Heat Transfer Characteristics Research Articles

Influence of Temperature and Mass Flow Rate on Heat Transfer Characteristics in Parallel Flow Corrugated Plate Heat Exchanger

Influence of Temperature and Mass Flow Rate on Heat Transfer Characteristics in Parallel Flow Corrugated Plate Heat Exchanger

Novel Cu-MXene hybrid nanofluids for the experimental investigation of thermal performance in double pipe heat exchanger

This work aims at analyzing the performance of a double-pipe heat exchanger (DPHE) using low concentrated (0.02–0.06 vol%) water, methanol, castor oil and silicon oil based Cu-MXene hybrid nanofluids. Convective heat transfer experiments were successfully performed in fabricated modular double pipe heat exchanger without using any twisted tapes, surfaces and effectively measured various heat transfer parameters such as Nusselt number (Nu), heat transfer coefficient (h), rate of heat transfer (Q), overall heat transfer coefficient (U), friction factor (f), pressure drop (∆P), and the thermal performance factor (TPF). The results indicated a considerable improvement in Nu, h, and U with some penalty in ∆P. Moreover, the TPF value of methanol and water-based hybrid nanofluids exceeded unity and showed superior heat transfer characteristics, confirming the viability of improving thermal performance in DPHE. Eventually, the LMTD and U of hybrid nanofluids were positively validated using Aspen HYSYS 12.1 version software to verify the experimental results and showed a variation of less than ± 5.35% for U and LMTD. These results successfully demonstrate the possible usage of proposed Cu-MXene hybrid nanofluids in thermal management systems, automotive cooling, and industrial cooling respectively. In addition, these findings also encourage its use in superior performance and cost-effective thermal management technologies.

Heat Transfer Characteristics of Electrical Heating Deicing and Snow-Melting Asphalt Pavement Under Different Operating Conditions

Heat Transfer Characteristics of Electrical Heating Deicing and Snow-Melting Asphalt Pavement Under Different Operating Conditions

Experimental and simulation study of flow and heat transfer characteristics of the leaf-veined mini-channel heat sink

Experimental and simulation study of flow and heat transfer characteristics of the leaf-veined mini-channel heat sink

Radiative-dissipative effects on bioconvective MHD flow in Eyring-Powell ternary nanofluids.

Eyring-Powell nanofluids have great potential for use in biomedical engineering to create more effective medical procedures and treatments due to their special properties of fluidity, efficient heat transfer, and interaction with biological systems. This study investigates bioconvection flow and its heat transfer characteristics of the magnetohydrodynamic ternary hybrid nanofluid containing silver, copper, and aluminum nanoparticles with human blood. The forced convection in a porous media, radiation, and viscous dissipation have been considered. The governing equations are reduced to dimensionless partial differential equations and further simplified using the local non-similarity method to obtain ordinary differential equations, which were solved numerically using the BVP4C algorithm. The results indicate that the concentration profiles reduce with inertia coefficients and Schmidt numbers, while radiation parameters increase the surface temperature. A higher Lewis number accelerates thermal diffusion, in contrast to mass diffusion. Fast dissipation of temperature prevents microbial growth and is useful in applications dealing with medicine administration and wound healing. These results support existing research and provide recommendations for further improvement of industrial and biological processes. As the rises from to the Nusselt number declines as follows: for by around , for by and for by . The Nusselt number increases around as rises from to for , for by the Nusselt number increases by and for by . The article proposes non-similar transformations for solving complex problems on the movement of ternary nanofluids. This provides insight into medical applications such as drug delivery and diagnostic tools and advances nanofluidic dynamics in healthcare.

