Orientadores: Florencia Cecilia Menegalli, Maria Isabel Rodrigues / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-24T08:01:10Z (GMT). No. of bitstreams: 1 Vissotto_FernandaZaratini_D.pdf: 6786611 bytes, checksum: dffef14262649a8cbe2a7daad1cf4d46 (MD5) Previous issue date: 2014 / Resumo: Os achocolatados em pó são formulados com a mistura de cacau, açúcar, maltodextrina e aromas, podendo conter derivados lácteos. Para se obter uma adequada reconstituição em líquidos, os achocolatados são submetidos aos processos de lecitinação (adição de um agente tensoativo: lecitina de soja) e aglomeração com vapor. Um dos objetivos desse estudo foi o de avaliar os efeitos das variáveis do processo de aglomeração com vapor (pressão do vapor, temperatura do secador rotativo, vazão de sólidos da alimentação e frequência de rotação do secador) sobre as características físicas e físico-químicas de achocolatados em pó. A aglomeração com vapor levou a um aumento do diâmetro médio de partículas, sendo mais pronunciado no produto formulado com o açúcar moído. O processo foi responsável pelo escurecimento e redução da umidade dos achocolatados, além da diminuição dos tempos de molhabilidade. Adicionalmente foi caracterizada a morfologia dos grânulos de achocolatado, obtidos em diferentes condições operacionais do aglomerador (máxima, média e mínima), utilizando os descritores de tamanho e forma. Os resultados mostraram que não existe diferença entre os descritores de forma e quanto aos descritores de tamanho verificou-se diferença entre as condições de processo para grânulos maiores que 600 ?m. Concluiu-se que os grânulos de achocolatado aglomerados apresentaram formato alongado. Foram também determinadas as transições de fase e as temperaturas de transição vítrea (Tg) de achocolatados em pó e dos seus principais constituintes. Durante a aglomeração com vapor a alta temperatura levou o açúcar moído a uma condição acima da sua Tg, passando a ser esse componente um veículo para a granulação. A Tg da maltodextrina é pequena em atividades de água elevadas (Tg= - 4,9 °C; Aa= 0,843), o que também a torna um veículo para o processo de aglomeração. No cacau em pó alcalino foi observada a fusão da manteiga de cacau (aparecimento das formas polimórficas ?v e ?). Para o achocolatado lecitinado verificou-se que a Tg aumenta com o incremento da atividade de água do meio, portanto para esse tipo de produto a água, ao ser adsorvida, não consegue interagir com o material, não sendo verificado o efeito plasticizante. Para o achocolatado aglomerado com vapor verificou-se que a Tg diminuiu com o aumento da atividade de água do meio (efeito plasticizante). A evolução do caking dos constituintes dos achocolatados mostrou que o cacau em pó apresentou baixa higroscopicidade (pequeno aumento do ângulo de repouso com o tempo), pequena formação de aglomerados e a ausência do caking. A medida da força de compressão dos agregados formados mostrou que a sacarose formou pontes mais rígidas entre as partículas que a maltodextrina. Foi também monitorada a estabilidade de achocolatados em pó lecitinados e aglomerados com vapor, estocados a 25 e 35 °C, numa umidade relativa de 84%, buscando-se simular um clima quente e úmido (região norte do Brasil). Ao longo do tempo, verificou-se aumento do ângulo de repouso e escurecimento dos produtos. O achocolatado lecitinado mostrou-se mais susceptível ao empedramento que o aglomerado, com a formação de grumos a partir do 63° dia de armazenamento / Abstract: Cocoa beverage powders consist of a mixture of cocoa, sugar, maltodextrin, flavors, and may contain dairy products. To obtain products with adequate reconstitution in liquids, the cocoa beverage powders are subjected to the processes of lecithination (addition of the surfactant soy lecithin) and steam agglomeration. One objective of this study was to evaluate the effects of the main variables of the steam agglomeration process (vapor pressure, temperature of rotary dryer, solid feed rate and dryer rotation frequency) on the physical and physicochemical characteristics of cocoa beverage powders. The steam agglomeration led to an increased average particle diameter, being more pronounced in the product formulated with granulated sugar. The process was responsible for powder darkening, reduction of the product¿s moisture and decrease in the wettability. Additionally, the morphology of the cocoa beverage powder granules was characterized in different operating conditions of the steam agglomerator (maximum, average and minimum) using the descriptors of size and shape. There were no differences between the shape descriptors and as to the size descriptors there were differences in the process conditions studied for the granules of size above 600 ?m. It was observed that the steam agglomerated cocoa beverage granules had a more elongated shape. It was also determined phase transitions and the glass transition temperature (Tg) of cocoa beverage powders and the main constituents of these products. During the steam agglomeration, the high temperature led the granulate sugar to a condition above its Tg, making this ingredient a granulation vehicle. The Tg of maltodextrin is small at higher water activities (Tg = - 4.9 °C, aw = 0.843), which makes this ingredient a vehicle for the agglomeration process. For the alkaline cocoa powder the phase transition observed is the melting of the cocoa butter with the appearance of polymorphic forms ? and ?v. For the lecithinated cocoa beverage powder, it was verified that the Tg increases with the increasing of the water activity, which leads to the conclusion that for this type of product the adsorbed water cannot interact with the material, and the plasticizing effect is not noted. For the steam agglomerated cocoa beverage powder it was observed that the Tg decreases with increasing water activity (plasticizing effect). The evolution of the caking for the constituents of cocoa beverage powders showed that the cocoa powder had low hygroscopicity (small increase of the repose angle with time), little formation of granules and the absence of caking. The measurement of the compression strength of the aggregates showed that sucrose formed bridges more rigid between the particles than maltodextrin. Stability of lecithinated and steam agglomerated cocoa beverage powders stored at 25 and 35 °C, in a relative humidity of 84%,was also monitored, in order to simulate hot and humid climates (like northern Brazil). Overtime, it was observed increase of the repose angles and products darkening. The lecithinated cocoa beverage powder was more susceptible to caking than the steam agglomerated product, with the formation of lumps from the 63th day of storage / Doutorado / Engenharia de Alimentos / Doutora em Engenharia de Alimentos

