A refrigeration system using CO2-water-carbon dioxide hydrate as refrigerant

Abstract

The present invention discloses a refrigeration system using CO2-water-carbon dioxide hydrate as a refrigerant, belonging to the field of hydrate technology applications. The present invention replaces traditional refrigerants with carbon dioxide hydrate and its decomposition products, replacing the latent heat of vaporization of traditional refrigerants with the decomposition enthalpy of carbon dioxide hydrate. Furthermore, a refrigeration cycle suitable for using hydrates and their decomposition products as working fluids is proposed. The process specifically includes a hydrate slurry generator, a gas compression device, a hydrate slurry throttling device, a liquid re-injection device, an evaporator, a control device, and connecting piping. The system's refrigeration function is achieved through the generation and decomposition of carbon dioxide hydrate. This system replaces traditional artificial refrigerants with natural working fluids, accelerating the process of refrigerant replacement.

Description

Technical Field

[0001] The present invention belongs to the field of hydrate technology application. Utilizing hydrate technology, the present invention addresses the problem of ozone layer damage caused by current traditional artificial refrigerants, and uses natural working fluids such as CO2 gas and water as refrigerants in a refrigeration cycle. Specifically, the present invention relates to a refrigeration system using CO2-water-carbon dioxide hydrate as the refrigerant. Background Art

[0002] Hydrates are formed by the crystallization reaction of gases (such as CH4, H2, CO2, etc.) or partial liquids (such as cyclopentane, tetrahydrofuran, etc.) with water under low temperature and high pressure conditions to form a non-stoichiometric cage-shaped crystalline compound. Its common crystal structures are Type I, Type II and Type H. Carbon dioxide hydrate is a cage-shaped crystalline compound formed by carbon dioxide gas and water under high pressure and low temperature conditions. Its crystal structure is Type I. It is a harmless and environmentally friendly working fluid. The formation and decomposition of carbon dioxide hydrates require changes in the external temperature and pressure environment, and are accompanied by the generation and absorption of heat. The phase equilibrium conditions of hydrates are high pressure and low temperature conditions. If the phase equilibrium conditions are met, hydrates are generated and accompanied by heat release. If the phase equilibrium conditions are not met, hydrates decompose and are accompanied by heat absorption. The heat absorbed and released is called the decomposition enthalpy of the hydrate. The phase equilibrium temperature and pressure conditions of carbon dioxide hydrates are as follows: Figure 2 As shown, its decomposition enthalpy is 500kJ / kg.

[0003] The traditional refrigeration cycle consists of the following processes: compression, condensation, throttling, and evaporation. The compression process involves the compressor compressing a low-temperature, low-pressure gaseous refrigerant into a high-temperature, high-pressure gaseous state. The condensation process involves cooling the high-temperature, high-pressure gaseous refrigerant to a high-pressure liquid state. The throttling process involves throttling and reducing the pressure of the high-pressure liquid refrigerant to a low-temperature, low-pressure liquid state. The evaporation process involves the evaporation of the low-temperature, low-pressure liquid refrigerant into a low-temperature, low-pressure gaseous refrigerant. The refrigerant undergoes these four processes in sequence, circulating. The evaporation process is the cooling process, and the cooling capacity is the refrigerant's latent heat of vaporization. The latent heat of vaporization of traditional refrigerants is 100-200 kJ / kg, approximately 30% of the decomposition enthalpy of carbon dioxide hydrate.

[0004] The entry into force of the Kigali Amendment to the Montreal Protocol and the Kyoto Protocol has accelerated the process of refrigerant replacement. Since February 16, 2005, chlorofluorocarbons and heptafluorocarbons have been phased out as primary refrigerants. Consequently, the use of traditional refrigerants needs to be reduced, and finding alternatives to these refrigerants is a pressing issue. Summary of the Invention

[0005] Based on the above problems, the present invention utilizes the generation and decomposition characteristics of carbon dioxide hydrate, uses carbon dioxide hydrate and its decomposition products as the working fluid of the refrigeration cycle to replace traditional refrigerants, and provides a refrigeration system using CO2-water-carbon dioxide hydrate as the refrigerant.

[0006] The technical solution of the present invention:

[0007] A refrigerant using CO2-water-carbon dioxide hydrate.

