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T. Glatzl, R. Beigelbeck, S. Cerimovic, H. Steiner, F. Wenig, T. Sauter, A. Treytl, F. Keplinger:
"A Thermal Flow Sensor Based on Printed Circuit";
Sensors, 19 (2019), 5; 1 pages.

We present a thermal flow sensor designed for measuring air as well as water flow velocities
in heating, ventilation, and air conditioning (HVAC) systems. The sensor is designed to integrate the
flow along the entire diameter of the pipe also quantifying the volume flow rate of the streaming fluid
where the calorimetric principle in constant temperature operation is utilized as a readout method.
In the constant temperature mode, a controller keeps a specific excess temperature between sensing
elements at a constant level resulting in a flow dependent heater voltage. To achieve cost-effective
sensors, the fabrication of the transducer is fully based on printed circuit board technology allowing
low-cost mass production with different form factors. In addition, 2D-FEM simulations were carried
out in order to predict the sensor characteristic of envisaged setups. The simulation enables a fast and
easy way to evaluate the sensor´s behaviour in different fluids. The results of the FEM simulations
are compared to measurements in real environments, proving the credibility of the model.

thermal flow sensor; calorimetric; CT mode; printed circuit board; HVAC systems

http://dx.doi.org/10.3390/s19051065