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.

Oxidation of Methane/n-Heptane Mixtures in a High-Pressure Flow Reactor

“…The ignition of methane/n-heptane mixtures has been investigated in RCM at intermediate temperatures (785−1285 K) 45,46 and in shock tubes at high temperature (1200−1825 K). 47−49 Methane/diesel mixtures were also studied in both RCM 50 and shock tubes.…”

“…The ignition of methane/ n -heptane mixtures has been investigated in RCM at intermediate temperatures (785–1285 K) , and in shock tubes at high temperature (1200–1825 K). − Methane/diesel mixtures were also studied in both RCM and shock tubes. , The studies show that addition of even small amounts of n -heptane or diesel decreases the ignition time for methane significantly. Published kinetic models capture the enhancement of methane oxidation in the presence of n -heptane. − …”