Fin Shape Research Articles

Design and thermal performance analysis of a new micro-fin liquid cooling plate based on liquid cooling channel finning and bionic limulus-like fins

As the current channel-type liquid cooling plate generally suffer from high pressure loss and low cooling efficiency, making electric vehicles have to face problems such as high battery pack temperature and short mileage. To solve the above problems with channelized liquid-cooled plate, the conventional liquid-cooled channel was first rectangularly finned, and the size of the fins was optimized by varying the longitudinal spacing ratio f/a and transverse spacing ratio w/b between adjacent fins. Results show that the liquid-cooled plate had the lowest average temperature and pressure drop and the best overall performance when the size of the fins in the corresponding directions and the size of the spacing between the corresponding directions were equal. Secondly, on the basis of the optimization, the preferred fin form was preliminarily biomimetic. CFD simulation results show that the bionic limulus-like fins (BLLF) were more effective, with pressure drop (ΔP) and average temperature (T_ave) improved to a certain extent, compared with the rectangular and oval conventional shape fins. Subsequently, the number of inlets and outlets and their layout positions were discussed. Then, in order to further improve the performance of the cold plate, according to the shape characteristics of the limulus, the scrambler fins were homogenized to form a central channel and two secondary channels were added diagonally upward, which continued to construct a new type of microfin for the bionic limulus, and a multi-objective optimization of the secondary channels was carried out with L, W, α, and β as the parameters. Compared with the original model, T_ave and ΔP of the optimal model were reduced by 1.69 °C (4.61 %) and 6.81 Pa (54.26 %). Finally, the effect of the variation of Reynolds number on the thermal performance was discussed. It can be seen that the bionic fin design approach obtained in this study will provide a reference for liquid-cooled channel finning optimization.

Effect of trailing-edge shape on the swimming performance of a fish-like swimmer under self-propulsion

Tuna, dolphin and whale as typical thunniform mode fish have obvious differences in body size and caudal fin shape. As the main propeller, the difference in the shape of caudal fin will have a significant impact on the swimming performance of fish. In this work, numerical simulations are adopted to study the hydrodynamics of self-propelled thunniform swimming. By changing the trailing-edge profile parametrically, three different tails varying from forked tuna-like tail to the square-shaped tail are constructed. The results revealed that the tuna-like tail is most beneficial to fish long distance cruise, while the square-shaped tail is the most unfavorable. It is interesting to note that for tuna-like tail, decreasing the undulating amplitude can improve fish's long-distance cruising ability more than decreasing the pitching amplitude, but the opposite is true for the square-shaped tail. Further study on the vortex dynamics and the surface pressure distribution indicate that the backward expansion of the trailing-edge profile will delay the shedding of the leading-edge vortex and increase the existence time of low-pressure region on the caudal fin. Since the pitching angle is reduced synchronously, the delayed disappearance of the low-pressure region will generate more lateral force. This will lead to more energy loss.

Geometric Modeling and Estimation of Robotic Fin Shape with Bending Actuators and Passive Elements

Geometric Modeling and Estimation of Robotic Fin Shape with Bending Actuators and Passive Elements

Extensive analysis of PCM-based heat sink with different fin arrangements under varying load conditions and variable aspect ratio

The present study compares a modified variable height fin heat sink with the conventional constant height fin heat sink. The two heat sinks are filled with an equal volume of PCM (n-eicosane) and a fin volume fraction of 8 %. The experiments are performed for constant loads and also different power surge conditions. The pulsed heat loads are applied for two scenarios: 1. Constant load 4 W - power surge and constant load 4 W - power surge - 1800 s no-load condition, and 2. Power surge (50 s, 100 s, and 150 s) - no-load conditions of 1800 s. During experiments, the proposed variable height fin heat sinks possess better thermal performance for all load scenarios. Further, a 3D computational model is developed using ANSYS Fluent 19 to assess not only the effect of fin arrangement for different aspect ratios but also the impact of fin shape. The enclosure aspect ratio employed for the given study ranges from 0.3 to 0.8 for both the heat sinks. Regarding the fin structure in a heat sink, four types of fin shapes are adopted: square, circular, diamond, and triangular. The contour images of temperature and the liquid fraction are shown for the charging process. For the discharging process, the time required for the heat sinks to completely solidify the PCM is discussed. From the outcomes, variable height fin heat sinks provide enhanced melting/solidification for all the aspect ratios and fin shapes considered. As the aspect ratio increases, the time difference between the heat sink for the completion of the discharging cycle is reduced. Moreover, the triangular shaped fin shows a higher enhancement percentage of 2.29 % and 1.43 % during melting and 6.25 % and 12.5 % during solidification for both the heat sinks, respectively.

