Steel Fin Research Articles

Axial and Lateral Load Test Performance of Steel Fin Pile

Steel fin piles may offer increased resistance to lateral and torsional loading; however, there is limited experimental data in the literature for steel fin pile performance. This study evaluates the performance of steel fin piles through field load testing and numerical analysis. Axial and lateral load tests were conducted on two fin piles with a diameter of 273 mm and a length of 3.73 m to evaluate their performance and compare with modeling in LPILE. The lateral tests were conducted with the load applied in two orientations, either in line with the fins or rotated 45 degrees to the fins to assess any difference in performance in the fin orientation to the direction of loading. The effect of the direction of loading compared to the fin orientation proved to be small but existent, with the fin pile displacing less from the lateral load when loaded in between the fins. Additionally, the modeled deflected shape of the fin piles in the lateral test closely matched the observed deflected shape recorded by the shape array instrumentation. The models in LPILE provided results consistent with field observations in the lateral testing, bolstering the viability of fin piles as a prospective replacement to conventional deep foundations when lateral loading governs design.

Thermo-hydraulic performance of solar air heater with finned absorber plate forming multiple rectangular air flow passages in parallel under laminar flow conditions

The paper presents results of an analysis carried out using the governing equations to compare the heat transfer performance of a uniformly heated flat plate with longitudinal fins, which form multiple rectangular air flow passages in parallel below the plate and cover whole of the passage surface, with that of the low aspect ratio rectangular duct typical of conventional flat plate solar air heater at equal pumping power under laminar flow conditions. The heat transfer rate at equal pumping power for the plate with 1 mm thick steel fins at pitch of 25 mm and 40 mm is found to be about 2.7 and 2.5 times, respectively, over the duct without fins. The heat transfer study is followed by thermo-hydraulic performance study of the solar air heater with absorber plate having longitudinal fins forming multiple rectangular air flow passages in parallel. The finned solar air heater with low air mass flow rates has been found to provide 28–31 % better thermal efficiency than the conventional solar air heater at equal pumping power. The results of the study can be utilized for the development of enhanced performance finned solar air heater operating with low air mass rates to deliver high temperature air.

Visual and oxide analysis of an oil-filled heater fire scene

This study demonstrates the use of visual and oxide analyses to identify the cause of an actual electrical fire. Three severely oxidised electric oil-filled heaters and heating elements located at different locations were discovered in the debris of a megamall fire. According to visual analysis, the steel fins exhibited signs of overheating and the presence of large amounts of iron oxidation, denoting that the fins were the probable ignition source. Metallographic analysis showed that oxidation inside the oil-filled heaters at the fire site was also severe. Moreover, the temperature-dependent wear of the metal parts provided new evidence about the exposure temperature of the fire. The microstructure of the oxide scale of metallic materials was also temperature dependent, indicating that metallurgical characterisation will greatly complement conventional evidence collection by way of macroscopic visual examination.

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

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

Enhanced Heat Transfer Performance of Multiple Triangular Air Flow Passages in Parallel With Inclined Fins for Flat Plate Solar Air Heater

Abstract This paper presents results of a study of heat transfer performance of multiple equilateral triangular parallel air flow passages below a uniformly heated flat plate having inclined fins of different thickness, length, and material covering a part of the side walls of the duct for transition to early turbulent regimes using appropriate experimental heat transfer coefficient and friction factor correlations from the literature. The heat transfer performance enhancement at equal pumping power has been measured in terms of a performance parameter (hA/hsAs), where hA is the product of heat transfer coefficient and total heat transfer area for the finned triangular duct, and hsAs is the product for the triangular duct with heated flat plate without fins and adiabatic side walls. The values of the performance parameter for steel fins integral with the heated plate are found to be 1.71–1.78 for 1.0 mm thick fins of 15 mm length and 1.94–2.04 for 1.5 mm thick fins of 20 mm length. For aluminum fins, the performance parameter is 2.36–2.54 for 30 mm long fins of 1–1.5 mm thickness. The results of the presented novel scheme of the finned heated plate can be utilized for the development of enhanced performance solar air heater with the finned absorber plate. Since the presented scheme enhances heat transfer without increased pumping power penalty, the existing smooth rectangular duct solar collectors can be modified for enhanced performance.

