Preparation and characterization of phase change microcapsule emulsion for thermal energy storage and transportation

Abstract

A method of water phase separation is adopted to prepare phase change emulsion samples, and a self-designed multi-stage gravity flow heat exchange system is then used to measure fluid flow and heat transfer performance. Under the conditions of different flow velocities and initial temperatures, flow and heat transfer performance of the emulsion is tested. Results show that phase change capsule in emulsion sample has a uniform core-shell structure, and core material is completely encapsulated by a uniform thickness of the shell. Thermal conductivity of emulsion is generally higher than 0.53 W·m-1·K-1, indicating that the emulsion itself has excellent thermal conductivity. The maximum encapsulation ratio and encapsulation efficiency of the capsule reached 80.7% and 80.8%, respectively, and thermal decomposition temperature of the capsule reached 300 °C, which indicated that the synthesized emulsion has potential excellent heat storage and release performance. When flow velocities are 0.35 m·s−1 and 0.65 m·s−1, heat transfer coefficients of phase change capsule emulsion are 1231.5 W·m-2·K-1 and 2020.5 W·m-2·K-1, respectively, which are more than 55% of the heat transfer coefficient of deionized water in same flow state.