A dual-effect lithium bromide absorption cooling and power cogeneration system utilizing waste heat from fuel cells

Abstract

The present invention discloses a dual-effect lithium bromide absorption-type combined cooling and power supply system that utilizes fuel cell waste heat. The system comprises a fuel cell system and a dual-effect lithium bromide absorption-type combined cooling and power supply system. The fuel cell system and the dual-effect lithium bromide absorption-type combined cooling and power supply system are coupled via a high-voltage generator. The dual-effect lithium bromide absorption-type combined cooling and power supply system is characterized by combining a dual-effect lithium bromide absorption refrigeration cycle with a power cycle. The system can be switched between power supply mode, cooling mode, or combined cooling and power supply mode by adjusting the opening of a first diverter valve and a second diverter valve. This fully utilizes the fuel cell waste heat for power generation and cooling, meeting various user needs and improving energy utilization efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cell waste heat utilization, and in particular to a double-effect lithium bromide absorption type cooling and power cogeneration system utilizing fuel cell waste heat. Background Art

[0002] As global energy consumption continues to rise, traditional energy resources are gradually decreasing, and the contradiction between energy supply and demand is becoming increasingly prominent. Furthermore, traditional energy utilization is inefficient, resulting in significant energy waste. Distributed energy systems, centered around fuel cell combined cooling and power, are a clean and efficient way to utilize energy, potentially alleviating the energy crisis. Fuel cells generate a large amount of heat during power generation, and fully utilizing this heat can improve energy efficiency.

[0003] Using waste heat to drive an absorption chiller for cooling is an effective way to utilize fuel cell waste heat, but users' demand for cooling varies seasonally, and there is no guarantee that the equipment will be effectively utilized throughout the year. Power cycles such as the organic Rankine cycle have much room for improvement in performance when utilizing low-grade waste heat.

[0004] Therefore, it is necessary to propose a system that can fully utilize the waste heat of fuel cells and improve energy utilization efficiency. Summary of the Invention

[0005] The purpose of the present invention is to address the defects of the existing technology and provide a dual-effect lithium bromide absorption cooling and power cogeneration system that utilizes the waste heat of fuel cells, so as to solve the problem of single utilization of fuel cell waste heat and low energy utilization efficiency, ensure full utilization of waste heat throughout the year, and improve energy utilization efficiency.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] A double-effect lithium bromide absorption-type cooling and power cogeneration system utilizing waste heat from a fuel cell, characterized in that it comprises a coupled fuel cell system and a double-effect lithium bromide absorption-type cooling and power cogeneration system, wherein the double-effect lithium bromide absorption-type cooling and power cogeneration system comprises a lithium bromide aqueous solution circulation system, a power generation system, and a refrigeration system;

[0008] The fuel cell system is connected to the lithium bromide aqueous solution circulation system, and the waste heat generated by the fuel cell system is input into the lithium bromide aqueous solution circulation system to evaporate water in the lithium bromide aqueous solution into water vapor;

[0009] The lithium bromide aqueous solution circulation system is connected to the power generation system and the refrigeration system through a diverter valve and a merging valve, and is used to provide water vapor to the power generation system and liquid water to the refrigeration system;

[0010] The power generation system utilizes the water vapor generated by the lithium bromide aqueous solution circulation system to drive the expander to generate electricity;

[0011] The refrigeration system utilizes liquid water generated by a lithium bromide aqueous solution circulation system for refrigeration;

[0012] By adjusting the opening of the diverter valve, the power supply mode, cooling mode and cooling and power combined supply mode of the system can be realized respectively.

