Browsing by Subject "Radiative heat transfer"

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An experimental study of the thermal processes relevant to infrared solder reflow
(1990) Fernandes, Neil Joseph, 1967-; Bergman, T. L.
An experimental system has been built to replicate, as closely as possible, the radiative and convective conditions during the infrared solder reflow process. Experiments were performed to measure the transient thermal response of modules for different module array configurations, under combined radiative and convective conditions. Numerical predictions have been obtained to i) identify and quantify the heat transfer mechanisms responsible for the transient thermal response of a center module within different array configurations and ii) to determine the level of modeling sophistication necessary to develop a detailed numerical model that can predict the thermal response of the card assembly. A comparison of the center module's thermal response in a uniform height array and in an array with different module heights illustrates the the module's sensitivity to shading. The predictions and measurements show the general need to incorporate the radiative exchange analysis which includes module-to-module radiative interactions and detailed evaluation of view factors. The predicted heat transfer mechanisms associated with the center module's thermal response shows that, for the case considered here, radiation is the dominant mode of heat transfer and is influenced by i) shading of the module's sides from the infrared panel heaters and ii) radiative exchange with neighboring modules. The convective cooling rate, although smaller than the radiative heating rates for the results presented here, increases with Reynolds number due to increasing convection coefficients. Radiative and conductive heat transfer rates through the gap separating the module and the card are small
Modeling methods of a rotary hearth forging furnace
(2018-01-25) Wanegar, Daniel Frederick; Ezekoye, Ofodike A.; Baldea, Michael
A series of single-physics heat and mass transfer models of a rotary hearth forging furnace are studied for design, selection, and implementation into a multi-physics full system model with a mind towards accuracy and computational efficiency. The transfer modes studied are fluid mass flow, mass-coupled enthalpy transfer, thermal conduction, thermal convection, radiative heat transfer, and steel oxidation. Each mode has one or more associated submodels which are compared for accuracy and efficiency against baseline high fidelity models. A novel model of zonal radiative heat transfer calculations is presented and compared to the radiative heat transfer of a full furnace geometry solved by finite element analysis. A full system model was developed by combining the optimal single-physics submodels according to criteria that favored both speed and accuracy. This system model was then put through a parameter sensitivity analysis for the purpose of identifying which uncontrollable parameters require further accuracy and which controllable parameters are best modified for temperature set point optimization. The system model was also put through an optimization function which determined locally optimal input parameters within a selected parameter space. These optima were compared for the purpose of maximizing furnace efficiency.