Forced Convection Heat Transfer Enhancement by Porous Pin Fins in Rectangular Channels

2010 ◽  
Vol 132 (5) ◽  
Author(s):  
Jian Yang ◽  
Min Zeng ◽  
Qiuwang Wang ◽  
Akira Nakayama
Keyword(s):  
Heat Transfer ◽  
Three Dimensional ◽  
Convection Heat Transfer ◽  
Heat Fluxes ◽  
Physical Parameters ◽  
Pore Density ◽  
Pressure Drops ◽  
Pin Fin ◽  
Rectangular Channels ◽  
Pin Fins

The forced convective heat transfer in three-dimensional porous pin fin channels is numerically studied in this paper. The Forchheimer–Brinkman extended Darcy model and two-equation energy model are adopted to describe the flow and heat transfer in porous media. Air and water are employed as the cold fluids and the effects of Reynolds number (Re), pore density (PPI) and pin fin form are studied in detail. The results show that, with proper selection of physical parameters, significant heat transfer enhancements and pressure drop reductions can be achieved simultaneously with porous pin fins and the overall heat transfer performances in porous pin fin channels are much better than those in traditional solid pin fin channels. The effects of pore density are significant. As PPI increases, the pressure drops and heat fluxes in porous pin fin channels increase while the overall heat transfer efficiencies decrease and the maximal overall heat transfer efficiencies are obtained at PPI=20 for both air and water cases. Furthermore, the effects of pin fin form are also remarkable. With the same physical parameters, the overall heat transfer efficiencies in the long elliptic porous pin fin channels are the highest while they are the lowest in the short elliptic porous pin fin channels.

Experimental and Numerical Investigation of Natural Convection Heat Transfer From Horizontal Rectangular Plate Fin Pin Fin Arrays

2020 ◽  
Author(s):  
Sunil V. Dingare ◽  
Narayan K. Sane ◽  
Ratnakar R. Kulkarni
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Natural Convection ◽  
Numerical Model ◽  
Convection Heat Transfer ◽  
Natural Convection Heat Transfer ◽  
Convection Heat ◽  
Pin Fin ◽  
Pin Fins ◽  
Fin Spacing

Abstract Fins are commonly employed for cooling of electronic equipment, compressors, Internal Combustion engines and for heat exchange in various heat exchangers. In short fin (length to height ratio, L/H = 5) arrays used for natural convection cooling, a stagnation zone forms at the central portion and that portion is not effective for carrying away heat. An attempt is made to modify plate fin heat sink geometry (PFHS) by inserting pin fins in the channels formed between plate fins and a plate fin pin fin heat sink (PFPFHS) is constructed to address this issue. An experimental setup is developed to validate numerical model of PFPFHS. The three-dimensional elliptic governing equations were solved using a finite volume based computational fluid dynamics (CFD) code. Fluent 6.3.26, a finite volume flow solver is used for solving the set of governing equations for the present geometry. Cell count based on grid independence and extended domain is used to obtain numerical results. Initially, the numerical model is validated for PFHS cases reported in the literature. After obtaining a good agreement with results from the literature, the numerical model for PFHS is modified for PFPFHS and used to carry out systematic parametric study of PFPFHS to analyze the effects of parameters like fin spacing, fin height, pin fin diameter, number of pin fins and temperature difference between fin array and surroundings on natural convection heat transfer from PFPFHS. It is observed that it is impossible to obtain optimum performance in terms of overall heat transfer by only concentrating on one or two parameters. The interactions among all the design parameters must be considered. This thesis presents Experimental and Numerical study of natural convection heat transfer from horizontal rectangular plate fin and plate fin pin fin arrays. The parameters of study are fin spacing, temperature difference between the fin surface and ambient air, fin height, pin fin diameter, number of pin fins and method of positioning pin fins in the fin channel. Experimental set up is validated with horizontal plate standard correlations. Results are generated in the form of variation in average heat transfer coefficient (ha), base heat transfer coefficient (hb), average Nusselt number (Nua) and base Nusselt number (Nub). Total 512 cases are studied numerically and finally an attempt is made to correlate the Nusselt Number (Nu), Rayleigh Number (Ra), increase in percentage by inserting pin fins (% Area), ratios like spacing to height (S/H) and L/H obtained in the present study.

