Fuel cell system; method for operating a fuel cell system
By coupling the cooling capacity of an inactive fuel cell stack with an active one using existing components, the method addresses thermal stress issues, enhancing cooling efficiency and extending the active stack's lifespan.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- ROBERT BOSCH GMBH
- Filing Date
- 2025-12-04
- Publication Date
- 2026-06-18
AI Technical Summary
Existing fuel cell systems face challenges in efficiently utilizing the cooling capacity of inactive fuel cell stacks to manage thermal stress and extend the lifespan of active stacks without requiring additional components.
The cooling capacity of an inactive first cooling circuit is coupled with an active second cooling circuit, utilizing existing components like 3-way valves and pumps to distribute coolant flow effectively, thereby enhancing temperature control and reducing thermal stress on the active stack.
This approach increases the cooling capacity available to the active stack, minimizing thermal stress and extending its lifespan while maintaining system efficiency and reducing component costs.
Smart Images
Figure EP2025085537_18062026_PF_FP_ABST
Abstract
Description
[0001] R. 416035
[0002] - 1 -
[0003] Description
[0004] title
[0005] Fuel cell system; method for operating a fuel cell system
[0006] The invention relates to a fuel cell system with the features of the preamble of independent claim 1. Furthermore, the invention relates to a method for operating a fuel cell system with the features of the preamble of independent claim 5.
[0007] State of the art
[0008] It is known from the prior art that fuel cell systems include a fuel cell stack, an anode system, a cathode system and a cooling circuit.
[0009] During operation of the fuel cell system, the reactants hydrogen and air flow into the fuel cell stack to obtain electrical energy in a cold combustion reaction.
[0010] The waste heat from the fuel cell stack is dissipated via a cooling circuit and can be released into the environment through a vehicle radiator. A coolant is recirculated within this cooling circuit.
[0011] European patent application EP 3747073 B1 describes a method for operating a fuel cell system with at least two fuel cell stacks and four different operating modes. The operating modes include preheating inactive fuel cell stacks, operating active and inactive fuel cell stacks, and keeping inactive fuel cell stacks warm with active fuel cell stacks. R. 416035
[0012] - 2 -
[0013] Disclosure of the invention
[0014] The invention relates to a fuel cell system according to independent claim 1 and a method for operating a fuel cell system according to independent claim 5. Further features and details of the invention will become apparent from the respective dependent claims, the description and the drawings.
[0015] The fuel cell system and method according to the invention have the advantage that the available cooling capacity of a first cooling circuit of a first fuel cell stack, which is inactive, can be used for a second fuel cell stack, which is active. The cooling capacity of the first cooling circuit can be used, in addition to the cooling capacity of a second cooling circuit of the second fuel cell stack, for temperature control of the second fuel cell stack. This further reduces the aging of the second fuel cell stack by ensuring effective temperature control.
[0016] It is advantageous if the coolant from a first vehicle radiator line and a second vehicle radiator line is fed into the manifold downstream of a bypass line. This allows the available cooling capacity to be distributed between the first and second fuel cell stacks without the need for additional components.
[0017] Advantageously, a first mass flow control device is arranged in the first vehicle radiator line, and a second mass flow control device is arranged in the second vehicle radiator line. This facilitates the distribution of mass flows by utilizing existing components of the fuel cell system, thus enabling effective control of the cooling capacity and a space-saving and cost-effective design of the fuel cell system.
[0018] It is advantageous if a first valve, in particular a 3-way valve, is arranged between a first coolant outlet and the first vehicle radiator line, and a second valve, in particular a 3-way valve, is arranged between a second coolant outlet and the second vehicle radiator line. This allows for effective control of the coolant flow and reduces the thermal load. R. 416035
[0019] - 3 - of the second fuel cell stack can be specifically minimized, which increases the lifespan of the second fuel cell stack.
[0020] Advantageously, the cooling capacity of the first cooling circuit of the first fuel cell stack is coupled into the second fuel cell stack by essentially routing the coolant from the first cooling circuit through a coolant path of the second fuel cell stack. This allows an increased amount of cooling capacity to be made available to the second fuel cell stack, thus preventing any reduction in the power output of the second fuel cell stack due to excessive thermal stress.
