Numerical Analysis Of Heat Transfer Research Articles

Expression of concern for article entitled “Numerical analysis of pressure drop and heat transfer of a non-Newtonian nanofluids in a Li-ion battery thermal management system (BTMS) using bionic geometries”

Expression of concern for article entitled “Numerical analysis of pressure drop and heat transfer of a non-Newtonian nanofluids in a Li-ion battery thermal management system (BTMS) using bionic geometries”

Numerical analysis of electrothermoconvection of a dielectric nanofluid in a heated cavity

A numerical analysis of electrohydrodynamic (EHD) flow and heat transfer of nanofluid in a heated rectangular cavity is presented. A two-dimensional (2D) rectangular cavity heated from the bottom is considered. An electric potential difference is applied vertically, with the bottom wall acting as a high-voltage electrode, and the top wall is grounded. TiO2-25 # transformer oil nanofluid with nanoparticle volume fraction ranging from 0–5% is considered. The numerical model for EHD flow and heat transfer of nanofluid is implemented in the finite-volume method (FVM) based numerical framework of OpenFOAM. A single-phase approach based on the effective properties is adopted to model the nanofluids. A two-way coupled EHD flow model is employed to consider mutual interactions of flow and electric field variables. The flow and heat transfer behavior of nanofluids in the presence of an electric field is quantified with reference to the key parameters, electric Rayleigh number (T), and the nanoparticle volume fraction ϕ. The addition of nanoparticles increased the viscosity and marginally reduced the natural convective flow and heat transfer. However, EHD flow induced by the electric field aided in overcoming the weak natural convection flow in nanofluids. Results confirm that nanofluids’ net effective heat transfer rates are notably increased in the presence of the electric field. For the parameters under consideration, combining electric fields with nanofluids led to a significant heat transfer enhancement of up to 32.3%. The present study showcases the feasibility of combining passive heat transfer enhancement using nanoparticles and active heat transfer enhancement using EHD flow.

Numerical analysis of turbulent mixed convection heat transfer of molten salt in horizontal tubes with uniformly cooled heat flux

Molten salt is a widely used heat transfer medium in the field of energy systems. In the engineering design, mixed convection heat transfer often occurs in the high heat flux tube convection heat transfer process, which can significantly change the convective heat transfer capability. However, optimizing the heat exchange conditions can improve the heat transfer capacity of molten salt. In this study, turbulent mixed convection heat transfer characteristics of Hitec molten salt inside horizontal cooling tubes are investigated numerically using the Reynolds stress turbulence model. The results show that the secondary flow caused by buoyancy can lead to significant nonuniform in heat transfer and wall temperature on the wall surface of the horizontal tube cross section. In addition, the buoyancy parameter Bo is selected to characterize the buoyancy effect on Hitec mixed convection heat transfer inside a horizontally cooled circular tube, and within the Bo range from 2.82 × 10−8 to 1.61 × 10−5, as the Bo increases, the relative average Nusselt number for the upper half tube wall gradually increases, the relative average Nusselt number for the lower half tube wall decreases, and the relative average Nusselt number for the entire tube wall shows the combined results of the upper half wall and the lower half wall relative average Nusselt numbers, which slightly increases and then decreases. Furthermore, based on the numerical data, the critical buoyancy parameters Bocr,1 = 10−7 and Bocr,2 = 6.96 × 10−6 at which the buoyancy force starts to affect heat transfer and the average Nusselt number for the entire tube wall starts to decrease are proposed, and variations of the mixed convection heat transfer against the buoyancy parameter Bo are presented respectively for different regions of the horizontal cooling tubes. Based on this research, a reasonable and widely applicable buoyancy parameter selection criterion can be constructed to guide the future engineering designs.

