CN116222020B - Phase change cold accumulation system based on transcritical carbon dioxide absorption refrigeration cycle - Google Patents

Abstract

The invention relates to a phase change cold storage system based on a transcritical carbon dioxide absorption refrigeration cycle. The system includes a solar heat collection system, an absorption refrigeration cycle system and a phase change cold storage and cooling system; the solar heat collection system is connected to an absorption refrigeration system. The refrigeration cycle system is used to provide solar energy to the absorption refrigeration cycle system. The absorption refrigeration cycle system is connected to the phase change cold storage and cooling system and is used to provide refrigeration to the phase change cold storage and cooling system. The invention effectively combines green carbon dioxide refrigeration technology with other energy-saving technologies, namely solar heating technology, through a generator. When solar natural resources are abundant during the day, the transcritical carbon dioxide absorption refrigeration system makes full use of the thermal energy it provides to produce sustainable and stable cooling, achieving efficient use of renewable energy and having the advantages of environmental friendliness and sustainability. , which is of great significance to energy conservation and carbon reduction.

Description

A phase change thermal storage system based on transcritical carbon dioxide absorption refrigeration cycle

Technical field

The invention relates to the technical field of refrigeration and thermal storage, and in particular to a phase change thermal storage system based on a transcritical carbon dioxide absorption refrigeration cycle.

Background technique

Nowadays, with the continuous depletion of traditional fossil energy, which has brought about many problems such as environmental pollution and ecological destruction, achieving sustainable development of energy and solving environmental problems have become urgent problems that need to be solved. As a renewable energy source, solar energy has the advantages of cleanness, economy and safety. Promoting the development and diversified utilization of solar energy resources can help alleviate energy shortages and environmental problems.

Compared with existing refrigerants, which often have shortcomings such as destruction of the ozone layer and high global warming potential, which have adverse effects on the environment, traditional carbon dioxide refrigerants can well solve the environmental problems caused by the use of refrigerants. Carbon dioxide has the advantages of being colorless, odorless, non-toxic, chemically stable, safe, low-cost, and easy to achieve critical states. It is an environmentally friendly natural working fluid. Therefore, green carbon dioxide refrigeration technology has broad development and application prospects. Absorption refrigeration has received widespread attention due to its ability to utilize low-grade heat sources without requiring compressor work to drive the cycle. It is a common refrigeration technology and has good application prospects in refrigeration situations where electric energy is scarce. Traditional absorption refrigeration cycles mostly use lithium bromide-water and ammonia-water as working fluid pairs. Both of these two working fluid pairs have some shortcomings. Among them, lithium bromide-water solution is highly corrosive and has a high impact on the system. Sealing, ammonia is explosive and toxic, while transcritical carbon dioxide and ionic liquid [bm im] PF ₆ working fluid pair have the advantages of non-toxic, good thermal stability and environmental friendliness.

Phase change thermal storage technology can break the time limit to achieve economical operation of the refrigeration system, achieve efficient use of energy, conform to the development trend of the future international society, and has considerable application prospects. As an inorganic phase change material, sodium sulfate decahydrate has the advantages of high energy storage density, low price, and easy adjustment of phase change temperature, and is widely used in the field of cold storage.

At present, the applications of supercritical carbon dioxide as a working fluid are mostly concentrated in the field of power generation. For example, Yang Sheng et al. (Patent name: Transcritical carbon dioxide cycle waste heat power generation system coupled with lithium bromide absorption refrigeration; Application number: 201910829358.8) proposed to combine the refrigeration system with carbon dioxide The cycle power generation system is coupled together and uses cascade waste heat as a heat source. This patent not only considers the utilization of medium and low temperature waste heat, but also provides new ideas for power generation methods. Shen Jiang et al. proposed a heat-driven pump-less absorption-assisted subcooling transcritical CO2 refrigeration system (application number: 201811568330.5) regarding transcritical carbon dioxide refrigeration technology. This patent uses absorption refrigeration with lithium bromide-water as the working fluid pair. The cycle and transcritical carbon dioxide refrigeration cycle are coupled together through a heat exchanger and generator, which solves the problem of heat utilization of compressor exhaust from the heat recovery level, but does not consider the sustainable development and diversified utilization of energy from the energy-saving technology level.

The patent titled "Combined air-conditioning system of solar-driven refrigeration machine and carbon dioxide heat pump" (application number: 201110072622.1) proposes a system that combines a solar-powered refrigeration machine with a carbon dioxide-based heat pump. This system can be used for different purposes. The operating mode is switched. In the refrigeration mode, a lithium bromide refrigerator and a carbon dioxide heat pump are mainly used for refrigeration. A conventional heat pump system is used, which is inseparable from the work of the compressor to provide power for the cycle and has a certain dependence on electrical energy. Although this patent took into account the special working conditions of carbon dioxide working fluid in heat pump systems and designed it, the absorption refrigerator used still uses the traditional lithium bromide-aqueous solution as the working fluid pair and does not focus on carbon dioxide absorption refrigeration. Related designs. When the heat collected by solar energy cannot meet the needs of the refrigerator during other periods of poor solar radiation, such as at night or on cloudy days, cooling can only be undertaken independently by the carbon dioxide heat pump, which has a certain dependence on primary energy.

The patent titled a solar absorption and emission composite transcritical CO2 refrigeration system (application number: 202010069090.5) mainly optimizes and designs the working efficiency of transcritical carbon dioxide working fluid in heat pump systems, and introduces solar absorption and emission. Supercooling cycle (i.e., an absorption refrigeration cycle using lithium bromide-water or ammonia-water solution as the working fluid pair), this cycle reduces the irreversible throttling loss and improves the overall energy efficiency of the system by cooling carbon dioxide in two consecutive steps. The operation and energy efficiency issues of transcritical carbon dioxide working fluid are not considered from the aspect of absorption refrigeration system.

