Experimental Investigation on Laminar Forced Convection Heat Transfer Enhancement of Microencapsulated Phase Change Suspension with Constant Heat Flux

摘要

By contrast with the conventional heat transfer fluid (water), the microencapsulated phase change material (MPCM) suspension, with a small temperature difference between storing and releasing heat, is of much larger apparent specific heat and much higher thermal energy storage capacity. Due to those, it has been suggested to serve as a dualfunctional medium for thermal energy transport and/or storage. The heat transfer characteristics of a kind of MPCM suspension, formed by microencapsulating industrial-grade 1- bromohexadecane (C16H33Br) as phase change material, were experimentally studied. The results show that: 1) the heat transfer enhancement ratio is larger as the mass fraction is higher, however, the difference between the heat transfer enhancement ratios of the three samples in the experiment is not remarkable; 2) the heat transfer enhancement ratio can be up to 1.37 times of that of water, and the dimensionless wall temperature w,x can reduce from 0.26 to 0.10 (10.0wt%); 3) at the same mean velocity um, heating power qw and the inlet temperature Tbi, the wall surface temperature can reduce 3.9 and the bulk temperature can reduce 2.7 (10.0wt%); 4) the pressure drop increases slightly when MPCM particles are used at lower mean velocity (um 0.8 m·s-1). Moreover, the pressure drop reduces at higher mean velocity because of hampering the fluid turbulence.