基于双测试原理的热式质量流量计的设计

Thermal Mass Flowmeter Based on Double Test Principle

中文关键词:  流量计  热式质量  恒温差法  恒功率法  宽量程

英文关键词:flowmeter  thermal mass  constant temperature difference method  constant power consumption method  wide range

中文摘要:

      传统恒温差式热式流量计受到测量电路本身限制，最大加热电流受限，因此测量范围有限。设计研制了一种结合恒温差法和恒功率法的热式质量流量计。该流量计是基于托马斯理论，对功耗和温差进行采集，从而测得流量。相比于传统恒温差式质量流量计，该流量计在低流速时通过对桥式电路电压差采集，以控制数字电位器改变输入总电压，从而实现探头间温度差恒定，测量功耗测得流量；而在高流速时，通过数字电位器控制功率恒定，探测电路各个参数，从而计算得到温度差，测得流量。该流量计针对内径80 mm的管道，测量范围为0~1500 m³/h，量程约为传统恒温差式流量计的1.3倍，相对误差小于1%，满足实际使用需求。相比于传统恒功率式流量计，该流量计测低流速时精度更高。

英文摘要:

      The traditional thermostatic differential thermal flowmeter is limited by the measuring circuit itself and the maximum heating current,so the measuring range is limited.A kind of thermal mass flowmeter combined with constant temperature difference method and constant power method is designed and developed.The flowmeter is based on Thomas theory to collect the power consumption and temperature difference,so as to measure the flow.Compared with the traditional constant temperature difference mass flowmeter,the flowmeter can control the digital potentiometer to change the total input voltage by collecting the voltage difference of the bridge circuit at low flow rate,so as to realize the constant temperature difference between probes,measure the power consumption and measure the flow rate.At the high flow rate,the digital potentiometer is used to control the constant power and detect the various parameters of the circuit,so as to calculate the temperature difference and measure the flow rate.The measuring range of the flowmeter is 0~1500 m³/h for the pipeline with inner diameter of 80 mm.The measuring range is about 1.3 times of the traditional constant temperature difference flowmeter,and the relative error is less than 1%,which can meet the actual needs.Compared with the traditional constant power flowmeter,the flowmeter has higher accuracy when measuring low flow rate.