CNG重型车排气含水量对CO₂测量的影响

钟祥麟，李彤，黄鹏程，孟庆梁

中汽研汽车检验中心（天津）有限公司，天津   300300

摘要：为研究不同干湿基修正方法对压缩天然气（compressed natural gas, CNG）重型车冷起动阶段CO₂排放测量结果的影响，在底盘测功机上对某国六CNG车辆进行不同试验循环下冷起动测试，分别采用国六标准中推荐的干湿基修正法和排气中水的体积分数湿基修正法计算车辆冷起动阶段的CO₂排放。结果表明：车辆冷起动阶段，采用国六标准推荐的干湿基修正法计算的CO₂排放结果偏差较大；充分热机后，2种方法的计算结果趋于一致；采用国六推荐方法修正时，相比直接湿基测量结果，冷起动热机阶段的排放中CO₂体积分数偏低约14%。对于排气中水的体积分数较大的燃用CNG、甲醇、汽油等燃料的车辆的冷起动阶段CO₂排放计算，采用排气中水的体积分数计算CO₂湿基修正因子，结果更准确。

关键词：CNG；重型车；冷起动；干湿基修正

Effect of exhaust water content of a CNG heavy-duty vehicle onCO₂ measurement

ZHONG Xianglin, LI Tong, HUANG Pengcheng, MENG Qingliang

CATARC Automotive Test Center (Tianjin) Co., Ltd., Tianjin 300300, China

Abstract: To investigate the influence of different dry-wet correction methods on the measurement results of CO₂ emissions during the cold start phase of a compressed natural gas (CNG) heavy-duty vehicle, cold start tests are conducted on a CHINA 6 CNG vehicle under different test cycles using a chassis dynamometer. The CO₂ emissions during the cold start phase of the vehicle are calculated using the dry-wet correction method recommended by CHINA 6 regulations and the dry-based correction method based on the volume fraction of H₂O in the exhaust gas. The results indicate that during the cold start phase of vehicles, the CO₂ emissions calculated using the dry-wet correction method recommended by CHINA 6 have a significant deviation. After sufficient heating, the calculation results of the two methods tend to be consistent. When using the recommended method of China 6 for correction, compared to direct wet-based measurement results, the CO₂ emissions during the cold start are about 14% lower. For the calculation of CO₂ emissions during the cold start phase of CNG, methanol, gasoline and other vehicles with high exhaust water content, using the volume fraction of H₂O in the exhaust to calculate the CO₂ dry-wet correction factor yields more accurate results.

Keywords: CNG; heavy duty vehicle; cold start; dry-wet correction