Natural convection of nanoencapsulated phase change suspensions inside a local thermal non-equilibrium porous annulus

• Published in: Journal of thermal analysis and calorimetry 2020-09, Vol.141 (5), p.1801-1816
• Main Authors: Ali, Farooq H., Hamzah, Hameed K., Mozaffari, Masoud, Mehryan, S. A. M., Ghalambaz, Mohammad
• Format: Article
• Language: English
• Subjects: Analysis; Analytical Chemistry; Annuli; Chemistry; Chemistry and Materials Science; Computational fluid dynamics; Cylinders; Darcy number; Encapsulation; Fluid flow; Free convection; Heat transfer; Heat transfer coefficients; Inorganic Chemistry; Measurement Science and Instrumentation; Melting points; Nanoparticles; Phase change materials; Physical Chemistry; Polymer Sciences; Polymers; Porosity; Porous media; Thermal energy; Thermal properties; Thermodynamic properties
• ISSN: 1388-6150; 1588-2926
• DOI: 10.1007/s10973-020-09658-z

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 (10 4  ≤  Ra  ≤ 10 6 ), Stefan number (0.2 ≤  Ste  ≤ ∞), melting point temperature of the core (0.05 ≤  θ f  ≤ 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 ( θ f ) plays the main role in the improvement in NEPCM on the heat transfer process.