Power, Efficiency, and Emissions Optimization of a Single Cylinder Direct-Injected Diesel Engine for Testing of Alternative Fuels through Heat Release Modeling

Abstract

The increasing dependency of the global economy on mineral fuels necessitates the investigation and future implementation of renewable fuels. Within the spectrum of compression ignition engines, this requires an understanding of the differences in combustion of alternative fuels (including biodiesels) from mineral diesel fuel oil, and requires an environment conducive to the experimentation necessary for future research. This thesis is a work in four parts, and gives much of the perspective necessary to empirically correlate the changes caused by differing fuel inputs. The first chapter provides a background as to the motivation of the work, its component sections, and a description of the work done previously and in parallel with the thesis. Finally, the focus of the thesis is given in order to relate the components to each other. The second chapter takes the form of a thorough review of hydrocarbon emissions from the perspective of compression-ignition engines, including a description of the variance in emissions when switching between diesel fuels from mineral or biological sources. The broad field of hydrocarbon emissions is broken down into subspecies of the group, and a recommendation as the future catalytic aftertreatment modeling using these subspecies is given. In chapter three, the basis of a thermodynamic equilibrium-based heat release model is given. In particular, this model is set up to use an Arrhenius-based rate of combustion calibrated to the emission profile recorded during experimentation. The model is subsequently tested and validated against previously acquired data, in order to highlight the model's ability to cope with varying testing modes, including variable fuels, Exhaust Gas Recirculation, or changing aspiration techniques. The final chapter describes the experimental procedure used to find the proper injection timings to trigger the Maximum Brake Torque condition at a given engine speed as a function of engine load, with the goal of accelerating future calibration of the improved test cell. These timings are also compared to the emissions profile of the engine, with the goal of linking variations in efficiency and emissions composition to variable injection timings.