Fin Arrangement Research Articles

Experimental study on fast quenching of cryogenic LN2 flow through interior micro-fin tube

Future cryogenic vehicle requires a fast propellant fueling as well as a rapid pipeline quenching operation. In the present study, a novel interior micro-fin tube concept, with a series of cyclic fins arranged along the flow direction and has the size of 1 mm in both of fin height and fin width, is proposed to reach the purpose of cryogenic quenching acceleration. A cryogenic quenching test platform is established to evaluate the micro-fin effect. A straight tube and three micro-fin tubes, with fin intervals of 50, 100, and 200 mm, are fabricated and tested under different inlet Reynolds numbers (Re) conditions. The tube quenching cases covering inlet flow rate range of Re = 5000–45,000 are performed, and the results on temperature decrease, heat flux, and pressure drop are analyzed and compared. The test results demonstrate that the proposed micro-fin tube significantly reduces time cost in quenching process, and about 33–62% of time savings are reached for different Re conditions. The mechanism of micro-fin tube in facilitating quenching progress is that a radial velocity component within the annular vapor film could be induced by the micro-fin structure. This radial velocity acts on the liquid-vapor interface directly, which motivates interface fluctuation or tears the interface, and finally brings about an earlier liquid-wall contact at higher wall temperature. Moreover, it shows high heat flux appears immediately at the beginning of the quenching operation, and an approximately linear temperature decrease is experienced throughout the entire process. In addition, changing fin interval could affect the quenching rate under low Re conditions, but the fin interval influence decreases with the increase of Re. The test results show that the fin interval has slight influence on time cost when Re = 30,000. For a high-Re quenching event, a micro-fin tube with large fin interval could be suggested in the view of balancing consideration on heat transfer enhancement and flow resistance reduction. Compared to the surface treatment approaches, the proposed micro-fin structure tube provides a competitive approach in accelerating the quenching progress, and more work should be performed to optimize the micro-fin structure and the fin arrangement.

Evaluation of thermal, electrical and overall efficiency of an air-cooled solar panel equipped with hexagonal pin-fins

In the present paper, a 5-W solar panel is cooled using airflow due to the importance and wide application of solar panels. A number of hexagonal pin-fins with two different arrangements are installed under the panel. The airflow enters a channel in the range of 1–3 m/s and cools the panel in a turbulent flow regime. The numerical method is employed for solving the governing equations. The airflow is turbulent and the standard k-ε turbulence model is selected. Finally, the maximum temperature of the panel, as well as, the electrical, thermal, and overall efficiency of the panel is presented at different air velocities for two pin–fin arrangements. The findings of this study show that growing the air velocity decreases the maximum temperature of the solar panel, resulting in an enhancement of the electrical efficiency of the panel. Moreover, augmenting the air velocity enhances the thermal and overall efficiency of the panel. The better pin–fin arrangement is also introduced based on lower maximum temperature and higher overall efficiency. Finally, it is understood that the maximum amount of electrical, thermal, and overall efficiency occurs at a velocity of 3 m/s, which are 13.1%, 60.8%, and 74%, respectively.

Effect of Wavy Fins on Thermal Performance of Double Pass Solar Air Heater

In this paper, experimental study on double pass solar air heater with wavy fins absorber has been investigated. The fins attached to the upper and lower surfaces of the absorber. Two wavy fins arrangement (3 and 7 fins) have been investigated with plan absorber by changing solar radiation intensity (500, 600, 700 and 800 W/m2), air mass flow rate form 0.008575 kg/s to 0.0214375 kg/s. The results of wavy finned absorbers are compared with plane and the improving in thermal efficiency reached 80% and 84% in 3 and 7 wavy fins absorbers respectively.

