Literatura académica sobre el tema "Heat – Transmission – Computer simulation"
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Artículos de revistas sobre el tema "Heat – Transmission – Computer simulation"
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Chang, Liang, Zhiwei Li, Sheng Li, Wenang Jia y Jian Ruan. "Heat Loss Analysis of a 2D Pump’s Transmission". Machines 10, n.º 10 (26 de septiembre de 2022): 860. http://dx.doi.org/10.3390/machines10100860.
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Highly enhanced pump power density inevitably results in a profound rise in pump temperature, which seriously influences both power loss and service performance. Heat loss analysis is an important part of analyzing the mechanical and cooling efficiency of a 2D piston pump. This paper focuses on heat loss analysis of this pump’s transmission. Firstly, theoretical and experimental studies are carried out on the thermal–hydraulic model to investigate the heat loss of the pump’s transmission. A pump test rig is developed and thermal experiments are conducted, from 1000 rpm to 6000 rpm. Furthermore, its transient thermal simulation model is implemented with Ansys software to capture the pump’s thermal status. The test convective heat transfer coefficients and temperature data are set in the model, and the simulation results are mutually validated with the experimental ones. Finally, the transmission’s heat loss is compared with its reference churning loss formula. The distribution of the transient heat loss is 49.66% into the end cap, 27.74% into the cylinder head, 13.30% into the inner cylinder, and 9.30% into the oil. The heat loss simulation results agree with the churning loss below 4000 rpm; therefore, the transmission thermal model is accurate and efficient.
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Kalua, Amos y James Jones. "Epistemological Framework for Computer Simulations in Building Science Research: Insights from Theory and Practice". Philosophies 5, n.º 4 (22 de octubre de 2020): 30. http://dx.doi.org/10.3390/philosophies5040030.
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Computer simulations are widely used within the area of building science research. Building science research deals with the physical phenomena that affect buildings, including heat and mass transfer, lighting and acoustic transmission. This wide usage of computer simulations, however, is characterized by a divergence in thought on the composition of an epistemological framework that may provide guidance for their deployment in research. This paper undertakes a fundamental review of the epistemology of computer simulations within the context of the philosophy of science. Thereafter, it reviews the epistemological framework within which computer simulations are used in practice within the area of building science research. A comparison between the insights obtained from the realms of theory and practice is made, which then interrogates the adequacy of the epistemological approaches that have been employed in previously published simulation-based research. These insights may help in informing a normative composition of an adequate epistemological framework within which computer simulation-based building science research may be conducted.
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Kuokkala, V. T. "Computer simulation of transmission electron micrographs by microscope for windows". Proceedings, annual meeting, Electron Microscopy Society of America 54 (11 de agosto de 1996): 126–27. http://dx.doi.org/10.1017/s0424820100163095.
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microScope for Windows™ is a transmission electron micrograph simulation program for brightfield and darkfield images of dislocations and stacking faults, based on the dynamical two-beam theory and the column approximation. The program is a modification of the original programs of Head et al, which have been rewritten in Visual Basic™ 4.0 for Microsoft® Windows™ 3.1. microScope for Windows™ also includes routines needed to prepare data for the actual calculation of the image, and to calculate and display a rocking curve for any pixel of the previously computed brightfield or darkfield image. On a 120 MHz Pentium, microScope for Windows™ calculates a true gray scale (256 gray level) image consisting of 19840 pixels in about 10 seconds (version 2.3). A 300 dpi laserprinter screendump at the end of the calculation of an image is shown in Fig. 1.
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Liang, Qing, Jing Liu, Wen Zhong Xu y Gang Xu. "Optimization of the Optical Performance of TiO2/Ag/TiO2 Multilayers for Warm Climates". Advanced Materials Research 168-170 (diciembre de 2010): 936–39. http://dx.doi.org/10.4028/www.scientific.net/amr.168-170.936.
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The optical performance of the heat mirror for warm climates was proposed, and a parameter Dx which equals the ratio of solar transmission to visible transmission was defined. To make the Dx as low as possible, the thicknesses of the films for TiO2/Ag/TiO2multilayers were optimized through computer simulation. A TiO2(140 nm)/Ag (16 nm)/TiO2(140 nm) structure optimized for 16-nm Ag has a maximum decrease in Dx value (from 0.75 to 0.51), which possesses excellent building energy efficiency.
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Huo, Wen. "Thermal Simulation Analysis of Internal Control Circuit Board of Steering Gear Box Based on COMSOL Three-Dimensional Simulation Software". Computational Intelligence and Neuroscience 2022 (24 de marzo de 2022): 1–20. http://dx.doi.org/10.1155/2022/3006349.
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The steering gear device includes two parts, a steering gear control circuit and a transmission component. The transmission component includes a ball screw and a motor. During the operation of the steering gear, due to the presence of the steering gear ball screw motor and friction, a certain amount of heat will be generated, which will affect the steering gear control circuit in a confined space. At the same time, the steering gear is inevitable in the actual working process, and will experience a high temperature environment, which will increase the temperature of the internal structure of the steering gear, and due to the difference in thermal expansion coefficients between various materials, stress and strain will occur in the structure, which may cause mismatch or even cracks in the system structure, and the steering gear system cannot work normally. It is necessary to analyze the thermal characteristics of the overall steering gear under multiple factors. Based on this, this paper uses COMSOL three-dimensional simulation software to conduct thermal simulation analysis on the shell of the steering gear containing the control circuit board. The temperature distribution and stress-strain response law of the control circuit board in the box, and the influence of different materials and thickness of the box heat insulation layer on the thermal characteristics of the control circuit are discussed, and then a reasonable thickness and material of the heat insulation layer are obtained for the design of the rudder chassis for reference.
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Hopmann, Christian y Suveni Kreimeier. "Modelling the Heating Process in Simultaneous Laser Transmission Welding of Semicrystalline Polymers". Journal of Polymers 2016 (27 de octubre de 2016): 1–10. http://dx.doi.org/10.1155/2016/3824065.
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Laser transmission welding is an established joining process for thermoplastics. A close-to-reality simulation of the heating process would improve the understanding of the process, facilitate and shorten the process installation, and provide a significant contribution to the computer aided component design. For these reasons a thermal simulation model for simultaneous welding was developed which supports determining the size of the heat affected zone (HAZ). The determination of the intensity profile of the laser beam after the penetration of the laser transparent semicrystalline thermoplastic is decisive for the simulation. For the determination of the intensity profile two measurement systems are presented and compared. The calculated size of the HAZ shows a high concordance to the dimensions of the HAZ found using light microscopy. However, the calculated temperatures exceed the indicated decomposition temperatures of the particular thermoplastics. For the recording of the real temperatures during the welding process a measuring system is presented and discussed.
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Noémi Zetz, Dóra y István Kistelegdi. "Comfort simulation supported sketch plan optimization of the University of Pécs, Medical School extension". Pollack Periodica 15, n.º 2 (agosto de 2020): 166–77. http://dx.doi.org/10.1556/606.2020.15.2.15.
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Abstract:During sketch design stage for the new block of the University of Pécs, Medical School comfort and lighting simulations were applied to quantify optimization strategies. Simulation cases about shading possibilities, façade glazing ratios and internal heat storage masses evaluate the impact of illumination, solar gains, loads and heat transmission on visual and thermal comfort. The goal was to select the most favorable comfort, coupled with maximum reduction of investment costs. Concepts represent 14% (shading), 10% (reduced wall-window ratio), 11% (slabs without suspended ceilings), and 17% (combined wall-window ratio and thermal mass) improvement in thermal comfort performance, and it was proposed for further design.
