Air waste heat utilization structure and method of fuel cell system

Abstract

The application provides an air waste heat utilization structure and method of a fuel cell system, which comprises an air compressor, a middle cooler, a stack and a radiator; a three-way valve is arranged between the air compressor and the middle cooler; a bypass outlet of the three-way valve is communicated to an air outlet of the middle cooler; the air outlet of the middle cooler is communicated to an air inlet of the stack; a blind end plate and a gas port end plate of the stack are both internally provided with cooling liquid flow channels; a cooling liquid outlet of the middle cooler is connected with a cooling liquid main pipeline, the cooling liquid main pipeline is provided with a cooling liquid branch I and a cooling liquid branch II; the cooling liquid branch II is respectively communicated to the inlet of the cooling liquid flow channel in the blind end plate and the gas port end plate; and a throttle valve is installed on the cooling liquid branch II. The technical scheme of the application fully utilizes the waste heat of the compressed air of the air compressor and the waste heat generated after the compressed air of the air compressor is heat-exchanged by the middle cooler.

Description

Technical Field

[0001] This invention relates to the field of fuel cell technology, and more particularly to a structure and method for utilizing waste air heat in a fuel cell system. Background Technology

[0002] A fuel cell is a power generation device that converts the chemical energy of hydrogen and oxygen into electrical energy. The reaction principle of a hydrogen-oxygen fuel cell is the reverse process of water electrolysis. Fuel cells have high energy conversion efficiency, directly converting the chemical energy of fuel into electrical energy without a combustion process. Therefore, they are not limited by the Carnot cycle, and their energy utilization rate is much higher than that of conventional engines, making them suitable as power systems for vehicles, ships, and other transportation vehicles.

[0003] A fuel cell system includes a stack (module), hydrogen system, air system, hydrothermal management system, and control system. The core of the fuel cell is the stack, which is mainly assembled from bipolar plates, membrane electrode assemblies, end plates, and encapsulation components. The air in the fuel cell air system generates a significant amount of heat after compression by the air compressor. While maintaining the required inlet air temperature for the stack, excess heat is carried away by the cooling water in the hydrothermal management system, resulting in waste heat. Current technologies for utilizing fuel cell waste heat often involve using the heat generated by the stack cooling exchange, or using the heat generated by the air compressor in the air system to exchange with the coolant to increase the coolant temperature and accelerate cold start. However, further research on heat regulation for waste heat utilization is lacking, preventing the full utilization of waste heat. Summary of the Invention

[0004] In view of the technical problems existing in the prior art, this invention provides a structure and method for utilizing waste heat from the air in a fuel cell system. This invention can use the heat after the air compressor to regulate the temperature of the air entering the fuel cell stack, so as to accelerate cold start. Moreover, the heat after the air compressor can provide heat preservation for the fuel cell stack through heat exchange with the coolant, which is beneficial to improving the performance of the fuel cell stack at low temperatures.

[0005] The technical means employed in this invention are as follows:

[0006] A structure for utilizing waste air heat in a fuel cell system includes an air compressor, an intercooler, a fuel cell stack, and a radiator.

[0007] A three-way valve is provided between the air compressor and the intercooler; the inlet of the three-way valve is connected to the air outlet of the air compressor, the outlet is connected to the air inlet of the intercooler, and the bypass outlet is connected to the air outlet of the intercooler.

[0008] The air outlet of the intercooler is connected to the air inlet of the fuel cell stack;

[0009] The blind-end plate and the gas port plate of the fuel cell stack are both provided with coolant channels; the coolant inlet of the intercooler is connected to the outlet of the radiator, and the coolant outlet is connected to a main coolant pipeline. The main coolant pipeline is provided with coolant branch I and coolant branch II; coolant branch I is connected to the inlet of the radiator; coolant branch II is connected to the inlet of the coolant channels inside the blind-end plate and the gas port plate, respectively, and a throttle valve is installed on coolant branch II; the outlet of the coolant channels inside the blind-end plate and the gas port plate is connected to the inlet of the radiator.

[0010] Furthermore, the air outlet of the intercooler is connected to the air inlet of the fuel cell stack via connecting pipe I. Temperature sensor I is installed on connecting pipe I to monitor the temperature of the air entering the fuel cell stack. Temperature sensor II is installed on coolant branch II to monitor the temperature of the coolant flowing into the blind end plate and the air inlet end plate.