Numerical analysis of heat and mass transfer for forced convection radially magnetized Williamson nanofluid over a curved stretching surface

Present communication investigates the magnetohydrodynamics (MHD) bioconvection Williamson nanofluid with mass and thermal characteristics caused by the swimming of gyrotactic microorganisms subjected to a radially magnetic field and thermal radiation through a curved stretching surface. To emphasize the significance of thermal engineering processes, this novel mathematical model is designed to simulate the transportation of energy through the boundary layer flow of non-Newtonian nanofluid, taking into account the influences of thermophoresis, the density of motile microbes, and Brownian motion. Based on these assumptions, the fundamental governing equations are initially modeled in terms of partial differential equations (P DEs) through boundary layer theory and then formulated into a system of ordinary differential equations (ODEs) by utilizing similarity transformations. The numerical solution for the given nonlinear system, along with their respective boundary conditions, is computed using the BVP4c package in MAT LAB. To comprehensively evaluate the influence of various emerging parameters, results are discussed through graphs and tables for nanofluid’s temperature, concentration profile, local Sherwood number, skin fraction, axial velocity, heat transfer, and distribution of motile microorganisms. The nanofluid’s velocity experiences a decrease with the simultaneous increase of both curvature and magnetic parameters. As a primary finding, the motile microorganism profile exhibits a substantial increase concerning the curvature parameter. Similarly, the nanofluid parameters, including thermophoresis and Brownian motion, along with the radiation parameter, enhance the temperature of the nanofluid.

Numerical investigation and optimisation of solid–solid phase change material composite-based plate-fin heat sink for thermal management of electronic package

Phase Change Material based Thermal Management Systems show promise in electronic packaging systems for safe operation, acting as a thermal storage element to prevent sudden temperature surges, enhancing operational time and mitigating electronic system failures. Therefore, the meticulous design of a solid–solid phase change material (SSPCM) based heat sink with fins is imperative for effective electronic thermal management by improving its safe operational time. This study performs a numerical analysis of two-dimensional transient heat transfer for the SSPCM-based plate-fin heat sink using the modified enthalpy porosity method, where the plate fins serve as Thermal Conductivity Enhancers (TCEs). Neopentyl glycol with 6% (w/w) Copper oxide nanoparticle is used as the SSPCM composite. Enhancement ratio based on safe operational time at different power levels (2–6 W) with different percentages of TCE and fin count recorded variation from 1.32 to 13.7. The TCE integration is more effective at higher power levels. The optimisation of SSPCM-based heat sink design for maximum safe operational time is accomplished through Response Surface Methodology. The significance of the TCE fraction, number of fins, heat generation rate, and interaction effects over the safe operational time are observed. The correlation for safe operational time as a function of TCE volume fraction, fin count and heat generation rate is developed. TCE volume fraction possesses the highest influencing factor over safe operational time at lower and higher power levels compared to fin count. At 2 W and 6 W, a maximum change in safe operational time is observed from 72.7% at 2 W to 83.45% at 6 W. The heat sink with 0.262 volume fraction of TCE and 11 fins is the optimised design that can provide the desirable safe operational time for the tested range of power levels.

Numerical Analysis of Convective Heat Transfer in Quenching Treatments of Boron Steel under Different Configurations of Immersed Water Jets and Its Effects on Microstructure

In this work, the effects of jet impact angle and water flow on the heat-transfer coefficient in boron steel probes were analyzed. Angles of 90°, 75° and 60° were used with stirring flows of 33 l·min−1, 25 l·min−1, 13 l·min−1 and 6 l·min−1. The aim consisted of determining the heat-extraction rates by analyzing the correlation programmed in the Ansys Fluent 2020R2 software when different cooling conditions are used, avoiding many experiments, and establishing quenching conditions free of surface defects on the workpiece. This process is currently used in heavy machinery, requiring high hardness and wear resistance. The fluid-dynamic field was validated using a scale physical model using the particle image velocimetry technique, PIV. In contrast, the thermal field was validated with transient state experiments solving the inverse heat conduction problem, IHCP. The results show that for high flows (33 l·min−1), the jets with an angle of 90° impact the entire surface of the piece, but their cooling rate is slower compared to the other angles, being 243.61 K·s−1, and 271.70 K·s−1, 329.56 K·s−1 for 75° and 60°, respectively. However, for low flows (6 l·min−1), the impact velocities are very similar for the three cases, promoting more homogeneous cooling rates of 58.47 K·s−1, 73.58 K·s−1 and 63.98 K s−1 for angles of 90°, 75° and 60°, respectively. Likewise, through the use of CCT diagrams, it was determined that regardless of the cooling rate, the final structure will always be a mixture of martensite–bainite due to the effect of boron as determined experimentally, which implies a more significant proportion of martensite at higher cooling rates.

