尿素喷射策略对柴油机排放性能影响的试验研究

彭滔¹，余道广²，崔员萦³，张革成¹，孙柯¹，白书战^1*

1.山东大学核科学与能源动力学院，山东 济南  250061；

2.山东大学后勤保障部，山东 济南  250061；

3.山东财经大学工商管理学院，山东济 南  250014

摘要：为提高NO_x转化效率、减少氨泄漏，对采用选择性催化还原（selective catalytic reduction，SCR）技术的柴油机排气后处理系统开展试验，研究不同空速和温度下的尿素不均匀喷射对NO_x转换效率、氨储存和氨泄漏的影响。试验结果表明：在固定的空速下，氨泄漏的程度与温度的变化有关，温度升高，催化还原反应加快，氨泄漏减小；温度对催化还原反应速率的影响较大，当空速为10 000 h^-1时，高温工况下SCR内的反应速率远高于低温工况；空速对催化还原反应速率的影响较小，相同温度下，当空速由10 000 h^-1增大为40 000 h^-1时，SCR内的平均反应速率基本不变；但提高空速加剧氨泄漏，抵消NO_x转化效率提高获得的效益。

关键词：柴油机；氨泄漏；转换效率；反应速率；空速

Experimental study on the influence of urea injection strategy of the emission performance for diesel engine

PENG Tao¹, YU Daoguang², CUI Yuanying³, ZHANG Gecheng¹, SUN Ke¹, BAI Shuzhan^1*

1.School of Nuclear Science, Energy and Power Engineering, Shandong University, Jinan 250061, China;

2.Logistics Surport Department, Shandong University, Jinan 250061, China;

3.School of Business Administration, Shandong University of Finance and Economics, Jinan 250014, China

Abstract: To improve NO_x conversion efficiency and reduce ammonia leakage, the influence of heterogeneous flow injection of urea at different space velocity and temperatures on NO_x conversion efficiency, ammonia storage and ammonia leakage are investigated experimentally. The diesel engine used in the experiment employed an exhaust aftertreatment system with selective catalytic reduction (SCR) technology. The experimental results show that for a fixed air flow, the extent of ammonia leakage is related to changes in temperature. As the temperature increases, the catalytic reduction reaction accelerates and the ammonia leakage decreases. The temperature has a great influence on the catalytic reduction reaction rate. At a flow velocity of 10 000 h^-1, the reaction rate of SCR at high temperature is much higher than that at low temperature. The flow velocity has a weak influence on the reaction rate. When the flow velocity changes from 10 000 h^-1to 40 000 h^-1 at the same temperature, the average reaction rate within the SCR remained largely unchanged. However, increasing the flow velocity can accelerate the leakage of ammonia, thereby mitigating the benefits associated with the NO_x conversion.

Keywords: diesel engine; ammonia leak; conversion efficiency; reaction rate; flow velocity