[0021] It is advantageous if the cooling capacity of the first cooling circuit is coupled into the second fuel cell stack, wherein a first pumping unit arranged in the first cooling circuit is inactive and a second pumping unit arranged in the second cooling circuit is active. This allows the efficiency of the fuel cell system to be increased by also carrying out the inventive method with a first pumping unit as an auxiliary consumer that is inactive.
[0022] Advantageously, the cooling capacity of the first cooling circuit of the first fuel cell stack is coupled into the second fuel cell stack, with the coolant from the second coolant outlet of the second fuel cell stack flowing at least partially into the first vehicle radiator line, in which a first vehicle radiator is located, via the bypass line. By selectively distributing the coolant from the second coolant outlet between the first and second vehicle radiator lines, the available cooling capacity for the active second fuel cell stack can be increased.
[0023] It is advantageous if a second valve, located between the second coolant outlet and the second vehicle radiator line, assumes a switching position that directs at least a portion of the coolant from the second coolant outlet into the bypass line, and a first valve, located between the first coolant outlet and the first vehicle radiator line, assumes a switching position that directs at least a portion of the coolant from the bypass line into the first vehicle radiator line. Through the targeted control of the first and second valves, efficient regulation of the coolant flow to the R. 416035 is achieved.
[0024] - 4 -
[0025] Minimizing the thermal stress on the second fuel cell stack that is active, thereby increasing the lifetime of the fuel cell system.
[0026] Advantageously, the cooling capacity of the first cooling circuit 200 of the first fuel cell stack 11 is coupled into the second fuel cell stack 12, whereby the first device for regulating the mass flows 24 in the first cooling circuit 200 is at least partially opened. This allows for a targeted adjustment of the coolant flow rate through the first vehicle radiator line.
[0027] The fuel cell system and the method according to the invention are explained in more detail below with reference to drawings with preferred embodiments.
[0028] They show:
[0029] Fig. 1 shows an embodiment of the fuel cell system according to the invention;
[0030] Fig. 2 shows an embodiment of the method according to the invention.
[0031] Figure 1 shows an embodiment of the fuel cell system 100 according to the invention, comprising a first fuel cell stack 11, a first cooling circuit 200, a second fuel cell stack 12 and a second cooling circuit 300.
[0032] The first cooling circuit 200 and the second cooling circuit 300 form a closed circuit.
[0033] The first cooling circuit 200 serves to temperature-control the first fuel cell stack 11 by means of a coolant flowing through an integrated coolant path of the first fuel cell stack 11. The first cooling circuit 200 includes a first coolant supply line 25, a first coolant outlet 26, a first vehicle radiator line 28, and a first section 27 of a bypass line 27, 37. R. 416035
[0034] - 5 -
[0035] The first coolant supply line 25 leads into the first fuel cell stack 11, the first fuel cell stack 11 being temperature-controlled with coolant via the first coolant supply line 25. A first conveying unit 21 is arranged within the first coolant supply line 25.
[0036] The first coolant outlet 26 is connected to the first fuel cell stack 11, with the coolant exiting the first fuel cell stack 11 via the first coolant outlet 26.
[0037] In the first vehicle radiator line 28, a first vehicle radiator 23 and a first device for regulating the mass flows 24, in particular a first throttle valve 24, are arranged. In the exemplary embodiment, the first vehicle radiator 23 is arranged upstream of the first device for regulating the mass flows 24 in the flow direction. In an alternative embodiment, the first vehicle radiator 23 can be arranged downstream of the first device for regulating the mass flows 24 in the flow direction.
[0038] A first valve 22, in particular a 3-way valve 22, is arranged between the first coolant outlet 26 and the first vehicle radiator line 28.
[0039] The second cooling circuit 300 serves to temperature-control the second fuel cell stack 12 by circulating a coolant through an integrated coolant path of the second fuel cell stack 12. The second cooling circuit 300 includes a second coolant supply line 35, a second coolant outlet 36, a second vehicle radiator line 38, and a second section 37 of the bypass line 27, 37.
[0040] The second coolant supply line 35 leads into the second fuel cell stack 12, which is temperature-controlled via the second coolant supply line 35. A second pumping unit 31 is arranged within the second coolant supply line 35.
[0041] In an alternative embodiment, a temperature sensor for determining the coolant temperature R can be installed in the second coolant supply line 35 between the second conveying unit 31 and the second fuel cell stack 12. 416035
[0042] - 6 - be arranged. The measured coolant temperature can be made available to the method according to the invention.
