Fin Radius Research Articles

Study on the flow and heat transfer characteristics of a hybrid nanofluid jet impingement microchannel heat sink with airfoil fins

AbstractDue to the continuously increasing power density of electronic devices, the improvement of the temperature uniformity and the reduction of the irreversible energy losses became crucial in these studies on enhanced cooling capacity of the heat sinks. In this paper, a jet impingement microchannel heat sink with airfoil fins (AF‐JIMHS) is proposed. The AF‐JIMHS with reversed fins arrangement has very high comprehensive heat transfer performance. The increase of the internal tangent circle radius and chord length of fin can improve the temperature uniformity of the AF‐JIMHS bottom surface and reduce the irreversible energy losses, at the expense of reducing its comprehensive heat transfer performance. Although the increase of the tangent arc length of fin reduces the temperature uniformity and increases the irreversible energy losses of the AF‐JIMHS, it improves the comprehensive heat transfer performance in a specific parameter range. The increase of fin height improves temperature uniformity of the AF‐JIMHS, while reducing its irreversible energy losses and improving its comprehensive heat transfer performance. Compared with the AF‐JIMHS with uniform height fins, the one with decreasing height fins has higher comprehensive heat transfer performance and lower irreversible energy losses. Moreover, the AF‐JIMHS with increasing height fins has better temperature uniformity.

Heat transfer optimization for MH reactor using combined taguchi design and data-driven optimization method

Adding the heat transfer enhancement components into the MH reactor can improve the hydrogen absorption/desorption rate, but the vital indicators as the gravimetric and volumetric hydrogen storage density decrease at the same time, which is hardly considered in the published researches. In this study, a comprehensive hydrogen storage performance (CHSP) indicator for the MH reactor has been proposed considering the above contradiction, which can be applied to evaluate the comprehensive performance of the MH reactor and compare the reactor performances with different heat transfer configurations. Then, with the constraint of the CHSP, the heat transfer structure of the classical finned-tube MH reactor is optimized using a novel sieving optimization strategy which combines the Taguchi design and the data-driven optimization (ANN model + GA) to increase the optimization efficiency and the reliability of optimization solutions. The optimized results indicate that the optimal structural parameters of the finned-tube MH reactor are the diameter of heat exchange tube d of 5.13 mm, the fin thickness h of 0.28 mm, the fin radius r of 21.73 mm and the fin number N of 11, and the optimal CHSP is 0.547 mg/s.

Insight into variable thermophysical features of the functionally graded porous annular fin influenced by internal heat and thermal radiation

The present analysis considers a functionally graded porous fin of radiating shape. The fin is subject to thermal-dependent internal heat generation and radiation. Two different cases are performed where the thermal conductivity varies linearly and exponentially with temperature. For simplicity, it is assumed that the material properties of the porous fin change along the fin radius based on a power-law function, with a consistent Poisson’s ratio. The Fourier’s law and Darcy model are used to model the ordinary differential equation (ODE) that governs the fin problem. The equation’s components have been arranged into dimensionless parameters, and their effects on fin efficiency, thermal stresses, and heat transfer rate are discussed and illustrated visually. The analysis comprehensively addresses the radial and tangential stresses and their thermal effects on the fin. It shows that near the base region of the fin, the tangential stress demonstrates less compression, and near the tip radius, there is smaller tensile stress. It has been found that for heat generation coefficient G=0.1 and εG=0.1 the percentage increase in efficiency is 28.1927%.

