The dependence of thermosyphonic system performance on collector aspect ratio

Abstract

The dependence of a standard thermosyphonic solar system's performance on collector aspect (length to width) ratio is investigated. Numerical simulation of the system's characteristics is conducted for systems with the same overall collector area but three aspect ratios. In all cases, spacing between collector tubes was kept constant to eliminate fin efficiency considerations. The systems were simulated for typical summer and winter days. Results of the investigation reveal that overall performance characteristics (like bulk efficiency or average tank temperature) as well as stratification in the tank and flow rates depend only slightly on the aspect ratio. The practical conclusion is that only economical considerations and not energetical ones should be applied in designing the aspect ratio of a thermosyphonic solar system.