scholarly journals Elliptical Pin Fin Heat Sink: Passive Cooling Control

2021 ◽  
Vol 39 (5) ◽  
pp. 1417-1429
Author(s):  
Fatima Zohra Bakhti ◽  
Mohamed Si-Ameur
Keyword(s):  
Reynolds Number ◽  
Aspect Ratio ◽  
Numerical Simulations ◽  
Heat Sink ◽  
Three Dimensional ◽  
Geometrical Parameters ◽  
Cooling Process ◽  
Pin Fin ◽  
Pin Fins ◽  
And Control

The aim of this study is to examine by means of three-dimensional numerical simulations the thermal-fluid features in elliptical pin fin heat sink. The passive heat transfer enhancement technique is used to comprehend and control the cooling process. This passive methodology is based on pin fins arrangement, hydrodynamic and geometrical parameters. The present numerical results are confronted with experimental measurements in open literature which used one-dimensional model to explore the thermal field. A good agreement was found especially around the optimal fins dimensions. A parametric study has been carried out to deeply analyse the three-dimensional thermal-fluid fields of the heat sink for various key parameters range such the Reynolds number (Re = 50–250) and the aspect ratio (γ=H/d=5.1-9.18). Some new observations and results are obtained thanks to numerical simulations as tool of investigation. It is shown that the fins circumferential temperature is almost uniform. Furthermore, a better cooling is obtained when the Reynolds number increases mainly when the inlet velocity u0> 0.3m/s. The most suitable value of the aspect ratio is attained for γ=8.16, which ensure an optimal cooling process of the pins. A new global Nusselt number correlation was developed for engineering applications.

S-Shaped Pin-Fins for Enhancement of Overall Performance of the Pin-Fin Heat Sink

2010 ◽  
Author(s):  
T. J. John ◽  
B. Mathew ◽  
H. Hegab
Keyword(s):  
Reynolds Number ◽  
Thermal Resistance ◽  
Thermal Performance ◽  
Heat Sink ◽  
Heat Sinks ◽  
Uniform Heat Flux ◽  
Pumping Power ◽  
Pin Fin ◽  
Pin Fins ◽  
Overall Performance

In this paper the authors are studying the effect of introducing S-shaped pin-fin structures in a micro pin-fin heat sink to enhance the overall thermal performance of the heat sinks. For the purpose of evaluating the overall thermal performance of the heat sink a figure of merit (FOM) term comprising both thermal resistance and pumping power is introduced in this paper. An optimization study of the overall performance based on the pitch distance of the pin-fin structures both in the axial and the transverse direction, and based on the curvature at the ends of S-shape fins is also carried out in this paper. The value of the Reynolds number of liquid flow at the entrance of the heat sink is kept constant for the optimization purpose and the study is carried out over a range of Reynolds number from 50 to 500. All the optimization processes are carried out using computational fluid dynamics software CoventorWARE™. The models generated for the study consists of two sections, the substrate (silicon) and the fluid (water at 278K). The pin fins are 150 micrometers tall and the total structure is 500 micrometer thick and a uniform heat flux of 500KW is applied to the base of the model. The non dimensional thermal resistance and nondimensional pumping power calculated from the results is used in determining the FOM term. The study proved the superiority of the S-shaped pin-fin heat sinks over the conventional pin-fin heat sinks in terms of both FOM and flow distribution. S-shaped pin-fins with pointed tips provided the best performance compared to pin-fins with straight and circular tips.

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.

Numerical Investigation of Heat Transfer in a High Aspect Ratio Double Wall Channel With Pin Fin and Jet Array Impingement

2016 ◽  
Author(s):  
Rui Kan ◽  
Shuqing Tian
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Cfd Simulation ◽  
Cooling Effectiveness ◽  
Pin Fin ◽  
Pin Fins ◽  
Double Wall ◽  
Jet Array

A combined impingement-pedestal geometry for turbomachinery double wall cooling application is studied numerically with the shear stress transport turbulence model. Conjugated CFD simulation is performed to investigate the cooling effectiveness distribution. The configuration consists of a high aspect ratio cooling duct, with jet array impinging onto the pin fin-roughed wall. The jet Reynolds number varies from 8,000 to 80,000, jet-to-target wall spacing is kept constant at Z/Dj=0.8. Three main parameters are investigated, including the jet Reynolds number, pin fin shapes (circular and elongated) and the relative location between jets and pin fins (the jet placed uniformly inside the duct or more densely at the front of the duct). For more detailed investigations, the pin fin diameter and impingement hole diameter are varied independently, and a total of 26 configurations are studied. The results show that the double wall configuration with pin fins significantly increases the heat transfer coefficients, compared to that with only impingement. Non-uniform jet arrangement results in a stronger crossflow and enhances heat transfer on the pins, which brings an increase of cooling effectiveness and more uniform temperature distribution.

