Fin Heat Exchanger Research Articles

The Study of 3D Simulation on Heat Transfer Enhancement on Fin Tube Heat Exchanger Using Delta Wing and Winglet Vortex Generators

The vortex generator is one of the methods to improve heat transfer augmentation on flow characteristics in the air side of the fin and tube heat exchanger. There are some models of vortex generators to produce longitudinal vortices when the airflow passes the surface of the vortex generator. In the previous studies, the longitudinal vortices were able to reduce the wake region phenomenon behind the tube heat exchanger. This research aims to investigate the thermal performance of heat transfer on the collaboration between two models of vortex generators namely delta wing and winglet vortex generators on plate fin and tube heat exchanger. The simulation used four models (1) without the vortex generator (2) with the delta wing vortex generators (3) with delta winglet (4) with the combination of delta wing and winglet. The study was generated with computational fluid dynamics. The boundary conditions were set in the inlet as velocity and the outlet as pressure outlet. The airflow of velocity is represented by Reynolds numbers in the range of 4000 - 8000 with an interval of 500. The wall temperature of the tube is given at 400 Kelvin and the temperature of the airflow is given at 300 Kelvin. The epsilon model was used in the turbulence model of the simulation. The result explained that the thermal performance of heat transfer on delta winglets improved the airflow to induce longitudinal vortices and then reduced the wake region to improve the heat transfer coefficient more than other vortex generator models

A new approach for global and multi-objective optimization of fin and tube heat exchanger

Fin and tube heat exchangers (FTHEs) are widely used in buildings for various heating, ventilation, and air conditioning (HVAC) applications due to their efficiency and compact design. Optimizing the design of FTHEs for building applications can bring numerous advantages in terms of energy efficiency, performance, and overall cost-effectiveness. For this purpose, this paper introduces the Multi-Objective Set Trimming (MOST) algorithm, a robust and global optimization approach applied to the optimization of a fin and tube heat exchanger. The study compares the results obtained using MOST with the well-known semi-stochastic method, Multi-Objective Particle Swarm Optimization (MOPSO), and an exhaustive search, considering both computational time and convergence. The optimization focuses on two objectives: effectiveness and annual cost, considering eight design parameters related to heat exchanger geometry. Six different cases with varying mass flow rates on both the hot and cold sides are investigated. Results reveal that the Pareto optimal fronts achieved with MOPSO are entirely dominated by those obtained using MOST across all studied cases. Additionally, MOST improves the annual cost for the best economic solution by up to 10.69% compared to MOPSO, and effectiveness is enhanced by up to 1.95%. Notably, the computational time is significantly reduced with MOST, ranging from 49.36% to 97.49% compared to MOPSO across different cases. As a result, the implemented method provides highly effective tools for optimizing the FTHE, ensuring both fast convergence and efficient computational performance.

Numerical Analysis of Operation Characteristics in Thermal Driven Adsorption Systems with Different Adsorbent Packing Method

Waste heat generated from industrial processes, such as data centers, is often discarded due to its low temperature, making reuse difficult. Adsorption systems have been proposed as a solution to utilize this low-grade waste heat. These systems consist of adsorption beds, an evaporator, and a condenser, with the adsorption bed—typically comprising a fin-tube heat exchanger and adsorbents—playing a central role in system operation. The adsorbent facilitates adsorption and desorption processes, driving system functionality. Two primary methods exist for packing the adsorbent into the adsorption bed: filling the void spaces around the heat exchanger with adsorbent particles, and coating the surface of the heat exchanger fins. These different packing methods affect the heat and mass transfer characteristics of the adsorption bed and, consequently, influence the overall system performance. This study presents a numerical analysis of the operational characteristics of an adsorption system using two distinct adsorbent packing methods, and evaluates their performance. Under typical operating conditions with a heat source temperature of 80°C, the coating model demonstrated a cooling capacity of 2.05 kW, an SCP of 0.117 kW/kg, and a COP of 0.333. Compared to the packing model, the coating model achieved 41% and 61% increases in cooling capacity and COP, respectively. Notably, the SCP showed a significant improvement of 153%. These results indicate that, despite using less adsorbent, the coating model not only offers better system performance but also presents a more economical approach to adsorption system development.AcknowledgementsThis work was supported by Korea Institute of Energy Technology Evaluation and Planning(KETEP) grant funded by the Korea government(MOTIE)(No. 20202020800200, Development and demonstration of smart design platform technology for thermal energy-intensive industrial facilities).

