基于格子Boltzmann方法，对应用于柴油机的选择性催化还原（SCR）进行了介观尺度数值模拟。采用D2Q9模型描述速度场，D2Q5模型描述浓度场，通过耦合化学反应分析了空速比、催化剂孔隙率及颗粒半径对柴油机SCR脱硝效率的影响，并描述了介观尺度上SCR反应过程中的流动、扩散与反应现象。其中，空速比选取范围为10 000~50 000/h，催化剂颗粒半径选取范围为400~800 μm，孔隙率选取范围为0.65~0.85。研究结果表明：气体在催化剂中会优先沿较宽的孔道流动和扩散，且在空速比增加时，孔隙较宽处的流速明显增加并降低NO转化率，因此，在催化剂生产中应保证孔隙的均匀性；当孔隙率增加时，计算域的入口处的NO质量分数降低得更快，但计算域的出口处NO质量分数更高，因此在布置催化剂时可考虑在入口布置孔隙率较大的催化剂；当催化剂半径增加时，降低了NO转化率，因此在催化剂生产中，应对焙烧温度进行控制，防止催化剂团聚。

The mesoscale numerical simulation on the selective catalytic reduction (SCR) applied in diesel engine was performed by the lattice Boltzmann method.D2Q9 model was used to describe the velocity field,and D2Q5 was used to describe the concentration field.The influence of space velocity ratio,catalyst porosity and particle radius on the diesel engine SCR denitration efficiency was analyzed by coupled chemical reactions,and the flow,diffusion and reaction phenomena in the SCR reaction process on the mesoscale were described.The space velocity ratio,catalyst particle radius and porosity were selected in the range of 10 000 to 50 000 per hour,400 to 800 μm and 0.65 to 0.85 respectively.The study results show that the gas will preferentially flow and diffuse through the wider pores in the catalyst, with the space velocity increasing,the flow velocity at the wider pores increases significantly and the NO conversion rate is reduced.Therefore,the uniformity of the pores should be ensured in the catalyst production.The NO mass fraction at the inlet of computational domain decreases faster and the NO mass fraction at the outlet is higher as the porosity increases.Therefore,when arranging the catalyst,it may be considered to arrange the catalyst with larger porosity at the inlet.When the radius of the catalyst increases,the NO conversion rate is reduced,so in the process of catalyst production,the calcination temperature should be controlled to prevent from catalyst agglomeration.

TK09

国家自然科学基金(51976129)；上海理工大学科技发展项目(2019KJFZ192)