NON-UNIFORM WATER FLUX DENSITY APPROACH APPLIED ON A MATHEMATICAL MODEL OF HEAT TRANSFER AND SOLIDIFICATION FOR A CONTINUOUS CASTING OF ROUND BILLETS
DISTRIBUIÇÃO NÃO-UNIFORME DA VAZÃO ESPECÍFICA DE ÁGUA APLICADA AO MODELO MATEMÁTICO DE TRANSFERÊNCIA DE CALOR E SOLIDIFICAÇÃO DO LINGOTAMENTO CONTÍNUO DE BARRAS CILÍNDRICAS
Assunção, Charles Sóstenes; Tavares, Roberto Parreiras; Oliveira, Guilherme
http://dx.doi.org/10.4322/tmm.2014.042
Tecnol. Metal. Mater. Min., vol.11, n4, p.363-370, 2014
Abstract
In the present work, the water flux densities of nozzles with flat jet and full cone jet were experimentally measured using an apparatus in industrial scale that reproduces the secondary cooling of the continuous casting of round billets of Vallourec Tubos do Brasil. A mathematical model for heat transfer and solidification for the continuous casting of round billets was developed applying the experimental water flux density profile, establishing a non-uniform water distribution approach. The mathematical model was validated by experimental measurements of the billet superficial temperature, performed at the industrial plant. The results of the mathematical model using both uniform and non-uniform water flux density approaches were compared. The non-uniform water distribution approach enabled to identify important variations of the heat transfer coefficients and the billet temperatures, especially in the first cooling zone, and to assess more accurately the local effects of the water distribution on the thermal behavior of the strand. The non-uniform water flux density approach applied to the mathematical model was a useful and more accurate tool to improve the comprehension of the thermal behavior of the steel along the secondary cooling.
Keywords
Water flux density, Heat transfer coefficient, Secondary cooling, Mathematical model.
Resumo
As vazões específicas de água de bicos spray com jato do tipo leque e cone cheio foram medidas experimentalmente usando um aparato em escala industrial que reproduz o resfriamento secundário do lingotamento contínuo de barras cilíndricas da Vallourec Tubos do Brasil. Um modelo matemático da transferência de calor e solidificação foi desenvolvido aplicando o perfil de vazão específica de água obtida experimentalmente, desenvolvendo uma nova abordagem de distribuição não-uniforme de água. O modelo matemático foi validado por medições experimentais de temperatura superficial da barra realizadas na planta industrial. Os resultados do modelo matemático usando as abordagens de distribuição uniforme e não-uniforme de vazão específica de água foram comparados. A abordagem de distribuição não-uniforme de vazão específica de água permitiu identificar importantes variações no coeficiente de transferência de calor e na temperatura superficial da barra, especialmente na primeira zona de resfriamento por spray, e, consequentemente, avaliar de forma mais exata os efeitos localizados na distribuição de água no comportamento térmico do aço. A abordagem de distribuição não-uniforme de vazão específica de água se mostrou uma ferramenta útil e mais acurada para aumentar a compreensão do comportamento térmico do aço ao longo da câmara spray.
Palavras-chave
Vazão específica de água, Coeficiente de transferência de calor, Resfriamento secundário, Modelo matemático.
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