 respectively, three-way reversing valve b is connected to throttle valve 1, condenser and fin tube heat exchanger 2 respectively, throttle valve 1 is connected to cooling evaporator, cooling evaporator, throttle valve 2 and four-way reversing valve A are connected in sequence, three-way reversing valve c is connected to fin tube evaporator 1, gas cooler 2 and four-way reversing valve A respectively, three-way reversing valve E is connected to domestic hot water tank, gas cooler 1 and gas cooler 2 respectively, three-way reversing valve D is connected to water inlet pipe, domestic hot water tank and gas cooler 1 respectively. The live hot water tank and three-way reversing valve F, the three-way reversing valve F are respectively connected to gas cooler 1 and gas cooler 2, compressor 1 is connected to four-way reversing valve B, the four-way reversing valve B is respectively connected to gas cooler 1 and three-way reversing valve d, the three-way reversing valve C is respectively connected to the indoor fan coil, the condenser and the three-way reversing valve B, the three-way reversing valve B is respectively connected to the floor heating coil (or radiator) and the gas cooler 1, the three-way reversing valve A is respectively connected to the cache water tank, the indoor fan coil and the floor heating coil (or radiator), and the expansion water tank is respectively connected to the three-way reversing valve B and the gas cooler 1.

The cooling evaporator serves as both the evaporator of the non-azeotropic working medium mechanical subcooling auxiliary system and the cooler in the transcritical _CO2 system. The domestic hot water tank can be electrically heated. When the hot water consumption is large but the heat supply of the heat pump is insufficient, it can be compensated by electric heating.

(I) Winter operation process

Heating process: The four-way reversing valve in the transcritical _CO2 system is switched to the winter operation state. When the three-way reversing valve of the indoor fan coil is switched to the closed state, and the three-way reversing valve of the floor heating coil (or radiator) is switched to the open state, the water flows through the gas cooler in the transcritical _CO2 system and is heated, and flows into the floor heating coil (or radiator) for water circulation to provide heat to the indoor environment; when the three-way reversing valve of the indoor fan coil is switched to the open state, and the three-way reversing valve of the floor heating coil (or heat exchanger) is switched to the closed state, the water flows through the gas cooler in the transcritical _CO2 system and is heated, and flows into the indoor fan coil through the buffer water tank for heat exchange to provide heat to the indoor environment. After that, it passes through the three-way reversing valve and returns to the gas cooler for heating again, completing the indoor heating. The expansion water tank is used to store water, set pressure, and release gas.

Defrosting process: In winter conditions, when the indoor fan coil is used to provide heat for the indoor environment, the indoor heat exchanger is a gas cooler, and the outdoor heat exchanger is a finned tube evaporator. This evaporator absorbs heat from the external environment and blows out cold air, resulting in frost on the external heat transfer surface of the evaporator. When the frost reaches a certain degree, the four-way reversing valve switches to the summer condition, and the outdoor heat exchanger becomes a gas cooler, which releases heat and defrosts. At this time, the water flowing out of the indoor fan coil flows through the three-way reversing valve into the evaporator in the transcritical _CO2 system to exchange heat with the _CO2 fluid to cool it, and the other flows into the condenser in the mechanical subcooling auxiliary system to exchange heat with the non-azeotropic working fluid to heat it. The two streams of water then flow into the cache water tank together for cold and hot mixing. The use of the cache water tank can significantly solve the problem of poor indoor thermal comfort during the defrosting process when the operating conditions are switched, and reduce the discomfort of people indoors caused by changes in ambient temperature. After defrosting, the four-way reversing valve switches to the winter condition to enter the heating state. The above completes the defrosting of the heat exchanger.

Domestic hot water supply process: The tap water flowing into the system is divided into two streams, one stream flows into the gas cooler in the transcritical _CO2 system for heating, and the other stream flows into the condenser of the non-azeotropic working fluid mechanical subcooling auxiliary system for heating. The heated hot water is stored in the domestic hot water tank for domestic hot water for bathing, washing hands, washing vegetables, etc. The cooling evaporator of the auxiliary system subcools the _CO2 fluid in the transcritical _CO2 system, so that the _CO2 fluid obtains a large degree of subcooling.

The above realizes winter working conditions, completes the heating of the indoor environment, supercooling of the _CO2 fluid, defrosting of the outdoor unit and heating of domestic water.

