# US 8,541,143 B2 · Fuel cell system and process for operating same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,541,143 B2 - Document ID: US8541143B2 - Status: Granted - Kind: B2 - Application number: 12/707,064 - Filed: 2010-02-17 - Published: 2010-08-19 - Granted: 2013-09-24 - Earliest claimed: 2009-02-19 - Assignees: Eberspächer Climate Control Systems GmbH & Co. KG - Applicants: Samuel Brandt; Richard Schmidt - Inventors: Samuel Brandt; Richard Schmidt - Web page: https://patentgrep.com/patent/US8541143B2 ## CPC - H01M 8/0618: {Reforming processes, e.g. autothermal, partial oxidation or steam reforming} - B60L 58/32: for controlling the temperature of fuel cells, e.g. by controlling the electric load - H01M 8/04074: {Heat exchange unit structures specially adapted for fuel cell} - H01M 8/04253: {Means for solving freezing problems} - H01M 8/04373: {of auxiliary devices, e.g. reformers, compressors, burners} - H01M 8/04738: {of auxiliary devices, e.g. reformer, compressor, burner} - H01M 2250/20: Fuel cells in motive systems, e.g. vehicle, ship, plane - Y02E 60/50: Fuel cells - Y02T 90/40: Application of hydrogen technology to transportation, e.g. using fuel cells - H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY - B60L: PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES (arrangements or mounting of electrical propulsion units or of plural diverse prime-movers for mutual or common propulsion in vehicles B60K1/00, B60K6/20; arrangements or mounting of electrical gearing in vehicles B60K17/12, B60K17/14; preventing wheel slip by reducing power in rail vehicles B61C15/08; dynamo-electric machines H02K; control or regulation of electric motors H02P); SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES (electric coupling devices combined with mechanical couplings of vehicles B60D1/64; electric heating for vehicles B60H1/00); ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL (control or regulation of electric motors H02P); MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES - Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION ## Abstract A process for operating a fuel cell system (1), especially in a motor vehicle. The fuel cell system (1) includes at least one fuel cell (3) as well as at least one reformer (2). To improve the possibility of warm start, a warm-holding mode, in which heat transfer takes place from the fuel cell (3) to the reformer (2), is activated after switching off the fuel cell system (1). ## Claims ### Claim 1 A process for operating a fuel cell system, the process comprising the steps of: providing that the fuel cell system comprises at least one fuel cell as well as at least one reformer; providing a control; operating the fuel cell; and establishing a warm-holding mode with said control, in which heat transfer takes place from the fuel cell to the reformer and activating the warm-holding mode with said control after the fuel cell system has been switched off. ### Claim 2 (depends on 1) A process in accordance with claim 1, wherein the heat transfer to the reformer is carried out such that the temperature of the reformer does not drop below a minimum warm-holding temperature of the reformer. ### Claim 3 (depends on 1) A process in accordance with claim 1, wherein the heat transfer is carried out until the temperature of the fuel cell has dropped below a minimum warm-holding temperature of the fuel cell. ### Claim 4 (depends on 1) A process in accordance with claim 1, wherein the heat transfer takes place via an educt circuit, in which an educt circulates between the fuel cell and the reformer. ### Claim 5 (depends on 4) A process in accordance with claim 4, wherein the educt circuit comprises an anode gas path passing through the fuel cell, a recirculation path returning anode waste gas from the fuel cell to the reformer, and a reformate gas path sending reformate gas from the reformer to the fuel cell. ### Claim 6 (depends on 5) A process in accordance with claim 5, wherein a delivery means is arranged in the recirculation path and the delivery means is used to drive the educt in the educt circuit. ### Claim 7 (depends on 4) A process in accordance with claim 4, wherein the educt circuit comprises a cathode gas path passing through the fuel cell, a cooling gas path sending cooling gas to a residual gas burner arranged downstream of the fuel cell, and a coupling path coupled with the reformer in a heat-transferring manner. ### Claim 8 (depends on 7) A process in accordance with claim 7, wherein the coupling path is activated and deactivated by means of a valve arrangement. ### Claim 9 (depends on 7) A process in accordance with claim 7, wherein the coupling path is connected to the cooling gas path via a valve arrangement. ### Claim 