Paper Title
The Stability of PCM-in-Water Emulsions as Working Fluid for Thermal Energy Storage Applications

Abstract
Phase change material (PCM) in water emulsion is a multi-phase fluid mixture, a potential working fluid with the advantages of high fluidity,thermal conductivity, and thermal capacity. However, instability due to aggregation and precipitation is a critical issue for their large-scale applications. This work was to evaluate the various factors affecting the stability of PCM-water emulsions prepared with n-hexadecane including theemulsion formulation and process conditions, the interfacial film properties,the droplet size and distribution, and the liquid viscosity. The nano-emulsion with small droplet size and uniform distribution exhibited ahigh stability. The stability was further enhanced with the addition of solid nano-particlesas both nucleating agent and stabilizer. In addition, the selection and concentration of emulsifiershad a significant effect on the viscosity of continuous phase.Eventually, a novel and stable paraffin-based PCM nano-emulsion with a moderate viscosity was developed for potential application in thermal energy storage systems. Keywords - PCM emulsion; PCM nano-emulsion; Nano-particles; Stability; Viscosity; Supercooling.