Thermal Performance Comparison of a Novel Chevron Collector and Standard Collectors

Quantitative comparison of collector designs plays an important role in the development of solar thermal systems. In this paper, performance comparison of a novel chevron flat plate collector design against two collectors is... [ view full abstract ]

Quantitative comparison of collector designs plays an important role in the development of solar thermal systems. In this paper, performance comparison of a novel chevron flat plate collector design against two collectors is presented. For the tested design, the chevron pattern was on the upper plate of the absorber while the lower plate was a flat aluminum channel. The aim of the investigation was to compare analyze the thermal performance of various collector designs and determine their suitability for solar seawater desalination systems for implementations in Qatar. For the purpose of comparison, two other collectors, i.e. a commercial collector, and a mosaic multichannel collector, were also investigated. The objective was to investigate the behavior of the thermal energy conversion system when the collectors of same size are connected to the same storage system and tested under similar environmental conditions. Outdoor experiments that include measurements of radiation, flow rates, temperatures and wind speeds were carried out. Preliminary investigations focused on the amount of heat collected in the storage system, charge and discharge modes of the system and the influence of load profiles. Satisfactory performances was observed for a morning and evening load draw-off operating mode with a direct stratified thermal storage system. The highest water temperatures obtained were 52°C, 55°C, and 65.5°C for the commercial, mosaic multichannel, and chevron collectors respectively. These results show the superiority of the chevron design. Since the minimum temperatures required for desalination is about 80°C, it can be inferred that the experimental collectors don not provide sufficiently heated water temperatures for effective solar desalination. However, it was noticed during the experiments that changing the arrangement of the chevron collector absorber (e.g. chevron patterns on the upper and lower plates with symmetrical and asymmetrical geometries) has a significant effect on the water flow behavior. Hence, an optimal flow pattern may provide improved collector performance to reach maximum water temperatures suitable for desalination.

Acknowledgements

This research was made possible by a NPRP award NPRP 5-161-2-053 from the Qatar National Research Fund (a member of The Qatar Foundation). The statements made herein are solely the responsibility of the authors.