Today, when the global energy crisis and environmental problems are prominent, if green carbon dioxide refrigeration technology can be effectively combined with other energy-saving technologies, it will be of great significance in terms of energy conservation and carbon reduction. At present, there is no design that can effectively and reasonably combine transcritical carbon dioxide absorption refrigeration cycle technology with other energy-saving technologies and phase-change cold storage and cooling technology and use it in the field of refrigeration and cold storage.

Contents of the invention

The main technical problem solved by the present invention is to provide a phase change cold storage system based on a transcritical carbon dioxide absorption refrigeration cycle, which combines transcritical carbon dioxide refrigeration technology, solar heating technology and phase change cold storage and cooling technology. When solar energy is sufficient during the day, The system provides cooling and storage, and the stored cold energy can be released for cooling at night, breaking the time and space constraints of cooling, achieving efficient use of energy, and being environmentally friendly, sustainable, and compact in structure. Advantages, it is of great significance to energy conservation and carbon reduction, and has broad application prospects.

The technical solution of the present invention is as follows: a phase change cold storage system based on a transcritical carbon dioxide absorption refrigeration cycle. The system includes a solar heat collection system, an absorption refrigeration cycle system and a phase change cold storage and release system;

The solar heat collection system is connected to the absorption refrigeration cycle system and is used to provide solar energy to the absorption refrigeration cycle system. The absorption refrigeration cycle system is connected to the phase change cold storage and cooling system and is used to provide refrigeration to the phase change cold storage and cooling system. .

As an improvement, the solar heat collection system includes a solar heat collector, a first circulation pump and a heat storage tank; the outlet of the first circulation pump is connected to the inlet of the solar heat collector, and the outlet of the solar heat collector is connected to the The entrance to the thermal storage tank.

As an improvement, the absorption refrigeration cycle system includes a generator, an absorber, a solution heat exchanger, a solution pump, a first throttle valve, a gas cooler, a regenerator, a second throttle valve and a heat exchanger; The first outlet of the generator is connected to the inlet of the heat storage tank, the second circulation pump is connected to the first inlet of the generator, the second outlet of the generator is connected to the first inlet of the gas cooler, and the gas cooler The first outlet is connected to the first inlet of the regenerator, the first outlet of the regenerator is connected to the inlet of the second throttle valve, and the outlet of the second throttle valve is connected to the first inlet of the heat exchanger. , the first outlet of the heat exchanger is connected to the second inlet of the regenerator, the second outlet of the regenerator is connected to the first inlet of the absorber, and the first outlet of the absorber is connected to the inlet of the solution pump. , the outlet of the solution pump is connected to the first inlet of the solution heat exchanger, the first outlet of the solution heat exchanger is connected to the second inlet of the generator, the third outlet of the generator is connected to the second inlet of the solution heat exchanger, the The second outlet of the solution heat exchanger is connected to the inlet of the first throttle valve, and the outlet of the first throttle valve is connected to the second inlet of the absorber.

As an improvement, the phase change cold storage and cooling system includes a heat exchanger and a water-gas heat exchanger; the heat exchanger is provided with an inlet and an outlet, and the water-gas heat exchanger is provided with an inlet, an outlet, The third inflow pipe and the third outflow pipe; the inlet and outlet on the heat exchanger are respectively connected with the outlet and inlet of the water-gas heat exchanger.

As an improvement, the refrigerant carbon dioxide in the absorption refrigeration cycle system is in a transcritical state. The transcritical state means that when the pressure of the refrigerant separated from the generator is higher than the critical pressure of carbon dioxide, then High-temperature and high-pressure supercritical carbon dioxide flows into the gas cooler to release heat. At this time, the temperature of the carbon dioxide supercritical fluid is slightly higher than the ambient temperature. Afterwards, the temperature of the carbon dioxide fluid decreases after exchanging heat with low-temperature and low-pressure carbon dioxide vapor in the regenerator. Then it enters the second throttle valve and becomes a low-temperature and low-pressure gas-liquid two-phase flow. Finally, it absorbs heat in the heat exchanger for cold storage. During the entire cycle, the refrigerant carbon dioxide is in a transcritical state.

As an improvement, the working fluid heat transfer oil in the solar heat collection system flows out from the outlet of the heat storage tank and enters the solar heat collector through the first circulation pump. After obtaining heat in the solar heat collector, the The high-temperature thermal oil flows from the outlet of the solar collector to the heat storage tank to form a circulation loop. The high-temperature thermal oil flows through the second circulation pump to the generator through the first inlet of the generator. In the generator After heating, it returns to the heat storage tank through the first outlet of the generator to form a cycle.

