An alternative cooling curve analysis method focused on the experimental determination of the latent heat of phase changes and phase transformation kinetics is proposed in this work. The method analyses the cooling process of a metallic sample, initially liquid that is contained into a cylindrical metallic mold, both of known weight, thermally isolated at its top and bottom. The method is based on an energy balance associated with the experimental measurement of the temperature change of the sample and the mold during their cooling process. From the numerical processing of the cooling curves, are obtained approximate values of the acting global heat transfer coefficient as a function of temperature in order to describe quantitatively the energy exchange of the metal/mold system with its surroundings. These relationships and other experimental data are used to process the cooling curve of the sample and the mold during solidification, in order to obtain the latent heat of solidification.The method was applied experimentally to zinc and tin of commercial purity, initially liquids and contained into stainless steel molds in order to determine its ability to measure the latent heat of solidification. The obtained results suggests that this method shows a good potential to characterize the solidification of metals. .
The traditional process for pottery production was analyzed in this work by developing a fundamental mathematical model that simulates the operation of rustic pottery furnaces as employed by natives of villages in Michoacán, Mexico. The model describes radiative heat transfer and fluid flow promoted by natural convection, phenomena that determine the operation of these furnaces. An advanced radiation model called the ''Discrete Ordinates Model'' was implemented within a commercial computational fluid dynamics software. Process analysis was performed to determine the effect of the design variables on the quality of the pottery pieces and on energy efficiency. The variables explored were: (a) Geometric aspect ratio between diameter and height of the furnace (D/H) and (b) Refractory thickness (L). The model was validated using experimental temperature measurements from furnaces located in Santa Fe and Capula, Mexico. Good agreement was obtained between experimental and numerically calculated thermal histories. It was found that furnaces with high aspect ratio D/H and with thick refractory bricks promote thermal uniformity and energy savings. In general, any parameter that increases the conductive thermal resistance of the wall furnace isolates better, and helps energy savings. Operating conditions that provide the smallest thermal gradients and lowest energy consumption are given.
Se desarrolló un modelo matemático 2D para un proceso de soldadura por arco eléctrico en CO2. Se presentan resultados de simulaciones computacionales basadas en los principios de conservación de masa, cantidad de movimiento y leyes de Maxwell, resueltas simultáneamente con la ayuda del software comercial PHOENICS. El modelo predice las propiedades eléctricas de la columna del arco, los patrones de flujo, contornos de temperatura, flujo de calor y potencial eléctrico, al variar la longitud de arco y la corriente aplicada. Al incrementar la corriente, el jet del arco es más intenso, el arco es más caliente y transfiere más calor a la pieza de trabajo, mientras que al incrementar la longitud del arco la temperatura máxima, la velocidad máxima y el flujo de calor no cambian aunque un arco corto focaliza más el calor que un arco largo.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.