Cylindrical Pin Fins Research Articles

Numerical investigation and optimization of an asymmetric elliptical-cylindrical pin fin heat sink

A 3D numerical simulation was performed to analyse the heat transfer characteristics of an asymmetric elliptical-cylindrical pin fin heat sink (AECPFHS) in a turbulent flow scenario and to determine the optimum asymmetric elliptical-cylindrical pin fin (AECPF) structure. The investigation is performed in three stages. The numerical procedure and the software tool used in the current research are first validated with another work in which the performance enhancement of a heat sink with staggered cylindrical pin fins (CPFs) was studied. A cylindrical pin fin heat sink (CPFHS) with staggered fins was considered as the reference case. In the next stage, the heat sink with staggered solid-AECPFs (SAECPFs) was simulated, and its performance was compared with the reference case. The highest fin effectiveness obtained was 1.43 for the fin radius (r) to channel height (H) ratio (r/H) = 0.9. This structure was chosen as the base case, and in the third stage, its performance is improved by adding perforation on AECPFs. The influence of nine distinct perforation patterns of three different hole size were selected, and their thermal performance was analysed in detail. The highest fin effectiveness noted for the fins with 8 holes of 3 mm diameter is 2.25 at Re 3111. Furthermore, with the proposed perforated-AECPFHS (PAECPFHS) structure, in comparison to the reference case, the volume of the fins was lowered by as much as 60 %.

CFD and ANN analyses for the evaluation of the heat transfer characteristics of a rectangular microchannel heat sink with various cylindrical pin-fins

CFD and ANN analyses for the evaluation of the heat transfer characteristics of a rectangular microchannel heat sink with various cylindrical pin-fins

Experimental and numerical analysis of heat sink using various patterns of cylindrical pin-fins

The increasing heat generated by electronic devices requires effective dissipation methods. This research proposes a unique pin-fin (PF) design inspired by cylindrical pin-fins, including three patterns: cross-pin-fins (CPFs), parallel-pin-fins (PPFs) and double-cross-pin-fins (DCPFs). The study examines the hydrothermal performance of these designs within Reynolds numbers of 4500 to 18,000 and heat fluxes of 445 W/m² to 2281 W/m². The PF design aims to maximise performance by increasing surface area and airflow turbulence. Experimental data confirmed the computational results for the PF and CPF heat sinks, exhibiting significant agreement. A numerical study evaluated the hydrothermal performance, revealing that DCPFs deliver a superior performance. As the diameter expands, the Nusselt number (Nu) rises significantly across each design, with increases of 100 %, 162 % and 328 % for the PPFs, CPFs and DCPFs, respectively. Each configuration achieved a Heat Transfer Performance Factor (HTPF) exceeding 1, indicating improved heat transfer efficiency over the friction factor. The heat sink comprising the DCPFs achieved a high HTPF of approximately 2, irrespective of the Reynolds numbers and heat fluxes, demonstrating its effectiveness in heat dissipation compared to other designs.

Effect of variation in heights of cylindrical pinfins on the thermo-hydraulic performance of an open-microchannel heat sink

This article investigates the impact of different heights of cylindrical micropillars on the thermo-fluid properties of an open microchannel heat sink. The dimensions of the microchannel considered in this study are 0.1 mm × 0.2 mm × 10 mm. Computational fluid dynamics has been employed to simulate seven distinct microchannel layouts. These configurations are Case 1 (Closedmicrochannel with full height pinfins), Case 2 (Openmicrochannel with reduced height pinfins), Case 3 (Openmicrochannel with half height pinfins), Case 4 (Open microchannel with reduced height pinfins at upstream and half height pinfins at downstream), Case 5 (Open microchannel with reduced height pinfins at upstream and half height pinfins at downstream). Case 6 (Open microchannel with two half-height pinfins at upstream and downstream regions, respectively). Case 7 (Open microchannel with two reduced height pinfins at upstream and downstream regions, respectively). Nusselt number, pressure drop, and overall thermal performance of all the considered open configurations of microchannels are evaluated and compared with the plain and closed microchannel for the range of Reynolds number between 150 and 350 by considering water as a working fluid. The results depict that the maximum augmentation in the Nusselt number is about 16.8% achieved by the open microchannel heatsink (Case 2) corresponding to the closed microchannel (Case 1) with a reduction in pressure drop of about 7.32%. To evaluate the mutual effect of heat transfer and pressure drop, overall thermal performance is evaluated. At a lower Reynolds number, the highest performance is associated with Case 2 but at the elevated range of Reynolds number, the maximum performance is acquired by Case 4.

