Fuel Cell Quick Restart via Thermal and Fuel Management
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Solution Overview
Problem
Fuel cell power plants in vehicles, such as electric vehicles, face inefficiencies due to the need to idle when power is not required, as restarting from a shutdown takes several minutes, leading to catalyst oxidation and increased voltage issues.
Innovation Solution
Implementing a quick restart function by monitoring the time since shutdown and adjusting the fuel purge and thermal management systems to reduce startup time, allowing for rapid reactivation without full shutdown procedures, thus minimizing idling and preventing catalyst oxidation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the fuel cell power plant is shut down to avoid idling, then energy waste from idling is reduced, but the restart time increases by several minutes
Solution Approach 1:
The thermal management system continues operating after shutdown to pre-maintain temperature conditions, and the fuel system performs partial purge operations in advance, so that when restart is commanded, the system is already prepared for rapid reactivation without requiring full shutdown procedures
Solution Approach 2:
The system dynamically adjusts the restart procedure based on the duration since shutdown. For short shutdown periods, a quick restart mode is initiated with reduced fuel purge and maintained thermal management, whereas longer shutdowns trigger full startup procedures, optimizing the balance between energy savings and restart time
2Loss of energy
If the fuel cell is shut down instead of idling, then catalyst oxidation occurs, but the voltage issues worsen
Solution Approach 1:
The thermal management system continues operating after shutdown to preemptively prevent catalyst oxidation by maintaining temperatures that avoid oxidative conditions, and the fuel system performs controlled purge operations to prevent voltage issues before they occur, rather than waiting for problems to develop
Data Source
AI summary
A fuel cell power plant keeps track, such as with a fuel-off timer (41), of the extent to which shutdown of the fuel cell power plant has occurred, in case the fuel cell power plant is quickly commanded to resume full operation. In one embodiment, if the fuel-off timer has not timed out at the time that the fuel cell power plant is ordered to resume full operation, a fuel-on timer is set (51) equal to the value of the fuel-off timer when the fuel cell power plant is ordered to resume full operation. Then, the fuel cell power plant is refueled (22), in a duration of time related to the setting of the fuel-off timer, rather than doing a full fuel purge.