Effect of plate configurations on thermal stratification and energy efficiency in solar hot water storage tanks: A CFD-based analysis

Abstract

This study numerically investigates the effect of plate configurations on thermal stratification performance and energy efficiency of solar hot water storage tanks, emphasizing the role of plate configurations in enhancing energy efficiency. Using a detailed three-dimensional model comprising fluid flow and heat transfer equations, accompanied by Boussinesq approximation, the study analyzes the impact of plate size, placement, and inlet design on temperature distribution and thermocline behavior. Key performance indicators including the Richardson number (Ri), stratification number (St), pressure drop (ΔP), and discharging efficiency were assessed. Validation against experimental data confirmed the model's reliability, with discrepancies remaining below 5%. The obtained results showed that the perforated plates with 25% open area achieved the highest Ri (55.36), the lowest ΔP (6.68 Pa), and pumping energy (0.178 μW), along with the most efficient stratification performance. In contrast, solid plates provided balanced stratification with Ri values of 4.79 and moderate ΔP of about 7.84 Pa. The outcomes confirm that plate diameter, placement near the thermocline, and perforation design significantly impact thermal stratification and energy efficiency, offering critical insights for optimizing thermal energy storage in renewable energy systems.