【作者】 王进；

【导师】 程勇；

【作者基本信息】 山东大学 ， 动力机械及工程， 2013， 硕士

【摘要】 近年来,我国汽车工业飞速发展,汽车保有量迅速增加,随之带来的石油资源短缺以及环境污染问题日益突出,亟需寻找替代燃料,其中醇类燃料是最现实的替代燃料之一。甲醇来源广泛,可以由煤、天然气、海藻等多种含碳物质生产而来。甲醇作为发动机替代燃料,热效率较高,甲醇是含氧燃料,避免了缸内混合气不均匀而造成的局部缺氧燃烧,可以降低CO的排放,并且由于甲醇汽化潜热较大,降低缸内温度使得NOx的排放量较低。但是甲醇对金属具有较强的腐蚀性,直接把甲醇应用到发动机上,会对发动机造成腐蚀。利用发动机废气余热将甲醇裂解,裂解后的甲醇裂解气主要包括氢气、一氧化碳以及甲醇蒸汽,缓解了液态甲醇对发动机的腐蚀,裂解气吸收发动机的废气余热,低热值提高,甲醇裂解气中富含氢气,有利于发动机的经济性以及排放特性。本课题对原有的甲醇裂解气发动机试验台架进行了改造,开发了试验所用的稳态数据采集系统和甲醇喷射控制系统,完善了试验环境。研究了甲醇裂解气的供气方式,并对现有甲醇裂解气供气方式对发动机功率、瞬态响应性、空燃比循环变动以及进气回火问题的影响进行了分析。开发了用于甲醇发动机冷起动以及提高裂解气发动机瞬态响应特性的液态甲醇加热蒸发装置,采用甲醇加热蒸发装置对甲醇进行预热,可以使发动机在环境温度为1℃时,以纯甲醇燃料顺利起动。通过试验,对甲醇裂解气发动机的起燃特性、甲醇裂解率、缸内工作过程等进行了研究,并对甲醇裂解气发动机的动力性、经济性以及排放特性与汽油机进行了对比分析。试验结果表明,甲醇裂解气发动机的起燃时间受环境温度影响较大,并且甲醇燃料相比于汽油燃料需要更长的起燃时间；由于钯系催化剂在较宽的温度范围内具有较高的活性以及甲醇裂解器的温度在短时间内受发动机排温影响较小,因此裂解气中氢气体积浓度变化较小,一般在42%～46%之间；在相同中、小节气门开度下,裂解气发动机输出功率大于汽油机,而当节气门开度大于67%时,由于受进气量的影响,裂解气发动机的输出功率逐渐小于汽油机；裂解气发动机缸内最大压力和压力升高率都要大于汽油机,燃烧速度较快,定容度较高,使得发动机循环热效率较高,经济性较好；在相同的工况下,甲醇裂解气发动机的CO以及NOx的排放值要远远低于汽油机的排放值,而甲醇裂解气发动机的HC排放值要略高于汽油机,并且甲醛排放相比于汽油机较高,需要做进一步的后处理。更多还原

【Abstract】 In recent years, with the rapid increase of vehicle population,the environmental pollution problems and consequent shortage of oil resources have become increasingly prominent, it is urgent to find alternative fuels, methanol is one of the most realistic alternative fuel.Methanol can be produced from widely available fossil raw materials including coal, nature gas and seaweed. There are many advantages for liquid methanol which is used in internal combustion engine, such as its high thermal efficiency, less emissions of CO and NOx. But methanol’s corrosion on metal have seriously restricted the application of methanol fuel in internal combustion engine. This problems can be reduced by reforming methanol. Owing to the high economy and low emissions, reformed methanol gas (RMG) engine has caused more and more attention.Transformed the engine test bench, and developed a data acquisition system and a injection control system of methanol. Researched the RMG’s inlet mode and analyzed its influence on power, transient response, air-fuel ratio and inlet backfire. Developed a supply system for liquid methanol, which is used in the case of cold starting and transient conditions. The methanol engine could be easily-start under atmospheric temperature of1℃. This paper analyzed the performance of RMG engine through experiments, such as characteristics of the engine-reformer system, the RMG’s composition under different conditions, power, fuel economy, emissions, and combustion process in the cylinder etc.The test results show that the time when the engine-reformer worked depends on ambient temperature, and using methanol take longer time than using gasoline. The hydrogen volume concentration in RMG is between42%and46%. The RMG engine’s maximum pressure and rate of pressure rise in the cylinder are larger than gasoline engine, lead to the high fuel economy. The RMG engine’s power is larger than gasoline engine’s in small throttle opening, but it is smaller than the gasoline engine’s when the throttle opening is larger than67%. The RMG engine’s emissions of CO and NOx are far lower than gasoline engine’s, but the RMG engine’s emissions of HC are slightly larger than gasoline engine’s. In addition, the RMG engine has high formaldehyde emissions.更多还原