Detection of frost growth and distribution on louver and offset strip fins of a microchannel heat exchanger using capacitance sensing approach

Frost growth and distribution on a microchannel heat exchanger (MCHX) are measured using a capacitance sensing approach. Capacitive sensors using two electrode layouts are developed to detect the real-time frost growth in the direction along and perpendicular to the airflow. Frosting and defrosting experiments are conducted under different air and coolant temperatures on both louver fins and rectangular offset strip (ROS) fins. The results demonstrate that the frost thickness is measured on the actual heat exchanger surface with an estimated uncertainty of ± 0.128 mm (95% confidence). A delay of frost growth on the trailing edge is captured by the sensor for both fin structures, and a larger frost thickness is obtained under lower air and coolant temperatures. The fin shape effect on the frost distribution profile is also characterized using the sensor. Compared to that on louver fin, the frost thickness at the leading edge of ROS fin is larger, as is the frost thickness difference between the leading and trailing edges. Due to the louver effect, the frost is more uniformly distributed over the fin. Based on the capacitance data at five locations, a frost distribution map is constructed and agrees well with frost imaging. This work demonstrates the development and application of a novel method for frost distribution detection for heat exchangers, providing a powerful tool for the study of the frosting process and defrost control.

Heating performance enhancement in panel-type radiators based on vortex generators and fin form optimization

Increasing the heat performance of heating radiators could be a valuable method for building energy conservation. This paper studied the influence of fins on the thermal performance of panel radiators (type 11). The effect of different vortex generator angles, the gap width of discontinuous fins, and different forms of staggered fins have been studied numerically and experimentally. Firstly, the simplified model of the panel radiator was analyzed by CFD simulation, the thermal performance under different geometric parameters was studied, and better geometric parameters were obtained. Research shows that optimizing the parameters of the vortex generator has a positive effect in increasing the heat dissipation of the radiator. Both discontinuous fins and staggered fins can improve the thermal performance of the radiator. The research shows that the fin shape has a significant impact on the heat dissipation of the radiator. The thermal performance of the radiator can be greatly improved by using a vortex generator with specific angles, staggered fins, and discontinuous fins. These technical routes can be directly implemented on the basis of the original radiator, which provides a direction for the technical improvement of this type of radiator.

Numerical Investigation of Pin Fin Types on the Thermal Improvement of H2/Air Micro Burner

The micro-thermophotovoltaic system is a prospective power generation system. The radiation performance of exterior walls is a critical component of MTPV, as it effectively determines the overall energy output. At a mixture intake speed of 10 m/s, the MCPFs-Diamond exhibits the most favourable thermal performance, as evidenced by the thermal distribution and the highest average temperature of the exterior walls, which measures 1255.3 K. Its available radiation energy can reach up to 43.6 W. In the case of micro combustors that incorporate alternative shapes of pin fins, the highest values for both the average external wall temperature and the available radiational energy are achieved when the gas intake speed is set to 8 m/s.

Simulation for performance of storage unit with analyzing water freezing in presence of nanoparticles

The influences of loading alumina with different range of diameter and concentration have been considered in this study. The single phase mixture for predicting the features of nanomaterial was incorporated and equations in unsteady form were presented. For deriving the solution of the model, Galerkin method was used incorporating implicit technique. Validation tests have been provided and reasonable accuracy has been obtained. The geometry has tree shape fins which can help to accelerate the process. Although increasing size of powder can augment the interaction of them, the freezing time increases if the size of particles increases greater than 40 nm. Adding nano-powders can decrease the required time by about 41.26 %. With the changing size of nanoparticles, firstly, freezing time decreases about 20.02 % then it increases about 49.33 %. The minimum required time for freezing is 3991.58 s and this period happens when dp = 40 nm and ϕ = 0.04.

