Carbon dioxide refrigeration system based on photovoltaic photo-thermal and soil cross-seasonal cold storage

Abstract

The application discloses a carbon dioxide refrigeration system based on photovoltaic photothermal and soil cross-seasonal cold storage supercooling, which comprises a PV / T system connected with a CO2 refrigeration cycle system, used for providing electric energy for the CO2 refrigeration cycle system and providing hot water for users; the CO2 refrigeration cycle system is used for refrigerating specific space; a heating system is used for heating specific space; a soil cold storage supercooling cycle system is connected with the PV / T system and the CO2 refrigeration cycle system respectively, used for storing cold in soil in winter and releasing cold from soil in summer, and cooling the PV / T system and the CO2 refrigeration cycle system. The application is equipped with the soil cold storage supercooling technology, uses the heat generated by the gas cooler, the environmental energy, the cold of tap water and the natural cold in external environment air to cool the refrigerant and the solar panel, and improves the refrigeration efficiency of the whole CO2 refrigeration system and the power generation efficiency of the PV / T system.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of refrigeration systems, in particular to a carbon dioxide refrigeration system based on photovoltaic photothermal and soil cross-seasonal cold storage supercooling. BACKGROUND

[0002] With the increasing global climate problems, the refrigeration and air conditioning industry also needs to find environmentally friendly refrigerants to replace HFCs and other high GWP (global warming potential) refrigerants.

[0003] In recent years, the replacement of refrigeration working medium has become an urgent problem to be solved in the refrigeration and air conditioning industry. Among them, natural working medium carbon dioxide CO2 is a non-toxic, non-flammable, abundant source, and large unit volume refrigeration capacity environmentally friendly natural working medium, its ODP (ozone damage degree) is zero and GWP (global warming potential) value is very low, so it is favored by the industry.

[0004] However, the critical temperature of CO2 is only 31.1℃, and its critical pressure is as high as 7.38MPa, which makes its throttling irreversible loss large, and the refrigeration efficiency of the whole CO2 refrigeration system is low. SUMMARY

[0005] The purpose of the present application is to overcome the technical defects of the prior art, and provide a carbon dioxide refrigeration system based on photovoltaic photothermal and soil cross-seasonal cold storage supercooling.

[0006] To this end, the present application provides a carbon dioxide refrigeration system based on photovoltaic photothermal and soil cross-seasonal cold storage supercooling, comprising a PV / T system, a CO2 refrigeration cycle system, a heating system and a soil cold storage supercooling cycle system;

[0007] The PV / T system is connected with the CO2 refrigeration cycle system, and is used to provide electric energy for the CO2 refrigeration cycle system and to provide hot water for users;

[0008] The CO2 refrigeration cycle system is used to refrigerate a specific space;

[0009] The heating system is used to heat a specific space;

[0010] The soil cold storage supercooling cycle system is connected with the PV / T system and the CO2 refrigeration cycle system respectively, and is used to store cold in the soil in winter and release cold from the soil in summer, so as to cool the PV / T system and the CO2 refrigeration cycle system.

[0011] It can be seen from the technical solution provided by the present invention above that compared with the existing technology, the present invention provides a carbon dioxide refrigeration system based on photovoltaic thermal energy and soil cross-seasonal cold storage and supercooling. It is scientifically designed, equipped with soil cold storage and supercooling technology, and fully utilizes the heat generated by the gas cooler and environmental energy, as well as the cooling capacity of tap water and the natural cooling capacity in the external ambient air to cool the refrigerant and solar panels, thereby improving the cooling efficiency and energy efficiency of the entire CO2 refrigeration system, and at the same time improving the power generation efficiency of the photovoltaic / thermal (PV / T) system. It can be widely used in integrated cooling and heating application scenarios for household, commercial and industrial use, and has great practical significance. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a working principle diagram of the carbon dioxide refrigeration system based on photovoltaic thermal energy and soil cross-seasonal cold storage and supercooling provided by the present invention;

[0013] Figure 2 A diagram showing the working principle of the photovoltaic solar thermal and soil-based inter-seasonal supercooling CO2 refrigeration system provided by the present invention in summer, with unused components omitted.

[0014] Figure 3 A diagram showing the working principle of the photovoltaic solar thermal and soil-based cross-seasonal cold storage and supercooling carbon dioxide refrigeration system provided by the present invention in winter, with unused components omitted.

[0015] Figure 4 Schematic diagram of the backplane piping distribution of the PV / T solar panel in the CO2 refrigeration system based on photovoltaic thermal energy and soil inter-seasonal cold storage and supercooling provided by the present invention;

[0016] In the figure, 1 to 14 are the first to fourteenth valves respectively;

[0017] 20 is the fifteenth valve, 24 is the sixteenth valve, 31 is the seventeenth valve, and 34 is the eighteenth valve;

[0018] 36 is the 19th valve, 37 is the 20th valve, 49 is the 21st valve, 50 is the 22nd valve, and 54 is the 23rd valve;

[0019] 17 is the first three-way valve, 18 is the second three-way valve, 19 is the third three-way valve, 22 is the fourth three-way valve, 23 is the fifth three-way valve, 26 is the sixth three-way valve, 44 is the seventh three-way valve, 45 is the eighth three-way valve, and 48 is the ninth three-way valve;

[0020] 16 is a water distributor; 15 is a water collector; 21 is a water-cooled evaporator;

[0021] 25 is a first air-cooled evaporator, 32 is a second air-cooled evaporator;

[0022] 28 is a first CO2 low-pressure stage compressor, 29 is a second CO2 low-pressure stage compressor, 30 is a third CO2 low-pressure stage compressor;

[0023] 27 is a first expansion valve, 33 is a second expansion valve; 35 is a space heating water pump;

[0024] 38 is a first CO2 high-pressure stage compressor, 39 is a second CO2 high-pressure stage compressor, 40 is a third CO2 high-pressure stage compressor;

[0025] 41 is a subcooler; 42 is a CO2 water-cooled gas cooler; 43 is a CO2 air-cooled gas cooler; 46 is a de-superheater; 47 is a tap water pump; 55 is a subcooling tower;

[0026] 51 is a thermal storage water tank; 52 is a PV / T solar panel; 53 is a user-side water equipment. DETAILED DESCRIPTION

