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ISSN Online: 2377-424X

ISBN Print: 978-1-56700-421-2

International Heat Transfer Conference 15
August, 10-15, 2014, Kyoto, Japan

Numerical Simulation of Heat Transfer in a Directly Illuminated Solar Thermal Energy Store

Get access (open in a dialog) DOI: 10.1615/IHTC15.sol.009290
pages 7587-7594

Resumo

A numerical simulation of the heat transfer inside a volumetric absorption thermal storage unit for integration with a 5kWe modular Concentrated Solar Power plant is presented in this paper. The volumetric thermal energy store consists of a high temperature molten thermal storage salt which is directly illuminated by a concentrated solar source, thus enabling efficient capture, conversion and thermal storage of solar energy. The overall aim of this research is to improve system efficiency and reduce the unit cost of generated electricity. This study aims to simulate the transient heat transfer arising from the volumetric absorption of directly deposited solar radiation in thermal store for aspect ratios of 0.5, l and 2. The Thermal Energy Storage (TES) is studied for a specific case in which the volume is heated by (l) the direct absorption of the incident solar radiation in accordance to Beer law and (2) re-emission of boundary residual radiation heat flux which develops large temperature gradients to influence convective heat transfer. Results of the transient temperature profile within the salt volume of the thermal energy store of aspect ratios, r = l and r = 2 reveal distinct flow regimes characterised by (l) an initial stage (conduction regime) (2) a transitional stage visible from the evolution of instabilities and (3) large scale cell circulation where natural convection is dominant. When r=2, stable stratification was observed and free convection is absent.