Effect of Rotation on Heat Transfer in Narrow Rectangular Cooling Channels (AR = 8:1 and 4:1) With Pin-Fins

2003 ◽  
Author(s):  
Lesley M. Wright ◽  
Eungsuk Lee ◽  
Je-Chin Han
Keyword(s):  
Heat Transfer ◽  
Aspect Ratio ◽  
Rotation Number ◽  
Rectangular Channel ◽  
Density Ratio ◽  
Pin Fin ◽  
Aspect Ratios ◽  
Rectangular Channels ◽  
Smooth Channel ◽  
Pin Fins

The effect of rotation on smooth narrow rectangular channels and narrow rectangular channels with pin-fins is investigated in this study. Pin-fins are commonly used in the narrow sections within the trailing edge of the turbine blade; the pin-fins act as turbulators to enhance internal cooling while providing structural support in this narrow section of the blade. The rectangular channel is oriented at 150° with respect to the plane of rotation, and the focus of the study involves narrow channels with aspect ratios of 4:1 and 8:1. The enhancement due to both conducting (copper) pin-fins and non-conducting (plexi-glass) pins is investigated. Due to the varying aspect ratio of the channel, the height-to-diameter ratio (hp/Dp) of the pins varies from two, for an aspect ratio of 4:1, to unity, for an aspect ratio of 8:1. A staggered array of pins with uniform streamwise and spanwise spacing (xp/Dp = sp/Dp = 2.0) is studied. With this array, 42 pin-fins are used, giving a projected surface density of 3.5 pins/in2 (0.543 pins/cm2), for the leading or trailing surfaces. The range of flow parameters include Reynolds number (ReDh = 5000–20000), rotation number (Ro = 0.0–0.302), and inlet coolant-to-wall density ratio (Δρ/ρ = 0.12). Heat transfer in a stationary pin-fin channel can be enhanced up to 3.8 times that of a smooth channel. Rotation enhances the heat transferred from the pin-fin channels 1.5 times that of the stationary pin-fin channels. Overall, rotation enhances the heat transfer from all surfaces in both the smooth and pin-fin channels. Finally, as the rotation number increases, spanwise variation increases in all channels.

Single-Phase Heat Transfer in Mems-Based Pin Fin Heat Sink

2005 ◽  
Author(s):  
Ali Kosar ◽  
Yoav Peles
Keyword(s):  
Heat Transfer ◽  
Single Phase ◽  
Reynolds Numbers ◽  
Heat Fluxes ◽  
Transfer Coefficients ◽  
Pin Fin ◽  
Heat Transfer Coefficients ◽  
Nusselt Numbers ◽  
Pin Fins ◽  
Micro Pin Fins

An experimental study has been performed on single-phase heat transfer of de-ionized water over a bank of shrouded micro pin fins 243-μm long with hydraulic diameter of 99.5-μm. Heat transfer coefficients and Nusselt numbers have been obtained over effective heat fluxes ranging from 3.8 to 167 W/cm2 and Reynolds numbers from 14 to 112. The results were used to derive the Nusselt numbers and total thermal resistances. It has been found that endwalls effects are significant at low Reynolds numbers and diminish at higher Reynolds numbers.

