Optimum Fin Spacing Research Articles

Optimization of a thermal energy storage system enhanced with fins using generative adversarial networks method

Optimizing fin configurations is an effective method to improve the performance of a thermal energy storage system. The present research aims to determine the optimal fin spacing and inclination angle to minimize the melting process of a phase change material (PCM) in a rectangular enclosure, which is exposed to a constant temperate finned wall while other walls are adiabatic. Oleic acid (OA) is used as a PCM with a melting temperature of 287–288 K. Computational fluid dynamics (CFD) simulations are employed to comprehensively investigate the thermal behavior of the system by solving continuity, momentum, and energy equations simultaneously. Initially, fifteen different datasets are simulated using CFD methods to explore various fin configurations. After that, fifteen additional datasets are generated to verify the reliability of the generative adversarial networks (GANs) method, which supplements the CFD approach. An ensemble learning approach is implemented to create a hybrid dataset consisting of thirty datasets, and then the optimum dataset is determined. To validate this approach, a single numerical simulation is conducted at the optimum dataset, and the obtained optimum value, minimum melting time of PCM, is compared with the result obtained from CFD simulation. It is identified as the optimal fin configuration, resulting in a fin spacing of 15.75 mm and an inclination angle of −11.6°, highlights the efficacy of the combined CFD and GANs approach. The melting time captured from the numerical simulation and the one produced with GANs differed by about 4.7 %. The current study concludes that the GANs method might be effectively worthwhile in many energy storage applications.

Multi-objective optimization of thermal management system for multiple heat source arrays electronic chassis in a noiseless environment

Effective thermal management of electronic chassis is currently a critical concern. A heat sink with fins and heat pipes is suggested in this paper. It is intended to handle the heat produced by numerous sources within an electronic case and enhance its functionality. The parameters have been examined and improved in order to work quietly. Response surface methodology (RSM) was employed to examine the influence of fin length, fin thickness, fin spacing and Re on the junction temperature, temperature uniformity and thermal resistance of the heat sink for a printed circuit board array (PCBA). The parameter combinations were optimized using a genetic algorithm. The results indicated that the optimal fin spacing is 11 mm, optimal length is 199 m, and optimal thickness is 2.9 mm when the Reynolds number falls within the range of 2000 ≤ Re ≤ 7000. Compared to the original fins, the combined finned heat pipe heat sink decreases the temperature of the PCBA junction by approximately 10 K, enhances the temperature uniformity by around 49 %, and diminishes the total thermal resistance by nearly 48 %. The optimal air velocity is approximately 0.41 m/s. The improved heat sink can efficiently enhance the thermal management of electronic casings.

Study on performance of carbon nanotube composite phase change cold storage sphere with annular fins

Aiming at the poor phase change material thermal conductivity, high shell layer thermal resistance and low cold storage efficiency in encapsulated cold storage sphere systems, we adopt computational fluid dynamics to numerically investigate the cold storage process after adding carbon nanotubes to phase change paraffin cold storage spheres. The heat transfer model of a new type of annular-finned cold storage sphere and cold storage device is established, and the effects of sphere diameter, shell material, fins and refrigerating medium flow rate on the cold storage process are investigated. The results show that the optimum fin length of the sphere is 11 mm and the optimum fin spacing is 8 mm at a sphere diameter of 50 mm. The completion time of the carbon nanotube-added annular finned sphere is 48 min shorter than that of the traditional pure paraffin sphere without fins, and the cooling efficiency increases by 61.7 %, which is better than those of adding either fins or carbon nanotubes; carbon nanotube additions are better than fin additions to the single-variable factors to enhance the cooling effect. The convective heat transfer coefficients at 4 m/s and 5 m/s refrigerating medium flow rates increase by 20.1 % and 42.3 %, respectively, compared with those at 3 m/s. We provide a theoretical basis and reference value for the optimal design of an accumulator sphere and its devices.