IDENTIFIKASI MORFOMETRIK DAN MERSITIK BETTA BURDIGALA ASAL PERAIRAN BANGKA SELATAN SEBAGAI DASAR PENGEMBANGAN AKUAKULTUR

Betta burdigala is a type of endemic fish from Bangka Island. The Betta burdigala on Bangka Island is threatened with extinction, with Critically Endangered (CR) status. The decline in the Betta burdigala fish population is caused by habitat degradation and environmental damage. The existence of Betta burdigala fish has never been reported in waters other than Bangka Island. This research aimed to described the morphometric and meristic characteristics of Betta burdigala fish from South Bangka waters as a basis for the conservation and development of aquaculture. The method used in this research is observation, with direct measurement, and observation of morphometric and meristic characters as well as literature studies to identify the morphology of Burdigala betta. The results of this research showed that the morphological characters of Betta burdigala have a mixed form. The shape of the tail fin of the Betta burdigala is round (spherical).. This type of fish's mouth is terminal (located in the anterior middle of the head). The type of scales it has is cosmoid shaped. The average morphometric characters measured were TL(28.25mm), SL(22.05mm), HL(6.15mm), ED(1.5mm), IW(1.6mm), BD(3.8mm), PDL(1.3mm), DBL(7.6mm), DFH(5.8mm), PAL(9.2mm), ABL(10.85), CPD(3.25mm), LUCL(5mm), LMCL(4 .5mm), LCLL(4.1mm). The average meristic character of the Betta burdigala fish is that the dorsal fin rays have the formula D.XIV, the anal fin rays have the formula A.XXV. The caudal fin radius has the formula C.XIII.

Numerical investigation of a thermoelectric generator system with embedded sickle-shaped fins

To enhance the utilization efficiency of exhaust gas in thermoelectric generator (TEG) systems, a polygonal heat exchanger with embedded sickle-shaped fins was proposed in this study. A coupled fluid-thermal-electric multiphysics numerical model was developed to analyze the impact of different fin variables on system performance. Subsequently, the established model was validated on a test bench. The results indicate that embedded sickle fins significantly improve the TEG performance. Higher fins enhance the system's output power and temperature uniformity, albeit with increased pressure drop. Conversely, elongated linear fins and increased arc fin radius decrease pressure drop but reduce its output power. Additionally, increasing the end angle of the arc improves temperature uniformity with minimal effect on output power and pressure drop. Moreover, the TEG system exhibits optimal performance when the linear fin length is 180 mm, the height is 45 mm, the radius of arc fins is 305 mm and the end angle is 8°. At the inlet air temperature of 600 K and the velocity of 40 m/s, the TEG output power, temperature uniformity coefficient and pressure drop for this configuration are 116.59 W, 0.99 and 845 Pa, respectively. This work contributes a theoretical reference for the structural optimization of low-backpressure TEG systems in future automotive exhaust applications.

Perbandingan Struktur Skeleton Sirip Ekor Mudskipper Boleophthalmus boddarti dan Periophthalmus chrysospilos

Glodok fish (mudskipper) is a member of the amphibian fish group that uses its tail fin as a tool for movement, both in water and on land. The aim of this study was to compare the skeleton structure and the number of tail fin bones of Boleophthalmus boddarti and Periophthalmus chrysospilos. The sampling location is in Banyuurip Mangrove Center (BMC), Ujungpangkah District, Gresik Regency. The research was carried out in December 2020-January 2021 at the Unisma FMIPA Laboratory. The research method used is descriptive qualitative, with purposive sampling and Alizarin red staining. The results showed that there was no difference in the tail fin skeleton structure of the two species. The modification of the caudal fins of the two species was shown by widening in the second and third spine hemalis and neural spine. The number of caudal fin bones of B. boddarti is the preural centrum os, two epural bones, the parhypural os, five hypural os, and lepidotrichia with two types of fin radius, namely 3 un-segmented and unbranched fin radii and 17 radii segmented and branched. In P. chrysospilos, there are eight cenrum preural os, two epural os, parhypural os, five hypural os, and lepidotrichia with two types of caudal fin radius, namely 3 un-segmented and unbranched fingers and 14 segmented and branched fingers. Keywords: caudal fin, Boleophthalmus boddarti, Periophthalmus chrysospilos, number of bones

Performance analysis and structure optimization for concentrated photovoltaic-phase change material-thermoelectric system in space conditions

