Fuel Cell Membrane Drying via Anode Flow and Cathode Heat
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Solution Overview
Problem
The existing fuel cell systems face challenges in efficiently controlling the wet/dry state of electrolyte membranes during dry operations, leading to extended periods due to increased water vapor retention with temperature increases, which affects the dryness degree of the membranes.
Innovation Solution
A fuel cell system with a control method that adjusts the flow rate of fuel and the temperature of the oxidant gas, using a detection unit to monitor the wet/dry state and adjust the anode gas flow rate and cathode gas temperature to efficiently reduce water content in the electrolyte membrane.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the temperature of the fuel cells is increased to increase the amount of water vapor retained in the oxidant gas during dry operation, then the water vapor retention capability is improved, but the amount of water vapor transmitted through the electrolyte membrane into the fuel gas increases, extending the dry operation period
Solution Approach 1:
The patent applies parameter changes by adjusting the flow rate of fuel supplied to the fuel cells during dry operation. Specifically, the control unit reduces the fuel flow rate to a value lower than during normal operation, which decreases the water vapor content in the fuel gas and accelerates the drying process of the electrolyte membrane, thereby resolving the contradiction between temperature increase and extended dry operation time.
2Manufacturing precision
If the flow rate of fuel is reduced to decrease water vapor in the fuel gas, then the wetness degree control is improved, but the electricity generation efficiency may be affected
Solution Approach 1:
The patent applies dynamics by implementing dynamic adjustment of the fuel flow rate based on the operational state of the fuel cells. The control unit dynamically reduces the fuel flow rate during dry operation and restores it to normal levels when drying is complete, thereby maintaining precise wetness degree control while minimizing impact on electricity generation efficiency.
Solution Approach 2:
The patent applies periodic action by executing dry operation as a temporary, periodic process rather than a continuous state. The system periodically switches between normal operation and dry operation modes, reducing fuel flow rate only during the necessary drying period, thus balancing wetness control precision with overall electricity generation efficiency.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for efficient control of the wet/dry state, reducing the time required for dry operations by prioritizing the reduction of the anode gas flow rate and increasing the cathode gas temperature, thereby maintaining optimal membrane dryness and improving electricity generation performance.
Implementation Method 1
an oxidant gas supplied to fuel cells is humidified by water vapor that accompanies electricity generation
Implementation Method 2
the amount of water vapor that is transmitted from the oxidant gas through the electrolyte membrane and mixed into the fuel gas
Data Source
AI summary
A fuel cell system includes a fuel supply unit that supplies a fuel to electrolyte membrane of fuel cell, an oxidant supply unit that supplies an oxidant to the electrolyte membrane, and an electricity generation control unit that controls electricity generation by the fuel cell by controlling supply of the oxidant by the oxidant supply unit and supply of the fuel by the fuel supply unit. the fuel cell system includes a wet/dry state detection unit configured to detect a wet/dry state of the electrolyte membrane, a flow rate adjustment unit configured to adjust a flow rate of the fuel supplied to the fuel cell by the fuel supply unit; and a temperature adjustment unit configured to adjust a temperature of the oxidant supplied to the fuel cell by the oxidant supply unit. when reducing an amount of water in the electrolyte membrane in accordance with a signal output from the wet/dry state detection unit, the electricity generation control unit is configured to reduce the flow rate of the fuel, and increase the temperature of the oxidant in accordance with the signal from the wet/dry state detection unit, compared with when increasing the amount of water in the electrolyte membrane.