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。     

含水乙醇在内燃机的应用研究

在摩托车发动机和车用柴油机上进行了含水乙醇的使用研究，当含水乙醇用于汽油机时，它是直接与汽油混合后使用而未对发动机进行任何改造；而当含水乙醇用于柴油机时则在柴油机的进气系统上安装含水乙醇的喷射系统，含水乙醇喷入进气歧管后蒸发并与进入的空气混合，然后在进气过程中进入气缸。试验结果显示，发动机的动力性都没有受到影响，燃料的能耗率都有所降低，柴油进气预混含水乙醇可大量降低其炭烟排放但导致HC和CO排放的增加；含水乙醇与汽油混合燃烧可降低其CO排放而可能导致NOx排放的增加。综合比较的结果，汽油机中应用含水乙醇比在柴油机中有更大的优势。     

The effects of ethanol–unleaded gasoline blends on engine performance and exhaust emissions in a spark-ignition engine

Alcohols have been used as a fuel for engines since 19th century. Among the various alcohols, ethanol is known as the most suited renewable, bio-based and ecofriendly fuel for spark-ignition (SI) engines. The most attractive properties of ethanol as an SI engine fuel are that it can be produced from renewable energy sources such as sugar, cane, cassava, many types of waste biomass materials, corn and barley. In addition, ethanol has higher evaporation heat, octane number and flammability temperature therefore it has positive influence on engine performance and reduces exhaust emissions. In this study, the effects of unleaded gasoline (E0) and unleaded gasoline–ethanol blends (E50 and E85) on engine performance and pollutant emissions were investigated experimentally in a single cylinder four-stroke spark-ignition engine at two compression ratios (10:1 and 11:1). The engine speed was changed from 1500 to 5000 rpm at wide open throttle (WOT). The results of the engine test showed that ethanol addition to unleaded gasoline increase the engine torque, power and fuel consumption and reduce carbon monoxide (CO), nitrogen oxides (NO_x) and hydrocarbon (HC) emissions. It was also found that ethanol–gasoline blends allow increasing compression ratio (CR) without knock occurrence.     

Effect of different types of fuels tested in a gasoline engine on engine performance and emissions

In this study, three different fuels named G100 (pure gasoline), E20 (volume 20% ethanol and 80% gasoline blend) and ES20 (20% sodium borohydride added ethanol solution and 80% gasoline) were used to test in a gasoline engine. First of all, G100 fuel, E20 and ES20 blended fuels, respectively, were tested in a gasoline engine and the effects of fuels on engine performance and exhaust emissions were investigated experimentally. Experiments were carried out at full load and at five different engine speeds ranging from 1400 to 3000 rpm, and engine performance and exhaust emission values were determined for each test fuel. When the test results of the engine operated with E20 and ES20 blended fuels are compared with the test results of the engine operated with gasoline; engine torque of E20 blended fuel increased by 1.87% compared to pure gasoline, while engine torque of ES20 blended fuel decreased by 1.64%. However, the engine power of E20 and ES20 blended fuels decreased by 2.02% and 5.10%, respectively, compared to the power of pure gasoline engine, while their specific fuel consumption increased by 5.02% and 6.57%, respectively, compared to pure gasoline fueled engine. On the other hand, CO and HC emissions of the engine operated with E20 and ES20 blended fuels decreased compared to the pure gasoline engine, while CO₂ and NO_x emissions increased.     

