Thermal Analysis Tool Research Articles

Thermo-Mechanical Coupled Analysis-Based Design of Ventilated Brake Disc Using Genetic Algorithm and Particle Swarm Optimization

The brake discs are subjected to thermal load due to sliding by the brake pad and fluctuating loads because of the braking load. This combined loading problem requires simulation using coupled thermo-mechanical analysis for design evaluation. This work presents a combined thermal and mechanical finite element analysis and evolutionary optimization-based novel approach for estimating the optimal design parameters of the ventilated brake disc. Five parameters controlling the design: Inboard plate thickness, outboard plate thickness, vane height, effective offset, and center hole radius were considered, and simulation runs were planned. 27 brake disc designs with design parameters as recommended by the Taguchi method (L27) were modeled using SOLIDWORKS, and the FEA simulation runs were carried out using ANSYS thermal & structural analysis tool. The fatigue life results were analyzed using a 3D surface plot for the effect of the design parameters on the response, contour plots for the determination of maximum response, and statistical regression analysis for model interpretation and predictive modeling. Finally, the two most accurate and widely used evolutionary optimization algorithms: genetic algorithm (GA) and particle swarm optimization (PSO) were applied to determine the optimal design parameters for the ventilated brake disc. The brake disc of design parameters predicted by GA and (PSO), gives 12.74% higher fatigue life compared to parametric analysis. These results have shown that the developed approach can be utilized effectively and reliably for solving, design ventilated brake disc problem in the industry.

Development of a Thermal Analysis Tool for Linear Machines

The thermal design is one of the most important stages in the design process of electrical machines. Thanks to software packages, like Motor-CAD, rotating machine designers can predict the thermal operation of the machines with high precision. However, a Motor-CAD equivalent for linear machines does not exist. Thus, linear machine designers must develop specific thermal analysis tools when designing the machines. In this article, a generic thermal analysis tool for different kinds of linear machines is presented. The model has been designed in MATLAB Simulink. Hence, it should be easy to implement for most engineers. The article describes the configuration of the different elements of the tool. The calibration parameters and procedure, and typical values of the calibration variables, are also given in the document. Finally, in order to demonstrate the generic nature of the tool, the model is experimentally validated via DC thermal tests to a linear induction machine and a linear switched-flux permanent magnet machine. The results show that, despite being simple and easy to implement, the model can predict the thermal operation of different machines with high precision.

Thermal Analyses of Reactor under High-Power and High-Frequency Square Wave Voltage Based on Improved Thermal Network Model

In order to quickly calculate the stable temperature of a reactor driven by high-frequency and high-power pulse voltage, an improved thermal network model suitable for a reactor under this condition is established in this paper. In power electronic equipment, the maximum temperature of the reactor is usually concentrated in its internal core. Moreover, with the increasing demand of high-power density in power electronic devices, the structure design of the reactor is more compact, and the internal magnetic field will affect the accuracy of the temperature-measuring device. Therefore, it is difficult to measure the internal temperature rise of the reactor directly. However, its stable operating temperature could be analyzed by the thermal network modeling methods and heat transfer analysis tool. Therefore, a convenient and accurate thermal network model of the reactor under high-frequency and high-power square wave voltage is established by considering the equivalent thermal resistance of the winding, the three-dimensional geometrical effect of the core and the effect of the high-frequency repeated pulse stress on the thermal penetration depth. Additionally, the internal temperature of the reactor can be obtained through the external temperature in terms of the presented model. To verify the feasibility of the thermal network model, the corresponding multiphysical field finite element simulation and the reactor temperature measurement platform is built. The simulation and experimental results show that the proposed thermal network model has a high precision and fast calculation speed, and it is an effective tool for thermal analysis of the reactor.

