Experimental and theoretical results showed that with the
increase of water temperature in the tank of a thermosyphon
domestic solar water heating systems, the outlet water temperature
is increased. Results by simulations showed that the collectortank
height difference and the thermal emissivity of absorbers had
significant effects on the freeze protection of collectors in terms of
outlet water temperature. Comparative studies have made on the
thermal performance of water-in-glass evacuated tube solar water
heating systems with different collector tilt angles by Runsheng