Influence of compression ratio on combustion and performance characteristics of direct injection compression ignition engine

The importance of diesel engines for human application is growing day by day. The engine operating parameters also play a key role in tuning the engine conforming to the better performance and emission standards. The effect of varying the compression ratios has more impact on the performance, emission and combustion parameters. In this study, single cylinder direct injection CI engine was tested on varying the compression ratios of 18, 17 and 16 at varying loads. The combustion and performance variation on reducing the compression ratios were investigated clearly. Reduction in brake thermal efficiency and increase in exhaust gas temperatures were observed when compression ratio was reduced from 18 to 16. The brake specific fuel consumption was increased on reducing the compression ratio. Reduction of peak cylinder pressure was observed on reduction of compression ratio and the ignition delay period increased on reducing the compression ratio. The peak heat release rate was closer to TDC on increasing compression ratios from 16 to 18. The rate of pressure rise was also investigated and showed maximum of 5.38 bar/°CA and minimum of 0.78 bar/°CA on above compression ratios. Cumulative heat release was also evaluated in this study showing higher heat energy for higher loads and compression ratios. The performance and combustion parameters on the useful compression ratio of 18 were also justified.