Compact Transient Thermal Model of Microfluidically Cooled Three-Dimensional Stacked Chips With Pin-Fin Enhanced Microgap

2021 ◽  
Vol 143 (3) ◽  
Author(s):  
Yuanchen Hu ◽  
Md Obaidul Hossen ◽  
Zhimin Wan ◽  
Muhannad S. Bakir ◽  
Yogendra Joshi
Keyword(s):  
Heat Transfer ◽  
Integrated Circuit ◽  
High Performance ◽  
Heat Dissipation ◽  
Three Dimensional ◽  
Heat Removal ◽  
Power Estimation ◽  
Leakage Power ◽  
Pin Fin ◽  
Pin Fins

Abstract Three-dimensional (3D) stacked integrated circuit (SIC) chips are one of the most promising technologies to achieve compact, high-performance, and energy-efficient architectures. However, they face a heat dissipation bottleneck due to the increased volumetric heat generation and reduced surface area. Previous work demonstrated that pin-fin enhanced microgap cooling, which provides fluidic cooling between layers could potentially address the heat dissipation challenge. In this paper, a compact multitier pin-fin single-phase liquid cooling model has been established for both steady-state and transient conditions. The model considers heat transfer between layers via pin-fins, as well as the convective heat removal in each tier. Spatially and temporally varying heat flux distribution, or power map, in each tier can be modeled. The cooling fluid can have different pumping power and directions for each tier. The model predictions are compared with detailed simulations using computational fluid dynamics/heat transfer (CFD/HT). The compact model is found to run 120–600 times faster than the CFD/HT model, while providing acceptable accuracy. Actual leakage power estimation is performed in this codesign model, which is an important contribution for codesign of 3D-SICs. For the simulated cases, temperatures could decrease 3% when leakage power estimation is adopted. This model could be used as electrical-thermal codesign tool to optimize thermal management and reduce leakage power.

Natural Convection Heat Transfer From Vertical 5×5 Rod Bundles in Liquid Sodium

2016 ◽  
Author(s):  
Koichi Hata ◽  
Katsuya Fukuda ◽  
Tohru Mizuuchi
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Three Dimensional ◽  
Convection Heat Transfer ◽  
Heat Fluxes ◽  
Liquid Sodium ◽  
Natural Convection Heat Transfer ◽  
Convection Heat ◽  
Rod Bundles ◽  
Average Value

Natural convection heat transfer from vertical 5×5 rod bundles in liquid sodium was numerically analyzed for two types of the bundle geometry (equilateral square and triangle arrays, ESA and ETA). The unsteady laminar three dimensional basic equations for natural convection heat transfer caused by a step heat flux were numerically solved until the solution reaches a steady-state. The PHOENICS code was used for the calculation considering the temperature dependence of thermophysical properties concerned. The 5×5 test rods for diameter (D = 7.6 mm), heated length (L = 200 mm) and L/d (= 26.32) were used in this work. The surface heat fluxes for each cylinder were equally given for a modified Rayleigh number, (Rf,L)ij and (Rf,L)5×5,S/D, ranging from 3.08 × 104 to 4.19 × 107 (q = 1 × 104∼7 × 106 W/m2) in liquid temperature (TL = 673.15 K). The values of S/D, which are ratios of the diameter of flow channel for bundle geometry to the rod diameter, for vertical 5×5 rod bundles were ranged from 1.8 to 6 on each bundle geometry. The spatial distribution of local and average Nusselt numbers, (Nuav)ij and (Nuav,B)5×5,S/D, on vertical rods of a bundle was clarified. The average value of Nusselt number, (Nuav)ij and (Nuav,B)5×5,S/D, for two types of the bundle geometry with various values of S/D were calculated to examine the effect of the bundle geometry, S/D, (Rf,L)ij and (Rf,L)5×5,S/D on heat transfer. The bundle geometry for the higher (Nuav,B)5×5,S/D value under the condition of S/D = constant was examined. The correlations for (Nuav,B)5×5,S/D for two types of bundle geometry above mentioned including the effects of (Rf,L)5×5,S/D and S/D were developed. The correlations can describe the theoretical values of (Nuav,B)5×5,S/D for two types of the bundle geometry for S/D ranging from 1.8 to 6 within −11.77 to 13.34 % difference.