Experimental and Numerical Investigation of Heat Transfer Characteristics of Double-Layer Phase Change Walls for Enhanced Thermal Regulation in Summer Climates

This study employs the effective heat capacity method within the COMSOL simulation framework to analyze the thermal performance of double-layer phase-change walls under typical summer climatic conditions in Zhengzhou, Henan Province. The model considers a wall structure with a total thickness of 100 mm and a height of 300 mm, where the exterior surface represents the outdoor environment, the interior surface represents the indoor environment, and the top and bottom boundaries are assumed to be adiabatic. A highly refined triangular mesh ensures numerical stability and solution accuracy. Special attention is given to the influence of Micro-PCM content on thermal storage characteristics. Simulation results demonstrate that increasing the Micro-PCM content substantially enhances the thermal regulation capacity of the double-layer phase-change walls. At a Micro-PCM volume fraction of 15%, the peak temperature of the double-layer phase-change wall is reduced by 4.33 °C compared to a conventional wall, while the attenuation factor increases to 16.88. Furthermore, the mean thermal delay extends to 440 min, the temperature amplitude decreases to 1.13 °C, and the peak instantaneous heat flux is reduced to 13.24 W/m2. These findings highlight the significant latent heat storage capacity and superior thermal modulation performance of double-layer phase-change walls, offering a valuable technical reference for the design of energy-efficient building envelope systems.

Investigation of the hydraulic and thermal characteristics of a double concentric tubes with an inner twisted spiral tube

The characteristics of heat transfer and fluid flow of twisted spiral tubes with different pitches and depths have been investigated experimentally with respect to a conventional tube (smooth tube) as a particular reference. The effects of the twisted spiral pitch ratios, S/Dhy, depth ratios, H/Dhy, Reynolds number and flow arrangement on the thermal performance of a twisted spiral tube heat exchanger are investigated. Three twisted spiral tubes with different pitches, S, of 3.9, 5.2 and 8.2 mm corresponding to twisted spiral pitch ratios, S/Dhy, of 0.278, 0.372 and 0.586; besides three twisted spiral tubes at different depths, H, of 0.6, 0.95, and 1.15 mm corresponding to twisted spiral height ratio, H/Dhy, of 0.043, 0.068 and 0.082 are experimentally examined in this study. The Reynolds number, Re, ranges in both inner tube side and annular side are 5000–50,000 and 1400–10,400, respectively. The results revealed that the twisted spiral pitch ratios S/Dhy of the 0.278achieved an enhancement of Nu by 38% compare to the smooth tube with a corresponding increase of 33.2% in the f. Also, the twisted spiral depths ratios, H/Dhy, of 0.082 achieved higher Nu by 44.9%, compared to the smooth tube with a corresponding increase of 36.4% in the f. The thermal performance criteria reached 1.93 and 2.03 at S/Dhy of 0.278 and H/Dhy of 0.082, respectively. New correlations to expect Nuc and fc were predicted.

CFD-DEM Modeling and Experimental Verification of Heat Transfer Behaviors of Cylindrical Biomass Particles with Super-Ellipsoid Model

The heat transfer (HT) characteristics of cylindrical biomass particles (CBPs) in fluidized beds (FBs) are important for their drying, direct combustion, and thermochemical transformation. To provide a deeper insight into the complex mechanisms behind the HT behaviors involving CBPs, this study developed a cylindrical particle HT model within the framework of computational fluid dynamics coupled with the discrete element method (CFD-DEM) in which the CBPs were characterized by the super-ellipsoid model, which has the unique merit of striking a balance between computational accuracy and efficiency. The newly developed heat transfer model considers particle–particle (P-P), particle–wall (P-W), and fluid–particle (F-P). Its accuracy was verified by comparing the numerical results with the experimental infrared thermography measurements in terms of the temperature evolution of the cylindrical particles. The effects of the gas velocity, inlet temperature, and thermal conductivity of particles on the HT behaviors of the CBPs were investigated comprehensively. The results demonstrated the following: (1) Gas velocity can improve the uniformity of bed temperature distribution and shorten the fluctuation process of bed temperature uniformity. (2) A 26.8% increase in inlet temperature leads to a 13.4% increase in the proportion of particles with an orientation in the range of 60–90°. (3) The thermal conductivity of particles has no obvious influence on the bed temperature, convective HT rate, or orientation of particles.

