Apostolos Karvountzis-Kontakiotis

Combustion and Emissions of a Common-Rail Diesel Engine Fueled with HWCO

Hydrotreated vegetable or waste cooking oils (HVOs or HWCOs) are considered second-generation biofuels and are regarded as a promising alternative to current market diesel because they mainly consist of paraffinic hydrocarbons. This paper presents an experimental investigation conducted in order to examine the potential of HWCO as a substitute of diesel fuel. The HWCO used was produced from waste cooking oils through a catalytic hydrotreatment process. The main target of the study was the investigation of the emissions and combustion characteristics of the HWCO in comparison with conventional diesel. To that aim, a light-duty common-rail Euro 5 diesel engine, running on neat HWCO, was tested over the New European Driving Cycle (NEDC) at the engine test bed. The results showed lower CO₂, CO, and hydrocarbon emissions, but increased NOₓ emissions. Combustion analysis, performed at specific steady-state operating points, revealed the differences in the combustion mechanism between HWCO and market diesel, forming a basis for the interpretation of emissions results.