Dans l'industrie agroalimentaire, le procédé de blanchiment est un traitement thermique indispensable pour la transformation de légumes en produits conserves et surgelés. L'objectif est de détruire des microorganismes par un chauffage des légumes à 97°C, puis de les refroidir à 5°C. L'enjeu de cette thèse est de proposer une conception énergétiquement efficace de ce procédé. L'analyse énergétique et exergétique, ainsi que le respect de contraintes qualité liées au produit, aboutissent à un nouveau schéma de procédé. L'essentiel de la récupération de chaleur est réalisée grâce à un débit d'eau circulant à contre-courant des légumes au travers de trois échangeurs de chaleur. Le complément de puissance est fourni par une thermo-frigo-pompe (TFP) délivrant les utilités chaude et froide. Le premier enjeu est le bon dimensionnement des échangeurs liquide/solides. Ceux-ci sont modélisés pour deux configurations d'écoulement : courant-croisé et contre-courant. D'autre part, une TFP usuelle n'est pas capable d'avoir la flexibilité nécessaire à son intégration dans un procédé agroalimentaire soumis à des besoins de puissance variables. Deux options de découplage (total et partiel) sont étudiées pour ajouter un degré de liberté à ce cycle thermodynamique. Ces travaux permettent la conception d'un pilote qui est réalisé pour blanchir 1 t/h de légumes. L'équipement a démontré une réduction des besoins de puissance de chauffage de 65 % à 75 %. La consommation exergétique, combinant les besoins de chauffage et de refroidissement, a chuté de 79 % et le débit d'eau consommée est divisé par 5. Si ces travaux posent de nouvelles questions, ils démontrent que la récupération de chaleur sur des solides tels que des légumes est réalisable. / In food industry, the blanching process is essential for transforming vegetables into canned or frozen products. To destroy microorganisms the vegetables are heated to 97 °C and cooled to 5 °C. The aim of this thesis is to propose an energy-efficient design of this process. Energy and exergy analysis, coupled to respect of safety requirements, resulted in a new process flow sheet. The largest part of heat is recovered using an intermediate water flow which circulates in counter-current of the solid flow rate. Remaining cooling and heating needs are provided by a heat pump. Thus, designing the liquid-to-solids heat exchangers is the first challenge. To do this, two mains components are modeled: the countercurrent and the crossflow heat exchangers. On the over hand, a usual heat pump is unable to deliver both heating and cooling with variable capacities. To improve flexibility of this thermodynamic system two different options are analyzed. Theses works lead to a new blanching process design, the pilot was made to operate with a solid mass flow rate of 1 t/h. This equipment demonstrates an energy saving of 65 % to 75 % and an exergy saving of 79 %. Moreover water consumption is divided by 5. If this work leads to new questions, it proves that energy efficiency if feasible on solids like vegetables.

