柴油机氧化催化器喷油助燃特性研究

Fuel Injection Assisted Combustion Characteristics of Diesel Oxidation Catalyst

基于发动机台架开展了柴油机氧化催化转化器(DOC)喷油助燃特性试验,研究分析了尾管喷油时DOC温升及对尾气后处理系统排放特性的影响。研究结果表明:尾管喷油能够使DOC在100 s内迅速升温,温升幅度随转速的升高而降低,并且来流温度越高、转速越高,温升速度就越快。为保证柴油机颗粒捕集器(DPF)前有足够高的温度,应对排气温度、空速、喷油脉宽进行合理的控制。在柴油喷射前,总碳氢(THC)排放浓度均接近零,在柴油喷射的瞬间,THC浓度飙升,高排气温度、低空速、小喷油量有利于控制碳氢泄漏,同时柴油喷射会降低NO_(2)产率。

The fuel injection assisted combustion characteristics test of diesel oxidation catalyst was conducted on the engine bench.The DOC temperature rise and aftertreatment emission performance were analyzed through the fuel injection in tail pipe.The result shows that the temperature of DOC increases rapidly within 100 seconds through the fuel injection,the temperature rise decreases with the increase of rotational speed and becomes faster with the higher temperature of incoming flow and the higher speed.In order to keep a high enough temperature before DPF,it is necessary to control the exhaust temperature,air velocity and injection pulse width reasonably.THC concentration is near to zero before diesel injection and sharply increases at the moment of injection.Accordingly,high exhaust temperature,low air velocity and small injection volume are conducive to THC leakage control.Besides,diesel injection can reduce NO_(2)production.