A new analytical model of condensation outside low-finned tubes for refrigerants at low temperatures and high heat flux

In this paper, a new analytical model is developed for the condensation of refrigerants outside low-finned tubes. It is based on the flow and heat transfer characteristics at low saturation temperatures and high heat flux, such as those in the LNG intermediate fluid vaporizer (IFV). Due to the increase of viscous effect at lower saturation temperature and higher heat flux, the previous condensate retention angle models are modified by adding the viscous term. At high heat flux and condensate rate, the condensate profile at the fin root is simplified to be arc-shaped and obtained directly by force analysis. Furthermore, considering the heat transfer enhancement caused by the circumferential flow at high heat flux, the convective mechanism is included for the heat transfer through the thick liquid film between the fins. The distributions of liquid film and fin surface temperature are also predicted. The present analytical model is in good agreement with different experimental and numerical results, while most deviations are within 10% for predicting the heat transfer coefficients at high heat flux. Because of the increased flow viscosity and surface tension, the optimal fin spacing and fin height increase as the heat flux increases and the saturation temperature decreases.

Thermal Management of Microelectronic Devices Using Nanofluid with Metal foam Heat Sink.

Microelectronic components are used in a variety of applications that range from processing units to smart devices. These components are prone to malfunctions at high temperatures exceeding 373 K in the form of heat dissipation. To resolve this issue, in microelectronic components, a cooling system is required. This issue can be better dealt with by using a combination of metal foam, heat sinks, and nanofluids. This study investigates the effect of using a rectangular-finned heat sink integrated with metal foam between the fins, and different water-based nanofluids as the working fluid for cooling purposes. A 3D numerical model of the metal foam with a BCC-unit cell structure is used. Various parameters are analyzed: temperature, pressure drop, overall heat transfer coefficient, Nusselt number, and flow rate. Fluid flows through the metal foam in a turbulent flow with a Reynold's number ranging from 2100 to 6500. The optimum fin height, thickness, spacing, and base thickness for the heat sink are analyzed, and for the metal foam, the material, porosity, and pore density are investigated. In addition, the volume fraction, nanoparticle material, and flow rate for the nanofluid is obtained. The results showed that the use of metal foam enhanced the thermal performance of the heat sink, and nanofluids provided better thermal management than pure water. For both cases, a higher Nusselt number, overall heat transfer coefficient, and better temperature reduction is achieved. CuO nanofluid and high-porosity low-pore-density metal foam provided the optimum results, namely a base temperature of 314 K, compared to 341 K, with a pressure drop of 130 Pa. A trade-off was achieved between the temperature reduction and pumping power, as higher concentrations of nanofluid provided better thermal management and resulted in a large pressure drop.

Evaluation of the solidification process in a double‐tube latent heat storage unit equipped with circular fins with optimum fin spacing

AbstractIn this study, the effect of fin number and size on the solidification output of a double‐tube container filled with phase change material (PCM) was analyzed numerically. By altering the fins' dimensions, the PCM's heat transfer performance is examined and compared to finless scenarios. To attain optimal performance, multiple inline configurations are explored. In addition, the initial conditions of the heat transfer fluid (HTF), including temperature and Reynolds number, are considered in the analysis. The research results show a significant impact of longer fins with higher numbers on improving the solidification rate of PCM. The solidification rate increases by 67%, 170%, 308%, and 370% for cases with 4, 9, 15, and 19 fins, respectively, all with the same fin length and initial HTF boundary condition. The best case results in a solidification time that is 4.45 times shorter compared to other fin number and dimension scenarios. The study also found that moving from Reynolds numbers 500 to 1000 and 2000 reduced discharging times by 12.9% and 22%, respectively, and increased heat recovery rates by 14.4% and 27.9%. When the HTF entrance temperature was 10°C and 15°C, the coolant temperature showed that the entire discharging time decreased by 37.5% and 23.1% relative to the solidification time when the initial temperature was 20°C. Generally, this work highlights that increasing the length and number of fins enhances thermal efficiency and the phase change process.

