Heat Transfer Analysis Method Research Articles

Heat transfer characteristics and stress analysis of a new tundish with vacuum chambers

Vacuum insulation can improve tundish insulation performance while increasing molten steel temperature. The tundish's heat transfer characteristics and thermal stress changed significantly following vacuum modification. A complete understanding of this process can improve the insulation and safety performance of vacuum tundishes. The heat transfer process and stress distribution of a tundish were investigated in this study using a fluid–structure coupling heat transfer analysis method. The variations in the temperature and stress fields of the tundish before and after vacuum modification were discussed, and the numerical model’s accuracy was validated using industrial experiments. Compared to the traditional tundish, the temperature distribution of the molten steel was more uniform; the outlet temperature of the vacuum tundish increased by 1.38 K, whereas the temperature of the outer wall decreased by 46 K. However, the higher temperature of the steel shell in the vacuum tundish resulted in an increase in thermal stress, which reached a maximum of 301.74 MPa. When high-strength Q345 steel was used as the steel shell material, the thermal stress decreased to 272.44 MPa. The results showed that a vacuum tundish can achieve low-superheat pouring of molten steel, and the thermal stress of the tundish can be improved by material selection.

Scrutinization of BVP Midrich Method for Heat Transfer Analysis on Various Geometries in the Presence of Porous Medium and Thermal Radiation

The importance of water, copper, and aluminium can have several applications in various industries and everyday life. Their unique properties make them valuable materials for a wide range of purposes. These applications demonstrate how water, copper, and aluminium play vital roles in ensuring the availability, safety, and efficiency of water-related processes and systems. Their specific properties make them suitable for various functions within the water industry, from transportation and heating to treatment and power generation. Based on the importance the current investigation aims to explore the significance of magnetic field and porous medium and Cu–Al2O3 hybrid nanofluid flow through three distinct geometries. The fluid transport equations were transformed into ordinary differential equations by using self-similarity variables. These equations were subsequently solved by using the Maple built in BVP Midrich scheme. The results are presented in a variety of graphical formats, including a two-dimensional plot, contours, and streamlines, this research demonstrates how numerous dynamic variables may alter the transport properties of a fluid in a number of approaches. Throughout all the investigated geometries, the velocity profile exhibits a decreasing nature for increasing the porosity parameter values and temperature profile display an increasing trend for higher values of the thermal radiation parameter. An increase in the heat generation corresponds to a rise in the nanofluid temperature. Similarly, the nanofluid velocity decreases with higher velocity magnetic field parameter values, while the fluid temperature exhibits opposite behavior, increasing with increasing magnetic field parameter values. Compared to nanofluids, hybrid nanofluids have a better heat transfer rate. Hybrid nanofluids are used in a variety of applications due to their excellent thermal properties, so it is used for nuclear reactor cooling, water purification industry, and vehicles.

Functional fatigue of superelasticity and elastocaloric effect for NiTi springs

In this work, the evolutions of superelasticity (SE) and elastocaloric effect (eCE) for NiTi shape memory alloy (SMA) helical springs under cyclic deformation are investigated experimentally and theoretically. Experimental results show that the functional fatigue of SE and eCE occur simultaneously, and these phenomena aggravate significantly with the increase/decrease of the loading level/spring index. Then, a thermo-mechanically coupled constitutive model is established. Two major inelastic deformation mechanisms, martensitic transformation (MT) and transformation-induced plasticity (TRIP), are incorporated. In addition to the martensitic and austenitic phases, the martensitic influence zone is also considered in the proposed constitutive model to characterize the high local stress in the region near the austenitic-martensitic interface. To accurately describe the deformation behavior of NiTi SMA springs, an analytical model considering both the torsion and bending deformation modes is employed. Furthermore, the lumped heat transfer analysis method is adopted to derive the evolution equation for the overall temperature of the springs. Finally, to verify the rationality of the newly developed model, predicted results for the functional fatigue of SE and eCE are compared with the experimental data.

