Active Heat Transfer Augmentation of Bundle of Tubes by Partial Oscillatory Excitation

Abstract

Numerical analysis of heat transfer from a heated oscillating tube bank in crossflow has been investigated for an aligned array of tubes using the Open Source Field Operation and Manipulation C++ library. The heat exchanger constructed based on the present idea of tube oscillation is called the oscillating heat exchanger. The verification/validation procedure was performed for four benchmark cases. The effect of several combinations of oscillating frequencies and amplitudes on the mean Nusselt number and the drag coefficient was investigated at the Reynolds number of 100. The results of simulation showed that, by vibrating the first column of tubes in the lock-in region, approximately 25% augmentation in the overall Nusselt number was obtained. Also, it is computed that the effect of oscillation of the first column on the heat transfer enhancement is remarkable in low-amplitude motion, the amplitude of oscillation is important in the off-lock-in frequencies, and the maximum Nusselt number is independent of the amplitude of oscillation. To reach the maximum possible heat transfer removal with low construction costs, it is recommended to oscillate the first column with low amplitude, but the frequency should be selected inside the lock-in region.