A comprehensive review on recent developments, applications and future aspects of heat pipe-assisted solar collectors

Solar energy offers a sustainable solution to address the increasing energy demand and environmental concerns in both industrial and domestic applications. To enhance the efficiency of solar collectors, researchers have integrated heat pipes, which are passive devices for effectively transferring heat to a working fluid. This integration has a wide range of applications for solar thermal collectors, including water and space heating, drying processes, and desalination. Conventional solar collectors have limitations in high-temperature applications. When heat pipes are integrated with these collectors, they have demonstrated a higher temperature range and improved performance. This paper presents a comprehensive review of the various techniques and innovations adopted by researchers over the last few decades to maximize the thermal performance of heat pipe solar collectors (HPSC). The review begins by covering the fundamental concept and working principle of heat pipes. Heat pipes are sealed copper tubes with an inner wick structure and a small amount of working fluid. Researchers have explored several techniques and innovations to enhance the thermal performance of HPSC. These include optimizing geometrical parameters such as length, diameter, and orientation of heat pipes to maximize heat transfer. Improvements in wick structure design and the selection of working fluids have also been investigated to enhance heat transfer efficiency. This review provides an overview of the techniques and innovations employed by researchers to enhance the efficiency of heat pipe solar collectors. By addressing the identified research gaps, further advancements can be achieved in maximizing the thermal performance of HPSC, leading to more efficient utilization of solar energy.