柴油机 SCR 系统快速老化方法研究

A general accelerated aging method for the selective catalytic reduction(SCR) system of diesel engines was developed based on the principle of thermal aging and Arrhenius equation，and the equivalence between accelerated aging and conventional aging methods was verified by engine tests. The test results show that a significant temperature difference appears in the deterioration of NO_x conversion efficiency of the SCR system. The constructional damage of the SCR catalyst by thermal aging and the deterioration of NH₃ storage capacity is the main reasons for the significant deterioration of SCR under low-temperature working conditions. The linear correlation coefficient between the world harmonized transient cycle(WHTC)-NO_x emission and equivalent durability mileage is 0.988，and the error range between the measured WHTC-NO_x factors and the fitted values used to verify the equivalence of conventional aging is in a range of -4.12% to 3.13%，proving that the accelerated aging method has good equivalence with the conventional aging method. Based on the test data，the tested China-Ⅵ diesel engine will exceed the durability emission limit of 0.46 g/(kW·h) after 0.80×10⁶ —1.06×10⁶ km and will exceed the on board diagnostics(OBD) limit of 1.20 g/(kW·h) after 3.13×10⁶ —3.67×10⁶ km.