STRENGTH CHARACTERISTICS OF CARBON STEEL FLAT-OVAL TUBES FOR TWO-PHASE THERMOSYPHONS OF THE LOW-TEMPERATURE RANGE

The development and improvement of heat exchangers and systems of cooling and thermal stabilisation of electronic equipment requires the use of new highly efficient heat transfer elements capable of transferring significant heat fluxes with small overall dimensions. Two-phase thermosyphons (TS) are widely used as such elements. As a rule, TS casings are made of round, solid pipes, but alternative profiles, such as flat-oval, are also used to improve the overall dimensions and heat transfer characteristics. Due to their simple manufacturing technology, convenient shape and high thermal and aerodynamic performance, flat-oval tubes have broad prospects for use as TS casings. When operating in the low-temperature range, the internal pressure in the TS can reach 4 MPa, so the key issue when using any pipes as TS casings is strength. Since there is no data on the strength characteristics of flat-oval pipes, this issue needs to be investigated. The paper presents the results of experimental studies of the strength characteristics of flat-oval tubes with a longitudinal weld made of carbon steel. To conduct the research, 3 samples of TS filled with water were made from such pipes. The internal pressure was created by supplying heat to the TS. Its value was determined by the saturation temperature, which, in turn, was determined by the readings of thermocouples installed on the outer surface of the TS casing. The obtained results showed that at temperatures up to 210°C and pressures up to 19,074·105 Pa, there was no change in the shape of the cross-section of the TS with a flat-oval tube casing. An increase in temperature and pressure led to deformation of the DTS casing with its subsequent depressurisation. In all cases, the depressurisation occurred along the sealing at the end of the filling tube. Also, the regularities of changes in the geometric dimensions of flat-oval TS depending on temperature and pressure were obtained in graphical form. The data obtained should be taken into account when designing cooling, thermal stabilisation and heat transfer systems based on flat-oval TS.

Cooling Performance Experiment and Simulation Investigation of Flow Boiling Heat Transfer for Wire Rods during Quenching in Molten Salt Mixtures

When the wire is cooled in the salt bath, since the wire temperature far exceeds the boiling point of the molten salt, accurately modeling the heat transfer process in molten salt quenching is difficult. Therefore, for investigating the cooling mechanism and improving the mechanical properties of wire rods, quenching experiments are conducted on specimens (92Si) at various molten salt (a 1:1 mixture of NaNO3‐KNO3) temperatures using a salt bath furnace. Cooling curves are measured, and thus the real boiling heat transfer coefficient (HTC) at the metal–salt interface is calculated using a validated in‐house‐programmed inverse heat transfer algorithm based on experimental data. By integrating the experimentally determined boiling HTC with the convective HTC obtained from a salt bath simulation, a mathematical model of superposition flow boiling heat transfer is developed to predict the heat transfer characteristics, wire cooling behavior, and phase‐transformation processes within the salt bath, which is also an innovation point of this article. The model effectively captures the actual heat transfer behavior during the early stages of salt bath quenching. The model is further used to evaluate the optimal molten salt temperature for quenching in a modified salt bath system with a flow rate of 60 m3 h−1.

Impact of geometric parameters on the performance of naturally ventilated photovoltaic curtain walls

Ventilated photovoltaic curtain walls reduce buildings’ reliance on the electricity grid, transforming them into producers and consumers. The airflow and heat transfer characteristics within curtain walls are necessary for better photovoltaic and thermal efficiency. This paper establishes a natural convection model of the photovoltaic curtain walls, solved using the finite element method, focusing on the impact of geometric parameters on flow and heat transfer to determine the optimal channel geometry. Results show that the thickness significantly affects the photovoltaic curtain wall’s performance, with 200 mm thickness being optimal. Compared to direct contact with the building surface, using a 200-mm-thick channel reduces the photovoltaic module’s average temperature by 5.27%, increasing the photovoltaic efficiency and overall efficiency by 0.21 and 12.56%. Increasing the width and height enhances heat accumulation and thermal efficiency. Large heights improve the chimney effect and air velocity but minimally affect the average temperatures of the air and panels.