[0027] The technical solutions of the present application will be described clearly and completely below in combination with the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0028] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", etc. are only for the purpose of description and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second", etc. can explicitly or implicitly include one or more of the features. In the description of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0029] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0030] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0031] See also Figures 1 to 4 The present invention provides a carbon dioxide refrigeration system based on photovoltaic thermal energy and soil cross-seasonal cold storage and supercooling, including a photovoltaic / thermal (PV / T) system, a CO2 refrigeration cycle system, a heating system (i.e., a space heating system), and a soil cold storage and supercooling cycle system;

[0032] PV / T (photovoltaic / solar thermal) system, connected to the CO2 refrigeration cycle system, is used to provide electricity to the CO2 refrigeration cycle system (specifically the compressor therein) and provide hot water to users;

[0033] CO2 refrigeration cycle system, used to cool a specific space (such as a building);

[0034] Heating systems (i.e., space heating systems) are used to heat a specific space (e.g., a building);

[0035] The soil cold storage and supercooling circulation system is connected to the PV / T system and the CO2 refrigeration circulation system respectively, and is used to store cold in the soil in winter and release cold from the soil in summer, thereby cooling the PV / T system and the CO2 refrigeration circulation system.

[0036] In the present invention, in a specific implementation, the PV / T system specifically includes a PV / T solar panel 52, a tap water pump 47, a hot water storage tank 51 and a user-side water device 53;

[0037] The water inlet of the tap water pump 47 is connected to the existing tap water network;

[0038] The water outlet of the tap water pump 47 is connected to the inlet of the ninth three-way valve 48;

[0039] The two outlets of the ninth three-way valve 48 are connected to the inlet of the twenty-first valve 49 and the inlet of the twenty-second valve 50 respectively;

[0040] The outlet of the twenty-first valve 49 is connected to the first water inlet of the subcooler 41 in the CO2 refrigeration cycle system;

[0041] The first water outlet of the subcooler 41 is connected to the first water inlet of the PV / T solar panel 52;

[0042] It should be noted that the first water inlet and the first water outlet of the supercooler 41 are connected through a separate pipe (specifically, the water pipe 3401) for flowing tap water, for example Figure 4 As shown, the PV / T solar panel 52 includes a back panel 3402 and a water pipe 3401 in the back panel 3402 for flowing tap water.

[0043] The first water outlet of the PV / T solar panel 52 is connected to the outlet of the 22nd valve 50 and the water inlet of the desuperheater 46 in the CO2 refrigeration cycle system respectively;

[0044] It should be noted that the first water inlet and the first water outlet of the PV / T solar panel 52 are connected through a separate pipe.

[0045] The water outlet of the superheater 46 is connected to the water inlet of the hot water storage tank 51;

[0046] The water outlet of the hot water storage tank 51 is connected to the user-side water-using equipment 53 .

[0047] In specific implementation, the power supply output end of the PV / T solar panel 52 is connected to the power input ends of the first CO2 low-pressure stage compressor 28, the second CO2 low-pressure stage compressor 29 and the third CO2 low-pressure stage compressor 30 and the first CO2 high-pressure stage compressor 38, the second CO2 high-pressure stage compressor 39 and the third CO2 high-pressure stage compressor 40 in the CO2 refrigeration cycle system, to provide power to these compressors.

[0048] It should be noted that the first CO2 low-pressure stage compressor 28, the second CO2 low-pressure stage compressor 29, and the third CO2 low-pressure stage compressor 30 are compressors connected in parallel.

[0049] Therefore, based on the above connection method, a photovoltaic / solar thermal (PV / T) system can be formed.

[0050] In a specific implementation, a twenty-third valve 54 is provided on the connecting pipe between the water outlet of the hot water storage tank 51 and the user-side water-using equipment 53 .

[0051] In a specific implementation, the user-side water-using device 53 is a device that the user needs to use hot water, such as a faucet in a bathroom or kitchen, or other living equipment that needs to use hot water.

[0052] It should be noted that, in the present invention, see Figure 4As shown, the backplane of the PV / T solar panel 34 features two parallel, non-intersecting serpentine coils. Thermally conductive silicone is applied to the coils to reduce the contact thermal resistance between the serpentine coils and the photovoltaic panel. One pipe is fed with tap water, while the other is fed with an ethylene glycol-water solution. Both pipes can simultaneously cool the PV / T panel. It should be noted that in the present invention, the tap water pump 47 extracts the tap water and divides it into two streams. The PV / T system specifically includes the following two operating modes:

[0053] Summer working mode: In summer, the ninth three-way valve 48 controls the 22nd valve 50 to be closed and the 21st valve 49 to be opened. The tap water first flows through the subcooler 41 of the CO2 refrigeration cycle. The subcooler 41 exchanges heat. After absorbing heat, the tap water increases in temperature. The tap water then flows through the back pipe of the PV / T solar panel 52 (i.e., the water pipe 3401 in the back panel 3402), absorbing the heat of the PV / T solar panel 52, causing the temperature of the tap water to continue to rise. After that, the tap water passes through the desuperheater 46 of the CO2 refrigeration cycle, causing the temperature of the tap water to rise again. The hot water finally formed enters the hot water storage tank 51 and is stored for subsequent use, thus completing the heat utilization route.

[0054] Winter working mode: In winter, the ninth three-way valve 48 controls the 21st valve 49 to be closed and the 22nd valve 50 to be opened. After the tap water is pumped out, it passes through the 22nd valve 50 and enters the desuperheater 46, so that the temperature of the tap water increases. Then, after coming out of the desuperheater 46, the tap water enters the hot water storage tank 51, and then passes through the 23rd valve 54 and enters the user-side water use equipment 53, completing the working process of the entire system.

[0055] It should be noted that in winter, the water-cooled evaporator 21 exchanges heat with the soil, while the first air-cooled evaporator 25 exchanges heat with the air. This allows the refrigeration cycle medium, CO2, to absorb heat. The heat released in the desuperheater 46 is absorbed by the tap water and stored in the hot water storage tank 51 for heating. The opening and closing of the water-cooled evaporator 21 and the first air-cooled evaporator 25 are selectively controlled by the fifth three-way valve 23. When the soil temperature is high, the water-cooled evaporator 21 is opened; when the air temperature is high, the first air-cooled evaporator 25 is opened. When there is a high demand for domestic hot water, both are opened.

