Longitudinal Fins Research Articles

Thermal analysis of rectangular moving fins with temperature‐variant properties by employing the Galerkin scheme

AbstractIn the present study, the thermal behavior of a longitudinal fin considering three types of heat transfer mechanisms (conduction, convection, and radiation) is investigated. For this research, thermal conductivity, heat source, and heat transfer coefficient are assumed nonindependent. A semianalytical scheme called the Galerkin Method is utilized for solving the dimensionless governing equation. The impacts of important physical variables like Peclet number, gradient of thermal conductivity, thermo‐geometric parameter, and radiation–conduction parameter on temperature profiles are analyzed comprehensively. The obtained results indicate that raising the thermo‐geometric parameter from 0 to 2 leads to a 32% reduction in the temperature profile. Also from the results, it can be found that a 28% increment in the temperature is observed by changing the gradient of thermal conductivity from 0 to 2.

Ammonia single-phase and two-phase frictional pressure losses in horizontal smooth and straight inner-grooved tubes

The experimental study of single-phase and two-phase frictional pressure losses has been performed with ammonia flow in stainless steel smooth tubes (internal diameter of 5.5 mm and 8.5 mm) and six straight inner-grooved aluminium tubes with different nominal diameters (7.15 to 13.3 mm), length (0.45 to 2.0 mm) and thickness (0.35 to 0.8) of fins. Single-phase test boundary conditions correspond to Reynolds numbers of 1000 to 20,000. Two-phase tests have been carried out at saturation temperature of 45 to 65 °C, mass velocity of 50 to 210 kg·m−2s−1 and vapour quality of 0.1 to 0.9. Comparison of obtained test data with the existing frictional losses approaches shows that the Blasius model is appropriate to single-phase flows in smooth tubes, and Müller-Steinhagen and Heck's (1986) model is most accurate in predictions of two-phase frictional losses in smooth tubes. Existing approaches of single-phase frictional pressure loss predictions in the pipes and channels with longitudinal fins (Carnavos, 1980; Edwards and Jensen, 1994) are not adequately suited to the ammonia test points obtained in the considered straight inner-grooved tubes. A new semi-empirical model has been proposed, based on generalisation around the revealed geometric dimensionless factor, which accurately describes friction pressure losses in the considered inner-finned profiles. The simplest homogeneous model for defining two-phase friction pressure losses, using McAdams et al.'s (1942) recommendation for mixture dynamic viscosity definition and a new model of single-phase friction factor, best fit both quantitatively and qualitatively to ammonia two-phase test points in most of the considered straight inner-grooved tubes.

Assessing the effects of different finned absorbers with swirl flow on the performance of solar air heater

ABSTRACT In this study, the effects of various absorber configurations of a tubular solar air heater are investigated. The models such as direct flow with a standard absorber (DF-SA), swirl flow with a standard absorber (SF-SA), swirl flow with perforated longitudinal fins (SF-PLF), swirl flow with radial fins (SF-RF), swirl flow with perforated radial fins (SF-PRF) are studied. Investigation parameters including Nusselt number, exergy efficiency, PEC, and friction factor are examined with Reynolds numbers ranging from 8488 to 25,464. The findings reveal an enhancement in Nusselt number, PEC, and exergy efficiency corresponding to an increase in Reynolds numbers, while the friction factor decreases. Models employing air-swirl flow entrances demonstrate superior effects in improving the performance compared to direct flow inlets. Notably, the SF-PRF shape records the maximum Nu ratio of (102.5–108%). This model has the maximum values of PEC enhancement ratio of (103.9–106.2%) compared to DF-SA, indicating the enhancement obtained by using swirl flow with perforated ring fins. Analysis of streamlines and distributions of temperature, pressure, and velocity elucidates the effects of perforated radial fins on vortex generation and secondary flow, particularly when incorporating air swirl inlets.