Experimental and numerical studies of the effect of perforation configuration on heat transfer enhancement of pin fins heat sink

AbstractIn this study, experimental and computational studies of the impact of forced convective flow on the heat transfer characteristics of staggered pin fins with perforations are investigated in a rectangular channel at constant heat flux with Reynolds numbers (Re) of 2 × 103–12 × 103. In particular, cylindrical pin fins with circular longitudinal (L) perforation, longitudinal/transverse (LT) perforation, and longitudinal/transverse/vertical (LTV) perforation perforations are compared to solid pin fins to find out how adding different perforation arrays affects overall heat transfer performance and also to find the best perforation configuration for maximum performance. ANSYS‐FLUENT is employed for numerical simulation, validated by experimental data. Experimental validation is conducted by attaching the heat sink to a Peltier module, inducing heat generation through current on one face in the Armfield Free and Forced Convection Heat Transfer Service Units HT 19 and HT10XC. Results highlight significant increases in Nusselt number (Nu) for perforated pins compared to solid pins, with L perforations at 8%, LT perforations at 33%, and 67% for LTV perforated pins due to transverse perforations that act as slots, which stir up the primary flow and induce secondary flow generated by vertical perforations. Regarding pressure drops, L perforations reduce by 9%, LT by 19%, and LTV by 27% compared to solid pins. The overall enhancement ratio peaks at the minimum Reynold number, notably achieving a 38% increase in the LTV perforation pin fin array. This innovative study holds promise for diverse electronic applications, offering enhanced heat transfer performance in electronic cooling systems.

Effects of the pin-fins cooler roughness on the thermo-fluid dynamics performance of a SiC power module

The objective of this study was to develop a Computational Fluid Dynamics (CFD) 3D model for an industrial application, to investigate how surface roughness affected pressure drop and thermal performance in the ACEPACKTM DRIVE, a commercial SiC-based power module used in traction inverters, that features a pin-finned baseplate with cylindrical pin-fins. The surface roughness of the pin-fins was modelled by using a sand-grain model available in Ansys Fluent, which represents a novelty in the literature and can pave the way for the development of accurate and computationally efficient simulations. The CFD model exhibits an error from experimental data within the range 10%–22% when the flow rate varies from 2 l/min to 12 l/min (maximum error at 2 l/min), while the validation of the thermal behaviour was obtained with a maximum error of 2.5%. Subsequently, a parametric analysis was carried out, varying the flow rate of the coolant, in order to investigate the influence of pin-fins surface roughness on performance, by considering two possible design option featuring respectively a surface roughness equal to 1 μm and 6 μm. The results showed a reduction in pressure drop from 4% to 11% and a degradation of the thermal performance, less than the 2%, when the pin-fins roughness increases.

Suitability analysis of an air heater coupled with PCM made fins

The outcomes of an experimental study onthe performance of a Double-Pass typeSolar Air Heater(DPSH) has been presented in the current study. The study was conducted on the DPSH with two set-ups; one set-up was a normal DPSH and another one was the DPSH containing pin-finned absorber and organic phase chaning materials (PCM) based latent heat storing medium (LHSM). The organic wax (PCM) was employed as the LHSM. Further, in the second set-up, the absorbing plateof the DPSH was configured with cylindrical pin fins. Experiments were conducted at 23°48′10″N and 78°48′14″Ein June2022in two different experimental set-upson the sunny days with a comparable radiation. In the investigation, the basic set-up solar air heaterwas directly named as DPSH-Normal and used in the investigations as it is, whereas, the second DPSHsetup was configured with pin-fins and LHSM, and named as DPSH-LHSM. A constant airflow massof 0.185 kg/s was used to facilitate the research. Adding LHSMto the pin-finned DPSHgreatly increased its performance, as shown by the findings. As a result of being coupled with the Pin-fins and LHSM, the DPSH's had displayed the improvedenergy efficiency by 13.56percent.

