Comparative analysis of heat transfer enhancement using direct current and alternating current corona discharge in pin fin arrays

Corona discharge-produced ionic wind has emerged as a promising area of research for enhancing heat transfer. In contrast to conventional cooling methods, which often require complex geometrical designs and inefficient energy consumption, corona wind induction offers a cost-effective solution with lower energy requirements. This study focuses on investigating the effectiveness of direct and alternating corona discharge in enhancing heat transfer from pin fin arrays of heat sources. Using numerical simulations performed with COMSOL Multiphysics (6.0) and the finite element method (FEM), both DC and AC-sourced corona ionic winds were evaluated at electric field strengths ranging from $V=15kV$ to $V=25kV$. Key parameters examined included the distance arrangement of high voltage electrodes to the pin surface ($A$), pin fin diameter ($D_f$), induced voltage ($V$), depth of corona wind penetration, and the differences between DC and AC corona. The findings revealed a direct relationship between the amount of induced voltage and the diffusion of corona discharge, resulting in significant heat transfer enhancement of up to 66.83 % in turbulent flow at $V=25kV$. Furthermore, direct corona induction exhibited a greater capability to enhance the heat transfer rate in comparison to AC induction. This discrepancy was notably more pronounced under turbulent conditions, registering at $10.02\%$, whereas in the laminar flow regime, the difference amounted to $4.73\%$. In addition, the results show that the implementation of corona wind leads to a significant increase in the Nusselt number, especially within the turbulent flow range, with the use of direct corona wind at a $25kV$ voltage elevating the local Nusselt number value from $29.37$ to $52.18$. The results highlight the effectiveness and advantages of corona wind induction as an energy-efficient solution for tackling heat dissipation challenges in complex geometries.