Semi-analytical and numerical investigation of a fully wet porous moving longitudinal fin exposed to a magnetic field with radiation and temperature-dependent thermal conductivity

ABSTRACT This article focuses on the thermal analysis of a fractional-order moving fin subjected to a magnetic field, specifically investigating natural convection and radiation effects. This research introduces a novel approach that combines the domains of both Homotopy perturbation and Sumudu transform techniques to tackle a previously uninvestigated issue related to a moving fin with thermal conductivity dependent on temperature. While previous research papers have utilised the Homotopy Perturbation Sumudu Transform Method (HPSTM) to derive analytical solutions for fins with temperature-dependent thermal conductivity, our current study employs the HPSTM to address a fractional-order problem associated with a moving fin. Through a comparison with numerical results, the present study has validated the dependability of its findings. The dimensionless temperature profile has been investigated by studying its relationship with several parameters. We found that as the value of the wet porous parameter raises by 400%, there is an 11.794% decrease in temperature of the fin and as the value of Hartman number increases by 400%, temperature of the fin has decreased by 14.196%. Furthermore, the efficiency of the fin by analysing graphical representations across various parameters. This study encourages the application of the Homotopy perturbation Sumudu transform technique in more complex fin problems.

The optimum fin length distribution of tabular PCM heat exchanger

AbstractThe study aims to find the optimal fin length distribution for improved heat transfer during melting and solidification in a tubular phase change material (PCM) heat exchanger (HE) designed for heat storage. Three types of horizontal PCM tabular HEs, all with five longitudinal fins, were studied numerically. While maintaining a constant heat‐transfer area, each model depicts a unique fin length distribution design. The first model, which serves as the reference design, has a uniform fin length distribution and each fi\n is 30 mm long. The second model has shorter upper and side fins and longer lower fins. The third model has long lower fins but shorter than that of the second model, with short side fins and no change in upper fin length with reference design. The findings indicate that the second model exhibits the best heat‐transfer performance for the melting process, while the first model is most effective for solidification. Interestingly, the third design emerges as the optimum choice for both melting and solidification processes, where for 1 h of melting operation, results obtained 87%, 92%, and 90% for three models, respectively, from the first uniform model to the third model. While for 2 h of solidification the result obtained 11%, 17%, and 13% liquid fraction for the three models, respectively.

Development of multi-module arranged in series using U-type longitudinal fin tube in thermal energy storage system

The performance of a thermal energy storage (TES) system for commercial applications can be improved using phase change materials (PCM). This study develops a vertical multi-module from a PCM for a TES system that achieves the same effect as a single-module by arranging multiple-modules in series as a U-type longitudinal fin tube to enhance the system's performance. The U-type longitudinal fin tube is designed to enhance heat transfer within the module, and a single-module is designed for multi-module applications. The TES system is analyzed to the average heat transfer rate, overall heat transfer coefficient, quantity of heat storage/release, and utilization ratio at different heat transfer fluid (HTF) flow rates, inlet and outlet temperatures and different number of modules. Consequently, the addition of several modules improves the thermal performance, and an increase in the HTF flow rate improves the average heat transfer rate. The overall heat transfer coefficient is used to analyze the thermal characteristics of the PCM. During the heat charging and discharging processes, the average heat transfer rates are 2.4 and 2.55 kW, respectively, and the quantities of heat storage and release are 5,153.59 and 4,771.79 kJ, respectively, for three modules. The overall heat transfer coefficient of the PCM exhibits similar results with an increasing HTF flow rate; it increases marginally from 42.25 to 45.8 and 9.9–10.8 W∙m−2∙K−1 as more modules are added. Further, the results of this study confirm that the relatively low HTF flow rates in the multi-module require the addition of several modules and that increasing the HTF flow rates limits the number of modules.

Numerical analysis of stretching/shrinking fully wet trapezoidal fin

<p>The purpose of fins or extended surfaces is to increase the dissipation of heat from hot sources into their surroundings. Fins like annular fins, longitudinal fins, porous fins, and radial fins are used on the surface of equipments to enhance the rate of heat transfer. There are many applications of fins, including superheaters, refrigeration, automobile parts, combustion engines, electrical equipment, solar panels, and computer CPUs. Based on a wide range of applications, the effects of stretching/shrinking on a fully wet trapezoidal fin with internal heat generation is investigated. The shooting approach is used to calculate the trapezoidal fin's thermal profile, tip temperature, and efficiency. It is observed that with an increase in the shrinking and wet parameter, the temperature distribution decreases and efficiency increases. On the other hand, when stretching increases, the temperature distribution increases and efficiency diminishes. Using the computed results, it is concluded that shrinking trapezoidal fins improves the effectiveness and performance of the system.</p>

