生物柴油的燃烧及排放特性研究

在一台四冲程直喷式柴油机上对比研究不同喷油策略对鱼油乙酯生物柴油混合燃料燃烧和排放特性的影响。发动机转速固定在1 500 r/min,喷油正时分别在21、24、27°CA BTDC的不同负荷下,使用的6种燃料为柴油及B20、B40、B60、B80、B100的鱼油乙酯生物柴油混合燃料。结果表明:在不同喷油正时、不同负荷下,生物柴油与柴油相比,发动机的氮氧化物和碳烟排放最大降幅为17.9%和55.38%;鱼油制取的生物柴油导致气缸压力峰值、放热率和最大压力升高率均低于柴油,碳氢化合物、一氧化碳排放降低。     

新疆棉籽生物柴油实用性能研究

以新疆棉籽油为原料用酯交换法制取生物柴油,按照体积比将棉籽生物柴油与0#石化柴油调和成B20棉籽生物柴油。调和的B20棉籽生物柴油理化指标得到优化,达到GB/T 19147-2003标准;柴油发动机试验分析表明,燃用B20棉籽生物柴油,发动机运行平稳,工作正常,动力下降2%～3%,油耗增加2%～5%,CO、THC、PM排放量减少,符合实际应用需求,是优质清洁的替代燃料。     

餐厨废弃油脂生物柴油对船舶柴油机性能、排放特性以及燃烧特性的影响北大核心CSCD

为探讨生物柴油应用于船舶柴油机的可行性,将餐厨废弃油脂生物柴油与柴油混合,在船舶柴油机上进行试验,测试其对船舶柴油机性能、排放特性和燃烧特性的影响。结果表明:生物柴油混合物的高黏度以及低热值会降低有效热效率,并导致燃油消耗率略有升高;由于生物柴油的高含氧量促进完全燃烧,相比于柴油,燃烧生物柴油混合物后,一氧化碳排放量最高下降17%,二氧化碳排放量最高下降5.1%,二氧化硫排放量最高下降41%,碳烟排放量最高下降36%;生物柴油过快的燃烧速率提高了气缸内的燃烧温度,以及高含氧量促进了氮氧化物的排放;生物柴油混合物燃烧时的缸内压力与柴油非常接近。餐厨废弃油脂生物柴油对船舶柴油机的性能、燃烧特性和排放特性均具有较好的表现,可以作为柴油的替代燃料用于船舶柴油机。     

燃用掺混小比例生物柴油对船舶柴油机性能的影响

为探究生物柴油在船舶柴油机上的适用性,基于六缸中速柴油机试验台架,在不同负荷推进特性工况下,对燃用0#柴油、B10生物柴油柴油机的动力性能、经济性能、振动特性和缸内燃烧特性进行对比分析。结果发现：与0#柴油相比,燃用B10生物柴油柴油机的输出功率和耗油量基本不变,耗油率有所升高,但随着负荷的升高有所改善,燃用B10生物柴油使得在25%负荷工况下的柴油机缸盖振动烈度下降,50%、75%、90%、100%负荷工况下的柴油机缸盖振动烈度稍有上升,不同负荷工况下的机体振动烈度均下降;从振动功率谱密度可以看出,两种燃油在不同负荷下低频段的振动响应相似,但高频段处振动响应存在差异;对两种燃油的缸内压力和压力升高率曲线的分析可知,燃用B10生物柴油可以使缸内压力峰值和最大压力升高率升高,燃烧反应速度加快。综上,B10生物柴油在不同负荷工况下动力性能、经济性能、振动特性和缸内燃烧特性方面均表现良好,在船舶柴油机上具有较好的应用前景。     

