Fluid Independent Thermal Flow Sensor using Constant-Temperature Anemometry and the 3ω-Method

A new method for the implementation of a fluid-independent thermal flowmeter is presented, combining the 3ω-method and constant temperature anemometry. It is shown that a single calibration with a reference fluid (water in this case) leads to a high accuracy (< 4%). The measurement method was verified for water, isopropanol, and an isopropanol-water mixture. The deviation between measured flow rate value and reference flow rate value is less than 4% with respect to the full scale value. The findings may play a key role for next generation thermal flow meters.