Fin Position Research Articles

MHD Forced Convection Using Ferrofluid Over a Backward Facing Step Containing a Finned Cylinder

Abstract In this paper, a numerical study of forced convection on a backward facing step containing a single-finned fixed cylinder has been performed, using a ferrofluid and external magnetic field with different inclinations. The partial differential equations, which determine the conservation equations for mass, momentum and energy, were solved using the finite element scheme based on Galerkin’s method. The analysis of heat transfer characteristics by forced convection was made by taking different values of the Reynolds number (Re between 10 and 100), Hartmann number (Ha between 0 and 100), nanoparticles concentration (φ between 0 and 0.1) and magnetic field inclination (γ between 0° and 90°); also, several fin positions α [0°–180°] were taken in the counter clockwise direction by a step of 5. After analysing the results, we concluded that Hartmann number, nanoparticles concentration, Reynolds number and magnetic field angles have an influence on the heat transfer rate. However, the fin position on the cylinder has a big impact on the Nusselt number and therefore on heat transfer quality. The best position of the fin is at (α = 150°), which gives the best Nusselt number and therefore the best heat transfer, but the fin position at (α = 0°) remains an unfavourable case that gives the lowest Nusselt values.

A Study on the Whole-skin Peeling System of a Snakehead Based on Three-dimensional Reconstruction

HighlightsA 3D reconstruction algorithm is proposed to determine the snakehead area.The whole-skin peeling system of snakehead is designed by a convolutional neural network.An automatic whole-skin peeling device is presented with computer vision technology.Abstract. A whole-skin peeling system for a snakehead is designed in this article. The snakehead photos are taken from multiple angles and are first filtered to extract the image features, before reconstructing the sparse model. Then, the characteristic parameters of the snakehead are determined through the point cloud coordinates, and dense reconstruction is carried out based on sparse points. The accurate three-dimensional spatial coordinates of the snakehead are obtained by the octree algorithm and Poisson surface reconstruction algorithm. Based on the triangular meshing algorithm, the skin area of a snakehead is calculated to determine whether the snakehead meets the peeling conditions. A trained Faster Region Convolutional Neural Network (R-CNN) is used to identify the fin position on the snakehead reconstruction model and program the cutting route on the fish neck, while the cutting route of the fish belly is determined by selecting the area of the excretory hole through the ROI region of interest. Finally, the designed mechanical structure is used to peel the whole skin of the snakehead. The experimental results show that the maximum fluctuation rate of the snakehead area calculated by the proposed three-dimensional reconstruction algorithm is less than 4.0%, and the accuracy reaches 87.3%. The average precision (AP) for the determination method of the fish neck cutting position on the snakehead is 90.89%, which proves the effectiveness and feasibility of this method. The present results provide useful technical support for automating fish whole-skin peeling and shedding light on the accurate determination of the surface area and the extrication of the morphological feature parameters of other organisms. Keywords: Neural network, Point cloud, Snakehead, Skin peeling, Three-dimensional reconstruction.

Thermal Analysis of Melting Occurring Inside a Finned Rectangular Enclosure Equipped with Discrete Pulsed Protruding Heat Sources

This paper numerically investigates the effect of the location of a horizontal fin on the melting of a phase change material (PCM) inside a rectangular enclosure heated by multiple discrete pulsed protruding heat sources. The fin and the phase change material filling the enclosure store the thermal energy extracted from the heat sources, in sensible and latent forms. The heat sources are assumed to simulate electronic components undergoing a superheating technical issue. By extracting heat from the electronics, the PCM plays the role of a heat sink. To analyze the thermal behavior and predict the cooling performance of the proposed cooling system, we derive a nonlinear mathematical model based on mass, momentum and energy conservation laws. Several numerical investigations are conducted to quantify the influence of the fin position on the thermal behavior and the cooling performance of the heat sink. Predictions include the transient maximum temperature occurring inside the heat sources and the liquid volume. A comparison between our numerical results and experimental data selected from the literature shows a good agreement. The main conclusion is that the presence of the fin leads to a slight increase in the melting time.

