Pin Fin Heat Research Articles

Quantifying turbulence model uncertainty in Reynolds-averaged Navier–Stokes simulations of a pin-fin array. Part 2: Scalar transport

The accuracy of Reynolds-averaged Navier-Stokes results for turbulent scalar transport are affected by epistemic uncertainty in the Reynolds stress model in two ways: by altering the mean velocity field that advects the scalar, and by altering the inputs required for scalar flux models. We investigate these effects by propagating uncertainty in the Reynolds stress model to the prediction of scalar quantities in simulations of a pin-fin heat exchanger. The Reynolds stress model uncertainty is quantified by perturbing the anisotropy of the predicted stress tensor towards the three limiting realizable states. This uncertainty is then propagated to the scalar turbulence transport via the conservation law for the mean scalar and the turbulent scalar flux model. We consider three different scalar flux models that explicitly take the Reynolds stresses as input, and evaluate the performance of the models by verifying if high-fidelity large eddy simulation results are encompassed by the model predictions. The results indicate that the predicted uncertainty depends on both the general level of momentum transport and the most-relevant stress component, which is affected by the anisotropy perturbations. The predictions provide a similar bounding behavior for the overall temperature field as for the momentum field, but fail in bounding the local heat transfer rates in several locations. The bounding behaviors are further analyzed in terms of the predicted uncertainty in the flux magnitude, direction, and divergence to identify opportunities for further improvement of the proposed methods.

Performance of drop shaped pin fin heat exchanger with four different fin dimensions

In engineering, there are two primary heat transfer procedures of fluids namely, heating and cooling within a conduit that are well recognized. The heat transfer literacy remains a core component to design the heat exchangers. The study aims to present the consequences of drop shaped pin fin hear exchanger performance with four different fin dimensions. A rectangular duct with different drop-shaped pin fins dimensions is present in the heat exchanger, having similar heat transfer wetted surface area. ANSYS FLUENT 14.5 conducted three-dimensional finite volume to select the optimum pin fin dimension. The numerical results for the four cases L/D 1, 1.25, 1.5 and 1.75 indicated heat transfer had no effect on the variations in pin tail length; however, it affected frictional losses or pressure drop. There is significant decrease in the frictional loss as the result of increase in the pin tail length. The pun fin drop showed significant decrease in friction power, unlike the round pins. The ratio of pin height to the cylindrical portion of the pin (H/D) had major impact on the wetted surface area, which affects the rate of heat transfer.

Numerical Simulation of Natural Convection Heat Transfer using Solid and Hollow/Perforated Pin Fin Heat Sinks

Free convection heat transfer from circular solid and hollow/perforated pin fin heat sinks with different geometry and heat flux is numericallystudied using FLUENT ANSYS 16.0. The geometric dependence of heat transfers from heat sinks of solid and hollow/perforated fins with staggered pattern, attached on a fixed area heated base plate is discussed. A SIMPLE code is developed using control volume approach to solve governing equations (mass, momentum and energy), and the second order upwind technique is used. The results were carried out for a range of Rayleigh number, 9.3×106> Ra> 1.63×107. It showed that the performance of the hollow/perforated fin heat sink is higher than that for the solid fin heat sink. It is also investigated that hollow/perforated fin array with inner-to-outer diameter ratio (Di/Do=1/2) and perforation diameter (dp =6 mm) is the best sample giving the maximum performance and less amount of weight compared to the corresponding solid ones

Thermal Performance of Metal Foam Heat Sink With Pin Fins for Nonuniform Heat Flux Electronics Cooling

Abstract In this paper, a concept of metal foam heat sink with pin fins (MFPF heat sink) is proposed to improve the cooling performance of high-powered electronics with nonuniform heat flux. Numerical simulations are carried out to investigate the thermohydraulic performance of MFPF heat sink, and the metal foam (MF) heat sink and traditional pin fin (PF) heat sink are employed for comparison. The capability of MFPF heat sink in handling nonuniform heat flux is examined under different power levels. It indicates that the MFPF heat sink greatly enhances the heat transfer performance, due to the common effects of the improved flow distribution and enhanced overall effective thermal conductivity (ETC). Results also show that the MFPF heat sink promotes the improvement of the bottom wall temperature uniformity. Porosity has more pronounced effects on heat transfer performance of MFPF heat sink than pore density. A nonuniform distribution heat flux (15–80–15 W/cm2) can be successfully dissipated using the proposed MFPF heat sink with the junction temperature below 95 °C at Re of 500.

