Chemical Kinetics Study on Combustion of Ethanol/ biodiesel-heptane

摘要

Methyl decanoate (MD), methyl-9-decanoate (MD9D), and n-heptane (H) as alternative blends of biodiesel (B) were used to build a detailed chemical kinetic mechanism containing 3,324 components and 11,053 elementary reactions. This condition verifies that the ignition delay time of the detailed mechanism in the experiment conditions is reasonable. MD and MD9D will produce methyl-2-palmitate (MP2D) and finally be dehydrogenated as CH2O. Furthermore, R4 (O + H2O + OH) and R228 (CH2CHO + O-2 - CH2O + CO + OH) are the key reactions, which will influence the ignition delay and heat release. According to the simulation result, the rate of BH (the volume ratio of the biodiesel-heptane mixture is fixed at 20%/80%) in constant volume bomb (Cetane Ignition Delay 510, CID 510) is the highest. However, with the development of ethanol, the rates decreased. The reactors of BHE5 (BHE5 refers to a blend of 5% ethanol and 95% biodiesel-heptane) have the highest rate among the ethanol blends. In addition, the reaction rate of the intermediate substance of ketohydroperoxide (KHP) in a modified cooperative fuel research engine (CFR) during combustion decreased with ethanol addition. However, the KHP rate of BHE15 (BHE15 refers to a blend of 15% ethanol and 85% biodiesel-heptane) and BHE20 (BHE20 refers to a blend of 20% ethanol and 80% biodiesel-heptane) is similar, causing the closed onset of low-temperature heat release. The rate of CH2O and MP2D of BH is the highest over the others in CID 510. The rate of CH2O and MP2D of BHE5 is lower than that of BHE10 (BHE10 refers to a blend of 10% ethanol and 90% biodiesel-heptane), BHE15, and BHE20. (C) 2019 Elsevier Ltd. All rights reserved.