[0013] Furthermore, the lithium bromide aqueous solution circulation system includes a high-pressure generator, a low-pressure generator, an absorber, a solution pump, a first throttle valve, and a fourth throttle valve. The power generation system includes a first diverter valve, a second diverter valve, a high-pressure expander, a low-pressure expander, a first merging valve, and a second merging valve. The refrigeration system includes a second throttle valve, a condenser, a third throttle valve, and an evaporator. The high-pressure generator, the first throttle valve, the low-pressure generator, the fourth throttle valve, the absorber, the solution pump, and the high-pressure generator are sequentially connected end to end to form a lithium bromide aqueous solution circulation loop. The fuel cell system is connected to the high-pressure generator through a coolant circulation loop and transfers heat. The water vapor outlet of the high-pressure generator is connected to the first throttle valve. The inlet of a diverter valve, the two outlets of the first diverter valve are respectively connected to the inlet of the high-pressure expander and the high-pressure water vapor inlet of the low-pressure generator, the low-pressure water vapor outlet of the low-pressure generator is connected to the inlet of the second diverter valve, the two outlets of the second diverter valve are respectively connected to the inlet of the low-pressure expander and the inlet of the condenser, the liquid water outlet of the low-pressure generator is connected to the second throttle valve and the inlet of the condenser in sequence, the condenser outlet is connected to the third throttle valve and the evaporator in sequence, the outlet of the low-pressure expander and the outlet of the evaporator are merged through the first merging valve and then connected to the inlet of the second merging valve, the outlet of the high-pressure expander is connected to the other inlet of the second merging valve, and the outlet of the second merging valve is connected to the water inlet of the absorber.

[0014] Furthermore, the lithium bromide aqueous solution circulation system also includes a low-temperature solution heat exchanger, the cold side inlet and outlet of the low-temperature solution heat exchanger are respectively connected to the solution pump outlet and the high-pressure generator solution inlet, and the hot side inlet and outlet of the low-temperature solution heat exchanger are respectively connected to the low-pressure generator solution outlet and the fourth throttle valve inlet.

[0015] Furthermore, the lithium bromide aqueous solution circulation system also includes a high-temperature solution heat exchanger, the cold side inlet and outlet of the high-temperature solution heat exchanger are respectively connected to the cold side outlet of the low-temperature solution heat exchanger and the high-pressure generator solution inlet, and the hot side inlet and outlet of the high-temperature solution heat exchanger are respectively connected to the high-pressure generator solution outlet and the first throttle valve inlet.

[0016] Furthermore, the fuel cell system includes a fuel cell stack, which is provided with a hydrogen inlet, an air inlet, and an air outlet. The fuel cell stack is connected to the high-voltage generator through the coolant circulation loop, and a circulation pump is provided in the coolant circulation loop.

[0017] Furthermore, the fuel cell system includes a hydrogen pump, the inlet and outlet of the hydrogen pump are respectively connected to the anode and the hydrogen inlet of the fuel cell stack.

[0018] Furthermore, the fuel cell system includes an air preheater, which is arranged between the air inlet and the air outlet.

[0019] Furthermore, in the power supply mode, all the water vapor generated by the high-pressure generator flows to the high-pressure expander through the first diverter valve; in the cooling mode, all the water vapor generated by the high-pressure generator first flows to the low-pressure generator through the first diverter valve to condense and release heat, and then flows to the condenser, and the water vapor generated by the low-pressure generator flows to the condenser through the second diverter valve; in the cooling and power combined supply mode, the water vapor generated by the high-pressure generator flows partly to the high-pressure expander through the first diverter valve and partly flows to the low-pressure generator, and the low-pressure water vapor passing through the second diverter valve flows partly to the low-pressure expander and partly to the condenser.

[0020] Compared with the existing technology, the beneficial effects of the present invention are: utilizing the waste heat of the fuel cell to drive the double-effect lithium bromide absorption combined cooling and power supply system to meet the user's electricity and refrigeration needs; compared with the single-effect absorption refrigeration system, the double-effect lithium bromide absorption combined cooling and power supply system can provide more water vapor, so that more water vapor enters the expander to perform work, and more refrigerant water enters the evaporator to absorb heat, thereby improving energy utilization efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic structural diagram of an embodiment of the present invention;

[0022] Among them: 1-fuel cell stack; 2-hydrogen pump; 3-air preheater; 4-circulating pump; 5-high-pressure generator; 6-first throttle valve; 7-first diverter valve; 8-low-pressure generator; 9-second throttle valve; 10-second diverter valve; 11-condenser; 12-high-pressure expander; 13-low-pressure expander; 14-third throttle valve; 15-evaporator; 16-first merging valve; 17-second merging valve; 18-absorber; 19-solution pump; 20-low-temperature solution heat exchanger; 21-high-temperature solution heat exchanger; 22-fourth throttle valve; 23-coolant circulation loop; 24-hydrogen inlet; 25-air inlet; 26-air outlet; 27-cooling loop. DETAILED DESCRIPTION

[0023] In order to deepen the understanding of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings. The embodiments are only used to explain the present invention and do not constitute a limitation on the scope of protection of the present invention.