[0011] Furthermore, the air outlet of the fuel cell stack is connected to the inlet of the back pressure valve via connecting pipe II, and a pressure sensor is installed on the connecting pipe II. The outlet of the back pressure valve is connected to the tailpipe. The pressure sensor is used to monitor the pressure of the air outlet of the fuel cell stack.

[0012] Furthermore, the fuel cell system includes a fuel cell system controller, which is electrically connected to the three-way valve, the throttle valve, and the fuel cell stack, respectively; the fuel cell system controller is used to determine the operating status of the fuel cell stack and to adjust the opening degree of the three-way valve and the throttle valve.

[0013] The present invention also provides a method for utilizing waste air heat in a fuel cell system, which adopts the above-mentioned waste air heat utilization structure for a fuel cell system, specifically including the following: when the fuel cell stack is started, the working status of the fuel cell stack is determined by the fuel cell system controller;

[0014] When the fuel cell system controller determines that the fuel cell stack is in a low-temperature cold start state, it starts the air compressor and opens the inlet, outlet, and bypass outlet of the three-way valve. This allows part of the high-temperature air compressed by the air compressor to be cooled by the intercooler, while the other part is directly mixed with the air outlet of the intercooler through the bypass outlet of the three-way valve to obtain mixed air. The mixed air then enters the fuel cell stack.

[0015] The fuel cell system controller can adjust the opening degree of the bypass outlet of the three-way valve, thereby controlling the temperature of the mixed air;

[0016] The high-temperature air heat after passing through the intercooler is carried away by the coolant inside the intercooler. The throttle valve is opened, and the coolant flows through the coolant branch II into the coolant channels inside the blind end plate and the air port end plate, respectively, to keep the fuel cell stack warm.

[0017] Furthermore, increasing the opening degree of the bypass outlet of the three-way valve can increase the temperature of the mixed air, while decreasing the opening degree of the bypass outlet of the three-way valve can decrease the temperature of the mixed air.

[0018] Furthermore, the fuel cell system controller can adjust the opening of the throttle valve to control the flow rate of the coolant, thereby adjusting the temperature of the coolant; the coolant inside the blind end plate and the gas port end plate flows into the radiator for heat dissipation through the outlet of the coolant flow channel and then flows back to the intercooler.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] The waste heat utilization structure and method for fuel cell systems provided by this invention fully utilizes the waste heat generated after the air compressor compresses air and the waste heat generated after the air compressor compresses air through the intercooler. By utilizing the waste heat after the air compressor compresses air, the temperature of the air entering the stack during low-temperature startup is increased, shortening the low-temperature cold start time and improving the performance of the fuel cell stack during low-temperature operation. At the same time, the waste heat generated after the air compressor compresses air through the intercooler is used to heat and insulate the fuel cell stack, shortening the low-temperature cold start time. This can effectively improve the single low temperature problem during low-temperature cold start of the fuel cell stack and improve the performance of the fuel cell stack.

[0021] Based on the above reasons, this invention can be widely promoted in the field of fuel cells. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a structural block diagram of the air waste heat utilization structure of the fuel cell system described in this invention.

[0024] Figure 2 This is a flowchart of the air waste heat utilization method of the fuel cell system described in this invention.

[0025] In the diagram: 1. Air compressor; 2. Three-way valve; 3. Intercooler; 4. Temperature sensor I; 5. Temperature sensor II; 6. Pressure sensor; 7. Back pressure valve; 8. Fuel cell stack; 9. Blind end plate; 10. Air port end plate; 11. Throttle valve; 12. Radiator; 13. Tail exhaust; 14. Main coolant line; 15. Coolant branch line I; 16. Coolant branch line II. Detailed Implementation

[0026] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0029] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0030] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention. The directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0031] For ease of description, spatial relative terms such as "above," "over," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation besides the orientation of the device as described in the figures. For example, if the device in the figures is inverted, a device described as "above" or "above" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0032] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0033] Example 1

[0034] like Figure 1-2 As shown, the present invention provides a structure and method for utilizing waste heat from air in a fuel cell system. It can utilize the waste heat from air compressed by the air compressor, as well as the waste heat from the high-temperature air after compression by the air compressor passing through the intercooler. Furthermore, different control methods can be adopted for the utilization of waste heat from air depending on the ambient temperature.

