Dewvaporation is a novel
desalination
Desalination is a process that takes away mineral components from saline water. More generally, desalination refers to the removal of salts and minerals from a target substance, as in Soil salinity control, soil desalination, which is an issue f ...
technology developed at
Arizona State University
Arizona State University (Arizona State or ASU) is a public research university in the Phoenix metropolitan area. Founded in 1885 by the 13th Arizona Territorial Legislature, ASU is one of the largest public universities by enrollment in the ...
(Tempe) as an
energy efficient tool for freshwater procurement and saline waste stream management. The system has relatively low installation costs and low operation and maintenance requirements.
The process uses air as a
carrier gas
Carrier may refer to:
Entertainment
* ''Carrier'' (album), a 2013 album by The Dodos
* ''Carrier'' (board game), a South Pacific World War II board game
* ''Carrier'' (TV series), a ten-part documentary miniseries that aired on PBS in April 20 ...
that transfers water
vapor
In physics, a vapor (American English) or vapour (British English and Canadian English; American and British English spelling differences#-our, -or, see spelling differences) is a substance in the gas phase at a temperature lower than its critic ...
from ascending evaporative channels to adjacent, descending
dew
Dew is water in the form of droplets that appears on thin, exposed objects in the morning or evening due to condensation.
As the exposed surface cools by radiating its heat, atmospheric moisture condenses at a rate greater than that at wh ...
-forming channels. Heat flowing through the barrier allows the
evaporative energy requirement to be fully satisfied by the heat released by condensation on the dew forming side. A small pressure difference is held so that the condensing cooler air is kept on the cool side.
Near
atmospheric
An atmosphere () is a layer of gas or layers of gases that envelop a planet, and is held in place by the gravity of the planetary body. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A s ...
operation permits
corrosion
Corrosion is a natural process that converts a refined metal into a more chemically stable oxide. It is the gradual deterioration of materials (usually a metal) by chemical or electrochemical reaction with their environment. Corrosion engine ...
free and
scale-resistant
polypropylene
Polypropylene (PP), also known as polypropene, is a thermoplastic polymer used in a wide variety of applications. It is produced via chain-growth polymerization from the monomer propylene.
Polypropylene
belongs to the group of polyolefins and ...
construction, and also allows the use of low-grade heat to drive the process.
The process is proprietary, developed by Dr. James R. Beckman. Currently, Altela Inc. (Albuquerque, NM) is manufacturing this technology under the AltelaRain trade name.
Detailed process
According to the
Bureau of Reclamation
The Bureau of Reclamation, and formerly the United States Reclamation Service, is a federal agency under the U.S. Department of the Interior, which oversees water resource management, specifically as it applies to the oversight and opera ...
, a branch of the
US Department of Interior
The United States Department of the Interior (DOI) is one of the executive departments of the U.S. federal government headquartered at the Main Interior Building, located at 1849 C Street NW in Washington, D.C. It is responsible for the mana ...
, this process uses simple corrugated plastic tanks with many "DewVaporation columns" inserted in each tank.
Figure 5. Top View of Tower
/ref> Each column is made of corrugated plastic and is divided into two compartments. The wall in the middle serves for receiving and evaporating sea-water into a hot air stream, and on the other side for condensing freshwater. The cooling from the evaporation helps water condense
Condensation is the change of the state of matter from the gas phase into the liquid phase, and is the reverse of vaporization. The word most often refers to the water cycle. It can also be defined as the change in the state of water vapor to ...
on the dividing wall, while the energy from the condensing vapor, now turned to droplets, passes back to the evaporation
Evaporation is a type of vaporization that occurs on the surface of a liquid as it changes into the gas phase. High concentration of the evaporating substance in the surrounding gas significantly slows down evaporation, such as when humidi ...
side, and is absorbed in the evaporating sea water. This way, much of the energy (as heat) is left in the process, and is not removed with the air leaving the DewVaporation column.
Various improvements have been proposed, among those reusing the output brine and adding external heat in a stacked way, so that the pressure and humidity gap between the two sides of the column are optimal and constant.
See also
* Heat of evaporation
The enthalpy of vaporization (symbol ), also known as the (latent) heat of vaporization or heat of evaporation, is the amount of energy (enthalpy) that must be added to a liquid substance to transform a quantity of that substance into a gas. T ...
* Heat transfer
Heat transfer is a discipline of thermal engineering that concerns the generation, use, conversion, and exchange of thermal energy (heat) between physical systems. Heat transfer is classified into various mechanisms, such as thermal conduction, ...
References
External links
Solar Desalination using DewvaporationSeawater desalination using Dewvaporation technique: theoretical development and design evolutionSeawater desalination using Dewvaporation technique: experimental and enhancement work with economic analysisDewvaporation Desalination 5,000-Gallon-Per-Day Pilot PlantBrackish and seawater desalination using a 20 ft2 dewvaporation tower
Water treatment
Water desalination