DSpace Coleção:
http://hdl.handle.net/11422/91
2019-06-27T04:47:39ZAnálise teórico-experimental de microrreatores para síntese de biodiesel com recuperação de calor rejeitado
http://hdl.handle.net/11422/8272
Título: Análise teórico-experimental de microrreatores para síntese de biodiesel com recuperação de calor rejeitado
Autor(es)/Inventor(es): Costa Junior, José Martim
Orientador: Cotta, Carolina Palma Naveira
Resumo : The present work deals with the analysis of the continuous synthesis of biodiesel in microreactors using the rejected heat of a thermal source and has as objective to obtain the maximum efficiency of the biodiesel production using multiple microreactors, aiming at the scheduling of the production, coupled to micro heat exchangers that allow The utilization of the rejected heat of a secondary process to increase the reaction temperature, and consequent improvement in the conversion rates. The first experimental analysis of the biodiesel synthesis is carried out in a device containing a single metal microreactor built using the micromilling technique and a ethyl esters yield of 92.56% at a residence time of 46.56s was achieved. The other experimental analysis is done in a device composed of multiple metal microreactors coupled to micro heat exchanger, manufactured by the additive manufacturing technique that allows the construction of these components in the same substrate, reducing the thermal resistance of contact. In this device a ethyl ester yield of 99.61% was obtained in a residence time of 34.92 seconds. A diffusive-convective-reactive three-dimensional mathematical model that describes the physico-chemical behavior of the species involved in the biodiesel synthesis is reformulated using the CIEA technique, resulting in a mathematical model non-linear and coupled compound of first-order ODE's which enables for simulations with reduced computational costs. The Markov Chain Monte Carlo method (MCMC) is used to estimate the kinetic constants using real experimental data with low conversion rates, which maximizes the presence of intermediary species, and increases the sensitivity of the problem to the parameters.
Editor: Universidade Federal do Rio de Janeiro
Tipo: Tese2017-06-01T00:00:00ZModeling, simulation and applications of ionic polymer metal composites
http://hdl.handle.net/11422/8243
Título: Modeling, simulation and applications of ionic polymer metal composites
Autor(es)/Inventor(es): Ranjbarzadeh, Shahin
Orientador: Duda, Fernando Pereira
Resumo : In the present study, a multiphysics model is presented to predict the behavior of Ionic Polymer Metal Composite (IPMC). The analysis is carried out using commercial software COMSOL. The response of electro actuated IPMC, including the displacement and electric potentials profiles, of the IPMC is numerically calculated. Furthermore, IPMC-fluid interaction is studied with coupling electro-chemo-mechanical model of IPMC with Navier-Stokes equation. The mathematical model used in the numerical analysis consists of three different types of micropumps. Then we focus on the application of IPMC micropump in Biomedical for drug delivery and extracting excess fluid. One of the applications of ionic polymer metal composites is an ophthalmic micropump implant in order to remove excess aqueous humor that may be causing Glaucoma. Therefore, in this study, a low energy IPMC micropump is simulated, in which the fluid is driven by deformation of two IPMC diaphragms. Results show that micropump has the ability to transfer mentioned liquid outside of eye chamber to reduce the pressure and risk of the disease. Another interesting medical application of IPMC micropump is in insulin dispenser device. Simulation of micropump with IPMC diaphragm confirms that IPMC micropump can generate sufficient flow rate of insulin required for treatment of Diabetes. Here, we propose a two-dimensional numerical study on the flow induced by an IPMC cilia vibrating underwater. Concequently, we designed an IPMC cilia integrated micropump that contains various IPMC cilia employed in the upper and bottom side of the fluid channel. Deformation of IPMCs cilia pushes fluid in the channel. Numerical simulation results show that micropump generate fluid flow rate at low electro-potential.
Editor: Universidade Federal do Rio de Janeiro
Tipo: Tese2017-06-01T00:00:00ZAnálise dos parâmetros de desempenho de um motor de ignição por centelha operando com gasolina ou etanol com adição de hidrogênio
http://hdl.handle.net/11422/7761
Título: Análise dos parâmetros de desempenho de um motor de ignição por centelha operando com gasolina ou etanol com adição de hidrogênio
Autor(es)/Inventor(es): Cristo, Bruno Elias Bento de
Orientador: Belchior, Carlos Rodrigues Pereira
Resumo : This work presents a computational study about the effects of the application of hydrogen as complementary fuel to gasoline and ethanol in a spark ignition engine, verifying the modifications of the engine performance parameters. In the research a numerical study was carried out, adopting a quasi-dimensional model for a combustion, simulating the engine operation for equivalence ratios of the mixture air/fuel in λ=1,00; 1,07 e 1,14. Using experimental data from the literature, the fraction of hydrogen used, which was produced in electrolysis process together with oxygen gas in the proportion of 2:1, represented 1.27% of the total volume of air admitted to engine operating at 840 rpm and 0.38% for rotation of 1400 rpm. Using the AVL Boost® software, the effects of the addition of hydrogen were analyzed, where a reduction in the duration of combustion and higher rates of heat release was observed, increasing the thermal efficiency of the engine, as well as it was verified increase peak pressure in the cylinder and the IMEP. It was concluded that the higher speed of the combustion process acquired by the addition of hydrogen allows spark ignition engines to operate with air/fuel blends impoverished, returning in reduction of specific fuel consumption.
Editor: Universidade Federal do Rio de Janeiro
Tipo: Dissertação2017-06-01T00:00:00ZNeutralizador dinâmico de vibrações torcionais viscoelásticos aplicado em sistemas rotodinâmicos
http://hdl.handle.net/11422/7608
Título: Neutralizador dinâmico de vibrações torcionais viscoelásticos aplicado em sistemas rotodinâmicos
Autor(es)/Inventor(es): Büchner, Paulo Cezar
Orientador: Pinto, Fernando Augusto de Noronha Castro
Resumo : Dynamic viscoelastic vibration neutralizers are devices used in the passive control of vibrations. The main characteristics that make them an advantageous choice are directly related to the viscoelastic materials used in the construction of these auxiliary systems. This doctoral thesis deals with the modeling of dynamic neutralizers applied to the problem of torsional vibrations in rotors, the final result of which is to define the viscoelastic and geometric parameters of the neutralizer, that is, in this approach, the material is defined later, from the Response of the physical system, obtained through modal analysis methods or finite elements. In this way, one can select or, eventually, synthesize the elastomer that best suits the on-screen problem. Therefore, this is the characteristic that differentiates the model proposed in this research from other already known models, in which the parameters of the auxiliary system are determined from a pre-selected material. The dynamic behavior of the linear viscoelastic material was described through the fractional model of four parameters and to validate the results of this modeling, a rotodynamic workbench was used, which allowed to evaluate the neutralizer in motion under the effect of torsional vibration. The introduction of torsional forcing was done by means of a remotely controlled angular excitation system. The solution to apply this excitation type overcomes, therefore, some of the difficulties of the torsional analysis with the spinning system. The results prove the effectiveness of the proposed fractional model and show the potential of the viscoelastic neutralizer for the control of torsional vibrations in rotors.
Editor: Universidade Federal do Rio de Janeiro
Tipo: Tese2017-04-01T00:00:00Z