Pin Fin Heat Sink Research Articles

Numerical study of the fluid dynamics and heat transfer for shear-thinning nanofluids in a micro pin-fin heat sink

The ability to enhance heat transfer rates of shear-thinning fluids in microchannel devices is evaluated numerically for steady and time-dependent flows in the range of 400 < Re < 2000. The geometry used represents a simplified micro pin-fin heat sink device with a staggered circular pin arrangement. The working fluids are composed by water and ethylene-glycol with different kinds of nanoparticles and concentrations. Four Newtonian and five non-Newtonian nanofluids are evaluated in detail, focusing on their rheological behavior, the heat extraction capacity, and the fluid dynamics developed for each flow condition. The nanofluids studied are extracted from experimental articles, and they are characterized as shear-thinning power-law ones with power-law indexes in the range 0.4946 <n < 0.69. Comparisons of heat-flux between the inlet and the outlet of the microchannel are investigated for nine different Reynolds numbers. Additionally, the pressure drop was evaluated for each case. The results show that the shear-thinning behavior of the nanofluids is the most critical factor in enhancing heat transfer rates due to the promotion of unsteady flows even for low Reynolds number values and a reduction of pressure drop. A large number of numerical tests are presented and carefully analyzed to justify our claims.

Elliptical Pin Fin Heat Sink: Passive Cooling 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&gt; 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.

A novel designed manifold ultrathin micro pin-fin channel for thermal management of high-concentrator photovoltaic system

To meet the requirements of cooling challenges of high concentrator photovoltaic (HCPV), a novel manifold ultrathin micro pin-fin heat sink (MUMPFHS) cooling technique is developed in this study. A comprehensive three-dimensional simulation model is established to investigate the thermal, energy and exergy performance of 10 × 10 mm2 HCPV cells cooling with MUMPFHS, using Star CCM+ with the help of user defined field functions. Compared with the previously proposed designs of the HCPV cooling schemes using jet impingement, hybrid jet impingement/microchannel and stepwise varying width microchannel, the present one shows great advantages of both uniform solar cell temperature and high cooling performance under a high solar concentration of 1000 suns. At inlet flow rate of 3 kg/h and temperature of 25 °C, the solar cell temperature can be reduced to 51 °C, with a small temperature non-uniformity of 3.4 °C. As the inlet flow rate increases, the average cell temperature and its non-uniformity further decrease, resulting in a higher electrical efficiency. However, the inlet coolant temperature has little impact on the cell temperature uniformity, allowing maximizing the inlet temperature to improve the thermal exergy efficiency under the recommended temperature range. In addition, five different designs of inlet/outlet plenums are proposed and integrated on the MUMPFHS, which could achieve a uniform flow distribution in each manifold channel. Thermal and exergy analysis confirms that taking the plenums into consideration increases the friction power which can be compensated by the improvement of electrical power due to the decrease of solar cell temperature. The present simulation results indicate that our designed MUMPFHS could increase the feasibility of using HCPV under higher solar concentration with safe operation.

Effect of air fan position on heat transfer performance of elliptical pin fin heat sink subjected to impinging air flow

Heat rejection from electronic components by heat sink is still a viable cooling solution. The optimal heat sink design enables higher heat transfer performance. The purpose of the present study is to predict the effectiveness of heat sink elliptical closely spaced fins subjected to impinging air cooling. The air fan is the main source of impinging air, then its position and direction with the heat sink take the main role in present work. Two positions of fan location are studied. The first position where the fan is outside the heat sink and the second case where the fan is existed in a cut out template. So there are one impinging air inlet with four transverse outlets and one axial exit opposite to the air flow inlet. Reynolds number were taken at a range 3400-16000, the flow was turbulent so k-ϵ model turbulence model was used as our choice to simulate mean flow characteristics for turbulent flow conditions. The heat sink base was subjected to constant heat flux condition and proposed with range between 10000–40000 kW/m2 to keep the base temperature at a temperature around 100 oC. The Results of temperature contour lines depicted a variation from the base to the extended surfaces tips. The comparison between the two cases results showed high temperature difference in the case with the cut out template. Nusselts numbers indicated that the second case performed better in heat transfer than the first case. The experimental and numerical results showed a good agreement with a difference not exceeding 2%.