Orientadores: Francisco Maugeri Filho, Helen Treichel / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-14T15:38:41Z (GMT). No. of bitstreams: 1 Mazutti_MarcioAntonio_D.pdf: 2533224 bytes, checksum: 5aa67cc7c607161a5f135fc67eb66778 (MD5) Previous issue date: 2009 / Resumo: Nas últimas duas décadas houve um aumento considerável no emprego de fermentação em estado sólido (FES) para a obtenção de enzimas de interesse em alimentos, incluindo a inulinase. No entanto, todos os trabalhos reportados na literatura abordam a produção de inulinase em escala de bancada, usando poucos gramas de substrato. Essa estratégia de condução do processo é muito importante na etapa de seleção dos substratos e triagem dos microrganismos produtores. Porém, não permite a avaliação do desempenho do processo em escalas maiores. O objetivo desse trabalho foi investigar a produção de inulinase por FES num biorreator de leito fixo com capacidade para 3kg (base seca) usando a levedura Kluyveromyces marxianus NRRL Y-7571. Inicialmente, foi realizado um delineamento composto central rotacional (DCCR) para otimizar a massa inicial de células, a temperatura e a vazão do ar de entrada do biorreator. A partir dos resultados obtidos na otimização, foram realizados 7 experimentos em torno da região otimizada, visando a avaliação cinética do processo. Foram monitorados experimentalmente o consumo de açúcar redutor total (ART), a produção de dióxido de carbono (CO2) e a geração de calor metabólico. A produção de água metabólica, massa de células e etanol, além do consumo de oxigênio, foram calculados a partir de uma equação estequiométrica, tomando como base a produção de CO2 e o consumo de ART. Os dados obtidos na avaliação cinética foram usados para a geração de um modelo de crescimento da levedura Kluyveromyces marxianus NRRL Y-7571 em FES. Este modelo é baseado em redes neurais artificiais (RNA), onde são usadas como entradas para a rede a massa inicial de ART, temperatura do ar de entrada do biorreator, temperatura do ar de saída do biorreator e tempo de fermentação. Como respostas têm-se as taxas associadas com o crescimento da levedura Kluyveromyces marxianus, como a produção de CO2, calor metabólico, etanol, água metabólica, atividade da inulinase e massa celular, além das taxas de consumo de oxigênio (O2) e ART. Por fim, o modelo de crescimento microbiano foi acoplado ao balanço macroscópico de energia no biorreator com o objetivo de prever os perfis de temperatura ao longo do processo. Entre os resultados obtidos no DCCR tem-se que a máxima produção de inulinase obtida foi de 437±36 unidades por grama de substrato seco (U.gds-1) (produtividade de 18,2 U.gds-1.h-1) quando a temperatura do ar de entrada, vazão volumétrica de ar e massa de células foram 30°C, 2,2 m3.h-1 e 22 g, respectivamente. Na avaliação cinética do processo, foram verificadas diferenças nas taxas associadas ao crescimento microbiano entre as condições experimentais. O aumento da temperatura do ar de entrada mostrou ter influência no tempo onde as taxas máximas foram verificadas, sendo que quanto mais alta a temperatura menor foi esse tempo. A temperatura máxima obtida na corrente de ar na saída do biorreator atingiu valores próximos a 50°C, não afetando o teor de umidade do substrato, o qual se manteve acima de 65%. A produção de inulinase mostrou variações significativas com a altura do biorreator. As maiores taxas associadas com o crescimento microbiano foram verificadas quando a temperatura do ar de saída atingiu valores compreendidos entre 30¿38°C, o que corresponde a 4-9 horas de fermentação. O modelo matemático baseado em redes neurais empregado para predizer as principais taxas associadas ao crescimento da levedura K. marxianus em FES mostrou desempenho satisfatório na representação dos dados experimentais e ao acoplar esse modelo à equação de balanço de energia macroscópico do processo obteve-se uma representação satisfatória dos perfis de temperatura ao longo do biorreator / Abstract: In the last two decades there has been a considerable increase in the interest of using solid-state fermentation (SSF) for the development of several bioprocesses and products, including enzyme production, as the inulinase. Nevertheless, all works related in the literature regarding the inulinase production were conducted in small scales, using few grams of substrate. This strategy is interesting to select the most promising substrate and microorganisms, which are able to produce the desired product, but this scale is not appropriated for the evaluation