Fin Shape Research Articles

A review on the modification of circular fin and tube heat exchangers through new innovative fin shapes

A review on the modification of circular fin and tube heat exchangers through new innovative fin shapes

Performance analysis and optimization of heat pipe-based radiator for space nuclear power system

The weight of radiator affects the launch weight of spacecraft and the feasibility of engineering development. Heat pipe radiator is widely used in space heat emission because of its strong resistance to single point failure and excellent heat transfer performance. This paper analyzed the sensitivity of fin width, inlet temperature, condensing section length and coolant mass flow of a direct contact heat pipe radiator are analyzed on four types of heat pipe radiators. The optimal design parameters of two inlet – two outlet radiator are obtained by double objective optimization, and the optimal design parameters are Lf = 0.0893 m, Tf11 = 697.8371 K, lhpc = 0.7736 m, qm = 8.9184 kg/s. ANSYS fluent 19.0, a CFD code is used to simulate the flow and the heat transfer characteristics of radiator with the best design parameters. Which indicates the intersection of coolant pipe and annular pipe of the radiator should be thickened, and the fin shape should be optimized along the direction of the fin isotherm.

The effect of novel fin shapes and non-uniform magnetic field on the nanoparticles embedded PCM melting in a tube

In this paper, the heat transfer and melting process of the phase change material (PCM) in a cylindrical space with different internal fins with the presence of nanoparticles and a non-uniform magnetic field (NUMF) are inspected numerically. Seven new fin models have been designed for this purpose. The enthalpy - porosity method based on FVM is used to simulate the melting process of PCM in a 3D state. Lauric acid as PCM and Ferric nanoparticles were utilized. The electric field is created using the electric potential. Their outcomes demonstrate that the process of PCM melting in the finned chamber is a strong function of geometric shape. Among the designed fins, Type 6 geometry has the most improvement in the melting process. The new fins are designed to improve the melting process by about 2–40%. The nanoparticles volume fraction (NPVF) is 2.55%. The consequences display that with increasing NPVF from 2.5 to 5%, the melting fraction has increased by about 1.5–2.5%. Applying NUMF on the outer walls of the chamber has amended. This effect is proportional to the intensity of the magnetic field. With increasing the intensity of the magnetic field by about 16–57%, an improvement in the melting process has been observed.

Numerical study on heat transfer augmentation techniques in concrete based thermal storage module for solar-thermal applications

• Thermal performance of sensible heat storage prototype is studied. • Heat transfer augmentation is investigated by varying the fin configuration. • The maximum reduction in charging time is 36.9%/. • Proposed optimized model increases the discharging rate by 75.6%. • Trapezoidal fin configuration is the best option with 50–75% cost reduction. In this study, the development and performance analysis of a concrete based thermal energy storage module with a capacity of 170 MJ operating in the temperature range of 523 K to 623 K is presented. To enhance the heat transfer rate in concrete based sensible heat thermal energy storage (SHTES) systems, the well-proven technique of fin incorporation is implemented. Longitudinal fins are attached on the outer side of the heat transfer fluid supply tube without compromising the thermal storage/discharge capacity of the storage module. Numerical simulations have been performed using COMSOL Multiphysics to study the thermal performance of the module by varying the design parameters such as the number of fins, fin dimension, and fin shape. The thermal performances of the models with fins, in terms of charging/discharging time and heat storage/retrieval rate, are compared with the model without fins for the same boundary condition. From the numerical study, it is observed that the maximum reduction in charging/discharging times of the storage module is 36.9%/48.1% and 36.9%/45.6% for rectangular and trapezoidal fin shaped models, respectively, in comparison with the model without fins. Whereas, the corresponding enhancement in heat storage/heat retrieval rate is 58.5%/92.7% and 58.5%/83.7% for rectangular and trapezoidal fin shaped models, respectively, in comparison with the model without fins. By adopting a trapezoidal shaped profile model, the fin material usage can be reduced by 50–75% without compromising on thermal performance. This numerical analysis would facilitate the design and development of efficient storage modules for solar thermal applications.

