Flexible flapping surfaces for water collection and condensation

1603737德比电力生产是一个非常水密集的过程，需要超过十加仑的水来产生每千瓦时的电力在美国发电厂冷却塔代表了一个有前途的领域，用于水收集，因为排污和蒸发的水可以回收和用于能源生产，工业或农业。薄，拍打聚合物薄膜/网格是一个潜在的变革过程，这将减少从空气中的热阻，通过聚合物的传导，和冷凝，从而增加总的水去除率。从初步的调查结果，液滴振荡的全氟烷氧基薄膜，在14赫兹的拍打从拍打表面喷出。平均液滴离开直径为0.985毫米的扑动表面，相比之下，3.27毫米的静止表面。拍打增加了两个数量级的液滴去除率和估计的水收集量的204%。估计的能量为17 W/m2，这可以减少或消除自扑翼。本研究将调查拍打对用于集水的柔性聚合物膜的影响。数值模拟将确定激励液滴所需的加速度，并了解拍打对水收集的影响。实验验证将在环境室中对拍打膜/网进行，条件类似于冷却塔羽流。此外，将使用来自狼溪发电站和杰弗里能源中心的水样进行实验，以确定回收的水质，并将考虑第一次冲洗和随后的样品，以确定水质随时间的变化。水质评估将侧重于盐度、阳离子和阴离子、营养物和细菌。将把收集的水与农业生产的灌溉标准以及发电厂和工业要求进行比较。建议的工作将增加液滴运动的柔性，扑动表面的基础知识。数值模拟将产生液滴平移或从表面喷射所需的拍打频率和振幅。液滴随时间的增长将通过使用撞击液滴和冷凝液滴的高速流动可视化来确定。将在301 K和80%RH下研究拍打式冷凝器表面，类似于冷却塔羽流条件。除了水的收集率，液滴成核，聚结，和离开将比较扑动和静止的表面，从而在一个更好的理解液滴动态振荡表面。已经确定了几种机制，可以解释上级液滴运动扑表面：表面张力，空气截留，并改变接触线软，聚合物表面。将进行数值模拟和实验验证，以确定这些建议的机制对水收集的相对影响。将对所监测的水质进行评估，并确定可能的工业和农业用途。本研究的目的是：1.了解拍打频率（1-100 Hz）和振幅对液滴聚结和从表面喷射的影响。蝴蝶、昆虫和旗帜在这个频率范围内摆动。2.在柔软的拍打表面上模拟液滴行为，包括聚结、重力、加速度、表面张力和表面能对液滴形成和运动的影响。3.确定在受控环境中扑翼对液滴清扫和水收集的影响，类似于冷却塔羽流。4.评估发电厂和农业应用的回收水质量。此外，PI和学生将为初中和高中女生创建一个工程外展模块，每年通过KAWSE计划接触100名女生。女孩们将创造喷刷T恤设计。使用高速视频，女孩们将确定平均油漆液滴大小，并评估油漆液滴行为如何随着拍打而变化，类似于拍打薄膜收集水。该项目与水资源保护和日常生活的相关性将吸引并激励女孩们追求STEM职业。该模块的简化版将每年在Aggieville Mini Maker Faire进行，并将吸引当地社区的儿童参与。

1603737DerbyElectrical power production is an extremely water intensive process, requiring over ten gallons of water to produce each kWh of electricity in the U.S. Power plant cooling towers represent a promising area for water harvesting, as blowdown and evaporated water could be recovered and used for energy production, industry, or agriculture. Thin, flapping polymer films/meshes are a potentially transformative process which would reduce thermal resistances from air, conduction through the polymer, and condensation, thereby increasing total water removal rates.From preliminary findings, droplets oscillated on a perfluoroalkoxy film, flapping at 14 Hz were ejected from the flapping surface. Average droplet departure diameters were 0.985 mm on flapping surfaces, compared to 3.27 mm on stationary surfaces. Flapping increased droplet removal rates by two orders of magnitude and estimated water collection volume by 204 %. Estimated energy to flap was 17 W/m2, and this could be reduced or eliminated by self-flapping. This research will investigate the effects of flapping on flexible polymer films for water harvesting. Numerical simulations will determine accelerations required to motivate droplets, and understand the impact of flapping on water harvesting. Experimental validation will be conducted on flapping films/meshes in an environmental chamber, with conditions similar to a cooling tower plume. Also, experiments will be conducted using water samples from Wolf Creek Generating Station and Jeffrey Energy Center to determine recovered water quality, and will consider the first flush and subsequent samples to determine the change in water quality with time. Water quality assessment will focus on salinity, cations and anions, nutrients, and bacteria. Recovered water will be compared to irrigation standards for agricultural production, as well as power plant and industrial requirements. The proposed work will increase fundamental knowledge of droplet motion on flexible, flapping surfaces. Numerical simulations will yield flapping frequencies and amplitudes required for droplets to translate or eject from the surface. Droplet growth with respect to time will be determined with high-speed flow visualization using impinging droplets and condensing droplets. Flapping condenser surfaces will be studied at 301 K and 80 % RH, similar to cooling tower plume conditions. In addition to water collection rates, droplet nucleation, coalescence, and departure will be compared for flapping and stationary surfaces, resulting in an improved understanding of droplet dynamics on oscillating surfaces. Several mechanisms have been identified which may explain superior droplet motion on flapping surfaces: surface tension, air entrapment, and altered contact lines on soft, polymer surfaces. Numerical simulations and experimental validations will be conducted to determine the relative effects of these proposed mechanisms on water collection. Recovered water quality will be assessed and possible industrial and agricultural uses identified. The research objectives are to: 1. Understand the impact of flapping frequency (1-100 Hz) and amplitude on droplet coalescence and ejection from the surface. Butterflies, insects, and flags flap in this frequency range. 2. Model droplet behavior on a soft, flapping surface, including the effects of coalescence, gravity, acceleration, surface tension, and surface energy on droplet formation and motion. 3. Determine the effects of flapping on droplet sweeping and water collection in a controlled environment, similar to a cooling tower plume. 4. Assess recovered water quality for power plant and agricultural applications. In addition, the PIs and students will create an engineering outreach module for middle and high school girls, reaching 100 girls each year through the KAWSE program. The girls will create airbrushed T shirt designs. Using high speed videos, the girls will determine average paint droplet size and assess how paint droplet behavior changes with flapping, analogous to the flapping film for water collection. The relevance of this project to water conservation and daily life will interest and inspire the girls to pursue STEM careers. A simplified version of this module would be conducted every year at the Aggieville Mini Maker Faire, and will engage children in the local community.