scholarly journals Hybrid Nanofluid-Based Thermal Fluid–Structure Interaction (FSI) Investigations for the Thermal Management System of a Computer Microprocessor

2021 ◽  
Vol 12 (1) ◽  
pp. 30
Author(s):  
Waseem Amjad ◽  
Adil Nawaz ◽  
Anjum Munir ◽  
Faisal Mahmood
Keyword(s):  
Heat Transfer ◽  
Heat Sink ◽  
Thermal Stresses ◽  
Temperature Drop ◽  
Thermal Characteristics ◽  
Heat Sinks ◽  
Heat Extraction ◽  
Hybrid Nanofluid ◽  
Pin Fin ◽  
Wear And Tear

The heat extraction from and cooling of computer microprocessors are challenging tasks in the modern era. Previously, the microprocessors were usually cooled by air, but now industry is shifting towards using nanofluids, as their properties are more thermo-physically stable. The experimental and numerical studies have revealed that the rate of heat transfer depends both on the thermal characteristics of the coolant and the geometry of the heat sink. For optimized results, it is recommended to analyze the combined effect of nanofluids and the geometry of the heat sink. Mini-channel heat sinks in combination with a nanofluid offered an excellent rate of heat transfer. However, passing nanofluids continuously through the system causes various problems over time; for example, the thermal stresses on the components are increased, which may lead to wear and tear of the system. In this study, a numerical investigation of mini-channel heat sinks was conducted through thermal-FSI. A numerical model was established with airfoil and Savonius pin-fin mini channel heat sinks, and they were analyzed at different flow rates from 0.25 LPM to 0.75 LPM with an increment of 0.25 LPM with different fluids, i.e., water, Al2O3–H2O, and Fe2O3–H2O nanofluids, varying their volumetric concentration. The minimum stresses were obtained while increasing the temperature drop and decreasing the pressure drop. The thermal stresses were calculated using the thermal-FSI technique and were found to be in the threshold range, and hence the material was within the yield limit at 0.75 LPM when using the Fe2O3-H2O Nanofluid at a 0° angle using the Savonius heat sink.

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.

Thermal Optimization of Microchannel Heat Sink With Pin Fin Structures

2003 ◽  
Author(s):  
Duckjong Kim ◽  
Sung Jin Kim
Keyword(s):  
Heat Transfer ◽  
Porous Medium ◽  
Fluid Flow ◽  
Heat Sink ◽  
Volume Averaging ◽  
Heat Sinks ◽  
Pumping Power ◽  
Heat Transfer Characteristics ◽  
Pin Fin ◽  
Flow And Heat Transfer

In the present work, a novel compact modeling method based on the volume-averaging technique and its application to the analysis of fluid flow and heat transfer in pin fin heat sinks are presented. The pin fin heat sink is modeled as a porous medium. The volume-averaged momentum and energy equations for fluid flow and heat transfer in pin fin heat sinks are obtained using the local volume-averaging method. The permeability, the Ergun constant and the interstitial heat transfer coefficient required to solve these equations are determined experimentally. To validate the compact model proposed in this paper, 20 aluminum pin fin heat sinks having a 101.43 mm × 101.43 mm base size are tested with an inlet velocity ranging from 1 m/s to 5 m/s. In the experimental investigation, the heat sink is heated uniformly at the bottom. Pressure drop and heat transfer characteristics of pin fin heat sinks obtained from the porous medium approach are compared with experimental results. Upon comparison, the porous medium approach is shown to predict accurately the pressure drop and heat transfer characteristics of pin fin heat sinks. Finally, surface porosities of the pin fin heat sink for which the thermal resistance of the heat sink is minimal are obtained under constraints on pumping power and heat sink size. The optimized pin fin heat sinks are shown to be superior to the optimized straight fin heat sinks in thermal performance by about 50% under the same constraints on pumping power and heat sink size.

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.

