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.

Hydoroil-Based Micro Pin Fin Heat Sink

2006 ◽  
Author(s):  
Ali Kosar ◽  
Chih-Jung Kuo ◽  
Yoav Peles
Keyword(s):  
Heat Sink ◽  
Hydraulic Performance ◽  
Heat Fluxes ◽  
Heat Sinks ◽  
Transfer Coefficients ◽  
Pin Fin ◽  
Nusselt Numbers ◽  
Friction Factors ◽  
Pin Fins ◽  
Micro Pin Fins

An experimental study on thermal-hydraulic performance of de-ionized water over a bank of shrouded NACA 66-021 hydrofoil micro pin fins with wetted perimeter of 1030-μm and chord thickness of 100 μm has been performed. Average heat transfer coefficients have been obtained over effective heat fluxes ranging from 4.0 to 308 W/cm2 and mass velocities from 134 to 6600 kg/m2s. The experimental data is reduced to the Nusselt numbers, Reynolds numbers, total thermal resistances, and friction factors in order to determine the thermal-hydraulic performance of the heat sink. It has been found that prodigious hydrodynamic improvement can be obtained with the hydrofoil-based micro pin fin heat sink compared to the circular pin fin device. Fluid flow over pin fin heat sinks comprised from hydrofoils yielded radically lower thermal resistances than circular pin fins for a similar pressure drop.

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.

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.  

Liquid Single-Phase Flow in an Array of Micro-Pin-Fins—Part I: Heat Transfer Characteristics

2008 ◽  
Vol 130 (12) ◽  
Author(s):  
Weilin Qu ◽  
Abel Siu-Ho
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Average Nusselt Number ◽  
Single Phase ◽  
Phase Flow ◽  
Single Phase Flow ◽  
Pin Fin ◽  
Pin Fins ◽  
Micro Pin Fins

This is Paper I of a two-part study concerning thermal and hydrodynamic characteristics of liquid single-phase flow in an array of micro-pin-fins. This paper reports the heat transfer results of the study. An array of 1950 staggered square micro-pin-fins with 200×200 μm2 cross-section by 670 μm height were fabricated into a copper test section. De-ionized water was used as the cooling liquid. Two coolant inlet temperatures of 30°C and 60°C and six maximum mass velocities for each inlet temperature ranging from 183 to 420 kg/m2 s were tested. The corresponding inlet Reynolds number ranged from 45.9 to 179.6. General characteristics of average and local heat transfer were described. Six previous conventional long and intermediate pin-fin correlations and two micro-pin-fin correlations were examined and were found to overpredict the average Nusselt number data. Two new heat transfer correlations were proposed for the average heat transfer based on the present data, in which the average Nusselt number is correlated with the average Reynolds number by power law. Values of the exponent m of the Reynolds number for the two new correlations are fairly close to those for the two previous micro-pin-fin correlations but substantially higher than those for the previous conventional pin-fin correlations, indicating a stronger dependence of the Nusselt number on the Reynolds number in micro-pin-fin arrays. The correlations developed for the average Nusselt number can adequately predict the local Nusselt number data.

Parameter Optimization of a Micro Heat Sink With Circular Pin-Fins

2010 ◽  
Author(s):  
Mustafa Koz ◽  
Ali Kosar
Keyword(s):  
Experimental Data ◽  
Heat Sink ◽  
Stokes Equations ◽  
Numerical Models ◽  
Symmetry Plane ◽  
Heat Removal ◽  
Heat Sinks ◽  
Performance Criteria ◽  
Pin Fin ◽  
Pin Fins

Micro heat sinks have a broad applicability in many fields such as aerospace applications, micro turbine cooling, micro reactors electronics cooling and micro biological applications. Among different types of micro heat sinks, those with micro pin-fins are becoming popular due to their enhanced heat removal performance. However, relevant experimental data is still scarce and few optimization studies are present in the literature. In order to effectively optimize their performance an extensive parametric study is necessary and should be based on a realistic model. Moreover, micro pin fin heat sinks should be optimized according to appropriate performance criteria depending on the application. The objective of this paper is to fill the research gap in micro pin fin heat sink optimization based on realistic configurations. In this paper, the parameters for micro pin optimization are the pin-fin height over diameter ratio (0.5<H/D<5) and the longitudinal and transverse pitch ratios (1.5<(SL, ST)/D<5), while Reynolds number and heat flux provided from the base of the micro heat sink are in the range of (1<Re<100) and (20<q(W/cm2)<500) respectively. In this research micro pin fin heat sinks are three dimensionally modeled on a one-to-one scale with the use of commercially available software COMSOL Multiphasics 3.5a. Full Navier-Stokes equations subjected to continuity and energy equations are solved for stationary conditions. To have increased computational efficiency, half of the heat sink is modeled with the use of a symmetry plane. In order to validate the use of numerical models parametric values from previous experimental data available in the literature are exactly taken and simulated. The numerical and experimental results show a good agreement. After this validation optimization study is performed using the three dimensional numerical models.