Enhancement of Heat Transfer rate using Axially Interrupted Rectangular Fins in Double Pipe Heat Exchanger

The current investigates the thermo-fluid behavior of a double pipe heat exchanger (DPHE) featuring axially interrupted rectangular fins (AIRF) on the annulus part. The inner tube under this study with AIRF represents an interruption of straight longitudinal fins. This modification introduces periodic breaks along the tube's surface, effectively disrupting the boundary layer of the fluid flow. Consequently, it enables a non-continuous fluid passage along the length of the tube, potentially enhancing heat transfer. The experimentation employs standard liquid water, for investigations conducted under varying cold water mass flow rate 0.136 Kg/s to with 0.374 Kg/s keeping hot water at constant flow rate of 0.34 Kg/s with a fin split interval of four different lengths 7mm,27mm,55mm,100mm. A comprehensive investigation of the AIRF arrangements is carried out in contrast to the plain pipe arrangement, concentrating on fluid flow parameters such as Nusselt number (Nu), friction factor, heat transfer rate, and overall performance factor. The findings reveal that heat transfer rates in an annulus equipped with 7mm AIRF exceed those of a plain pipe by 59.31% under similar fluid flow conditions. The Nusselt number shows 1.5 times increase in the 0.007 m AIRF arrangement compared to the plain pipe. Thermal performance factor for 7mm interrupted length of AIRF outperforms other models.

Performance improvement of magnesium-based hydrogen storage tanks by using carbon nanotubes addition and finned heat exchanger: Numerical simulation and experimental verification

One of the important tasks of improving the properties of metal hydride reactors is the design of system with optimized heat and mass transfer. Many works are devoted to the selection of the optimal heat exchanger for metal hydride hydrogen storage systems. At the same time, it is necessary to consider the composition of the metal hydride bed, which affects thermal conductivity as well. Little attention has been paid to the study of heat transfer properties in hydrogen storage systems with a heat exchanger and a metal hydride bed based on magnesium hydride and carbon nanotubes. In this work we used numerical simulation to determine the effectiveness of carbon nanotubes addition and heat exchangers with different fin number and geometries on high-temperature magnesium-based hydrogen storage tanks performance. It was found, that increasing the number of fins from three to five makes a smaller contribution in the temperature increasing as compared to the addition of three fins to the heater. The three solid, radial and complex fins have a similar effect on the average Mg/MgH2 bed temperature at 60 min. The most optimal fin number and geometry is three radial fins in terms of the efficiency and the volume it occupies. The addition of carbon nanotubes increases the average temperature of the Mg/MgH2 bed by 67 K for a reactor equipped with a heater without fins. Hydrogen storage system with three radial fins and Mg/MgH2 bed enhanced with carbon nanotubes provides an increase in the average bed temperature of about 180 K as compared to system without fins and nanotubes. This leads to a reduction in the hydrogen absorption time to reach 90% saturation by almost 63% for the three radial fins reactor with carbon nanotubes addition to the metal hydride bed. It has been confirmed that the addition of carbon nanotubes to Mg/MgH2 makes a significant contribution to the heat transfer in the metal hydride bed. In addition, it is shown that both an increase in the heat transfer area and the thermal conductivity coefficient leads to a significant improvement in the efficiency of the metal hydride reactor. In the future, the obtained results can be taken into account when designing hydrogen storage systems based on these materials.

