Finding a low cost energy multi-DBD plasma actuator for natural heat transfer enhancement in a vertical duct

Abstract

Current study is focused on numerically finding an optimal active control system to augment the natural heat transfer through a vertical duct. This control system consists of a multiple set of wall embedded Dielectric-Barrier-Discharge (DBD) plasma actuators, which inherently consume the electric power to push the momentum near their embedded electrodes. On the other hand, in current study which the vertical duct is exposed to a constant heat flux on one side, the enhancement of natural convection by wall momentum pushes cause the upward flow to recirculate through the channel and consequently decelerates the mass flow rate to give higher outflow temperatures. The numerical simulation deals with the effects of variable parameters such as Rayleigh number, number of DBD actuators, and the vertical DBD arrangements. A descriptive enhancement ratio: The ratio of the average Nusselt number affected by plasma actuation to the average Nusselt number without DBD control, is used to evaluate capability of the heat transfer augmentation. The numerical results showed that the enhancement ratio in the presence of the DBD actuator reaches to about 2.75. However, the results briefly show the sensitivity of the heat transfer enhancement to the Number of the actuators and their arrangement. As the main goal and the final step, the overall thermal efficiency (OTE) as a parameter expressed to further clarify the performance of plasma actuator system from the perspective of energy consumption is defined as the rate of the augmented heat transfer by the DBD actuator to the actuation electric power consumption. Also, it can be realized that by increasing the number of DBD actuators from 1 to 4, the La increases, and over 4 it is constant. The results show that the case N = 4 can be a candidate for the optimum design.