甲醇替代柴油 破解柴油紧张之局

本文从甲醇的资源、可获得性、运输性和在柴油机上采用甲醇/柴油组合燃烧后的燃料费用及其对有害物质与温室气体排放影响等多个角度,全面阐述用甲醇替代柴油的可行性,并指出用甲醇替代柴油不仅可以缓解柴油供应紧张,而且有利于调节不合理柴汽比,同时为国家实施立足于自身资源、多元化发展的能源战略提供更合理的途径。     

正丁醇作为生物燃料在生产和应用方面的进展

作为车用替代燃料,丁醇的热值比乙醇高30%左右,挥发性只有乙醇的1/6左右,吸湿性远小于甲醇、乙醇和丙醇,具有适度的水溶性,腐蚀性低,安全性更高。但丁醇直接应用到发动机上也存在一些问题,如其热值比传统汽油或柴油低,使得燃料消耗量增加;燃烧效率低于甲醇、乙醇;当应用于点燃式发动机时,丁醇较高的黏度将产生潜在的沉积或腐蚀等问题。目前许多研究者将正丁醇作为替代生物燃料进行研究,现有的研究主要是将丁醇与汽油或柴油混合应用在发动机上,或是应用在一些基本的燃烧反应器中。综合各方面的研究成果,正丁醇在混合燃料中体积分数小于20%时,无需调整发动机就可获得与汽油燃料相同的发动机功率;当达到30%时,发动机最大功率开始下降;随着正丁醇体积的增加,燃料消耗量增加。CO、THC、NOx排放的减少或增加取决于具体的发动机、操作条件、丁醇-汽油的混合比等。混合燃料与纯汽油相比,未燃烧醇的排放增加,而且丁醇的比例越高,未燃烧醇的排放越高。     

车用甲醇汽油的生命周期能源消耗与温室气体排放分析

结合生命周期评价原理,对煤制甲醇与原油制汽油混合而成的甲醇汽油路线的能源消耗与温室气体排放进行生命周期分析。发现煤气化方法对甲醇路线影响较大,燃料的制造环节所消耗的能源与产生的温室气体占全生命周期相应指标的比例均超过50%。在所考虑的四种煤气化方法中,谢尔法的一次能源消耗与温室气体排放最低。若考虑车辆技术的进步,甲醇汽油路线的一次能源消耗可比传统汽油路线降低9%,温室气体排放量仅增加3.5%。此外,分析结果还表明利用煤制甲醇来代替部分传统汽油,每投入1.8t原煤便可以节省1.0t原油。由于我国的能源生产以煤为主,故以甲醇代替汽油的策略既能有效缓解我国对原油进口的依赖,又不会对能源生产造成明显压力。     

福建省能源活动温室气体排放测算及其碳强度趋势

根据《省级温室气体清单编制指南(试行)》,福建省能源活动温室气体包括化石燃料、生物质燃料燃烧活动产生的CO2、CH4和N2O排放及煤矿和矿后活动、石油和天然气系统产生的CH4逃逸排放。界定福建省能源活动过程温室气体的排放源及温室气体种类;给出各排放源相关的温室气体排放量估算方法,确定活动水平数据及排放因子,并估算各排放源温室气体的排放量;汇总化石燃烧排放的CO2量,化石燃料燃烧、生物质燃料燃烧、煤炭开采和矿后活动逃逸、石油和天然气系统逃逸排放的CH4量,化石燃料燃烧和生物质燃料燃烧排放的N2O量;生成福建省能源活动温室气体清单汇总,并根据福建省地区生产总值GDP得出碳强度趋势。     

HCCI甲醇发动机的燃烧与排放特性

在Ricardo Hydra单缸四冲程发动机上利用内部废气再循环策略实现了甲醇燃料的HCCI燃烧.通过调整HCCI发动机的过量空气系数和转速,研究了HCCI甲醇发动机的燃烧和排放特性.结果表明,甲醇燃料的HCCI燃烧不同于普通汽油,其着火更早、燃烧更快,但在低转速时,平均指示压力相对较低.甲醇燃料可以在更稀的混合气条件下实现HCCI燃烧.在相同的转速和过量空气系数下,甲醇燃料的NOx和HC排放低于汽油.     