[0024] Figure 1 A specific embodiment of a double-effect lithium bromide absorption cooling and power cogeneration system utilizing waste heat from a fuel cell is shown, comprising a coupled fuel cell system and a double-effect lithium bromide absorption cooling and power cogeneration system, wherein the double-effect lithium bromide absorption cooling and power cogeneration system comprises a lithium bromide aqueous solution circulation system, a power generation system, and a refrigeration system.

[0025] The circulating working fluid of the lithium bromide aqueous solution circulation system is lithium bromide aqueous solution.

[0026] The lithium bromide aqueous solution circulation system includes a high-pressure generator 5, a low-pressure generator 8, an absorber 18, a solution pump 19, a first throttle valve 6, a fourth throttle valve 22, a low-temperature solution heat exchanger 20, and a high-temperature solution heat exchanger 21. The power generation system includes a first diverter valve 7, a second diverter valve 10, a high-pressure expander 12, a low-pressure expander 13, a first combining valve 16, and a second combining valve 17. The refrigeration system includes a second throttle valve 9, a condenser 11, a third throttle valve 14, and an evaporator 15. The high-pressure generator 5, the first throttle valve 6, the low-pressure generator 8, the fourth throttle valve 22, the absorber 18, the solution pump 19, and the high-pressure generator 5 are connected end-to-end to form a lithium bromide aqueous solution circulation loop. The cold-side inlet and outlet of the low-temperature solution heat exchanger 20 are connected to the outlet of the solution pump 19 and the cold-side inlet of the high-temperature solution heat exchanger 21, respectively. The hot-side inlet and outlet of the low-temperature solution heat exchanger 20 are connected to the solution outlet of the low-pressure generator 8 and the inlet of the fourth throttle valve 22, respectively. The cold side inlet and outlet of the high-temperature solution heat exchanger 21 are respectively connected to the cold side outlet 20 of the low-temperature solution heat exchanger and the solution inlet of the high-pressure generator 5, and the hot side inlet and outlet of the high-temperature solution heat exchanger 21 are respectively connected to the solution outlet of the high-pressure generator 5 and the inlet of the first throttle valve 6. The fuel cell system is connected to the high-pressure generator 5 through the coolant circulation loop 23 and transfers heat. The water vapor outlet of the high-pressure generator 5 is connected to the inlet of the first diverter valve 7. The two outlets of the first diverter valve 7 are respectively connected to the inlet of the high-pressure expander 12 and the high-pressure water vapor inlet of the low-pressure generator 8. The low-pressure water vapor outlet of the low-pressure generator 8 is connected to the inlet of the second diverter valve 10. The two outlets of the second diverter valve 10 are respectively connected to the inlet of the low-pressure expander 13 and the inlet of the condenser 11. The liquid water outlet of the low-pressure generator 8 is connected to the second throttle valve 9 and the inlet of the condenser 11 in sequence. The outlet of the condenser 11 is connected to the third throttle valve 14 and the evaporator 15 in sequence. The outlet of the low-pressure expander 13 and the outlet of the evaporator 15 are merged through the first merging valve 16 and connected to the inlet of the second merging valve 17. The outlet of the high-pressure expander 12 is connected to the other inlet of the second merging valve 17. The outlet of the second merging valve 17 is connected to the water inlet of the absorber 18.

[0027] The high-voltage generator 5 is used to heat the low-concentration lithium bromide aqueous solution, causing water to evaporate from the low-concentration lithium bromide aqueous solution, thereby converting the low-concentration lithium bromide aqueous solution into a saturated lithium bromide aqueous solution of intermediate concentration. The first throttle valve 6 is used to throttle and reduce the pressure of the saturated lithium bromide aqueous solution of intermediate concentration.

