HEAT TRANSFER ENHANCEMENT IN PIPE FLOW WITH DOWNSTREAM PULSATION

Document Type : Original Article

Authors

1 Mech. Eng. Dept., Shoubra Faculty of Engineering, Banha University.

2 MSC Student.

Abstract

ABSTRACT:
Experiments were carried out to investigate the heat transfer characteristics for turbulent flow through pipes with downstream pulsation. Measurements were conducted in a horizontal brass pipe of 40 mm inner diameter and 3000 mm long under uniform heat flux condition, with air as a working fluid. The pulsating frequency was ranged from 45 to 145 Hz and Reynolds number was varied from 27900 to 58900. The results show that an enhancement in heat transfer is obtained for the pulsated flow for different values of both Reynolds number and pulsating frequency. The rate of enhancement decreases as the pulsation frequency increases. The maximum enhancement of the relative average Nusselt number (about 84.5 %) is obtained with Re = 55500 and f = 45 Hz, while the minimum enhancement (about 17%) is obtained at Re =42500 and f = 145 Hz. As Reynolds number increases from 27900 to 35800, the relative average Nusslet number increases and peaks at Reynolds of 35800 and pulsation frequency of 93.3. As Reynolds number increases further from 35800 to 42500, a reduction in the relative average Nusslet number is obtained for the whole studied range of the pulsation frequencies. While as Reynolds number increases further (42500 ≤Re≤ 58900), the relative average Nusselt number increases again with about 84.5% maximum enhancement. The present experimental data for the relative average Nusselt number enhancement ratio were correlated in terms of Reynolds number and the dimensionless frequency.  

Keywords