Orientador: José Vicente Hallak d'Angelo / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-23T08:54:55Z (GMT). No. of bitstreams: 1 Araujo_HugoValenca_M.pdf: 2457535 bytes, checksum: cf5a800ee51a5605b7d2cd69248ef52c (MD5) Previous issue date: 2013 / Resumo: A refrigeração e o condicionamento de ar representam um campo tecnológico em potencial para a adoção de medidas de economia de eletricidade. Nesse sentido, Sistemas de Refrigeração por Absorção (SRAs) figuram como uma opção interessante por serem adequados à produção de frio mediante um gasto significativamente menor de energia elétrica em comparação a Sistemas de Refrigeração por Compressão Mecânica (SRCMs) de vapor. Com a finalidade de gerar o efeito de refrigeração, o SRCM realiza uma compressão mecânica de vapor à custa do consumo de trabalho elétrico em um compressor; em contrapartida, a compressão no SRA é de natureza termofísica/química e promovida por energia térmica. No segmento de açúcar e álcool brasileiro, a etapa determinante da produção de etanol a partir da cana consiste na fermentação alcoólica do mosto em dornas. Tal etapa é exotérmica e, uma vez que a elevação descontrolada da temperatura desfavorece a produção de álcool, há a necessidade de remover o calor gerado por meio do resfriamento do meio em fermentação. Dessa forma, o objetivo geral do presente trabalho foi simular e analisar o desempenho termodinâmico (energético, COP, e exergético, ?ex) de SRAs com diferentes configurações, trabalhando com o par água/brometo de lítio (H2O/LiBr) e que satisfaçam a carga de refrigeração demandada por um processo fermentativo. Adicionalmente, um dos objetivos específicos foi investigar o risco de ocorrência da cristalização do LiBr, a qual resulta em depósitos, com o auxílio da curva de equilíbrio sólido-líquido (solubilidade) do par H2O/LiBr. As análises dos efeitos de variáveis de projeto e operação (realizadas no software Engineering Equation Solver - EES) demonstraram que os valores de COP das configurações de SRAs de duplo efeito são significativamente maiores do que aquele da configuração de simples efeito; no entanto, as eficiências exergéticas de todas as configurações são equiparáveis, o que pode ser atribuído à quantidade e à qualidade da energia térmica consumida nos respectivos geradores de primeiro efeito. Baixos desempenhos de Segunda Lei são devidos principalmente ao absorvedor, pois esse equipamento apresenta os maiores defeitos de eficiência em todos os SRAs estudados. Adicionalmente, avaliou-se a dependência do desempenho termodinâmico quanto às efetividades de trocadores de calor intermediários, a diferenças de pressão operacional e à cessão direta de calor externo a geradores de segundo efeito. Entre outros resultados, observou-se a existência de máximos do COP e da ?ex em função da temperatura no gerador de primeiro efeito. No que se refere à possibilidade de precipitação do LiBr, verificou-se menor iminência no SRA de duplo efeito com fluxo em paralelo. Em particular, observou-se que aumentos excessivos da temperatura no gerador de primeiro efeito, além de não favorecerem o desempenho termodinâmico, tornam o risco de cristalização do LiBr mais significativo / Abstract: Refrigeration and air conditioning represent a potential technological field for the adoption of measures to save electricity. In this way, Absorption Refrigeration Systems (ARSs) are an interesting option because they are suitable for the production of cold utilities with a significantly lower cost of electric power compared to Mechanical Compression Refrigeration Systems (MCRSs). In order to generate the cooling effect, the MCRS performs a mechanical vapor compression at the expense of the consumption of electrical work in a compressor. On the other side, the nature of the compression in ARSs is thermo physical/chemical and this process is promoted by thermal energy. In the Brazilian sugar and ethanol industry, the main stage of ethanol production from sugarcane is the alcoholic fermentation in vats. This stage is exothermic and since the uncontrolled elevation of temperature results in disadvantages to the ethanol production, it is necessary to remove the heat generated by the cooling of the fermentation medium. Thus, the general objective of this study was to simulate and analyze the thermodynamic performance (energy, COP, and exergy, ?ex) of ARSs with different configurations, working with the water/lithium bromide (H2O/LiBr) mixture, and satisfying the cooling load demanded by a fermentation process. Additionally, one of the specific objectives was to investigate the risk of LiBr crystallization, resulting in deposits, with the aid of the solid-liquid equilibrium (solubility) curve of the H2O/LiBr mixture. Analyses of the effects of design and operating variables (executed in the software Engineering Equation Solver - EES) have shown that the values of COP of the double effect configurations are significantly greater than that of the simple effect configuration; however, the exergetic efficiencies of all configurations are comparable, which can be attributed to the quantity and the quality of the energy consumed in the respective first effect generators. Low Second Law performances are mainly due to the absorber because this equipment has the highest efficiency defects in all ARSs studied. Additionally, it was evaluated the dependence of the thermodynamic performance regarding to the effectivenesses of intermediate heat exchangers, the differences in operating pressures and the direct supply of external heat to second effect generators. Among other findings, it was observed the existence of maximums of COP and ?ex as functions of the temperature in the first effect generator. With regard to the possibility of LiBr precipitation, it was verified lower imminence in the double effect ARS with parallel flow. In particular, it was observed that excessive rises in the temperature in the first effect generator, besides not favor the thermodynamic performance, makes the risk of LiBr crystallization more significant / Mestrado / Sistemas de Processos Quimicos e Informatica / Mestre em Engenharia Química

