Performance and Emissions Analysis of Pre-mixed and Partially Pre-mixed Charge Compression Ignition Combustion.

Abstract

Due to raising concerns of depleting petroleum reserves coupled with global warming, the interest in Compression Ignition (CI) engines is more than ever primarily due to the comparatively superior efficiency of CI engines over Spark Ignition (SI) engines. However, nitrogen oxides (NOx) and Particulate Matter (PM) emissions, and the nature of their trade-off is a major hurdle for CI engines to meet the future emissions regulations. In the last two decades, Low Temperature Combustion (LTC), a method stated to be effective in reducing both NOx and PM emissions simultaneously, has received justifiable attention. In this thesis, the importance of mitigating various emissions from CI engines and the relevant challenges is presented in Chapter 1. Subsequently, brief literature reviews of the various types of LTC; namely, Homogeneous Charge Compression Ignition (HCCI), Pre-mixed Charge Compression Ignition (PCI), and Multi-point Fuel Injection (MPFI) are included in Chapter 2. Details of the single cylinder CI engine lab facility at the University of Kansas (KU) are given in Chapter 3. Additionally, performance and emissions results of a PCI combustion trial are presented. Here, the fuel injection timing was modified at various stages to shift from conventional to PCI combustion regime. Based on the results obtained, a follow up experimental study similar to the previous one was conducted to explore the advantages and restrictions of Partially Pre-mixed Compression Ignition (PPCI) combustion (Chapter 4). Furthermore, an in house built zero-dimensional heat release model was utilized to analyze the in-cylinder pressure data of both the tests conducted. In general, the performance, emissions, and heat release model results indicated good agreement with the trends published in the literature.