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Abstract
This study presents a comprehensive experimental investigation to determine the optimal compression ratio (CR) for a diesel-fueled compression ignition (C.I.) engine under controlled operating conditions. Experiments were conducted on a single-cylinder, four-stroke variable compression ratio engine across a wide range of compression ratios (13.2–20.2) at constant speed and varying load. Key performance and emission parameters, including brake thermal efficiency (BTE), specific fuel consumption (SFC), exhaust gas temperature (EGT), and smoke density, were systematically evaluated.
The results indicate that engine performance is strongly dependent on compression ratio, with an optimal value identified at CR = 14.8. At this condition, the engine exhibits maximum thermal efficiency, minimum fuel consumption, and reduced smoke emissions, reflecting improved combustion efficiency and enhanced air–fuel mixing. In contrast, lower compression ratios lead to incomplete combustion, while higher compression ratios result in increased heat losses and reduced net work output, causing a decline in overall performance.
The findings demonstrate that compression ratio optimization is essential for achieving a balance between engine efficiency and emission control. This study provides valuable insights into the role of compression ratio as a key design and operating parameter, contributing to the development of more efficient and environmentally sustainable diesel engines.
References
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Copyright (c) 2026 Ratnakara Raju (Author)