Fin Geometry Research Articles

Modelling heat transfer in fins using finite difference method

In this paper a heat transfer analysis through rectangular fins (extended surfaces) is conducted using the finite difference method. The impact of different fins geometries and aspect ratios on the convective heat transfer coefficient is investigated using finite difference approach. Transient heat conduction through fins is modelled using a time implicit scheme and convection heat transfer coefficient is computed explicitly using an empirical correlation from literature.

Phase change materials for thermal management and energy storage: A review

This paper presents a general review of significant recent studies that utilize phase change materials (PCMs) for thermal management purposes of electronics and energy storage. It introduces the causes of electronic devises failure and which methods to control their fails. Moreover, this paper gives an overview of PCMs types and their characteristics and applications. It focuses on the thermal energy storage applications i.e., the use of PCMs in heat sinks to control their thermal efficiency. Also, the methods of enhancing the thermal conductivity of PCM are presented including the addition of nanoparticles to the PCMs or metallic fins manufactured for the heat sink. Furthermore, there is a systemic discussion of the effect of various parameters affecting the performance of the HSs with TCE-PCM. The focus of the discussion is based on lowering the base temperature of the heat sink. All factors affected the thermal response of the HS is deeply illustrated including HS's orientation, fins geometry and shape, power levels, PCM volume fractions, and nanoparticles concentrations.

Research on thermal performance and optimization design of phase change pin fin heat sink based on Lattice Boltzmann method

This paper reports a numerical research of the phase change materials (PCMs) based pin fin heat sinks for thermal management of battery and electronic device. The 58 semi-refined paraffin and several paraffin/CNTs composites (CNT mass fraction of 5 %, 8 %, 10 %) were adopted as PCMs filled in the heat sink. Lattice Boltzmann method (LBM) was used to numerically study the influence of fin geometry (square fin, circular fin, cross fin), fin number (one to five), fin arrangement (array arrangement, cross arrangement) and PCMs on the working performance (charging time and heat dissipation power) of the heat sinks. The LBM code was solved in Visual Basic. The results report that the four/five square fins (arrangement A) heat sink with 10 % CNT compound paraffin has the shortest charging time and the heat sink with four square fins (arrangement A) and 8 % CNT compound paraffin has the largest heat dissipation power. It is worth noted that compared with square fin heat sinks, the cross fin heat sinks still present 83 % of the heat dissipation power with only 36 % of the fin volume. Besides, aiming at acquiring the largest heat dissipation power, a back propagation neural network-genetic algorithm was developed to optimize the structure of the pin fin heat sink. The corresponding fin number, fin side length and fin distance for the optimized square fin heat sink (arrangement A) are 4, 2.13 mm and 5.88 mm, respectively.

Investigating Al-Si base abradable material removal mechanism with axial movement in labyrinth seal system

Modern aeroengines employ labyrinth seal systems to seal the clearance between the blade tip and surrounding engine casing. Understanding of the wear mechanism between labyrinth fins and abradable coatings on the casing is necessary to help the aeroengine achieve higher efficiency. In this study, multiple tests with different types of fin geometries are conducted on a high-speed test rig with a fin tip speed of 100m/s. Two motorized stages are used to simulate the axial movement of the labyrinth fin in an aeroengine. The wear mechanism is investigated over a range of incursion rates from 2μm/pass to 10μm/pass, with in-situ force and temperature measurements along with high-speed imaging recorded on the side in each case. The surface examination of the wear track is also employed by using microscopy post-test. The main abradable material removal mechanism is extruding from the fin side. Also, adhesion of abradable material to the fin is found in each test and the adhesion amount is affected by both fin geometry and incursion rate.

A novel passive solar vertical-finned-thermocatalytic-Trombe wall system for air purification and heating

In this study, the combination of thermocatalytic oxidation technology with finned heat transfer technology was proposed to produce a novel passive solar vertical-finned- thermocatalytic-Trombe wall (VFTC-Trombe wall) system. The numerical model coupled with flow and heat transfer, convective-diffusion and catalytic reaction kinetic processes was established. The influences of fins geometry and environmental parameters on thermal and air purification performance were evaluated. The main findings are as follow: Both the purification efficiency and total efficiency increase with fins height. As the fins spacing rises, thermal, purification and total efficiencies all show maximum values. By adding the vertical fins in the channel, the purification performance improvement of the TC-Trombe wall system can be realized without sacrificing thermal performance. The optimum purification efficiency improves more than 1.5 times compared to that without vertical fins. The vertical fins have more significant effect on the purification performance than the thermal performance. At fins height h = 40 mm, fins spacing s = 16.67 mm, and solar radiation intensity I = 400 W/m2, the maximum total efficiency of VFTC-Trombe wall system reaches 65.11%, which is relatively improved by 31.9% compared to the TC-Trombe wall system without vertical fins. In addition, the impact of ambient temperature on thermal performance is more significant than that on purification performance.

