Fuel cell system and vehicle including the same

Abstract

The present disclosure relates to a fuel cell system (100) and a vehicle comprising the fuel cell system (100). The fuel cell system (100) is capable of thawing the dedicated component (120) by directing coolant from the fuel cell stack (110) to the dedicated component (120) via the coolant branch line.

Description

Technical Field

[0001] The present disclosure generally relates to a fuel cell system and an aircraft having the same, wherein the aircraft allows for thawing of the fuel cell system. In particular, the present disclosure relates to a fuel cell system and an aircraft having the same, wherein the coolant branch line directs coolant to specific components of the fuel cell system. Background Art

[0002] In a fuel cell system, chemical energy is converted into electricity and heat. Specifically, if hydrogen is used as fuel for a fuel cell, the resulting reaction product is water. This reaction product in the fuel cell is also known as process water or water, which is discharged from the outlet of the fuel cell stack.

[0003] If such a fuel cell system is used in an environment where sub-zero temperatures may occur, there is a risk that the process water in the fuel cell stack or any components downstream of the fuel cell stack outlet may freeze. This, in turn, could block the corresponding portion of the fuel cell system. Therefore, if the fuel cell stack begins operating while ice accumulates in some of the fuel cell system's components, the fuel cell system may fail to operate.

[0004] Therefore, fuel cell systems are provided with an electric heater to heat the fuel cell system or parts thereof before the fuel cell stack can begin operation. Summary of the Invention

[0005] Therefore, an object of the present disclosure is to provide a fuel cell system that allows for quick startup and has a simple setup.

[0006] This object is solved by the invention as defined in its main aspects. Preferred embodiments are defined in its subsidiary aspects.

[0007] According to a first aspect to better understand the present disclosure, a fuel cell system includes: a fuel cell stack; a cooling circuit configured to cool the fuel cell stack; and a coolant branch line connected to the cooling circuit and guiding the coolant of the cooling circuit to dedicated components of the fuel cell system.

[0008] When a fuel cell stack begins operating, fuel (e.g., hydrogen) is converted into electricity, water, and heat. Because the fuel cell system's cooling circuit is specifically configured to transfer heat away from the fuel cell stack (to maintain the stack's operating temperature, e.g., 80°C to 90°C), the heat generated by starting the fuel cell stack heats the coolant in the cooling circuit. Consequently, the heat is easily transferred to the dedicated components of the fuel cell system. Consequently, the temperature of the dedicated components rises, particularly to above 0°C, allowing the dedicated components to automatically thaw during startup of the fuel cell stack.

[0009] This heat transfer from the fuel cell stack to the dedicated components can even occur without the need for coolant delivery. By way of example only, the warmed coolant can automatically move within the cooling circuit due to thermal expansion of the coolant or through convection. Furthermore, the coolant can change its aggregate state, such as from a liquid to a gas, when exceeding a certain temperature, facilitating the transport of this coolant to the dedicated components.

[0010] Additionally, specialized components can be thawed without electronic heaters or other components requiring their own energy and maintenance.

[0011] In a variant implementation, the dedicated component may be a component of the fuel cell system that comes into contact with the process water generated in the fuel cell stack. For example, the dedicated component may be a part of the fuel cell stack on its cathode side where water is generated, or any component arranged downstream of the cathode side specifically for draining water from the fuel cell stack.

[0012] In various implementations, the dedicated components may include a water separator, a drain pipe, a valve, and / or a water tank. The water separator separates water (liquid droplets) from gas (e.g., air and / or steam). The drain pipe may be a pipe that discharges water from the cathode side of the fuel cell stack. The valve may be a valve in the drain pipe and / or at the outlet of the cathode side of the fuel cell stack. The water tank may be a buffer tank in, at, or near the fuel cell stack and / or the water tank may be connected to the drain pipe.

[0013] In a variant implementation, the coolant branch lines may include: a supply branch line, which begins at a branch point of a coolant discharge line of the cooling circuit, located at the coolant outlet of the fuel cell stack; and a return branch line, whose end portion is connected to the cooling circuit downstream of the branch point of the coolant discharge line. Furthermore, dedicated components may be arranged at the end of the supply branch line and at the beginning of the return branch line.