Maximum Transparency – Messeturm Frankfurt

The Messeturm in Frankfurt/Main is currently adjusted to the requirements of a modern office building. The lobby area has been enlarged by a highly transparent facade consisting of oversized insulating glass (IG) units. The IG units are curved and have a size of up to 17 m x 2.8 m. The IG units are supported by tapered stainless steel fins. Inclined steel beams connect the top of the facade fins with the tower structure creating a rounded roof. The facade with its glass roof allows maximum transparency for people inside the lobby as well as for people passing by.

Experimental investigation of contact forces and temperatures in rubbing interactions of honeycomb interstate seals

The new architecture of high velocity aircraft engines includes labyrinth-honeycomb interstate seals to improve the engine’s stability. To increase these engines capacity a commonly used strategy is to reduce the clearance between the blades and the sealing system. However, this reduction causes non-desired contacts (rubbing) between the rotating and static components of the engine. This rubbing interaction has an adverse effect on the engine life (wear and thermal cracking) and efficiency. In this work, experimental tests were carried out to recreate the rub between an F110 steel fin and a Hastelloy X honeycomb seal. A conventional CNC machine controlled the sliding and penetration velocities, and the interaction forces and fin tip temperatures were measured during the rub. Results demonstrate the dependence that both, interaction forces and tip temperatures, have with sliding and penetration velocities. However, it is clear that this influence is more pronounced in relation to the sliding velocity.

Repositioning Messeturm–Maximum Transparency

The Messeturm (“Trade Fair Tower”) in Frankfurt is currently adjusted to the requirements of a modern office building. The lobby area has been enlarged by a highly transparent facade consisting of oversized insulating glass (IG) units. The IG units are curved and have a size of up to 17 m $$\times $$ 2.8 m. To obtain a perfectly curved facade, the IG units were fabricated with laminated cold-bended glass panes. Horizontally the IG units are supported by tapered stainless steel fins. Inclined steel beams connect the top of the facade fins with the tower structure creating a rounded roof. The vertical facade with its glass roof allows maximum transparency for people inside the lobby as well as for people passing by outside to the nearby trade fair grounds. The glass was fabricated by sedak. The facade was installed by seele on behalf of the owner OFFICEFIRST, the asset-management of Blackstone.

Experimental investigation and COMSOL modeling for different geometrical configurations of extended surfaces

AbstractThe current work presents and analyzes an experimental and three‐dimensional COMSOL simulation to address and quantify the influence of different geometric cross‐sectional shapes and types of materials (ie, brass and stainless steel) on the thermal performance of extended surfaces. Three cross‐sectional shapes (ie, circular, square, and hexagonal) were examined under various base temperatures (ie, 40°C, 50°C, 60°C, and 70°C). Additionally, two types of fin materials, brass and stainless steel, were investigated to address the impact of thermal conductivity on the temperature distribution, local heat transfer coefficient, heat dissipation rate, efficiency, and effectiveness of extended surfaces. The experimental results showed a significant increase in the heat transfer coefficient and heat dissipation rates for hexagonal brass fins over other shapes and stainless steel fins. The simulation results were validated with the experimental temperature distributions for different geometries and materials under differing operating conditions (ie, different base temperatures, with and without an insulated fin tip). The validation and evaluation of the current COMSOL simulation indicated that the simulated results had high accuracy, with less than a 6% deviation, compared with the experimental data. The current validated COMSOL model can serve as a useful tool to facilitate the design and optimization of fins under various design and operating parameters.

Numerical investigation of thermal performance of extended surfaces for a novel heat exchanger

AbstractThe present paper provides a thorough numerical study of variation in geometrical parameters that affect the performance of the novel finned‐tube type heat exchanger design. The finite volume method was employed to discretize and solve the governing partial differential equations of heat conduction. A wide range of constant convective heat transfer coefficient (5 < h < 200 W/m2 K) is chosen to reduce the computational time and power, which covers thermal applications of latent thermal energy storage, refrigeration & air‐conditioning, etc. The effects of the ratio of fin spacing of fins to the outer diameter of the tube (0.1 ≤ δ* ≤ 8), the material of fins (copper and stainless steel) and the ratio of fin thickness to the outer diameter of the tube (0.0333 ≤ t* ≤ 0.4) on the performance parameters namely efficiency (η) and effectiveness (ε) of the fins were studied. Temperature contours for a wide range of geometries were depicted. The maximum effectiveness of copper fins is 304.62, whereas that for steel fin is 219.33 with the optimum dimensionless fin thickness reported to be t* = 0.1666. Furthermore, the maximum overall efficiencies of fins were 99.98% and 99.62% for copper and steel fins, respectively.