Metaheuristics applied to the optimization of a compact heat exchanger with enhanced heat transfer surface

• A combined geometry of louvered fins and vortex generators is numerically simulated. • Parametric study on the influence of 8 independent variables on j and f. • Independent optimization of all the variables involved in the VG geometry. The heat exchanger compactness is a key factor in several engineering applications, such as, in automotive applications that use enhanced heat transfer surfaces on the air side to improve the convective heat transfer coefficient. In this study, a combined geometry of louvered fins and vortex generators is numerically simulated to optimize the thermohydraulic behavior of a compact heat exchanger. The influence of eight parameters of the enhanced surface on its thermohydraulic performance is analyzed. The thermohydraulic performance is evaluated through the Performance Evaluation Criterion, which relates the Colburn factor and the friction factor, i.e., the heat transfer enhancement and the increment of the pressure losses of the actual model with respect to a reference one. A metaheuristic tool, based on the NSGA-II genetic algorithms, combined with multi-objective optimization technique, is applied. The objective functions used in the optimization are obtained with numerical methods and computational fluid dynamics techniques. As a novelty, the optimization was carried out individually and under non-stationary flow conditions, for a total of eight magnitudes associated with the vortex generators. The optimized geometry is able to enhance the convective heat transfer between 6.55% and 19.63%, with an increase in pressure losses varying from 10.95% to 20.67% depending on the Reynolds number.

Overall Pressure Loss and Heat Transfer Performance of Additively Manufactured Offset Strip Fins Used in Compact Heat Exchangers

Abstract Preliminary heat exchanger design relies heavily on correlations for overall heat transfer and pressure drop performance, particularly for heat transfer augmentation features such as fins. Extensive work has been performed by the research community to develop these correlations for the numerous designs. However, with the new technology of metal additive manufacturing and the resultant surface roughness, the traditional correlations and design considerations related to performance need to be adjusted. As a result, two metal additively manufactured offset strip fin heat exchanger geometries with different fin spacing are studied for heat transfer and pressure drop performance and compared with traditional correlations. Deviations between the additively manufactured geometries and previous correlations for smooth fins are found and are further amplified as the surface roughness-to-hydraulic diameter ratio is increased. Furthermore, the surface roughness from the additive process results in a constant friction factor behavior at high Reynolds numbers, which is unlike behavior observed for conventionally manufactured fins. Considerations for both the laminar and turbulent flow regimes are needed for correct performance prediction. A final offset strip fin geometry with a change in the fin spacing every third of the way through the flow path is tested. This study found that the orientation of fin spacing, wider spaced to tightly spaced or tightly spaced to wider spaced, did not have a significant effect on pressure drop or heat transfer. However, the study found a method for predicting the performance which will become important as additive manufacturing increases the complexity of heat exchanger designs.

Analysis of engine cylinder block with fins by varying different materials

Aluminium alloy AA 6061 material is used in this study, and the engine cylinder is one of the most important automotive products that is subjected to high-temperature changes and thermal stresses. Fins are placed on the surface of the cylinder to boost the rate of heat transmission, which helps to cool the cylinder down more quickly. It is beneficial to perform thermal analysis on the engine cylinder fins to determine the amount of heat dissipation occurring inside the cylinder. Because increasing the surface area results in an increase in the heat dissipation rate, developing a large complex engine is extremely difficult. By altering the geometry of cylinder fins and analyzing the results with the Ansys workbench, the primary goal of this paper is to understand the thermal properties of cylinder fins. With the help of CREO parametric software, the geometries are transformed into a 3D model, which is then subjected to thermal analysis using the Ansys workbench. It is important to understand how temperature distribution changes over time since it is useful in many applications, such as cooling. The accurate thermal simulation may allow for the identification of important design parameters that will improve the life of the product. In the present work, the three different materials of AA6061, cast iron and AZ31 magnesium alloys were chosen during the simulation of temperature and heat flux distribution on the engine block and were analyzed. The aluminium alloy 6061 utilized in the fabrication of the cylinder fin body has a thermal conductivity of 160 – 170 W/mk which showed good performance and it is recommended in the construction of the cylinder fin body.

