Three-dimensional unsteady CFD simulations of a thermal storage tank performance for optimum design

Abstract This paper presents the results of three-dimensional (3D) unsteady Computational Fluid Dynamics (CFD) simulations to investigate the influence of several design and operating parameters during charging operation on the flow behaviour, thermal stratification and performance of a hot water storage tank installed in solar thermal energy systems. Validation of the unsteady flow computation results with experimental data found in the literature has shown a good agreement. Different computation test cases were run to systematically analyse the effects of key geometrical and operating parameters on the system performance. The CFD results confirmed the importance of combined effects on the performance of thermal storage tanks and showed that an appropriately designed storage tank can provide improved stratification conditions. Moreover, 3D transient CFD simulations can be used as an effective tool to optimise thermal storage tank parameters at early design stages, thus it may add to the value of the storage tank performance and efficiency, by optimising the whole solar thermal energy storage system design and size.

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