Purpose
The nanofluid flow and heat transfer within a heat exchanger, with different thermal arrangements of internal active bodies, are investigated.
Design/methodology/approach
For the numerical simulations, the lattice Boltzmann method is utilized. The KKL model is used to predict the dynamic viscosity of CuO-water nanofluid. Furthermore, the Brownian method is taken account using this model. The influence of shapes of nanoparticles on the heat transfer performance is considered.
Findings
The results show that the platelet nanoparticles render higher average Nusselt number showing better heat transfer performance. In order to perform comprehensive analysis, the heatline visualization, local and total entropy generation, local and average Nusselt variation are employed.
Originality/value
The originality of this work is carrying out a comprehensive investigation of nanofluid flow and heat transfer during natural convection using lattice Boltzmann method and employing second law analysis and heatline visualization.
Numerical study of the slip effects and radiative heat transfer on a steady state fully developed Williamson flow of an incompressible Newtonian fluid; between parallel vertical walls of a microchannel with isothermal walls in a porous medium is performed. The slip effects are considered at both boundary conditions. Radiative highly absorbing medium is modeled by the Rosseland approximation. The non-dimensional governing Navier-Stokes and energy coupled partial differential equations formed a boundary problem are solved numerically using the fourth order Runge-Kutta algorithm by means of a shooting method. Numerical outcomes for the skin friction coefficient, the rate of heat transfer represented by the local Nusselt number were presented even as the velocity and temperature profiles illustrated graphically and analyzed. The effects of the temperature number, Grashof number, thermal radiation parameter, Reynolds number, velocity slip length, Darcy number, and temperature jump, on the flow field and temperature field and their effects on the boundaries are presented and discussed.
Abstract:In this paper, the modeling of a steady state two phase flow heated through a vertical upward flow under electro-magneto-hydro-dynamic forces is presented. The thermal non-equilibrium, non-homogeneous, two-phase flow model consisting of mass, momentum and energy conservation in each phase has been adjusted for subcooled inlet conditions close to saturation. The P-1 approximation, viscous dissipation and Joule heating are included in the energy equations. It was seen that the Lorentz force can decrease and postpone the bubble generation, as well as affect the slip velocity, flow forces, viscous dissipation and Joule heating. Furthermore, two correlations for the slip velocity under magnetohydrodynamic (MHD) forces are presented. As shown, skin friction and Joule heating increase with the magnetic field strength.
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