Orientadores: Everson Alves Miranda, Pedro de Alcântara Pessôa Filho / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-24T01:51:47Z (GMT). No. of bitstreams: 1 Hirata_GiseleAtsukoMedeiros_D.pdf: 4140620 bytes, checksum: 01025f5b18791e6b6698c34eea1dcda4 (MD5) Previous issue date: 2013 / Resumo: O segundo coeficiente virial osmótico, B22, tem sido considerado um preditor para o processo de cristalização. Uma faixa relativamente estreita de valores negativos de B22, -1x10-4 a -8x10-4 mL.mol/g2, é ideal à formação de cristais de acordo com George e Wilson (1994). Essa faixa de valores de B22 é denominada de "janela de cristalização", sendo utilizada para classificar condições adequadas de solvente à formação de cristais. Para valores maiores que -1x10-4 mL.mol/g2, a interação proteína-proteína não é suficientemente forte para a cristalização e nenhuma fase sólida é formada, enquanto para valores menores que -8x10-4 mL.mol/g2, as interações proteína-proteína são muito intensas e precipitados amorfos são formados. Dessa forma, os valores de B22 se tornaram um critério de seleção para a cristalização de proteínas, uma vez que esse coeficiente pode ser determinado por diversos métodos. Este trabalho teve como objetivo determinar experimentalmente diagramas de fases de proteínas (lisozima, insulina suína e bovina) e identificar nesses diagramas, através de análise dos valores do B22, as condições nas quais ocorre a formação de precipitado amorfo, cristalino ou outras fases (por exemplo, fase líquida). O "salting-out" foi o método escolhido para precipitar as proteínas, pois é considerado um dos mais simples e importantes métodos para induzir a cristalização. O sal volátil carbamato de amônio foi o agente de "salting-out" escolhido. As técnicas de espalhamento de luz estático (SLS) e cromatografia de auto-interação (SIC) foram usadas para determinar os valores de B22 para as proteínas em diferentes soluções aquosas de sal a 15 e 25 °C. O fenômeno de "salting-out" foi observado nos diagramas para as três proteínas estudadas. Valores negativos de B22 e altos valores da constante de "salting-out" - entre 1,07 a 3,77 kg/mol - confirmaram que o sal volátil carbamato de amônio empregado neste estudo é um bom agente precipitante. Os valores do B22 para a insulina suína (-250x10-4 a -18x10-4 mol.ml/g2 a 25 °C e -187x10-4 a -45,2x10-4 mol.ml/g2 a 15 °C) e insulina bovina (-999x10-4 a 6,7x10-4 mol.ml/g2 a 25 °C e -533x10-4 a -16,7x10-4 mol.ml/g2 a 15 °C) indicaram a precipitação, o que também foi confirmado pelos ensaios de cristalização. Já para a lisozima, obteve-se formação de cristais independente do valor de B22 encontrado (-20,4x10-4 a -3,6x10-4 mol.ml/g2 a 25 °C e -400x10-4 a -14,4x10-4 mol.ml/g2 a 15 °C). Além disso, os modelos teóricos disponíveis na literatura utilizados para a obtenção de uma estimativa do parâmetro B22 são adequados e válidos para as condições em que a medida experimental não é possível, podendo ser aplicados para o sistema proteína/sal volátil. Dessa forma, este trabalho mostrou que não existe uma "janela de cristalização universal" válida para todos os sistemas e o uso do sal volátil carbamato de amônio como agente de cristalização é uma alternativa ao uso de sais convencionais. / Abstract: The osmotic second virial coefficient, B22, has been used as a predictor of crystallization. A relatively narrow range of negative B22 values, -1x10-4 to -8x10-4 mL.mol/g2, is the ideal range for crystal formation according to George and Wilson (1994). This range, referred to as the "crystallization slot", has been used to classify suitable conditions under which proteins will assemble into crystals. For B22 values greater than -1x10-4 mL.mol/g2, the protein-protein interaction is very weak and no solid phase is formed, while for values less than -8x10-4 mL.mol/g2, the protein-protein interactions are very intense and amorphous precipitates are formed. Thus, the B22 value has become a selection criterion for protein crystallization, since this coefficient can be determined by various methods. This study aimed to determine the experimental phase diagrams for proteins (lysozyme and bovine and porcine insulin) and to identify those diagram conditions under which amorphous precipitate, crystals or other phases (for example, liquid phase) are formed, based on the values of B22. The salting-out method to precipitate proteins was chosen because it is considered one of the simplest and most important methods to induce crystallization. The volatile salt ammonium carbamate was chosen as the salting-out agent. Traditional static light scattering (SLS) and the novel self-interaction chromatography (SIC) technique were used to determine B22 values for the proteins in different aqueous salt solutions at 15 and 25 °C. The salting-out phenomenon was observed in the phase diagrams for the three proteins studied. Negative B22 values and high values of the salting-out constant - between 1.07 to 3.77 kg/mole (Cohn, 1925) - confirmed that ammonium carbamate was a good precipitant agent. The B22 values for porcine (-250x10-4 to -18x10-4 mol.ml/g2 at 25 °C and -187x10-4 to -45.2 x10-4 mol.ml/g2 at 15 °C) and bovine (-999x10-4 to 6.7x10-4 mol.ml/g2 at 25 °C and -533x10-4 to -16.7x10-4 mol.ml/g2 at 15 °C) insulin indicated precipitation that was confirmed experimentally. However, lysozyme was obtained as crystals, regardless of the B22 values found (-20.4x10-4 to -3.6 x10-4 mol.ml/g2 at 25 °C and -14.4x10-4 to -400x10-4 mol.ml/g at 15 °C). In addition, thermodynamic models available in the literature and suitable for the conditions under which experimental measurements were done provided a good fit to the data. Thus, this work showed that there is no universal "crystallization slot" applicable to all systems and that for crystallization agent, volatile salt ammonium carbamate can serve as an alternative to conventional salts. / Doutorado / Desenvolvimento de Processos Biotecnologicos / Doutora em Engenharia Quimica