生物柴油掺氨对均质压燃发动机燃烧及排放性能的影响

为提升燃料的综合燃烧品质和性能,进一步降低有害物质排放和缓解温室效应,以燃烧动力学和化学反应机制作为理论基础,采用Chemkin软件将生物柴油替代物和氨气充分融合,模拟并计算氨气掺混比例分别为0、5%、10%、15%、20%的5组燃料在均质压燃发动机模式下燃烧和排放指标的数值,对比分析得到不同掺混比例对发动机燃烧和排放的影响和变化规律。结果表明：随着氨气掺混比例增加,燃料的点火滞燃期有所缩短,缸内燃烧最高温度升高,排温降低;排放方面,NO_x的排放升高,CO₂、CO和总碳氢化合物(THC)的排放均明显降低;生物柴油掺混氨气的最佳比例为20%,此时发动机功率下降12百分点,NO的单位功率排放升高了0.003 kW^-1,而CO₂和THC的单位功率排放分别降低了0.01 kW^-1和0.001 3 kW^-1。综上,生物柴油掺混氨气后改善了燃烧性能,降低了排放量,具有良好的应用前景。     

橡胶籽生物柴油在柴油发动机上的应用研究

以0#轻柴油、-10#军用柴油为对比燃油,对调和生物柴油B5、B20(橡胶籽生物柴油含量分别为5%、20%,常规柴油含量分别为95%、80%)在WD61550柴油发动机上进行适应性研究,考察了柴油机燃用不同燃油时的外特性、负荷特性,测定了功率、扭矩、油耗等性能指标。研究结果表明,发动机使用调和生物柴油的外特性、负荷特性参数变化趋势与所用对比燃油一致;使用调和生物柴油B5时,发动机动力性、经济性与0#轻柴油几乎无区别,与-10#军用柴油相比略有下降;使用B20时,发动机动力性与0#轻柴油、-10#军用柴油相比稍有下降,油耗略有增加。总体来看,在不改变发动机结构情况下,调和橡胶籽生物柴油B5、B20可以替代0#轻柴油。     

降低燃用生物柴油NOx排放量的分析

在YL4102型柴油机上分别燃用生物柴油、石化柴油、生物柴油和石化柴油的混合物测定NOx的排放情况,并对降低NOx排放量的措施进行了研究。结果表明,适当推迟喷油提前角会降低NOx的排放,在满负荷范围时,当喷油提前角为10°CA左右时NOx排放降低30％左右。燃用乳化生物柴油可降低NOx的排放,随着乳化生物柴油中水的增加,NOx的排放迅速下降,当水的体积分数为30％时,NOx排放降低40％左右。     

DICI发动机燃用生物柴油振动特性研究

通过将发动机外在的振动信号经过变换与缸内的燃烧放热规律相结合,以对DICI发动机燃用生物柴油后引起的振动进行协同特性研究。具体方法为,将餐饮废油生物柴油以10%掺混作为测试燃料,在常用工况下对缸盖振动信号和缸内燃烧压力进行采集。通过将小波尺度进行重排计算、振动功率密度计算和缸内压力计算,得到振动时间谱图、功率密度谱图和燃烧放热率等。结果表明:燃用B10生物柴油后,发动机整体振动频率从约4 200 Hz降低至约2 900 Hz。这主要由于生物柴油高黏度和低热值等特性导致缸内燃烧有所弱化,因而导致发动机振动的降低。生物柴油在整个频段上振动分布表现更为均匀,将对人体舒适度的提高和发动机寿命的延长有所贡献。     

美国将大力生产乙醇和生物燃油

由美国可再生燃油协会、国家玉米种植商协会和国家生物柴油委员会共同资助的一项研究最近表明：大力生产可再生燃油对美国能源安全、农业领域和经济都将产生重大积极影响。如果2016年可再生燃油占美国所有燃油消费总量4%的话，据该项研究预测：约有29亿桶石油被替代，从而使进口石油占美国所需石油总量比例从70%降至65%，且减少美国贸易赤字634亿美元；乙醇使用量2002年为20亿桶，到2016年将增长至76亿桶，从而将消耗约27.5亿蒲式耳粮食。 纯度为85%乙醇（即E85燃油）燃烧时对环境的污染低于汽油。利用生物量生产燃油只需一个结构简单的蒸…     

生物柴油调和燃料理论热值比对分析

通过酯交换法在实验室制备了小桐子生物柴油、地沟油生物柴油和橡胶籽生物柴油,与0#柴油按照不同体积比配制出36种生物柴油调和燃料。计算生物柴油调和燃料的门捷列夫理论热值和质量分数理论热值,分别与测定热值进行线性拟合,得出最佳理论热值计算方法。结果表明:质量分数理论热值计算方法适用于小桐子生物柴油调和燃料;门捷列夫理论热值计算方法适用于地沟油生物柴油调和燃料;两种方法均适用于橡胶籽生物柴油调和燃料理论热值计算。     

