Optimisation design of short pitch spiral hybrid SCR structure for improving the exhaust performance

Abstract

As exhaust emission standards become increasingly stringent, the requirements for diesel exhaust post-treatment systems become increasingly demanding. This research focuses on the optimisation of a new hybrid structure to improve the performance of exhaust post-treatment systems. First, a short pitch spiral mixing chamber with sufficient mixing space and low temperature loss was designed to improve the evaporation of liquid droplets. Additionally, a conical plate mixer was used to conduct secondary mixing of the gas to improve the flow characteristics further. The ammonia uniformity and crystallisation risk of the new hybrid structure were simulated using Computational Fluid Dynamics, and the optimal hybrid structure was verified by tests. The results showed that ammonia leakage, low temperature crystallisation and NOX conversion efficiency could effectively be improved by optimally designing the new hybrid structure. This research is of great significance for reducing exhaust pollution and optimising diesel exhaust post-treatment systems.