Flow rate measurement system using thermal air flow sensor

An intelligent digital flow rate measurement system is presented to replace the conventional hot-wire flow rate measurement system, which uses original analog feedback circuit. In this paper, the conventional Wheatstone bridge measurement circuit is replaced by a new Pulse Width Modulation (PWM) circuit for the purpose of energy conservation. The system employs a PIC18F452 chip to interface a thermal flow measurement system to measure the flow rate. And a signal prediction algorithm is introduced to speed up the measurement. It has been proved that the performance of the intelligent digital flow rate measurement system has been increased compared with conventional flow rate measurement system based on the thermal air flow sensor.