Attempts have been made to study an ice slurry generation system where two immiscible liquids, water and a coolant, are used to produce ice slurry by direct contact heat transfer. A mathematical model has been developed to evaluate the heat transfer phenomena between the coolant drops and the water in the ice slurry generation system. In this process, all the important variables that affect the direct contact heat transfer between these two fluids were incorporated into the simulation model to evaluate thermal performance of the system. Experiments were performed on an ice slurry generator using water and an immiscible liquid coolant, Fluroinert FC-84. The coolant at about −10°C to −15°C was delivered to the top of the ice slurry generator containing water and collected from the bottom for recirculation. The measured temperature profiles of water in the ice slurry generator for different coolant flow rates (8 lit/min to 12 lit/min) showed a good agreement with those temperature profiles obtained from the simulation model. These results validated the simulation model developed for the ice slurry generator. The analysis showed that during sensible cooling, the estimated heat transfer coefficients between water and the coolant were in the range of 3.0 to 6.5 kW/m2 for coolant flow rates varying from 8 lit/min to 12 lit/min. Higher coolant flow rates also enhanced the ice formation process due to the increased heat transfer rate. In addition, it was also observed that the ice production increased significantly when the nozzle was placed at the bottom of the ice slurry generator.
Gas Hydrate Cold Storage Using Direct-Contact Heat Transfer of Liquid-Vapor Phase Change and Natural Circulation of Refrigerant in Closed Vessel.