A Review of Heat Transfer Enhancement Techniques in Thermosyphon Solar Water Heating Systems

Interest in transitioning to renewable energy sources, particularly solar energy, has surged due to its clean nature and ability to meet thermal and electric needs while minimizing environmental pollution and global warming risks. Thermosyphon Solar Water Heating Systems (TSWHS) are noted for their efficiency in converting solar radiation to thermal energy. Research primarily focuses on enhancing heat transfer, categorized into active methods utilizing external energy sources - and passive methods, which improve transfer by modifying flow geometry through techniques like fins, twisted tapes, adding a nanofluid, or dual-layer staggered pipes.