Longitudinal Rectangular Fins Research Articles

Numerical and Dynamic Features for Heat Transfer Through a Longitudinal Rectangular Fin with Temperature-Dependent Thermal Conductivity

In the work reported herein, we adopt a Newton-Richtmeyer iterative scheme to arrive at solutions describing heat transfer in a longitudinal rectangular fin. Both the thermal conductivity and heat transfer coefficients are assumed to be temperature dependent and the governing partial differential equation highly nonlinear. In order to validate the numerical formulation, we consider some analytical results for this class of problems at steady state .Comparisons show convergence to exact solutions as demonstrated by local and global error indicators. In addition,various fin parameters which play a key role for efficient fin operation and design are investigated by carrying out a comprehensive dynamical qualitative study.

Enhancing the Thermal Performance of a Central Tower Tubular Solar Receiver With Direct Steam Generation by Using Internal Fins and Thicknesses Variation

Abstract This study provides a comprehensive analysis of the thermal behavior of tubular solar receivers used for direct steam generation, focusing on the effects of different wall thicknesses and longitudinal rectangular fins on the internal surface. The study evaluated six tubes, including two tubes with distinct wall thicknesses (5 mm and 3 mm) without fins and four tubes with fins but varying configurations. These tubes represent external tubular receivers used in solar central tower plants and operate at 4.5 MPa with a nonuniform solar flux averaging 0.8 MW/m2. Adding longitudinal fins to the tubes significantly reduced the maximum temperature on the irradiated surface and improved heat transfer to the fluid. The study concluded that the 45F5 receiver, which has three fins on the internal section, outperforms the other receivers, presenting a higher vapor generation. Furthermore, the 45F5 geometry enhances heat transfer, allowing the lowest maximum Biot number. These results are crucial for designing tubular solar receivers with direct steam generation systems and improving their efficiency in generating energy from renewable sources.

Thermal performance of a longitudinal fin under the influence of magnetic field using Sumudu transform method with pade approximant (STM‐PA)

AbstractTemperature distribution, and efficiency of a rectangular profiled longitudinal fin are examined in this investigation with the impact of the magnetic field. By exploiting appropriate non‐dimensional terms, the heat transfer equation incorporating temperature‐dependent thermal conductivity, heat transfer coefficient, and Maxwell expression for the effect of the magnetic field yield a dimensionless nonlinear ordinary differential equation (ODE) with corresponding boundary conditions (BCs). Sumudu transform method with Pade approximant (STM‐PA) has been employed to obtain an analytical solution for the temperature profile of a longitudinal rectangular fin subjected to a uniform magnetic field under multi‐boiling heat transfer. The STM‐PA results are compared to the Runge‐Kutta Fehlberg's fourth‐fifth (RKF‐45) order technique for computational verification and are observed to be in good accordance. The behavior of dimensionless temperature profile has been explicated graphically for diverse values of non‐dimensional parameters such as thermal conductivity parameter, Hartmann number, and thermogeometric parameter. The results of this study show that as the thermal conductivity parameter enriches, the temperature profile of the longitudinal fin improves, whereas it declines for the Hartmann number and thermogeometric parameter. Under multi‐boiling heat transference, fin efficiency varies significantly depending on the impact of pertinent variables.

A Review on Heat Transfer Enhancement of Phase Change Materials Using Fin Tubes

Latent heat thermal energy storage (LHTES) has received more and more attention in the thermal energy storage field due to the large heat storage density and nearly constant temperature during phase change process. However, the low thermal conductivity of phase change material (PCM) leads to poor performance of the LHTES system. In this paper, the research about heat transfer enhancement of PCM using fin tubes is summarized. Different kinds of fins, such as rectangular fin, annular fin, spiral fin, etc., are discussed and compared based on the shape of the fins. It is found that the longitudinal rectangular fins have excellent heat transfer performance and are easy to manufacture. The effect of fins on heat transfer enhancement is closely related to the number of fins and its geometric parameters.

