摘要
根据某柴油机设计一款喷嘴集成式选择性催化还原(SCR)系统,使其排放满足国Ⅴ标准,结晶量小于3g。首先研究穿孔管加混合器结构,结果表明这种结构的载体前端面蒸汽均匀性系数和尿素蒸发量不能满足设计要求,且在混合器上会形成大块结晶。随后提出一种新型混合腔结构,分析表明:载体前端面速度和蒸汽均匀性系数分别为0.95和0.98,载体能被充分利用;喷射系统采用三孔气助喷嘴,使得喷出的液滴直接撞向内筒圆管,在内筒圆管的高温作用下,液膜全部蒸发;此外尿素喷射轨迹会在底部形成2个较大旋涡,促进了液滴的雾化与混合。试验验证此结构SCR排放满足国Ⅴ标准,在低温工况下NO_x转化效率明显高于其他结构,尿素结晶满足设计要求。
A SCR system with an integrated nozzle was designed for a certain type of diesel engine to meet the national V emissions standard with crystallized urea less than 3 g. First the structure of a perforated pipe combined with a mixer was studied. The results show that both the uniformity coefficient of steam at the carrier front face and the urea evaporation cannot meet the requirements, and there is large block of crystal on the mixer. Then a new type of mixing chamber structure was proposed. With the new structure, the velocity and steam uniformity coefficient at the carrier front face are 0.95 and 0.98 respectively, and the catalyst carrier can be utilized fully. The injection system composed of three-hole nozzle with air-aid spray makes injected droplets hit against the cylinder surface directly. Due to high temperature, liquid film evaporates entirely. In addition, urea injection trajectory forms two large vortexes at the bottom, which promotes the atomization and mixing of the droplets. Finally, an experiment was made, and it verified that this new SCR system meets the national V emissions standards. The conversion efficiency of NO~ is higher than other structures at low temperature and the urea deposition meets the design requirements.
作者
臧志成
魏家星
卢凯
郭官清
吴燕
ZANG Zhicheng WEI Jiaxing LU Kai GUO Guanqing WU Yan(Kailong High Technology Co. ,Ltd. ,Wuxi 214177,China)
出处
《内燃机工程》
EI
CAS
CSCD
北大核心
2017年第4期103-108,共6页
Chinese Internal Combustion Engine Engineering
基金
江苏省科技成果转化专项资金项目(BA2012045)~~
