Catalytic Reactor Oxygen Sensor for Aircraft Fuel Tank Ullage
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Solution Overview
Problem
Existing systems for measuring oxygen concentration in aircraft fuel tanks, particularly in high-temperature environments, face challenges due to the risk of ignition, necessitating indirect measurement methods that rely on approximations rather than direct sensing.
Innovation Solution
A system comprising a catalytic reactor with upstream and downstream temperature sensors, which calculates oxygen concentration by measuring temperature differences across the reactor, allowing for precise determination of oxygen levels without direct temperature sensing in hazardous areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an oxygen sensor is located upstream of the fuel tank to measure oxygen concentration, then the measurement avoids ignition risk, but the measurement is indirect and relies on approximations rather than direct sensing
Solution Approach 1:
The patent introduces a catalytic converter as an intermediary component between the oxygen sensor and the fuel tank. The catalytic converter converts a portion of the oxygen in the nitrogen-enriched air stream into carbon dioxide and water through catalytic oxidation, thereby reducing the oxygen concentration before it reaches the sensor. This intermediary mechanism allows the sensor to indirectly measure the original oxygen concentration by detecting the change in gas composition after partial oxidation, achieving both safety and improved measurement accuracy.
2Measurement precision
If a temperature sensor is placed directly in the fuel tank ullage to measure oxygen concentration, then direct measurement is achieved, but the high reference temperature creates ignition risk
Solution Approach 1:
The catalytic converter serves as a protective intermediary that allows the temperature sensor to operate in a safer environment. By positioning the sensor downstream of the catalytic converter rather than directly in the fuel tank ullage, the sensor measures gases that have already undergone partial oxidation and are at lower temperature, eliminating the ignition risk while maintaining measurement capability through the established catalytic oxidation model.
3Measurement precision
If nitrogen-enriched air flow rate through the air separation module is increased, then the nitrogen-enriched air purity is improved, but the power consumption increases
Solution Approach 1:
The patent implements a feedback control system where the oxygen sensor continuously monitors the oxygen concentration in the nitrogen-enriched air stream (either directly or through the catalytic converter approach). The control unit receives this feedback signal and adjusts the flow control valve to optimize the balance between nitrogen-enriched air purity and power consumption. By maintaining oxygen concentration within a target range rather than constantly maximizing purity, the system reduces unnecessary power consumption while still achieving effective fuel tank inerting.
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 method provides accurate oxygen concentration measurements in high-temperature environments, reducing the reliance on approximations and enabling more efficient control of nitrogen generation systems to maintain fuel tank inertness, thereby optimizing nitrogen usage and power conservation.
Implementation Method 1
The catalytic reactor includes a catalyst that supports the combustion of oxygen
Implementation Method 2
The catalytic reactor includes a catalyst that supports the combustion of oxygen
Implementation Method 3
The first temperature sensor is located upstream of the catalytic reactor for sensing an upstream temperature of the gas stream, and the second temperature sensor is located downstream of the catalytic reactor for sensing a downstream temperature of the gas stream
Data Source
AI summary
A system for measuring the oxygen concentration of a gas includes a catalytic reactor, first and second temperature sensors and a control unit. The catalytic reactor includes a combustion catalyst that supports the catalytic combustion of hydrocarbon fuel vapor in a gas stream. The first temperature sensor is located upstream of the catalytic reactor for sensing an upstream temperature of the gas stream, and the second temperature sensor is located downstream of the catalytic reactor for sensing a downstream temperature of the gas stream. The control unit compares the upstream temperature and the downstream temperature to determine the oxygen concentration of the gas stream.