Performance evaluation and nanofluid using capability study of a solar parabolic trough collector

The aim of present work is to prepare a standard pilot of trough collector to investigate the ways of its performance enhancement. In this paper, a pilot of trough collector was designed and manufactured in a simple way with a 0.7 m width and 2 m in height reflector, which was made of steel mirror. The design, construction procedure and the new shape of receiver coupling are defined by details in the manuscript. The transient response and the optical and thermal performances of the collector were compared using four kinds of receivers: a black painted vacuumed steel tube, a copper bare tube with black chrome coating, a glass enveloped non-evacuated copper tube with black chrome coating, and a vacuumed copper tube with black chrome coating. Then 0.2% and 0.3% carbon nanotube/oil based nanofluids were prepared as working fluid and tested in the pilot with the black chrome coated vacuumed copper absorber tube. All the operating conditions were considered according to ASHRAE Standard 93 (2010) in all steps of test procedure. The results show that the global efficiency of vacuumed tube is averagely 11% higher than the bare tube efficiency, which is in good agreement with the previous works. Also, the nanofluid shows high thermal potential for further and more complete examinations. At last, a model of global efficiency is curve fitted for present prototype and compared with the previous models.