Systems, apparatus, and methods for robust cold start of fuel cell systems

Abstract

The invention relates to an anode system for supplying fuel to an anode of a fuel cell system of a plant. The invention relates to an anode system for a fuel cell system, comprising a grid structure which is coupled to an inlet region of an anode of the fuel cell system and is configured and / or configurable for delaying a temperature rise of the grid structure during operation of the device, until the inlet region of the anode of the fuel cell system of the apparatus exceeds the freezing point of water in the inlet region of the anode.

Description

Technical Field

[0001] The invention relates to a system, a device and a method for robust cold starting of a fuel cell system, in particular to a device having a polymer electrolyte membrane fuel cell (PEM fuel cell) and an anode system having a droplet catcher. Background Art

[0002] Vehicles with hydrogen-based fuel cell systems are considered a future concept, since they emit only water as exhaust gas and, unlike conventional electric vehicles, for example, allow short refueling times.

[0003] Hydrogen-based fuel cell systems, such as PEM fuel cells, also known as proton exchange membrane fuel cells, provide high power density and, compared to other fuel cells, offer the advantages of light weight and small size. PEM fuel cells can use solid polymers as electrolytes and use porous carbon electrodes containing catalysts composed of platinum or platinum alloys. For the operation of the PEM fuel cell, the PEM fuel cell requires only hydrogen, oxygen from the air, and water. The PEM fuel cell is usually fed with hydrogen from a storage tank or a reformer. PEM fuel cells often operate at a temperature of about 80°C (176°F).

[0004] The operation and especially the commissioning of the device in a fuel cell system at a temperature of 0° C. or below 0° C. is a challenge. If the operating temperature of the PEM fuel cell is below the freezing point, the water supplied or produced therein turns into ice. Depending on the location of the ice formation, the gas supply in the fuel cell system is reduced or completely prevented. This type of fuel depletion is particularly dangerous at the anode of the PEM fuel cell, because it can lead to carbon corrosion in the support structure of the catalyst layer of the PEM fuel cell and thus shorten the service life of the PEM fuel cell.

[0005] In order to avoid ice formation during a cold start, in conventional systems, the anode system is dried before the cold start. The goal of this drying is to have as little water as possible in the anode system. To this end, in conventional anode systems, a purge valve is opened and the anode system is purged with fresh hydrogen.

[0006] However, it cannot always be ensured that the water in the anode system is drained away without residue. Small amounts of water may still be present in the anode system after drying and subsequently freeze during the cooling process. In conventional systems with fuel cell systems, individual components of the anode system may be heated during a cold start in order to reduce mechanical blockages of these components, such as purge valves or recirculation blowers (anode recirculation blower, ARB), due to ice.

[0007] During a cold start, parts and / or components of the anode system can also heat up faster than the inlet region of the anode of the fuel cell system. In this case, existing ice can be liquefied, so that liquid and therefore mobile water is produced in the anode system. If, for example, anode recirculation is started at the beginning of a cold start, this liquid water is conveyed via the gas flow into the fuel cell system, which has a temperature of 0° C. or below 0° C., and the supplied water can immediately freeze there.

[0008] If water droplets enter the inlet region of the anode of the fuel cell system, ice formation may immediately occur there, with partial or complete obstruction of the gas path to the anode of the fuel cell system. As a result, dangerous fuel depletion may occur, which may damage one or more fuel cells, so that it may even be necessary to replace the fuel cell. Another possible consequence may be that the cold start is interrupted, i.e. the system with the fuel cell system cannot be transferred to an operationally ready state. A single or a small number of fine droplets are already sufficient to block the usually very fine paths for distributing the fuel.

[0009] In conventional devices with fuel cell systems, recirculation can be minimized during cold start by switching off the recirculation blower, thereby reducing the probability of harmful droplet input. However, switching off the recirculation blower can lead to uneven supply to the fuel cell, which includes, for example, insufficient supply on the cell surface in one or more fuel cells. In addition, uneven supply to the cell surface can lead to uneven current generation and thus to uneven current density and uneven heat generation in the fuel cell. Summary of the invention

[0010] The present invention provides a system, apparatus and method for robustly cold starting a fuel cell system.

[0011] The present invention makes it possible to provide a system, device and method that prevents liquid water droplets from the anode system from entering the cold inlet region of the anode of the fuel cell, which is still below 0° C., and freezing there in the anode distributor structure of the fuel cell. Thus, severe aging of the fuel cell or the necessary interruption of a cold start can be prevented.

