Brief Introduction of EGST
Evacuated Glass Solar Tubes (EGST) is the key components of Solar Water Heating Systems. The EGST have the best possible insulation, a vacuum jacket, which allows sunlight to pass through freely but stops the thermal heat transferring back out. They feature high efficiency, low heat loss and are guaranteed for ten years. The use of evacuated glass solar tube technology appears to be one of the significant developments in the solar industry, world wide.
Configuration of the Evacuated Glass Solar Tubes
Each of the EGST is configured by two concentric borosilicate glass tubes, the outside surface of the inner tube is coated, with the lastest magnetron sputtering Hi-Tech, layers of selective coatings of AL-N with an Al base coating on the inside of the inner tube. The jacket between the exterior glass tube and the inner glass tube is evacuated and permanently sealed off to form the best possible insulation, which allows sunlight to penetrate, but prevents heat loss. In order to maintain vacuum in the jacket between the two tubular glass tubes, a barium getter (gas absorbent) is used inside the bottom of the cover tube. During manufacturing this getter is exposed briefly to high frequency magnetic fields, causing rapid high temperatures and coating the bottom of the evacuated tube with a pure layer of barium. This barium layer actively absorbs any CO, CO2, N2, O2, H2O and H2 from the tube during operation, thus helping the vacuum tube sustain a long lifetime.The barium layer also provides a clear visual indicator of the vacuum status. The silver coloured barium layer will turn white if the vacuum is ever lost. This makes it easy to determine whether or not a tube is in good condition. See picture below.
The efficiency of a evacuated water heater is dependent upon a number of factors, one important one being the level of evacuated radiation ( insolation ) in your region. To learn more about insolation and the average values for your area click here. |