scholarly journals Effect of Using Extra Fins on the Pin Fin Classic Geometry for Enhancement Heat Sink Performance using EGM Method

2018 ◽  
Vol 24 (4) ◽  
pp. 1 ◽  
Author(s):  
Kadhum Audaa Jehhef
Keyword(s):  
Reynolds Number ◽  
Nusselt Number ◽  
Cross Section ◽  
Entropy Generation ◽  
Heat Sink ◽  
Generation Rate ◽  
Entropy Generation Rate ◽  
Minimum Entropy ◽  
Pin Fin ◽  
Pin Fins

In the present study, the effect of new cross-section fin geometries on overall thermal/fluid performance had been investigated. The cross-section included the base original geometry of (triangular, square, circular, and elliptical pin fins) by adding exterior extra fins along the sides of the origin fins. The present extra fins include rectangular extra fin of 2 mm (height) and 4 mm (width) and triangular extra fin of 2 mm (base) 4 mm (height). The use of entropy generation minimization method (EGM) allows the combined effect of thermal resistance and pressure drop to be assessed through the simultaneous interaction with the heat sink. A general dimensionless expression for the entropy generation rate is obtained by considering a control volume around the pin fin including a base plate and applying the conservations equations of mass and energy with the entropy balance. The dimensionless numbers used includes the aspect ratio (ε), Reynolds number (Re), Nusselt number (Nu), and the drag coefficients (CD). Fourteen different cross-section fin geometries are examined for the heat transfer, fluid friction, and the minimum entropy generation rate. The results showed that the Nusselt number increases with increasing the Reynolds number for all employed models. The ellipse models (ET and ER-models) give the highest value in the Nusselt number as compared with the classical pin fins. The fin of the square geometry with four rectangular extra fins (SR-models) gives an agreement in Nusselt number as compared with the previous study.  

Nusselt Number and Friction Factor of Staggered Arrays of Low Aspect Ratio Micro-Pin-Fins Under Cross Flow for Water as Fluid

2006 ◽  
Author(s):  
Ravi S. Prasher ◽  
John Dirner ◽  
Je-Young Chang ◽  
Alan Myers ◽  
David Chau ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Nusselt Number ◽  
Aspect Ratio ◽  
Friction Factor ◽  
Cross Flow ◽  
Maximum Velocity ◽  
Pin Fin ◽  
Low Aspect Ratio ◽  
Pin Fins ◽  
Cold Plates

Experimental results of the thermal and hydraulic performances of silicon-based, low aspect ratio micro-pin-fin cold plates under cross flow conditions are reported. The pins were both circular and square in shape with dimensions (diameter for circular and sides for square) ranging from 50 to 150 μm. The test chip contained 20 integral 75×75 μm temperature sensors which were used to determine the thermal resistance (K W-1) of the cold plates. The experiments were conducted using water, over a Reynolds number (Re) ranging from 40 to 1000. The data show that the average Nusselt number (Nu) based on the fin diameter varies as Re0.84 for Re < 100 and as Re0.73 for Re > 100, where Re is the Reynolds number based on maximum velocity and the fin diameter. Analysis of the Fanning friction factor (f) data shows that f varies as Re-1.35 for Re < 100 and as Re-0.1 for Re > 100.

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.

Effect of Pin-Fin Geometry on Microchannel Performance

2018 ◽  
Vol 14 (1) ◽  
Author(s):  
Subhash V. Jadhav ◽  
Prashant M. Pawar ◽  
Babruvahan P. Ronge
Keyword(s):  
Nusselt Number ◽  
Numerical Analysis ◽  
Heat Sink ◽  
Three Dimensional ◽  
Total Surface Area ◽  
Microchannel Heat Sink ◽  
Pin Fin ◽  
Nusselt Numbers ◽  
Pin Fins ◽  
Maximum Increment

