Uso da técnica de análise de óleo lubrificante em motores diesel estacionários, utilizando-se misturas de biodiesel e diferentes níveis de contaminação do lubrificante

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Avaliação da utilização do atual Diesel (combustível) comercial brasileiro (ano de referência 2003-2004) para motores com gerenciamento eletrônico de combustível e sistema de recirculação de gases de escape (EGR), certificados pela legislação EPA, 2004

Pós-graduação em Engenharia Mecânica - FEG

Diesel, biodiesel de mamona e de soja: desgaste do motor de trator agrícola em operações de preparo de solo

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Biodiesel de buriti em trator: desempenho em função do tipo de diesel e da proporção de mistura na operação de preparo do solo

Pós-graduação em Agronomia (Ciência do Solo) - FCAV

Opacidade da fumaça do trator agrícola funcionando com biodiesel etílico destilado de babaçu e diesel B S10 em períodos do dia

Pós-graduação em Agronomia (Ciência do Solo) - FCAV

Comparative study of cogeneration systems in a chemical industry

With the large penetration of the natural gas into the Brazilian energy structure, industries such as paper mills and chemical plants are analyzing the feasibility of implementing cogeneration schemes appropriate to this fuel. The analysis of the energy demand patterns of a chemical company from the photographic sector revealed the possibility of using combined cycles or diesel engine cogeneration schemes keeping the existing compression refrigeration units and steam or gas cycle cogeneration systems with absorption refrigeration units. In terms of economic attractiveness, an analysis based on the method of the internal rate of return was performed. The results indicated that the schemes composed by reciprocating engines and combined cycle with compression chillers, as well as the gas cycle scheme with absorption chiller, present return periods of up to 3 years, showing that the investment in cogeneration could be of interest for this plant. (C) 2000 Elsevier B.V. Ltd. All rights reserved.

Networked control system for the guidance of a four-wheel steering agricultural robotic platform

A current trend in the agricultural area is the development of mobile robots and autonomous vehicles for precision agriculture (PA). One of the major challenges in the design of these robots is the development of the electronic architecture for the control of the devices. In a joint project among research institutions and a private company in Brazil a multifunctional robotic platform for information acquisition in PA is being designed. This platform has as main characteristics four-wheel propulsion and independent steering, adjustable width, span of 1,80m in height, diesel engine, hydraulic system, and a CAN-based networked control system (NCS). This paper presents a NCS solution for the platform guidance by the four-wheel hydraulic steering distributed control. The control strategy, centered on the robot manipulators control theory, is based on the difference between the desired and actual position and considering the angular speed of the wheels. The results demonstrate that the NCS was simple and efficient, providing suitable steering performance for the platform guidance. Even though the simplicity of the NCS solution developed, it also overcame some verified control challenges in the robot guidance system design such as the hydraulic system delay, nonlinearities in the steering actuators, and inertia in the steering system due the friction of different terrains. Copyright © 2012 Eduardo Pacincia Godoy et al.

Ácaros associados à Jatropha spp. (Euphorbiaceae) no Brasil

Pós-graduação em Biologia Animal - IBILCE

Modelagem de motor de combustão internae simulação do processo de queima de combustível

The internal combustion engine is a heat engine widely used in the automotive industry. In order to better understand its behavior many models in the literature have been proposed in the last years. The 0-D thermodynamic model is a fairly simple tool but it is very useful to understand the phenomenon of combustion inside the chamber of internal combustion engines. In the first phase of this work, an extensive literature review was made in order to get information about this kind of analysis and, after this, apply them in a model able to calculate the instantaneous temperature and pressure in one zone of the combustion chamber of a diesel engine. Therefore some considerations were made with the aim of increasing the accuracy of the model in predicting the correct behavior of the engine, adding the combined effects of heat transfer, leakage and injection. In the second phase, the goal was to study the internal flow of a three-dimensional model of an internal combustion engine. In order to achieve this goal the software Solidworks was used to create the geometries of an engine and the suite of softwares Ansys was used to create the moving mesh (ICEM CFD and CFX-Pre) and to solve the CFD problem (Ansys CFX code). The model was able to perform the air flow simulation during the four-stroke cycle of an engine: admission, compression, expansion and exhaust. The results obtained from both models were suitable and they open a new range of possibilities for future researches on the field