甲醇/乙醇/汽油HCCI燃烧和排放特性对比

在Ricardo单缸四冲程汽油机上采用内部废气再循环策略,实现了汽油、乙醇和甲醇的HCCI燃烧,并对比了这3种燃料HCCI的燃烧和排放特性。结果表明:在HCCI燃烧模式下,醇类燃料与汽油相比有更多的燃料参与了低温反应,有利于化学动力学反应的进行,因此醇类燃料提前着火时刻,缩短燃烧持续期,降低发动机的燃烧温度;在相同的发动机转速和空燃比条件下,醇类燃料可以极大地降低发动机的NOx排放,特别是甲醇的NOx排放最低可达2×10-6;并且醇类燃料更有利于稀燃,适用于中高速的发动机工况。     

柴油机燃用甲醇的应用研究和进展

简单介绍了甲醇燃料在柴油机中燃烧所存在的问题及应用。并介绍了西安交通大学在此方面的一些研究进展,认为在一定的技术措施下,甲醇可以应用于柴油机,以替代或部分替代柴油;并可减少发动机的碳烟颗粒和NOx的排放,但不同的技术方法对CO和HC排放的影响不同。     

甲醇/生物柴油/F-T柴油煤基多元燃料对柴油机燃烧及排放性能的影响

为寻找柴油清洁替代燃料,选用F-T柴油、甲醇两种煤基燃料,并结合生物柴油,配制成甲醇(methanol)/生物柴油(biodiesel)/F-T柴油(F-T)煤基多元燃料(简称MBFT燃料)。在未经改动的增压直喷式发动机上,通过试验分析了MBFT燃料的性能,研究了甲醇比例对MBFT燃料性能的影响规律。研究结果表明:MBFT燃料的燃烧特性介于0#柴油与F-T柴油之间,甲醇比例对MBFT燃料的燃烧特性产生直接的影响,随着甲醇比例增大,预混燃烧量与扩散燃烧量比值增大;在动力经济性方面,相比于0#柴油,MBFT燃料的动力性降低了7.5%~9.5%,但燃油经济性提升了6.6%~11.3%,随着甲醇比例增大,MBFT燃料在动力性下降的同时,燃油经济性也变差,因此甲醇的体积比例不宜超过10%;关于排放性能,MBFT燃料可以在F-T柴油的基础上,进一步优化排放中氮氧化物(NOx)与碳烟之间的折中关系,不同甲醇比例的MBFT燃料对排放的改善效果基本一致。     

掺醇燃料发动机非常规有害排放物甲醛的分析

随着石油资源的日益减少,醇类燃料作为汽车的代用燃料,在我国有着广泛的应用前景.发动机采用醇类清洁燃料代替传统汽油、柴油虽然降低了传统发动机常规排放污染物的含量,但它们的非常规排放污染物(甲醛、乙醛、甲醇、乙醇、1,3-丁二烯、苯等)的排放浓度往往高于传统发动机的排放水平.甲醛是甲醇不完全燃烧的产物,对人体健康和大气环境...     

甲醇汽油添加剂与调配技术

介绍了中国甲醇车用燃料研发的历程及巨澜牌甲醇汽油的使用范围。指出,不需要采用甲醇专用发动机,也不必改装汽车就能使用大比例甲醇汽油,指出,甲醇汽油煤基醇醚燃料在车用能源领域实现大比例替代石油的新途径。     

Transportation: meeting the dual challenges of achieving energy security and reducing greenhouse gas emissions

As the population and economy continue to grow globally, demand for energy will continue to grow. The transportation sector relies solely on petroleum for its energy supply. The United States and China are the top two oil-importing countries. A major issue both countries face and are addressing is energy insecurity as a result of the demand for liquid fuels. Improvements in the energy efficiency of vehicles and the substitution of petroleum fuels with alternative fuels can help contain growth in the demand for transportation oil. Although most alternative transportation fuels — when applied to advanced vehicle technologies — can substantially reduce greenhouse emissions, coal-based liquid fuels may increase greenhouse gas emissions by twice as much as gasoline. Such technologies as carbon capture and storage may need to be employed to manage the greenhouse gas emissions of coal-based fuels. At present, there is no ideal transportation fuel option to solve problems related to transportation energy and greenhouse gas emissions. To solve these problems, research and development efforts are needed for a variety of transportation fuel options and advanced vehicle technologies.     

Life cycle analysis of energy use and greenhouse gas emissions for road transportation fuels in China

Life cycle analysis is considered to be a valuable tool for decision making towards sustainability. Life cycle energy and environmental impact analysis for conventional transportation fuels and alternatives such as biofuels has become an active domain of research in recent years. The present study attempts to identify the most reliable results to date and possible ranges of life cycle fossil fuel use, petroleum use and greenhouse gas emissions for various road transportation fuels in China through a comprehensive review of recently published life cycle studies and review articles. Fuels reviewed include conventional gasoline, conventional diesel, liquefied petroleum gas, compressed natural gas, wheat-derived ethanol, corn-derived ethanol, cassava-derived ethanol, sugarcane-derived ethanol, rapeseed-derived biodiesel and soybean-derived biodiesel. Recommendations for future work are also discussed.     

