Effect of Air Bubbles on Heat Transfer Using a Helical Coil: A Review

Abstract

This review paper discusses the important role of helical coils in heat transfer applications, focusing attention on their distinct geometry and high thermal performance. Helical coils, with tapering shape and continuously varying diameter, offer numerous advantages over their straight and helical counterparts concerning fluid dynamics, heat transfer rates, and efficiency. This paper explores the underlying principles of heat transfer in helical coils and addresses how fluid flow behavior, promotion of turbulence, and generation of secondary circulations enhance the rate of heat transfer. Advantages of helical coils, which include the increased mixing of fluids, enhanced surface area for heat exchange, and reduced fouling, have led to its usage in various applications such as in heat exchangers, solar thermal systems, biomedical devices, refrigeration, and industrial processes. It further explains how air bubbles impact the transfer of heat in two-phase flow systems and demonstrates that air bubbles improve convective heat transfer through the generation of turbulence and effective distribution of heat. Finally, it ends with an underlining fact that Helical coils play a vital role in optimizing the transfer of heat and its efficiency especially when the concerned parameters include minimal space availability, high thermal efficiency, and minimum maintenance.