Experimental and theoretical investigation of using gasoline–ethanol blends in spark-ignition engines

The effects of ethanol addition to gasoline on an SI engine performance and exhaust emissions are investigated experimentally and theoretically. In the theoretical study, a quasi-dimensional SI engine cycle model, which was firstly developed for gasoline-fueled SI engines by author, has been adapted for SI engines running on gasoline–ethanol blends. Experimental applications have been carried out with the blends containing 1.5, 3, 4.5, 6, 7.5, 9, 10.5 and 12 vol% ethanol. Numerical applications have been performed up to 21 vol% ethanol. Engine was operated with each blend at 1500 rpm for compression ratios of 7.75 and 8.25 and at full throttle setting. Results obtained from both theoretical and experimental studies are compared graphically. Experimental results have shown that among the various blends, the blend of 7.5% ethanol was the most suitable one from the engine performance and CO emissions points of view. However, theoretical comparisons have shown that the blend containing 16.5% ethanol was the most suited blend for SI engines. Furthermore, it was demonstrated that the proposed SI engine cycle model has an ability of computing SI engine cycles when using ethanol and ethanol–gasoline blends and it can be used for further extensive parametric studies.     

Study of cold start air–fuel mixture parameters for spark ignition engines fueled with gasoline–isobutanol blends

Biofuels are set to play an important role in the future strategy of automotive fuel suppliers, and therefore the study of using alcohols in spark ignition engines has become a necessity. A simple thermodynamic model was developed for calculating air–fuel mixture parameters for port injection engines fueled with gasoline–isobutanol blends, and theoretical results were compared to experimental values. For simulating the evaporation process, gasoline was considered a mixture of four components, with isobutanol added in different proportions. As all engine components are at ambient temperature during cold starts, mixture formation was considered an adiabatic process, with the fuel breaking up into droplets and evaporating, thus resulting in a temperature drop. A port injection engine fitted to a passenger car was used to validate the model for calculating air–fuel mixture parameters.     

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.     

Active fuel design—A way to manage the right fuel for HCCI engines

Homogenous charge compression ignition (HCCI) engines feature high thermal efficiency and ultralow emissions compared to gasoline engines. However, unlike SI engines, HCCI combustion does not have a direct way to trigger the in-cylinder combustion. Therefore, gasoline HCCI combustion is facing challenges in the control of ignition and, combustion, and operational range extension. In this paper, an active fuel design concept was proposed to explore a potential pathway to optimize the HCCI engine combustion and broaden its operational range. The active fuel design concept was realized by real time control of dual-fuel (gasoline and n-heptane) port injection, with exhaust gas recirculation (EGR) rate and intake temperature adjusted. It was found that the cylinderto- cylinder variation in HCCI combustion could be effectively reduced by the optimization in fuel injection proportion, and that the rapid transition process from SI to HCCI could be realized. The active fuel design technology could significantly increase the adaptability of HCCI combustion to increased EGR rate and reduced intake temperature. Active fuel design was shown to broaden the operational HCCI load to 9.3 bar indicated mean effective pressure (IMEP). HCCI operation was used by up to 70% of the SI mode load while reducing fuel consumption and nitrogen oxides emissions. Therefore, the active fuel design technology could manage the right fuel for clean engine combustion, and provide a potential pathway for engine fuel diversification and future engine concept.     

Comparative studies on Performance evaluation of a two stroke copper coated spark ignition engine with alcohols with catalytic converter

AimInvestigations were carried out to evaluate the performance of a two-stroke, single cylinder, spark ignition (SI) engine, with alcohol blended gasoline (80% gasoline, 20% methanol by vol; 80% gasoline and 20% ethanol by volume) having copper coated engine [CCE, copper-(thickness, 300 μm) coated on piston crown, inner side of cylinder head] provided with catalytic converter with sponge iron as catalyst and compared with conventional SI engine (CE) with pure gasoline operation.Study designPerformance parameters of brake thermal efficiency, exhaust gas temperature and volumetric efficiency were determined at various values of brake mean effective pressure (BMEP).MethodologyA microprocessor-based analyzer was used for the measurement of carbon monoxide (CO) and un-burnt hydro carbons (UBHC) in the exhaust of the engine at various values of BMEP. Aldehydes were measured by dinitrophenyl hydrazine (DNPH) method at peak load operation of the engine.Brief resultsCCE with alcohol blended gasoline considerably reduced pollutants in comparison with CE with pure gasoline operation. Catalytic converter with air injection significantly reduced pollutants with test fuels on both configurations of the engine. Gasohol improved the performance of the both versions of the engine in comparison with methanol blended gasoline. On the other hand, methanol blended gasoline effectively reduced the emissions when compared with gasohol in both versions of the engine.     