A novel composite pinfin heat sink for hotspot mitigation

A power-efficient composite pinfin heat sink has been introduced to mitigate the temperature non-uniformity in a microprocessor with heterogeneous heat flux distribution. The proposed composite design was evaluated numerically, and its performance was compared with a non-composite design. The concept utilizes the difference in thermal conductivities of different metals to develop an efficient cooling solution. The heat sink was divided into two zones (hotspot zone and background zone) according to the heat flux distribution. Copper and aluminum were selected for the hotspot and background zones, respectively. The non-composite heat sink was designed with exactly the same geometric parameters, however, aluminum was used for the background as well as the hotspot zone. Both designs (composite and non-composite) were analyzed at different flow rates and heating conditions. The temperature non-uniformity, temperature rise, thermal resistance, and pumping power were evaluated to compare their thermohydraulic performances. The composite heat sink showed substantial enhancement in the thermal performance without any change in the pumping power.

New Approach of Triumphing Temperature Nonuniformity and Heat Transfer Performance Augmentation in Micro Pin Fin Heat Sinks

Abstract This study is the first part of the development of improved micro pin fin heat sink (MPFHS) for the thermal management of modern microprocessor chip cooling. In the current numerical study, a new fluid flow distribution scheme for MPFHS has been proposed for triumphing over surface temperature nonuniformity problem—one of the most critical issues interfering with the thermal management of modern microprocessors chip cooling. It is established that fluid, if supplied from the confronting sides (front/side directions) of the MPFHS, helps in mitigating temperature nonuniformity and intensifies heat transfer rate. Fluid starts enjoying following paybacks on account of proposed change: the benefits of the developing flow even in adverse temperature zones of the conventional design, enriched secondary channels fluid flow, and rigorous mixing of the cooling fluid between the primary and the secondary channels. Two front facing multi-inlet designs (MPFHSMI,F and MPFHSMI,FH) and one side facing multi-inlet design (MPFHSMI,SH) are conceptualized and compared with the conventional design MPFHSCD. Base surface temperature nonuniformity reduces 7.6 °C, 24 °C, and 7.4 °C by the MPFHSMI,F, MPFHSMI,FH, and MPFHSMI,SH designs, respectively. Average Nusselt number for the cases MPFHSMI,F, MPFHSMI,FH, and MPFHSMI,SH is found 26.7%, 52.3%, and 70.9% higher than the conventional design of MPFHS. Overall thermal performance factor of one design MPFHSMI,FH is found 1.66 at the applied heat flux of 125 W/cm2.

Constructal design progress for eight types of heat sinks

This review paper summarizes constructal design progress performed by the authors for eight types of heat sinks with ten performance indexes being taken as the optimization objectives, respectively, by combining the methods of theoretical analysis and numerical calculation. The eight types of heat sinks are uniform height rectangular fin heat sink, non-uniform height rectangular fin heat sink, inline cylindrical pin-fin heat sink (ICPHS), plate single-row pin fin heat sink (PSRPHS), plate inline pin fin heat sink (PIPHS), plate staggered pin fin heat sink (PSPHS), single-layered microchannel heat sink (SLMCHS) with rectangular cross sections and double-layered microchannel heat sink (DLMCHS) with rectangular cross sections, respectively. And the ten performance indexes are heat transfer rate maximization, maximum thermal resistance minimization, minimization of equivalent thermal resistance which is defined based on the entransy dissipation rate (equivalent thermal resistance for short), field synergy number maximization, entropy generation rate minimization, operation cost minimization, thermo-economic function value minimization, pressure drop minimization, enhanced heat transfer factor maximization and efficiency evaluation criterion number maximization, respectively. The optimal constructs of the eight types of heat sinks with different constraints and based on the different optimization objectives are compared with each other. The results indicated that the optimal constructs mostly are different based on different optimization objectives under the same boundary condition. The optimization objective should be suitable chosen based on the focus when the constructal design for one heat sink is performed. The results obtained herein have some important theoretical significances and application values, and can provide scientific bases and theoretical guidelines for the thermal design of real heat sinks and their applications.