Applied methodology for temperature numerical evaluation on high current leads in power transformers

The majority of power transformer manufactures use their own proprietary design to build oil-immersed power transformers with high current busbar leads (HCBL) because there is no standardization or registered standard in the technical literature. Anyway, specialists certainly require a highly accurate temperature estimation regardless of the proprietary designs used to build these power transformers. It is well known that the temperature at the copper HCBL surface is mainly influenced by the Joule effect induced by the passing current, paper wrapping insulation characteristics, and temperature of the surrounding oil. In this context, we suggest a novel non-invasive technique for estimating the temperature of HCBL power transformers. Such methodology is simple and can be used to estimate the temperature for any power transformer despite designs strategies, becoming an algorithm that can be used in several commercial programs. The temperature is taken as a function of variables and measurements easily acquired from the transformer and, therefore, turns out to be an original and simple method. The methodology is based on the evaluation of the convection heat transfer coefficient h, which depends on the geometry factors and cooling fluid characteristics of the transformer. Since temperature levels are critically sensitive to h variations, Computer Fluid Dynamics (CFD)-based commercial software are a common-place tool for thermal analysis of power transformers as coefficient h must be calculated with very high precision and correctly evaluated. However, this solution have both high financial and computational burden. The skin and proximity effects are taken into account in the proposed methodology by using the Finite Element Method – FEM. Thus, we propose an efficient and simplified solution for temperature estimation. We will show that the solution is as accurate as the CFD programs, albeit, more economically and computationally viable. We validate the results by means of measurements made with Fiber Optic Temperature Sensors during a full-load test and show the estimation numerical accuracy for parameter h.

Outdoor Thermal Comfort: Application of RayMan Tools

The UN has issued a policy regarding the achievement of sustainable development goals, among which are to ensure inclusive and equitable quality education and promote lifelong learning opportunities for all. One of the contributors to the quality of education is the convenience of buildings as educational facilities. This paper describes thermal comfort analysis in the case study of the LABTEK VII Building on the Bandung Institute of Technology campus divided into 2 cases: the open space in the building’s hallway and the study room in the building. Thermal comfort analysis uses standard thermal comfort analysis tools as a measurement effort. This research was conducted by analysing the indicators of thermal comfort in educational buildings with multiple capacities in temperature, humidity (humidity), and wind speed obtained from Meteoblue and indicators of metabolic rate and clothing of building users. The analysis of these indicators is processed using CBe thermal Comfort and Rayman to produce thermal comfort in the building. This paper presents the highest PET values obtained at 2 pm with PET temperatures reaching 40 ° C, considered a Hot sensation. And in the CBE measurement results, it can be seen that the process of changing indoor temperature from morning to evening is getting higher. From measurements with these two tools, concludes that the thermal comfort at Labtek VII ITB is thermally comfortable.

Thermal design, analysis, and testing of the first Turkish 3U communication CubeSat in low earth orbit

TURKSAT-3USAT is the first Turkish communication 3U CubeSat designed and built by the students of the Space Systems Design and Test Laboratory and Radio Frequency Electronics Laboratory of Istanbul Technical University (ITU). Students partnered with TURKSAT, A.S. Company as well as the Turkish Amateur Technology Organization, when creating the design. The payload of TURKSAT-3USAT, having dimensions of 10 × 10 × 34 cm3, is an amateur band VHF/UHF transponder that will be used for voice communication. In this study, a thermal control system of TURKSAT-3USAT at 680 km altitude was presented. TURKSAT-3USAT used both passive and active thermal control. The thermal model of CubeSat was constructed and analyzed using ThermXL and ESATAN-TMS thermal analysis tools. The temperature results showed that all electronic components were within their allowed temperature range, except the batteries. For batteries, heaters are recommended during the cold case condition. Thermal cycling and bake-out testing were carried out on the flight model in a thermal vacuum chamber.

Delving into Autocatalytic Liquid-State Thermal Decomposition of Novel Energetic 1,3,5-Triazines with Azido, Trinitroethyl, and Nitramino Groups.

