Aircraft Inerting System Membrane Temperature Control
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Solution Overview
Problem
Inerting systems for aircraft fuel tanks face challenges in maintaining optimal membrane temperature to enhance oxygen depletion efficiency, as they are sensitive to heat losses and limited by air flow rates, which can lead to reduced oxygen purity and increased engine bleed consumption, particularly for aircraft with non-standard flow rates.
Innovation Solution
An inerting system with a heating system outside the enclosure, which heats a significant portion of the membranes to maintain them within their optimal operating temperature range, using an electric heating system controlled by sensors to manage temperature and power based on external conditions and air flow rates, allowing for efficient oxygen depletion without excessive engine bleed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the air flow rate passing through the membrane is increased to improve heating efficiency and oxygen permeability, then the membrane temperature is maintained better, but the quantity of filtered air is limited and oxygen purity at the outlet deteriorates
Solution Approach 1:
The air separating device is divided into multiple membranes arranged in parallel, each membrane handling a portion of the air flow. This segmentation allows each membrane to operate at optimal temperature with controlled flow rates while collectively providing sufficient oxygen-depleted air output.
Solution Approach 2:
The invention introduces a thermal dimension by adding a heating system that operates independently from the air flow rate. Instead of relying solely on increasing air flow to heat the membranes, a dedicated heating system provides thermal energy from an external source, decoupling temperature control from flow rate control.
2Loss of energy
If the air flow rate is increased to improve heating efficiency, then heat losses are reduced, but the engine bleed consumption increases significantly
Solution Approach 1:
A heating system acts as an intermediary between the engine bleed air source and the membranes. This intermediary component (heating system) provides the necessary thermal energy to the membranes without requiring high air flow rates, thus reducing the burden on the engine while maintaining membrane temperature.
Solution Approach 2:
The invention replaces the mechanical heating approach (relying on high-velocity air flow through the membranes to generate heat via friction and convection) with a thermal heating approach (using a dedicated heating system to provide thermal energy directly to the membranes or the air stream).
3Temperature
If the temperature at the inlet of each membrane is increased significantly to curb heat losses, then the membrane temperature is maintained, but the polymer fibers in the membrane are damaged
Solution Approach 1:
The heating system operates continuously to maintain membrane temperature within the optimal range, ensuring consistent oxygen permeability and preventing temperature fluctuations that could lead to thermal stress and damage to the polymer fibers.
Solution Approach 2:
The system incorporates temperature sensors and control mechanisms that continuously monitor membrane temperature and adjust the heating system output accordingly. This feedback control ensures the membranes operate within their thermal tolerance limits, preventing overheating and fiber damage.
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 improves oxygen depletion efficiency in fuel tanks by minimizing heat losses and maintaining membrane temperature, reducing the need for significant engine bleed and ensuring consistent oxygen purity, while accommodating various aircraft flow rates.
Implementation Method 1
the separating device is sensitive to heat losses caused by the environment in which it is installed and which decrease the temperature of the air passing through the membranes
Implementation Method 2
the air separating device typically comprises membranes, which are for example permeable to oxygen but not to nitrogen
Implementation Method 3
the increase in this flow rate improves the internal convection of the membrane and decreases the impact of heat losses thereof
Data Source
AI summary
An inerting system comprises an air separating device having an enclosure (40) having at least one air inlet (46) and one outlet (48) for oxygen-depleted air. The air separating device (18) is configured to generate, from an air inlet flow coming from the air inlet (46) of the enclosure (40), an outlet flow of oxygen-depleted air and to discharge the outlet flow of oxygen-depleted air through the outlet (48) for oxygen-depleted air. The inerting system (14) comprises a heating system (20), outside the enclosure (40), configured to heat at least one region of the enclosure (40).