Abstract
A simulation model for thermal energy storage (TES) tank of the direct external ice-on-coil type is presented. Ice is formed on the outer surface of unfinned copper tubes evaporator coil, where heat is transferred to R-22 refrigerant. The conservation equations, in finite difference form, are presented and solved for the charging mode. The model predicts the local thickness of ice as well as the cumulative inventory over a specified charging period. An ice energy storage tank of 3150 kW capacity was studied as a standard module; the ice thickness showed strong dependency on the refrigerant side heat transfer coefficient (h(ref)). The results showed that for ready built TES increasing the refrigerant flow rate beyond the full load rate did not enhance ice formation because of the drop in the refrigerant quality and the non-appreciable increase in (h(ref)). On the other hand operation below the capacity was affected by formation of superheated vapor zone of low h(ref).