[0014] Thus, the coolant branch line bypasses at least a small portion of the coolant circuit to direct the coolant to the dedicated component. Because the coolant branch line branches off from the coolant discharge line, it is positioned closest to the hottest point in the system, namely the fuel cell stack. Consequently, coolant is directed to the dedicated component from a portion of the cooling circuit that is physically close to a heat source that heats the coolant in the cooling circuit.

[0015] In an implementation variation, the dedicated component may include a heat exchange device through which the coolant of the coolant branch line flows and which is configured to exchange heat between the coolant and the dedicated component.

[0016] In an implementation variant, the heat exchange device can be a coolant conduit that contacts and / or surrounds the dedicated component or at least a portion of the dedicated component. The heat exchange device can be a double-walled conduit or component, wherein the coolant is guided into the spacing of the double-walled conduit or component. For example, the dedicated component can be at least partially surrounded by an additional housing, and the coolant from the coolant branch line flows through the space inside the housing, for example, around the dedicated component or the portion of the dedicated component.

[0017] In an implementation variant, the end of the return branch line can be connected to a coolant discharge line, a coolant supply line that supplies coolant to the fuel cell stack, or a bypass line that connects the coolant discharge line and the coolant supply line. Thus, the coolant branch line is a short line or a bypass line of a portion of the coolant circuit. Depending on where the coolant of the coolant branch line re-enters the portion of the cooling circuit, the coolant can quickly return to the fuel cell stack, so that this "short circuit" quickly heats up during start-up of the fuel cell stack and the dedicated component is thawed in a quick manner.

[0018] In an implementation variant, the cooling circuit can further comprise a transport device configured to transport coolant through the cooling circuit, and a heat exchanger configured to thermally couple the coolant received from the coolant discharge line with a heat sink. Thus, the cooling circuit can be a conventional cooling circuit for a fuel cell stack, wherein heat generated by the fuel cell stack is transferred to the heat sink. In particular, during start-up of the fuel cell stack, the dedicated component, as well as other parts of the fuel cell stack, are heated up faster due to the coolant branch line compared to a conventional fuel cell system.

[0019] In an implementation variant, the bypass line can connect the coolant discharge line with a coolant line of the cooling circuit that connects the heat exchanger with the transport device. Thus, the cooling circuit can be operated without cooling the coolant at the heat exchanger. This in particular facilitates warming up of the dedicated component and further facilitates a quick start-up of the fuel cell stack.

[0020] In an implementation variant, the fuel cell system can further comprise a valve in the supply branch line and / or the return branch line in order to couple and decouple the coolant branch line from the rest of the cooling circuit.

[0021] In an implementation variant, the fuel cell system can further comprise a control unit configured to control the delivery device to stop or to operate at a reduced delivery rate during a start-up phase of the fuel cell stack. Thus, instead of a regular operation of the fuel cell stack and the cooling circuit, during the start-up phase, the cooling circuit is either not operated at all or is operated in a way that reduces the heat transport. This facilitates heating of the coolant in the part of the cooling circuit comprising the coolant branch line, so that the dedicated components are warmed up and the fuel cell stack can quickly reach an operating temperature.

[0022] In an implementation variant, the control unit can further be configured to close at least one valve of the cooling circuit to prevent the coolant from flowing through the heat exchanger. Thus, even if the delivery device is operated, the coolant can only flow through the part of the cooling circuit comprising the coolant branch line, without passing through the heat exchanger, where the coolant would lose heat to the heat sink (i.e. the coolant would be cooled).

[0023] According to a second aspect for better understanding the present disclosure, a vehicle comprises at least one fuel cell system of the first aspect or one or more variants of the variants thereof.

[0024] The vehicle can be, by way of example only, an aircraft or a spacecraft that can be exposed to low temperatures. Thus, the fuel cell system in such a vehicle typically has a risk of freezing or at least partially freezing when exposed to low temperatures.