Study on the double-coil heat exchanger for dehumidification and heating in greenhouses: Modeling, analysis, and optimization

Heat exchangers are widely used in dehumidification and heating technologies owing to their excellent heat transfer performance, however, their dehumidification capability is limited for greenhouse applications. This study evaluates a double-coil heat exchanger (DC-HE) for dehumidification and heating in greenhouses. Humid air undergoes condensation dehumidification through the dehumidifying coil and is then reheated by the heating coil before being released. Using double coils allows for the separate circulation of cold and warm water in their respective paths, handling the latent and sensible heat of the air. In this study, predictive methods for air treatment in a heat exchanger are combined, and theoretical calculations are performed on the DC-HE and validated through experimental investigations. Furthermore, the impact of variables such as air temperature, relative humidity, water temperature and flow rate, and air flow rate on the moisture removal rate (MRR), latent heat ratio (LHR), and heating capacity (qheat) of the DC-HE is analyzed, the effects of these variables on the sensible and latent heat transfer rates are discussed. Finally, the optimal variables for maximizing MRR and LHR are determined using the response surface method and multi-objective genetic algorithm. When the inlet air temperature, relative humidity, cooling-side water temperature, heating-side water temperature, cooling-side water flow rate, heating-side water flow rate, and air flow rate are 11.8 ℃, 95 %, 3 ℃, 30 ℃, 2 m/s, 2 m/s, and 2 m/s, respectively, the DC-HE achieves an MRR of 1.58 g/s, an LHR of 62.2 % and a qheat of 9.99 kW. Compared with other finned tube heat exchangers, the DC-HE enhances the moisture removal capacity and significantly reduces the temperature requirement for the heat source, offering a promising dehumidification and heating technology for greenhouse applications.

Enhancement of air-side heat transfer in crossflow heat exchangers using auto-fluttering reeds

Thin film aeroelastically fluttering reeds are investigated as a mechanism to enhance air-side heat transfer in an industry relevant crossflow heat exchanger that can reject over 10kW of heat. Nusselt number and friction factor measurements are made in a temperature- and humidity- controlled wind tunnel over a range of air inlet temperatures and flow rates spanning an air-side Reynolds number range of 800<Re<6000 without the reeds and 1200<Re<3400 with the reeds installed in the heat exchanger fin channels. Experiments are conducted with a set of 1440, 50.8-mm long, 15.9-mm wide, rectangular Mylar reeds installed in the heat exchanger fin channels. The fluttering reeds enhanced heat transfer by up to 60% with a maximum friction factor penalty of 200%. Two different reed thicknesses are investigated, 0.013mm and 0.025mm. Increasing the reed thickness yielded similar heat transfer performance while decreasing the friction factor penalty, indicating that it may be possible to decrease the pressure drop penalty through geometric optimization. Correlations for the reed Strouhal number and the reed-enhanced Nusselt number and friction factor are developed as a function of relevant dimensionless parameters.

Heat transfers in heat exchangers in steady and oscillating flows

Heat exchangers are a key constitutive element in thermoacoustic machines. Although they are required to operate with oscillating gas, their design is mostly guided by direct extrapolation of the knowledge applicable to steady flow heat exchangers, due to the lack of objective criteria for the design of oscillating flow heat exchangers. Most of the works in the literature present theoretical or numerical results, but very few experimental data are available to confirm (or refute) the strong hypothesis leading to the extrapolation. This study presents the comparative measurements of the heat transfers capabilities of triangular louvered fin heat exchangers in steady and oscillating flows under otherwise similar conditions.