High-efficient thermal management is urgently needed for concentrated photovoltaic-thermoelectric hybrid system due to the high heat flux. In present paper, a three-dimensional model for the hybrid system in outer space conditions was established by coupling phase change temperature control and radiation heat sink technologies to find the propriate thermal management scheme. Firstly, the three shortcomings in the typical hybrid system were proposed and their adverse effects on efficiency were elucidated. Then, a heat transfer pillar for temperature control unit and a newly designed circular fins for heat sink were designed. The effects of structure parameters on power generation performance were investigated, and the interaction between temperature control unit and heat sink were discussed. The results show that the hybrid systems with the newly designed heat transfer pillar and circular fins have higher efficiency. After that, a united structure optimization by artificial neural network-multi-objective genetic algorithm was performed to solve the interaction and to balance the electrical efficiency and power density of hybrid system. The comprehensive power generation performance of hybrid system can be further improved after the optimization. The system with PCM thickness dPCM = 6.33 mm, heat transfer pillar width a = 18.19 mm, fin length L = 49.99 mm and fin radius R = 50 mm, has the maximum average total efficiency (31.83%, 2.98% higher than the typical system); the system with dPCM = 3.02 mm, a = 10.05 mm, L = 47.03 mm and R = 25.86 mm, has the maximum average power density (36.97 W/kg, 15.78% higher than the typical system).

Comparative study on different cooling techniques for photovoltaic thermal management: Hollow fins, wavy channel and insertion of porous object with hybrid nanofluids

The present work considers performance of different cooling methods applicable to photovoltaic (PV) panels. Hollow fins and two different channel cooling systems are considered. Flat and hollow fins types are used while cooling channels with wavy wall and with porous layer insert are compared. Effects of different fin numbers (between 2 and 16), hollow fin radius (between 0.8h and 3.2h, h-panel height), Reynolds number (between 100 and 500), wavy channel amplitude (between 0.01H and 0.5H, H-channel height), porous insert permeability (Darcy number between 10−6 and 10−1), porous layer size (between 0.1L and 0.7L, L-channel length) and nanoparticle volume fraction (between 0 and 0.02) on the cooling performance are numerically assessed. When nanofluid is used in the cooling channels, additional improvements in the cooling performance are obtained while temperature drop of 2.5 °C is achieved at the highest loading. When different cooling systems are compared, channel cooling with porous layer and wavy walls provide the highest cooling performance followed by hollow fin and flat fin systems while 37.6 °C , 37 °C, 33.6 °C and 29 °C temperature drops are obtained as compared to reference panel case without cooling system. When compared to flat fins, hollow fins perform better and additional temperature drop of 8.5 °C can be obtained by using 16 number of fins. It also provides a lightweight design as less material is used. Artificial neural networks are successfully used for performance estimation of wavy cooling channel system with 15 neurons in the hidden layer. The outcomes of this work is useful in further optimization and system development of PV cooling technologies as the need for thermal management in renewable energy sources is increasing due to the energy cost and environmental side concerns.

POPULATION DIVERSITY BASED ON MORPHOMETRIC MERISTIC ENDEMIC BUTINI FISH (Glossogobius matanensis) IN LAKE TOWUTI, SOUTH SULAWESI

Butini fish is a resource wealth of fauna found only in the East Complex Malili Luwu, South Sulawesi. The necessary information about the morphological characters (morphometric and meristic) to determine the management of fish resources. The purpose is to assess the diversity of populations based on morphometric meristik. Sampling is based on descriptive methods and fish samples taken to determine the diversity of phenotypes based on the depth of each morphometric character. Calculating morphometric characters using the main component analysis to obtain the correlation between the character and the grouping of individuals based on morphometric characters. Calculation meristik characters include the number of fingers, the number of fins and scales, namely the number of fingers of the dorsal fin, anal fin radius, the radius of the ventral fin, pectoral fin radius, the radius of the caudal fin, scales on the rib line, scales above the rib line, scales below the ribs, scales in front of the dorsal fins, scales on the cheeks, around the body scales, scales around the tail shaft. The analysis showed that the first two principal components contained the greatest information, with a cumulative range of 80%. All the characters' morphometric first role is a major component. The character who plays the main component of the length of the head in front of the eyes, long upper jaw, lower jaw length, high cheeks, and the length of the radius of a weak base ventral fins showed great correlation to the diversity of forms. Main components analysis also showed that butini fish, at any depth, showed no grouping. This suggests that the fish species observed was one (one unit of population). In calculating the value of phenotypic diversity of each character, butini generally fish in the lake Towuti show morphometric characters with the highest diversity value and the lowest given by the total length and high under the eyes. In the calculation of the formula derived characters meristik flipper fingers that D1, V-VI. D2. I, 8-11; dan D1, V-VI, D2. I, 8-10.

