Abstract

Exhaust after treatment systems are becoming more complicated with the ever-stricter emission regulations. To meet the regulation limits, a tightly packed high-performance system is required. In selective catalytic reduction (SCR) systems, ammonia (NH³) uniformity is a key performance indicator. In this work, a low flow intrusion automated device was designed to measure NOₜ reduction from the SCR catalyst outlet. A topological surface was reconstructed from the measurement data to obtain the shape of the distribution. Before the actual measurements, the method was theoretically tested with distribution extracted from computational fluid dynamics (CFD) simulations. The results show that in stable engine load conditions, uncertainty of the measurement was low, approximately 1.1% from the measured value. In the case of high uniformity, a satisfactory result can be obtained with 10 to 20 measurement positions, whereas in the case of low uniformity, the number of positions should be increased. The distribution shape between the measurements was consistent throughout the measurements.