Evaluation of Waste Transformer Oil Biodiesel Blend with n-Heptane Additives for Engine Performance under Variable Injection Pressure and Timing

This study examines performance metrics and emission profiles of Kirloskar TV1 CI engine fuelled with blend containing waste transformer oil (WTO) biodiesel (40%), n-Heptane (10%), and diesel (50%) by volume (referred to as WTO40H10D50), with additional 10 lpm of hydrogen induction in the intake manifold. Effects of varied injection of fuel timing (19°, 21°, and 23°bTDC) and injection pressure (170, 210, and 240 bar) of WTO40H10D50 on diesel engine were analyzed at 100% engine loading condition. The findings indicate that an injection timing of 23°bTDC and an IP of 240 bar yield the highest BTE and lowest BSEC, suggesting optimal energy conversion efficiency. The influence of inducted H₂ resulted in the lowest smoke opacity and HC emissions, demonstrating more complete and cleaner combustion. The results indicate at 23° bTDC of injection timing and 240 bar injection pressure produced best overall performance, with highest brake thermal efficiency and the lowest brake specific energy consumption, reflecting more efficient energy conversion and fuel use. This combination also resulted in the lowest smoke opacity, signifying cleaner combustion with minimal soot emissions. However, for emissions control, different injection timings performed better: 19° bTDC at 240 bar minimized unburnt hydrocarbon (UHC) emissions, while 21° bTDC at 240 bar yielded the lowest carbon monoxide (CO) emissions. The trade-off occurred with oxides of nitrogen (NOx) emissions, which were highest at 19° bTDC due to elevated combustion temperatures, requiring after-treatment technologies for mitigation. Overall, while 23° bTDC and 240 bar yielded the best fuel efficiency and cleanliness These settings provide a balanced approach, maximizing efficiency and minimizing harmful emissions, making them suitable for cleaner diesel engine operation.