MELTING WITHIN HORIZONTAL H-SHAPED ENCLOSURE WITH ADIABATIC CURVED BOUNDARY AFFECTED BY INCLINATION, MONO/HYBRID NANOFLUIDS AND FINS

From an energy saving viewpoint, full melting of phase change material in thermal storage systems should be achieved. Constrained ice melting with natural convection inside a horizontal H-shaped capsule with adiabatic curved sidewalls is not completed because energy input from hot surfaces overheats the liquid phase on top while stable thermal stratification on bottom persists. Although 90° inclination of capsule engenders full melting of pure ice, the melting process is still sluggish due to low thermal conductivity of ice/water. Hence, heat transfer enhancement techniques using mono Cu, hybrid Ag/MgO nanoparticles, and 310 stainless steel fins are incorporated into system. Existing enthalpy-based lattice Boltzmann method with double distribution function model in single-phase framework is implemented. Insertion of Ag-MgO hybrid nanoparticles within horizontal H-shaped enclosure does not eradicate persistent thermal stratification. Full melting time inside 90° inclined capsule is diminished 13.6 and 24.5%, respectively, when the volume fraction of hybrid nanoparticles is increased from 0.0 to 0.01 and 0.02. While mono Cu nanoparticles give a better thermal performance in contrast to Ag-MgO hybrid nanoparticles, their price is double. Lower volume fraction (0.01) of mono Cu nanoparticles is prescribed since storage capacity is less decreased. Compared to pure PCM melting, partial internal fins mounted on bottom hot surface diminish full melting time 28.0%. However, magnitude of maximum velocity in molten PCM demonstrates that existence of fins considerably limits growth of natural convection flow.

Effect of fin material on PCM melting in a rectangular enclosure

A comprehensive study was conducted to analyse the effect of fin material on PCM melting in a rectangular enclosure. Four commonly employed indicators, surface averaged Nusselt number, melting time, total stored energy and mean power, and two proposed, stored energy per mass and cost per energy stored, were used to evaluate the influence of fin material roundly. Results show that compared with the no-fin scheme, the PCM melts faster and the melting time is reduced by 41.6%, 41.0%, 40.1% and 37.2% with inserting copper, aluminum, carbon steel and steel302 fins. Significant reduction in stored energy per mass is presented by adding fins and the decline range is the highest for the copper fin scheme and the lowest for the aluminum fin scheme, which is 27% and 9.4% respectively. Among four fin schemes, the cost per energy stored is the largest for the copper, 5.6% higher than the no-fin case. The selection of fin material is affected by adopted indicators. If four commonly used indicators are considered only, the copper and carbon steel fin schemes are highly recommended, while the aluminum fin scheme is highly recommended if six indicators are considered simultaneously. A criterion, selecting fin material with higher thermal conductivity, high specific heat capacity, low density and low cost as fins, is proposed.

Results of Thermal Tests of Recirculation Cooling Installations

The article presents the results from thermal tests of some recirculation installations for cooling air in nuclear power plant premises, including the volume under the containment. The cooling effect in such installations is produced by pumping water through its heat-transfer tubes. Air from the cooled room is blown by a fan through a bundle of transversely finned tubes and is removed to the same room after having been cooled. The finning of tubes used in the tested installations was made of Grade 08Kh18N10T and Grade 08Kh18N10 stainless steels or Grade AD1 aluminum. Steel fins were attached to the tube over their entire length by means of high-frequency welding. Aluminum fins were extruded on a lathe from the external tube sheath into which a steel tube had preliminarily been placed. Although the fin extrusion operation was accompanied by pressing the sheath inner part to the steel tube, tight contact between them over the entire surface was not fully achieved. In view of this, the air gap’s thermal resistance coefficient was introduced in calculating the heat transfer between the heat-transferring media. The air gap average thickness was determined from the test results taking into account the gap variation with temperature due to different linear expansion coefficients of steel and aluminum. These tests were mainly aimed at checking if the obtained thermal characteristics were consistent with the values calculated according to the standard recommendations with introduction, if necessary, of modifications to those recommendations.