Estudo da utilização de ferramentas a base de nitreto de silício (Si3N4) e alumina (Al2O3) na usinagem do ferro fundido vermicular

Machining is one of the most commonly manufacturing processes used in the modern world, consuming millions of dollars annually. Because of this, it is crucial for the automotive industry to reduce costs on their heat-resistant alloy machining processes, such as compacted graphite iron (CGI), which has shown an increasing trend of its application in diesel engine blocks, brakes disks, among other applications, due to its superior mechanical properties to gray cast iron. Despite this advantage, its use is still limited due to its difficulty of machining, moreover, cutting tools are displayed as the main factor in increasing the machining cost. Seeking an alternative to a better machinability of CGI, this paper aims to study two types of ceramic tools developed in Brazil, and benchmark their performance by dry turning. For this, were used CGI class 450 and two tools: ceramic of silicon nitride (Si3N4) and alumina-based (Al2O3), with a cutting speed (Vc) of 300, 400 and 500 m / min; feed (f) of 0.2 mm / rev and depth of cut (ap) of 0.5 mm, using three replicates and starting with new cutting edges. The results showed that the Al2O3 tool had the best performance in Vc of 500 m / min, while the Si3N4 tool had the best results in Vc of 300 m / min. This can be explained by the tool of Si3N4 based include soft intergranular phase, called amorphous, while alumina has higher abrasion resistance due to its high refractoriness. The results make it clear that the tools have significant potential for machining of compacted graphite iron, being necessary a strict control of the cutting parameters used

Biodiesel de mamona no diesel interior e metropolitano em trator agrícola

A demanda de recursos energéticos pelos sistemas de produção, aliada à escassez dos combustíveis fósseis, tem motivado a produção do Biodiesel, que é um combustível obtido de fontes renováveis. O objetivo deste trabalho foi realizar dois ensaios: o primeiro dinâmico, para avaliar o desempenho operacional utilizando como parâmetro o consumo de combustível, e o segundo, estático, para mensurar a opacidade da fumaça (material particulado) do motor de um trator agrícola, operando com diesel metropolitano e interior misturados ao Biodiesel de mamona, em sete proporções. O trabalho foi conduzido no Departamento de Engenharia Rural da UNESP/Jaboticabal - SP. Os resultados mostraram que o tipo de diesel influenciou no consumo de combustível e na opacidade da fumaça, sendo o diesel metropolitano de melhor qualidade; observou-se, também, que à medida que a proporção de Biodiesel aumentou, o mesmo ocorreu para o consumo de combustível; entretanto, a opacidade da fumaça reduziu com o acréscimo de Biodiesel até B75.

Ecological impacts from syngas burning in internal combustion engine: Technical and economic aspects

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Desempenho de um motor de trator agrícola em bancada dinamométrica com biodiesel de óleo de frango e misturas binárias com óleo diesel

O Brasil, terceiro maior produtor de biodiesel do mundo e terceiro maior produtor mundial de frango, pode incrementar, na sua matriz energética, o uso de óleo oriundo de aves como alternativa aos combustíveis fósseis e à redução da dependência do óleo de soja para esse fim. O país dispõe de mais de 350 milhões de litros de óleo de frango por ano. Considerando a aplicação dos combustíveis alternativos para os motores a diesel, em máquinas agrícolas, o trabalho teve por objetivo avaliar o desempenho do motor de um trator agrícola de 53kW acoplado pela TDP em bancada dinamométrica, operando com biodiesel metílico de óleo de frango e misturas com óleo diesel, sendo: B5 (testemunha), B20, B40, B60, B80 e B100. Avaliaram-se a potência, o torque, a reserva de torque, o consumo de combustível, o consumo de energia e a eficiência térmica do motor. O ensaio foi instalado com delineamento inteiramente casualizado (DIC) em esquema fatorial com seis tratamentos. Os resultados foram submetidos à análise de variância e as médias ajustadas por equações de regressão. Foram observadas perdas na geração de potência e torque, aumento no consumo de combustível, redução do consumo energético e melhoria na eficiência térmica do motor, de acordo com o aumento da proporção de biodiesel na mistura.