Thermo-hydraulic performance in ceramic-made microchannel heat sinks with an optimum fin geometry

Efficient heat rejection from modern microelectronic equipment plays a substantial role in increasing the functionality and longevity of these products. Microchannel heat sinks (MCHSs) are one of the liquid-cooling technologies, and it is needed to increase their heat transfer performance to acquire higher cooling capacity. In the current numerical study, two distinct strategies are suggested to ameliorate the heat transfer behavior of the MCHSs. First, straight-slot fins with different aspect ratios (b/a = 1.5, 2, 2.5, 3, 4, and 5) are added to the microchannels. The heat transfer and pressure drop properties in the finned-heat sink are analyzed numerically. After investigating straight-slot fins and selecting the optimum model, the heat sink's material is changed from alumina to Aluminum nitride (AlN) and Beryllium oxide (BeO). The impact of utilizing these two advanced ceramics on the thermo-hydraulic performance of the MCHS is examined. According to the obtained results, the MCHS with longer straight-slot fins (b/a = 5) indicated higher thermal performance values at all investigated Reynolds numbers. Changing the optimum model's material from alumina to AlN and BeO ceramics, the MCHS's thermal performance was enhanced by about 3.72 and 4.22 times (at the Reynolds number of 300), respectively.

Steady State Free Convection through some Variable Fin Geometries

Thermal performances on some typical variable geometries were conducted in this work which can be reported into two phases. In the first phase of this work, fins of rectangular, cylindrical, and conical geometries having the same total surface area were studied. It is found that the cylindrical fin is the least efficient and least effective among the three. In the second phase, design modification in the form of grooves is made on cylindrical fins. Cutting grooves on cylindrical fins increase its surface area. The three grooved cylindrical fins are namely- fully grooved cylindrical fins, bottom half grooved cylindrical fins, and top half grooved cylindrical fins. All three grooved fins have the same volume. It was noticed hat, on cutting groove the on fin the quality of convective heat transfer, as well as the effectiveness, improves, but the efficiency degrades. Keywords: Finite Element Method, thermal steady state, fin effectiveness, fin efficiency, free convection

Parametric Study on Thermo-Hydraulic Performance of NACA Airfoil Fin PCHEs Channels

In this work, a discontinuous airfoil fin printed circuit heat exchanger (PCHE) was used as a recuperator in a micro gas turbine system. The effects of the airfoil fin geometry parameters (arc height, maximum arc height position, and airfoil thickness) and the airfoil fin arrangements (horizontal and vertical spacings) on the PCHE channel’s thermo-hydraulic performance were extensively examined by a numerical parametric study. The flow features, local heat transfer coefficient, and wall shear stress were examined in detail to obtain an enhanced heat transfer mechanism for a better PCHE design. The results show that the heat transfer and flow resistance were mainly increased at the airfoil leading edge owing to a flow jet, whereas the airfoil trailing edge had little effect on the thermo-hydraulic performance. The airfoil thickness was the most significant while the arc height and the vertical spacing were moderately significant to the performance. Moreover, only the airfoil thickness had a significant effect on the PCHE compactness. Based on a comprehensive investigation, two solutions NACA-6230 and -3220 were selected owing to their better thermal performance and smaller pressure drop, respectively, with horizontal spacings of 2 mm and vertical spacings of 2 or 3 mm.

A Numerical Investigation of Laterally Loaded Steel Fin Pile Foundation in Sand

Pile foundations are often subjected to lateral loadings. By adding steel plates (fins) to the side of the pile, steel fin pile foundations (SFPFs) can improve the lateral load capacity of piles. Existing numerical studies using elastic–perfectly plastic models (e.g., Mohr–Coulomb model) for soil behavior may result in unrealistic load response when modeling soil–pile interaction in dense sand due to the lack of consideration of strain-hardening/softening behavior. In the present study, finite-element analyses were conducted to understand the effect of fin geometry on the lateral load capacity of SFPFs. The prepeak hardening and postpeak softening soil behavior was accounted for by varying soil strength parameters with plastic shear strain based on a modified Mohr–Coulomb model. The developed model was calibrated and validated against well-documented experimental and field tests in the literature. The validated model was subsequently used to conduct a parametric study to understand the effect of fin geometry on the response of SFPFs subjected to lateral loading at the pile head. The behavior of SFPFs at different displacement levels and load levels was studied. The effect of the relative density of soil on the performance of SFPFs was also investigated. Based on the numerical simulation results, the optimal fin width and length values for mobilizing soil resistance were suggested and the underlining mechanisms affecting the efficiency of fins were discussed.

EXPERIMENTAL AND COMPUTATIONAL ANALYSIS OF A COPPER BASED RADIATOR OF A MOTORCYCLE TO DETERMINE ITS COMPACTNESS BY MODIFICATION OF GEOMETRY OF FINS.

