作　　者： (徐晓川）; (石秀勇）; (倪计民）; (童凯麟）;

机构地区： 同济大学汽车学院,上海201804

出　　处： 《小型内燃机与车辆技术》 2017年第4期36-45,共10页

摘　　要： 目前对于EGR冷却系统常采用单一的FLUENT流场分析方法研究EGR冷却器冷却特性,而实际中作为清洁柴油机机内净化的重要组成部分,发动机整机运行对于EGR冷却器特性影响显著。针对以上问题,采用BOOST与CFD联合仿真的方法,对于EGR冷却系统冷却特性进行了研究。基于BOOST建立EGR冷却器及发动机模型,采用十三工况法对原机进行冷废气再循环的模拟,取得EGR冷却器的进出口数据,并且以之作为边界条件,采用CFD对EGR冷却器进行热力学计算和结构优化。结果表明,优化后换热器中间换热管中气体的速度明显比优化前的换热管中气体的速度要低10%左右;冷却器的换热效能随着EGR流量的增加而降低;优化后的换热器在高EGR流量下比优化前所有情况下的换热器效能都高,而在低流量低入口温度的工况下则没有明显区别;EGR冷却温度的降低对新鲜空气流量和EGR率有显著的提升,可以在很大程度上提高EGR系统的工作能力,从而大大降低NO_x的排放。 At present, a single FLUENT flow field analysis method is used in the EGR cooling system characteristics study, but as an important purification part of clean diesel machine, the engine operation has significant influence on EGR cooler characteristics. Aiming at the above problem, a method of joint simulation between BOOST and CFD is adopted in cooling characteristics of EGR cooling system. The EGR cooler and engine model is established based on BOOST, and 13 operating conditions method is adopted in the simulation of cold exhaust gas recirculation in a primary engine, and then the import and export data for EGR cooler is obtained. Thermodynamic calculation and structural optimization of EGR cooler is carried out by CFD based on the above data. The results show that, the velocity of gas in the middle heat exchange tube of the heat exchanger is obviously 10% lower than that of the heat exchange tube before the optimization; The heat transfer efficiency of cooler decreases with the increase of EGR flow rate; The optimized heat exchanger has high heat efficiency in all cases at high EGR flow, but at low flow and low inlet temperature, there is no obvious difference; The decrease of EGR cooling temperature significantly increases the fresh air flow rate and EGR rate, and the work ability of EGR system is greatly improved,while the NOxdischarge decreases significantly.

关 键 词： 冷却器 换热效能 流动过程 压力损失