Engenharia Química
URI permanente desta comunidadehttps://repositorio.fei.edu.br/handle/FEI/25
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8 resultados
Resultados da Pesquisa
- Biodiesel production from vegetal oil and ethanol via transesterification in supercritical conditions(2023-08-03) SIDI NETO, V.; DERENZO, S.; MARIN, M. P. DE A.; Luis Novazzi; João Guilherme Rocha Poço© 2023, The Author(s) under exclusive licence to Associação Brasileira de Engenharia Química.Biodiesel, which is derived from renewable feedstock, has potential to replace fossil diesel. In this study, biodiesel production was carried out through the transesterification of soybean oil with ethanol (anhydrous and hydrated) under supercritical conditions in a batch reactor, with a temperature range of 280–340 °C and an oil/alcohol molar ratio of 1:40. The effects of both anhydrous and hydrated ethanol on the reaction were evaluated, as well as the direct esterification of oleic acid to produce ethyl ester. A first-order reversible kinetic model was proposed to describe the transesterification process. The results showed a good agreement between experimental data and the model. It was observed that temperature has an important effect on ester yield and hydrated ethanol improved this yield. After 120 min of reaction time at 310 °C with hydrated ethanol, transesterification led to 89.7% of ethyl ester. When compared to anhydrous ethanol, forward rate constants of hydrated ethanol suggested that water may have a catalytic effect on transesterification. Although the transesterification of soybean oil and ethanol under supercritical conditions is nearly irreversible at 280 °C, the reaction is limited by equilibrium at temperatures equal to or higher than 310 °C.
Artigo de evento 0 Citação(ões) na Scopus Use of hydrodynamic cavitation as an alternative for biodiesel production(2009-08-30) SANTOS, S. L. DOS; FERREIRA, M. S.; Maristhela Passoni de Araújo Marin; Luis Novazzi© 2009 by ABCM.Biodiesel is known as an alternative to conventional petrodiesel because of its renewability and better combustion performance, in addition to reducing emissions, harmful to the environment. Biodiesel production consists on the transesterification of triglycerides with an alcohol and the reaction is affected by the alcohol type, temperature, molar ratio of alcohol to oil and catalyst type and amount. Since this reaction is a heterogeneous one, reagent mixing is also of crucial importance and traditionally the blending is carried out by using mechanical mixers. In this work a different approach is proposed, where the mixing is induced by hydrodynamic cavitation provoked by an orifice plate connected to the suction of a centrifugal pump. Biodiesel production was carried out at 45°C with a 1:8 molar ratio of soybean oil to ethanol. It was observed that the method assisted by hydrodynamic cavitation promotes the enhancement of biodiesel yield in comparison to the conventional method that uses mechanical stirring. In comparative tests carried out from 0 to 40 minutes, the hydrodynamic cavitation always showed conversion rates larger than the mechanical agitation. Although specific energy consumption in biodiesel production is slightly higher for hydrodynamic cavitation when compared to conventional mechanical mixing, it was observed that in the alternative approach the equipment employed is simple and has a low acquisition cost, showing that it has a great potential to be scaled up and used in industrial processes.Artigo de evento 5 Citação(ões) na Scopus Multivariable control of a heat exchanger with bypasses(2009-07-15) Delatore, F.; DA CRUZ, J. J.; Fabrizio Leonardi; Luis NovazziA myriad of different multivariable control techniques, ranging from the simplest isolated PID controllers to the most sophisticated model predictive controls, are presented in the literature and applied to chemical plants. This work intends to present an intermediate control solution between the simplest and the most complex control design, with a relative simplicity, in combination with a superior performance when compared to traditional PID controllers. The proposed strategy, based on a Linear Quadratic Regulator (LQR), was applied to a heat exchanger with bypasses, which is a typical equipment in industries' processes. Even though the LQR is relatively straightforward to design, with a simple tuning procedure, some simulations' results demonstrated that the proposed approach leaded to a reasonable control performance, i.e., process variables became almost totally decoupled, no offset was observed and the output responses presented an small time constant.Artigo de evento 0 Citação(ões) na Scopus Transesterification of sunflower oil produced by solvent extraction(2014-11-16) Maristhela Passoni de Araújo Marin; Luis Novazzi; DENARI, M. L.In this work, the leaching of oil from sunflower seeds using hexane was studied. The solution of oil / hexane was thereafter transesterified, with methanol and potassium hydroxide (KOH) as the catalyst, in a batch reactor, for 1 hour and with a constant temperature of 45 °C. It is important to point out that the extracted oil was not refined and was directly used on transesterification reactions. The hexane in the oil / hexane solution acted as a cosolvent and made the oil / methanol mixture forms a single-phase. Experimental results obtained in the transesterification reactions showed that the increase of methanol / oil mole ratio on reaction yield is negative, whereas the increase of catalyst concentration on reaction yield is positive. Reaction yields decreased 18.00% on average when the mole ratio methanol / oil was increased. When catalyst concentration was augmented, reaction yields increased 15.19%, on average. These results are statistically meaningful, since the standard deviation was equal to 0.48%. Moreover, an interaction between methanol / oil mole ratio and catalyst concentration on reaction yield was observed.Artigo de evento 0 Citação(ões) na Scopus Analysis of the transient behavior of an engine cooling radiator(2019-06-23) RODRIGUES, K.; LIRA, L. M.; IENO, J. P. S.; Luis