Computational fluid dynamic study on the adsorption-based desalination and cooling system

Adsorption desalination (AD) is a potentially competitive alternative for potable water production. Unlike traditional rectangular fins for finned-tube adsorbent bed in the AD system, in this study, bullet- and umbrella-shaped fins are employed in the adsorbent bed to improve the heat and mass transfer characteristics in the adsorption/desorption processes, thus augmenting the system performance. Based on a complete transient mathematical model incorporating a three-dimensional computational fluid dynamic model for adsorber and lumped models for evaporator and condenser, impacts of fin configurations regarding base diameter, tip diameter, and shape factor on system performances considering the adsorbent and the whole bed are comprehensively analyzed. Results reveal that a larger base and tip diameter with a lower shape factor contribute to specific bed productions. The underlining relationship between fin configurations and overall performance (total daily water production, total cooling power, and coefficient of performance) is further explored via machine learning. And the optimal fin shape is identified by the genetic algorithm. The optimal base diameter, tip diameter, and shape factor are 0.262, 0.517, and 4.20, respectively, which render a total water production of 5.20 m3/day with a total cooling power of 0.149 kW and coefficient of performance of 0.855.

An analysis of latent heat thermal energy storage in a hexagonal triplex-tube unit with curve shape fin and CNTs

In this article, latent heat thermal energy storage (LHTES) is analyzed for nano phase change material enclosed in a hexagonal triplex-tube with solidification acceleration. Optimized curve shape fins are adjusted inside the tube. The shape of the structure is a hexagonal annular. Therefore, both inner hexagonal walls are cold. Corresponding to six vertices of the hexagonal shaped tube, parallel but symmetrically curved fins are adjusted to every corner. Nanoparticles Enhanced Phase Change Material (NEPCM) is filled inside the annulus, and the mathematical model is constructed based upon the system of nonlinear partial differential equations through the heat equation. Single wall carbon nanotubes (SWCNT) and Copper driven through liquid phase and solid phase within the entire duct. Galerkin Finite Element Method (GFEM) is employed to model the solidification procedure. The smaller symmetric fins achieving an angle of 10o≤β1≤45o and the larger symmetric fins making an angle of 10o≤β2≤45o with the vertical rod. However, the length of rod is 10mm≤L≤20mm. It is found that the optimized curve shape fin penetrate the intensity of thermal storage into the Phase change materials (PCM) and the shape of the fin prevents the phase trade manner from final unsolidified PCM near the outer shell, in which the phase alternate front passes the top of the fins. It is further analyzed that at the mean position of the triplex tube, the solidification process is minimum due to the high thermal performance of nanoparticle volume fraction and time perfection.

A comparative study of the effect of fin shape on mixed convection heat transfer in a lid-driven square cavity

A comparative study of the effect of fin shape on mixed convection heat transfer in a lid-driven square cavity

Performance enhancement of nano PCM solidification in a hexagonal storage unit with innovative fin shapes dealing with time-dependent boundary conditions

The effect of innovative branching fins and nanoparticles as direct and indirect heat transfer augmentation methods on the solidification of a PCM within a hexagonal storage unit was numerically investigated in this research. A time-dependent boundary condition of the third kind is applied to the cold walls which let us investigate the influences of the amplitude and periodicity of the ambient temperature variation on the phase-change process during the time-dependent boundary conditions. Also, the exergy efficiency of the system is analyzed by conducting an exergy analysis. In the indirect method, nano-enhanced PCM is made by dispersing CuO nanoparticles to it. Furthermore, the finite element method was employed to simulate the procedure. The results of the current parametric study depicted that the addition of innovative fins, with a 30% decrement in the full solidification time, was a more effective method than making nano-enhanced phase change material, which at best (ϕ=0.04) had a 14.5% reduction in the full solidification time. Moreover, a reduction of about 3% in release exergy efficiency is obtained by raising the HTF from 240 K to 260 K. Additionally, it was found that augmenting the amplitude and duration of the cold wall would speed up the solidification process.

Effects of Pin–Fin Shape on Heat Transfer, Flow Behavior and Pressure Loss in a Swirl Tube

Effects of Pin–Fin Shape on Heat Transfer, Flow Behavior and Pressure Loss in a Swirl Tube

OLBIAN DOLPHIN PROTO-COINS: STURGEONS, SHARKS OR DOLPHINS?

