Enhancement of heat transfer from a flat surface in a channel flow by attachment of rectangular blocks

Abstract

SUMMARYEnhancement of the heat transfer from a #at surface in a channel #ow by attachment of rectangular crosssectional blocks has been investigated as a function of Reynolds number (Re), arrangement of the blocks with respect to the main #ow direction as well as each other, and the numbers (spacing) of the blocks. The channel had a cross-sectional area of 80;160 mm (i.e. an aspect (width-to-height) ratio of 2). Re, based on the hydraulic diameter of the channel (D ) and bulk mean velocity (u), changed in the range of 6670}40000. The blocks were positioned both transverse and parallel with respect to the main #ow direction. The parallel blocks were arranged in both in-line and staggered orientation with respect to each other. The e!ect of the blocks on the #ow pressure drop was also measured. The results indicated that the heat transfer could be enhanced or reduced depending on the spacing between the blocks and their positioning and arrangement. For a given pressure drop, the best heat transfer enhancement by the blocks over that from a smooth surface (without blocks) was obtained when the blocks were positioned parallel to the #ow and arranged in a staggered manner with respect to each other.

Convective heat transfer enhancement in solar air channels

“…It was reported that the rounding of the corrugation peaks resulted in decreases in both Nu and f. Won et al [83] investigated angled rib turbulators with an angle of attack 45 , rib height to hydraulic diameter ratio of 0.078, rib pitch to height ratio of 10, and blockage of 25% for an Re range of 9000e76,000. Sara et al [84] carried out an experimental study to enhance the heat transfer from the flat surface in a flow channel provided with rectangular cross sectional blocks. The blocks were positioning in both the transverse and parallel (inline and staggered) directions with respect to the main flow direction.…”

Experimental Investigation on Heat Transfer Enhancement from a Channel Mounted with Staggered Blocks

“…Increasing the heat transfer surface area by introducing block or obstacles in the flow path is one of the most universal approaches to enhancing heat transfer. Many researchers have investigated heat transfer enhancement in arrays of rectangular blocks [1][2][3][4][5]. Flow over heated blocks simulate electronic components mounted on a printed circuit board.…”

“…To avoid the vibration effect of the pump, it is mounted on a separate stand. Laminar flow is achieved by a flow straightener [2,3] which is provided between the upstream side of the channel and the supply tank. Flow of water to the flow straightener is controlled by a flow control valve.…”

Heat transfer enhancement in oscillatory flow in channel with periodically upper and lower walls mounted obstacles

“…However, this heat transfer enhancement was accompanied by a significant increase in pressure drop. Furthermore, Sara et al (2001a) studied the effect of block arrangement on both heat transfer and pressure drop. The results showed that the heat transfer could be enhanced or reduced depending on the spacing between blocks.…”