Performance Improvement of Photovoltaic Module Using an Air-Cooling Micro Finned Heat Sink

In this work, improved PV panel was fabricated by replacing the tedlar layer with aluminum alloy micro pin fin heat sink to increase the heat transfer conduction. Air flow system was designed and implemented to apply force convection on the heat sink, which named MPFHS-PV/T integrated system, to decrease the PV module temperature. The integrated system was tested on 25Jun 2019 in Baghdad climate and the results recorded as flowing: decreasing the PV module temperature by 14.65% along with electrical performance improvement by 13% for the output power and 13.32% for efficiency. The daily averages of electrical efficiency. 1102%, thermal efficiency 40.94% and overall thermal efficiency 51.9%.

A surrogate assisted thermal optimization framework for design of pin-fin heat sink for the platform inertial navigation system

ABSTRACT In this study, a thermal optimization framework for the platform inertial navigation system (PINS) is built. To reduce the local high temperature of the PINS, a pin-fin heat sink with staggered arrangement is designed. To reduce the dimension of the inputs and improve the optimization efficiency, a feasible global sensitivity analysis (GSA) based on kriging–high-dimensional model representation with DIviding RECTangles (DIRECT-KG-HDMR) sampling strategy is proposed. According to the GSA results, the filtered structural parameters are used to optimize the thermal performance of the heat sink, and several optimization algorithms (genetic algorithm, differential evolution, teaching–learning-based optimization, particle swarm optimization and efficient global optimization) are used for optimization. The steady thermal response of the PINS with the optimized heat sink is also studied, and the result shows that the maximum temperature of the high-temperature region of the platform is reduced by 1.08°C compared with the PINS without the heat sink.

Optimization of pin perforation(s) induced flow dynamic for effective thermal dissipation

This study numerically investigates the 3D perforated pin-fin heat sink forced convection and the induced flow dynamics at Reynolds number ranging between 10 × 103<ReDh < 50 × 103 (Dh represents the hydraulic diameter). The preferences of single perforated pin diameter along pin diameter of Dpin/Dh = 0.188, 0.375 and 0.563, as well as the effect of multiple perforations N on pin of Dpin/Dh = 0.375 and N = 5 are studied. Response surface optimization is incorporated with two-equation turbulence model to explore the correlation between pin perforation diameter and the respective thermal dissipative preferences. Nusselt number maximization serves as the single-objective function to unveil the efficacy of optimized perforated pin-induced flow recirculation. Results show that optimum pin perforation diameter Dpf,opt exists as a function of Dpin and ReDh. Dpf,opt increases with larger Dpin but decreases at higher ReDh, owing to the size of flow recirculation induced leeward from pin. The ratio of Dpf,opt/Dpin is larger for smaller pin to effectively restructure the wider wakes coverage. The optimized flow dynamic in the lee from a perforated pin of Dpf = Dpf,opt is able to strengthen the thermal interaction within the perforation(s), weaken the capability of flow recirculation in trapping thermal energy, as a consequence, provide the most predominant thermal dissipation. Additionally, optimized pins of smaller Dpin and higher N value are more efficient in retrieving back the overheated situation to the targeted low temperature regime in a timely manner.

Numerical Study of Heat Transfer Performance of Pin Fin by Shape Modification

Rate of heat transfer is an important parameter of heat exchangers, mostly it is affected by fins geometry. To achieve maximum heat transfer, shape of the fins plays a major role. In the present work an attempt is made to study the heat transfer performance in terms of temperature difference and pressure drop of pin fin heat sink with constant base heat flux is studied using commercial CFD software (ANSYS). Three geometries of pin fin have been designed by keeping the same cross-sectional area. CFD analysis have been carried out in both free and forced convection with transient formulation. Results have been compared with circular shape fin.