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Lim, Huey Sia, Nayan Nafarizal, Mohd Zainizan Sahdan, Samsul Haimi Dahlan, Zuhairiah Zainal Abidin, Muhammad Yusof Ismail, Fauziahanim Che Seman et al. "Optimization of Transmission Lost for Energy Saving Glass with Different Sheet Resistance Values". Advanced Materials Research 832 (noviembre de 2013): 233–36. http://dx.doi.org/10.4028/www.scientific.net/amr.832.233.
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Recently, energy saving glass is commonly applied in the modern engineered building. This is due to its advantages of keeping the heat inside the building in winter while rejecting the heat when in summer. The typical energy saving glass is made by applying a very thin metallic oxide such as silver oxide or tin oxide on one side of the float glass. But at the same time, it has the disadvantages of attenuates useful microwave frequencies that ranging from 0.8 2.2 GHz. The examples of the microwave frequency at this range are GSM mobile signal, GPS and personal communication. Frequency selective surface (FSS) has been introduced to overcome this drawback of energy saving glass. In this study, the transmission of the microwave signal is observed through the simulation using Computer Simulation Technology Microwave Studio. Bandpass frequency selective surface of cross dipole shape is used for the simulation. In the simulation, conductivity and electrical properties of glass and metal oxide thin film are important. The microwave transmission was evaluated at various sheet resistance of metal oxide thin film. The results show that the minimum transmission lost increased with the ohmic resistance increased. On the other hand, the peak frequency at various sheet resistance shows constant value at around 1.25-1.30 GHz. The full width half maximum of the microwave transmission increases with the sheet resistance value. The results suggest that FSS structured metal oxide thin film with lowest sheet resistance transmits more signal in the range for GSM phone signal.
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Della Torre, Augusto, Gianluca Montenegro, Angelo Onorati, Sumit Khadilkar y Roberto Icarelli. "Multi-Scale CFD Modeling of Plate Heat Exchangers Including Offset-Strip Fins and Dimple-Type Turbulators for Automotive Applications". Energies 12, n.º 15 (1 de agosto de 2019): 2965. http://dx.doi.org/10.3390/en12152965.
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Plate heat exchangers including offset-strip fins or dimple-type turbulators have a wide application in the automotive field as oil coolers for internal combustion engines and transmissions. Their optimization is a complex task since it requires targeting different objectives: High compactness, low pressure drop and high heat-transfer efficiency. In this context, the availability of accurate Computational Fluid Dynamics (CFD) simulation models plays an important role during the design phase. In this work, the development of a computational framework for the CFD simulation of compact oil-to-liquid heat exchangers, including offset-strip fins and dimples, is presented. The paper addresses the modeling problem at different scales, ranging from the characteristic size of the turbulator geometry (typically µm–mm) to the full scale of the overall device (typically cm–dm). The simulation framework is based on multi-scale concept, which applies: (a) Detailed simulations for the characterization of the micro-scale properties of the turbulator, (b) an upscaling approach to derive suitable macro-scale models for the turbulators and (c) full-scale simulations of the entire cooler, including the porous models derived for the smaller scales. The model is validated comparing with experimental data under different operating conditions. Then, it is adopted to investigate the details of the fluid dynamics and heat-transfer process, providing guidelines for the optimization of the device.
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Alzu’bi, Oruba Ahmad Saleh, Firas A. Alwawi, Mohammed Z. Swalmeh, Ibrahim Mohammed Sulaiman, Abdulkareem Saleh Hamarsheh y Mohd Asrul Hery Ibrahim. "Energy Transfer through a Magnetized Williamson Hybrid Nanofluid Flowing around a Spherical Surface: Numerical Simulation". Mathematics 10, n.º 20 (16 de octubre de 2022): 3823. http://dx.doi.org/10.3390/math10203823.
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A computational simulation of Williamson fluid flowing around a spherical shape in the case of natural convection is carried out. The Lorentz force and constant wall temperature are taken into consideration. In addition, upgrader heat transfer catalysts consisting of multi-walled carbon tubes, molybdenum disulfide, graphene oxide, and molybdenum disulfide are employed. The Keller box approach is used to solve the mathematical model governing the flow of hybrid Williamson fluid. To validate our findings, the key parameters in the constructed model are set to zero. Next, the extent of the agreement between our results and published results is observed. Numerical and graphical results that simulate the impressions of key parameters on physical quantities related to energy transmission are obtained, discussed, and analyzed. According to the results of this study, increasing the value of the Weissenberg number causes an increase in both the fluid temperature and drag force, while it also leads to a decrease in both the velocity of the fluid and the rate of energy transmission. Increasing the magnetic field intensity leads to a reduction in the rate of heat transfer, drag force, and fluid velocity while it has an appositive effect on temperature profiles.
Tesis sobre el tema "Heat – Transmission – Computer simulation"
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Srinivasan, Raghavan. "CFD Heat Transfer Simulation of the Human Upper Respiratory Tract for Oronasal Breathing Condition". Thesis, North Dakota State University, 2011. https://hdl.handle.net/10365/29310.
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In this thesis. a three dimensional heat transfer model of heated airflow through the upper human respiratory tract consisting of nasal, oral, trachea, and the first two generations of bronchi is developed using computational fluid dynamics simulation software. Various studies have been carried out in the literature investigating the heat and mass transfer characteristics in the upper human respiratory tract, and the study focuses on assessing the injury taking place in the upper human respiratory tract and identifying acute tissue damage based on level of exposure. The model considered is for the simultaneous oronasal breathing during the inspiration phase with high volumetric flow rate of 90/liters minute and a surrounding air temperature of 100 degrees centigrade. The study of the heat and mass transfer, aerosol deposition and flow characteristics in the upper human respiratory tract using computational fluid mechanics simulation requires access to a two dimensional or three dimensional model for the human respiratory tract. Depicting an exact model is a complex task since it involves the prolonged use of imaging devices on the human body. Hence a three dimensional geometric representation of the human upper respiratory tract is developed consisting of nasal cavity, oral cavity, nasopharynx, pharynx, oropharynx, trachea and first two generations of the bronchi. The respiratory tract is modeled circular in cross-section and varying diameter for various portions as identified in this study. The dimensions are referenced from the literature herein. Based on the dimensions, a simplified model representing the human upper respiratory tract is generated.This model will be useful in studying the flow characteristics and could assist in treatment of injuries to the human respiratory tract as well as help optimize drug delivery mechanism and dosages. Also a methodology is proposed to measure the characteristic dimension of the human nasal and oral cavity at the inlet/outlet points which are classified as internal measurements.
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Shao, Ming. "Modelling simultaneous heat and mass transfer in wood". Thesis, Virginia Tech, 1994. http://hdl.handle.net/10919/42073.
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The fundamental and quantitative study of heat and mass transfer processes in wood plays an important role for understanding many important production processes, such as wood drying and hot-pressing. It will help us improve the existing products and production techniques and develop new manufacturing technology. The most difficult aspect of the study is the complicated interactions of heat and mass transfer mechanisms. Extensive characterization of these physical processes using a strictly experimental approach is extremely difficult because of the excessively large number of variables that must be considered. However, mathematical modeling and numerical techniques serve as a powerful tool to help us understand the complicated physical processes.
The goal of this research is to model the simultaneous heat and mass transfer in wood. The specific objectives of this research are:
1) develop a computer simulation program, implementing an existing one-dimensional mathematical drying model, using a finite difference approach, to numerically evaluate the mathematical model.
