尿素SCR内における液滴径の計測と空気流れの可視化

抄録

The urea SCR system is paying attention as a technique for reducing NOx emissions since the NOx purification rate is high during normal engine operating and it can operate under an excessive oxidizing atmosphere. The urea SCR system reduces NOx to N2 and H2O by using urea aqueous. However, if urea aqueous is not sufficiently reacted, purification efficiency is lower depending on deposits. Therefore, many study have been conducted to improve the high efficiency of urea aqueous decomposition process, and uniform exhaust flow is presupposed. However, they are different from the actual phenomenon since the actual exhaust flow is irregular. Therefore, in this study, it was visualized and measured the droplet diameter and flow velocity for the purpose of clarifying the relationship between air and droplets. As a result, it was confirmed that the influence from the air to the droplets changed due to the difference in particle size, and that difference in speed occurred even with droplets and air at the same position. From these results, the influences of droplets having deferent particle sizes in the urea SCR and the air flow given to the droplet speed and examined improvement of vaporization efficiency of liquid droplets were clarified.