Fuel Cell Anode Pressure Control for Start-Up Polarization
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Solution Overview
Problem
Fuel cells experience prolonged high-potential polarization during start-up due to a concentration difference in the anode passage when the inner gas is replaced with oxidant gas, leading to inefficient operation and potential deterioration.
Innovation Solution
A fuel cell system with a fuel-gas-pressure-adjusting-and-supplying unit and a high-pressure-fuel-gas-supply-controlling unit that sets a higher target pressure for fuel gas supply to the anode passage when the inner gas is replaced with oxidant gas, promoting the mixture of oxidant and fuel gases and preventing prolonged high-potential polarization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the fuel cell starts under the condition where inner gas in the anode passage is replaced with oxidant gas, then the concentration difference in fuel gas between inlet and outlet sides of the anode passage becomes large, but the fuel cell is subject to high potential polarization for a long time
Solution Approach 1:
The patent applies parameter changes by adjusting the pressure parameter of fuel gas supply. When oxidant gas is detected in the anode passage, the system increases the target pressure of fuel gas supply from normal operating pressure to a higher pressure, which accelerates the mixing process and reduces the duration of high potential polarization by rapidly equalizing the concentration distribution.
Solution Approach 2:
The patent implements dynamics by making the fuel gas supply pressure adjustable and controllable based on real-time detection of gas composition in the anode passage. The system dynamically switches between normal pressure supply and high pressure supply modes, allowing the pressure parameter to adapt to changing operational conditions and optimize the mixing process.
2Productivity
If high pressure fuel gas is supplied to promote mixing of oxidant and fuel gases, then the concentration difference is reduced rapidly, but the system complexity increases due to pressure control requirements
Solution Approach 1:
The patent employs feedback control through a gas composition detector that continuously monitors the anode passage for the presence of oxidant gas. This feedback signal triggers the pressure control unit to adjust the fuel gas supply pressure accordingly, creating a closed-loop control system that automates the high pressure supply decision-making process and reduces operational complexity.
Solution Approach 2:
The system implements self-service by using the gas composition detector to automatically detect oxidant gas presence and trigger the appropriate pressure supply mode without requiring manual intervention. The control unit autonomously decides when to switch between normal and high pressure supply based on real-time gas composition data, simplifying the operational interface.
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 configuration effectively reduces the concentration difference in the anode passage, preventing fuel cell polarization at high potential and enhancing start-up efficiency by ensuring efficient mixing of gases.
Implementation Method 1
a fuel-gas-pressure-adjusting-and-supplying unit which is disposed on the fuel gas inlet passage and adjusts a pressure of the fuel gas to supply the fuel gas to the anode passage
Data Source
AI summary
Provided is a fuel cell system capable of preventing a fuel cell from being polarized at a high potential for a long time during start-up. A fuel cell system 1 includes a first injector 23A and a second injector 23B in a fuel gas inlet passage. When an ECU 60 determines that a power generation down time is equal to or more than a predetermined period at start-up of a fuel cell stack 10, a target pressure of hydrogen supplied to an anode passage 12 is set to be higher for supply than when the power generation down time is less than the predetermined period. In addition, as the power generation down time of the fuel cell stack 10 becomes longer, the target pressure is set to be higher. Also, a pressure increase in the fuel cell stack is set to be lower than that during ordinary power generation.