As an improvement, the refrigerant carbon dioxide in the absorption refrigeration cycle system is precipitated from the concentrated solution in the generator after being heated by the high-temperature heat transfer oil in the generator. The concentrated solution in the generator After being heated, it becomes a dilute solution. The precipitated high-temperature and high-pressure carbon dioxide flows from the second outlet of the generator to the gas cooler. The pressure of the high-temperature and high-pressure carbon dioxide refrigerant is higher than the critical pressure of carbon dioxide. The high-temperature and high-pressure carbon dioxide refrigerant The high-pressure supercritical carbon dioxide becomes high-pressure room-temperature supercritical carbon dioxide after heat exchange with the outdoor normal-temperature cooling water in the gas cooler. The high-pressure room-temperature supercritical carbon dioxide has a slightly higher temperature after heat exchange with the outdoor normal-temperature cooling water. At ambient temperature, the high-pressure room temperature supercritical carbon dioxide refrigerant enters the regenerator, and exchanges heat with the low-temperature and low-pressure carbon dioxide vapor flowing out from the heat exchanger into the regenerator. , flows out from the regenerator to the second throttle valve, and enters the heat exchanger after throttling in the second throttle valve. After absorbing heat and evaporating in the heat exchanger, it flows into the The regenerator is heated in the regenerator and then flows to the absorber. In the absorber, it is mixed with the dilute water flowing out from the second outlet of the solution heat exchanger through the first throttle valve and entering the absorber. After the solution is mixed, it becomes a low-pressure concentrated solution. The low-pressure concentrated solution in the absorber flows to the solution pump through the first outlet of the absorber. The heat generated by the reaction in the absorber is absorbed by the outdoor normal temperature cooling water. Take away, the mixed low-pressure concentrated solution flows from the solution pump to the solution heat exchanger, where it mixes with the dilute solution flowing from the generator to the solution heat exchanger. After heat exchange, it flows out from the first outlet of the solution heat exchanger and returns to the generator through the second inlet of the generator, forming a closed refrigeration cycle. The refrigerant carbon dioxide flows into the absorber through the first inlet of the absorber and mixes with the dilute solution that flows out of the solution heat exchanger through the first throttle valve and then flows into the absorber to become a low-pressure concentrated solution.

As an improvement, the heat exchanger includes a shell, a cavity, a working fluid water heat exchange channel and a working fluid carbon dioxide heat exchange channel; the shell is surrounded by insulation material, and a phase change material is placed in the cavity. The phase change material uses sodium sulfate decahydrate. The working medium water heat exchange channel is provided with four and evenly arranged in a ring shape inside the cavity. The working medium carbon dioxide heat exchange channel is provided with one and is arranged in the cavity. The middle part of the cavity.

The phase change cold storage system based on the transcritical carbon dioxide absorption refrigeration cycle of the present invention combines the solar heat collection system through the generator with transcritical carbon dioxide as the refrigerant and the ionic liquid [bm im] PF ₆ as the absorption The absorption refrigeration cycle system of the agent is combined with the phase change cold storage and cooling system using sodium sulfate decahydrate as the phase change material through the heat exchanger. The invention has the following advantages and beneficial effects:

(1) Effectively combine green carbon dioxide refrigeration technology with other energy-saving technologies, namely solar heating technology, through the generator. When solar natural resources are abundant during the day, the transcritical carbon dioxide absorption refrigeration system makes full use of the thermal energy it provides to produce sustainable and stable cooling, achieving efficient use of renewable energy and having the advantages of environmental friendliness and sustainability. , which is of great significance to energy conservation and carbon reduction.

(2) The refrigerant of the transcritical carbon dioxide absorption refrigeration system uses carbon dioxide, which has the advantages of non-toxic, colorless, odorless, stable chemical properties, safe and low-cost, and easy to achieve critical state. It is an environmentally friendly natural industry. quality.

(3) A regenerator is installed in the transcritical carbon dioxide absorption refrigeration system to reduce the temperature of the carbon dioxide fluid, increase its degree of subcooling, and improve the energy efficiency of the system.

(4) Introduce a phase change cooling storage and cooling system. When solar energy is sufficient during the day, the system provides cooling and cold storage, and the stored cold energy can be released for cooling at night. The integration of cold storage for refrigeration breaks the time and space constraints of cooling, and has broad application prospects.

(5) The present invention has a detailed design and description for the application of transcritical carbon dioxide working fluid in the absorption refrigeration system. It adopts a working fluid pair of carbon dioxide and ionic liquid, which is safe, non-toxic and environmentally friendly, and adds a regenerator. , lowering the temperature of the carbon dioxide working fluid, increasing the degree of subcooling, and improving the refrigeration efficiency of the refrigeration system; at the same time, a phase change cooling storage and cooling system is introduced to integrate refrigeration, supply and cooling, and sufficient solar energy can be used for cooling during the day. At the same time, cold storage is carried out to achieve uninterrupted cooling at night. Compared with a heat pump, the transcritical carbon dioxide absorption refrigeration system proposed by the present invention does not require the work of a compressor to provide power. By using the heat energy recovered by the solar collector to drive the system for cyclic refrigeration, it saves electrical energy resources and improves the utilization of renewable energy. Rate.

Description of the drawings

Figure 1 is a schematic diagram of the phase change thermal storage system based on the transcritical carbon dioxide absorption refrigeration cycle of the present invention;

Figure 2 is a partial schematic diagram 1 of the phase change thermal storage system based on the transcritical carbon dioxide absorption refrigeration cycle of the present invention;

Figure 3 is a partial schematic diagram 2 of the phase change thermal storage system based on the transcritical carbon dioxide absorption refrigeration cycle of the present invention;

Figure 4 is a schematic structural diagram of the heat exchanger in the phase change cold storage system based on the transcritical carbon dioxide absorption refrigeration cycle of the present invention.