CFD Simulation Study on the Air Side of a CO2 Evaporator in a Motor Train Unit Air Conditioning System

At present, China’s high-speed rail is in a period of rapid development. Most of the refrigerants used in Chinese motor train units at this stage are still R134a and R407c, which have an impact on the environment. In response to the environmental protection concept of green travel, it is of great significance to study the air conditioning system of motor train units using CO2 refrigerant. Using CFD simulation analysis technology, the heat transfer performance of the air side of the CO2 finned tube evaporator used in the air conditioning system of the motor train unit is studied. We select the air outlet temperature, pressure drop, heat transfer factor, and resistance factor as the objective function, in addition, monitoring points are set up in the air flow channel to monitor the turbulent flow field and pipe wall pressure. Our research shows that the cooling capacity of the CO2 evaporator can reach up to 29.76 kW, which can meet the heat exchange required in the air conditioning system of the motor train unit. In order to obtain a better structure and the conditions of the heat transfer effect, structural optimization was conducted. The simulation results demonstrate several trends: (i) With the augment of the air inlet velocity, the cooling capacity of the evaporator increases and the heat exchange effect improves; when the air inlet ve > 2.2 m/s, the effect of continuing to augment ve on heat exchange is weak. (ii) Following appropriate reduction of the diameter of the heat exchange tube, the wind resistance is reduced and the cooling capacity of the evaporator is improved. (iii) With the enlargement of the fin spacing, the turbulent motion in the flow channel can be fully developed, there is a peak in the change in the heat exchange tube area optimization factor, and the optimal fin spacing is between 1.6 mm and 1.7 mm; at this time, the average turbulent kinetic energy of the air side is larger and the turbulent dissipation rate is smaller. These results provide a reference for the practical application of CO2 refrigerant in the motor train unit.

Thermal management and optimization of the reactor geometry for adsorbed natural gas storage systems subjected to free convection and radiative environment

The present investigation explores the effects of the reactor geometry (i.e., the aspect ratio of cylindrical and annular reactors with and without fins, fin spacing, the aspect ratio of fins for finned reactors, and outer to inner diameter ratio for annular unfinned reactors) on the heat and mass transfer characteristics of the adsorbed natural gas storage system employing passive cooling techniques. The authors try to capture how the geometric modification changes the surrounding buoyancy-driven flow physics and improves the proposed novel reactor's storage performance. The study also considers surface radiation, which significantly improves the heat transfer rate, especially for the reactor with lower internal thermal resistance. An attempt is made to reduce the internal thermal resistance of the adsorbent bed by adding 10% graphite by mass and suitably modeling the bed's thermal conductivity and thermal capacity. The result shows that, in terms of adsorbed amount and heat transfer rate, the reactors with an aspect ratio (AR) of 7.8 outperform the other aspect ratios. The simultaneous effects of reactor aspect ratio and fins spacing on the heat transfer and adsorption rates are expounded, and the optimum fin spacing as a function of reactor aspect ratio and diameter ratio (i.e., fin diameter to reactor diameter) is obtained. The best annular reactor outperforms the cylindrical reactor with and without fin in terms of volumetric and gravimetric storage capacity. The annular finned reactor achieves a maximum 33% improvement in storage capacity compared to the adiabatic case and isothermal efficiency of 90%.

Optimization of Horizontal Annular Finned Tube Under Natural Convection Heat Transfer

Free convection heat transfer over annular finned tubes was studied numerically for more than 60 different cases and verified against two experimental works. In addition, the effect of fin spacing on heat transfer was investigated. As a result, a correlation was proposed to estimate Nusselt number as a function of Rayleigh number. Moreover, it was shown that there was an optimum fin spacing for which the total heat transfer was maximized. Based on the proposed equation, an expression for optimum fin spacing was derived, which proved that the optimum Nusselt number was 0.9035. The presented equation for optimum fin spacing was a general equation in so far that it could also be used to find the optimum spacing between a series of circular disks by letting the tube diameter in the equation be zero. Moreover, a good agreement was observed between the derived equation for optimum fin spacing and the results of the scale analysis method.