Evaluation of hydrogen-containing NaBH4 and oxygen-containing alcohols (CH3OH,C2H5OH) as fuel additives in a gasoline engine

The aim of this study is to obtain alternative fuels with hydrogen-containing (NaBH₄) and oxygen-containing (ethanol, methanol) fuel additives and to test these fuels in a gasoline engine. For this purpose, each of the NaBH₄ added ethanol and methanol solutions was added to pure gasoline at a volume of 10% and mixed fuels named SE10 and SM10 were obtained, respectively. The obtained SE10 and SM10 mixed fuels were tested in a spark ignition engine and the performance and emission effects of the fuels were compared with the pure gasoline fueled engine test data. When the test results of the mixture fuel engine were compared with the test results of the engine running with pure gasoline, the torque of the SE10 fuel engine decreased compared to the pure gasoline engine, while the torque of the SM10 blended engine increased. In addition, while the exhaust gas temperatures of both blended fuels decreased, their specific fuel consumption and thermal efficiency increased. On the other hand, adding NaBH₄ doped ethanol and methanol solutions to pure gasoline resulted in better combustion, reductions in CO emissions of SE10 and SM10 blended fuels by 31.04% and 53.7%, but CO₂ emissions increased by 11.20% and 19.51% respectively. In addition, NO_x emissions of SE10 and SM10 blended fuels decreased by 15.17% and 8.73%, respectively.     

The effect of clove oil and diesel fuel blends on the engine performance and exhaust emissions of a compression-ignition engine

Diesel engines provide the major power source for transportation in the world and contribute to the prosperity of the worldwide economy. However, recent concerns over the environment, increasing fuel prices and the scarcity of fuel supplies have promoted considerable interest in searching for alternatives to petroleum based fuels. Based on this background, the main purpose of this investigation is to evaluate clove stem oil (CSO) as an alternative fuel for diesel engines. To this end, an experimental investigation was performed on a four-stroke, four-cylinder water-cooled direct injection diesel engine to study the performance and emissions of an engine operated using the CSO–diesel blended fuels. The effects of the CSO–diesel blended fuels on the engine brake thermal efficiency, brake specific fuel consumption (BSFC), specific energy consumption (SEC), exhaust gas temperatures and exhaust emissions were investigated. The experimental results reveal that the engine brake thermal efficiency and BSFC of the CSO–diesel blended fuels were higher than the pure diesel fuel while at the same time they exhibited a lower SEC than the latter over the entire engine load range. The variations in exhaust gas temperatures between the tested fuels were significant only at medium speed operating conditions. Furthermore, the HC emissions were lower for the CSO–diesel blended fuels than the pure diesel fuel whereas the NO_x emissions were increased remarkably when the engine was fuelled with the 50% CSO–diesel blended fuel.     

Performance and emission study in manifold hydrogen injection with diesel as an ignition source for different start of injection

Over the past two decades there has been a considerable effort to develop and introduce alternative transportation fuels to replace conventional fuels, gasoline and diesel. Environmental issues are the principal driving forces behind this effort. To date the bulk of research has focused on the carbon-based fuels such as reformulated gasoline, methanol and natural gas. One alternative fuel to carbon-based fuels is hydrogen which is considered to be low polluting fuel. In the present experimental investigation hydrogen was injected into the intake manifold by using an injector. Using an electronic control unit (ECU) the injection timing and the duration were controlled. From the results it is observed that the optimum injection timing is at gas exchange top dead center (GTDC). The efficiency improved by about 15% with an increase in NO_X emission by 3% compared to diesel. The smoke emission decreased by almost 100%. A net reduction in carbon emissions was also noticed due to the use of hydrogen. By adopting manifold injection technique the hydrogen–diesel dual fuel engine operates smoothly with a significant improvement in performance and reduction in emissions.     

A review of hydrogen usage in internal combustion engines (gasoline-Lpg-diesel) from combustion performance aspect

Demand for fossil fuels is increasing day by day with the increase in industrialization and energy demand in the world. For this reason, many countries are looking for alternative energy sources against this increasing energy demand. Hydrogen is an alternative fuel with high efficiency and superior properties. The development of hydrogen-powered vehicles in the transport sector is expected to reduce fuel consumption and air pollution from exhaust emissions. In this study, the use of hydrogen as a fuel in vehicles and the current experimental studies in the literature are examined and the results of using hydrogen as an additional fuel are investigated. The effects of hydrogen usage on engine performance and exhaust emissions as an additional fuel to internal combustion gasoline, diesel and LPG engines are explained. Depending on the amount of hydrogen added to the fuel system, the engine power and torque are increased at most on petrol engines, while they are decreased on LPG and diesel engines. In terms of chemical products, the emissions of harmful exhaust gases in gasoline and LPG engines are reduced, while some diesel engines increase nitrogen oxide levels. In addition, it is understood that there will be a positive effect on the environment, due to hydrogen usage in all engine types.     