[0012] By avoiding hydrogen depletion, an increased service life of the fuel cell can be achieved. Since heated components that are thermally insulated or thermally insulable from the grid structure are permitted in the anode circuit, an improved robustness of the fuel cell can be achieved. At the same time, the proposed improvement can be realized cost-effectively and in a small installation space.

[0013] According to a first aspect, the present invention relates to an anode system for supplying fuel to an anode of a fuel cell system of a device, the anode system comprising: a grid structure, which is coupled to an inlet area of ​​the anode of the fuel cell system and is configured and / or can be configured to delay the heating of the grid structure during commissioning of the device until the inlet area of ​​the anode of the fuel cell system of the device exceeds the freezing point of water in the inlet area of ​​the anode.

[0014] According to one embodiment, the grid structure has one or more components, and the specific heat capacity of the one or more components is greater than the specific heat capacity of water.

[0015] According to one configuration, the grid structure is at least partially thermally decoupled and / or can be thermally decoupled from the anode system in order to thermally insulate the grid structure in the anode system.

[0016] According to one embodiment, the grid structure is at least partially thermally coupled to a cooling system for cooling the grid structure in the anode system.

[0017] According to one embodiment, the grid structure comprises a plurality of grid structures which are configured and / or can be configured to deflect fuel in the grid structure.

[0018] According to one embodiment, the anode system comprises a bypass valve for bypassing the fuel directly into the inlet region of the anode of the fuel cell system when the inlet region of the anode exceeds the freezing point of water in the inlet region of the anode.

[0019] According to a second aspect, the invention relates to a device having a fuel cell system with an anode and having an anode system as described above.

[0020] According to one embodiment, the device further comprises a cooling system which is at least partially thermally coupled to the grid structure for cooling the grid structure in the anode system.

[0021] According to a third aspect, the invention relates to a method comprising: with the aid of the above-mentioned anode system, delaying the heating of the grid structure during the operation of the above-mentioned device until the inlet area of ​​the anode of the fuel cell system of the device exceeds the freezing point of water in the inlet area of ​​the anode.

[0022] According to an extended scheme, the method includes at least one or more of the following steps: thermally isolating the grid structure from the anode system; cooling the grid structure; offsetting multiple grid structures to divert the fuel in the grid structure; and bypassing the fuel directly into the inlet area of ​​the anode of the fuel cell system when the inlet area of ​​the anode exceeds the freezing point of water in the inlet area of ​​the anode. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings show:

[0024] Figure 1 A schematic diagram showing an exemplary device according to one embodiment of the present invention, the device having a fuel cell system and an anode system; and

[0025] Figure 2 A schematic diagram showing an exemplary anode system according to one embodiment of the present invention, the anode system being coupled to an anode of a fuel cell system; and

[0026] Figure 3 A schematic diagram is shown of an exemplary method according to one embodiment of the present invention.

[0027] In all figures, identical or functionally identical elements and devices are provided with the same reference numerals. The numbering of the method steps is for the sake of clarity and should generally not imply a specific chronological sequence. In particular, a plurality of method steps may also be performed simultaneously. DETAILED DESCRIPTION

[0028] Figure 1 A schematic diagram of an exemplary device 1000 according to one embodiment of the present invention is shown, which has a fuel cell system 1100 and an anode system 1200. In addition, the exemplary device 1000 may include a cooling system 1300, a cathode system 1400, and an electrical system 1500.

[0029] The fuel cell system 1100 is configured to generate an electric current. The electric current may be used at least in part to operate the device 1000. The fuel cell system 1100 may include one or more low temperature fuel cells, such as PEM fuel cells.

[0030] The fuel cell system 1100 includes an anode 1110. The anode 1110 is coupled to an anode system 1200. In addition, the fuel cell system 1100 includes a cooling device 1120 and a cathode 1130. The cooling device 1120 is coupled to a cooling system 1300. The cathode 1130 is coupled to a cathode system 1400. The anode 1110 and the cathode 1130 are coupled to an electrical system 1500.

[0031] The anode system 1200 is configured to supply fuel, such as hydrogen, H 2 , to the anode 1110 of the fuel cell system 1100 .

[0032] The anode system 1200 may include a fuel tank 1205 and at least one shut-off valve 1210. Optionally, a heat exchanger 1215 may be coupled between the shut-off valve 1210 and the purge and / or drain valve 1220. The anode system 1200 includes a jet pump 1225 and a recirculation blower 1235. The jet pump 1225 and the recirculation blower 1235 are configured for recirculation of the fuel. The recirculation blower 1235 may be coupled between the jet pump 1225 and the purge and / or drain valve 1240. The grid structure 1230 is coupled between the jet pump 1225 and the anode 1110 of the anode system 1200.