Heat transfer and pressure drop in turbulent nanofluid flow in a pin-fin heat sink: Fin and nanoparticles shape effects

In this paper, the turbulent flow of a nanofluid in a channel is simulated in the presence of a pin-fin heatsink. Pin fins have different shapes, including hexagonal, circular, square, and triangular that are considered in two different arrangements. Constant heat flux is applied to the heatsink from its bottom due to the operation of an electronic chip. The nanoparticles suspended in water are alumina, which are in different shapes such as blades, bricks, cylinders, and plates. Their shape effect is investigated. The nanofluid enters the channel at a constant velocity in the range of 1–3 m/s and a constant volume percentage of 2%, and exits after cooling the pin-fin heatsink. The standard k-ε turbulence model is used to model turbulent flow, and the SIMPLEC method is employed to linearize the equations. The variables include fin type, fin arrangement, nanoparticle shape, and nanofluid velocity. Their effect on the maximum and average heatsink temperature and pressure drop (ΔP) is studied. The results show that increasing the velocity leads to a reduction in heatsink temperature, and the use of brick-shaped nanoparticles and circular fin results in the best cooling performance. Also, the use of circular fin and brick nanoparticles requires less ΔP than other cases.

A comprehensive study on parametric optimization of the pin-fin heat sink to improve its thermal and hydraulic characteristics

In an effort to reduce the highest temperature of electronic pieces, using high performance cooling systems is required, and for this reason, optimization is one of the most essential and attractive issues that has an undeniable role in industry and technology. In this study, a finite volume method is employed to numerically simulate conjugate heat transfer in pin-fin heat sinks, which are of the most common cooling systems, and all the geometric parameters affecting their performance are optimized based on thermal and hydraulic performances (FOM). These geometric parameters are: the number of fins, the fin height, the fin diameter, and the transverse pitch. It will be shown that the total performance of the pin-fin heat sink improves step by step by optimizing these parameters. Also, it will be suggested that the shape of pin-fins changes to a tapered one. It is proved that changing the fin shape has a significant influence on the convective heat transfer coefficient and pressure drop and enhances the total performance of the system. Furthermore, it is observed that the total performance of the pin-fin heat sink increases more than 17% during the stages of the optimization.

The effect of inlet/outlet number and arrangement on hydrothermal behavior and entropy generation of the laminar water flow in a pin-fin heat sink

A numerical analysis was performed to evaluate the hydrothermal performance of a pin-fin mini-channel heatsink (MCHS) with six different inlet/outlet flow arrangements from the first and second laws of thermodynamics point of views. The results are presented in terms of several important parameters such as convective heat transfer coefficient (h), CPU mean temperature (Tm, CPU), pumping power (Ẇp), frictional and thermal entropy generation rates (Ṡfr and Ṡth) as well as Performance Evaluation Criterion (PEC). The results demonstrated that configurations with two inlets and outlets have the lowest Ẇp, Ṡfr, h, and highest Tm, CPU among the studied cases. The vorticity intensification is high at the inlet/outlet headers and over the pin-fin bodies for the case with one inlet from the left and two outlets located at opposite sides, namely configuration d. The highest values of Ṡfr and h, the lowest value of Tm, CPU, and a moderate value of Ẇp are obtained for configuration d as compared to the other studied cases. In consequence, the maximum PECs (1.61–2.20) is obtained for case d at different Re numbers (500–2000). The PEC of configuration d is nearly 19.77% higher than those of configurations with two inlets and two outlets. Also, the PEC of configuration d is nearly 66.95% higher than those obtained for two other configurations with one inlet and two outlets.

