Auto-ignition behavior of methyl decanoate

A study was conducted to identify premixed auto-ignition differences between a diesel-relevant compound, n-heptane, and a biodiesel relevant compound, methyl decanoate, using a motored engine experiment. Of particular interest for each compound is the magnitude of the cool-flame, and the intermediate products produced by it. An octane rating engine with modified intake air and fueling systems was used. Both n-heptane and methyl decanoate showed strong cool-flame behavior. At low compression ratios, the cool-flame ignition occurred, but the maximum temperature in the cylinder did not get high enough of the main ignition to occur. As the compression ratio was increased further, the maximum temperature increased until the main combustion event occurred. The cool-flame ignition of n-heptane produced high levels of CO, formaldehyde, and acetaldehyde, while CO₂ was only formed during the main ignition. However, methyl decanoate produced significant levels of CO₂ during the cool-flame. This is an abstract of a paper presented at the ACS Fuel Chemistry Meeting (Washington, DC Fall 2005).