| 项目编号: | 1603737
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| 项目名称: | Flexible flapping surfaces for water collection and condensation |
| 作者: | Melanie Derby
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| 承担单位: | Kansas State University
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| 批准年: | 2016
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| 开始日期: | 2016-07-01
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| 结束日期: | 2019-06-30
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| 资助金额: | 313655
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| 资助来源: | US-NSF
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| 项目类别: | Standard Grant
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| 国家: | US
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| 语种: | 英语
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| 特色学科分类: | Engineering - Chemical, Bioengineering, Environmental, and Transport Systems
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| 英文关键词: | surface
; water collection
; water quality
; water harvesting
; droplet
; water
; girl
; surface tension
; stationary surface
; water sample
; surface energy
; water conservation
; polymer surface
; effect
; power plant
; total water removal rate
; water intensive process
; condenser surface
; numerical simulation
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| 英文摘要: | 1603737
Derby
Electrical 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. |
| 资源类型: | 项目
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| 标识符: | http://119.78.100.158/handle/2HF3EXSE/91955
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| Appears in Collections: | 全球变化的国际研究计划
科学计划与规划
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| Recommended Citation: | |
Melanie Derby. Flexible flapping surfaces for water collection and condensation. 2016-01-01.
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