Effect of Fin Number and Position on Non-linear Characteristics of Natural Convection Heat Transfer in Internally Finned Horizontal Annulus

Detailed numerical calculations are performed for investigating the effect of fin number and position on unsteady natural convection heat transfer in internally finned horizontal annulus. The SIMPLER algorithm with Quick scheme is applied for solving the Navier Stokes equations of flow and heat transfer. The results show that the heat transfer rate in annulus with fins increases with the increasing numbers of fin and Rayleigh numbers. For Ra = 2 × 105, the effect of numbers of fins and fins position at the bottom part on the unsteady solutions can be neglected, because the self-oscillation phenomenon is mainly affected by natural convection at the upper part of annulus. Although the fin positions cannot increase heat transfer rate significantly in the case of four fins, the self-oscillated solutions can be suppressed by altering fins position.

Numerical study of a building integrated photovoltaic-finned phase change material panel under Tunisian climatic conditions.

Building-integrated photovoltaic systems' electrical efficiency decreases when their operating temperature increases. To overcome this drawback, the use of the PCM as a passive method to improve the thermal and electrical performances of the system is highly recommended. Yet pure phase change materials are known for low thermal conductivity. Inserting fins in the PCM enhances its thermal conductivity leading therefore to an improvement in the heat transfer rate. The present investigation carried out the optimization of the BIPV-FPCM system to reduce BIPV system temperature at real Tunisian climatic conditions. The best inclination angle of BIPV-FPCM is carried out. Moreover, the suitable depth of the FPCM box is evaluated. BIPV, BIPV-PCM, and BIPV-FPCM systems are compared. In the present thermodynamic work, the fusion and solidification processes of the FPCM were analyzed. In addition, space between successive fin effect, fin length, and position effect on BIPV electrical and thermal performances had been investigated. Interesting findings showed that the decrease in the tilt angle of the module enhances the heat transfer rate in the FPCM due to the improvement of the convection heat transfer rate in the melted PCM. Thirty degrees is found the most optimal tilt angle with respect to the horizontal where the received solar radiation increases with the decrease of the tilt angle from 90° to 30°. Results prove that the best fin number to enhance performances of the BIPV-PCM system is 3 where 6cm is found to be the best PCM box depth. Eventually, fin positioning is so important to improve the rate of heat transfer rate by promoting natural convection in the PCM. Results reveal that "full fins" and "front fins" scenarios are the best cases for improving the melting rate and performances of the BIPV-FPCM system.

Middle fins hold the key to fish movement

Next time you find yourself in an aquarium, pay attention to the fish's fins. The middle fins in particular show a mesmerising variety in number, shape and position on the fish's body. But what is the purpose of such a variation? David Matthews and George Lauder of Harvard University aimed to address this question by investigating the interactions between the middle and tail fins and their effect on a fish's movement. Biologists and engineers have previously attempted to navigate these tough waters, so what new angle did the pair introduce?Matthews and Lauder used a simplified fish-like robotic model: a thin plastic foil mimicking the proportions and form of a fish (a fish body, a tail fin and two middle fins symmetrically arranged on either side of the body) connected to a robotic flapping device introducing a sideways movement with the help of motors. This model was a step closer to real fish than previous mechanical models, in which just the forces produced by the fins were investigated. On top of that, they decided not to control every aspect of the fish's movement, which would overcomplicate the robot-fish, but measure them instead. They attached a force-sensing rod to the front of the foil, where the fish's head would be, and changed the number of flapping cycles the body experienced per second to propel itself forward. Using this setup, they could quantify the foil's energy and movement such as its speed and the maximum amount each model fin flaps respectively, all together determining the swimming performance of this model fish.With the robot-fish at hand, the authors first asked how the position of the fish's middle fins and the timing of their flapping, i.e. whether they flap in unison with the tail fin or not, affect its movement. They performed experiments with four types of robot-fish: flexible or stiff, and with middle fins near or far from the tail. They then showed that the number of flapping cycles per second has the largest effect on the fish's swimming performance, which is consistent with live fish that flap their fins more often when they want to accelerate. The modelling also revealed that the stiffness of the foil didn't significantly change its movement while the location of the middle fins did. The far-fin foil was always the fastest, and when the middle fins were moving out of sync with the tail fin, it was also the most efficient. The team also observed that the out of sync flapping of the fins was beneficial for force production, which varied less over time, costing less energy for the fish.To understand these results further, Matthews and Lauder used a visualisation technique to look at the water flow around the fins. They showed that having middle fins is helpful as their flapping results in a strong side-to-side flow at the front of the tail fin – irrespective of the fin position in flexible foils. In contrast, they found that for the stiffer foils, the one with the far middle fins resulted in a direct interaction of its flow with the front of the tail fin, amplifying the production of the propelling force. Thus, they were able to conclude that the patterns of flow amplification are consistent with their statistical model and can help explain why fin position and flapping timing affect force production. As a result, while we previously knew that flow from one fish's body can impact swimming performance in following individuals, we now also know that following fish can independently improve their performance using their secret weapon – middle fins.

