Fuel Cell Oxidant Gas Backpressure Control for Fuel Dilution
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Solution Overview
Problem
Fuel gas permeation through the electrolyte membrane into the cathode during shutdown periods in fuel cell systems leads to accumulation, causing increased oxidant gas pressure requirements for dilution, which in turn increases power consumption, noise, and vibrations in the oxidant gas supplying device.
Innovation Solution
A fuel cell system with an oxidant gas backpressure regulating device and a controller that supplies oxidant gas at elevated pressure and utilizes a stirring effect to dilute permeated fuel gas, controlling valve openings to manage pressure and flow rates, thereby reducing the load on the oxidant gas supplying device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oxidant gas pressure is increased to dilute fuel gas in the cathode, then fuel gas dilution effectiveness is improved, but power consumption and load on the oxidant gas supplying device increases
Solution Approach 1:
The system performs periodic pressure regulation cycles during startup: first increasing oxidant gas pressure to dilute fuel gas, then releasing pressure once dilution is achieved. This periodic action avoids continuous high-pressure operation, thereby reducing overall power consumption while maintaining effective fuel gas dilution when needed.
Solution Approach 2:
The control device monitors oxidant gas pressure and uses this feedback to regulate the backpressure regulating valve. When pressure reaches the target level for effective dilution, the system automatically releases pressure, preventing excessive power consumption while ensuring fuel gas dilution effectiveness is achieved.
2Reliability
If oxidant gas pressure is increased to dilute fuel gas, then fuel gas dilution is improved, but noise and vibrations from the oxidant gas supplying device increase
Solution Approach 1:
The system applies high pressure periodically only when needed for fuel gas dilution, then releases pressure to reduce noise and vibrations. This intermittent operation pattern maintains dilution effectiveness while minimizing harmful noise and vibration generation during non-critical periods.
3Quantity of substance
If fuel gas concentration in the oxidant gas system is large, then dilution requirement increases, but the required oxidant gas pressure becomes excessively high
Solution Approach 1:
The control device continuously monitors oxidant gas pressure and regulates the backpressure regulating valve based on feedback signals. When pressure reaches the level sufficient for dilution, the system automatically releases pressure, preventing excessively high pressure conditions while ensuring adequate dilution of fuel gas concentrations.
Solution Approach 2:
The system dynamically adjusts the backpressure regulating valve opening degree to change oxidant gas pressure parameters. By controlling the valve opening based on monitored pressure levels, the system maintains pressure within optimal ranges for dilution without allowing excessively high pressure 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
Effectively dilutes and exhausts fuel gas from the cathode while minimizing the load on the oxidant gas supplying device, reducing power consumption and noise, and preventing excessive pressure buildup.
Implementation Method 1
an oxidant gas backpressure regulating device configured to regulate the pressure of the oxidant gas at the cathode of the fuel cell according to a valve opening
Implementation Method 2
fuel gas remaining in the anodes sometimes permeates the electrolyte membranes and enters into the cathodes during a shutdown period of the system
Implementation Method 3
the concentration of fuel gas in the cathode is decreased both by providing the oxidant gas at an elevated pressure and by the stirring effect created by flowing the oxidant gas through the cathode
Data Source
AI summary
A fuel cell system includes a fuel cell having an anode, a cathode, and an electrolyte membrane disposed therebetween. An oxidant gas supplying device supplies oxidant gas to the cathode, an oxidant gas backpressure regulating device regulates the pressure of the oxidant gas at the cathode according to a valve opening, and a pressure detecting device detects the oxidant gas pressure at the cathode. During a start-up fuel gas disposal process, a controller controls the oxidant gas supplying device to supply the oxidant gas at a standard oxidant gas flow, controls the valve opening of the oxidant gas backpressure regulating device to a first valve opening, and controls the valve opening of the oxidant gas backpressure regulating device to a second valve opening which is greater than the first valve opening when the oxidant gas pressure detected by the pressure detecting device reaches an elevation target pressure.