Investigating Thermal Stratification in a Hot Water Storage Tank during Charging Mode

Abstract

Hot water storage (HWS) tanks are the sensible energy storage systems used to accumulate thermal energy in water for later use. In the present study, a vertical cylindrical HWS tank equipped with three heat exchanger coils to harness energy from different energy sources is numerically investigated. A 2-D axisymmetric model is developed in ANSYS Fluent to simulate and study the dynamic behavior of the HWS tank during charging. Three operating cases with one heating source functioning at a time are analyzed to determine the degree of thermal stratification. Transient temperature and velocity distributions are discussed for the qualitative and quantitative analysis of mixing and stratification in each case. The results assist the design engineers and end-users in determining effective modes of HWS operation with maximum stratification, thus, system efficiency.