10 (depends on 7) A process in accordance with claim 7, wherein the educt circuit further comprises: a section of an air path sending air to the fuel cell; and a coupling path connected to the air path via a valve arrangement. ### Claim 11 (depends on 7) A process in accordance with claim 7, wherein a delivery means is arranged in the coupling path or in the cooling gas path or in the air path to drive the educt in the educt circuit. ### Claim 12 (depends on 1) A process in accordance with claim 1, wherein at least one of: a burner waste gas path, which removes burner waste gas from a residual gas burner arranged downstream of the fuel cell is closed during the warm-holding mode; and a fuel cell air path, which sends air to the fuel cell, is closed during the warm-holding mode; and a reformer air path, which sends air to the reformer, is closed during the warm-holding mode. ### Claim 13 A fuel cell system, comprising: a fuel cell; a reformer; a control for operating the fuel cell system including operating the fuel cell and the reformer, said control being equipped or programmed for establishing a warm-holding mode and establishing the warm-holding mode in which said control controls heat transfer from said fuel cell to said reformer and heat transfer takes place from said fuel cell to said reformer and said control activating the warm-holding mode after said fuel cell has been switched off. ### Claim 14 (depends on 13) A fuel cell system in accordance with claim 13, wherein said control controls heat transfer to said reformer to at least one of: prevent the temperature of said reformer from dropping below a minimum warm-holding temperature of said reformer; and until the temperature of said fuel cell has dropped below a minimum warm-holding temperature of said fuel cell. ### Claim 15 (depends on 13) A fuel cell system in accordance with claim 13, further comprising an educt circuit wherein the heat transfer takes place via said educt circuit, in which an educt circulates between said fuel cell and said reformer. ### Claim 16 (depends on 15) A fuel cell system in accordance with claim 15, further comprising a delivery means to feed the educt in the educt circuit, wherein said educt circuit comprises an anode gas path passing through said fuel cell, a recirculation path returning anode waste gas from said fuel cell to said reformer, and a reformate gas path sending reformate gas from said reformer to said fuel cell, said delivery means being arranged in said recirculation path. ### Claim 17 (depends on 15) A fuel cell system in accordance with claim 15, wherein said educt circuit comprises a cathode gas path passing through said fuel cell, a cooling gas path sending cooling gas to a residual gas burner arranged downstream of said fuel cell, and a coupling path coupled with said reformer in a heat-transferring manner, wherein said coupling path is activated and deactivated by means of a valve arrangement and said coupling path is connected to the cooling gas path via said valve arrangement. ### Claim 18 (depends on 17) A fuel cell system in accordance with claim 17, wherein the educt circuit further comprises: a section of an air path sending air to said fuel cell; and a coupling path connected to the air path via a valve arrangement. ### Claim 19 (depends on 17) A fuel cell system in accordance with claim 17, wherein a delivery means is arranged in the coupling path or in the cooling gas path or in the air path to drive the educt in the educt circuit. ### Claim 20 (depends on 13) A fuel cell system in accordance with claim 13, wherein at least one of: a burner waste gas path, which removes burner waste gas from a residual gas burner arranged downstream of said fuel cell is closed by said control during the warm-holding mode; and a fuel cell air path, which sends air to said fuel cell, is closed by said control during the warm-holding mode; and a reformer air path, which sends air to said reformer is closed by said control during the warm-holding mode. ### Claim 21 A fuel cell system, comprising: a fuel cell; a reformer; a fluid circuit for circulating a fluid between said fuel cell and said reformer for transferring heat, via a fluid in said fluid circuit, between said fuel cell and said reformer; a fluid delivery device for feeding the fluid in said fluid circuit; a control operating the fuel cell system including operating said fuel cell and said reformer, said control establishing a warm-holding mode in which said control controls said fluid delivery device to control heat transfer from said fuel cell to said reformer and heat transfer takes place from said fuel cell to said reformer and said control activating the warm-holding mode after said fuel cell has been switched off.