[0035] like Figure 1 As shown, the present invention provides a structure for utilizing waste air heat in a fuel cell system, including an air compressor 1, an intercooler 3, a fuel cell stack 8, and a radiator 12.

[0036] A three-way valve 2 is provided between the air compressor 1 and the intercooler 3; the inlet of the three-way valve 2 is connected to the air outlet of the air compressor 1, the outlet is connected to the air inlet of the intercooler 3, and the bypass outlet is connected to the air outlet of the intercooler 3.

[0037] The air outlet of the intercooler 3 is connected to the air inlet of the fuel cell stack 8;

[0038] The blind end plate 9 and the air inlet end plate 10 of the fuel cell stack 8 are both provided with coolant channels; the coolant inlet of the intercooler 3 is connected to the outlet of the radiator 12, and the coolant outlet is connected to the main coolant pipeline 14. The main coolant pipeline 14 is provided with coolant branch I 15 and coolant branch II 16; coolant branch I 15 is connected to the inlet of the radiator 12; coolant branch II 16 is connected to the inlet of the coolant channels inside the blind end plate 9 and the air inlet end plate 10 respectively, and a throttle valve 11 is installed on the coolant branch II 16; the outlets of the coolant channels inside the blind end plate 9 and the air inlet end plate 10 are both connected to the inlet of the radiator 12.

[0039] Furthermore, the air outlet of the intercooler 3 is connected to the air inlet of the fuel cell stack 8 via a connecting pipe I. A temperature sensor I4 is installed on the connecting pipe I, and the temperature sensor I4 is used to monitor the temperature of the air entering the fuel cell stack 8. A temperature sensor II5 is installed on the coolant branch II16, and the temperature sensor II5 is used to monitor the temperature of the coolant flowing into the blind end plate 9 and the air port end plate 10.

[0040] Furthermore, the air outlet of the fuel cell stack 8 is connected to the inlet of the back pressure valve 7 via a connecting pipe II. A pressure sensor 6 is installed on the connecting pipe II. The outlet of the back pressure valve 7 is connected to the tail drain 13. The pressure sensor 6 is used to monitor the pressure of the air outlet of the fuel cell stack 8.

[0041] Furthermore, the fuel cell system includes a fuel cell system controller (FCU), which is electrically connected to the three-way valve 2, the temperature sensor I 4, the temperature sensor II 5, the throttle valve 11, the pressure sensor 6, the back pressure valve 7, and the fuel cell stack 8, respectively. The fuel cell system controller is used to determine the operating status of the fuel cell stack 8 and to adjust the opening of the three-way valve 2, the throttle valve 11, and the back pressure valve 7 according to the monitoring results of the temperature sensor I 4, the temperature sensor II 5, and the pressure sensor 6, respectively.

[0042] The waste heat utilization structure of the fuel cell system provided by the present invention has a three-way valve 2 installed between the air compressor 1 and the intercooler 3, which can control whether all the high-temperature gas after the air compressor 1 passes through the intercooler 3; at the same time, the coolant chamber of the intercooler 3 is connected in series with the coolant flow channels inside the blind end plate 9 and the air port end plate 10, which can carry the heat of the intercooler 3 to the blind end plate 9 and the air port end plate 10 through the coolant, for the purpose of heat preservation of the fuel cell stack 8.

[0043] like Figure 2 As shown, the present invention also provides a method for utilizing waste air heat in a fuel cell system, which adopts the above-mentioned waste air heat utilization structure of the fuel cell system, specifically including the following: when the fuel cell stack 8 is turned on, the working state of the fuel cell stack 8 is determined by the fuel cell system controller;

[0044] When the fuel cell system controller determines that the fuel cell stack 8 is in a low-temperature cold start state, it starts the air compressor 1 and opens the inlet, outlet, and bypass outlet of the three-way valve 2. This allows part of the high-temperature air compressed by the air compressor 1 to be cooled by the intercooler 3, while the other part is directly mixed with the air outlet of the intercooler 3 through the bypass outlet of the three-way valve 2 to obtain mixed air. The mixed air enters the fuel cell stack 8 and undergoes a chemical reaction. The reacted air is then discharged through the tailpipe 13 via the back pressure valve 7.

