Flow and heat transfer characteristics of phase change emulsions in a circular tube: Part 2. Turbulent flow

Phase change emulsion (PCE) has recently attracted attention as a thermal media in thermal energy storage systems because it has the advantages of high-density thermal storage and transportability. In the present study, the heat transfer characteristics of a phase change emulsion (PCE) for turbulent flow were experimentally investigated. Wall heat flux, mass fraction of PCM, and Reynolds number were the varied experimental parameters. For turbulent flow, it was found that the Nusselt number of the PCE with melting dispersed PCM particles was higher than that of a single-phase fluid. The Nusselt number varied along the flow direction and the maximum Nusselt number was about 2.2 times higher than that of a single-phase fluid. Furthermore, the increasing ratio depended on the wall heat flux and the latent heat held by the PCE. However, the Reynolds number had little influence on the ratio. A modified Stefan number was defined and an equation that represents the melting heat transfer characteristics of a PCE in a turbulent flow region was derived using the modified Stefan number, Reynolds number, and Prandtl number.