Unsteady Flow of Magnetized SWCNTs-MWCNTs/H2O Over a Stretching Sheet with Temperature-Dependent Properties: A Comparative Analysis

Purpose: This research aims to investigate the flow and heat transfer characteristics of a hybrid nanofluid comprising water, single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs) over a stretching sheet under the influence of a magnetic field. Design/Methodology/Approach: The study employs a mathematical model that accounts for factors such as variable viscosity, thermal radiation, a porous medium and heat generation/absorption. The governing partial differential equations (PDEs) are transformed into ordinary differential equations (ODEs) using similarity transformations and then solved numerically using the bvp4c solver in MATLAB. Findings: The numerical results reveal that the velocity profile of the hybrid nanofluid is significantly enhanced by the presence of MWCNTs. Additionally, the temperature profile is influenced by parameters like the magnetic field, heat source/sink and Prandtl number. The Yamada–Ota (Y–O) model is found to have a more pronounced effect on heat transfer compared to the Xue model. Originality/Value: This study provides valuable insights into the behavior of hybrid nanofluids in complex flow scenarios. The findings can be applied to the design and optimization of various thermal systems, such as heat exchangers and cooling devices.

Numerical Study on Conjugate Heat and Mass Transfer Characteristics Around Thermosolutal Exchangers: Effect of Flow Parameters and Solid Block Arrangement

Abstract The effect of airflow characteristics within a slot-ventilated enclosure is carried out numerically to optimize the heat and contaminants’ removal rate where cold air is injected via an inlet port. The contaminated air is expelled by the chimney outlet port positioned along the left side of the top wall. Based on the structure dynamics, the flow governing equation is dealt with the Navier–Stokes equations coupled with the energy equation, where the maximum cooling efficiency is evaluated. A finite volume-based semi-implicit method for pressure-linked equations (SIMPLEs) method is utilized to deal with the nonlinear coupled partial differential equations to evaluate the flow variation with changing various physical parameters. Different thermosolutal block orientations are considered to investigate the effective interpretation of heat and mass transfer in a natural chamber. The effects of the inclination angle of the chimney, Richardson and Reynolds numbers on the average heat and mass transfer rate, average temperature, average Bejan number, and performance evaluation criterion (PEC) inside the system are evaluated. Boundary layer analysis is performed to examine the transient behavior of the boundary layer flow dominated by natural convection near the wall heater on the enclosure’s left wall and results are found to agree with our numerical results.

Full-Scale Simulation and Experimental Study of Heat Transfer in Landing Gear Brake Discs for Medium-Sized Passenger Aircraft

Aircraft brake discs undergo rapid temperature rises during braking, critically impacting safety, lifespan, and adjacent components. Therefore, it is particularly important to study the heat transfer mechanism during the braking process and predict the temperature distribution of the brake disc. To address challenges in experimental studies (e.g., high costs and extreme conditions), this study employs full-scale numerical simulations to investigate heat transfer behaviours in medium-sized passenger aircraft brake discs. In the numerical simulation process, a coupling model that comprehensively considers the friction heat generation of the brake disc, the solid heat transfer between the discs, and the heat dissipation of the outer surface of the disc and the surrounding air is constructed to accurately describe the heat transfer characteristics of the brake disc under dynamic conditions. The study shows that the surface temperature of the brake disc rises sharply during the braking process, resulting in a significant increase in the temperature gradient; at the same time, the surrounding air flow state significantly affects the heat dissipation efficiency of the brake disc and affects its temperature distribution. Finally, the effectiveness of the numerical simulation was verified by experiments, and the maximum relative error between the experimental results and the simulation results was about 4.5%. This study provides a research basis for optimizing the structural design of the brake disc, improving its heat dissipation performance and operating safety.