[0025] The present disclosure is not limited to the aspects and variants described in the form and order. In particular, the description of the aspects and variants should not be understood as a specific, restrictive grouping of features. It should be understood that the present disclosure also encompasses combinations of aspects and variants. Thus, each variant or optional feature can be combined with any other aspect, variant, optional feature or even combinations thereof. BRIEF DESCRIPTION OF DRAWINGS

[0026] In the following, the present disclosure will be further described with reference to the exemplary embodiments illustrated in the drawings, in which:

[0027] Figure 1 schematically illustrates a fuel cell system;

[0028] Figure 2 schematically illustrates details of the dedicated components of the fuel cell system; and

[0029] Figure 3 schematically illustrates a vehicle comprising the fuel cell system. DETAILED DESCRIPTION

[0030] In the following description, for purposes of explanation and not limitation, specific details are set forth in order to provide a thorough understanding of the present disclosure. It will be apparent to one skilled in the art that the present disclosure can be practiced in other implementations that depart from these specific details.

[0031] Figure 1 A fuel cell system 100 is schematically illustrated, which comprises a fuel cell stack 110 and a cooling circuit 200 configured to cool the fuel cell stack 110. In particular, the cooling circuit comprises a coolant discharge line 205 provided at (starting at) a coolant outlet of the fuel cell stack 110, a coolant supply line 206 supplying coolant to the fuel cell stack 110, and a conveying device 220 configured to convey the coolant through the cooling circuit 200. A heat exchanger 210 of the cooling circuit 200 thermally couples the coolant of the cooling circuit 200 with a heat sink (at Figure 1 An air is exemplarily illustrated in the middle to be conveyed by a fan as heat sink through the heat exchanger). Thus, when the conveying device 220 is operated, the coolant is circulated through the coolant supply line 206, the fuel cell stack 110, the coolant discharge line 205, the heat exchanger 210 and back to the conveying device 220. This allows cooling the fuel cell stack 110, i.e. transporting heat generated during regular operation of the fuel cell stack 110 to the heat sink at the heat exchanger 210.

[0032] The cooling circuit 200 can further comprise a bypass line 207 allowing to bypass the heat exchanger 210. The bypass line 207 starts at the coolant discharge line 205 and ends upstream of the conveying device 220. For example, a three-way valve 230 can be employed to direct at least a portion of the coolant from the coolant discharge line 205 into the bypass line 207 and / or to the heat exchanger 210. Thus, the temperature of the coolant before entering the conveying device 220 can be controlled by the three-way valve 230.

[0033] Further, a control valve 215 can be provided in the cooling circuit 200 downstream of the heat exchanger 210 and upstream of the conveying device 220. The control valve 215 also allows to control the amount of coolant flowing from the heat exchanger 210 to the conveying device 220. It should be appreciated that the control valve 215 can also be used to control the amount of coolant bypassing the heat exchanger 210 via the bypass line 207.

[0034] The fuel cell system 100 further comprises coolant branch lines 125, 126 connected to the cooling circuit 200 and directing the coolant of the cooling circuit 200 to dedicated components 120 of the fuel cell system 100. Figure 1 The valve 120 is shown as such a dedicated component only for example. It should be understood that any other dedicated components of the fuel cell system 100 may be provided with coolant via the coolant branch lines 125, 126. Figure 1 As shown in FIG, this also includes components 130 in or near the fuel cell stack 110. Explanation of dedicated components and coolant branch lines 125, 126 with respect to the "external" valve 120 increases Figure 1 clarity.

[0035] Dedicated components may be components of the fuel cell system 100 that come into contact with the process water produced in the fuel cell stack 110. Examples of such dedicated components are the water separator 130, the drain line 112, the valve 120, and / or a water tank (the water tank is not specifically illustrated because the drained water is shown only as a droplet at the end of the drain line 112 on which an exemplary water tank may be mounted).

