Transient heat transfer modeling of an ice on coil thermal storage system with boiling heat transfer process of a refrigerant for diary preservation application

Abstract

A numerical investigation has been made on transient heat transfer modeling of an ice on coil type thermal storage system based on a double u-tube borehole thermal network concept. Four distinct concentric tube has been considered inside a milk storage tank, where a refrigerant streams inside the inner tubes of the concentric tubes, while an ice will be formed at outer tube to store a cold energy. The complex boiling heat transfer of the cooling refrigerant has been performed by utilizing a set of empirical equations with iterative process. The cooling refrigerant cools down the milk inside the storage tank as well as it freezes the water inside the outer concentric tubes at the same time. In this analysis, temperature profile of the working fluids along the vertical position has been determined for specified times. Also temperature history of the working fluids has been determined at specific position of the thermal storage system. Finally the temperature variation of the refrigerant at the exit of the tubes is determined, and it is found that for the first 400 s the refrigerant leaves the exit of the tubes as superheated state, while the refrigerant exits the tubes as saturated state afterwards.