Analytical Thermal Model Research Articles

An enhanced analytical and numerical thermal model of frictional clutch system using functionally graded materials

Abstract When a component was built from a functionally graded material (FGM), the temperature of contact was determined using an analytical model (FGM). The analytical solution is applied using the concept of equivalent properties. In order to fully examine the dynamic of the equivalent property principle, a numerical analysis was done. The FGM (silicon carbide and aluminum) friction liner was used. It focuses on a few characteristics that have an impact, such as load, velocity, friction material type, and slip time, which appear in dimensionless form. The results show that for loads and velocities, the ratio of the rate of dissipation to the rate of generation of heat transfer is one, whereas the behavior differs for friction material and slip time. Furthermore, this study’s chosen FGM exhibits superior thermal behavior compared to Al and Sic, bolstering its viability as a friction liner in the clutch system.

A fractal model for thermal analysis of newtonian fluid to forecast thermal behavior

A fractal model for thermal analysis of newtonian fluid to forecast thermal behavior

Development of Low-Pressure Die-Cast Al-Zn-Mg-Cu Alloy Propellers Part II: Simulations for Process Optimization.

With the increasing demand for high-performance leisure boat propellers, this study explores the development of high-strength aluminum alloy propellers using the low-pressure die-casting (LPDC) process. In Part I of the study, we identified the optimal alloy compositions for Al-6Zn-2Mg-1.5Cu propellers and highlighted the challenges of hot tearing at the junction between the hub and blades. In this continuation, we developed a coupled thermal fluid stress analysis model using ProCAST software to optimize the LPDC process. By adjusting casting parameters such as the melt supply temperature, initial mold temperature, and curvature radius between the hub and blades, we minimized hot tearing and other casting defects. The results were validated through simulations and practical applications, showing significant improvements in the quality and structural integrity of the propellers. Non-destructive testing using X-ray CT confirmed the reduction in internal defects, demonstrating the effectiveness of the simulation-based approach for alloy design and process optimization.

Transient thermal analysis model of nitrogen-cooled cryogenic system for superconducting electromagnetic suspension magnet

This paper proposes a transient thermal analysis model for a nitrogen-cooled cryogenic system used in superconducting electromagnetic suspension magnets. First, the structural parameters of the nitrogen cryogenic system and the internal high-temperature superconducting magnet are detailed. Subsequently, temperature change simulations during the system's cooling process using a cryocooler, as well as during the cooling and nitrogen-insulation process, were conducted using COMSOL software. Finally, simulations of the temperature variations during the system's offline operation were performed. This study provides valuable references for the design and optimization of nitrogen-cooled cryogenic systems.

Pulse approach: a physics-guided machine learning model for thermal analysis in laser-based powder bed fusion of metals

Pulse approach: a physics-guided machine learning model for thermal analysis in laser-based powder bed fusion of metals

MAF process for aluminum 6060: An analytical temperature modelling and chemo-mechanical analysis

The magnetic abrasive finishing process is a sophisticated micro-finishing process that enhances the surface quality of superalloys, ceramics, and composites. Surface temperature plays a pivotal role in facilitating chemo-mechanical reactions between the processed surface and abrasive particles. In triggering the chemo-mechanical response of the micro-finished surface of Aluminum 6060 (Al-6060), an analytical thermal model derived using Jaeger moving heat formulation to find the flash temperature (FT) and flash time duration (FTD) at the micro-finishing interface of the processed workpiece and the abrasive particles of the magnetic abrasive brush. Furthermore, the present work performed an RSM-based Box Behnken design experiment to analyse and explain the crucial role of machining gap, abrasive weight, Voltage, and rotational speed on surface temperature, machining surface, and hardness. ANOVA highlighted key factors in machining responses. Surface roughness and temperature were notably influenced by voltage (58.42 % and 57.62 %, respectively), while surface hardness primarily depended on abrasive weight (60.65 %). Using the developed model, extreme FT of 880 °C and 810 °C were calculated under specific conditions, along with corresponding FTD required for quasi-steady-state conditions. FT and FTD were identified as sufficient for initiating chemo-mechanical action in the MAF micro-finishing process, depending on contact pressure, the number of abrasive particles, and sliding velocity, which in turn are influenced by magnetic intensity, abrasive ratio, and rotational speed. Furthermore, a detailed examination of the finished surface was carried out using the SEM, EDS and XRD of Al-6060 which shows that the SiC does participate on the finishing surface. Chemical substrates such as Kaolinite (Al2O9Si2), Iron silicide (FeSi), and Cristobalite (O2Si) had formed on the finished surface of Al-6060 due to the chemo-mechanical action between the SiC and workpiece material.