Introduction. Olbian dolphin proto-coins is one of the most common and simultaneously unique serial metalworks of the early antiquity period. The question of biological prototypes, which, according to different researchers, could be either fish or dolphins, remains debatable. The absence of species affiliation analysis of the dolphin-like depictions does not allow to give a clear answer to this question. Objective. Determination of zoological prototypes of dolphin protocoins by comparative anatomical analysis. Results. Among the 36 anatomical feautures that can be identified on the coins, 25 are inherent in fish, in particular 21 are specific for sturgeons and 19 for sharks, and only 9 clearly belong to dolphins. The presence and distinctiveness of the traits creates a variety of types of proto-coins, and the combination of feautures from fish and dolphins causes the depictions to look whimsical. Archaic and primitive proto-currency herewith have a fish prototype. Diagnostic features of fish on the coins: big eyes on the sides of the head, operculum, lateral line, two dorsal fins, pressed to the body pectoral fin, truncated caudal fin. Some feautures (hypertrophied elongated snout, dorsal fin being closer to caudal fin, scutes on the body, heterocercal caudal fin) correspond to sturgeons, others (gill slits, location and shape of dorsal and pectoral fins, heterocercal caudal fin) to sharks. Bulging forehead should be considered as direct proof of a dolphin prototype for the coins, while other traits are either overlaped by fish feautures, or their interpretation is subjective. Conclusions. 1. The multiplicity of types and forms of dolphin-like coins, which combines traits of dolphins and different species of fish, indicates an absence of a single prototype. 2. The majority of the traits on anepigraphic coins is native to fish. The prototypes are sturgeons and possibly sharks. 3. By combinations of features it is possible to distinguish sturgeon- and shark-type proto-coins. 4. Some creations have bizarre depictions. 5. Heavyweight dolphins - whimsical representations with features of sharks as well as possibly other fish and dolphins. 6. Epigraphical dolphins with an «АРІХО» inscription bear signs of fish, whilst smaller ones with «ΘΥ» are rather bizarre depictions. 7. Predominance of fish traits on archaic and primitive items proves the primacy of the image of the fish.

A numerical investigation of a heat transfer augmentation finned pear-shaped thermal energy storage system with nano-enhanced phase change materials

Thermal energy storage using latent heat and phase change materials is a frequently utilized technique in energy storage systems. It is critical to search for various thermal enhancement approaches in order to further improve the poor thermal conductivity of phase change materials in these systems. Two primary thermal enhancement approaches (fins and the use of a nano-enhanced phase change material (NePCM)) are discussed in this study for a pear-shaped TES system. The TES unit is filled with n-octadecane PCM incorporated with Al2O3 nanoparticles and equipped with fins. Different concentrations of Al2O3 (such as 0, 3, and 6 vol%), fin shapes (2-fin, Y-shaped fin, and T-shaped fin), and fin materials (aluminum, copper, and steel) are tuned to obtain an optimal heat transfer and acceleration of PCM melting process. The results indicated that when a dose of 6 % of Al2O3 nanoparticles and copper fins are utilized, the melting time is lowered by 14 % and 32 %, respectively, compared to pure PCM with steel 302 fins. Additionally, the best choice for accelerating energy storage in a pear-shaped unit is to equip it with a Y-shaped copper fin. The use of steel 302 fins causes a dominance of the heat transfer irreversibility compared to the fluid friction irreversibility. Nonetheless, two rectangular aluminum fins may be considered a more cost-effective option due to the moderate difference in performance between the cases, the fact that aluminum is cheaper and lighter than copper, and the simplicity and convenience of producing the two rectangular fins.

Deep reinforcement learning for heat exchanger shape optimization

We present a parametric approach for heat exchanger shape optimization utilizing Deep Reinforcement Learning (Deep RL) and Boundary Representation (BREP). In this study, we show that continuous geometric representation of the fluid and solid domain facilitates the implementation of boundary conditions and design space exploration in contrast to traditional Topology Optimization such as density-based methods. The proposed framework consists of a Deep Neural Network (DNN), a Computational Fluid Dynamics (CFD) solver with an automatic body-fitted mesh generation to solve a single fin shape optimization. The learning is performed using Proximal Policy Optimization (PPO) in combination with a CFD environment in FEniCS. The RL agent successfully explores the design space and maximizes heat transfer and minimizes pressure drop for geometric design with as low as 12 degrees of freedom represented by composite Bézier curves. Higher degree of freedom results in higher reward of the agent. This method alleviates the curse of dimensionality compared to voxel and pixel-based optimization of coupled thermal fluid-structure. Results show the manufacturability and efficiency of the output of our framework. Over 30 percent improvement in overall heat transfer while lowering the pressure drop by more than 60 percent compared to the rectangle reference geometry is achieved.

