| 摘要 |
For each cell x, y of an X . Y matrix in the NOx storage catalyst, loading and unloading with NOx and SOx is calculated iteratively as function of the following: NOx and SOx emissions ahead of the catalyst, temperature of the catalyst discs x or the exhaust gas temperature ahead of the catalyst, exhaust gas mass flowrate and the lambda value ahead of the catalyst. X is the number of catalyst discs in the direction of flow; x and y are the numbers of successive wash coats in their thickness direction y. Calculation of loading and unloading is effected successively for each catalyst disc x, where x lies between unity and a maximum value X in the flow direction x. It is effected inside each catalyst disc successively from the outermost (x, 1) to the innermost wash coat cell (x, Y). Preferred Features: Calculated NOx and SOx emission from the xth catalyst disc is used as an input magnitude for the (x + 1)th catalyst disc. Starting from an NOx storage of 100%, for each cell, the storage is corrected by four factors (N1-N4), each of which can represent a group of effects. N1 represents the reaction dynamics of the NOx storage catalyst in the X direction, as a function of temperature and spatial velocity. N2 represents decrease in NOx storage capability as a result of thermal aging. N3 represents decrease of NOx storage capability as a result of sulfur storage, N4 represents reduction of NOx storage capability by saturation of the storage cells with nitrates. The factors are further analyzed, for example, N2 is a collective function of N2.1, N2.2 and N2.3, representative of damage to the storage components, damage to the noble metal components and separation of the storage and the noble metal components. The method is further detailed and developed, applying a closely-similar treatment, to represent the storage capability for SOx.
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