Lifetime thermal analysis of the CANDU spent fuel storage canister at the Wolsung site

CANDU spent fuels in the Wolsung site have been stored in dry storage systems, such as concrete canisters and modular air-cooled storage system. The primary role of the canister is to ensure the integrity of the fuel during the storage period, which is significantly influenced by temperature. Thus, thermal analysis for the canister's components, especially for fuel cladding, is essential to demonstrate its safety. The thermal analysis has been conducted mainly for predicting the peak cladding temperature (PCT) since high temperature of the fuel can promote oxidation and cracking. As the expiration of storage license approaches, fuel transfer to final disposal should be prepared. This also requires a thermal analysis to predict minimum cladding temperature (MCT), which is related with brittleness. So, it is crucial to accurately predict both PCT and MCT during entire storage period. The cladding temperature is primarily influenced by decay heat and ambient conditions. The lifetime PCT may occur during summer at the beginning of storage, while the lifetime MCT occurs during winter at the end of storage. In this study, we calculated the PCT and MCT during the entire storage period using a realistic thermal analysis model and, subsequently, conducted their uncertainty analysis.

Integrating PEM fuel cell control with building heating systems: A comprehensive thermal and control model analysis

Integrating PEM fuel cell control with building heating systems: A comprehensive thermal and control model analysis

An Experimental Investigation Of Local Thermo-Fluidic Heat Transfer In A U-Shaped Mini-Channel Sink

This study investigates experimentally a heated U-shaped mini-channel heat sink using Infrared Thermography and Particle Image Velocimetry for a water coolant flow of Reynolds numbers of 280, 650, and 1350 (based on the hydraulic channel diameter). The choice of this cell geometry is based on its role as a simplified unit of a serpentine heat exchanger, which is proved to be one of the most promising for cooling processes. The use of the infrared camera allows the detection of temperature fields on top of the external surface of the cell. Therefore, aiming to derive the temperature distribution on the channel roof, a dedicated transfer function is implemented. Moreover, we employed the lumped capacitance model for thermal analysis on both infrared measurements and thermocouple data. The latter are recorded to capture the cooling process of the aluminium base and water temperature at the end of the outlet tube. As a result, thermal transient rate, cooling magnitude and equilibrium temperature are obtained. These parameters indicate that higher Reynolds numbers correspond to increased thermal transient rates, enhanced cooling effects, and lower equilibrium temperatures. A non-uniform distribution of heat transfer along the channel is reported, with the most efficient cooling area localized close to the first 90-degree corner. These findings are consistent with numerical simulations and previous experimental observations. PIV results reveal the presence of two fluid acceleration zones following both 90-degree corners, which contribute to improve the water cooling ability in their respective regions. Additionally, the formation of two recirculating bubbles is reported at the inner wall from corners vertices, whose intensity is dependent on Reynolds number, pushing the main flow towards the outer channel wall and reducing the local heat transfer. Turbulent kinetic energy distributions are also investigated, pointing out the presence of intense areas that better match with regions of minimum equilibrium temperature than maximum velocity zones. This suggests the presence of local turbulent unsteadiness and three-dimensional phenomena, which contributes significantly to cooling enhancement.

Effect of boron on the microstructure and performance of HIP-prepared high boron steels

High boron steels containing 2 wt% and 3.3 wt% boron were fabricated using hot isostatic pressing (HIP). The enhanced shielding performance of the steel with higher boron content was quantitatively evaluated through Monte Carlo simulations using software Fluka. The steels were studied with XRD and the phase ratio were calculated using Rietveld refinement method. The microstructure of the materials was investigated using electron backscatter diffraction (EBSD). Comprehensive thermal property measurements, complemented by Hamilton thermal conductivity model analysis, were conducted on high boron steels. The results revealed that the decreased overall thermal conductivity in these materials is primarily attributed to two factors: the increased volume fraction of the boride phase and the enhanced interconnectivity among boride particles. These findings provide crucial insights into the thermal behavior of high boron steels. Room temperature tensile tests indicate that high boron content can cause the fracture mode of the material to transition from ductile to brittle. This study provides a detailed analysis of the effects of boron content on various properties of high boron steels, which can serve as shielding materials in fusion reactors. Advances were proposed for optimizing the thermal performance of high boron steels in this study.

Thermal Analysis of Power Transformer Using 2D and 3D Finite Element Method

An accurate simulation and computational analysis of temperature distribution in large power transformers used in power plants is crucial during both the design and operational phases. This study introduces a thermal modeling analysis encompassing two- and three-dimensional (2D and 3D) approaches for power transformers. The mathematical model for heat diffusion follows the Finite Element Method (FEM) approach. Validation of the computed results involves comparing them against measurements from Hyundai’s test report for both 2D and 3D models, aiming to identify the most effective solution. Additionally, the thermal dynamics of power transformers under diverse operational conditions, specifically oil-immersed ones, are examined. The efficacy of this model is confirmed through testing on a step-up transformer at Kureimat station in Egypt, with specifications including three-phase, 50 Hz, 16.5/240 KV, nine taps, and cooling type (ONAN/ONAF1/ONAF2).

