针对热式流量计的温度漂移问题,提出了一种恒定功率模式下的热式流量计结构,并对其数字校准方法进行了研究.与传统热式流量计相比,增加了环境探头,该探头内嵌于流体管道壁.各传感器之间采用隔热措施,利用环境探头和感温探头测量得到的电压信号进行实时数字校准.采用音速喷嘴法燃气表检验装置对流量计进行检测.检测结果显示:流量在0.016~0.25 m3/h范围内误差率小于0.5%,流量在0.25~6 m3/h范围内误差率小于1.0%,温度漂移现象有效改善.
To solve the problem of temperature drift of thermal flowmeter,the structure of thermal flowmeter in constant power mode was proposed,and its digital calibration method was studied.Compared with conventional thermal flowmeters,an environ-mental probe was added,which was embedded in the fluid pipe wall.The sensors were insulated from each other.The voltage sig-nal measured by the environmental probe and the temperature sensor was calibrated digitally in real time.The flowmeter was test-ed by the sonic nozzle gas meter inspection device.The test results show that the error rate is controlled within 0.5%in the flow range of 0.016~0.25 m3/h,and the error rate is controlled within 1.0%in the flow range of 0.25~6 m3/h,and the temperature drift phenomenon is effectively improved.