1-solar collector, 2-first circulation pump, 3-thermal storage tank, 4-second circulation pump, 5-generator, 6-absorber, 7-solution heat exchanger, 8-solution pump, 9 -First throttle valve, 10-gas cooler, 11-regenerator, 12-second throttle valve, 13-heat exchanger, 14-water-gas heat exchanger, 15-shell, 16-air Cavity, 17-working fluid water heat exchange channel, 18-working fluid CO ₂ heat exchange channel, 19-first outlet of generator, 20-first inlet of generator, 21-second outlet of generator, 22-gas cooler The first inlet, 23-the first outlet of the gas cooler, 24-the first inflow pipe, 25-the first outflow pipe, 26-the first inlet of the regenerator, 27-the first outlet of the regenerator, 28-heat exchanger The first inlet, 29-the first outlet of the heat exchanger, 30-the second inlet of the regenerator, 31-the second outlet of the regenerator, 32-the first inlet of the absorber, 33-the second outflow pipe, 34-the second Inflow pipe, 35-first outlet of absorber, 36-second inlet of absorber, 37-first inlet of solution heat exchanger, 38-second outlet of solution heat exchanger, 39-first outlet of solution heat exchanger, 40 -The second inlet of the solution heat exchanger, 41-the second inlet of the generator, 42-the third outlet of the generator, 43-the second inlet of the heat exchanger, 44-the third inlet of the heat exchanger, 45-the second inlet of the heat exchanger Exit, 46-the third outlet of the heat exchanger, 47-the first outlet of the water-gas heat exchanger, 48-the first inlet of the water-gas heat exchanger, 49-the second outlet of the water-gas heat exchanger, 50-water -The second inlet of the gas heat exchanger, 51-the third inflow pipe, 52-the third outflow pipe, 53-the first stop valve, 54-the second stop valve, 55-the first water supply valve, 56-the second water supply valve , 57-the third water supply valve, 58-the fourth water supply valve.

Detailed ways

The technical solutions in the embodiments of the present invention will be supplemented below with reference to the accompanying drawings in the embodiments of the present invention. The phase change thermal storage system based on the transcritical carbon dioxide absorption refrigeration cycle of the present invention is shown in Figures 1 and 2 and Figures 3 and 4. Its preferred implementation mode is:

As shown in Figure 1, a phase change cold storage system based on a transcritical carbon dioxide absorption refrigeration cycle includes a solar heat collection system, an absorption refrigeration cycle system and a phase change cold storage and cooling system; the solar system is connected to the absorption refrigeration cycle A system is used to provide solar energy to an absorption refrigeration cycle system. The absorption refrigeration cycle system is connected to a phase change cold storage and cooling system, and is used to provide refrigeration to the phase change cold storage and cooling system.

As shown in Figure 1, the solar heat collection system includes a solar heat collector 1, a first circulation pump 2, a second circulation pump 4 and a heat storage tank 3; the outlet of the first circulation pump 2 is connected to the solar collector. The inlet of the solar collector 1 and the outlet of the solar collector 1 are connected to the inlet of the heat storage tank 3; the fluid absorbs solar energy in the solar collector 1 and then transfers the heat to the heat storage tank 3. After the heat exchange, it is circulated back to the solar collector 1 through the first circulation pump 2.

As shown in Figure 1, the absorption refrigeration cycle system includes a generator 5, an absorber 6, a solution heat exchanger 7, a solution pump 8, a first throttle valve 9, a gas cooler 10, a regenerator 11, and a third Two throttle valves 12 and heat exchangers 13; the generator 5 is provided with a first outlet 19, a first inlet 20, a second outlet 21, a second inlet 41 and a third outlet 42. The gas cooler 10 The regenerator 11 is provided with a first inlet 22, a first outlet 23, a first inflow pipe 24 and a first outflow pipe 25. The regenerator 11 is provided with a first inlet 26, a first outlet 27, a second inlet 30 and a second inlet 27. Two outlets 31. The heat exchanger 13 is provided with a first inlet 28, a first outlet 29, a second inlet 43, a third inlet 44, a second outlet 45 and a third outlet 46. The absorber 6 is provided with There is a first inlet 32, a first outlet 35, a second inlet 36, a second outflow pipe 33 and a second inflow pipe 34. The solution heat exchanger 7 is provided with a first inlet 37, a second outlet 38, a first The outlet 39 and the second inlet 40; the first outlet 19 of the generator is connected to the inlet of the heat storage tank 3, the second circulation pump 4 is connected to the first inlet 20 of the generator, and the second outlet of the generator 21 is connected to the first inlet 22 of the gas cooler, the first outlet 23 of the gas cooler is connected to the first inlet 26 of the regenerator, and the first outlet 27 of the regenerator is connected to the second throttle valve 12 The inlet of the second throttle valve 12 is connected to the first inlet 28 of the heat exchanger, and the first outlet 29 of the heat exchanger is connected to the second inlet 30 of the regenerator. The two outlets 31 are connected to the first inlet 32 of the absorber. The first outlet 35 of the absorber is connected to the inlet of the solution pump 8. The outlet of the solution pump 8 is connected to the first inlet 37 of the solution heat exchanger. The solution heat exchanger The first outlet 39 of the generator is connected to the second inlet 41 of the generator, the third outlet 42 of the generator is connected to the second inlet 40 of the solution heat exchanger, and the second outlet 38 of the solution heat exchanger is connected to the inlet of the first throttle valve 9 , the outlet of the first throttle valve 9 is connected to the second inlet 36 of the absorber.

