Fuel Cell Water Drainage via Cathode Pressure Pulsation
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Solution Overview
Problem
Existing fuel cell systems face challenges in efficiently draining water that builds up within the membrane-electrode assembly and catalyst layer during temperature changes, leading to reduced gas diffusion and power generation efficiency, especially when ice freezes and defrosts, causing a vicious cycle that disrupts the fuel cell's operation.
Innovation Solution
A fuel cell system with a temperature sensor, pressure sensor, and pressure regulator that applies pulsation to the cathode electrode pressure when the temperature rises above freezing, creating a pressure gradient to effectively drain water and maintain gas flow, while ensuring the pressure remains above a reference value to prevent output drops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the temperature of the fuel cell exceeds 0 degree after actuation below freezing temperature, then the frozen ice is defrosted, but the rapid water generation blocks the gas flow channel and disturbs smooth drainage of the generated water
Solution Approach 1:
The patent applies periodic pressure pulsation to the cathode electrode pressure when the temperature exceeds 0 degree. This periodic action creates alternating high and low pressure phases that facilitate water drainage during the low pressure phase while maintaining adequate gas supply during the high pressure phase, resolving the contradiction between defrosting and water drainage.
Solution Approach 2:
The patent dynamically changes the pressure parameter of the cathode electrode by applying pressure pulsation. This parameter change enables the system to overcome the water blocking issue by creating pressure gradients that drive water drainage while maintaining fuel cell operation above freezing temperature.
2Productivity
If pressure of reactant gas is increased to compensate for decreased gas diffusion, then gas supply to reaction surface is improved, but water drainage from inside of membrane-electrode assembly and catalyst layer is insufficient
Solution Approach 1:
The patent employs periodic pressure pulsation that creates alternating high and low pressure phases. During the low pressure phase, water is effectively drained from the membrane-electrode assembly and catalyst layer, while during the high pressure phase, gas supply to the reaction surface is enhanced. This periodic action resolves the contradiction between gas supply and water drainage.
3Productivity
If the fuel cell operates below freezing temperature, then power generation can be maintained, but water freezes and builds up blocking reactant gas flow channel
Solution Approach 1:
The patent applies pressure pulsation as a preliminary action when the temperature exceeds 0 degree to prevent water buildup before it can block the gas flow channels. This preliminary drainage action prevents the formation of ice blocks that would otherwise occur during subsequent cooling periods, maintaining power generation capability.
Solution Approach 2:
The patent changes the pressure parameter by applying pulsation to create favorable conditions for water drainage during temperature transitions. This parameter change prevents water freezing and buildup, allowing the fuel cell to maintain power generation even during cold operation.
4Temperature
If generated water builds up within membrane-electrode assembly and catalyst layer, then gas diffusion is disturbed and temperature rise is suppressed, but this creates a vicious cycle that reduces power generation
Solution Approach 1:
The patent applies periodic pressure pulsation that creates alternating phases of water drainage and gas supply enhancement. This periodic action breaks the vicious cycle by efficiently removing water during low pressure phases, allowing temperature rise and power generation to improve during high pressure phases without being constrained by water buildup.
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 solution ensures smooth water drainage and improved fuel cell output by utilizing pressure pulsation to enhance gas flow and warm-up effects, stabilizing pressure and gas flow conditions, and rapidly recovering output performance.
Implementation Method 1
a pressure regulator that regulates pressure of the cathode electrode and a pressure control unit that controls the pressure regulator so as to apply pulsation to the pressure of the cathode electrode
Implementation Method 2
a temperature sensor that measures a temperature within the fuel cell stack
Implementation Method 3
a pressure sensor that measures pressure of the cathode electrode
Implementation Method 4
The fuel cell extracts electric energy from electrodes through an electrochemical reaction occurring on a surface of a side of the electrolyte membrane of the paired electrode structure body
Implementation Method 5
the generated water within the fuel cell freezes in a cold environment, e.g., below freezing temperature
Implementation Method 6
the once frozen generated water is defrosted by heat generated at drive of the fuel cell
Data Source
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AI summary
To improve an output of a fuel cell and power generation efficiency by enhancing drainage of the fuel cell upon actuation below freezing temperature. In a fuel cell system that generates power by supplying fuel gas and oxidant gas, the output of the fuel cell is measured when a temperature of the fuel cell after the actuation below freezing temperature exceeds 0 degree, and if a value of the output is equal to or less than a reference output value, pressure pulsation is applied to a cathode electrode to drain water built up in the fuel cell.