Thermal performance of stretching/shrinking fully wet porous cylindrical and conical pin fin structures by differential transformation approach

In this paper, the thermal behavior of cylindrical and conical pin fin structures operating in a convective–radiative environment has been examined. The fully wet porous fin structures are assumed to be mounted with a stretching/shrinking mechanism similar to a conveyer belt. The conical pin fin has been comparatively analyzed with the cylindrical one for three distinct cases of stretching, stagnant, and shrinking. Further, the Darcy model has been employed to analyze the fluid–solid interactions. The differential transformation method (DTM) has been used to solve the resulting second-order nonlinear ordinary differential equations. On the thermal performance of conical and cylindrical pin fin structures, the effects of the stretching/shrinking parameter, Peclet number, wet porous parameter, convective parameter, and radiative parameter have been established graphically. The conical pin fin is found to aid the heat transmission process better than the cylindrical one. The work is also helpful in the realm of microelectronics, particularly in the development of micro-pin-fin structures.

Multi-objective topology optimization and thermal performance of liquid-cooled microchannel heat sinks with pin fins

The optimized structures for the liquid-cooled microchannel heat sinks with different pin-fin arrays were designed via using the topology optimization method for the better performance, including minimization of the flow energy dissipation and the average temperature of the bottom surface, aiming to facilitate the more efficient design of microchannel heat sink for electronic chips’ cooling. The heat transfer and flowing performance was simulated with steady-state incompressible Navier-Stokes equation and the energy equation. Based on the rational approximation of material properties (RAMP) method, the mathematical optimization model for heat sink was established according to the multi-objective function. The Galerkin finite element method (GFEM) was employed to calculate the flow and heat transfer system. Furthermore, the globally convergent method of moving asymptotes (GCMMA) was adopted to deal with the mathematical optimization problem as the optimization method. The entropy generation analysis and comprehensive heat transfer factor were employed to evaluate the performance of the conjugate heat transfer problem of 3D microchannel heat sinks with various pin-fin structures. The calculation results reveal that the multi-objective optimal structure has good heat transfer performance, and the temperature distribution of the optimized structure is more uniform. As the same pumping power, the comprehensive heat transfer efficiency of the optimized inline and staggered pin-fin arrays increases by 31.20% and 32.18% compared to the smooth rectangular channel. Compared with the cylindrical pin-fin configuration with the same heat transfer area, the entropy generation rates of the optimized inline and staggered pin-fin configurations decrease by 4.67% and 4.25%, respectively. The results can provide theoretical basis and application support for the electronic chip cooling technology.

A comprehensive analysis of a rectangular microchannel heat sink furnished with a circular perforated cylindrical pinfin

In this study, a simulation has been performed to investigate the effect of circular perforated pinfins on the performance of microchannel heat sink by varying the number of holes and their locations on the pinfins. A total of ten configurations are considered in this work including a plain microchannel (without pinfin) and a solid pinfin case. The study was conducted on a single-phase flow using deionized water as coolant and the Reynolds numbers range from 150 to 350 when a constant heat flux of 100W/cm2 has been applied at the heated base wall of a heat sink. The results obtained indicate that the location, as well as the number of perforations, affects the heat transfer capacity and pressure drop that occurs in the microchannel. However, the outcomes of the present analysis contradict the findings for thermal airflows when identical cases have been applied to the micro heatsink. According to the present analysis case 1 (perforation at the underside of the pinfin) has the maximum Nusselt number followed by case 2 (perforation at the mid of the pinfin) and case 3 (perforation at the topside of the pinfin) whereas the minimum pressure drop is achieved by case 8 (four equidistant perforations) among pinfin configurations. The highest performance factor is achieved by case 1 at a low Reynolds number while case 6 (perforation at the underside and topside) performs best at a higher Reynolds number.

Optimization of different pin-fins on heat transfer and pressure drop of a heat sink for antifreeze liquid case

BackgroundThis paper presents numerical simulation of flow of water, ethylene glycol, and water-ethylene glycol (50:50) in a heatsink with new geometry. A large number of cylindrical pin-fin with differen cross sections in a spiral arrangement are used to extend the heat transfer surfaces of the heat sink. MethodsThe heatsink that is designed for cooling microprocessors has an inlet and four outlets. A portion of the heatsink receives a steady heat flux of 100 W/cm2. The simulations are carried out with COMSOL commercial software and the finite element approach. Significant findingsThe results showed that as the Re is increased, the maximum and average values of THS as well as THR are reduced and better TPU is achieved. Using water instead of ethylene glycol at low values of Re can reduce the THS by 19.8%. This reduction is 13.7% for high amounts of Re. The use of a circular pin-fin at Re = 500 and 1000 relative to the elliptical one can reduce the amount of PMP required for water circulation by 12.7% and 13.1%, respectively. The minimum THR and the best TPU occur for square and circular pin-fins, respectively.