[0056] In the present invention, in a specific implementation, the CO2 refrigeration cycle system specifically includes a first CO2 low-pressure stage compressor 28, a second CO2 low-pressure stage compressor 29 and a third CO2 low-pressure stage compressor 30, a first CO2 high-pressure stage compressor 38, a second CO2 high-pressure stage compressor 39 and a third CO2 high-pressure stage compressor 40, a CO2 air-cooled gas cooler 43, a CO2 water-cooled gas cooler 42, a desuperheater 46, a subcooler 41, a water-cooled evaporator 21, a first air-cooled evaporator 25 and a second air-cooled evaporator 32;

[0057] The CO 2 water-cooled gas cooler 42 operates in winter, and the CO 2 air-cooled gas cooler 43 operates in summer. The switching between the two is controlled by the seventh three-way valve 44 and the eighth three-way valve 45 .

[0058] Among them, the first CO2 low-pressure stage compressor 28, the second CO2 low-pressure stage compressor 29, the first CO2 high-pressure stage compressor 38 and the second CO2 high-pressure stage compressor 39 are all fixed-frequency compressors; the third CO2 high-pressure stage compressor 40 and the third CO2 high-pressure stage compressor 40 are all variable-frequency compressors, which can realize continuous adjustment of the compressor power.

[0059] In the present invention, in a specific implementation, the application temperature range of the subcooler 41 is 5-40°C;

[0060] The application temperature range of the CO2 air-cooled gas cooler 43 and the CO2 water-cooled gas cooler 42 is 30-50°C;

[0061] The application temperature range of the superheater 46 is 50-130°C.

[0062] The working medium outlet of the water-cooled evaporator 21 is connected to an inlet of the sixth three-way valve 26;

[0063] The outlet of the sixth three-way valve 26 is connected to the working medium inlets of the first CO2 low-pressure stage compressor 28, the second CO2 low-pressure stage compressor 29 and the third CO2 low-pressure stage compressor 30 respectively;

[0064] The working medium outlet of the first air-cooled evaporator 25 is connected to the other inlet of the sixth three-way valve 26;

[0065] The outlet of the sixth three-way valve 26 is connected to the working medium inlets of the first CO2 low-pressure stage compressor 28, the second CO2 low-pressure stage compressor 29 and the third CO2 low-pressure stage compressor 30;

[0066] The working medium outlets of the first CO2 low-pressure stage compressor 28, the second CO2 low-pressure stage compressor 29 and the third CO2 low-pressure stage compressor 30 are connected to the working medium inlets of the first CO2 high-pressure stage compressor 38, the second CO2 high-pressure stage compressor 39 and the third CO2 high-pressure stage compressor 40;

[0067] The working medium inlets of the first CO2 high-pressure stage compressor 38, the second CO2 high-pressure stage compressor 39 and the third CO2 high-pressure stage compressor 40 are also connected to the working medium outlet of the second air-cooled evaporator 32;

[0068] The working medium outlets of the first CO2 high-pressure stage compressor 38, the second CO2 high-pressure stage compressor 39 and the third CO2 high-pressure stage compressor 40 are connected to the working medium inlet of the desuperheater 46;

[0069] The working medium outlet to the superheater 46 is connected to the inlet of the eighth three-way valve 45;

[0070] The two outlets of the eighth three-way valve 45 are connected to the inlets of the CO2 water-cooled gas cooler 42 and the CO2 air-cooled gas cooler 43 respectively;

[0071] An eighth three-way valve 45 is used to control the flow of CO2 working medium to the CO2 water-cooled gas cooler 42 and the CO2 air-cooled gas cooler 43;

[0072] The outlets of the CO2 water-cooled gas cooler 42 and the CO2 air-cooled gas cooler 43 are respectively connected to the inlet of the seventh three-way valve 44;

[0073] The outlet of the seventh three-way valve 44 is connected to the working medium inlet of the subcooler 41;

[0074] The working medium outlet of the subcooler 41 is connected to the inlet of the second expansion valve 33;

[0075] The outlet of the second expansion valve 33 is connected to the inlet of the seventeenth valve 31 and the first expansion valve 27 respectively;

[0076] The outlet of the seventeenth valve 31 is connected to the working medium inlet of the air-cooled evaporator 32;

[0077] The outlet of the first expansion valve 27 is connected to the inlet of the fifth three-way valve 23;

[0078] The two outlets of the fifth three-way valve 23 are connected to the inlet of the sixteenth valve 24 and the inlet of the fifteenth valve 20 respectively;

[0079] The outlet of the sixteenth valve 24 is connected to the working medium inlet of the first air-cooled evaporator 25;

[0080] The outlet of the fifteenth valve 20 is connected to the working medium inlet of the water-cooled evaporator 21 .

[0081] In terms of specific implementation, it should be noted that the water-cooled evaporator 21 is installed in the machine room of the building, in contact with the soil, and is used to absorb heat from the soil;

[0082] In terms of specific implementation, it should be noted that the first air-cooled evaporator 25 is installed on the roof of the building to exchange heat with the air and absorb the temperature in the environment; the second air-cooled evaporator 30 is installed on the roof of the building to play the role of a refrigeration system evaporator.

[0083] Therefore, based on the above connection method, a CO2 refrigeration cycle can be formed.

[0084] In specific implementation, the working fluid used in the CO2 refrigeration cycle system is natural working fluid carbon dioxide CO2.

[0085] It should be noted that the CO2 refrigeration cycle includes a CO2 evaporator, a CO2 compressor, a CO2 gas cooler and two expansion valves. The low-temperature and low-pressure CO2 fluid at the outlet of the CO2 evaporator (including the water-cooled evaporator 21 and the first air-cooled evaporator 25 and the second air-cooled evaporator 32) is sucked into the CO2 compressor (the first CO2 low-pressure stage compressor 28, the second CO2 low-pressure stage compressor 29 and the third CO2 low-pressure stage compressor 30 and the first CO2 high-pressure stage compressor 38, the second CO2 high-pressure stage compressor 39 and the third CO2 high-pressure stage compressor 40), and then compressed to a high-temperature and high-pressure CO2 fluid, and then successively enters the CO2 that has been The working medium exchanges heat with the heat exchange fluid in the supercooler, and then flows through the second expansion valve 33 and the first expansion valve 27 for throttling and reducing the pressure, and then evaporates and absorbs heat in the water-cooled evaporator 21, the first air-cooled evaporator 25 and the second air-cooled evaporator 32 to complete the CO2 refrigeration cycle.