2) study sensitivity of the heat and mass transfer model to determine the effects of wood physical properties and environmental conditions on the drying processes.Master of Science
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Baumgratz, Filipe Dias. "Estudo da distribuição da temperatura em encapsulamentos de dispositivos MOSFET utilizando simulação por métodos de elementos finitos". [s.n.], 2011. http://repositorio.unicamp.br/jspui/handle/REPOSIP/259569.
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Orientador: Marco Antônio Robert AlvesDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação
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Resumo: O transistor MOSFET teve uma evolução muito grande desde sua invenção até os dias de hoje. As dimensões foram reduzidas, a capacidade de integração de componentes e frequência de operação aumentaram, como consequência desta evolução houve um aumento da potência dissipada pelos circuitos integrados. Neste trabalho foi utilizada simulação por elementos finitos para estudar o comportamento térmico de um encapsulamento ao variar-se sua montagem interna, utilizando um MOSFET de potência como fonte de calor. A partir destas simulações foi possível identificar os pontos de maior e menor temperatura, bem como as regiões de melhor condução de calor. Ainda utilizando simulação por elementos finitos estudou-se o efeito da variação do tempo de chaveamento nas temperaturas observadas no interior do encapsulamento
Abstract: The transistor had a great evolution since its invention until today. The dimensions were reduced, the components integration and operating frequency increased, a result of these developments is higher power dissipation in integrated circuits. This work use finite element method simulation to study the thermal behavior of a package with different internal assembly, using a power MOSFET as heat source. From these simulations it is possible to identify the points of high and low temperature, and best thermal paths. Still using finite element method simulation was studied the effect of switching time in the thermal behavior of the package
Mestrado
Eletrônica, Microeletrônica e Optoeletrônica
Mestre em Engenharia Elétrica
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Gempesaw, Daniel. "A multi-resolution discontinuous Galerkin method for rapid simulation of thermal systems". Thesis, Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/42775.
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Efficient, accurate numerical simulation of coupled heat transfer and fluid dynamics systems continues to be a challenge. Direct numerical simulation (DNS) packages like FLU- ENT exist and are sufficient for design and predicting flow in a static system, but in larger systems where input parameters can change rapidly, the cost of DNS increases prohibitively. Major obstacles include handling the scales of the system accurately - some applications span multiple orders of magnitude in both the spatial and temporal dimensions, making an accurate simulation very costly. There is a need for a simulation method that returns accurate results of multi-scale systems in real time. To address these challenges, the Multi- Resolution Discontinuous Galerkin (MRDG) method has been shown to have advantages over other reduced order methods. Using multi-wavelets as the local approximation space provides an inherently efficient method of data compression, while the unique features of the Discontinuous Galerkin method make it well suited to composition with wavelet theory. This research further exhibits the viability of the MRDG as a new approach to efficient, accurate thermal system simulations. The development and execution of the algorithm will be detailed, and several examples of the utility of the MRDG will be included. Comparison between the MRDG and the "vanilla" DG method will also be featured as justification of the advantages of the MRDG method.
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Li, Shuo. "A Numerical Study of Micro Synthetic Jet and Its Applications in Thermal Management". Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/7539.
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A numerical study of axisymmetric synthetic jet flow was conducted. The synthetic jet cavity was modeled as a rigid chamber with a piston-like moving diaphragm at its bottom. The Shear-Stress-Transportation (SST) k-omega and #61559; turbulence model was employed to simulate turbulence. Based on time-mean analysis, three flow regimes were identified for typical synthetic jet flows. Typical vortex dynamics and flow patterns were analyzed. The effects of changes of working frequency, cavity geometry (aspect ratio), and nozzle geometry were investigated. A control-volume model of synthetic jet cavity was proposed based on the numerical study, which consists of two first-order ODEs. With appropriately selected parameters, the model was able to predict the cavity pressure and average velocity through the nozzle within 10% errors compared with full simulations. The cavity model can be used to generate the boundary conditions for synthetic jet simulations and the agreement to the full simulation results was good. The saving of computational cost is significant. It was found that synthetic jet impingement heat transfer outperforms conventional jet impingement heat transfer with equivalent average jet velocity. Normal jet impingement heat transfer using synthetic jet was investigated numerically too. The effects of changes of design and working parameters on local heat transfer on the impingement plate were investigated. Key flow structures and heat transfer characteristics were identified. At last, a parametric study of an active heat sink employing synthetic jet technology was conducted using Large Eddy Simulation (LES). Optimal design parameters were recommended base on the parametric study.
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Mulcahey, Thomas Ian. "Convective instability of oscillatory flow in pulse tube cryocoolers due to asymmetric gravitational body force". Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/51808.
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Pulse tube cryocoolers (PTCs) are among the most attractive choices of refrigerators for applications requiring up to 1 kW of cooling in the temperature range of 4-123 K as a result of the high relative efficiency of the Stirling cycle, the reliability of linear compressors, and the lack of cryogenic moving parts resulting in long life and low vibration signature. Recently, PTCs have been successfully used in applications in the 150 K range, extending the useful range of the device beyond the traditional cryogenic regime. A carefully designed cylindrical cavity referred to as the pulse tube replaces the mechanical expander piston found in a Stirling machine. A network consisting of the pulse tube, inertance tube, and surge volume invoke out-of-phase pressure and mass flow oscillations while eliminating all moving parts in the cold region of the device, significantly improving reliability over Stirling cryocoolers. Terrestrial applications of PTCs expose a fundamental flaw. Many PTCs only function properly in a narrow range of orientations, with the cold end of the pulse tube pointed downward with respect to gravity. Unfavorable orientation of the cold head often leads to a catastrophic loss of cooling, rendering the entire cryocooler system inoperable. Previous research indicates that cooling loss is most likely attributed to secondary flow patterns in the pulse tube caused by free convection. Convective instability is initiated as a result of non-uniform density gradients within the pulse tube. The ensuing secondary flow mixes the cryogen and causes enhanced thermal transport between the warm and cold heat exchangers of the cryocooler.
This study investigates the nonlinear stabilizing effect of fluid oscillation on Rayleigh-Bénard instability in a cryogenic gas subject to misalignment between gravitational body force and the primary flow direction. The results are directly applicable to the flow conditions frequently experienced in PTCs. Research has shown that the convective component can be minimized by parametrically driven fluid oscillation as a result of sinusoidal pressure excitation; however, a reliable method of predicting the influence of operating parameters has not been reported. In this dissertation, the entire PTC domain is first fully simulated in three dimensions at various angles of inclination using a hybrid method of finite volume and finite element techniques in order to incorporate conjugate heat transfer between fluid domains and their solid containment structures. The results of this method identify the pulse tube as the sole contributor to convective instability, and also illustrate the importance of pulse tube design by incorporating a comparison between two pulse tubes with constant volume but varying aspect ratio. A reduced domain that isolates the pulse tube and its adjacent components is then developed and simulated to improve computational efficiency, facilitating the model’s use for parametric study of the driving variables. A parametric computational study is then carried out and analyzed for pulse tubes with cold end temperatures ranging from 4 K to 80 K, frequencies between 25-60 Hz, mass flow - pressure phase relationships of -30◦ and +30◦, and Stokes thickness-based Reynolds numbers in the range of 43-350, where the turbulent transition occurs at 500.
