PODE_(3)/异辛烷二元燃料实验与简化动力学模型研究

Experiment on PODE_(3)/Iso-Octane Binary Fuel Mixtures and Simplified Kinetic Modeling

聚甲氧基二甲醚(PODE)具有高十六烷值、高含氧量和互溶性好等燃料特性,目前PODE通常与传统燃料混合使用,具有显著改善内燃机热效率和有害物排放的潜力.本文首先基于射流搅拌反应器开展典型汽油替代物异辛烷与高活性代用燃料PODE_(3)混合燃料的低温氧化实验,然后通过简化PODE_(3)详细机理并耦合异辛烷/正庚烷机理构建了包含108个组分和434个反应的PRF-PODE_(3)简化机理.利用该机理模型对PODE_(3)/异辛烷燃料进行了滞燃期、层流预混火焰和射流搅拌反应器的实验验证并获得了良好的预测结果.PODE_(3)/异辛烷低温氧化实验及模拟结果表明,掺混PODE_(3)后,会在低温反应阶段产生大量的OH、HO_(2)、CH_(3)等活性基,从而促进异辛烷的低温反应,且随着掺混比例的提高,异辛烷低温反应明显增强.异辛烷中添加PODE_(3)对于CH_(4)、C_(2)H_(6)等中间产物影响较小,但会显著降低C_(2)H_(4)和C_(3)H_(6)等中间产物的浓度,具备显著改善PAH和碳烟生成的潜力.

Polyoxymethylene dimethyl ether(PODE)has a lot of advantages,such as high cetane number,high oxygen content and good mutual solubility.At present,PODE-traditional fuels blends are used to improve the thermal efficiency and reduce harmful emissions of internal combustion engines.First,based on the jet-stirred reactor experimental platform,this paper carried out a low-temperature oxidation experiment on high-reactivity PODE_(3) and gasoline surrogate of iso-octane mixed fuel.Then,a simplified PODE_(3) sub-mechanism was coupled to the isooctane/n-heptane mechanism to construct a simplified mechanism of PRF-PODE_(3) containing 108 species and 434 reactions.This reduced mechanism was extensively validated against experimental data including ignition delay times,laminar flame speeds,and jet-stirred reactor,and a good prediction was obtained.The low-temperature oxidation experiment and simulation results indicated that the addition of PODE_(3) can produce a large number of active groups such as OH,HO_(2),CH_(3) before rapid reaction,thus increasing the low-temperature reaction of isooctane.As the mixing ratio increases,the low-temperature reaction of iso-octane is significantly enhanced.With the increased mole fraction of PODE_(3),the values of CH_(4) and C_(2)H_(6) remain unchanged,and those of C_(2)H_(4) and C_(3)H_(6) are greatly reduced,indicating that PODE_(3) has the potential to reduce the polycyclic-aromatic hydrocarbon and soot emissions.