[0086] In the present invention, in a specific implementation, the heating system (i.e., the space heating system) specifically includes a space hot water pump 35;

[0087] The water inlet of the space heating water pump 35 is connected to the return water outlet of the space heating pipeline in the specific space;

[0088] The outlet of the space hot water pump 35 is connected to the inlet of the nineteenth valve 36;

[0089] The outlet of the nineteenth valve 36 is connected to the water inlet of the CO2 water-cooled gas cooler 42 in the CO2 refrigeration cycle system;

[0090] The water outlet of the CO2 water-cooled gas cooler 42 is connected to the water inlet of a space heating pipeline in a specific space (for example, a heating pipeline in a building, such as an existing heating pipeline).

[0091] Therefore, based on the above connection method, the space heating process can be completed.

[0092] In the present invention, the space hot water pump 35 is used to pump (ie, extract) circulating water into the heating system.

[0093] It should be noted that the heat exchange fluid in the heating system is water.

[0094] It should be noted that, in the present invention, the heating system (i.e., space heating system) includes the following working modes:

[0095] In winter, the space heating water pump 35 pumps the return water from the space heating pipeline, which then passes through the nineteenth valve 36 and enters the CO2 water-cooled gas cooler 42. Then, the return water from the space heating pipeline is heated in the CO2 water-cooled gas cooler 42. The heated return water (i.e., hot water) flowing out of the CO2 water-cooled gas cooler 42 enters the existing space heating pipeline, completing the heating process.

[0096] In the present invention, in a specific implementation, the soil cold storage and subcooling cycle system is specifically used to cool the refrigerant at the outlet of the PV / T solar panel 52 in the photovoltaic / solar thermal (PV / T) system and the subcooler 41 in the CO2 refrigeration cycle system;

[0097] The soil cold storage and supercooling circulation system specifically includes a water distributor 16, a water collector 15 and a cooling tower 55.

[0098] The inlet of the water distributor 16 is connected to the outlet of the sixth valve 6;

[0099] The outlet of the water distributor 16 is connected to the inlets of the eighth valve 8, the tenth valve 10, the twelfth valve 12 and the fourteenth valve 14 respectively;

[0100] The outlet of the eighth valve 8 is connected to the inlet of the seventh valve 7 through the first U-shaped borehole heat exchanger 101;

[0101] The outlet of the seventh valve 7 is connected to the inlet of the water distributor 15;

[0102] The outlet of the tenth valve 10 is connected to the inlet of the ninth valve 9 through the second U-shaped borehole heat exchanger 102;

[0103] The outlet of the ninth valve 9 is connected to the inlet of the water distributor 15;

[0104] The outlet of the twelfth valve 12 is connected to the inlet of the eleventh valve 11 through the third U-shaped borehole heat exchanger 103;

[0105] The outlet of the eleventh valve 11 is connected to the inlet of the water distributor 15;

[0106] The outlet of the fourteenth valve 14 is connected to the inlet of the thirteenth valve 13 through the fourth U-shaped borehole heat exchanger 104;

[0107] The outlet of the thirteenth valve 13 is connected to the inlet of the water collector 15;

[0108] It should be noted that the first U-shaped buried heat exchanger, the second U-shaped buried heat exchanger, the third U-shaped buried heat exchanger and the fourth U-shaped buried heat exchanger are all U-shaped heat exchangers, and are all buried in the soil 100 .

[0109] The outlet of the water collector 15 is connected to the inlet of the fifth valve 5;

[0110] The outlet of the fifth valve 5 is connected to the inlet of the first three-way valve 17;

[0111] The two outlets of the first three-way valve 17 are connected to the inlet of the first valve 1 and the inlet of the third valve 3 respectively;

[0112] The outlet of the first valve 1 is connected to the inlet of the supplementary cooling tower 55 (i.e., the cooling tower);

[0113] The outlet of the supplementary cooling tower 55 is connected to the inlet of the second valve 2;

[0114] The outlet of the second valve 2 is connected to an inlet of the second three-way valve 18;

[0115] The cooling tower 55 is set in an outdoor natural environment;

[0116] The outlet of the third valve 3 is connected to the inlet of the third three-way valve 19;

[0117] The two outlets of the third three-way valve 19 are respectively connected to the second water inlet of the subcooler 41 and the water inlet of the water-cooled evaporator 21 in the CO2 refrigeration cycle system;

[0118] The second water outlet of the subcooler 41 is connected to the second water inlet of the PV / T solar panel 52 in the PV / T system;

[0119] The second water outlet of the PV / T solar panel 52 is connected to the inlet of the twentieth valve 37;

[0120] The outlet of the twentieth valve 37 is connected to an inlet of the fourth three-way valve 22;

[0121] Another inlet of the fourth three-way valve 22 is connected to the water outlet of the water-cooled evaporator 21;

[0122] It should be noted that the water inlet and the water outlet of the water-cooled evaporator 21 are connected through a separate pipe.

[0123] The outlet of the fourth three-way valve 22 is connected to the inlet of the fourth valve 4;

[0124] The outlet of the fourth valve 4 is connected to the other inlet of the second three-way valve 18;

[0125] The outlet of the second three-way valve 18 is connected to the inlet of the water distributor 16 .

[0126] Therefore, based on the above connection method, the soil's cold storage and supercooling cycle can be completed.

[0127] It should be noted that in the present invention, multiple U-shaped buried tube heat exchangers, including the first U-shaped buried tube heat exchanger, the second U-shaped buried tube heat exchanger, the third U-shaped buried tube heat exchanger and the fourth U-shaped buried tube heat exchanger, are used to exchange energy with the soil, utilize the heat in the soil for heating in winter, and store the cold energy in the air in the soil.

[0128] In the present invention, the cooling tower 55 is installed on the roof of the building to exchange heat with the air in winter, absorb the cold energy in the air, and finally store it in the soil.

[0129] It should be noted that the medium in the soil cooling and supercooling circulation system is an ethylene glycol aqueous solution. The solute of the ethylene glycol aqueous solution is ethylene glycol, and the solvent is water. In the present invention, the volume concentration of the ethylene glycol aqueous solution is 20% to 45%, the initial solidification temperature is -10 to -30°C, and the density range is: 1025 to 1060 kg / m 3 .