Numerical heat transfer analysis of a thermal energy storage system enclosure with horizontal fin for sustainable energy storage

Two-dimensional numerical analysis is carried out in a square cavity with extended surface with nanofluid foe heat transfer enhancement under natural convection in a laminar flow regime. Pure water, ethylene glycol (EG), Water/EG mixture (20%, 40%, 60% and 80%) with aluminium oxide concentration of 3% inside a square cavity for a given fin length, position and different Rayleigh number (103, 104, 105, 106) is considered. Numerical analysis is carried out in Ansys Fluent using homogenous heat transfer model. It is observed that as the conductivity ratio and Rayleigh number increased resulting in higher surface temperature leading to heat transfer enhancement. Moreover, a fin position of 0.5 m height and 0.75 m length has been found to be the most optimal position for better heat transfer enhancement. Furthermore, it has been observed that the higher the conductivity ratio of the fin, the better is the heat enhancement.

Numerical modeling of energy storage unit during freezing of paraffin utilizing Al2O3 nanoparticles and Y-shape fin

Freezing process inside an annulus zone was reported numerically in this article. The domain is filled with paraffin (Tm=82 °C) and for improving thermal features, nanoparticles were added. Fins with various sizes and positions were applied and two levels for fraction of nanomaterial were utilized. Exergy drop is main outputs of current research and contours in three time stages were reported. Unsteady phenomena were reported with considering structure grid. Average values of significant parameters were extracted as function of time. Non-zero values of velocity show the impact of buoyancy force. For verification, experimental outputs of published paper have been utilized. Exergy drop (Xd) declines with rise of time because of reduction of temperature. The value of Xd decrease about 91.14% when time increases from 1 to 15 min for case 8. The geatest case win lowest needed time is case with thinner fins over the outer wall and it needs 17.86 min to reach complete solidification. Inclusion of alumina in to paraffin makes freezing time to decrease about 11.7%. Changing the position of fins from inner to outer causes the freezing rate to increase about 14.45%.

Numerical investigation of circular porous fins effect on natural heat transfer enhancement in an annulus cavity

An asymmetric numerical study has been performed to investigate the effect of utilizing circular porous fins on heat convection inside of an annulus enclosure. The walls are considered to be at a constant temperature. The porous fins are installed on the outer wall, and other walls are insulated. Governing equations discretized using the FVM based on the second-order upwind scheme. The effect of different parameters on heat transfer enhancement inside the annulus, such as annulus inclination angle, annulus aspect ratio, Darcy number, Rayleigh number, thermal conductivity, the position of fins, number, and length of fins, has been investigated. Results declared that increasing Darcy number from a certain value would enhance the average Nusselt number dramatically at both aspect ratios, even though annulus with an aspect ratio of 3:1 has a higher value of average Nusselt number compared to the aspect ratio of 2:1. It has been illustrated utilizing low relative solid to fluid phase thermal conductivity nullify the effect of the increasing number of porous fins on heat transfer enhancement but, by increasing relative thermal conductivity to Ke=100, installing four porous fins on the inner cylinder increases the average Nusselt number by 7 percent compared to using only one fin.