[0028] The water vapor generated by the high-pressure generator 5 condenses and releases heat in the low-pressure generator 8, heating the intermediate concentration saturated lithium bromide aqueous solution after throttling and depressurization, so that the intermediate concentration saturated lithium bromide aqueous solution after throttling and depressurization is further separated into water vapor and high concentration lithium bromide aqueous solution.

[0029] The high-pressure expander 12 utilizes the water vapor generated by the high-pressure generator 5 to expand and perform work, thereby driving the generator to generate electricity; the low-pressure expander 13 utilizes the water vapor generated by the low-pressure generator 8 to expand and perform work, thereby driving the generator to generate electricity.

[0030] The high-pressure steam generated by the high-pressure generator 5 condenses and releases heat in the low-pressure generator 8 , and then passes through the second throttle valve 9 to reduce the pressure and enter the condenser 11 .

[0031] The fuel cell system includes a fuel cell stack 1, a hydrogen pump 2, an air preheater 3, and a circulation pump 4. The fuel cell stack 1 uses hydrogen and oxygen in the air to undergo an electrochemical reaction, generating electricity and heat. The hydrogen pump 2 is connected to the anode terminal of the fuel cell stack 1 and the hydrogen inlet 24 to recover hydrogen that has not participated in the reaction. The air preheater 3 is connected to the air inlet 25 and air outlet 26 on the fuel cell stack 1, using the high-temperature air discharged from the cathode outlet of the fuel cell stack 1 to preheat the air entering the cathode. The circulation pump 4 is located in the coolant circulation loop 23 and is used to drive the coolant to circulate between the fuel cell stack 1 and the high-voltage generator 5 to transfer heat.

[0032] The flow path of the lithium bromide aqueous solution is: high-pressure generator 5-high-temperature solution heat exchanger 21-first throttle valve 6-low-pressure generator 8-low-temperature heat exchanger 20-fourth throttle valve 22-absorber 18-solution pump 19-low-temperature solution heat exchanger 20-high-temperature solution heat exchanger 21-high-pressure generator 5.

[0033] The water flow cycle is:

[0034] Route a: high-pressure generator 5 - first diverter valve - 7 high-pressure expander 12 - second combining valve 17 - absorber 18;

[0035] Route b: high-pressure generator 5 - first diverter valve 7 - low-pressure generator 8 - second throttle valve 9 - condenser 11 - third throttle valve 17 - evaporator 15 - first combining valve 16 - second combining valve 17 - absorber 18;

[0036] Route c: low-pressure generator 8 - second diverter valve 10 - low-pressure expander 13 - first combining valve 16 - second combining valve 17 - absorber 18;

[0037] Route d: low-pressure generator 8 - second diverter valve 10 - condenser 11 - third throttle valve 17 - evaporator 15 - first combining valve 16 - second combining valve 17 - absorber 18 .

[0038] The working modes based on the above embodiment include: power supply mode, cooling mode and combined cooling and power supply mode.

[0039] The working medium circulation process of the power supply mode is as follows: the coolant heats the low-concentration lithium bromide aqueous solution in the high-pressure generator 5 to produce an intermediate-concentration saturated lithium bromide aqueous solution and high-pressure water vapor; the opening of the first diverter valve 7 is adjusted to allow all the high-pressure water vapor to enter the high-pressure expander 12 to expand and work to drive the generator to generate electricity, and the low-pressure water vapor after expansion enters the absorber 18; the intermediate-concentration saturated lithium bromide aqueous solution enters the high-temperature solution heat exchanger 21 to preheat the low-concentration lithium bromide aqueous solution, and after heat exchange, the intermediate-concentration saturated lithium bromide aqueous solution enters the first throttle valve 6 for throttling and pressure reduction, and the intermediate-concentration lithium bromide aqueous solution after pressure reduction enters the low-pressure generator 8. Since there is no heat source in the low-pressure generator 8 to heat the intermediate-concentration lithium bromide, the intermediate-concentration lithium bromide aqueous solution enters the high-temperature solution heat exchanger 21 to preheat the low-concentration lithium bromide aqueous solution. aqueous solution, so the concentration of the intermediate-concentration lithium bromide aqueous solution does not change, the intermediate-concentration lithium bromide aqueous solution enters the low-temperature solution heat exchanger 20 to preheat the low-concentration lithium bromide aqueous solution, and the intermediate-concentration lithium bromide aqueous solution after heat exchange enters the fourth throttle valve 22 for throttling and pressure reduction. The intermediate-concentration lithium bromide aqueous solution after pressure reduction enters the absorber 18, absorbs the low-pressure water vapor from the high-pressure expander 12, and produces a low-concentration lithium bromide aqueous solution; the low-concentration lithium bromide aqueous solution enters the solution pump 19 for pressurization, and the pressurized low-concentration lithium bromide aqueous solution enters the low-temperature solution heat exchanger 20 and the high-temperature solution heat exchanger 21 in turn for preheating. The preheated low-concentration lithium bromide aqueous solution enters the high-pressure generator 5 to complete the cycle.

