Diesel engines are more fuel-efficient than their gasoline counterpart. However, high temperature and heterogeneous mixture combustion produce high oxides of nitrogen (NOx) and soot emissions from diesel engines. A sharp contrast in the formation mechanism of these two major pollutants leads to a NOx-soot trade-off that makes it difficult to reduce them simultaneously. Advanced low temperature combustion (LTC) strategies received considerable attention recently due to their potential to reduce NOx and soot emissions simultaneously to near-zero levels. However, the commercial implementation of LTC strategies requires several challenges to be addressed, including lack of ignition timing control, narrow operating load range, high unburned hydrocarbon and carbon monoxide emissions. In the present study, a single fuel LTC strategy referred to as homogeneous charge with direct injection (HCDI) is implemented in a light-duty diesel engine through suitable changes in the intake manifold, cylinder head and fuel injection system. HCDI combustion is achieved with port-injected premixed diesel vapour-air mixture and direct-injected diesel fuel. The experiments conducted in the HCDI mode showed higher indicated thermal efficiency and reduced exhaust emissions except for NOx compared to conventional diesel combustion (CDC). Numerical investigations were then carried out using a commercial 3D CFD code, CONVERGE, to develop a suitable NO
x mitigation strategy for HCDI. With validated CONVERGE models, parametric investigations were carried out on split injections, exhaust gas recirculation and water vapour induction, whose outcome suggests that water vapour induction is the most effective method for NOx control in HCDI. Experimental investigations conducted in HCDI mode with water vapour induction showed a 20.3% improvement in indicated thermal efficiency and 27.1% lower NOx emissions than CDC. However, water vapour induction showed adverse effects at high loads in HCDI with reduced thermal efficiency and higher soot emissions. The fuel injection pressure was increased at higher loads to mitigate soot emissions, which resulted in considerable soot reduction benefits. Finally, CFD investigations were carried out to examine further improvement in thermal efficiency and emission reduction potential in HCDI. The results show that higher boost pressure, water vapour induction and higher fuel injection pressure further improved thermal efficiency with a considerable reduction in regulated pollutants in HCDI than CDC. In this seminar, the reasons behind the benefits obtained in HCDI will be discussed in detail.