Elliptical Fin Research Articles

Investigation of hydrothermal characteristics and entropy generation in a microchannel heat sink with elliptical fins

Abstract As the integration of microelectronic devices continues to increase, thermal management issues become increasingly prominent. Microchannel heat sinks are effective for heat dissipation in high heat flux microelectronic devices. This study designs five elliptical finned microchannel heat sinks with different aspect ratios (γ) while maintaining a constant elliptical area to enhance heat transfer performance. The values of γ are 0.74, 0.86, 1, 1.17, and 1.35, respectively. Over the Reynolds number (Re) range of 293 to 740, the hydrothermal characteristics and entropy generation of the microchannels with elliptical fins (MC-EFs) are investigated through numerical simulations. The thermal enhancement mechanism of MC-EFs is analyzed via flow, temperature, and pressure fields. The optimal γ value is determined by maximizing the overall performance factor (OPF) and minimizing the augmentation entropy generation number (Ns,a). Results indicate that introducing elliptical fins in the straight microchannel (SMC) significantly improves heat dissipation. An increase in γ enhances thermal performance but also raises flow resistance. Specifically, when γ increases from 0.74 to 1.35, the Nusselt number (Nu) improves by 10.71%-25.64%, and the friction coefficient (f) increases by 30.92%-57.27%. Overall, at Re = 740, the OPF of the MC-EF with γ = 1.35 reaches a maximum of 1.285, and at Re = 597, the Ns,a for this configuration is minimized to 0.578. These findings provide valuable insights for effective thermal management in microelectronic devices.

A novel pin finned structure-embedded microchannel heat sink: CFD-data driven MLP, MLR, and XGBR machine learning models for thermal and fluid flow prediction

Microscale mechanical systems benefit from microchannel heat sinks' heat transfer efficiency. This study uses six new pin fin shapes embedded in microchannel to improve heat dissipation. The study optimizes geometries based on overall thermal performance for Reynolds numbers ranging from 150 to 350. Validation using numerical and experimental data indicates variations under 10 %. Graphical representations show that the proposed pin fin configurations outperform the baseline case. From numerical investigation, the circular perforated fish fin increases Nusselt number by 25 %, whereas the elliptical fin lowers pressure loss by 66.95 %. Elliptical fins enhance thermal performance by 30 %, proving that novel designs and optimization tactics work. Six machine learning models are considered to predict Nu and pressure drop. Keras and sklearn were used for MLP, MLR, and XGBR was imported from XGBoost. Model performance was assessed using the R2 test, MRE, RMSE, and rRMSE. MLP (R2 test = 0.950, MRE (%) = 11, rRMSE = 2.3 %) and XGBR (R2 test = 0.909, MRE (%) = 2.2, rRMSE = 2.9 %) model a good estimation of Nu. XGBR (R2 test = 0.999, MRE (%) = 1.2, rRMSE = 1.6 %) also estimates pressure drop with good accuracy. KFold cross validation was employed to evaluate the mean CV score of the developed model.

Thermal performance analysis of a lithium-ion cell using the novel fins and the phase change material

The battery thermal management system (BTMS) plays a key role in keeping the electric vehicle battery temperature within thermal safety limits. A poorly designed BTMS may reduce the operational life of the battery. The present work aims to maintain the battery temperature below the threshold limit using the triangular and elliptical-shaped novel fins and the phase change material (PCM). Multiple arrays of these fins were fitted along the cell height in the annulus space between the cell sleeve and the casing such that the tip of the fins touches the casing. The individual and the combined performance of the fins and the PCM was assessed through temperature measurements using the thermocouples and the thermal camera at various power inputs of 30, 50 and 70 W. At 70 W, the cell operation was extended by a maximum of 250 %, 270 % and 280 % for the cell with PCM, with PCM and triangular fins and PCM with elliptical fins, respectively. The lowest extension in cell operation by 10 % was observed for the triangular fins alone at 70 W. This demonstrates the significant influence of the PCM on the cell performance. The temperature contours using the thermal camera showed that for all power settings, the peak temperature occurs at the cell center. The present studies demonstrate a significant potential for BTMS application in the combined system of elliptical fins with PCM.

