COMPARATIVE STUDIES ON HEAT TRANSFER AND FLUID FLOW IN CORED BRICK AND PEBBLE BED HEATERS

Gokul. M, Krishnan. A. S

Abstract: The article reports on comparison of transient heat transfer and fluid flow in two different sensible heat storage devices using Computational Fluid Dynamics. The candidate heat storage devices considered were cored brick and pebble bed and air was taken to be the working fluid. Same geometrical, material, porosity and boundary conditions, have been used for both the cored brick and pebble bed heaters, to compare the axial temperature history and pressure drop. The heat storage system comprises alumina, either in form of pebbles of diameter 6.5 mm, packed to a length of 0.455m in a 43mm diameter pipe, or cored brick of 43mm diameter and same length with through holes to have the same porosity (0.48) as that of the former. The conditions at inlet, outlet and lateral surface too have been taken to be same for both the systems. The fluid flow was considered to be incompressible with k-epsilon model to predict turbulence, and the thermo-physical properties of fluid and solid were assumed to remain constant. Simulations carried out for an inlet temperature of 465 K for velocities ranging from 2m/s to 5 m/s revealed that pressure drop in pebble bed to be considerably higher than those in cored brick, while the temperature history exhibited mixed trends.

Keywords: Cored Brick, Pebble Bed and Porosity

DOI: https://doi.org/10.15623/ijret.2015.0401065