[0008] A refrigeration system using CO2-water-carbon dioxide hydrate as a refrigerant comprises a hydrate slurry generator 1, a gas compression device, a hydrate slurry throttling device, a liquid reinjection device, and an evaporator 2; the gas compression device comprises a carbon dioxide compressor 7; the hydrate slurry throttling device comprises a slurry throttling and pressure-reducing valve 9 and a heat-insulating and high-pressure-resistant connecting pipeline 10; the liquid reinjection device comprises a liquid delivery pump 12 and a liquid infusion connecting pipeline 13;

[0009] The bottom of the hydrate slurry generator 1 is connected to the top of the evaporator 2 via a carbon dioxide compressor 7; the upper part of the hydrate slurry generator 1 is connected to the lower part of the evaporator 2 via a liquid delivery pump 12 and a liquid delivery connection pipe 13; the lower part of the hydrate slurry generator 1 is connected to the evaporator 2 via a slurry throttling and pressure reducing valve 9 and a heat-insulating and high-pressure resistant connection pipe 10;

[0010] The compressor 7 , the throttling and pressure reducing valve 9 and the liquid delivery pump 12 are all controlled by an electric control box 14 .

[0011] A solid-liquid separation filter plate 6 and a hydrate decomposition buffer plate 18 are provided at the bottom of the evaporator 2. One end of the hydrate decomposition buffer plate 18 is tightly connected to the wall, and there is a gap between the other end and the wall. There are three plates in total, from top to bottom, respectively, a hydrate decomposition buffer plate 18 tightly connected to the wall away from the thermal insulation and high-pressure resistant connecting pipeline 10, a hydrate decomposition buffer plate 18 tightly connected to the wall close to the thermal insulation and high-pressure resistant connecting pipeline 10, and a hydrate decomposition buffer plate 18 tightly connected to the wall away from the thermal insulation and high-pressure resistant connecting pipeline 10. The solid-liquid separation filter plate 6 is placed below the three hydrate decomposition buffer plates 18.

[0012] A hydrate diverter plate 17 is provided on the top of the evaporator 2, which is arranged obliquely inside the evaporator 2, with the end close to the thermal insulation and high pressure resistant connecting pipeline 10 being higher and the end away from the thermal insulation and high pressure resistant connecting pipeline 10 being lower, and holes of the same size are evenly distributed on the plate.

[0013] The carbon dioxide compressor 7 is mainly composed of a crank-connecting rod piston system 8, a compressor intake valve 19 and a compressor exhaust valve 20. The crank-connecting rod piston system 8 is in the cavity of the carbon dioxide compressor 7; the compressor intake valve 19 is distributed on both sides of the carbon dioxide compressor 7, and is used to connect the crank-connecting rod piston system 8 and the evaporator 2; the compressor exhaust valve 20 is distributed at the top of the carbon dioxide compressor 7, and is used to connect the carbon dioxide compressor 7 and the hydrate slurry generator 1.

[0014] The heat-insulating and high-pressure-resistant connecting pipe 10 is wrapped with a cold-insulating material 11 .

[0015] The evaporator 2 is provided with a heat exchange coil 5 , and the heat exchange coil 5 is provided with hydrate decomposition fins 16 .

[0016] The hydrate slurry generator 1 is a high-temperature-resistant container, with a water bath jacket 15 on the outside, a space stirrer 3 on the inside, and a pressure gauge 4 on the top.

[0017] The specific refrigeration process is as follows:

[0018] The water bath jacket 15 maintains a low temperature environment inside the hydrate slurry generator 1. High-pressure CO2 gas and low-concentration CO2 aqueous solution are mixed in the hydrate slurry generator 1 to generate carbon dioxide hydrate, and carbon dioxide hydrate slurry is generated through the spatial agitator 3. This process replaces the condensation process in the traditional refrigeration cycle; the carbon dioxide hydrate slurry enters the heat-insulating and high-pressure resistant connecting pipeline 10, is depressurized by the slurry throttling and pressure-reducing valve 9, and enters the evaporator 2. This process replaces the throttling process in the traditional refrigeration cycle; in the evaporator 2, the hydrate evenly falls onto the hydrate decomposition fins 16 around the heat exchange coil 5 through the hydrate diverter plate 17. The hydrate absorbs the heat of the heat exchange coil 5 and the hydrate is hydrated. The decomposition of the solids replaces the evaporation process in the traditional refrigeration cycle; the low-concentration CO2 aqueous solution produced by the decomposition falls to the bottom of the evaporator 2 through the hydrate decomposition buffer plate 16 and the solid-liquid separation filter plate 6, and then enters the hydrate slurry generator 1 in a high-pressure state through the liquid delivery pump 12 and the liquid delivery connecting pipe 13; the CO2 gas produced by the decomposition is compressed to a high-pressure state by the carbon dioxide compressor 7 through the high-pressure gas delivery connecting pipe 8 at the top of the evaporator 2, and enters the hydrate slurry generator 1, thereby replacing the compression process in the traditional refrigeration cycle; the power unit carbon dioxide compressor 7, the throttling pressure reducing valve 9 and the liquid delivery pump 12 in the above cycle are all controlled by the electric control box 14.

