An experimental investigation on combustion, performance and ringing operation characteristics of a low compression ratio early direct injection HCCI engine with ethanol fuel blends

Abstract

Homogenous charged compression ignition engines can be an alternative to spark ignition and compression ignition engines due to their high thermal efficiency and low exhaust emission characteristics. In this study, the effects of ethanol fuel blends on combustion, performance and ringing operation characteristics were investigated in an early direct injection homogenous charged compression ignition engine at a low compression ratio of 9.2. During the experiments, n-heptane, E10, E15 and E20 were used as test fuels. The experiments were carried out at three different intake air temperatures which are 353, 373 and 393 K, 800-1800 rpm engine speed range and 0.3-0.75 equivalence ratio range. The variations of indicated mean effective pressure, in-cylinder pressure, heat release rate, CA10, CA50, CA90, combustion duration, combustion efficiency, thermal efficiency, indicated specific fuel consumption, maximum pressure rise rate, coefficient of variation of indicated mean effective pressure, ringing intensity and combustion noise level were evaluated. The results showed that the maximum in-cylinder pressure and heat release rate decreased with the increase of ethanol fuel ratio in the mixture. The CA10, CA50 and CA90 advanced and the combustion duration shortened with the increase of the n-heptane fuel in the mixture. The coefficient of variation of indicated mean effective pressure increased with the increase of the ethanol fuel ratio in the mixture at misfiring region. The maximum pressure rise rate, ringing intensity and combustion noise level were tended to increase with the increase of the equivalence ratio at all test conditions.