Fuel Cell Pressure Control for Membrane Protection
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Solution Overview
Problem
Fuel cell systems face challenges in maintaining appropriate fuel gas supply while reducing impurity concentration, leading to inefficient fuel usage and potential damage to the electrolyte membrane due to difficulties in controlling anode-cathode differential pressure.
Innovation Solution
A fuel cell system with gas supply pressure control means that adjusts the gas supply pressure to increase the anode-cathode differential pressure when the reaction gas supply is insufficient, allowing for desired generation without the need for a purge process by selectively routing the gas through higher pressure reduction valves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the fuel off gas is circulated to increase fuel efficiency, then the fuel efficiency is improved, but the concentration of impurities in the fuel gas increases
Solution Approach 1:
The invention changes the pressure parameter of the fuel gas by using a pressure reduction valve with a higher set pressure. This allows the system to operate with higher fuel gas pressure and flow rate, which compensates for the increased impurity concentration from off-gas circulation, enabling the system to achieve the desired generation amount without purging
Solution Approach 2:
The invention dynamically adjusts the pressure reduction valve set pressure based on operating conditions. By making the pressure parameter adjustable rather than fixed, the system can adapt to varying load conditions and impurity concentrations, allowing off-gas circulation to be maintained while still achieving sufficient gas supply for the required generation
2Quantity of substance
If the fuel off gas is purged to reduce impurity concentration, then the impurity concentration is reduced, but the fuel efficiency decreases due to extra fuel gas discharge
Solution Approach 1:
Instead of reducing pressure to purge impurities, the invention increases the pressure reduction valve set pressure to maintain higher fuel gas pressure and flow rate. This parameter change allows the system to handle higher impurity concentrations from off-gas circulation without needing to purge, thereby eliminating the fuel waste associated with purging while maintaining acceptable impurity levels
3Reliability
If the anode-cathode differential pressure is controlled within a predetermined range to prevent membrane damage, then the membrane durability is improved, but the ability to provide appropriate fuel gas supply for high generation requirements is reduced
Solution Approach 1:
The invention changes the pressure parameter by using a pressure reduction valve with a higher set pressure, which increases the fuel gas supply pressure and flow rate. This allows the system to provide sufficient fuel gas supply for high generation requirements while the anode-cathode differential pressure is maintained within the safe range through coordinated control of both fuel and oxidizer gas pressures
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 a desired fuel gas supply amount is achieved while minimizing fuel gas discharge to the exterior, improving fuel efficiency and preventing electrolyte membrane damage by precisely controlling gas supply pressure and flow rate.
Implementation Method 1
gas supply pressure control means for controlling a gas supply pressure so as to maintain an anode-cathode differential pressure between the reaction gas supplied to the fuel pole of the fuel cell and the reaction gas supplied to the oxidizer pole of the fuel cell within a predetermined range
Implementation Method 2
the fuel cell can generate electric energy directly from chemical energy resulting from the oxidation-reduction reaction between the fuel gas and the oxidizer gas
Data Source
AI summary
The present invention provides a fuel cell system that controls a pressure for a fuel gas supplied to a fuel cell so that the anode-cathode differential pressure between an anode and a cathode of a fuel cell is maintained within a predetermined range, in order to provide a desired generation amount while reducing the amount of fuel gas discharged to the exterior of the system even if it is difficult to provide an appropriate fuel gas supply amount for a fuel cell load (the generation requirement on the cell). If the system determines that the amount of fuel gas supplied to the fuel cell is less than an appropriate required gas amount for the load (generation requirement) (step S9: NO), for example, if the concentration of nitrogen in the fuel gas reaches a predetermined value or greater, the open and close state of shut-off valves H3, H3A is switched to increase the pressure for the fuel gas supplied to the fuel cell 20 (step S11).