Orientadores: Theo Guenter Kieckbusch, Valdecir Luccas / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-24T05:00:36Z (GMT). No. of bitstreams: 1 Miyasaki_EriksenKoji_M.pdf: 5704488 bytes, checksum: 8c68d44e4acedc12c047e6f34e53701d (MD5) Previous issue date: 2013 / Resumo: As lecitinas modificadas de soja estão sendo introduzidas no processamento de chocolates como alternativa à lecitina padrão para melhorar as propriedades reológicas e de cristalização. A influência da adição de 0,2 a 0,8% (m/m) de lecitinas hidrolisada enzimaticamente, hidroxilada, em pó e acetilada na cristalização da manteiga de cacau foi avaliada. No chocolate, foram adicionadas as lecitinas hidrolisada enzimaticamente e hidroxilada nas concentrações de 0,1 a 0,3% (m/m). Os resultados, para ambos os casos, foram comparados com as amostras contendo lecitina padrão. Para quantificar o efeito destes aditivos foram determinadas as propriedades de fusão e de cristalização por DSC, as características reológicas utilizando um reômetro, a cinética de cristalização usando um Espectrômetro de Ressonância Magnética Nuclear, e o temper index por meio de um temperímetro. Barras de chocolate foram armazenadas a 25°C por 62 dias com o monitoramento dos eventos de fusão por DSC, de textura por texturômetro, das transformações polimórficas por difração de Raios-X e do desenvolvimento de fat bloom por Microscopia Eletrônica de Varredura. A adição de emulsificantes na manteiga de cacau e no chocolate promoveu uma aceleração da cristalização, mas apenas nas concentrações mais baixas. A adição de lecitinas modificadas à manteiga de cacau diminuiu a temperatura máxima de fusão e aumentou a entalpia de cristalização e de fusão. O uso de lecitinas modificadas no chocolate não apresentou vantagens em termos reológicos, se comparadas ao de lecitina padrão. No armazenamento, algumas amostras com lecitinas modificadas foram capazes de retardar a transição polimórfica e a forma VI foi obtida apenas na amostra contendo 0,2% de lecitina padrão. No geral, a transição polimórfica foi antecipada usando maior concentração de lecitina padrão e de lecitina hidrolisada, e retardada com maior quantidade de lecitina hidroxilada. As propriedades de fusão não apresentaram uma tendência definida ao longo do tempo e com a variação de concentração dos emulsificantes. A tensão de ruptura aumentou em chocolates com menores concentrações de lecitinas e uma diminuição significativa desta resistência foi observada a partir de 21 dias de armazenamento nos chocolates com maiores concentrações de emulsificantes. O desenvolvimento do fat bloom não apresentou uma causa única, ocorrendo com e sem transição de fases, e não foi encontrada correlação definida com o tamanho médio de partículas e o índice de temperagem. / Abstract: Modified soy lecithins are being introduced in chocolates processing as an alternative to standard lecithin to improve the rheological characteristics and the crystallization patterns. The influence of the amount added (0.2 to 0.8% (w/w)) and the types of these new additives (hydroxylated, enzymatically hydrolyzed, acetylated, defatted or powder lecithins) on cocoa butter was evaluated. In dark chocolate, enzymatically hydrolyzed and hidroxilated lecithin were added at concentration of 0.1 to 0.3%(w/w) to evaluate mass crystallization. The results in both cases were compared to samples containing standard lecithin. The influence of the addition of lecithins was quantified by determining the melting and crystallization events with a DSC, the rheological characteristics using a rheometer, the crystallization kinetics using a Nuclear Magnetic Resonance Spectrometer, the temper index using a temperimeter. Chocolate bars were stored for 62 days at 25°C, monitoring their melting properties by DSC, texture properties with a texturometer, the polymorphic events by X-rays diffraction and the fat bloom development by Scanning Electron Microscopy. The addition of the emulsifiers to cocoa butter and chocolate accelerated the fat crystallization rates, but only at the lower concentrations. The use of modified lecithins in cocoa butter decreased the maximum melting temperature and increased the crystallization and melting enthalpies. No rheological improvements were detected with the use of modified lecithins in chocolates, compared to the addition of standard lecithin. During the storage period, some chocolates with modified lecithins were able to restrain polymorphic transitions and the polymorphic form VI was only achieved in chocolates containing 0.2 % of standard lecithin. As a general trend, increasing concentrations of standard or hydrolyzed lecithins in dark chocolates anticipate the polymorphic transitions and increasing amount of hydroxylated lecithins delayed these events. No correlation was found between the melting properties with the storage period and with the emulsifier's concentration. Increasing values of mechanical resistance (snap test) were detected in chocolates with the lowest lecithin concentrations and a significant decrease was observed in chocolates with the highest lecithin concentrations after 21 days of storage. The fat bloom development showed no single cause, occurring with and without phase transitions, and there was no clear correlation with the mean particle size and the temper index. / Mestrado / Engenharia de Processos / Mestre em Engenharia Química

Orientadores: Theo Guenter Kieckbusch, Ana Paula Badan Ribeiro / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-19T03:57:53Z (GMT). No. of bitstreams: 1 Oliveira_GlazieliMarangoni_M.pdf: 37166380 bytes, checksum: d530fd83010bcc0c3c08c7f68ff9ac52 (MD5) Previous issue date: 2011 / Resumo: A palma (Elaesis guineensis) e uma das principais fontes de óleos vegetais, sendo o óleo de palma amplamente utilizado na industria de alimentos, como por exemplo, na produção de chocolates. Entretanto, sua utilização para este fim e limitada por seu polimorfismo ß' preferencial, lenta cristalização e formação de grandes aglomerados cristalinos na etapa de pós-processamento. Como alternativa de adequações destas propriedades para aumentar a compatibilidade com a manteiga de cacau, esta pesquisa avaliou a adição de gorduras totalmente hidrogenadas (hardfats) a amostras comerciais de óleo de palma. Os hardfats apresentam composição triacilglicerólica homogênea e bem definida, com triacilgliceróis (TAGs) de alto ponto de fusão, desejável na obtenção de chocolates de boa qualidade. Alem disso, os hardfats podem atuar como moduladores do processo de cristalização, agindo como núcleos preferenciais