Effect of methanol and ethanol on n-decane pyrolysis process by ReaxFF simulation and experiment validation

Alcohol assisted hydrocarbon fuels regenerative cooling is a promising method to deal with scramjet engine heat management of hypersonic flight vehicle. To reveal the effect of alcohol on hydrocarbon fuels pyrolysis pathway, ReaxFF molecular dynamics simulation was done to investigate the variation of intermediate fragments in methanol/ethanol assisted n-decane pyrolysis process. Results shows that, two alcohols increase the initial cracking temperature of n-decane. Two alcohols turn the first-step cracking products of n-decane from C₃H₇ + C₇H₁₅ to C₅H₁₁ + C₅H₁₁, and make n-decane cracking into C₂H₅ + C₈H₁₇ possible. Initial pyrolysis of n-decane with methanol and ethanol can be coupled by CH₃ and C₂H₅ free radical respectively. In the subsequent pyrolysis process, C10 are completely consumed within 10 ps. C7-C9 fragments are transient intermediates and can hardly accumulate. Experiment indicates that 450–500 °C is the decisive temperature range for n-decane cracking, and adding methanol or ethanol increase the initial cracking temperature of n-decane pyrolysis.