A fuel cell cooling circulation system

Abstract

The present invention relates to a fuel cell cooling circulation system, comprising a stack, an air circuit, a cooling circuit and a pressure circuit; the air circuit comprises an air compressor, the air compressed by the air compressor is passed into the stack from the air inlet of the stack, and discharged from the stack from the air outlet of the stack; the cooling circuit comprises an expansion water tank and a water pump, the coolant is passed into the stack under the action of the water pump, and flows back from the stack to the water inlet of the water pump, and the expansion water tank replenishes the coolant for the cooling circuit; the pressure circuit comprises an air delivery pipe and a one-way valve, the air delivery pipe connects the air outlet of the stack and the expansion water tank, and the one-way valve is arranged between the air outlet of the stack and the expansion water tank. Compared with the prior art, the present invention passes the gas with a certain pressure at the air outlet of the stack into the expansion water tank, reduces the fuel cell's need for the water pump head, reduces the cost of the fuel cell, and the power of the water pump with a smaller head is also smaller, thereby increasing the system net output power of the fuel cell.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and in particular to a fuel cell cooling circulation system. Background Art

[0002] In a fuel cell system, in order to ensure that the stack can operate in a relatively ideal state, it is generally required to maintain a certain pressure difference between the cooling side of the stack and the anode and cathode of the stack, so as to avoid excessive pressure difference between the cooling side of the stack and the anode and cathode of the stack, which may lead to mutual penetration of hydrogen, air and coolant.

[0003] At present, the system power of fuel cells is getting bigger and bigger. In order to ensure the pressure on the cooling side, a water pump with a relatively large head is required. However, the configuration of a water pump with a relatively large head will cause the following problems: the increase in the power of the water pump will lead to a decrease in the net output power of the entire fuel cell system; the high cost of the water pump with a large head will lead to an increase in the production cost of the fuel cell; there are relatively few optional models of water pumps with a large head, making it difficult to match the fuel cell system.

[0004] Chinese patent CN210668556U discloses a fuel cell engine cooling water pressure control system, the basic concept of which is to pass the compressed air at the inlet of the stack into the expansion water tank, thereby increasing the pressure at the inlet of the water pump and reducing the power consumed by the water pump. The advantages of this system are low energy consumption and good pressure control stability, but there are still shortcomings in practical application: after the compressed air is passed into the expansion water tank, the expansion water tank has a certain pressure. When the air compressor stops running or the air path pressure is less than the expansion water tank pressure, the water and gas in the expansion water tank will flow back into the air path, affecting the life of the fuel cell; compressed air is passed into the expansion water tank through the air pipe. As the power of the stack increases, the pressure at the inlet of the stack (the outlet of the air compressor) will also increase significantly. It is necessary to set a pressure regulating part on the air pipe to adjust the air pressure, which leads to a high cost of the fuel cell system and occupies a certain volume and space, which is not conducive to integrated setting. Summary of the invention

[0005] The purpose of the present invention is to provide a fuel cell cooling circulation system in order to overcome the defects of the prior art.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] A fuel cell cooling circulation system comprises a fuel cell stack, an air circuit, a cooling circuit and a pressure circuit;

[0008] The air circuit includes an air compressor, which is used to compress air. The compressed air is passed into the cathode of the fuel cell stack from the air inlet of the fuel cell stack, and the compressed air in the fuel cell stack is discharged from the fuel cell stack from the air outlet of the cathode of the fuel cell stack.

[0009] The cooling circuit includes an expansion water tank and a water pump. The coolant is introduced into the battery stack under the action of the water pump and flows back from the battery stack to the water inlet of the water pump. The expansion water tank is used to replenish the coolant for the cooling circuit.

[0010] The pressure circuit includes an air supply pipe and a one-way valve, one end of the air supply pipe is connected to the air outlet of the fuel cell stack, and the other end of the air supply pipe is connected to the expansion water tank. The one-way valve is arranged between the air outlet of the fuel cell stack and the expansion water tank, and is used to conduct the air outlet to the expansion water tank and block the expansion water tank from the air outlet.

