System and method for recovering waste heat of hydrogen-oxygen fuel cell to obtain dry gas and hot water

Abstract

The invention relates to a system for recovering waste heat of a hydrogen-oxygen fuel cell to obtain dry air and hot water. Waste gas generated by the hydrogen-oxygen fuel cell passes through the first evaporator and the first condenser and then enters the dryer, and meanwhile, the first evaporator and other assemblies such as the first compressor, the first condenser, the first gas storage tank and the first expansion valve form a circulation loop used for treating the waste gas and obtaining dry gas. In addition, cooling water of the fuel cell passes through the second evaporator, and a circulation loop is formed between the fuel cell and the second evaporator. The second evaporator is connected with the second compressor, the second condenser, the second air storage tank and the second expansion valve to form another loop, water flow is heated through waste heat, and the waste heat is converted into domestic hot water. By the adoption of the structure, waste heat of the hydrogen-oxygen fuel cell is effectively recycled, waste heat emission is reduced, the energy utilization rate can be increased, energy consumption is reduced, and the problem of waste heat loss of the fuel cell is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of green energy storage, and in particular to a system and method for recovering waste heat from hydrogen and oxygen fuel cells to obtain dry gas and hot water. Background Art

[0002] At present, with the development of industry, the use and industrial application of hydrogen and oxygen fuel cells are becoming more and more extensive. Due to their environmental friendliness, hydrogen and oxygen fuel cells have an irreplaceable position in the field of power generation. They have significant advantages such as efficient energy conversion, zero emissions, a wide range of applications and quiet operation. It directly converts hydrogen and oxygen into electrical energy through electrochemical reactions, with an efficiency of more than 60%, and the only by-product is water, which is suitable for occasions where carbon emissions are reduced.

[0003] However, the byproducts of the hydrogen-oxygen fuel cell reaction, such as water and some exhaust gas, also contain a large amount of waste heat. The temperature of the cooling water and exhaust gas can be as high as 70°C. Directly discharging the exhaust gas and water out of the environment will cause energy waste. The waste heat that cannot be utilized by large-scale and frequent use of fuel cells will be a large part of the loss. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a system and method for recovering the waste heat of hydrogen and oxygen fuel cells to obtain dry gas and hot water. By recycling the surplus heat energy in the hydrogen and oxygen fuel cells and converting it into other energy sources, this part of the heat energy can be used for heating or power generation, further improving the energy utilization rate of the overall system, reducing waste heat emissions, and reducing energy consumption, thus effectively solving the major problem of waste heat loss in hydrogen and oxygen fuel cells.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a system for recovering waste heat of a hydrogen-oxygen fuel cell to obtain dry gas and hot water, comprising a hydrogen-oxygen fuel cell, wherein the exhaust gas output pipeline on the hydrogen-oxygen fuel cell passes through a first evaporator and a first condenser and is connected to a dryer; The first evaporator is also connected to the first compressor, the first condenser, the first gas storage tank, and the first expansion valve to form a loop; The cooling water delivery pipeline on the hydrogen and oxygen fuel cell is connected to the second evaporator, and a circulation loop is formed between the hydrogen and oxygen fuel cell and the second evaporator through the cooling water delivery pipeline; The second evaporator is also connected with the second compressor, the second condenser, the second gas storage tank, and the second expansion valve to form a loop; The second condenser is provided with a water supply pipeline, and both ends of the water supply pipeline are respectively connected to the cold water tank and the hot water tank.

[0006] In a preferred solution, the circulating working medium CO2 in the circulating pipeline where the exhaust gas output pipeline and the first gas storage tank are located is heat-exchanged in the first evaporator to cool the exhaust gas and precipitate water in the exhaust gas; The circulating working medium CO2 in the circulating pipeline where the exhaust gas output pipeline and the first gas storage tank are located exchanges heat in the first condenser to form dry gas; The pipeline outputted from the output end of the hydrogen-oxygen fuel cell passes through the first evaporator and the first condenser and is connected to the dryer.

[0007] In a preferred solution, the circulating working medium CO2 in the circulating pipeline where the cooling water delivery pipeline and the second gas storage tank are located exchanges heat in the second evaporator; The high-temperature circulating working fluid CO2 formed by heat exchange in the second evaporator is compressed by the second compressor to form high-temperature and high-pressure gas, and then exchanges heat with the cold water output from the cold water tank in the second condenser to form hot water, which is then input into the hot water tank.