Design and heat transfer numerical analysis of high-speed continuous casting mold water slot system

The water slot structure can reduce the temperature of the mold and increase the heat transfer between the mold and cooling water. It has significant impacts on high-speed continuous casting. Therefore, a three-dimensional model of heat transfer from mold to cooling water was used to analyze the influence of water slot size on the cooling capacity of a single water slot. Then, the fluid flow, heat transfer, and solidification three-dimensional models were used to analyze the temperature distribution and cooling effect of three kinds of water slot molds and non-water slot molds. Finally, the water slot mold was designed to achieve high-speed continuous casting. The results show that to make full use of the cooling water in the water slot, the width and height of a single water slot should be less than 8 mm. Compared with the conventional mold without the water slot structure, the temperature of the mold with the water slot structure significantly decreases. The final design of the mold water slot system is as follows: the water slot width and depth are 8 mm, and the number of water slots on one side of the mold is 9. The water slots have a symmetrical distribution, and the symmetrical plane is the middle plane of the mold. The high-speed continuous casting experiment was carried out, and the casting speed can reach 4–4.5 m/min. The water slot mold in this study can be applied in the high-speed continuous casting process.

Numerical Investigation of Hybrid Nanofluid Natural Convection and Entropy Generation in a Corrugated Enclosure with an Inner Conducting Block

Current work deals with a numerical analysis of convective heat transfer and entropy generation inside a rectangular cavity with a corrugated bottom filled with MoS2–SiO2-water hybrid nanofluid. Here, a conducting solid body is attached to the top wall, and discrete heaters are attached to the bottom wall of the cavity. The numerical solutions of the governing equations are derived utilizing a higher-order compact (HOC) finite difference scheme and validated with the existing computational and experimental results. Present numerical results are then studied in detail, emphasizing isotherms, streamlines, and local entropy generation with respect to specific parameters like Rayleigh number (103 ≤ Ra ≤ 106), the volume percentage of nanoparticles (0% ≤ Φ ≤ 4%), the thermal conductivity of solid body (1.95 ≤ ks ≤ 16.00) as well as the aspect ratio of heater length (AR = 0.2, 0.4, 0.6, 0.8). The impacts of key factors on the Bejan number, average Nusselt number, and overall entropy generation are also investigated. The results show that an increase in the thermal conductivity of the solid body from 1.95 to 16.00 increases the average Nusselt number and total entropy generation by 9.17% and 40.07%, respectively, for AR = 0.2, Ra = 106, and Φ = 4%. In addition, the average Nusselt number and total entropy generation decrease by 59.11% and 61.99%, respectively, for ks = 16.00, Ra = 106, and Φ = 4% when the aspect ratio of heater length increases to 0.8.

Artificial neural network (ANN) analysis on thermophysical properties of magnetohydrodynamics flow with radiation in an arc-shaped enclosure with a rotating cylinder

The objective of this research is to examine the thermophysical features of magnetic parameter (Ha) and time step (τ) in a lid-driven cavity using a water-based Al2O3 nanofluid and the efficacy of ANN models in accurately predicting the average heat transfer rate. The Galerkin weighted residual approach is used to solve a set of dimensionless nonlinear governing equations. The Levenberg-Marquardt back propagation technique is used for training ANN using sparse simulated data. The findings of the investigation about the flow and thermal fields are shown. Furthermore, a comparative study and prediction have been conducted on the impact of manipulating factors on the average Nusselt number derived from the numerical heat transfer analysis. The findings of the research indicate that, in the absence of magnetohydrodynamics, a rise in the Hartmann number resulted in a drop in both the fluid velocity profile and magnitude. Conversely, it was observed that the temperature and Nusselt number exhibited an increase under these conditions. The mean temperature of the fluid rises as the Hartmann number drops, reaching a peak value of 0.114 when Ha = 0. The scenario where Ha = 0, representing the lack of magnetohydrodynamics, shows the highest average Nusselt number, whereas the instance with Ha = 45 presents the lowest Nusselt number. The ANN model has a high level of accuracy, as seen by an MSE value of 0.00069 and a MAE value of 0.0175, resulting in a 99% accuracy rate.

