Effect of ethanol enrichment and engine parameters on the performance of an HCCI engine fuelled with biodiesel/ethanol mixtures

Based on models resulting from the merging of validated kinetic schemes, four reaction mechanisms were developed to describe the combustion of biodiesel-surrogate/ethanol blends in an HCCI engine. The proposed models were then compared to experimental data issued from a modified cooperative fuel research (CFR) engine which can be considered as an HCCI engine. The kinetic scheme displaying the best predictive capabilities, in conjunction with the single-zone HCCI code from the chemkin library, was used to investigate effects of ethanol enrichment and the variation of some important parameters, such as inlet temperature, relative air/fuel ratio and compression ratio, on the combustion and performance characteristics of the investigated HCCI engine. The blended fuels were formed by incrementally adding 10% of ethanol to the neat biodiesel mixture. The inlet temperature ranged from 320 to 420 K with a step of 20 K, whereas air/fuel and compression ratios were varied from 2 to 5 with a step of 0.5, and from 9 to 14 with a step equal to 1, respectively. The obtained data indicated that ethanol effects on the starting of combustion, combustion duration and indicated mean effective pressure were dependent on intake temperature, air/fuel and compression ratios.

Automated summary

Four reaction mechanisms were developed to describe the combustion of biodiesel-surrogate/ethanol blends in an HCCI engine, by merging validated kinetic schemes. The proposed models were compared to experimental data from a modified CFR engine, which serves as an HCCI engine. The best predictive model was used to investigate the effects of ethanol enrichment and the variation of important parameters on the combustion and performance of the HCCI engine.