Fuel Cell Water Distribution via Flow Rate Control
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Solution Overview
Problem
In fuel cell systems, insufficient water content in the electrolyte membrane leads to increased impedance and reduced output, with existing methods like lowering hydrogen pressure risking a hydrogen-deficient state, and existing methods for water redistribution are not effective in maintaining uniform water content without lowering fuel gas pressure.
Innovation Solution
A fuel cell system with opposite flow directions for oxidant and fuel gases, where the control unit increases the flow rate of fuel gas and lowers its pressure when the electrolyte membrane is dry, particularly in high-load states, to promote water distribution without reducing fuel gas pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the pressure of hydrogen is lowered to promote water shift from oxidant electrode to fuel electrode, then water content distribution in electrolyte membrane is improved, but hydrogen supply for power generation becomes insufficient
Solution Approach 1:
The invention changes the parameter of fuel gas flow rate instead of pressure. By increasing the flow rate of fuel gas through the recirculation path, water is transported from the oxidant electrode side to the fuel electrode side without lowering hydrogen pressure, thus resolving the contradiction between water distribution and hydrogen supply quantity
Solution Approach 2:
The invention introduces a recirculation path as an intermediary mechanism. This path allows water to be transported from oxidant electrode exhaust to fuel electrode inlet, enabling water redistribution without directly manipulating hydrogen pressure, thereby avoiding hydrogen supply deficiency
2Stability of the object's composition
If oxygen-containing gas is supplied at higher pressure to exhaust water to fuel electrode side, then water content compensation is improved, but pressure difference requirements increase system complexity
Solution Approach 1:
The invention utilizes the existing exhaust gases from the oxidant electrode as the carrier for water transport. The natural flow of exhaust gases through the recirculation path provides the necessary transport mechanism without requiring additional pressure difference control systems, reducing device complexity while achieving water content compensation
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 ensures uniform water content distribution in the electrolyte membrane, preventing output drops and hydrogen insufficiency, while maintaining fuel gas pressure, thus enhancing power generation efficiency.
Implementation Method 1
setting the pressure of hydrogen lower than that of air in the case where water content in a fuel cell is insufficient, to thereby promote shift of water from an oxidant electrode side to a fuel electrode side via the electrolyte membrane
Implementation Method 2
generating power by means of an oxidant gas such as air including oxygen supplied to the oxidant electrode, and a fuel gas including hydrogen supplied to the fuel electrode
Data Source
AI summary
This invention provides a fuel cell system which can render the distribution of water in an electrolyte membrane even without lowing the pressure of a fuel system (1) comprises an electrolyte membrane (11), an oxidant electrode provided on one side of the electrolyte membrane (11), and a fuel electrode provided on the other side of the electrolyte membrane (11). An oxidant gas flow passage (14) for supplying an oxidant gas along the face of the oxidant electrode and a fuel gas flow passage (15) for supplying a fuel has along the face of the fuel electrode are provided so that the flow direction of the oxidant gas faces the flow direction of the fuel gas. A control unit (50) conducts control so that, when the electrolyte membrane (11) is dry, the flow rate of the fuel gas which flows through the fuel gas flow passage (15) is increased.