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中南大学学报(自然科学版)

Journal of Central South University

第51卷    第2期    总第306期    2020年2月

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文章编号:1672-7207(2020)02-0367-10
污染物对热膜式气体流量传感器精度的影响
袁昌荣,孙中圣,李小宁

(南京理工大学 机械工程学院,江苏 南京,210094)

摘 要: 为了预测污染物对热膜式气体流量传感器精度的影响,研究传感器精度下降机理。首先,分析传感器测量原理,建立传感器电压输出理论数学模型,并基于绕流理论推导气体流经污染物后流速公式;然后,搭建污染物颗粒累积试验平台,进行长时间颗粒累积试验,验证理论模型合理性。研究结果表明:传感器的输出电压与所测气体流速、基底隔膜厚度以及导热系数有关;气体流速下降幅度随污染物高度增加而增大,随污染物与加热电阻中心距离增加而减小;污染物颗粒主要围绕热膜电阻周边呈“U”型分布,热膜电阻上方基本无累积,说明传感器精度下降主要是由热膜电阻前端累积的污染物改变气流流速所致;传感器电压输出理论计算值和试验测量值相吻合,证实了理论模型的合理性。

 

关键词: 热膜式;气体流量传感器;芯片污染;累积厚度;精度

Influence of contamination on accuracy of hot film gas flow sensor
YUAN Changrong, SUN Zhongsheng, LI Xiaoning

School of Mechanical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China

Abstract:To predict the accuracy caused by contamination, the mechanism of sensor accuracy reduction was studied. Firstly, the measurement principle of the sensor was analyzed, and the theoretical voltage output mathematical model was established. The flow rate formula of the gas after passing through the contaminants was also derived based on the flow theory. Then, a test platform for the contaminant accumulation was built and a long-term cumulative test was conducted to verify whether the theoretical model is reasonable. The results show that the voltage output of the sensor is related to the flow rate of the gas, the thickness and the thermal conductivity of the diaphragm on the sensor chip. The decrease amplitude of the flow rate increases with the increase of the contaminant thickness, and decreases with the increase of the distance between the contaminant and the heating resistor center. The contaminants are mainly accumulated around the thermal film resistance and keep U-shaped distribution. There is almost no accumulation above the thermal film resistance, which indicates that the decrease of sensor accuracy is mainly caused by the change of the flow rate due to the contaminants accumulation at the front of the thermal film resistor. The theoretical and experimental values of the sensor voltage output are in good agreement, which confirms the rationality of the theoretical model.

 

Key words: hot film; gas flow sensor; chip contamination; cumulative thickness; accuracy

中南大学学报(自然科学版)
  ISSN 1672-7207
CN 43-1426/N
ZDXZAC
中南大学学报(英文版)
  ISSN 2095-2899
CN 43-1516/TB
JCSTFT
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