Fuel Cell Air Humidification Using Recycled Air at Low Power
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Solution Overview
Problem
Fuel cells in aircraft face challenges in achieving low-power operation without exceeding maximum voltage limits, leading to reduced efficiency and shortened lifespan, particularly during low-power regimes like idling phases, while maintaining optimal efficiency during nominal power operations.
Innovation Solution
A method and air supply circuit that recirculate air from the fuel cell to mix with ambient air, adjusting the ratio of recycled air to ambient air based on power or current settings to manage humidity, thereby controlling water and dioxygen concentrations to achieve low-power operation without exceeding voltage limits and reversing this for nominal power efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the fuel cell operates at low power settings, then the power consumption is reduced, but the voltage exceeds the maximum limit causing fuel cell degradation
Solution Approach 1:
The patent changes the chemical composition parameters of the air supplied to the fuel cell by introducing inert gases (nitrogen, carbon dioxide) from the aircraft cabin atmosphere. This modifies the oxygen concentration and partial pressure in the air mixture, enabling the fuel cell to operate at low power settings without exceeding voltage limits, thus resolving the contradiction between low power consumption and fuel cell reliability
Solution Approach 2:
The patent uses the aircraft cabin atmosphere as an intermediary medium. The cabin air, containing inert gases, serves as a mediator that mixes with the air supplied to the fuel cell, allowing voltage control during low-power operation without requiring direct modification of the fuel cell itself, thereby protecting fuel cell lifespan while enabling low-power operation
2Temperature
If the ratio of recycled air to ambient air is increased, then the water concentration in the air supply increases improving humidification, but the dioxygen concentration decreases reducing fuel cell efficiency
Solution Approach 1:
The patent changes the compositional parameters of the air supply by controlling the ratio of recycled air (rich in water vapor) to ambient air (rich in oxygen). By adjusting this ratio, the system optimizes both humidification levels and oxygen concentration dynamically, resolving the contradiction between temperature/humidification and fuel cell efficiency
Solution Approach 2:
The patent implements dynamic adjustment of the air mixing ratio based on real-time fuel cell operating conditions. The control system continuously modifies the proportion of recycled air to ambient air, enabling the system to adapt to varying humidification needs while maintaining optimal oxygen levels for fuel cell efficiency, thus resolving the static contradiction through dynamic control
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
Enables low-power fuel cell operation without voltage limit exceedance, preserving fuel cell life and maintaining optimal efficiency across various power ranges by dynamically adjusting air composition, thus optimizing performance in both low-power and nominal power scenarios.
Implementation Method 1
injecting into the injection line the recovered recycled air so as to mix the recycled air with ambient air
Data Source
AI summary
A method for humidifying an air supply of a fuel cell, an air supply circuit including an injection line, an intermediate line and an evacuation line. The method includes steps for recovering recycled air, in the evacuation line, and injecting recycled air into the injection line so as to mix it with ambient air from the environment. The method additionally includes increasing the ratio of recycled air in the injection line when a power setting of the cell reduces and if the power setting is lower than a predefined power threshold, and reducing the ratio of recycled air when the power setting increases and if the power setting remains lower than the predefined threshold.