Semi-analytical investigation of heat transfer in a porous convective radiative moving longitudinal fin exposed to magnetic field in the presence of a shape-dependent trihybrid nanofluid

Semi-analytical investigation of heat transfer in a porous convective radiative moving longitudinal fin exposed to magnetic field in the presence of a shape-dependent trihybrid nanofluid

Numerical investigation of the process of melting and solidification within a parabolic trough solar collector using nanoparticles and fins

This study investigates the integration of heat storage and solar concentrating systems utilizing phase-change material (PCM) in a triplex tube parabolic trough solar collector (TTPTSC). The simulated system contains a middle region filled with PCM (RT82), with Syltherm 800 flowing via the inner and outer tubes. The finite volume technique was used to simulate this laminar flow with variable heat flux on the outer wall. This numerical study aims to assess the impacts of adding Alumina and Single-Walled Carbon Nano Tube (SWCNT) nanoparticles at volume fractions of 0 and 0.025, as well as the effects of fin installation, geometry, rim angles (φR), and other relevant parameters on these processes. The addition of nanomaterials in different cases led to significant reductions in melting times, ranging from 7.39% to 8.1%, compared to cases without nanoparticles. In addition, the fins in various cases improved the melting performance compared to the simple case. The melting time reductions ranged from 26.2% to 30.14%, demonstrating how fins can improve heat transfer and accelerate the melting process. The case with seven longitudinal outer fins and a rim angle of 60 had the shortest melting time among the studied configurations.

Analysis of Transient Thermal Behaviour of a Different Profiled Fully Wetted Longitudinal Porous Fin with Internal Heat Generation

The transient thermal performance of a fully wetted longitudinal permeable fin under natural convection, radiation, and internal heat generation has been studied in the present problem. Due to variation of fin thickness with respect to fin length, it is possible to obtain different fin profiles such as triangular, convex and rectangular profiles. Here, the diverse profiles of the fin have been considered for the examination and Darcy’s model was implemented to investigate the porous nature of the fin. The governed partial differential equation has been solved by applying finite difference method. The influence of dimensionless parameters on the transient thermal profile as well as the heat dissipation rate of the three types of fins, has been graphically illustrated and interpreted physically.

Heat transfer enhancement of a lithium-ion battery cell using vertical and spiral cooling fins

Lithium-ion batteries are widely regarded as the primary source of power for electric cars due to their high energy density, long lifespan, and lack of memory effect. However, their efficacy and safety greatly depend on the temperature at which they operate. Therefore, a battery thermal management system (BTMS) is crucial to ensure the safety of an electric vehicle. This research presents a model of a BTMS that employs a single cylindrical lithium-ion with longitudinal and spiral fins on the cell surface to investigate its cooling effectiveness. Effects of the fin’s number, rotation, thickness, length, and position are assessed at various current rates. The results show that the fins reduce the maximum cell temperature when compared to a finless case and become more effective at a low Reynolds number. Despite the fact that increasing the number of fins enhances the heat transfer area, when the number of fin reaches more than 3, they become a barrier to the flow around the cell and hence increase the battery temperature. The orientation of the fin also has a significantly impact on the heat transfer between the cell and air cooling, with the cell temperature rising by 1.5 °C when compared to the half-length of a longitudinal fin. However, the cooling benefit is found to be very modest when the half-fin is placed in various locations on the battery surface (i.e., top, middle, and bottom). Furthermore, compared to the longitudinal fins, the spiral fins reduce the cell temperature by 3.2%, resulting in a 65.6% reduction in material usage.

The potential of arc-shaped fins for expedited solidification in triplex-tube latent heat storage: Parametric investigation

Phase change materials (PCMs) enable efficient thermal energy storage (TES) but suffer from poor thermal response. This study introduces and optimizes a novel arc-shaped fin configuration to improve heat recovery during PCM solidification in a horizontal triplex-tube TES unit. The effects of fin base length and inter-fin angle on solidification time, temperature distribution, and heat recovery rate are systematically analyzed. An asymmetric base length of 15 mm for internal fins and 10 mm for external fins substantially expedites solidification. This is attributed to enhanced heat conduction from the larger surface area of longer internal fins and increased natural convection from reduced external fin blockage. Furthermore, compact 0° inter-fin angles create extensive fin-free zones that encourage convection. The optimized arc-shaped fins reduce solidification time by about 75 % and elevate heat recovery rate by 284 % versus no fins. They also significantly outperform conventional longitudinal fins, which only achieved 47 % faster solidification and 80 % greater heat recovery over no fins. This highlights the profoundly favorable solidification enhancement and temperature uniformity offered by properly designed arc-shaped fins.

