Fuel Tank Ullage Pressure Control for Flammability Reduction
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Solution Overview
Problem
Commercial aircraft face challenges in reducing the flammability of fuel tank vapors, as existing methods like filling the ullage space with inert gas or increasing tank pressure can be inefficient and may lead to fuel vapor leakage.
Innovation Solution
A fuel storage system that includes a fuel tank, a controllable pressure source, and a controller. The controller calculates the target pressure for the ullage space based on the fuel temperature, ensuring the flammability remains below a predefined threshold by dynamically adjusting the pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the ullage space is filled with inert gas to reduce flammability, then the flammability level is reduced, but the device complexity increases
Solution Approach 1:
The patent changes the physical parameter of pressure in the ullage space to reduce flammability. By increasing the pressure above a predetermined threshold, the system reduces the flammability of fuel vapors without requiring inert gas filling, thus avoiding the complexity of inert gas storage and delivery systems while achieving the same safety objective
Solution Approach 2:
The patent extracts the flammable fuel vapors from the ullage space by compressing them into the liquid fuel phase through pressure increase. This removes the hazardous flammable mixture from the vapor space, reducing flammability risk without adding complex inert gas handling equipment
2Reliability
If the pressure in the ullage space is increased to reduce flammability, then the flammability level is reduced, but fuel vapor leakage increases
Solution Approach 1:
The patent employs a feedback control system that continuously monitors the pressure in the ullage space and adjusts the pressure control mechanism accordingly. When the pressure reaches the predetermined threshold that ensures flammability reduction, the system automatically stops further pressurization, preventing excessive pressure that would cause fuel vapor leakage while maintaining adequate pressure for flammability control
Solution Approach 2:
The patent uses dynamic pressure control rather than static high pressure. The pressure in the ullage space is actively regulated to maintain it at or above the predetermined threshold level, allowing the system to adapt to changing conditions and avoid the harmful effects of overly high pressure while ensuring flammability reduction is always achieved
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 system effectively reduces fuel tank flammability by optimizing pressure in real-time based on fuel temperature, minimizing the risk of fuel vapor leakage and allowing for the use of pressure-based flammability reduction in a wider range of aircraft fuel tanks.
Implementation Method 1
calculate a value for a temperature of fuel inside the fuel tank at a given time based on a current value of a temperature inside a different fuel tank using a predefined relationship between temperature of fuel in the different fuel tank and temperature of fuel in the fuel tank
Implementation Method 2
determine a target pressure for the ullage space at the given time based on information relating to the temperature of fuel inside the fuel tank at the given time... control the pressure source such as to cause the pressure in the ullage space to be substantially equal to the target pressure
Data Source
Figure 1~2
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AI summary
There is provided a fuel storage system. The fuel storage system (2) comprises a fuel tank (21) configured to store a liquid fuel; a controllable pressure source (22) for altering the pressure in an ullage space (211) of the fuel tank; and a controller (24). The controller is configured to determine a target pressure for the ullage space at a given time based on information relating to a temperature of fuel inside the fuel tank at the given time; and to control the pressure source such as to cause the pressure in the ullage space to be substantially equal to the target pressure.