Feasibility Testing of a Thermal Dispersion Flowmeter with External Signal Conditioning for Health Monitoring of Liquid and Gas flows



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2023 International Conference on Environmental Systems


Spacecraft environmental and thermal control systems have liquid and air loops that include instrumentation to monitor the health of the prime mover (pump or fan). This instrumentation often includes temperature of the fluid flow, pressure rise of the pump or fan, and/or flow rate. In terrestrial and aircraft applications, there are many flowmeter technologies available, all requiring signal conditioning electronics to provide the required power or electrical signal to the sensing element and to convert the sensor output signal into a useable format, such as a linear analog or a digital output. The high radiation environment and stringent electronic part quality requirements typical of long life and/or mission critical space applications are a barrier for entry for many commercially available sensors with built-in signal conditioning electronics. Furthermore, the high non-recurring cost coupled with extremely low production quantities make a challenging business case for development and certification of new space hardened electronics, resulting in a very limited supply base and heavy reliance on re-use of legacy designs.

Thermal dispersion flowmeters are an interesting technology for space applications because the sensing element has very simple electrical interfaces, consisting only of a heater and a pair of resistance temperature detectors (RTDs). These interfaces are readily available in many spacecraft and subsystem controllers, offering the opportunity to eliminate the signal conditioning electronics in the sensor and instead allocate the signal conditioning function to the space hardened subsystem controller. A proof-of-concept test was conducted at Collins Aerospace to evaluate the feasibility of interfacing a thermal dispersion flowmeter directly with a space hardened fan/pump motor controller. The flowmeter was tested in Water and Air at flow rates relevant to current and future environmental and thermal control systems. This paper describes the concept and theory of operation, presents the test results, and provides recommendations for future implementation.


Diego Mugurusa, Collins Aerospace, USA
Nicholas Van Derzee, Collins Aerospace, USA
James Davis, Collins Aerospace, USA
ICES205: Advanced Life Support Sensor and Control Technology
The 52nd International Conference on Environmental Systems was held in Calgary, Canada, on 16 July 2023 through 20 July 2023.


Flowmeter, Thermal Dispersion, Instrumentation, Flow Instrumentation, Sensor, Flow Sensor