Innovative Emission Aftertreatment System for Super Clean Diesel Engine Using Nonequilibrium Plasma Process

开发了一种新型的超净柴油机等离子体排气净化系统，并对其进行了基础研究。本研究的特点是利用低温非热非平衡等离子体。研发“1。非平衡等离子体DPF（柴油机微粒过滤器）再生”和“2。进行了非平衡等离子体脱附和NOx还原的研究。1.非平衡等离子体DPF再生：提出了一种新的DPF捕集柴油机微粒的焚烧再生系统，并利用常压低温等离子体对该系统的性能进行了优化。该系统利用低温等离子体激发的NO_2、臭氧和负离子自由基团簇，在近室温下对柴油机微粒进行净化。使用小型柴油发动机，在发动机操作期间的连续再生几乎在20 ° C的排气温度下进行。 ...更多信息 0℃。能耗进一步降低到1 Wh/m^3.2.非平衡等离子体脱附还原NOx：柴油机尾气中约2 × 10 vol.%的氧通常是包含的。将等离子体应用于这样的废气，总NOx（= NO + NO_2）量几乎没有减少，因为废气中所含的大部分NO仅被氧化成NO_2。该过程不被认为是真实的污染控制过程。因此，提出了以下新工艺：在富氧状态下，含有NOx的废气首先被吸附到反应器中的吸附剂上。在NOx吸附达到饱和后，将N_2气体或通过改变发动机运行模式获得的含有较多HC、CO和较少O_2的废气以小流量引入反应器中，施加等离子体。结果，NOx的脱附和还原以及HC和CO的氧化同时进行。在实验室试验中，对于250 ppm的NOx，能量效率为22 Wh/m^3，去除率超过85%。此外，对本系统处理一台小型柴油机（200 cc）的全部废气进行了检验。对非平衡等离子体化学过程进行了数值模拟，阐明了等离子体处理废气的详细机理（化学反应）。少

A new type plasma exhaust cleanup system for super clean diesel engine in near future is developed and basic study on it is carried out. This research is characterized by utilizing low-temperature nonthermal and nonequilibrium plasma. Research and development of "1. Nonequilibrium plasma DPF (Diesel particulate filter) regeneration" and "2. Nonequilibrium plasma desorption and reduction of NOx" are made. The following results are obtained.1.Nonequilibrium plasma DPF regeneration : A new incineration regeneration system of the diesel particulates trapped by the DPF is demonstrated and the performance is optimized using the atmospheric-pressure nonthermal plasma. In this system, NO_2, ozone and negative ion radical clusters excited with the nonthermal plasma are introduced into the DPF to realize the removal of the diesel particulate nearly at the room temperature. Using a small diesel engine, continues regeneration during the engine operation is performed nearly at the exhaust gas of 20 … More 0℃. Energy consumption is further decreased down to 1 Wh/m^3.2.Nonequilibrium plasma desorption and reduction of NOx : In the exhaust gas of diesel engines, the oxygen of approximately 2〜10vol.% is usually contained. Applying the plasma to such exhaust gas, the total NOx (= NO + NO_2) amount hardly decreases because most of NO contained in the exhaust gas is only oxidized to NO_2, This process is not considered to be a real pollution control process. Therefore, the following new process is proposed : In the oxygen rich state, the exhaust gas containing NOx is first adsorbed to the adsorbent in the reactor. After the NOx adsorption reaches saturation, either N_2 gas or the exhaust gas containing much HC, CO and less O_2 obtained by changing the engine operation mode is introduced into the reactor with the small flow rate, applying the plasma. As a result, the desorption and reduction of NOx, and oxidization of HC and CO are carried out simultaneously. More than 85% removal with the energy efficiency of 22Wh/m^3 for 250 ppm NOx is achieved in the laboratory test. Furthermore, the examination of the present system treating the whole exhaust gas of a small diesel engine (200cc) is carried out. The operation procedure and validity of the system are confirmed.3.The numerical simulation of nonequilibrium plasma chemistry is performed and the detailed mechanisms (chemical reactions) of the plasma exhaust gas processing are clarified. Less