[0033] The grid structure 1230 is configured to bind liquid water or gaseous water, such as formed in the anode system 1200 .

[0034] The grid structure 1230 can be thermally connected to the anode system 1200 in such a way that its temperature (e.g., -15°C) is kept lower than the temperature (e.g., 0°C) at the inlet region of the anode 1110 of the fuel cell system 1100 during cold start, during heating of other components in the anode system 1200 (e.g., purge valve and / or recirculation blower), so that liquid water carried from the fuel to the anode in the anode system 1200 freezes on the grid structure. While the temperature at the inlet region of the anode 1110 is 0°C or below 0°C, the temperature difference between the temperature at the inlet region of the anode 1110 and the temperature of the grid structure 1230 is preferably in the range of between 5 and 50°C, more preferably in the range of between 10 and 30°C.

[0035] If the temperature at the inlet region of the anode 1110 is already above the freezing point, the supply of liquid water which would otherwise occur when slowly warming up the grid structure is less problematic, since ice formation no longer occurs frequently in the fuel cell system 1100 .

[0036] Different implementations can be considered for the grid structure 1230, which allow as large and / or cool a surface as possible to contact the fuel before the fuel flows into the anode 1110. For example, the grid structure 1230 may include one or more of a metal structure, a sintered metal structure, a rib structure, a needle structure, a porous medium, or any combination of one or more of them.

[0037] The specific heat capacity of one or more components of the grid structure 1230 may be greater than the specific heat capacity of water. The grid structure 1230 may have a grid with openings whose diameters are in the range between 0.01 mm and 3 mm, preferably in the range between 0.5 mm and 1.5 mm. The openings in the grid structure 1230 may have the same or different diameters within this range.

[0038] The grid structure 1230 may be thermally insulated toward the heated elements of the anode system 1200 to delay warming of the grid structure 1230 during a cold start until the inlet region of the anode 1110 exceeds the freezing point of water in the inlet of the anode 1110 .

[0039] In addition, the anode system 1200 may include a purge and / or drain valve 1240, an optional condensate separator 1245, and an optional water container 1250, which may be coupled directly or indirectly to the anode 1110 and the recirculation blower 1235 via respective inputs. The output of the water container 1250 may be coupled to the input of the purge and / or drain valve 1225 of the anode system 1200.

[0040] The cooling system 1300 is configured for temperature control of the fuel cell system 1100. The cooling system 1300 comprises a coolant circuit in which the coolant is recirculated by means of a coolant pump 1305. The three-way valve 1310 can guide the coolant at least partially or completely past the vehicle cooler 1315 via a bypass line. The three-way valve 1310 can be closed relative to the vehicle cooler 1315 so that the coolant KM flows past the vehicle cooler 1315 via the bypass line.

[0041] The cathode system 1400 is configured to supply an oxidant, such as air, in particular oxygen, to the cathode 1130 of the fuel cell system 1100. An intake air 1405 can be supplied to the fuel cell system 1100 via an intake line having an optional air filter 1410 of a gas delivery device 1415. The air filter 1410 can be configured to filter chemicals and / or particles from the intake air 1405 to prevent them from entering the fuel cell system 1100, in particular the cathode 1130. The gas delivery device 1415, such as a compressor, can be configured to draw the intake air 1405 or air from the environment and provide it to the fuel cell system 1100.

[0042] After passing through the fuel cell system 1100, the exhaust gas 1445 can be exhausted from the fuel cell system 1100 to the environment via an exhaust line. Figure 1 As shown, at least one heat exchanger for cooling the intake air 1405 and a humidifier (not shown) may be provided downstream of the gas delivery device 1415. Shutoff valves 1425, 1430 may be provided before and / or after the fuel cell system 1100. In addition, a valve (not shown) may be provided in the exhaust line as a pressure regulator.

[0043] Along the air intake line, before the inlet into the fuel cell system 1100 and / or after the outlet from the fuel cell system 1100 , a temperature sensor (not shown) may be provided.

[0044] The intake and exhaust lines may be coupled to each other via a bypass line having an optional bypass valve 1435. The bypass line may be configured for controlling mass flow in the cathode system 1400 and / or for diluting exhaust gas from the fuel cell system 1100, which may contain hydrogen.

[0045] The electrical system 1500 is configured to remove electrical energy generated by the fuel cell system 1100 from the fuel cell system 1100 (eg via an onboard electrical system of a vehicle) and to supply it to the device 1000 .

[0046] The electrical system 1500 includes a rectifier 1505 that is directly or indirectly coupled to the anode 1110 and cathode 1130 of the fuel cell system 1100 to operate the motor 1515 via an optional inverter 1510. Alternatively or additionally, the rectifier 1505 can be coupled to a drive battery 1525 and / or to a low voltage battery 1535 via an inverter 1530. The inverter 1510 can achieve energy regeneration when using the motor 1515.

