ディーゼル微粒子の堆積とフィルタの再生過程の数値解析

摘要

現在，貨物トラックやバスなどディーゼル車は広くわれわれの生活に用いられている．ディーゼル車は耐久性がよぐ，高出力であるためこのような輸送手段に用いられる．また，ディーゼル車はガソリン車に比べて燃費がよいため，ヨーロッパでは乗用車に占めるディーゼル車の割合が50%を超えている．しかしながら，ディーゼル車から排出される排気ガス中の大気汚染物質が問題となっている．特に，粒子状物質（PM）は発がん性を有するため健康を損なうことが懸念されており，ヨーロッパのEuroVや日本のポスト新長期規制など排出ガス規制が強化されている．%Recently, more strict diesel particulate emissions standards are being set in many countries. To have an advantage of low fuel consumption in comparison with gasoline engines, several improvements including combustion conditions in diesel engines have been considered. As for the after-treatment of exhaust gas, a filter such as cellular diesel particulate filters has been widely used. In this study, we conducted fluid simulation in the diesel filter by the Lattice Boltzmann method. The soot deposition was considered for the soot trap inside the filter. The soot combustion. was also simulated to burn accumulated soot particles in filter regeneration process. The inner structure of the filter developed by COTEC Limited was obtained by a 3D-CT technique. Results show that the flow pattern is largely changed when the soot is attached to the filter wall, with higher back-pressure. The soot combustion is well simulated to show the effects of oxygen concentration on the temperature and reaction rate.