An Experiment of Heat Transfer in Packed Bed of Grain

Abstract

This invastigation was carried out to estimate the heat transfer coefficient, h_P, in packed bed of grain.
In this analysis, Babcock's approximate solution was adopted to calculate the vale of h_P.
The following conculsion are drawn from the results of this investigation.
1. The effect of air velocity on the value of h_P was arrenged as the relation between Nu and Re, and the following equations were obtained;
glass beads: Nu=0.155Pe^0.92 (25≤Re≤170)
rough rice: Nu=0.0198Re^1.02 (20≤Re≤95)
barley: Nu=0.477x10^-3Re^1.99 (34≤Re≤94)
2. The predicted values of temperature at the each bed length from the approximate solution good agree with the measured values.
3. The values of h_P in packed bed were lowes than those of single kernel and in packed bed, temperature distribution in particle is negligible over the range of this investigation because the values of Biot No. were smaller than 0.1,
4. Air temperature and bed length effect on the value of h_P. In this investgation, however, those effects cannot be analyzed quantitatively. The new model, contains heat loss through the apparatus wall, fluid dispersion and overall heat transfer of particle, should be used to analyze those effects.