In the Internal Combustion Engines, the radiator system plays a vital role in the management of the thermal efficiency. The good conditioned radiator increases the performance of engine by removing the heat effectively. Thus, the present project work is fundamentally based on the investigations of modelling of radiator made of copper, through the experimental and CFD analysis. Further the effects of increased thickness of fin and the perforation on the fin is analyzed. The work is focused on increasing the heat transfer from the copper fin with the perforation (circular hole) to cool the engine using forced convection method effectively for the improved performance of the engine. The radiator is analyzed with mass flow rate and inlet temperature as boundary conditions for hot water flow. Similarly for air flow inlet velocities and temperatures are taken as a boundary conditions. For this purpose, a copper-based radiator is fabricated and tested for four volumetric flow rates of the hot water. The performance of this radiator is evaluated in terms of outlet temperature of water and heat flow. It is predicted and proven that modifications in fin geometry plays a vital role in improving the performance of engine by cooling water circulation effectively. Thus, making the radiator compact

Assessment of an Exhaust Thermoelectric Generator Incorporating Thermal Control Applied to a Heavy Duty Vehicle

The road transport industry faces the need to develop its fleet for lower energy consumption, pollutants and CO2 emissions. Waste heat recovery systems with Thermoelectric Generators (TEGs) can directly convert the exhaust heat into electric energy, aiding the electrical needs of the vehicle, thus reducing its dependency on fuel energy. The present work assesses the optimisation and evaluation of a temperature-controlled thermoelectric generator (TCTG) concept to be used in a commercial heavy-duty vehicle (HDV). The system consists of a heat exchanger with wavy fins (WFs) embedded in an aluminium matrix along with vapour chambers (VCs), machined directly into the matrix, that grant the thermal control based on the spreading of local excess heat by phase change, as proposed by the authors in previous publications and patents. The TCTG concept behaviour was analysed under realistic driving conditions. An HDV with a 16 L Diesel engine was simulated in AVL Cruise to obtain the exhaust gas temperature and mass flow rate for each point of two cycle runs. A model proposed in previous publications was adapted to the new fin geometry and vapour chamber configuration and used the AVL Cruise data as input. It was possible to predict the thermal and thermoelectric performance of the TCTG along the corresponding driving cycles. The developed system proved to have a good capacity for applications with highly variable thermal loads since it was able to uncouple the maximisation of heat absorption from the regulation of the thermal level at the hot face of the TEG modules, avoiding both thermal dilution and overheating. This was achieved by the controlled phase change temperature of the heat spreader, that would ensure the spreading of the excess heat from overheated to underheated areas of the generator instead of wasting excess heat. A maximum average electrical production of 2.4 kW was predicted, which resulted in fuel savings of about 2% and CO2 emissions reduction of around 37 g/km.

Numerical simulation of the thermal performance of a wavy fin configuration for a straight fin array

Fins over the years have been used as heat exchangers for exchanging heat generated in engineering machines or systems, between the system surface and the ambient air. However, the challenge of thermal design for the best geometry of heat fin prompted the study, to determining the performance of a wavy and straight fin projecting vertically from a horizontal base, by comparing their rate of heat transfer. In this study a free convection steady state numerical analysis was carried out using Solidworks 2018 flow simulation application, which is based on finite volume method of Computational Flow Dynamics (CFD). The numerical analysis was carried out on three different fin array configurations, all of the same fin spacing or separation distance. The three fin array modeled includes the straight and wavy fin of fin height, 35mm and spacing, 14.2mm respectively. The third fin was a straight fin of height, 50mm equivalent of the effective wavelength of the wavy fin, but of same fin spacing. Aluminum metal was selected as the material, and the simulation was done using air as the fluid, of temperature, and convective heat coefficient, 27°C and 20W/mK respectively. Simulation was carried out at different temperatures for each geometry, ranging from 45°C – 120°C. The results showed that the difference in the rate of heat transfer for the wavy fin and straight fin were close at low temperatures, but significantly increased to about 28% at higher temperatures in favor of the wavy fin. The third fin had an insignificant 9% heat transfer rate higher than the wavy fin but with 43% additional height, thereby occupying more space. It is established from this study that wavy fin array possesses higher convection heat transfer performance than the straight rectangular fin array. Therefore, in a bit to achieve high performance heat transfer with limited space, a wavy fin array is recommended.