Phase change material heat transfer enhancement in latent heat thermal energy storage unit with single fin: Comprehensive effect of position and length

In this study, the comprehensive effect of position and length of the fin in a latent heat thermal energy storage (LHTES) unit with a single fin on the melting and solidification of the phase-change materials (PCMs) was explored by transient numerical simulations. By analyzing the liquid-solid interfaces, temperature distributions, velocity vector and phase change rate, the melting and solidification characteristics of PCM and heat transfer enhancement mechanism of the fin with various length ratios and height ratios were understood in detail. The results illustrated that the total melting time was significantly reduced by increasing the fin length and lowing the fin position simultaneously. On the other hand, lowering the fin position would result in non-uniform temperature distribution during the solidification process. More importantly, considering the contradiction in fin position between melting and solidification, an optimal position of the fin corresponding to different fin lengths was suggested. Besides, a disparity between heat storage/release and phase transition was quantitatively discussed.

The effect of hull fineness ratio and fin parameters on the optimization of tethered aerostat

PurposeThis paper aims to optimize the mass of a tethered aerostat to achieve optimum hull volume, and fins to generate aerodynamic lift to reduce the blow-by.Design/methodology/approachThe design code of aerostat involving structure, aerostatics, aerodynamics and stability has been developed using MATLAB®. The design code is used to obtain the baseline configuration for a tactical aerostat mission by using the statistical values of the hull fineness ratio and the fin parameters of in-service aerostats. The effect of the design variables that include the hull fineness ratio, fin area and fin position on the aerostat mass and blow-by is determined through sensitivity analysis. The aerostat is optimized with an objective function of minimization of mass for the bounded values of design variables and taking blow-by limit as a constraint.FindingsThis study reveals that the simultaneous optimization of the aerostat hull fineness ratio, fin area and fin position results in an improvement in the design. The aerostat design with optimum values of these parameters helps in a reduction in its size and mass without compromising the blow-by limits.Research limitations/implicationsThis study has been conducted by keeping the hull shape constant by selecting standard National Physics Laboratory envelope shape. The aerodynamic model used in the design code is based on empirical relationships that can be improved in future studies that can use high fidelity aerodynamic models using CFD based surrogate models.Originality/valueThe previous studies on optimization of aerostats are limited to hull envelope shape only, whereas this paper presents the optimization of the hull and fin together. The optimized configuration obtained has a reduced mass and can operate within the specified blow-by limits.

Comparing the performance of supervised classification methods on a multispecies fishery of post-larval galaxiids

ABSTRACT Galaxiid post-larvae constitute five of the six species in New Zealand’s iconic whitebait fishery. Distinguishing the five species needs to occur at a younger age than is convenient for easy identification. Traditional identification uses subjective characteristics such as colouration of fresh specimens and fin position, but supervised classification methods could be more accurate and less labour-intensive. We compared the accuracy of six methods (multinomial logistic regression, linear discriminant analysis, quadratic discriminant analysis, naive Bayes, decision tree, and random forest) using total length, wet weight, body depth, and date, latitude and longitude of capture as predictive variables. Four of the galaxiid species were represented in 17,546 observations, but the other species was too rare to analyse. The best method, determined using 10-fold cross-validation classification accuracy (95.2% overall), was random forest across all species. The most difficult species to classify correctly (giant kōkopu) was the rarest species included in data with 66.1% accuracy at best. In addition to examining overall accuracy, we show how use of a cost function can improve classification performance with respect to rare species. This research could improve the efficiency of monitoring the composition of the whitebait fishery, and thus management of this occasionally overfished group of fish.

