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HEAT TRANSFER IN PACKED BEDS-TEMPERATURE DISTRIBUTION

CHU PAO-LIN, WANG HSUEH-SUNG (Institute of Petroleum, Academia Sinica)   

  • Online:1957-06-25 Published:1957-06-25

填充床层热之传导——床层之温度分布

朱葆琳,王学松   

  1. 中国科学院石油研究所 ,中国科学院石油研究所

Abstract: An experimental investigation was made of temperature gradients in air streams being cooled while flowing through a cylinder of diameter 81 mm packed with high thermal conductivity (iron and copper) and low thermal conductivity solids of spheres, cylinders and Raschig rings. From the measured temperature gradients at various bed depths and radial posi-tions, and for the different particle sizes and flow rates, the effective thermal conductivity Ke, and the heat transfer coefficient of the wall hw, were determined by the integral, graphical and the direct-current electric analog methods. In the experimental range: Dp/Dt varied from 0.074 to 0.254 for the low thermal conductivity solids, from 0.12 to 0.2 for the high thermal con-ductivity solids; L/Dt varied from 5 to 15; Re number varied from 130 to 1400, corresponding to a linear velocity of 0.5- 1.6 meters per minute. If the arithmatic mean of the inlet and outlet temperatures was used as a qualitative temperature in the calculation, the effective thermal conductivity Ke, and heat transfer coefficient of the wall hw, could be correlated in the following equations: For low thermal conductivity solids: For high thermal conductivity solids: In case of cylinders and Raschig rings, the Dp in the above equations should be substituted by Dp and the constants 0.182 and 0.3 in the KG for- mulas should be changed to 0.22 and 0.38 correspondingly. A direct-current electric analog method was used in this paper, by which the temperature profiles of the bed could be calculated very con-veniently.

摘要: 作者用低导热系数(包括玻璃、磁)的球体、圆柱体、环柱体与高导热系数(包括铜、铁的球体,圆柱体为填充物,以空气为传热介质,使其在管径为81毫米之填充床层内冷却,改变流体流量,床层高度及填充物大小,通过试验测出在不同的条件下床层的径向温度分布,并应用积分法、直流电模拟计算法及图解法求得床层的有效导热系数及管壁薄膜传热系数.在试验范围:低导热系数填充物D_P/D_t自0.074—0.254;高导热系数填充物D_p/D_t自0.12—0.2,L/D_t自5—15,Re汇数自130—1400,即直线速度自0.5—1.6公尺/分,若以床层进出口平均温度之数学平均值为定性温度,则床层之有效导热系数及管壁薄膜传热系数可分别归纳于下式:低导热系数填充物:K_e=0.182(D_t/D_p)~(0.45)Re~(0.75),h_w=65e~(-4)(D_p/D_t)(K/D_t)((D_t/L))~(0.2)Re~(0.4)高导热系数填充物:K_e=0.3k(D_t/D_p)~(0.6)Re~(0.72),h_w=5.1(K/D_t)(D_t/D_p)~(0.8)(D_t/L)~(0.1)Re~(0.46)填充物形状对K_e及h_w的影响,仅需将D_p用 D’_p代替,同时把K_e式中之常数0182及03各改为0.22及0.38即可.直流电模拟计算法系利用电压表示温度,电阻表示传热阻力,电流表示热的流动,是简单的模拟计算机的一种,它在近代工程上的应用日渐广泛,有了传热数据应用它来求床层的温度分布异常方便.