Shahrood University of Technology Renewable Energy Research and Applications 2717-252X Articles in Press 2025 11 30 THE EFFECT OF WASTE PLASTIC OIL BLENDS ON AN UNMODIFIED CRDI DIESEL ENGINE AT DIFFERENT SPEED AND LOAD VARIATIONS 3674 10.22044/rera.2023.13066.1220 EN Ravi Kumar 9494755058 K Assistant Professor, Department of Mechanical Engineering, Vidya Jyothi Institute of Technology (Autonomous), Aziz nagar, Hyderabad- 500075 Murali Krishna MVS Department of Mechanical Engineering, CBIT, Hyderabad SUDHEER PREM KUMAR B Professor, JNTU Hyderabad College of Engineering, Kukatpally, Hyderabad - 500085 Journal Article 2023 05 05 Due to their availability and environmental concerns, waste plastic, which contains a lot of hydrocarbons with high calorific value, makes suitable alternative fuels. Pyrolysis oil from discarded plastics can fuel diesel engines without modification. The performance, combustion, and emissions of waste plastic oil bio-diesel blend were tested on a single-cylinder, CRDi vehicle research engine with an open ECU. The test varied engine speed (1500, 2000, 2500 rpm) and load (low, medium, full). Waste plastic oil (WPO) blended with pure diesel fuel in 10%, 20%, and 30% volumes and compared to diesel. Engine speeds increased cylinder pressure and brake thermal efficiency. The findings demonstrate that the thermal efficiency of all waste plastic oil blends is lower compared to diesel across all loading conditions. Specifically, at full load, the peak cylinder pressure, heat release, combustion duration, and ignition delay were higher for plastic oil and its blends compared to diesel. The engine running on waste plastic oil experienced a roughly 6% increase in peak pressure but exhibited lower thermal efficiency. These test results highlight the significant impact of the fuel's physical properties on combustion characteristics. In addition, it is observed that increase in Nitrogen oxides (NOx) emission and low brake specific fuel consumption with respect to the speed. The utilization of WPO with diesel up to 20% in the blend can be used in diesel engines with a slight increase in emission of Carbon monoxide (CO) at higher loads.