[0130] In the present invention, the ethylene glycol aqueous solution can prevent the freezing of water in winter, which would cause the cold storage to be impossible.

[0131] It should be noted that the second water inlet and the second water outlet of the supercooler 41 are connected through a separate pipe (i.e., the glycol aqueous solution pipe 3403 in the back plate 3402 of the PV / T solar panel 52), which is used to flow through the working medium in the soil cold storage and supercooling circulation system, i.e., the glycol aqueous solution, for example Figure 4 As shown, the PV / T solar panel 52 includes a back plate 3402, and an ethylene glycol aqueous solution pipe 3403 in the back plate 3402 is used to flow through the ethylene glycol aqueous solution in the soil cool storage and supercooling circulation system.

[0132] It should be noted that, in the present invention, the soil cold storage and supercooling circulation system includes the following soil cold storage and supercooling working modes:

[0133] Winter cold storage mode: During winter cold storage, the eighteenth valve 34 and the twentieth valve 37 are closed, and the remaining valves are opened. The cooling tower 55 (specifically, the ethylene glycol aqueous solution therein) absorbs cold energy from the outdoor natural environment in which it is installed, and stores the cold energy in the soil 100 through pipelines (specifically, through the water distributor 16 and the first, second, third, and fourth U-shaped buried heat exchangers), thereby replenishing natural cold energy to the soil 100.

[0134] The ethylene glycol-water solution in supplemental cooling tower 55 serves as the coolant in the soil cold storage and supercooling circulation system. It is cooled by the outdoor air and then enters the first, second, third, and fourth U-shaped heat exchangers in sequence. The coolant flows through these four U-shaped heat exchangers, transferring cold energy to the surrounding soil 100, thereby storing natural cold energy in the soil 100. The heated coolant is then cooled down by supplemental cooling tower 55, completing the entire cycle.

[0135] Transition season working mode: In the transition season (i.e. neither summer nor winter), the cold storage system (i.e. soil cold storage supercooling circulation system) is shut down.

[0136] Summer cooling mode: see Figure 2 In the summer cooling mode, the first valve 1 and the second valve 2 are closed, and the other valves are opened. The higher temperature refrigerant (i.e., ethylene glycol aqueous solution) flows in the first U-shaped buried heat exchanger, the second U-shaped buried heat exchanger, the third U-shaped buried heat exchanger, and the fourth U-shaped buried heat exchanger. After releasing heat to the surrounding cold-storing soil 100, the refrigerant temperature decreases. The refrigerant then passes through the subcooler 41 and the PV / T solar panel 52 to cool the CO2 fluid in the subcooler 41 and the PV / T solar panel 52. Then, the refrigerant with increased temperature returns to the four U-shaped buried heat exchangers, namely the first U-shaped buried heat exchanger, the second U-shaped buried heat exchanger, the third U-shaped buried heat exchanger, and the fourth U-shaped buried heat exchanger, to exchange heat with the surrounding soil 100 for cooling, completing the entire cycle.

[0137] It should be noted that after the summer cooling is released and the transition period is over, the soil temperature is basically restored. In the second year, the system will continue to store cold in winter and take out cold in summer to ensure the sustainable operation of the system.

[0138] Specifically, the present invention provides a CO2 refrigeration system based on photovoltaic thermal energy and soil thermal storage and subcooling, comprising a PV / T system (i.e., solar PV / T modules), a refrigeration cycle, a heating system, and a soil thermal storage and subcooling cycle. The refrigeration cycle uses the natural refrigerant CO2, the soil thermal storage and subcooling medium is an ethylene glycol-water solution, and the heating system uses water as the heat exchange fluid.

[0139] In the present invention, the water distributor 15 is used to collect the ethylene glycol aqueous solutions in different dispersed buried pipes;

[0140] The water collector 16 is used to evenly distribute the ethylene glycol aqueous solution to different buried pipes;

[0141] The cooling tower 55 is used to absorb the cold energy from the air and store it in the soil 100;

[0142] The water-cooled evaporator 21 is used to exchange heat with the soil in winter, so that the refrigerant absorbs the heat of the refrigerant through the water-cooled evaporator. When the heat load is large, it absorbs heat from the low-level heat source air to meet the demand of large heating load;

[0143] The air-cooled evaporator 25 is used to exchange heat with the air in winter, so that the refrigerant absorbs heat from the air. When the heat load is large, it absorbs heat from the low-level heat source air to meet the demand of large heating load;

[0144] The air-cooled evaporator 32 serves as the evaporator of the refrigeration system to meet the cooling needs of the user;

[0145] The first CO2 low-pressure stage compressor 28, the second CO2 low-pressure stage compressor 29 and the third CO2 low-pressure stage compressor 30, as well as the first CO2 high-pressure stage compressor 38, the second CO2 high-pressure stage compressor 39 and the third CO2 high-pressure stage compressor 40 are used to compress the working medium to increase the temperature and pressure of the working medium;

[0146] The desuperheater 39 is used to realize heat exchange between the working medium and tap water. The working medium temperature is reduced, and the tap water absorbs heat and stores it in the heat storage tank for domestic hot water and heat load requirements.

[0147] The gas cooler 38 is used to remove the heat of the refrigerant and use it for space heating in winter.

[0148] The subcooler 37 is used to subcool the working medium with the ethylene glycol solution and cooling water to reduce throttling losses.

[0149] In the present invention, in terms of specific implementation, the CO2 refrigeration system of the present invention adopts an integrated refrigeration and heating mode of cross-seasonal cold storage and release combined cooling. In summer, the cold energy in the soil is extracted by the refrigerant, and first passes through the supercooler 41 and the back plate of the PV / T solar panel 52 with tap water to cool the CO2 fluid at the outlet of the gas cooler and the back plate of the PV / T solar panel 52, thereby realizing the segmented and cascaded utilization of the cold energy of the soil and tap water, and improving the energy efficiency of the CO2 refrigeration system and the efficiency of solar power generation. Then, the refrigerant enters the soil to continue to absorb the cold energy, and the tap water enters the desuperheater 46 for secondary heating and then provides heat.

