Effects of Combustion Parameters on Emissions of Diesel, Diesel/n-Butanol, and Diesel/n-Butanol/2-Ethylhexyl Nitrate Fuels at Different Intake-Oxygen Concentrations in a Diesel Engine

Abstract

This paper tested one cylinder of a modified light-duty 4-cylinder diesel engine to study the coupling effect of 1.8-bar pressure and oxygen concentration (Coxy) on the combustion process of diesel (B00), diesel/n-butanol (B20) and diesel/n-butanol/2-ethylhexyl nitrate (B20+EHN), with emphasis on the analysis of the influence of combustion state parameters on emission generation. The research results showed that the difference between B00 fuel and B20 fuel in hydrocarbon (HC) and CO emissions was caused mainly by the combustion duration (CD) when the gas circuit concentration was 12%–17%, whereas when the gas circuit Coxy was 9%–12%, the HC and CO emissions were the result of the combined action of the two factors of in-cylinder combustion temperature (IT) and CD. The main influencing factor of NOx emission difference was IT. However, the main influencing factor of soot emission difference at 11%–17% gas circuit Coxy was the ignition delay period (ID), and at 9%–11% gas circuit Coxy it was the in-cylinder combustion temperature. Further research on the emissions difference between B00 fuel and B20+EHN fuel showed that ID plays a decisive role in the reduction of HC and CO emissions.