Structure Optimization of Longitudinal Rectangular Fins to Improve the Melting Performance of Phase Change Materials through Genetic Algorithm

In this paper, the structural parameters of longitudinal rectangular fins used in a horizontal shell-and-tube latent heat storage unit (LHSU) are optimized to increase the melting rate of phase-change materials. The influence of natural convection on the melting process is considered. Due to the extremely nonlinear and expensive computational cost of the phase-change heat-transfer-optimization problem, a new coupling algorithm between genetic algorithm and computational fluid dynamics is developed. The effects of the thermal conductivity of fins; the filling rate of fins; and the number of fins on the optimal structure parameters, including the length, width, and position of each fin, are discussed. The results show that when a single fin is inserted in the half-ring region, the optimal dimensionless fin angle is about 0.2, and the optimal dimensionless fin length is about 0.96. The use of optimal single fin can shorten the dimensionless total melting time by 68% compared with the case of no fin, and 61.3% compared with uniformly arranged single fin. When the number of fins exceeds one, each fin should have a specific length (L), thickness (∆), and position (ψ) instead of uniform distribution. The advantage of the optimized fins decreases as the number of fins increases. When the number of fins is four, the optimized fin distribution is almost uniform, and the dimensionless total melting time is only 15.9% less than that of the absolutely uniform fin. The number of fins is a more sensitive parameter affecting the optimal position and structure of fins than the filling rate and thermal conductivity of fins.

Analysis study of nano fluids and longitudinal fins on the heat transfer in the counter flow double pipe heat exchanger

In this paper, the heat transfer enhancement in a counter-flow double pipe heat exchanger with longitudinal rectangular fins on the outer surface of the inner tube was numerically investigated by ANSYS 20.R1 software using CFD package and finite volume method. Hot water flows in the inner tube at 60℃ while cold water flows in the outer tube at 25℃. The flow is laminar with five mass flow rates from 0.012kg/s to 0.02kg/s) for hot side and from 0.01kg/s to 0.03kg/s for cold side. Two types of nanoparticles Al₂O₃ and SiO₂ have been added to produce nanofluids as heat transfer fluid in the external channel (cold fluid flow) with four different concentrations from 0.04% to 1%. Results showed, as the concentration of Nanofluids increased, the heat transfer rate also increased. At 1% concentration, the maximum heat transfer coefficient was belonged to Al₂O₃/water nanofluid by 22.3% enhancement in comparison with distilled water, while the SiO₂/water nanofluid has enhancement of 19% in heat transfer coefficient in comparison with the distilled water. Both nanofluids show higher pressure drop compared with distilled water where the SiO₂/water nanofluid gives a higher drop of (33.2%), while the Al₂O₃/water nanofluid has (32.1%) of the pressure drop.

Exploration of Temperature Distribution through a Longitudinal Rectangular Fin with Linear and Exponential Temperature-Dependent Thermal Conductivity Using DTM-Pade Approximant

The present study elaborates on the thermal distribution and efficiency of a longitudinal rectangular fin with exponentially varying temperature-dependent thermal conductivity and heat transfer coefficient concerning internal heat generation. Also, the thermal distribution of a fin is comparatively studied for both exponentially varying temperature-dependent thermal conductivity and linearly varying temperature-dependent thermal conductivity. Further, the thermal distribution of a longitudinal fin is examined by using ANSYS software with different fin materials. Many physical mechanisms can be explained by ordinary differential equations (ODEs) with symmetrical behavior, the significance of which varies based on the perspective. The governing equation of the considered problem is reduced to a non-linear ODE with the assistance of dimensionless terms. The resultant equation is solved analytically using the DTM-Pade approximant and is also solved numerically using Runge-Kutta Fehlberg’s fourth-fifth (RKF-45) order method. The features of dimensionless parameters influencing the fin efficiency and temperature profile are discussed through graphical representation for exponentially and linearly varying temperature-dependent thermal conductivity. This study ensures that the temperature field enhances for the higher magnitude of thermal conductivity parameter, whereas it diminishes for diverse values of the thermo-geometric parameter. Also, greater values of heat generation and heat transfer parameters enhance the temperature profile. Highlight: Thermal distribution through a rectangular profiled straight fin is examined. Linear and non-linear thermal properties are considered. The combined impact of conduction, convection, and internal heat generation is taken for modeling the energy equation of the fin. Thermal simulation is performed for Aluminum Alloy 6061 (AA 6061) and Cast Iron using ANSYS.