Investigate on the Fluid Dynamics and Heat Transfer Behavior in an Automobile Gearbox Based on the LBM-LES Model

With the rapid development of the new energy vehicle market, the demand for efficient, low-noise, low-energy consumption, high-strength, and durable gear transmission systems is continuously increasing. Therefore, it has become imperative to conduct in-depth research into the fluid heat transfer and lubrication dynamics within gearboxes. In gear systems, the interaction between fluids and solids leads to complex nonlinear heat transfer characteristics between gears and lubricants, making the development and resolution of gearbox thermodynamic models highly challenging. This paper proposes a gear lubrication heat transfer dynamics model based on LBM-LES coupling to study the dynamic laws and heat transfer characteristics of the gear lubrication process. The research results indicate that the interaction between gears and the intense shear effects caused by high speeds generate vortices, which are particularly pronounced on larger gears. The fluid mixing effect in these high vortex regions is better, achieving a more uniform heat dissipation effect. Furthermore, the flow characteristics of the lubricant are closely related to speed and temperature. Under high-temperature conditions (such as 100 °C), the diffusion range of the lubricant increases, forming a wider oil film, but its viscosity significantly decreases, leading to greater stirring losses. By optimizing the selection of lubricants and stirring parameters, the efficiency and reliability of the gear transmission system can be further improved, extending its service life. This study provides a comprehensive analytical framework for the thermodynamic characteristics of multi-stage transmission systems, clarifying the heat transfer mechanisms within the gearbox and offering new insights and theoretical foundations for future research and engineering applications in this field.

Reactive flow dynamics of conductive Maxwell nanofluids past heated stretching surfaces with slip and thermal radiation

In this paper, we thoroughly examine the influences of slip effects and stagnation point flows in the context of an upper-convected non-Newtonian Maxwell nanofluid interacting with a stretching sheet. The existence of a heat generation, transverse magnetic field, and thermal radiation induces a flow resulting from a linearly stretched sheet. The application of the shooting method involves deriving nonlinear ordinary differential equations from the governing partial differential equations, followed by their solution. The effects of dimensionless governing parameters, including velocity ratio, Brownian motion parameter, thermophoresis parameter, velocity slip parameter, Lewis numbers, solutal slip parameter, Maxwell parameter, magnetic number, Eckert number, thermal slip parameter, chemical reactions parameter, and heat source parameter, are examined. The outcomes are illustrated and discussed through graphical representations, showcasing their impact on the velocity field, as well as heat and mass transfer characteristics. Tabular data are generated to display numerical values for physical parameters, including the skin-friction coefficient, local Sherwood number, and the reduced local Nusselt number. The findings suggest that an increase in the velocity slip parameter results in a reduction of both the local Sherwood number and the local Nusselt number. Furthermore, an increase in the strength of the magnetic field leads to a decrease in velocity profiles while simultaneously elevating temperature and concentration profiles.

Theoretical Exploration of Bioconvection Magneto Flow of Micropolar Nanomaterial Off‐Centered Stagnation Point Framed by Rotating Disk

AbstractThis study explores the bioconvection flow of MHD Micropolar nanomaterial having with motile microorganisms off‐centered stagnation point across the rotating. The flow field study takes into account the impact of radiative flow, chemically reactive species, and the convective flow condition. The Buongiorno two‐component nanoscale model is used to simulate Brownian movement with thermophoretic body force phenomena. Using dimensional similarity factors, the nonlinear partial differential equations related to boundary conditions are transformed by a complex dimensionless ordinary differential expression. The homotopy analysis method is applied to utilize the ordinary differential expression and envision the influence of resulting variables such as viscosity variable, spin gradient parameter, microinertia density parameter, porosity parameter, rotational parameter, Biot number, Brownian movement, thermal radiation, Prandtl number, and Bioconvection Lewis number over velocities, heat, and mass transfer characteristics in visually and the table formats. It is observed that the larger magnitude of the material variable, magnetic variable, and porosity variable reduces the radial velocity. Moreover, microrotational profiles depreciate quickly as spin gradient viscosity, micro‐inertia density. The fluid temperature increases in direct correlation with thermal radiation, thermophoresis, and Biot number while microorganism density distribution reduces due to the larger values of Peclet number and Bioconvection Lewis number.