Abstract Purpose A numerical analysis is carried out to study the effect of pin fin geometry on the performance of microchannel heat sinks. Design/methodology/approach A three-dimensional numerical analysis is carried out using the conjugate heat transfer module of COMSOL MULTIPHYSICS software. Initially, the study is carried out for a microchannel heat sink with elliptical pin fins of 500 µm fin height, and the results of the same are validated with the results obtained from the literature. Further, the effect of different pin fin shapes and pin fin heights is investigated in terms of Nusselt number and pressure drop. The analysis is carried out with different pin fin shapes viz. ellipse, circle, square and hexagon. The pin fin height for all channels is varied from 300 µm to 700 µm. The total surface area of the channel coming into contact with coolant is kept constant for different coolant inflow velocities. Findings Higher values of Nusselt numbers are obtained for fin pins at larger height and high coolant inlet velocities. At coolant inlet velocity of 1 m/s, as pin fin height increases from 300 µm to 700 µm, the channel with circular pin fins shows a maximum increment of 66 % and elliptical pin fins shows a minimum increment of 40 % in terms of Nusselt number. A maximum value of Nusselt number observed is 21.36 with square pin fins of 700 µm fin height and a minimum of 6.03 Nusselt number with circular fins of 300 µm fin height. OriginalityOriginality/Value This study is useful in appropriate selection of pin fin geometry for enhancing the performance of microchannel heat sink.

scholarly journals Thermo-Hydraulic Performance of Square Micro Pin Fins under Forced Convection

2021 ◽  
Vol 39 (1) ◽  
pp. 170-178
Author(s):  
Niranjan Ramendra Singh ◽  
Singh Onkar ◽  
Janakarajan Ramkumar
Keyword(s):  
Reynolds Number ◽  
Forced Convection ◽  
Heat Sink ◽  
Turbulent Transport ◽  
Heat Removal ◽  
Surface Flow ◽  
Fin Efficiency ◽  
Pin Fin ◽  
Pin Fins ◽  
Micro Pin Fins

Thermal management of the new generation’s high performance electronic and mechanical devices is becoming important due to their miniaturization. Conventionally, the plate fin arrangement is widely used for removal of dissipated heat but, their effectiveness is not up to mark. Among different options, the most attractive and efficient alternative for overcoming this problem is micro pin fin heat sink. This paper presents the experimental investigation of square micro-pin fins heat sink for identifying the most suitable pin fin geometry for heat removal applications under forced convection. Twenty five square micro pin fin heat sinks were tested for three different heat load and Reynolds number. The results show that for large fin height lower thermal resistance was observed at the cost of large pressure drop. The dimensionless heat transfer coefficient increases with fin height and Reynolds number while it decreases with increasing fin spacing. The improvement in micro pin fin efficiency were observed by about 2 to 9% owing to presence of fins on the impingement surface, flow mixing, disruption of the boundary layers, and augmentation of turbulent transport.

Effect of Heat Sink Structure Improvement on Heat Dissipation Performance in High Heat Flux

2016 ◽  
Author(s):  
Zhuo Cui
Keyword(s):  
Heat Resistance ◽  
Water Flow ◽  
Heat Sink ◽  
Heat Dissipation ◽  
Convection Heat Transfer ◽  
Cooling Water ◽  
High Heat Flux ◽  
Pin Fin ◽  
Pin Fins ◽  
Pin Fin Arrays

This paper presents the effects of heat dissipation performance of pin fins with different heat sink structures. The heat dissipation performance of two types of pin fin arrays heat sink are compared through measuring their heat resistance and the average Nusselt number in different cooling water flow. The temperature of cpu chip is monitored to determine the temperature is in the normal range of working temperature. The cooling water flow is in the range of 0.02L/s to 0.15L/s. It’s found that the increase of pin fins in the corner region effectively reduce the temperature of heat sink and cpu chip. The new type of pin fin arrays increase convection heat transfer coefficient and reduce heat resistance of heat sink.

scholarly journals Heat Transfer From Low Aspect Ratio Pin Fins

2007 ◽  
Author(s):  
Michael E. Lyall ◽  
Alan A. Thrift ◽  
Atul Kohli ◽  
Karen A. Thole
Keyword(s):  
Heat Transfer ◽  
Aspect Ratio ◽  
Gas Turbines ◽  
Channel Height ◽  
Internal Cooling ◽  
Number Range ◽  
Pin Fin ◽  
Heat Transfer Augmentation ◽  
Low Aspect Ratio ◽  
Pin Fins

The performance of many engineering devices from power electronics to gas turbines is limited by thermal management. Heat transfer augmentation in internal flows is commonly achieved through the use of pin fins, which increase both surface area and turbulence. The present research is focused on internal cooling of turbine airfoils using a single row of circular pin fins that is oriented perpendicular to the flow. Low aspect ratio pin fins were studied whereby the channel height to pin diameter was unity. A number of spanwise spacings were investigated for a Reynolds number range between 5000 to 30,000. Both pressure drop and spatially-resolved heat transfer measurements were taken. The heat transfer measurements were made on the endwall of the pin fin array using infrared thermography and on the pin surface using discrete thermocouples. The results show that the heat transfer augmentation relative to open channel flow is the highest for smallest spanwise spacings and lowest Reynolds numbers. The results also indicate that the pin fin heat transfer is higher than the endwall heat transfer.

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