EVACUATED SOLAR COLLECTOR TUBE

摘要

EVACUATED SOLAR COLLECTOR TUBE A solar energy collector element having an inner tube which carries a heat exchange fluid, an outer glass tube, an evacuated space between the two tubes and a solar selective surface coating in thermal contact with the outer surface of the inner tube. A gas is admitted to the evacuated space for the purpose of degrading the vacuum and limiting the stagnation temperature of the collector element, The gas is selected to exhibit hydrophobic characteristics, to adsorb onto the selective surface coating at temperatures less than a predetermined temperature, to desorb into the evacuated space at temperatures greater than the predetermined temperature but to not adsorb significantly onto the outer glass tube. Collector geometries are proposed which reduce the temperature range over which significant heat losses can occur.