no processo de ordenação da rede cristalina e como indutores de hábitos polimórficos específicos. O presente trabalho estudou cinco distintos hardfats no óleo de palma, são eles: palmiste (PMTH), palma (PATH), algodão (AGTH), soja (SJTH) e crambe (CRTH). Misturas com 1%, 3% e 5%, de cada hardfat, originaram quinze diferentes combinações de gorduras. Os resultados obtidos por analises de composições de ácidos graxos e triacilgliceróis, assim como as isotermas de cristalização e teor de sólidos obtidos por RMN e, as analises térmicas, realizadas por intermédio de um Calorímetro Diferencial de Varredura (DSC), indicam que o uso de hardfats com cadeias alquilas similares ao do óleo de palma, como PATH e AGTH, proporciona maior compatibilidade na estrutura cristalina e consequentemente melhor empacotamento. A adição de hardfats, que apresentam na composição química, ácidos graxos de cadeias maiores, como a SJTH e CRTH, influenciaram significativamente na aceleração da cristalização do óleo de palma e na redução do tamanho dos cristais, proporcionando maior dureza destas formulações. Todas as misturas mostraram preferência de cristalização de hábitos cristalinos ß', mas as misturas com os SJTH e CRTH, entretanto formaram uma miscelânea de Cristais ß'+ß. A adição destes hardfats provavelmente aumentara a resistência térmica de chocolates. Tomando-se por base este conjunto de resultados, sugere-se a aplicação dos hardfats de algodão e soja, na proporção de 5% e o hardfat de crambe na proporção de 1%, no óleo de palma visando a aplicação em chocolates por meio da substituição parcial da manteiga de cacau / Abstract: Palm threes (Elaesis guineensis) are one of the main sources of industrial vegetable oils. Palm oil, extracted from the pulp of the fruit is widely used in the food industry, as for instance, in the production of chocolates. However, in many applications the amount of palm oil added is restricted by its preferential ß'- polymorphism, slow crystallization rates and formation of large crystalline clusters in the stage of postprocessing. In this research the addition of fully hydrogenated vegetable oils (hardfats) to industrial palm oil samples was evaluated aiming the adjustment of those attributes in order to increase the compatibility with cocoa butter. Hardfats can behave as modulators in the crystallization process and are able to induce specific polymorphic habits due to their homogeneous triacylglicerols profile. Five different hardfats were added to palm oil, in the proportion of 1%, 3% and 5%: palm kernel (FHPKO), palm (FHPO), cottonseed (FFHCO), soybean (FHSO) and crambe (FHCR), rendering fifteen fat mixture formulations. Results obtained through GC analyses for the fatty acids and triacylglycerols profiles, as well as crystallization isotherms and solid fat content by NMR and also thermal analysis using a Differential Scanning Calorimeter (DSC) indicate that the use of hardfats like FHPO and FHCO that have carboxylic chain lengths similar to palm oil implements the compatibility of their mixture with cocoa butter. The addition of hardfats with longer chains like FHSO and FHCR showed significant effect on the increase of the rate of crystallization of palm oil and in the reduction of the crystals size inducing higher hardness to these formulations. All the mixtures showed a preference for the ß'-polymorphism, except for the mixtures with FHSO and FHCR, which produced an assortment of ß'+ ß crystal habits. The addition of these hardfats will probably increase the thermal resistance of chocolates. It is suggested the application of hardfats of cottonseed and soybean in the proportion of 5% and hardfat of crambe in the proportion of 1% in palm oil aiming the application in chocolate by partial substitution of cocoa butter / Mestrado / Engenharia de Processos / Mestre em Engenharia Química

Orientador: Lireny Aparecida Guaraldo Gonçalves / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-21T23:51:40Z (GMT). No. of bitstreams: 1 Oliveira_IngridFrancode_M.pdf: 12512639 bytes, checksum: 63474efdec388007cba17547f09ce8c9 (MD5) Previous issue date: 2013 / Resumo: Gorduras equivalentes de manteiga de cacau (CBEs) são utilizadas nas formulações de chocolates, substituindo parte da manteiga de cacau (MC). Embora as CBEs sejam compatíveis com a MC é importante um estudo detalhado a fim de se conhecer as propriedades de cristalização, fusão e estabilidade dos cristais, uma vez que as mesmas alteram a qualidade dos chocolates. Este estudo objetivou aumentar o conhecimento sobre CBEs e propor alteração do comportamento de fusão e cristalização de uma CBE escolhida. Sendo assim, foram caracterizadas quatro CBEs, com base em uma MC usada como padrão. As análises utilizadas para a caracterização foram índices de qualidade e de identidade, composição em ácidos graxos, índice de iodo, índice de saponificação, ponto de fusão, teor de sólidos por Ressonância Magnética Nuclear (RMN), isoterma de cristalização a 17,5°C por RMN, eventos de cristalização por Calorimetria Diferencial de Varredura (DSC), eventos de fusão por DSC em quatro tempos de armazenamento a 25°C (0, 4, 8 e 24 horas) e análise por difração de Raios-X. Adicionou-se 0,3% de triestearato de sorbitana (STS) às CBEs e o efeito do STS foi avaliado por meio de isotermas a 17,5°C, eventos de fusão por DSC em quatro tempos de armazenamento a 25°C (0, 4, 8 e 24 horas) e análise por difração de Raios-X. Ao final do estudo, foram elaboradas três formulações de chocolate: chocolate com 12% de MC, chocolate com 12% de CBE e chocolate com 12% de CBE com adição de 0,3% STS. Os chocolates foram avaliados quanto à viscosidade plástica, limite de fluidez, evento de fusão, tensão de ruptura (snap test) e microscopia eletrônica de varredura (MEV). A MC e as CBEs estudadas apresentaram-se dentro dos padrões de qualidade e identidade e os teores de ácidos graxos e triacilgliceróis analisados individualmente diferiram, destacando que as CBEs apresentaram maiores discrepâncias nos teores de POP (1, 3 palmitoil oleoil glicerol) e SOS (1,3 estearoil oleoil glicerol). As amostras apresentaram diferentes comportamentos de fusão, cristalização, estabilização e polimorfismo. O uso de STS promoveu elevação das curvas de