In order to validate the computational models reported and therefore justify their suitability to perform parametric exploration, the CFD codes are applied to a commercially developed single stage PTR design. The results of the CFD model are compared to laboratory-measured values of refrigeration power at temperatures ranging from 60 K to 120 K at inclination angles of 0◦ and 91◦. The modeled results are shown to agree with experimental values with less than 8.5% error for simulation times of approximately six days using high performance computing (HPC) resources through Georgia Tech’s Partnership for Advanced Computing (PACE) cluster resource, and 10 days on a common quad-core desktop computer. The results of the computational parametric study as well as the commercial cryocooler data sets are compiled in a common analysis of the body of data as a whole. The results are compared to the current leading pulse tube convective stability model to improve the reliability of the predictions and bracket the range of losses expected as a function of pulse tube convection number. Results can be used to bracket the normalized cooling loss as a function of the pulse tube convection number NPTC. Experimental data and simulated results indicate that a value of NPTC greater than 10 will yield a loss no greater than 10% of the net pulse tube energy flow at any angle. A value of NPTC greater than 40 is shown to yield a loss no greater than 1% of the net pulse tube energy flow at all angles investigated.
The computational and experimental study completed in this dissertation addresses static angles of inclination. Recent interest in the application of PTCs to mobile terrestrial platforms such as ships, aircraft, and military vehicles introduces a separate regime wherein the angle of inclination is dynamically varying. To address this research need, the development of a single axis rotating cryogenic vacuum facility is documented. A separate effects apparatus with interchangeable pulse tube components has also been built in a modular fashion to accommodate future research needs.
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Mioralli, Paulo Cesar. "Analise termica de um regenerador rotativo". [s.n.], 2005. http://repositorio.unicamp.br/jspui/handle/REPOSIP/263462.
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Orientador: Marcelo Moreira GanzarolliDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica
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Resumo: Este estudo concentra-se na análise térmica de um regenerador rotativo, no qual o processo de transferência de calor é investigado numericamente. As equações de transporte foram discretizadas utilizando o método de volumes finitos e um programa computacional em linguagem FORTRAN foi confeccionado para as simulações numéricas. Uma correlação para estimar o coeficiente médio de transferência de calor em um canal da matriz do regenerador foi obtida para o regime laminar de escoamento a partir da utilização do pacote numérico comercial PHOENICS 3.5. O valor de temperatura média de mistura na saída de cada escoamento foi obtido e comparado com o valor calculado por método existente em literatura. Os resultados foram analisados e também comparados com dados de campo e uma concordância relativamente boa foi observada. Através das simulações numéricas, foi possível obter a distribuição de temperatura ao longo de um canal do regenerador em diferentes posições angulares. Conhecendo essa distribuição de temperatura, é possível obter um dimensionamento adequado para o sistema de selagem acoplado na matriz do regenerador. Foi visto neste trabalho que o perfil de temperatura na direção axial é determinante no dimensionamento do sistema de selagem do regenerador
Abstract: This study focalizes on the thermal analysis of a rotary regenerator, in which the process of heat transfer is numerically investigated. The governing equations are solved using finite volume code. A computational code in FORTRAN programming language was made for the numerical simulations. A correlation for valuation the medium heat transfer coefficient in the duct, for flow in laminar regime, was obtained using a commercial code (PHOENICS 3.5). The value of mean temperature at the exit of each flow was obtained and compared with the value calculated by existent method in the literature. The results were analyzed and also compared with field data and a relatively good agreement was observed. Through the numerical simulations, it was possible to obtain the temperature distribution along a duct of the regenerator in different angular positions
Mestrado
Termica e Fluidos
Mestre em Engenharia Mecânica
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Tomazeti, Cristina Autuori. "Analise numerica do desempenho termico de trocadores de calor de correntes cruzadas". [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/264127.
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Orientador: Carlos Alberto Carrasco AltemaniTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica
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Resumo: Uma análise foi desenvolvida para avaliar o desempenho de trocadores de calor compactos de correntes cruzadas de placas aletadas com canais de seção transversal arbitrária. Os coeficientes convectivo e de atrito foram obtidos através de simulação numérica, tanto no regime de escoamento laminar quanto no turbulento, utilizando o pacote computacional PHOENICS. Estes resultados foram então usados junto com o método da efetividade para avaliar as características térmicas e de escoamento do trocador de calor. As simulações foram efetuadas inicialmente para o escoamento e a transferência de calor entre duas placas placa paralelas isotérmicas e bastante próximas, porque os resultados podiam ser comparados com aqueles disponíveis na literatura. Resultados numéricos adicionais foram obtidos, em seguida, para seis dutos de paredes isotérmicas com seções transversais distintas. Um deles era um duto retangular, e os outros cinco eram passagens típicas de placas aletadas utilizadas em trocadores de calor compactos. O fluido de trabalho era o ar e as simulações foram tridimensionais devido à presença das paredes das aletas. Perfis uniformes de velocidade e de temperatura sempre foram utilizados na entrada dos dutos, de forma que os resultados refletem os efeitos combinados de entrada hidrodinâmica e térmica. Os resultados para o duto retangular e o método da efetividade foram utilizados para prever o desempenho térmico de um trocador de calor de correntes cruzadas composto por um empilhamento de dutos retangulares idênticos. O desempenho deste trocador de calor foi avaliado também por uma simulação direta do escoamento cruzado e da transferência de calor através da parede de separação de dois dutos retangulares adjacentes do empilhamento. Os resultados obtidos foram bastante semelhantes, fornecendo confiança para a análise anterior. As simulações efetuadas para os cinco dutos típicos de placas aletadas de dimensões pequenas apresentaram resultados similares aos valores experimentais obtidos da literatura. Eles foram utilizados para avaliar o desempenho de trocadores de calor compactos de correntes cruzadas compostos por empilhamentos destas placas aletadas. Vários parâmetros como o volume total, o peso, a potência de bombeamento, a efetividade, a taxa de geração adimensional de entropia, e a eficiência exergética também foram avaliados para comparar os trocadores compactos de calor considerados
Abstract: An analysis was developed to evaluate the performance of cross flow compact heat exchangers with plate-fin passages of arbitrary cross section. The convective and the friction coefficients were obtained by numerical simulation, either in the laminar or the turbulent flow regimes, using the software PHOENICS. These results were then employed together with the effectiveness method to evaluate the heat exchanger thermal and flow characteristics. The simulations were performed initially for the flow and heat transfer between two closely spaced parallel isothermal plates, because the results could be compared with those available in the literature. Additional numerical results were obtained, next, for six isothermal wall ducts with distinct cross sections. One was a rectangular duct, and the other five were typical plate-fin passages employed in compact heat exchangers. The working fluid was air and the simulations were three dimensional due to the fins walls. Uniform velocity and temperature profiles were always assumed at the duct inlet, so that the results reflected the combined effects of hydrodynamic and thermal entrance. The results for the rectangular duct and the effectiveness method were employed to predict the thermal performance of a cross flow heat exchanger made from a stack of identical rectangular ducts. The performance of this heat exchanger was also evaluated by a direct simulation of the cross flow and the heat transfer through the separating wall of two adjacent rectangular ducts of the stack. The results compared favorably, lending confidence to the previous analysis. The simulations performed for the five typical plate-fin passages of small cross section presented results similar to the experimental values obtained from the literature. They were used to evaluate the performance of cross flow compact heat exchangers composed of stacks of these plate-fins. Several parameters like total volume, weight, pumping power, effectiveness, rate of dimensionless entropy generation, and exergetic efficiency were also evaluated to compare the distinct compact heat exchangers
Doutorado
Termica e Fluidos
Mestre em Engenharia Mecânica
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Lavarda, Jairo Vinícius. "Convecção natural de fluidos de lei de potência e de Bingham em cavidade fechada preenchida com meio heterogêneo". Universidade Tecnológica Federal do Paraná, 2015. http://repositorio.utfpr.edu.br/jspui/handle/1/1306.