Study on the deposition migration and heat transfer characteristics in the reactor core based on OpenFOAM

Corrosion deposition in heat exchangers may lead to a reduction in heat transfer efficiency, and even can affect equipment operational safety. Traditional CFD deposition heat transfer analysis methods are limited by model size, making it difficult to obtain global, long-term deposition heat transfer characteristics for complex heat exchange equipment. In this paper, a corrosion product deposition prediction and heat transfer model based on sub-channel analysis is proposed. By integrating it into the nuclear reactor core thermal–hydraulic characteristics analysis code CorTAF, which is developed on the OpenFOAM platform, the corrosion deposition and heat transfer calculation for the entire reactor is achieved. A numerical simulation of the deposition and heat transfer of the AP1000 reactor core during a 300-day operation is conducted. The calculation results clearly show the distribution of corrosion products in the reactor core and the temperature changes of the fuel cladding with the deposition days: the maximum deposition thickness on the core cladding surface is 38.3 μm, and the highest temperature increase is 11.0 K. The deposition and cladding temperature rise distribution is not linear with operation time but is closely related to the core power distribution. The modeling method successfully obtains the corrosion deposition and heat transfer characteristics of the entire reactor core, and has potential implications for the prediction of corrosion deposition distribution and thermal effect calculations in other large-scale heat exchange equipment.

Inverse Heat Transfer Analysis Method to Determine the Entropic Coefficient of Reversible Heat in Lithium-Ion Battery

An entropic coefficient of reversible entropic heat is a key parameter in determining the battery thermal responses, but its measurement is challenging due to time consuming and inaccurate traditional methods. In this regard, an analytical approach based on the inverse heat transfer problem is newly proposed to precisely determine the entropic coefficient with low experiment cost. Experiments are conducted by discharging the battery under four different current rates to inversely estimate the entropic coefficients, and the least squares regression are conducted to optimize the derived entropic coefficients. Through the comparison with the existing potentiometric method, the experimental time can be reduced by 93.7%. Furthermore, the accuracy of the proposed method is well verified by validating within the root mean square error of 0.848°C by comparing with the experimental results. Through the validation processes under various operating conditions, such as low to high current rates, charging process, dynamic loads, and different ambient temperatures, the proposed method is proven over temperatures ranging from 10°C to 60°C. Conclusively, the proposed method can be a great alternative to replace the classical experimental methods.

Heat transfer analysis in thermal energy storage—A comprehensive review‐based latent heat storage system

AbstractThermal energy storage (TES) system is the most eminent storage method that aids in the power generation. Latent heat storage (LHS) is on the rapid mark‐up that fosters the TES with the utilization of the phase transition of a material to store the heat. Typically the phase change materials (PCM) are used in the LHS system to store the energy. During the material's phase transition, thermal energy is stored and released. Nevertheless, the low thermal conductivity of the PCM in the LHS is susceptible to deteriorate the charging and discharging of the thermal energy. Hence there is a necessity to enhance the thermal performance of the LHS system, on which various studies have been done. Therefore this paper aims in providing a review on the enhancements of the LHS system with improved heat transfer rate and heat transfer enhancement techniques in the PCM for better efficiency. A comprehensive review on the LHS system component is provided to make an emphasis on the heat transfer enhancement rate and storage time. Various characterizations and categories of the PCM are provided to intensify the outcomes of the review as PCMs are most viable materials for storing thermal energy. In addition the recent researches on the integration of PCM with other materials are also discussed that help in the improvements of the thermal conductivity of the PCM. The selection parameters of the PCM materials are also discussed in brief to avoid the poor performance of the PCMs. The heat transfer analysis methods are analyzed to improve the efficiency and reduce the heat loss. Finally, advancements in the future trends for the enhancement of heat transfer is provided.

Symmetric Heat Transfer Pattern of Fuel Assembly Subchannels in a Sodium-Cooled Fast Reactor

The method outlined in this paper is convenient and effective for studying the thermal performance of fuel assemblies cooled with sodium fast reactors using the subchannel procedure. To initially study an optimization model for a symmetric single fuel assembly heat transfer pattern analysis in a fast sodium-cooled reactor based on subchannel calculations, this paper innovatively proposes a subchannel heat transfer analysis method with the entransy dissipation theory, which can solve the limitations and inaccuracies of the traditional entropy method such as poor applicability for heat transfer processes without functional conversion and the paradox of entropy production of heat exchangers. The symmetric distributions of the thermal-hydraulic parameters such as coolant flow rate, coolant temperature, cladding temperature, and fuel pellet temperature were calculated, and the entransy dissipation calculation method corresponding to the fuel assembly subchannels was derived based on the entransy theory. The effect of subchannel differences on the thermal-hydraulic parameters and the symmetric distribution pattern of entransy dissipation during the cooling process of the fuel assembly was analyzed and compared from the symmetrical arrangement of subchannels in the axial and radial directions.

