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ISSN Online: 2379-1748

ISBN Flash Drive: 978-1-56700-469-4

ISBN Online: 978-1-56700-470-0

Second Thermal and Fluids Engineering Conference
April, 2-5, 2017, Las Vegas, NV, USA

NUMERICAL STUDY OF NANOPARTICLE ENHANCED HEAT TRANSFER IN A SOLAR THERMAL ENERGY STORAGE UNIT

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DOI: 10.1615/TFEC2017.est.017936

摘要

Solar energy is clean and sustainable but intermittent in nature. Efficient storage of solar thermal energy is critical for its wider applications. This paper presents a numerical study on heat transfer and energy storage performance of a vertical shell and tube thermal energy storage system, in which CuO - water nanofluid is used as heat transfer fluid (HTF) in the tube while CuO - paraffin wax nanoparticle enhanced phase change material (NePCM) is used on the shell side for energy storage. The nanoparticle diameter is 10nm and the concentration range in HTF and NePCM is 0-8 vol.% and 0-11 vol.% respectively. A computational fluid dynamics (CFD) model is developed to simulate the laminar nanofluid flow, the overall heat transfer, and the melting of NePCM (with an enthalpy porosity technique). Thermophysical properties of the materials are considered to be temperature dependent. It was found that adding nanoparticles in the HTF only slightly increases the melting rate, but the addition of same nanoparticles in the PCM improves the melting rate more significantly. Moreover there is a critical value for nanoparticle concentration in the PCM, beyond which the melting rate starts to decrease, possibly due to reduced natural convection in the shell.