CAREER: Synthetic Mangrove Trees for Passive Desalination and Water Harvesting

职业：用于被动海水淡化和集水的合成红树林

基本信息

批准号：
1653631
负责人：
Jonathan Boreyko
金额：
$ 52.21万
依托单位：
Virginia Polytechnic Institute and State University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2017
资助国家：
美国
起止时间：
2017-03-15 至 2022-02-28
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1653631&HistoricalAwards=false
关键词：
CAREER Synthetic Mangrove Trees Passive

项目摘要

Synthetic Mangrove Trees for Passive Desalination and Water HarvestingAt least one-third of the world population does not have enough access to fresh water, and this is predicted to increase to two-thirds by 2025. Reverse osmosis plants, which pump ocean water through filters, are useful for large-scale desalination but require a large power consumption of about 2 kilowatt-hours for every cubic meter of purified water. Inspired by mangrove trees, this project seeks to develop an alternative means of harvesting fresh water that is powered by transpiration and does not require any active energy input. Synthetic mangrove leaves will be fabricated using 3D printing and connected to an array of micro-channels that mimic the xylem conduits of trees. As water evaporates from the nano-pores of the synthetic leaves, the water still inside of the leaves will exhibit a negative (suction) pressure due to the concave curvature of the water meniscus within each nano-pore. This suction pressure will generate a pressure differential across the synthetic xylem to allow for continuous pumping of water from a reservoir or moist soil. The ultimate goal is to achieve a suction pressure strong enough to pull ocean water through a salt-excluding filter without requiring a mechanical pump, analogous to how mangrove trees are able to grow in ocean water. To reach out to a broad audience, a completed artificial mangrove tree will be used to design a new exhibit at the Virginia Museum of Natural History. The objective of this project is to develop a synthetic mangrove tree capable of passively desalinating ocean water by generating transpiration-induced hydraulic loads exceeding 3 MPa. It is already known that water transpiring from a nanoporous medium can induce a highly negative water pressure due to the concave curvature of the menisci. However, current synthetic trees exhibit a very low hydraulic conductance and do not feature stomata on the transpiring leaves to help stabilize the water, which has constrained the hydraulic load to under 1 MPa and required impractical ambient humidities of over 85% to avoid dryout or boiling instabilities. Here, the stability and throughput of water flowing through synthetic trees will be dramatically improved by 3D printing an array of substomatal chambers and stomatal apertures at the interface of the synthetic leaves and by connecting the leaves to a dense array of micro-channels (xylem). The hypothesis is that the substomatal chambers serve to locally increase the humidity to avoid cavitation even in highly subsaturated ambient environments, while the increased conductance of the micro-channel array should prevent leaf dryout. The mass flux and by extension the hydraulic load will be measured by connecting the xylem to a water reservoir placed on a mass balance, heating the underside of the leaf, and exposing the top of the leaf to a controlled subsaturated ambient. The onset and dynamics of cavitation/dryout events will be captured using a top-down microscope focused on the xylem micro-channels. The metastability of the water will be analyzed using the Kelvin equation, Laplace equation, and classical nucleation theory. The flow of water through the tree will be modeled using Poiseuille's law (xylem), Darcy's law (nano-pores), and Fick's law (stomata). These theoretical insights will be correlated with the experimental measurements to optimize the design configuration of the final synthetic tree. The synergistic blend of controlled nanofabrication, experimental characterization, and theoretical analysis should uniquely reveal how the configuration of the xylem, nano-pores, substomatal chambers, and stomata serve to cooperatively govern the transpiration rate of water through trees.

合成红树林的被动息水和水收集至少三分之一的世界人口没有足够的淡水接入，预计到2025年，这将增加到三分之二。反渗透植物（通过过滤器向海水泵式渗透水，可用于大约2加牛油米的大量供水，可用于大约2级均等水平。受红树林的启发，该项目旨在开发一种替代手段，用于收获由蒸腾供电的淡水，不需要任何主动能量输入。合成的红树林叶子将使用3D打印制成，并连接到模仿树木木质部导管的一系列微通道。随着水从合成叶的纳米倍数蒸发时，由于每个纳米孔内的水弯板的凹入曲率，叶子内的水仍会表现出负（吸力）压力。这种吸力压力将在整个木质部产生压力差，以使水库或潮湿的土壤连续抽水。最终的目标是达到足够强大的吸力压力，可以通过盐分的过滤器拉出海水，而无需提供机械泵，类似于红树林如何在海水中生长。为了吸引广泛的观众，将使用完整的人造树林树来设计弗吉尼亚自然历史博物馆的新展览。该项目的目的是开发一种合成的红树林树，能够通过产生超过3 MPa的蒸腾诱导的液压负荷来被动地脱尔海水。众所周知，从纳米多孔培养基中渗出的水会由于半月板的凹入曲率引起高度负面的水压。然而，当前的合成树表现出非常低的液压电导，并且在蒸汽叶子上不带有气孔，以帮助稳定水，这将液压负荷限制在1 MPa以下，并要求不切实际的环境湿度超过85％以避免干燥或沸腾的不便。在这里，通过在合成叶的界面上打印一系列的定性腔和气孔孔，并将叶子连接到密集的微通道（Xylem），从而，将通过3D打印一系列的定性腔和气孔（Xylem），从而大大改善流过合成树的水的稳定性和吞吐量。假设的假设是，下定腔室用于局部增加湿度，即使在高饱和的环境环境中，也可以避免空化，而微通道阵列的电导率增加也应防止叶片干燥。质量通量和延长，将通过将木质部连接到放置在质量平衡上的水库中，加热叶子的底面，并将叶子的顶部暴露于受控的饱和环境中来测量液压负载。空化/干旱事件的发作和动力学将使用以木质部微通道上的自上而下的显微镜捕获。将使用开尔文方程，拉普拉斯方程和经典成核理论来分析水的亚稳定性。水通过树的流动将使用Poiseuille的定律（Xylem），Darcy的定律（纳米pores）和Fick的定律（气孔）进行建模。这些理论见解将与实验测量相关，以优化最终合成树的设计配置。受控纳米化，实验表征和理论分析的协同混合物应独特地揭示木质部，纳米孢子，定子腔和气孔的构型如何合作控制通过树木的水的跨性速率。

项目成果

期刊论文数量（6）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Synthetic trees for enhanced solar evaporation and water harvesting

DOI：
10.1063/5.0049904
发表时间：
2021-06
期刊：
Applied Physics Letters
影响因子：
4
作者：
Ndidi L. Eyegheleme;Weiwei Shi;Lance H. De Koninck;J. O'Brien;J. Boreyko
通讯作者：
Ndidi L. Eyegheleme;Weiwei Shi;Lance H. De Koninck;J. O'Brien;J. Boreyko

Modeling transpiration in synthetic trees

DOI：
10.1016/j.ijheatmasstransfer.2021.122121
发表时间：
2022-02
期刊：
International Journal of Heat and Mass Transfer
影响因子：
5.2
作者：
Ndidi L. Eyegheleme;K. Peng;J. Boreyko
通讯作者：
Ndidi L. Eyegheleme;K. Peng;J. Boreyko

Enhanced Water Evaporation with Floating Synthetic Leaves

通过漂浮的合成叶片增强水蒸发

DOI：
发表时间：
2018
期刊：
International Heat Transfer Conference
影响因子：
0
作者：
Shi, Weiwei;Vieitez, Joshua R.;Berrier, Austin S.;Roseveare, Matthew W.;Boreyko, Jonathan B.
通讯作者：
Boreyko, Jonathan B.

Passive water ascent in a tall, scalable synthetic tree