Abstract
•Droplet solidification process on different material plate surfaces was explored.•Plate surface roughness affects freezing temperature and critical nucleation energy.•The inhibitor concentration affects subcooling and the critical nucleation energy.•The liquid property and the surface roughness dominate heterogeneous nucleation energy.
Ice slurry has been widely used for thermal energy storage system due to its high cold energy storage capacity. To effectively improve the efficiency of ice slurry generator, it is essential to have a deeper understanding about the solidification mechanism on the plate surface of ice generator, which is affected by many factors, such as the roughness of surface and the apparent contact angle. This work studies the impacts of roughness and inhibitor concentration on the freezing temperature, subcooling and the heterogeneous nucleation energy at the surface of aluminum, copper and Teflon plates. Results show that both the roughness and the inhibitor concentration can clearly affect the freezing temperature of water droplet and the heterogeneous nucleation energy. In general, the freezing temperature rises and the subcooling and the heterogeneous nucleation energy drop as the surface roughness increases for all studied materials; and the heterogeneous nucleation energy also increases with the increase of inhibitor concentration. Since the heterogeneous nucleation energy is mainly determined by the substance and the roughness, while not by the surface material, it is important to increase the roughness in order to reduce subcooling and save energy, especially for copper and aluminum.