Numerical investigation of heat transfer in wire and tube-based phase change material heat exchanger

The utilization of latent heat storage units with their high energy density and isothermal heat transfer behavior can enhance the performance of thermal energy systems. This study aims to investigate the effect of fin placement on the melting time of a wire and tube-based Phase Change Material (PCM) heat exchanger using numerical simulations. The study introduces a new complex geometry for the heat exchanger, and numerical analysis of heat transfer was conducted in Ansys Fluent software using an established solidification and melting model. The numerical results were validated against experimental data, and it was found that the position of the tubes and fins had a significant impact on heat transfer within the PCM. The model was able to predict temperature data with a maximum discrepancy of 3%.

Numerical analysis of heat and moisture transfer in waterproof and breathable composite fabric used for steam protective clothing

A coupled heat and moisture transfer model for waterproof and breathable composite fabrics was developed to examine the behavior of steam heat transfer in porous and hygroscopic membranes. The model accounted for the impact jet flow at outer boundary of fabric, Darcian flow, molecular diffusion, dynamical absorption and phase change of moisture in the fabric. The predictive model was validated by experimental data of hot steam exposure. The heat and moisture distribution in porous and hygroscopic membranes (PM and HM) fabrics was analyzed. The parameters affecting the steam protective performance of waterproof and breathable composite fabric were investigated. The results demonstrated that the HM fabric provided higher steam protective performance than the PM fabric, and placing the membrane on the outer layer of PM and HM fabrics significantly enhanced the steam protective performance. For the PM fabric, the steam protective performance was greatly determined by the thickness and porosity of membrane layer. However, the steam protective performance for the HM fabric was strongly affected by the thickness and thermal conductivity of the substrate layer. The findings obtained in this study can be used to engineer protective clothing that offer better protection against hot steam exposure.

Numerical analysis of the radiative heat transfer and fluid flow between two cylinders using a high-order efficient Probabilists’ Hermite polynomial based collocation method

Radiative effects are useful in physics and engineering, especially in high-temperature operations and space technology. The impact of thermal radiation is important in managing the heat transfer process in the polymer production sector. This work examines the impact of the Soret and Dufour effect on the mass and heat transfer in the fluid flow between two cylinders. The only thing that creates the flow is the inner cylinder extending beneath the motionless outer cylinder. Thermal radiation and nonuniform heat source/sink are also considered. Through the application of similarity transformations, the governing nonlinear differential equations for this flow dynamics are converted into nonlinear ordinary differential equations (ODEs). After that, these simplified equations are solved by applying the collocation method with Probabilists’ Hermite polynomial. The physical behavior of important parameters is examined in depth using graphical representations. The results of a comprehensive examination are presented in tabular data. Result reveals that, the heat, momentum, and mass transfer fields are all significantly impacted by the gap size. As the Dufour number and radiation parameter value grows, the thermal profile also rises. The concentration profile rises as the Soret number values increases, whereas the rise in the Schmidt number shows the reverse pattern.

Numerical Modeling and Analysis of Transient and Three-Dimensional Heat Transfer in 3D Printing via Fused-Deposition Modeling (FDM)

Fused-Deposition Modeling (FDM) is a commonly used 3D printing method for rapid prototyping and the fabrication of plastic components. The history of temperature variation during the FDM process plays a crucial role in the degree of bonding between layers. This study presents research on the thermal analysis of the 3D printing process using a developed simulation code. The code employs numerical discretization methods with an implicit scheme and an effective heat transfer coefficient for cooling. The computational model is validated by comparing the results with analytical solutions, demonstrating an agreement of more than 99%. The code is then utilized to perform thermal analyses for the 3D printing process. Interlayer and intralayer reheating effects, sensitivity to printing parameters, and realistic printing patterns are investigated. It is shown that concentric and zigzag paths yield similar peaks at different time intervals. Nodal temperatures can fall below the glass transition temperature (Tg) during the printing process, especially at the outer nodes of the domain and under conditions where the cooling period is longer and the printed volume per unit time is smaller. The article suggests future work to calculate welding time at different conditions and locations for the estimation of the degree of bonding.