[0011] Furthermore, the air circuit also includes an air intake pipe, which connects the air compressor and the air inlet of the fuel cell stack, and the air compressed by the air compressor is passed into the fuel cell stack through the air intake pipe.

[0012] Furthermore, the air circuit also includes an exhaust pipe, which is connected to the air outlet of the battery stack. The compressed air in the battery stack is discharged through the exhaust pipe. A pressure regulating valve is installed on the exhaust pipe, and the pressure regulating valve is used to adjust the air pressure of the air circuit.

[0013] Furthermore, one end of the gas supply pipe is connected to the exhaust pipe, and the connection between the gas supply pipe and the exhaust pipe is located upstream of the pressure regulating valve.

[0014] Furthermore, the pipeline from the air outlet of the fuel cell stack to the expansion water tank is slanted upward or vertically upward to avoid the pipeline bending downward and then upward, thereby preventing the increase in flow resistance caused by water at the cathode outlet of the fuel cell stack accumulating in the pipeline.

[0015] Furthermore, the fuel cell cooling circulation system also includes a supporting structure, which is used to support the pipeline between the air outlet of the fuel cell stack and the expansion water tank.

[0016] Furthermore, the cooling circuit also includes a water inlet pipe, a water outlet pipe and a water make-up pipe. The water outlet of the water pump is connected to the coolant inlet of the battery stack through the water outlet pipe. The coolant flowing out of the coolant outlet of the battery stack flows back to the water inlet of the water pump through the water inlet pipe after cooling. The expansion water tank is connected to the water inlet of the water pump through the water make-up pipe to replenish the coolant for the cooling circuit.

[0017] Furthermore, the expansion water tank comprises a tank body and a pressure cover, the water supply pipe is connected to the tank body, and the pressure cover is provided with a pressure relief port.

[0018] Furthermore, the one-way valve is integrated on the tank body of the expansion water tank.

[0019] Furthermore, the pressure cap is arranged on the top of the box body, the one-way valve is integrated on the side wall of the box body, and the position of the one-way valve is higher than the highest liquid level in the box body of the expansion water tank, so that the coolant in the expansion water tank is evenly pressurized to avoid stirring the coolant in the expansion water tank.

[0020] Furthermore, the air circuit also includes a filter, an intercooler and a humidifier, the filter is arranged upstream of the air compressor, the intercooler is arranged between the air compressor and the fuel cell stack, and the humidifier is arranged between the intercooler and the fuel cell stack.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) The gas with a certain pressure at the air outlet of the fuel cell stack is passed into the expansion water tank, thereby reducing the fuel cell's need for a water pump head. A water pump with a smaller head can be selected. At this time, the water pump has a wide range of optional models and is cheaper than a water pump with a large head, thereby reducing the cost of the fuel cell. The power of a water pump with a smaller head is also smaller, so the power consumed by the water pump will be reduced, thereby increasing the system net output power of the fuel cell.

[0023] (2) A one-way valve is integrated on the expansion tank to prevent the backflow of water and gas in the expansion tank, thus ensuring the safety and service life of the fuel cell system.

[0024] (3) The gas pressure at the air outlet of the fuel cell stack is stable, with basically no pressure fluctuation. The pressure transmitted to the expansion water tank is also stable, which is beneficial to the stability of the cooling circuit. Therefore, there is no need to install a pressure regulating part on the gas pipe, which reduces the cost and volume, and is beneficial to the integrated layout of the fuel system.

[0025] (4) There is flow resistance inside the fuel cell stack. When the pressure at the air inlet of the fuel cell stack increases, the air outlet pressure of the fuel cell stack also increases accordingly. However, the flow resistance of the fuel cell stack is also increasing at the same time. Therefore, the pressure at the air outlet of the fuel cell stack increases slowly. In this way, the pressure of the expansion water tank is regulated by relying on the flow resistance of the fuel cell stack, and there is no need to install a pressure regulating device on the gas pipe.

