Modeling the impact of fuel properties on compression ignition engine performance

Abstract

Renewable fuels are of a great importance when aiming at decreased dependency from fossil resources in the transportation sector. This thesis, being part of ADVANCEFUEL project, encompasses examination of alternative fuels for light-duty engine purposes. Special attention is paid to the impact of fuel properties on modern compression ignition (CI) engine performance. The results are based on extensive literature review from publicly available sources. Interference between fuel properties and engine operating conditions is observed. Modeling is performed by multilinear regression method using data from driving cycles such as New European Driving Cycle (NEDC) and Worldwide harmonized Light vehicles Test Cycle (WLTC). Only representative, passenger car engine data is taken into account. Analyzed fuels and their blends with standard diesel are as follows: biodiesel (FAME), hydrotreated vegetable oil (HVO), biomass- or gas-to-liquid diesel (BTL/GTL). Density, lower heating value (LHV), viscosity, cetane number, oxygen and carbon content are selected as key fuel properties. The developed model predicts engine performance in terms of fuel consumption (FC) and CO2 emissions from the end-user point of view. It enables to estimate a relative change of performance indicators in reference to standard fossil-based diesel. Based on literature sources, the maximum change of FC is +11,8% in case of pure FAME and -3,25% in case of HVO blends. The model satisfies theoretical values with good accuracy (average absolute error of 0,85% in FC). A promising potential in FC reduction is observed for high cetane number paraffinic diesel, including HVO. Finally, predictions of CO2 emissions are based on outcomes from FC model and they indicate only tailpipe emissions changes.