Instability and merging of a helical vortex pair in the wake of a rotor

We present results from an experimental investigation of two closely spaced helical vortices. The two co-rotating vortices are generated in a water channel by a one-bladed rotor, whose tip geometry is modified by the addition of a perpendicular fin on the pressure side. The fin parameters are tuned so that the two vortices have approximately equal circulation. Dye visualisations and flow field measurements from Particle Image Velocimetry show that the vortices merge into a single tip vortex within less than one rotor rotation. This fast merging is caused by a rapid increase of the core radii of the initial vortices, which indicates the presence of an instability phenomenon. Analysis of the vortex velocity profiles identifies it as a centrifugal instability, linked to the presence of opposite-signed vorticity in the blade tip region. We further explore the origin of this vorticity by modifying the streamwise fin position. Measurements suggest that the interaction between the secondary fin vortex and the blade surface is partly responsible for the generation of the unstable velocity profile. The vortex resulting from the merging has a significantly larger core size than the one developing without a fin, indicating that this configuration could be beneficial in the context of Blade-Vortex Interaction noise for helicopters, or for the reduction of fatigue loads on wind turbine rotors caused by the interaction with concentrated tip vortices in the wake of upstream turbines.

Two new annual fishes (Cyprinodontiformes: Rivulidae) unexpectedly discovered in the highlands of southern Brazil.

Two new species of Austrolebias are described based on specimens collected from temporary pools located in natural grassland landscape within the Araucaria Forest domain at exceptionally high altitudes (~1000 meters a.s.l.). Austrolebias botocudo sp. n. and Austrolebias nubium sp. n. occur, respectively, in drainages of upper rio Apuaê-Inhandava (upper rio Uruguay basin) and upper rio Taquari-Antas (upper rio Jacuí, Laguna dos Patos basin), in the Meridional Plateau of southern Brazil. Despite an intensive survey conducted in the area, only two populations of each species were recorded. Both new species occurs at altitudes that are among the higher recorded for species of the genus, and both are assigned to the subgenus Acrolebias. The new species described herein are easily distinguished for its congeners by the colour pattern of males, by presence of melanophores irregularly distributed in different parts of the body, contact organs cover the body and anal fins, position of fins related with vertebrae, by preopercular and mandibular series of neuromasts united, by a series of morphometric features and by larger maximum standard length. Austrolebias botocudo and A. nubium are distinguished from each other by colour pattern of males, length of contact organs in the flank and number of contact organs in scales of lateral line, dorsal profile of head, number of neuromasts in the preopercular + mandibular series, body depth in females, and by basihyal cartilage length. Additionally, we discuss the conservation status of the new species, and provided an identification key for the species of the subgenus Acrolebias.

Banded Killifish (<i>Fundulus diaphanus</i>) and Mummichog (<i>Fundulus heteroclitus</i>) distributions in insular Newfoundland waters: implications for a Species at Risk

Newfoundland’s Banded Killifish (Fundulus diaphanus) population is listed as a species of Special Concern under Canada’s Species at Risk Act and Vulnerable under Newfoundland and Labrador’s Endangered Species Act. Mummichog (Fundulus heteroclitus) is a similar looking fish species and is currently under review by Newfoundland and Labrador’s Species Status Advisory Committee. Both species have limited known distributions in Newfoundland waters that overlap. They may occur sympatrically in estuaries and occasionally hybridize; thus, field identifications can be challenging. We found that dorsal fin position and caudal fin depth were the most useful morphological characters for distinguishing Banded Killifish and Mummichog in the field. We used local ecological knowledge, literature review, museum records, and field surveys to update the known distribution ranges and found both species in more locations than previously documented in Newfoundland. Thus, we extend their known ranges. Our results will be critical in future status assessments of these species in Newfoundland.

Optimization of phase change heat exchanger based on RSM

A tube phase change heat storage unit with fins was designed and optimized by multi-objective optimization method based on response surface method. Taking the temperature of phase change material (PCM) at a certain time as the optimization index, the effect of the relative position between the outer wall of the inner tube and the inner wall of the intermediate tube on the heat exchanger performance is mainly considered. The angle of the inner tube outer wall fin, the angle between the two fins on the outer wall of the inner tube and the angle of the fin on the inner wall of the outer tube are the three influencing factors. The optimum parameters are as follows: angle A = 7.09 °, angle B = 40.06 ° and angle C = 45 ° and the best result is obtained when the relative position of inner and outer fins is about 40 °and the optimization result is increased by 6.4%. The results show that the fitting accuracy of the regression model is as high as 97%, which shows that the results are reliable.