Effect of pin fin configuration on thermal performance of plate pin fin heat sinks

Flow behavior and heat transfer characteristics of air flow inside the plate pin fin heat sinks (PPFHS) are presented. The effects of pin fin shape, pin fin orientation, and ratio of distance between pin and plate fin center to pin fin size (S/Dp or S/Wp) on the flow pattern, heat transfer coefficient (HTC), pressure drop (ΔP) and thermal performance are investigated. Three types of pin fin shape, including a circular pin, square pin, and 45° square pin with pin fin sizes of 2.5, 3.0, and 3.5 mm, are used. The flow visualization used smoke to study the air flow behavior inside the PPFHS. The test runs were done at a heat flux of 14.81 kW/m2 and Reynolds number (Re) ranging between 1700 and 5200. Under the same pin fin frontal area, the HTC and ΔP of air inside the plate square pin fin heat sink (PSPFHS) was higher than that from the plate circular pin fin heat sink (PCPFHS) by an average of 12.52 and 15.05%, respectively. The decrease of the S/Dp or S/Wp from 2.25 to 1.61 caused the augmentation of the HTC and ΔP of air flow inside the PPFHS by about 11.77%–17.17% and 46.61%–50.52%, respectively. The average thermal performance factors (TPF) were 1.32, 1.44, and 1.42 for PCPFHS, PSPFHS, and the plate 45° square pin fin heat sink (P45oSPFHS), respectively. The correlations for Nusselt number (Nu) and friction factor (f) were also proposed.

Multi-objective NSGA-II based shape optimisation of the cross-sectional shape of passively cooled heat sinks

PurposeThe purpose of the study is to optimise the cross-sectional shape of passively cooled horizontally mounted pin-fin heat sink for higher cooling performance and lower material usage.Design/methodology/approachMulti-objective shape optimisation technique is used to design the heat sink fins. Non-dominated sorting genetic algorithm (NSGA-II) is combined with a geometric module to develop the shape optimiser. High-fidelity computational fluid dynamics (CFD) is used to evaluate the design objectives. Separate optimisations are carried out to design the shape of bottom row fins and middle row fins of a pin-fin heat sink. Finally, a computational validation was conducted by generating a three-dimensional pin-fin heat sink using optimised fin cross sections and comparing its performance against the circular pin-fin heat sink with the same inter-fin spacing value.FindingsHeat sink with optimised fin cross sections has 1.6% higher cooling effectiveness than circular pin-fin heat sink of same material volume, and has 10.3% higher cooling effectiveness than the pin-fin heat sink of same characteristics fin dimension. The special geometric features of optimised fins that resulted in superior performance are highlighted. Further, Pareto-optimal fronts for this multi-objective optimisation problem are obtained for different fin design scenarios.Originality/valueFor the first time, passively cooled heat sink’s cross-sectional shapes are optimised for different spatial arrangements, using NSGA-II-based shape optimiser, which makes use of CFD solver to evaluate the design objectives. The optimised, high-performance shapes will find direct application to cool power electronic equipment.

Integration of multi-objective reliability-based design optimization into thermal energy management: Application on phase change material-based heat sinks

Phase change material-based heat sinks are widely used in several industrial applications such as in the field of industrial automation and mechatronics. Nowadays, several researchers aim to obtain an optimal design of these systems in order to ameliorate its performances. Nevertheless, uncertainties are not considered for the majority of these studies. Furthermore, it has been confirmed that deterministic multi-objective optimization (DMOO) may lead to an unreliable design. In this study, a new methodology that leads to perform the Multi-Objective Reliability-Based Design Optimization (MORBDO) for thermal management of a passive cooling system is proposed. It consists in coupling the Finite Element Model (FEM), MORBDO procedures and surrogate approaches. Kriging predictor is used to construct metamodels and then validated using Cross-Validation (CV) and error predictions. A numerical investigation is carried out to study the different DMOO and MORBDO approaches. In this study, a 3D PCM-based round pin-fin heat sink is detailed. The aim of this problem is to minimize two objective functions: the cost (total volume V) and the final cooling time tf by considering both thermal and physical constraints. For this purpose, geometrical uncertain parameters are considered such as length L, height H and ϕ pin diameter of the heat sink. This study leads to develop a well-distributed reliable Pareto solutions by combining the Robust Hybrid Method (RHM) and the Constrained Non-dominated Sorting Genetic Algorithm (C-NSGA-II). Then, the efficiency of the proposed MORBDO-RHM approach for PCM-based heat sink is verified.

