Conjugate buoyant convective transport of nanofluids in an enclosed annular geometry

Abstract

A vertical annular configuration with differently heated cylindrical surfaces and horizontal adiabatic boundaries is systematically studied in view to their industrial applications. In this paper, we investigate the effects of conjugate buoyant heat transport in water based nanofluids with different nanoparticles such as alumina, titania or copper, and is filled in the enclosed annular gap. The annulus space is formed by a thick inner cylinder having a uniform high temperature, an exterior cylindrical tube with a constant lower temperature, and thermally insulated upper and lower surfaces. By investigating heat transport for broad spectrum of Rayleigh number, solid wall thickness, thermal conductivity ratio and nanoparticle volume fraction, we found that the influence of wall thickness on thermal dissipation rate along wall and interface greatly depends on conductivity ratio and vice-versa. In particular, we uncover that the choice of nanoparticle in a nanofluid and its concentration are key factors in enhancing the thermal transport along the interface. Specially, copper based nanofluids produces higher heat transport among other nanoparticles, and for the range of nanoparticle concentration chosen in this analysis, enhanced thermal dissipation along the interface has been detected as nanoparticle volume fraction is increased. Our results are applicable to choose nanofluids along with other critical parameters for the desired heat transport.

Magneto-convective flow through a porous enclosure with Hall current and thermal radiation effects: numerical study

“…Although porous media enclosure flows have been studied previously in the presence of magnetohydrodynamic effects [23][24][25]. Sankar et al [30] presented detailed analysis on impacts of various key parameters on flow and thermal behaviour of three different nanofluids in the annular geometry having finite thickness at the inner cylinder. Sankar et al [31] presented detailed analysis on Natural convection of a low Prandtl number electrically conducting fluid (Pr = 0.054) under the influence of either axial or radial magnetic field in a vertical cylindrical annulus.…”

Buoyant heat transfer of nanofluids in a vertical porous annulus: a comparative study of different models

“…Among the studies focusing on convective thermal transport and fluid flow phenomena in finite-sized geometries, the investigations pertaining to annular domain formed by two upright concentric cylinders has gained great attention in several engineering systems because of vital applications in cooling of electronic gadgets, nuclear reactors, gas-cooled electrical cables and so on. An overview of the well-documented investigations on convection in annulus has been recorded in the literature (Prasad and Kulacki, 1985; Kumar and Kalam, 1991; Sankar and Do, 2010; Mebarek-Oudina, 2017; Abouali and Falahatpisheh, 2009; Mebarek-Oudina, 2019; Reddy and Sankar, 2020; Sankar et al , 2021). One of the earlier experimental works in the annular geometry by Prasad and Kulacki (1985) deals with the natural convection in a liquid-filled annular domain.…”

“…In the same geometry filled with nanofluids, the impact of non-uniform thermal profiles has been studied in detail by Reddy and Sankar (2020) and reported the appropriate thermal profile suitable for heat transport enhancement. Recently, Sankar et al (2021) performed numerical investigation of buoyant convection in a nanofluid-filled annular enclosure considering the effect of wall thickness. The above cited works mainly addresses the buoyant motion and associated heat transport characteristics in a vertical annulus without considering porous media effects.…”

Dual solutions for double diffusion and MHD flow analysis of micropolar nanofluids with slip boundary condition

“…Investigation of the combined effects of the electrically conducting water-based nanofluid parameters, thermal radiation, the porous medium, convective heating, viscous dissipation, magnetic field, and the nanofluid on the dimensionless velocity, temperature, and rescaled nanoparticle volume frame is the aim of the current work. Readers are directed to [22][23][24][25][26][27][28][29][30][31][32][33][34] and any cited references therein for more information. This study's objective is to numerically investigate micropolar nanofluid flow with slip boundary conditions.…”