An analytical design tool for pin fin sorber bed heat/mass exchanger

This paper proposes a novel closed-form analytical model to predict the sorption performance of a pin fin heat/mass exchanger (PF-HMX) prototype, using the Eigenfunction expansion method to solve the governing energy equation. The proposed transient 2-D solution includes all salient thermophysical and sorption properties, sorbent geometry, operating conditions, and the thermal contact resistance at the interface between the sorber bed heat exchanger and sorption composite. An analysis of variance (ANOVA) method is utilized to understand the percentage contribution of each parameter on specific cooling power (SCP) and coefficient of performance (COP). It is shown that the amount of graphite flake, sorbent thickness, and fin radius on one hand and cycle time and graphite flake content on the other have the highest level of contribution to the COP and SCP, respectively. Moreover, a parametric study found that HMX geometry, sorbent properties, and cycle time counteract effects on COP and SCP, which should be optimized simultaneously to build an optimal design. The analytical model was validated successfully using the sorption data from a custom-built gravimetric large temperature jump (G-LTJ) testbed. The experimental results show that the present PF-HMX design with a relatively low mass ratio (MR) can achieve an SCP of 1160 W kg−1 and a COP of 0.68 which are higher than the previously published results in the literature.

Study of Morphomeristic and Habitat Tempuring Fish (Puntius spp) In Bangka Island Freshwater

This study aims to analyze the morphomeristic characteristics and habitat of Tempuring Fish (Puntius spp) in Bangka Island. The research was conducted from February to March 2020 at Bangka Island. The study used a survey method using primary and secondary data. Based on the analysis of the morphomeristic characteristics, The kind of tempuring (Puntius spp) which found in the Freshwater of Bangka Island are Puntius lineatus dan Puntius johorensis. Puntius lineatus on Bangka Island has a total body length (TL) ranging from 67.13 to 75.80 mm; head height (HD) ranges from 10 -12 mm; height (BD) ranged from 15.47-18.60 mm; dorsal fin radius (DR) D.I-II. 8-9; and lateral line (LL) scales ranging from 24-25 mm; characterized by having 5 vertical black lines on the body. Puntius johorensis has a total body length (TL) ranging from 59.60-80.67mm; head height (HD) ranged from 10.40 -16.00 mm; height (BD) ranged from 14.00-28.44 mm; dorsal fin radius (DR) D.I-II. 6-10; and lateral line (LL) scales ranging from 25-30 mm; characterized by having 6 vertical black lines on the body. Ecology of Tempuring in Bangka Island freshwater when viewed from several water quality parameters, including temperature ranges from 29-31 °C, pH 5, water transparency 0.27 - 0.36 m, flow velocity 0.03-0.06 m / s, and TSS range from 4-19.2 mg / l. This indicates that the water quality of the Tempuring Fish habitat on Bangka Island is still in a good range.
 Morphomeristic; Tempuring; Puntius lineatus; Puntius johorensis; Bangka Island

Experimental and Cfd Analysis of Heat Transfer Rate in Multi Air Jet Impingement Over A Flat Plate and Pin-Fin Heat Sink

In this paper reports the results of investigation of heat transfer performance of in compression air jet impinging of heated surface over a flat plate & pin-fin heat sink. To mimic the computer processor of flat plate and pin fin dimensions are 120mm*75mm and pin height is 5cm and fin radius is 1cm and L/d ratios are 5,10,15respectively. By using this simulation in Ansys fluent software to perform the turbulent jet impingement on a surface. The bottom surface of the plate is supply constant heat flux and top surface of the plate is cooled by an impingement jet of air. It has two equations are used k-w model and shear stress transport to handle the turbulent jet. The result of flat plate heat sink is compare the Experimental and simulation is higher at 0.89% of experimental to compare numerical and Nusselt is higher at 3.35% of numerical to compare the experimental and heat transfer coefficient is higher at 4.51% of numerical to compare the Experimental and result of pin fin heat sink is compare the Experimental and numerical is higher at 0.23% of experimental to compare the numerical and Nusselt number is higher at 0.71% of numerical to compare the experimental and heat transfer coefficient is higher at 0.88% of numerical to compare the experimental. The effect of L/d ratios of jet impingement over a flat plate and pin fin heat sink on the heat transfer performance of the heated surface of investigated.

