Effects of n-Heptane/Methane Blended Fuel on Ignition Delay Time in Pre-Mixed Compressed Combustion

Abstract

This study analyzed factors that influence the ignition delay characteristics of n-heptane/methane-blended fuel. The effects of chemical species, exhaust gas recirculation rate, compression ratio, cool/hot flames, and combustion chamber conditions (temperature, pressure, and O2 concentration) were determined and analyzed using CHEMKIN Pro. The experiment conditions for verification were 550–1000 K at 15 bar with 50% H2/50% CH4 fuel. The main combustion reactions were confirmed through reactivity analysis and sensitivity analysis on the ignition delay time. The ignition delay time at 14.7% O2 concentration was significantly higher than that at 21% O2 concentration by more than 30%. In addition, a higher ratio of methane in the blended fuel increased the ignition delay time as a result of methane dehydrogenation, delaying the ignition of heptane.