固定床内传热参数的估计与分析

本文在系统地考察了各种因素对床层径向有效导热系数和壁传热系数影响的实验研究与计算机模拟的基础上,对文献中发表的固定床内传热参数估值离散的原因进行了分析。结果表明,Bi取值在5.0左右时,对床层出口温度比较敏感,是造成h_(?)估值离散的重要原因之一。床层填充的随机性影响床层温度分布,低床层、低Re_p条件下估计参数误差要大。d_(?)取值范围不同,壁冷却和壁加热条件下估计出的参数均会不同。

ESTIMATION AND ANALYSIS OF HEAT TRANSFER PARAMETERS IN FIXED BED

The causes of the discrepancy of the estimated heat transfer parameters in fixed bed are discussed on the basis of investigations on the effects of various factors on the radial efficient heat conduction coefficients and the wall heat transfer coefficients. The results show that one of the important reasons for that the estimation of the wall heat transfer coefficient scatter widely is that the outlet temperature of the packed bed is more sensitive to Biot number when Bi is about 5. The experimental results indicate that the irregularity of bed packing will affect the bed temperature distribution, and the estimation error will be greater when the packed bed is lower and Rep number is small. The parameters are different at various d_p range and the wall which is either heated or cooled.