Enhancement of melting heat transfer of ice slurries by an injection flow in a rectangular cross sectional horizontal duct

Ice slurries are now commonly used as cold thermal storage materials, and have the potential to be applied to other engineering fields such as quenching metals to control properties, emergency cooling systems, and preservation of food and biomaterials at low temperatures. Although ice slurries have been widely utilized because of their high thermal storage densities, previous studies have revealed that the latent heat of ice particles is not completely released on melting because of insufficient contact between the ice particles and a heated surface. In this study, an injection flow that was bifurcated from the main flow of an ice slurry was employed to promote melting heat transfer of ice particles on a horizontal heated surface. The effects of injection angle and injection flow rate on local heat transfer coefficients and heat transfer coefficient ratios were determined experimentally. The results show that from two to three times higher heat transfer coefficients can be obtained by using large injection flow rates and injection angles. However, low injection angles improved the utilization rate of the latent heat of ice near the injection point by approximately a factor of two compared to that without injection. •Melting of ice slurries were enhanced by the injection under constant total flow rate.•Contribution of ice particles and their latent heat to heat transfer was investigated.•Effect of velocity ratio of injection to that of main flow was examined.•Effect of the angle of injection flow to the main flow was also examined.•Appropriate conditions for the use of latent heat of ice and heat transfer did not coincide.