甲醇对氨着火特性的影响与动力学分析

Effect of Methanol on Ignition Characteristics of Ammonia and Chemical Kinetic Analysis

利用激波管试验平台测量了氨/甲醇混合气在不同当量比、不同掺混比、高温中低压条件下的着火延迟期。基于试验数据,提出了一个新的组合简化模型(NH_(3)-M),能够较好地预测氨/甲醇混合气的着火延迟期,基于该模型进行了化学反应动力学分析。结果表明,添加5%(摩尔分数)的甲醇可以使氨/甲醇混合气的着火延迟期缩短60%以上,氨/甲醇混合气着火延迟期的对数和着火温度的倒数均满足线性关系,影响该混合气的着火延迟期主要是OH、O、HO_(2)、H等小分子自由基,氨和甲醇最初的消耗均从脱氢反应开始,R224H+O_(2)=O+OH是敏感度最大的着火促进反应,R466:CH_(3)OH+NH_(2)=NH_(3)+CH_(3)O和R467:CH_(3)OH+NH_(2)=NH_(3)+CH_(2)OH并不直接促进着火,而是产生的中间产物进而生成活性物质促进了整个反应的进行。

The ignition delay times of ammonia/methanol mixtures were measured by a shock tube at different equivalence ratios,high temperature and medium-low pressure.A new combined simplification model(NH_(3)-M)was proposed and it can well predict the experimental ignition delay times of ammonia/methanol mixtures,Chemkin-PRO software was used to analyze the chemical reaction kinetics based on NH_(3)-M model.The results show that adding a small amount of methanol can significantly shorten the IDTs of ammonia/methanol mixtures.The ignition delay time satisfies the Arrhenius relation,it is mainly affected by small radicals such as OH,O,HO_(2) and H.The initial consumption of ammonia and methanol mixtures begins with H-abstraction,R224 is the most sensitive ignition-promoting reaction,it is not R466 and R467 that directly promote ignition but the active substances generated from the intermediates produced by R466 and R467 that facilitate the entire reactions.