Fuel Cell Shutdown Method for Freezing Conditions
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Summary
Problems
Existing methods for shutting down and storing fuel cell systems face challenges in subzero temperatures due to ice formation and inefficient energy use, particularly in automotive applications where rapid start-up is required from freezing conditions.
Innovation solutions
A method that involves monitoring the fuel cell stack temperature and performing initial and predetermined warming operations with varying parameters such as threshold temperatures, reactant flow rates, and heating times to maintain an optimal hydration state, eliminating the need for purging steps and ensuring efficient energy use.
TRIZ Analysis
Specific contradictions:
General conflict description:
Principle concept:
If water is purged out of reactant gas flow channels before storage, then ice formation is reduced, but additional system complexity and time are required
Why choose this principle:
The patent applies preliminary action by maintaining the fuel cell stack at an elevated temperature during shutdown and storage to prevent ice formation before it occurs. The control system monitors temperature and activates heating when the stack temperature approaches freezing points, proactively preventing ice formation in the membrane and flow channels without requiring purging operations.
Principle concept:
If water is purged out of reactant gas flow channels before storage, then ice formation is reduced, but additional system complexity and time are required
Why choose this principle:
The patent extracts the harmful freezing condition by removing excess water through controlled operation before shutdown. By operating the fuel cell in a water-deficient mode prior to shutdown, the system removes liquid water from the membrane and flow channels, eliminating the source material that would otherwise freeze during storage.
Application Domain
Data Source
AI summary:
A method that involves monitoring the fuel cell stack temperature and performing initial and predetermined warming operations with varying parameters such as threshold temperatures, reactant flow rates, and heating times to maintain an optimal hydration state, eliminating the need for purging steps and ensuring efficient energy use.
Abstract
Improved methods are disclosed for shutting down and storing a fuel cell system, particularly for below freezing temperature conditions. The methods comprise stopping power production from the fuel cell stack, monitoring its temperature, and repeatedly performing a predetermined warming operation if the stack temperature falls to a normal threshold temperature. In the improved methods, either an initial threshold temperature and/or an initial warming operation are used that differ from the respective normal threshold temperature and the predetermined warming operation.