Comparative study of different storage bed designs of a solid-state hydrogen tank

Abstract This work discusses the influence of different metal hydride storage bed configurations. The objective was to design and optimize a solid-state hydrogen storage for a nonpolluting mobility. A study of the absorption and desorption dynamics of a loose powder bed was performed first, followed by three different storage bed configurations: compacted Ti-Mn alloy powder, alternated Ti-Mn alloy compacts with stainless steel fins and compacted [Ti-Mn alloy/Stainless steel] powder mixture. A numerical model was developed to simulate the heat transfer and the hydrogen absorption and desorption rates. The alternation and compact mixture configurations gave better heat transfer efficiencies, absorption and desorption rates and increased hydrogen storage densities. Indeed, an efficient heat transfer (between the tank and its surrounding fluid), a tailored porosity of the metal hydride storage bed and the addition of high thermal conductivity materials allowed the overall storage performance to be improved. Thus, the required time for loading/unloading hydrogen was reduced drastically. The alternation configuration would offer the additional advantage of a simple, inexpensive and efficient recycling procedure.

Experimental and modeling study on thermal performance of hydrated salt latent heat thermal energy storage system

Phase change material (PCM) holds tremendous promise in the fields of renewable energy utilization and waste heat recovery. In this context, a series of experiments of low-temperature hydrated salt latent heat thermal energy storage (LHTES) system have been conducted to investigate its thermal performance and charging-discharging behavior. Sodium acetate trihydrate mixed with nucleating agent and thickening agent was applied as the PCM and filled into the experimental tube. The temperature evolution of PCM was observed and thermal properties were measured. Numerical model was established to monitor the phase transition process and predict the temperature distribution of PCM filled tube, to make a comparison with the experimental results. It revealed that heat conduction played predominate role in heat transfer when the PCM temperature was below the fusion value, whereas the natural convection was the controlling mode when liquid PCM appeared during the phase transition process. The tube diameter and flow rate were studied to present their effects on the performance of heat storage/release. Compared to smooth tubes, the stainless steel fins and aluminum fins with various thickness added to inside of the tube to enhance the heat transfer. It was found that the heat transfer between thermal fluid and PCM relied greatly in the geometry of the storage tube and fins attribution. The optimized fins geometry can effectively reduce the charging time and discharging time by 27% and 24%, respectively. Our conclusions drawn from this research can provide a theoretical basis for the application of the low-temperature hydrated salt LHTES system.

Retrograde Stainless Steel Flexible Nails Have Superior Resistance to Bending in Distal Third Femoral Shaft Fractures.

It has been shown that retrograde titanium flexible intramedullary nails (Ti FIN) provide superior resistance to bending compared to antegrade Ti FIN in distal femur fractures. The purpose of this study was to compare resistance to torsional and bending forces of stainless steel (SS) FIN, with or without a locking screw, and Ti FIN in distal third femoral shaft fractures. We hypothesize that locked retrograde SS FIN will demonstrate greater resistance to both bending and torsional forces. Thirty adolescent synthetic femur models were used to simulate transverse distal femoral fractures at either 60 mm or 90 mm proximal to the distal femoral physis. The femurs were instrumented with antegrade Ti FIN, antegrade SS FIN, retrograde Ti FIN, retrograde SS FIN, or retrograde locked SS FIN. Three models for each construct at both osteotomy levels were tested. Models were analyzed to determine maximum resistance to bending and torsion. In fractures 60 mm from the physis, retrograde SS FIN demonstrated statistically superior resistance to bending when compared with both antegrade and retrograde Ti FIN (P=0.001 and 0.008, respectively) and antegrade SS FIN (P=0.0001). Locked SS constructs showed a trend towards greater resistance to bending forces when compared with unlocked constructs (P>0.05). No significant difference was seen in resistance to bending when fractures were 90 mm proximal to the distal femoral physis between the five groups. No significant differences were observed in resistance to torsion in either the proximal or distal fracture models, regardless of construct type. Retrograde SS FIN confer significantly greater resistance to bending forces for fractures 60 mm proximal to the distal femoral physis compared with Ti FIN or antegrade entry SS FIN. In fractures 90 mm from the physis, no differences were noted in our model. Our results support the use of retrograde SS nails in the pediatric patient with distal femoral shaft fractures. Level II-comparative biomechanical study.

