Experimental Comparison of Thermal Resistance for Micro pin fin heat sinks with different shapes and arrangement

2019 ◽  
Author(s):  
Gagan V. Kewalramani ◽  
Gaurav Hedau ◽  
Sandip Kumar Saha ◽  
Amit Agrawal
Keyword(s):  
Thermal Resistance ◽  
Heat Sinks ◽  
Experimental Comparison ◽  
Pin Fin ◽  
Different Shapes

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.

Parametric Study of Heat Sink Performance at High Altitudes With Air Impingement Cooling

2006 ◽  
Author(s):  
Robert E. Seidel ◽  
Jinny Rhee
Keyword(s):  
Reynolds Number ◽  
Thermal Resistance ◽  
Heat Sink ◽  
Air Flow ◽  
Heat Sinks ◽  
Temperature Measurements ◽  
Test Apparatus ◽  
High Altitudes ◽  
Pin Fin ◽  
Hypobaric Chamber

Heat sinks are one of the primary mechanisms today for thermal management of electronics. In the high altitudes reached by modern military aircraft, the capacity for air cooling is reduced due to the rarefied atmosphere. With an increase in altitude there is a subsequent decrease in the density of air. A review of the literature shows a lack of research done on pin-fin heat sinks with impingement flows at low Reynolds number conditions. Experimental testing will determine the thermal resistance of a pin-fin heat sink with impingement flow at low absolute pressures. A test apparatus will be constructed, and experiments will be conducted within a hypobaric chamber. In a hypobaric chamber, it is possible to simulate altitudes up to 30 000 meters by reducing the absolute pressure using a vacuum pump. Temperature is regulated and air is circulated within the chamber. The test apparatus, which is to be completely enclosed within the hypobaric chamber, consists of a centrifugal blower forcing air through a duct. Air is impinged upon a pin-fin heat sink heated with uniform flux on the base. Incident air flow is along the axis of each circular pin-fin, and exhaust from the heat sink will be transverse to the pins. Feedthroughs are available in the chamber wall for supplying electrical power to the blower, for taking temperature measurements with embedded thermocouples, and for measuring blower shaft speed. Temperature measurements are made in the base of the heat sink, in the air, and at other points to characterize other heat losses from the apparatus. Blower speed is monitored with an optical tachometer, and by similarity laws for turbomachinery it will be possible to determine the air flow impinging upon the heat sink. Pressure in the chamber will be varied in several steps up to the equivalent of a 30 000-meter altitude, and at each step a correlation will be made between heat sink thermal resistance and Reynolds number of the impinging air.

The Thermal Resistance of Pin Fin Heat Sinks in Transverse Flow

2003 ◽  
Author(s):  
Sukhvinder Kang ◽  
Maurice Holahan
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Heat Transfer Coefficient ◽  
Thermal Resistance ◽  
Transfer Coefficient ◽  
Building Blocks ◽  
Heat Sinks ◽  
Cfd Simulations ◽  
Pin Fin ◽  
Thermal Wake

This paper presents a physics based analytical model to predict the thermal behavior of pin fin heat sinks in transverse forced flow. The key feature of the model is the recognition that unlike plate fins, streamwise conduction does not occur in pin fin heat sinks. Thus, the heat transfer from each fin depends on its local air temperature or adiabatic temperature and the local adiabatic heat transfer coefficient. Both experimental data and simplified CFD simulations are used to develop the two building blocks of the model, the thermal wake function and the adiabatic heat transfer coefficient. These building blocks are then used to include the effect of the thermal wake from upstream fins on the adiabatic temperature of downstream fins in determining the fin-by-fin heat transfer within the pin fin array. This approach captures the essential physics of the flow and heat transport within the fin array and yields an accurate model for predicting the thermal resistance of pin fin heat sinks. Model predictions are compared with existing experimental data and CFD simulations. The model is expected to provide a sound basis for a consistent performance comparison with plate fin heat sinks.

Thermal Performance Analysis of Fan-Heat Sinks for CPU Cooling

2003 ◽  
Author(s):  
Seo Young Kim ◽  
Ralph L. Webb
Keyword(s):  
Thermal Resistance ◽  
Thermal Performance ◽  
Heat Sink ◽  
Heat Sinks ◽  
Operating Point ◽  
Pin Fin ◽  
Flow Impedance ◽  
Impedance Curve ◽  
Convective Thermal ◽  
Offset Strip Fin

The thermal performance of plate fin, round pin-fin and offset strip-fin heat sinks with a duct-flow type fan arrangement was analytically evaluated. Heat sinks of 65mm × 60mm plan area × 50 mm height with a 4300-RPM DC fan (60mm × 15mm) were chosen for the performance comparison. A constant temperature, 6 mm thick heat sink base plate is assumed so that thermal spreading resistance is not involved. The operating point on the fan curve is based on the flow pressure drop impedance curve through a heat sink using the friction factor correlation for the chosen heat sink. The loss coefficients at both the entrance and the exit of heat sink are included in the flow impedance curve. The operating point is defined by the balance point of the flow impedance curve and the fan performance curve. After determining the operating air velocity, the convective thermal resistance of heat sinks is evaluated from the Nusselt number correlation for the chosen heat sink. Results obtained show that optimized round pin-fin heat sinks provide 32.8%-to-46.4% higher convective thermal resistance compared to an optimized plate-fin heat sink. The optimized offset strip-fin heat sink shows a slightly lower convective thermal resistance than the plate-fin heat sink. As the offset strip length decreases, however, thermal performance seriously deteriorates.

