EXPERIMENTAL TESTING AND MODELING OF GRANULAR HEAT TRANSFER AROUND OBSTRUCTIONS

Abstract

A visual method for predicting the heat transfer coefficient associated with flowing granular material around an obstruction without the need for testing at elevated tem- peratures was developed. The developed model was used to predict the heat transfer performance of two novel obstruction geometries that prevented the formation of stagna- tion and void zones which was shown to increase the predicted heat transfer coefficient by up to 40%. In addition, experimental testing was completed on several geometries, both obstructed and unobstructed. The method developed model was validated against the experimental testing at elevated temperatures and showed moderate predictive power. The results of the experimental testing at elevated temperatures were input into a one- dimensional particle heat exchanger model which analyzed how changes in mass flux and heat transfer coefficient effected the overall size of a particle heat exchanger. The novel obstructions showed promise of increasing the power density of a particle heat exchanger by up to 1.5x but due to large experimental uncertainty, no strong conclusions were made.