Numerical analysis of the impact of fin design and solar radiation on the cooling performance of a power transformer

In the present work, a three-dimensional model was performed to test a geometry and solar radiation effect on the cooling efficiency of a 250 kilovolt-ampere (kVA) oil-natural-air-natural (ONAN) electrical distribution transformer. Several fin shapes and other geometric aspects of the transformer were analyzed numerically (trapezoidal, wavy, and triangle fins).According to the findings, the trapezoidal fin shapes were the most effective in lowering the transformer's average surface and core temperatures, followed by the wavy fins and the triangular fins compared to the traditional transformer shape (straight fins). The study also showed that the temperature of the surface and the core of the transformer increases with increasing solar radiation, but the effect of high temperature as a result of electrical load is more influential than solar radiation. The results showed a significant convergence with previous research.

Numerical analysis of the magnetic field impact on hydrothermal characteristics of a microchannel heatsink with Fe3O4 ferrofluid and various pin-fin shapes

Enhancing the hydrothermal proficiency of thermal management devices by integrating active and passive heat transfer techniques is possible. Under magnetic field (MF), pin–fin heat sinks have rarely been studied in terms of frictional losses and coefficient of heat transfer (h). Here, with a nanoparticle concentration ratio of 2%, Fe3O4 ferrofluid flow inside a pin–fin heatsink was analyzed numerically considering various pin–fin shapes (rhumbas, squares, circles, and triangles) for absenteeism (WO) and attendance (W) of MF. In the results, the greatest and lowest gains for h were 13.12% and 8.8%, respectively, utilizing MF and Re = 200, for the circular and triangular heatsinks, which would be reduced to 5.36% and 2.41% by increasing Re to 500. In addition, h (and thermal resistance factor) in triangular configuration is 7.82–10.86% (and 4.98–8.68%) and 3.23–8.08% (1.94–6.22%) greater (and smaller) than that in the circular design under two scenarios of MF. Moreover, MF brings about a reduction of 1.86–0.60%, 1.61–0.46%, 1.71–0.54%, and 1.16–0.24% in Tm,CPU for the circular, square, rhumbas, and triangular configurations, respectively, within the Re range of 200–500. Although, when MF is present, pressure loss escalates by almost 6.39%, 4.97%, 3.60%, and 2.92% at Re numbers of 200, 300, 400, and 500 for each configuration, with the maximum pressure loss for triangular heatsink compared to the other arrangements. PEC factors at different Re numbers range from 1.51 to 1.87, suggesting an improved heatsink hydrothermal performance under MF impact compared to absenteeism of that. The highest/lowest PEC values at Re numbers 200 and 500 are associated with the rhumbas/triangular (1.871/1.782) and Triangular/square (1.547/1.496) configurations, respectively.

Using artificial intelligence and two-phase numerical simulation method for investigating the effect of the shape of pin fins on the entropy production of nanofluid flow in a heatsink at different flow rates

Numerical simulations of a heatsink (HTK) are performed in this article for cooling a heat source with multiple pin-fins (PFS). The HTK is placed in a channel with alumina/water nanofluid flow. The two-phase nanofluid is simulated using the finite element method (FEM). Artificial intelligence is also utilized for data analysis. The results of this study demonstrate that the enhancement of Re from 200 to 600 reduces the maximum temperature (T-mx) in the square and rhombus PFS by 6.8% and 7%, respectively. The increase of Re from 200 to 600 decreases the average temperature (T-av) of the HTK by 6.8% and 6.9% for square and rhombic PFS, respectively. An increment in Re diminishes the outlet temperature (T-ot) for both pin-fin shapes. As Re is enhanced, the amount of Δp is intensified. The use of square PFS results in more values of Δp in the HTK compared to the rhombus ones. A maximum enhancement in Δp, i.e. 17.9%, corresponds to Re = 600. The square shape of PFS generates more thermal, frictional, and total entropy than the rhombic shape of PFS. The increase of Re reduces the thermal ENG and enhances the frictional and total ENG for both shapes of PFS.

