Numerical Investigation of Array Impingement Heat Transfer on the Target With Advanced Pin Fins

2021 ◽  
Author(s):  
Tao Guo ◽  
Yun-Peng Ben ◽  
Yu-Chao Liu ◽  
Cun-Liang Liu ◽  
Hui-Ren Zhu
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Performance ◽  
Hole Diameter ◽  
Transfer Performance ◽  
Target Plate ◽  
Enhancement Of Heat Transfer ◽  
Pin Fin ◽  
Plate Spacing ◽  
Impingement Heat Transfer ◽  
Pin Fins

Abstract The paper proposes a technique of using advanced pin fins on a target plate to improve the impingement heat transfer performance in an array impingement cooling system. The initial shape of the advanced pin fin is a frustum of a cone. In order to enhance heat transfer and reduce flow resistance, the upper and lower sharp edges of the frustum of a cone are rounded. There are arrays of film holes on the target plate, and the influence of the crossflow is not considered. The flow and heat transfer characteristics of the array impingement flat plate and advanced pin fin plate were studied by numerical simulation. During the numerical simulation, the Reynolds number was varied from 2000 to 19500, the jet-to-plate spacing Z/d from 3 to 6 (d = 0.50mm) and the jet hole diameter d is 0.50 mm, 0.75 mm and 1.00 mm respectively. The results show that the averaged Nusselt number values for the advanced pin fin target plate showed an increase ranging from 15% to 20% over those for the flat target plate, It is generally considered that the enhancement of heat transfer is mainly due to the enhancement of fluid disturbance by the pin fins. However, by changing the size of the pin fins, it is found that the enhancement of heat transfer is mainly caused by the increase of heat transfer area, and the influence of enhancing the disturbance is not significant. The pressure loss is little higher than that of the flat plate. The averaged Nusselt number values for the advanced pin fin target plate decreases with the increase of the jet-to-plate spacing, and increases with the increase of Reynolds number. At the same mass flow rate, the averaged heat transfer performance of the pin fin target plate decreases with the increase of jet hole diameter, and the results show that the averaged heat transfer performance of 0.5mm jet hole diameter is the best.

Jet Impingement Heat Transfer in Narrow Channels With Different Pin Fin Configurations on Target Surfaces

2018 ◽  
Vol 140 (7) ◽  
Author(s):  
Yu Rao
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Performance ◽  
Jet Impingement ◽  
Transfer Performance ◽  
Heat Transfer Characteristics ◽  
Narrow Channels ◽  
Pin Fin ◽  
Impingement Heat Transfer ◽  
Pin Fins ◽  
Full Height

A comparative experimental and numerical study has been done on multiple-jet impingement heat transfer in narrow channels with different pin fin configurations on the target surfaces. Three different target plates including a flat plate, a plate with full-height pin fins, and another plate with miniature pin fins are investigated in the jet impingement cooling systems comparatively. The experiments were done under maximum cross flow scheme for the jet Reynolds numbers from 15,000 to 30,000. Narrow jet impingement spacing is kept the same as 1.5 times jet diameter for all the target plates. In the experiments, detailed jet impingement heat transfer characteristics on the flat plate and the full-height pin-fin plate were obtained by using the transient liquid crystal thermography technique, and additionally steady experiments were done to obtain the overall heat transfer performance of the jet impingement systems with all the three different target plates, which accounts for the heat transfer contribution from the pin fins' surface. Significant overall jet impingement heat transfer enhancement can be obtained with full-height pin-fin roughened surfaces with appreciable pressure loss; however, with miniature pin fins on the target plate, the jet impingement overall heat transfer performance can be remarkably improved with negligible pressure loss penalty. Furthermore, three-dimensional (3D) computational fluid dynamics (CFD) analysis was done to analyze the detailed flow structure and heat transfer characteristics in the jet impingement systems with different pin fin configurations.

An Experimental Investigation of Impingement Heat Transfer in Narrow Space With Full-Height Pin Fins

2016 ◽  
Author(s):  
Yu Rao ◽  
Chaoyi Wan ◽  
Yuyang Liu ◽  
Jiang Qin
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Reynolds Numbers ◽  
Target Plate ◽  
Pin Fin ◽  
Impingement Heat Transfer ◽  
Pin Fins ◽  
Narrow Space ◽  
Pin Fin Arrays ◽  
Full Height

An experimental study has been conducted on multiple-jet impingement heat transfer in a narrow space with full-height pin fins under maximum cross flow scheme. Transient liquid crystal thermography method has been used to obtain the detailed impingement heat transfer distribution for the Reynolds numbers from 15,000 to 30,000. The experimental study shows that the spanwisely-averaged Nusselt number ratio Nu/(Re0.8 Pr1/3) is almost independent of Reynolds numbers, and the full-height pin-fin arrays can slightly improve the average Nusselt number on the endwall of the target plate by about 5.0%, and increase the pressure loss by up to about 17.9%. It is also found that heat transfer uniformity is also improved on the endwall of the target plate with pin fin arrays.

