ASHRAE AB-10-021

Abstract

<strong>INTRODUCTION</strong> <br>Increasing intensity and performance of heat transfer in heat exchanger equipment is one of the most pressing issues in the world today. Information technology applications as well as data centers have seen a growth in processing speed which has resulted in higher dissipation of heat. In HVAC applications, increasing the heat transfer rate can lead to reduction of the required flow rate of heat transfer fluids which consequently saves energy through decreased pumping power. <br>The introduction of Microencapsulated Phase Change Material (MPCM) in form of slurries as heat transfer fluids has been well accepted among researchers. MPCM slurries consist of a base fluid such as water that contains a relatively low mass fraction of microcapsule filled with phase change material such as octadecane or paraffin wax. The microcapsules vary in size between 1 to 10 &#956;m to avoid breakage during continuous pumping. High effective heat capacity is expected when the phase change undergoes phase change while is flowing under constant heat flux or temperature conditions. Several experimental as well as numerical studies have been published recently (Ravi et al. 2009, Alkan et al. 2009, Alvarado et al. 2007, Chen et al. 2008, Goel et al. 1994, Bai and Lu 2003, Yamagishi et al. 1999 and Mulligan et al. 1996). Improvement in heat transfer coefficient as much as 3 times has been reported.