Orientador: José Luz Silveira / Banca: Carlos Daniel Ebinuma / Banca: Julio Santana Antunes / Banca: Nathan Mendes / Banca: Electo Eduardo Silva Lora / Resumo: Os sistemas de refrigeração por absorção da mistura amônia-água têm sido amplamente utilizados e referenciados na literatura. Normalmente, os modelos encontrados para análises são baseados considerando-se, dados de tabelas e diagramas para a entalpia em função da concentração. Para a análise de tabelas e diagramas de entropia em função da concentração de amônia na mistura, não se detém a mesma atenção, existindo ausência de dados disponíveis na literatura para esta propriedade termodinâmica. Estes sistemas apresentam-se complexos quanto aos parâmetros físico-químicos, tornando-se necessário um estudo mais aprofundado e detalhado da termodinâmica associada, corroborando para a determinação da inter-relação da entropia com outras propriedades associadas a refrigeração. Neste trabalho são formulados modelos de cálculos para o levantamento da entropia em função da temperatura, pressão e concentração de misturas amônia-água S = S (T, P, x). A confecção dos diagramas de entropia na fase líquido-vapor foram determinados visando auxiliar projetos industriais através de análises energéticas e exergéticas, simulação e otimização de processos relacionados ao sistema de refrigeração por absorção. / Abstract: Refrigeration systems of the ammonia-water mixtures by absorption have been widely used and referred in the literature. Usually the models found for analyses are based taking in to account data of tables and diagrams for the enthalpy as a function of the concentration. For the analysis of tables and entropy diagrams in function of the concentration of ammonia in the mixture, it has not been taken the same attention, existing lack of available data in the literature for that thermodynamic property. These systems seem to be complex as for the physiochemical parameters, becoming necessary a deeper and detailed study on the associated thermodynamics, corroborating to determine the interrelation of the entropy with other associated refrigeration properties. In this work, calculation models to improve the entropy are formulated in function of temperature, pressure and concentration of the ammonia-water mixtures S = S (T, P, x). The performance of the entropy diagrams in the liquid-vapor phase was surely aiming to aid industrial projects through energy analyses and exergetic simulation and optimization of processes related to the system of cooling by absorption. / Doutor

A thermodynamic framework was presented for the development of powderconstitutive models. The process of powder compaction through Equal ChannelAngular Extrusion (ECAE) at room temperature was modeled using the finiteelement analysis package ABAQUS. The simulation setup was used to conduct aparametric study involving varying the process parameters of ECAE, aimed ataiding the process design.Two powder compaction models, the Gurson model and the Duva and Crowmodel, were used to test their efficacy in modeling this process. Thethermodynamic framework was applied to derive the constitutive equations of theDuva and Crow model. Modeling parameters like friction coefficients, interactionconditions were determined by comparing the simulations for solid billet and anempty can with actual experimental runs for loads, shear angle and workpiece geometry. The simulations using the two powder constitutive models showed nosignificant difference in the stress in the powder during the extrusion.The results obtained from the 3-D simulations were also compared toexperiments conducted to compact copper powder with a size distribution of 10mto 45m. It was found through experiments that the powder does not fullyconsolidate near the outer corner of the workpiece after the first ECAE pass and theresults from the simulations were used to rationalize this phenomenon.Modifications made to the process by applying a back pressure during thesimulations resulted in a uniformly compacted powder region.Further, simulations were carried out by varying the process parameters likethe crosshead velocity, the friction coefficient between the walls of the die and thecan, can dimensions and material, shape of the can cross section etc and the effectof each of these parameters was quantified by doing a sensitivity analysis.

A thermodynamic framework was presented for the development of powderconstitutive models. The process of powder compaction through Equal ChannelAngular Extrusion (ECAE) at room temperature was modeled using the finiteelement analysis package ABAQUS. The simulation setup was used to conduct aparametric study involving varying the process parameters of ECAE, aimed ataiding the process design.Two powder compaction models, the Gurson model and the Duva and Crowmodel, were used to test their efficacy in modeling this process. Thethermodynamic framework was applied to derive the constitutive equations of theDuva and Crow model. Modeling parameters like friction coefficients, interactionconditions were determined by comparing the simulations for solid billet and anempty can with actual experimental runs for loads, shear angle and workpiece geometry. The simulations using the two powder constitutive models showed nosignificant difference in the stress in the powder during the extrusion.The results obtained from the 3-D simulations were also compared toexperiments conducted to compact copper powder with a size distribution of 10mto 45m. It was found through experiments that the powder does not fullyconsolidate near the outer corner of the workpiece after the first ECAE pass and theresults from the simulations were used to rationalize this phenomenon.Modifications made to the process by applying a back pressure during thesimulations resulted in a uniformly compacted powder region.Further, simulations were carried out by varying the process parameters likethe crosshead velocity, the friction coefficient between the walls of the die and thecan, can dimensions and material, shape of the can cross section etc and the effectof each of these parameters was quantified by doing a sensitivity analysis.

