基于VDI2198循环的内燃叉车实际作业排放特性

Analysis of the real working emission features of the internal combustion forklift based on the study of VDI2198 cycle

为了分析实际作业的叉车排放特征,基于VDI2198循环,采用车载排放测试系统（PEMS）对某基本型配备非道路国Ⅲ柴油发动机叉车进行前进、后退、货物举升、货物下降4种作业工况下的实车道路排放测试。结果表明,各排放物的排放速率在前进、货物举升和货物下降工况下处于较高水平,在后退工况下处于较低水平。CO_2、NO_x基于时间的排放因子在前进工况下最高,其原因是在前进工况下发动机处于合理转速工作区,进气充足,燃料燃烧较为充分,达到了高温富氧条件;CO、PN基于时间的排放因子在货物举升工况下最高,其原因是举升工况下发动机转速过高,进气不足、喷油量增加导致大量燃料不完全燃烧。后退工况下较低的CO_2基于时间排放因子,使得各污染物基于CO_2当量排放因子在后退工况下较高。与美国NONROAD模型中同类叉车排放水平对比,试验叉车的CO排放水平远低于Tier4A之前的排放水平,远高于Tier4排放水平;NO_x的排放水平低于Tier4A之前的排放水平,稍高于Tier4的排放水平。适度超载对排放影响较小,冷起动对排放影响较大。坡度增加对排放影响显著,坡度从0（平地）增至10%,CO、NO_x、PN、CO_2基于里程的排放因子分别增加了54%、19%、100%、27%;坡度从10%增加至15%,CO、NO_x、PN、CO_2基于里程的排放因子分别增加了41%、50%、51%、56%。

The paper is intended to make a test and analysis of the real working emission features of China-made forklift vehicles, a basic type forklift with China HI diesel engine by using a porta- ble emission measurement system （PEMS）. The test has been done based on the VDI2198 cycle, whose working modes can be categorized into the forward-driving mode, backward-driving mode, upward-lifting mode and the downward-dropping mode. The testing results we have gained show that the emission rates of CO, NOx, PN, CO2 tend to be greater in the driving forward mode and lifting mode, in addition to the descending mode, whereas the backward-driving mode would be much lower. Due to the reasonable moving speed, it would be possible for the engine to get sufficient oxygen for its full fuel combustion and high-temperature operation satisfaction of their engine condition, and, therefore, their hourly emission factors of COz, NOx in the driving forward mode prove to be higher than the rest working modes. Besides, thanks to the ultra high speed working condition, its fuel combustion of oxygen proves insufficient with its engine＇ s incomplete fuel combustion, its hourly emission factors of CO and PN in the lifting mode can be much higher than the other working modes. Furthermore, in contrast, the CO2 based emission factor in the backward driving proves to be higher due to the low level of hourly emission factor of CO2. Thus, comparing the measurement results with the emission factors from the NONROAD model, the hourly emission factor of CO we have gained in this study proves much lower than that before Tier4A, whereas that of CO can be 4. 543 times higher than that of Tier4. And, in comparison, NOx hourly emission factor in the case of the paper turns out much lower than the level before Tier4A, but 1. 073 times higher than that of Tier4. Though slight overload has little effect on the emission, the factor of cold start may have a greater effect on the emission. What is more, with the increase of the sloping grade, the emission may tend to grow significantly. Thus, it can be seen that, when the sloping grade increases from 0 to 10%, the mileage-based emission factors of CO, NO,, PN and CO2 may increase at about 54%, 19%, 100% and 27%, respectively, whereas when the driving grade increases from 10% to 15% , the mileage-based emission grates of CO, NOx, PN and CO2 can be expected to increase by 41% , 50% , 51% and 56% , correspondingly.