Investigation of free convection heat transfer from vertical cylinders with semicircular fins

ABSTRACT In this paper, the effects of three parameters on the thermal performance of the vertical cylinder with semicircular fins was investigated experimentally. The fin shape, fin number and input heat flow on the thermal performance are studied effected. Three different heat sink models (SC-0, SC-40, and SC-50) were contrasted in order to choose the best reference model. The result show that the heat transfer coefficient increased up to 30% with SC-0 and SC-40, 27% with SC-0 and SC-50, while the thermal resistance of the radial heat sink was demonstrated to be less than that of SC by 17% with SC-40 and less than 19% with SC-50. Additionally, it was found that, the larger number of fins was more effective at dissipating heat than the smaller number of fins, this can be attributed to the heat transfer occurred under natural convection conditions. Finally, to developed Nusselt number correlation with experimental data, the correlation shows the good agreement with experimental data with error less than 5%.

The Arrangement and Cross-sectional Shape of Cooling Fins on Train Brake Discs

Taking into account physical factors such as the wind effect of the brake disc pump, heat dissipation power, and temperature rise, the optimal cross-sectional shape and layout of the brake disc cooling fins are studied. The flow field distribution and pump-wind heat dissipation power ratio of four different cross-sectional shapes, namely circular, elliptical, square, and rhombic, are compared and analyzed. The flow characteristics, wind effect, and heat dissipation power of the cooling fins under two different layouts, namely crosswise and parallel layouts, are also analyzed. The research results show that the circular cooling fins have the optimal pump-wind loss and heat dissipation power, and the crosswise layout of cooling fins shows the best comprehensive performance. The performance analysis method of cooling fins obtained in this paper provides a reference for the optimization design of brake disc structures.

Numerical investigation of the hydrothermal performance of novel pin-fin heat sinks with hyperbolic, wavy, and crinkle geometries and various perforations

In the current work, pin-finned heat sink applications comprising crucial thermal engineering problems are taken into account. Nonetheless, design optimization is still required. The goal of the study was to fill a gap in the literature by using staggered pin fins using a variety of new combinations of perforation and fin shapes. For the pin-fin arrays under consideration, three-dimensional incompressible flow and heat transport are modeled using the ANSYS Fluent software. With the proper boundary conditions included, all of the governing equations of fluid flow are numerically solved. The turbulence is modeled by a realizable κ-ε model. The Nusselt number (Nu) improved by 47.85% and 50.93% for the elliptical perforated wavy pin fin and wavy perforated crinkle pin fin, respectively, at a Reynolds number of 44502. Approximately 13% pressure drop reduction was seen for an elliptical perforated hyperboloid shape that yields hydrothermal performance factor (HTPF) of roughly 45% compared to the cylindrical case. Also, at Re = 44502, the promising Copper-Diamond composite on a hyperboloid shaped pin fin with elliptical perforation case increased the HTPF by 95%. For a variety of industrial applications, this design can be incorporated.

Evolutionary design with freedom - Fin shapes and entrance length channels for heat sinks

The new direction traced in this article is to vary freely and simultaneously the fin and flow channel aspect ratios in the search for the complete high-density heat transfer flow architecture. We show that when the combined solid and fluid volume is specified, and the fluid flow rate is known, it is possible to anticipate from theory the complete design (all the aspect ratios) of the flow configuration. The power to predict covers the overall heat transfer rate and the required pumping power. The configuration and performance owe their existence to the multiple degrees of freedom identified in the design, and exploited in the theory.

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.

