HEAT TRANSFER TO FLOWING GAS - SOLIDS MIXTURES IN A VERTICAL CIRCULAR DUCT

摘要

The problem of heat transfer to an air stream laden with solid spherical particles flowing up a vertical tube with constant heat flux was examined analytically and experimentally. Two different particle sizes were used, 30 microns and 200 microns in diameter. The air rate was held constant at Reynolds number = 13,500 and 27,400 while solids were added up to gravimetric ratios of seven.nThe analytical treatment parallels the solution for single-phase flow. An approximate solution is obtained when it is assumed that the difference in the temperature of the two phases is small, and that the radial temperature profiles of the two phases in the fully developed region are similar. Nusselt numbers are based on the local tube wall and bulk mean mixture temperatures. Qualitative agreement with the experimental results is obtained.