[0008] In a preferred solution, a fan is also provided on the pipeline where the dryer is located, and the fan transports the dry gas formed in the exhaust gas output pipeline through the first condenser to the drying process, and the exhaust gas that completes the drying and water absorption work in the drying process is discharged to the environment.

[0009] In a preferred solution, a first throttle valve is also provided in a loop formed by connecting the first evaporator with the first compressor, the first condenser, the first gas storage tank, and the first expansion valve.

[0010] In a preferred solution, a second throttle valve is further provided in a loop formed by connecting the second evaporator with the second compressor, the second condenser, the second gas storage tank, and the second expansion valve.

[0011] In a preferred solution, a third throttle valve is further provided in the loop formed by the cooling water delivery pipeline between the hydrogen and oxygen fuel cell and the second evaporator.

[0012] A method for recovering waste heat from hydrogen and oxygen fuel cells to obtain dry gas and hot water based on the above system, specifically including heat recovery from reaction exhaust gas and waste heat recovery from cooling water; The heat recovery of the reaction waste gas comprises the following steps: 1) The reaction waste gas generated in the hydrogen-oxygen fuel cell is output from the waste gas output pipeline and passes through the first evaporator to exchange heat with the circulating working medium CO2. The reaction waste gas releases heat and cools down to precipitate moisture in the waste gas; 2) The gas then passes through the first condenser, where it forms dry gas with the circulating working fluid CO2; 3) Dry gas is sucked in by the fan for drying process, and the waste gas after drying and absorbing water is discharged into the environment; The waste heat recovery of the cooling water comprises the following steps: 1) The cooling water carries the waste heat, circulates the working fluid CO2 in the second evaporator for heat exchange, and then returns to the hydrogen and oxygen fuel cell through the third throttle valve.

[0013] In a preferred embodiment, during the heat recovery process of the reaction waste gas, the circulation process of the circulating working fluid CO2 that exchanges heat with the reaction waste gas is as follows: 1) The high-temperature and high-pressure gaseous CO2 in the first gas storage tank is output and passes through the first expansion valve to form low-temperature and low-pressure CO2; 2) Control the flow and pressure of the working fluid CO2 through the first throttle valve to control the balance and stability in the circulation loop; 3) Low-temperature and low-pressure CO2 passes through the first evaporator and exchanges heat with the reaction exhaust gas; 4) The CO2 after heat exchange is pressurized by the first compressor to form high-temperature and high-pressure CO2, and then input into the first condenser; 5) The pressurized CO2 exchanges heat with the reaction waste gas again in the first condenser to obtain hot dry gas which is used in the drying process.

[0014] In a preferred solution, during the waste heat recovery process of the cooling water, the circulation process of the circulating working fluid CO2 that exchanges heat with the cooling water is as follows: 1) The high-temperature and high-pressure gaseous CO2 in the second gas storage tank is output and passes through the second expansion valve to become low-temperature and low-pressure CO2; 2) Control the flow and pressure of the working fluid CO2 through the second throttle valve to control the balance and stability in the circulation loop; 3) Low temperature and low pressure CO2 passes through the second condenser and exchanges heat with cooling water; 4) The CO2 after heat exchange is pressurized by the first compressor to form high-temperature and high-pressure CO2, and then input into the second condenser; 5) The high-temperature and high-pressure CO2 exchanges heat between the second condenser and the cold water output from the cold water tank to produce hot water; 6) After completing the heat exchange, the working fluid CO2 continues to enter the circulation loop to repeat the above steps, and the hot water is input into the hot water tank for storage.

[0015] The present invention provides a system and method for recovering waste heat from a hydrogen-oxygen fuel cell to obtain dry gas and hot water. By adopting the above method and system, the following beneficial effects are achieved: (1) The advantage of using CO2 as a heat pump circulating medium is its superior thermodynamic properties and environmental friendliness. It can not only convert the reaction exhaust gas into hot drying gas for drying, but also recover the waste heat of cooling water and use it to heat hot water through a CO2 heat pump; (2) CO2 has a low critical temperature, allowing heat pumps to operate in a supercritical state, thereby improving heat transfer efficiency, especially in high-temperature heating and hot water applications. In addition, CO2's high-pressure characteristics enable it to transfer heat more efficiently during evaporation and condensation, improving the system's energy efficiency. As a natural working fluid, CO2 does not damage the ozone layer and has a global warming potential close to 1, combining sustainability with excellent thermodynamic efficiency. (3) The entire system not only effectively cools the cooling water of the hydrogen-oxygen fuel cell, but also greatly improves energy efficiency by utilizing the waste heat of the cooling water and the waste heat of the reaction exhaust gas of the hydrogen-oxygen fuel cell. By recycling and utilizing this waste heat for heating and other purposes, it reduces the system's energy waste, reduces additional energy consumption and operating costs, and at the same time reduces dependence on external energy, achieving more environmentally friendly and sustainable operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention will be further described below in conjunction with the accompanying drawings and embodiments: Figure 1 It is a schematic diagram of the overall structure of the present invention. DETAILED DESCRIPTION