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CAPESVários estudos numéricos investigaram cavidades fechadas sob o efeito da convecção natural preenchidas com fluidos newtonianos generalizados (FNG) nos últimos anos pelas aplicações diretas em trocadores de calor compactos, no resfriamento de sistemas eletrônicos e na engenharia de polímeros. Neste trabalho é realizada a investigação numérica do processo de convecção natural de fluidos de lei de Potência e de Bingham em cavidades fechadas, aquecidas lateralmente e preenchidas com meios heterogêneos e bloco centrado. O meio heterogêneo é constituído de blocos sólidos, quadrados, desconectados e condutores de calor. Como parâmetros são utilizados a faixa de Rayleigh de 104 à 107, índice de potência n de 0, 6 à 1, 6, número de Bingham de 0, 5 até Bimax , sendo investigado da influência do número de Prandtl para cada modelo de fluido. Nas cavidades com meio heterogêneo são utilizadas as quantidades de blocos de 9, 16, 36 e 64, mantendo-se a razão entre a condutividade térmica do sólido e do fluido κ = 1. Para as cavidades com bloco centrado, são utilizados os tamanhos adimensionais de 0, 1 à 0, 9 com κ = 0, 1; 1 e 10. A modelagem matemática é realizada pelas equações de balanço de massa, de quantidade de movimento e de energia. As simulações são conduzidas no programa comercial ANSYS FLUENT R . Inicialmente são resolvidos problemas com fluidos newtonianos em cavidade limpa, seguida de cavidade preenchida com meio heterogêneo e posteriormente bloco centrado para validação da metodologia de solução. Na segunda etapa é realizada o estudo com os modelos de fluidos de lei de Potência e de Bingham seguindo a mesma sequência. Os resultados são apresentados na forma de linhas de corrente, isotermas e pelo número de Nusselt médio na parede quente. De maneira geral, a transferência de calor na cavidade é regida pelo número de Rayleigh, tamanho e condutividade térmica dos blocos, pelo índice de potência para o modelo de lei de Potência e do número de Bingham para o modelo de Bingham. O número de Prandtl tem grande influência nos dois modelos de fluidos. O meio heterogêneo reduz a transferência de calor na cavidade quando interfere na camada limite térmica para ambos os fluidos, sendo feita uma previsão analítica para o fluido de lei de Potência. Para bloco centrado, a interferência na camada limite com fluido de lei de Potência também foi prevista analiticamente. A transferência de calor aumentou com bloco de baixa condutividade térmica e pouca interferência e com bloco de alta condutividade térmica e grande interferência, para ambos os fluidos.
Many studies have been carried out in square enclosures with generalized Newtonian fluids with natural convection in past few years for directly applications in compact heat exchangers, cooling of electronics systems and polymeric engineering. The natural convection in square enclosures with differently heated sidewalls, filled with power-law and Bingham fluids in addition with heterogeneous medium and centered block are analyzed in this study. The heterogeneous medium are solid, square, disconnected and conducting blocks. The parameters used are the Rayleigh number in the range 104 - 107 , power index n range of 0, 6 - 1, 6, Bingham number range of 0, 5 - Bimax , being the influence of Prandtl number investigated for each fluid model. The number of blocks for heterogeneous medium are 9, 16, 36 and 64, keeping constant solid to fluid conductive ratio, κ = 1. For enclosures with centered block are used the nondimensional block size from 0, 1 to 0, 9, with solid to fluid conductive ratio in range κ = 0, 1; 1 and 10. Mathematical modeling is done by mass, momentum and energy balance equations. The solution of equations have been numerically solved in ANSYS FLUENT R software. Firstly, numerical solutions for validation with Newtonian fluids in clean enclosures are conducted, followed by enclosures with heterogeneous medium and centered block. Subsequently, numerical solutions of power-law and Bingham fluids with same enclosures configurations are conducted. The results are reported in the form of streamlines, isotherms and average Nusselt number at hot wall. In general, the heat transfer process in enclosure is governed by Rayleigh number, size and thermal conductivity of the blocks, power index n for power-law fluid and Bingham number for Bingham fluid. Both fluid models are very sensitive with Prandtl number changes. Heterogeneous medium decrease heat transfer in enclosure when affects thermal boundary layer for both fluid models. One analytical prediction was made for power-law fluid. An increase in heat transfer occurs with low thermal conductivity block and few interference and with high thermal conductivity block and great interference, for both fluids.
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Spinelli, Jose Eduardo. "Simulação do lingotamento continuo de tiras finas de aços". [s.n.], 2000. http://repositorio.unicamp.br/jspui/handle/REPOSIP/264701.
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Orientador: Amauri GarciaDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica
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Resumo: Entende-se por modelagem de processo, o desenvolvimento de uma representação quantitativa ou qualitativa dos fenômenos físicos associados ao processo. Neste trabalho são realizadas simulações do processo twin roll de lingotamento contínuo de tiras de aços, utilizando como referência tecnológica o equipamento piloto instalado nas dependências do Instituto de Pesquisas Tecnológicas do Estado de São Paulo. São construídos dois simuladores para o processo: um simulador da solidificação unidirecional, com molde refrigerado de aço e paredes laterais de material refratário, utilizando-se o aço inoxidável 304 como material de simulação; e variando-se as temperaturas de vazamento; e outro simulador a frio, com componentes feitos de acrílico, água como fluido de simulação e permanganato de potássio como corante. Um modelo matemático previamente desenvolvido é utilizado para confrontar perfis térmicos teóricos com perfis experimentais, para a determinação do coeficiente de transferência de calor metal/molde. O levantamento de valores de espaçamento dendrítico secundário é realizado nas amostras, além da observação simultânea das estruturas de solidificação, o que comprovou a eficiência do simulador em caracterizar o processo de solidificação do equipamento piloto. O uso do modelo frio permitiu a caracterização do posicionamento de barreira a 15 cm ou a 20 cm da lateral esquerda do distribuidor como a melhor configuração
Abstract: It can be understood by process modeling the development of a quantitative or qualitative representation of the physical phenomena associated to the process. In this work, simulations concerning the twin roll continuous caster of steels process at IPT (Instituto de Pesquisas Tecnológicas do Estado de São Paulo) are performed. Two simulators were developed: (i) a simulator of unidirectional solidification with cooled steel mold and refractory lateral walls, by using a stainless steel as the reference metal (AISI 304), and varying superheat temperatures; (ii) a physical model, with components made of acrylic, water as the simulation fluid and potassium permanganate as a pigment. A previously developed mathematical model has been used to determine the metal/mold heat transfer coefficient by a method that compares experimenta1ltheoretical temperature curves. Measurement of secondary dendrite arm spacings is performed by microestructural examination of the samples, confirming the simulator efficiency in characterizing the solidification process in the pilot equipment. The use of the physical model has permitted to attain the best configuration for the tundish, by positioning the dam 15 cm or 20 cm from the left side of tundish
Mestrado
Materiais e Processos de Fabricação
Mestre em Engenharia Mecânica
Libros sobre el tema "Heat – Transmission – Computer simulation"
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Numerical simulations of heat transfer and fluid flow on a personal computer: Incorporating simulation programs on diskette. Amsterdam: Elsevier, 1993.
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seminar, Eurotherm. Advanced concepts and techniques in thermal modelling: Proceedings of the Eurotherm seminar 36, September 21-23, 1994, Poitiers, France. Editado por Fiebig Martin, Lemonnier Denis, Saulnier Jean-Bernard y Ecole nationale supérieure de mécanique et d'aérotechnique (Poitiers, France). Laboratoire d'études thermiques. Amsterdam: Elsevier, 1996.
