Numerical investigation of MHD effects on Al2O3–water nanofluid flow and heat transfer in a semi-annulus enclosure using LBM
TL;DR: In this paper, free convection heat transfer in a concentric annulus between a cold square and heated elliptic cylinders in the presence of magnetic field is investigated, and the Lattice Boltzmann method is applied to solve the governing equations.
About: This article is published in Energy.The article was published on 2013-10-01. It has received 284 citations till now. The article focuses on the topics: Nusselt number & Hartmann number.
Citations
More filters
TL;DR: In this paper, the effect of thermal radiation on magnetohydrodynamics nanofluid flow between two horizontal rotating plates is studied and the significant effects of Brownian motion and thermophoresis have been included in the model of Nanofluide.
700 citations
TL;DR: In this article, the effect of thermal radiation on Al2O3-water nanofluid flow and heat transfer in an enclosure with a constant flux heating element was explored.
398 citations
TL;DR: In this paper, the influence of an external magnetic field on ferrofluid flow and heat transfer in a semi annulus enclosure with sinusoidal hot wall is investigated and the governing equations which are derived by considering the both effects of FHD and MHD (Magnetohydrodynamic) are solved via CVFEM (Control Volume based Finite Element Method).
393 citations
TL;DR: In this article, the effect of Brownian motion on the effective thermal conductivity and viscosity of nanofluid is investigated using Lattice Boltzmann method to solve the governing equations.
346 citations
TL;DR: In this paper, an extensive literature review of various turbulators (coiled tubes, extended surfaces (fin, louvered strip, winglet), rough surfaces (Corrugated tube, Rib) and swirl flow devices such as twisted tape, conical ring, snail entry turbulator, vortex rings, coiled wire) for enhancing heat transfer in heat exchangers.
Abstract: Economic reasons (material and energy saving) leads to make efforts for making more efficient heat exchange. The heat transfer enhancement techniques are widely used in many applications in the heating process to make possible reduction in weight and size or enhance the performance of heat exchangers. These techniques are classified as active and passive techniques. The active technique required external power while the passive technique does not need any external power. The passive techniques are valuable compared with the active techniques because the swirl inserts manufacturing process is simple and can be easily employed in an existing heat exchanger. Insertion of swirl flow devices enhance the convective heat transfer by making swirl into the bulk flow and disrupting the boundary layer at the tube surface due to repeated changes in the surface geometry. An effort has been made in this paper to carry out an extensive literature review of various turbulators (coiled tubes, extended surfaces (fin, louvered strip, winglet), rough surfaces (Corrugated tube, Rib) and swirl flow devices such as twisted tape, conical ring, snail entry turbulator, vortex rings, coiled wire) for enhancing heat transfer in heat exchangers. It can be concluded that wire coil gives better overall performance if the pressure drop penalty is considered. The use of coiled square wire turbulators leads to a considerable increase in heat transfer and friction loss over those of a smooth wall tube.
344 citations
References
More filters
3,793 citations
TL;DR: In this article, a model is developed to analyze heat transfer performance of nanofluids inside an enclosure taking into account the solid particle dispersion, where the transport equations are solved numerically using the finite-volume approach along with the alternating direct implicit procedure.
2,560 citations
TL;DR: In this paper, the Brownian motion of nanoparticles at the molecular and nanoscale level is a key mechanism governing the thermal behavior of nanoparticle-fluid suspensions (nanofluids).
Abstract: We have found that the Brownian motion of nanoparticles at the molecular and nanoscale level is a key mechanism governing the thermal behavior of nanoparticle–fluid suspensions (“nanofluids”). We have devised a theoretical model that accounts for the fundamental role of dynamic nanoparticles in nanofluids. The model not only captures the concentration and temperature-dependent conductivity, but also predicts strongly size-dependent conductivity. Furthermore, we have discovered a fundamental difference between solid/solid composites and solid/liquid suspensions in size-dependent conductivity. This understanding could lead to design of nanoengineered next-generation coolants with industrial and biomedical applications in high-heat-flux cooling.
1,459 citations
TL;DR: Through an order-of-magnitude analysis of various possible mechanisms, convection caused by the Brownian movement of these nanoparticles is primarily responsible for the enhancement in k of these colloidal nanofluids.
Abstract: Researchers have been perplexed for the past five years with the unusually high thermal conductivity (k) of nanoparticle-laden colloidal solutions (nanofluids). Although various mechanisms and models have been proposed in the literature to explain the high k of these nanofluids, no concrete conclusions have been reached. Through an order-of-magnitude analysis of various possible mechanisms, we show that convection caused by the Brownian movement of these nanoparticles is primarily responsible for the enhancement in k of these colloidal nanofluids.
876 citations
TL;DR: In this paper, the lattice Boltzmann equation (LBE) is applied to high Reynolds number incompressible flows, some critical issues need to be addressed, noticeably flexible spatial resolution, boundary treatments for curved solid wall, dispersion and mode of relaxation, and turbulence model.
861 citations