[0017] Embodiment 1: like Figure 1 A system for recovering waste heat from a hydrogen-oxygen fuel cell to obtain dry gas and hot water includes a hydrogen-oxygen fuel cell, wherein an exhaust gas output pipeline on the hydrogen-oxygen fuel cell passes through a first evaporator 1 and a first condenser 3 and is connected to a dryer 5; The first evaporator 1 is also connected to the first compressor 2, the first condenser 3, the first gas storage tank 6, and the first expansion valve 7 to form a loop; The cooling water delivery pipeline on the hydrogen-oxygen fuel cell is connected to the second evaporator 9, and a circulation loop is formed between the hydrogen-oxygen fuel cell and the second evaporator 9 through the cooling water delivery pipeline; The second evaporator 9 is also connected to the second compressor 10, the second condenser 11, the second gas storage tank 14, and the second expansion valve 15 to form a loop; The second condenser 11 is provided with a water supply pipe, and both ends of the water supply pipe are connected to the cold water tank 12 and the hot water tank 13 respectively.

[0018] In a preferred solution, the circulating working medium CO2 in the circulating pipeline where the exhaust gas output pipeline and the first gas storage tank 6 are located is heat-exchanged in the first evaporator 1 to cool the exhaust gas and precipitate water in the exhaust gas; The circulating working medium CO2 in the circulating pipeline where the exhaust gas output pipeline and the first gas storage tank 6 are located exchanges heat in the first condenser 3 to form dry gas; The pipeline outputted from the output end of the hydrogen-oxygen fuel cell passes through the first evaporator 1 and the first condenser 3 and is connected to the dryer 5 .

[0019] In the preferred solution, the cooling water delivery pipeline and the circulating working medium CO2 in the circulating pipeline where the second gas storage tank 14 is located exchange heat in the second evaporator 9; The high-temperature circulating working fluid CO2 formed by heat exchange in the second evaporator 9 is compressed by the second compressor 10 to form a high-temperature and high-pressure gas, and then exchanges heat with the cold water output from the cold water tank 12 in the second condenser 11 to form hot water, which is then input into the hot water tank 13.

[0020] In a preferred embodiment, a fan 4 is further provided on the pipeline where the dryer 5 is located. The fan 4 transports the dry gas formed in the exhaust gas output pipeline through the first condenser 3 to the drying process, and the exhaust gas that completes the drying and water absorption work in the drying process is discharged to the environment.

[0021] In a preferred solution, a first throttle valve 8 is further provided in a loop formed by connecting the first evaporator 1 with the first compressor 2 , the first condenser 3 , the first gas storage tank 6 , and the first expansion valve 7 .

[0022] In a preferred solution, a second throttle valve 16 is further provided in a circuit formed by connecting the second evaporator 9 with the second compressor 10 , the second condenser 11 , the second gas storage tank 14 , and the second expansion valve 15 .

[0023] In a preferred solution, a third throttle valve 17 is further provided in the loop formed by the cooling water delivery pipeline between the hydrogen and oxygen fuel cell and the second evaporator 9 .

[0024] Embodiment 2: A method for recovering waste heat from a hydrogen-oxygen fuel cell to obtain dry gas and hot water based on the system described in Example 1, which includes heat recovery from reaction exhaust gas and waste heat recovery from cooling water; The heat recovery of the reaction waste gas comprises the following steps: 1) The reaction waste gas (relative humidity of 70%-90%) generated in the hydrogen-oxygen fuel cell is output from the waste gas output pipeline and passes through the first evaporator 1 to exchange heat with the circulating working medium CO2. The reaction waste gas releases heat and cools down to separate out moisture in the waste gas; 2) The gas then passes through the first condenser 3, where it forms dry gas (relative humidity of 4%-5%) with the circulating working fluid CO2; 3) Drying gas is sucked in by fan 4 for drying process, and the waste gas after drying and absorbing water is discharged to the environment; The waste heat recovery of the cooling water comprises the following steps: 1) The cooling water carries the waste heat, exchanges heat with the circulating working medium CO2 in the second evaporator 9, and then returns to the hydrogen-oxygen fuel cell through the third throttle valve 17.