[0045] The fuel cell system controller can adjust the opening of the bypass outlet of the three-way valve 2 according to the temperature of the mixed air monitored by the temperature sensor I4, thereby controlling the temperature of the mixed air to meet the requirements of the fuel cell stack 8;

[0046] The high-temperature air heat passing through the intercooler 3 is carried away by the coolant inside the intercooler 3. The throttle valve 11 is opened, and the coolant flows through the coolant branch II 16 into the coolant channels inside the blind end plate 9 and the air port end plate 10 respectively, for the purpose of keeping the fuel cell stack 8 warm.

[0047] Furthermore, only a portion of the coolant flowing out of the intercooler 3 needs to flow into the coolant channels inside the blind end plate 9 and the air port end plate 10 via the coolant branch II 16 to meet the heat preservation requirements of the fuel cell stack 8 in the low-temperature cold start state, while the rest flows into the radiator 12 via the coolant branch I 15.

[0048] Furthermore, increasing the opening degree of the bypass outlet of the three-way valve 2 can increase the temperature of the mixed air, while decreasing the opening degree of the bypass outlet of the three-way valve 2 can decrease the temperature of the mixed air.

[0049] Furthermore, the fuel cell system controller can adjust the opening of the throttle valve 11 to control the flow rate of the coolant based on the temperature of the coolant flowing into the blind end plate 9 and the gas port end plate 10 monitored by the temperature sensor II5, thereby adjusting the temperature of the coolant; the coolant inside the blind end plate 9 and the gas port end plate 10 flows into the radiator 12 for heat dissipation through the outlet of the coolant flow channel and then flows back to the intercooler 3.

[0050] Furthermore, during the low-temperature cold start process of the fuel cell stack 8, the throttle valve 11 remains open, and the coolant continuously circulates between the intercooler 3, the blind end plate 9, and the air port end plate 10 to keep the fuel cell stack 8 warm.

[0051] Furthermore, the fuel cell system controller can adjust the opening of the back pressure valve 7 according to the pressure of the air outlet of the fuel cell stack 8 monitored by the pressure sensor 6, thereby controlling the pressure of the air cavity inside the fuel cell stack 8 to meet the requirements of the fuel cell stack 8.

[0052] Furthermore, when the fuel cell system controller determines that the fuel cell stack 8 is in normal operating condition, it starts the air compressor 1, opens the inlet and outlet of the three-way valve 2, and closes the bypass outlet of the three-way valve 2, so that all the high-temperature air compressed by the air compressor 1 is cooled by the intercooler 3, and then introduced into the fuel cell stack 8 for chemical reaction. The air after reaction is discharged through the tailpipe 13 via the back pressure valve 7.

[0053] The high-temperature air heat passing through the intercooler 3 is carried away by the coolant inside the intercooler 3. The throttle valve 11 is closed, allowing the coolant to flow directly into the radiator 12 for heat dissipation through the coolant branch I 15, and then flow back to the intercooler 3.