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Wright, J. L. Measurement and computer simulation of heat transfer in glazing systems. Ottawa, Ont: Efficiency and Alternative Energy Technology Branch, Energy, Mines and Resources Canada, 1991.
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Analytis, G. Th. Assessment of interfacial shear and wall heat transfer of RELAP5/MOD2/36.02 during reflooding. Washington, DC: Office of Nuclear Regulatory Research, U.S. Nuclear Regulatory Commission, 1989.
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Pakanen, Jouko. An ARMAX-model approach for estimating static heat flows in buildings: A methods for computerised energy allocation systems. Espoo [Finland]: Technical Research Centre of Finland, 2002.
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Tuomaala, Pekka. Implementation and evaluation of air flow and heat transfer routines for building simulation tools. Espoo [Finland]: VTT, 2002.
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Kisilewicz, Tomasz. Wpływ izolacyjnych, dynamicznych i spektralnych właściwości przegród na bilans cieplny budynków energooszcze̜dnych. Kraków: Wydawn. Politechniki Krakowskiej, 2008.
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Christoph, Clauser, ed. Numerical simulation of reactive flow in hot aquifers: SHEMAT and processing SHEMAT. Berlin: Springer, 2003.
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Xu, Kun. Rayleigh-Beńard simulation using gas-kinetic BGK scheme in the incompressible limit. Hampton, Va: Institute for Computer Applications in Science and Engineering, NASA Langley Research Center, 1998.
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Roland, Fortunier, ed. Finite element simulation of heat transfer. London: ISTE Ltd., 2008.
Buscar texto completoCapítulos de libros sobre el tema "Heat – Transmission – Computer simulation"
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O’Kelly, Peter. "Heat Transfer". En Computer Simulation of Thermal Plant Operations, 181–206. New York, NY: Springer New York, 2012. http://dx.doi.org/10.1007/978-1-4614-4256-1_8.
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O’Kelly, Peter. "Heat Exchangers". En Computer Simulation of Thermal Plant Operations, 207–33. New York, NY: Springer New York, 2012. http://dx.doi.org/10.1007/978-1-4614-4256-1_9.
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O’Kelly, Peter. "Furnaces, Fuels and Heat Release". En Computer Simulation of Thermal Plant Operations, 259–300. New York, NY: Springer New York, 2012. http://dx.doi.org/10.1007/978-1-4614-4256-1_11.
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Baerdemaeker, J. y B. Nicolai. "Simulation of Heat Transfer Processes Using Stochastic Parameters". En Food Properties and Computer-Aided Engineering of Food Processing Systems, 557–63. Dordrecht: Springer Netherlands, 1989. http://dx.doi.org/10.1007/978-94-009-2370-6_43.
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Gadeikytė, Aušra y Rimantas Barauskas. "Computer Simulation of Heat Exchange Through 3D Fabric Layer". En Numerical Methods and Applications, 392–99. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-10692-8_44.
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Sorin, Adrian y Filip Ciolacu. "Modelling of Reverse Problem in Heat Transfer". En Microstructures, Mechanical Properties and Processes - Computer Simulation and Modelling, 356–61. Weinheim, FRG: Wiley-VCH Verlag GmbH & Co. KGaA, 2005. http://dx.doi.org/10.1002/3527606157.ch56.
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Chen, Qiong. "Molecular Dynamic Simulation for Heat Capacity of MgSiO 3 Perovskite". En Communications in Computer and Information Science, 24–28. Berlin, Heidelberg: Springer Berlin Heidelberg, 2014. http://dx.doi.org/10.1007/978-3-662-45049-9_4.
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Meng, Xiangci. "Numerical Simulation Study on Heat Exchange Effect of Open Computer". En Communications in Computer and Information Science, 83–90. Singapore: Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-13-5919-4_8.
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Miroshnichenko, Igor y Mikhail Sheremet. "Numerical Simulation of Heat Transfer in an Enclosure with Time-Periodic Heat Generation Using Finite-Difference Method". En Lecture Notes in Computer Science, 149–62. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-50436-6_11.
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Stepanov, Sergei P., Ivan K. Sirditov, Petr N. Vabishchevich, Maria V. Vasilyeva, Vasiliy I. Vasilyev y Anastasiya N. Tceeva. "Numerical Simulation of Heat Transfer of the Pile Foundations with Permafrost". En Lecture Notes in Computer Science, 625–32. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-57099-0_71.
Texto completoActas de conferencias sobre el tema "Heat – Transmission – Computer simulation"
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Zhou, Jianxu, Chengmin Bi y Ming Hu. "Computer Simulation of the Hydropower Stations With Long Pressurized Pipelines and Far Transmission Line". En ASME 2008 Fluids Engineering Division Summer Meeting collocated with the Heat Transfer, Energy Sustainability, and 3rd Energy Nanotechnology Conferences. ASMEDC, 2008. http://dx.doi.org/10.1115/fedsm2008-55288.
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With the rapid development of automatic technology and computer science in the hydropower stations, the computer simulation system named as simulator is developed quickly and applied widely especially as a modern training tool for field operators. In the project of power transmission from west to east in Southwest China, there are lots of hydropower stations with long pressurized pipelines and far transmission line, so their simulators are more complex to be built correctly to show the characteristic of hydraulic-mechanical-electrical system and its dynamic procedure distinctly in real time. Based on the characteristic analysis of hydraulic system and long transmission system, a new easily-decoupled elastic model of water flow in pressurized pipelines is given and recommended, and its application and the choice of appropriate model order are analyzed considering the effect of power system, furthermore, how to build the model of far transmission line is discussed in detail based on its state equations. The results indicate that, in order to realize the truthfulness and robustness of the simulator, the higher order oscillation mode of water flow in long pressurized pipelines should be introduced and the frequency property of far transmission line should be analyzed.
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Feng, Yaonan y Xiaorui Dong. "Notice of Retraction: Simulation of engine heat transmission on the grounds of module". En 2010 International Conference on Computer Application and System Modeling (ICCASM 2010). IEEE, 2010. http://dx.doi.org/10.1109/iccasm.2010.5622786.
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Cheney, Drew A. y Jennifer R. Lukes. "Comparison of Atomistic and Continuum Methods for Calculating Ballistic Phonon Transmission in Nanoscale Waveguides". En ASME 2012 Third International Conference on Micro/Nanoscale Heat and Mass Transfer. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/mnhmt2012-75264.
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We compare two methods for the calculation of mode dependent ballistic phonon transmission in nanoscale waveguides. The first method is based on continuum acoustic waveguide theory and uses an eigenmode expansion to solve for phonon transmission coefficients. The second method is an atomistic, lattice dynamics (LD)-molecular dynamics (MD) hybrid that uses LD computed mode shapes to excite guided phonon wavepackets in a nonequilibrium MD simulation and calculates phonon transmission from the final distribution of system energy. The two methods are compared for a planar waveguide with a t-stub irregularity, a geometry which has been proposed for the tuning of phonon transmission and nanostructure thermal conductance. Our comparison highlights advantages and disadvantages of the two methods and illustrates regimes when atomistic effects are prominent and continuum approaches are not appropriate.
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Liu, Jian-Qin. "A robust controller of dynamic networks and its verification by the simulation of the heat shock response network with reliable signal transmission". En IEEE INFOCOM 2011 - IEEE Conference on Computer Communications Workshops. IEEE, 2011. http://dx.doi.org/10.1109/infcomw.2011.5928864.
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Estejab, Bahareh y John Tobin. "Mineral Oil As an Alternative Cooling Method". En ASME 2021 30th Conference on Information Storage and Processing Systems. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/isps2021-65201.
