Aircraft Fuel Tank Inerting via Fuel Cell Carbon Dioxide Recycling
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Solution Overview
Problem
Conventional fuel tank inerting systems for aircraft, such as On-Board Inert Gas Generation Systems (OBIGGS) and passive inert systems, are costly, complex, and logistically challenging, while foam-based solutions are heavy, inefficient, and require frequent replacement, failing to effectively reduce the risk of fuel tank ignition incidents.
Innovation Solution
A fuel system that utilizes a hydrogen fuel cell array and a fuel reformer to produce carbon dioxide as a waste gas, which is then recycled and conditioned to inert the fuel tank ullage space, eliminating the need for OBIGGS and providing a cost-effective, efficient means to reduce flammability without generating additional greenhouse gases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If OBIGGS system is used to generate oxygen-depleted gas for fuel tank inerting, then the flammability of fuel vapor is reduced, but the device complexity and cost increase significantly
Solution Approach 1:
The fuel cell system serves dual purposes: generating electricity for the aircraft and producing inert gas for fuel tank protection. The same hydrogen fuel cells that power the aircraft also generate carbon dioxide as a byproduct, which is then used to inert the fuel tanks, making the system self-sufficient and eliminating the need for separate inert gas generation equipment
Solution Approach 2:
The hydrogen fuel cell system performs multiple functions simultaneously: it generates electrical power for the aircraft and produces carbon dioxide gas that serves as the inerting agent for fuel tanks. This multi-functionality eliminates the need for separate OBIGGS equipment, reducing overall system complexity while maintaining fuel tank safety
2Reliability
If passive inert system with bottled gas is used, then fuel tank inerting is achieved, but logistical requirements and operational complexity increase
Solution Approach 1:
The aircraft generates its own inert gas supply through the fuel cell system during normal operation. The carbon dioxide produced as a byproduct of electricity generation is captured and used to inert the fuel tanks, eliminating the need for external bottled gas supplies and the logistical burden of storing, handling, and replacing them
3Reliability
If foam is used to prevent fuel tank ignition, then ignition probability is reduced, but the system becomes heavy and requires frequent replacement
Solution Approach 1:
The fuel cell system continuously generates inert gas during aircraft operation, providing ongoing protection without the weight and replacement issues of foam systems. The carbon dioxide produced during electricity generation is continuously supplied to the fuel tanks, creating a dynamic protection system that does not degrade over time like foam
Solution Approach 2:
The system changes the chemical composition of the gas in the fuel tank ullage space by introducing carbon dioxide, which reduces the oxygen concentration below the ignition limit. This parameter change (oxygen concentration) provides continuous protection without adding physical mass like foam would
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 eliminates the need for expensive OBIGGS systems, reduces logistical burdens, and recycles a waste product to inert the fuel tank, enhancing aircraft efficiency and safety by minimizing the risk of fuel tank ignition while avoiding additional greenhouse gas emissions.
Implementation Method 1
a fuel reformer for receiving fuel from the fuel tank
Implementation Method 2
a hydrogen fuel cell array for receiving hydrogen from the fuel reformer
Implementation Method 3
a mechanism for providing an inerting gas from the fuel system to the fuel tank
Data Source
AI summary
A fuel system for an aircraft is disclosed. The fuel system comprises a fuel tank and a fuel reformer for receiving fuel from the fuel tank. The system includes a hydrogen fuel cell array for receiving hydrogen from the fuel reformer. The system further includes mechanism for providing an inerting gas from the fuel system to the fuel tank.