[0054] The present invention provides a structure and method for utilizing waste heat from the air in a fuel cell system. A structure for utilizing the waste heat of high-temperature gas after the air compressor is designed. This waste heat increases the temperature of the air entering the stack during low-temperature startup, shortening the cold start time and improving the performance of the fuel cell stack during low-temperature operation. Simultaneously, a structure for heat preservation and heating of the fuel cell stack is designed, utilizing the coolant from the intercooler for heat exchange. Coolant flow channels are located within the blind end plate and the air port end plate of the fuel cell stack, introducing the coolant from the intercooler into these channels, thus utilizing the waste heat of the coolant and shortening the low-temperature cold start time. This effectively improves the single-low temperature problem during low-temperature cold start of the fuel cell stack.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A structure for utilizing waste air heat in a fuel cell system, characterized in that, Includes air compressor, intercooler, fuel cell stack and radiator; A three-way valve is provided between the air compressor and the intercooler; the inlet of the three-way valve is connected to the air outlet of the air compressor, the outlet is connected to the air inlet of the intercooler, and the bypass outlet is connected to the air outlet of the intercooler. The air outlet of the intercooler is connected to the air inlet of the fuel cell stack; The blind-end plate and the gas port plate of the fuel cell stack are both provided with coolant channels; the coolant inlet of the intercooler is connected to the outlet of the radiator, and the coolant outlet is connected to a main coolant pipeline. The main coolant pipeline is provided with coolant branch I and coolant branch II; coolant branch I is connected to the inlet of the radiator; coolant branch II is connected to the inlet of the coolant channels inside the blind-end plate and the gas port plate, respectively, and a throttle valve is installed on coolant branch II; the outlets of the coolant channels inside the blind-end plate and the gas port plate are both connected to the inlet of the radiator. The fuel cell system includes a fuel cell system controller, which is electrically connected to the three-way valve, the throttle valve, and the fuel cell stack. The fuel cell system controller is used to determine the operating status of the fuel cell stack and to adjust the opening of the three-way valve and the throttle valve. When the fuel cell system controller determines that the fuel cell stack is in a low-temperature cold start state, it starts the air compressor and opens the inlet, outlet, and bypass outlet of the three-way valve. This allows part of the high-temperature air compressed by the air compressor to be cooled by the intercooler, while the other part directly mixes with the air outlet of the intercooler through the bypass outlet of the three-way valve to form mixed air. The mixed air enters the fuel cell stack. The fuel cell system controller can adjust the opening of the bypass outlet of the three-way valve to control the temperature of the mixed air. The heat of the high-temperature air passing through the intercooler is carried away by the coolant inside the intercooler. The throttle valve is opened, and the coolant flows through the coolant branch II into the coolant channels inside the blind end plate and the air port end plate to keep the fuel cell stack warm.

2. The air waste heat utilization structure of the fuel cell system according to claim 1, characterized in that, The air outlet of the intercooler is connected to the air inlet of the fuel cell stack via connecting pipe I. Temperature sensor I is installed on connecting pipe I to monitor the temperature of the air entering the fuel cell stack. Temperature sensor II is installed on coolant branch II to monitor the temperature of the coolant flowing into the blind end plate and the air inlet end plate.

3. The air waste heat utilization structure of the fuel cell system according to claim 1, characterized in that, The air outlet of the fuel cell stack is connected to the inlet of the back pressure valve via connecting pipe II. A pressure sensor is installed on connecting pipe II. The outlet of the back pressure valve is connected to the tailpipe. The pressure sensor is used to monitor the pressure of the air outlet of the fuel cell stack.

4. A method for utilizing waste air heat in a fuel cell system, characterized in that, The structure for utilizing waste air heat in a fuel cell system as described in claim 1 is adopted, specifically including the following: when the fuel cell stack is started, the working status of the fuel cell stack is determined by the fuel cell system controller; When the fuel cell system controller determines that the fuel cell stack is in a low-temperature cold start state, it starts the air compressor and opens the inlet, outlet, and bypass outlet of the three-way valve. This allows part of the high-temperature air compressed by the air compressor to be cooled by the intercooler, while the other part is directly mixed with the air outlet of the intercooler through the bypass outlet of the three-way valve to obtain mixed air. The mixed air then enters the fuel cell stack. The fuel cell system controller can adjust the opening degree of the bypass outlet of the three-way valve, thereby controlling the temperature of the mixed air; The high-temperature air heat after passing through the intercooler is carried away by the coolant inside the intercooler. The throttle valve is opened, and the coolant flows through the coolant branch II into the coolant channels inside the blind end plate and the air port end plate, respectively, to keep the fuel cell stack warm.

5. The method for utilizing waste air heat in a fuel cell system according to claim 4, characterized in that, Increasing the opening of the bypass outlet of the three-way valve can increase the temperature of the mixed air, while decreasing the opening of the bypass outlet of the three-way valve can decrease the temperature of the mixed air.

6. The method for utilizing waste air heat in a fuel cell system according to claim 4, characterized in that, The fuel cell system controller can adjust the opening of the throttle valve to control the flow rate of the coolant, thereby adjusting the temperature of the coolant; the coolant inside the blind end plate and the gas port end plate flows into the radiator for heat dissipation through the outlet of the coolant flow channel and then flows back to the intercooler.

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