The enhancement effect of corona discharge on natural convection heat transfer in triangular channels

A numerical research was conducted to investigate the effect of corona discharge on natural convection heat transfer in a triangular channel. The channel side walls were isothermal, the lower wall was adiabatic, and the fluid was air at the atmospheric pressure. The electric field was generated by a positive corona discharge from a charged wire electrode located at the center of the channel. The governing equations of the electric and flow fields were solved by a finite-volume technique. Three cases were considered: (1) natural convection; (2) corona-induced convection; and (3) combined natural and corona-induced convection. The computations encompassed Rayleigh numbers from 3,737 to 37,377 and applied voltages from 7 to 9 kV in the laminar regime. Computations for the applied voltage of 7.5 kV indicated that the heat transfer was enhanced from Nu/Nu(0) = 1.01 to 1.04, or 1-4%, for different values of Ra. The enhancement at Ra = 3,737 and the applied voltage of 7 to 9 W was Nu/Nu(0) = 1.01 to 1.40, or 1-40%.