Mixed and Forced Convection Heat Transfer in Baffled Channels: A Brief Review

Improving heat transfer in thermal systems has become a focus of many research studies due to the critical need for efficient waste of residual heat. The regulation of heat transfer between components in thermal systems has a direct impact on their efficiency and performance. As a result, effective heat management is critical to improving the efficiency of thermal systems and extending the life of their components. It should be noticed that baffles are important structural components widely used in various industrial applications like heat exchangers, solar collectors, electronic cooling, etc. In addition, baffles enhance fluid mixing and heat transfer behaviors. Most industrial systems do not operate in a steady state. In particular, transient phases occur during start-up and shut-down or during the control phase of controlled systems. Thus, in laminar flow, baffles induce flow unsteadiness or help the flow to bifurcate from a steady state to an unsteady flow. This paper treated the effects of different baffle shapes incorporated in channels on heat transfer rate, efficiency and friction factor in mixed and forced convection cases. Various experimental and numerical studies have been carried out on this topic to examine heat transfer enhancement compared to the flow energy. It was noticed that increasing the Reynolds number, blockage ratio and decreasing the Grashof number can achieve an increase in heat transfer. The maximum heat transfer enhancement was obtained for higher blockage ratio and higher Reynolds number in forced convective flow. The highest heat transfer improvement was obtained for the 45° angled baffles (between 150% and 850%). In mixed convective flow, the highest rate of heat transfer was obtained for transverse baffles (2.8 times compared to a similar channel with no baffles). Finally, This comprehensive review is beneficial for researchers focused on flow and heat transfer applications to use other baffle designs and fluids beyond air.