Vacuum cavity parabolic trough collector

Abstract

Without frequent cleaning, dust accumulation on parabolic trough collectors can lead to significant degradation of the performance of trough collectors over time. Owing to the nature of the trough profile and the presence of the receiving tube in the middle of the trough, automatic cleaning has not been a feasible option. The problem of dust accumulation is of particular interest in the Middle East/North African (MENA) region with the high frequency of dusty days throughout the year. This paper presents a thermal numerical analysis of a novel vacuum cavity parabolic trough collector (VCPTC) in which the top and the sides of the trough were covered with borosilicate sheets and a vacuum was assumed inside the cavity. The typical vacuum tube used in conventional troughs was replaced by a bare stainless steel pipe with selective coating. The new trough with its flat top surface should now be much easier to clean with an automatic cleaning machine. This paper compares the performance of a conventional trough with the new VCPTC in terms of overall heat loss. The results have shown that the VCPTC has slightly outperformed the conventional trough.