Numerical Predictions of Thermal and Hydraulic Performances of Heat Sinks With Enhanced Heat Transfer Capability

2011 ◽  
Author(s):  
Feng Zhou ◽  
Nicholas Hansen ◽  
Ivan Catton
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Cross Section ◽  
Heat Sink ◽  
Heat Sinks ◽  
Pin Fin ◽  
Numerical Predictions ◽  
Pin Fins ◽  
New Type ◽  
Cross Section Profile

The plate-pin fin heat sink (PPFHS) is composed of a plate fin heat sink (PFHS) and some pin fins planted between the flow channels. In this paper, a numerical investigation was performed to compare the thermal and hydraulic performances of the PPFHSs and PFHS. PPFHSs with five forms of pin cross-section profiles (square, circular, elliptic, NACA 0050, and dropform) were numerically simulated. The influence of pin fin cross-section profile on the flow and heat transfer characteristics was presented by means of Nusselt number and pressure drop. It is found that the Nu number of a PPFHS is at least 35% higher than that of a PFHS used to construct the PPFHS at the same Reynolds number. Planting circular and square pins into the flow channel of heat sinks enhances the heat transfer at the expense of high pressure loss. Using the streamline shaped pins, not only the pressure drop of the compound heat sinks could be decreased considerably, the heat transfer enhancement also makes a step forward. The present numerical simulation provides original information of the influence of different pin-fin cross-section profiles on the thermal and hydraulic performance of the new type compound heat sink, which is helpful in the design of heat sinks.

Cooling Performance Comparisons of Five Different Plate-Pin Compound Heat Sinks Based on Two Different Length Scale

2011 ◽  
Author(s):  
Feng Zhou ◽  
David Geb ◽  
Ivan Catton
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Heat Transfer Enhancement ◽  
Cross Section ◽  
Heat Sink ◽  
Heat Sinks ◽  
Length Scale ◽  
Transfer Enhancement ◽  
Pin Fin ◽  
New Type

Plate fin heat sinks (PFHS) are widely used to remove heat from the microelectronic devices. In the present study, a new type of compound heat sink, named as plate-pin fin heat sink (PPFHS), is employed to improve the air cooling performance. With CFD numerical method, PPFHSs with five forms of pin cross-section profiles (square, circular, elliptic, NACA 0050, and dropform) and PFHS were simulated. Two different length scales were adopted to evaluate the performance of six types of heat sinks, including PFHS. One of the length scales is commonly used by many investigators, which is two times of the channel spacing. The other length scale is suggested by volume averaging theory (VAT), which is four times of average porosity divided by specific interface. The influence of pin fin cross-section profile on the flow and heat transfer characteristics was presented by means of Nusselt number, pressure drop and overall efficiency. It is found that the Nu number of a PPFHS is at least 35% higher than that of a PFHS used to construct the PPFHS at the same Reynolds number no matter which length scale was used. It is also revealed that the heat transfer enhancement of square PPFHS is offset by its excessively high pressure drop, which makes it not as efficient as the other types of PPFHS. Circular PPFHS performs similar to the streamline shaped PPFHS when the Reynolds number is not too high. However, with the increase in Re the advantage of the circular cross-section diminishes. Using the streamline shaped pins, not only the pressure drop of the compound heat sinks could be decreased considerably, the heat transfer enhancement also makes a step forward. However, evaluating the performance of heat sinks by using the commonly used length scale, the benefit of streamline shaped types of PPFHSs is a little bit overstated. The VAT suggested length scale is more reasonable to do the performance comparison of different heat sinks, especially when it is difficult to provide a fair and physically meaningful basis for the comparison. In short, the present numerical simulation provides original information of the influence of different pin-fin cross-section profiles on the thermal and hydraulic performance of the new type compound heat sink and emphasizes the importance of choosing a proper length scale when evaluating heat transfer enhancement, which is helpful in the design of heat sinks.