Experimental Enhancement of Mixed Convection Heat transfer in Hot Base Rectangular Channel

This paper presents an experimental study to enhance the flow and heat transfer enhancement over horizontal and orientation channel with hot base by laminar mixed convection heat transfer. The hot base is fitted with the longitudinal rectangular fin arrays as a finned wall. The study covered the following range: modified Grashof number varied (3× 101 - 8× 108), Reynolds number in range 1800-2300, and Pyrantel number 0.71. The bottom finned wall of the channel was supplied with constant heat flux, while the other sides are insulated. The experiment part includes a suitable test rig that was built to get accurate decisions. A good mechanism was created to get the orientation angles at (90°,120°, 150 °and 180°) then to analysis this effect on heat transfer for laminar flow force convection. Three different cases are investigated: the effect of modified Grashof number and orientation angles on fluid particles flow and heat removal will be an enhancement. The experiment results show that the average heat transfer coefficient increased with Reynolds number and an increase of the Grashof number for all orientation angles due to increases buoyancy forces, thus causes a detach with the secondary layer flow. The average heat transfer coefficient and fins effectiveness are enhanced to 25% at highest longitudinal orientation angles.

Performance analysis and optimization of rectangular fin arrays used in plate-fin heat exchangers

This paper deals with longitudinal rectangular fin arrays used in plate-fin heat exchangers. The temperature distribution and rate of heat transfer were obtained using 1-D and 2-D solutions. The ranges of independent parameters within which the 1-D solution was within 1% from the 2-D solution were determined. Simple analytical solutions were determined for the rate of heat transfer, fin effectiveness, and augmentation factor. The aspect ratio at which the rate of heat transfer reached a maximum was determined, as well as the corresponding effectiveness and augmentation factor.

An experimental simulation of free convection heat performance for rectangular-fins array inside an enclosure: the direction and inclination effect

In this paper, an experimental simulation has been performed to predict the thermal performance of free heat convective from a heated longitudinal rectangular-fins array to ambient air in an open ended wooden enclosure. Three various directions of fins array named front, top and bottom. Also, two inclinations of front direction fins array are 30° and 60° are utilized. Fins array is heated from a base plate. Wide ranges of power input magnitudes to the fins array base have been employed. The effect of fins array direction, inclination angle of fins array, heat flux and surface temperature on the thermal performance of free convective have been investigated and analyzed experimentally. The present data refers to the front direction fins array gave best thermal performance in term of Nusselt number about 6% to 10% and 22% to 27% larger than top and bottom directions respectively. Three empirical correlation equations to speculate Nusselt number values for the front, top and bottom directions rectangular-fins array are suggested. The results are compared than last researches and well proximities in behaviors is observed.

A Uniquely Finned Tube Heat Exchanger Design of a Condenser for Heavy-Duty Air Conditioning Systems

This study introduces the design of a novel condenser for air conditioning systems. Enhancement of performance of the system was manifested by increasing the coefficient of performance (COP), decreasing the pressure drop and the power consumed by the refrigerant compressor and the cooling water pump. The design consists of an adiabatic double-pipe heat exchanger with longitudinal rectangular fins. This model can enhance heat transfer coefficient and expose more area per unit length. This novel design supersedes other conventional condenser designs by 4.7% higher COP, 8.2% lower water pressure drop, 4.68% lower compressor power. Two refrigerants have been examined in the study; R-134a which is used in commercial and industrial chillers and R-1234ze which has low global warming potential.

Thermal management of high concentrator solar cell using new designs of stepwise varying width microchannel cooling scheme

High concentrator photovoltaic (HCPV) system are generally exposed to high solar concentration ratios and reach high temperatures. An advanced cooling technique is compulsory to attain the highest net output power along with the safe operation of the system components. Different designs of stepwise varying width microchannel heat sink are investigated in this study. The main purpose of this study is to investigate the influence of the channel geometry of longitudinal rectangular internal fins and different water inlet mass flow rates on the performance of an HCPV system. A three-dimensional thermal model is developed and used to compare the performance of four different designs of stepwise varying width microchannel heat sinks. These designs are compared with the conventional multichannel heat sink design. The results show that the heat sink design and the coolant mass flow rate have a significant impact on the cell temperature, electrical cell efficiency, system thermal efficiency, electrical exergy efficiency, thermal exergy efficiency, total exergy efficiency and thermal resistance of the heat sinks. For instance, using one of the proposed stepwise varying width microchannel heat sink at solar concentration ratio of 1000 suns and increasing the coolant flowrate from 25 to 1000 g/min decreased the solar cell temperature from around 71.7° C to 40° C with solar cell temperature non-uniformity decreased from 15.5 °C to 9 °C respectively.

