Hydrocracket fossil oil and hydrotreated vegetable oil (HVO) effect on combustion and emissions performance of "torque-controlled" diesel engines

The present paper describes the results of a research activity aimed at studying the potential offered by the use of Hydrocracked fossil oil (HCK) and Hydrotreated Vegetable Oil (HVO) blends as premium fuels for next generation diesel engines. Five fuels have been tested in a light duty four cylinder diesel engine, Euro 5 version, equipped with closed loop control of the combustion. The set of fuels comprises four experimental fuels specifically formulated by blending high cetane HVO and HCK streams and oneEN590-compliant commercial diesel fuel representative of the current market fuel quality. A well consolidated procedure has been carried out to estimate, for the tested fuels, the New European Driving Cycle (NEDC) vehicle performance by means of the specific emissions at steady-state engine operating points. The procedure included combustion, emission and fuel consumption analysis at seven steady state partial speed/loads test points which are representative of the urban and extra-urban part of the engine homologation cycle (NEDC) and at high speed/high load engine operating condition outside the NEDC area. The results of the experimental activity proved that HCK-HVO blends give several benefits when used in modern Euro 5 automotive engines. While Nitrogen Oxides (NOx) emission are mainly controlled by the Exhaust Gas Recirculation (EGR) level, all other engine emissions and comfort parameters can be significantly improved significantly by using specific fuels tailored blended for light duty engines