L’objectif de la thèse est de fabriquer des structures catalytiques washcoatées de taille centimétrique pour différentes réactions catalytiques comme le vaporeformage et le pré-reformage, le SNG (Substitute Natural Gas) et le MTP (Methanol to Propylene). L’étude de l’utilisation de ces structures alternatives aux catalyseurs extrudés conventionnels utilisés dans l’industrie est la conséquence des contraintes opératoires (gradients de pression et de température) et leur influence sur les coûts opératoires (endommagement des matériaux, désactivation des catalyseurs, perte de charge dans les réacteurs, etc.). Le dépôt des catalyseurs sur les architectures céramiques et métalliques a été possible grâce à l’étude minutieuse du comportement des solides catalytiques en suspension dans un milieu liquide. Le contrôle de paramètres comme la chimie de surface et la rhéologie a été nécessaire pour acquérir une maîtrise nécessaire afin d’obtenir des pièces catalytiques avec un dépôt homogène, stable mécaniquement et non fissuré. / L’objectif de la thèse est de fabriquer des structures catalytiques washcoatées de taille centimétrique pour différentes réactions catalytiques comme le vaporeformage et le pré-reformage, le SNG (Substitute Natural Gas) et le MTP (Methanol to Propylene). L’étude de l’utilisation de ces structures alternatives aux catalyseurs extrudés conventionnels utilisés dans l’industrie est la conséquence des contraintes opératoires (gradients de pression et de température) et leur influence sur les coûts opératoires (endommagement des matériaux, désactivation des catalyseurs, perte de charge dans les réacteurs, etc.). Le dépôt des catalyseurs sur les architectures céramiques et métalliques a été possible grâce à l’étude minutieuse du comportement des solides catalytiques en suspension dans un milieu liquide. Le contrôle de paramètres comme la chimie de surface et la rhéologie a été nécessaire pour acquérir une maîtrise nécessaire afin d’obtenir des pièces catalytiques avec un dépôt homogène, stable mécaniquement et non fissuré.

