Showing papers by "Raymond Viskanta published in 1986"

Radiative transfer in axisymmetric, finite cylindrical enclosures

Abstract: Modele de transfert radiatif axisymetrique a 2 dimensions pour un milieu heterogene, diffusant de facon anisotrope, emissif, absorbant base sur l'approximation d'harmoniques spheriques du 3eme ordre

three-dimensional numerical simulation of circulation and heat transfer in an electrically boosted glass melting tank

Abstract: A three-dimensional numerical methodology to simulate the effect of electric boosting on glassmelt circulation and heat transfer in a glass melting furnace is presented. Due to a small, characteristic Hartmann number, the ponderomotive forces in the momentum equation were neglected. The voltage and electric current fields within the melt were determined by solving real and imaginary parts of the electric potential. The Joulean heat dissipation was determined and coupled to the energy equation of the melt. Other relevant processes, such as batch-melting and heat transfer from combustion space, were integrated into a system model. Merits of electric boosting were examined by obtaining some representative results and comparing model predictions with and without electric boosting.

Three-Dimensional Numerical Simulation of Circulation and Heat Transfer in an Electrically Boosted Glass Melting Tank

Abstract: A three-dimensional numerical methodology to simulate the effect of electric boosting on glassmelt circulation and heat transfer in a glass melting furnace is presented. Due to a small, characteristic Hartmann number, the ponderomotive forces in the momentum equation were neglected. The voltage and electric current fields within the melt were determined by solving real and imaginary parts of the electric potential. The Joulean heat dissipation was determined and coupled to the energy equation of the melt. Other relevant processes, such as batch-melting and heat transfer from combustion space, were integrated into a system model. Merits of electric boosting were examined by obtaining some representative results and comparing model predictions with and without electric boosting.

Dynamics of a Natural Circulation Loop: Analysis and Experiments

Abstract: A dynamic one-dimensional model of a simple rectangular natural circulation loop with tube bundles in the two vertical legs has been simulated. A supporting experimental study using water at atmospheric pressure as the working fluid has been conducted to obtain data to verify the model. Good agreement was obtained between the predicted and measured mixed-mean fluid temperatures and surface temperatures of the tube bundle as well as the loop piping and insulation temperatures at several locations around the system. A number of different simulations and tests have been performed and are discussed. In general, at steady state there was less than 7% deviation between the model predictions and the test data, which indicates that the one-dimensional model is capable of predicting the transient temperature response of the loop structural components and of the circulating fluid.

Modeling of heat transfer in the melting of a glass batch

Abstract: On the basis of appropriate assumptions, a mathematical model has been constructed to predict the temperature distribution and heat transfer in a glass batch blanket and to simulate the effects of individual factors on the conversion process. The solution of the model equations is obtained numerically. The model is used to determine the effect of various parameters describing the melting process on heat transfer and melting time of unpreheated and preheated batch. The numerical results obtained for container glass are presented in graphical and tabular form.

Radiation Transfer in a Cylindrical Vessel Containing High-Temperature Corium Aerosols

Abstract: Radiation transfer is relevant to a number of key technical issues related to nuclear reactor safety studies. To gain understanding of thermal radiation transfer under hypothetical reactor accident conditions, analysis of radiation transfer in a finite length cylindrical vessel containing high-temperature aerosols that absorb, emit, and scatter thermal radiation has been performed. The fine particles are assumed to be produced by the dispersion of the reactor core debris under high pressure. The model parameters used in the calculations correspond to those proposed in the High-Pressure Melt Streaming experimental program. Results of calculations show that the extinction coefficient and the single scattering albedo of the aerosol and the emissivity of the vessel are important model parameters. The sensitivity studies have identified the radiative property data base needed to make realistic radiative transfer calculations relevant to hypothetical reactor accidents in which fine aerosol particles are generated from the core debris.