[0040] The working medium circulation process of the cooling mode is as follows: the coolant heats the low-concentration lithium bromide aqueous solution in the high-pressure generator 5 to produce an intermediate-concentration saturated lithium bromide aqueous solution and high-pressure water vapor; the opening of the first diverter valve 7 is adjusted so that all the high-pressure water vapor enters the low-pressure generator 8 to heat the concentrated solution by condensation heat release, and the condensed high-pressure liquid water passes through the second throttle valve 9 for throttling and pressure reduction, and enters the condenser 11; the intermediate-concentration saturated lithium bromide aqueous solution enters the high-temperature solution heat exchanger 21 to preheat the low-concentration lithium bromide aqueous solution, and after heat exchange, the intermediate-concentration saturated lithium bromide aqueous solution enters the first throttle valve 6 for throttling and pressure reduction, and the intermediate-concentration lithium bromide aqueous solution after pressure reduction enters the low-pressure generator 8 to further separate water vapor and high-concentration lithium bromide aqueous solution; the opening of the second diverter valve 10 is adjusted so that all the water vapor The gas enters the condenser 11 to condense and release heat; the condensed liquid water enters the third throttle valve 14 for throttling and reducing the pressure, and the liquid water after reducing the pressure enters the evaporator 15 to evaporate and absorb heat, thereby providing cooling for the user; the high-concentration lithium bromide aqueous solution enters the low-temperature solution heat exchanger 20 to preheat the low-concentration lithium bromide aqueous solution, and the high-concentration lithium bromide aqueous solution after heat exchange enters the fourth throttle valve 22 for throttling and reducing the pressure, and the high-concentration lithium bromide aqueous solution after reducing the pressure enters the absorber 18 to absorb water vapor from the evaporator 15 to produce a low-concentration lithium bromide aqueous solution; the low-concentration lithium bromide aqueous solution enters the solution pump 19 for pressurization, and the pressurized low-concentration lithium bromide aqueous solution enters the low-temperature solution heat exchanger 20 and the high-temperature solution heat exchanger 21 in turn for preheating, and the preheated low-concentration lithium bromide aqueous solution enters the high-pressure generator 5 to complete the cycle.