Effects of Al2O3-Water Nanofluid and Angular Orientation on Entropy Generation and Convective Heat Transfer of an Elliptical Micro-Pin-Fin Heat Sink

2014 ◽  
Author(s):  
Husam Rajab ◽  
Da Yin ◽  
Hongbin Ma
Keyword(s):  
Heat Transfer ◽  
Entropy Generation ◽  
Heat Sink ◽  
Heat Transfer Performance ◽  
Volume Fraction ◽  
Al2o3 Nanoparticles ◽  
Transfer Performance ◽  
Enhancement Of Heat Transfer ◽  
Pin Fin ◽  
Prandtl Numbers

This paper presents an investigation of the effect of nanofluid on the heat transfer performance in an elliptical micro-pin-fin heat sink including the influence of entropy generation and pin orientation. The orientation angle of pins is decreased with the number of pins in the array with a 90 degree angle for the first pin and a 0 degree angle for the last pin. To study the flow and heat transfer behaviors in a micro-pin-fin heat sink, steady Navier-Stokes and energy equations were discretized using a finite volume approach and were solved iteratively. Deionized (DI) water was used as a base coolant fluid while aluminum oxide (Al2O3) nanoparticles were used in the present study with mean diameters of 41.6 nm. The results showed that (1) changing the angular orientation of pins can cause significant enhancement in heat transfer, (2) a significant enhancement of heat transfer can be attained in the system due to the suspension of Al2O3 nanoparticles in the base fluid in comparison with pure water, (3) enhancement of heat transfer is intensified with increasing volume fraction of nanoparticles and Reynolds and Prandtl numbers, (4) increasing volume fraction of nanoparticles, which is responsible for higher heat transfer performance, leads to a higher pressure drop, (5) using nanofluids as coolant can cause lower heat transfer entropy generation due to their high thermal properties, and (6) with increasing volume fraction and Reynolds and Prandtl numbers, overall entropy generation rate decreases.

An Experimental Study of Transitional Flow Friction and Heat Transfer Performance of a Channel With Staggered Arrays of Mini-Scale Short Pin Fins

2009 ◽  
Author(s):  
Yu Rao ◽  
Chaoyi Wan ◽  
Shusheng Zang
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Reynolds Number ◽  
Thermal Performance ◽  
Heat Transfer Performance ◽  
Diameter Ratio ◽  
Transitional Flow ◽  
Transfer Performance ◽  
Pin Fin ◽  
Pin Fins

An experimental study was conducted to investigate the friction and heat transfer performance of air transitional flow in a rectangular channel with staggered arrays of short pin fins with transverse spacing-to-diameter of 1.5 and streamwise spacing-to-diameter ratio of 2.5. The friction factor, averaged Nusselt number and the overall thermal performance of the transitional flow have been obtained, and compared with Metzger’s pin fin channel with transverse spacing-to-diameter of 2.5 and streamwise spacing-to-diameter ratio of 2.5. The experimental study has showed that in the Reynolds number range of 1678–8500, the pin fin channel with transverse spacing-to-diameter of 1.5 has a higher convective heat transfer performance, but the enhancement capability decreases with the Reynolds number. For Re <6000, the overall thermal performance of the pin fin channel with transverse spacing-to-diameter of 1.5 is higher than the pin fin channel transverse spacing-to-diameter of 2.5, however for Re >6000 the overall thermal performance of the former is lower than the latter. For both of the pin fin channels, the overall thermal performance gets highest when the flow transition occurs.

Experimental Study on the Heat Transfer Under Impinging Jet Array Using Liquid Crystal Thermograph

2010 ◽  
Author(s):  
Han-Chieh Chiu ◽  
Jer-Huan Jang ◽  
Wei-Mon Yan
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Liquid Crystal ◽  
Heat Transfer Performance ◽  
Target Surface ◽  
Transfer Performance ◽  
Plate Spacing ◽  
Aspect Ratios ◽  
Impingement Heat Transfer ◽  
Elliptical Jet

In this work, the effects of jet geometry and the arrangement of film holes on the target plate on the impinging heat transfer are experimentally investigated in detail. A liquid crystal thermograph technology is employed in this study. The aspect ratios (AR) of elliptical jet with five different values, 4, 2, 1, 0.5, and 0.25, jet Reynolds number ranging from 2000 to 4000, and jet-to-target spacing ranging from 1.5 to 4.5 are considered to investigate impingement heat transfer performance. In addition, three arrangements of film hole on the target plates, named side-, middle- and staggered-types, are tested, respectively. The experimental results show that the Nu increases with the increase of jet Reynolds number. Better heat transfer is noted for the cases with smaller jet-to-plate spacing. For the effect of the arrangement of pores on the target surface, the heat transfer on middle-type plate is more significant than the other two for smaller jet-to-plate spacing. As for the effect of aspect ratio, results indicate that the optimal heat transfer performance is found with circular jet of AR = 1.

A Study on Flow Boiling in Microchannel With Piranha Pin Fin

2015 ◽  
Author(s):  
X. Yu ◽  
C. Woodcock ◽  
Y. Wang ◽  
J. Plawsky ◽  
Y. Peles
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Fluid Flow ◽  
Pressure Drop ◽  
Heat Transfer Performance ◽  
Flow Boiling ◽  
Transfer Performance ◽  
Flow Conditions ◽  
Pin Fin ◽  
Flow And Heat Transfer

In this paper we reported an advanced structure, the Piranha Pin Fin (PPF), for microchannel flow boiling. Fluid flow and heat transfer performance were evaluated in detail with HFE7000 as working fluid. Surface temperature, pressure drop, heat transfer coefficient and critical heat flux (CHF) were experimentally obtained and discussed. Furthermore, microchannels with different PPF geometrical configurations were investigated. At the same time, tests for different flow conditions were conducted and analyzed. It turned out that microchannel with PPF can realize high-heat flux dissipation with reasonable pressure drop. Both flow conditions and PPF configuration played important roles for both fluid flow and heat transfer performance. This study provided useful reference for further PPF design in microchannel for flow boiling.

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