重型柴油机后处理电加热技术研究

耿宗起^1，2，白书战^1*，仲昆²，吕志华²

1.山东大学核科学与能源动力学院，山东 济南  250061；

2.潍柴动力股份有限公司，山东 潍坊  261061

摘要：为提高柴油机排气温度，缩短选择性催化还原(selective catalytic reduction，SCR)系统起燃时间，降低重型柴油机冷态排放，在一台排量为13 L的重型柴油机后处理系统中增加电加热器，开展稳态工况和冷态全球统一瞬态测试循环（world harmonized transient cycle, WHTC）测温试验，并进行冷态WHTC下、电加热器功率分别为5.4、7.2 kW时的排放试验。结果表明：稳态工况下，电加热器功率稳定时，排气温度升高幅度和发动机排气流量成反比；冷态WHTC中，电加热功率越大，升温效果越好，SCR起燃时间越短，相应的能耗也越高；以SCR上游温度达到理想温度作为电加热器关闭的判断条件，与未加热相比，电加热功率分别为5.4、7.2 kW的两组冷态WHTC试验的循环NO_x排放分别下降了49%和53%，油耗分别增加2.6%和3.6%。

关键词：柴油机；排放；电加热器；NO_x；油耗

Electric heating technology study on the after-treatment ofa heavy-duty diesel engine

GENG Zongqi^1,2, BAI Shuzhan^1*, ZHONG Kun², LÜ Zhihua²

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

2. Weichai Power Co., Ltd., Weifang 261061, China

Abstract: In order to increase exhaust temperature, shorten the ignition time of selective catalytic reduction (SCR) system, and reduce cold emissions of heavy-duty diesel engines, an electric heater is added to the after-treatment system of heavy-duty diesel engine with a displacement of 13 L. Temperature measurement tests are conducted under steady-state and cold world harmonized transient cycle (WHTC), and emission tests are conducted under cold-state WHTC with electric heater power of 5.4 and 7.2 kW respectively. The results show that under steady-state conditions, when the power of the electric heater is stable, the increase in exhaust temperature is inversely proportional to the engine exhaust flow rate. In the cold-state WHTC cycle, the greater the electric heating power, the better the heating effect, the shorter the ignition time of the SCR, and correspondingly, the higher the energy consumption. The judgment condition for turning off the electric heater is that the upstream temperature of the SCR reaches the ideal temperature. Compared with the unheated state, the NO_xemissions of the two cold-state WHTC tests with electric heater power of 5.4 kW and 7.2 kW decreased by 49% and 52% respectively, and the fuel consumption increased by 2.6% and 3.6% respectively.

Keywords: diesel engine; emission; electric heater;NO_x; fuel consumption