Assessment of Performance and Emissions from a Hybrid Vehicle Integrated with a Low Temperature Combustion Engine Undergoing a Drive Cycle

In the last decade, the increased global temperature, stringent regulations, and customer demand for high fuel economy have led to the accelerated development of alternative propulsion solutions, with particular focus on electrified vehicles. Hybrid electric vehicles (HEV), the combination of electric machinery with conventional powertrains, allows the diversification of powertrain architectures. In addition, it has been demonstrated that engines employing advanced low temperature combustion concepts, such as dual fuel reactivity controlled compression ignition (RCCI), and able to operate on both renewable and conventional fuels, produce ultra-low nitrogen oxides (NOx) and particulate matter (PM) emissions while maintaining thermal efficiency similar to conventional diesel operation at part load operating conditions. Therefore, the combination of both technologies creates a promising horizon to be implemented in production vehicles in the near future. This study aims to investigate the potential of integrating a gasoline-diesel RCCI engine in a HEV in achieving reduced fuel consumption and lower NOx and soot emissions compared to a conventional diesel powertrain. In this work a combination of engine experimental data and a vehicle powertrain simulation tool (AVL CRUISE) is employed to determine the vehicle level emissions and performance of a commercial vehicle on the worldwide harmonised light-duty vehicles test cycle (WLTC). In order to assess the emissions, the powertrains are simulated utilising both conventional diesel combustion (CDC) and RCCI-CDC dual combustion mode engines as the primary power sources. For a series hybrid vehicle, NOx emissions decreased by 67% and soot emissions decreased by 70% compared to a CDC vehicle. However, the combustion efficiency decreased in the RCCI mode resulting in a significant increase in total hydrocarbon (THC) and carbon monoxide (CO) emissions. Moreover, the implementation of the HEV technology results in decreased fuel consumption, leading to a 40% reduction in carbon dioxide (CO2) emissions compared to the CDC vehicle. These results indicate the potential of HEVs, particularly when equipped with RCCI-CDC dual combustion mode engines, to achieve enhanced environmental performance in terms of reduced fuel consumption and emissions, thereby offering a promising solution for sustainable transportation.