Variable Permeability Membrane for Fuel Cell Crossover Control
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Solution Overview
Problem
Fuel crossover in fuel cells, where reactants like methanol migrate through the electrolyte from the anode to the cathode, leading to reduced fuel utilization efficiency and performance losses, is a significant issue, particularly for cells supplying electrical energy to variable loads, and existing solutions often require excessive water or complex processes.
Innovation Solution
A fuel cell system with a fuel delivery system that controls the molecular ratio of fuel and water through a controller and pumping apparatus, using jet nozzles or porous membranes with variable permeability to limit fuel crossover by ensuring only the necessary amount of fuel is available at the anode for electro-oxidation, thereby minimizing waste and poisoning of the cathode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If conventional methods are used to reduce fuel crossover, then fuel crossover is reduced, but excessive water is required and device complexity increases
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the permeability of the porous membrane based on load conditions. The membrane permeability is modified to allow controlled fuel crossover at high loads while preventing excessive crossover at low loads, eliminating the need for excessive water and complex processing systems.
Solution Approach 2:
The patent implements dynamics by using a porous membrane with variable permeability that can adapt its fuel transport properties according to operating conditions. The membrane transitions between different permeability states to optimize fuel utilization across varying load conditions, replacing static conventional methods with a dynamic adaptive system.
2Loss of substance
If conventional methods are used to reduce fuel crossover, then fuel utilization efficiency is improved, but the amount of water required increases
Solution Approach 1:
The patent changes the permeability parameter of the porous membrane to control fuel transport. By adjusting membrane permeability according to load conditions, the system achieves high fuel utilization efficiency without requiring excessive water, as the membrane itself becomes the primary control mechanism rather than water-based dilution methods.
Solution Approach 2:
The porous membrane acts as an intermediary between the fuel supply and the electrochemical reaction. It mediates fuel transport by allowing controlled crossover based on its permeability characteristics, replacing the need for water as a controlling medium and directly regulating fuel delivery to optimize utilization efficiency.
3Power
If fuel is supplied to meet peak load demands, then power output is sufficient, but fuel crossover increases during low load operation
Solution Approach 1:
The patent applies dynamics by making the membrane permeability variable rather than fixed. The permeability adapts to load conditions: at high loads, increased permeability allows sufficient fuel supply for peak power output, while at low loads, decreased permeability prevents excessive fuel crossover, optimizing fuel utilization across the entire operating range.
Solution Approach 2:
The system changes the permeability parameter of the porous membrane in response to varying load conditions. This parameter modification enables the system to maintain adequate fuel supply for peak power demands while automatically reducing fuel crossover during low load operation, eliminating the need to oversupply fuel for peak conditions.
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 effectively reduces fuel crossover, optimizing fuel utilization and maintaining performance across varying load conditions without the need for excessive water or complex processes, ensuring efficient energy production and extending the lifespan of the fuel cell.
Implementation Method 1
a porous membrane with variable permeability is provided between the anode layer and the fuel-water mixture, the porous membrane allowing controlled transport of fuel and water
Implementation Method 2
A fuel cell system with a fuel delivery system that controls the molecular ratio of fuel and water through a controller and pumping apparatus, using jet nozzles or porous membranes
Implementation Method 3
Fuel cells are electrochemical cells in which a free energy change resulting from a fuel oxidation reaction is converted into electrical energy
Implementation Method 4
The protons formed at the anode electro catalyst migrate through the ion-exchange membrane from the anode to the cathode
Data Source
AI summary
A method of and fuel cell system for limiting an amount of a fuel crossing over a membrane in a fuel cell, the method including determining an appropriate molecular ratio of the fuel and water for a fuel-water mixture 503; and controlling an amount of the fuel-water mixture that is available to an anode side of the membrane 507 in the fuel cell according to an amount of the fuel that will be electro-oxidized by the fuel cell. The fuel cell system includes a fuel cell membrane 103 having an anode layer 107, a cathode layer 109, and an electrolyte layer 111 where the cathode layer is exposed to an oxygen source, and a fuel delivery system 105 including a fuel chamber 119 disposed around and proximate to the anode layer at a side opposite to the electrolyte layer, the fuel delivery system implementing the method above.