Fuel Cell Humidification via Off-Gas Recirculation
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Solution Overview
Problem
Conventional fuel cell systems in vehicles face issues with ventilation, leading to the introduction of low-humidity air and static electricity accumulation in the fuel cell chamber, which can affect performance and reliability.
Innovation Solution
A fuel cell system design incorporating an oxygen-containing gas supply apparatus with an oxygen-containing gas supply channel, branch supply channel, discharge channel, and off-gas circulation channel, where highly humid off-gas is recycled and reintroduced upstream to maintain humidity and suppress static electricity, utilizing a humidifier to adjust the humidity of the supplied gas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a ventilation device with a three-way valve is used to ventilate the fuel cell chamber, then hydrogen can be discharged to the outside, but low-humidity air flows into the chamber causing static electricity accumulation
Solution Approach 1:
The patent introduces a humidifier as an intermediary device in the ventilation path. The humidifier adds moisture to the air before it enters the fuel cell chamber, thereby preventing static electricity accumulation while maintaining the hydrogen discharge function. This mediator resolves the contradiction by modifying the air properties without compromising the ventilation capability.
Solution Approach 2:
The patent changes the humidity parameter of the air supplied to the fuel cell chamber. By controlling the humidifier to maintain relative humidity between 30-70%, the system prevents static electricity generation while preserving effective ventilation. This parameter modification directly addresses the harmful effect without sacrificing the discharge function.
2Reliability
If outside air is supplied for ventilation, then the fuel cell chamber can be ventilated, but the humidity of the air drops significantly
Solution Approach 1:
The patent implements a feedback control system that monitors the relative humidity in the fuel cell chamber and adjusts the humidifier operation accordingly. When humidity drops below the 30-70% range, the humidifier increases moisture addition. This feedback mechanism maintains stable humidity levels despite continuous ventilation, preventing excessive moisture loss.
Solution Approach 2:
The patent ensures continuous humidification action during ventilation operations. Rather than allowing humidity to drop periodically, the humidifier operates continuously or in controlled intervals to maintain constant moisture levels in the chamber, ensuring uninterrupted protection against static electricity while allowing ongoing ventilation.
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 design effectively ventilates the fuel cell chamber while minimizing static electricity generation, ensuring optimal operating conditions by maintaining humidity and preventing significant drops in atmospheric moisture levels.
Implementation Method 1
The membrane electrode assembly includes a cathode, an anode, and an electrolyte membrane interposed between the cathode and the anode
Implementation Method 2
The fuel cell performs power generation as a result of electrochemical reactions occurring between an oxygen-containing gas supplied to the cathode and a fuel gas supplied to the anode
Data Source
AI summary
A fuel cell system includes a fuel cell formed by stacking a plurality of power generation cells, and an oxygen-containing gas supply apparatus for supplying an oxygen-containing gas to the fuel cell. The oxygen-containing gas supply apparatus includes an oxygen-containing gas supply channel connected to an oxygen-containing gas inlet of the fuel cell for allowing the oxygen-containing gas to flow from an air pump into the oxygen-containing gas inlet, a branch supply channel branched from the oxygen-containing gas supply channel and which is opened to the inside of a fuel cell chamber, an oxygen-containing gas discharge channel for discharging an oxygen-containing off gas from the fuel cell, and an oxygen-containing off gas circulation channel one end of which is connected to the oxygen-containing gas discharge channel, and another end of which is connected to the oxygen-containing gas supply channel at a position upstream from the air pump.