Study on Diesel Engine Selective Catalytic Reduction Performance at Different Atmospheric Pressures Using the Response Surface Method.

Abstract

Nitrogen oxides (NO x ) are the main emissions of diesel engines. Selective catalytic reduction (SCR) is the main technology used to reduce NO x emissions from diesel engines. NO x conversion efficiency and ammonia (NH3) escape are the main indicators to evaluate SCR performance. In this work, the effects of diesel engine exhaust temperature and exhaust mass flow rate on the SCR performance under different atmospheric pressures were studied by the combination method of experiment and one-dimensional numerical simulation. At the same time, the response surface method (RSM) was used to analyze the interaction of atmospheric pressure, exhaust temperature, and exhaust mass flow rate on the SCR performance. The results show that the lower the atmospheric pressure, the lower the NO x conversion efficiency and ammonia escape. Under the same exhaust temperature, the lower the atmospheric pressure, the smaller the impact of exhaust mass flow rate on NO x conversion efficiency. According to the RSM results, the optimal NO x conversion efficiency is 78.6% under the combination working conditions of an atmospheric pressure of 100 kPa, exhaust temperature of 395 °C, and exhaust mass flow rate of 250 kg/h, and the NH3 escape is also at a low level of 1.7 g/cycle.