Simulation of the effectiveness of longitudinal rectangular fins on the efficiency of the double pipe heat exchanger

In this article, a mathematical simulation of a double pipe heat exchanger is carried out, having the longitudinal rectangular fins with the dimension of (2*3*1000) mm, mounted on the outer surface of the inner tube of the heat exchanger. In this paper, the advantage of using of that type of fins and its effect on the effectiveness of the heat exchanger are studied with the help of the computer program. The carried out research allowsmaking the calculation to find the optimum design parameters of heat exchangers. The outer tube diameter is (34.1mm) while the inner tube diameter is (16.05mm). The tubes wall thickness is (1.5mm) and the model length was (1 m). The hot water is flowing through the inner tube in parallel with the cold water that passing the outer tube. The hot and cold water temperature at the inlet is (75°C & 30°C) respectively. The mass flow rate inside the central pipe is (0.1 kg/s) while the annular pipe carrying (0.3 kg/s). In the present work, the program ANSYS Workbench 15.0 was used to find out the results of heat transfer as well as the behavior of liquids inside the heat exchangers.

Numerical Investigation of Forced Convection Heat Transfer from Longitudinal Perforated Fins in a Horizontal Rectangular Channel

The present paper reports a numerical study to investigate the heat transfer enhancement over horizontal channel with longitudinal rectangular fin arrays by laminar forced convection heat transfer. Fins are perforated with two types of holes, square and circular with different diameters. Three-dimensional steady-state continuity, momentum and energy equations along with the Boussinesq approximation were solved by finite volume method with commercial available software ANSYS FLUENT 15.1. The bottom finned wall of the channel was supplied with constant heat flux, while the other sides are insulated. Data used in performance analysis were obtained numerically for fin arrays of material aluminum, by varying geometry, diameter and number of perforation (12, 16 and 20) mm, (10-22) respectively. In addition at different channel inclinations ( 150?> , 1590?> and 15 180?> ), as well as by varying Reynolds number from 1800 to 2300, at modified Grashof number Gr * 5 15?108> . The results show that the Reynolds number and size perforation have a larger impact on average heat transfer coefficients for the both type of Perforations. Also the channel inclination increases the removal heat from the channel. Keywords: Force convection, heat transfer, perforated fin arrays, square holes, notch fins, ordination angle. DOI : 10.7176/JNSR/9-16-05 Publication date : August 31 st 2019

Natural-Convection Phenomenon from a Finned Heated Vertical Tube: Experimental Analysis

In this work, an experimental analysis is made to predict the thermal performance of the natural-convection phenomenon from a heated vertical externally finned-tube to surrounding air through an open-ended enclosure. Two different configurations of longitudinal rectangular fin namely, continuous and interrupted are utilized with constant thickness, different numbers, and different heights are extended radially on the outer surface of a heated tube. The tube is heated electrically from inner surface with five varied power input magnitudes. The effect of fins configuration, fins number, fins height, and heat flux of the inner tube surface on the thermal performance of natural convection have been studied and analyzed experimentally. Obtained results show that the tube with twelve interrupted longitudinal fins gives the best natural-convection thermal performance in terms of average Nusselt number, about 20% greater than that for the tube with continuous fins. Experimental correlations to predict the average Nusselt number for the heated tubes with continuous and interrupted longitudinal fins are proposed. The present data are compared to previous study and good convergence is noticed.

Thermal Analysis of Longitudinal Fin with Temperature-Dependent Properties and Internal heat Generation by a Novel Intelligent Computational Approach Using Optimized Chebyshev Polynomials

Abstract In this work, heat transfer in a longitudinal rectangular fin with temperature-dependent thermal properties and internal heat generation is studied and more accurate results obtained in respect of the previous investigations. The advanced heat transfer models have been used to study the effects of thermo-geometric parameters, coefficient of heat transfer and thermal conductivity parameters on the temperature distribution, heat transfer and thermal performance of the longitudinal rectangular fin. It is applied a novel intelligent computational approach for searching the solution. In order to achieve this aim, the governing equation is transformed into an equivalent problem whose boundary conditions are such that they are convenient to apply reformed version of Chebyshev polynomials of the first kind. These Chebyshev polynomials based functions construct approximate series solution with unknown weights. The mathematical formulation of optimization problem consists of an unsupervised error which is minimized by tuning weights via interior point method. The trial approximate solution is validated by imposing tolerance constrained into optimization problem.