[0026] (5) The pipeline from the air outlet of the fuel cell stack to the expansion water tank is slanted upward or vertically upward to avoid the pipeline bending downward and then upward, thereby preventing the increase in flow resistance caused by water accumulation in the pipeline at the cathode outlet of the fuel cell stack. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a structural schematic diagram of the present invention;

[0028] Figure 2 Flow chart of

[0029] Figure numerals: 1. battery stack, 2. air compressor, 3. pressure regulating valve, 4. expansion tank, 41. pressure cover, 42. check valve, 43. box body, 5. water pump. DETAILED DESCRIPTION

[0030] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0031] In the drawings, components with the same structure are indicated by the same numerical labels, and components with similar structures or functions are indicated by similar numerical labels. The size and thickness of each component shown in the drawings are arbitrarily shown, and the present invention does not limit the size and thickness of each component. In order to make the illustration clearer, some parts in the drawings are appropriately exaggerated.

[0032] Embodiment 1:

[0033] A fuel cell cooling circulation system, such as Figure 1 As shown, it includes a battery stack 1, an air circuit, a cooling circuit and a pressure circuit;

[0034] The air circuit includes an air compressor 2, which is used to compress the air. The compressed air is passed into the fuel cell stack 1 from the air inlet of the cathode of the fuel cell stack 1, and the compressed air in the fuel cell stack 1 is discharged from the fuel cell stack 1 from the air outlet of the cathode of the fuel cell stack 1. In order to ensure the normal operation of the fuel cell, the air circuit also includes a filter, an intercooler and a humidifier. The filter is arranged upstream of the air compressor 2 to filter the air. The intercooler is arranged between the air compressor 2 and the fuel cell stack 1 to cool the compressed high-temperature air. The humidifier is arranged between the intercooler and the fuel cell stack 1 to humidify the air. The humidified air is then passed into the fuel cell stack 1.

[0035] The air circuit also includes an intake pipe and an exhaust pipe. The intake pipe is connected to the air inlet of the air compressor 2 and the fuel cell stack 1, and the air compressed by the air compressor 2 is passed into the fuel cell stack 1 through the intake pipe; the exhaust pipe is connected to the air outlet of the fuel cell stack 1, and the compressed air in the fuel cell stack 1 is discharged through the exhaust pipe. A pressure regulating valve 3 (i.e., back pressure valve) is installed on the exhaust pipe, and the pressure regulating valve 3 is used to adjust the air pressure of the air circuit.

[0036] The cooling circuit includes an expansion water tank 4, a water pump 5, a water inlet pipe, a water outlet pipe and a water supply pipe. The coolant is passed into the battery stack 1 under the action of the water pump 5, and flows back from the battery stack 1 to the water inlet of the water pump 5. The expansion water tank 4 is used to replenish the coolant for the cooling circuit; in this embodiment, the coolant is water. The outlet of the water pump 5 is connected to the coolant inlet of the battery stack 1 through the outlet pipe. The coolant flowing out of the coolant outlet of the battery stack 1 flows back to the water inlet of the water pump 5 through the water inlet pipe after cooling. In this embodiment, the coolant flowing out of the coolant outlet of the battery stack 1 will first pass through the radiator for heat dissipation, and then flow back to the water inlet of the water pump 5 through the water inlet pipe to cool the battery stack 1 again. The expansion water tank 4 reduces the water pressure fluctuation caused by the thermal expansion and contraction of the coolant in the fuel cell cooling cycle system, which is manifested in accommodating excess coolant in the cooling circuit or replenishing coolant in the cooling circuit. In this embodiment, it is simply described as the expansion water tank 4 replenishing coolant for the cooling circuit. Therefore, the expansion water tank 4 is connected to the water inlet of the water pump 5 through the water supply pipe.

[0037] The pressure circuit includes an air supply pipe and a one-way valve 42, one end of the air supply pipe is connected to the air outlet of the fuel cell stack 1, and the other end of the air supply pipe is connected to the expansion water tank 4. The one-way valve 42 is arranged between the air outlet of the fuel cell stack 1 and the expansion water tank 4, and is used to conduct the air outlet to the expansion water tank 4 and block the expansion water tank 4 from the air outlet; specifically, the pressure upstream of the pressure regulating valve 3, that is, the pressure of the air discharged from the fuel cell stack 1, is generally about 2 atmospheres, and the pressure downstream of the pressure regulating valve 3 is atmospheric pressure, so one end of the air supply pipe is connected to the exhaust pipe, and the connection between the air supply pipe and the exhaust pipe is located upstream of the pressure regulating valve 3.