Numerical Analysis of Entropy Generation in Array of Pin-Fin Heat Sinks for Some Different Geometries

2010 ◽  
Author(s):  
Reza Kamali ◽  
Bamdad Barari ◽  
Ashkan Abbasian Shirazi
Keyword(s):  
Heat Transfer ◽  
Numerical Analysis ◽  
Pressure Drop ◽  
Cross Section ◽  
Entropy Generation ◽  
Heat Sink ◽  
Control Volume ◽  
Heat Sinks ◽  
Entropy Generation Rate ◽  
Pin Fin

In this study, Numerical analysis has been used to investigate entropy generation for array of pin-fin heat sink. Technique is applied to study the thermodynamic losses caused by heat transfer and pressure drop in pin-fin heat sinks. A general expression for the entropy generation rate is obtained by considering the whole heat sink as a control volume and applying the conservation equations for mass and energy with the entropy balance. Analytical and empirical correlations for heat transfer coefficients and friction factors are used in the numerical modeling. Also effects of heat transfer and pressure drop in entropy generation in control volume over pin-fins have been studied. Numerical analysis has been used for three different models of pin-fin heat sinks. The models are different in cross section area. These cross section areas are circle, horizontal ellipse and vertical ellipse which mentioned in next sections. Reference velocity used in Reynolds number and pressure drop is based on the minimum free area available for the fluid flow. Also for numerical analysis in-line arrangement of fins has been investigated and their relative performance is compared. At the end, the performance of these three models has been compared.

Pin-Fin Heat Sink With Horizontal Base and Blocked Edges

2008 ◽  
Author(s):  
D. Sahray ◽  
H. Shmueli ◽  
N. Segal ◽  
G. Ziskind ◽  
R. Letan
Keyword(s):  
Heat Transfer ◽  
Free Convection ◽  
Contact Resistance ◽  
Cross Section ◽  
Heat Input ◽  
Heat Sink ◽  
Numerical Study ◽  
Heat Sinks ◽  
Transfer Enhancement ◽  
Pin Fin

In the present work, horizontal-base pin fin heat sinks exposed to free convection in air are studied. They are made of aluminum, and there is no contact resistance between the base and the fins. For the same base dimensions the fin height and pitch vary. The fins have a constant square cross-section. The edges of the sink are blocked: the surrounding insulation is flush with the fin tips. The effect of fin height and pitch on the performance of the sink is studied experimentally and numerically. In the experiments, the heat sinks are heated using foil electrical heaters. The heat input is set, and temperatures of the base and fins are measured. In the corresponding numerical study, the sinks and their environment are modeled using the Fluent 6 software. The results show that heat transfer enhancement due to the fins is not monotonic. The differences between sparsely and densely populated sinks are analyzed for various fin heights. Also assessed are effects of the blocked edges as compared to the previously studied cases where the sink edges were exposed to the surroundings.

Cryogenic Single-Phase Heat Transfer in a Microscale Pin Fin Heat Sink

2013 ◽  
Author(s):  
Eric D. Truong ◽  
Erfan Rasouli ◽  
Vinod Narayanan
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Heat Sink ◽  
Single Phase ◽  
Flow Direction ◽  
Heat Sinks ◽  
Variable Cross ◽  
Transfer Coefficients ◽  
Pin Fin ◽  
Heat Transfer Coefficients

A combined experimental and computational fluid dynamics study of single-phase liquid nitrogen flow through a microscale pin-fin heat sink is presented. Such cryogenic heat sinks find use in applications such as high performance computing and spacecraft thermal management. A circular pin fin heat sink in diameter 5 cm and 250 micrometers in depth was studied herein. Unique features of the heat sink included its variable cross sectional area in the flow direction, variable pin diameters, as well as a circumferential distribution of fluid into the pin fin region. The stainless steel heat sink was fabricated using chemical etching and diffusion bonding. Experimental results indicate that the heat transfer coefficients were relatively unchanged around 2600 W/m2-K for flow rates ranging from 2–4 g/s while the pressure drop increased monotonically with the flow rate. None of the existing correlations in literature on cross flow over a tube bank or micro pin fin heat sinks were able to predict the experimental pressure drop and heat transfer characteristics. However, three dimensional simulations performed using ANSYS Fluent showed reasonable (∼7 percent difference) agreement in the average heat transfer coefficients between experiments and CFD simulations.