Automatization of Pin Fin Heat Sink Design with Geometric and Fluid Constraints

Automatization of Pin Fin Heat Sink Design with Geometric and Fluid Constraints

Second Law Analysis and Optimization of Elliptical Pin Fin Heat Sinks Using Firefly Algorithm

One of the most significant considerations in the design of a heat sink is thermal management due to increasing thermal flux and miniature in size. These heat sinks utilize plate or pin fins depending upon the required he... | Find, read and cite all the research you need on Tech Science Press

Experimental and Numerical Study Upon Uniformity of Impingement Cooling With Pin-Fin Heat Sink

In this paper, the impingement cooling performance on pin-fin heat sinks is experimentally and numerically investigated with different outlet arrangements and pin-fin layouts. Compared with one-way opening arrangement, results show that the two-way opening arrangement can offer a much lower pressure loss ( $\Delta p$ ) due to shorter flow distance of airflow from outer jets. Meanwhile, it is surprising that the two-way opening arrangement still offers appreciable improvements on effective heat transfer coefficient ( $h_{\mathrm {eff}}$ ). This is because the fountain may shift toward the outer jets more rapidly with one-way opening arrangement. Yet the implementation of staggered pin-fin layout has minor improvement on $h_{\mathrm {eff}}$ . However, $\Delta p$ can be obviously reduced by 11.1% due to the more effective spreading of impinging airflow in radial direction. The $h_{\mathrm {eff}}$ value can be further increased by 8.8% when a smaller jet-to-target distance is applied. With priority consideration of hot spots in electronic cooling, the nonuniformity of local Nusselt number ( ${S}$ ) is further studied through the computational fluid dynamics (CFD) method. ${S}$ approaches 18.5% when the airflow directly impinges on a flat surface with optimized jet array. Implementing pin-fin heat sinks can reduce the nonuniformity of Nusselt number distribution to fall below 8.0%. The nonuniformity of local Nusselt number can be further reduced to 1.8% by applying four-way opening arrangement and larger central jet at the same time.

Numerical investigation on hydraulic and thermal characteristics of micro latticed pin fin in the heat sink

Micro pin fin heat sinks are an indispensable component in high-power electronic devices that are intended to enhance the device's thermal performance. In this study, the combination of conventional pin fin and lattice structure are used to propose a new design of micro latticed pin fin. The thermal performance and the impacts of the flow states and morphological types on the new design are investigated through fluid-thermal coupled numerical approach.The results reveal that overall pressure loss shows a slight improvement by using the latticed pin fin when compared with a solid pin fin. However, only a cubic body-centered-cubic pin fin has a positive influence on hydraulic and thermal performance, using a vertex cube achieves the opposite results. In terms of weight reduction, using the latticed pin fin can reduce the volume of the heat sink by approximately 14%-17%. Considering both pressure loss and Nusselt number (Nu), the improvement of the thermal-hydraulic performance index (η) of the BCC-PF (cubic body-centered-cubic pin fin) heat sink is more than 140% compared with the conventional pin fin heat sink.

Effects of passage divider and packed brass beads on heat transfer characteristic of the pin-fin heat sink by water cooling

In this study, a design of an aluminum alloy pin-fin heat sink with the passage divider and the packed brass beads was proposed. The effects of the passage divider and packed brass beads on the overall heat transfer performance of the pin-fin heat sink under forced convection with water cooling was investigated experimentally. The heat sink is made of an aluminum alloy square cavity with the in-line square pin fins as the basic configuration. Among them, the number of pin fins (4 × 4, 3 × 3, 2 × 2, 0 × 0) and the height of pin fins (H = 5, 10, 20 mm) are variables. The filled brass beads have three particle sizes (d = 4, 6 and 8 mm), and the passage divider designs are divided into 2 types, namely, left-and-right S-shape divider and up-and-down S-shape divider. The results indicate that for the heat sink with the passage divider but no filled with brass beads, the passage divider has a significant heat transfer enhancement for the 4 × 4 and 3 × 3 pin-fin heat sink. Especially for the 3 × 3 pin-fin heat sink added with the up-and-down S-shape divider, the heat transfer enhancement is up to 60%. For the heat sink with the passage divider and filled with brass beads, when adding the same passage divider, compared with the test case without filled with the brass beads, the filling of brass beads (d = 4 mm) has a significant heat transfer enhancement for the heat sink with H = 5 and 10 mm. It increases the heat transfer by an average of about 14%. Therefore, in the test case, the 3 × 3 pin-fin heat sink (H = 10 mm) added with the up-and-down S-shape divider and filled with brass beads (d = 4 mm) has the most significant heat transfer enhancement, and the overall Nusselt number increases by about 65% compared with the heat sink without the passage divider and brass beads.