Optimal Arrays of Pin Fins and Plate Fins in Laminar Forced Convection

1993 ◽  
Vol 115 (1) ◽  
pp. 75-81 ◽  
Author(s):  
A. Bejan ◽  
A. M. Morega
Keyword(s):  
Thermal Resistance ◽  
Heat Sinks ◽  
Optimal Thickness ◽  
Pin Fin ◽  
Dimensionless Groups ◽  
Pin Fins ◽  
Fluid Channel ◽  
Laminar Forced Convection ◽  
Fin Thickness ◽  
Pin Fin Array

This paper reports the optimal geometry of an array of fins that minimizes the thermal resistance between the substrate and the flow forced through the fins. The flow regime is laminar. Two fin types are considered: round pin fins, and staggered parallel-plate fins. The optimization of each array proceeds in two steps: The optimal fin thickness is selected in the first step, and the optimal thickness of the fluid channel is selected in the second. The pin-fin array is modeled as a Darcy-flow porous medium. The flow past each plate fin is in the boundary layer regime. The optimal design of each array is described in terms of dimensionless groups. It is shown that the minimum thermal resistance of plate-fin arrays is approximately half of the minimum thermal resistance of heat sinks with continuous fins and fully developed laminar flow in the channels.

Multi Layer Micro Pin-Fins Heat Sinks for Better Performance

2010 ◽  
Author(s):  
T. J. John ◽  
B. Mathew ◽  
H. Hegab
Keyword(s):  
Temperature Distribution ◽  
Thermal Resistance ◽  
Heat Sink ◽  
Single Layer ◽  
Heat Sinks ◽  
Substrate Thickness ◽  
Pin Fin ◽  
Micro Channels ◽  
Pin Fins ◽  
Overall Performance

This study numerically investigates the feasibility and advantages of using a multilayer pin-fin heat sink to increase the overall performance of the heat sink. For the purpose of determining overall performance of the pin-fin heat sink a figure of merit (FOM) term is introduced in this paper, which constituted of both the thermal resistance and the pumping power of the heat sink. Higher the FOM of a heat sink better is its overall performance. A computational fluid dynamics software CoventorWARE™ is used for the analysis of micro heat sink performance. A small portion of the entire heat sink is modeled in this study assuming repeatability towards both sides for the ease of analysis. The developed models consist of two sections, the substrate (silicon) and the fluid (water at 278K). A uniform heat flux is applied to the base of the heat sink. A single layer micro pin-fin heat sinks with same dimensions as of the multi layer heat sink was also modeled for the comparison purpose. Temperature distribution at five different locations from the inlet to the outlet section is also analyzed to study the temperature distribution over the heat sink. Circular pin-fins were used in both the multilayer and single layer micro heat sinks. Feasibility of using micro channels as the second layer was also investigated in this paper and it proved to have advantages over using pin-fin structures on both layers. A geometric optimization based on the substrate thickness of the second layer of the double layer heat sink showed that the substrate thickness of the second layer doesn’t have any effect on the overall thermal resistance of the heat sink.

Effect of Pin Fin Density of the Thermal Performance of Unshrouded Pin Fin Heat Sinks

1994 ◽  
Vol 116 (4) ◽  
pp. 306-309 ◽  
Author(s):  
Kaveh Azar ◽  
Carlo D. Mandrone
Keyword(s):  
Thermal Resistance ◽  
Surface Area ◽  
Forced Convection ◽  
Heat Sinks ◽  
Optimum Number ◽  
Base Temperature ◽  
Pin Fin ◽  
Pin Fins ◽  
Pattern Comparison ◽  
Temperature Constant

An experimental investigation was conducted to examine the effect of pin fin density on thermal resistance of unshrouded pin fin heat sinks. Six heat sinks with different number of round pin fins were constructed. Heat sink thermal resistance was calculated by maintaining its base temperature constant. For these experiments, air flow varied from natural to high velocity forced convection. The results showed that thermal resistance did not decrease with increase of number of pin fins. An optimum number of pin fins existed beyond which thermal resistance actually increased. The study also showed that thermal resistance was a function of air velocity and governing flow pattern. Comparison of the heat transfer coefficient (h) and pin fin surface area showed that h decreased dramatically as surface area increased. The results showed that pin fin heat sinks with small number of pins had the best performance at low and moderate forced convection cooling.

Analysis of Pin-Fin Heat Sinks With an Unconventional Fin Profile

2013 ◽  
Author(s):  
Jose-Luis Gonzalez-Hernandez ◽  
Abel Hernandez-Guerrero ◽  
Carlos Rubio-Jimenez ◽  
Cuauhtemoc Rubio-Arana
Keyword(s):  
Wave Function ◽  
Pressure Drop ◽  
Thermal Resistance ◽  
Geometric Parameter ◽  
Entropy Generation ◽  
Heat Sink ◽  
Total Pressure ◽  
Heat Sinks ◽  
Pin Fin ◽  
Sinusoidal Function

In this work the performance of pin-fin heat sinks having an unconventional fin profile is compared with the use of cylindrical fins. The fin profile is a sinusoidal function and a staggered array is considered. The overall thermal resistance and total pressure drop are reported for the pin-fin heat sinks. The effect of using a wave function for the fin is studied for different number of complete waves along the height of the fins and a geometric parameter defined as the ratio of the higher to the lower radius of the fins is proposed. The study is carried out for two different inlet velocities, and for two different fin densities, corresponding to 5×5 and 7×7 arrays. An entropy generation analysis for each pin fin heat sink configuration is carried out and reported. The results of the present analysis reveal that the proposed geometry has an improvement as compared to the conventional heat sinks profiles when there is a high number of waves per fin. The effect of the geometric parameters defined in this study for the thermal and hydraulic performance is identified and discussed as well.

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