The solution in the generator 5 is a mixed solution of carbon dioxide and ionic liquid. After the mixed solution in the generator 5 absorbs the heat of the working fluid heat transfer oil from the first inlet 20 of the generator, the carbon dioxide is precipitated from the mixed solution, causing the mixed solution to At this time, the concentrated solution changes to a dilute solution, and the precipitated high-temperature and high-pressure carbon dioxide fluid flows out through the second outlet 21 of the generator and flows into the gas cooler 10 through the first inlet 22 of the gas cooler. Heat is released in the generator 10, and the released heat is taken away by the circulating cooling water at room temperature. The high-temperature and high-pressure carbon dioxide fluid becomes a normal-temperature carbon dioxide supercritical liquid after exothermic cooling. The remaining dilute solution in the generator 5 passes through the third generator. The outlet 42 flows to the solution heat exchanger 7. After exchanging heat and cooling through the solution heat exchanger 7, it passes through the first throttle valve 9 to throttle and reduce the pressure, and flows into the absorber 6 from the second inlet 36 of the absorber. The dilute solution absorbs The low-temperature and low-pressure carbon dioxide fluid from the first inlet 32 of the absorber releases a large amount of heat. The heat released is taken away by the circulating cooling water at room temperature. At the same time, the dilute solution becomes a low-pressure mixed concentrated solution. The concentrated solution in the absorber 6 is transferred from the absorber 6 An outlet 35 is drawn out by the solution pump 8, and after heat exchange and temperature rise in the solution heat exchanger 7, it finally returns to the generator 5 through the second inlet 41 of the generator, where it is continued to be heated to high temperature by the solar heat collection system. High pressure state, forming a cycle. Among them, the solution heat exchanger realizes heat exchange between the low-pressure mixed concentrated solution and the dilute solution, effectively increasing the temperature of the concentrated solution before entering the generator.

As shown in Figure 1, the phase change cold storage and cooling system consists of the heat exchanger 13 and a water-to-gas heat exchanger 14; the heat exchanger 13 is provided with a first inlet 28, a second inlet 43, The first outlet 29, the second outlet 45, the third inlet 44 and the third outlet 46. The water-to-gas heat exchanger 14 is provided with a first outlet 47, a first inlet 48, a second outlet 49 and a second inlet. 50. The third inflow pipe 51 and the third outflow pipe 52; the second outlet 45 of the heat exchanger is connected to the second inlet 50 of the water-gas heat exchanger, and the second outlet 49 of the water-gas heat exchanger is connected The second inlet 43 of the heat exchanger, the third outlet 46 of the heat exchanger are connected to the first inlet 48 of the water-gas heat exchanger, and the first outlet 47 of the water-gas heat exchanger is connected to the heat exchanger. The third entrance 44 of the device.

Preferably, the pressure range of the transcritical absorption refrigeration system is between 4MPa and 10MPa, in which the heat removal process in the gas cooler occurs in the supercritical region where the pressure is greater than 7.18MPa and the temperature range is about 5°C to 100°C.

The phase change cold storage system based on the transcritical carbon dioxide absorption refrigeration cycle described in the above embodiments of the present invention is provided with a solar heat collection system, an absorption refrigeration cycle system and a phase change cold storage and cooling system. The solar heat collection system passes through The generator 5 is combined with the absorption refrigeration cycle system, and the absorption refrigeration cycle system is combined with the phase change cold storage and cooling system through the heat exchanger 13; in the solar heat collection system The working fluid thermal oil flows out from the outlet of the heat storage tank 3 and enters the solar collector 1 through the first circulation pump 2. After obtaining heat in the solar collector 1, the high-temperature thermal oil flows from the solar collector 1. The outlet of the heater 1 flows to the heat storage tank 3 to form a circulation loop, and the high-temperature heat transfer oil flows to the generator 5 through the second circulation pump 4 through the first inlet 20 of the generator. In the generator 5 After heating, it returns to the heat storage tank 3 through the first outlet 19 of the generator to form a cycle.

Wherein, the refrigerant used in the absorption refrigeration cycle system is transcritical carbon dioxide, and the absorbent is ionic liquid [bm im]PF ₆ .

Wherein, the refrigerant carbon dioxide in the absorption refrigeration cycle system is in a transcritical state. The transcritical state means that after the refrigerant is heated and precipitated from the generator 5, the high-temperature and high-pressure carbon dioxide is in a supercritical state, After that, high-temperature and high-pressure supercritical carbon dioxide flows into the gas cooler 10 to perform constant-pressure heat release. The constant-pressure heat release process is located in the carbon dioxide supercritical region. At this time, the temperature of the carbon dioxide supercritical fluid is slightly higher than the temperature of the cooling medium (preferably higher than the cooling medium). The temperature of the medium is 2 to 3°C). During the refrigeration cycle flow process, the carbon dioxide temperature at the outlet of the gas cooler is optimal as close as possible to the inlet temperature of the cooling medium. Afterwards, the temperature of the carbon dioxide fluid decreases after exchanging heat with low-temperature and low-pressure carbon dioxide vapor in the regenerator 11, and then enters the second throttle valve 12 for throttling and becomes a low-temperature and low-pressure gas-liquid two-phase flow. Finally, in the The heat exchanger 13 absorbs heat at constant pressure for cold storage. The constant-pressure heat absorption process is carried out in the subcritical region of carbon dioxide. During the cycle of the entire system, the refrigerant carbon dioxide is in a transcritical state. Among them, the supercritical carbon dioxide flowing out of the gas cooler in the regenerator exchanges heat with the low-temperature steam from the heat exchanger. The higher-temperature supercritical carbon dioxide is cooled, reducing the throttling loss of the system and effectively improving the system performance. and cooling capacity.

Wherein, the outdoor normal temperature cooling water flows into the gas cooler 10 through the first inflow pipe 24, and then flows out 25 of the gas cooler 10 through the first outflow pipe.

The outdoor normal-temperature cooling water flows into the absorber 6 through the second inflow pipe 34 , and then flows out of the absorber 6 through the second outflow pipe 33 .