(II) Summer operation process

Cooling process: The four-way reversing valve in the transcritical _CO2 system switches to the summer operation state. The cooling water flows through the evaporator side of the transcritical _CO2 system and is cooled, and flows into the indoor fan coil for heat exchange, providing cooling to the indoor environment. After the cooling water lowers the indoor temperature, it passes through the three-way reversing valve and returns to the evaporator for cooling again, completing the indoor cooling. The expansion water tank is used to store water, maintain pressure, and release air.

Domestic hot water supply process: The tap water flowing into the system is divided into two streams, one stream flows into the gas cooler in the transcritical _CO2 system for heating, and the other stream flows into the condenser of the non-azeotropic working fluid mechanical subcooling auxiliary system for heating. The heated hot water is stored in the domestic hot water tank for domestic hot water for bathing, washing hands, washing vegetables, etc. The cooling evaporator of the auxiliary system subcools the _CO2 fluid in the transcritical _CO2 system, so that the _CO2 fluid obtains a large degree of subcooling.

The above realizes summer working conditions, completes cooling of the indoor environment, supercooling of _CO2 fluid and heating of domestic water.

The controller control method is as follows:

(1) When the temperature in the hot water tank is equal to the hot water temperature required by the user, in winter, the three-way reversing valve on the auxiliary system condenser side is switched to only one port as an open state, and in summer, the three-way reversing valve on the gas cooler side is also switched to one port as an open state, so that the air-cooled fin tube heat exchanger does not work, and only hot water is heated;

(2) When the temperature in the hot water tank is higher than the hot water temperature required by the user, based on (1), the three-way reversing valve is switched to the fully open state, and the air-cooled fin-tube heat exchangers connected in parallel on both sides of the auxiliary system condenser and the summer working gas cooler are both operated, while heating the water, the excess heat is dissipated into the environment;

(3) When the temperature in the hot water tank is lower than the hot water temperature required by the user, the required heat can be compensated by electric heating of the hot water tank based on (1).

The advantages and positive effects of the present invention are:

(1) The refrigerant used in the transcritical _CO2 system is the natural working fluid _CO2 , which has a GWP of 1 and an ODP of 0. It is safe, non-toxic, non-flammable, cheap and easy to obtain, and does not decompose and produce harmful gases under high temperature conditions; the auxiliary system uses non-azeotropic refrigerants with large temperature glide and low GWP, such as R1234ze(E)/CO2, R1234ze(Z)/CO2, R1234yf/CO2, R1234ze(E)/R41, R1234ze(Z)/R41, R1234yf/R41, R1234ze(E)/R32, R1234ze(Z)/R32, R1234yf/R32 and other non-azeotropic mixed working fluids. The refrigerants used in the system are all environmentally friendly working fluids.

(2) By using two four-way reversing valves to switch and control the auxiliary system and the transcritical _CO2 system respectively, a set of equipment can be used to meet the requirements of _CO2 fluid supercooling in winter and summer, thereby improving equipment utilization and significantly improving system energy efficiency.

(3) When the outdoor heat exchanger is frosted in winter, the buffer water tank in front of the indoor fan coil can significantly solve the problem of poor indoor thermal comfort during the defrosting process and reduce the discomfort caused by changes in ambient temperature to people indoors.

(4) The heat from the gas cooler side of the transcritical _CO2 system and the condenser side of the non-azeotropic mechanical subcooling auxiliary system is recovered and utilized to heat the tap water and store it in the system's domestic hot water tank to provide domestic hot water for bathing, hand washing, vegetable washing, etc.

(5) The use of the controller controls the switching of the three-way reversing valve based on the temperature information collected by the temperature sensor installed in the domestic hot water tank, so as to better utilize the heat on the condenser side of the auxiliary system and the gas cooler side under summer conditions, and realize different working modes such as heat exchange heating of domestic hot water, heat dissipation of finned tube evaporator and automatic heating of the hot water tank.

(6) The system can be used in civil and commercial buildings that require both cooling and heating. Therefore, it provides a better system for buildings such as family villas, rural buildings, shopping malls and supermarkets, which can simultaneously achieve winter heating, summer cooling and provide hot water for daily life. One set of equipment can realize the functions of three devices: air conditioning, heat pump and water heater, realizing trigeneration.