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.

Innovative ladder-shaped fin design on a latent heat storage device for waste heat recovery

Latent heat energy storage system provides an alternative solution to solving the imbalance problem of energy supply and demand. To improve the phase change efficiency, a novel ladder-shaped fin is proposed to accelerate melting process. Under the same mass of fin materials, two groups of fin shapes (totally eight cases) are innovatively designed. Upon being verified by experiments in literature, numerical models account for comprehensive descriptions on melting front propagation with emphasizing temperature development and free convection in the liquid phase. Results demonstrate that the ladder-shaped fins can better optimize the melting channel of phase change material than the straight fin. Compared to the original straight fin case, a maximal 52.2% of the total melting time can be saved. The angle change of fins has a significant effect on reducing the melting time of the whole PCM. In Group I where fins are arranged vertically and horizontally, the total melting time is much shorter than that of each corresponding case in Group II (45° from the vertical axis). For the original straight fin in Group II, a 36.8% reduction in total melting time is obtained if turning fins by 45°clockwise. To be conclusive, it is more beneficial to add fins to mobile heat accumulators than to have no fins, saving more energy charging time.

Fish-inspired segment models for undulatory steady swimming

Many aquatic animals swim by undulatory body movements and understanding the diversity of these movements could unlock the potential for designing better underwater robots. Here, we analyzed the steady swimming kinematics of a diverse group of fish species to investigate whether their undulatory movements can be represented using a series of interconnected multi-segment models, and if so, to identify the key factors driving the segment configuration of the models. Our results show that the steady swimming kinematics of fishes can be described successfully using parsimonious models, 83% of which had fewer than five segments. In these models, the anterior segments were significantly longer than the posterior segments, and there was a direct link between segment configuration and swimming kinematics, body shape, and Reynolds number. The models representing eel-like fishes with elongated bodies and fishes swimming at high Reynolds numbers had more segments and less segment length variability along the body than the models representing other fishes. These fishes recruited their anterior bodies to a greater extent, initiating the undulatory wave more anteriorly. Two shape parameters, related to axial and overall body thickness, predicted segment configuration with moderate to high success rate. We found that head morphology was a good predictor of its segment length. While there was a large variation in head segments, the length of tail segments was similar across all models. Given that fishes exhibited variable caudal fin shapes, the consistency of tail segments could be a result of an evolutionary constraint tuned for high propulsive efficiency. The bio-inspired multi-segment models presented in this study highlight the key bending points along the body and can be used to decide on the placement of actuators in fish-inspired robots, to model hydrodynamic forces in theoretical and computational studies, or for predicting muscle activation patterns during swimming.

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.

Early impacts of the largest Amazonian hydropower project on fish communities

Hydropower is a threat to freshwater fishes. Despite a recent boom in dam construction, few studies have assessed their impact on mega-diverse tropical rivers. Using a before-after study design, we investigated the early impacts of the Belo Monte hydroelectric complex, the third-largest hydropower project in the world, on fishes of the Xingu River, a major clear-water tributary of the lower Amazon. We explored impacts across different river sectors (upstream, reservoir, reduced flow sector, and downstream) and spatial scales (individual sectors vs. all sectors combined) using joint species distribution models and different facets of diversity (taxonomic, functional, and phylogenetic). After 5 years of the Belo Monte operation, species richness declined ~12% in lentic and ~16% in lotic environments. Changes in abundance were of less magnitude (<4%). Effects were particularly negative for species of the families Serrasalmidae (mainly pacus), Anostomidae (headstanders), Auchenipteridae, and Pimelodidae (catfishes), whereas no taxonomic group consistently increased in richness or abundance. The reservoir and downstream sectors were the most impacted, with declines of ~24–29% in fish species richness, overall reductions in fish body size and trophic level, and a change in average body shape. Richness and abundance also declined in the reduced river flow, and changes in size, shape, and position of fins were observed. Relatively minor changes were found in the upstream sector. Variation in functional and phylogenetic diversity following river impoundment was subtle; however, across sectors, we found a reduction in functional divergence, indicating a decline in the abundance of species located near the extremities of community functional space. This may be the first sign of an environmental filtering process reducing functional diversity in the region. Greater changes in flow and habitats are expected as hydropower operations ramp up, and continued monitoring is warranted to understand the full scope and magnitude of ecological impacts.