Investigating the effects of LPG on spark ignition engine combustion and performance

A quasi-dimensional spark ignition (SI) engine cycle model is used to predict the cycle, performance and exhaust emissions of an automotive engine for the cases of using gasoline and LPG. Governing equations of the mathematical model mainly consist of first order ordinary differential equations derived for cylinder pressure and temperature. Combustion is simulated as a turbulent flame propagation process and during this process, two different thermodynamic regions consisting of unburned gases and burned gases that are separated by the flame front are considered. A computer code for the cycle model has been prepared to perform numerical calculations over a range of engine speeds and fuel–air equivalence ratios. In the computations performed at different engine speeds, the same fuel–air equivalence ratios are selected for each fuel to make realistic comparisons from the fuel economy and fuel consumption points of view. Comparisons show that if LPG fueled SI engines are operated at the same conditions with those of gasoline fueled SI engines, significant improvements in exhaust emissions can be achieved. However, variations in various engine performance parameters and the effects on the engine structural elements are not promising.     

EXPERIMENTAL INVESTIGATION ON VARYING THE COMPRESSION RATIO OF SI ENGINE WORKING UNDER DIFFERENT ETHANOL–GASOLINE FUEL BLENDS

Using different ethanol–gasoline fuel blends, a VARICOMP engine was used to study the effect of varying the compression ratio on SI engine performance. The performance tests were carried out using different percentages of ethanol in gasoline fuel, up to 40%, under variable compression ratio conditions. The results show that the engine indicated power improves with the percentage addition of the ethanol in the fuel blend. The maximum improvement occurs at 10% ethanol–90% gasoline fuel blend. © 1997 by John Wiley & Sons, Ltd.     

电喷汽油机燃用乙醇-汽油燃料的排放性能研究

研究了不同掺混比的乙醇 -汽油燃料在多点电喷汽油机上应用时的排放性能。研究结果表明 :在汽油机参数未做任何调整的情况下 ,在试验的掺混比范围内 ,随着乙醇 -汽油混合燃料中乙醇含量的增加 ,THC排放改善了 30 %,CO排放在大负荷时有所改善 ,NOx 排放在中、小负荷时改善较明显。排放特性的变化不仅与乙醇含量有关 ,而且与电喷发动机的空燃比控制策略有关。以质量计的燃油消耗率有所增加 ,但以燃料热值计的比能耗降低。     

Determination of ecological efficiency in internal combustion engines: The use of biodiesel

This paper evaluates and quantifies the environmental impact from the use of some renewable fuels and fossils fuels in internal combustion engines. The following fuels are evaluated: gasoline blended with anhydrous ethyl alcohol (anhydrous ethanol), conventional diesel fuel, biodiesel in pure form and blended with diesel fuel, and natural gas. For the case of biodiesel, its complete life cycle and the closed carbon cycle (photosynthesis) were considered. The ecological efficiency concept depends on the environmental impact caused by CO₂, SO₂, NO_x and particulate material (PM) emissions. The exhaust gases from internal combustion engines, in the case of the gasoline (blended with alcohol), biodiesel and biodiesel blended with conventional diesel, are the less polluting; on the other hand, the most polluting are those related to conventional diesel. They can cause serious problems to the environment because of their dangerous components for the human, animal and vegetable life. The resultant pollution of each one of the mentioned fuels are analyzed, considering separately CO₂, SO₂, NO_x and particulate material (PM) emissions. As conclusion, it is possible to calculate an environmental factor that represents, qualitatively and quantitative, the emissions in internal combustion engines that are mostly used in urban transport. Biodiesel in pure form (B100) and blended with conventional diesel as fuel for engines pollute less than conventional diesel fuel. The ecological efficiency for pure biodiesel (B100) is 86.75%; for biodiesel blended with conventional diesel fuel (B20, 20% biodiesel and 80% diesel), it is 78.79%. Finally, the ecological efficiency for conventional diesel, when used in engines, is 77.34%; for gasoline, it is 82.52%, and for natural gas, it is 91.95%. All these figures considered a thermal efficiency of 30% for the internal combustion engine.     