The phase change cold storage system based on the transcritical carbon dioxide absorption refrigeration cycle described in the above embodiments of the present invention, the refrigerant used in the absorption refrigeration cycle system is transcritical carbon dioxide, and the absorbent is ionic liquid [bm im] PF ₆ ; The refrigerant carbon dioxide in the absorption refrigeration cycle system is precipitated from the concentrated solution in the generator 5 after being heated by the high-temperature heat transfer oil in the generator 5. The concentrated solution in the generator 5 After the solution is heated, it becomes a dilute solution. The precipitated high-temperature and high-pressure carbon dioxide flows from the second outlet 21 of the generator to the gas cooler 10 through the first inlet 22 of the gas cooler. The high-temperature and high-pressure carbon dioxide is refrigerated. The pressure of the agent is higher than the critical pressure of carbon dioxide. The high-temperature and high-pressure supercritical carbon dioxide becomes high-pressure and room-temperature supercritical carbon dioxide after heat exchange with the outdoor normal-temperature cooling water in the gas cooler 10. The high-pressure and room-temperature supercritical carbon dioxide After heat exchange with the outdoor normal temperature cooling water, the temperature is slightly higher than the ambient temperature. The high-pressure room temperature supercritical carbon dioxide refrigerant flows from the first outlet 23 of the gas cooler through the first inlet 26 of the regenerator to the gas cooler. The regenerator 11, after exchanging heat with the low-temperature and low-pressure carbon dioxide vapor flowing out from the first outlet 29 of the heat exchanger through the second inlet 30 of the regenerator and flowing to the regenerator 11, , flows out from the first outlet 27 of the regenerator to the second throttle valve 12, and after throttling in the second throttle valve 12, enters the heat exchanger through the first inlet 28. The heat exchanger 13, after absorbing heat and evaporating in the heat exchanger 13, flows out from the first outlet 29 of the heat exchanger and flows to the regenerator 11 through the second inlet 30 of the regenerator. After being heated in the absorber 11, it flows out from the second outlet 31 of the regenerator and flows to the absorber 6 through the first inlet 32 of the absorber. The dilute solution flowing out of the second outlet 38 through the first throttle valve 9 and flowing to the absorber 6 through the second inlet 36 of the absorber is mixed and becomes a concentrated solution. The concentrated solution in the absorber 6 passes through the The first outlet 35 of the absorber flows to the solution pump 8. The heat generated by the reaction in the absorber 6 is taken away by the outdoor normal temperature cooling water. The mixed low-pressure concentrated solution passes through the solution pump 8. The first inlet 37 of the solution heat exchanger flows to the solution heat exchanger 7 , and flows out from the third outlet 42 of the generator through the second inlet 40 of the solution heat exchanger 7 . After heat exchange, the dilute solution flowing to the solution heat exchanger 7 flows out from the first outlet 39 of the solution heat exchanger and returns to the generator 5 through the second inlet 41 of the generator, forming a closed refrigeration cycle. loop. Among them, in the regenerator 11, the supercritical carbon dioxide from the gas cooler 10 and the low-temperature steam from the heat exchanger 13 exchange heat. The supercritical carbon dioxide with a higher temperature is cooled by the low-temperature steam, which reduces the throttling of the system. loss, effectively improving system performance and cooling capacity.

Among them, the phase change cold storage and cooling system also includes the structural design of the heat exchanger. The heat exchanger 13 is designed to be exchanged by a shell 15, a cavity 16, a working fluid water heat exchange channel 17 and a working fluid carbon dioxide 18. The hot channel is composed of four parts; the shell 15 is wrapped with insulation material, the cavity 16 is placed with a phase change material, the phase change material is sodium sulfate decahydrate, and the working medium water heat exchange channel 17 Four of them are provided and evenly arranged inside the cavity in a ring shape. One of the working medium carbon dioxide heat exchange channels 18 is provided and arranged in the middle of the cavity. Compared with the existing common storage heat exchanger, which only has one fluid channel, and requires two working fluids, cold storage and cold, to flow through the same flow channel in order to achieve heat storage and withdrawal. This heat exchanger is inside the cavity. There are four annularly arranged working medium water heat exchange channels and one carbon dioxide heat exchange channel. This structural design enables the two fluids to simultaneously perform cold storage and cold heat exchange processes in the phase change material, making the cold use process It is not limited by time and improves the efficiency of cold energy storage and retrieval.

The indoor air (to be cooled) flows into the water-to-gas heat exchanger 14 through the third inflow pipe 51 , and then flows out of the water-to-gas heat exchanger 14 through the third outflow pipe 52 .

Among them, through the circulating flow of the working fluid water between the phase change material and the water-gas heat exchanger 14, cooling is achieved, and the room temperature (to be cooled) air is cooled and supplied into the room.

The phase change cold storage system based on the transcritical carbon dioxide absorption refrigeration cycle described in the above embodiments of the present invention uses the sodium sulfate decahydrate as the phase change material, and the heat exchanger 13 is designed by The structure is composed of four parts: the shell 15, the cavity 16, the working fluid water heat exchange channel 17 and the working fluid carbon dioxide heat exchange channel 18; the carbon dioxide refrigerant flows from the first inlet 28 of the heat exchanger to the working fluid carbon dioxide exchange channel. The hot channel 18, after absorbing heat and evaporating in the heat exchange channel 18 of the working medium carbon dioxide, flows out from the first outlet 29 of the heat exchanger to achieve refrigeration and reciprocating circulation to achieve continuous cold storage of the phase change material sodium sulfate decahydrate. ; The heat exchanger 13 and the water-gas heat exchanger 14 are both provided with four working fluid water heat exchange channels 17 and are evenly arranged in an annular shape. The working fluid water flows from the water-gas heat exchanger The first outlet 47 and the second outlet 49 of the water-gas heat exchanger flow out through the third inlet 44 and the second inlet 43 of the heat exchanger and enter the heat exchanger 13. After exchanging heat with the sodium sulfate decahydrate in the heat exchanger 13, it becomes low-temperature cold water to achieve cooling. The low-temperature cold water flows out from the third outlet 46 and the second outlet 45 of the heat exchanger through the heat exchanger. The first inlet 48 and the second inlet 50 of the water-gas heat exchanger enter the water-gas heat exchanger 14, and the indoor air (to be cooled) flows from the third inflow pipe 51 flows to the water-to-gas heat exchanger 14, where it exchanges heat with the low-temperature cold water and becomes cold air, flows out through the third outflow pipe 52 and is supplied into the room.