[0043] The second coolant outlet 36 is connected to the second fuel cell stack 12, whereby the coolant is discharged from the second fuel cell stack 12 via the second coolant outlet 36.
[0044] In the second vehicle radiator line 38, a second vehicle radiator 33 and a second mass flow control device 34, in particular a second throttle valve 34, are arranged. In the exemplary embodiment, the second vehicle radiator 33 is arranged upstream of the second mass flow control device 34 in the flow direction. In an alternative embodiment, the second vehicle radiator 33 can be arranged downstream of the second mass flow control device 34 in the flow direction.
[0045] A second valve 32, in particular a 3-way valve 22, is arranged between the second coolant outlet 36 and the second vehicle radiator line 38.
[0046] The first cooling circuit 200 of the first fuel cell stack 11 and the second cooling circuit 300 of the second fuel cell stack 12 are connected to each other via a manifold 39 through which fluid can flow.
[0047] The manifold 39 is connected to the first coolant supply line 25 and to the second coolant supply line 35. In the exemplary embodiment of the fuel cell system 100 according to the invention, the manifold 39 branches into the first coolant supply line 25 and the second coolant supply line 35.
[0048] The manifold 39 is connected to the bypass line 27, 37, whereby the bypass line 27, 37 can divert the coolant at least partially around the first vehicle radiator 23, which is located in the first vehicle radiator line 28 of the first cooling circuit 200, and / or the second vehicle radiator 33, which is located in the second vehicle radiator line 38 of the second cooling circuit 300. The manifold 39 divides the bypass line 27, 37 into a first section 27 and a second section 37. R. 416035
[0049] - 7 -
[0050] The coolant of the first vehicle radiator line 28 and the coolant of the second vehicle radiator line 38 are fed into the collector line 39 behind the bypass line 27, 37 in the direction of flow of the manifold 39.
[0051] In the illustrated embodiment, the first valve 22 is designed as a 3-way valve 22, so that the first section 27 of the bypass line 27, 37 is connected to the first 3-way valve 22.
[0052] In the illustrated embodiment, the second valve 32 is designed as a 3-way valve 32, so that the second section 37 of the bypass line 27, 37 is connected to the second 3-way valve 32.
[0053] The first fuel cell stack 11 and the second fuel cell stack 12 each have a cathode system (not shown) and an anode system (not shown).
[0054] The cathode system (not shown) supplies a cathode compartment of the first fuel cell stack 11 or a cathode compartment of the second fuel cell stack 12 with oxygen (O2) as a reactant. Oxygen is a component of air. By supplying air to the fuel cell system 100, oxygen is made available to it as a reactant.
[0055] The anode system, not shown in each case, supplies an anode compartment A of the first fuel cell stack 11 or an anode compartment of the second fuel cell stack 12 with a fuel or anode gas, in particular hydrogen (H2), as reactants.
[0056] A control unit 500 is provided to regulate and control all control processes in the fuel cell system 100. This also includes the processing of a measured value for the execution of the method according to the invention.
[0057] Figure 2 shows an embodiment of the method according to the invention.
[0058] Using the method according to the invention, it is possible to optimize the existing cooling capacity of the fuel cell system 100 within the R. 416035
[0059] - 8 -
[0060] To distribute 100 fuel cell systems. When the first fuel cell stack
[0061] Since the first fuel cell stack 11 is inactive, it does not require cooling by the first cooling circuit 200, so that the cooling capacity of the first cooling circuit 200 can be made available to the second fuel cell stack 12, which is active, by carrying out the method according to the invention.
[0062] The process is initiated in step S100. The process according to the invention is carried out during the operation of the fuel cell system 100.
[0063] Subsequently, in step S200, the first cooling circuit 200 of the first fuel cell stack 11 is connected, via fluid flow, to the second cooling circuit 300 of the second fuel cell stack 12, so that the cooling capacity of the first cooling circuit 200 of the first fuel cell stack 11 is essentially transferred to the second fuel cell stack
[0064] 12 is coupled in, with the first fuel cell stack 11 being inactive and the second fuel cell stack 12 being active.
[0065] The cooling capacity of the first cooling circuit 200 of the first fuel cell stack 11 is coupled into the second fuel cell stack 12 by the coolant of the first cooling circuit 200 essentially flowing through a coolant path of the second fuel cell stack 12.