Heat transfer and pressure drop in turbulent nanofluid flow in a pin-fin heat sink: Fin and nanoparticles shape effects

In this paper, the turbulent flow of a nanofluid in a channel is simulated in the presence of a pin-fin heatsink. Pin fins have different shapes, including hexagonal, circular, square, and triangular that are considered in two different arrangements. Constant heat flux is applied to the heatsink from its bottom due to the operation of an electronic chip. The nanoparticles suspended in water are alumina, which are in different shapes such as blades, bricks, cylinders, and plates. Their shape effect is investigated. The nanofluid enters the channel at a constant velocity in the range of 1–3 m/s and a constant volume percentage of 2%, and exits after cooling the pin-fin heatsink. The standard k-ε turbulence model is used to model turbulent flow, and the SIMPLEC method is employed to linearize the equations. The variables include fin type, fin arrangement, nanoparticle shape, and nanofluid velocity. Their effect on the maximum and average heatsink temperature and pressure drop (ΔP) is studied. The results show that increasing the velocity leads to a reduction in heatsink temperature, and the use of brick-shaped nanoparticles and circular fin results in the best cooling performance. Also, the use of circular fin and brick nanoparticles requires less ΔP than other cases.

Heat Transfer Enhancement for On-Chip Cooling Application Using Novel Composite Heat Sink—Comparative Numerical Study

This study investigates the enhancement of thermal performance of a composite heat sink (CHS). The novelty is that instead of embedding a conventional heat pipe at the bottom of base plate of the heat sink, a series of microheat pipes (MHPs) are embedded above, in such a manner that it replaces the solid fin arrangement. With this novel idea, the comparison of thermal performance of novel CHS with embedded MHP and micro-oscillating heat pipe (MOHP) is carried computationally using ANSYS-FLUENT-2019R1. The parametric study is carried out by varying the heat input in evaporator section and the convective condition in condenser section in accordance with the single fin of heat sink, and additionally different fill ratios in both MHP and MOHP are also considered. The thermal resistance modeling is used to calculate the effective total thermal resistance of the novel CHS using the volume averaged properties. The average temperature variation in single MOHP is found to be more which results in better performance than single MHP. The lowest thermal resistance of single MOHP is 0.827 K/W and single MHP is 0.969 K/W for 3.2-W distributed heat input and 35-W/ m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ·K convective condition. The total thermal resistance of novel CHS is more efficient than the conventional heat sink with solid fins by an average of 64.7% and 72.3% for MHP and MOHP, respectively, at considered maximum convective condition. Finally, the thermal resistance of novel CHS with MHP or MOHP is compared with the previously investigated CHS which seems to have enhanced heat transfer.

Field synergy analysis for heat and mass transfer characteristics in adsorption-based desalination and cooling systems

Adsorption-based desalination and cooling system has gained particular interests for low-grade heat harvesting. In this study, field synergy analysis is conducted to illustrate the complicated heat and mass transfer characteristics in an adsorption-based desalination and cooling system with finned-flat beds via a dynamical three-dimensional computational fluid dynamics model. Two field synergy angles α and β reflecting the synergy effect of heat transfer and flow resistance with the adsorption driving force are examined. Results illustrate that smaller α and β result in better adsorption performance. Furthermore, guided by the field synergy analysis, adsorbent bed configurations (fin diameter, fin pitch, fin shape, and fin arrangement) are optimized. The fork-row arrangement results in a higher SCP and SDWP than that of the in-line arrangement. With the fin pitch of 20 mm and fin diameter of 12 mm, the system with fork-row arrangement demonstrates a SCP of 0.363 kW/kg and SDWP of 12.5 m3 per ton silica gel per day, which is 6.6% higher than that of the in-line arrangement as the field synergy parameter between heat transfer and the driving force factor (α) is more predominant at a relatively smaller fin pitch.

