Solar Still


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solar still

[′sō·lər ′stil]
(chemical engineering)
A device for evaporating seawater, in which water is confined in one or more shallow pools, over which is placed a roof-shaped transparent cover made of glass or plastic film; the sun's heat evaporates the water, leaving behind a residue of salt; the vapor from the evaporated water condenses on the surface of the cover and trickles down into gutters, which thus collect fresh water.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Solar Still

 

a water-distilling device whose energy source is solar radiation.

The most commonly used solar stills are based on the principle of the “hot box” (seeSOLAR HEATER). Such stills are simple in design, are comparatively inexpensive, and do not require maintenance by skilled personnel. This type of still (Figure 1) is made in the form of a thermally insulated basin whose interior is blackened. The basin contains the salt water that is to be distilled. The upper part of the still is covered by a transparent material, such as glass, a polymeric film, or organic glass. The sun’s rays pass through the transparent cover and heat the water, thereby causing it to evaporate. The temperature of the transparent cover is close to that of the surrounding air. When the water vapor comes into contact with the cover, it condenses on the cover’s inside surface. The condensed fresh water then trickles down into collecting troughs. The solar still is usually oriented toward the south. In choosing the optimal slope of the still’s transparent surface, the sun’s altitude above the horizon is taken into account, as is the need to permit the condensate to flow into the collecting troughs. The amount of fresh water produced by such a still depends primarily on the intensity of the solar radiation and on the airtightness of the device; the output of the still is 3–5 liters/m2-day.

Figure 1. Schematic of a solar still of the hot-box type: (1) basin containing salt water, (2) air-vapor mixture, (3) transparent cover, (4) condensate, (5) heat-insulating wall of box; the arrows indicate the sun’s rays

Solar stills have found application in areas where fresh water is in short supply but adequate amounts of salt water (for example, seawater) are available. Inflatable solar stills have been used successfully throughout the world by the crews of aircraft and oceangoing vessels in emergency situations on the open sea.

REFERENCES

Brdlik, P. M. “Ispytanie i raschet solnechnykh opresnitel’nykh ustanovok.” In collection 1: ispol’zovanie solnechnoi energii. Moscow, 1957.
Bairamov, R. “Sravnitel’nye ispytaniia solnechnykh opresnitelei par-nikovogo tipa.” Izv. AN Turkm. SSR.: Ser. fiziko-tekhnicheskikh, khimicheskikh i geologicheskikh nauk, 1964, no. 1.
Sovremennye metody opresneniia vody. Ashkhabad, 1967.

P. M. BRDLIK

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
"With a solar still the size of a mini fridge, we estimate that we can generate 10 to 20 liters of clean water every single day."
The desalination can be done in various methods such as reverse osmosis, multi flash method and solar still. Amond these solar still desalination is the best method which is working based on renewable energy a source which is not harming the environment and freely available energy source.
To explore alternative ways of purifying water, students used a solar still to learn about the distillation process and the states of matter.
Single basin solar still were fabricated and tested under field condition at the testing field of the Mechanical Engineering department, Adhiyamaan College of Engineering, Hosur, Tamilnadu, India.
Box 799 Longmont, CO 80501 (866) 253-7087 ($12 Solar Still by W.R.
With a solar still, polluted, brackish or otherwise marginal water and even salt water can be converted to distilled water.
The first modern solar still was built in Las Salinas, Chile, in 1872, by Charles Wilson.
Low-cost solar stills generating water via evaporation, largely fabricated with whatever black and clear plastic cases and tubing a community might have on hand, are gradually closing the safe water gap for coastal residents in the developing world.