玻纤增强微米木纤维滤芯净化柴油车尾气PM微观机理研究

The filter element of diesel particulate filter (DPF) formed by glass fiber reinforced micron wood fiber（GFR-MWF）can purify the particulate material (PM) emitted by diesel engine efficiently. The tracheid microscopic surface chambers, tearing microfibril and the tectonic cavities can make GFR-MWF in possession of great embedment capacity for PM. The study on the mechanism of purification for PM in GFR-MWF has great significance for the development of purification theory applying biological porous medium to filter diesel exhaust. First,we will produce some groups of filter elements with different parameters,develop an advanced DPF test bench and select the high quality filter elements that could meet with Chinese quality standard V for automotive diesel.Then,the filter elements and PM would be characterized and the micro models would be established. And meanwhile, the movement process and law during "steady-state" working stage would be simulated by using Monte Carle method. Furthemore, the dimensional model of random distribution of fibers would be established and the growth process of "particulate branches" would be simulated based on the modern filtration theory and Computational Fluid Dynamics(CFD),and then the motion characteristics and deposition form during "nonsteady-state" working stage would be analyzed. Last,we would try to discover the application extent and influence factors by comparing with filtration processes of many groups of filter elements,and obtain the filtration microcosmic mechanism of GFR-MWF by using experiments to verify the simulation results during "steady-state" and "nonsteady-state" working stage,which offer new method and theory foundation to develop and generalize the high performance DPF.

玻纤增强微米木纤维（GFR-MWF）组构柴油车尾气颗粒捕集器（DPF）滤芯可有效净化碳烟颗粒（PM）。GFR-MWF的管胞容腔、撕裂的微纤丝及组构形成的孔穴使其具备强大的嵌藏PM的能力。探索GFR-MWF滤芯净化PM机理，对发展生物多孔介质净化柴油车尾气理论具有重要意义。试制多组不同参数的GFR-MWF滤芯，研制高等DPF检测试验台并优选符合国V的滤芯；对滤芯和PM进行表征并建立微观模型，利用基于蒙特卡罗方法的粒子输运理论模拟PM在 "稳态"工作阶段的运动过程与规律；依据现代过滤理论和计算流体动力学等技术，建立随机分布的纤维立体模型，模拟 "颗粒树枝"生长过程，分析"非稳态"工作阶段的颗粒系统运动特性及沉积形式；对多组滤芯"稳态"和"非稳态"工作阶段模拟结果进行对比，探索理论方法的适用范围及影响因素，并通过实验进行修正，获得净化PM微观机理，为高性能木基滤芯的研发和推广提供有效的理论支持。

PM2.5是指大气中空气动力学直径小于或等于2.5μm，可对环境和人类健康造成极大危害的颗粒物。目前我国许多大城市都出现了严重的雾霾天气，其元凶就是PM2.5，而大气中25%~30%的PM2.5都直接来源于机动车尾气，其中柴油车排放的碳烟颗粒（PM）比例最大。研究表明，柴油车排放的PM2.5约为其总排放颗粒数的95%，因此控制柴油车尾气PM对降低大气PM2.5意义重大！.然而，由于柴油含硫量高和柴油车尾气颗粒捕集器（DPF）技术复杂等原因，在美国、欧洲、日本等国家已经成熟的柴油车尾气净化技术在我国仍无法推广使用。目前，国内绝大部分柴油车都没有安装PM净化装置，发动机产生的PM都被直接排入大气！研究对油品要求低、技术简单、价格便宜、安装方便的适合我国国情的柴油车尾气净化装置已迫在眉睫。.本项目组以玻纤为增强材料，利用微米木纤维制成玻纤增强微米木纤维（GFR-MWF）滤芯，该种滤芯不但能耐受柴油车尾管的温度与振动，而且过滤效率高、排气背压小、成本低、对油品无特殊要求。.在项目执行期间，我们先后完成了：符合国V标准的微米木纤维滤芯研发及PM“稳态”阶段过滤机理理论与试验研究；模拟纤维表面颗粒生长过程及其对过滤性能的影响，揭示 “非稳态”阶段过滤PM的微观机理；对微米木纤维滤芯及PM进行微观表征，利用理论和试验方法进行PM过滤机理微观研究。同时我们还进行了微米木纤维滤芯推广应用所需相关技术研究。共发表论文14篇，其中SCI 2篇，EI 2篇，获得授权发明专利3项，获得授权实用新型专利8项，培养研究生6名。.所研发的GFR-MWF管胞容腔、撕裂的微纤丝及组构形成的孔穴使其具备强大的嵌藏PM的能力，所以寿命长，一般5000~6000公里可随汽车保养更换滤芯，这相当于汽车空气滤清器的使用寿命，废弃的滤芯可回收利用，属于大力提倡的生态产品！.探索GFR-MWF滤芯净化柴油车尾气PM微观机理，对GFR-MWF滤芯的设计制造及推广具有重要的理论指导意义，同时对丰富和发展绿色环保生物多孔介质净化柴油车尾气理论具有重要的意义。