Multiphysics Studies of 3D Plate Fin Heat Exchanger Filled with Ortho-Para-Hydrogen Conversion Catalyst for Hydrogen Liquefaction

Multiphysics Studies of 3D Plate Fin Heat Exchanger Filled with Ortho-Para-Hydrogen Conversion Catalyst for Hydrogen Liquefaction

Inclined Installation Effect on the Offset Strip Finned Heat Exchanger Designed for a Hybrid Electric Propulsion System in Electric Vertical Take-Off and Landing

The plate-fin heat exchanger was designed for the liquid cooling thermal management system of the hybrid electric propulsion system for an electric vertical take-off and landing (eVTOL) vehicle. The offset-strip fin design was applied, and the performance of the heat exchanger was evaluated, particularly with respect to the inclination of the airflow entering the heat exchanger. The estimated performance during the design phase matched well with the experimental results. The inclination of the heat exchanger had a minimal effect on thermal performance, with a slight increase in performance as the inclination increased. However, the pressure difference along the airflow was affected, likely increasing as the inclination increased. The sensitivity of various parameters on coolant temperature was also investigated. The air inlet temperature had a significant effect on coolant temperature, followed by the coolant flow rate. Therefore, when designing the thermal management system, careful consideration should be given to the ambient air temperature and coolant flow rate.

Anti-Frosting and Defrosting Fins with Hierarchical Interlocking Structure for Enhancing Energy Utilization Efficiency of Heat Exchanger.

Air conditioners, being an indispensable component of contemporary living, consume a significant amount of electricity every year. The accumulation of frost, dust, and water on the fins surface hinders the efficiency of the heat exchange process, thereby reducing the effectiveness of the air conditioning system. To address these limitations, this paper proposes a large-scale and cost-effective method combining compression molding, chemical etching, and spray coating to fabricate aluminum fins (HMNA) with hierarchical interlocking structures. The HMNA exhibits outstanding durability, passive and active anti-icing, anti-frosting and defrosting, and self-cleaning capabilities associated with the robust super-hydrophobicity. The hierarchical interlocking structure effectively enhances the physical and environmental durability of the HMNA. Most significantly, the frost time of the HMNA fins assembled heat exchanger is significantly delayed by ≈700% compared to the traditional Al fins heat exchanger, while the frost layer thickness is reduced by ≈75%. This greatly reduces the frequency with which the defrosting cycle is started, thus effectively improving the efficiency of the air conditioning system. The proposed method for economical and mass production of the HMNA fins can be an excellent candidate for the development of low energy consumption air conditioning system.

Analysis of Efficiency of Finned Heat Exchanger Fed with Synthetic and Natural Refrigerant

Analysis of Efficiency of Finned Heat Exchanger Fed with Synthetic and Natural Refrigerant

Numerical Investigation of Enhanced Heat Transfer with Micro Pin Fins in Heat Exchangers.

Pin-fin and flat-tube heat exchangers (PFFTHXs) offer a promising alternative to traditional louvered-fin and flat-tube heat exchangers (LFFTHXs), especially when used as evaporators. The streamlined structure of pin fins helps to effectively remove condensate and defrost water. In this study, we conducted a numerical analysis of 60 different pin-fin configurations across three pin diameters to enhance heat transfer in PFFTHXs. Our investigation focused on how pin pitch affects both airflow and heat transfer efficiency. The results show that a closer pin pitch increases both the heat transfer rate per unit area and the pressure drop for a given airflow velocity. We evaluated the overall performance of these configurations using the heat transfer rate per unit frontal area obtained at equivalent fan power levels. The analysis identified optimal configurations for each pin diameter, with the 0.2 mm diameter configuration demonstrating the highest heat transfer efficiency-this was on par with louvered fins but used fewer resources. This makes it an ideal choice for evaporative applications in PFFTHXs.

Temperature-Driven Instabilities in High-Pressure Vessel Flat Plates: A Thermal Buckling Study

