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Simple Model for Diffusion-Limited Drop Evaporation of Binary Liquids from Physical Properties of the Components: Ethanol-Water Example.
Langmuir ( IF 3.7 ) Pub Date : 2020-01-07 , DOI: 10.1021/acs.langmuir.9b03590 Tugba Ozturk 1 , H Yildirim Erbil 1
Langmuir ( IF 3.7 ) Pub Date : 2020-01-07 , DOI: 10.1021/acs.langmuir.9b03590 Tugba Ozturk 1 , H Yildirim Erbil 1
Affiliation
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The understanding of the evaporation process of drops consisting of binary mixtures, in particular ethanol-water drops, is important in many industries such as ink-jet printing, cooling of microelectronics, and alcohol-added pesticide spray applications. The theory of the diffusion-limited drop evaporation process for pure liquids has been investigated thoroughly, and linear (dV(2/3)/dt) slopes were obtained for most of the cases. However, the evaporation of binary liquid drops was found to be much more complicated than that of the pure liquids due to the change of the composition of the drop by time and there is a need for the development of a new model. The experimental results on the diffusion-limited drop evaporation behavior of ethanol-water binary drops initially containing 25 and 50% ethanol by wt and having a volume of 7 μL were reported on a flat hydrophobic Teflon-FEP substrate under the constant relative humidity of 54% and 25 °C temperature conditions, together with pure liquids. The change of contact angles, heights, and contact radius of the drops by time were monitored with a camera. In a parallel study, the concentration changes in the bulk composition of ethanol-water binary drops of 7 μL (25 and 50% ethanol by wt) by time in the same evaporation conditions were monitored using a refractive index-ethanol concentration calibration curve. Then, the parameters affecting the drop evaporation process, such as total vapor pressures, average diffusion coefficient of binary vapors, average molecular weights, and densities of the liquid drops, were calculated using well-known physical chemistry approaches from the previously published data. These parameters were used to estimate the rate of binary ethanol-water drop evaporation, and it was determined that the proposed model fitted the (dV(2/3)/dt) slopes obtained from experimental data points with lower than 5% error when the surface cooling of the drops was considered.
中文翻译：
根据组分的物理性质对二元液体进行扩散限制的液滴蒸发的简单模型：乙醇-水实例。
对由二元混合物组成的液滴（特别是乙醇-水滴）的蒸发过程的理解在许多行业中都很重要，例如喷墨印刷，微电子冷却和添加酒精的农药喷雾应用。已对纯液体的扩散受限液滴蒸发过程的理论进行了深入研究，并且在大多数情况下获得了线性（dV（2/3）/ dt）斜率。然而，由于液滴的组成随时间变化，因此发现二元液滴的蒸发比纯液体的蒸发复杂得多，并且需要开发新的模型。在恒定相对湿度为54的平坦疏水性Teflon-FEP基底上报道了最初含25％和50％重量百分比的乙醇且体积为7μL的乙醇-水二元液滴扩散受限液滴蒸发行为的实验结果。 ％和25°C温度条件，以及纯净液体。用照相机监测液滴的接触角，高度和接触半径随时间的变化。在一项平行研究中，使用折射率-乙醇浓度校准曲线监测了在相同蒸发条件下，乙醇-水二元滴7升（25和50％重量百分比的乙醇）的总体组成中浓度的时间变化。然后，影响液滴蒸发过程的参数，例如总蒸气压，二元蒸气的平均扩散系数，平均分子量和液滴的密度是使用众所周知的物理化学方法从以前发布的数据中计算得出的。这些参数用于估计二元乙醇-水滴蒸发的速率，并且确定所提出的模型拟合了从实验数据点获得的（dV（2/3）/ dt）斜率，当误差小于5％时。考虑了液滴的表面冷却。
更新日期：2020-01-29
中文翻译：
根据组分的物理性质对二元液体进行扩散限制的液滴蒸发的简单模型：乙醇-水实例。
对由二元混合物组成的液滴（特别是乙醇-水滴）的蒸发过程的理解在许多行业中都很重要，例如喷墨印刷，微电子冷却和添加酒精的农药喷雾应用。已对纯液体的扩散受限液滴蒸发过程的理论进行了深入研究，并且在大多数情况下获得了线性（dV（2/3）/ dt）斜率。然而，由于液滴的组成随时间变化，因此发现二元液滴的蒸发比纯液体的蒸发复杂得多，并且需要开发新的模型。在恒定相对湿度为54的平坦疏水性Teflon-FEP基底上报道了最初含25％和50％重量百分比的乙醇且体积为7μL的乙醇-水二元液滴扩散受限液滴蒸发行为的实验结果。 ％和25°C温度条件，以及纯净液体。用照相机监测液滴的接触角，高度和接触半径随时间的变化。在一项平行研究中，使用折射率-乙醇浓度校准曲线监测了在相同蒸发条件下，乙醇-水二元滴7升（25和50％重量百分比的乙醇）的总体组成中浓度的时间变化。然后，影响液滴蒸发过程的参数，例如总蒸气压，二元蒸气的平均扩散系数，平均分子量和液滴的密度是使用众所周知的物理化学方法从以前发布的数据中计算得出的。这些参数用于估计二元乙醇-水滴蒸发的速率，并且确定所提出的模型拟合了从实验数据点获得的（dV（2/3）/ dt）斜率，当误差小于5％时。考虑了液滴的表面冷却。
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