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Influence of the cell geometry on the conversion efficiency of oxidation catalysts under real driving conditions
Energy Conversion and Management ( IF 9.9 ) Pub Date : 2021-02-22 , DOI: 10.1016/j.enconman.2021.113888
Pedro Piqueras , María José Ruiz , José Martín Herreros , Athanasios Tsolakis

Worldwide pollutant regulations applied to the transportation sector are progressively tightening the emission limits and widening the operating conditions of the type approval tests. As a result, the layout and thermal management of the exhaust system is becoming highly complex looking to achieve early catalytic converter activation. On this regard, the monolith meso-geometry plays a primary role to optimise the pollutants conversion efficiency. The geometrical characteristics simultaneously affect and trade-off multiple flow phenomena as the exhaust gas is transported through the channels. These include the bulk gas and internal pore diffusion towards the active sites in addition to the heat transfer including convection, radial conductivity and thermal capacitance. In this work, the impacts of the cell size, cross-section shape, washcoat loading and substrate material on CO and HC conversion efficiency have been investigated under representative real driving conditions. From the real driving conditions experimental data, the study decouples the influence of the washcoat loading from the cell size and material applying a catalytic converter model. Detailed expressions are provided for the calculation of the specific surfaces and heat and mass transfer parameters as a function of the cell and washcoat meso-geometry in square and triangular cells. Therefore, this work enables to identify the processes which govern the catalytic abatement of pollutant emissions. In particular, the role of the gas and washcoat specific surfaces is highlighted because of its importance on the optimization of the mass transfer process by means of a proper cell geometry selection. In parallel, the differences in the change of the CO and HC abatement patterns, which are explained by the characteristic CO emission spikes in accelerations and the HC accumulation, contribute to evidence the limitations on the conversion efficiency benefit that the optimum cell geometry and washcoat loading can provide.



中文翻译:

实际驱动条件下电池几何形状对氧化催化剂转化效率的影响

适用于运输行业的全球污染物法规正在逐步收紧排放限值,并扩大了型式认可试验的操作条件。结果,为了实现早期催化转化器的活化,排气系统的布局和热管理正变得非常复杂。在这方面,整体式介观几何起着优化污染物转化效率的主要作用。当废气通过通道传输时,几何特性同时影响和权衡多种流动现象。除了包括对流,径向传导性和热容的热传递之外,这些还包括大量气体和内部孔隙向着活性部位的扩散。在这项工作中,单元大小,横截面形状,在代表性的实际行驶条件下,研究了修补基面涂料的添加量以及基质材料对CO和HC的转化效率。从实际驾驶条件下的实验数据来看,该研究使用催化转化器模型将修补基面涂层负载的影响与单元尺寸和材料分离开来。提供了详细的表达式,用于计算特定的表面以及传热和传质参数,这些参数是方形和三角形单元中单元格和修补基面细观几何的函数。因此,这项工作使得能够确定控制污染物排放的催化减排的过程。尤其要强调气体和修补基面特定表面的作用,因为它对于通过适当的孔几何结构选择来优化传质过程非常重要。在平行下,

更新日期:2021-02-22
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