(7) The system not only reduces the number and volume of equipment, but also meets the user's demand for the simultaneous operation mode of heat pumps and air conditioners, and optimizes the performance of heat pumps and air conditioners and the efficient use of heat. Under the same power consumption, the system is more energy-efficient and has a higher energy utilization rate, achieving economic operation of the system, improving the flexibility of heat utilization, and achieving the goal of energy conservation and emission reduction. In rural areas in the north, the system can not only reduce the harm of coal burning to the environment and alleviate haze, but also respond to the government's proposal to adopt coal-to-electricity heating measures.

(8) The non-azeotropic refrigerant used in the mechanical subcooling auxiliary system has a large temperature glide in the phase change process in the condenser and the cooling evaporator, that is, the non-azeotropic refrigerant on the condenser side forms a good temperature match with the temperature rise process of water, and the non-azeotropic refrigerant on the cooling evaporator side forms a good temperature match with the subcooling section of the transcritical _CO2 system, which not only reduces the temperature of the gas cooler outlet in the transcritical _CO2 system, but also reduces the irreversible heat exchange loss on the evaporator side and the condenser side, thereby improving the system. Efficiency, reduce compressor exhaust pressure, extend compressor service life, reduce operating costs and improve the overall performance of the cycle.

(9) The non-azeotropic working fluid mechanical subcooling auxiliary system is coupled with the transcritical _CO2 system to reduce the _CO2 operating high pressure, reduce throttling losses, and improve the overall energy efficiency of the transcritical _CO2 refrigeration and heating integrated system.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is an overall schematic diagram of a transcritical _CO2 trigeneration comfort system based on a double four-way reversing valve according to the present invention;

FIG2 is a simplified schematic diagram of a transcritical _CO2 trigeneration comfort system based on a double four-way reversing valve in summer conditions according to the present invention;

FIG3 is a simplified schematic diagram of the transcritical _CO2 trigeneration comfort system based on a double four-way reversing valve in winter conditions according to the present invention.

In the figure: 1. Four-way reversing valve A; 2. Floor heating coil; 3. Gas cooler 1; 4. Buffer water tank; 5. Expansion water tank; 6. Three-way reversing valve A; 7. Three-way reversing valve B; 8. Three-way reversing valve C; 9. Indoor fan coil; 10. Four-way reversing valve B; 11. Compressor 1; 12. Three-way reversing valve D; 13. Three-way reversing valve E; 14. Domestic hot water tank; 15. Three-way reversing valve D; 16. Fin tube heat exchanger 1; 17. Gas cooler 2; 18. Throttle valve 1; 19. Three-way reversing valve B; 20. Condenser; 21. Three-way reversing valve A; 22. Fin tube heat exchanger 2; 23. Compressor 2; 24. Cooling evaporator; 25. Three-way reversing valve F; 26. Throttle valve 2; 27. Three-way reversing valve C.

Detailed ways

The invention comprises: a non-azeotropic working medium mechanical subcooling auxiliary system and a transcritical _CO2 refrigeration and heating integrated system.

Winter implementation plan:

The first step: Compressor 23 sucks in the low-temperature and low-pressure non-azeotropic refrigerant gas at the outlet of the cooling evaporator 24, compresses it into a high-temperature and high-pressure gas, and flows into the condenser 20 through the a2-a3 port of the three-way reversing valve a21, exchanges heat with water in the condenser 20 to achieve condensation, and then flows into the throttle valve 18 through the b3-b2 port of the three-way reversing valve b19 to throttle and reduce the pressure, turning into a gas-liquid two-phase state, and then evaporates and absorbs heat in the cooling evaporator 24 to become a superheated gas and enter the compressor 2 23, completing the auxiliary cycle.

