Experiment investigation on the effects of air assisted SCR spray impingement on wall temperature evolution

Abstract

Abatract Wall temperature distribution and evolution is a crucial factor for solid deposit formation in SCR system. An experiment is established to investigate wall temperature evolution under different SCR spray impingement conditions with the infrared thermography. The wall temperature evolution is ananlyzed based on the theory of the impingement and the heat transfer theory. The research results indicate that the increasing injection rate promotes the cooling rate of the wall and the spread of the low temperature area for the higher spray impingement density. Lower injection height leads to the break up of droplets and accerates the evaporation. The cross-flow causes the asymmetric distribution of wall temperature around the impinging center. The temperature profiles and the impinging center shift downstream along the direction of the cross-flow. The average temperature gradient presents a descent initially and a slight rise subsequently with the increase of the cross-flow velocity. When the initial wall temperature is 225 °C, the heat flux reaches the peak and the temperature drops fast, when the initial wall temperature is higher than 260 °C, the wall temperature hardly changes due to the leidenfrost effect.