TCAD-Based Flexible Fin Pitch Design for 3-nm Node 6T-SRAM Using Practical Source/Drain Patterning Scheme

In this article, we analyzed the stability, power, performance, and area of 6T-SRAMs using a promising scaling booster, i.e., source/drain patterning (SDP) scheme for the 3-nm technology node based on 3-D TCAD simulation. SDP scheme allows to decrease the spacing between transistors by downsizing the source/drain epitaxy. Proposed 5-nm and 3-nm SDP-SRAM (SDP-SRAM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> and SDP-SRAM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> ) are compared with conventional 5-nm node SRAM (Conv-SRAM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> ), quantitatively. Unlike a Conv-SRAM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> , SDP-SRAMs have more design margins according to the two fin position parameters: fin location adjustment (FLA) and separation pitch adjustment (SPA). The optimized layout has the maximum FLA by significantly decreasing the back-end-of-line (BEOL) bitline and internal node capacitance. Read and write static noise margins were comparable (<; 10 mV) between the SDP-SRAM and Conv-SRAM. The SDP-SRAM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> improved the read access time 18% compared to the Conv-SRAM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> in low-power (LP) applications, but the SDP-SRAM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> degraded it by 11% in high-performance (HP) applications because of the narrow M2 pitch. Both the SDP-SRAM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> and SDP-SRAM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> improved write access time about 10% compared to a Conv-SRAM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> in LP applications. The cell area of the SDP-SRAM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> decreased about 0.64 times compared to a Conv-SRAM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> without severe degradation of performance. The SDP scheme provides flexible layout designs enabling a high-density SRAM, promising for 3-nm node logic applications.

A Practical Study of the Positions of the Offsite-Strip Fins [OSF] Heat Transfer Performance to the Turbulent Water Flow

A Practical Study of the Positions of the Offsite-Strip Fins [OSF] Heat Transfer Performance to the Turbulent Water Flow

Influence of fin orientation on the natural convection of aqueous-based nano-encapsulated PCMs in a heat exchanger equipped with wing-like fins

The heat transfer enhancement in pin-fin heat exchangers is achieved by fluid mixing, disruption of the thermal-viscous boundary and the extension of the effective surface area for maximum heat exchange. The orientation and configuration of the fins are among the prime factors influencing the performance of these heat exchangers. Therefore, the present study investigates the combined influences of fin angle (0≤ζ≤270), arrangement and position of the wing-like fins on the natural convection of aqueous-based nano-encapsulated phase change material (PCM) in a fin heat exchanger. The analysis is performed for Rayleigh and Stefan numbers of 1e3-1e5 and 0.2 respectively by considering the PCM concentration of 0.05. The flow is assumed to be laminar, incompressible and Newtonian. The results demonstrate that the vertical alignment of the fins contributes to the augmentation of the thermal performance compared to the horizontally arranged fins. At the larger Rayleigh number, the mode of heat transfer is predominantly convective and thermal performance slightly deteriorates due to the blockage caused by adjacent fins. For low Rayleigh number, the conduction is the primary mode of heat transfer between the source and sink fins. This phenomenon is crucial to determine the heat exchanger thermal performance.

Melting performance enhancement of thermal storage system by utilizing shape and position of double fin

In present study, a 2D rectangular enclosure was considered as a latent thermal energy storage (LTES) system. Lauric acid was used as PCM material. The aim of this study was to use fins to enhance melting process of PCM. Position and shape of double fins were considered as investigating parameters. At first stage three different positions were considered for fins of rectangular shape. Results indicated that amongst aforementioned cases, best results were achieved when double fins were located at lower half of enclosure. Results revealed that up to 1800s could be saved during whole melting process. At second step, two trapezoidal form and one triangular shaped double fins were used to evaluate the effect of fin shape. In these cases, fins were placed at optimum position concluded from previous stage. Results presented that up to Fo = 0.15, best values of Nusselt numbers were related to triangular shaped fins. After Fo = 0.15, the case with triangular fin has least Nu number. The best melting performance was related to triangular fins at which 1000s less melting time was observed. Enhancement ratio results presented better performance for triangular fins after second of 2500s.