A New Technique to Determine Convection Coefficients With Flow Through Particle Beds

Abstract

Abstract A new method for determining the heat transfer coefficient for air flowing steadily through beds of particles is presented. In this technique, a step change in the inlet air temperature is applied to a small test bed and temperature distributions in the bed and at the air outlet are sampled over a short time period. The convective heat transfer coefficient is determined using data from the convective heat transfer process in the bed where the analysis includes the partial differential equation that describes the transient energy storage in the particles within the bed. The analysis is performed for a short time duration when the temperature distribution in the particle bed is almost linear along the axis of the bed. This time period permits the most accurate determination of the heat transfer coefficient using the data. Using beds of spherical particles a new correlation is developed for the Nusselt number versus the Reynolds number (5<Redh<280) and includes the uncertainty bounds. This new correlation compares well with correlations developed by some other researchers for similar spherical particle beds.