[0025] Embodiment 3: In the heat recovery process of the reaction waste gas described in Example 2, the circulation process of the circulating working fluid CO2 that exchanges heat with the reaction waste gas is as follows: 1) The high-temperature and high-pressure gaseous CO2 in the first gas storage tank 6 is output and passes through the first expansion valve 7 to form low-temperature and low-pressure CO2; 2) Control the flow and pressure of the working medium CO2 through the first throttle valve 8 to control the balance and stability in the circulation loop; 3) Low-temperature and low-pressure CO2 passes through the first evaporator 1 and exchanges heat with the reaction exhaust gas; 4) The CO2 after heat exchange is pressurized by the first compressor 2 to form high-temperature and high-pressure CO2, and is input into the first condenser 3; 5) The pressurized CO2 exchanges heat with the reaction waste gas again in the first condenser 3 to obtain hot dry gas which is used in the drying process.

[0026] Embodiment 4: In the waste heat recovery process of cooling water described in Example 2, the circulation process of the circulating working fluid CO2 that exchanges heat with the cooling water is as follows: 1) The high-temperature and high-pressure gaseous CO2 in the second gas storage tank 14 is output and passes through the second expansion valve 15 to become low-temperature and low-pressure CO2; 2) Control the flow and pressure of the working medium CO2 through the second throttle valve 16 to control the balance and stability in the circulation loop; 3) Low-temperature and low-pressure CO2 passes through the second condenser 11 and exchanges heat with cooling water; 4) The CO2 after heat exchange is pressurized by the first compressor 2 to form high-temperature and high-pressure CO2, and is input into the second condenser 11; 5) The high-temperature and high-pressure CO2 exchanges heat between the second condenser 11 and the cold water output from the cold water tank 12 to produce hot water; 6) After the heat exchange is completed, the working medium CO2 continues to enter the circulation loop to repeat the above steps, and the hot water is input into the hot water tank 13 for storage.

[0027] In the above process, the reaction exhaust gas of the hydrogen-oxygen fuel cell and the waste heat of the cooling water are effectively utilized, and dry gas and hot water are produced, effectively reducing unnecessary fossil energy consumption.

Claims

1. A system for recovering waste heat from hydrogen and oxygen fuel cells to obtain dry gas and hot water, characterized in that: It comprises a hydrogen-oxygen fuel cell, wherein the exhaust gas output pipeline on the hydrogen-oxygen fuel cell passes through a first evaporator (1) and a first condenser (3) and is then connected to a dryer (5); The first evaporator (1) is also connected to the first compressor (2), the first condenser (3), the first gas storage tank (6), and the first expansion valve (7) to form a loop; The cooling water delivery pipeline on the hydrogen-oxygen fuel cell is connected to the second evaporator (9), and a circulation loop is formed between the hydrogen-oxygen fuel cell and the second evaporator (9) through the cooling water delivery pipeline; The second evaporator (9) is also connected to a second compressor (10), a second condenser (11), a second gas storage tank (14), and a second expansion valve (15) to form a loop; The second condenser (11) is provided with a water supply pipe, and both ends of the water supply pipe are respectively connected to a cold water tank (12) and a hot water tank (13).

2. A system for recovering waste heat from hydrogen and oxygen fuel cells to obtain dry gas and hot water according to claim 1, characterized in that: The circulating working medium CO2 in the circulating pipeline where the exhaust gas output pipeline and the first gas storage tank (6) are located exchanges heat in the first evaporator (1) to cool the exhaust gas and precipitate water in the exhaust gas; The circulating working medium CO2 in the circulating pipeline where the exhaust gas output pipeline and the first gas storage tank (6) are located exchanges heat in the first condenser (3) to form dry gas; The pipeline output from the output end of the hydrogen-oxygen fuel cell passes through the first evaporator (1) and the first condenser (3) and is then connected to the dryer (5).

3. The system for recovering waste heat from hydrogen and oxygen fuel cells to obtain dry gas and hot water according to claim 1, characterized in that: The cooling water delivery pipeline and the circulating working medium CO2 in the circulating pipeline where the second gas storage tank (14) is located exchange heat in the second evaporator (9); The high-temperature circulating working fluid CO2 formed by heat exchange in the second evaporator (9) is compressed by the second compressor (10) to form high-temperature and high-pressure gas, and then heat-exchanged with cold water output from the cold water tank (12) in the second condenser (11) to form hot water, which is then input into the hot water tank (13).