Numerical research on heat transfer and flow characteristics of R141b refrigerant in metal foam bionic hierarchical microchannels

Greater heat transfer area is provided since the special porous media frame structure for metal foam. However, it also increases fluid flow resistance, which is not conducive to fluid flow. In this study, the Sarracenia trichome bionic channel structure is innovatively developed to reduce the flow resistance. First, six different types of bionic hierarchical microchannels are modeled using metal foam concerning the high and low rib structure of Sarracenia trichomes. The gas-liquid two-phase flow process is simulated numerically in each microchannel by using R141b refrigerant. Then, the synergy coefficients are compared between the bubble number and heat transfer coefficient in different microchannels. Finally, the velocity field and streamline distribution of the microchannels are studied, and the flow resistances are analyzed. Results show that the bubble number and heat transfer coefficient in the high and low rib microchannels follow the same synergistic trend as the other microchannels. Furthermore, two continuous but different fluid transport modes exist in the hierarchical microchannels with high and low rib structures. The bionic structure transport modes improve the water transport performance and reduce the flow pressure drop.

Drag Force and Heat Transfer Characteristics of Ellipsoidal Particles near the Wall

This study investigates the force and heat transfer characteristics of oblate spheroidal particles in gas–solid two-phase flows near walls, addressing the influence of particle orientation, shape, Reynolds number, and particle–wall distance. These factors are critical in industrial processes such as pneumatic transport and crop drying, as well as in natural phenomena. Utilizing the Euler–Lagrangian model and large eddy simulation (LES), we simulated flow fields and heat transfer under various conditions. The results indicate that at Re = 500, turbulence mitigates wall interference, leading to a 14.4% increase in the Nusselt number (Nu). Particle orientation plays a crucial role in heat transfer, with Nu decreasing by 20% at = 90° due to restricted interstitial flow. A higher aspect ratio (Ar = 0.8) enhances heat transfer by 25% compared to a lower aspect ratio (Ar = 0.1). Additionally, increasing the particle–wall distance from H = 0.25dv to H = 0.5dv reduces wall-induced drag by 30%. The findings enhance the understanding of particle–fluid interactions near walls, providing a foundation for optimizing computational fluid dynamics models and improving industrial applications. Future work should consider additional variables such as particle roughness to further refine predictive capabilities. This study contributes to advancing theoretical and practical insights into non-spherical particle behaviors in complex flow environments.

Visualization Investigation of Heat Transfer Behavior in a Flat-Tube Shaped Heat Pipe

Unveiling the heat transfer behavior of solar collectors in concentrating solar thermochemical energy storage is crucial for harnessing full-spectrum solar light. In this study, a glass Flat Tube-Shaped Heat Pipe (FT-SHP) was developed, and a visualization experimental platform was established to investigate its internal operation mechanisms and heat transfer characteristics. The results revealed that the liquid filling ratio (FR) significantly affects the heat transfer performance, with an optimal value identified as 25%. As the heat flow temperature in the evaporation section increased, both the Bubble Growing Frequency (BGF) and Droplet Condensation Reflux Period (DCRP) decreased, leading to a reduction in thermal resistance. Conversely, an increase in the cooling flow rate resulted in opposite trends in BGF and DCRP within the tube, while both the Reynolds (Re) number and thermal resistance decreased. As such, an empirical correlation between thermal resistance and Re number was derived, demonstrating a nonlinear relationship between thermal resistance, BGF, and DCRP. These findings provide important insights for the design of heat pipes, with the potential to enhance the efficiency and reliability of solar collectors.