Numerical simulation and parametric analysis of latent heat thermal energy storage system
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Numerical simulation and parametric analysis of latent heat thermal energy storage system Manoj Kumar Soni1 · Nisha Tamar1 · Suvanjan Bhattacharyya1 Received: 5 February 2020 / Accepted: 6 August 2020 © Akadémiai Kiadó, Budapest, Hungary 2020
Abstract This paper presents the numerical analysis of the transient performance of the latent heat thermal energy storage unit established on finite difference method. The storage unit consists of a shell and tube arrangement with phase change material (PCM) filled in the shell space and the heat transfer fluid (HTF) flowing in the inner tube. The heat exchange between the HTF, wall and PCM has been investigated by developing a 2-D fully implicit numerical model for the storage module and solving the complete module as a conjugate problem using enthalpy transforming method. A comparative investigation of the total melting time of the PCM has been performed based on natural convection in liquid PCM during the charging process. The novelty of this paper lies in the fact it includes convection in PCM and this investigation includes a detailed parametric study which can be used as a reference to design latent heat storage. The results indicate that natural convection accelerates the melting process by a significant amount of time. In order to optimize the design of the thermal storage unit, parametric study has been accompanied to analyze the influence of various HTF working conditions and geometric dimensions on the total melting time of the PCM. Another important feature considered in this work is the influence of the inner wall of the tube carrying the HTF on the entire melting time of the PCM. An error of around 7.2% is reported when inner wall of the tube is ignored in the analysis. Keywords Natural convection · Enthalpy · Transforming method · Phase change material · Thermal energy storage · Latent heat List of symbols a Thermal diffusivity (m2 s−1) c Specific heat (J kg−1 K−1) D Diameter of tube (m) G Dimensionless acceleration due to gravity h Convection heat transfer coefficient H Volume enthalpy (J m−3) L Length of tube (m) m Mass flow rate (kg s−1) P Dimensionless pressure p Pressure (Pa) Pr Prandtl number q Latent heat capacity (J kg−1) R Dimensionless coordinates along radial direction r Coordinate along radial direction (m) * Suvanjan Bhattacharyya [email protected]‑pilani.ac.in 1
Center for Renewable Energy and Environment Development (CREED), Department of Mechanical Engineering, Birla Institute of Technology and Science, Pilani, Pilani Campus, Vidya Vihar, Pilani, Rajasthan 333 031, India
Re Reynolds number St Stefan number T Temperature (K) t Time (s) V Volume W Dimensionless velocity w Velocity m s−1 X Dimensionless coordinate along axial direction Greek symbols χ Dimensionless enthalpy ⋋ Thermal conductivity (W mK−1) Θ Dimensionless temperature ρ Density (kg m−3) Τ Dimensionless time μ Dynamic viscosity (Pa-s) ϑ Kinematic viscosity (m2 s−1) ¥ Melt fraction Subscripts f HTF ii Internal radius of inner tu
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