Numerical simulation and optimization with artificial neural network of two-phase nanofluid flow in a circular heatsink with cylindrical pin-fins

This paper designs and simulates a circular heatsink (HSK) with a novel geometry. A number of cylindrical pin-fins (PIFs) are placed on the HSK. The flow of alumina/water nanofluid (NF) enters from the middle of the HSK, passes through the PIFs, goes toward the outer curvature, and exits from the HSK. Constant thermal flux is applied at the bottom of the HSK. The variables include the length of PIFs changing from 5 to 20 mm, the distance between PIFs varying from 10 to 15 mm, and the diameter of PIFs changing from 1 to 4 mm. The effect of these variables on the maximum of the HSK, the average temperature (T-AV) of the HSK is examined. Finally, numerical optimization is done on the results using machine learning and artificial intelligence in terms of the minimum HSK temperature. The flow of NF is simulated using a two-phase model and the finite element method (FEM). An increment in the length of the PIFs from 5 to 20 reduces the T-AV by 11.42 K. An increment in the diameter of the PIFs from 1 to 4 reduces the T-AV of the HSK by 5.98 K.

Transient thermal investigation of a fully wet porous convective–radiative rough cylindrical pin fin

AbstractThe microelectromechanical systems technologies frequently produce rough surfaces, and the repercussion of roughness on the thermal performance is more prominent in structures of smaller dimensions. In this regard, the present article intends to examine the unsteady thermal behavior of a fully wet, porous, and rough micropin‐fin structure under convective–radiative conditions. Here, a pin fin of a cylindrical profile has been chosen. The problem is modeled by incorporating the roughness parameters in the perimeter and cross‐sectional area of the pin fin. Further, the study of the porous structure has been carried out by implementing the Darcy model. The resulting partial differential equation is nonlinear and of the second order which has been solved by employing the finite difference method. The impact of the roughness parameter, wet porous parameter, dimensionless time, convective parameter, base radius‐to‐length ratio, radiative parameter, thermal conductivity parameter, power index, and ambient temperature on the thermal performance and efficiency of rough micropin‐fin structures has been established graphically. According to the findings, for rise in roughness, the rough micropin fin has more thermal drop rate and less efficiency than the smooth one. Further, the work is beneficial in the field of microelectronics, especially in the design of micropin‐fin structures.

Shape optimization of pin fin array in a cooling channel using genetic algorithm and machine learning

This article reports the optimization of pin fin shape using a genetic algorithm (GA) coupled either to a machine learning (ML) model or a computational fluid dynamics (CFD) model. The ML model evaluates the temperature and pressure induced by the fins within a second and allows us to replace the time-consuming CFD simulations during the design stage. The optimization is conducted for a cooling channel with a uniform heat flux boundary condition (5 W/cm2) in the Reynolds numbers range of 3000 – 12000. The optimization identifies a funnel-shaped fin that enhances the heat transfer coefficient by 20% without an apparent increase of pressure drop as compared to the standard cylindrical pin fins. The funnel-shaped fin outperforms other conventional fins of elliptical, cubic, and drop shapes that induce a similar level of pressure drops. This work demonstrates the potential of ML-based optimization in searching unexplored shapes of heat transfer systems with superior performance.

Performance Analysis of Central Processing Unit Heat Sinks Fitted With Perforation Technique and Splitter Inserts

Abstract The increase in the heat dissipation rate in heat sinks (HSs), the reduction of the occupied volume and mass, and the elimination of the lower heat transfer areas (LHTAs) behind the pins are the main parameters to be controlled in HSs design. For this purpose, this study is devoted to numerically investigating the effect of the combination between perforation technique and splitters inserts on the heat dissipation and turbulent fluid flow characteristics of pin fins heat sinks (PFHSs). The splitter is located in the back of the pin, and the cylindrical pin fins heat sinks (CPFHSs) are perforated with different pairs of hole numbers. These configurations are named PFHS-0 (without perforation) to PFHS-5. The results obtained for the PFHS-5 show an increase in Nusselt number by 34.91% and a reduction in the thermal resistance by 24.22%, compared with CPFHSs. For the same conditions, the occupied volume and mass of this case are also reduced by 70% and 47.5%, respectively. In addition, the PFHS-5 case ensures the highest hydrothermal performance factor (HTPF) of 1.42 at Re = 8,740.