Numerical modeling and performance comparison of high-temperature metal hydride reactor equipped with bakery system for solar thermal energy storage

The current study provides an optimal design strategy for the metal hydride reactor for the thermal energy storage system for solar bakery applications. The sensitivity analysis of the annular truncated hollow conical fins type reactor was conducted by using COMSOL Multiphysics 5.3a software. The gravimetric exergy output rate and exergy output of different designs were compared. It was found that the optimal geometric parameters and operating conditions for the annular truncated hollow conical fins type reactor are fin angle (θ)=20°, fin radius (Rf) = 0.07 m, number of fins (Nf)= 32 and fin spacing (Sf) = 0.02 m, fin thickness (thf) = 0.008 m, hydrogen supply pressure (Pin, H2) = 5 MPa and inlet heat transfer fluid velocity (VHTF,in) = 20 m/s. Finally, it was concluded that the Deign IV is the most favorable design, which has a uniform reaction, faster reaction time (15,000 s), and higher values of gravimetric exergy output rate and exergy output (1.23 W/kg, 0.028 kW).

Multi-objective optimization of a latent thermal energy storage unit with compound enhancement method

The compound enhancement method shows excellent prospects for improving the heat transfer performance of phase change materials (PCMs) in recent years. This study intends to design and investigate an efficient latent thermal energy storage (LTES) unit with a novel combination of the heat pipe (HP), fins, copper foam, and nanoparticles. To explore the combination characteristics, a method that includes the multi-objective differential evolution (DE) algorithm, the response surface methodology (RSM), and conventional numerical simulations was developed. The optimization was carried out to minimize the phase change time and maximize the exergy conversion capacity. The results indicate that the fin radius and the porosity significantly affect the phase change time, while the PCM enclosure height and the PCM enclosure radius profoundly affect the exergy conversion capacity. The main and interaction effects of seven control parameters on the thermal characteristics were also investigated. The existence of some strong synergistic effects indicates that the appropriate values of the control parameters are crucial in designing the highly efficient LTES unit. Moreover, the Pareto front was displayed to prove the effectiveness of the multi-objective DE algorithm by achieving a reasonable balance between the two conflicting objectives.

Transient thermal stress analysis of functionally graded annular fin with free base

The present study aims to provide a deeper understanding for the transient thermal stress distributions of an annular fin made of FGM. The material properties of annular fin are assumed to be graded along the fin radius as a power-law function while the Poisson’s ratio is taken to be constant for simplicity. The energy balance equation is solved on Laplace domain by using exponential like solution introduced by Keller and Keller and Gauss quadrature method. The transformation to time domain achieved by using Durbin fast Fourier transformation method. The temperature distribution and thermal stresses are presented in graphical form for FG annular fin that is pure ceramic in the base and pure metal on the tip.

Configuration and Optimization of a Minichannel Using Water-Alumina Nanofluid by Non-Dominated Sorting Genetic Algorithm and Response Surface Method.

Nanofluids in minichannels with various configurations are applied as cooling and heating fluids. Therefore, it is essential to have an optimal design of minichannels. For this purpose, a square channel with a cylinder in the center connected to wavy fins at various concentrations of an Al2O3 nanofluid is simulated using the finite volume method (FVM). Moreover, central composite design (CCD) is used as a method of design of experiment (DOE) to study the effects of three input variables, namely the cylinder diameter, channel width, and fin radius on the convective heat transfer and pumping power. The impacts of the linear term, together with those of the square and interactive on the response variables are determined using Pareto and main effects plots by an ANOVA. The non-dominated sorting genetic algorithm-II (NSGA-II), along with the response surface methodology (RSM) is applied to achieve the optimal configuration and nanofluid concentration. The results indicate that the effect of the channel width and cylinder diameter enhances about 21% and 18% by increasing the concentration from 0% to 5%. On the other hand, the pumping power response is not sensitive to the nanofluid concentration. Besides, the channel width has the highest and lowest effect on the heat transfer coefficient (HTC) and pumping power, respectively. The optimization for a concentration of 3% indicates that in Re = 500 when the geometry is optimized, the HTC enhances by almost 9%, while the pumping power increases by about 18%. In contrast, by increasing the concentration from 1% to 3%, merely an 8% enhancement in HTC is obtained, while the pumping power intensifies around 60%.