Numerical Investigation on the Flow and Heat Transfer Characteristics of the Superheated Steam in the Wedge Duct With Pin-Fins

2013 ◽  
Author(s):  
Gaoliang Liao ◽  
Xinjun Wang ◽  
Xiaowei Bai ◽  
Ding Zhu ◽  
Jinling Yao
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Three Dimensional ◽  
Heat Transfer Characteristics ◽  
Pin Fin ◽  
Transfer Characteristics ◽  
Flow And Heat Transfer ◽  
Pin Fins ◽  
Steam Superheat

By using the CFX software, the three-dimensional flow and heat transfer characteristics in the cooling duct with pin-fin in the blade trailing edge were numerically simulated. The effects of pin-fin arrangements, Reynolds number, steam superheat degrees, streamwise pin density and convergence angle of the wedge duct on the flow and heat transfer characteristics were analysed. The results show that the Nusselt number on the endwall and pin-fin surfaces as well as the pin-fin row averaged Nusselt number increase with the increasing of Reynolds number, while it decreased with the with the increasing of X/D. The pressure drop increases with the increasing of Reynolds number while decreases with the increasing of X/D in the wedge duct. The degree of superheat has little effect on the pressure loss in the wedge duct. A comprehensive analysis and comparison show that the highest thermal performance is reached in the wedge duct when the value of X/D is 1.5.

Natural Convection Heat Transfer From Vertical 5 × 5 Rod Bundles in Liquid Sodium

2017 ◽  
Vol 139 (3) ◽  
Author(s):  
Koichi Hata ◽  
Katsuya Fukuda ◽  
Tohru Mizuuchi
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Three Dimensional ◽  
Convection Heat Transfer ◽  
Heat Fluxes ◽  
Liquid Sodium ◽  
Natural Convection Heat Transfer ◽  
Convection Heat ◽  
Rod Bundles ◽  
Nusselt Numbers

Natural convection heat transfer from vertical 5 × 5 rod bundles in liquid sodium was numerically analyzed for two types of the bundle geometry (equilateral square array (ESA) and equilateral triangle array (ETA)). The unsteady laminar three-dimensional basic equations for natural convection heat transfer caused by a step heat flux were numerically solved until the solution reaches a steady-state. The phoenics code was used for the calculation considering the temperature dependence of thermophysical properties concerned. The 5 × 5 test rods for diameter (D = 7.6 mm), heated length (L = 200 mm), and L/d (=26.32) were used in this work. The surface heat fluxes for each cylinder were equally given for a modified Rayleigh number, (Rf,L)ij and (Rf,L)5×5,S/D, ranging from 3.08 × 104 to 4.19 × 107 (q = 1 × 104–7 × 106 W/m2) in liquid temperature (TL = 673.15 K). The values of S/D, which are ratios of the diameter of flow channel for bundle geometry to the rod diameter, for vertical 5 × 5 rod bundles were ranged from 1.8 to 6 on each bundle geometry. The spatial distribution of local and average Nusselt numbers, (Nuav)ij and (Nuav,B)5×5,S/D, on vertical rods of a bundle was clarified. The average value of Nusselt numbers, (Nuav)ij and (Nuav,B)5×5,S/D, for the two types of the bundle geometry with various values of S/D were calculated to examine the effect of the bundle geometry, S/D, (Rf,L)ij, and (Rf,L)5×5,S/D on heat transfer. The bundle geometry for the higher (Nuav,B)5×5,S/D value under the condition of S/D = constant was examined. The correlations for (Nuav,B)5×5,S/D for two types of bundle geometry above mentioned including the effects of (Rf,L)5×5,S/D and S/D were developed. The correlations can describe the theoretical values of (Nuav,B)5×5,S/D for the two types of the bundle geometry at S/D ranging from 1.8 to 6 within −12.64% to 7.73% difference.