A New Iterative Broyden Legendre Wavelet Galerkin FEM Applied to Unsteady State Model of Two-Dimensional Elliptic Fin

Abstract The novelty of this paper is the investigation of numerical study of a mathematical model which deals with time dependent heat flow in elliptic fin ( dry, wet and partially wet). In this paper, we developed a nonlinear model of second-order heat equations in unsteady state condition. A new iterative Broyden Legendre Wavelet Galerkin Finite Element Method is used for the solution. The central difference approximation used for discretization of second order derivatives and then utilization of Hadamard, Khatri Rao and Face splitting matrices product with Legendre Wavelet Galerkin Method transfers our main problem in to system of non-linear algebraic equations. The iterative Broyden Method provides the solution for this system. In a particular case, present solution is compared with the exact solution and is approximately the same. Effect of different parameters such as Biot number, Latent heat, Kirpichev number, Fin thickness, μ, η and ξ on the temperature distribution are discussed in detail.

Numerical investigation of the thermo-hydraulic performance of a shark denticle-inspired plate fin heat exchanger

Growing demand for increased power dissipation is fuelling the need for the design of more efficient heat exchangers. Modifying fin geometry is an effective way of improving heat transfer efficiency and of reducing flow resistance for plate fin heat exchangers. To date, fin designs have mostly revolved around classical shapes such as pins, ellipses, and rectangles, due to limitations of conventional manufacturing technologies. However, with recent advancements in metal additive manufacturing, there is an opportunity of redesigning approaches and ways of thinking to create novel fin geometries. In this study, biomimicry was used as a tool to reverse engineer a novel geometry for a plate fin heat exchanger based on a denticle, which is a mesoscopic structure on the skin of sharks. The shape of the denticle is streamlined; therefore, showing the possibility of enhancing fluid-to-solid contact if used as geometry for a plate fin heat exchanger. The thermo-hydraulic performance of the denticle was evaluated with respect to a rectangular, cylindrical and an elliptical fin (NACA 0030), using conjugate-heat-transfer simulations on ANSYS-Fluent. The numerical model was calibrated and validated based on experimental results from an additively manufactured rectangular plate fin heat exchanger. Results demonstrated that over the range of tested Reynolds Numbers, 9.8x104 < Re ≤ 22.9x104, the denticle fin had average Nusselt number improvements of 13.1 %, 5.4 % and 75.7 % with respect to the rectangular fin, the NACA 0030 and cylindrical fin, respectively. At Re = 22.9x104, a 26 % decrease in pressure drop was noted for the denticle with respect to the rectangular fin, with maximum thermal performance factors (ƞ) of 1.29, 0.81 and 1.53 as noted for the denticle fin with respect to the rectangular fin, NACA 0030 fin and cylindrical fin, respectively.

Heat Transfer and Performance Enhancement of Porous Split Elliptical Fins

To augment the heat transfer phenomenon, the infusion of various fin geometry over the heated plate is being investigated by various researchers. Solid fins of the porous medium can enhance the convective heat transfer, providing a higher surface area-to-volume ratio for heat transfer. In this work, the fluid flow pattern and thermodynamic analysis of porous-based split elliptical fins mounted staggered over a heated base plate is numerically studied with the Reynolds numbers in the range of 783 to 1839, which is dependent on the fin dimension. The variable parameters were dimensionless transverse offset ( TO ∗ = transverse offset / diameter ), which varied from 0 to 0.5; dimensionless longitudinal offset ( L O ∗ = longitudinal offset / diameter ), which varied from 0 to 0.25; porosity (ɸ), which varies from 0.8 to 0.92; pores per inch (PPI), which was 10; permeability ( P n ); and inertial parameter ( F ). To count the viscous and inertial effect inside the porous zone, the Forchheimer–Brinkman extended Darcy model was adopted. The associated parameters, the Nusselt number (Nu), frictional coefficient ( C f ), and performance evaluation criteria (PEC), are thoroughly analyzed over the TO ∗ and LO ∗ combination. The results of the investigation revealed that the highest value of Nu and PEC was obtained by TO ∗ = 0.5 and L O ∗ = 0 at ɸ = 0.92 , which were approximately 54% and 79% higher than the solid circular fin at Re = 1839 . Additionally, a response function based on Nu was obtained using the response surface method, and cuckoo optimization was assessed to identify the optimal Nu. The optimal Nu is established at TO ∗ = 0.4141 and L O ∗ = 0 ( ɸ = 0.92 and Re = 1839 ) and was validated with the present investigation with an accuracy of 1.20%.

