Evaluation of Thermal Stratification Inside a New Model of Spherical Water Storage Tank Using a Computational Fluid Dynamics 6 Degrees of Freedom Solver

Abstract

In this work, a computational analysis of a spherical solar hot water storage tank during the discharging process is carried out by using the commercial code ansys-fluent.15. The study investigates a new type of spherical heat storage tank. A hinged baffle is fixed at the tank vertical axis to increase the discharge flow rate without a thermocline layer. The dynamic mesh LAYERING technique is used to update the computational domain during the movement of the hinged baffle. The passive pitching of the submerged baffle is due to the fluid-dynamic loads. This model limits the mixture between hot and cold water regardless of the inlet flow rate. A comparative study between tanks with typical diffusers and the hinged baffle model is considered. The comparison of the computational fluid dynamics results with available experimental data showed a good agreement. Examinations of the temperature contours indicate that for the typical models, the interaction between the incoming cold water and the stored hot water gives rise to a thick thermocline layer where its temperature and thickness are related to the intensity of the mixing process. The suggested model shows high stratification efficiency along the discharging process.