Effects of hydrogenation of fossil fuels with hydrogen and hydroxy gas on performance and emissions of internal combustion engines

Energy security is an important consideration for development of future transport fuels. Among the all gaseous fuels hydrogen or hydroxy (HHO) gas is considered to be one of the clean alternative fuels. Hydrogen is very flammable gas and storing and transporting of hydrogen gas safely is very difficult. Today, vehicles using pure hydrogen as fuel require stations with compressed or liquefied hydrogen stocks at high pressures from hydrogen production centres established with large investments.Different electrode design and different electrolytes have been tested to find the best electrode design and electrolyte for higher amount of HHO production using same electric energy. HHO is used as an additional fuel without storage tanks in the four strokes, 4-cylinder compression ignition engine and two-stroke, one-cylinder spark ignition engine without any structural changes. Later, previously developed commercially available dry cell HHO reactor used as a fuel additive to neat diesel fuel and biodiesel fuel mixtures. HHO gas is used to hydrogenate the compressed natural gas (CNG) and different amounts of HHO-CNG fuel mixtures are used in a pilot injection CI engine. Pure diesel fuel and diesel fuel + biodiesel mixtures with different volumetric flow rates are also used as pilot injection fuel in the test engine. The effects of HHO enrichment on engine performance and emissions in compression-ignition and spark-ignition engines have been examined in detail. It is found from the experiments that plate type reactor with NaOH produced more HHO gas with the same amount of catalyst and electric energy. All experimental results from Gasoline and Diesel Engines show that performance and exhaust emission values have improved with hydroxy gas addition to the fossil fuels except NO_x exhaust emissions. The maximum average improvements in terms of performance and emissions of the gasoline and the diesel engine are both graphically and numerically expressed in results and discussions. The maximum average improvements obtained for brake power, brake torque and BSFC values of the gasoline engine were 27%, 32.4% and 16.3%, respectively. Furthermore, maximum improvements in performance data obtained with the use of HHO enriched biodiesel fuel mixture in diesel engine were 8.31% for brake power, 7.1% for brake torque and 10% for BSFC.     

Importance of P-Series Fuels for Flexible-Fuel Vehicles (FFVs) and Alternative Fuels

As engine fuels, the most popular alternative fuels are bioetanol, biodiesel, and hydrogen. Recently, in addition to these, there are intensive researches on methyl-, and ethylalcohols, natural gas, liquefied petroleum gas, P-series, electricity, and solar fuels. Alternative fuels for diesel engines are becoming increasingly important due to diminishing petroleum reserves and the environmental consequences of exhaust gases from petroleum-fueled engines. One of the advantages of P-series is that they are very easy to use. There is no need for any special fuel management because gasoline and P-series can be freely intermixed in any proportion with fuel that is already in the vehicle's fuel tank. So, even if P-series is not available at a particular location, simply fill up with gasoline. These fuels are inexpensive fuels generated by municipal and agricultural wastes. The National Renewal Energy Laboratory (NREL) showed that P-series would be 96% derived from domestic resources and reduce petroleum use by 80% as compared to gasoline. Use of P-series fuels also greatly reduces toxic emissions. P-fuels are economically competitive with gasoline. As of May 2003, the projected retail price for P-series, including all taxes, is $1.49 per gallon, about the same as mid-grade gasoline in a $/mile calculation. There are 3 million cars on the road today that could run on P-series fuels.     

Comparative performance and emission studies for vaporized diesel fuel and gasoline as supplements in swirl-chamber diesel engines

An experimental study has been conducted to evaluate and compare the use of fumigated diesel fuel or gasoline as supplementary fuels for a naturally-aspirated, four-stroke diesel engine with a swirl-combustion chamber. The supplementary diesel fuel or gasoline is introduced together with the aspirated air (fumigation) in various proportions with respect to the main diesel fuel, which is injected in the usual manner. The influence of fuel/feed ratios (supplementary or main feed), for a large range of loads, has been examined on fuel consumption, pressure diagrams, exhaust smokiness and exhaustgas emissions (nitrogen oxides, hydrocarbons and carbon monoxide). Knocking limits have been determined. The differences in the measured performance and exhaust-emission parameters from baseline engine operation, when using either supplementary diesel fuel or gasoline fumigated in the intake air, are determined and compared. Our study shows promise for this approach and indicates that above ˜60% of maximum load, there is high smoke reduction with only a slight change in specific fuel consumption, when using either one of the supplementary fumigated fuels. Examination of gaseous pollutant levels shows involved relations with respect to load and fuel proportions. Theoretical aspects of the supplementary fuel-mode (fumigation) of combustion are used to explain the observed engine behaviour.