of process performance in larger scales. This work evaluate the inulinase production by SSF in a packed-bed bioreactor with available capacity of 3 kg (dry basis) using the yeast Kluyveromyces marxianus NRRL Y-7571. Initially, it was evaluated the technical viability to produce inulinase by SSF in the packed-bed bioreactor. To optimize the operational conditions, such as temperature and flow rate of inlet air and the initial mass of cells, a central composite rotational design (CCRD) for three independent variables was carried out. Starting from the results obtained in the CCRD, seven new experimental runs were carried out within the range investigated for the independent variables to evaluate the kinetics of cell growth and inulinase production by Kluyveromyces marxianus NRRL Y-7571 in the packed-bed bioreactor. A stoichiometry correlation between CO2, ethanol, metabolic water, O2 and total reducing sugar was determined. Besides, the metabolic heat production was estimated by a proper energy balance in the inlet and outlet air stream. The data obtained during the kinetic evaluation of the process were employed on the development of a mathematical model based on artificial neural networks (ANN) to predict the above mentioned microbial rates associated with the microbial growth in function of the fermentation time, initial total reducing sugar concentration, inlet and outlet air temperatures. In the last step of the work, the model related to the microbial growth was coupled to the macroscopic energy balance in the bioreactor to predict the temperature profile through the substrate bed. The results obtained in the CCRD showed that the optimum inulinase production was 436.7±36.3 U.gds-1 at 24 h of fermentation (productivity of 18.2 U.gds-1.h- 1) when SSF was carried out at 30°C of air inlet temperature, 2.2 m3.h-1 of air flow rate and 22 g of cells. During the kinetic evaluation of the process it was verified that the manipulated variables affected the process performance. The maximum temperature reached in the outlet air stream was about 50°C, however not affecting the moisture content of the substrates that was higher than 65% (w/w) inside the bioreactor. The inulinase production showed significant variations in different bed heights inside the bioreactor. The highest microbial rates were verified when the mean temperature of moist substrate reached values in the range of 30 to 38°C that leads to a fermentation time between 4 to 9 hours. The model developed to predict the main microbial rates of the yeast K. marxianus grown in solid-state fermentation showed a good performance during both training and validation steps. The framework developed showed to be an interesting alternative to substitute the simple empirical microbial model in the macroscopic balance of energy in the bioreactor, since the proposed hybrid model predicted efficiently the temperature profiles through the bioreactor / Doutorado / Doutor em Engenharia de Alimentos

No description available.

The purpose of the research was to design, build, test, and recommend a process to economically separate CO from a gas mixture of CO, CO2, and O2. The general method considered in this research to accomplish the separation was liquid absorption in a packed column. Several experiments were performed to identify the best process solution to use in a prototype. The experiments, based on the COSORB process, consisted of CuCl mixed with a complexing agent (metal tri-chloride) and a solvent (metal tetra-chloride, toluene, ethanol, etc.). The best method consisted of an aqueous solution of CuCl and MgCl2, which has previously been used for CO absorption experiments reported in the literature. The absorption takes place at elevated pressure (30 psig) and ambient temperature, and the stripping occurs at approximately 75 ºC. Using the apparatus at approximate design conditions, the highest removal of CO was 88% with a product composition of 48%. The highest product composition achieved was 84%; in this case CO removal was 66%. Product composition was low because a significant amount of CO2 physically absorbed into solution (which also decreased the pH of the solution to about 4, according to calculation). The removal of CO should increase with a taller column and higher liquid flow through the column; however, this might decrease the product composition. Advantages of this process are that the raw materials used are relatively cheap, heating and cooling requirements are lower than similar processes, and operation is relatively simple.