[0019] Beneficial effects of the present invention: The present invention proposes a refrigeration system using CO2-water-carbon dioxide hydrate as a refrigerant, which solves the problem of refrigerant substitution and utilizes the generation and decomposition characteristics of carbon dioxide hydrate, providing a feasible method for realizing natural working fluids as refrigerants. It is of great significance for environmental protection issues such as refrigerant substitution, and also provides a new type of refrigeration system that is efficient, convenient and energy-saving, which is of great promotion value. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of a refrigeration system using CO2-water-carbon dioxide hydrate as the refrigerant.

[0021] Figure 2 This is a schematic diagram of the phase equilibrium temperature and pressure conditions of carbon dioxide hydrate.

[0022] In the figure: 1 hydrate slurry generator; 2 evaporator; 3 space agitator; 4 pressure gauge; 5 heat exchange coil; 6 solid-liquid separation filter; 7 carbon dioxide compressor; 8 crank-connecting rod piston system; 9 slurry throttling and pressure reducing valve; 10 thermal insulation and high-pressure resistant connecting pipeline; 11 cold insulation material; 12 liquid delivery pump; 13 infusion connecting pipeline; 14 electrical control box; 15 water bath jacket; 16 hydrate decomposition fin; 17 hydrate diverter plate; 18 hydrate decomposition buffer plate; 19 compressor intake valve; 20 compressor exhaust valve. DETAILED DESCRIPTION

[0023] The specific implementation of the present invention is described in detail below in conjunction with the technical solutions and drawings.

[0024] Figure 1 Shown is a schematic diagram of a refrigeration system using CO2-water-carbon dioxide hydrate as a refrigerant.

[0025] The electric control box 14 controls the compressor inlet valve 19 of the carbon dioxide compressor 7 to draw in CO2 gas from the top of the evaporator 2 and compress it to high pressure. The high-pressure CO2 gas is then fed into the hydrate slurry generator 1 through the compressor exhaust valve 20. Simultaneously, the electric control box 14 controls the liquid delivery pump 12 to draw in the low-concentration CO2 aqueous solution from the bottom of the evaporator 2 and pump it to high pressure. The low-concentration CO2 aqueous solution is then fed into the hydrate slurry generator 1 through the infusion connection line 13. The water bath jacket 15 maintains a low-temperature environment within the hydrate slurry generator 1. Within the hydrate slurry generator 1, the high-pressure CO2 gas and the low-concentration CO2 aqueous solution mix to form carbon dioxide hydrate, and the carbon dioxide hydrate slurry is then generated by the spatial agitator 3. The throttling and pressure-reducing valve 9 is regulated by the electrical control box 14. The high-pressure hydrate slurry enters the throttling and pressure-reducing valve 9 through the insulated and high-pressure-resistant connecting pipe 10, where it is reduced to low pressure. It then enters the evaporator 2 from the top through the insulated and high-pressure-resistant connecting pipe 10. It passes through the hydrate diverter plate 17 and evenly falls onto the hydrate decomposition fins 16 surrounding the heat exchange coil 5. Decomposition occurs in the evaporator, an endothermic reaction that cools the coil 5. The low-concentration CO₂ aqueous solution produced by the decomposition passes through the hydrate decomposition buffer plate 16 and the solid-liquid separation filter 6 and falls to the bottom of the evaporator 2. It is then fed into the hydrate slurry generator 1 by the liquid delivery pump 12. The decomposed CO₂ gas is then fed into the hydrate slurry generator 1 by the carbon dioxide compressor 7 to generate carbon dioxide hydrate for the next cycle.