[0038] Furthermore, the pipeline between the air outlet of the stack 1 and the expansion water tank 4 is obliquely upward or vertically upward, so as to avoid the pipeline bending downward first and then upward, thereby preventing the flow resistance from increasing due to the accumulation of water at the cathode outlet of the stack in the pipeline. In this embodiment, the fuel cell cooling circulation system also includes a support structure, which is used to support the pipeline between the air outlet of the stack 1 and the expansion water tank 4, so that the pipeline between the air outlet of the stack 1 and the expansion water tank 4 is obliquely upward or vertically upward.

[0039] like Figure 2 As shown, the expansion water tank 4 includes a box body 43 and a pressure cap 41, the water supply pipe is connected to the box body 43, the pressure cap 41 is provided with a pressure relief port, and the one-way valve 42 is integrated on the box body 43 of the expansion water tank 4. Specifically, the pressure cap 41 is arranged on the top of the box body 43, the one-way valve 42 is integrated on the side wall of the box body 43, and the position of the one-way valve 42 is higher than the highest liquid level in the box body 43 of the expansion water tank 4, so that the coolant in the expansion water tank 4 is evenly pressurized to avoid stirring the coolant in the expansion water tank 4.

[0040] The inventive ideas of this application are as follows:

[0041] In order to ensure the pressure difference between the cooling side of the stack 1 and the anode and cathode of the stack 1, a water pump 5 with a large head is required. The relationship between the head and pressure of the water pump 5 is as follows:

[0042]

[0043] in, Indicates the head of the water pump 5, in m; Indicates the pressure at the outlet of water pump 5, in Pa; Indicates the pressure at the water inlet of water pump 5, in Pa; Indicates the density of the coolant flowing in the cooling circuit, in kg / m 3 ; Indicates the acceleration due to gravity, in m / s 2 ; Indicates the flow rate at the outlet of water pump 5, in m / s; Indicates the flow rate at the water inlet of the water pump, in m / s; Indicates the height of the water outlet of water pump 5, in m; Indicates the height of the water inlet of the water pump, in m;

[0044] Maintain coolant flow rate , , Inlet and outlet height , and outlet pressure Under the condition of no change, it can be found that the head of pump 5 With inlet pressure Inversely proportional:

[0045]

[0046]

[0047] Therefore, if the pressure at the water inlet of the water pump 5 is increased , then the required pump head is Therefore, the inventor's research idea is to increase the pressure at the water inlet of the water pump 5 .

[0048] Without considering the pipeline pressure loss, the pressure at the water inlet of pump 5 is Equal to the pressure in the expansion tank 4 If a booster device is added to the expansion tank 4 to increase the pressure of the expansion tank 4, the pressure at the water inlet of the water pump 5 can be increased. However, the cost of adding an additional booster device is high and it also increases the size of the fuel cell system.

[0049] After research and analysis, the inventor found that the air compressed by the air compressor 2 has a certain pressure, and the compressed air still has a certain pressure after being discharged from the fuel cell stack 1, which is higher than the pressure in the expansion water tank 4. If the compressed air is introduced into the expansion water tank 4 at the air inlet of the fuel cell stack 1, that is, the method in patent CN210668556U, the following deficiencies will occur:

[0050] (1) After the compressed air is introduced into the expansion water tank 4, there is a certain pressure in the expansion water tank 4. When the air compressor 2 stops running, the water and gas in the expansion water tank 4 will flow back into the air circuit, affecting the life of the fuel cell. Therefore, when implementing patent CN210668556U, it is necessary to first release the pressure of the expansion water tank 4 and then stop the air compressor 2. This is not only cumbersome to operate, but also cannot prevent the water and gas in the expansion water tank 4 from flowing back into the air circuit when the pressure of the air circuit is lower than the pressure of the expansion water tank 4.