A simple capillary flow porometer (CFP) was assembled for pore structure characterization of monolithic capillary liquid chromatography columns based on ASTM standard F316-86. Determination of differential pressures and flow rates through dry and wet samples provided the necessary information to determine the through-pore throat diameter, bubble point pore diameter, mean flow pore diameter, and pore distribution. Unlike measurements in bulk using traditional techniques to provide indirect information about the pore properties of monolithic columns, monoliths can be characterized in their original chromatographic forms with this system. The performance of the new CFP was first evaluated by characterizing the pore size distributions of capillary columns packed with 3, 5, and 7 µm spherical silica particles. The mean through-pore diameters of the three packed columns were measured to be 0.5, 1.0 and 1.4 µm, which are all smaller than the pore diameters calculated from a close-packed arrangement (i.e., 0.7, 1.1 and 1.6 µm), with distributions ranging from 0.1 - 0.7, 0.3 - 1.1 and 0.4 - 2.6 µm, respectively. This is reasonable, since visual inspection of SEM images of the particles showed relatively large fractions of smaller than specified particles in the samples. Typical silica monoliths were fabricated via phase separation by polymerization of tetramethoxysilane (TMOS) in the presence of poly(ethylene glycol) (PEG). The mean pore diameter and pore size distribution measured using the CFP system verified that a greater number of pores with small throat diameters were prepared in columns with higher PEG content in the prepolymer mixture. SEM images also showed that the pore diameters of monoliths fabricated in bulk were found to be smaller than those in monoliths synthesized by the same procedure, but confined in capillary tubes. The CFP system was also used to study the effects of column inner diameter and length on pore properties of polymeric monoliths. Typical monoliths based on butyl methacrylate (BMA) and poly(ethylene glycol) diacrylate (PEGDA) in capillary columns with different inner diameters (i.e., 50 to 250 µm) and lengths (i.e., 1.5 to 3.0 cm) were characterized. The mean pore diameters and the pore size distributions indicated that varying the inner diameter and/or the length of the column affected little the pore properties. The latter finding is especially important to substantiate the use of CFP for determination of monolithic pore structures in capillaries. The results indicate that the through-pores are highly interconnected and, therefore, pore structure determinations by CFP are independent of capillary length. A negatively charged polymer monolith based on BMA, ethylene glycol dimethacrylate (EDMA) and 2-acryloylamido-2-methylpropanesulfonic acid monomer (AMPS), was successfully prepared in silica sacrificial layer, planar (SLP) microchannels. Extraction of FITC (fluorescein 5-isothiocyanate) labeled phenylalanine and capillary electrochromatography (CEC) of FITC labeled glycine using this monolithic stationary phase were demonstrated.

No description available.

Chemical warfare agents are a toxic class of compounds that are incredibly harmful to human health. Methods of detoxification and decontamination currently exist, however they all suffer from problems that involve logistical transport or involve technologies that directly address liquid threats instead of vapors. One promising method of detoxification involves the oxidation of these compounds into less-harmful species. The relatively large chemical size and complexity of modern-day chemical warfare agents, however, precludes a straightforward analysis of the chemical transformations that take place on novel decontaminating materials. Additionally, a fundamental understanding of reaction mechanisms that occur on novel material surfaces is required before improved materials can be developed. To this end, the oxidation of three simpler, smaller organic molecules were studied over a variety of materials in order to build up a chemical understanding of the systems under study. The photoepoxidation of propene into propene oxide was observed to readily occur over an in-house developed dual titania-silica catalyst created by atomic layer deposition. The subsequent photoinduced degradation of produced propene oxide was observed to occur over the novel catalyst. Next, the oxidation of CO was studied over a Pt/TiO2 catalyst while in the presence of humidity. The addition of water was shown to enable an alternative, low energy pathway that closely followed the water gas shift, but ended upon the production of stable surface-bound formates. Gaseous oxygen was found to subsequently oxidize these surface formates into the full oxidation product, CO2. Next, the oxidation of methanol was studied over the same Pt/TiO2 catalyst. It was discovered that the water produced when methanol initially adsorbs to the catalyst surface is responsible for unlocking the oxidative capacity of the material. Finally, a custom packedbed reactor was designed and built that enabled unique experimental capabilities not yet available in commercial systems, and will be used in the future to directly test the oxidative capabilities of novel materials for chemical warfare agent destruction. / Doctor of Philosophy / The chemical interactions and reactions that occur between gases and surfaces are incredibly important for a multitude of technologies employed by governments, militaries, and citizens alike. The precise methods in which these gases interact with materials of interest determine whether said material can be used in a catalytic fashion. Much like how an automobile catalytic converter does not have to be replaced each time the vehicle is started; a catalyst is able to be used repeatedly without loss of function. Catalysts in general are unique in that they function to create or allow for chemical reactions to proceed through alternative, lower energy pathways that are more likely to occur under milder environmental conditions. In order to understand the chemical reactions that occur on a catalyst, a combination of specialized spectroscopic methods was used that allowed for tracking the precise chemical bonds that were formed or broken during reaction. A few different model chemical reactions are explored in this work, ranging from the conversion of carbon monoxide into CO2, and the oxidation of methanol, a small alcohol commonly found in fuel cells. The experimental techniques employed herein allowed for precise chemical mechanisms to be tracked, and the information gained will certainly be useful for the design of next-generation materials by future research.