Numerical investigation of convection in tubes with aluminium and carbon steel fins: evaluating the assumption of convective heat transfer coefficient as that for the tube without fins and relating physical processes with the optimum spacing between fins

Finned tubes exist in diverse geometric configurations, usually the convective heat transfer coefficient is unknown and approximated as that for a geometry similar to the actual one. This paper presents a numerical investigation about the convective heat transfer in a horizontal finned tube. Ten geometric configurations were considered, which differed on the distance between fins, and two materials were analysed for the fins: aluminium and carbon steel. Eleven different values were considered for the temperature difference between the base of the tube and air. Therefore, a total of one hundred and ten different conditions were studied, for each material. The flow regime was laminar. The analysis showed that approximating the convective heat transfer of the finned tube as that for a tube without fins, for which correlations are available in the literature, can lead to significant errors. The maximum difference verified was for the spacing between fins equal to 2 mm, for which the convective heat transfer coefficient was about seven times lower than that for the tube without fins. For spacings equal to 6 mm and 8 mm, associated to the maximum heat transfer rate, the convective heat transfer coefficient for the tube without fins was about 30% to 50% higher than that for the finned tube. The common assumption of uniform fins surface temperature was also evaluated for the two considered materials the fins were made of. The results showed that for the steel fins the approximation leads to an error of about 10%, while for aluminium it is only about 3%. Results that allow a better understanding of the physical phenomena related to the occurrence of the optimum spacing between fins, which maximize the heat transfer, are also presented and analysed.

A hybrid numerical-experimental analysis of heat transfer by forced convection in plate-finned heat exchangers

A hybrid numerical-experimental approach to obtain the thermal performance of heat exchangers is presented. The proposed methodology combines numerical simulation with wind tunnel experimental data to predict the average convective heat transfer coefficient and overall finned surface efficiency. The technique is applied to a plate-finned tube heat exchanger with in-line arrangement. Validation of the present methodology is performed by comparing the results against empirical correlations for the Nusselt number available in the literature. A parametric study is performed aiming to evaluate the influences of the airflow velocity (Reynolds number) and fin materials (aluminium, carbon steel and copper) upon the heat transfer characteristics. The main results indicate an increase of the average convective heat transfer coefficient with air velocity; whereas the overall fin surface efficiency presents an opposite behaviour. Furthermore, the Nusselt number based on the overall heat transfer coefficient is larger for higher conductive fin materials. In addition, aluminium and steel fins are found to be the most weight and cost-effective fin materials, respectively.

Performance analysis of evacuated tubes coupled solar still with double basin solar still and solid fins

ABSTRACT Experimental set up of double basin solar still with evacuated tubes has been fabricated by locally available materials and then carry out research work by use of solid fins. Here 2.5 cm constant depth of water maintained and 3 cm depth mild steel fins are used. Experimental results have been obtained during month of March and April 2018 during clear sky days. Month of March 2018 is chosen for experiments on double basin solar still with evacuated tubes only and April 2018 is chosen for experiments on double basin solar still with evacuated tubes and fins. After series of experiments, it has been found that, the fins increase 25% distillate output compared with alone double basin solar still with evacuated tubes. It also increases distillate output during sunshine hours as well as off-sunshine hours.

A combined ANN-GA and experimental based technique for the estimation of the unknown heat flux for a conjugate heat transfer problem

The major objectives in the design of thermal systems are obtaining the information about thermophysical, transport and boundary properties. The main purpose of this paper is to estimate the unknown heat flux at the surface of a solid body. A constant area mild steel fin is considered and the base is subjected to constant heat flux. During heating, natural convection heat transfer occurs from the fin to ambient. The direct solution, which is the forward problem, is developed as a conjugate heat transfer problem from the fin and the steady state temperature distribution is recorded for any assumed heat flux. In order to model the natural convection heat transfer from the fin, an extended domain is created near the fin geometry and air is specified as a fluid medium and Navier Stokes equation is solved by incorporating the Boussinesq approximation. The computational time involved in executing the forward model is then reduced by developing a neural network (NN) between heat flux values and temperatures based on back propagation algorithm. The conjugate heat transfer NN model is now coupled with Genetic algorithm (GA) for the solution of the inverse problem. Initially, GA is applied to the pure surrogate data, the results are then used as input to the Levenberg- Marquardt method and such hybridization is proven to result in accurate estimation of the unknown heat flux. The hybrid method is then applied for the experimental temperature to estimate the unknown heat flux. A satisfactory agreement between the estimated and actual heat flux is achieved by incorporating the hybrid method.