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1
Gwebu, Excellent Zibhekele. "Transient boiler heat exchanger thermal behaviour analysis." Master's thesis, University of Cape Town, 2014. http://hdl.handle.net/11427/13230.
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Includes bibliographical references.<br>Coal fired power plants that were built in the past four decades are aging. The main aging mechanisms are creep and thermal fatigue. Creep results from the high temperatures at which the components operate. Thermal fatigue is due to thermal stresses and these stresses result from temperature gradients within the material. Cycling of these thermal stresses accelerate the creep in a process called creep- fatigue aging. The boiler and its final heat exchangers and headers are the main components that are affected by these mechanisms. The aging of these components results in high maintenance costs, reduction of the plant reliability and availability, and contribute to increased safety risks for the plant and personnel. Therefore, there is a need to understand the steady state and dynamic behaviour of the components of these plants in order to predict the stresses that the material experience. This report discusses an investigation to the possibility of modelling the thermal dynamic behaviour of typical boiler heat exchanger components which have to withstand the highest temperature of a Pulverised Fuel Rankine cycle power plant. Thus, illuminating the issues that need to be addressed in modelling such heat exchangers. Modelling approaches of heat exchangers are systematically presented, starting with the use of exact analytical solutions. This is followed by the application of finite volume numerical method. Finishing off with the use of the Flownex software. The exact analytical solutions are used to characterise the transient temperature distribution in solid materials with simplified heat transfer, highlighting the dependence of the solutions on the Fourier number and Biot number. These solutions are further used to calculate thermal stresses generated in the material, illustrating the relationship between thermal stresses and temperature gradients. Furthermore, a finite volume solution is applied to modelling an infinitely long tube. I t is illustrated that for transient conduction heat transfer problems, the solution depends on both physical space discretisation and time- wise discretisation. The numerical solution is verified against the exact analytical solution. Finally, the Flownex software is used to illustrate the issues that need to be addressed when modelling the transient behaviour of a heat exchanger . For this purpose only the average area discretisation scheme is used since it allows for any generic solid structure to be modelled, provided that the appropriate level of discretization is applied. The Flownex modelling starts by modelling transient conduction heat transfer within an infinitely long tube. The Flownex solution is verified against the finite volume numerical solution. The Flownex solution depends on thickness discretisation, especially for thick cylindrical components. Finite tubes are also modelled on Flownex including axial discretisation and layout simplification of the tubes. Flownex is also used to model a heat exchanger bundle using two methods; a tube by tube method and a method that involves the combination of all ii the tubes into one tube. The product of the thermal resistance and the capacitance of the system governs the transient simulations for both methods.
2
Boo, Joon-Hong. "Transient analysis of heat pipe radiators for space station applications." Diss., Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/19553.
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Thuppal, Vedanta Srivatsan, and Naga Vamsi Krishna Kora. "HEAT TRANSIENT TRANSFER ANALYSIS OF BRAKE DISC /PAD SYSTEM." Thesis, Blekinge Tekniska Högskola, Institutionen för maskinteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-13461.
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Braking is mainly controlled by the engine. Friction between a pair of pads and a rotating disc converts the kinetic energy of the vehicle into heat. High temperatures can be reached in the system which can be detrimental for both, components and passenger safety. Numerical techniques help simulate load cases and compute the temperatures field in brake disc and brake pads. The present work implements a Finite Element (FE) toolbox in Matlab/Simulink able to simulate different braking manoeuvres used for brake dimensioning mainly in the early phase of car development process. The brake pad/disc geometry is considered as an axisymmetric body assuming negligible temperature gradient along the circumference of the disc. Calibration using three control factors namely: heat coefficient during braking , acceleration and emissivity for the implemented thermal model is performed using experimental investigation at Volvo Car Corporation (VCC) for three specific severe load cases. The thermal model is extended to measure brake fluid temperatures to ensure no vaporisation occurs. Simulation results of the brake disc and brake pad show good correlation with the experimental tests. A sensitivity analysis with the control factors showed convective coefficient during acceleration the most sensitive, with temperature change of around 16%.
4
Hendrix, Walter Adrian. "An analysis of body force effects on transient and steady-state performance on heat pipes." Diss., Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/16678.
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Alshatti, Rashid Ali. "Heat Transfer Analysis of Slot Jet Impingement onto Roughened Surfaces." Scholar Commons, 2015. http://scholarcommons.usf.edu/etd/5898.
