Dewvaporation
Encyclopedia
Dewvaporation is a novel desalination
technology developed at Arizona State University
(Tempe) as an energy efficient
tool for freshwater procurement and saline waste stream management. The system has relative low installment costs and low operation and maintenance requirements.
The process uses air as a carrier gas that transfers water vapor
from ascending evaporative channels to adjacent, descending dew
-forming channels. Thermal communication across the channel boundaries allows the evaporative energy requirement to be fully satisfied by the heat of fusion on the dew forming side. A small pressure difference is held so that the condensing cooler air is kept on the cool side by a slight pressure difference.
Near atmospheric
operation permits corrosion
free and scale
-resistant polypropylene
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, Altella Inc. (Albuquerque, NM) is manufacturing this technology under the Altellarain trade name.
and on the other side for condensing freshwater. The cooling from the evaporation helps water condensate
on the dividing wall, while the energy from the condensing vapor, now turned to droplets, passes back to the evaporation
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.
Desalination
Desalination, desalinization, or desalinisation refers to any of several processes that remove some amount of salt and other minerals from saline water...
technology developed at Arizona State University
Arizona State University
Arizona State University is a public research university located in the Phoenix Metropolitan Area of the State of Arizona...
(Tempe) as an energy efficient
Efficient energy use
Efficient energy use, sometimes simply called energy efficiency, is the goal of efforts to reduce the amount of energy required to provide products and services. For example, insulating a home allows a building to use less heating and cooling energy to achieve and maintain a comfortable temperature...
tool for freshwater procurement and saline waste stream management. The system has relative low installment costs and low operation and maintenance requirements.
The process uses air as a carrier gas that transfers water vapor
Vapor
A vapor or vapour is a substance in the gas phase at a temperature lower than its critical point....
from ascending evaporative channels to adjacent, descending dew
Dew
[Image:Dew on a flower.jpg|right|220px|thumb|Some dew on an iris in Sequoia National Park]]Dew is water in the form of droplets that appears on thin, exposed objects in the morning or evening...
-forming channels. Thermal communication across the channel boundaries allows the evaporative energy requirement to be fully satisfied by the heat of fusion on the dew forming side. A small pressure difference is held so that the condensing cooler air is kept on the cool side by a slight pressure difference.
Near atmospheric
Atmospheric pressure
Atmospheric pressure is the force per unit area exerted into a surface by the weight of air above that surface in the atmosphere of Earth . In most circumstances atmospheric pressure is closely approximated by the hydrostatic pressure caused by the weight of air above the measurement point...
operation permits corrosion
Corrosion
Corrosion is the disintegration of an engineered material into its constituent atoms due to chemical reactions with its surroundings. In the most common use of the word, this means electrochemical oxidation of metals in reaction with an oxidant such as oxygen...
free and scale
Fouling
Fouling refers to the accumulation of unwanted material on solid surfaces, most often in an aquatic environment. The fouling material can consist of either living organisms or a non-living substance...
-resistant polypropylene
Polypropylene
Polypropylene , also known as polypropene, is a thermoplastic polymer used in a wide variety of applications including packaging, textiles , stationery, plastic parts and reusable containers of various types, laboratory equipment, loudspeakers, automotive components, and polymer banknotes...
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, Altella Inc. (Albuquerque, NM) is manufacturing this technology under the Altellarain trade name.
Detailed process
According to the Bureau of Reclamation, a branch of the US Department of Interior, this process uses simple corrugated plastic tanks with many "DewVaporation columns" inserted in each tank. 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 condensate
Condensation
Condensation is the change of the physical state of matter from gaseous phase into liquid phase, and is the reverse of vaporization. When the transition happens from the gaseous phase into the solid phase directly, the change is called deposition....
on the dividing wall, while the energy from the condensing vapor, now turned to droplets, passes back to the evaporation
Evaporation
Evaporation is a type of vaporization of a liquid that occurs only on the surface of a liquid. The other type of vaporization is boiling, which, instead, occurs on the entire mass of the liquid....
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.
External links
- Solar Desalination using Dewvaporation
- Seawater desalination using Dewvaporation technique: theoretical development and design evolution
- Seawater desalination using Dewvaporation technique: experimental and enhancement work with economic analysis
- Dewvaporation Desalination 5,000-Gallon-Per-Day Pilot Plant
- Brackish and seawater desalination using a 20 ft2 dewvaporation tower
See also
- Heat of evaporation
- DesalinationDesalinationDesalination, desalinization, or desalinisation refers to any of several processes that remove some amount of salt and other minerals from saline water...
- Heat transferHeat transferHeat transfer is a discipline of thermal engineering that concerns the exchange of thermal energy from one physical system to another. Heat transfer is classified into various mechanisms, such as heat conduction, convection, thermal radiation, and phase-change transfer...