Heat transfer in a wet porous moving inclined longitudinal fin exposed to convection and radiation in the presence of shape-dependent hybrid nanofluid: Adomian decomposition Sumudu transformation approach

This research paper investigates the thermal examination of a non-integer-ordered mobile fin situation with a hybrid nanofluid flowing past it at an unceasing speed U. The combination approach is utilized to evaluate the physical and thermal characteristics of the hybrid nanofluid, excluding the thermal conductivity and dynamic viscosity. This governing equation is transformed into a dimensionless form and the Adomian Decomposition Sumudu Transform method is employed to solve the conundrum of a moving fin immersed in a hybrid nanofluid. The reliability of this research has been confirmed by verifying the results through a comparison with numerical simulations. The influence of diverse factors on the thermal overview for varying noninteger values alpha is analyzed and presented in graphical representations. Moreover, the analysis reveals that the highest heat flux occurs in the scenario where nanoparticles with spherical-platelet shapes are combined. This is succeeded by the spherical-cylindrical combination, and finally, the spherical-spherical pairing, in terms of heat flux magnitude. Here, we discovered that the temperature at the fin tip decreases by 11.19141 % for s-s shaped nanoparticles, 10.45649 % for s-c shaped nanoparticles and 10.21162 % for s-p shaped nanoparticles as the wet parameter (m2) increases by a factor of 400, and also when the radiation parameter is increased by 400 %, the temperature of the fin tip drops by 13.11313 % for s-s shape nanoparticles, 11.97076 for s-c shape nanoparticles and 11.653899 % for s-p shape nanoparticles.

Melting-solidification cycle of finned heat storage tank: Optimization of fin structure by response surface method

The impact of the enhanced heat transfer performance of longitudinal fins on the entire process of melting and solidification in a phase change heat storage unit is investigated through experiments and numerical simulations in this paper. The position and structure of the longitudinal fins are optimized by using the response surface method while ensuring that the total volume of the heat storage medium remains unchanged. Studies have identified that some challenging zones in melting and solidification significantly impact the heat transfer of the entire heat storage cycle. Specifically, the challenging zone in melting primarily exists in the lower part of the unit during the charing process, while the challenging zone in solidification is mainly distributed around the unit during the discharging process. Through optimization, the optimized structure (fin spacing is 22.5 mm, fin width is 6.05 mm) can reduce the charging and discharging time by 16.94 % and 45.90 %, respectively. Additionally, the round trip time is significantly reduced by 39.19 %, and the mean heat absorption rate during the melting process is enhanced by 20.28 %. Moreover, the mean heat release rate during solidification is enhanced by 80.23 %.

Design and Research of Heat Storage Enhancement by Innovative Wave Fin in a Hot Water–Oil-Displacement System

Energy storage technology provides a new direction for the utilization of renewable and sustainability energy. The objective of this study is to introduce a novel, wavy, longitudinal fin design, which aims to improve heat transfer in the melting process of a Latent Heat Thermal Energy Storage (LHTES) unit. The main goal is to mitigate the negative effects caused by the refractory zone at the end of the melting phase. A two-dimensional numerical model of LHTES unit is established by using the enthalpy porosity method and verified by experimental data. Through the quantitative comparison between the traditional rectangular fin and the innovative wave fin, the influence of wave fin on the heat transfer mechanism in the heat storage process is revealed. The results show that the average heat storage rate of five and six wave fins is 3.70% and 12.98% higher than that of conventional rectangular fins, respectively, and the average temperature response of six wave fins is 17.78% higher than that of conventional rectangular fins. The addition of the wave fin weakens the negative effect of the refractory zone, but prolongs the heating time of the initial melting point.