Many of the industrial processes, used by manufacturers to produce biologics, have not been significantly updated since their original design and conception. And thus, there is a great opportunity to update and optimize manufacturing processes. Downstream purification is often considered the bottleneck of the manufacturing process and when biologics are being purified for clinical applications, the final purity is paramount. As a result, pharmaceutical products are subjected to multiple concentration, conditioning, and chromatographic steps. The pharmaceutical industry is constantly and slowly evolving and is always looking to improve efficiency. Simulations and modeling are becoming more commonly used in the pharmaceutical industry as a tool to strategically design and test new production and separation processes developed at the research and development scale. In this thesis, computational fluid dynamics (CFD) modeling was used to develop more efficient bioseparation processes by (1) using a cuboid module geometry and (2) chromatographic medium with product-specific affinity ligands. The laterally-fed class of chromatography modules has a unique cuboidal geometry, with lateral feeding of the sample in the channel above the bed and lateral collection of permeate. CFD simulations and experimental results have shown that the laterally-fed class of chromatography devices can produce sharper elution peaks, have better peak resolution, and consequently purer product fractions than conventional membrane and resin-based chromatographic formats. The enhanced performance by the laterally-fed class of chromatography devices is attributed to improved system fluidics and narrow solute residence time distribution. One other approach to improving efficiency is to address the tradeoff between purity and recovered yield, due to the non-specific binding nature of many commercial resins and membranes. Purification using high-affinity biological ligands selected on specificity to the target molecule could be a feasible solution. A purification scheme for pertactin was developed with final eluate purity of 90% and approximately 100% recovery. / Thesis / Master of Applied Science (MASc)

Background: National School Lunch Program (NSLP) meals have been found to be of higher dietary quality than home-packed lunches. Objective: To explore the cost, including time, of NSLP versus different categories of home-packed lunches. Methods: Data from pre-kindergarten and kindergarten lunches from three schools in southwest Virginia were used for this study. Each lunch item was priced, and a direct cost was assigned based on the lunches contents. Time assessments were conducted to determine the amount of time to prepare each lunch, with a monetary value for time computed based on average salary of the respective county. A non-parametric Kruskal Wallis test was used to compare the direct cost, time, time cost, and the full cost of the meals. Medians were computed based on outlier data. Results: The lowest median direct cost was found for homemade packed lunches ($1.55), followed by homemade school lunches ($2.11), then convenience packed lunches ($2.12), and then NSLP lunches ($2.15). When incorporating preparation time, the NSLP lunch cost the least ($2.15), followed by convenience packed lunches ($2.56), then homemade packed lunches ($2.92), and then homemade school lunches ($11.32). Seventy-six percent (n=414) of home-packed lunches contained sugar-sweetened beverages and/or dessert food items, accounting for almost one-quarter (21.8%) of the cost of all home-packed lunches. Conclusion: When time is computed as part of the total cost of NSLP versus home-packed lunches, the NSLP is the least expensive option. In conjunction with the nutritional benefits of the NSLP, this time-cost data may help shift purchasing and consumption patterns. / Master of Science

The world energy supply and demand, together with limited available resources have resulted in the need to develop alternative energy sources to ensure sustainable and expanding economies. Hydrogen is being considered a viable option with particular application to fuel cells. The Hybrid Sulphur cycle has been identified as a process to produce clean hydrogen (carbon free process) and can have economic benefits when coupled to nuclear reactors (High Temperature Gas Reactor) or solar heaters for the supply of the required process energy. The sulphur trioxide decomposition reactor producing sulphur dioxide for the electrolytic cells in a closed loop system has been examined, but it is clear that development with respect to a more durable active catalyst in a reactor operating under severe conditions needs to be investigated. A suitable sulphur trioxide reactor needs to operate at a high temperature with efficient heating in view of the endothermic reaction, and has to consist of special materials of construction to handle the very corrosive reactants