WEDM of Copper for the Fabrication of Large Surface-Area Micro-Channels A Prerequisite for the High Heat-Transfer Rate.

To get the maximum heat transfer in real applications, the surface area of the micro-features (micro-channels) needs to be large as possible. It can be achieved by producing a maximum number of micro-channels per unit area. Since each successive pair of the micro-channels contain an inter-channels fin, therefore the inter-channels fin thickness (IFT) plays a pivotal role in determining the number of micro-channels to be produced in the given area. During machining, the fabrication of deep micro-channels is a challenge. Wire-cut electrical discharge machining (EDM) could be a viable alternative to fabricate deep micro-channels with thin inter-channels fins (higher aspect ratio) resulting in larger surface area. In this research, minimum IFT and the corresponding machining conditions have been sought for producing micro-channels in copper. The other attributes associated with the micro-channels have also been deeply investigated including the inter-channels fin height (IFH), inter-channels fin radius (IFR) and the micro-channels width (MCW). The results reveal that the inter-channels fin is the most critical feature to control during the wire electrical discharge machining (WEDM) of copper. Four types of fin shapes have been experienced, including the fins: broken at the top end, deflected at the top end, curled bend at the top, and straight with no/negligible deflection.

Effect of fin design parameters on the performance of a two-bed adsorption chiller

Abstract Adsorption refrigeration systems are commercially matured due to the need of decreasing electrical power consumption and usage of non-environmental refrigerants, which are the main problems of the conventional refrigeration systems. This paper presents an investigation on the performance of small-scale two-bed adsorption chiller combined with heat and mass recovery cycles with the aid of a lumped analytical simulation technique. This model is applied to analyze the effect of fin design parameters on the heat transfer inside the bed and system performance. The working pair used in the simulations is RD silica gel–water. Defining a base-case for the fin design parameters, fin thickness, fin radius, and fin spacing are changed and the performances of four fin configurations are demonstrated. Decreasing the fin spacing enhances the heat transfer significantly. For optimum operation condition, specific cooling capacity is improved by an average value up to 147.6% by decreasing fin spacing from 4 mm to 2 mm, while increasing the fin radius decreases temperatures of the adsorbent. Specific cooling capacity is improved by an average value up to 44% by decreasing fin radius from 16 mm to 8 mm. The fin thickness has a minor effect on heat transfer in the bed.

A Practical Approach for Thermal Stress of Functionally Graded Annular Fin

A practical approach is implemented for thermal stresses in an axisymmetric thin annular fin, made of functionally graded material. All material properties of the annular fin are assumed to be graded along the fin radius as a power-law function. A linear differential equation is derived to be the governing equation. Analytical solution of such equations except for simple grading functions is difficult or maybe not possible to implement for each parameter, so the numerical approach becomes inevitable. The novelty of the present study is to introduce the effects of mechanical and thermal properties on the thermal stress distribution of functionally graded annular fin with the help of a complementary function method (CFM). The complementary functions method will be incorporated into the analysis to convert the problem to an initial value problem, which can be easily solved by, for instance, Runge−Kutta methods with great accuracy. The results are validated for isotropic and homogeneous annular fin.

Fabrication of Composite Heat Sinks Consisting of a Thin Metallic Skin and a Polymer Core Using Wire-Arc Spraying

Three composite heat sinks in the shape of a disk, a cylinder, and a cylinder with vertically projecting fins were made by applying a thin (0.4-0.7 mm) zinc layer onto ABS polymer cores using wire-arc spraying. The influence of spray distance and surface roughness on the adhesion strength between the zinc and ABS layers was investigated, and a maximum adhesion strength of 2.6 MPa was obtained. An analytical model of the heat conduction in an annular fin was developed, assuming one-dimensional heat conduction in the metal coating and two-dimensional conduction in the polymer core. The temperature distribution along the disk-shaped heat sink was measured using an infrared camera and found to agree well with the developed model. The calculated temperatures at the base of the heat sink also agreed with measured values as heater power was varied. The model was used to examine the effect of fin radius and coating thickness on fin efficiency.