Step 2: Compressor 11 inhales low-temperature and low-pressure _CO2 gas at the outlet of fin tube heat exchanger 16, compresses it into high-temperature and high-pressure supercritical gas, flows through the pipeline shown by the solid line in the four-way reversing valve B10, enters the gas cooler 3 to exchange heat with water and condense, and then becomes medium-temperature and medium-pressure _CO2 fluid, and then flows through the pipeline shown by the solid line in the four-way reversing valve A1 to enter the cooling evaporator 24 for supercooling, and after supercooling, it is throttled by the throttle valve 26 and becomes low-temperature and low-pressure gas-liquid two-phase _CO2 refrigerant, and passes through the pipeline shown by the solid line in the four-way reversing valve A1 to the fin tube heat exchanger 16. Under this working condition, the c3 port of the three-way reversing valve c 27 and the d1 port of the three-way reversing valve d 12 are both switched to the closed state. After evaporation, the _CO2 fluid enters the pipeline shown by the solid line in the four-way reversing valve B10 and is finally inhaled into the compressor 11 to complete the transcritical _CO2 cycle.

Step 3: After the water flows through the gas cooler 3 of the transcritical _CO2 system, it exchanges heat with the _CO2 fluid. Under this condition, if the indoor fan coil 9 is used to heat the indoor environment, then the A1 port of the three-way reversing valve A6 and the B1 port of the three-way reversing valve B7 are switched to the closed state to ensure that the water flows into the indoor fan coil 9, releases heat to the room, and then returns to the gas cooler 3 for heating, and then enters the cache water tank 4. The above completes the indoor heating. The expansion water tank 5 can replenish water, set pressure, and release air to the water circulation system. When the indoor fan coil is used to heat the room, when the outdoor heat exchanger is frosted to a certain extent, the four-way reversing valve B10 and the four-way reversing valve A1 will be switched to the summer working state, the indoor heat exchanger will be changed from a gas cooler to an evaporator, and the outdoor heat exchanger will be changed from a finned tube evaporator to a gas cooler, to release heat and defrost. When switching to the summer working state, the three-way reversing valve C8 will be switched so that the water flowing out of the indoor fan coil 9 enters from the C2 port of the three-way reversing valve C8, one stream flows from the C1 port of the three-way reversing valve C8 to the condenser 20 side of the mechanical subcooling auxiliary system for heating, and the other stream flows from the C3 port of the three-way reversing valve C8 to the evaporator side of the transcritical _CO2 system for cooling. After the two streams of water flow out of the two heat exchangers, they flow into the buffer water tank 4, and the heated and cooled water are mixed. The use of the buffer water tank 4 can significantly solve the problem of poor indoor thermal comfort during the defrosting process during the working state conversion operation, and reduce the discomfort caused by the changes in ambient temperature to the indoor people. After defrosting is completed, the four-way reversing valve B10 and the four-way reversing valve A1 are switched to the winter working condition, i.e., the heating state, to complete the defrosting of the heat exchanger. If the floor heating coil (or heat exchanger) 2 is used to heat the indoor environment, then the A2 port of the three-way reversing valve A6 and the B2 port of the three-way reversing valve B7 are both switched to the closed state to ensure that water flows into the floor heating coil (or radiator) 2, and after providing heat to the room, it returns to the gas cooler 3 for further heating. The buffer water tank 4 also plays a buffering role, to complete the indoor heating. The expansion water tank 5 can replenish water, set pressure, and release air to the water circulation system. During winter operation, tap water flows into the water circulation system and is divided into two streams. One stream flows into the gas cooler 13 in the transcritical _CO2 system through the D1-D3 port of the three-way reversing valve D15 for heating. At this time, the F3 port of the three-way reversing valve F25 is switched to the closed state, and the heated hot water flows into the domestic hot water 14 for storage through the E1-E3 port of the three-way reversing valve E13; the other stream flows into the condenser 20 of the non-azeotropic working medium mechanical subcooling auxiliary system through the D1-D2 port of the three-way reversing valve D15 through the domestic hot water tank 14 for heating, and the heated hot water flows into the domestic hot water 14 for storage; it is used for domestic hot water for bathing, washing hands, washing vegetables, etc. The cooling evaporator 24 of the auxiliary system supercools the _CO2 fluid. The above completes the operation of the winter operation, and the cycle is repeated.

