Water vapor capturing using an array of traveling liquid beads for desalination and water treatment

Abstract

Growing concern over the scarcity of freshwater motivates the development of compact and economic vapor capture methods for distributed thermal desalination or harvesting of water. We report a study of water vapor condensation on cold liquid beads traveling down a massive array of vertical cotton threads that act as pseudo-superhydrophilic surfaces. These liquid beads form through intrinsic flow instability and offer localized high-curvature surfaces that enhance vapor diffusion toward the liquid surface, a critical rate-limiting step. As the liquid flow rate increases, the bead spacing decreases, whereas the bead size and speed stay nearly constant. The resulting increase in the spatial bead density leads to mass transfer conductances and hence condensation rates per volume that are almost three times higher than the best reported values. Parallel and contiguous gas flow paths also result in a substantial reduction in gas pressure drop and hence electric fan power consumption.

Coating flows down a vertical fibre: towards the full Navier–Stokes problem

“…desalination (Sadeghpour et al. 2019); the reduced models cannot be applied and an accurate prediction of the flow dynamics is in demand.…”

Instabilities and bifurcations of liquid films flowing down a rotating fibre

“…Very recently, an experimental study by Sadeghpour etal. (2019) also showed that the water–vapour transfer rate in the coating flow is dependent on the AI–CI characteristics. For example, when the flow is absolutely unstable, the water–vapour transfer rate is generally promoted by increasing the liquid flow rate.…”

“…The most relevant work to the present problem is the study on the AI-CI characteristics of an exterior coating film down a vertical fibre (Duprat et al 2007). Very recently, an experimental study by Sadeghpour et al (2019) also showed that the water-vapour transfer rate in the coating flow is dependent on the AI-CI characteristics. For example, when the flow is absolutely unstable, the water-vapour transfer rate is generally promoted by increasing the liquid flow rate.…”

Pressure effect on an ocean-based humidification-dehumidification desalination process

“…Special designs can be implemented to the tank and pipe to increase the cooling surface and enhance condensation. Examples include employing a large number of pipes with small diameters, using fin structures [9] or string arrays [38], etc. At the end of this cooling phase, position 8, the temperature of the in-pipe moist air drops to the ambient temperature, and a portion of freshwater extraction is achieved.…”