【作者】 游伏兵；

【导师】 高孝洪； 李格升；

【作者基本信息】 武汉理工大学 ， 轮机工程， 2008， 博士

【摘要】 目前人类所依存的能源,主要是不可再生的化石能源。但对化石能源储采比的研究表明,化石能源的可开采年限有限。而大规模的使用化石能源,将地底下沉积几亿年的碳元素不可逆地引入大气层,也导致了全球温室气体排放严重,气候变暖。随着经济的发展,能源消费量的日益增加与能源储量日益减少和环境日益恶化的矛盾迫使人类不得不寻找新的替代能源。太阳能、风能、海洋能、地热能和生物质能等可再生能源都是未来潜在的替代能源。在目前的技术条件下,和其他可再生能源相比,生物质能中的生物柴油和生物酒精因其能量密度的优势更适于作为载运工具的替代燃料。生物乙醇作为车用替代燃料的技术最为成熟,乙醇汽油已得到广泛应用。但在现有发动机上使用乙醇汽油乙醇的含量不能大于10%,替代率低。若直接燃用高乙醇含量的乙醇汽油发动机需作大的结构改造。而且乙醇汽油对乙醇的纯度要求高,必须是脱水酒精,体积浓度在99.5%以上。本课题提出的含水酒精重整燃料方案可克服以上缺点,将含水酒精直接在现有发动机上应用。基本原理是将含水酒精重整为富氢混合气后供发动机燃烧,含水酒精的蒸发和重整所需的热量由发动机的排气余热提供。本文的主要目的就是研究含水酒精重整燃料的各种特性,寻找对含水酒精重整燃料发动机热效率产生重大影响的燃料内在因素,提出含水酒精重整燃料发动机性能优化策略,为发动机的开发提供理论依据和技术支持。主要研究内容为:1)论述了本文研究的背景、目的和意义。2)研究了在发动机运行的条件下,乙醇水蒸气在催化剂作用下的重整规律。利用乙醇水蒸气催化重整可得到富氢混合气;在可比条件下,重整率随温度的升高而增加,随酒精浓度的增加而增加,随着酒精流量增加而减小,但在有效空速比范围内,酒精流量对重整率影响有限。3)分析了含水酒精重整燃料的特性。含水酒精经过重整后燃料的热值得到了提高,由于富含H₂燃烧特性得到了改善。但因其气体的形态,对发动机的充气效率带来不利影响,而且燃烧时分子体积减小,部分抵消了燃料热值提高和燃烧特性改善有利于发动机性能提高的作用。4)研究了含水酒精重整燃料-空气混合气发动机的理论循环。随着重整率的提高,理想循环的最高温度逐渐增大,由于分子体积变化系数的影响,循环最大压力随着重整率的提高逐渐下降;随着重整率的提高,循环热效率逐渐增加。5)对比分析了RE发动机和VE发动机台架试验结果。RE发动机热效率较VE发动机高,主要原因是由于RE燃料为富氢混合气,实现了快速燃烧和稀薄燃烧;6)研究了以现有发动机改造的含水酒精重整燃料发动机性能优化策略。提高压缩比、点火提前角增大、实现稀薄燃烧都可改善发动机经济性和排放性能。与原机相比,优化后的RE发动机除动力性有所下降外,经济性和排放性能都大幅提高。更多还原

【Abstract】 At present the nonrenewable fossil fuel is the main energy source human-being depend on.But the researches for the reserve/production ratio of fossil fuel indicate the durative time of fossil fuel production is limited.The serious emission of greenhouse gas and warming of the climate are induced by large scale application of fossil fuel which introduces the carbon depositing under the ground hundreds of millions years to the aerosphere.With the development of the economy, human-being are forced to search new alternative energy by energy consume increasing,energy source reserve decreasing and the environment worsening.Solar,wind,ocean,geothermal and biomass are the potential alternative energy sources in the future.To the technology of present status,biodiesel and bioethanol are fit for the transport facilities in comparison with all other alternative fuels because of its relatively greater power density.The technology of ethanol as engine alternative fuel is ripest for ethanol-gasoline widely application in the market.But the ratio of ethanol in ethanol-gasoline used to the existing engines couldn’t be over 10%,and there are many structure modifications to the existing engines using high ratio ethanol-gasoline.And ethanol-gasoline needs dehydrated ethanol which purity must be over 99.5%.The hydrous-ethanol reforming approach presented in this paper could overcome above shortcomings,which applies hydrous-ethanol to the existing engines directly.The principle of the approach is that hydrous-ethanol is reformed to hydrogen-rich gas mixture for engine combustion,and the energy source for ethanol steam evaporating and reforming comes from the waste heat of engine exhaust.To support the development of hydrous-ethanol reforming fuel engines(RE), the main aim of this paper is to research the characters of hydrous-ethanol reforming fuel,study the intrinsic factors of the fuel which improve engine thermal efficiency, and put forward the optimizing strategies for engine performances.The main contents include:1) The research background,aim and significance have been discussed.2) The reforming rules of ethanol steam with catalyst under the conditions provided by running engine have been studied.Hydrogen-rich gas mixture could be produced by ethanol steam reforming with catalyst;under the comparable conditions,the reforming ratio would be improved with temperature increasing and with alcohol concentrate increasing,and decreased with alcohol flux increasing.3) The characters of hydrous-ethanol reforming fuel have been analyzed.Heat value of hydrous-ethanol reforming fuel is increased,and combustion performance is improved due to hydrogen-rich.But the gas form of it brings negative influence to engine charge coefficient,and moles shrinkage in combustion partly offsets the positive effect from increased heat value and improved combustion performance.4) Engine theory cycle with hydrous-ethanol reforming fuel/air mixture is studied.With reforming ratio increasing,the maximal temperature and thermal efficiency of theory cycle is increasing,but the maximal pressure would be decreasing with reforming ratio increasing due to influence of moles.5) Kit experiment results of RE compared to that of hydrous-ethanol vapor engine(VE) are studied.The thermal efficiency of RE is higher than that of VE because hydrogen-rich RE fuel realizes quick combustion and lean combustion.6) Optimizing strategies for performances of RE based on existing engine have been researched.The economy and emission performances of RE could be improved by increasing compression ratio and ignition angle,and realizing lean combustion.Compared to the baseline gasoline engine,optimized RE performances including energy consuming and emissions are improved greatly except of power performance.更多还原