Thermal decomposition of 1,3,5-triazines with azido, trinitroethyl, and nitramino groups, the three important energetic functionalities, has been studied with a range of thermal analysis tools. The involved compounds melt under heating with the following mass loss and heat and gas release in the course of thermal decomposition. Model-fitting kinetic analysis resulted in formal reaction schemes with two general stages. In case of the least energetic 6-azido-2,4-bis(2,2,2-trinitroethylamino)-1,3,5-triazine, the first reaction is a first-order reaction followed by a third-order reaction. Alternatively, for 6-azido-2,4-bis(2,2,2-trinitroethylnitramino)-1,3,5-triazine and 2,4,6-tris(2,2,2-trinitroethylnitramino)-1,3,5-triazine, the first step comprises the autocatalytic reaction. The activation energy for the first decomposition step drops from 141 to 122 kJ mol-1 due to the inductive influence of a β-nitramino group. The second general reaction for all species obeys the third-order reaction model with activation energies in the range 112-126 kJ mol-1. On the basis of the analysis of the kinetic data and temporal behavior of the evolved gases, a similar primary decomposition channel, the homolytic cleavage of a C-NO2 bond, has been proposed for all investigated substances.

Development of analytical thermal analysis tool for synchronous reluctance motors

This study presents the principles of analytical lumped parameter model for a synchronous reluctance motor (SynRM) for traction application purposes. Particular focus is put on the calculation of the heat transfer from the machine's housing during the active and passive cooling. For this purpose, the area-based composite correlations method is proposed. The approach is attractive due to its simplicity and the fact that it closely models the temperature of the machine's housing. Finally, the proposed thermal model is evaluated experimentally on a totally enclosed fan cooled SynRM, and good correspondence between the analytical and experimental results is obtained.

Quartz Enhanced Conductance Spectroscopy for Polymer Nano-Mechanical Thermal Analysis

A fast and highly sensitive polymer nano-mechanical thermal analysis method for determining the melting temperature (Tm) of polymer microwires was proposed. In this method, a small-size, low-cost quartz tuning fork was used as a piezoelectric transducer to analyze the thermodynamics of polymer microwires at the nanogram level without changing its own properties. Due to the thin wire sample, which has a length of 1.2 mm and a diameter of ~5 µm, which is bridged across the prongs of the tuning fork, the nanogram-level sample greatly reduces the thermal equilibrium time for the measurement, resulting in a fast analysis for the melting temperature of the polymer sample. Compared with the traditional method, the analysis method based on the quartz enhanced conductivity spectrum (QECS) does not require annealing before measurement, which is an essential process for conventional thermal analysis to reduce the hardness, refine the grain, and eliminate the residual stress. In this work, the melting temperatures of three of the most commonly used polymers, namely polymers polymethyl methacrylate, high-density polyethylene, and disproportionated rosin, were obtained under the temperature from room temperature to >180 °C, proving the QECS method to be a useful tool for nano-mechanical thermal analysis.

On efficiency and effectiveness of finite volume method for thermal analysis of selective laser melting

Purpose Selective laser melting (SLM) is a major additive manufacturing (AM) process in which laser beams are used as the heat source to melt and deposit metals in a layerwise fashion to enable the construction of components of arbitrary complexity. The purpose of this paper is to develop a framework for accurate and fast prediction of the temperature distribution during the SLM process. Design/methodology/approach A fast computation tool is proposed for thermal analysis of the SLM process. It is based on the finite volume method (FVM) and the quiet element method to allow the development of customized functionalities at the source level. The results obtained from the proposed FVM approach are compared against those obtained from the finite element method (FEM) using a well-established commercial software, in terms of accuracy and efficiency. Findings The results show that for simulating the SLM deposition of a cubic block with 81,000, 189,000 and 297,000 cells, the computation takes about 767, 3,041 and 7,054 min, respectively, with the FEM approach; while 174, 679 and 1,630 min with the FVM code. This represents a speedup of around 4.4x. Meanwhile, the average temperature difference between the two is below 6%, indicating good agreement between them. Originality/value The thermal field for the multi-track and multi-layer SLM process is for the first time computed by the FVM approach. This pioneering work on comparing FVM and FEM for SLM applications implies that a fast and simple computing tool for thermal analysis of the SLM process is within the reach, and it delivers comparable accuracy with significantly higher computational efficiency. The research results lay the foundation for a potentially cost-effective tool for investigating the fundamental microstructure evolution, and also optimizing the process parameters in the SLM process.