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.

scholarly journals Multi-scale pin fins: Scale analysis and mathematical optimization of micro-pin fins arranged in rows

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Tunde Bello-Ochende
Keyword(s):  
Heat Transfer ◽  
Heat Sink ◽  
Mathematical Optimization ◽  
Thermal Conductivity Ratio ◽  
Maximum Heat ◽  
Pin Fin ◽  
Maximum Heat Transfer ◽  
Computational Fluid Dynamics Analysis ◽  
Pin Fins ◽  
Micro Pin Fins

AbstractThis paper shows the performance of a cylindrical micro-pin fins with multiples-arrays structures for maximum heat transfer. The structures has a varying geometric sizes (diameter, height and spacing). The effects of Reynolds number and thermal conductivity ratio on the optimized geometric configurations and the maximum heat transfer rate is documented. Two design configuration were considered. Scales and computational fluid dynamics analysis shows that the benefits of varying fin height is minimal. Results show that performace is increased when three rows of micro pin fin heat sinks with a reduced degree of freedom (fixed height) when compared to two rows of micro pin fins heat sink for the same amount of material. The optimized diameters of the fins seems to have greatest effect on perfomance of the heat sink.

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.

Heat Transfer and Pressure Loss Characteristics of Pin-Fins With Different Shapes in a Wide Channel

2017 ◽  
Author(s):  
Jin Xu ◽  
Jiaxu Yao ◽  
Pengfei Su ◽  
Jiang Lei ◽  
Junmei Wu ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Thermal Performance ◽  
Pressure Loss ◽  
Bottom Surface ◽  
Number Range ◽  
Pin Fin ◽  
Nominal Diameter ◽  
Pin Fins

Convective heat transfer enhancement and pressure loss characteristics in a wide rectangular channel (AR = 4) with staggered pin fin arrays are investigated experimentally. Six sets of pin fins with the same nominal diameter (Dn = 8mm) are tested, including: Circular, Elliptic, Oblong, Dropform, NACA and Lancet. The relative spanwise pitch (S/Dn = 2) and streamwise pitch (X/Dn = 4.5) are kept the same for all six sets. Same nominal diameter and arrangement guarantee the same blockage area in the channel for each set. Reynolds number based on channel hydraulic diameter is from 10000 to 70000 with an increment of 10000. Using thermochromic liquid crystal (R40C20W), heat transfer coefficients on bottom surface of the channel are achieved. The obtained friction factor, Nusselt number and overall thermal performance are compared with the previously published data from other groups. The averaged Nusselt number of Circular pin fins is the largest in these six pin fins under different Re. Though Elliptic has a moderate level of Nusselt number, its pressure loss is next to the lowest. Elliptic pin fins have pretty good overall thermal performance in the tested Reynolds number range. When Re>40000, Lancet has a same level of performance as Circular, but its pressure loss is much lower than Circular. These two types are both promising alternative configuration to Circular pin fin used in gas turbine blade.

Row Removal Heat Transfer Study for Pin Fin Arrays

2014 ◽  
Author(s):  
Kathryn L. Kirsch ◽  
Jason K. Ostanek ◽  
Karen A. Thole ◽  
Eleanor Kaufman
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
High Reynolds Number ◽  
Pin Fin ◽  
Heat Transfer Augmentation ◽  
Aspect Ratios ◽  
Pin Fins ◽  
High Reynolds ◽  
Pin Fin Arrays ◽  
Transfer Study

Arrays of variably-spaced pin fins are used as a conventional means to conduct and convect heat from internal turbine surfaces. The most common pin shape for this purpose is a circular cylinder. Literature has shown that beyond the first few rows of pin fins, the heat transfer augmentation in the array levels off and slightly decreases. This paper provides experimental results from two studies seeking to understand the effects of gaps in pin spacing (row removals) and alternative pin geometries placed in these gaps. The alternative pin geometries included large cylindrical pins and oblong pins with different aspect ratios. Results from the row removal study at high Reynolds number showed that when rows four through eight were removed, the flow returned to a fully-developed channel flow in the gap between pin rows. When larger alternative geometries replaced the fourth row, heat transfer increased further downstream into the array.

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