and products. This investigation was undertaken to address (1) the synthesis, characterisation, reactivity and stability of a suitable catalyst (2), determination the reaction rate of the chosen catalyst with a suitable micro reactor (3) construction and evaluation of a packed bed reactor for the required reaction, and (4) the development and validation of a reactor model using computational fluid dynamics with associated chemical reactions. A supported catalyst consisting of 0.5 wt% platinum and 0.5 wt% palladium on rutile (TiO2, titania) was prepared by the sintering of an anatase/rutile supported catalyst with the same noble metal composition, synthesized according to an incipient impregnation procedure using cylindrical porous pellets (±1.7 mm diameter and ±5 mm long). Characterization involving: surface area, porosity, metal composition, - dispersion, - particle size, support phase and sulphur content was carried out and it was found from reactivity determinations that the sintered catalyst, which was very different from the synthesized catalyst, had an acceptable activity and stability which was suitable for further evaluation. A micro pellet reactor was constructed and operated and consisted of a small number of pellets (five) placed apart from each other in a two-stage quartz reactor with sulphur trioxide generated from sulphuric acid in the first stage and the conversion of sulphur trioxide in the second stage, respectively. Attention was only confined to the second stage involving the conversion of sulphur trioxide with the supported catalyst. The overall reaction kinetics of the pellets involving momentum, heat and mass transfer and chemical reaction was evaluated and validated with constants obtained from literature and with an unknown reaction rate equation for which constants were obtained by regression. As result of the complexity of the flow, mass and heat transfer fields in the micro pellet reactor it was necessary to use a CFD model with chemical reactions which was accomplished with a commercial code COMSOL MultiPhysics® 4.3b. A reversible reaction rate equation was used and a least squares regression procedure was used to evaluate the activation energy and pre-exponential factor. The activation energy obtained for the first order forward reaction was higher than values obtained from literature for a first order reaction rate (irreversible reaction) for the platinum group metals on titania catalysts. Detailed analyses of the velocity, temperature and concentration profile revealed the importance of using a complex model for determination of the reaction parameters. A fixed bed reactor system consisting of a sulphuric acid vaporizer, a single reactor tube (1 m length, 25 mm OD) heated with a surrounding electrical furnace followed, by a series of condensers for the analysis of the products was constructed and operated. Three process variables were investigated, which included the inlet temperature, the weight hourly velocity and the residence time in order to assess the performance of the reactor and generate results for developing a model. The results obtained included the wall and reactor centreline temperature profiles together with average conversion. As a result of the complexity of the chemistry and the phases present containing the products from the reactor a detailed calculation was done using vapour/liquid equilibrium with the accompanying mass balance (Aspen-Plus®) to determine the distribution of sulphur trioxide, sulphur dioxide, oxygen and steam. A mass balance was successfully completed with analyses including SO2 with a GC, O2 with a paramagnetic cell analyser, acid/base titrations with sodium hydroxide, SO2 titrations with iodine and measurement of condensables (mass and volume). The results obtained showed that a steady state (constant conversion) was obtained after approximately six hours and that it was possible to obtain sulphur trioxide conversion approaching equilibrium conditions for bed lengths of 100 mm with very low weight hourly space velocities. A heterogeneous 2D model consisting of the relevant continuity, momentum, heat transfer and mass transfer and the reaction rate equation determined in this investigation was developed and solved with the use of the commercial code COMSOL MultiPhysics® 4.3b with an appropriate mesh structure. The geometry of the packed bed (geometry) was accomplished by generating a randomly packed bed with a commercial package DigiPac™. The model predicted results that agreed with experimental results with conversions up to 56%, obtained over the following ranges: weight hourly space velocity equal to 15 h-1, temperatures between 903 K and 1053 K and residence times between 0.1 and 0.07 seconds. The post-processing results were most useful for assessing the effect of the controlling mechanisms and associated parameters. / PhD (Chemical Engineering), North-West University, Potchefstroom Campus, 2014