高Gr数水平旋转圆筒多孔介质表面对流质变换的研究

EXPERIMENTAL STUDY FOR CONVECTIVE MASS TRANSFER OF THE POROUS MEDIUM WALL OF HORIZONTAL ROTATING CYLINDER WITH LARGE Gr

一、前言 水平旋转圆筒表面的蒸发和午燥过程常见予化工、轻纺、建材等工业部门。针对不同的目的,一些文献曾研究了小直径垂直旋转圆筒的对流质交换,但未见有关水平旋转圆筒的研究报道,更未涉及高Gr数的传质问题;再者,常见的对流质交换往往伴随着热交换。有鉴于此,本文通过水在多孔介质表面的蒸发过程,测量它的局部及平均对流质交换系数,研究了高Gr数旋转圆筒表面紊流质交换时准则关联式及临界参数表达式。局部对流质交换系数hD及平均对流质交换系。h_D即:

The average convectiye mass transfer rate is measured by the method of calorimeter made from silicon rubber plate. For checking the average Sh and detecting the variations of local Sh with the rotational speed, the concentration boundary layers are measured by a probe consisted of a fine dry and a wet bulb thermocouples. The relationships of the convective mass transfer and the expression of the critical Reynolds number are proposed. The paper also analyzes the analogue for the heat and mass trans er of horizontal rotating cylinder.