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Abstract In an effort to increase the performance ceiling and reduce the size of modern personal computers especially gaming computers and consequently data centers and supercomputers, mineral oil is proposed as the working fluid to cool the system. Mineral oil operates as an avenue for transmission rather than a liquid heatsink for heat storage, which differentiates this project from traditional mineral oil systems. Using non-conductive liquid as cooling fluid brings many advantages due to its higher convective heat transfer coefficient, which leads to more compact computers, higher speed of data transition, more efficient processors, lower noise levels, and less upkeep costs with respect to data centers. Modeling and simulations are done in NX to gauge temperature expectations; which is the most important limitation when designing and testing a computer before construction. The temperature range was found to be 34°C–50°C in the motherboard and 45°C–67°C in the graphic card. Based on the modeling results, a prototype of the proposed computer is built and tested. Ultimately, this project is trying to open up an avenue through which processor design can be reconsidered.
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Tejwani, Gopal D. "Transmittance and Radiance Computations for Rocket Engine Plume Environments". En ASME 2003 Heat Transfer Summer Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/ht2003-47406.
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Rocket engine exhaust plume is generally thermal in character arising from changes in the internal energy of constituent molecules. Radiation from the plume is attenuated in its passage through the atmosphere. In the visible and the infrared region of the spectrum for clear-sky conditions, this is caused mainly through absorption by atmospheric molecular species. The most important combustion-product molecules giving rise to emission in the IR are water vapor, carbon dioxide, and carbon monoxide. In addition, the high temperature plume reacting with the surrounding atmosphere may produce nitrogen oxides, in the boundary layer, all of which are strongly emitting molecules. Important absorbing species in the atmosphere in the engine plume environment are H2O, CO, CO2, CH4, N2O, NO, and NO2. Under normal atmospheric conditions, the concentrations of O3, SO2, and NH3 are too small to produce any significant absorption. Essentially the problem comprises of the propagation of radiation from a hot gas source through a long cool absorbing atmosphere thus combining aspects of atmospheric and combustion gas methods. Since many of the same molecular species are responsible for both emission and absorption, the high degree of line position correlation between the emission and absorption spectra precludes the decoupling of the optical path into isolated emitter and absorber regions and multiplying the source band radiance by the absorber band transmittance in order to arrive at the transmitted radiance spectrum. Also, very strong thermal gradients may be encountered. All this suggests that a layer-by-layer computation is called for. The pathlength through the plume and the atmosphere is assumed to go through a certain number of layers, each of which is considered to have all molecular species in local thermodynamic equilibrium at constant temperature and pressure within the layer. Radiative transfer problems can be visualized as a set of parallel layers orthogonal to the line of sight, each with an input radiance from the previous layer and an output radiance to the subsequent layer. The MODTRAN (MODerate resolution TRANsmission) code is ideally suited for layer-by-layer absorption/emission calculations for atmospheric molecular species. We have utilized MODTRAN 4.0 computer code, implemented on a Power Mac G3, for the radiance and transmittance computations. The MODTRAN code has been adapted for the engine plume radiance computations. If the plume composition and flowfield parameters such as the temperature and pressure values are known along the line of sight by means of the experimental measurements or (more likely) CFD simulations, one can compute the radiance from any plume with high degree of accuracy at any desired point in space. Emission and absorption characteristics of several atmospheric and combustion species have been studied and presented in this paper with reference to the rocket engine plume environments at the Stennis Space Center. In general transmittance losses can not be neglected for any pathlength of 2 m or more. We have also studied the effect of clouds, rain, and fog on the plume radiance/transmittance. The transmittance losses are severe if any of these occur along the line of sight. Preliminary results for the radiance from the exhaust plume of the space shuttle main engine are shown and discussed.
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Zhang, Yunjia y Dengfang Ruan. "Investigation on the Lubrication Performances and Thermal Characteristics of the Tapered Roller Bearing". En ASME 2017 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/detc2017-67052.
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In this paper, the tapered roller bearing supported on the output shaft of the dual clutch transmission was studied. During the operating process of the DCT (Dual Clutch Transmission) gearbox, the heat generation of the bearing is very large due to the large operating load and high operating speed, which will easily result in bearing failure, such as pitting and abrasion, so it is necessary to investigate the lubrication performances and thermal characteristics of the tapered roller bearing. The simulation models considering or not considering the roller’s spinning (the rollers rotating on their own axles) were established based on Ansys Fluent software. The influences of the roller’s spinning on the lubrication performances of the bearing were analyzed. Furthermore, the transit heat transfer properties of the bearing were simulated and analyzed. The roller’s spinning and transit heat boundary specification were realized by using UDF (user-defined functions). At the same time, the lubrication performances and heat transfer properties of the bearing with different operating conditions are presented and analyzed.
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Jaworski, Maciej, Ryszard Wnuk, Małgorzata Cieślak y Bogna Goetzendorf-Grabowska. "Experimental Investigation and Mathematical Modelling of Thermal Performance Characteristics of Textiles Incorporating Phase Change Materials (PCMs)". En Environmental Engineering. VGTU Technika, 2017. http://dx.doi.org/10.3846/enviro.2017.260.
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Impregnation of textiles (fabrics) by phase change materials (PCMs) changes their thermal properties. High thermal capacity of PCMs, due to large enthalpy of phase change (latent heat), increases the potential of these materials for heat accumulation, but also modifies heat transfer in transient states what improves their insulating characteristics. The paper presents selected results of both experimental and theoretical investigation of the thermal behavior of textiles impregnated with phase change materials, PCMs, under variable thermal loads. Thermal capacity of textiles containing different amounts of microencapsulated PCM were measured with DSC. Then, their thermal behavior characteristics were investigated under irradiation from a solar simulator (heating phase) and during cooling in the regime of natural convection. Mathematical model of heat transfer in the textiles, including radiative and convective boundary conditions, was formulated. Computer simulations of the processes under study, validated on the base of experimental results, allowed to determine important properties of the textiles, such as coefficients of absorption and transmission for solar radiation. Overall thermal characteristics of the textiles, i.e. temperature variations under different thermal loads, are also presented in the paper.
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Chung, Chih-Ang, Ci-Siang Lin y Ci-Jyun Ho. "Computational Study of Hydrogen Storage Performance in Metal Hydride Reactors". En ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2010. http://dx.doi.org/10.1115/esda2010-24059.
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Hydrogen as the most abundant element on Earth is viewed to be a promising energy carrier. For transmission, hydrogen stored as metal hydrides is a potent candidate for its advantages in safe and reliability and being able to offer high energy density compared to the conventional ways such as high pressure gas and liquefaction. Metal hydriding is basically an exothermic process. The heat released will cause an increase in temperature and raise the absorption equilibrium pressure as high as that of the supplied hydrogen gas, which may in turn stop the hydriding process. On the other hand, metal dehydriding is an endothermic process. A temperature decrease can retard desorption and even bring down the dissociation equilibrium pressure as low as the back pressure to stop dehydriding. Therefore, reducing thermal resistance of the storage vessels and enhancing heat transfer of the storage system have become a critical issue for the success of hydrogen storage using metal hydrides. This work models the metal hydriding/dehydriding process in order to assess the vessel design on heat transfer enhancement to improve the performance of hydrogen storage with metal hydrides. First of all, the thermal-fluid behavior of hydrogen storage was modeled including gas flow and energy equations. The vessel is considered to be equipped with an air pipe at the centre line with internal fins. Detailed theoretical models that describe force convection of the heat exchange pipe and natural convection at the lateral wall are constructed. Results from the simulation show that the addition of a concentric heat exchanger pipe with fins can enhance the reaction rates. The work demonstrates how computer aided engineering can be applied to evaluate the performance of hydrogen storage designs, and help reduce experimental efforts in developing the hydrogen storage systems.
