Apparatus and method for fuel cell start from freezing without melting ice
AssigneeAudi AG
InventorsRobert M. Darling, Timothy W. Patterson, Jr., Michael L. Perry, Jonathan O'Neil
Life of this patent
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Abstract
Fuel cell systems and related methods involving accumulators with multiple regions of differing water fill rates are provided. At least one accumulator region with a relatively more-rapid fill rate than another accumulator region is drained of water at shutdown under freezing conditions to allow at least that region to be free of water and ice. That region is then available to receive water from and supply water to, a fuel cell nominally upon start-up. The region having the relatively more-rapid fill rate may typically be of relatively lesser volume, and may be positioned either relatively below or relatively above the other region(s).
Claims18
A method of operating a fuel cell system at shutdown under freezing conditions, the fuel cell system having a fuel cell stack, and an accumulator for receiving water from and supplying water to the fuel cell stack, the accumulator having structure defining a first region having a first volume configured to contain a volume of water during steady state operation of the fuel cell stack and configured to fill with water vertically at a first rate for an arbitrary fill water flow rate, and structure defining a second region having a second volume and configured to fill with water vertically at a second rate greater than said first rate for said same arbitrary fill water flow rate, said first volume of said first region being greater than said second volume of said second region, the method comprising:
- draining water from the second region of the accumulator at shutdown to allow the second region to be substantially water and ice-free during shutdown, whereby said second region of the accumulator may receive water from and supply water to the fuel cell stack upon start up.
A method of operating a fuel cell system at shutdown under freezing conditions, the method comprising:
- providing a fuel cell stack and an accumulator for receiving water from and supplying water to the fuel cell stack, the accumulator having structure defining a first region having a first volume configured to contain a volume of water during steady state operation of the fuel cell stack and configured to fill with water vertically at a first rate for an arbitrary fill water flow rate, and structure defining a second region having a second volume and configured to fill with water vertically at a second rate greater than said first rate for said same arbitrary fill water flow rate, said first volume of said first region being greater than said second volume of said second region, and the accumulator including a drain in the second region;
- and
- draining water from at least the second region of the accumulator at shutdown to allow the second region to be substantially water and ice-free upon shutdown, whereby said second region of the accumulator may receive water from and supply water to the fuel cell stack upon start up.
A method of operating a fuel cell system having a fuel cell stack and an accumulator for receiving water from and supplying water to the fuel cell stack, the accumulator having structure defining a first region having a first volume configured to contain a volume of water during steady state operation of the fuel cell stack and configured to fill with water vertically at a first rate for an arbitrary fill water flow rate, and structure defining a second region having a second volume and configured to fill with water vertically at a second rate greater than said first rate for said same arbitrary fill water flow rate, said first volume of said first region being greater than said second volume of said second region, the method comprising:
- shutting down the fuel cell system under freezing conditions;
- draining water from at least the second region of the accumulator at shutdown to allow the second region to be substantially water and ice-free upon shutdown;
- and
- supplying water from the fuel cell stack to the second region of the accumulator and withdrawing water from the second region of the accumulator for supply to the fuel cell stack upon start up.
Dependencies are inferred from the claim text.