Optical characterization of nano-sized organic carbon particles emitted from a small gasoline engine

The nano-sized organic carbon （NOC） particles emitted from a small gasoline engine were characterized using various ex situ optical techniques to assess their hazardous impact. The exhaust gas was sampled iso-kinetically by a quartz probe and passed through de-ionized water to gather the hydrophilic car- bonaceous particulates as hydrosol. The hydrodynamic diameter of the particles ranged between 1.7 and 3.6 nm at no load, with a mean diameter of 2.4 nm. The particle size in the engine exhaust was found to increase at higher loads, which is attributed to coagulation of the particles. The chemical structure of the particles was analyzed using UV-vis and infra-red spectroscopy. Both the band gap energy and oscillator strength data evaluated from the UV-vis absorbance showed that the NOC particles contained polyaromatic hydrocarbon structures with three to five aromatic rings. Infra-red spectroscopy analysis further confirmed the presence of aliphatic and carbonyl functionalities in the aromatic structures of the particles. The fine size of the particles, their high number concentration for the type of the engine under study and their structural features, make the particles extremely hazardous for environment and health.

汽油机尾气排放的影响因素数值分析

汽车的污染问题是当今环保领域绕不开的一大难题,其中废气排放的污染尤为受人关注。汽车尾气排放的处理和控制已逐渐成为汽车产业发展的重要目标之一。因此,通过建立汽油机燃烧模型进行了汽车尾气排放生成量的研究分析,该模型可对汽油机的燃烧工作过程进行数值模拟,重点在模拟变化的因素如点火提前角、压缩比和空燃比等对尾气中有害成分生成量的影响规律。具体结果为:随点火提前角或压缩比的增加,NO在燃烧过程中的生成量随之明显增加,而CO的生成量有所降低,但波动幅度较小;在理论空燃比附近,NO排放量达到峰值,CO的排放量接近最少。

甲醇汽油混合燃料对国Ⅲ汽油机性能与碳排放的影响

为了全面客观地评估汽油机燃用掺甲醇汽油时的性能和碳排放的情况,在一台进气道多点电喷汽油机SQR477F上进行了汽油、M15和M50燃料的负荷特性、外特性、经济性以及排放特性试验。研究结果表明:甲醇作为低碳燃料,在发动机参数未做任何调整的情况下,与燃用纯汽油相比,发动机的动力性随着掺醇比例的增加略有下降,基本不影响发动机的动力性;质量燃油消耗率增加,但等热值比油耗降低,具有较好的燃油经济性且CO2排放量较低;发动机燃用掺醇汽油后,排气中的H2O含量大幅度增加;冷态时,排气中H2O含量是燃用纯汽油时的4倍以上,热态时H2O含量与燃用纯汽油时的差距缩小。