Numerical study of melting and solidification in a wavy double-pipe latent heat thermal energy storage system
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Numerical study of melting and solidification in a wavy double‑pipe latent heat thermal energy storage system Amin Shahsavar1 · Hafiz Muhammad Ali2 · Roohollah Babaei Mahani3,4 · Pouyan Talebizadehsardari5,6 Received: 25 March 2020 / Accepted: 18 May 2020 © Akadémiai Kiadó, Budapest, Hungary 2020
Abstract The objective of this paper is to develop the influences of channel waviness on the performance of a latent heat storage system during phase change mechanism. The heat exchanger is a vertically oriented double pipe where the heat transfers to/from the PCM in the annulus by moving the water in the inner tube. Various wavelengths, as well as wave amplitudes, are examined at various fluid Re and water temperatures (Tin) to find the effects of channel waviness on different aspects of melting/solidification time, pressure drop, pumping power and exchanged heat rate. Increasing Re, Tin and amplitude of wavy wall improves the system performance during melting and solidification mechanisms. Besides, it is found that there is an optimum dimensionless wavelength of 0.2 for achieving the minimum melting and solidification times as a result of maximum heat exchanged between the water and PCM. Furthermore, the waviness has an almost negligible effect on the pumping power which is reduced for the dimensionless wavelengths higher than 2.0. In the best scenario, the required time to melt and solidify the PCM reduces by almost 28.6% and 57.63%, respectively, using wavy channels compared with the smooth wall case. Keywords Latent energy storage system · Double-pipe heat exchanger · Wavy channel · Melting · Solidification · Liquid fraction List of symbols aw/m Wave amplitude Am Mushy zone constant Cp /J kg−1 K−1 Specific heat transfer coefficient g/m s−2 Gravity * Pouyan Talebizadehsardari [email protected] Roohollah Babaei Mahani [email protected] 1
Department of Mechanical Engineering, Kermanshah University of Technology, Kermanshah, Iran
Mechanical Engineering Department, King Fahd University of Petroleum and Minerals, Dhahran 31261, Kingdom of Saudi Arabia
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Institute of Research and Development, Duy Tan University, Da Nang 550000, Vietnam
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Faculty of Civil Engineering, Duy Tan University, Da Nang 550000, Vietnam
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Metamaterials for Mechanical, Biomechanical and Multiphysical Applications Research Group, Ton Duc Thang University, Ho Chi Minh City, Vietnam
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Faculty of Applied Sciences, Ton Duc Thang University, Ho Chi Minh City, Vietnam
k /W m−1 K−1 Thermal conductivity Lw/m Wave-length Lf /J kg−1 Latent heat of fusion m/kg PCM mass P/Pa Pressure tm/s Melting/solidification time T/K Temperature Ti/K Inlet temperature Tm/K Melting temperature Te/K End temperature V⃗ /m s−1 Velocity /m s−1 Velocity in x-direction v /m s−1 Velocity in y-direction Greek symbols 𝛽 /K−1 Expansion coefficient 𝜆 Liquid fraction 𝜇/kg m−1 s−1 Viscosity 𝜌/kg m−3 PCM density ΔH /J kg−1 PCM latent heat
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Introduction Thermal energy storage
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