cristalização a 17,5°C acarretando em perfis mais similares ao da MC em duas CBEs, embora não tenha alterado o polimorfo final das amostras após a estabilização. O uso de 0,3% STS em chocolate promoveu elevação do snap, embora não tenha sido verificada alteração na viscosidade plástica e no limite de fluidez dos chocolates. Diferentes estruturas foram visualizadas nas imagens realizadas em MVE / Abstract: Cocoa butter equivalent (CBEs) are used in chocolate formulations, replacing part of the cocoa butter (CB). Although there is compatibility between CBEs and cocoa butter, it is important a detail study that aims to know the properties of crystallization, melting and stability of the crystals, once it modifies the quality of the chocolate. This study intends to increase knowledge of CBEs and modify the melting and crystallization behavior of a selected CBE. Present study characterized and differentiated four CBEs and a standard CB. Analyzes used for the characterization and differentiation were free fatty acids, peroxide value, fatty acid composition, iodine value, saponification value, melting point, solid fat content by Nuclear Magnetic Resonance (NMR), isothermal crystallization at 17.5 ° C by NMR, crystallization events by Differential Scanning Calorimetry (DSC), fusion events by DSC during storage in four times at 25 ° C (T0 ¿ 0 hour, T1 ¿ 4 hours, T2 - T3 and 8 hours - 24 hours) and analysis by X-rays diffraction. It was added to CBE 0.3% tristearate sorbitan (STS) and the effect of STS addiction was evaluated by isotherms at 17.5 ° C, fusion events by DSC at four times of storage at 25 °C (T0 ¿ 0 hour, T1 ¿ 4 hours, T2 - 8 hours and T3 - 24 hours ) and analysis by X-rays diffraction. At the end of the study, three formulations of chocolates were prepared: chocolate with 12% CB, chocolate with 12% CBE and chocolate with 12% CBE and 0.3% STS. Chocolates were evaluated by plastic viscosity, shear stress, fusion event, texture (snap test) and scanning electron microscopy (SEM). The CB and CBEs studied were within the standards of quality and identity and fatty acids and triacylglycerols analyzed individually differed, emphasizing that the CBEs had differences in the levels of POP (palmitoil oleoil glycerol) and SOS (stearoyl oleoyl glycerol). The samples showed different behaviors melting, crystallization, stabilization and polymorphism. The use of STS caused increase of the crystallization curves at 17.5 ° C resulting in profiles most similar to the CB in two CBEs, although not changed polymorph end of the samples after equilibration. The use of 0.3% STS in chocolate increased the snap, though not verified change in plastic viscosity and fluidity limit of chocolates. Different structures were visualized in the images of SEM / Mestrado / Tecnologia de Alimentos / Mestra em Tecnologia de Alimentos

Orientador: Flávio Vasconcelos da Silva / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-20T15:49:40Z (GMT). No. of bitstreams: 1 Navarro_AlexandreKhaeWu_M.pdf: 4067789 bytes, checksum: 20f4684078783b9a38711e856a726e6e (MD5) Previous issue date: 2012 / Resumo: O controle de distribuições de cristais é de grande importância para a indústria química de alta tecnologia, encontrando especial aplicação na produção de fármacos e alimentos. Nestas indústrias, outra característica é igualmente importante: polimorfismo. Legislações específicas comumente requerem a presença de um determinado tipo de polimorfo. Como o controle para obtenção destas características é de relevância industrial e tipicamente de difícil realização, neste trabalho, foi estudado o controle da cristalização do ácido L-glutâmico por resfriamento visando obter um único polimorfo e maximizar o tamanho dos cristais ao final da batelada. Este tema foi abordado utilizando controle ótimo através de três estratégias diferentes: controle ótimo em malha aberta, controle ótimo em malha aberta com rastreamento de temperatura e concentração e controle ótimo em malha fechada. As otimizações foram realizadas no software Scilab através de um método quasi-newton em esquema sequencial, de forma que os momentos da distribuição de cristais eram simulados e a curva de resfriamento ajustadas com base na simulação. Para lidar com o efeito de dissolução total de um dos polimorfos, característica que não é capturados pelos momentos populacionais, foi utilizado um loop de integração baseado na interpretação física dos valores dos momentos populacionais. Ao final do trabalho, verificou-se que a estratégia de controle ótimo em malha fechada obteve melhores resultados / Abstract: Crystal size distribution control is of great importance to high-end chemical industry, especially in applications to the production of pharmaceuticals and foods. In these industries, another crystal characteristic is equally important: polymorphism. Strict regulations often require that only an specific type of polymorph may be present in a determined product. As controlling these factors is both of industrial relevance and typically difficult, in this work, the control of batch L-glutamic acid crystallization by cooling aiming to obtain one specific polymorph while maximizing crystal size at the end of the operation. This theme was approached by using optimal control and three different strategies: open-loop optimal control, open-loop optimal control with temperature and concentration tracking, and closed-loop optimal control. The optimizations were performed in Scilab through a quasi-newton method in a sequential process so that the moments of the crystal size distribution were simulated and the cooling curves adjusted based on the simulation and the objective. To deal with the total dissolution of one of the polymorphs, a feature not captured by the populational momentts, a special integration loop was used based on the physical interpretation of the moment values. Finalluy, at the end of the study, it was found that the closed-loop optimal control approach provided better results / Mestrado / Sistemas de Processos Quimicos e Informatica / Mestre em Engenharia Química

