Evaluation of Effects of Compression Ratio on Performance, Combustion, Emission, Noise and Vibration Characteristics of a VCR Diesel Engine

In this study, an experimental study has been evaluated on a variable compression ratio diesel engine to investigate the compression ratio effects on engine performance, combustion, emission, vibration, and noise characteristics. The result of engine characteristics were studied at 12:1, 14:1, and 16:1 compression ratios under partial load condition. Experimental engine was operated with diesel, biodiesel and diesel-biodiesel blends throughout the experiments. Experimental study indicated that compression ratio considerably affects the engine characteristics that measured in this study. It is observed that in the experiments, higher compression ratio results in higher brake thermal efficiency and thus lower specific fuel consumption. Higher compression ratios resulted with higher cylinder pressure and thus improved combustion. Increasing compression ratio improved carbon monoxide emission, however, increased carbon dioxide emission and nitrogen oxides formation. Also, noise and vibration of the engine reduced with the increment of compression ratio.