Comparison of Heat Transfer From Staggered Pin Fin Arrays With Circular, Cubic and Diamond Shaped Elements

Abstract

This study investigates the effects of pin shape of staggered arrays on heat transfer enhancement. Three different pins: circular, cubic, and diamond, are studied. The arrays consists of twelve rows of five columns with geometry configuration of ST/D = 2.5 and SL/D = 2.5, H/D = 1. Tests were conducted at Reynolds number between 12,000 and 19,000. The heat transfer measurement uses a liquid crystal imaging technique combined with a one-dimensional, transient conduction model and a lumped heat-capacitance model. The results reveal that the heat transfer from the cubic pin arrays and diamond pin arrays is higher than that from the circular pin arrays at the same Reynolds number. However, the circular pin arrays provide the lowest pressure loss among the three arrays. Considering the trade-offs between heat transfer and pumping power, the circular pin arrays may still be the better choice as a heat exchanger.

Endwall heat transfer and pressure drop in rectangular channels with attached and detached circular pin-fin array

“…This f versus Re trend is closely relevant to the pin height-todiameter (H/d) ratio that agrees with the correlation reported in [36]. But in the channels with attached pin-fins of H/d < 1.5 [27,34], the f values generally decrease with the increase of Re. A further increase of H/d ratio enlarges the friction and pressure drags inside the pin-fin channels that can lead to the increased f values as Re increases for the pin-fin channels with H/d P 2.5 such as the pin-fin geometries examined by Zukauskas et al [36] and present study.…”

“…As compared in Fig. 6, the comparison of Nu derived by Lyall et al [35] with present Nu at Re = 30,000 yields 7% lower values of present Nu than those reported by Lyall et al [35]; whereas the comparison of present Nu with Nu derived by Chyu et al [34] at Re = 18000 results in 17% lower values of present Nu. These discrepancies can be attributed to differences in channel aspect ratio, pin pitch ratio, experimental setup and boundary conditions.…”

“…For the purpose of validation, Fig. 6 also collects the endwall heat transfer data reported in [27,34,35] for the channels with attached pin-fins which share the similar test configurations with the present study. As compared in Fig.…”

Endwall heat transfer and pressure drop in scale-roughened pin-fin channels

“…These features are widely fitted in the cooling passages at the trailing edge of a gas turbine blade and in the heat sink for cooling of electronic chipsets to enhance the heat transfer. Driven by these cooling applications, a large number of experimental and numerical studies examined heat transfer performances over the pin-fins and endwalls in the pin-fin channels [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. These pin-fins improve heat transfer performances by tripping wakes which enhance fluid mixing but with consequential increase in pressure gradients and friction drag.…”

“…While the aforementioned flow physics generalizes the heat transfer characteristics in a pin-fin channel, the detailed HTE effects vary with the height-to-diameter ratio [5,6] and the shape [7][8][9][10][11] of pins, the arrangement [12,13] and the orientation [14] of pin-arrays and the clearance between endwall and detached pins [15,16]. In view of the endwall heat transfer performance, the staggered diamond pin-fin array with pitch ratios of 1.5-2.5 pin-diameters offers considerable HTE effects; while the elliptical fins provide higher thermal performance factors [13].…”