[0051] (2) The gas pressure at the outlet of the air compressor 2 and the inlet of the fuel cell stack 1 often fluctuates. This fluctuation will be directly transmitted to the expansion water tank 4, causing pressure fluctuations in the cooling circuit, which is not conducive to the water pressure and temperature of the cooling circuit. Patent CN210668556U sets a pressure regulating valve on the gas pipeline to avoid such pressure fluctuations, but this also leads to an increase in cost and volume, which is not conducive to the integrated layout of fuel cells.

[0052] (3) The air flow at the inlet of the stack 1 is positively correlated with the power of the stack 1. The flow of the air compressor 2 is reflected in the pressure. In simple terms, the higher the power of the stack 1, the greater the air pressure at the inlet of the stack 1. This will cause the pressure of the expansion tank 4 to increase with the increase of the power of the stack 1. However, the pressure that the expansion tank 4 can bear is limited. When the power of the stack 1 reaches a certain level, the air pressure at the inlet of the stack 1 also reaches a certain level. When the pressure in the expansion tank 4 is too high, the pressure cap 41 will be triggered to release pressure and release gas. In this way, when the air pressure at the inlet of the stack 1 reaches a certain level, it will not be able to continue to increase due to the pressure release of the pressure cap 41, so that the power of the stack 1 cannot continue to increase after reaching a certain level. Patent CN210668556U sets a pressure sensor, a pressure regulating valve, etc. on the gas pipeline, but this also leads to an increase in cost and volume, which is not conducive to the integrated layout of fuel cells.

[0053] Therefore, if compressed air is introduced into the expansion water tank 4 at the air inlet of the fuel cell stack 1, although the lift of the water pump 5 is reduced, new problems are also brought about.

[0054] After further research and analysis, the inventors found that the compressed air will be directly discharged from the fuel cell stack 1 after passing into the fuel cell stack 1, that is, the compressed air will be discharged from the exhaust pipe of the air outlet of the fuel cell stack 1 after reacting inside the fuel cell stack 1. In order to ensure that the air circuit has a certain pressure, a pressure regulating valve 3 will be arranged on the exhaust pipe. The pressure upstream of the pressure regulating valve 3 is the pressure of the air discharged from the fuel cell stack 1, which is generally about 2 atmospheres, and the pressure downstream of the pressure regulating valve 3 is the atmospheric pressure.

[0055] After research, the inventor found that after the compressed air reacts inside the fuel cell stack 1, although the gas pressure at the air outlet of the fuel cell stack 1 is lower than the gas pressure at the air inlet of the fuel cell stack 1, the pressure at the air outlet is still higher than the pressure of the expansion water tank 4, so the compressed air at the air inlet of the fuel cell stack 1 can be passed into the expansion water tank 4, and compared with the patent CN210668556U, the compressed air passed into the air outlet of the fuel cell stack 1 has the following advantages:

[0056] (1) The air compressed by the air compressor 2 will tend to be stable after passing through the fuel cell stack 1 and then discharged, with basically no pressure fluctuation. The pressure transmitted to the expansion water tank 4 will also tend to be stable, which is conducive to the stability of the cooling circuit. Therefore, there is no need to set a pressure regulating part on the air supply pipe.

[0057] (2) There is flow resistance inside the fuel cell stack 1. When the pressure of the air compressor 2 continues to increase, the air inlet pressure of the fuel cell stack 1 continues to increase, and the air outlet pressure of the fuel cell stack 1 also increases accordingly. However, as the pressure of the air circuit increases, the flow resistance of the fuel cell stack 1 also increases. Therefore, the pressure at the air outlet of the fuel cell stack 1 increases slowly. In this way, the pressure is regulated by relying on the flow resistance of the fuel cell stack 1, and there is no need to set a pressure regulating part on the gas pipeline.

[0058] (3) When the power of the fuel cell stack 1 continues to increase, even if the expansion tank 4 is depressurized due to excessive pressure, it has almost no effect on the pressure at the inlet of the fuel cell stack 1. With the help of the pressure regulating valve 3 on the exhaust pipe, the power of the fuel cell stack 1 can continue to increase.

