Evacuated Vacuum Tubes

These Evacuated Vacuum Tubes are made from low emissivity borosilicate glass (glass with low iron content that has superior durability and heat resistance ) with an all-glass seal and they employ AL/N on AL selective coating, which enables the use of the whole solar energy spectrum to generate heat; this produces greater thermal efficiency in bright sunshine but also produces high efficiency in overcast or diffuse sunlight conditions. Further, the tubes are evacuated and have a barium getter which changes color from silver to white if a tubea s vacuum has been compromised.
Evacuated-tube collectors can achieve extremely high temperatures (170A F to 350A F), making them more appropriate for cooling applications and commercial and industrial application. The collectors are usually made of parallel rows of transparent glass tubes. Each tube contains a glass outer tube and metal absorber tube attached to a fin. The fin is covered with a coating that absorbs solar energy well, but which inhibits radiative heat loss. Air is removed, or evacuated, from the space between the two glass tubes to form a vacuum, which eliminates conductive and convective heat loss.