[0150] In winter, the air's natural cooling energy is stored in the soil via a supplemental cooling tower for inter-seasonal use in the summer. Tap water is heated in a desuperheater 46 for hot water production, while a CO2 water-cooled gas cooler 42 heats circulating water for heating. Solar energy is used to generate photovoltaic power year-round, powering the compressors in the CO2 refrigeration cycle.

[0151] It should be noted that, in the present invention, by supercooling the CO2 fluid at the outlet of the CO2 gas cooler of the refrigeration cycle system, the throttling loss of the CO2 refrigeration cycle can be greatly reduced, and the efficiency of the CO2 refrigeration system can be improved.

[0152] It's important to note that solar panels, as a clean, renewable energy source, heat up significantly during power generation, reducing their efficiency. By running pipes beneath the panels and passing a cooling fluid, such as water, through the pipes, the panels can be cooled and, at the same time, absorb the heat to produce hot water for use. Furthermore, in refrigeration systems, using photovoltaic panels to power compressors can also reduce energy consumption. Gas coolers generate significant heat during operation, and recycling this heat can improve system energy efficiency.

[0153] The use of natural cooling is an effective way to achieve energy conservation and emission reduction. As a pollution-free, renewable energy source, it holds considerable value. Natural cooling also plays a significant role in areas such as data center cooling. Harnessing the thermal inertia of the soil to store and utilize winter cooling energy across seasons can promote low-carbon sustainable development and address the imbalance between the supply and demand of natural cooling energy over time.

[0154] Compared with the existing technology, the carbon dioxide refrigeration system based on photovoltaic thermal energy and soil cross-seasonal cold storage and supercooling provided by the present invention has the following beneficial effects:

[0155] 1. In the present invention, in summer, by extracting cold energy from the soil and using tap water, the refrigerant at the outlet of the gas cooler is supercooled, and the back plate of the PV / T solar panel 52 is further cooled, thereby synergistically improving the power generation efficiency of the CO2 refrigeration system and solar energy.

[0156] 2. In the present invention, soil cold storage can achieve cross-seasonal cold storage and release, realizing natural cold energy in winter, which can be used to cool the CO2 gas cooler, desuperheater, fluid at the high-pressure compressor outlet and PV / T solar panel 52 in summer.

[0157] 3. In the present invention, the ethylene glycol solution that extracts cold energy from the soil in summer can continuously cool the CO2 gas cooler, the desuperheater, the fluid at the outlet of the high-pressure compressor, and the PV / T assembly (i.e., the PV / T solar panel 52), thereby realizing the cascade utilization of cold energy.

[0158] 4. The present invention recovers heat from the PV / T modules (i.e., PV / T solar panels 52) and the gas cooler, desuperheater, and subcooler in the summer to heat domestic hot water. Simultaneously, heat from the desuperheater is recovered in the winter to heat domestic hot water, thereby improving energy efficiency. In winter, if heating capacity is insufficient, heat released in the summer by the soil can be extracted by a water-cooled evaporator, and heat can be absorbed from the air by an air-cooled evaporator for heating.

[0159] In a specific implementation, the water-cooled evaporator 21 is installed in a machine room in a building and is used to absorb heat in the soil through a refrigerant.

[0160] 5. In this invention, the refrigerant in the CO2 refrigeration system based on photovoltaic thermal energy and soil thermal storage is the natural working fluid CO2. It has an ODP (Ozone Detriment Level) of 0 and a GWP (Global Warming Potential) of 1. It does not decompose even under high temperatures, making it safe, non-toxic, and environmentally friendly.

[0161] 6. The present invention is equipped with PV / T solar modules, which can not only provide electricity for the compressor of the CO2 refrigeration system through solar power generation, but also absorb heat through solar panels and store and utilize it through water. It can not only reduce the energy consumption of the CO2 refrigeration system, but also provide hot water for users, making great use of solar energy and indirectly reducing carbon emissions.

[0162] 7. The present invention can realize cooling and heating throughout the year through a set of devices, with a high degree of system integration, which can greatly reduce the investment cost of the system.

[0163] In summary, compared with the existing technology, the carbon dioxide refrigeration system based on photovoltaic thermal energy and soil cross-seasonal cold storage and supercooling provided by the present invention has a scientific design, is equipped with soil cold storage and supercooling technology, and fully utilizes the heat generated by the gas cooler and environmental energy, as well as the cooling capacity of tap water and the natural cooling capacity in the external ambient air to cool the refrigerant and solar panels, thereby improving the cooling efficiency and energy efficiency of the entire CO2 refrigeration system, and at the same time improving the power generation efficiency of the photovoltaic / thermal (PV / T) system. It can be widely used in integrated cooling and heating application scenarios for household, commercial and industrial use, and has great practical significance.