Analysis of performance parameters of an ethanol fueled spark ignition engine operating with hydrogen enrichment

Concerns with the environment and energy security have increased interest in phasing out fossil fuels in the automotive industry, as it transitions from conventional internal combustion engines (ICE) to electric and fuel cell powertrains. During this transition, ethanol is of particular interest as a renewable fuel option in ICE, despite drawbacks compared to gasoline. Adding hydrogen to ethanol could remedy the disadvantages associated with ethanol, while maintaining the benefits of using renewable fuels. There is a gap in the literature of both experimental and numerical studies considering hydrogen addition in turbocharged ethanol engines. Therefore, this paper presents an experimental and numerical study of a turbocharged ethanol engine operating with hydrogen enrichment at stoichiometric conditions under boosted conditions. It was concluded that hydrogen addition allowed spark ignition engines to achieve lower brake specific energy consumption, better performance, and lower emissions. Thus, after proper calibration, a simulation model was created and shown to be a suitable tool to predict engine performance of a spark ignition engine operating with hydrogen enrichment and reduce the overall number of experimental tests needed to tune engines operating with this fuel blend. Finally, some operating strategies are recommended based on these findings.     

汽油机燃用E10含水乙醇/汽油的试验研究

在高原地区开展了燃用含水乙醇/汽油混合燃料的试验研究。在汽油机上进行了纯汽油与掺比为10%含水乙醇(95%浓度)/汽油混合燃料的动力性、经济性和排放性能的对比试验。试验结果表明,E10混合燃料的稳定性良好;燃用E10含水乙醇/汽油混合燃料后,能保持发动机的原机动力性;在较低转速内,有效燃油消耗率有一定的上升,随着转速和负荷的提高,有效燃油消耗率的上升状况得到较好的改善;当量燃油消耗率明显低于原机水平;有效热效率得到不同程度的提高;怠速工况的CH和CO的排放有所改善。     

油品差异对汽车发动机性能影响的试验研究

国内外汽车用油存在较大差异,为了让国产车更好地满足国外市场需求,以我国出口汽车使用的甲基叔丁基醚（MTBE）（体积分数为10%）混合汽油、乙醇体积分数为20%（E20）的含水乙醇汽油和我国92号汽油为对象,基于某排量为2.0 T的汽油发动机台架试验,进行了三种油品对发动机性能影响的分析及验证。通过试验结果对比发现,使用MTBE混合汽油和E20含水乙醇汽油的动力性均低于92号汽油。在经济性方面,E20含水乙醇汽油略低于92号汽油,而MTBE混合汽油能使燃料消耗下降7%左右。在排放性方面,使用E20含水乙醇汽油和MTBE混合汽油对CO、HC的排放都有显著的改善效果,而在低转速、低负荷时对NO_x的排放有一定改善,随着转速和负荷的上升,E20含水乙醇汽油对NO_x的排放改善不明显,使用MTBE混合汽油时NO_x的排放反而变差。     

多缸HCCI汽油机SIAI/AI燃烧模式切换的试验

HCCI/SI复合燃烧模式是HCCI汽油发动机实用化的运行策略.但不同的空燃比和内部EGR率的需求给HCCI/SI模式切换带来了极大控制难度;同时由于HCCI负荷范围窄,使得燃烧模式切换频率过高,降低了发动机运行稳定性.在一台具备错位双凸轮机构的多缸汽油机上实现了火花点火激发混合气自燃着火(SIAI)燃烧方式,扩展了压燃模式下的负荷范围,研究了SIAI/SI燃烧模式的切换.结果表明,采用压缩冲程燃油喷射配合火花点火策略能够有效地避免燃烧模式切换中的失火现象,提高模式切换的稳定性;同时采用SIAI燃烧方式扩展内部EGR条件下的负荷范围,可以有效地减小模式切换频率.     