This system has three working modes, including: refrigeration and cooling mode, refrigeration and cold storage mode, and cold storage and cooling mode.

Before using the device, a pre-cooling stage must be started. The first stop valve 53 and the second stop valve 54 are opened, the solar heat collection system is working, and the first water supply valve 55, the second water supply valve 56, and the third water supply valve are The valve 57 and the fourth water supply valve 58 are closed, and no cooling is provided for domestic use. The heat collecting plate 1 in the solar heat collecting system circulates and heats the heat transfer oil working fluid in the system by recovering solar radiation, and stores the heat in the heat storage tank 3. The high temperature heat transfer oil in the heat storage tank 3 is supplied to The generator 5 cools the absorption refrigeration cycle system, and the cold generated is stored in the phase change material of the heat exchanger 13. When the temperature of the sodium sulfate decahydrate in the phase change cold storage and cooling system is lower than about 6°C, a phase change occurs. When the start-up pre-cooling phase is completed, the system will enter the working mode.

Refrigeration and cooling mode, the first stop valve 53 and the second stop valve 54 are open, the solar heat collection system is working, the first water supply valve 55, the second water supply valve 56, the third water supply valve 57 and the fourth water supply valve 58 opens, providing life with cold. When the temperature of the heat transfer oil measured in the heat storage tank 3 is higher than 80°C, the stored heat transfer oil is supplied to the generator 5 through the second circulation pump 4, so that the absorption refrigeration system circulates refrigeration, and the generated cold energy is transferred to In the heat exchanger 13, the heat exchanger 13 transfers the cold energy to the working fluid water in the loop, and the working fluid water exchanges heat with the air flowing in through the third inflow pipe 51 under the action of the water-gas heat exchanger. And the cold air is sent into the indoor end through the third outflow pipe 52.

In the refrigeration and cold storage mode, when the solar radiation is sufficient during the day, but there is no cooling demand or the output cooling capacity exceeds demand, on the basis of the refrigeration and cooling supply mode as mentioned above, the first water supply valve 55, The second water supply valve 56, the third water supply valve 57 and the fourth water supply valve 58 are closed and do not provide domestic cooling. The cold energy generated by the absorption refrigeration cycle system is stored in the phase change material of the heat exchanger 13. The amount of stored cold energy is related to the structural size of the heat exchanger and the selection of the phase change material.

In the cold storage and cooling mode, in order to prevent the heat stored in the thermal storage tank 3 from being lost through radiation through the heat collector 1 during other periods of poor solar radiation at night or on cloudy days, based on the cooling and cooling mode as mentioned above On, the first stop valve 53 and the second stop valve 54 are closed, and the solar heat collection system is closed. The cold energy stored in the phase change material in the heat exchanger 13 is transferred to the water-gas heat exchanger through the working fluid water in the loop. In the water-gas heat exchanger, the working fluid water transfers the cold energy to the third phase. The air flowing in from the inflow pipe 51 is sent to the indoor end through the third outflow pipe 52 .

The phase change cold storage system based on the transcritical carbon dioxide absorption refrigeration cycle described in the above embodiments of the present invention is provided with a solar heat collection system, an absorption refrigeration cycle system and a phase change cold storage and cooling system. The absorption refrigeration cycle system is based on The transcritical carbon dioxide is the refrigerant and the ionic liquid [bm im] PF ₆ is the absorbent. The phase change cold storage and cooling system uses the sodium sulfate decahydrate as the phase change material. The regenerator 11 The setting can effectively reduce the temperature of the refrigerant entering the second throttle valve 12 and reduce throttling losses; the solar heat collection system is combined with the absorption refrigeration cycle system through the generator, and the The absorption refrigeration cycle system is combined with the phase change cold storage and cooling system through the heat exchanger, and achieves efficient utilization of energy by combining transcritical carbon dioxide refrigeration technology, solar heating technology and phase change cold storage technology. , which integrates cold storage for refrigeration, breaks the time and space constraints of cooling, has the advantages of environmental friendliness, sustainability, compact structure, etc., is of great significance to energy saving and carbon reduction, and has broad application prospects.

The above embodiments are only for illustrating the technical concepts and characteristics of the present invention. Their purpose is to enable those familiar with this technology to understand the content of the present invention and implement it accordingly. They cannot limit the scope of protection of the present invention. All equivalent changes or modifications made based on the spirit and essence of the present invention should be included in the protection scope of the present invention.

