INVESTIGATION OF HEAT TRANSFER AND RHEOLOGY OF A PHASE CHANGE MATERIAL EMULSION WITH A HIGH CONCENTRATION IN SURFACTANT

摘要

The thermohydraulic characteristics of a secondary refrigerant consisting of a phase change material emulsion(PCME) were investigated. This PCME is a paraffin-in-water emulsion containing 30 wt.% of paraffin and arelatively high concentration of surfactant (5 wt.%). A fully instrumented 1 m long rectangular channel wasused to conduct heat transfer experiments. Heat transfer coefficients during cooling inside the rectangularchannel were determined. Furthermore, a specific test rig was used to perform experiments on the rheologicalbehavior. Tests were carried out using a pipe viscosimeter at different temperatures for laminar flow. Thestability of the emulsion was examined under thermal-mechanical loads. The experiments revealed a shearthinning behavior. Phase change of the PCM droplets was confirmed for high Reynolds number, while for lowReynolds number, the phase change remains uncertain. In addition, results showed a large supercooling degreeand a very good stability but viscosity was found to be quite high.