Thermo-fluidic analysis of microchannel heat sink with inline/staggered square/elliptical fins

The present study reports the thermo-fluidic behavior of a microchannel heat sink employed over a heat source dissipating a heat flux of 50 W/cm2. The microchannel heat sink is embedded with elliptical and square fins varied from 11 × 3 (11 fins per row with a total of 3 rows) to 79 × 3 fins and 100 μm to 300 μm height to obtain the optimum configuration for maximum heat transfer and minimum frictional loss. Fluid flow is considered in the laminar range of Re varying from 100 to 400. The problem is solved numerically using a Finite Volume Method based multigrid solver of ANSYS Fluent. The aim of the present study is to investigate the shape effect of square fin (α = 0), square fin (α = 45) and elliptical fins on the heat transfer from the heater surface and frictional loss. This is achieved by keeping the correctional area and the surface the same for all types of fins. It is found that the heater surface temperature monotonously decreases with the number of fins for a fin height more than 200 μm. When different fin shapes are compared, no remarkable difference in the heater surface temperature is observed; however, elliptical fins are marginally more effective for a greater number of fins than the square fin with α = 0 followed by α = 45. Increasing the fin height results in augmenting the heat transfer for all cases. When different arrangements are compared, staggered fins result in slightly better heat transfer than the inline fins except 11 × 3 and 79 × 3 fins. As far as friction factor is concerned, elliptical fins with staggered arrangement provide the least frictional resistance.

Performance enhancement of a horizontal latent thermal energy storage unit with elliptical fins

The practical use of latent thermal energy storage (LTES) system is limited by the low thermal conductivity of the available Phase Change Materials (PCMs). In this study, the elliptical fin is proposed and applied to Horizontal Double Tube LTES Unit (HDT-LTESU) for improving the performance of thermal storage. Paraffin wax is used as PCM that is placed in the annulus between tube and shell. Three-dimensional numerical simulation based on enthalpy porosity method is performed to study the characteristics of the PCM melting/solidification and the performance of charging/discharging thermal energy of HDT-LTESU with different aspect ratios elliptical fins. The mechanism of enhanced thermal energy storage is also verified and analyzed by the entransy theory. It was found that the addition of elliptical fins can effectively improve convection heat transfer of PCM at the top and bottom of the annulus. Further, the high aspect ratio fins are more favorable for improving the comprehensive performance enhancement, and enhancement ratio can reach up to maximum 16.9% and 13.8% for melting and solidification, respectively. The entransy dissipation is reduced, and the phase change process of heat transfer is improved.

Investigation of flow and heat transfer behavior of integrated pin fin-aluminum foam heat sink

• A novel aluminium foam heat sink (AFHS) consisting of pin fin inserts is proposed. • The developed mathematical model is validated with experimental data. • Thermo-hydraulic characteristics of proposed heat sinks are numerically studied. • Pin fin inserts lead to an enhancement on the heat removal capability of AFHS. • Pressure drop along the flow direction increases with pin fin insertion into AFHS. With the rapid development in the electronics industry, the thermal management of high power density electronic products (HPDEPs) has become very important and requires innovative heat removal technologies. In this study, an integrated heat sink (IHS) fabricated by combining aluminum foam and pin-finned heat sink configurations that are frequently used in the cooling of electronic products has been proposed as an effective solution for the thermal management of HPDEPs. The heat removal and pressure drop characteristics of the IHS were numerically investigated for its various design conditions such as the length/height ratio ( L/H ), fin profile, fin/foam height ratio ( H fin /H foam ), and heat sink/fin volume ratio ( V hs /V f ) over the range of Reynolds ( Re Dh ) number from 500 to 3500 by using the COMSOL Multiphysics v5.4. Before the numerical study was performed, to verify the outcomes of the developed simulation models, some of the IHS subjected to the numerical study were fabricated and their pressure drop and heat removal performances were experimentally examined in the range of Re Dh from 596 to 3551. As a result of the study, it was found that the thermal contact resistance ( TCR ) between the IHS and the heated surface has a greater effect on the Nusselt ( Nu ) number compared to the TCR between the solid fins and aluminum foam. The in-line or staggered arrangement of pin fins inside the aluminum foam did not lead to any significant difference in the overall performance of investigated IHS. For all the IHS examined, an increase in Re Dh results in a similar increase in the Nu and ΔP along the flow direction. In general, the most efficient IHS among the investigated ones in terms of the H fin /H foam ratio is the IHS with half-length fins, H fin /H foam =15/30. Average values of thermal performance factor ( ƞ) of the IHS with H fin /H foam ratio of 15/30 in in-line and staggered arrangement over the Re Dh number studied are 1.3 and 1.25 times higher relative to IHS with H fin /H foam ratio of 30/15. For a fixed number of fins, η of the IHS with fins of 4mm diameter is superior up to Re Dh =2000, after which, the situation varies in favor of the 8mm solid finned aluminum foam heat sink. Increasing the fin diameter from 4mm to 12mm in both fin configurations worsens the average value of ƞ by 10%. For a constant fin diameter, IHSs with 9 fins in in-line and 8 fins in staggered configuration have the highest ƞ when the Re Dh is greater than 2500 and 2000, respectively. Among the fin profiles examined, the IHS with elliptical fins is found to have the highest η , with a value of 1.24, at Re Dh =3500.

