天然气发动机EGR混合器加热仿真与试验研究

刘志治，黄林^*，韦钻国

广西玉柴机器股份有限公司，广西 玉林  537005

摘要：为解决天然气发动机的废气再循环（exhaust gas re-circulation,EGR）混合器结冰问题，以K13N天然气发动机的EGR混合器为研究对象，利用ANSYS Fluent软件计算增加水循环加热结构后EGR混合器出口气体的温度、速度及压力分布情况；根据仿真计算结果制作EGR混合器样件，并搭载车辆进行低温环境试验。结果表明：天然气发动机EGR混合器增加水循环加热结构后，发动机在环境温度为-40 ℃、怠速工况运行时，天然气发动机EGR混合器出口的气体温度可以升高6.5 ℃；使用带水循环加热结构EGR混合器的车辆，在温度为-25 ℃的低温环境中进行长怠速工况、长下坡工况、综合工况试验后，天然气发动机EGR混合器均未结冰，发动机工作正常；仿真计算结果与试验结果基本吻合，带水循环加热结构的天然气发动机EGR混合器可有效解决国六天然气发动机EGR混合器结冰问题。该研究对解决天然气发动机EGR混合器结冰问题具有一定的参考价值。

关键词：天然气发动机；EGR；EGR混合器；结冰；混合气温度

Simulation and experimental study on heating of EGR mixer of natural gas engine

LIU Zhizhi, HUANG Lin^*, WEI Zuanguo

Guangxi Yuchai Machinery Co., Ltd., Yulin 537005, China

Abstract：In order to solve the icing problem of exhaust gas re-circulation (EGR) mixer of a natural gas engine, based on the mixer of K13N natural gas engine, ANSYS Fluent software is used to calculate the temperature, velocity and pressure distribution of the mixer outlet after adding the water cycle heating system. According to the simulation results, a sample mixer is made and carried on the vehicle for cold storage test. The results show that the gas temperature at the engine EGR mixer outlet increases by 6.5 ℃ when the engine operates at -40 ℃ ambient temperature and idle speed after adding the water cycle heating system. The vehicle with water cycle heating mixer has been tested in the cold storage at -35 ℃ under the conditions of long idle speed, long downhill condition and comprehensive condition, and the EGR mixer does not freeze, and the engine works normally. The simulation results are basically consistent with the test results. The mixer with water circulation heating can effectively solve the icing problem of the EGR mixer in the CHINA Ⅵ natural gas engine. This study can provide a reference for solving the icing problem of EGR mixer of natural gas engine.

Keywords:natural gas engine; EGR;EGR mixer; ice; temperature of mixed gas