Nucleation promoting effect of fat shell on phase change material particles dispersed in an emulsion for thermal energy storage medium

Abstract

Abstract Phase change material emulsions (PCMEs) can be prepared in which a paraffin type phase change material (PCM) is dispersed as small particles in water by the action of a surfactant. Using the latent heat of PCM particles in the PCME, the PCME can be used as an efficient heat storage and transport medium. PCM particles in the PCME are stabilized by the action of a surfactant, but they irreversibly coalesce over time. When the PCM particles change from liquid to solid, they can also show large supercooling because of their small size. These problems must be overcome for PCMEs to be used as efficient thermal media. In this study, PCM particles are emulsified with a high-melting-point fat containing a hydrophobic group consisting of single bonds, in an attempt to overcome these problems. The high-melting-point fat exists as fat shell around PCM. The stability and supercooling characteristics of the PCM particles are investigated. The amount of fat affects the stability of the emulsion. Adding 1.0–5.0 wt% fat is the optimum amount for stabilizing the emulsion. The fat promotes the nucleation of the PCM particles, and the degree of supercooling is suppressed to 3.0 K. Furthermore, the latent heat retained by the emulsion emulsified with fat is about 10% larger than the value obtained by multiplying the latent heat of the PCM by the content of the PCM. These features indicate that PCME prepared with high-melting point fat is suitable as high performance thermal energy storage medium for thermal energy storage and transport system.