Effects of pin fin height, spacing and orientation to natural convection heat transfer for inline pin fin and plate heat sinks by experimental investigation

In this work, pin fin and plate heat sinks were investigated in terms of natural convection and radiation heat transfer by experimental means. One rectangular base plate and eight pin fin and plate heat sinks were manufactured particularly for this study. Eight different pin fin and plate heat sinks had four different pin fin numbers and hence pin fin spacings; and two different pin fin heights. Three different orientations of 0°, 90° and 180° were tested. Ten different constant heating rates were applied to heat sinks during tests, corresponding to Rayleigh number interval between 1 × 106 and 7 × 106. Heating powers were changed between 5 and 50 W by 5 W increments by means of DC electrical power source. All cases were compared with each other. Results were evaluated by calculating heat transfer indicators from experimental measurements, dependent Nusselt and Rayleigh numbers, and by drawing their corresponding graphics. It was detected that increasing pin fin number up to a threshold value increases thermal performance. After the threshold pin fin number, thermal convection coefficient decreases significantly. Up to the favourable highest pin fin number, the reason of thermal performance enhancement is due to increasing surface area without deteriorating thermal convection coefficient significantly. It is also seen that extended surface area by increasing number of pin fins partly compensates the reduction in thermal convection coefficient up to a level. However, increasing pin fin number further degrades heat transfer performance. Results show that the highest heat transfer is achieved by 121 × 40 pin fin and plate heat sink for all three orientation angles. The lowest heat transfer performance is realized by non-pinned plate. When plate orientation is considered, the highest heat transfer is achieved with upward facing orientation which has 0° orientation angle value, and the lowest heat transfer rate is realized with downward facing heat sink which has 180° orientation angle value. Therefore, it is concluded that inline pin fin and plate heat sinks are best used with upward orientation with optimum number of pins. Experimental dataset was analysed in terms of parametrical effects and accordingly empirical correlations expressions were composed and proposed.

Assessment of heat transfer and pressure drop of metal foam-pin-fin heat sink

Numerical investigation on Metal Foam Pin-Fin Heat Sink (MFPFHS) has been conducted and compared to the traditional Solid Pin-Fin Heat Sink (SPFHS). For investigating turbulent convection heat transfer and friction factor characteristics in the MPFHS, the 3D steady continuity, momentum, and energy equations are discretized using the finite volume approach. The key parameters investigated here are; the pin diameter ratio (DR) i.e., reducing the upper diameter and increasing the lower diameter simultaneously, the number of pins and the pins’ height ratio (HR) i.e., reducing the pin height and increasing its diameter simultaneously. The overall pin volume is retained constant throughout the whole study. The results show that (i) the MFPF exhibit a superior enhancement in the heat dissipation and reduction in the frictional losses compared to the solid pin-fin (SPF), (ii) a great heat transfer and PEC enhancement is observed when DR increases associated with a decrease in the friction factor, (iii) heat transfer and performance evaluation criteria (PEC) enhancement (with a maximum value of 3.7) is obtained when the number of MFPF increases with a large decrease in the friction factor, (iv) high augmentation in PEC with a peak value of 3.8 but up to a certain value is seen, however, with an association of high increase in the friction factor.