Orientador: Everson Alves Miranda / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-04T07:13:28Z (GMT). No. of bitstreams: 1 Barros_GeorgiadeOliveiraFigueiredo_M.pdf: 2282903 bytes, checksum: b104323f697a813ec6af57b15ba7b95b (MD5) Previous issue date: 2005 / Resumo: A separação de enantiômetros em altos níveis de pureza enantiomérica é atualmente um requerimento da industria farmacêutica. No entanto, altas purezas estão sendo alcançadas neste sistema com comprometimento da produtividade. O acoplamento do leito móvel simulado (LSM) a uma etapa de cristalização pode resultar num processo de maior produtividade global . A escolha do método de cristalização para a resolução de misturas racêmicas por cristalização é dependente do tipo de cristal (conglomerado ou composto racêmico) e da localização do ponto eutético no diagrama de solubilidade. O ponto eutético difine a mínima puraza enantiomérica que deve ser fornecida pelo LMS para assegurar que a cristalização irá produzir somente um dos enantiômeros puros. A cetamina é um anstésico que possui um isômero R com indesejáveis efeitos colaterais. O objetivo deste trabalho é trabalho é o desenvolvimento de conhecimento básico (identificação do tipo de racemato e seu ponto eutético no diagrama de solubilidade) para o acolplamento do LMS a uma etapa de cristalização a fim de produzir o isômero S da cetamina em pureza enantiomérica e produtividade alta. Para caracterizar a natureza cristalina da cetamina, diração de raios-X e espectroscopia de infravermelho da mistura racêmica e dos enantilômero puros foram realizados e as curvas de solubilidade em função da temperatura foram determinadas...Observação: O resumo, na íntegra, poderá ser visualizado no texto completo da tese digital / Abstract: The resolution of enantiomers to high levels of enantiomeric purity is presntly a requeriment in the pharmaceutical industry. However, high, purities are reached with this system at the expenses of productivity. Coupling of simulated moving bed (SMB) to a crystallization step can result in a process whith a overall higher productivity. The choise ofcristallization method for the resolution of racemic mixtures is dependent on the eutetic point on the solubility diagram. Eutetic point is the minimum enantiomeric purity that has to be delivered by the SMB to assure that crystallization will produce just one pure isomer. Ketamine is a anesthetic that has a R-isomer with undesirable side-effect. The objective of this work was development of basic knowlwdge for a process (identification of the type of racemate and its eutetic point in the solubility diagram) coupling the SMB to a crystallization step in order to produce the S-isomer of ketamine at high enantiomeric purity and productivity. To characterize the crystalline nature of ketamine, X-ray diffraction and infrared spectroscopy of the racemic mixture and pure enantiomers were performed between powder x-ray pattems, infrared spectra, and solubility curve slopes of the pure enantiomers and racemic mixture indicated racemic compound formation...Note: The complete abstract is available with the full electronic digital thesis or dissertations / Mestrado / Desenvolvimento de Processos Biotecnologicos / Mestre em Engenharia Química

Les caoutchoucs naturels chargés sont largement utilisés pour leurs excellentes propriétés mécaniques comme matériaux structurels dans les pneumatiques. Leurs excellentes performances sont souvent associées à leur capacité à cristalliser sous tension. Dans le cas de la fatigue cyclique, la dissipation induite par la création et fusion de cristallites est souvent donnée comme responsable de la bonne résistance des caoutchoucs naturel à la propagation de fissures. Ce travail de doctorat s'est focalisé sur les divers mécanismes dissipatifs qui sont activé par les grandes déformations rencontrées près d'une pointe de fissure. La diffusion des rayons X a été utilisée pour caractériser les changements de structure à des échelles sub-microniques, tels que la cristallisation sous tension, la création de nano-cavités, ou la réorganisation de la charge. Un premier volet de l'étude s'est focalisé sur des tests uniaxiaux, afin d'étudier l'effet d'un changement de formulation du matériau (taux de charge, densité de réticulation), d'un vieillissement thermique, ou encore d'une élévation de la température sur ces modification de structure. Dans une seconde partie, une caractérisation complète de fissures de fatigue a été effectuée. La corrélation d'image numérique a été utilisée pour mesurer les déformations locales au voisinage d'une pointe de fissure, et les rayons X ont permis d'y associer une mesure locale de la structure du matériau. Les propriétés de fatigue de ces matériaux ont été mit en regard des structures observées afin de discuter leur relation. Il a été mis en évidence que le rôle de la cristallisation dépassait largement sa contribution à la dissipation locale. / Filled natural rubbers are widely used in structural parts such as tires for their outstanding mechanical properties. Their exceptional behavior is often associated to the ability of natural rubber chains to form a crystalline structure under tension. In the case of cyclic fatigue cracking, the dissipation added through crystallization and melting at the crack tip is often seen as the main reinforcing mechanism that reduces fatigue crack growth. This PhD work focused on all the dissipative mechanisms activated by the strain amplification near a crack tip. An extensive use of X-ray scattering was made to investigate sub-micronic changes in structure (strain-induced crystallization, cavitation, filler network). A study was made in uniaxial tension to understand the effects of material composition and test environment on these structure changes. The effect of filler volume fraction, crosslink density, thermal ageing and test temperature were considered. This study was followed by a complete description of several fatigue crack-tips. Digital image correlation was used to map the strain fields at the vicinity of the cracks, while X-ray mapping of the process zone gave information on the local changes in structure. The cyclic fatigue properties of the materials were then discussed through the knowledge acquired both in uniaxial tension and near crack-tips. It showed that the effect of strain induced-crystallization far outweigh the dissipation added.

