Sustainable Fuel Pathways: Performance, Combustion and Emission Analysis of Waste Plastic–Tamarind Seed Biofuel Blends in a CI Engine

This study experimentally investigates the influence of clove oil as an antioxidant additive on the performance, combustion, and emission characteristics of a single-cylinder, four-stroke diesel engine fuelled with diesel–waste plastic oil–tamarind biodiesel blends. Clove oil was added to the base blend at concentrations of 1000, 2000, and 3000 parts per million (ppm) to examine its potential for improving combustion and reducing nitric oxide (NO) emissions. Engine experiments were conducted at a constant speed of 1500 revolutions per minute (rpm) under varying load conditions using an eddy-current dynamometer. Performance, combustion, and emission parameters were evaluated and compared with those of neat diesel and the base blend. The results indicate that clove oil effectively reduced NO emissions because of its antioxidant properties, which suppress free-radical reactions during combustion and thereby limit NO formation. However, increasing the clove oil concentration adversely affected other emission characteristics, resulting in higher carbon monoxide (CO), hydro carbon (HC), and smoke opacity emissions. The base diesel–waste plastic oil–tamarind biodiesel blend without clove oil exhibited superior brake thermal efficiency compared with the clove oil-containing blends. At 3000 ppm clove oil concentration, NO emissions decreased by 8.9%, whereas HC, CO, and smoke opacity increased by 2.0%, 50.0%, and 5.8%, respectively. Overall, clove oil shows promising potential as an antioxidant additive for reducing NO emissions.