Development of the Multi-point Thermal Gas-mass Flowmeter

A multi-point thermal gas-mass flowrate measurement method is designed. The meter has four hot-film sensoring elements. Four often-used arrangements of the sensing elements are studied and the optimal disposition is selected. The temperature characteristics of the hot-film probe are analyzed under different surrounding temperature conditions and different currents passing through the hot-film probe. The relationship between the resistance of the probe and the ambient temperature is obtained. The automatic compensation method is applied to the temperature compensation. The curve fitting method is employed to calibrate the multi-point thermal gas-mass flowmeter. The gas flowrate is measured according to the output of the sensing elements array through curve fitting. The test results show that the multi-point method is satisfactory