溫度與溼度對氣體感測器之影響研究

Abstract

本文利用二維數值計算，模擬放置於管道中的氣體感測器。考慮氣體感測器加熱造成的自然對流效應、設置方向的不同和管道內空氣流速的快慢，以找到較佳的氣體感測器安裝的方式。並且利用暫態計算，得知達到穩定所需要的時間，和管道中濃度場、流場和溫度場隨時間變化的情形。當感測器置於管道下方時，自然對流效應會在感測器內部形成的渦流，而置於管道上方時則會發生熱空氣的層化現象，各種情形對氣體感測氣的感測能力之利弊值得加以討論。

A gas sensor placing in a tunnel is simulated by a 2-D numerical method in this study. In order to find a better way to place a gas sensor, natural convection caused by heating when operating a gas sensor、different directions of a gas sensor and air flow speed in a tunnel are considered. Transient computes are also done, thus we can estimate the time needed for a gas sensor to be steady, and know something about how humidity、flow field and temperature is changed with time. When a gas sensor is placed under a tunnel, a circulation will form in the sensor due to natural convection, and when a gas sensor is placed above a tunnel, hot air will stagnate in the sensor, thus it is worth while discussing whether these phenomena do well or ill to a gas sensor’s ability.