OICC Press International Journal of Energy and Environmental Engineering 2251-6832 14 4 (December 2023) 2022 11 19 Investigation of waste cooking oil–diesel blend with copper oxide additives as fuel for diesel engine under variations in compression ratio 10.1007/s40095-022-00549-7 EN Madhuri G. Chatur Department of Mechanical Engineering, Sandip University, Nashik, IN Anil Maheshwari Department of Mechanical Engineering, Sandip University, Nashik, IN Srinidhi Campli Department of Mechanical Engineering, JSPM’s Rajarshi Shahu College of Engineering, Pune-33, IN Journal Article 2022 11 19 Abstract The current day energy expenses contribute cripplingly to inflation rates and hamper the day-to-day needs of the common man. Biodiesel which is a hopeful fuel to muscle diesel needs to be researched extensively such that when brought to day-to-day use must not hamper the traditional engines working. So in the current work, a conventional diesel engine that can be modified to various compression ratios is used to testify to the performance and emissions results. Copper oxide nano additives are used as fuel additives. The copper oxide nano-sized particle characteristics and various parameters were determined using appropriate characterization methods. The additives are mixed in waste cooking oil methyl ester blend and later subjected to property check and engine testing. The addition of nano-sized additives does enhance the thermal performance of the engine by incrementing the thermal efficiency and retarding the fuel consumption rates by 6.3 and 4.9%. The emissions discharged from the engine were also retarded by 4.3%, 26.1 for CO and HC emissions.