A Simulation Model for the optimization of Turbo charged Diesel Engine Performance

Abstract

Diesel engines are widely used throughout the world in the transportation and industrial sector. Over the years, engineers and researchers have made continuous efforts to maximize the efficiency of the diesel engine, but there is still room for improvement. By maximizing the efficiency we can not only reduce the fuel consumption of engine, but can also contribute to the better environment by reducing the emissions from the engine. In the present research a simulation model for the optimization of the performance of a diesel engine has been developed;  The cylinder to cylinder approach is used.  Physical, empirical and thermodynamic relations are used to setup the model in MATLAB.  The model can predict the backflow through the valves based upon pressure difference across the valves.  Multi event fuel injection technique is employed using main injection and pilot injection.  The presented model can also predict the back flow through the intake valve during hot running of engine.  The turbocharger is investigated with and without intercooler to see the effect on engine performance. The simulated results are in good agreement with already presented experimental results. A study has been performed to analyze the effect of variation of different parameters on the efficiency of the compression ignition engine. The parameters analyzed are bore to stroke ratio, compression ratio, equivalence ratio, injection timing variation (advance, retard), inlet charge heating and turbo-charging. Total of five injection points that is two before top dead center, two after and one at top dead center are simulated. The injection performed before top dead center results in increase in peak pressure of the diesel cycle which in effect increases the brake power of engine. The injection performed after top dead center results in decrease in peak pressure of the cycle hence reducing the engine brake power. Increase in bore to stroke ratio results in higher heat loss during the cycle. In order to counter the heat loss effect on the performance of the cycle, we increased the diameter of intake valve which results in increase in suction of air during intake stroke and compensated the decrease in power due to heat loss. By using the developed technique it is easier to make decisions regarding efficiency optimization in the design phase of the engine. The testing time and cost associated with the engine can also be reduced. The study provides a thorough insight on the effect of parametric variation on engine efficiency.