Simulação de curvas de rendimento do motor de combustão interna do ciclo Otto

Abstract

This paper presents a mathematical modeling of performance curves in internal combustion engine of the Otto cycle, using two types of fuels and diferente combustion times. Important performance parameters were discussed, such as, torque, power, thermal and volumetric efficiency, mean effective pressure. The methodology consisted in the application of the theory of finite heat release for internal combustion engines of the Otto cycle. Through the Engineering equation Solver software, graphs were obtained in order to simulate the behavior of performance curves as a function of the crankshaft rotation of the engine fed with gasoline and alcohol. Additionally, the effect of the change promoted by the ignition time and duration of combustion within the engine was checked. The results showed that the model of heat release can respond to changes of the start time and duration of the addition of heat, showing, however, limitations to properly describe the behavior of the performance parameters as a function of fuel type, due mainly to the hypothesis considered in the thermodynamic analysis and the absence of determining factors such as heat transfer, combustion kinetics and the effect of friction, this one highly dependent on engine speed.