[0036] The coolant branch lines may include a supply branch line 125 that begins at a branch point of the coolant discharge line 205. The supply branch line 125 allows coolant to be directed from the coolant discharge line 205 to the dedicated component 120. Similarly, a return branch line 126 may begin at the dedicated component 120, and the end of the return branch line 126 is connected to the cooling circuit 200 downstream of the branch point of the coolant discharge line 205. Thus, the dedicated component 120 is arranged at the end of the supply branch line 125 and the beginning of the return branch line 126. Thus, the coolant in the coolant branch lines 125, 126, which form a short line or short-circuit of the entire cooling circuit 200, is taken away from the cooling circuit 200 downstream near the coolant outlet of the fuel cell stack 110 where the coolant has the highest temperature, or at the coolant outlet of the fuel cell stack 110.

[0037] Figure 2 Schematically illustrates a dedicated component 120, such as Figure 1 Detail of the valve 120 of the fuel cell system 100 . The dedicated component 120 includes a heat exchange device 127 through which the coolant of the coolant branch lines 125 , 126 flows and is configured to exchange heat between the coolant and the dedicated component 120 .

[0038] In more detail, the exemplary valve 120 is provided with a surrounding housing 127. The housing 127 can form a double-walled pipe together with the valve line 121. The intermediate space formed between the valve 120 (particularly the valve line 121) and the surrounding housing 127 provides space for the coolant. Therefore, the supply branch line 125 can be fluidically coupled to the intermediate space so that the coolant of the supply branch line 125 flows through the intermediate space ( Figure 2After exchanging heat with a dedicated component 120 (here a valve 120 ), the (cooled) coolant can flow from the intermediate space into a return branch line 126 and back to the cooling circuit 200 .

[0039] It should be understood that other heat exchange arrangements may be provided. By way of example only, the supply branch line 125 may be wound around the dedicated components 120, 130. Alternatively or additionally, the supply branch line 125 and / or the return branch line 126 may be widened and flattened to cover a larger area of ​​the dedicated components 120, 130.

[0040] The valve 120 comprises a closing member and an actuator, such as a ball valve 120 having a disc 123 and a wheel with a stem 122 as shown in the exemplary illustration. Figure 2 By rotating the wheel 122, the disk 123 can be moved up and down to close the valve passage at the valve seat 124. Since water can be present in the drain pipe 112 and therefore in the valve 120, and in particular at the disk 123 and the valve seat 124, the valve 120 is at risk of freezing and blocking if the fuel cell system is exposed to freezing temperatures during a period in which the fuel cell stack 110 is not in operation.

[0041] Therefore, when the fuel cell stack 110 begins to operate, the heat generated in the fuel cell stack due to the reaction of the fuel and the oxidant will heat the coolant in the cooling circuit 200. Since the supply branch line 125 branches off from the coolant exhaust line 205 at or near the coolant outlet of the fuel cell stack 110, the dedicated components 120 can be heated by the coolant in the supply branch line 125. Therefore, thawing of the dedicated components 120 can be achieved in a rapid manner during the startup of the fuel cell stack 110.

[0042] Return to reference Figure 1 The fuel cell system 100 may include a control unit 180 configured to control at least a portion of the cooling circuit 200, such as the delivery device 220. For example, during the startup phase of the fuel cell stack 110, the control unit 180 may stop the delivery device 220 or operate it at a reduced delivery rate. Thus, coolant may be transported through the cooling circuit 200 including the coolant branch lines 125, 126. Therefore, during startup of the fuel cell stack 110, the dedicated components 120, 130 may be heated and thawed.

[0043] In addition, the control unit 180 may further close the control valve 215 of the cooling circuit. Therefore, the coolant is blocked from flowing through the heat exchanger 210, so that the coolant in the cooling circuit 200 does not lose heat to the radiator.

[0044] Furthermore, the control unit 180 can further control the three-way valve 230, in particular during start-up of the fuel cell stack 110. The control unit 180 can either completely close the three-way valve or can direct the coolant through the bypass line 207.