Numerical Study on Heat Transfer Characteristics in Rectangular Ducts With Pin-Fins

2011 ◽  
Author(s):  
Xinjun Wang ◽  
Xiaowei Bai ◽  
Jiangbo Wu ◽  
Rui Liu ◽  
Ding Zhu ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Numerical Study ◽  
Flow Direction ◽  
Three Dimensional ◽  
Heat Transfer Characteristics ◽  
Pin Fin ◽  
Transfer Characteristics ◽  
Pin Fins

By using the CFX software, three-dimensional flow and heat transfer characteristics in rectangular cooling ducts with in-line and staggered array pin-fins of gas turbine blade trailing edge were numerically simulated. The effects of in-line and staggered arrays of pin-fins, flow Reynolds number as well as density of cylindrical pin-fins in flow direction on heat transfer characteristics were analyzed. Both in the cases of in-line and staggered arrays of pin-fins, the results show that the pin-fin surface averaged Nusselt number increases with the increasing of Reynolds number. In the case of the same Reynolds number, the mean Nusselt number of pin-fin surface decreased with the increasing of X/D (the ratio of streamwise pin-pitch to pin-fin diameter) value. The Nusselt number increases gradually before the first pin-fin row and then reached the fully developed value at fourth or fifth row. The pin-fin Nusselt number at flow direction is larger than that at back flow direction. Along the height direction of pin-fin, the Nusselt number in middle area is larger.

A Comparative Study of Flow Boiling in a Microchannel With Piranha Pin Fins

2016 ◽  
Vol 138 (11) ◽  
Author(s):  
X. Yu ◽  
C. Woodcock ◽  
Y. Wang ◽  
J. Plawsky ◽  
Y. Peles
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Flow Boiling ◽  
High Heat ◽  
Heat Fluxes ◽  
Working Fluid ◽  
Flow Conditions ◽  
Pressure Drops ◽  
Flow And Heat Transfer ◽  
Pin Fins

In this paper, we report on the recent development of an advanced microscale heat sink, termed as piranha pin fin (PPF). A 200 μm deep microchannel embedded with PPFs was fabricated and tested. Fluid flow and heat transfer performance were evaluated with HFE7000 as the working fluid. The surface temperature, pressure drop, heat transfer coefficient, and critical heat flux (CHF) conditions were experimentally obtained and discussed. A 676 W/cm2 CHF was achieved based on the heater area and at an inlet mass flux of 2460 kg/m2 s. Microchannels with different PPF configurations were investigated and studied for different flow conditions. It was found that a microchannel with PPFs can dissipate high heat fluxes with reasonable pressure drops. Flow conditions and PPF configuration played important roles for both fluid flow and heat transfer performances. These studies extended knowledge and provided useful reference for further PPF design in microchannel for flow boiling.

Experimental and Numerical Analysis of Convective Heat Transfer From Notched Fin Arrays With Pin Fins

2013 ◽  
Author(s):  
Sunil V. Dingare ◽  
Suneeta S. Sane ◽  
Aniket H. Kawade ◽  
Hrishikesh N. Kulkarni ◽  
Kaustibh U. Suranglikar
Keyword(s):  
Heat Transfer ◽  
Numerical Analysis ◽  
Temperature Difference ◽  
Heat Sink ◽  
Convection Heat Transfer ◽  
Heat Sinks ◽  
Central Portion ◽  
Pin Fin ◽  
Pin Fins ◽  
Free Convection Heat

In electronic components, it is essential to provide for adequate cooling to ensure that overheating does not affect the performance. It has been observed that for short fins, (L/H ≤ 5) due to formation of stagnant zone, central portion of fin is ineffective. To overcome this problem central portion from plate fin is removed. By doing so average heat transfer coefficient of notched array was improved almost by 30percentage compared to normal plate fin array. In this study we present computational assessment of notched plate fin heat sink (NPFHS) & notched plate fin pin fin heat sink (NPFPFHS). Based on NPFHS, a NPFPFHS is constructed which is composed of a NPFHS and some columnar pins planted between notched plate fins. Limited experimentation is carried out for validation of numerical model. Numerical analysis is carried out to compare thermal performance of these two types of heat sinks under the condition of equal temperature difference between mean sink temperature and ambient temperature. The effects of fin spacing, fin height, pin fin diameter and temperature difference between fin and surroundings on the free convection heat transfer from horizontal fin arrays were studied. The analysis have been carried out for the two types of heat sinks with three different spacing, three different height, four temperature differences and three pin diameters.

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