Biofuels policy and the US market for motor fuels: Empirical analysis of ethanol splashing

Low ethanol prices relative to the price of gasoline blendstock, and tax credits, have resulted in discretionary blending at wholesale terminals of ethanol into fuel supplies above required levels—a practice known as ethanol splashing in industry parlance. No one knows precisely where or in what volume ethanol is being blended with gasoline and this has important implications for motor fuels markets: Because refiners cannot perfectly predict where ethanol will be blended with finished gasoline by wholesalers, they cannot know when to produce and where to ship a blendstock that when mixed with ethanol at 10% would create the most economically efficient finished motor gasoline that meets engine standards and has comparable evaporative emissions as conventional gasoline without ethanol blending. In contrast to previous empirical analyses of biofuels that have relied on highly aggregated data, our analysis is disaggregated to the level of individual wholesale fuel terminals or racks (of which there are about 350 in the US). We incorporate the price of ethanol as well as the blendstock price to model the wholesaler's decision of whether or not to blend additional ethanol into gasoline at any particular wholesale city-terminal. The empirical analysis illustrates how ethanol and gasoline prices affect ethanol usage, controlling for fuel specifications, blend attributes, and city-terminal-specific effects that, among other things, control for differential costs of delivering ethanol from bio-refinery to wholesale rack.     

含氧燃料对内燃机燃烧和排放性能的影响

列举醇类、醚类、酯类、生物柴油等及其作为含氧燃料添加剂与汽、柴油混合的混合燃料性能，介绍部分纯质含氧燃料及其混合燃料对内燃机燃烧和排放的影响。研究表明，醇类燃料及其与汽油的混合燃料能够降低点燃式发动机的HC和CO排放，使发动机的动力性和经济性提高；二甲醚燃料、柴油与DMC或ADMM等的混合燃料对降低压燃式发动机的微粒排放具有显著的作用。含氧化合物混入燃油中有利于降低内燃机中HC，CO等物质的排放。     

The impacts of compression ratio on the performance and emissions of ice powered by oxygenated fuels: A review

Energy sources are becoming a governmental issue, with cost and stable supply as the main concern. Oxygenated fuels production is cheap, simple and eco-friendly, as a well as can be produced locally, cutting down on transportation fuel costs. Oxygenated fuels are used directly in an engine as a pure fuel, or they can be blended with fossil fuel. The most common fuels that are conceded under oxygenated fuels are ethanol, methanol, butanol Dimethyl Ether (DME), Ethyl tert-butyl ether (ETBE), Methyl tert-butyl ether (MTBE) and biodiesel that have attracted the attention of researchers. Due to the higher heat of vaporization, high octane rating, high flammability temperature, and single boiling point, the oxygenated fuels have a positive impact on the engine performance, combustion, and emissions by allowing the increase of the compression ratio. Oxygenated fuels also have a considerable oxygen content that causes clean combustion. The aim of this paper was to systematically review the impact of compression ratio (CR) on the performance, combustion and emissions of internal combustion engines (ICE) that are operated with oxygenated fuels that could potentially replace petroleum-based fuels or to improve the fuel properties. The higher octane rating of oxygenated fuels can endure higher compression ratios before an engine starts knocking, thus giving an engine the ability to deliver more power efficiently and economically. One of the more significant findings to emerge from this review study was the slight increases or decreases in power when oxygenated fuel was used at the original CR in ICE engines. Also, CO, HC, and NOx emissions decreased while the fuel consumption (FC) increased. However, at higher CR, the engine performance increased and fuel consumption decreased for both SI and CI engines. It was seen the NOx, CO and CO₂ emissions of oxygenated fuels decreased with the increasing CR in the SI engine, but the HC increased. Meanwhile, in CI engine, the HC, CO and NOx decreased as the CR increased with biodiesel fuel.