Emissions Optimization Potential of a Diesel Engine Running on HVO: A Combined Experimental and Simulation Investigation 2019-24-0039
The present work investigates some recalibration possibilities of a 1.4l common rail turbo-charged diesel engine for the optimal operation in terms of emissions and fuel consumption (FC) with pure Hydrotreated Vegetable Oil (HVO). Initially, steady-state experimental data with nominal engine settings revealed HVO benefits as a drop-in fuel. Under these conditions, pure HVO is associated with lower engine out PM (up to 75%) and CO2 (up to 10%) emissions, and lower mass-based FC (up to 9%), while NOx are similar or slightly higher to diesel fuel. At the next step, a combustion model was developed for the particular engine targeting to identify the optimal IT (Injection Timing) and EGR settings for further emissions (PM, NOx and CO2) and FC reduction with pure HVO. For this purpose, four re-adjusted IT and EGR maps were developed with both conventional diesel and HVO. The results of the combustion model in steady-state conditions showed clear reductions in NOx (up to 45%), PM (up to 70%) and CO2 (up to 6%) emissions and in fuel mass consumed (up to 6%) with HVO, when IT is retarded and combined with default EGR compared to market diesel at nominal engine settings.
The investigation was extended with a vehicle simulation model, aiming to examine the performance of the recalibrated engine over the NEDC and the WLTP driving cycles focusing only on CO2 emissions and FC. New maps for CO2 and FC were calculated with the combustion model for the re-adjusted IT and EGR and were implemented in the vehicle model. According to the results, the optimal IT and EGR settings for HVO, lead to lower CO2 emissions in both NEDC (below 1%) and WLTP (1.8%) with the respective reduction in mass FC being below 1% in NEDC and 1.4% in WLTP compared to diesel at nominal engine settings.