[0045] The control unit 180 can also control the valves 215, 230 and the delivery device 220 based on the installation of the return branch line 126. In particular, the end of the return branch line 126 can be connected to the coolant discharge line 205 (as illustrated by the solid line 126 in Fig. 10). Thus, in case a coolant circulation is desired, the control unit 180 can control the three-way valve 230 such that the coolant flows through the bypass line 207. Alternatively, the end of the return branch line 126 can be connected to the coolant supply line 206 or the bypass line 207 (as illustrated by the respective dashed line in Fig. 10). In this case, the control unit 180 can completely close the three-way valve 230. Figure 1 Figure 1

[0046] In any case, during the start-up phase of the fuel cell stack 110, the coolant can be delivered, for example, by convection (and gravity) and / or by a reduced speed of the delivery device 220. The reduced speed means a smaller delivery rate than during operation of the delivery device 220 when the fuel cell stack 110 is operated at regular operating temperatures and requires the full cooling capacity of the cooling circuit 200.

[0047] Figure 3 A vehicle comprising the fuel cell system 100 is schematically illustrated. The vehicle can be, for example only, an aircraft 1 employing the fuel cell system 100 of Figure 1 and Figure 2 in order to generate the required electrical power on the aircraft 1.

[0048] It is believed that the advantages of the technology presented herein will be fully understood from the foregoing description, and it will be apparent that various changes can be made in the form, constructions and arrangement of the exemplary aspects thereof without departing from the scope of the disclosure or sacrificing all of its advantageous effects. Because the technology presented herein can be varied in many ways, it will be recognized that the disclosure should be limited only by the scope of the claims that follow.​​

Claims

1. A fuel cell system (100), comprising: a fuel cell stack (110); and a cooling circuit (200) configured to cool the fuel cell stack (110), Characterized in that the fuel cell system (100) further comprises: A coolant branch line is connected to the cooling circuit (200) and guides the coolant of the cooling circuit (200) to dedicated components (120, 130) of the fuel cell system.

2. The fuel cell system (100) according to claim 1, wherein: The dedicated component is a component of the fuel cell system (100) that comes into contact with the treated water generated in the fuel cell stack (110).

3. The fuel cell system (100) according to claim 2, wherein: The dedicated components are a water separator (130), a drain pipe (112), a valve (120) and / or a water tank.

4. The fuel cell system (100) according to any one of claims 1 to 3, wherein: The coolant branch line comprises: a supply branch line (125) which starts at a branch point of a coolant discharge line (205) of the cooling circuit (200) provided at a coolant outlet of the fuel cell stack (110); and a return branch line (126) whose end is connected to the cooling circuit (200) downstream of the branch point of the coolant discharge line (205), and The dedicated components (120, 130) are arranged at the end of the supply branch line (125) and at the starting point of the return branch line (126).

5. The fuel cell system (100) according to any one of claims 1 to 3, wherein: The dedicated component (120, 130) includes a heat exchange device (127) through which the coolant of the coolant branch line flows and the heat exchange device (127) is configured to exchange heat between the coolant and the dedicated component (120, 130).

6. The fuel cell system (100) according to claim 4, wherein: The end of the return branch line (126) is connected to the coolant discharge line (205), a coolant supply line (206) that supplies coolant to the fuel cell stack (110), or a bypass line (207) that connects the coolant discharge line (205) and the coolant supply line (206).

7. The fuel cell system (100) according to claim 6, wherein: The cooling circuit (200) further includes a delivery device (220) configured to deliver coolant through the cooling circuit; and a heat exchanger (210) configured to thermally couple the coolant received from the coolant discharge line (205) to a radiator.

8. The fuel cell system (100) according to claim 7, wherein: The bypass line (207) connects the coolant discharge line (205) to a coolant line of the cooling circuit, and the coolant line connects the heat exchanger (210) to the delivery device (220).

9. The fuel cell system (100) according to claim 7, further comprising: A control unit (180) is configured to control the delivery device (220) to stop or operate at a reduced delivery rate during a startup phase of the fuel cell stack (110).

10. The fuel cell system (100) according to claim 9, wherein: The control unit (180) is further configured to close at least one valve (215, 230) of the cooling circuit to prevent the coolant from flowing through the heat exchanger (210).

11. A carrier (1), comprising: At least one fuel cell system (100) according to any one of claims 1 to 10.

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