Effect of cylinder proximity to the wall on channel flow heat transfer enhancement

Abstract

Heat-transfer enhancement in a uniformly heated slot mini-channel due to vortices shed from an adiabatic circular cylinder is numerically investigated. The effects of gap spacing between the cylinder and bottom wall on wall heat transfer and pressure drop are systemically studied. Numerical simulations are performed at Re = 100, 0.1 Pr 10and a blockage ratio of D/H = 1/3. Results within the thermally developing flow region show heat transfer augmentation compared to the plane channel. It was found that when the obstacle is placed in the middle of the duct, maximum heat transfer enhancement from channel walls is achieved. Displacement of circular cylinder towards the bottom wall leads to the suppression of the vortex shedding, the establishment of a steady flow and a reduction of both wall heat transfer and pressure drop. Performance analysis indicates that the proposed heat transfer enhancement mechanism is beneficial for low-Prandtl-number fluids.

Heat and fluid flow characteristics of a rectangular channel with a small diameter circular cylinder as vortex generator

“…They found that the cylinder wake altered significantly the thermal boundary layer, and wall heat transfer was increased when the temperature distributions became steeper. Mohesn et al [24] studied the effect of the cylinder which is close to the wall on heat transfer enhancement in channel flow. The results showed that the velocity and temperature distributions gradually tended to steady, the heat transfer and pressure drop gradually decreased when the distance from the cylinder to the bottom wall gradually became small.…”

Benefits of spanwise gaps in cylindrical vortex generators for conjugate heat transfer enhancement in micro-channels

“…Indeed, reduction in chips size is a real challenge for designing efficient cooling systems with limited space in which to reject generated heat [1][2][3][4]. One of the promising systems by which high performance heat rejection can be achieved is micro and mini-scale systems, such as micro-channel heat exchangers and heat sinks [5][6][7][8][9]. They are different from traditional channels, and can be classified according to their associated hydraulic diameters, D h , [10][11][12].…”

“…The present work is focused on cylindrical or rib-based structures, which have received some recent attention. A 2D numerical study by Cheraghi et al [6] investigated the impact of the position of an adiabatic cylinder in a uniform micro-channel. They used fixed heat flux applied to the wall sides, Reynolds number of 100 and the Prandtl number ranged from 0.1 to 1.…”

Heat transfer enhancement in a micro-channel cooling system using cylindrical vortex generators

“…A 2D numerical study utilized smooth channel with fixed heat flux applied to the wall sides having an adiabatic cylinder inside which was perpendicular to the laminar flow direction with Reynolds number of 100and Prandtl number ranging from 0.1 to 1 [3]. The authors have investigated the influence of the distance between the base and the top of the channel as they This is the accepted manuscript of an article published in International Communications in Heat and Mass Transfer.…”

“…Therefore there is a need to improve cooling systems by decreasing their size and weight to micro-and mini-scale systems, such as micro-channel heat exchangers and heat sinks [2], while simultaneously increasing the efficiency to meet this development [3]. Mini-and micro-channels are different from traditional channels, and can be classified according to their associated hydraulic diameters, Dh, [4][5][6] as presented in table 1.…”