The second law analysis is a powerful tool for assessing the performance of engines and has been employed for few decades now. Turbocharged diesel engines have been explored in much detail with the help of second law analyses. There is also a need to examine the turbocharged spark-ignition engines in greater detail using second law analyses as they are gaining popularity in high performance and conventional automobiles as well. A thermodynamic simulation was developed in order to investigate the effects of turbocharging on spark-ignition engines from second law perspective. The exergy values associated with the components of the turbocharger along with the engine components were quantified as a percentage of fuel exergy. The exergy balance values indicated that turbocharger does not add considerably to the overall irreversibilities and combustion irreversibility is still the major source of exergy destruction. A comprehensive parametric investigation was also performed to investigate the effects of compression ratio, intercooler effectiveness, etc. for the turbocharged spark-ignition engine over the entire load and speed range. The simulation studies helped in understanding the behavior of turbocharged sparkignition engine with these parameters. A simulation study was also performed to compare the turbocharged engine with the naturally aspirated spark-ignition engine. This study examined the engines for operating parameters like bmep and bsfc over the entire speed range and revealed that turbocharging offers higher bmep and lower bsfc values for most of the operating range. In an additional study, these engines were analyzed for the brake thermal efficiency values at part load. The results indicated that turbocharging offers marginally higher brake thermal efficiency at part loads.

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Based on the GT-Power software, an engine cycle simulation for a biodiesel fueled direct injection compression ignition engine was developed and used to study its performance and emission characteristics. The major objectives were to establish the engine model for simulation and then apply the model to study the biodiesel fueled engine and compare it to a petroleum-fueled engine. The engine model was developed corresponding to a 4.5 liter, John Deere 4045 four-cylinder diesel engine. Submodels for flow in intake/exhaust system, fuel injection, fuel vaporization and combustion, cylinder heat transfer, and energy transfer in a turbocharging system were combined with a thermodynamic analysis of the engine to yield instantaneous in-cylinder parameters and overall engine performance and emission characteristics. At selected engine operating conditions, sensitivities of engine performance and emission on engine load/speed, injection timing, injection pressure, EGR level, and compression ratio were investigated. Variations in cylinder pressure, ignition delay, bsfc, and indicated specific nitrogen dioxide were determined for both a biodiesel fueled engine and a conventional diesel fueled engine. Cylinder pressure and indicated specific nitrogen dioxide for a diesel fueled engine were consistently higher than those for a biodiesel fueled engine, while ignition delay and bsfc had opposite trends. In addition, numerical study focusing on NOx emission were also investigated by using 5 different NO kinetics. Differences in NOx prediction between kinetics ranged from 10% to 65%.