Development and testing of an automated tool to leverage building energy models for thermal resilience analysis

Unlike building energy use analysis, thermal resilience analysis to understand how buildings perform during disruptive events has not been widely adopted or standardized. To ensure best practices are applied consistently, this paper proposes a new automated toolbox to leverage building performance models developed for energy analysis purposes, for thermal resilience analysis. To demonstrate the functionality and robustness of the toolbox for automating the analysis and reporting of thermal resilience, example simulations are completed with models gathered from different sources. Major contributions from this study include the establishment of a standardized transparent simulation framework for thermal resilience analysis, as well as the proposal of techniques for overcoming challenges associated with a diversity of model sources including different modelling habits/preferences by modellers and different versions of EnergyPlus. Recommended future work includes the development of standardized modelling configurations reflecting extreme events; the inclusion of more comprehensive metrics, and the refining analytics report through consultation with stakeholders.

Reynolds number based optimization on liquid cooling system for permanent magnet synchronous motor of electric vehicle

The electric motor thermal management system (TMS) is a pivotal unit for electric vehicles (EVs). To study the factors affecting cooling performance and cooling efficiency of spiral housing water jacket (HWJ), simulations were carried out on a 150 kW jacked-cooled permanent magnet synchronous motor (PMSM) with ethylene glycol & water (EGW) as coolant. The coupling between channel numbers (N) and coolant flow rate (Q) on winding average temperature (T) and pressure drop (P) were investigated focusing on the Reynolds number (Re) via analytical and numerical thermal models. The results indicated that the cooling performance was nearly the same for coolant under fully turbulent. Both the cooling performance and cooling efficiency were not conducive when N > 8, and meanwhile, N < 6 also hindered the heat extraction. Resorting to the investigation, a Re-based multi-objective optimization algorithm was put forward. Compared the optimized jacket N6Q12 (denoting 6 channels with 12 L per minute flow rate) with the sub-optimized N12Q6 at the same Re, winding average temperature T was found 6.5 deg C lower, and pressure drop P was reduced by up to 71.6 %.

A two-phase flow node-solid joint simulation algorithm based on heat flow correction

In order to accelerate the temperature field calculation of fuel and tank wall protective materials, we propose a node-solid joint simulation method based on heat flow correction, in which the gas–liquid is used as a node for joint CFD (Computational Fluid Dynamics) calculation of the solid temperature field. Based on this method, we constructed a transient thermal analysis model of the fuel tank and performed a gas–liquid–solid conjugate heat transfer tight coupling simulation to obtain the wall heat transfer coefficient and the corrected heat flux under the specified thermal boundary conditions. The results show that the maximum relative errors of the average temperature of the gas–liquid node and the temperature field of the tank wall are less than 0.2 % and 6 %, respectively, and the calculation efficiency is about 160 times that of the traditional tight coupling calculation. When the solid boundary temperature is reduced by 200 K and increased by 500 K, the maximum relative error between the average temperature of the gas–liquid node and the solid temperature is less than 7 %. The algorithm has good robustness and accelerates the iterative design of the fuel tank. The accuracy of the algorithm was verified by the fuel temperature test experiment of the full flight profile.

Thermal buckling analysis of nano composite laminated and sandwich beams based on a refined nonlocal zigzag model

A refined nonlocal zigzag model for thermal buckling analysis of nano composite laminated and sandwich beams is proposed in this study based on a refined zigzag theory and Eringen’s nonlocal theory. Firstly, present model satisfies the stress-free and continuity conditions a priori by introducing the piecewise-linear zigzag functions and a preprocessing, such that the transverse shear correction factors are not needed. In the preprocessing, accurate and continuous transverse shear stresses are obtained with the aid of the general mixed variational principle, which can be solved simultaneously with other stresses in the governing equations. This is quite different from the previous post-processing. Subsequently, thermal buckling problems of nano composite laminated and sandwich beams are analytically solved in simply supported boundary conditions. The degenerated results without small effect indicate that the non-dimensional critical loads and critical temperatures have a good agreement with the 3D elasticity solutions and previous results, which demonstrate the accuracy and reliability of present model. Moreover, it is observed that the small effect of the critical temperatures can be effectively captured by Eringen’s differential constitutive law (EDCL), which shows the small effect decreases the critical temperature by weakening the stiffness of the beam. Finally, the effects of different thermal expansion coefficients, laminations, geometric sizes and beam theories are discussed. The results show that present model is robust in the arbitrary layouts for both of composite and sandwich structures, which may have some referential significance to Micro-Electro-Mechanical Systems (MEMS) sensors and actuators.

