Evaluation of engine performance and exhaust emissions using polyethylene terephthalate (C10H8O4)n derived waste plastic oil in a diesel engine

Plastic waste accumulation is a serious environmental challenge in the present scenario, while converting it into fuel offers a capable approach for energy recovery. Waste plastic oil (WPO), obtained through the pyrolysis of plastic waste, was examined as a potential substitute fuel for diesel engines by preparing blends of WPO10, WPO20, WPO30, and WPO40 using neat diesel as the reference fuel. Tests were conducted using a variable compression ratio in a single-cylinder, common rail direct injection with a constant speed of 1500 rpm. The performance, combustion, and emission characteristics of these blends were studied under different operating conditions, including fuel injection pressure (400–600 bars), fuel injection timing (21°–25° before top dead center), compression ratio (14–18), and engine load (0–12 kg). The results showed a considerable reduction in carbon monoxide emissions, ranging from 25.48% to 45.22% for the tested blends, highlighting the environmental benefit of WPO usage. However, the lower calorific value of WPO compared to diesel led to an increase in brake-specific fuel consumption, with the highest increase of 29.3% observed for the WPO40 blend. On the other hand, nitrogen oxide emissions increased. Among all the blends, WPO10 and WPO20 showed the best overall performance by maintaining a good balance between emission reduction and thermal efficiency without requiring any engine modification. These findings indicate that lower WPO blend ratios can be considered promising alternative fuels for diesel engines, although further investigation is still needed to address the existing limitations.