Claims (5)

1. The phase change cold accumulation system based on the transcritical carbon dioxide absorption refrigeration cycle comprises a solar heat collection system, an absorption refrigeration cycle system and a phase change cold accumulation cold release system;

the solar heat collection system is connected with the absorption refrigeration cycle system and is used for providing solar energy for the absorption refrigeration cycle system, and the absorption refrigeration cycle system is connected with the phase-change cold accumulation and release system and is used for providing refrigeration for the phase-change cold accumulation and release system;

the solar heat collection system comprises a solar heat collector, a first circulating pump and a heat storage tank; the outlet of the first circulating pump is communicated with the inlet of the solar heat collector, and the outlet of the solar heat collector is communicated with the inlet of the heat storage tank;

the absorption refrigeration cycle system comprises a generator, an absorber, a solution heat exchanger, a solution pump, a first throttle valve, a gas cooler, a heat regenerator, a second throttle valve and a heat exchanger; the first outlet of the generator is communicated with the inlet of the heat storage tank, the second circulating pump is communicated with the first inlet of the generator, the second outlet of the generator is communicated with the inlet of the gas cooler, the first outlet of the gas cooler is communicated with the first inlet of the heat regenerator, the first outlet of the heat regenerator is communicated with the inlet of the second throttle valve, the outlet of the second throttle valve is communicated with the first inlet of the heat exchanger, the first outlet of the heat exchanger is communicated with the second inlet of the heat regenerator, the second outlet of the heat regenerator is communicated with the first inlet of the absorber, the first outlet of the absorber is communicated with the inlet of the solution pump, the outlet of the solution pump is communicated with the first inlet of the solution heat exchanger, the first outlet of the solution heat exchanger is communicated with the second inlet of the generator, the third outlet of the generator is communicated with the second inlet of the solution heat exchanger, the second outlet of the solution heat exchanger is communicated with the inlet of the first throttle valve, and the outlet of the first throttle valve is communicated with the second inlet of the absorber; the carbon dioxide of the refrigerant in the absorption refrigeration cycle system is in a transcritical state, wherein the transcritical state refers to that when the pressure of the refrigerant separated out from the generator is higher than the critical pressure of the carbon dioxide, then high-temperature high-pressure supercritical carbon dioxide flows into the gas cooler to release heat, the temperature of the supercritical carbon dioxide fluid is cooled to be close to the ambient temperature, then the temperature of the carbon dioxide fluid is reduced after heat exchange with low-temperature low-pressure carbon dioxide vapor in the heat regenerator, then the carbon dioxide fluid enters the second throttling valve to be throttled and then becomes a low-temperature low-pressure gas-liquid two-phase flow, finally heat is absorbed in the heat exchanger to store heat, and the carbon dioxide of the refrigerant is in the transcritical state in the whole cycle.

2. The phase-change cold storage system based on a transcritical carbon dioxide absorption refrigeration cycle according to claim 1, wherein the phase-change cold storage and release system comprises a heat exchanger and a water-gas heat exchanger; an inlet and an outlet are arranged on the heat exchanger, and an inlet, an outlet, a third inflow pipeline and a third outflow pipeline are arranged on the water-gas heat exchanger; the inlet and the outlet on the heat exchanger are respectively connected with the outlet and the inlet of the water-gas heat exchanger.

3. The phase change cold storage system based on transcritical carbon dioxide absorption refrigeration cycle as set forth in claim 1, wherein working medium conduction oil in the solar heat collection system flows out from an outlet of a heat storage tank, enters the solar heat collector through the first circulating pump, after heat is obtained in the solar heat collector, high temperature conduction oil flows from the outlet of the solar heat collector to the heat storage tank to form a circulating loop, the high temperature conduction oil flows to the generator through a first inlet of the generator through the second circulating pump, and returns to the heat storage tank through a first outlet of the generator to form a circulation after being heated in the generator.

4. The phase-change cold storage system based on transcritical carbon dioxide absorption refrigeration cycle as set forth in claim 1, wherein carbon dioxide as refrigerant in said absorption refrigeration cycle system is separated out from concentrated solution in said generator after being heated by high temperature conduction oil in said generator, said concentrated solution in said generator is changed into a dilute solution after being heated, said separated high temperature and high pressure carbon dioxide flows out from said generator second outlet to said gas cooler, pressure of said high temperature and high pressure carbon dioxide refrigerant is higher than critical pressure of carbon dioxide, said high temperature and high pressure supercritical carbon dioxide becomes high pressure room temperature supercritical carbon dioxide after being heat exchanged with outdoor normal temperature cooling water in said gas cooler, said high pressure room temperature supercritical carbon dioxide becomes high pressure room temperature supercritical carbon dioxide after being heat exchanged with said outdoor normal temperature cooling water, said high pressure room temperature supercritical carbon dioxide refrigerant enters said regenerator, after being heat exchanged with low temperature low pressure carbon dioxide vapor flowing out from said heat exchanger into said regenerator, said second outlet to said gas cooler, said high pressure supercritical carbon dioxide refrigerant enters said regenerator after being heat exchanged with said outdoor temperature conduction oil, said low pressure supercritical carbon dioxide refrigerant enters said regenerator after being heat exchanged with said outdoor temperature heat conduction oil, said low pressure supercritical carbon dioxide refrigerant enters said regenerator, said dilute carbon dioxide refrigerant enters said regenerator after being mixed solution after flowing out from said heat exchanger, said low pressure supercritical carbon dioxide refrigerant enters said heat absorber after being absorbed in said heat exchanger, and the solution flows from the solution pump to the solution heat exchanger, exchanges heat with the dilute solution flowing from the generator to the solution heat exchanger in the solution heat exchanger, flows out of the first outlet of the solution heat exchanger, and returns to the generator through the second inlet of the generator to form a refrigeration closed circulation loop.

5. The phase change cold storage system based on transcritical carbon dioxide absorption refrigeration cycle as set forth in claim 1, wherein said heat exchanger comprises a housing, a cavity, a working medium water heat exchange channel and a working medium carbon dioxide heat exchange channel; the heat-insulating material is wrapped around the shell, the phase-change material is placed in the cavity, the phase-change material adopts sodium sulfate decahydrate, four working medium water heat exchange channels are arranged and are uniformly arranged in the cavity in an annular mode, and one working medium carbon dioxide heat exchange channel is arranged and is arranged in the middle of the cavity.