Claims

1. A refrigeration system using CO2-water-carbon dioxide hydrate as a refrigerant, characterized in that: The refrigeration system comprises a hydrate slurry generator (1), a gas compression device, a hydrate slurry throttling device, a liquid reinjection device and an evaporator (2); the gas compression device comprises a carbon dioxide compressor (7); the hydrate slurry throttling device comprises a slurry throttling pressure reducing valve (9) and a heat-insulating and high-pressure resistant connecting pipeline (10); the liquid reinjection device comprises a liquid delivery pump (12) and a liquid delivery connecting pipeline (13); The bottom of the hydrate slurry generator (1) is connected to the top of the evaporator (2) via a carbon dioxide compressor (7); the upper part of the hydrate slurry generator (1) is connected to the lower part of the evaporator (2) via a liquid delivery pump (12) and a liquid delivery connection pipeline (13); the lower part of the hydrate slurry generator (1) is connected to the evaporator (2) via a slurry throttling and pressure-reducing valve (9) and a heat-insulating and high-pressure-resistant connection pipeline (10); a heat exchange coil (5) is provided in the evaporator (2), and a hydrate decomposition fin (16) is provided on the heat exchange coil (5); The compressor (7), throttling pressure reducing valve (9) and liquid delivery pump (12) are all controlled by an electric control box (14); the carbon dioxide compressor (7) is mainly composed of a crank-connecting rod piston system (8), a compressor intake valve (19) and a compressor exhaust valve (20), and the crank-connecting rod piston system (8) is in the cavity of the carbon dioxide compressor (7); the compressor intake valve (19) is distributed on both sides of the carbon dioxide compressor (7) and is used to connect the crank-connecting rod piston system (8) and the evaporator (2); the compressor exhaust valve (20) is distributed on the top of the carbon dioxide compressor (7) and is used to connect the carbon dioxide compressor (7) and the hydrate slurry generator (1).

2. The refrigeration system according to claim 1, characterized in that The bottom of the evaporator (2) is provided with a solid-liquid separation filter (6) and a hydrate decomposition buffer plate (18). One end of the hydrate decomposition buffer plate (18) is tightly connected to the wall surface, and there is a gap between the other end and the wall surface. There are three hydrate decomposition buffer plates (18), which are, from top to bottom, a hydrate decomposition buffer plate (18) tightly connected to the wall surface away from the heat-insulating and high-pressure resistant connecting pipe (10), a hydrate decomposition buffer plate (18) tightly connected to the wall surface close to the heat-insulating and high-pressure resistant connecting pipe (10), and a hydrate decomposition buffer plate (18) tightly connected to the wall surface away from the heat-insulating and high-pressure resistant connecting pipe (10). The solid-liquid separation filter plate (6) is placed below the three hydrate decomposition buffer plates (18).

3. The refrigeration system according to claim 2, characterized in that The evaporator (2) is provided with a hydrate diverter plate (17) on the top, which is arranged obliquely inside the evaporator (2), with the end close to the heat-insulating and high-pressure resistant connecting pipeline (10) being higher and the end away from the heat-insulating and high-pressure resistant connecting pipeline (10) being lower, and holes of the same size are evenly distributed on the plate.

4. The refrigeration system according to claim 3, characterized in that The heat-insulating and high-pressure-resistant connecting pipeline (10) is wrapped with a cold-insulating material (11).

5. The refrigeration system according to claim 4, characterized in that The hydrate slurry generator (1) is a high-temperature-resistant container, with a water bath jacket (15) provided on the outside, a space stirrer (3) provided on the inside, and a pressure gauge (4) provided on the top.

6. The refrigeration system according to claim 5, characterized in that The specific refrigeration process is as follows: The water bath jacket (15) maintains a low temperature environment inside the hydrate slurry generator (1). In the hydrate slurry generator (1), high-pressure CO2 gas and low-concentration CO2 aqueous solution are mixed to generate carbon dioxide hydrate, and carbon dioxide hydrate slurry is generated through the space stirrer (3). This process replaces the condensation process in the traditional refrigeration cycle; the carbon dioxide hydrate slurry enters the heat-insulating and high-pressure resistant connecting pipeline (10), is depressurized through the slurry throttling and pressure-reducing valve (9), and enters the evaporator (2). This process replaces the throttling process in the traditional refrigeration cycle; in the evaporator (2), the hydrate evenly falls onto the hydrate decomposition fins (16) around the heat exchange coil (5) through the hydrate diverter plate (17). The hydrate absorbs the heat of the heat exchange coil (5), and the hydrate decomposition fins (16) around the heat exchange coil (5) are uniformly distributed. Decomposition, using this process to replace the evaporation process in the traditional refrigeration cycle; the low-concentration CO2 aqueous solution produced by the decomposition falls to the bottom of the evaporator (2) through the hydrate decomposition buffer plate (18) and the solid-liquid separation filter (6), and then enters the hydrate slurry generator (1) in a high-pressure state through the liquid delivery pump (12) and the delivery connection pipeline (13); the CO2 gas produced by the decomposition is compressed to a high-pressure state by the carbon dioxide compressor (7) through the high-pressure gas delivery connection pipeline (8) at the top of the evaporator (2) and enters the hydrate slurry generator (1), using this process to replace the compression process in the traditional refrigeration cycle; the power unit carbon dioxide compressor (7), throttling pressure reducing valve (9) and liquid delivery pump (12) in the above cycle are all controlled by the electric control box (14).

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