Realisation of Low Temperature Combustion in an Unmodified Diesel Engine

Heavy-duty diesel engines are an essential part of road transportation. Since viable alternatives are not expected in the short and medium term, the problematic emission characteristics of compression ignition engines must be addressed. Lowtemperature combustion (LTC) is an alternative combustion method for compression ignition engines that allows low particulate matter and nitrogen oxide emissions while improving efficiency. To overcome the difficulties of market introduction, the realisation of such alternative combustion methods should come with marginal engine modifications. Thus, this work investigates a possible realisation of LTC in an unmodified diesel engine. LTC methods were studied with and without injection strategy modifications to provide sufficient recommendations for other researchers. It was concluded that techniques requiring early direct injection, such as homogeneous charge compression ignition (HCCI), necessitate a narrow cone angle injector to reduce wall impingement. It was also determined that modulated kinetics (MK) type LTC can be easily achieved by applying a conventional injection strategy and high amounts of cooled exhaust gas recirculation. The realised MK combustion resulted in an enhanced NOx-PM trade-off and a lower peak pressure rise rate than normal operation.