Internal Recycle Reactor for Fuel Tank Inerting
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Solution Overview
Problem
Conventional air separation module (ASM) methods for fuel tank inerting in aircraft require bleed air, which may not be available in sufficient quantity or pressure, leading to engine idling during descent, and do not effectively manage heat generated by catalytic oxidation reactions.
Innovation Solution
An integrated ejector-style reactor with a catalyst and recycle loop, which recycles exhaust gas internally to manage heat and reduce oxygen and fuel availability, eliminating the need for external recycle devices and allowing operation with various air sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional air separation module (ASM) methods are used for fuel tank inerting, then oxygen separation can be achieved, but bleed air availability and pressure are insufficient leading to engine idling during descent
Solution Approach 1:
The catalytic oxidation system is designed to accept multiple air sources including engine bleed air, APU air, and ram air, making the system versatile and adaptable to different flight conditions. The reactor can effectively process inerting tasks regardless of which air source is available, eliminating the limitation of conventional ASM systems that require specific bleed air conditions.
2Use of energy by moving object
If catalytic oxidation reactions are used for inerting, then oxygen consumption is reduced, but significant heat generation occurs requiring external recycle devices
Solution Approach 1:
The ejector and recycle loop are integrated directly into the reactor body, forming a unified structure where the exhaust gas is internally recirculated. This merging of functions eliminates the need for separate external recycle devices while effectively managing reactor temperature through continuous exhaust gas recirculation that reduces oxygen and fuel availability at the catalyst surface.
3Temperature
If external recycle devices are used for heat management, then temperature control is improved, but device complexity increases
Solution Approach 1:
The ejector-style recycle loop is integrated within the reactor body itself, combining the heat management function with the existing reactor structure. This internal integration eliminates the need for separate external recycle devices, reducing system complexity while maintaining effective temperature control through exhaust gas recirculation.
4Stress or pressure
If bleed air from compressor stage is used, then sufficient pressure and quantity can be obtained, but aircraft engines must idle during descent
Solution Approach 1:
The system is designed to accept multiple air sources including ram air during descent, APU air, and engine bleed air. This versatility allows the system to maintain sufficient pressure and quantity for effective inerting without requiring engine idle during descent, thereby preserving descent efficiency while ensuring adequate air supply for the catalytic oxidation process.
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 solution enables efficient production of inert gas with low oxygen levels, reducing the risk of combustion and explosion in fuel tanks while managing heat generation, thereby enhancing safety and operational flexibility.
Implementation Method 1
Catalytic oxidation of fuel can leverage a variety of incoming air sources, not limited to bleed air, to produce inert air with oxygen levels below the required 12% oxygen (or 9% for military engines) over a range of conditions. In catalytic oxidation, a catalyst can be used to catalyze a chemical reaction between oxygen (O 2 ) and fuel to produce carbon dioxide (CO 2 ) and water.
Implementation Method 2
In catalytic oxidation, a catalyst can be used to catalyze a chemical reaction between oxygen (O 2 ) and fuel to produce carbon dioxide (CO 2 ) and water. Catalytic oxidation is an exothermic reaction, which can produce a significant amount of heat.
Implementation Method 3
Catalytic oxidation is an exothermic reaction, which can produce a significant amount of heat.
Implementation Method 4
The heat produced must be managed to prevent damage to the oxidizer system and to minimize any hazard to the aircraft. One method to manage the heat within the oxidizer system is to recycle a portion of the oxidizer exhaust back to the inlet of the reactor. The exhaust gas can internally cool the reactor and minimize heat release within the reactor by reducing the amount of oxygen and fuel available for reaction, minimizing the difference between inlet and outlet reactant concentrations, and changing the residence time across the catalyst.
Data Source
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AI summary
An internal recycle reactor for catalytic inerting has a monolithic body having a motive fluid duct (38), a suction chamber (42), a mixing region (44), a reactor section (46), an outlet (34), and a recycle passage (50). The suction chamber includes a suction chamber inlet. The mixing region is configured to receive gaseous fluids from the motive fluid duct and the suction chamber inlet to produce a gaseous mixture. The reactor section includes a catalyst and is configured to receive the gaseous mixture from the mixing region. The outlet is configured to deliver an exhaust gas from the reactor section and the recycle passage is configured to deliver a portion of the exhaust gas to the suction chamber inlet.