Experimental investigation of heat transfer characteristics of UWS spray impingement in diesel SCR

Abstract

To comply with the stringent regulations as stated in Euro6, the NOx emissions of heavy-duty vehicles have to be reduced by up to 80% compared to Euro5. Engine exhaust after-treatment SCR is a promising technique to reduce NOx emissions without sacrificing engine efficiency. The introduction of the reducing agent urea plays a significant role on the reduction reactions. The main challenges for the implementation of mobile urea-SCR systems include rapid decomposition and homogeneous distribution of urea and the mitigation of deposit formation. A key factor affecting these performances is the heat transfer characteristics of UWS spray under exhaust flow conditions. However, the heat transfer characteristics of UWS spray impingement have not been studied experimentally under exhaust flow conditions so far.

The present study is focused on the heat transfer characteristics of the impinging SCR spray in crossflow. The heat transfer characteristics of spray impingement are analyzed based on the temporal and spatial evolution of the wall temperature using infrared thermography. This work enhances the understanding of the wall impingement of UWS sprays.