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Liang, Jianyu y Zhenhai Xia. "Synthesis and Properties of Cobalt Nanowires". En 2007 First International Conference on Integration and Commercialization of Micro and Nanosystems. ASMEDC, 2007. http://dx.doi.org/10.1115/mnc2007-21298.
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Understanding the structure and properties of metal nanowires is critical for the atomic-scale manipulation, design and application of those materials. Currently, active research on structure and behavior of various metallic nanowires has been carried out by computer simulation. Much experimental work has been done for synthesizing various metal nanowires by many different methods. To experimentally explore the mechanism of the behavior of and the development of structures in the nanowires, it is desirable to have the capability of synthesis various metal nanowires with controlled size, length, uniformity and aspect ratio. It is also desirable to further process those metal nanowires to engineer their properties. In our study, a template assisted fabrication method has been employed to fabricate various metal nanowire arrays, including cobalt, iron and nickel. This fabrication method offers us command over the size and length of the nanowires with excellent uniformity. Heat treatments were used to further process the metal nanowires. The structure of cobalt nanowire array has been investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Mechanical properties of the metal nanowire array will be investigated through nanoindentation and atomic force microscopy (AFM).
Informes sobre el tema "Heat – Transmission – Computer simulation"
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Kilaas, R. Computer simulation of high resolution transmission electron micrographs: theory and analysis. Office of Scientific and Technical Information (OSTI), marzo de 1985. http://dx.doi.org/10.2172/5649044.
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Georgiev, G. Evt, V. Manolov, Ya Lukarski y At Baikushev. Computer Simulation of the Heat Transfer in a Tool for Reinforcement Steel Production. Prof. Marin Drinov Publishing House of Bulgarian Academy of Sciences, marzo de 2018. http://dx.doi.org/10.7546/engsci.lv.18.01.03.
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Ally, M. R. Computer simulation of absorption heat pump using aqueous lithium bromide and ternary nitrate mixtures. Office of Scientific and Technical Information (OSTI), junio de 1988. http://dx.doi.org/10.2172/6955013.
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Russo, David y William A. Jury. Characterization of Preferential Flow in Spatially Variable Unsaturated Field Soils. United States Department of Agriculture, octubre de 2001. http://dx.doi.org/10.32747/2001.7580681.bard.
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Preferential flow appears to be the rule rather than the exception in field soils and should be considered in the quantitative description of solute transport in the unsaturated zone of heterogeneous formations on the field scale. This study focused on both experimental monitoring and computer simulations to identify important features of preferential flow in the natural environment. The specific objectives of this research were: (1) To conduct dye tracing and multiple tracer experiments on undisturbed field plots to reveal information about the flow velocity, spatial prevalence, and time evolution of a preferential flow event; (2) To conduct numerical experiments to determine (i) whether preferential flow observations are consistent with the Richards flow equation; and (ii) whether volume averaging over a domain experiencing preferential flow is possible; (3) To develop a stochastic or a transfer function model that incorporates preferential flow. Regarding our field work, we succeeded to develop a new method for detecting flow patterns faithfully representing the movement of water flow paths in structured and non-structured soils. The method which is based on application of ammonium carbonate was tested in a laboratory study. Its use to detect preferential flow was also illustrated in a field experiment. It was shown that ammonium carbonate is a more conservative tracer of the water front than the popular Brilliant Blue. In our detailed field experiments we also succeeded to document the occurrence of preferential flow during soil water redistribution following the cessation of precipitation in several structureless field soils. Symptoms of the unstable flow observed included vertical fingers 20 - 60 cm wide, isolated patches, and highly concentrated areas of the tracers in the transmission zone. Soil moisture and tracer measurements revealed that the redistribution flow became fingered following a reversal of matric potential gradient within the wetted area. Regarding our simulation work, we succeeded to develop, implement and test a finite- difference, numerical scheme for solving the equations governing flow and transport in three-dimensional, heterogeneous, bimodal, flow domains with highly contrasting soil materials. Results of our simulations demonstrated that under steady-state flow conditions, the embedded clay lenses (with very low conductivity) in bimodal formations may induce preferential flow, and, consequently, may enhance considerably both the solute spreading and the skewing of the solute breakthrough curves. On the other hand, under transient flow conditions associated with substantial redistribution periods with diminishing water saturation, the effect of the embedded clay lenses on the flow and the transport might diminish substantially. Regarding our stochastic modeling effort, we succeeded to develop a theoretical framework for flow and transport in bimodal, heterogeneous, unsaturated formations, based on a stochastic continuum presentation of the flow and a general Lagrangian description of the transport. Results of our analysis show that, generally, a bimodal distribution of the formation properties, characterized by a relatively complex spatial correlation structure, contributes to the variability in water velocity and, consequently, may considerably enhance solute spreading. This applies especially in formations in which: (i) the correlation length scales and the variances of the soil properties associated with the embedded soil are much larger than those of the background soil; (ii) the contrast between mean properties of the two subdomains is large; (iii) mean water saturation is relatively small; and (iv) the volume fraction of the flow domain occupied by the embedded soil is relatively large.
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Floyd, Jason y Daniel Madrzykowski. Analysis of a Near Miss in a Garden Apartment Fire – Georgia 2022. UL's Fire Safety Research Institute, octubre de 2022. http://dx.doi.org/10.54206/102376/rsfd6862.
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On February 9, 2022, Cobb County Fire and Emergency Services responded to a fire in a ground floor unit in a garden apartment building. At arrival, the fire was a post-flashover fire in a bedroom. Initial fire control was attempted by an interior fire attack team which was unable to quickly locate the fire. Exterior suppression through the bedroom window was started prior to discovery of the fire by the interior team. Shortly after fire discovery by the internal team, a mayday was called. Four firefighters from the interior fire attack team received first and second degree burns. This report analyzes photographic, video, and written documentation from the incident to evaluate the timeline of the incident and to assess the fire conditions present. Computer modeling using the Fire Dynamics Simulator (FDS) was performed to provide further insight into the fire conditions and the impact of decisions and actions on the fire ground. Additionally, data from a full scale fire test of a similar fire in a similar structure was used to provide additional insight. Four FDS simulations were performed in support of the analysis. These included a simulation of the event as it unfolded and three simulations looking at the impact of alternate tactics which included: initial exterior attack prior to entry, the use of a smoke curtain to protect the building exit path, and interior only attack. FDS simulations provided insight on the heat present in the apartment during the fire and the impact of the interior and exterior suppression on conditions inside the apartment. Full scale test data of a similar fire showed similar behavior to the FDS predictions and gives credence to the FDS results. Results of the analysis suggest that injuries resulted from the length of time the interior attack team was present inside the apartment before actions were taken to reduce the severity of the fire. Six contributing factors were identified including size-up, communication and accountability, delayed exterior attack, lack of entry hall protection, the apartment layout and construction, thermal imager use, and mayday procedures and training. The last contributing factor was a positive contribution that helped avoid more serious injuries. Based on the contributing factors, five recommendations were made that include improved size-up, exterior fire control to prevent exterior spread, protection of exit pathways, basing fire ground tactics on known information, and recognizing when a change in tactics is needed.
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HST3D; a computer code for simulation of heat and solute transport in three-dimensional ground-water flow systems. US Geological Survey, 1987. http://dx.doi.org/10.3133/wri864095.
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