CFD simulation of the impact of tip clearance on the hydrothermal performance and entropy generation of a water-cooled pin-fin heat sink

In this paper, the 3D numerical calculations of the water flow inside a pin-fin heat sink (PFHS) to determine the influence of tip clearance on the hydrothermal behavior and frictional & thermal irreversibilities of the fluid flow. The numerical simulations were conducted for five different fin heights (ξ = 1.5 mm to 2.5 mm) considering four different Reynolds numbers (Re=500, 1000, 1500, and 2000). The results demonstrated that the highest heat transfer coefficient is associated with ξ = 2.25 mm due to more uniform vorticity distributions, while the minimum central processing unit (CPU) average temperature is obtained for ξ = 2.5 mm due to the higher heat transfer surface area. The minimum thermal and frictional entropy generation rates are associated with PFHS with ξ = 1.5 mm. However, the PFHS with ξ = 2.25 mm has the highest Performance Evaluation Criterion (PEC) of nearly equal to 1.28 as compared to the other ξs. Besides, the fluid flow from the pin-fin base to the top and vice versa leads to create the vortices especially at the entrance of the PFHSs with tip clearance.

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

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.

Correction to: Performance evaluation of perforated pin fin heat sink using particle swarm optimization and MCDM techniques

Correction to: Performance evaluation of perforated pin fin heat sink using particle swarm optimization and MCDM techniques

Performance evaluation of perforated pin fin heat sink using particle swarm optimization and MCDM techniques

Performance evaluation of perforated pin fin heat sink using particle swarm optimization and MCDM techniques

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

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.

Thermal optimization of the pin-fin heat sink with variable fin density cooled by natural convection

Abstract Thermal performance of the pin-fin heat sink cooled by natural convection is numerically investigated when the fin density is allowed to vary along the flow direction. The distribution of the fin density is thermally optimized by using a compact modeling method, in which the pin-fin heat sink is modeled as a fluid-saturated porous medium. In the porous region, the volume-averaged governing equations are used; the Brinkman-Forchheimer-extended Darcy equation for fluid flow and the one-equation model for heat transfer. Based on the analogy between convective heat transfer between the fin and air and that carried by the fluid flowing through the porous medium, a new model for the effective thermal conductivity is proposed. The proposed model is validated by the experimental data available in literature and the numerical results obtained from a direct numerical simulation. For minimal thermal resistance, optimization is conducted using the Kriging method under the constraint of fixed base plate and fin height dimensions. As a result, the optimal distribution of the fin density is obtained as a function of the porosity ( ϕ ) along the flow direction. The optimal distribution of the fin density is found to be monotonically increasing from ϕ = 0.898 to ϕ = 0.946 , which indicates the densely-populated fins in the lower part and the coarsely-populated fins in the upper part. Consequently, the optimized pin-fin heat sink with variable fin density has 11% lower thermal resistance and 30% less weight than those of the uniformly-populated pin-fin heat sink with ϕ = 0.891 optimized using an existing correlation. This study suggests that varying the fin density is very useful to not only improving the thermal performance but also reducing the weight of the pin-fin heat sink cooled by natural convection.

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

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.

Computational analysis of perforation effect on the thermo-hydraulic performance of micro pin-fin heat sink

This paper investigates the hydrodynamic and thermal characteristics of perforated micro pin-fin (MPF) heat sink with different shapes and numbers of perforations under a low range (100–1000) of Reynolds number (Re) and constant base wall heat flux thermal boundary condition with air as the working fluid. The results show that the perforated MPFs provide higher Nusselt number (Nu) values and lower pressure drop levels (ΔP) than a solid MPF. These perforations have also shown higher fin effectiveness compared to solid square-shaped MPFs. Besides, the perforated MPFs show a superior performance (i.e., ≥45%) than solid MPFs. This study also infers that the circular-shaped perforation offers the best system performance (η) amidst the all different perforation shapes irrespective of the perforation number, followed by the elliptical and square-shaped perforation. For the circular-shaped perforation, performance improves by 30% when going from one to two perforations, and it improves up to 28% while moving from two to three perforations. This study reveals that there is a greater potential to employ circular perforation on a solid square MPF heat sink for better thermal management in electronic devices.