Atomic Layer Epitaxy is a stepwise deposition process by supplying the sources materials alternatively. This deposition technique provides the monolayer control of film thickness and the uniform film growth over a large area. ZnSxSe1-x layers were grown epitaxially onto Si and GaAs substrate by using DMZn and H2S , H2Se gases for the reactant source. Owing to the self-limiting characteristics of ALE process, ZnSxSe1-x monolayers could be deposited over a wide range of temperature within growth window. In this study, for obtaining high crystalline quality ZnSxSe1-x epitaxial films, various growth conditions were investigated including substrate temperature, the flow rate of DMZn, H2S and H2Se, H2 purge duration and pulse duration etc.. A thermodynamic analysis based the calculation of Seki et. al [6], was used to investigate the effects by varying the substrate temperature, input mole ratio of group VI source gases on equilibrium partial pressure, solid composition and solid-vapor distribution relation of this alloy. The interaction parameter of ZnSxSe1-x, £[, was estimated by using the delta-lattice parameter (DLP) model suggested by Stringfellow [39]. Finally, it shows that the thermodynamic analysis provides a useful guideline for the growth of ZnSxSe1-x alloy on Si and GaAs substrates.

The Earth’s atmosphere is a vulnerable system which is easily changed by micro- and macrophysical variations. Big decreases in pollution levels of sulfur dioxide over Central Europe from 1980s to 2000s led to decreased mass concentration of atmospheric solid and liquid particles. This gives the opportunity to investigate how these particles influence the atmosphere. Newly released satellite climatology data was used to analyze statistics of cloud properties during four years in the high polluted atmosphere (1985-88) and four years in the less polluted atmosphere (2004-07). These two periods were investigated in collaboration with Atmospheric Remote Sensing Unit of the research department of the Swedish Meteorological and Hydrological Institute (SMHI). Cloud top temperature of liquid clouds over polluted regions during the earlier period was colder by more than 2 K and more than 5 K for only optical thin liquid clouds. The changes in mass concentrations of atmospheric particles derived by the sulfur dioxide emissions are shown to be a highly possible factor to the observed cloud changes. / Jordens atmosfär är ett känsligt system som lätt förändras av mikro- samt makrofysikaliska variationer. Stora minskningar i föroreningsnivåer av svaveldioxid över centrala Europa från 1980 till 2000-talet ledde till minskade masskoncentrationer av fasta och flytande atmosfäriska partiklar. Detta ger en möjlighet att undersöka hur dessa partiklar påverkar atmosfären. Nyligen utvecklad klimatologisk satellitdata användes för att analysera statistik av molnegenskaper under fyra år i en högt förorenad atmosfär (1985-88) och fyra år i en mindre förorenad atmosfär (2004-07). De två perioderna undersöktes i samarbete med Enheten för atmosfärisk fjärranalys av forskningsavdelningen till Sveriges meteorologiska och hydrologiska institut (SMHI). Molntopptemperaturen för moln i vätskefas över förorenande områden under den tidigare perioden var mer än 2 K kallare och mer än 5 K kallare för endast optiskt tunna moln i vätskefas. Förändringarna i masskoncentrationer för atmosfäriska partiklar och droppar med svaveldioxidusläpp som ursprung visas vara högst möjliga att ligga bakom de observerade molnförändringarna.

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1994. / Vita. Abstract. Includes bibliographical references (leaves 101-103). Also available via the Internet.

Thesis (M.S.)--University of Akron, Dept. of Chemical Engineering, 2006. / "December, 2006." Title from electronic thesis title page (viewed 06/02/2008) Advisor, J. Richard Elliott; Committee members, George G. Chase, Stephanie T. Lopina; Department Chair, Lu Kwang Ju; Dean of the College, George K. Haritos; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.