[0059] (4) The present application integrates a one-way valve 42 on the expansion water tank 4. The one-way valve 42 allows the air outlet to pass through the expansion water tank 4 and blocks the expansion water tank 4 from passing through the air outlet, thereby effectively preventing the water and gas in the expansion water tank 4 from flowing back.

[0060] The present application effectively reduces the fuel cell system's need for the lift of the water pump 5 , and can balance the pressures on the cooling water side and the air side. The air side pressure and the cooling circuit pressure can be well kept within a reasonable range, thereby increasing the service life of the fuel cell stack 1 .

[0061] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A fuel cell cooling circulation system, It is characterized in that It includes a battery stack (1), an air circuit, a cooling circuit and a pressure circuit; The air circuit comprises an air compressor (2), the air compressor (2) being used to compress air, the compressed air being introduced into the fuel cell stack (1) from an air inlet of the fuel cell stack (1), and the compressed air in the fuel cell stack (1) being discharged from the fuel cell stack (1) from an air outlet of the fuel cell stack (1); The cooling circuit comprises an expansion water tank (4) and a water pump (5); the coolant is introduced into the fuel cell stack (1) under the action of the water pump (5) and flows back from the fuel cell stack (1) to the water inlet of the water pump (5); the expansion water tank (4) is used to replenish the coolant for the cooling circuit; the expansion water tank (4) comprises a box body (43) and a pressure cap (41); the pressure cap (41) is arranged on the top of the box body (43); a water supply pipe is connected to the box body (43); and a pressure relief port is provided on the pressure cap (41); The pressure circuit comprises an air supply pipe and a one-way valve (42); one end of the air supply pipe is connected to the air outlet of the fuel cell stack (1), and the other end of the air supply pipe is connected to the expansion water tank (4); the one-way valve (42) is arranged between the air outlet of the fuel cell stack (1) and the expansion water tank (4); the compressed air still has a certain pressure after being discharged from the fuel cell stack (1), and is higher than the pressure in the expansion water tank (4); the one-way valve (42) is integrated on the side wall of the tank body (43), and the position of the one-way valve (42) is higher than the highest liquid level in the tank body (43) of the expansion water tank (4), and is used to conduct the air outlet to the expansion water tank (4) and block the expansion water tank (4) from the air outlet; The air circuit also includes an exhaust pipe, which is connected to the air outlet of the fuel cell stack (1), and the compressed air in the fuel cell stack (1) is discharged through the exhaust pipe. A pressure regulating valve (3) is installed on the exhaust pipe, and the pressure regulating valve (3) is used to adjust the air pressure of the air circuit; one end of the air supply pipe is connected to the exhaust pipe, and the connection between the air supply pipe and the exhaust pipe is located upstream of the pressure regulating valve (3).

2. A fuel cell cooling circulation system according to claim 1, It is characterized in that The air circuit also includes an air intake pipe, which is connected to the air compressor (2) and the air inlet of the fuel cell stack (1), and the air compressed by the air compressor (2) is passed into the fuel cell stack (1) through the air intake pipe.

3. A fuel cell cooling circulation system according to claim 1, It is characterized in that The pipeline between the air outlet of the fuel cell stack (1) and the expansion water tank (4) is slanted upward or vertically upward.

4. A fuel cell cooling circulation system according to claim 3, It is characterized in that The fuel cell cooling circulation system further comprises a support structure, wherein the support structure is used to support a pipeline between the air outlet of the fuel cell stack (1) and the expansion water tank (4).

5. A fuel cell cooling circulation system according to claim 1, It is characterized in that The cooling circuit also includes a water inlet pipe, a water outlet pipe and a water replenishment pipe. The water outlet of the water pump (5) is connected to the coolant inlet of the battery stack (1) through the water outlet pipe. The coolant flowing out of the coolant outlet of the battery stack (1) flows back to the water inlet of the water pump (5) through the water inlet pipe after being cooled. The expansion water tank (4) is connected to the water inlet of the water pump (5) through the water replenishment pipe to replenish the coolant for the cooling circuit.

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