Exact closed-form unique and dual solutions to the longitudinal fin with temperature-dependent properties and internal heat generation

In this study, heat transfer in a longitudinal rectangular fin with temperature-dependent thermal properties and internal heat generation is revisited. The advanced heat transfer models have been used to study the effects of thermo-geometric parameters, coefficient of heat transfer, and thermal conductivity parameters on the temperature distribution, heat transfer, and thermal performance of the longitudinal rectangular fin. It is shown that its governing nonlinear differential equation with proper boundary conditions is exactly solvable. With this aim, we reduce the order of the differential equation to first and then convert it into a total differential equation by multiplying by a convenient integrating factor. A full discussion and exact analytical solution in the implicit form is given for further physical interpretation and it is proved that three possible cases may occur: there is no solution to the problem, the solution is unique, or the solutions are dual, depending on the values of the parameters of the model.

Numerical investigation of the thermal performance enhancement of latent heat thermal energy storage using longitudinal rectangular fins and flat micro-heat pipe arrays

The performance of a new type of latent heat thermal energy storage (LHTS) device based on flat micro-heat pipe arrays (FMHPAs) with longitudinal rectangular fins is numerically studied by enthalpy–porosity technique based on finite volume method (FVM) in this research. The numerical model is verified correct. The temperature distribution and phase transition process in different directions of the interior of a thermal storage tank and the effects of fin height, spacing, and thickness on charging power and thermal storage capacity are also analyzed numerically. Results show that phase interface is presented in U type in the horizontal direction. In the vertical direction, the phase change material (PCM) among fins melts from up to down when the fin spacing is larger than 6 mm, and the opposite occurs when the fin spacing is less than 6 mm. The thermal storage capacity of the LHTS device is reduced drastically when the fin spacing is less than 4.14 mm. For fin height, the structure of multiple rows of FMHPAs with dwarf fins is recommended because it exhibits large power and exerts a small negative effect on thermal storage capacity. Fin thickness has a minimal effect on charging power and thermal storage capacity. The study results provide optimization design guidance for LHTS devices based on FMHPAs under various application backgrounds, such as solving the contradiction between energy supply and demand in solar thermal systems and the peak load shifting of electricity in heat pump systems.

FINSTOOL: a New Universal Multi Boundary Conditions Tool for Steady and Unsteady Cases Fins Dimensioning

This paper describes a new tool developed in laboratory which is named FINSTOOL. This latter has been adopted as a powerful tool that helps the designer in fins dimensioning by focusing on the determination of temperature distribution along fins in both stationary and transient states (steady and unsteady ones). The mathematical model is based on the finite volumes’ numerical method for the three types of boundary conditions which can be applied to the fin’s four sides where 162 of the simulation cases represent the whole possible cases, that is why FINSTOOL is the first universal tool to treat fins. The present study supplies a new, powerful and convivial code to calculate temperature distribution along a longitudinal two-dimensional rectangular fin (the researcher’s case study). Further, a graphical interface has been integrated to enable easy manipulation as well as a post-processor treatment that made it possible to interpret the simulations’ results. The validation has been successfully accomplished in determining temperature distribution along a rectangular two-dimensional fin by considering both stationary and transient cases

Optimum Dimensions of Longitudinal Rectangular Fins and Cylindrical Pin Fins with a Prescribed Tip Temperature

ABSTRACTThis paper deals with constant-area, longitudinal fins with rectangular and circular cross-sections for the condition of prescribed tip temperature. For these fin geometries, the optimum aspect ratios for maximum heat transfer per unit volume have been determined analytically in the literature for the cases of adiabatic tip and convective tip using a one-dimensional analysis. For the case of prescribed tip temperature, a numerical two-dimensional analysis was reported for rectangular fins. In the present study, the temperature distribution and rates of heat transfer at the base and tip of both fin cross-sections were determined using one– and two-dimensional analyses. The ranges of independent parameters within which the one-dimensional solution was within 1% from the two-dimensional solution were determined, and simple analytical formulae for the optimum aspect ratios were derived based on the one-dimensional solution. An example is given showing the application of the results in design.