AN EXPERIMENTAL INVESTIGATION OF THE OVERALL AND INDIVIDUAL HEAT TRANSFER COEFFICIENTS BETWEEN PARTICLE CLOUD AND A HEATED SURFACE

The potential of reactive particles for thermochemical energy storage greatly dependents on the effective energy transport in and out of these particles. This paper uses experimental data on inert particles to provide a useful insight into the heat transfer mechanism between a dilute free falling particle cloud at (γ < 1) and a heated surface. A series of experiments were performed in a tubular furnace to characterize the overall and individual heat transfer coefficients between particles and a heated surface. The particle feed rate and wall temperature were taken as the main variables. It has been found that the addition of particles to a stagnant gas adjacent to the wall significantly changes the characteristic of the combined thermal resistance. The experimental data showed increase in wall convection by 4-6 times compared to natural convection of a single-phase gas. The foregoing findings are directly applicable to evaluate the thermal performance of dilute particle heat exchangers, furnaces, and solar receivers.