Through the temperature information collected by the temperature sensor in the domestic hot water tank 14, the controller can control the switching of the three-way reversing valve a 21 and the three-way reversing valve b 19 to better utilize the heat on the condenser side of the auxiliary system to achieve different working modes of heat exchange heating of domestic hot water, heat dissipation of finned tube evaporator and automatic heating of the hot water tank. When the temperature in the hot water tank is equal to the hot water temperature required by the user, that is, as mentioned above, the controller controls the three-way reversing valve to switch, the a1 port of the three-way reversing valve a and the b1 port of the three-way reversing valve b are closed, the fin-tube heat exchanger 22 does not work, and the water is heated by the condenser 20 side of the non-azeotropic working medium mechanical subcooling auxiliary system to meet the demand for domestic hot water; when the temperature in the hot water tank is higher than the hot water temperature required by the user, the controller controls the three-way reversing valve to switch, so that the three-way reversing valve a 21 and the three-way reversing valve b 19 are all opened, and the fin-tube heat exchanger 22 works, while heating the water, the excess heat is dissipated into the environment; when the temperature in the hot water tank is lower than the hot water temperature required by the user, the controller controls the three-way reversing valve to switch, the a1 port of the three-way reversing valve a and the b1 side of the three-way reversing valve b are closed, the fin-tube heat exchanger 22 does not work, and the hot water tank 14 electrically heats the tap water to meet the heat required by the user, and the above completes the control of the system by the controller.

Summer implementation plan:

The first step: Compressor 23 sucks in the low-temperature and low-pressure non-azeotropic refrigerant gas at the outlet of the cooling evaporator 24, compresses it into a high-temperature and high-pressure gas, and flows into the condenser 20 through the a2-a3 port of the three-way reversing valve a21, exchanges heat with water in the condenser 20 to achieve condensation, and then flows into the throttle valve 18 through the b3-b2 port of the three-way reversing valve b19 to throttle and reduce the pressure, turning into a gas-liquid two-phase state, and then evaporates and absorbs heat in the cooling evaporator 24 to become a superheated gas and enter the compressor 2 23, completing the auxiliary cycle.

Step 2: Compressor 11 sucks in low-temperature and low-pressure _CO2 gas at the outlet of gas cooler 3, compresses it into high-temperature and high-pressure supercritical gas, flows through the pipeline shown by the dotted line of the four-way reversing valve B10, enters the gas cooler 217 through the d3-d1 port of the three-way reversing valve d12, exchanges heat with water and condenses to become medium-temperature and medium-pressure _CO2 fluid, flows through the c3-c1 port of the three-way reversing valve c27, and then enters the cooling evaporator 24 through the pipeline shown by the dotted line of the four-way reversing valve A1 for supercooling. After supercooling, it passes through the throttle valve 26 to become a low-temperature and low-pressure gas-liquid two-phase state _CO2 refrigerant, passes through the pipeline shown by the dotted line of the four-way reversing valve A1 to the gas cooler 3 for evaporation, then enters the pipeline shown by the dotted line of the four-way reversing valve B10 and finally enters the compressor 11 to complete the transcritical _CO2 cycle.

Step 3: The cooling water is cooled after passing through the gas cooler 3 of the transcritical _CO2 system. Under this working condition, the A1 of the three-way reversing valve A6, the B1 of the three-way reversing valve B7 and the C1 of the three-way reversing valve C8 are all switched to the closed state to ensure that the water flows into the indoor fan coil 9, absorbs the indoor heat, and then returns to the gas cooler 3 for heat release and cooling. The above completes the indoor cooling. The expansion water tank 5 can supply water, set the pressure and release air to the water circulation system.

In summer conditions, tap water flows into the water circulation system and is divided into two streams. One stream flows into the gas cooler 2 17 in the transcritical _CO2 system through the D1-D3 port of the three-way reversing valve D15 for heating. At this time, the F1 port of the three-way reversing valve F25 is switched to a closed state, and the heated hot water flows into the domestic hot water 14 for storage through the E2-E3 port of the three-way reversing valve E13; the other stream flows into the condenser 20 of the non-azeotropic working medium mechanical subcooling auxiliary system through the D1-D2 port of the three-way reversing valve D15 through the domestic hot water tank 14 for heating, and the heated hot water flows into the domestic hot water 14 for storage; it is used for domestic hot water for bathing, washing hands, washing vegetables, etc. The cooling evaporator 24 of the auxiliary system supercools the _CO2 fluid. The above completes the operation of the winter condition, and the cycle is repeated.