Optimization of Pin-Fin Heat Sinks in Bypass Flow Using Entropy Generation Minimization Method

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
W. A. Khan ◽  
J. R. Culham ◽  
M. M. Yovanovich
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Entropy Generation ◽  
Heat Sink ◽  
Heat Sinks ◽  
Entropy Generation Rate ◽  
Bypass Flow ◽  
Minimization Method ◽  
Pin Fin ◽  
Entropy Generation Minimization

An entropy generation minimization method is applied to study the thermodynamic losses caused by heat transfer and pressure drop for the fluid in a cylindrical pin-fin heat sink and bypass flow regions. A general expression for the entropy generation rate is obtained by considering control volumes around the heat sink and bypass regions. The conservation equations for mass and energy with the entropy balance are applied in both regions. Inside the heat sink, analytical/empirical correlations are used for heat transfer coefficients and friction factors, where the reference velocity used in the Reynolds number and the pressure drop is based on the minimum free area available for the fluid flow. In bypass regions theoretical models, based on laws of conservation of mass, momentum, and energy, are used to predict flow velocity and pressure drop. Both in-line and staggered arrangements are studied and their relative performance is compared to the same thermal and hydraulic conditions. A parametric study is also performed to show the effects of bypass on the overall performance of heat sinks.

Pressure Drop and Heat Transfer in a Single-Phase Micro-Pin-Fin Heat Sink

2006 ◽  
Author(s):  
Abel M. Siu Ho ◽  
Weilin Qu ◽  
Frank Pfefferkorn
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Pressure Drop ◽  
Friction Factor ◽  
Heat Sink ◽  
Single Phase ◽  
Fluid Transport ◽  
Heat Sinks ◽  
Inlet Temperature ◽  
Pin Fin

The pressure drop and heat transfer characteristics of a single-phase micro-pin-fin heat sink were investigated experimentally. Fabricated from 110 copper, the heat sink consisted of 1950 staggered micro-pins with 200×200 μm2 cross-section by 670 μm height. Deionized water was employed as the cooling liquid. A coolant inlet temperature of 25°C, and two heat flux levels, q" eff = 50 W/cm2 and q" eff = 100 W/cm2, defined relative to the planform area of the heat sink, were tested. The inlet Reynolds number ranged from 93 to 634 for q" eff = 50 W/cm2, and 127 to 634 for q" eff = 100 W/cm2. The measured pressure drop and temperature distribution were used to evaluate average friction factor and local averaged heat transfer coefficient/Nusselt number. Predictions of the Moores and Joshi friction factor correlation and the Chyu et al. heat transfer correlation that were developed using macro-size pin-fin arrays were compared to micro-pin-fin heat sink data. While the Moores and Joshi correlation provide acceptable predictions, the Chyu et al. correlation overpredicted local Nusselt number data by a fairly large margin. These findings point to the need for further study of single-phase thermal/fluid transport process in micro-pin-fin heat sinks.

