Natural convection of nanoencapsulated phase change suspensions inside a local thermal non-equilibrium porous annulus
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Natural convection of nanoencapsulated phase change suspensions inside a local thermal non‑equilibrium porous annulus Farooq H. Ali1 · Hameed K. Hamzah1 · Masoud Mozaffari2 · S. A. M. Mehryan3 · Mohammad Ghalambaz4,5 Received: 5 January 2020 / Accepted: 31 March 2020 © Akadémiai Kiadó, Budapest, Hungary 2020
Abstract In this study, the heat transfer, fluid flow and heat capacity ratio are analyzed in an annulus enclosure filled with porous and saturated by a suspension of nanoencapsulated phase change materials (NEPCMs). It consists of phase change material core and a polymer or non-polymer shell. The presence of nanoparticles in the base fluid and the phase change capability of the nanoparticle’s core improve the thermal properties of the base fluid and thermal control process. The inner cylinder wall is reserved at hot temperatures where the encapsulated particles absorb the heat, while the outer cylinder wall is reserved at cold temperatures where the encapsulated particles release the heat. A local thermal non-equilibrium model is adopted for the porous medium. The parameters studied are Rayleigh number (104 ≤ Ra ≤ 106), Stefan number (0.2 ≤ Ste ≤ ∞), melting point temperature of the core (0.05 ≤ θf ≤ 1), the concentration of the NEPCM particles (0% ≤ ϕ ≤ 5%), radius ratio (1.67 ≤ Rr ≤ 2.5), eccentricity (− 0.67 ≤ Ec ≤ 0.67), Darcy number ( 10−4 ≤ Da ≤ 10−1), porosity (0.3 ≤ ε ≤ 0.9) and interface heat transfer coefficient (1 ≤ H ≤ 1000). The results show that the dimensionless temperature of fusion (θf) plays the main role in the improvement in NEPCM on the heat transfer process. Keywords Nanoencapsulated phase change materials (NEPCMs) · NEPCM suspension · Local thermal non-equilibrium (LTNE) · Heat transfer enhancement
* Mohammad Ghalambaz [email protected] Farooq H. Ali [email protected] Hameed K. Hamzah [email protected] Masoud Mozaffari [email protected] S. A. M. Mehryan [email protected] 1
Mechanical Engineering Department, College of Engineering, University of Babylon, Babylon, Iraq
2
Department of Mechanical Engineering, Najafabad Branch, Islamic Azad University, Najafabad, Iran
3
Young Researchers and Elite Club, Yasooj Branch, Islamic Azad University, Yasooj, Iran
4
Metamaterials for Mechanical, Biomechanical and Multiphysical Applications Research Group, Ton Duc Thang University, Ho Chi Minh City, Vietnam
5
Faculty of Applied Sciences, Ton Duc Thang University, Ho Chi Minh City, Vietnam
List of symbols Cp Specific heating for pressure constant (KJ kg−1 K−1) Cr Ratio of heat capacity of the suspension to base fluid Da Darcy number f Dimensionless form of phase change behavior Ec Eccentricity g Gravitational acceleration (m s−2) hsf Latent heat of the core (kJ kg−1) i Number of grid case k Thermal conductivity (W m−1 K−1) K Permeability of the porous medium (m2) N Mesh size Nc Suspension conductivity number Nu Nusselt number Nv Suspension dynamic viscosity Pr Prandtl number Qt Total heat transfer rate Rr Radius r
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