Novazzi; Cyro Albuquerque© ECOS 2019 - Proceedings of the 32nd International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems. All rights reserved.The transient analysis of a radiator may be important in situations of high sudden demands and for use in electric vehicles or in heat recovery systems. This work aims to study the dynamic behavior of a radiator in different operational conditions. A mathematical model to simulate its behavior was proposed and validated with experimental data. An experimental bench was assembled with the radiator inside a wind tunnel. The water flows through a closed circuit containing the radiator, a tank, a pump and heaters. Thermocouples were placed in several points for temperature measurement. The flow of water and air were also measured. Some tests were carried out to verify the transient performance, by starting from a steady state condition and then imposing, through a heater, different heat loads on the system. The model was developed from energy balances for the radiator air, water and aluminum, the tank and the heater. The solution of these equations allows to obtain the variation of the temperature in each one of these components. It was observed that the radiator responds very quickly to the variation of the heating, in a few seconds, probably due to its small mass and large area of heat transfer. Then the temperature of the radiator increases more slowly accompanying the increase of temperature of the whole system until all the volume of water arrives at the steady state, taking about 15 minutes. The outlet temperature of air and water and the aluminum had a very close behavior. The model presented a behavior very close to the experimental results, showing that even an analysis with few control volumes can bring satisfactory results for the simulation of the transient state under different conditions.- Optimal control of heat exchanger networks(2009-01-05) Luis Novazzi; ZEMP, R. J.Energy integration among chemical process streams can lead to quite complex heat exchanger networks (HEN) with difficulties in terms of control. In the HEN, the control system primary objective is to keep outlet stream temperatures in a specified range. This objective can be achieved by manipulating bypasses in the exchangers or heat loads in coolers or heaters, which results in a positive degree of freedom, since the number of possible manipulated variables is greater than the number of controlled variables. Thus, a secondary control objective can be set: minimization of utility consumption. In this work HEN dynamics and steady state aspects were addressed with the aim of proposing a control strategy that minimizes utility consumption and satisfies imposed restrictions. With the tools developed in this work it was proposed a feedforward optimal control strategy, which consisted in the minimization of a steady state objective function, connected to utility consumption and subjected to constraints in outlet stream temperatures. The suggested approach is an interesting one since rigid or flexible control objectives can be set. The solution of the minimization problem resulted in optimal bypasses positions in the HEN, which were dynamically implemented using a ramp function and a step function. It was verified that ramp implementation was better, with tolerable dynamic violations. © 2009 Elsevier B.V. All rights reserved.
- Coupling of Fischer-Tropsch synthesis and MCH dehydrogenation in a multifunctional reactor(2016) Luis Novazzi; SANTOS, R. S.Multifunctional reactors are used in chemical process industries and promote thermal coupling between an exothermic and an endothermic reaction. The former supplies energy to the latter so they can be carried out simultaneously. Fischer-Tropsch (FT) synthesis coupled with methyl cyclohexane (MCH) dehydration in a multifunctional reactor was studied in this work, aiming the production of gasoline and hydrogen. The reactor was modelled by using material and energy balances for the reactional system, in a pseudo homogeneous, one dimensional and steady state model. Reaction kinetics were taken from the literature and the system of ordinary differential equations was solved in Matlab, in parallel flow. In addition to technical aspects, a preliminary economic evaluation was developed. Gasoline production was optimized and in the best operational conditions its yield was equal to 10.2 g / 100 g.
- Projeto de reator multifuncional no acoplamento das reações de desidratação de etanol e hidrodealquilação do tolueno(2019-08-22) Luis Novazzi; SANTOS, FERNANDO AUGUSTO ROMEROReatores multifuncionais possibilitam o acoplamento de um meio reacional exotérmico com um endotérmico, de modo que a energia cedida pelo primeiro supre o segundo. Isso pode levar a projetos de equipamentos com menor custo de capital e também promover uma redução no consumo de utilidades da planta. Neste trabalho, a reação de desidratação do etanol foi acoplada termicamente com a hidrodealquilação do tolueno, em um reator multifuncional, através de simulação do sistema reacional. Fez-se a modelagem matemática desse sistema escrevendo-se os balanços molares para os diversos componentes, os balanços de energia e de perda de carga, enquanto que as leis cinéticas foram tomadas da literatura. Como hipóteses simplificadoras, considerou-se o meio pseudo-homogêneo, em regime permanente e sem variações radiais. O sistema de equações diferenciais ordinárias resultantes, oriundas de um problema de valor inicial, foi resolvido em Matlab. Simulou-se um caso base no qual foi admitida uma configuração de trocador duplo tubo para o reator, com as reações exotérmicas sendo conduzidas no tubo e as endotérmicas na região anular. Esse caso base foi posteriormente otimizado, por meio de análise das condições de operação do equipamento. No projeto final do reator, a conversão tanto do meio endotérmico como do exotérmico foram altas, atingindo mais de 94% e 83%, respectivamente, com boa seletividade. Além disso, os perfis de temperatura indicaram que a associação dessas duas reações é factível.