Effects of fin parameters on performance of latent heat thermal energy storage systems: A comprehensive review

Due to the low thermal conductivity of the available phase change materials (PCM), fins are usually incorporated into latent heat thermal energy storage (LHTES) systems. Although many different fin configurations have been proposed and investigated, each assessment is performed with its unique assumptions and limitations. Therefore, the objective of the present paper is to provide a comprehensive review of various fin designs proposed for LHTES systems and critically discuss the effects of different geometrical parameters such as fin length, number, thickness, spacing, angle, and shape. The interaction between other design parameters (such as enclosure geometry and fluid flow rate and temperature) and fin configurations are also discussed. It is shown that an optimum number of fins, spacing, and length can be found in each case, while some parameters such as fin thickness are less important. However, the relationship between various design parameters is complicated, and finding an optimum fin arrangement for a wide range of operating conditions is a difficult task. Moreover, the superiority of different fin configurations cannot be addressed unless the operating and initial conditions are identical.

Superhydrophobic fins with inclined arrangement for enhancing energy saving of air-cooled wet heat exchangers

The energy consumption of the air-cooled heat exchangers such as evaporators operating under wet conditions is much higher owing to the condensate retention and bridging. The retained condensates and condensate bridging could narrow down the free airflow passage in the fin side and can adversely increase the airside pressure drop, which raises the fan power consumption. Effective condensate drainage can minimize the fan power consumption in such thermal management systems. Accordingly, this work proposes a superhydrophobic heat exchanger with an inclined fin arrangement that can effectively remove condensates and minimize the airside pressure drop. In this work, the departure droplet diameter of the untreated and superhydrophobic surfaces is predicted using the force balance analysis. A rationally based correlation is proposed to describe the condensate shedding ability of the different fin surfaces through dimensionless analysis. It is found that the departure droplet diameter of the superhydrophobic surfaces is almost 90% smaller than that of the untreated surfaces. The superhydrophobic fins offered remarkable condensate shedding characteristics. Consequently, the superhydrophobic heat exchangers with inclined fins provided a pressure drop reduction of up to 70%. The effect of inclination angle and the superhydrophobic coating on the heat transfer rate is negligible.

The influence of multiple fins arrangement cases on heat sink efficiency of MHD MWCNT-water nanofluid within tilted T-shaped cavity packed with trapezoidal fins considering thermal emission impact

This paper explores numerically the MHD heat transfer of MWCNT nanoliquid inside a T-shaped cavity fitted with trapezoidal equidistant fins under thermal radiation effects. The simulation model is done with the help of the program Comsol Multiphysics. The function of several parameters is investigated, including Rayleigh and Hartmann quantities, as well as emission factors and trapezoidal fins height. In addition, for various cavity tilt angle, the influence of various fin arrangement cases on heat transfer efficiency is addressed. The important findings show that increasing the number of Rayleigh, as well as the radiation parameter, improves the flow of convection heat flow. The influence of Lorentz powers on weakening convective heat exchange is reduced when the impact of thermal emission is present. Moreover, rising the height of the trapezoidal fins increases the convective flow. Among the various trapezoidal fins arrangements, the average Nusselt limit is obtained with case 4 in the case of horizontal cavity γ = 0°. On the other hand, depending on the cavity tilt angles, the best trapezoidal fins arrangements for the most efficient heat transfer changes.

Optimization of fins arrangements for the square light emitting diode (LED) cooling through nanofluid-filled microchannel

In current paper, a finned micro-channel is designed for the cooling application in Light Emitting Diode (LED), numerically using Galerkin weighted residual Finite Element Method (GFEM). Selected materials for LED-chip is GaN, Die from Si, Die-attach is made by Au-20Sn, substrate is copper and heat sink material is considered to be Al. To make a convection heat transfer for cooling process, Al2O3-water nanofluid is used as the cooling fluid flow through the micro-channel and tried to maximize the heat transfer efficiency by optimized geometry. For this aim, there geometry variables from the microchannel were selected and minimum possible geometry cases (11 cases) were proposed by Central composite design (CCD) and variables were optimized by the Response Surface Method (RSM). As a main result, parameter B, i.e. fin length had the most effect on the Nusselt number and Al2O3 nanoparticles with φ = 0.05 stated greatest heat transfer value. Also, different designs of fins arrangements, caused up to 6.5% increase in the nanofluid temperature which enhanced the LED cooling process.