Characteristics of SME biodiesel-fueled diesel particle emissions and the kinetics of oxidation

Biodiesel is one of the most promising alternative diesel fuels. As diesel emission regulations have become more stringent, the diesel particulate filter (DPF) has become an essential part of the aftertreatment system. Knowledge of kinetics of exhaust particle oxidation for alternative diesel fuels is useful in estimating the change in regeneration behavior of a DPF with such fuels. This study examines the characteristics of diesel particulate emissions as well as kinetics of particle oxidation using a 1996 John Deere T04045TF250 off-highway engine and 100% soy methyl ester (SME) biodiesel (B100) as fuel. Compared to standard D2 fuel, this B100 reduced particle size, number, and volume in the accumulation mode where most of the particle mass is found. At 75% load, number decreased by 38%, DGN decreased from 80 to 62 nm, and volume decreased by 82%. Part of this decrease is likely associated with the fact that the particles were more easily oxidized. Arrhenius parameters for the biodiesel fuel showed a 2-3times greater frequency factor and approximately 6 times higher oxidation rate compared to regular diesel fuel in the range of 700-825 degrees C. The faster oxidation kinetics should facilitate regeneration when used with a DPF.     

地沟油生物柴油在发动机上的应用现状和发展趋势

通过对地沟油生物柴油的制备工艺、燃料特性、动力性、经济性、燃烧排放特性、使用现状以及发展前景进行综合分析,认为利用地沟油制备生物柴油具有良好的可再生性、具有与石化柴油相当的动力性、具有优于石化柴油的排放性,是实现地沟油资源化利用的有效途径。但是地沟油生物柴油在实际车用中仍有几个关键问题需要解决:制备过程不完善,黏度过高,燃烧排放中NOX排放增加。解决上述问题有利于真正实现地沟油的经济效益、环境效益与社会效益。     

Brassica carinata as an alternative oil crop for the production of biodiesel in Italy: engine performance and regulated and unregulated exhaust emissions

A comparison of the performance of Brassica carinata oil-derived biodiesel with a commercial rapeseed oil-derived biodiesel and petroleum diesel fuel is discussed as regards engine performance and regulated and unregulated exhaust emissions. B. carinata is an oil crop that can be cultivated in coastal areas of central-southern Italy, where it is more difficult to achieve the productivity potentials of Brassica napus (by far the most common rapeseed cultivated in continental Europe). Experimental tests were carried out on a turbocharged direct injection passenger car diesel engine fueled with 100% biodiesel. The unregulated exhaust emissions were characterized by determining the SOOT and soluble organic fraction content in the particulate matter, together with analysis of the content and speciation of polycyclic aromatic hydrocarbons, some of which are potentially carcinogenic, and of carbonyl compounds (aldehydes, ketones) that act as ozone precursors. B. carinata and commercial biodiesel behaved similarly as far as engine performance and regulated and unregulated emissions were concerned. When compared with petroleum diesel fuel, the engine test bench analysis did not show any appreciable variation of output engine torque values, while there was a significant difference in specific fuel consumption data at the lowest loads for the biofuels and petroleum diesel fuel. The biofuels were observed to produce higher levels of NOx concentrations and lower levels of PM with respect to the diesel fuel. The engine heat release analysis conducted shows that there is a potential for increased thermal NOx generation when firing biodiesel with no prior modification to the injection timing. It seems that, for both the biofuels, this behavior is caused by an advanced combustion evolution, which is particularly apparent at the higher loads. When compared with petroleum diesel fuel, biodiesel emissions contain less SOOT, and a greater fraction of the particulate was soluble. The analysis and speciation of the soluble organic fraction of biodiesel particulate suggest that the carcinogenic potential of the biodiesel emissions is probably lower than that of petroleum diesel. Its better adaptivity and productivity in clay and sandy-type soils and in semiarid temperate climate and the fact that the performance of its derived biodiesel is quite similar to commercial biodiesel make B. carinata a promising oil crop that could offer the possibility of exploiting the Mediterranean marginal areas for energetic purposes.     