[0041] The working medium circulation process of the cooling and power cogeneration mode is as follows: the coolant heats the low-concentration lithium bromide aqueous solution in the high-pressure generator 5 to produce an intermediate-concentration saturated lithium bromide aqueous solution and high-pressure water vapor; by adjusting the opening of the first diverter valve 7, part of the high-pressure water vapor enters the high-pressure expander 12 to expand and do work to drive the generator to generate electricity, and the water vapor after expansion enters the absorber 18; part of the high-pressure water vapor enters the low-pressure generator 8 to heat the concentrated solution by condensation and heat release, and the condensed high-pressure liquid water passes through the second throttle valve 9 to throttle and reduce the pressure and enter the condenser 11; the intermediate-concentration saturated lithium bromide aqueous solution enters the high-temperature solution heat exchanger 21 to preheat the low-concentration lithium bromide aqueous solution, and after heat exchange, the intermediate-concentration saturated lithium bromide aqueous solution enters the first throttle valve 6 to throttle and reduce the pressure, and the intermediate-concentration lithium bromide aqueous solution after pressure reduction enters the low-pressure generator 8 to further separate water vapor and high-concentration lithium bromide aqueous solution; by adjusting the opening of the second diverter valve 10, part of the water vapor enters the low-pressure generator 8 to heat the concentrated solution by condensation and heat release, and the condensed high-pressure liquid water passes through the second throttle valve 9 to throttle and reduce the pressure, and enters the condenser 11; the intermediate-concentration saturated lithium bromide aqueous solution enters the high-temperature solution heat exchanger 21 to preheat the low-concentration lithium bromide aqueous solution, and after heat exchange, the intermediate-concentration saturated lithium bromide aqueous solution enters the first throttle valve 6 to throttle and reduce the pressure, and the intermediate-concentration lithium bromide aqueous The high-pressure expander 13 expands and performs work, driving the generator to generate electricity. The water vapor after the expansion work enters the absorber 18; part of the water vapor enters the condenser 11 to condense and release heat; the condensed liquid water enters the third throttle valve 14 for throttling and pressure reduction, and the liquid water after pressure reduction enters the evaporator 15 to evaporate and absorb heat, providing cooling for users; the high-concentration lithium bromide aqueous solution enters the low-temperature solution heat exchanger 20 to preheat the low-concentration lithium bromide aqueous solution. The high-concentration lithium bromide aqueous solution after heat exchange enters the fourth throttle valve 22 for throttling and pressure reduction, and the high-concentration lithium bromide aqueous solution after pressure reduction enters the absorber 18, which absorbs water vapor from the high-pressure expander 12, the low-pressure expander 13 and the evaporator 15 to produce a low-concentration lithium bromide aqueous solution; the low-concentration lithium bromide aqueous solution enters the solution pump 19 for pressurization, and the pressurized low-concentration lithium bromide aqueous solution enters the low-temperature solution heat exchanger 20 and the high-temperature solution heat exchanger 21 in sequence for preheating. The preheated low-concentration lithium bromide aqueous solution enters the high-pressure generator 5, completing the cycle. By adjusting the opening of the first diverter valve 7 and the second diverter valve 10, the ratio of the working fluid distributed to the evaporator and the expander can be controlled, thereby adjusting the cooling capacity and power generation.

[0042] The above specific implementation methods are only for illustrating the technical concept and structural features of the present invention, and the purpose is to enable relevant persons familiar with this technology to implement them accordingly. However, the above content does not limit the scope of protection of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should fall within the scope of protection of the present invention.