Transient Conjugate Heat Transfer Analysis of a Cylindrical Pin Fin Made by Functionally Graded Material Embedded in the Turbulent Flow

Transient Conjugate Heat Transfer Analysis of a Cylindrical Pin Fin Made by Functionally Graded Material Embedded in the Turbulent Flow

Numerical Simulation of Heat Transfer Behaviors in Conical Pin Fins Heat Sinks

The present study is a numerical investigation of the effect of the shape of pin fins on the overall performances of heat sinks. Conical shaped pin fins with varying conical size ratio (Hcp/d) are considered. Five geometrical cases are explored, namely Hcp/d = 0.167, 0.333, 0.500, 0.667 and 0.833. The distribution and values of temperature, Nusselt number, thermal resistance, pressure drop, as well as the hydrothermal performance factor are determined for various Reynolds numbers (up to 8,000). In addition, the performances of conical shaped fins are compared to those of the cylindrical fins. The obtained results revealed a decrease in the thermal resistance with increasing Re and Hcp/d ratio. At Re = 8000 and when changing (Hcp/d) from 0.167 to 0.833, the thermal resistance is decreased from 192.30% to 83.52% compared to the cylindrical pin fins. However, the increased (Hcp/d) ratio yields an increase in the pressure drop. At Re = 8000, the values of pressure drop for the conical fins are lower than those of the cylindrical fins by 343.32%, 275.92%, 205.79%, 144.86% and 100.38% for Hcp/d = 0.167, 0.333, 0.500, 0.667 and 0.833, respectively. The values of the hydrothermal performance factor (h) for the conical fins are greater than those of the cylindrical fins. Also, an increase in (h) values is observed with decreasing Hcp/d ratio. The highest (h) value of 1.51 is reached with the case Hcp/d = 0.167 at Re = 8,000.

Studying transient heat transfer in a cylindrical pin fin with radiation and convection

A simple experimental fin device was used to develop a laboratory procedure for undergraduate engineering students, in order to enhance their understanding of the transfer of thermal energy. This experiment exposes the student to several important concepts, namely one-dimensional, time-dependent heat transfer in extended surfaces by conduction, convection and radiation. In a few simple steps, students have the opportunity to compare the measured to the predicted temperature profiles obtained at different times using an analytical complex solution and to calculate convective and radiative heat coefficients, such as the relative predominance of convection heat transfer with respect to radiation.

Investigation of the hydrothermal enhancement of grooved pin fins heat sinks

In this paper, a numerical investigation was conducted to analyse heat transfer and fluid flow on a new design of heat exchangers with grooved pin-fin heat sinks (G-PFHS), which included the optimisation of shape, size, and groove number (Ng ). The simulation results indicate that all-novel geometries have the highest heat dissipation rates compared to conventional geometry (Cylindrical pin fins heat sink, CPFHS). However, the configuration with semi-circular grooves exhibits the most design compared to other configurations (pin-fins heat sinks with a rectangle, triangular, trapezoidal grooves and CPFHS). Also, after optimisation of the size and number of grooves, the Nusselt number and thermal resistance are improved by 21.01% and 16.70%, respectively, with an increase in the pressure drop by 15.42% compared with the CPFHS at the highest Reynolds number. Therefore, this case provides the best hydrothermal performance factor (HTPF) of 1.18 at Re = 8740.

Effect of circular perforated pin fin on heat transfer and fluid flow characteristics of rectangular microchannel heat sink

In the present work, a numerical analysis has been performed to observe the heat transfer and fluid flow characteristics of the perforated pin fin microchannel heat sink. Six equidistant cylindrical pin fins with circular perforation at the center are entrenched at the base wall of the channel. This perforated pin fin can act as an extended surface and enhanced the heat transfer whereas the circular perforation may reduces the pressure drop and also influence the flow characteristics. The analysis has been done for the single-phase flow with Reynolds number ranges between 150 to 350 and the nondimensional diameter(α) of circular perforations considered in this study are 0.33, 0.5, 0.67 and 0.83. It is observed that the Nusslet number improves with the smallest perforation that is α = 0.33 and decreases as the diameter of perforation increases however the maximum value of overall thermal performance is associated with the perforation size of 0.5.