Role of extended surfaces on the enhancement of quenching performance

High heat transfer rate is essential in several industrial applications, including, nuclear reactors, storage and transport of cryogenic liquid, and metal forming, which deal with the rapid cooling of various materials. Rapid cooling of surfaces at temperatures significantly higher than the boiling point of the coolant is often restricted by formation of a vapor layer around the surface that retards the rate at which heat can be dissipated. In the present work we report on the effect of finned structures of millimetric length scale on the enhancement of heat transfer performance during quenching. The fins are observed to destabilize hydrodynamic vapor layer during film boiling. We show that the quench duration reduces by ~3.8 times and the maximum heat flux (MHF) increases by nearly 230% for the finned sample as compared to the smooth samples. The quench duration and heat transfer rate are shown to be dependent on spacing between fins and the optimum fin spacing is determined to yield the highest MHF and minimum quench time.

Review on Heat Transfer Enhancement by Rectangular Fin

Heat generation of engineering appliances has bad effect in handling the system can cause the trouble, short life cycle of machines, frequent maintenance requirements and low reliability of systems. The passive cooling technique has been widely used to solve such problems. This review work summarizes the heat transfer enhancement technique in a rectangular fin with economic way. So many research about the enhancement of heat transfer by rectangular fins experimentally and numerically and found very significant result. In this review, various types of rectangular fin structures are studied simultaneously. It is revealed through reviewing the related literature that the highest value of equivalent heat transfer enhancement is found the increase in average heat transfer performance of inverted triangular notched fin 50.51% as compared with plane rectangular fin and the perforated fin total heat transfer rate increased by 38.9% compared to regular fin. Furthermore, by reduction of the optimal fin spacing, heat flux can be changed by 20% in standard rectangular fin when compared with regular fin spacing. Also cooling performance of the inclined rectangular fin with 60° of tilt angle is seen to be as 6% higher than solid rectangular fin. This article can be considered as a benchmark in the practical application for enhances the heat transfer rates.

Numerical studies on the influence of natural convection under inclination on optimal aluminium proportions and fin spacings in a rectangular aluminium finned latent-heat thermal energy storage

• Angular dependency of natural convection effects in aluminium finned PCM cavities. • Evaluation of heat transfer enhancement of aluminium proportions and fin spacings. • Guideline values for optimal aluminium proportions in heat transfer structure. • Optimal fin spacing in heat transfer structure for varying cavity orientations. Phase change material (PCM) is applicable in various use cases, such as in a novel hybrid steam/latent heat storage system where containers filled with PCM are placed at the shell surface of a Ruths steam storage (RSS) for retrofitting. The considered approximately rectangular PCM cavity design includes aluminium fins, which is a common choice for heat transfer enhancement. Numerical studies were conducted with two separate numerical models to analyse melting and solidification of PCM in such cavity. Varying aluminium proportions, as well as varying fin spacings were simulated under different orientations of the PCM cavity and their impact on charging/discharging speed was analysed, providing a foundation for design optimization of the considered geometry. Guideline values for optimal aluminium ratio and optimal fin spacing could be obtained. Significant angular dependency on the thermophysical behaviour could be observed during melting, whereas the effect of natural convection during solidification was found to be negligible. The results of this work provide important insight to facilitate the design process of rectangular aluminium finned PCM cavities.

CFD analysis on heat transfer through different extended surfaces

AbstractThe present study includes computational fluid dynamics analysis and comparison of heat enhancement through different extended surfaces, especially in rectangular and square conductive and nonconductive fins. Computational and numerical analysis of heat transfer from a rectangular extended surface and a pin‐finned plate studied to calculate the average Nusselt number in parallel, vertical direction placed along the sidewall. The total rise of the mean Nusselt number is noticed around 36% in pin‐finned plate with respect to a plain plate. This is examined with optimal fin spacing of Sv with L ratio equals to 0.2 and Sh with W ratio equals to 0.25, height of extended surfaces 24 mm with 45° angle of inclination. The mean Nusselt number reduces with a rise in the angle of inclination and also increases with a rise in aspect ratio. The present study reveals that inline and staggered arrangements do not yield appreciably different results. The maximum average Nusselt number difference between conductive and nonconductive fins is around 5% for Sh per W ratio 0.33 and Sv per L ratio 0.2 at an angle of inclination 45°, fin height of 6 mm (height to thickness ratio 2).

