Mr. Riazi et J. Razavi, PERFORMANCE OF POLYPROPYLENE AND STEEL TUBES IN SOLAR WATER-HEATERS WITH NATURAL CIRCULATION, Energy sources, 19(2), 1997, pp. 147-152
Performance of solar water heaters in thermosyphonic flow with polypro
pylene and steel tubes was studied experimentally. An experimental app
aratus consisting of 36 south-facing parallel tubes was designed and b
uilt especially for this study. Experiments were performed at Sharif U
niversity of Technology in Tehran during July-August 1994 from 0900 to
1700, when the ambient temperature varied from 29 to 36 degrees C. Ov
erall, 30 experiments were conducted for both types of tubes. At first
, it was found that the best collector slope for both types of tubes w
as 36 degrees and it is independent of tube type. Generally, it was fo
und that polypropylene tubes under similar conditions can increase wat
er temperature by 10 degrees C more than steel tubes. Based on the res
ults shown in this study, use of polypropylene tubes in solar water he
ating systems is recommended.