Simultaneous determination of neutral nitrogen compounds in gasoline and diesel by differential pulse voltammetry

The presence of trace neutral organonitrogen compounds as carbazole and indole in derivative petroleum fuels plays an important role in the car's engine maintenance. In addition, these substances contribute to the environmental contamination and their control is necessary because most of them are potentially carcinogenic and mutagenic. For those reasons, a reliable and sensitive method was proposed for the determination of neutral nitrogen compounds in fuel samples, such as gasoline and diesel using preconcentration with modified silica gel (Merck 70-230 mesh ASTM) followed by differential pulse voltammetry (DPV) technique on a glassy carbon electrode. The electrochemical behavior of carbazole and indole studied by cyclic voltammetry (CV) suggests that their reduction occurs via a reversible electron transfer followed by an irreversible chemical reaction. Very well resolved diffusion controlled voltammetric peaks were obtained in dimethylformamide (DMF) with tetrabutylammonium tetrafluoroborate (TBAF(4) 0.1 mol L-1) for indole (-2.27 V) and carbazole (-2.67 V) versus Ag vertical bar AgCl vertical bar KClsat reference electrode. The proposed DPV method showed a good linear response range from 0.10 to 300 mg L-1 and a limit of detection (L.O.D) of 7.48 and 2.66 mu g L-1 for indole and carbazole, respectively. The results showed that simultaneous determination of indole and carbazole presents in spiked gasoline samples were 15.8 +/- 0.3 and 64.6 +/- 0.9 mg L-1 and in spiked diesel samples were 9.29 +/- 1 and 142 +/- 1 mg L-1, respectively. The recovery was evaluated and the results shown the values of 88.9 +/- 0.4 and 90.2 +/- 0.8% for carbazole and indole in fuel determinations. The proposed method was also compared with UV-vis spectrophotometric measures and the results obtained for the two methods were in good agreement according to the F and t Student's tests. (C) 2007 Elsevier B.V. All rights reserved.

Development and validation of an environmentally friendly attenuated total reflectance in the mid-infrared region method for the determination of ethanol content in used engine lubrication oil

Lubricating oils are crucial in the operation of automotive engines because they both reduce friction between moving parts and protect against corrosion. However, the performance of lubricant oil may be affected by contaminants, such as gasoline, diesel, ethanol, water and ethylene glycol. Although there are many standard methods and studies related to the quantification of contaminants in lubricant oil, such as gasoline and diesel oil, to the best of our knowledge, no methods have been reported for the quantification of ethanol in used Otto cycle engine lubrication oils. Therefore, this work aimed at the development and validation of a routine method based on partial least-squares multivariate analysis combined with attenuated total reflectance in the mid-infrared region to quantify ethanol content in used lubrication oil. The method was validated based on its figures of merit (using the net analyte signal) as follows: limit of detection (0.049%), limit of quantification (0.16%), accuracy (root mean square error of prediction=0.089% w/w), repeatability (0.05% w/w), fit (R 2 =0.9997), mean selectivity (0.047), sensitivity (0.011), inverse analytical sensitivity (0.016% w/w-1) and signal-to-noise ratio (max: 812.4 and min: 200.9). The results show that the proposed method can be routinely implemented for the quality control of lubricant oils. © 2013 Elsevier B.V. All rights reserved.