Computational modeling of a thermal energy storage tank coupled to a water-cooled household refrigerator

Abstract

In this work, two-dimensional numerical simulations of a thermal energy storage tank coupled to a household refrigerator through a shell and tube heat exchanger studies are performed. The geometry was developed in SpaceClaim from ANSYS, whereas the unstructured quadrilateral mesh was developed in ANSYS ICEM© and the simulations performed in ANSYS Fluent©. The boundary conditions used on the tank walls are the non-slip and adiabatic. Six simulations were performed: three of them with prescribed heat flux and three with prescribed temperature, all values were associated with the experiment data. Due to the two-dimensional modeling, a heat flux correction is proposed. Furthermore, the thermal coefficient expansion variation effect on the tank performance is analyzed. The Boussinesq approximation is used to account for the density variation with the fluid temperature. The sensible heat storage performance of the tank is assessed employing the Richardson Number, Stratification Number, energy and exergy content. The numerical results are validated with experimental data. Prescribed heat flux is the appropriate boundary condition to model the heat transfer inside the heat exchanger. Also, the heat flux correction represents qualitatively and quantitatively the experiment. The thermal expansion coefficient value influences significantly the water thermal stratification inside the TES tank.