Orientador: Antonio Carlos Bannwart / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-07-18T08:26:40Z (GMT). No. of bitstreams: 1 Picado_RenatoMigueis_M.pdf: 4702100 bytes, checksum: d0bfd761ce0ac219b5de6f346082ac24 (MD5) Previous issue date: 1992 / Resumo: O objetivo deste trabalho é investigar as metodologias clássicas encontradas na literatura para o tratamento de problemas de condensação de misturas multicomponentes, aplicando-as ao dimensionamento térmico de trocadores de calor multitubulares do tipo casco e tubos. Sob este prisma são analisados os modelos de filme, da curva de condensação e o modelo da curva de condensação com fatores corretivos obtidos a partir da teoria do filme. Cada modelo é definido a partir das equações gerais de balanço e os parâmetros termodinâmicos necessários são obtidos através da relação P-V-T de Soave Redlich Kwong ( S-R-K). O equipamento considerado na simulação é subdividido em vinte elementos de área iguais entre si e o perfil de temperaturas das correntes fria e quente no seu interior é calculado pela técnica dos Elementos Finitos / Abstract: The objective of this work is to investigate the classic methods found in literatura for the treatment of multicomponent mixtures condensation, aplying them to the thermal rating of multitubular shell and tube heat exchangers. Film, condensation curve and condensation curve with correction factors based on film theory models are analised. Each model is defined from local balance equations and the necessary thermodynamic parameters are evaluated from the Soave Redlich Kwong ( S-R-K) equation of state. The equipment is breken into twenty equal area elements and the temperature behavior of hot and cold streams is determineel with Finite Element technics / Mestrado / Mestre em Engenharia Mecânica

Orientador: Artur Zaghini Francesconi / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-07-20T05:50:48Z (GMT). No. of bitstreams: 1 Batista_SoniaMaria_M.pdf: 3489125 bytes, checksum: 1d4dd078582f164ff3e960625c9b4e4f (MD5) Previous issue date: 1995 / Resumo: O estudo do efeito salino no Equilíbrio Líquido-Vapor (EL V) em soluções binárias tem como interesse principal a quebra do azeótropo e mudanças nas volatilidades relativas. O presente trabalho tem como objetivo estudar o efeito salino no equilíbrio líquido-vapor (EL V) do sistema n-hexano/propan-2-01 na presença do sal CaCl2 nas frações molares de sal de 0,005; 0,010 e solução saturada (xsal>= 0,015) à pressão constante de 101,33 kPa. O sistema foi escolhido por ser um sistema não-aquoso (álcool/hidrocarboneto) e que forma um azeótropo. Para a obtenção do EL V foi utilizado um ebuliômetro de recirculação de ambas as fases desenvolvido por Zemp, R. J. e Francesconi, A. Z. [1] e as composições das fases líquida e vapor foram determinadas por cromatografia gasosa e a do sal por gravimetria. Os dados de EL V para o sistema n-hexano/propan-2-o1 livre de sal foram considerados termodinamicamente consistentes quando o método de Herington foi aplicado. Tanto o sistema salino quanto o livre de sal foram correlacionados pelo modelo UNIQUAC. Os resultados permitem concluir que o efeito salino no ELV para o sistema estudado alterou as volatilidades relativas deste, porém o ponto de azeotropia não foi quebrado nem modificado / Abstract: The study of salt effect on the vapor-liquid equilibria (VLE) of binary mixtures is of main interest in breaking azeotropes and improving relative volatilities. The aim of this work is to study the salt effect on the vapor-liquid equilibrium (VLE) of the system n-hexane/propan-2-ol in the presence of the salt CaCl2, in salt molar fractions of 0.005 and 0.010 and satured system (xsalt>= 0.015) at constant pressure of 101.33 kPa. The system was chosen because it is non-aquous (alcohol/hydrocarbon) and forms an azeotrope. The VLE was obtained by both phases recirculating still developed by Zemp, R.J. and Francesconi, AZ. [1] and the compositions of liquid and vapour phases were determined by gas cromotography and gravimetry for the salt. The VLE data for n-hexane/propan-2-ol were found to be thermodinamically consistent when Herington' s test was applied. Both data the system free of salt and the system with salt were correlated using the UNIQUAC model. The results a11ow the conclusion that the salt effect on the VLE for the system studied modifies the relative volatilities, but no change in the azeotropic point was observed. / Mestrado / Mestre em Engenharia Química

Graphene, a layer of carbon atoms arranged in a honeycomb-type structure, has attracted enormous interest since it was first isolated in 2004. Chemical vapor deposition (CVD) is one of the most common techniques to produce graphene but questions remain on how best to standardize its growth. Different designs of reactors, numerous sub-types of CVD (plasma-enhanced, low pressure…), catalytic metal foils that vary in surface chemistry and texture… these are all variables that are abundantly scrutinized in the literature. Despite the scattering of procedures and observations, it is rare to find comparative studies of graphene growth. In this thesis, two thermal CVD reactors were explored to grow single–layer graphene (SLG) on a 50 μm copper foil. These set–ups were very different, one being a “showerhead” cold–wall type whereas the other one had a tubular hot-wall chamber. Their inner volume, gas flow limits, and heating rates were other differentiating factors. The work had three critical steps: pre–growth treatment of the metal foil, growth step and SLG transfer. All required absolute control to obtain high quality, uniform and cm2–scale SLG placed on a SiO2 substrate. Overall, and after standardizing the surface of the metal foil, it was possible to design a CVD recipe for the two reactors that differed only on the gas flow rates used. Thus, and contrary to an often-used argument in the literature, SLG growth recipes can be transferred amongst thermal CVD reactors.

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Tese de mestr.. Engenharia Mecânica. Faculdade de Engenharia. Universidade do Porto. 2002

Call number: LD2668 .T4 1960 C66

Call number: LD2668 .T4 1963 C59 / Master of Science