[0164] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A carbon dioxide refrigeration system based on photovoltaic thermal energy and soil seasonal cold storage and supercooling, characterized by: Including PV / T system, CO2 refrigeration cycle system, heating system and soil cold storage and supercooling cycle system; The PV / T system is connected to the CO2 refrigeration cycle system to provide electricity for the CO2 refrigeration cycle system and hot water for users; The CO2 refrigeration cycle system is used to cool a specific space; Heating systems are used to heat specific spaces; The soil cold storage and supercooling cycle system is connected to the PV / T system and the CO2 refrigeration cycle system respectively, and is used to store cold in the soil in winter and release cold from the soil in summer, thereby cooling the PV / T system and the CO2 refrigeration cycle system; PV / T system, including PV / T solar panels (52), tap water pump (47), hot water storage tank (51) and user-side water use equipment (53); The water inlet of the tap water pump (47) is connected to the existing tap water network; The water outlet of the tap water pump (47) is connected to the inlet of the ninth three-way valve (48); The outlet of the ninth three-way valve (48) is connected to the inlet of the twenty-first valve (49) and the inlet of the twenty-second valve (50) respectively; The outlet of the twenty-first valve (49) is connected to the first water inlet of the subcooler (41) in the CO2 refrigeration cycle system; The first water outlet of the subcooler (41) is connected to the first water inlet of the PV / T solar panel (52); The first water outlet of the PV / T solar panel (52) is respectively connected to the outlet of the twenty-second valve (50) and the water inlet of the desuperheater (46) in the CO2 refrigeration cycle system; The water outlet of the superheater (46) is connected to the water inlet of the hot water storage tank (51); The water outlet of the hot water storage tank (51) is connected to the user-side water-using equipment (53); The back plate (3402) of the PV / T solar panel (52) has two parallel serpentine coils, and the two serpentine coils include an ethylene glycol water solution pipe (3403) and a water pipe (3401); The water pipe (3401) is used to flow tap water; The ethylene glycol aqueous solution pipeline (3403) is used to flow through the ethylene glycol aqueous solution in the soil cooling storage and supercooling circulation system; A CO2 refrigeration cycle system comprising a first CO2 low-pressure stage compressor (28), a second CO2 low-pressure stage compressor (29), and a third CO2 low-pressure stage compressor (30), a first CO2 high-pressure stage compressor (38), a second CO2 high-pressure stage compressor (39), and a third CO2 high-pressure stage compressor (40), a CO2 air-cooled gas cooler (43), a CO2 water-cooled gas cooler (42), a desuperheater (46), a subcooler (41), a water-cooled evaporator (21), a first air-cooled evaporator (25), and a second air-cooled evaporator (32); The working medium outlet of the water-cooled evaporator (21) is connected to an inlet of the sixth three-way valve (26); the outlet of the sixth three-way valve (26) is respectively connected to the working medium inlets of the first CO2 low-pressure stage compressor (28), the second CO2 low-pressure stage compressor (29), and the third CO2 low-pressure stage compressor (30); The working medium outlet of the first air-cooled evaporator (25) is connected to the other inlet of the sixth three-way valve (26); the outlet of the sixth three-way valve (26) is connected to the working medium inlets of the first CO2 low-pressure stage compressor (28), the second CO2 low-pressure stage compressor (29), and the third CO2 low-pressure stage compressor (30); The working fluid outlets of the first CO2 low-pressure stage compressor (28), the second CO2 low-pressure stage compressor (29), and the third CO2 low-pressure stage compressor (30) are connected to the working fluid inlets of the first CO2 high-pressure stage compressor (38), the second CO2 high-pressure stage compressor (39), and the third CO2 high-pressure stage compressor (40); The working medium inlets of the first CO2 high-pressure stage compressor (38), the second CO2 high-pressure stage compressor (39), and the third CO2 high-pressure stage compressor (40) are also connected to the working medium outlet of the second air-cooled evaporator (32); The working medium outlets of the first CO2 high-pressure stage compressor (38), the second CO2 high-pressure stage compressor (39), and the third CO2 high-pressure stage compressor (40) are connected to the working medium inlet of the desuperheater (46); The working medium outlet of the superheater (46) is connected to the inlet of the eighth three-way valve (45); The two outlets of the eighth three-way valve (45) are respectively connected to the inlets of the CO2 water-cooled gas cooler (42) and the CO2 air-cooled gas cooler (43); The eighth three-way valve (45) is used to control the flow of CO2 working medium to the CO2 water-cooled gas cooler (42) and the CO2 air-cooled gas cooler (43); the outlets of the CO2 water-cooled gas cooler (42) and the CO2 air-cooled gas cooler (43) are respectively connected to the inlet of the seventh three-way valve (44); the outlet of the seventh three-way valve (44) is connected to the working medium inlet of the subcooler (41); the working medium outlet of the subcooler (41) is connected to the inlet of the second expansion valve (33); The outlet of the second expansion valve (33) is connected to the inlet of the seventeenth valve (31) and the first expansion valve (27), respectively; the outlet of the seventeenth valve (31) is connected to the working medium inlet of the air-cooled evaporator (32); the outlet of the first expansion valve (27) is connected to the inlet of the fifth three-way valve (23); the two outlets of the fifth three-way valve (23) are connected to the inlet of the sixteenth valve (24) and the inlet of the fifteenth valve (20), respectively; the outlet of the sixteenth valve (24) is connected to the working medium inlet of the first air-cooled evaporator (25); and the outlet of the fifteenth valve (20) is connected to the working medium inlet of the water-cooled evaporator (21); A soil cold storage and subcooling circulation system is used to cool the refrigerant at the outlet of the PV / T solar panel (52) and the subcooler (41) in the PV / T system; A soil cold storage and supercooling circulation system, comprising a water distributor (16), a water collector (15), a cooling tower (55), and a plurality of U-shaped buried heat exchangers; The cooling tower (55) is connected to the water distributor (16) and the water collector (15) respectively; The water distributor (16) and the water collector (15) are respectively connected to two ends of the plurality of U-shaped buried tube heat exchangers.

2. The carbon dioxide refrigeration system based on photovoltaic thermal energy and soil inter-seasonal cold storage and supercooling according to claim 1 is characterized in that: The power output end of the PV / T solar panel (52) is connected to the power input ends of the first CO2 low-pressure stage compressor (28), the second CO2 low-pressure stage compressor (29), and the third CO2 low-pressure stage compressor (30), as well as the first CO2 high-pressure stage compressor (38), the second CO2 high-pressure stage compressor (39), and the third CO2 high-pressure stage compressor (40).

3. The carbon dioxide refrigeration system based on photovoltaic thermal energy and soil inter-seasonal cold storage and supercooling according to claim 1 is characterized in that: For the PV / T system, the tap water pump (47) extracts the tap water and divides it into two streams. The PV / T system specifically includes the following two working modes: Summer working mode: In summer, the ninth three-way valve (48) controls the twenty-second valve (50) to be closed and the twenty-first valve (49) to be opened. The tap water first flows through the subcooler (41) of the CO2 refrigeration cycle to exchange heat with the subcooler (41). The tap water absorbs heat and its temperature rises. The tap water then flows through the water pipe (3401) in the back plate (3402) of the PV / T solar panel (52) to absorb heat from the PV / T solar panel (52), causing the temperature of the tap water to continue to rise. The tap water then flows through the desuperheater (46) of the CO2 refrigeration cycle to increase its temperature again. The hot water finally formed enters the hot water storage tank (51) for storage. Winter working mode: In winter, the ninth three-way valve (48) controls the 21st valve (49) to be closed and the 22nd valve (50) to be opened. After the tap water is drawn out, it passes through the 22nd valve (50) and enters the desuperheater (46), thereby increasing the temperature of the tap water. The tap water then flows out of the desuperheater (46) and enters the hot water storage tank (51). The tap water then passes through the 23rd valve (54) and enters the user-side water-using equipment (53).