Time-dependent neutron diffusion analysis using finite element method for a block-type VHTR core design

The very high-temperature gas-cooled reactor (VHTR) has attracted interest owing to its high passive safety. A reactor analysis tool is required to analyze the safety characteristics of a VHTR in detail, and such a tool should be capable of a transient calculation for a reactivity insertion accident such as control rod ejection or withdrawal. This work presents a transient analysis of a block-type VHTR core. Time-dependent neutron diffusion equation is solved by the finite element method. A simplified thermal fluid analysis tool is also implemented to consider thermal feedback. In addition, a new method is introduced to resolve the control rod cusping effect without additional computation or mesh reconstruction. The above methods are applied to a reactor physics code CAPP, developed at Korea Atomic Energy Research Institute (KAERI). The methods are tested on three-dimensional VHTR problems that include control rods and show encouraging results.

Nano differential scanning fluorimetry for comparability studies of therapeutic proteins

Differential scanning calorimetry (DSC) has been extensively used in the biopharmaceutical industry to characterize protein thermal stability and domain folding integrity. Recently, nano differential scanning fluorimetry (nanoDSF) has emerged as a powerful tool for thermal stability analysis and studies of protein domain unfolding. Due to increased interests in the qualification of characterization methods, we are in this study presenting the qualification results for the comparability studies of thermal stability analysis using nanoDSF. The results show that nanoDSF is able to detect thermal transition signals for mAbs, BiTE® molecules, and cytokines at a wide concentration range with high precision, clearly indicating that nanoDSF is suitable for characterization including comparability studies of therapeutic proteins. Compared to the current recognized industry standard DSC, the nanoDSF method enables thermal stability analysis over a much wider concentration range, consumes considerably less materials, and provides significantly higher throughput.

Pyrolytic carbon resonators for micromechanical thermal analysis

Thermal analysis is essential for the characterization of polymers and drugs. However, the currently established methods require a large amount of sample. Here, we present pyrolytic carbon resonators as promising tools for micromechanical thermal analysis (MTA) of nanograms of polymers. Doubly clamped pre-stressed beams with a resonance frequency of 233 ± 4 kHz and a quality factor (Q factor) of 800 ± 200 were fabricated. Optimization of the electrical conductivity of the pyrolytic carbon allowed us to explore resistive heating for integrated temperature control. MTA was achieved by monitoring the resonance frequency and quality factor of the carbon resonators with and without a deposited sample as a function of temperature. To prove the potential of pyrolytic carbon resonators as thermal analysis tools, the glass transition temperature (Tg) of semicrystalline poly(L-lactic acid) (PLLA) and the melting temperature (Tm) of poly(caprolactone) (PCL) were determined. The results show that the Tg of PLLA and Tm of PCL are 61.0 ± 0.8 °C and 60.0 ± 1.0 °C, respectively, which are in excellent agreement with the values measured by differential scanning calorimetry (DSC).

Buildingmass and Energy Demand in Conventional Housing Typologies of the Mediterranean City

The causal relation among building typology and building energy demand is a complex balance of climate, morphology, technology and use. The assessment of the relation between mass of building elements and energy demand in different housing typologies is the main goal of this study. A novel indicator, namely the Buildingmass, is introduced and tested in the Mediterranean climate region. Explorations on nine conventional housing typologies in Barcelona and Rome are carried out. Buildingmass evaluation is based on the calculation of the mass of building elements. Energy demand is assessed by modelling on multi-space dynamic thermal analysis tool. Our results point out that the Buildingmass has a strong relevance on energy, playing an important role in reducing heating and cooling demand in the Mediterranean city, as described by the proposed correlation (R2 = 0.88). Moreover, this indicator gives a more detailed characterisation of the housing stock of the Mediterranean city. The study aims at bridging the gap between urban physics and urban metabolism studies and fostering energy conservation measures for the built environment.

