A Comparative Study of High-Temperature Latent Heat Storage Systems

Alok Kumar Ray, Dibakar Rakshit, K. Ravi Kumar and Hal Gurgenci
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Alok Kumar Ray: Department of Energy Science and Engineering, University of Queensland-Indian Institute of Technology Delhi Academy of Research (UQIDAR), Indian Institute of Technology, Delhi 110016, India
Dibakar Rakshit: Department of Energy Science and Engineering, Indian Institute of Technology, Delhi 110016, India
K. Ravi Kumar: Department of Energy Science and Engineering, Indian Institute of Technology, Delhi 110016, India
Hal Gurgenci: School of Mechanical and Mining Engineering, University of Queensland, Brisbane 4072, Australia

Energies, 2021, vol. 14, issue 21, 1-19

Abstract: High-temperature latent heat storage (LHS) systems using a high-temperature phase change medium (PCM) could be a potential solution for providing dispatchable energy from concentrated solar power (CSP) systems and for storing surplus energy from photovoltaic and wind power. In addition, ultra-high-temperature (>900 °C) latent heat storage (LHS) can provide significant energy storage density and can convert thermal energy to both heat and electric power efficiently. In this context, a 2D heat transfer analysis is performed to capture the thermo-fluidic behavior during melting and solidification of ultra-high-temperature silicon in rectangular domains for different aspect ratios (AR) and heat flux. Fixed domain effective heat capacity formulation has been deployed to numerically model the phase change process using the finite element method (FEM)-based COMSOL Multiphysics. The influence of orientation of geometry and heat flux magnitude on charging and discharge performance has been evaluated. The charging efficiency of the silicon domain is found to decrease with the increase in heat flux. The charging performance of the silicon domain is compared with high-temperature LHS domain containing state of the art salt-based PCM (NaNO 3 ) for aspect ratio (AR) = 1. The charging rate of the NaNO 3 domain is observed to be significantly higher compared to the silicon domain of AR = 1, despite having lower thermal diffusivity. However, energy storage density (J/kg) and energy storage rate (J/kgs) for the silicon domain are 1.83 and 2 times more than they are for the NaNO 3 domain, respectively, after 3.5 h. An unconventional counterclockwise circular flow is observed in molten silicon, whereas a clockwise circular flow is observed in molten NaNO 3 during charging. The present study establishes silicon as a potential PCM for designing an ultra-high-temperature LHS system.

Keywords: renewable energy; high-temperature; LHS; thermo-fluidic; liquid/solid fraction; energy storage density (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2021
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