摘要
采用详细的尿素沉积物模型,对尿素喷嘴内部的沉积物生成过程进行研究。在沉积物模型中,考虑了壁膜形成、蒸发、剥落、结晶和尿素副产物形成的基本过程,同时耦合了尿素热解的化学反应机理。以发动机台架和热重分析仪的试验结果,分别对喷嘴内壁面温度和尿素分解副产物的预测值进行验证。研究结果表明:模拟值与试验值基本一致,说明尿素沉积物模型可以较好地预测不同工况条件下尿素沉积的变化趋势。对尿素喷嘴内部的沉积物生成过程进行多维数值模拟结果表明:喷嘴内壁面温度在140℃以下时可以避免尿素分解副产物生成;在不出现硬结晶的条件下,排气温度为300℃和400℃工况(排气流量600kg/h)的最小喷射量分别为1000mL/h和2000mL/h。
A computational study on the process of deposit formation in urea injector was performed using a detailed deposit model. The deposit model includes the basic process of wall film formation, evaporation, entrainment, crystallization and by-product formation and incorporates the chemical reaction mechanism of urea thermal decomposition. The simulations of the inner wall temperature and deposit quality inside urea injector were validated respectively by the results of bench test and Thermal Gravity Analysis （TGA） ,showing a good agreement with experiment data. This indicates that the detailed deposit model can predict the trend of deposit under different working conditions. Meanwhile, a multi-dimensional numerical simulation was made to analyze the process of deposit formation in a urea injector. The result shows that byproduct formation or deposit can be avoided by keeping the temperature inside injector below 140℃. The minimum urea injection rates which has no by-product formation are 1000 mL/h and 2000 mL/h respectively when exhaust temperatures are 300℃ and 400℃ with the same exhaust flow rate of 600 kg/h.
出处
《内燃机工程》
EI
CAS
CSCD
北大核心
2015年第1期6-11,共6页
Chinese Internal Combustion Engine Engineering
基金
国家自然科学基金项目(51379165)
湖北省自然科学基金项目(20520005)
关键词
内燃机
详细沉积物模型
选择性催化还原
尿素喷嘴
计算流体力学
IC engine
detailed deposit model
selective catalytic reduction（SCR）
urea injector
computational fluid dynamics （CFD）