Solidification performance of new trapezoidal longitudinal fins in latent heat thermal energy storage

In order to improve the solidification performance of latent heat thermal energy storage system, a new trapezoidal longitudinal outer fin distributed by Fibonacci sequence is proposed due to the low thermal conductivity of phase change material. Firstly, the solidification behavior (temperature distribution, solid fraction, and solidification time) of three trapezoidal fins and traditional quadrilateral fin are compared by numerical simulation. The fin design with the highest improvement in solidification performance is selected and the dynamic temperature analysis is carried out. The Fibonacci sequence is introduced into the fin distribution and the effect of different longitudinal fin arrangements on solidification performance is analyzed. In addition, Response surface method is used to investigate the influence of geometric parameters of the trapezoidal fin based on Fibonacci sequence arrangement, and the optimal structure is obtained after optimization. The results show that the solidification time of phase change material after using modified trapezoidal fin with Fibonacci sequence is shortened by 45.28% compared with the traditional quadrilateral fin. Finally, the temperature difference between the inner tube cold fluid and the phase change material is greater than 20 K, which can ensure the excellent solidification performance.

Numerical investigation on the influence of installation angle of inclined interrupted fins heat sink on heat dissipation performance

Numerical simulations of a symmetric array of inclined fins heat sink under natural convection had been carried out using the ANSYS icepak to solve the complete Navier-Stokes equation and the energy equation in the current study. The effects of fin height (20 mm ≤ H ≤ 40 mm) and heat sink installation angle (–45° ≤ φ ≤ 30°) were analyzed. The work fluid was the air. The results showed that when the input power was constant, as the fin height increased, the heat transfer performance improved. There was no better heat transfer performance than the case of fin height was 40 mm, of which the corresponding heat transfer resistance was also almost the lowest. Compared with H = 20 mm and H = 30 mm, the case of H = 40 mm can reduce the average substrate temperature by 5%−10%. The installation angle greatly affected the heat transfer performance of the heat sink. Compared with the negative installation angle, the positive installation angle showed stronger inhibition on the heat dissipation. The installation angle of −15° showed the highest heat transfer coefficient, which could improve the heat transfer coefficient by about 7%. The Nusselt number (Nu) was found to increase approximately linearly with the Rayleigh number (Ra) in the range of 8.5 × 106 ∼ 1.64 × 107. A correlation between Nu and Ra, the geometric parameters of fin arrangement and the dimensionless correlations related to the heat sink installation angle were obtained. Highlights A new type of fin heat sink was proposed to improve heat sink performance. The heat sink installation angles was studied with the best angle found. The correlation formula related to the installation angle was obtained.

Experimental evaluation of used engine oil based thermal energy storage coupled with novel evacuated tube solar air collector (NETAC)

The significant challenge in vacuum tube solar air collector is worse performance after sunset which prompts the thermal energy storage. In present manuscript, the used engine oil based thermal energy storage coupled with novel evacuated tube solar air collector (NETAC) is developed. The NETAC investigation is evaluated during winter season for hot air production for 13 h at diverse air flow rates and different directions of air flow (parallel air flow & counter air flow). The maximal temperature difference (24.8 oC) of air is obtained at low air flow rate (79.5 Kg/h) and maximal mean efficiency (28.8%) of NETAC at high air flow rate (159 Kg/h) with circular fin and counter flow arrangement. The maximal mean energy efficiency (27.15%) and exergy efficiency (24.8%) of the oil thermal storage tank is attained at high air flow rate (159 Kg/h) with circular fin and parallel flow arrangement. The maximal mean energy gain (538.7 W) by air is obtained at high air flow rate (159 Kg/h) with circular fin and parallel flow arrangement.

