Análise do desempenho de um motor do ciclo diesel operando de forma dual (diesel/biodiesel - gás natural) em pequenas centrais termoelétricas.

Abstract

The shortage of energy sources and environmental impact are crucial for the existence of new studies of the conversion and use of energy and reduce the levels of pollutants in the atmosphere. When it comes to diesel, the operation that uses in dual form diesel and natural gas has been widely researched and publicized in recent years and is indicated in the literature as one of the best ways to control emissions of pollutants from them. Another way also to aim the same objective is to use the new alternative fuel that is biodiesel, which is a non-fossil fuel. Thus, this academic work aims to study via mathematical modeling a thermomechanical system composed of a internal combustion engine operating cycle diesel in dual form of fuel utilization (combinations of diesel / biodiesel and natural gas) coupled to an electric generator. The system is equipped with accessories for measuring flow rate, pressure, temperature, power and emissions. The experiments were conducted with the engine operating at a load variation from 40 kW to 120kW, the rate of substitution of diesel by natural gas of about 85% and with various blends of biodiesel with diesel, varying the volumetric percentage of biodiesel in the blend (B5 the B100). As main findings were observed: values for SO2 dissonant with the literature; certain percentage of biodiesel blended with diesel promoted slightly worse results than the use of diesel to pure CO and CxHy (methane) and, on the other hand, very promising results in emissions of CO2 and NOx and combustion efficiency; theoretical combustion efficiency compared to experimental results produced mean errors of up to 20%; energy efficiency in the condition of dual fuel use at least flattens the condition pure diesel operation, the lower the percentage of biodiesel in the mixture, the mole fraction of water vapor in the exhaust and dew temperature are larger; the model was effective in simulation, showing good relationship between experimental and theoretical results.