Three-Dimensional Frequency-Dependent Thermal Model for Planar Transformers in LLC Resonant Converters

In this paper, a thorough thermal analysis is carried out in order to find an analytical three-dimensional (3-D) frequency-dependent thermal model of planar transformers (PTs) used in high-frequency power converters. Because of the tendency of having higher power density as well as miniaturization of power converters, the components have to work near their thermal limit margins. This issue is more critical for planar magnetics in LLC converters due to their variable high-frequency operation, making thermal modeling and heat transfer analysis tools necessary. The proposed 3-D frequency thermal model is obtained based on the lumped parameters network (LPN) according to different thermal resistances of the PT including convection, conduction, and radiation heat exchanges. It should be noted that not only the 3-D geometry effect of the core is applied to the proposed model, but thermal surface resistances are also considered to model the high-frequency operation effect. Moreover, the lumped capacitance thermal model is used to analyze the transient thermal variation of the transformer. The LLC resonant converter with two PTs, including EE58/11/38 and ER51/10/38 planar cores, is considered to show the compatibility of the proposed 3-D-frequency LPN model. In addition, the temperature distribution of different parts of the transformers is evaluated using finite element method modeling and compared with the proposed 3-D frequency-dependent LPN model. Experimental results confirm the improved accuracy of the proposed LPN model and show the proposed model predicts the temperature distribution in PTs with an error of less than 3%. Considering the improved accuracy and low computational time of the method, the proposed 3-D frequency-dependent model is a powerful and fast design tool to evaluate the temperature distribution for different designs, and so can be used to effectively optimize the transformer from thermal point of view.

Analysis and Modelling of Non-Fourier Heat Behavior Using the Wavelet Finite Element Method.

Non-Fourier heat behavior is an important issue for film material. The phenomenon is usually observed in some laser induced thermal responses. In this paper, the non-Fourier heat conduction problems with temperature and thermal flux relaxations are investigated based on the wavelet finite element method and solved by the central difference scheme for one- and two-dimensional media. The Cattaneo–Vernotte model and the Dual-Phase-Lagging model are used for finite element formulation, and a new wavelet finite element solving formulation is proposed to address the memory requirement problem. Compared with the current methodologies for the Cattaneo–Vernotte model and the Dual-Phase-Lagging model, the present model is a direct one which describe the thermal behavior by one equation about temperature. Compared with the wavelet method proposed by Xiang et al., the developed method can be used for arbitrary shapes. In order to address the efficient computation problems for the Dual-Phase-Lagging model, a novel iteration updating methodology is also proposed. The proposed iteration algorithms on time avoids the use the global stiffness matrix, which allows the efficient calculation for title issue. Numerical calculations have been conducted in the manner of comparisons with the classical finite element method and spectral finite element method. The comparisons from accuracy, efficiency, flexibility, and applicability validate the developed method to be an effective and alternative tool for material thermal analysis.

Coupling of a Reactor Analysis Code and a Lower Head Thermal Analysis Solver

Due to the recent high interest on in-vessel melt retention (IVR), development of detailed thermal and structural analysis tool, which can be used in a core-melt severe accident, is inevitable. Although RELAP/SCDAPSIM is a reactor analysis code, originally developed for U.S. NRC, which is still widely used for severe accident analysis, the modeling of the lower head is rather simple, considering only a homogeneous pool. PECM/S, a thermal structural analysis solver for the reactor pressure vessel (RPV) lower head, has a capability of predicting molten pool heat transfer as well as detailed mechanical behavior including creep, plasticity, and material damage. The boundary condition, however, needs to be given manually and thus the application of the stand-alone PECM/S to reactor analyses is limited. By coupling these codes, the strength of both codes can be fully utilized. Coupled analysis is realized through a message passing interface, OpenMPI. The validation simulations have been performed using LIVE test series and the calculation results are compared not only with the measured values but also with the results of stand-alone RELAP/SCDAPSIM simulations.