Data-Driven Conjugate Heat Transfer Analysis of a Gas Turbine Vane

Cooling structures of gas turbine blades have become more complex to achieve a better cooling effect. Therefore, heat transfer analysis tools with higher accuracy and efficiency are required to verify the effectiveness of cooling designs and continuously improve the design. In this work, a data-driven method is combined with a decoupled conjugate heat transfer analysis. The analysis object is a typical air-cooled gas turbine first-stage vane with film cooling, impingement cooling, and pin-fin cooling. In addition, a conventional 3-D conjugate heat transfer simulation of the vane was executed for contrast. Results show that this method shortens the time of the heat transfer analysis process significantly and ensures accuracy. It proves that the data-driven method is effective for the evaluation of a modern gas turbine cooling design and is an improvement compared to the traditional three-dimensional heat transfer analysis method.

Numerical simulation and ultrasonic measurement on welding residual stresses of full penetration U-shaped stiffening ribs

In order to study the distribution of welding residual stresses in single-sided and full penetration double-sided welded U-ribs, numerical and experimental investigations were carried out considering different deck thicknesses. The birth–death element technique and the heat transfer analysis method were utilized to obtain the welding temperature field and the stress field. The accuracy of the numerical simulation was verified by using the ultrasonic method and the hole-drilling method. The proposed formulas of residual stresses as a function of the weld length in full penetration double-sided welded U-ribs were regressed. The results show that the stress distribution of double-sided welded U-ribs is consistent with that of single-sided welded U-ribs, but double-sided welded U-ribs produce more complex and adverse residual stresses. With the increase of deck thickness, the peak value of the residual stresses in the weld has no significant change and is stable at about 380 MPa. But the residual stresses in the region around double-sided U-rib welds are generally larger than those of the single-sided U-rib welds, and they decrease with the increase of the deck thickness. When the thickness increases to 18 mm, the maximum decrease reaches about 80 MPa. In addition, the calculation errors of new formulas are very small. The accuracy and reliability of numerical simulation results has been verified.

Performance Parameter Analysis of Thermoelectric Generators for Power Generation System from the Scramjet Cooling Heat

Thermoelectric generator (TEG) for power generation system is proposed for energy recovery. The heat from cooling scramjet would be converted to electric energy. A parametric study of TEGs power generation system for heat recovery has been performed. The output power, the efficiency and the fuel flow saving ratio of the system have been analyzed and the proposed heat transfer analysis method of the system is depicted.

Non-Fourier heat conduction analysis of a 2-D plate with inner cracks at arbitrary direction angles

This paper investigates the problem of a 2-D plate containing internal cracks at arbitrary angles to the heating surface under thermal shock. The finite difference method is applied to solve the temperature distribution and a difference scheme of the oblique crack is developed. For the first time, a non-Fourier heat transfer analysis method of a 2-D plate with inner cracks at arbitrary direction angles is established. Specifically, for a strip with an inner crack paralleling to the surface, numerical results are compared with the analytical solutions by rotating the boundary, and perfect agreement is obtained. Numerical experiments are further presented to investigate the influence of crack orientation angle and multi-crack distribution on non-Fourier heat conduction.

Heat Transfer Scale Effect Analysis and Parameter Measurement of an Electrothermal Microgripper.

An electrothermal microgripper is an important actuator in microelectromechanical and micro-operating systems, and its temperature field analysis is the core problem in research and design. Because of the small size of an electrothermal microgripper, its microscale heat transfer characteristics are different from those of the macrostate. At present, only a few studies on the heat transfer scale effect in electrothermal microgrippers have been conducted, and the heat transfer analysis method under the macrostate is often used directly. The temperature field analysed and simulated is different from the actual situation. In the present study, the heat transfer mechanism of an electrothermal microgripper in the microscale was analysed. The temperature field of a series of microscale heating devices was measured using microthermal imaging equipment, and the heat transfer parameters of the microscale were fitted. Results show that the natural convective heat transfer coefficient of air on the microscale can reach 60–300 times that on the macroscale, which is an important heat transfer mode affecting the temperature field distribution of the electrothermal microgripper. Combined with the finite element simulation software, the temperature field of the electrothermal microgripper could be accurately simulated using the experimental microscale heat transfer parameters measured. This study provides an important theoretical basis and data support for the optimal design of the temperature controller of the electrothermal microgripper.