Relative assessment of various annular fin shapes for heat transfer and pressure penalty

Three dimensional numerical investigations are carried out to analyse the effect of different shapes of annular fin on heat transfer characteristics and pressure drop across a tube surface. Shear stress transport based k-ω turbulence model is used to analyse flow physics and heat transfer characteristics in flow domain. Weak zones of heat transfer across a circular tube surface are identified for 2500 &lt; Re &lt; 13000. Three different shapes of annular fin are considered to test the possibility of optimum heat transfer characteristics in weak zones. Results are compared with circular shape annular fin. Circular shape annular fin outperforms in terms of overall rate of heat transfer at the cost of highest pressure drop. The heat transfer rate decreases by 18%, 21% and 31% in sectorial fin, elliptical fin and sectional fin as compared to that of circular fin at 12965 Reynolds number, but at other end pressure drop across a tube surface in case of these fins also decrease as compared to that of circular annular fin. Potential rate, ratio of heat transfer rate to required pumping power, is calculated to evaluate optimum fin performance. Potential rate of an elliptical fin is highest among all the reported cases.

Study on heat transfer performance of fin-and-tube heat exchanger with elliptical fins

In the present work, three-dimensional numerical analysis was carried out for thermo-fluid analysis of annular fin-and-tube heat exchangers (AFTHE) with circular fins and elliptical fins having varying Reynolds number (Re) changed from 4000 to 9000. The effects of the angle of attack (α) and the ratio of long diameter to short diameter (LDR) for elliptical fins on heat transfer characteristics and flow structures were studied and analyzed in inline arrangement tubes. The thermo-hydraulic performance criteria which include Nusselt number (Nu), friction factor (f), and London area goodness factor (JF) were also compared. The results showed that the heat transfer performance of the AFTHE with elliptical fins was better than that of AFTHE with circular fins, except for elliptical fins with an α of 90°. The JF for AFTHE with elliptical fins, when the value of α was 0°, was optimal, which improved by 42.08 % based on the AFTHE with circular fins. When α was 0°, the JF of the AFTHE with elliptical fins was proportional to the LDR, where the LDR of 1.5 was improved by 43.52 % from the AFTHE with circular fins. And the results were well in line with the entropy generation.

Comparative study of elliptical fin microchannel over oblique micro‐fin heat sinks

AbstractIn the present paper, the effect of elliptical fin and its orientation were computationally examined by considering equivalent fin cross‐sectional area and height of oblique fin to enhance thermal performance. A total of seven distinctly oriented elliptical fin microchannel models were developed and analyzed using finite volume method for velocity range of 0.2 to 0.9 m/s at constant heat flux of 65 W/cm2. The results showed that the elliptical fin microchannel model reduced pressure drop significantly and consumed less pumping power than the oblique fin microchannel model. It was also found that the average Nusselt number initially increases with decreasing elliptical fin orientation angle and then it rapidly decreases on further reduction of orientation angle beyond 4°. The optimal performance factor for a 4° elliptical fin was 1.21, with only a 6.5% penalty in wall temperature at Re 436. Furthermore, the maximum pumping power reduction of 41.4% was found for the 4° elliptical fin microchannel model with a 2.3% increase in Nusselt number. Hence, for the same pumping power, the 4° elliptical fin microchannel model performs better than oblique fin microchannel.

