A team of UCLA engineers and mathematicians were inspired by the formation of dew drops on spider webs that they were able to create a quite simple yet unique and effective way to capture water vapor producing clean, fresh water, or to recycle industrial water that would otherwise be wasted.
Their system is a 'dense array of parallel cotton threads strung vertically, with a steady stream of water droplets flowing down the strings'. The water vapor is then pushed upward by a fan and then captured by the "web" of water droplets and condenses. The collected water is then moved into a container.
Results showed a 200 percent increase in efficiency when using this method if compared to existing technologies that captures water vapor.
In addition to harvesting water from the atmosphere, the method could be used to produce clean water from the evaporation of high-salinity wastewaters, such as those produced from oil and gas production, or from irrigation runoff.
It could also be used in recycling steam that espaces from cooling towers in power plants and industrial facilities which can then be recycled back into the cooling system.
There are several methods proposed of capturing water vapor; some with the use of chilled metal, others with the use of spray nozzles or electric fields, but most of the aren't adopted due to manufacturing costs and energy inefficiency.
"The growing global concern over the scarcity of fresh water has motivated the development of economically feasible ways to capture water vapor," said Sungtaek Ju, professor of mechanical and aerospace engineering at the UCLA Samueli School of Engineering and the principal investigator of the study. "This idea of imitating the natural rain cycle to produce clean water, called 'the humidification-dehumidification process,' has been around for quite some time. However, making such a system that's inexpensive to build and operate has been a major challenge. Our system is inexpensive, lightweight and energy-efficient. These factors can potentially help overcome challenges for its adoption."
Something that is noteworthy of this particular system is its consistency. It is able to generate water droplets of the same size and constant flowing speed."The liquid beads form highly curved surfaces that enhance the rate at which water vapor diffuses through the air," said Abolfazl Sadeghpour, a UCLA mechanical engineering graduate student and a co-lead author of the study. "Simply said, this is analogous to a snowball rolling downhill. The beads are picking up water vapor as they travel down. And while a drop may seem small, think of an entire array of threads working constantly. The water vapor harvested could add up to quite a bit."