Analysis and Simulation of PV Solar Panel with Face Down Finned Heat Sink

Electrical/thermal modeling and simulation of a solar PV panel was made. The effect of face down finned heat sink which is attached to the back surface of panel in lowering the cell temperature and improving the panel electrical efficiency was studied. The performance of a typical PV panel was programed using MATLAB to predict the variation of current and voltage produced by the panel. Thermal modeling of the PV was also made including all modes of heat transfer. To show the effect of the finned heat sink on the cell temperature and PV efficiency both cases with and without heat sink were studied. Convection and radiation heat transfer from the finned heat sink were considered. The simulation results indicate an optimum fin spacing of 12 mm and a fin height of 150 mm for the considered PV 65.2 W solar panel. A decrease in cell temperature of about 25% and an improvement of about 10.8% in efficiency were predicted when attaching geometrically optimized facedown finned heat sink to PV solar panel under an ambient temperature range of 25 °C to 50 °C, and a solar flux of 1000 W/m2.

Numerical analysis of 2-D laminar natural convection heat transfer from solid horizontal cylinders with longitudinal fins

Proper thermal management through an effective cooling mechanism is essential for improving the reliability of operation of various electronic devices. A number of cooling methods are available among which passive cooling by natural convection has been deemed appropriate since it has distinctive advantages over active cooling or forced convection like high reliability, low maintenance cost, energy efficiency and noise-free nature. In the present study, natural convection from solid horizontal cylindrical heat sources of the geometry and dimensions of heat sinks of LED bulbs with external longitudinal plate fins have been modelled. Numerical computations of continuity, momentum and energy equations to solve the two dimensional incompressible natural convection conjugate heat transfer from such cylinders has been studied in the laminar regime (4.5×105<RaD<5.2×105). The diameter of the cylinder is kept at 60 mm whereas the length is kept at 50 mm. The number of fins has been varied from three to 36, the height of fins kept at 10, 20 and 30 mm and thickness at one mm. The effect of fin geometry parameters and Rayleigh number on total heat transfer, heat transfer exclusively from fin surface and from bare cylinder surface, heat transfer per fin and Nusselt number based on cylinder diameter have been studied in detail. Finally, optimum fin spacing for a particular fin height has been evaluated. Contour plots to capture temperature and velocity vectors around the heat source have also been developed. Numerical correlations of Nusselt number as a function of Rayleigh number, non-dimensional fin spacing and non-dimensional fin height reveal that the scaling laws of RaD1∕3 and RaD1∕4 are valid both for the computational data of our present analysis and experimental data even though the experiments are for a slightly different boundary condition.

Enhancement of Heat Transfer From Extended Surfaces by CFD

Theoretical studies and analysis of heat transfer from a rectangular extended surfaces and a pin finned plate studied to calculate the average Nusselt number in parallel, vertical direction placed along the sidewall. The total rise of the mean Nusselt number is noticed around 36% for pin finned plate with respect to a plain plate. This is examined with optimal fin spacing of Sv with L ratio equals to 0.2 and Sh with W ratio equals to 0.25, height of extended surfaces 24 mm (Height to thickness ratio 8), and 45o angle of inclination . The mean Nusselt number decreases with rise in angle of inclination and also increases with rise in aspect ratio. Present study reveals that in-line and staggered arrangements do not yield appreciably different results.The maximum average Nusselt number difference between conductive and non-conductive fins is around 5 % for Sh/W= 0.33, Sv/L =0.2 at θ = 45°, fin height of 6 mm (H/t=2).

