基于OH^(*)的NH_(3)-H_(2)-DME高温自着火特性

High-Temperature Self-Ignition Characteristics of NH_(3)-H_(2)-DME Based on OH

氨(NH_(3))作为一种十分有前景的零碳替代燃料,其低反应性限制了它的发展和应用,而掺混与其特性互补的其他低碳或零碳燃料,可明显改善其燃烧特性.基于此,在激波管试验平台上利用反射激波和燃料激发态羟基(OH^(*))的自发光特性,测量了温度T为1 300~2 000 K、压力p为0.14 MPa与1.00 MPa且当量比φ为0.5、1.0和2.0条件下,NH_(3)-氢(H_(2))-二甲醚(DME)三元燃料与空气混合燃料的着火延迟期(IDT),并研究了H_(2)+DME作为二元活性剂,其比例在各工况下对纯NH_(3)混合燃料着火延迟期缩短率的影响.结果表明:活性组分比例会影响活性剂的着火促进效果,活性剂H_(2)+DME(摩尔分数比为1∶1)相比同比例下的单一活性剂可以降低混合燃料更多的活化能.三元混合燃料的着火特性随活性剂比例、反应条件不同,有截然不同的特点,其中,在稀燃条件下,H_(2)+DME(摩尔分数比为2∶1)着火促进效果更好,而在富燃条件下,H_(2)+DME(摩尔分数比为1∶2)活性更高.

Ammonia(NH_(3))is a very promising zero-carbon alternative fuel,but its low reactivity limits its development and application.Blending other low-carbon or zero-carbon fuels complementary to its low reactivity characteristics can significantly improve its combustion characteristics.The ignition delay time(IDT)of NH_(3)-hydrogen(H_(2))-dimethyl ether(DME)ternary blended fuels with air was measured under the temperature variation from 1300—2000K,the pressure of 0.14 MPa and 1.00 MPa,and the equivalence ratio of 0.5,1.0 and 2.0 respectively,by using reflected shock wave and the self-luminescence property of fuel excited hydroxyl group(OH^(*))on a shock tube experimental platform.The experiment focused on the effects of the blending ratio of binary activator H_(2)+DME on the shortening rate of pure ammonia under each working condition.Results show that the equivalence ratio affects the ignition promotion of the activator,and the H_(2)+DME(mole fraction ratio is 1∶1)can reduce the activation energy more than the single activator at the same mixed ratio.The ignition characteristics of the ternary fuel show obviously different depending on the activator ratio and reaction conditions,where the higher hydrogen ratio of H_(2)+DME(mole fraction ratio is 2∶1)has a better ignition promotion effect under the lean-burn combustion conditions,and H_(2)+DME(mole fraction ratio is 1∶2)is more active under the fuel-rich conditions.