[0066] The coolant temperature in the second coolant supply line 35 is regulated and controlled within upper and lower limits. The upper limit is the maximum temperature the coolant in the second coolant supply line 35 may reach to provide adequate cooling to the second fuel cell stack 12. The lower limit is the minimum temperature the coolant in the second coolant supply line 35 may reach to provide adequate cooling to the second fuel cell stack 12.
[0067] The cooling capacity of the first cooling circuit 200 is coupled into the second fuel cell stack 12, with the first pump unit 21, located in the first cooling circuit 200, being inactive and the second pump unit 31, located in the second cooling circuit 300, being active. When the first pump unit 21 is inactive and the second pump unit 31 is active, essentially no coolant flows through the first fuel cell stack 11, which is inactive, so the cooling capacity of the first R. 416035
[0068] - 9 -
[0069] Cooling circuit 200 is additionally available for cooling the second fuel cell stack 12.
[0070] The cooling capacity of the first cooling circuit 200 of the first fuel cell stack 11 is coupled into the second fuel cell stack 12, whereby the coolant from the second coolant outlet 36 of the second fuel cell stack 12 flows at least partially into the first vehicle cooler line 28, in which a first vehicle cooler 23 is arranged, via the bypass line 27, 37.
[0071] The second valve 32, located between the second coolant outlet 36 and the second vehicle radiator line 38, assumes a switching position that directs at least a portion of the coolant from the second coolant outlet 36 into the bypass line 27, 37, and the first valve 22, located between the first coolant outlet 26 and the first vehicle radiator line 28, assumes a switching position that directs at least a portion of the coolant from the bypass line 27, 37 into the first vehicle radiator line 28. This directs the coolant from the second fuel cell stack 12 into the first cooling circuit 200.
[0072] Depending on the coolant temperature in the second coolant supply line 35, the second valve 32 can vary the proportion of coolant directed into the bypass line. The highest cooling capacity is supplied to the second fuel cell stack 12 when a substantially equal mass flow of coolant flows through the first vehicle radiator line 28 and through the second vehicle radiator line 28 and is supplied to the second fuel cell stack 12.
[0073] The cooling capacity of the first cooling circuit 200 of the first fuel cell stack 11 is coupled into the second fuel cell stack 12, whereby the first device for controlling the mass flows 24 in the first cooling circuit 200 is at least partially opened.
[0074] When the first mass flow control device 24 is fully open, there is no reduction in the coolant mass flow through the first vehicle radiator line 28. When the first mass flow control device 24 is partially open, a reduced coolant mass flow passes through the first vehicle radiator line 28. The first mass flow control device 24 can be used to adjust the coolant mass flow in the first vehicle radiator line 28 and thereby control the coolant temperature in R. 416035
[0075] - 10 - to regulate or control the second coolant supply line 35 within an upper limit and a lower limit.
[0076] In step S300, the inventive method is then terminated. The inventive method is terminated when the first fuel cell stack
[0077] 11 is switched on and / or the first fuel cell stack 11 has no cooling capacity of the first cooling circuit 200 for temperature control of the second fuel cell stack
[0078] The method according to the invention is terminated when the second fuel cell stack 12 no longer requires additional cooling by the first cooling circuit 200. The second fuel cell stack 12 does not require additional cooling by the first cooling circuit 200 when the lower limit is undershot.
[0079] The process can be carried out, at least in part, by the control unit 500 of the fuel cell system 100. A computer program in the form of code can be stored in a memory unit of the control unit 500. When executed by a processing unit of the control unit 500, this code performs a process that can proceed as described above. The same advantages described above in connection with the process according to the invention can be achieved using the control unit 500. These advantages are fully referenced herein.
[0080] The control unit 500 can be in communication with the sensors of the fuel cell system 100 in order to monitor the sensor values.
[0081] The control unit 500 can control the actuators in the fuel cell system 100 in order to carry out the procedure accordingly.
[0082] Furthermore, the control unit 500 can be in a communication link with an external computing unit in order to outsource some process steps and / or calculations completely or partially to the external computing unit.
[0083] According to another aspect, the invention provides a computer program product comprising instructions that are executed by a computer, such as the arithmetic unit of the control unit 500, R. 416035, when the computer program product is executed.
[0084] - 11 -
[0085] The computer is instructed to carry out the process, which can proceed as described above. The same advantages described above in connection with the inventive method and / or the inventive control unit 500 can be achieved using the computer program product. These advantages are fully referenced herein.
