Abstract After fermentation, the concentration of bioethanol is only 8–12 wt%. To produce anhydrous ethanol fuel, a significant amount of energy is required for separation and dehydration. Once the azeotrope composition is reached, distillation can no longer be exploited for purification and more expensive methods must be used. Replacing anhydrous ethanol fuel with hydrous ethanol (at the azeotrope composition) can result in significant energy and cost savings during production. The goal of this study was to characterize the volatility behavior and the droplet evaporation dynamics of hydrous and anhydrous ethanol gasoline blends. Three hydrous ethanol-gasoline blends (10, 15, and 30 vol%) in which the hydrous ethanol was composed of the azeotropic proportions of ethanol and water, and three anhydrous ethanol gasoline blends (10, 15, and 30 vol%) were prepared and analyzed with the advanced distillation curve method. Distillation curves were obtained for all test fuels and distillate samples were taken during the distillation process. A droplet evaporation model validated with the distillation data was exploited to understand how the non-ideal volatility behavior of these blends, the high heat of vaporization of water, and altered fluid properties can affect the transient droplet evaporation phenomena and thus the fuel's potential to effectively mix with air in direct injection internal combustion engines. Minor differences in the distillation curves and vapor-liquid equilibrium between the hydrous and anhydrous fuels were measured. Droplet modeling results showed that the higher heat of vaporization and viscosity of water relative to ethanol can lead to significant differences in the net droplet evaporation time between the two types of blends, especially at the higher blending ratios evaluated. These results suggest that the presence of water in ethanol-gasoline blends may extend droplet lifetimes and increase the susceptibility of the fuel to form particulate matter emissions. This is the first study to use distillation methods to gain a better understanding of evaporation behavior and the role of water's non-linear vapor-liquid equilibrium on droplet evaporation dynamics.

中文翻译：

---

含水和无水乙醇汽油混合物的近共沸挥发行为及其对液滴蒸发动力学的影响

摘要 发酵后生物乙醇的浓度仅为8-12 wt%。为了生产无水乙醇燃料，分离和脱水需要大量的能量。一旦达到共沸组合物，就不能再利用蒸馏进行纯化，必须使用更昂贵的方法。用含水乙醇（处于共沸组成）代替无水乙醇燃料可以在生产过程中显着节省能源和成本。本研究的目的是表征含水和无水乙醇汽油混合物的挥发性行为和液滴蒸发动力学。三种含水乙醇汽油混合物（10、15 和 30 vol%），其中含水乙醇由乙醇和水的共沸比例组成，以及三种无水乙醇汽油混合物（10、15、和 30 vol%) 用先进的蒸馏曲线方法制备和分析。获得了所有测试燃料的蒸馏曲线，并在蒸馏过程中采集了馏出物样品。利用蒸馏数据验证的液滴蒸发模型来了解这些混合物的非理想挥发性行为、水的高汽化热和改变的流体性质如何影响瞬态液滴蒸发现象，从而影响燃料的有效利用潜力在直喷式内燃机中与空气混合。测量了含水燃料和无水燃料之间蒸馏曲线和汽液平衡的微小差异。液滴建模结果表明，相对于乙醇而言，水的汽化热和粘度较高，这会导致两种类型的混合物之间的净液滴蒸发时间存在显着差异，尤其是在评估的较高混合比率下。这些结果表明，乙醇-汽油混合物中水的存在可能会延长液滴寿命并增加燃料形成颗粒物排放物的敏感性。这是首次使用蒸馏方法更好地了解蒸发行为以及水的非线性汽液平衡对液滴蒸发动力学的作用的研究。这些结果表明，乙醇-汽油混合物中水的存在可能会延长液滴的寿命并增加燃料形成颗粒物排放物的敏感性。这是首次使用蒸馏方法更好地了解蒸发行为以及水的非线性汽液平衡对液滴蒸发动力学的作用的研究。这些结果表明，乙醇-汽油混合物中水的存在可能会延长液滴的寿命并增加燃料形成颗粒物排放物的敏感性。这是首次使用蒸馏方法更好地了解蒸发行为以及水的非线性汽液平衡对液滴蒸发动力学的作用的研究。