Simulation of solar thermal panel systems with nanofluid flow and PCM for energy consumption management of buildings

The present study simulates a solar thermal panel using the finite element method (FEM) in COMSOL Multiphysics. A cropper pipe of a water-Al2O3 nanofluid flow was used under a solar panel. A number of elliptic fins were attached to the pipe. The fins were holed and configured in three models. The system of the pipe and fins was placed in a chamber filled with CaCl2.6H2O as a phase change material (PCM) under the panel. The proposed solar system was used on a pitched roof to partially supply the energy demand of the Boarding clinic. The energy calculations were carried out in Design Builder. It was found that PCM began to melt at t=40 min. The fins with a central hole led to 10.4% higher melted PCM than double-hole fins at t=100 min. The centrally-holed fins minimized the output flow temperature. However, they also minimized the PVT temperature. It was also found that the proposed system could supply 9.11% of the heating demand of the building in the coldest month of the year. In hot months, however, up to 33.3% of the energy required to heat water could be supplied by the PVT + PCM system.

Thermal and Flow Analysis of Different Shaped Pin Fins for Improved Heat Transfer Rate

In this paper, a micro pin fin heat sink is numerically investigated with four fins geometries (circular, elliptical, square, and drop shape) at two types of arrangement styles, inline and staggered arrangement. The hydrodynamic and thermal characteristics of different fin geometries and two arrangement styles have been compared under the exact value of Reynolds number and constant wall temperature thermal boundary conditions. The Reynolds number was sweeping in the range of (400-2800) to ensure the fluid flow velocity impact in the pin fin performance. The results obtained indicate that a longitude pin fin dropped with increasing Reynolds number at a distributed temperature. Also, the circler Pin fin reaches the lowest temperature comparison to the rest of the three-pin fin types. Generally, according to the extracted, Nusselt number for different geometries increased versus increasing the Reynolds number. Observe that the elliptical fin shape yields the highest Nusselt number at all Reynolds numbers. Moreover, the elliptical pin fin ejects the highest heat transfer rate, which indicates the pin fin performance. Furthermore, skin friction has a significant function with variation in Reynolds number.

Thermal Analysis of Extended surfaces from the Heat sink of Different shape - A Brief Review

This paper introduces a brief review about the way of heat extraction enhancement from heat sink using fins of different types and different shapes and also with different shape of perforation. Extended surfaces from the base plate or heat sink is nothing but they are FINS. There are various types of fin exits. They are Rectangular, Square, Annular, Elliptical, Cylindrical or Pin fin which is utilized with different geometrical combinations. To achieve maximum temperature droop from the base surface or heat sink by using fins numerous trials are completed or being carried out for designing optimized Fin. The optimization of Fin can be achieved by increasing surface contact area with the atmospheric air. In these days there are numbers of experiment is done on fins like Solid fin, Porous fins and Solid fins with perforation, has also been brought off. The various design modifications which are implemented and studied analytically and experimentally by the researchers using ANSYS Work bench is been discussed in this review paper.

Heat transfer enhancement using elliptical fin microchannel

AbstractThermal performance and fluid flow characteristics of elliptical fin microchannel are numerically investigated by varying fin orientation in the laminar flow region. Six distinctly oriented elliptical fins ranging 0°–12° along channel length are numerically examined for inlet Reynolds number (Re) ranging 174–748. The same is compared with the conventional straight fin microchannel. It is found that continuous straight fin when replaced with a series of short length elliptical fins leads to re‐establishment of the thermal boundary layer and results in thinning of boundary layer thickness. By varying the fin angle, fluid is directed from primary channel to secondary channel which finally flows into the primary channel. These secondary flows disrupt the boundary layer and show better fluid mixing in the channel. Among all the orientations considered, elliptical fin oriented at 2° yields better cooling performance ensuing an optimum average Nusselt number enhancement of 116% (7.68–16.64) with a very less pressure penalty (15%). Besides this, the rise in wall temperature is reduced by 25.39% in comparison to straight fin microchannel.