4. The carbon dioxide refrigeration system based on photovoltaic thermal energy and soil inter-seasonal cold storage and supercooling according to claim 1 is characterized in that: A heating system, specifically including a space heating water pump (35); The water inlet of the space heating water pump (35) is connected to the return water outlet of the space heating pipeline in the specific space; The water outlet of the space hot water pump (35) is connected to the inlet of the nineteenth valve (36); The outlet of the nineteenth valve (36) is connected to the water inlet of the CO2 water-cooled gas cooler (42) in the CO2 refrigeration cycle system; The water outlet of the CO2 water-cooled gas cooler (42) is connected to the water inlet of the space heating pipeline in the specific space.

5. The carbon dioxide refrigeration system based on photovoltaic thermal energy and soil inter-seasonal cold storage and supercooling as claimed in claim 4 is characterized in that: Heating system, including the following working modes: In winter, the space heating water pump (35) pumps the return water from the space heating pipeline, passes through the nineteenth valve (36), and then enters the CO2 water-cooled gas cooler (42). Then, the return water from the space heating pipeline is heated in the CO2 water-cooled gas cooler (42). The heated return water from the space heating pipeline flows out of the CO2 water-cooled gas cooler (42) and then enters the existing space heating pipeline, completing the heating process.

6. The carbon dioxide refrigeration system based on photovoltaic thermal energy and soil inter-seasonal cold storage and supercooling according to any one of claims 1 to 5, characterized in that: The inlet of the water distributor (16) is connected to the outlet of the sixth valve (6); The outlet of the water distributor (16) is connected to the inlets of the eighth valve (8), the tenth valve (10), the twelfth valve (12) and the fourteenth valve (14), respectively; The outlet of the eighth valve (8) is connected to the inlet of the seventh valve (7) through the first U-shaped buried heat exchanger (101); The outlet of the seventh valve (7) is connected to the inlet of the water collector (15); The outlet of the tenth valve (10) is connected to the inlet of the ninth valve (9) through the second U-shaped buried heat exchanger (102); The outlet of the ninth valve (9) is connected to the inlet of the water collector (15); The outlet of the twelfth valve (12) is connected to the inlet of the eleventh valve (11) through the third U-shaped underground heat exchanger (103); The outlet of the eleventh valve (11) is connected to the inlet of the water collector (15); The outlet of the fourteenth valve (14) is connected to the inlet of the thirteenth valve (13) through the fourth U-shaped underground heat exchanger (104); The outlet of the thirteenth valve (13) is connected to the inlet of the water collector (15); The first U-shaped buried heat exchanger, the second U-shaped buried heat exchanger, the third U-shaped buried heat exchanger and the fourth U-shaped buried heat exchanger are all buried in the soil (100); The outlet of the water collector (15) is connected to the inlet of the fifth valve (5); The outlet of the fifth valve (5) is connected to the inlet of the first three-way valve (17); The two outlets of the first three-way valve (17) are respectively connected to the inlet of the first valve (1) and the inlet of the third valve (3); The outlet of the first valve (1) is connected to the inlet of the cooling tower (55); The outlet of the cooling tower (55) is connected to the inlet of the second valve (2); The outlet of the second valve (2) is connected to an inlet of the second three-way valve (18); The cooling tower (55) is arranged in an outdoor natural environment; The outlet of the third valve (3) is connected to the inlet of the third three-way valve (19); The two outlets of the third three-way valve (19) are respectively connected to the second water inlet of the subcooler (41) and the water inlet of the water-cooled evaporator (21) in the CO2 refrigeration cycle system; The second water outlet of the subcooler (41) is connected to the second water inlet of the PV / T solar panel (52) in the PV / T system; The second water outlet of the PV / T solar panel (52) is connected to the inlet of the twentieth valve (37); The outlet of the twentieth valve (37) is connected to an inlet of the fourth three-way valve (22); Another inlet of the fourth three-way valve (22) is connected to the water outlet of the water-cooled evaporator (21); The outlet of the fourth three-way valve (22) is connected to the inlet of the fourth valve (4); The outlet of the fourth valve (4) is connected to the other inlet of the second three-way valve (18); The outlet of the second three-way valve (18) is connected to the inlet of the water distributor (16).

7. The carbon dioxide refrigeration system based on photovoltaic thermal energy and soil inter-seasonal cold storage and supercooling according to claim 6 is characterized in that: The soil cool storage and supercooling circulation system includes the following working modes: Winter cold storage working mode: When storing cold in winter, the eighteenth valve (34) and the twentieth valve (37) are closed, and the other valves are opened. The ethylene glycol aqueous solution in the supplementary cooling tower (55) is used as the coolant in the soil cold storage supercooling circulation system. After passing through the supplementary cooling tower (55), it is cooled by the outdoor air and then enters the first U-shaped buried heat exchanger, the second U-shaped buried heat exchanger, the third U-shaped buried heat exchanger and the fourth U-shaped buried heat exchanger in sequence. The coolant flows in the first U-shaped buried heat exchanger, the second U-shaped buried heat exchanger, the third U-shaped buried heat exchanger and the fourth U-shaped buried heat exchanger, and transfers the cold to the surrounding soil (100), thereby achieving the purpose of storing natural cold in the soil (100).

8. The carbon dioxide refrigeration system based on photovoltaic thermal energy and soil inter-seasonal cold storage and supercooling according to claim 6 is characterized in that: The soil cool storage and supercooling circulation system includes the following working modes: Summer cooling mode: In the summer cooling mode, the first valve (1) and the second valve (2) are closed, and the other valves are opened. The high-temperature refrigerant ethylene glycol aqueous solution flows in the first U-type buried heat exchanger, the second U-type buried heat exchanger, the third U-type buried heat exchanger and the fourth U-type buried heat exchanger. After releasing heat to the surrounding cold-storing soil (100), the temperature of the refrigerant decreases. The refrigerant then passes through the subcooler (41) and the PV / T solar panel (52) to cool the CO2 fluid in the subcooler (41) and the PV / T solar panel (52). Then, the refrigerant with increased temperature returns to the four U-type buried heat exchangers, namely the first U-type buried heat exchanger, the second U-type buried heat exchanger, the third U-type buried heat exchanger and the fourth U-type buried heat exchanger, to exchange heat and cool down with the surrounding soil (100), completing the entire cycle.

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