Feasibility demonstration of µEDM for fabrication of arrayed micro pin-fins of complex cross-sections

Thermal management in microelectronics components through micro pin-fins heat sinks is well understood. This work aims to propose an unexplored methodology for fabrication of such MPFs having cross-sections in shapes of droplet, aerofoil, piranha and diamond of dimensions as less as 200 µm and height up to 1200 µm. Density of these pin-fins has been achieved more than 4 pins/mm2 on brass plates. The methodology is basically a retrieval of µEDM which has been combined with LASER micromachining to achieve the goal. Research directions for possible improvement in ‘quality of the pin-fins’ and ‘material removal rate’ have been proposed at the end.

Enhanced heat transfer in pin fin heat sink working with nitrogen gas–water two-phase flow: variable pin length and longitudinal pitch

In the current study, thermal–hydraulic characteristics of nitrogen gas–water two-phase flow through a plate–pin fin heat sink are investigated experimentally. Water flow through the smooth case, i.e., heat sink without pin fin, is considered as baseline. Four new models of the pin fin with variable longitudinal pitch and pin length having low-to-high and high-to-low arrangements are proposed. They are named for short as LP–LH, LP–HL, PL–LH, and PL–HL. The results indicate that in all heat sinks, the Nusselt number values of the two-phase flow in comparison with those of the single-phase flow are higher, but the friction factor values of the two-phase flow in comparison with those of the single-phase flow are lower. Also, the friction factor and the Nusselt number of both the single-phase flow and the two-phase flow in the heat sinks with pin fin are greater than those in the heat sink without pin fin. The highest values of the Nusselt number are recorded for PL–HL at water mass flow rate of 0.0093 kg s−1 and gas volume flow rate of 0.8 L min−1. At these flow rates in PL–HL, the Nusselt number of the two-phase flow is increased about 45.6% relative to the single-phase flow.

Hydraulic and thermal performances of metal foam and pin fin hybrid heat sink

In this study, a metal foam and pin fin hybrid heat sink (MFPFH heat sink) is proposed for thermal management of high powered electronic devices. Thermo-hydraulic performance of MFPFH heat sink is numerically investigated under local thermal non-equilibrium condition, and compared with metal foam (MF) heat sink and traditional pin fin (PF) heat sink. Influences of MF morphological parameters on flow and heat transfer of MFPFH heat sink are analyzed, and the thermal performance ratio is evaluated. Thermal contact resistance between PFs and MF is introduced to explain its effects on the thermal performance of MFPFH heat sink for its practical application. Results indicate that significant heat transfer enhancement is achieved by using the MFPFH heat sink, due to the enhanced heat conduction and the improved heat convection by the common contribution of MF and PFs. Heat transfer characteristics of MFPFH heat sink are more sensitive to foam porosity, and pressure drop to pore size. By simultaneously considering the heat transfer enhancement and flow resistance increase, the thermal performance ratio of MFPFH heat sink is 1.6 times higher than the traditional PF heat sink. When thermal contact resistance is 10−3 m2·K/W, the degradation of average Nusselt number is approximately 36%.

Airfoil shaped pin-fin heat sink: Potential evaluation of ferric oxide and titania nanofluids

Miniaturization of devices poses many problems for the manufacturing industry. To maintain the temperature of such high heat generating devices hybrid cooling via mini-channel heat sinks in combination with nanofluid is one of the potential cooling techniques. Airfoil pin-fins performed well due to delayed separation of fluid that ensured the maximum interaction of coolant with the walls of heat sink. The main purpose of present study is to analyze the hydrothermal performance of airfoil shaped pin-fin heat sink employing nanofluids of ferric oxide (Fe2O3) and titania (TiO2), also compare the results with base fluid (distilled water). The study was conducted by varying the heating power and Reynolds number. Maximum augmentation in average Nusselt number of 14.5% and 15.89% was found for TiO2-water and Fe2O3-water nanofluids respectively with a particle concentration of 0.01 vol% at 25 W as compared to distilled water. In addition, a maximum enhancement of 42.46% was observed in pumping power for Fe2O3 while it was 30.5% for TiO2 nanofluid.