Combustion performance evaluation of air staging of palm oil blends

The problems of global warming and the unstable price of petroleum oils have led to a race to develop environmentally friendly biofuels, such as palm oil or ethanol derived from corn and sugar cane. Biofuels are a potential replacement for fossil fuel, since they are renewable and environmentally friendly. This paper evaluates the combustion performance and emission characteristics of Refined, Bleached, and Deodorized Palm Oil (RBDPO)/diesel blends B5, B10, B15, B20, and B25 by volume, using an industrial oil burner with and without secondary air. Wall temperature profiles along the combustion chamber axis were measured using a series of thermocouples fitted axially on the combustion chamber wall, and emissions released were measured using a gas analyzer. The results show that RBDPO blend B25 produced the maximum emission reduction of 56.9% of CO, 74.7% of NOx, 68.5% of SO(2), and 77.5% of UHC compared to petroleum diesel, while air staging (secondary air) in most cases reduces the emissions further. However, increasing concentrations of RBDPO in the blends also reduced the energy released from the combustion. The maximum wall temperature reduction was 62.7% for B25 at the exit of the combustion chamber.     

Diesel particle filter and fuel effects on heavy-duty diesel engine emissions

The impacts of biodiesel and a continuously regenerated (catalyzed) diesel particle filter (DPF) on the emissions of volatile unburned hydrocarbons, carbonyls, and particle associated polycyclic aromatic hydrocarbons (PAH) and nitro-PAH, were investigated. Experiments were conducted on a 5.9 L Cummins ISB, heavy-duty diesel engine using certification ultra-low-sulfur diesel (ULSD, S ≤ 15 ppm), soy biodiesel (B100), and a 20% blend thereof (B20). Against the ULSD baseline, B20 and B100 reduced engine-out emissions of measured unburned volatile hydrocarbons and PM associated PAH and nitro-PAH by significant percentages (40% or more for B20 and higher percentage for B100). However, emissions of benzene were unaffected by the presence of biodiesel and emissions of naphthalene actually increased for B100. This suggests that the unsaturated FAME in soy-biodiesel can react to form aromatic rings in the diesel combustion environment. Methyl acrylate and methyl 3-butanoate were observed as significant species in the exhaust for B20 and B100 and may serve as markers of the presence of biodiesel in the fuel. The DPF was highly effective at converting gaseous hydrocarbons and PM associated PAH and total nitro-PAH. However, conversion of 1-nitropyrene by the DPF was less than 50% for all fuels. Blending of biodiesel caused a slight reduction in engine-out emissions of acrolein, but otherwise had little effect on carbonyl emissions. The DPF was highly effective for conversion of carbonyls, with the exception of formaldehyde. Formaldehyde emissions were increased by the DPF for ULSD and B20.     

Effects of ethanol (E85) versus gasoline vehicles on cancer and mortality in the United States

Ethanol use in vehicle fuel is increasing worldwide, but the potential cancer risk and ozone-related health consequences of a large-scale conversion from gasoline to ethanol have not been examined. Here, a nested global-through-urban air pollution/weather forecast model is combined with high-resolution future emission inventories, population data, and health effects data to examine the effect of converting from gasoline to E85 on cancer, mortality, and hospitalization in the United States as a whole and Los Angeles in particular. Under the base-case emission scenario derived, which accounted for projected improvements in gasoline and E85 vehicle emission controls, it was found that E85 (85% ethanol fuel, 15% gasoline) may increase ozone-related mortality, hospitalization, and asthma by about 9% in Los Angeles and 4% in the United States as a whole relative to 100% gasoline. Ozone increases in Los Angeles and the northeast were partially offset by decreases in the southeast. E85 also increased peroxyacetyl nitrate (PAN) in the U.S. but was estimated to cause little change in cancer risk. Due to its ozone effects, future E85 may be a greater overall public health risk than gasoline. However, because of the uncertainty in future emission regulations, it can be concluded with confidence only that E85 is unlikely to improve air quality over future gasoline vehicles. Unburned ethanol emissions from E85 may result in a global-scale source of acetaldehyde larger than that of direct emissions.