In the realm of high-pressure vessel simulation, conventional finite element method (FEM) approaches, as per ASME standards, may inadequately predict the behavior of flat surfaces under elevated temperatures. This study challenges the efficacy of shell-type mesh modeling for high-temperature flat plates, demonstrating that the thermal conditions within such high-pressure vessels can induce thermal instability and buckling, not accounted for by traditional FEM methods recommended by ASME. Through comprehensive analytical investigations, we reveal that traditional shell-type meshing techniques, while suitable for certain applications, fail to capture the intricate thermal stresses and deformation patterns inherent in high-temperature flat plate configurations. Our analysis delineates distinct stability regimes governed by key design parameters, including plate thickness, operating temperature, and geometric dimensions, profoundly impacting the structural integrity of heating plates under thermal loading. Specifically, we found that increasing the plate thickness enhances resistance to thermal buckling, clamping the plate edges raises the critical buckling temperature, and selecting materials with lower thermal expansion coefficients improves stability. These findings provide engineers with critical insights necessary for optimizing the design and performance of high-temperature equipment. This includes the design of high-pressure vessels with flat surfaces for heating materials, flanges in high-temperature environments, and fins in heat exchangers across various industries such as oil and gas, pyrolysis, and power plants. The findings presented herein serve as a valuable reference for engineers seeking to comprehend and mitigate instability phenomena in solid mechanics, offering practical guidance for developing robust and reliable high-temperature structures in demanding industrial environments.

Melting performance of PCM with MoS2 and Fe3O4 nanoparticles using leaf-based fins with different orientations in a shell and tube-based TES system

Phase change materials (PCMs) are frequently utilized in the thermal sector, especially for thermal energy storage (TES) applications. The purpose of this study was to analyze the thermal efficiency and melting characteristics of a leaf-vein-shaped fin in a triplex tube heat exchanger. The analysis focused on the use of pure molten salt PCM and a combination of molten salt PCM with MoS2 and Fe3O4 nanoparticles. The study utilized ANSYS Fluent software to conduct numerical simulations and analyze seven distinct fin arrangements. The simulations were employed to visualize and examine the liquid fraction, temperature, and fluid velocity. The findings indicated that the leaf-vein fin shape greatly improved the dispersion of liquid fraction, average temperature, and velocity in comparison to alternative fin designs. The addition of MoS2 and Fe3O4 nanoparticles significantly enhanced the melting and thermal characteristics of the PCM as a result of heightened thermal conductivity. This showcases the capability of the leaf-vein fin design and PCM nanocomposites to enhance the efficiency of thermal energy storage in triplex tube systems. About 2500 s PCM melt about 36% for case A, but melting rate enhance up-to 55% using nano particles. Melting rate enhance 91% in 1000 s in case of G using 8 fins as compare to case A having no fins.

Experimental study on the characteristics of frost formation and defrosting water retention between vertical double surfaces with different wettability

Frost formation and defrosting water retention directly affect the heat transfer process of outdoor finned tube heat exchanger, which in turn influences the energy efficiency of air source heat pumps for building heating. Three typical wettability surfaces were prepared, including a bare copper hydrophilic surface (BCS), a hydrophobic copper surface (HCS) and a superhydrophobic copper surface (SHCS). The above three surfaces are combined in pairs to construct three different wettability combinations, which are Combination 1: HCS-BCS, Combination 2: BCS-SHCS and Combination 3: HCS-SHCS, respectively. Frosting-defrosting experiments between vertical double surfaces are carried out on the above combinations. The results illustrated that the combinations with SHCS exhibit excellent frost inhibition properties. Compared with Combination 1, the channel filling rate of Combination 2 and Combination 3 were reduced by 16.79 % and 30.09 % respectively at a frosting time of 60 min. The defrosting time of the combination is determined by the slower defrosting of the two surfaces. Compared with Combination 2, the defrosting rate of Combination 3 is improved by up to about 12.93 %. Avoiding the formation of large-sized liquid films and droplets or utilizing the “absorption” phenomenon caused by wettability differences between surfaces are important measures to reduce the possibility of bridge formation during the defrosting process. And the greater the wettability difference, the more obvious the “absorption” phenomenon became. Spherical droplets on the SHCS can be completely absorbed by the liquid film on BCS under the action of differential surface tension. Neither Combination 2 nor Combination 3 formed a liquid bridge at a surface spacing of 2 mm. The research will provide theoretical support for the selection of fin spacing and fin coating type under different working conditions in practical engineering.