[0047] Alternatively or additionally, the drive battery 1525 and the low-voltage battery 1535 may be coupled to a charging device 1520 configured for attaching the device to an external source of electrical energy in order to charge the drive battery 1525 and / or the low-voltage battery 1535 .

[0048] Figure 2 A schematic diagram of an exemplary anode system 2200 is shown, which is coupled to anode 2110 of fuel cell system 2100 , according to one embodiment of the present invention.

[0049] The anode system 2200 is configured to supply fuel, such as hydrogen, H 2 , to the anode 2110 of the fuel cell system 2100 .

[0050] The anode system 2200 may include a fuel tank 2205 and at least one shut-off valve 2210. Optionally, a heat exchanger 2215 may be coupled between the shut-off valve 2210 and the purge and / or drain valve 2220. The anode system 2200 includes a jet pump 2225 and a recirculation blower 2235. The jet pump 2225 and the recirculation blower 2235 are configured for recirculation of the fuel. The recirculation blower 2235 may be coupled between the jet pump 2225 and the purge and / or drain valve 2240. The grid structure 2230 is coupled between the jet pump 2225 and the anode 2110 of the anode system 2200.

[0051] When the temperature at the inlet area of ​​the anode 2110 is lower than the freezing point of water in the inlet area of ​​the anode 2110, the grid structure 2230 can be connected to the anode 2110 of the anode system 2200 via a bypass valve 2229, such as a three-way valve, so as to combine liquid water and / or gaseous water formed in the anode system 1200.

[0052] The flow through the grid structure 2230 can be controlled by means of a three-way valve so that flow is only passed through the grid structure 2230 when the temperature at the inlet region of the anode 2110 is below the freezing point of water in the inlet region of the anode 2110. This can avoid pressure losses in normal operation, which, for example, reduces the energy consumption of the recirculation blower 2235 of the anode system 2200 compared to the energy consumption of the recirculation blower 1235 of the anode system 2200.

[0053] The grid structure 2230 can be thermally connected to the anode system 2200 in such a way that its temperature (e.g., -15°C) is kept lower than the temperature (e.g., 0°C) at the inlet region of the anode 2110 of the fuel cell system 2100 during the cold start-up during the heating of other components in the anode system 2200 (e.g., purge valve and / or recirculation blower), so that liquid water in the anode system 2200 that is carried from the fuel to the anode freezes on the grid structure 2230. While the temperature at the inlet region of the anode 2110 is 0°C or below 0°C, the temperature difference between the temperature at the inlet region of the anode 2110 and the temperature of the grid structure 2230 is preferably in the range of between 5 and 50°C, more preferably in the range of between 10 and 30°C.

[0054] If the temperature at the inlet region of the anode 2110 is already above the freezing point, the supply of liquid water that would otherwise occur when the grid structure is slowly warmed up is less of a problem, since ice formation can no longer occur in the fuel cell system 2100 .

[0055] Different implementations can be considered for the grid structure 2230, which allow as large and / or cool a surface as possible to contact the fuel before the fuel flows into the anode 2110. For example, the grid structure 2230 may include one or more of a metal structure, a sintered metal structure, a rib structure, a needle structure, a porous medium, or any combination of one or more of them.

[0056] The specific heat capacity of one or more components of the grid structure 2230 may be greater than the specific heat capacity of water. The grid structure 2230 may have a grid with openings having a diameter in the range between 0.01 mm and 3 mm, preferably in the range between 0.5 mm and 1.5 mm. The openings in the grid structure 2230 may have the same or different diameters within this range.

[0057] The grid structure 2230 may be thermally insulated toward the heated elements of the anode system 2200 so as to delay warming of the grid structure 2230 during a cold start until the inlet region of the anode 2110 is above freezing.

[0058] The grid structures 1230 and 2230 in the anode systems 1200 and 2200 may also have one or more cooled grid structures. For example, the grid structures 1230 and 2230 may be coupled with the cooling system 1300 or a separate cooling system (not shown) to slow down the warming of the grid structures 1230 and 2230 compared to the inlet area of ​​the anodes 1210 and 2110. This combination is possible, for example, to optimize the control of the temperature of the grid structures 1230 and 2230.

[0059] In addition, grid structures 1230 and / or 2230 may have one or more grid structures that are arranged in pairs with an offset so as to divert the fuel. Liquid water carried from the fuel into grid structures 1230 and / or 2230 may poorly follow the change in direction corresponding to the offset due to its inertia and thus appear with increased probability on the surface of the second grid structure behind the first grid structure, where the liquid water freezes.

