摘要
本文通过建立二维非稳态导热的数学模型 ,模拟了瞬态热流计测量低温金属表面与高温流体换热时影响测量精度的五种主要因素。计算得出 ,由于热流计测头的出现 ,对流换热系数的变化会给热流测量带来较大误差。其次 ,热流计测头自身因素的变化也会给测量带来误差。测头越薄 ,测量误差越小 ,稳定越迅速 ;测头边长越长 ,测量误差越小。但当被测物表面积较大时 ,测头边长存在一个最优值 ,能达到测量精度与测头尺寸的最佳结合 ,这个值约为 2 0mm ;测头与被测物粘贴越紧密 ,误差越小 ,稳定越迅速 ;被测物导热系数越小 ,则测量误差越小。
A two-dimensional unsteady heat conduction mathematical model is presented.Through this model,factors that can influence measurement precision using surface-mounted transient heat flux gage on heat flux measurement exchanged between low temperature metal board and high temperature gases are simulated.Conclusions can be drawn that changes of the convective heat transfer coefficients can bring error because of the appearance of heat flux sensors.Furthermore,the changes of the heat flux gages' characteristics can bring measurement error too.The thinner heat flux sensor is,the bigger sensor's dimension is,the tighter the sensor be pasted and the smaller thermal conductivity of the measured material is,the higher measurement precision could be and the shorter time of steady could be.Through calculation,there is an optimum length of the dimension,which is nearly 20mm square.Results of the calculation can give a reference to manufacture and applications of heat flux gages.
出处
《节能》
2005年第2期3-7,共5页
Energy Conservation
基金
科技部"九五"重点基础研究项目"高效节能的关键科学问题"资助 (G2 0 0 0 0 2 63 )
