Long-Term Effects of Rapeseed Oil Blended Diesel Fuel on Fuel Injection System Wear in Diesel Engines

Abstract

This study comprehensively evaluates the long-term impact of blended diesel fuels containing rapeseed oil on the wear and operational performance of diesel engine fuel systems. A Cummins ISF 2.8 engine equipped with a Common Rail Bosch CP3 injection system was tested over 1,200 hours under conditions simulating real operational cycles. Rapeseed oil used in the blends was cold-pressed, unesterified, straight vegetable oil (SVO) filtered to 5 μm before blending. A brief comparative statistical analysis (one-way ANOVA, α = 0.05) indicated that changes in injector wear metrics were significant for the 20% blend (p < 0.01). In comparison, the 10% blend did not differ significantly from diesel in wear-related parameters but significantly reduced smoke opacity (p<0.01). The experiments demonstrated that a 10% rapeseed oil blend resulted in a moderate increase in injector wear, a 3.1% reduction in injector mass flow, and a minor increase in the spray angle. In contrast, a 20% blend led to a 7.2% decrease in injector performance, significant carbon deposit accumulation of up to 28 µm, and erosion craters reaching 12 µm in depth. Fuel filtration resistance increased by 22% at higher biofuel concentrations, whereas cold-start performance deteriorated markedly, with start times increasing by 3.2 seconds. Despite these drawbacks, blends with up to 10% of rapeseed oil achieved a 14% reduction in exhaust smoke and maintained acceptable durability margins, indicating their practical feasibility for partial replacement of conventional diesel fuel.