The controller can control the switching of the three-way reversing valve a21, the three-way reversing valve b19, the three-way reversing valve c27, and the three-way reversing valve d12 through the temperature information collected by the temperature sensor in the domestic hot water tank 14, so as to better utilize the heat on the gas cooler side of the transcritical _CO2 system and the condenser side of the auxiliary system, and realize different working modes of heat exchange heating domestic hot water, heat dissipation of the finned tube evaporator, and automatic heating of the hot water tank. When the temperature in the hot water tank is equal to the hot water temperature required by the user, that is, as mentioned above, the controller controls the switching of the three-way reversing valve, so that the a1 of the three-way reversing valve a21, the b1 of the three-way reversing valve b19, the c2 of the three-way reversing valve c27, and the d2 side of the d12 are closed, the finned tube heat exchanger 22 and the finned tube heat exchanger 16 do not work, and the water passes through the transcritical CO2. _2. The gas cooler 217 side of the system and the condenser 20 side of the non-azeotropic working fluid mechanical subcooling auxiliary system are heated to meet the demand for domestic hot water; when the temperature in the hot water tank is higher than the hot water temperature required by the user, the controller controls the three-way reversing valve to switch, so that the three-way reversing valve a21, the three-way reversing valve b19 and the three-way reversing valve c27, and the three-way reversing valve d12 are all opened, and the fin tube heat exchanger 22 and the fin tube heat exchanger 116 work, and while heating the water, the excess heat is dissipated into the environment; when the temperature in the hot water tank is lower than the hot water temperature required by the user, the controller controls the three-way reversing valve to switch, and the a1 of the three-way reversing valve a21, the b1 of the three-way reversing valve b19, the c2 of the three-way reversing valve c27 and the d2 side of the d12 are closed, the fin tube heat exchanger 22 and the fin tube heat exchanger 116 do not work, and the hot water tank 14 electrically heats the tap water to meet the heat required by the user, and the above completes the control of the system by the controller.

Although the preferred embodiments of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the above-mentioned specific embodiments. The above-mentioned specific embodiments are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, which all fall within the scope of protection of the present invention.

Claims (1)

1. A trans-critical CO ₂ triple supply comfort system based on a double four-way reversing valve is characterized in that,

The system consists of a non-azeotropic working medium mechanical supercooling auxiliary system and a transcritical CO ₂ refrigerating and heating integrated system, wherein the non-azeotropic working medium mechanical supercooling auxiliary system comprises a compressor II, a condenser, a throttle valve I and a cooling evaporator; the transcritical CO ₂ refrigerating and heating integrated system comprises a first compressor, a first gas cooler, a second gas cooler and a second throttle valve;

the compressor is respectively connected with the cooling evaporator and the three-way reversing valve a, the three-way reversing valve a is respectively connected with the condenser and the finned tube heat exchanger II, the three-way reversing valve B is respectively connected with the throttle valve I, the condenser and the finned tube heat exchanger II, the throttle valve I is connected with the cooling evaporator, the throttle valve II is sequentially connected with the four-way reversing valve A, the four-way reversing valve A is respectively connected with the gas cooler I and the cooling evaporator, the three-way reversing valve C is respectively connected with the finned tube evaporator I, the gas cooler II and the four-way reversing valve A, the three-way reversing valve E is respectively connected with the domestic hot water tank, the gas cooler I and the gas cooler II, the three-way reversing valve D is respectively connected with the water inlet pipe, the domestic hot water tank and the three-way reversing valve F, the three-way reversing valve F is respectively connected with the gas cooler I and the gas cooler II, the air inlet and the air outlet of the compressor I are respectively connected with the four-way reversing valve B, the four-way reversing valve B is respectively connected with the gas cooler I and the three-way reversing valve D, the three-way reversing valve D is respectively connected with the finned tube evaporator I and the gas cooler II, the three-way reversing valve C is respectively connected with the indoor fan, the condenser and the three-way reversing valve B and the air cooler B and the air tank B respectively, the three-way reversing valve B is respectively connected with the indoor fan and the air radiator and the air cooler air radiator A respectively, the three-way reversing valve B and the air radiator B respectively; in the first gas cooler, the refrigerant CO ₂ and water exchange heat in a countercurrent mode; in the condenser, the non-azeotropic refrigerant and water exchange heat in countercurrent; the domestic hot water tank compensates heat by electric heating; the temperature sensor is arranged in the living hot water tank, and the switching of each three-way reversing valve is controlled according to the temperature information acquired by the temperature sensor.