Effects of Fin Arrangements on Thermal Hydraulic Performance of Supercritical Nitrogen in Printed Circuit Heat Exchanger

The printed circuit heat exchanger (PCHE) with discontinuous fins is a novel type of compact and highly efficient plate heat exchanger, which has superior thermal hydraulic performance. The morphology and characteristics of the flow channel greatly affect the performance of the PCHE. The discontinuous airfoil fins are used in PCHE channel design because they can affect the flow and heat transfer by increasing the heat transfer area and the disturbance in the channel. In this paper, the effects of different staggered distance (Ls) and transverse distance (Lv) of airfoil fin arrangements on the heat transfer and flow of supercritical nitrogen in the PCHE are numerically simulated using ANSYS Fluent. Simulation results and subsequent analysis show that the appropriate decrease in Ls and reduction in Lv between the two rows of fins can improve the convective heat transfer of the PCHE. A fully staggered arrangement of fins (Ls = 1.2) and an appropriate increase in the Lv can mitigate pressure drop. The comprehensive performance of different channel geometries is compared by the performance evaluation criteria (PEC) in this study. It is shown that considering flow resistance and heat transfer, the comprehensive heat transfer performance can be enhanced by properly increasing the staggered distance and the vertical distance between fins. When Ls = 1.2 mm and Lv = 1.25 mm, the PEC value of the staggered channel is the highest, which is 11.6% higher than that of the parallel channel on average.

Numerical optimization of a conical cavity as a radiation-focused concentrator

Conical enclosures rely on the conical cavity and can be used as radiation concentrators. Two circular cross-section baffles were used to improve the heat transfer of this geometry. By changing the rigid fins to porous, it could improve the heat transfer. Al2O3/water nanofluid was also employed to enhance the heat transfer performance of the cavity. For this purpose, numerical analysis of three-dimensional natural convection heat transfer was performed in a conical cavity with two types of fins. The best combination of fins arrangement for the next step was selected using the differential evolutionary optimization method (D.E). In this case study, a new combination of laminar and turbulence methods was employed for the first time to increase the accuracy of the natural convection solution. This combination is based on the laminar solution by suppressing the perturbation parameter in the turbulence method which led to more accurate results. The analysis results showed that a conical cavity with optimized fin geometry can lead to a 23% increase in Nu. The best porosity for the inner fin was calculated 40% in the case of constant porosity. Ascending porosity along the fin, whose increase was more intense near the base and slower near the cone's tip, was the best variable porosity for the inner fin.

Study of Thermal Behavior of a Horizontal Two Fins Annular Tube Heat Exchanger with Melting Phase Change Material: Fins Orientation Effects

This paper investigates the effect of fins orientations of a horizontal two fins annular tube heat exchanger on enhancing the heat transfer during the melting process of n-eicosane, as phase change material (PCM) used in thermal storage systems. Based on the enthalpy-porosity method, two-dimensional model is performed and solved by Ansys Fluent. The impact of the fins orientation on melting rate, thermal conduction and natural convection, as the angle of the system varied from 0º (vertical fins) to 90º (horizontal fins) are discussed. Numerical predictions are validated by comparison with experimental data and numerical results reported in the literature. Good agreements are achieved. The results show that at initial time of the melting process, the conduction heat transfer is dominant. During the melting process, the heat transfer in the horizontal fins is more effective while the upper half of PCM melts and less effective as the lower half of PCM melts because fin arrangement resists natural convection occurs. However, the effectiveness of heat transfer and convection in the vertical fins is almost constant during the entire melting process. From comparison, better heat transfer performance is achieved with vertical fins system; complete melting was reduced 250% compared to horizontal fins case.

Experimental and numerical investigations of thermal performance enhancement in a latent heat storage heat exchanger using bifurcated and straight fins