An Experimental Study of Pin Fin Heat Sinks and Determination of End Wall Heat Transfer

2003 ◽  
Author(s):  
Massimiliano Rizzi ◽  
Ivan Catton
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Heat Sink ◽  
Optimization Methods ◽  
Heat Sinks ◽  
Base Region ◽  
Transfer Coefficients ◽  
Media Type ◽  
Pin Fin ◽  
Heat Transfer Coefficients

An experimental study of a pin fin heat sink was carried out in support of the development of heat sink optimization methods requiring more detailed measurements be made. Measurements of heat flux and temperature are used to separately determine heat transfer coefficients for the pins and the base region between the pins. Three pitch to diameter ratios (distance from pin center to pin center measured diagonally) were studied: P/d = 3/1, 9/4, 3/2. Heat generation was accomplished using cartridge heaters inserted into a copper block. The high thermal conductivity of the copper ensured that the surface beneath the heat sink would be at a constant temperature. The cooling fluid was air and the experiments were conducted with a Reynolds numbers based on a porous media type hydraulic diameter ranging from 500 to 25000. The channel had a shroud that touches the fin tips, eliminating any flow bypass. The pin surface heat transfer coefficients match the values reported by Kays and London and by Zukauskas. The base region heat transfer coefficients were, surprisngly, larger than the pin values.

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.

Cooling Performances of Perforated-Finned Heat Sinks

2016 ◽  
Author(s):  
Mohammad Reza Shaeri ◽  
Bradley Richard ◽  
Richard Bonner
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Heat Sink ◽  
Cooling System ◽  
Thermal Characteristics ◽  
Heat Sinks ◽  
Pumping Power ◽  
Maximum Heat ◽  
Maximum Heat Transfer

Cooling performances of perforated-finned heat sinks (PFHS) are investigated in the laminar forced convection heat transfer mode, through detailed experiments. Perforations like windows with square cross sections are placed on the lateral surfaces of the fins. Cooling performances are evaluated due to changes in both porosities and perforation sizes. Thermal characteristics are reported based on pumping power, in order to provide more practical insight about performances of PFHSs in real applications. It is found that at a constant perforation size, there is an optimum porosity that results in the largest heat transfer coefficient. For a fixed porosity, increasing the number of perforations (reducing the perforation size) results in an enhancement of heat transfer rate due to repeated interruption of the thermal boundary layer. The opposite trend is observed for PFHSs with larger perforation sizes. This indicates that there is an optimum perforation size and distance between perforations in order to achieve the maximum heat transfer coefficients at a constant porosity. Also, a PFHS results in a smaller temperature non-uniformity across the heat sink base, as well as a more rapid reduction in temperature non-uniformity on the heat sink base by increasing pumping power. In addition, the advantage of a PFHS to reduce the overall weight of the cooling system is incorporated into thermal characteristics of the heat sinks, and demonstrated by the mass specific heat transfer coefficient.

Thermo-hydraulic performance of modified plate fin and pin fin heat sinks

2021 ◽  
pp. 095765092110240
Author(s):  
Anil Kumar Patil ◽  
Vishwjeet Choudhary ◽  
Ayush Gupta ◽  
Manoj Kumar
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Friction Factor ◽  
Heat Sink ◽  
Hydraulic Performance ◽  
Heat Sinks ◽  
Forced Flow ◽  
Transfer Rates ◽  
Pin Fin ◽  
Pitch Ratio

Extended surfaces are widely investigated for their ability to enhance the heat transfer rates in different applications. Pin-fin and plate-fin heat sinks are used in a variety of cases involving a miniaturized to the large systems. The present study compares the performance of the pin-fin and the plate-fin heat sink under similar forced flow conditions. The experimental data for a modified pin fin heat sink with wings and a plate-fin heat sink with dimples are collected for the Reynolds number in the range of 6800–15100. The Nusselt number, friction factor, and thermo-hydraulic performance (THP) are examined for different geometries of the heat sink and the enhancements brought out in the heat transfer and friction are gauged relative to the smooth plate. The pin fin heat sink yields two-fold enhancement in heat transfer as compared to the plate-fin heat sink. The maximum thermo-hydraulic performance of the pin-fin heat sink with wings is found to be 4.52 at a pitch ratio (S/Df) of 2 and Wing length ratio (Lw/Df). For the plate fin heat sink with dimples, the maximum thermo-hydraulic performance is found to be 4.67 at dimple diameter ratio (D/d) of 0.5 and dimple pitch ratio (s/d) of 2.5. The correlations of the Nusselt number and friction factor are proposed for different geometries of fins.

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.

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.

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