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Improvement in Performance of the Blowdown Supercharged HCCI Gasoline Engine by Increasing Compression Ratio
Published October 03, 2012 by Society of Automotive Engineers of Japan in Japan
The objective of this study is to extend the HCCI operational range while maintaining high thermal efficiency of a HCCI engine using the blowdown supercharge (BDSC) system. Two different compression ratios, 11.7 and 14.1, were tested by changing the piston head. The effect of CR on both the high and low load HCCI operational limits was investigated. The experimental results showed that the HCCI operational limit and the fuel consumption at the low load operation were successfully improved by increasing CR. On the other hand, high load operational limit was hardly affected by compression ratio. Also, it was found that the BDSC-HCCI engine with higher CR improves the thermal efficiency of the entire area of HCCI operation range.