La cristallisation en solution est une opération unitaire essentielle du génie chimique. Les conditions opératoires dans lesquelles cette opération est menée déterminent sa productivité et la qualité des cristaux produits, par le biais de l’influence qu’elles ont sur les cinétiques de germination et de croissance. De nombreuses études ont mis en évidence que les conditions d’écoulement influencent significativement ces deux cinétiques. Néanmoins, une compréhension profonde de la nature de cette influence n’a, à l’heure actuelle, pas encore été atteinte. Ceci cause bien souvent des problèmes tant au niveau du procédé que du produit et a également pour conséquence que l’effet des conditions d’écoulement sur les cinétiques de cristallisation est rarement exploité de manière à en tirer le meilleur avantage.La première partie de ce travail a été consacrée à l’étude de l’effet des conditions d’écoulement sur les cinétiques de cristallisation en solution (germination et croissance), avec pour cas pratique la cristallisation d’hydrates de dioxyde de carbone (CO2), une solution émergeante pour la capture et la séquestration du CO2 (gaz à effet de serre majeur).De manière à étudier l’impact des conditions d’écoulement sur le taux de formation des hydrates de CO2, des expériences de formation d’hydrates de CO2 ont été réalisées dans un réacteur de type cuve agitée de 20 L mis en œuvre de manière semi-continue dans des conditions d’écoulement variées, produites à l’aide de trois mobiles d’agitations différents (une turbine à pales inclinées, un MaxblendTM et un DispersimaxTM) opérés à différentes vitesses de rotations. Un modèle mathématique original de l'ensemble du processus de formation des hydrates de CO2 attribuant une résistance à chacune de ses étapes constitutives a été établi. Pour chaque condition expérimentale, le taux de formation est mesuré et l’étape limitante est déterminée sur base de la valeur des différentes résistances. Les trois mobiles d’agitations étudiés sont comparés relativement à leur efficacité et, pour chaque mobile, l’influence de la vitesse de rotation sur l’étape limitante est discutée. En l’occurrence, il est montré que des limitations dues aux transferts de chaleur peuvent se produire à l'échelle relativement petite utilisée dans cette étude.L’étude de l’impact des conditions d’écoulement sur la cinétique de germination des hydrates de CO2 s’est concentrée sur la caractérisation de l’effet du taux de cisaillement sur le temps d’induction associé à cette formation (proportionnel à cette cinétique). Cette étude a été basée sur la réalisation de mesure de temps d’induction au cours d’expériences de formation d’hydrates de gaz, utilisant le système CO2-H2O-tetrahydrofuran comme système modèle, réalisées dans un réacteur de type Couette-Taylor. L’application, à la phase liquide dans laquelle prend place la formation des hydrates de gaz, de différents taux de cisaillement (entre 50 et 300 s-1), maintenus constants tout au long de l’expérience de formation, a révélé que le temps d’induction moyen diminuait significativement lorsque le taux de cisaillement appliqué à la phase liquide augmentait. Il a été montré que cette diminution peut être principalement attribuée à une diminution du temps nécessaire à l’apparition de germes stables d’hydrates et à leurs croissances jusqu’à une taille macroscopiquement détectable. Il a également été montré que le temps d’induction moyen peut également être significativement réduit par l’application, à la phase liquide, d’un haut taux de cisaillement (900 s-1) durant une période relativement courte et définie.La seconde partie de ce travail a été dédiée au développement d’une stratégie permettant d’améliorer le contrôle des procédés de cristallisation de substances pouvant cristalliser sous plusieurs formes cristallines, et ce, relativement à la forme cristalline générée au cours et à l’issue de ces procédés. Le cas pratique de cette partie du travail est le développement d’un procédé de cristallisation en solution par refroidissement en mode batch d’un principe actif, récemment développé par la société pharmaceutique UCB, présentant deux formes cristallines connues. La robustesse et la reproductibilité de ce procédé vis-à-vis de la production de la forme cristalline d’intérêt et de la prévention de l’occurrence d’un phénomène de prise en masse, dû à une formation massive de cristaux de la forme cristalline indésirable, sont deux impératifs ayant guidés son développement.Le procédé qui a été envisagé dans le cadre de la deuxième partie de ce travail est basé sur la production de semences cristallines de forme I (la forme d’intérêt) par germination primaire au sein d’un réacteur tubulaire suivie d’une croissance de ces semences en milieu agité contrôlé en température. Les propriétés particulières de l’écoulement mis en œuvre au sein du réacteur tubulaire permettent d’y contrôler finement l’allure des champs de température et de concentration (et donc de sursaturation) et, de manière inédite, de circonscrire l’apparition de cristaux à la partie centrale de l’écoulement (afin de prévenir tout risque d’incrustation de la paroi interne du réacteur). Les expériences réalisées dans ce travail montrent que, associé aux conditions expérimentales utilisées, ce dispositif permet de produire des semences cristallines de forme I de manière reproductible. Elles montrent également qu’un contrôle adéquat des conditions initiales dans lesquelles les semences cristallines de forme I sont amenées à croitre ainsi que du taux de refroidissement utilisé pour entretenir cette croissance permet de garantir que celle-ci se déroule sans que le phénomène de prise en masse ne prenne place. Il est mis en évidence que ce contrôle repose sur la prévention de toute formation indésirable de cristaux de forme II par un maintient, en tout temps, d’un niveau de sursaturation ne dépassant pas une valeur critique donnée. Enfin, ces expériences montrent aussi que le type d’agitation utilisée dans ce travail n’a pas d’influence sur l’occurrence de la prise en masse mais a une influence majeure sur l’état de surface, la taille moyenne et la distribution en taille des cristaux produits. / Solution crystallization is an essential unit operation in the chemical engineering field. Through their effect on the nucleation and growth kinetics, the operating conditions of such an operation determine its productivity and the quality of the produced crystals. An important number of studies have shown that the flow conditions have a significant influence on these two kinetics. Nonetheless, a deep understanding of the nature of this effect is still lacking, which often leads to severe difficulties in the development and operation of crystallization processes and impedes the emergence of positive applications of this effect.The first part of this work has been