Numerical Analysis of Heat Transfer of Polyethylene Nanocomposites with Carbon Nanotubes

Numerical Analysis of Heat Transfer of Polyethylene Nanocomposites with Carbon Nanotubes

Numerical analysis of reflood heat transfer and large-break LOCA including CRUD layer thermal effects

This study examined the effects of CRUD on reflood heat transfer behaviors of nuclear fuel rods during a loss-of-coolant-accident (LOCA) in a pressurized water reactor using a best-estimate thermal-hydraulic analysis code. Changes in thermal properties and boiling heat transfer characteristics of the CRUD layer were extensively reviewed, and a set of correction factors to reflect the changes was implemented into the code. A heat structure layer reflecting the effects of CRUDs on the properties was added to the outer surface of the fuel cladding. Numerical simulations were conducted to examine the effects of CRUDs on reflood cooling of overheated fuel rods for representative separate and integral effect tests, FLECHT-SEASET and LOFT. In LOFT analysis, the average cladding temperature was increased due to the low thermal conductivity of CRUD during steady-state operation; however, in both analyses, the peak cladding temperature decreased, and the quenching time was reduced. Obtained results revealed that when the porous CRUD layer is deposited on the fuel cladding, two opposite effects appear. Low thermal conductivity of the CRUD layer always increases fuel temperature during normal operation; however, its hydrophilic porous structures may contribute to accelerated reflood cooling of fuel rods during a LOCA.

Heat exchange characteristics of underground and pavement buried pipes for bridge deck heating conditions.

Geothermal energy is increasingly employed across diverse applications, with bridge deck snow melting emerging as a notable utilization scenario. In Jinan city, China, a project is underway to utilize ground source heat pumps (GSHPS) for heating bridges. However, essential operational parameters, including fluid medium, temperature, and heat exchange details, are currently lacking. This study addresses the thermal design challenges associated with ground heat exchangers (GHE) for bridge heating through a combination of numerical modeling and field experiments. Utilizing software Fluent, a refined three-dimensional multi-condition heat transfer numerical analysis was carried out. Field tests based on actual operating conditions were also conducted and the design parameters were verified. The results indicate that an inlet temperature of 5°C and an aqueous solution of ethylene glycol with a mass concentration of 35% as the heat exchange medium are suitable for the GSHPS in Jinan; Moreover, the influence of backfill material and operation time on the heat transfer efficiency was revealed and the suitable material with 10% bentonite and 90% SiO2 was suggested; Finally, based on the influence of the pipe spacing on the heating characteristics of bridge deck, the transition spacing of 0.2 m is given for the temperature response of the bridge deck. This comprehensive study contributes valuable insights through simulation and experimental analysis of the thermal environment variation, aiming to advance the development of GSHPS for bridge deck heating in Jinan, China.

Numerical Heat Transfer Analysis of Evacuated Tube Solar Collector Using MXene/Soyabean Oil Nanofluid

This study focuses on investigating the thermo-hydraulic performance and entropy generation rate of an evacuated tube solar collector using MXene/Soybean oil as a working nanofluid by means of Computational Fluid Dynamics (CFD). A complete 3-D geometry is considered using three different kinds of working fluids (water, soybean oil and MXene/Soybean oil-0.025 wt.%, 0.075 wt.%, and 0.125 wt.%) for five different mass flow rates (0.02475 kg/s, 0.04818 kg/s, 0.0717 kg/s, 0.0952 kg/s, and 0.1188 kg/s) under same solar radiation (925W/m2). The results revealed that MXene/SO-0.125 wt.% at 0.0717 kg/s showed the best thermo-hydraulic performance because it achieves the balance between a high heat transfer coefficient and a low-pressure drop. However, MXene/SO-0.125 wt.% has been shown to have the highest entropy generation rate compared to other loadings because thermal efficiency is directly proportionate to the entropy generation rate. Therefore, the final recommendation for the best working fluid is MXene/SO 0.075 wt.% at 0.4818 kg/s because it attains good thermal efficiency, low entropy generation rate, and when compared to water has shown the highest improvement of 31.1%.