Effect of Fin Pitch and Height on Pin-Fin Heat Sink Performance

2008 ◽  
Author(s):  
D. Sahray ◽  
H. Shmueli ◽  
N. Segal ◽  
G. Ziskind ◽  
R. Letan
Keyword(s):  
Heat Transfer ◽  
Free Convection ◽  
Contact Resistance ◽  
Cross Section ◽  
Heat Input ◽  
Heat Sink ◽  
Numerical Study ◽  
Heat Sinks ◽  
Transfer Enhancement ◽  
Pin Fin

In the present work, horizontal-base pin fin heat sinks exposed to free convection in air are studied. They are made of aluminum, and there is no contact resistance between the base and the fins. The sinks have the same base dimensions whereas the fin height and pitch vary. The fins have a constant square cross-section. The effect of fin height and pitch on the performance of the sink is studied experimentally and numerically. In the experiments, the heat sinks are heated using foil electrical heaters. The heat input is set, and temperatures of the base and fins are measured. In the corresponding numerical study, the sinks and their environment are modeled using the Fluent 6.3 software. The results show that heat transfer enhancement due to the fins is not monotonic. The differences between sparsely and densely populated sinks are analyzed for various fin heights.

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.

A Model for Flow Bypass and Tip Leakage in Pin Fin Heat Sinks

2005 ◽  
Vol 128 (1) ◽  
pp. 53-60 ◽  
Author(s):  
M. Baris Dogruoz ◽  
Alfonso Ortega ◽  
Russell V. Westphal
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Heat Sink ◽  
Ad Hoc ◽  
Flow Direction ◽  
Heat Sinks ◽  
Tip Leakage ◽  
Pin Fin ◽  
Static Pressure Distribution ◽  
Study Results

A model for the pressure drop and heat transfer behavior of heat sinks with top bypass is presented. In addition to the characteristics of a traditional two-branch bypass model, the physics of tip leakage are taken into consideration. The total flow bypass is analyzed in terms of flow that is completely diverted and flow that enters the heat sink but leaks out. Difference formulations of the momentum and the energy equations were utilized to model the problem in the flow direction. Traditional hydraulic resistance and heat transfer correlations for infinitely long tube bundles were used to close the equations. Tip leakage mechanisms were modeled by introducing momentum equations in the flow normal direction in both the pin side and bypass channel, with ad hoc assumptions about the static pressure distribution in that direction. Although the model is applicable to any kind of heat sink, as a case study, results are presented for in-line square pin fin heat sinks. Results were compared with the predictions from a two-branch bypass model and previous experimental data. It is shown that tip leakage effects are important in setting the overall pressure drop at moderate and high pin spacing, but have only minor influence on heat transfer.

Comparative Analysis of Heat Transfer and Fluid Flow in Circular and Rhombus Pin Fin Heat Sink Using Nanofluid

2021 ◽  
Vol 13 (5) ◽  
Author(s):  
Dungali Sreehari ◽  
Yogesh K. Prajapati
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Comparative Analysis ◽  
Pressure Drop ◽  
Heat Sink ◽  
Heat Dissipation ◽  
Flow Behavior ◽  
Computational Domain ◽  
Pin Fin ◽  
Pin Fins

Abstract Numerical investigation has been carried out to compare the heat transfer performance and fluid flow behavior of microchannel heat sinks with circular and rhombus pin fins which are arranged in an in-line manner. Diameter and sides are 1 mm for circular and rhombus fins. Three-dimensional (3D) computational domain has been simulated using two types of cooling medium, i.e., water and Al2O3–H2O nanofluid. A comprehensive comparative analysis has been presented considering the coolants and pin fin profiles as variable parameters. Two operating variables, i.e., heat flux (q) and Reynolds number (Re), are varied in the range of q = 100–400 kW/m2 and Re = 100–400. A total of 64 cases have been simulated to identify the promising features of both the pin fins attributed to improved heat transfer and overall thermal performance. Comparison has also been made between the coolant medium to find out their heat dissipation potential and flow characteristics in the heat sink. Results obtained in terms of average bottom wall temperature, heat transfer coefficient, Nusselt number (Nu), and pressure drop demonstrate that heat sink with rhombus pin fins dissipates more heat compared to its counterpart. It is attributed to the shape and geometry of rhombus fins that facilitate distinct fluid flow behavior; nevertheless, the pressure drop is less in the circular fin heat sink. Moreover, for constant value of Re, nanofluid extracts more heat compared to water in both configurations of the heat sink.

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