An adaptive Bernstein-Bézier finite element method for heat transfer analysis in welding

We present a Bernstein–Bézier finite element method with local mesh refinement to simulate the heat transfer problem in the welding process. A novel constraint method is formulated to handle the incompatible degrees of freedom associated with the transitional elements during the local quad-tree/oct-tree refinement. A dynamic refinement strategy is proposed with a local L2 projection approach to transfer the control variables between different meshes, which enables the reduction of the model size, on the premise that good accuracy of the solution around the heat source is obtained. The cladding process during welding is simulated by the element addition technique. Exactness of the geometry is preserved by use of the rational form of the basis functions, which avoids frequent communication between the CAD and simulation when refining the mesh locally. The proposed method is investigated through examples, including convergence studies and industrial applications. The numerical results obtained using the proposed method and serendipity finite elements are compared in terms of accuracy and efficiency, revealing the potential of the proposed method for welding analysis.

Evaluation of mesh dependence of combined heat transfer analysis method of radiation and convection field using OpenFOAM

Evaluation of mesh dependence of combined heat transfer analysis method of radiation and convection field using OpenFOAM

An element decomposition method for heat transfer analysis

In this work, an element decomposition method (EDM) is formulated to deal with heat transfer analysis. For this method, the quadrilateral elements are first divided into sub-triangular cells and the local temperature gradient in each sub-triangular cell is obtained using linear interpolation function. Then, the temperature gradient of whole quadrilateral can be calculated by averaging the local gradient in each sub-domain. As only one integration point is utilized for each element, the computational cost of presented method is much less and no mapping or coordinate transformation is involved. Several numerical examples are given to fully test the validity of this method and it is found that the EDM is very accurate, stable and can achieve high level of convergence when solving heat transfer problems.

Radiative Heat Transfer Analysis Method for Coupled Simulation of Convection and Radiation in Large-Scale and Complicated Enclosures : Part 1-Accurate Radiative Heat Transfer Analysis based on Monte Carlo Method

Radiative Heat Transfer Analysis Method for Coupled Simulation of Convection and Radiation in Large-Scale and Complicated Enclosures : Part 1-Accurate Radiative Heat Transfer Analysis based on Monte Carlo Method

Radiative Heat Transfer Analysis Method for Coupled Simulation of Convection and Radiation in Large-Scale and Complicated Enclosures : Part2-Analysis of Thermal Environment around Human Body Model with Realistic Shape and Size

Radiative Heat Transfer Analysis Method for Coupled Simulation of Convection and Radiation in Large-Scale and Complicated Enclosures : Part2-Analysis of Thermal Environment around Human Body Model with Realistic Shape and Size

Optimal design of thermal loaded composites filled with curvilinear fibers

The problem of optimal design of shape and orientation of fibers in composite material, leading to the local inhomogeneity of its parameters, is considered in this paper. The paper concerns the problem of curvilinear fibers arrangement in the composite material, so that the structural element made from this material can fulfill the requirements imposed on its thermal properties. An equivalent homogeneous orthotropic model of the composite is utilized for this purpose and next, basing on this model, the attempt is taken to determine the most profitable orientation and arrangement of fibers in the layers of the composite in order to obtain the desired behavior of structure. To solve this problem, the optimization method based on evolutionary algorithm is applied, and it is supplemented with finite element method for heat transfer analysis.

Simplified heat transfer analysis method for large-scale boreholes ground heat exchangers

A simplified heat transfer method to analyze the thermal performance of large-scale boreholes ground heat exchangers (GHE) has been proposed considering the geometric symmetry of borehole layout. Taking the ground heat exchanger with matrix layout of vertical boreholes as the example, the ground temperature distribution is analyzed under the conditions of no groundwater advection by the proposed simplified method. Based on the simulation results, a representative boreholes matrix can be proposed to replace the original large-scale ground heat exchanger for heat transfer analysis. Meanwhile, the results show that the representative boreholes matrix can be determined by the thermal influence radius of a single borehole by assuming all the boreholes have the same thermal loads and also in the same geological conditions, geometry parameters and operating conditions. It is indicated that the thermal influence radius of a single borehole can be obtained according to the allowed error range of the ground temperature responses, which can correspondingly determine the number of the representative boreholes matrix.

Vertex Combination Method for Heat Transfer Analysis of Structures with Uncertain Parameters

Uncertainty is wide-spreads in practical projects which can be solved by interval method. Regarding the temperature field prediction of structures with uncertain parameters, a vertex combination method is presented on the basis of the sampling according to the vertex combinations of interval parameters and monotonic relationship of objective function which can effectively reduce the number of boundary combined samples. A numerical example of heat transfer problems of a panel without thermal resource is used to verify the effectiveness of the proposed method.