dedicated to the study of the effect of the flow conditions on the solution crystallization kinetics (nucleation and growth). Carbon dioxide (CO2) hydrate crystallization, an emerging method for the separation and capture of CO2, was used as a practical case.CO2 hydrate formation experiments have been performed in a 20 L semi-batch stirred tank reactor using three different impellers (a down-pumping pitched blade turbine, a Maxblend™, and a Dispersimax™) at various rotational speeds to examine the impact of the flow conditions on the CO2 hydrate formation rate. An original mathematical model of the CO2 hydrate formation process that assigns a resistance to each of its constitutive steps has been established. For each experimental condition, the formation rate is measured and the rate-limiting step is determined on the basis of the respective values of the resistances. The efficiencies of the three considered impellers are compared and, for each impeller, the influence of the rotational speed on the rate-limiting step is discussed. For instance, it is shown that a formation rate limitation due to heat transfer can occur at the relatively small scale used to perform our experiments.The investigation of the impact of the flow conditions on the nucleation kinetics of CO2 hydrates was focused on the characterization of the effect of the fluid shear rate on the induction time of gas hydrate formation (proportional to this kinetics). This study was based on induction time measurements during gas hydrate formation experiments, using the CO2-H2O-tetrahydrofuran system as model system, realized in a Couette-Taylor reactor. The investigation of the effect of the application of a constant shear rate (50 to 300 s-1) to the liquid phase from which the hydrates are formed revealed that the mean induction time decreases significantly as the applied shear rate increases. This could primarily be attributed to a decrease in the time required for stable gas hydrate nuclei to be generated and to grow to a macroscopically detectable size. The induction time could also be significantly reduced by the application of a high shear rate (900 s-1) to the liquid phase for a relatively short, defined period of time.The second part of this work has been dedicated to the development of a strategy for the improvement of the control of crystallization processes involving compounds able to crystallize under several crystalline forms, relatively to the crystalline form generated during and at the end of these processes. The strategy examined in this work was applied to the development of a batch cooling solution crystallization process of an active pharmaceutical ingredient, recently developed by the pharmaceutical company UCB, exhibiting two known crystalline forms. The robustness and the reproducibility of this process relatively to production of the desired crystalline form produced and the prevention of caking, due to the massive formation of crystals of the undesired crystalline form, were the two main priorities that have driven its development.The process considered in the second part of this work is based on the production of form I (the desired form) crystalline seeds through nucleation in a tubular reactor followed by the growth of these seeds in an agitated medium controlled in temperature. The particular properties of the flow conditions in the tubular reactor enable the temperature and the concentration fields, and therefore the supersaturation field, to be finely tuned and, in an original manner, to confine the emergence of new crystals in the center part of the flow (to prevent any fouling of the inner surface of the reactor). The experiments performed in this work showed that, coupled to the experimental conditions used, this device enables to reproducibly generate form I crystalline seeds. The experiments also revealed that a proper control of the initial conditions in which these seeds are brought to grow and of the cooling rate used to sustain this growth allows ensuring that this growth takes place without caking. It is shown that such a control lies on the inhibition of the formation of undesired form II crystals by keeping, at all times, the supersaturation level under a defined critical value. Finally, the experiments showed that the type of agitation used in this work does not influence the occurrence of caking but has a significant impact on the crystals surface quality, mean size, and size distribution. / Doctorat en Sciences de l'ingénieur et technologie / info:eu-repo/semantics/nonPublished

Doctor of Philosophy / Food Science Institute / Jayendra K. Amamcharla / Lactose is commercially produced from whey, whey permeate, or milk permeate as α-lactose monohydrate in crystalline form. Focused Beam Reflectance Measurement (FBRM) as a potential tool for in situ monitoring of lactose crystallization at concentrations relevant to the dairy industry was evaluated. Applicability of FBRM at supersaturated lactose concentrations 50%, 55%, and 60% (w/w) was reported in comparison with Brix values obtained from a Refractometer during isothermal crystallization at temperatures 20ºC and 30ºC. FBRM technique was shown to be a valuable tool for monitoring chord length distributions during lactose crystallization. In a different study, the influence of cooling rate during crystallization of lactose in concentrated permeates was studied. Three cooling rates accounting for approximately 17, 11, and 9 h were applied during lactose crystallization to evaluate the lactose crystal yield and quality of lactose crystals. There was no significant difference (P>0.05) found in lactose crystal yield, mean particle size obtained at the end of crystallization. This study suggested that increasing the cooling rate during lactose crystallization within the range explained in this study can save approximately 8 h of crystallization time. These studies evaluated FBRM as a potential tool to monitor lactose crystal chord lengths and counts. Also, process improvements were suggested to increase the productivity of lactose crystallization process by reducing the crystallization time. In chapters 5 and 6, calcium-reduced milk protein concentrates (MPCs) were used as an ingredient to improve the stability of high-protein dairy beverages. Heat stability increased significantly (P>0.05) in 8% protein solutions made from 20% calcium-reduced MPC. A significant increase in heat stability was observed in beverages formulated with 20% calcium-reduced MPC in the absence of chelating agent. In another study, it was evident that the dairy beverage formulation with 20% calcium-reduced MPC showed no sedimentation and age gelation indicating an improved storage stability. These studies confirmed that 20% calcium reduced MPC contributed towards improved heat stability and storage stability of the high-protein beverages.