Claims
R. 416035 - 12 - Claims 1. Fuel cell system (100) with at least two fuel cell stacks (11, 12), wherein each fuel cell stack (11, 12) is assigned a cooling circuit (200, 300) and a coolant flows through the respective cooling circuit (200, 300), wherein a coolant supply line (25, 35) and a coolant outlet line (26, 36) are arranged in each cooling circuit (200, 300), characterized in that a first cooling circuit (200) of a first fuel cell stack (11) and a second cooling circuit (300) of a second fuel cell stack (12) are connected to each other via a manifold (39) and the manifold (39) is connected to a bypass line (27, 37), wherein the bypass line (27, 37) diverts the coolant at least partially around a first vehicle radiator (23), which is located in a first vehicle radiator line (28) of the first cooling circuit (200) is arranged, and / or a second vehicle radiator (33),which is arranged in a second vehicle radiator line (38) of the second cooling circuit (300), and the collecting line (39) divides the bypass line (27, 37) into a first section (27) and a second section (37).
2. Fuel cell system (100) according to claim 1 , characterized in that the coolant of the first vehicle radiator line (28) and the second vehicle radiator line (38) is supplied in the direction of flow of the manifold (39) behind the bypass line (27, 37) into the manifold (39).
3. Fuel cell system (100) according to claim 1 , characterized in that a first device for controlling the mass flows (24) is arranged in the first vehicle cooler line (28) and a second device for controlling the mass flows (34) is arranged in the second vehicle cooler line (38).
4. Fuel cell system (100) according to claim 1, characterized in that a first valve (22), in particular a 3-way valve (22), is arranged between the first coolant outlet (26) and the first vehicle radiator line (28) and between the second coolant outlet (36) and the second R. 416035 - 13 - A second valve (32), in particular a 3-way valve (32), is arranged in the vehicle radiator line (38).
5. Method for operating a fuel cell system (100) with at least two fuel cell stacks (11, 12), wherein each fuel cell stack (11, 12) is assigned a cooling circuit (200, 300) through which a coolant flows and in the cooling circuit (200, 300) a coolant supply line (25, 35) and a coolant outlet (26, 36) are arranged, characterized in that a first cooling circuit (200) of a first fuel cell stack (11) is connected, fluid-permeable, to a second cooling circuit (300) of a second fuel cell stack (12), such that the cooling power of the first cooling circuit (200) of the first fuel cell stack (11) is substantially coupled into the second fuel cell stack (12), wherein the first fuel cell stack (11) is inactive and the second fuel cell stack (12) is active.
6. Method according to claim 5, characterized in that the cooling capacity of the first cooling circuit (200) of the first fuel cell stack (11) is coupled into the second fuel cell stack (12) by the coolant of the first cooling circuit (200) flowing substantially through a coolant path of the second fuel cell stack (12).
7. Method according to claim 5, characterized in that the cooling capacity of the first cooling circuit (200) is coupled into the second fuel cell stack (12), wherein a first conveying unit (21) arranged in the first cooling circuit (200) is inactive and a second conveying unit (31) arranged in the second cooling circuit (300) is active.
8. Method according to claim 5, characterized in that the cooling capacity of the first cooling circuit (200) of the first fuel cell stack (11) is coupled into the second fuel cell stack (12), wherein the coolant from the second coolant outlet (36) of the second fuel cell stack (12) flows at least partially into the first vehicle cooler line (28) in which a first vehicle cooler (23) is arranged via the bypass line (27, 37).
9. Method according to claim 8, characterized in that a second valve (32) is located between the second coolant outlet (36) and the second R. 416035 - 14 - vehicle radiator line (38) is arranged, assumes a switching position which directs at least a proportion of coolant from the second coolant outlet (36) into the bypass line (27, 37), and a first valve (22) which is arranged between the first coolant outlet (26) and the first vehicle radiator line (28) assumes a switching position which directs at least a proportion of the coolant from the Bypass line (27, 37) directs into the first vehicle radiator line (28).
10. Method according to claim 5, characterized in that the cooling capacity of the first cooling circuit (200) of the first fuel cell stack (11) is coupled into the second fuel cell stack (12), wherein the first device for controlling the mass flows (24) in the first cooling circuit (200) is at least partially opened.