New design of U-turn type minichannel cold plate with hybrid fins for high temperature uniformity

The thermo-hydraulic performance of cold plates is strongly influenced by the channel profiles and fin shapes. First, a shape optimization of U-turn type liquid cold plates is performed employing a discrete adjoint method in this work. The better uniformity of flow rate in minichannel cold plates is obtained by applying the optimized design of structures for entrance and baffle regions. Compared with the baseline design, the standard deviation of the flow rate for the optimal design decreases by 82.76%. The temperature uniformity of liquid cold plates can be further improved by using an asymmetric design of the double flow paths. The standard deviation of the temperature of the heating wall surface in the optimal design decreased by 20.75% compared with that of the conventional design. Furthermore, the roles of fin shape (rectangular, discontinuous, and wavy), fin thickness, and amplitude, wavelength and phase difference of sinusoidal wavy fin on the thermal performance of liquid cold plates having the asymmetric design with the curved baffle proposed are evaluated in detail. The results reveal that the larger amplitude, the smaller wavelength, the greater phase difference of wavy units may contribute to the greater heat transfer performance and the better temperature uniformity of cold plates. The heat transfer augmentation is attributed to the formation of vortices in the channel caused by the wavy fins and the increase of heat transfer surface area caused by the corrugated walls. As a result, two novel designs of minichannel cold plate were presented. New design of minichannel cold plate with wavy fins exhibits better heat transfer performance, while the other design with hybrid fins has more advantages to enhance temperature uniformity. The obtained results demonstrate that the new designs proposed have better temperature uniformity than the initial design of cold plates having straight rectangular minichannels.

Hammer it out: shifts in habitat are associated with changes in fin and body shape in the scalloped hammerhead (Sphyrna lewini)

Abstract Major shifts in habitat often occur during life history and can have significant impacts on the morphology and function of an animal; however, little is known about how such ecological changes influence the locomotor system of large aquatic vertebrates. Scalloped hammerheads (Sphyrna lewini) are large sharks found in warm temperate and tropical waters. Smaller scalloped hammerheads are generally found in near-shore habitats, but as they grow larger, individuals spend time in deep-water, pelagic habitats. We measured a number of morphological traits of scalloped hammerheads, ranging from 32 to 130 cm, to determine whether there are allometric changes in morphology in association with this shift in habitat. We found that head morphology, caudal fin area and lateral span scaled with negative allometry, whereas the lengths of their pectoral, dorsal and caudal fins, and their pectoral and caudal fin aspect ratios, scaled with positive allometry. Furthermore, the largest shark in our dataset exhibited an optimal body fineness ratio for locomotor efficiency. This suggests that the changes in ecology have profound influences on the functional morphology of scalloped hammerheads. We discuss how these drastic morphological changes relate to potential changes in scalloped hammerhead swimming function and performance.

Design and implementation of a swimming robot with pectoral fins only

AbstractThe use of swimming robots has increased widely in recent years due to the need of using them in situations where human intervention is difficult or not allowed. Exploring depths of seas, military interventions, or entering areas where the amount of water pollution is high that may threaten the lives of divers. In such cases, the best alternative for humans is to use swimming robots. This paper presents a swimming robot based on Labriform swimming mode. First, it starts with an analytical study of the effect of the fins shape on the performance of a robotic fish. The suggested design of the pectoral fins is concave. The effect of such a design would help largely in achieving the highest thrust in comparison to flat designs provided in the literature. Secondly, a variation in the velocity between the power and recovery strokes is accomplished and a maximum thrust can be obtained when the velocity of the power stroke is three times the velocity of recovery stroke. Thirdly, the kinematics and dynamics of the swimming robot are derived and an evaluation of the total hydrodynamic forces that are exerted on the robot’s body is studied via the computational fluid dynamics method from SOLIDWORKS® platform. Finally, the obtained results are compared to other designs in the literature in terms of some dimensionless numbers of biological fish to examine the efficiency. The proposed design has been validated theoretically and examined experimentally. The results of the simulation and practical experiments confirmed the validity of the design.