Analytical and FEM models for thermal analysis and residual stresses using wire arc-based welding and additive manufacturing of SUS304

Analytical and FEM models for thermal analysis and residual stresses using wire arc-based welding and additive manufacturing of SUS304

Enhancing thermal management efficiency in robotics engineering: Exploring mechanisms, techniques, and modeling approaches

Thermal management is pivotal in robotics engineering, ensuring optimal performance and reliability of robotic systems. This comprehensive review explores various heat dissipation mechanisms, cooling techniques, and thermal modeling approaches employed in robotics engineering. Key topics include conduction-based, convection-based, and radiation-based heat transfer mechanisms, alongside liquid cooling, air cooling, and phase-change cooling techniques. Analytical thermal models, computational fluid dynamics (CFD) simulations, and finite element analysis (FEA) modeling are discussed for their roles in predicting thermal behaviors and optimizing heat dissipation strategies. By synthesizing these advancements, this review provides valuable insights into enhancing thermal management efficiency and ensuring the longevity of robotic systems.

A numerical study on thermal-structural characteristics of cryogenic common bulkhead propellant tanks for various tank lengths and core thicknesses

Common bulkhead (CBH) propellant tanks have the advantage that its structural and space efficiency are high. The tank is a form in which an oxidizer tank and a fuel tank are integrally combined, and the oxidizer and fuel are separated by the CBH. The CBH propellant tank in which two tanks are integrated can reduce unnecessary space between the two tanks. However, there are other difficult problems regarding effectively designing the CBH propellant tanks even though there are structural and space benefit. This paper is a study on the thermal-structural characteristics of CBH tanks containing LOX/LH2 propellant. In order to conduct the thermal-structural analysis, the thermal analysis model was constructed using 2-dimensional axisymmetric elements to reflect the shape features of the tank, and the structural analysis model was built using 3-dimensional elements. The thermal-structural analysis was performed on the length of the bottom tank and the foam core thickness of the CBH. In the structural analysis of the tank, when the thermal load was ignored and only the pressure load was applied, there was a difference in the buckling load factor depending on the thickness of the CBH foam core, but as the thermal load was taken into consideration, there was also a difference in the bottom tank length. The analysis results show that the thermal-structural characteristics of the CBH propellant tank were influenced by the length of the bottom tank as well as the thickness of the foam core.

Gene expression programming (GEP) as novel tool for thermal analysis and kinetic modeling of pyrolysis reactions: coal pyrolysis case study

PurposeIn this study, a different approach is introduced to generate the kinetic sub-model for the modeling of solid-state pyrolysis reactions based on the thermogravimetric (TG) experimental data over a specified range of heating rates. Gene Expression Programming (GEP) is used to produce a correlation for the single-step global reaction rate as a function of determining kinetic variables, namely conversion, temperature, and heating rate.Design/methodology/approachFor a case study on the coal pyrolysis, a coefficient of determination (R2) of 0.99 was obtained using the generated model according to the experimental benchmark data. Comparison of the model results with the experimental data proves the applicability, reliability, and convenience of GEP as a powerful tool for modeling purposes in the solid-state pyrolysis reactions.FindingsThe resulting kinetic sub-model takes advantage of particular characteristics, to be highly efficient, simple, accurate, and computationally attractive, which facilitates the CFD simulation of real pyrolizers under isothermal and non-isothermal conditions.Originality/valueIt should be emphasized that the above-mentioned manuscript is not under evaluation in any journals and submitted exclusively for consideration for possible publication in this journal. The generated kinetic model is in the final form of an algebraic correlation which, in comparison to the conventional kinetic models, suggests several advantages: to be relatively simpler, more accurate, and numerically efficient. These characteristics make the proposed model computationally attractive when used as a sub-model in CFD applications to simulate real pyrolizers under complex heating conditions.

Research on thermal characteristics modeling of CNC machine tools based on submodel method

To improve the accuracy of thermal characteristics analysis of CNC machine tools, a modeling method for the thermal characteristics of CNC machine tools based on submodel method is proposed in this paper. In this method, the thermal-structural coupling calculation of the feed system and spindle system is initially completed in ABAQUS to obtain temperature and deformation results of the submodels. Subsequently, User Define Function (UDF) in Fluent is used to extract the temperature information from the surface of the submodels. The obtained surface temperature data is then imported into the overall machine model for fluid-structure coupling heat transfer calculation. The model developed in this study takes into account factors such as the dynamic heat generation of the heat source, the cooling fan system, and the secondary heat source effect of the cutting fluid. To validate the approach, a thermal characteristics experiment was conducted, and the research results demonstrate that the thermal analysis model established in this paper exhibits both high accuracy and efficiency. During the 180 min of machine operation, the thermal displacement between the tool tip and the workpiece increased. The maximum thermal deformation of the machine tool tip was 40.83 [Formula: see text], primarily observed in the X and Y directions.