Heat transfer characteristics in turbulent flow and flow patterns of PCM slurry using super-hydrophobic gel particles

Abstract

An experimental study on the characteristics of heat transfer in turbulent flow and the flow patterns of an organic phase change marerial (PCM) slurry was conducted to investigate the latent heat transportation. As a PCM slurry, the particles of the super-hydrophobic marshmallow-like gel, adsorbing hexadecane on their surface, were dispersed in sodium carboxymethyl cellulose (CMC) solution. Hexadecane is a PCM with a melting point of 17.5 °C, and latent heat of 226.5 kJ·kg−1. For the heat transfer measurement, a double-tube heat exchanger with an inner tube with an inner diameter of 8 mm was used. The results demonstrated that the heat transfer of the marshmallow-like slurry with hexadecane was 1.5 times higher than that of Newtonian fluids. From the pressure drop in the test section, the heat transport efficiency was calculated, which was also higher than that of Newtonian fluids. Furthermore, the flow patterns of the marshmallow-like gel slurries were investigated by varying the CMC concentration and flow velocity. From the results, four patterns of particle dispersion in the flow were observed. The most dispersed flow pattern was observed with all CMC concentrations when the flow velocity was sufficiently high. Based on these results, it was concluded that heat transportation by the marshmallow-like gel slurry is promising.