Deposition Distribution and Thermal Resistance Analysis of Fins in Heat Exchangers

Deposition Distribution and Thermal Resistance Analysis of Fins in Heat Exchangers

Parametric study and optimization of H-type finned tube heat exchangers with honeycomb arrangement using Taguchi method

Enhancing the efficiency of flue gas waste heat utilization is an important way to achieve carbon peaking and carbon neutrality goals. In this paper, a three-dimensional numerical model of an H-type finned tube heat exchanger with honeycomb arrangement is developed. Firstly, the effects of five parameters are analyzed using the control variable method, including the oblique tube pitch, the ratio of fin height to oblique tube pitch, fin pitch, fin thickness and slit width. Then, the Taguchi method was used to investigate the interaction effects of the five geometric parameters. Numerical simulations of 27 cases with different parameter combinations were carried out and the heat transfer and flow friction characteristics and their overall performance were discussed in detail. The results show that oblique tube pitch has the most significant effect on heat transfer capacity, fin pitch has the most significant effect on overall performance, and slit width has the least effect on both. Finally, the optimum parameter combinations were obtained. When inlet velocity ranges from 5 m/s to 10 m/s, heat transfer performance is increased by 46.3 %-52.1 %, pressure drop is increased by 5.7 % − 11.3 %, and the overall performance PEC is improved by 63.5 %-105.9 %. The results of the study contribute to the development and optimization of new flue gas heat exchangers.

Multi-objective optimization of heat transfer performance of H-type fin with vortex generator based on NSGA-II

To further enhance the performance of heat exchangers and bolster waste heat recovery, vortex generators (VGs) of various shapes are added to the H-type fins. This study explores the impact of VGs’ attack angles and configurations on the thermal performance of H-type finned tubes under different Reynolds (Re) numbers. Additionally, multiple dimensionless evaluation metrics are introduced to assess the flow and heat transfer characteristics with VGs, and correlations for predicting the Nusselt (Nu) number and pressure drop at varying attack angles are developed. The results reveal that at low Re numbers, trapezoidal winglets yield the highest comprehensive performance factor (R-factor), while at high Re numbers, rectangular winglets prevail. Compared to trapezoidal winglet configurations, rectangular winglets enhance the Nu by 6.49%-6.67%. Among the various attack angle configurations, the 45° rectangular winglets exhibit the most favorable overall heat transfer performance, with a Nu increase of 12.07% compared to standard H-type fins. It is observed that installing more than two VGs can result in an R-value less than 1, suggesting that excessive VG placement in H-type fin heat exchangers is not advisable. Finally, the Non-dominated Sorting Genetic Algorithm II (NSGA-II) is employed to identify Pareto optimal points, which exhibit lower resistance and enhanced convective heat transfer. The Pareto optimal set, in comparison to different attack angle CFD data, shows a 31.27% reduction in resistance and a 15.72% increase in Nu.

Performance of a Simplified Computational Fluid Dynamics Model for a Phase Change Material–Water Finned Heat Exchanger Under Different Orientations

ABSTRACTThe prevalent numerical models for simulating axially finned heat exchangers with phase change materials (PCMs) and water as the heat transfer fluid rely on computational fluid dynamics (CFD) techniques, with a primary focus on phase change modeling. However, the computational demands of these models, incorporating phase change effects and resolving PCM movement in the liquid state, are substantial. From experiments suggesting that conduction in the solidified PCM around the finned tube dominates heat transfer during the heat discharge process, this article introduces a simplified CFD‐based model in which convective flow of the PCM is neglected. The model is experimentally validated using a 1‐m‐long axially finned heat exchanger prototype with four fins, recording temperatures under different water flow rates and orientations (horizontal and vertical). Results show that the proposed model predicts outlet water temperature satisfactorily, with absolute errors below 1.0°C and 2.2°C for the horizontal and vertical orientations, respectively. Additionally, the model can capture the temperature trend inside the PCM for the horizontal orientation.