Numerical study about thermal performance evaluation of PCM and PCM/fins composite-based thermal control module at microgravity conditions

Satellite subsystems are becoming smaller and have extra power density. There are only two types of heat transport in space: conduction and radiation, making thermal management more difficult. For the thermal regulation of satellite subsystems, thermal energy storage materials are appropriate. In the present study, small satellite subsystems were controlled using a phase change material (PCM)-based heat sink. The design of the aluminium heat sink was according to the outside dimensions of the subsystem in a small satellite. The PCM material used in the work was RT 35. Integrated fins of various shapes were used to overcome PCM's poor thermal conductivity. Three fin geometries were investigated: parallel fins, cross fins, and pin fins. Three shapes of pin fins were evaluated: square pin, circular pin, and triangular pin fins. The heat sink was exposed to a thermal cycle with 80 min cooling and 10 min heating processes. The results reveal that pin fins have better thermal performance than cross and parallel fins. For pin fins, the triangular pin fin provides the best thermal performance among all cases. Maximum temperatures reported for triangular pin fin were 41.5 °C with a 10.8 % reduction. The results indicated a considerable improvement in thermal performance by increasing the number of pin fins.

Investigation and simulation of parabolic trough collector with the presence of hybrid nanofluid in the finned receiver tube

The present study discusses the thermal performance of the receiver tube, which contains a wall with various fin shapes in the parabolic trough collector. Inserted fins and bulge surfaces of the inner wall of the receiver tube increase the turbulent fluid flow. In pursuance of uniform distribution of heat transfer, various fin shapes such as square-shape, circle-shape, triangle-shape, and combined square-circle shapes were inserted, examined, and compared. A study of the temperature differences and fluid flow is meaningful for this project therefore finite volume method was used to investigate heat transfer. Also, hybrid Nano-Fluid AL2O3CuO, TiO2Cu, and Ag-MgO were applied to increase thermal diffusivity. When the combined square-circle-shaped fin was inserted, the thermal peak of fluid flow in the receiver tube was lower than the other studied fin shapes by almost 1%. Besides, the hybrid nano-fluid Ag-MgO Syltherm-oil-800 has lower thermal waste in comparison to others by more than 3%.

Numerical Investigation of Fluid Flow and Heat Transfer in High-Temperature Wavy Microchannels with Different Shaped Fins Cooled by Liquid Metal.

The microchannel heat sink has been recognized as an excellent solution in high-density heat flux devices for its high efficiency in heat removal with limited spaces; however, the most effective structure of microchannels for heat dissipation is still unknown. In this study, the fluid flow and heat transfer in high-temperature wavy microchannels with various shaped fins, including the bare wavy channel, and the wavy channel with circular, square, and diamond-shaped fins, are numerically investigated. The liquid metal-cooled characteristics of the proposed microchannels are compared with that of the smooth straight channel, with respect to the pressure drop, average Nusselt number, and overall performance factor. The results indicate that the wavy structure and fin shape have a significant effect on the heat sink performance. Heat transfer augmentation is observed in the wavy channels, especially coupled with different shaped fins; however, a large penalty of pressure drops is also found in these channels. The diamond-shaped fins yield the best heat transfer augmentation but the worst pumping performance, followed by the square-, and circular-shaped fins. When the Re number increases from 117 to 410, the Nu number increases by 61.7% for the diamond fins, while the ∆p increases as much as 7.5 times.

Impact of fin aspect ratio on enhancement of external quantum efficiency in single AlGaN fin light-emitting diodes pixels

Previously, we showed within a sub-micron fin shape heterojunction, as current density increases, the non-radiative Auger recombination saturates mediated by the extension of the depletion region into the fin, resulting in a droop-free behavior. Here, we investigate the dependence of the fin aspect ratio (height to width ratio) on external quantum efficiency (EQE) of single n-AlGaN fin/p-GaN heterojunctions. Fins are arranged in an array format varying in width from 3000 to 200 nm. In this architecture, an n-metal contact is interfaced with the non-polar side facet of the fin. At a fixed current density, as the aspect ratio increases from 0.2 to 3 (the fin width reduces), we systematically observe an increase in the ultraviolet (UV) excitonic emission of the AlGaN fin and a 7× enhancement in the EQE. We explain this phenomenon by conserving the volume of the carrier depletion region within a fin. As the fin gets thinner, the base area of the depletion volume shrinks, whereas its height increases within the fin. This geometrical advantage allows a 200 nm wide fin to operate at 1/3rd the current density compared to a 3000 nm wide fin while generating a UV emission with a comparable power of 1 μW. These findings show additional parameters that can be used for developing brighter light sources, including the shape and aspect ratio of a heterojunction at the micro- or nano-scale.