Effect of proportions of fins with radial branches on the lauric acid melting process in an annular cavity

Energy storage systems with phase change materials (PCM) are characterized by high energy density, with a low thermal and volumetric variation. However, the usual low thermal conductivity increases energy charging and discharging times. An established solution to enhance heat exchange is the use of fins. The objective of the present work is to analyze the effect of innovative fin geometry on the melting process of Lauric acid PCM in an annular cavity. In the case studies, the fins cross-sectional areas were considered constant, then varying the proportions and positioning of the fin branches for two different area fractions between the fin and cavity. The numerical model, validated with experimental data from reference works, consisted of the continuity, momentum, and energy conservation equations complemented by an enthalpy-porosity phase change model. The results showed that the melting rate effectiveness reached average values up to 146% compared to a finless system. The increase in branches intensified the natural convection while its positioning was decisive for total melting time reduction. Positioning the branches close to the heated inner core or outer cavity wall reduced the melting rate due to the fluid circulation inhibition.

Investigation on Cooling Rate of Different Fin Design of an I.C. Engine by use of CFD

The Cylinder block is most important components in IC engine vehicles, which is under very high temperature stresses. To control the engine in efficient way we required to cool the cylinder, extended surface is provided on the cylinder to increase the speed of temperature reducing. By doing thermal analysis on the cylinder block fins, it is helpful to find the heat transfer outside the cylinder. The principle use in this research is to improve the heat dissipation rate by using the surrounding air flow direction and new geometry. We all know that, by expanding the surface area we can improve the heat transfer rate, so designing fin geometry. The main aim of using these cooling fins is to cool the engine cylinder by environmental air. The main aim of the research is to analyze the thermal properties by varying geometry, material and thickness of cylinder fins. Model is created to analyze and simulation purpose in solid works software. The models are created by varying the geometry and shape of fin. Present thickness and shape of the fin is changed. The 3D modelling software used is Solid works. In the current year Material used for manufacturing cylinder block’s fin body is Aluminium Alloy 204 it has thermal conductivity of 110-150W/mk. In this research, it is replaced with aluminium alloy 6061 and analysis is done in Ansys.

Heat and Flow Study of the Internally Finned Tubes with Different Fin Geometries

Heat and flow enhancement is a critical weapon for the design of highly efficient, compact, and cost-effective devices. The objective of this analysis is the detailed examination of the implementation of different fin shapes on the internal side of a tube aiming the heat and flow enhancement. The reference empty tube is examined, while the use of circular, rectangular, and triangular fins is also studied. Different simulations were conducted with a developed computational fluid dynamic model, and the results were expressed in heat and flow terms. The developed model was validated by comparing the results with the theoretical expressions for the Nusselt number, as well as for the friction factor. The obtained results were evaluated by calculating the heat convection coefficient, the pressure drop, the Nusselt number, the friction factor, the pump work, the mean wall temperature, and the Bejan number. According to the calculations, the use of rectangular fins is the best solution; the use of triangular fins is the second choice, while the less efficient improvement method is the use of circular internal fins. Regarding the heat transfer enhancement, the rectangular fins lead to 36% enhancement, circular fins to 25%, and triangular fins to 23% compared to the reference tube.

Analysis of total ionizing dose response of optimized fin geometry workfunction modulated SOI-FinFET

The total ionizing dose (TID) response of SOI-FinFET with linear gate workfunction modulation is presented and evaluated. The gate metal workfunction is linearly modulated from source to drain to maintain the electrostatic integrity of the device. At the higher radiation dose (2000 krad), the proposed device has shown reduced Off-current by 2-decade leads to improvement in current switching ratio. Moreover, the proposed device offers 9% and 3% improvement in subthreshold swing before and after the radiation, respectively. During irradiation the trap charges are found in the BOX layer and SiO2/Si interface. These charges contributed towards shifting of threshold voltage (Vth). The linear workfunction modulation shows a 73% more Vth as compared to single workfunction FinFET for radiation of 2000 krad dose. As per simulation results, the proposed device is reliable and capable to sustain in the radiation environment.

Total Entropy Field in a Complex Helical Fin-and-Tube Heat Exchanger

We present a comparative evaluation of the generated entropy fields obtained via two different approaches: 1) a direct integration of the transport equation for the entropy, and 2) an a posteriori processing of the thermal and velocity fields produced by the energy equation. In both cases, we numerically solve the Reynolds-averaged equations with a two-layer model to account for the turbulent effects. The process under consideration takes place inside a heat exchanger with two helical fin-and-tube configurations, which include plain and serrated fin geometries. Our analysis suggests that 1) the entropy fields produced with the two calculation approaches may differ, depending on how the convective–diffusive effects are computed relative to the generation effects; 2) the serrated fin geometry represents a significant advantage over the plain geometry when installed in the first three stages of the tube array; and 3 the convective entropy transport is higher than the diffusive entropy transport by one order of magnitude. These results are relevant to the design of efficient heat exchangers for aerospace applications.