[0060] In addition, the anode system 2200 may include a purge and / or drain valve 2240, an optional condensate separator 2245, and an optional water container 2250, which may be coupled directly or indirectly to the anode 2110 and the recirculation blower 2235 via respective inputs. The output of the water container 2250 may be coupled to the input of the purge and / or drain valve 2225 of the anode system 2200.

[0061] Figure 3 A schematic diagram of an exemplary method 3000 according to one embodiment of the present invention is shown. The method 3000 comprises: by means of the anode system according to the present invention, during the operation of the device according to the present invention, the heating of the grid structure is delayed until the inlet region of the anode of the fuel cell system of the device exceeds the freezing point of water in the inlet region of the anode 1110.

[0062] Delaying the temperature rise may include thermally isolating 3100 the grid structure from the anode system.

[0063] Alternatively or additionally, the delay of the temperature increase may include cooling 3200 the grid structure.

[0064] Alternatively or additionally, the delay of the temperature increase may include offsetting 3300 a plurality of grid structures in pairs in order to divert the fuel within the grid structures.

[0065] Furthermore, the method includes bypassing 3400 the fuel directly into the inlet region of the anode when the inlet region of the anode of the fuel cell system of the device exceeds the freezing point of water in the inlet region of the anode 1110 .

Claims

1. An anode system (1200; 2200) for supplying fuel to an anode (1110; 2110) of a fuel cell system (1100; 2100) of an apparatus (1000), the anode system comprising: A grid structure (1230; 2230) is coupled to an inlet region of an anode (1110; 2110) of the fuel cell system (1100; 2100) and is configured and / or configurable to delay heating of the grid structure (1230; 2230) during operation of the device (1000) until the inlet region of the anode (1110; 2110) of the fuel cell system (1100; 2100) of the device (1000) exceeds the freezing point of water in the inlet region of the anode (1110; 2110).

2. The anode system (1200; 2200) according to claim 1, wherein: The grid structure (1230; 2230) has one or more components, and the specific heat capacity of the one or more components is greater than the specific heat capacity of water.

3. The anode system (1200; 2200) according to claim 1 or 2, wherein: The grid structure (1230; 2230) is at least partially thermally decoupled from the anode system (1200; 2200) and / or is capable of thermally decoupling, for thermally isolating the grid structure (1230; 2230) in the anode system (1200; 2200).

4. The anode system (1200; 2200) according to any one of claims 1 to 3, wherein: The grid structure (1230; 2230) is at least partially thermally coupled to a cooling system for cooling the grid structure (1230; 2230) in the anode system.

5. The anode system (1200; 2200) according to any one of claims 1 to 4, wherein: The grid structure (1230; 2230) comprises a plurality of grid structures, which are configured and / or configurable for diverting the fuel within the grid structure (1230; 2230).

6. The anode system (2200) according to any one of claims 1 to 5, wherein: The anode system (2200) includes a bypass valve (2229), which is used to: when the inlet area of ​​the anode (2110) exceeds the freezing point of water in the inlet area of ​​the anode (1110), allow the fuel to bypass directly to the inlet area of ​​the anode (2110) of the fuel cell system (2100).

7. A device (1000), comprising: A fuel cell system (1100; 2100) comprising an anode (1110; 2110); and An anode system (1200; 2200) according to any one of claims 1 to 6.

8. The device (1000) according to claim 7, wherein The device (1000) furthermore has a cooling system (1300), which is at least partially thermally coupled to the grid structure (1230; 2230) and is used to cool the grid structure (1230; 2230) in the anode system (1200; 2200).

9. A method (3000), comprising: With the aid of the anode system according to any one of claims 1 to 6, the heating of the grid structure (1230; 2230) is delayed during the operation of the device (1000) according to any one of claims 7 to 8 until the inlet area of ​​the anode (1110; 2110) of the fuel cell system (1100; 2100) of the device (1000) exceeds the freezing point of water in the inlet area of ​​the anode (1110).

10. The method according to claim 9, wherein: The method comprises at least one or more of the following steps: thermally isolating (3100) the grid structure (1230; 2230) from the anode system (1200; 2200); Cooling 3200 the grid structure (1230; 2230); staggering (3300) a plurality of grid structures (1230; 2230) for diverting the fuel within the grid structures (1230; 2230); When the inlet area of ​​the anode (2110) exceeds the freezing point of water in the inlet area of ​​the anode (1110), the fuel is bypassed directly into the inlet area of ​​the anode (2110) of the fuel cell system (2100).

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