Investigation the influence of the number and configuration of fins on the hydrothermal behavior of a double-pipe heat exchanger

The current study targets improving the overall performance of a Double Pipe Heat Exchanger (DPHE), along with developing a correlation equation to predict the Nusselt number and friction factor. The effect of both the number and configuration of fins has been studied numerically in detail using ANSYS Fluent 2022 R1 software. The numbers of fins considered under study were 4, 6, 8, and 10, while the fin configurations were longitudinal and wavy. To verify the numerical results, a comparison of computational and experimental results was done for the traditional model; this comparison showed excellent agreement between them. Furthermore, the outcomes have shown that the overall performance of a DPHE is influenced by the number and configuration of fins. The results show that the optimum model among all models under study is a wavy fin configuration with 8 fins with an overall response of 1.33 as compared to the traditional model. In addition, four equations were developed using the numerical findings and analysis of multiple regression to predict the Nu number and friction factor as functions of the Reynolds Number (Re), Prandtl Number (Pr), number of fins (No. fin), length of pitch (Lp) and inner pipe length (Lan). The accuracy of the Nu number and friction factor equations for the longitudinal fins is 98.96 % and 96.17 %, respectively, while that for the wavy fins is 99.18 % and 97.96 %, respectively. As a result, this study can accurately depict the overall response of a DPHE.

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.

A phase change material (PCM) based novel retrofitting approach in the air conditioning system to reduce building energy demand

Improvement in air quality and reduction of airborne diseases can be effectively achieved by inducing fresh air into the building. However, this challenges the building’s energy consumption. As a proposed solution, the present study dwells into the use of phase change materials (PCM), a heat-based exchanger, as a retrofit with a Heating Ventilation and Air-conditioning system (HVAC), to extract thermal energy from fresh air and consequentially diminish the energy demand. Calcium chloride hexahydrate (CaCl2·6H2O) is used as PCM, selected by TOPSIS method based on entropy weights. The energy saved in the augmented PCM thickness (from 20 mm to 100 mm) and added longitudinal fins (5 mm in width and 50 mm in length) is assessed in comparison to the standard HVAC systems utilizing R134a. For summers in composite climate, the HVAC system retrofitted with a heat exchanger with 100 mm PCM thickness 48 fin configuration achieved peak and average energy savings of 12 % and 9 %, respectively, when the system operated for 6 h. For PCM thicknesses of 75 mm, 50 mm, and 20 mm, the maximum energy savings were 6.64 % with 48 fins, 5.22 % with 24 fins, and 3.22 % with 12 fins, respectively. The study provides policymakers with energy-efficient and sustainable solutions for HVAC systems, which can reduce energy demand and help combat climate change.

Thermal analysis of fully wetted porous longitudinal fin of parabolic profile with variable thermal conductivity and convection–radiation

AbstractThe thermal performance of a fully wetted porous fin with concave parabolic cross section is explored in this study for variable thermal conductivity. We have considered convective and radiative heat transfer with variations of temperature‐dependent surface emissivity, internal heat generation, heat transfer coefficient, and magnetic field effect on the thermal profile of the fin. The heat transfer equation is derived from Darcy's model. Nondimensional governing ordinary differential equation is attempted by Runge–Kutta–Fehlberg technique. Influences of associated parameters on the cooling performance of fin are explored through graphs. From this study, it was found that the rate of heat transfer from the fin whose thermal conductivity varies linearly with temperature is twice than that of the fin with exponential dependency on thermal conductivity in the presence of magnetic effect.

A comparative analysis of dovetail and rectangular fins with insulated tips wetted with ZnO-SAE 50 nanolubricant for energy transfer process

This study focuses on exploring innovative methods of energy conservation specifically through the nonlinear fin equation. To improve the heat transfer efficiency in cooling systems, the research suggests utilizing nano lubricants that possess superior thermo-physical properties. Unlike other nanofluids, the use of nanolubricants can decrease corrosion and abrasion in operational parts such as the bore-piston, gasket, and valve mechanisms. The study concentrates on the temperature distribution in both rectangular and longitudinal dovetail fins utilized in double-pipe heat exchanger applications. The energy equation is formulated to consider radiation, temperature-dependent internal heat generation, and wetted conditions, and is subsequently transformed into a dimensionless form. Numerical solutions to the resulting differential equation are obtained through the utilization of the collocation method. The study explores the use of a specific heat transfer liquid (ZnO-SAE 50) nanolubricant to analyze thermal dispersion in both straight rectangular and dovetail fins. Additionally, it investigates how temperature-dependent internal heat generation impacts convection-conduction heat transfer. The study finds that an increase in surface emissivity results in greater heat transfer through the fin's surface in the presence of nanolubricant.