The study on formaldehyde emissions of biodiesel in the HCCI combustion mode

Methyl decanoate mechanism was used to replace biodiesel, the combustion processes and the pollutants formaldehyde from biodiesel HCCI engines were forecasted. Based on Woschni heat transfer model and the numerical simulations, the influence factors of formaldehyde formation were researched, and sensitivity analysis of formaldehyde formation has been made. The results showed that: The formaldehyde emissions can be reduced by improving intake air temperature and pressure; in the view of reduce formaldehyde emissions, the best compression ratio of biodiesel HCCI engine was 7~13, and the best excess air ratio was 1.9-2.3, higher EGR ratio would improve the quality of the mixture to achieve HCCI combustion; the activity free radicals that generated in the low temperature combustion stage have an important impact to the whole chain reaction.