Experimental determination of buoyancy induced convection heat transfer characteristics in a rectangular cavity with cylindrical porous medium fixed between pin fins

The present work aims to investigate the heat transfer characteristics of heated cylindrical pins within an air-filled rectangular enclosure experimentally in a natural convection dominated regime. The experiments are performed to analyze the effects of fin spacing (25 mm ≤ S ≤ 100 mm) and Rayleigh number (248,659 ≤ Ra ≤ 578,395) as key factors at constant pin height (l = 25 mm) and pin diameter (d = 10 mm) values. The results confirm the existence of optimum fin spacing providing maximum heat transfer enhancement. The investigation is extended further to quantify the effects of the presence of cylindrical porous pins with the uniform diameter (dp = 15 mm), pin length (lp = 20 mm) and calculated porosity of 19.3% by volume on the thermal performance of the system. The results reveal the improved system performance due to the presence of a porous medium for all tested system configurations. Some new empirical correlations predicting system performance are also proposed those demonstrate the satisfactory qualitative behavior of system performance.

Optimization of Fin Spacing of Vertical Plate Fin Heat Sink in Natural Convection

Heat sinks are frequently used in the cooling of electrical and electronics devices If the heat sink have very close fin spacing, it increases the surface area but reduces the heat transfer coefficient. On the other hand, if heat sink has wide fin spacing, it reduces the surface area but increases the heat transfer coefficient. Therefore, there is need to optimize the fin spacing that enhanced the heat transfer from the heat sink. A properly selected heat sink may reduced the operating temperature and reduce the risk of failure of components. A steady state natural convective heat transfer from aluminum plate fin heat sink was examined experimentally. The length and thickness of fin was kept constant while height were varied from 5mm to 25mm and spacing varied between 5.5mm to 17mm.After experimentation, it was observed that fin spacing plays important role than any other geometrical parameters. Response surface methodology is used for optimization of fin spacing. It is observed that optimum fin spacing of heat sink is 8.28mm.The error analysis is done with the help of ANN and flow visualization were done using CFD

A Review On Rectangular Heat Sinks Under Natural Convection

In the paper review of studies of heat sinks under natural convection is taken up. The discussions are mainly on experimental works carried out on rectangular fin arrays, optimization of heat sink dimensions and heat transfer enhancement. The geometries of heat sinks, fin spacing, fin height, fin length, fin thickness and fin material and base to ambient temperature difference are the important parameters on which heat transfer rate depends. So the design and optimization of the heat sink geometries becomes essential. It was found that the optimum fin spacing is ranging from 6.1- 11.9mm which gives maximum heat dissipation; the base to ambient temperature difference is 20-1500C. During most of the experimental work carried out a good thermal conductivity material which is cost-effective was chosen.

Investigation of Fin Spacing for Heat Transfer Enhancement in Cross Flow Over Tubes Between Two Parallel Plates

This research explains the investigation of fin spacing for heat transfer enhancement in the finned tube heat exchanger. The objective of this paper is to recommend the optimum fin spacing for heat transfer enhancement. Three different types of tube and spacing are identified through the simulation from Ansys software. The data between simulation using Ansys Fluent and published literature were being compared. Graph of total pressure, Nusselt number and total temperature have been plotted to make the comparison. Result obtained showed that were a bigger agreement between the simulation and published literature for both types of the tube which are circular and elliptic. From the analysis, there were considered two types of arrangement for the different types of tube. From that, the aligned arrangement is the best for heat transfer enhancement compared to the staggered. For the effect of spacing, there was three spacing which is 1.7 mm, 1.8 mm, and 2.0 mm spacing with velocity and the total heat flux is set to be constant (v =1.4 m/s; q = 500 W/m2). For the circular tube, it can be seen that the wider of the fin spacing gave the best heat transfer enhancement in the heat exchanger. Different from the circular which is 1.8 mm spacing is the best for heat transfer enhancement. Other types of tube are a flat surface which is comparing with the variations of Nu vs Re with different heat flux. Then, the result showed that as the Re is increased the Nu will also increase. In the other side, it is recommended for future work to do the real model dimension followed to import to the Ansys instead of assuming the model is symmetrical.