Low temperature combustion has proved to be beneficial for low NOx and particulate matter emissions. Renewable fuels, such as biodiesel, alcohol fuels, and ether fuels can further decrease the carbon footprint of the engine. The NO to NO2 ratio in engine out NOx emissions has shown dependency on the concentration of hydrocarbon emissions. This relationship has a significant impact on the design of exhaust after-treatment systems. However, the effect of the renewable fuels on NO to NO2 conversion process is less understood. This paper investigates the impact of DME and propane on the in-cylinder conversion of NO to NO2 in a compression ignition engine. Firing test under low temperature combustion condition is first performed to demonstrate the impact of HC concentration on exhaust NO concentration and composition. Then, motoring tests are performed with a mixture of the HC and NO dosed into the engine intake manifold. The simplified testing scenario makes it easier to understand HC-NO interaction. To simplify the process of understanding the difference in fuel behavior a study of NO to NO2 conversion as a resolution of engine cycle is conducted using a Gas Sampling Valve which is capable of collecting in-cylinder gases at varying crank-angles. The FTIR data from these compression tests can help assist future mechanism studies to be performed. This study aims to describe the impact of the two fuels on the NO to NO2 conversion process and the boundary conditions at which these differences occur.

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