Parametric assessment of the effect of oxygenated low carbon fuels in a light-duty compression ignition engine

Abstract

Low carbon fuels (LCF) are proposed as an alternative to help in the reduction of CO2 emissions from the energy sector, specially related to transportation. These fuels, due to their synthesis process, can generate carbon offsets that mitigate the combustion emissions, while at the same time they can have other properties that reduce criteria pollutants like soot. The current study evaluates the combustion characteristics, performance, and emissions of three LCFs with 100%, 66% and 33% renewable content in volume. The fuels are assessed as drop-in alternatives for diesel, using a baseline calibration present in commercially available vehicles, and with an optimized calibration that targets NOx emissions reductions. The optimized calibration is reached by performing a design of experiments (DOE) that allows to create linear models to observe the engine response based on injection and air management settings for each of the LCFs at three operating conditions. Then the cases with similar combustion phasing are evaluated to determine the settings that can provide the lowest NOx and soot emissions without worsening fuel consumption and engine efficiency. It is found that when the LCFs are used as drop-in alternatives soot emissions are reduced when compared to diesel while brake-specific fuel consumption (BSFC) is increased by nearly 10 g/kWh. In contrast, the optimized calibration achieves average NOx reductions of 44% when compared to diesel. Under both calibrations well-to-wheel CO2 reductions of nearly 96% are achieved when the fuel with highest renewable proportion is used.