Whether the activity of creating digital art influences high school students' attitudes toward science is unknown. The purpose of this study was to determine if the creation of artistic digital chemoscans by high school students influences their attitudes toward science. In this study, ninth grade high school students' attitudes toward science were examined after participating in the creation of chemoscans in their science classroom. The theory of affective domain helped explain the process that leads to a person's behavior toward a certain phenomenon in the educational setting. The research questions concerned the use of chemoscan creation in the physical science classroom and if and whether implementation effected a change in students' attitudes toward science. Archival pre- and posttest data from the Test of Science Related Attitude was used to measure high school students' attitudes toward science in 7 categories. Archived student pre- and posttest data were treated with multiple regression for analysis. Key findings of this study showed that creation of artistic digital chemoscans (a) impacted one of the seven subscales of science attitude from the Test of Science related Attitude entitled attitude toward the normality of scientists, (b) did not have an impact on the any of the other six subscales from the TOSRA and (c) was influenced by teacher effect. This study may contribute to social change by providing improved training for science teachers who implement digital art activities, which may lead to some students enjoying science more and then possibly going into science careers.

The purpose of the thesis is to create a model for an analysis of a steam conditioning valve whose function is to reduce the temperature of the steam using a spray water system. First of all, simulation of the fluid flow and heat transfer is done using CFD analysis. Then the results are used for thermal stress calculation.

The content of this thesis is the design of a condensing steam turbine with an output of 80 MWe to a waste incinerator with impulse blading. In this work are elaborated proposals and calculations of balancing schemes, which are used in the next part of the work as a foundation for calculation of the blades part of the turbine. The blades part is designed for two operations - for full condensing operation and for full demand operation. The turbine should contain one process offtake and three unregulated offtakes. Besides that, the thesis solves basic strength control. The thesis is finished with a technical drawing of the longitudinal cut of the turbine.

The master thesis deals with design and comparison of condensing steam turbine for steam-gas cycle for single-cylinder and double-cylinder body with air condenser at its end, one regulated take and ability to use additive steam. Thesis is based on the calculation of thermal scheme which is followed by a preliminary and subsequently a detailed design of steam turbine. Thermodynamic efficiency for single-cylinder turbine was calculated at 93,28 % with terminal power 136,2 MW. The design procedure was repeated for a double-cylinder body. Calculated terminal power for two-cylinder turbine was 134,4 MW with thermodynamic efficiency of 92.1%. By dividing turbine into two rotors resulting low-pressure turbine has a smaller rotor diameter, a longer blade and at the same time a larger number of stages. For double-cylinder turbine, it was necessary to consider twice the number of seals and radial bearings. Due to the increase in flow diameter of low-pressure turbine, losses related to the geometry of the stage increased. Thesis is supplemented by a section drawing of steam turbine with higher efficiency.

This thesis concerns with recalculation of steam boiler. Arrangement for reaching of new steam boiler parameters and temperature of combustion gases was suggested at first. Then it was verified with thermal calculation, all necessities included.

Thesis deals with oil-turbine frame of the model SST 300 SST 400. This work is divided into several parts. Beginning of this thesis deals with a description of the problem and the oil economy. Next part is concerned with 3D design model of the oil tank in the program ProEngineer Wildfire 2.0. Final part describes a creation of manufacturing drawings with BOMs. In conclusion, the thesis presents the results of additional topics, such as a computational model in Ansys 11 and making the calculation of tension or bonds in an oil suspension in the frame. The result of this work is the full-fledged design of the weldment of oil frame, which was submitted for approval to the Siemens Company, which will continue in the subproject tasks of new turbo model SST 300 pattern SST 400.

The aim of this thesis is to design a surface condenser with lateral exhaust. A research in the field of surface condensers with lateral exhaust takes place before the design. Core of the thesis is a thermodynamic design of the heat exchanger, calculation of pressure losses on the side of coolant water, check of the tube bundles from standpoint of oscillation and a design of air removal pipeline. Finally a design of the condenser is supported with a drawing attached in the supplement.

The Diploma Thesis deals with a design of a backpressure turbine without any bleeds. The fundament of the Diploma Thesis is a thermodynamical calculation of particular parts of the turbine. Technical solutions are designed according to given details of a steam and chosen conditions of use.