Aircraft Bleed-Air Moisture Collection for 5-10 ppm Humidity Sensing
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Solution Overview
Problem
Current humidity sensors, such as capacitive MEMS sensors, are not sensitive enough to measure atmospheric moisture levels in the 5-10 ppm range, which is crucial for understanding contrail formation, and existing advanced sensors are complex and expensive for airborne applications.
Innovation Solution
An atmospheric moisture measuring system using an aircraft air bleed system, comprising a moisture collector, heater, and timer system, which selectively activates the heater to evaporate moisture for detection by a moisture sensor, providing a concentration factor of approximately 100X with low-cost sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If advanced optical based humidity sensing technologies are used to reach 5-10 ppm precision, then measurement precision is improved, but device complexity and cost increase significantly
Solution Approach 1:
The system divides the measurement process into two stages: (1) a collection phase where moisture is accumulated in a trap over time, and (2) a measurement phase where the accumulated moisture is concentrated and measured. This segmentation allows the use of simpler sensors by pre-concentrating the moisture to levels detectable by low-cost sensors.
Solution Approach 2:
The system performs preliminary action by collecting and concentrating moisture before measurement. The moisture collection trap accumulates atmospheric moisture over an extended period, pre-concentrating it to levels that can be detected by inexpensive sensors, thereby avoiding the need for complex high-precision sensors.
2Measurement precision
If advanced optical based humidity sensing technologies are used to reach 5-10 ppm precision, then measurement precision is improved, but cost increases significantly
Solution Approach 1:
The measurement system is segmented into a collection component and a measurement component. The collection trap performs the expensive function of concentration, while the measurement component can use inexpensive sensors, thereby reducing overall system cost while maintaining high precision.
Solution Approach 2:
The moisture collection trap acts as an intermediary between the atmosphere and the sensor. It concentrates the dilute atmospheric moisture into a form that can be measured by low-cost sensors, serving as a mediator that bridges the gap between low-concentration atmospheric moisture and the detection capabilities of inexpensive sensors.
3Device complexity
If capacitive MEMS sensors are used, then device complexity is reduced, but measurement precision deteriorates due to insufficient sensitivity
Solution Approach 1:
The system performs preliminary concentration of moisture using the collection trap before the measurement is taken. This preliminary action increases the moisture concentration to levels that simple MEMS sensors can detect, thereby maintaining device simplicity while achieving the required measurement precision.
Solution Approach 2:
The collection trap serves as an intermediary that enhances the signal for simple sensors. By concentrating the dilute atmospheric moisture into a more concentrated form, it enables inexpensive MEMS sensors to achieve the precision that would otherwise require complex optical sensors.
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
The system achieves precise atmospheric moisture measurement in the 5-10 ppm range using low-cost sensors, improving contrail prediction and reducing aircraft emissions by optimizing flight paths.
Implementation Method 1
Each heater is configured to heat an associated moisture collector to generate the evaporated moisture received by an associated moisture sensor
Data Source
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AI summary
An atmospheric moisture measuring system is provided that includes at least one moisture collector, at least one moisture sensor, at least one heater and at least one timer system. The at least one moisture collector is coupled to receive an airflow from a bleed system of a vehicle. Each moisture sensor is coupled to receive evaporated moisture from an associated moisture collector of the at least one moisture collector. Each heater is configured to heat an associated moisture collector to generate the evaporated moisture received by an associated moisture sensor. Each timer system is configured to selectively activate an associated heater.