Worldwide, people live in harsh climates or arid regions where there is very little clean drinking water and available. Eth Zürich researchers have developed a condenser for use in countries where water is being procured. This is the first zero energy solution that harvests water directly from the atmosphere throughout the 24-hour daily cycle.
The device uses an automatic cooling surface and a special radiation shield. Atmospheric water harvesting systems usually require high energy entry or rely on passive technologies that exploit the change in temperature between day and night. Other available technologies include dew collection sheets that can only extract water at night as the sun must heat the sheet during the possible condensation day. The new technology of Eth Zurich has a specially coated glass that reflects solar radiation and radiates its heat through the atmosphere.
On the underside of this window, the air vapor of the air condenses in water. The researchers say that the process used by their technology is the same process that occurs on poorly isolated windows in winter. Scientists covered glass with a special polymer and silver layers. The special coating causes infrared radiation to a specific wavele length window on the outdoor space without absorption by the atmosphere or the reflection in the pane.
Another key element of the system design is a cone-shaped radiation shield that deviates the thermal radiation of the atmosphere to protect the glass of solar radiation. The shield allows the device to radiate heat outwards for self-cooling you completely passively. The researchers have discovered that the new technology can produce at least twice more water per day and by zone than the best current passive technologies that use leaves.
The researchers created a small pilot system with a diameter of the window of 10 centimeters and found that he delivered 4.6 milliliters of water per day under real conditions. A large device with larger windows would produce more water. Under ideal conditions, the device could harvest up to 0.53 water decalters per square meter of the surface of the pane per hour. The maximum theoretical value of the harvest is 0.6 decalters per hour, which is physically impossible to exceed. Project scientists note that several systems can be placed together to harvest more water.