Lattice Boltzmann Simulation of Mixed Convection Around a Heated Elliptic Block Cylinder within a Lid-driven Square Cavity

A numerical analysis of mixed convection flows and heat transfer in a square enclosure having a sliding wall containing an elliptical block heated by isothermal temperature has been carried out. The enclosure is full of air and cooling from its sides by a cold temperature, whereas the remaining walls of the enclosure are considered thermally insulated. The mixed convection impact is attained by the heating elliptic block and moving upper wall. The investigation of fluid’s hydrodynamic and thermal behavior was examined by using Lattice Boltzmann Method (LBM) at different locations and orientations of the interior elliptical block for Richardson number, Ri, varying from 0.01 to 100 while the Rayleigh number, Ra, is fixed at 104. The findings indicate that the temperature pattern and flow structure are very responsive to the position of the elliptical block and Richardson number. Also, it is found that the heat exchange is very important for the block placed vertically close to the left wall or horizontally close to the bottom wall. More precisely, for Ri = 0.01, by moving the vertical block from the center towards the vicinity of the left/ (the right) surface, the heat transfer rate increases from 5.44 to 11.06/(8.36) with an increase of 103.30%/(53.67%). On the other hand, it is noted that the horizontal elliptic block favors heat evacuation in comparison with the vertical one. This study’s real-world impact lies in the potential to improve our understanding and, consequently, design more efficient cooling systems for electronic devices.

Numerical analysis of heat and mass transfer of MHD natural convection flow in a cavity with effects of source and sink

The study of fluid flow and heat transport is found in many engineering applications such as boilers, nuclear plants, thermal energy storage, and underground pipelines. This study focuses on investigating the effects of isothermal source and sink on natural convection and entropy generation for Casson fluids using the finite element method. Under these considerations, fins ensure the effectiveness of heat transfer systems and flow patterns. Results describe that a higher Ra value leads to promote heat and mass transfer while Ha has the opposite impact. By increasing Ha value, results to retard convective heat transfer. As the Lewis number increases, so does the entropy due to deformation and the Bejan number. The shape optimization study about fins is performed in detail. The aspect ratio of cold fins is varied from 1.25 to 7, found that length and width are nearly directly related to entropy, mass, and heat transfer rates. The correlation coefficient for mean Nusselt and Sherwood number versus sink width is 0.9942, very close to 1, showing a very close direct relationship. The linear regression coefficients for mean Nusselt, Sherwood number and total entropy versus sink lengths are (0.7484, 2.2343), (0.7706, 2.254) and (2.4927, 5.8662), respectively.

A numerical analysis of fluid flow and heat transfer between two rotating disks with induced porous medium

In this article, fluid flow between rotating disks is a fundamental topic in fluid dynamics and has various practical applications in engineering and technology. The primary motivation for studying fluid flow between two rotating disk includes its applications in heat exchanger design, generating energy, designing aircraft components like helicopter blades, propellers, wind turbine rotors, fluid pumping, stirring, etc. Authors have considered radially stretching and rotating disks simultaneously under the spiraling motion of a couple stress fluid. This type of motion is developed by radial stretching in addition to the disk’s uniform rotation. This study gives information about the effect of various physical parameters on radial, tangential velocities, and temperature profiles. The similarity transformation resulted in coupled nonlinear ordinary differential equations from the constitutive flow rules of nonlinear partial differential equations. For getting numerical solutions, the authors have used the in-build NDSolve command in MATHEMATICA software, which uses the finite difference method for discretizing and solving differential equations. The outcomes of the above study depict how the fluid flow pattern between the rotating disks is affected by Darcy’s parameter, and other parameters, like Prandtl number, rotation parameter, stretching parameter, couple stress parameter, etc. on the flow, have been thoroughly analyzed, with the physical relevance illustrated. Radial and tangential velocity profiles decrease whenever the Darcy parameter increases. An increase in rotation parameter enhances the radial and tangential velocity due to rotation of the disks.