CFD analysis of thermal stratification in domestic hot water storage tank during dynamic mode

In this paper, the thermal behavior of a vertical domestic hot water storage tank during the dynamic mode was studied. A 3D computational fluid dynamic (CFD) model was performed using the commercial software package Fluent v6.3. The proposed model was validated with experimental data obtained from the literature. The results of the simulation served to analyze the flow characteristics and the thermal stratification evolution during charging and discharging phases. This study was further extended to explore the effect of varying tank position (horizontal/vertical) on the system performance. A numerical comparison between the two configurations was carried out and performance parameters such as discharge efficiency, Richardson number and stratification efficiency were calculated. A major finding of the above analysis was the presence of two regions of increased thermal mixing in the horizontal tank. The contribution of these two recirculation zones on the destruction of the thermal stratification resulting in a decrease of the overall performance was demonstrated.