Enabling Early and Fast Thermal Simulation for 3D Multi-Die System Designs

As design complexity increases with 3DICs and time-to-market becomes a critical component in the automotive, wearables and IoT segments, reducing design cycle time while maintaining accuracy of analysis has become all the more important. To address this, a system level co-design approach in step with multi-physics analysis is presented. To mitigate errors due to manual exchange of data between various engineering teams spread across chip, package and board with design and analysis adding further level of exchange, a design flow incorporating simplification at the layout level is shown. The flow enables various levels of simplified models to be used, wherein data transfer between the complex 3D structures in layout to the thermal analysis tool is automated. The efficacy of the model simplification is verified through a test case showing comparable results for the simplified and full models.

Thermal analysis used to guide the production of thymol and Lippia origanoides essential oil inclusion complexes with cyclodextrin

This study aimed to use thermal analysis and other analytical tools to guide the production of thymol (TML) and essential oil of Lippia origanoides (EO) solid inclusion complexes from a screening of different cyclodextrins (CDs) types and production methods (freeze drying, spray drying, rotary evaporation and supercritical CO2). According to the phase solubility diagrams, the best complexation efficiency of TML was achieved using hydroxypropyl-β-cyclodextrin (~ 0.7), comparing to the natives CDs, which showed values below 0.5. Thermogravimetry was effective in evaluating the amount of drug inclusion complexes in each solid sample by measuring the evaporation of TML, which was dependent of its degree of interaction with the CD. Freeze drying was the most effective method in originating true inclusion complexes in solid state producing the encapsulation of nearly 70% of available TML which were stable at temperature ranges from 200 to 280 °C. Indeed, according to the stability assay, the shelf-life increase achieved for the TML standard was 354%, while the EO had a stability increase of around 45%. Finally, the antifungal effect against Candida albicans (ATCC 14053) was increased in complexed forms in about 1.5 times and 5.4 times for EO and TML, respectively, while the antifungal activity for Trichophyton mentagrophytes (ATCC 11481) was increased with TML and EO encapsulated with CD in more than 22 times and 45 times, respectively, compared to their free forms. Thus, the optimized inclusion complexes seem to be promising in pharmaceutical field for a future development of topical preparations containing TML and its natural substrates.

The MTA: An Advanced and Versatile Thermal Simulator for Integrated Systems

Fast and accurate thermal analysis is crucial for determining the propagation of heat and tracking the formation of hotspots in integrated circuits (ICs). Existing academic thermal analysis tools primarily use compact models to accelerate thermal simulations but are limited to linear problems on relatively simple circuit geometries. The Manchester Thermal Analyzer (MTA) is a comprehensive tool that allows for fast and highly accurate linear and nonlinear thermal simulations of complex physical structures including the IC, the package, and the heatsink. The MTA is targeted for 2.5/3-D IC designs but also handles standard planar ICs. The MTA discretizes the heat equation in space using the finite element method and performs the time integration with unconditionally stable implicit time stepping methods. To improve the computational efficiency without sacrificing accuracy, the MTA features adaptive spatiotemporal refinement. The large-scale linear systems that arise during the simulation are solved with fast preconditioned Krylov subspace methods. The MTA supports thermal analysis of realistic integrated systems and surpasses the computational capabilities and performance of existing academic thermal simulators. For example, the simulation of a processor in a package attached to a heat sink, modeled by a computational grid consisting of over 3 million nodes, takes less than 3 min. The MTA is fully parallel and publicly available. 1