Thesis (Ph.D.)--Boston University / The heat capacity (Cp) of four Beta-quinol clathrates of carbon monoxide with y = 0.460, 0.626, 0.752 and 0.810, and of one HBr clathrate with y = 0.811 have been measured from 15 to 300K. Cp for 3C6H4(OH)2 * yCO is found to be a linear function of y. The partial molal heat capacity and entropy of clathrated CO and hte heat capacity and entropy of 3 moles of Beta-quinol have been calculated. The respective values at 298.15K are: Cco = 9.76 +/- 0.8 cal. deg.^-1mol^-1; SCO = 20.94 +/- 0.20 cal. deg.^-1mole^-1; Cp^Q = 98.72 cal. deg.^-1; S^Q = 100.28 cal. deg.^-1. [TRUNCATED]

Orientador: Elias Basile Tambourgi. / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-25T15:10:41Z (GMT). No. of bitstreams: 1 Silva_AndreRodriguesGurgelda_M.pdf: 1839329 bytes, checksum: 62d25f563cc23cf1138031c7be606be8 (MD5) Previous issue date: 2014 / Resumo: O abacaxi, considerado a terceira fruta mais importante do mundo, é utilizado como principal fonte de bromelina, uma enzima com atividade anti-inflamatória e que auxilia no tratamento de queimaduras. Pesquisas recentes indicam possíveis aplicações dessa enzima em terapias oncológicas. Atualmente a purificação de compostos biológicos é um grande desafio para a indústria. A extração em sistemas de duas fases aquosas (SDFA) proporciona um elevado rendimento e fácil ampliação de escala nesse tipo de processo. Dessa forma, esse trabalho visa a caracterização de um SDFA formado por polietilenoglicol (PEG) e sulfato de amônio, utilizando os modelos termodinâmicos NRTL, UNIQUAC, UNIFAC E ASOG. Os dados experimentais foram obtidos a 5°C e 25°C com PEG de peso molecular 2000, 4000 e 6000 e, posteriormente, comparados com os resultados dos modelos indicando uma predominância dos modelos que utilizam o conceito de contribuição de grupos, e dentre estes, se destacou o método UNIFAC obtendo valores com erros próximos a 2% / Abstract: The pineapple, considered the third most important fruit in the world, is used as the main source of bromelain, an enzyme with anti-inflammatory activity and used for burns treatment. Nowadays, several researches show a possible application of this protein for cancer's treatment. In this context, the purification of biological components is an important challenge to industries. The extraction in aqueous two-phase system (ATPS) presents an elevated potential and easy application for this process. Thus, this study aims the characterization of an ATPS composed by Polyethylene Glycol (PEG) and ammonium sulfate, using NRTL, UNIQUAC, UNIFAC and ASOG as thermodynamic models. Experimental data were obtained for temperatures of 5 °C and 25 °C with PEG of different molecular weight (2000, 4000 and 6000) and posteriorly compared to the model's results, which indicated a predominance of those whom employ the group concept for calculating the activity coefficient, emphazing the UNIFAC method which obtained an average error of 2% / Mestrado / Engenharia Química / Mestre em Engenharia Química

Consider a multidimensional shift space with a countably infinite alphabet, which serves in mathematical physics as a classical lattice gas or lattice spin system. A new definition of a Gibbs measure is introduced for suitable real-valued functions of the configuration space, which play the physical role of specific internal energy. The variational principle is proved for a large class of functions, and then a more restrictive modulus of continuity condition is provided that guarantees a function's Gibbs measures to be a nonempty, weakly compact, convex set of measures that coincides with the set of measures obeying a form of the DLR equations (which has been adapted so as to be stated entirely in terms of specific internal energy instead of the Hamiltonians for an interaction potential). The variational equilibrium measures for a such a function are then characterized as the shift invariant Gibbs measures of finite entropy, and a condition is provided to determine if a function's Gibbs measures have infinite entropy or not. Moreover the spatially averaged limiting Gibbs measures, i.e. constructive equilibria, are shown to exist and their weakly closed convex hull is shown to coincide with the set of true variational equilibrium measures. It follows that the "pure thermodynamic phases", which correspond to the extreme points in the convex set of equilibrium measures, must be constructive equilibria. Finally, for an even smoother class of functions a method is presented to construct a compatible interaction potential and it is checked that the two different structures generate the same sets of Gibbs and equilibrium measures, respectively.