Effects of Micro-Particle Diameters and Low Fluid Velocities on Effective Thermal Parameters of Micro-Particle Packed Bed as a Biothermal Reactor

Abstract

The effects of micro-particle diameters (i.e. dp=0.4~1.1mm) and low fluid velocities (v=5ml/min, 3ml/min and 1ml/min) on the heat transfer behavior of water flowing through a micro-particle packed bed as a reactor of thermal biosensor were investigated experimentally under constant wall temperature conditions (i.e. 60°C). The effective thermal parameter is smaller with decreasing the particle diameter and fluid velocities. This is mainly due to the poor thermal conductivity of the filling materials which leads to a larger thermal resistance and hydraulic resistance. As such, it is very important to select a filling material with better thermal conductivity to enhance heat transfer, which is favorable to completely detect the heat created during the enzyme-catalyzed reaction. Comparing the correlations of both this work and those published in the literature, there are considerable discrepancies among them due to different experimental conditions. The two-dimensional heat transfer model that predicts the temperature distributions agree reasonably well with actual measurements except a slight over-prediction in the region close to the inlet.