Abstract
A new method to measure local heat flux distribution from capsule surface in packed bed of ice thermal storage capsule using magnetic resonance imaging (MRI) was developed to investigate nonuniform heat transfer phenomena in porous media. In this method, local heat flux distribution from a capsule was calculated from freezing rate of water in the capsule cooled by brine below 0°C in a time interval. The mean heat flux of single capsule surface under uniform flow obtained by this method agrees with one by the conventional method. By applying this method to packed bed, heat flux distributions on capsule surfaces in packed bed were measured, and axial velocity distributions of brine through packed bed were obtained by the phase method in MRI techniques. Based on these results, it was found that heat exchange effectiveness of brine through channel was lower than that through the region where channel flow was not induced. In addition, time-variations of overall heat transfer coefficient of packed bed at different flow rates were obtained.