Design and optimization study of a densely packed ultrahigh concentration photovoltaic thermal array for desalination usability

The cogenerated energy from the densely packed ultrahigh concentration photovoltaic thermal systems (UHCPV/T) can not only promote higher exergetic efficiency but also enable the usability of the collected thermal energy for potential desalination purposes. In the present study, three finned heat sink designs of UHCPV/T have been proposed toward maximum collected thermal power and minimum required pumping power. A conjugate heat transfer model has been developed and validated to simulate the different designs under various operating conditions. The cooling setups are based on copper millimeter-scale finned heat sinks immersed in fully developed laminar flow in a rectangular microchannel. It was found that the configuration from the more efficient heat sink design to the poorest thermal one is the rectangular fins (RFs), elliptical fins (EFs), diamond pin-fins (DPFs), and then traditional round pin-fins (TRPFs) heat sink. The RF heat sink has demonstrated the best thermal performance with a maximum multi-junction solar cell (MJSC) temperature of 81.4°C and water temperature increase of 14.21°C under ×1200 and water inlet velocity of 0.02 m/s. Despite the RF heat sink has recorded the highest values of pressure drop and required pumping power equal to 78.74 Pa and 570.7 mW, respectively, it was selected as the optimal heat sink design, ensuring the highest net electrical output power and thermal collected power.

Use of Cuckoo Search Algorithm for Performance Evaluation of Split Elliptic Shaped Fins for Enhanced Rate of Heat Transfer

Abstract Proper dissipation of thermal energy has always been a need for desirable efficiency of a system. Extended surface aids in releasing the heat to the immediate surrounding by inducing an extra area. This particular work assesses thermal and fluid flow behavior of extended surfaces with circular and elliptic shaped cross section. Extended surfaces of unvaried cross section are mounted over a square plate arrayed in a staggered manner. With the aid of different thermofluidic parameters, the elliptic shaped pin fin is established to provide a higher thermal performance enhancement of nearly 15% over cylindrical pin fin at inlet flow velocity of 2.35 m/s. Further, for elevating the interaction between the surface of the fin and the fluid, elliptic fins are reoriented to form a split. In contrast to cylindrical shaped fin, modification using split shows better result with the highest heat transfer increment of nearly 25%. Further, in order to maximize Nusselt number (Nu), a single objective cuckoo search optimization analysis is done by adopting the response surface method. After analyzing the optimization, it is found that the maximum value of Nu is obtained at dimensionless transverse offset (TO*) = 0.125 and dimensionless longitudinal offset (LO*) = 0, which has been further validated with the numerical result within 0.97% accuracy. Further, for the cylindrical fin, the present simulations agree with the available empirical correlation within 6.22% accuracy.

Comparative numerical investigation of rectangular and elliptical fins for air cooled IC engines

In the present numerical examination, thermal characteristics of a rectangular and elliptical fin are compared. The problem considered is assessed with convective tip in a realistic manner. The basic conservation equations are solved by employing SIMPLE scheme in FLUENT 15.0. The numerical results shown 5% enhancement in heat transfer rate through elliptical fin than that of rectangular fin. Also, the attained numerical results are compared with the analytical values and are found to be in good accordance. Moreover, this study forms a basic paradigm for young researchers to understand the importance of CFD in the field of IC engines.

Practical Investigation to Improve the Heat Transfer Performance in Elliptical Fins for Different Axis Ratios by Forced Convection

All engineering industries have proven that there is a demand to maintain heat transfer and in many engineering production processes, an increase in the rate of thermal transfer is required.. The solution lies in adding solid bodies made externally from heat-conducting materials called fins, which in turn have been the subject of very large engineering research by changing shapes, lengths, axis, thicknesses, etc., in order to raise the efficiency of performance in heat transfer to avoid industrial problems and accidents. The materials type and surface area have direct affect of the heat transfer rate depends on the types of materials used and the surface area of the fin. One of the most popular choice is the radial annular fin due to the cylindrical primary surface where the performance of the fins is a function of many parameters, namely the heat transfer coefficient, the fin efficiency and the fins’ thermal resistance. In this research work, an experimental study to investigate the effect of fin heat transfer performance characteristics elliptical fin shape at differnt at its major and minor axis ratio (a/b) with different cooling air velocities. As a results, the optimum ratio is found to be for an elliptical shape fins for forced convection.