Showing papers by "Raymond Viskanta published in 1999"
TL;DR: In this article, the authors treated transient cooling of a hot solid by an impinging circular free surface liquid jet, and the flow and thermal fields in the liquid as well as the temperature distributions in the hot solid have been predicted numerically.
Abstract: This paper treats transient cooling of a hot solid by an impinging circular free surface liquid jet. The flow and thermal fields in the liquid as well as the temperature distributions in the hot solid have been predicted numerically. The Navier-Stokes equations for incompressible fluid flow in an axisymmetric coordinate system and the transient heat conduction equation for a solid have been solved by a finite difference method. The hydrodynamics of the liquid film and the heat transfer processes have been investigated to understand the physics of the phenomena.
34 citations
TL;DR: In this article, the convective heat transfer between a circular free surface impinging jet and a solid surface has been studied numerically, and the predicted results have been compared with experimental data for the purpose of validating the analysis.
Abstract: The convective heat transfer between a circular free surface impinging jet and a solid surface has been studied numerically. The thin liquid film formed on the surface has been assumed to be in non-turbulent free surface flow. The effects of surface tension, viscosity, gravity and heat transfer between the film flow and the solid surface have been taken into account. The flow structure on a non-heated surface has been investigated first. Next, the steady-state flow structure in the liquid film as well as the heat transfer has been examined. The predicted results have been compared with experimental data for the purpose of validating the analysis. The hydrodynamics of the liquid film and the heat transfer processes have been investigated numerically to understand the physics of the phenomena.
28 citations
TL;DR: In this paper, a dynamic model for conjugate heat and mass transfer in a microchannel adsorption reactor is developed based on transient, two-dimensional, and compressible Navier-Stokes equations of motion as the governing conservation equations.
Abstract: A dynamic model for conjugate heat and mass transfer in a microchannel adsorption reactor is developed. The model is based on transient, two-dimensional, and compressible Navier-Stokes equations of motion as the governing conservation equations. Appropriate boundary conditions for the momentum, heat, and mass transfer at the channel wall in the presence of adsorption for the no-slip and slip flows are formulated and incorporated into the generalized single-equation-based framework for solving conjugate problems. The 500- mu m-long parallel-plate channel with spacing between walls 10 mu m and a wall thickness 2 mu m is considered as a prototype of the unit cell of the adsorption microreactor. Air is taken a carrier gas and water vapor as an adsorbable species. The flow conditions are characterized by the Reynolds and Knudsen numbers equal to 130x10-2 and 6.5x10-3, respectively. The Freundlich adsorption isotherm is utilized to specify the adsorption desorption equilibrium. The theoretical model developed i...
3 citations
TL;DR: In this article, a porous medium saturated with an aqueous salt solution was investigated experimentally and theoretically to obtain the improved understanding of the solute redistribution during solid/liquid phase change.
Abstract: Lateral freezing of a porous medium saturated with an aqueous salt solution was investigated experimentally and theoretically to obtain the improved understanding of the solute redistribution during solid/liquid phase change. The emphasis was on the interaction between hydrodynamics and transport of energy and species in the solidifying and unsolidified regions and on the effect of the flow characteristics of the porous matrix and dendrite arrays. Freezing experiments were performed in a square cross-section enclosure chilled and heated from the side by imposing uniform but different temperatures, and filled with the artificial porous structure. The latticed structure of the porous matrix phase and the shadowgraph enabled the flow visualization and the observation of the solidus and liquidus positions. Simultaneous measurements of local temperature and liquid composition at selected locations were also made. An analytical model based on the mass, momentum, heat, and species conservation and relations from the phase diagram is used, and the predictions are compared with experimental data.