Aplicação da transformada integral generalizada e da transformação conforme na solução de um problema de convecção forçada laminar em dutos de setor de anel circular

ResumoEste trabalho descreve uma solução híbrida analítico‐numérica aplicando a técnica da transformada integral generalizada (TTIG) na transferência de calor por convecção forçada de um escoamento laminar fluido dinamicamente desenvolvido e termicamente em desenvolvimento de um fluido Newtoniano em dutos de seção transversal com formato de setor de anel circular sob condições de contorno de Dirichlet, considerando um perfil de temperatura uniforme na entrada. Para facilitar o tratamento analítico e a aplicação das condições de contorno uma transformação conforme foi utilizada, visando alterar o domínio para um sistema de coordenadas mais apropriado. Feito isso, a TTIG foi aplicada na equação da energia para obtenção do campo de temperatura. Os resultados numéricos foram obtidos para parâmetros térmicos de interesse, tais como: temperatura média de mistura, números de Nusselt local e médio e comprimento de entrada térmica. Estes resultados foram comparados, quando possível, com os valores disponíveis na literatura e apresentaram uma ótima concordância.AbstractThis work describes a hybrid analytical‐numerical solution employing the Generalized Integral Transform Technique (GITT) to forced convection heat transfer in hydrodynamically fully developed and thermally non‐developed Newtonian laminar flow inside annular sector ducts under Dirichlet boundary conditions, considering uniform temperature entrance profile. In order to facilitate the analytical treatment and the application of the boundary conditions, a Conformal Transform was utilized to change the domain into a more suitable coordinate system. Thereafter, the GITT was applied on the energy equation to obtain the temperature field. Numerical results were obtained for quantities of practical interest, such as bulk mean temperature, local and average Nusselt number, and thermal entry length. These results were compared, as much as possible, with the parameter values available in the literature and they presented a good agreement

Analysis of overall utilization of sugarcane biomass and waste from the production of sugar and ethanol for cogeneration in a Brazilian sugarcane mill

Paper presented to the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Florida, 14-16 July 2014.This work presents thermodynamic, thermoeconomic and economic analyses of biomass gasification systems integration in a sugar-ethanol factory. Four configurations, combining the actual cogeneration plant with straw and stillage gasification systems, are considered. Case 1 represents a steam plant of a modern conventional power plant (base case), with a steam boiler of high-pressure and high-temperature, as well as an extraction-condensation steam turbine, being all mechanical driving electrified. In the other cases, gasification systems are associated to the actual plant using the energy from a gas turbine and a heat recovery steam generator to complete a combined cycle. In Case 2, the incorporation of a system for biodigestion of stillage is experimented. In Case 3, the incorporation of the sugar-cane straw gasification in the current plant is considered and Case 4 considers the gasification of straw and stillage.cf201

Application of generalized integral and conformal transforms on the solution of a problem of laminar forced convection inside annular sector ducts

This work describes a hybrid analytical‐numerical solution employing the Generalized Integral Transform Technique (GITT) to forced convection heat transfer in hydrodynamically fully developed and thermally non‐developed Newtonian laminar flow inside annular sector ducts under Dirichlet boundary conditions, considering uniform temperature entrance profile. In order to facilitate the analytical treatment and the application of the boundary conditions, a Conformal Transform was utilized to change the domain into a more suitable coordinate system. Thereafter, the GITT was applied on the energy equation to obtain the temperature field. Numerical results were obtained for quantities of practical interest, such as bulk mean temperature, local and average Nusselt number, and thermal entry length. These results were compared, as much as possible, with the parameter values available in the literature and they presented a good agreement

Study On Determination And Removal Of Metallic Ions From Aqueous And Alcoholic Solutions Using A New Poss Adsorbent

In this study, a new nanostructured organosilicate, named Octakis[(thiourea)propyl] octasilsesquioxane (POSS-Pr-THIO) was prepared, characterized and used for determination and removal of the ions Fe3+, Cr3+, V3+ and Zn2+ and compared with 3-[(thiourea) propyl] silica gel (SG-Pr-THIO). To the best of our knowledge, this study is the first that has reported the preparation of POSS-Pr-THIO and the comparison with its analogous SG-Pr-THIO for removal by batch and column experiments of toxics metals from natural waters, fuel ethanol and sugar-cane spirits. Langmuir and pseudo-second order models were the most appropriate to describe the adsorption and kinetic data respectively. Thermodynamic functions showed a feasible, spontaneous and endothermic process. The method of quantitative analysis of metal ions in natural waters, fuel ethanol and sugar-cane spirits by Flame AAS was validated using, namely, linearity, limit of detection, limit of quantification, and the relative standard deviation and accuracy. The results obtained in the flow of experiments in natural waters, fuel ethanol and sugar-cane spirit solutions, showed a recovery of nearly 100% of the metal ions adsorbed in a column packed with 1.0g of material, using 5mL of 1.0M HCl solution as eluent.2647788Phillips, S.H., Haddad, T.S., Tomczak, S.J., Developments in nanoscience: polyhedral oligomeric silsesquioxane (POSS)-polymers (2004) Curr. Opin. Solid State Mater. Sci., 8, pp. 21-29Dias Filho, N.L., Marangoni, F., Costa, R.M., Preparation, characterization, and CuX2 and CoX2 (X=Cl-, Br-, ClO- 4) adsorption behavior of a polyhedral oligomer silsesquioxane functionalized with an organic base (2007) J. 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