Claims

1. A dual-effect lithium bromide absorption cooling and power cogeneration system utilizing waste heat from fuel cells, characterized by: The double-effect lithium bromide absorption cooling and power cogeneration system includes a lithium bromide aqueous solution circulation system, a power generation system, a refrigeration system, and a fuel cell system; The fuel cell system is connected to the lithium bromide aqueous solution circulation system, and the waste heat generated by the fuel cell system is input into the lithium bromide aqueous solution circulation system to evaporate water in the lithium bromide aqueous solution into water vapor; The lithium bromide aqueous solution circulation system is connected to the power generation system and the refrigeration system through a diverter valve and a merging valve, and is used to provide water vapor to the power generation system and liquid water to the refrigeration system; The power generation system utilizes the water vapor generated by the lithium bromide aqueous solution circulation system to drive the expander to generate electricity; The refrigeration system utilizes liquid water generated by a lithium bromide aqueous solution circulation system for refrigeration; By adjusting the opening of the diverter valve, the system can be operated in power supply mode, cooling mode and combined cooling and power supply mode respectively; The lithium bromide aqueous solution circulation system comprises a high-pressure generator (5), a low-pressure generator (8), an absorber (18), a solution pump (19), a first throttle valve (6), and a fourth throttle valve (22); the power generation system comprises a first diverter valve (7), a second diverter valve (10), a high-pressure expander (12), a low-pressure expander (13), a first merging valve (16), and a second merging valve (17); the refrigeration system comprises a second throttle valve (9), a condenser (11), a third throttle valve (14), and an evaporator (15); the high-pressure generator (5), the first throttle valve (6), the low-pressure generator (8), the fourth throttle valve (22), the absorber (18), the solution pump (19), and the high-pressure generator (5) are sequentially connected end to end to form a lithium bromide aqueous solution circulation loop; the fuel cell system is connected to the high-pressure generator (5) through a coolant circulation loop and transfers heat; the water vapor outlet of the high-pressure generator (5) is connected to the first The inlet of the diverter valve (7) and the two outlets of the first diverter valve (7) are respectively connected to the inlet of the high-pressure expander (12) and the high-pressure water vapor inlet of the low-pressure generator (8); the low-pressure water vapor outlet of the low-pressure generator (8) is connected to the inlet of the second diverter valve (10); the two outlets of the second diverter valve (10) are respectively connected to the inlet of the low-pressure expander (13) and the inlet of the condenser (11); the liquid water outlet of the low-pressure generator (8) is sequentially connected to the second throttle valve (9) and the inlet of the condenser (11); the outlet of the condenser (11) is sequentially connected to the third throttle valve (14) and the evaporator (15); the outlet of the low-pressure expander (13) and the outlet of the evaporator (15) are connected to the inlet of the second merging valve (17) after merging through the first merging valve (16); the outlet of the high-pressure expander (12) is connected to the other inlet of the second merging valve (17); and the outlet of the second merging valve (17) is connected to the water inlet of the absorber (18); In the power supply mode, all the water vapor generated by the high-pressure generator (5) flows to the high-pressure expander (12) through the first diverter valve (7); in the cooling mode, all the water vapor generated by the high-pressure generator (5) first flows to the low-pressure generator (8) through the first diverter valve (7) to condense and release heat, and then flows to the condenser (11), and the water vapor generated by the low-pressure generator flows to the condenser (11) through the second diverter valve (10); in the cooling and power combined supply mode, the water vapor generated by the high-pressure generator (5) flows partly to the high-pressure expander (12) and partly to the low-pressure generator (8) through the first diverter valve (7), and the low-pressure water vapor that flows through the second diverter valve (10) flows partly to the low-pressure expander (13) and partly to the condenser (11).

2. The dual-effect lithium bromide absorption cooling and power cogeneration system utilizing fuel cell waste heat according to claim 1, characterized in that: The lithium bromide aqueous solution circulation system further includes a low-temperature solution heat exchanger (20), wherein the cold side inlet and outlet of the low-temperature solution heat exchanger (20) are respectively connected to the outlet of the solution pump (19) and the solution inlet of the high-pressure generator (5), and the hot side inlet and outlet of the low-temperature solution heat exchanger (20) are respectively connected to the solution outlet of the low-pressure generator (8) and the inlet of the fourth throttle valve (22).

3. The dual-effect lithium bromide absorption cooling and power cogeneration system utilizing waste heat from fuel cells according to claim 2, characterized in that: The lithium bromide aqueous solution circulation system further includes a high-temperature solution heat exchanger (21), wherein the cold side inlet and outlet of the high-temperature solution heat exchanger (21) are respectively connected to the cold side outlet of the low-temperature solution heat exchanger (20) and the solution inlet of the high-pressure generator (5), and the hot side inlet and outlet of the high-temperature solution heat exchanger (21) are respectively connected to the solution outlet of the high-pressure generator (5) and the inlet of the first throttle valve (6).

4. The dual-effect lithium bromide absorption cooling and power cogeneration system utilizing waste heat from fuel cells according to claim 1, characterized in that: The fuel cell system comprises a fuel cell stack (1), wherein the fuel cell stack (1) is provided with a hydrogen inlet (24), an air inlet (25), and an air outlet (26); the fuel cell stack (1) is connected to the high-voltage generator (5) via the coolant circulation loop (23); and a circulation pump (4) is provided in the coolant circulation loop (23).

5. The double-effect lithium bromide absorption cooling and power cogeneration system utilizing waste heat from fuel cells according to claim 4, characterized in that: The fuel cell system comprises a hydrogen pump (2), wherein an inlet and an outlet of the hydrogen pump (2) are respectively connected to the anode of the fuel cell stack (1) and a hydrogen inlet (24).

6. The double-effect lithium bromide absorption cooling and power cogeneration system utilizing waste heat from fuel cells according to claim 4, characterized in that: The fuel cell system comprises an air preheater (3), which is arranged between the air inlet (25) and the air outlet (26).

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