4. The system for recovering waste heat from hydrogen and oxygen fuel cells to obtain dry gas and hot water according to claim 1, characterized in that: A fan (4) is also provided on the pipeline where the dryer (5) is located. The fan (4) transports the dry gas formed in the waste gas output pipeline through the first condenser (3) to the drying process, and the waste gas that has completed the drying and water absorption work in the drying process is discharged to the environment.

5. The system for recovering waste heat from hydrogen and oxygen fuel cells to obtain dry gas and hot water according to claim 1, characterized in that: A first throttle valve (8) is also provided in a circuit formed by connecting the first evaporator (1) with the first compressor (2), the first condenser (3), the first gas storage tank (6), and the first expansion valve (7).

6. The system for recovering waste heat from hydrogen and oxygen fuel cells to obtain dry gas and hot water according to claim 1, characterized in that: A second throttle valve (16) is also provided in a circuit formed by connecting the second evaporator (9) with the second compressor (10), the second condenser (11), the second gas storage tank (14), and the second expansion valve (15).

7. The system for recovering waste heat from hydrogen and oxygen fuel cells to obtain dry gas and hot water according to claim 1, characterized in that: A third throttle valve (17) is also provided in the loop formed by the cooling water delivery pipeline between the hydrogen and oxygen fuel cell and the second evaporator (9).

8. A method for recovering waste heat from hydrogen and oxygen fuel cells to obtain dry gas and hot water based on the system according to any one of claims 1 to 7, characterized in that: Including heat recovery of reaction exhaust gas and waste heat recovery of cooling water; The heat recovery of the reaction waste gas comprises the following steps: 1) The reaction waste gas generated in the hydrogen-oxygen fuel cell is outputted from the waste gas output pipeline and passes through the first evaporator (1) to exchange heat with the circulating working medium CO2, and the reaction waste gas releases heat and cools down to separate out moisture in the waste gas; 2) the gas then passes through a first condenser (3) and forms a dry gas with the circulating working fluid CO2 in the first condenser (3); 3) Dry gas is sucked in by the fan (4) for the drying process, and the waste gas after drying and absorbing water is discharged into the environment; The waste heat recovery of cooling water comprises the following steps: 1) The cooling water carries the waste heat, exchanges heat with the circulating working medium CO2 in the second evaporator (9), and then returns to the hydrogen-oxygen fuel cell through the third throttle valve (17).

9. The method for recovering waste heat from hydrogen and oxygen fuel cells to obtain dry gas and hot water according to claim 8, characterized in that: In the heat recovery process of the reaction waste gas, the circulation process of the circulating working fluid CO2 that exchanges heat with the reaction waste gas is as follows: 1) The high-temperature and high-pressure gaseous CO2 in the first gas storage tank (6) is output and passes through the first expansion valve (7) to form low-temperature and low-pressure CO2; 2) Controlling the flow rate and pressure of the working medium CO2 through the first throttle valve (8) to control the balance and stability in the circulation loop; 3) Low-temperature and low-pressure CO2 passes through the first evaporator (1) and exchanges heat with the reaction exhaust gas; 4) The CO2 after heat exchange is pressurized by the first compressor (2) to form high-temperature and high-pressure CO2, which is then input into the first condenser (3); 5) The pressurized CO2 is heat-exchanged with the reaction waste gas again in the first condenser (3) to obtain hot dry gas which is used in the drying process.

10. The method for recovering waste heat from hydrogen and oxygen fuel cells to obtain dry gas and hot water according to claim 8, characterized in that: In the waste heat recovery process of the cooling water, the circulation process of the circulating working fluid CO2 that exchanges heat with the cooling water is as follows: 1) The high-temperature and high-pressure gaseous CO2 in the second gas storage tank (14) is output and passes through the second expansion valve (15) to become low-temperature and low-pressure CO2; 2) Controlling the flow rate and pressure of the working medium CO2 through the second throttle valve (16) to control the balance and stability in the circulation loop; 3) The low-temperature and low-pressure CO2 passes through the second condenser (11) and exchanges heat with cooling water; 4) The CO2 after heat exchange is pressurized by the first compressor (2) to form high-temperature and high-pressure CO2, which is then input into the second condenser (11); 5) The high-temperature and high-pressure CO2 exchanges heat between the second condenser (11) and the cold water output from the cold water tank (12) to produce hot water; 6) After the heat exchange is completed, the working fluid CO2 continues to enter the circulation loop to repeat the above steps, and the hot water is input into the hot water tank (13) for storage.

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