In this paper, the effects of applying straight and bifurcated fin configurations on melting behavior of paraffin inside the shell-and-tube heat exchangers are both experimentally and numerically investigated. Three different fin arrangements for each of the fin configurations were considered: (a) cross arrangement, (b) diagonal cross arrangement and (c) arranged evenly at the lower half of the heat exchanger. The evolution of the melt front was photographed to obtain the instantaneous melt fractions and gain a better insight into the effect of fin configuration on the melting process of phase change material under different Rayleigh and Stefan numbers. The impacts of fin length and thickness on the thermal performance of the heat exchangers were also investigated while the mass of fins for all cases was kept constant. It was found that the bifurcated fin configuration outperforms the straight fin configuration. Also, the fin arrangement showed a significant effect on the melting process. Numerical results revealed that the optimum fin arrangement depends on the fin length which was more pronounced when the fins located at the lower half of the annulus. For charging temperature of 95 °C (Ste = 1.08, Ra = 1.73 × 106), the maximum melting time reductions of bifurcated fin heat exchangers with dimensionless fin lengths of 0.51 and 0.89 mm, compared to those of the straight fin heat exchangers, were 19.5% for the (c)-type fin arrangement and 61.6% for the (b)-type fin arrangement, respectively.

CFD Analysis and Electrical Efficiency Improvement of a Hybrid PV/T Panel Cooled by Forced Air Circulation

Renewable energy sources are becoming more and more popular, regarding the pollution and non-sustainability of common energy sources. The study mainly focused on the improvement of the PV collector performance by using ANSYS fluent. The design of the fin will change according to the previous study. In the current study, we will increase the thermal contact area of the fin by changing the design of the fin. The change in the design of the fin will increase the total heat transfer and efficiency of the system. It concluded that with better-designed fin arrangements, the required fan speed could be lowered for any number of fins or similar results could be obtained with fewer fins. On the other hand, since the power required by the PV-powered fan will also decrease with fewer fins and at lower air velocities, the total efficiency obtained from the PV system will also increase.

Heat Transfer Enhancement of Liquid Cooled Copper Plate with Oblique Fins for Electric Vehicles Battery Thermal Management

As the automotive industry progresses, electric vehicles (EV) grow with increasing demand throughout the world. Nickel-metal hydride (NiMH) battery and lithium-ion (Li-ion) are widely used in EV due to their advantages such as impressive energy density, good power density, and low self-discharge. However, the batteries must be operated within their optimum range for safety and good thermal management to enable a longer lifespan, lower costs, and improve safety for EV batteries. The need for a liquid cold plate (LCP) to be used in EV batteries is now highly reliable on the distribution of the required temperature rather than only standard cooling systems. The fins arrangement in the LCP would likewise impact the cooling efficiency of the EV battery. The main objective of this paper is to determine the heat transfer enhancement of liquid cold plate systems with the oblique fin and different types of liquid coolants. In the experimental test, two liquid types are used namely G13 ethylene glycol and distilled water in five steps, 10% ethylene glycol, 100% distilled water, 75% ethylene glycol + 25% distilled water, 50% ethylene glycol + 50% distilled water, and 25% ethylene glycol + 75% distilled water. Three different flow rates have been utilized which are 0.3, 0.5, and 0.7 GPM to maximize the productivity of flowing fluid and heat transferring with the gate door valve. The LCP encompasses the inline configuration of the oblique fin, which is able to enhance the heat transfer rate from the heater to the liquid cold plate. A GPM of 0.7 reached the least surface temperature for the battery in the three different flow levels. The LCP is capable of sustaining the ambient surface temperatures of the batteries just under the permissible 50 °C operating temperature, which indicates that the developed LCP with the oblique fin may perhaps become an effective option for the thermal control of EV batteries.

Experimental Investigation of Heat Transfer of Concentric Triple Pipe Heat Exchanger Coupled with Blossom Fins.

The present work describes the principle techniques of industrial importance as it deals with heat transfer analysis of concentric triple pipe heat exchanger employing blossom fins. Findings indicate that the use of fin arrangement is advantageous to enhance the performance of heat exchanger, LMTD, over all heat transfer and effectiveness is found to be increased. The additional fins improve the heat transfer by providing a larger area for heat transfer area per unit length of the exchanger. The net heat transfer, overall heat transfer, efficiency and effectiveness were calculated and compared for all the flow patterns and Counter flow 3 was found to have the best results among the flow patterns with the maximum heat transfer, heat transfer coefficient, efficiency and effectiveness being 1642.09 watts, 1842.07 w/m2k, 0.57896 and 0.73 respectively.