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The effect of surface roughness on jet impingement heat transfer was investigated in this research. A numerical analysis was conducted for free surface slot jet impinging normally onto a heated plate. Six different geometries and three different plate materials were investigated. The cooling fluid used for the analysis was water, and the flow was laminar with a range of Reynolds number (Re) from 500 to 1000. Temperature distribution, local and average heat transfer coefficient, and local and average Nusselt number were presented for each case.
The steady state heat transfer results show that the increase in Reynolds number (Re) increases the local heat transfer coefficient and the local Nusselt number. Impinging the jet nozzle directly onto a step has a better heat transfer enhancement than impinging the jet nozzle in between steps. Materials with low thermal conductivity exhibit large variation in temperature along the solid-fluid interface. The variations of the interface temperature become smaller between all cases when applying the isothermal boundary condition.
The transient heat transfer results show that the temperature of the interface increases with time until steady state condition is met. Materials with high thermal diffusivity reach the steady state condition with less time. The increase in surface roughness increases the time required to reach the steady state condition. The highest rates of heat transfer were found at locations where no fluid recirculation occurs. It takes less time to reach steady state condition when applying the isothermal boundary condition at the bottom surface of the plate.
6
Carper, Jayme Lee. "Verification and Validation of a Transient Heat Exchanger Model." Wright State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=wright1441064582.
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Tijiboy, Jose Carlos. "Steady and Transient Analysis of Flow and Heat Transfer in SPND Assembly." Thesis, Virginia Tech, 2008. http://hdl.handle.net/10919/36240.
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This thesis presents the analysis of flow and heat transfer for the SPND (Self-Powered Neutron Detector) system used within the nuclear reactor core in the U.S. Evolutionary Power Reactor developed by AREVA. The SPND system is composed of six individual detectors which are used for in-core measurement of thermal neutron flux. The study of the SPND system is important since this system provides information and signals necessary for safe reactor operation and control. The main goal of the project was to determine the maximum temperature for the SPND detectors under three different operating scenarios. The maximum temperature of the detectors is of special interest, since if it exceeds a limiting temperature of 622 K then the accuracy of the information provided by the system is reduced. All of the flow and heat transfer simulations were performed using the commercial software Fluent. <p>
The first scenario that was studied was for the system under normal operating conditions. For this case, the maximum temperature for a detector was determined to be 603.4 K, which is within the proper range of operation. It was also important to determine the maximum temperature of the fluid within the SPND assembly in order to ascertain that boiling does not occur within the system during normal operation. The maximum fluid temperature was found to be 613.7 K, which is below the boiling temperature of water (618.05 K) at an operating pressure of 2250 psi.
<p>
The second scenario involved an increase in the power of the reactorâ s core by a factor of 17% in a 30 second period. The results of the unsteady calculation indicated that the maximum temperature for a detector was 608.5 K. The results also indicate that no boiling occurs inside of the SPND system.
<p>
The third scenario involved a loss of coolant flow in the SPND system. This reduction in flow rate caused the maximum temperature of the detectors to reach 619.6 K. For this case, boiling occurs within the guide tube and protection tube.<br>Master of Science
8
Samayamantula, Sri Prithvi Samrat. "Development of a Computer Program for Transient Heat Transfer Coefficient Studies." Wright State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=wright15581072805784.
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Franchetta, Matteo. "Experimental and transient computational fluid dynamic analysis of vehicle underhood in heat soak." Thesis, University College London (University of London), 2006. http://discovery.ucl.ac.uk/1444411/.
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Simulation-based analyses of underhood compartments are proving to be crucially important in a vehicle development program, reducing test work and time-to-market. While Computational Fluid Dynamics (CFD) simulations of steady forced flows have demonstrated reliable, studies of transient natural convective flows in engine compartments under thermal soak are not yet carried out due the high computing demands and lack of validated work. The present work assesses the practical feasibility of applying the CFD tool at the initial stage of a vehicle development programme for investigating the thermally-driven flow in an engine bay. A typical vehicle underhood was reproduced in half-scale for laboratory investigations. Surface temperatures of components, airflow patterns induced by the buoyant forces as well as the spatial distribution of the air temperature were measured under both steady and transient thermal conditions. Temperature mappings were obtained with thermocouples whereas airflow magnitudes and directions were determined with Particle Image Velocimetry (PIV) instrumentation. The detailed measurements were used as reference for validating the corresponding CFD simulations carried out with the software VECTIS. Experimental and numerical data correlated well in steady state, both quantitatively and qualitatively. A computation procedure that enables pseudo time-marching simulations to be performed with significantly reduced CPU time usage, in comparison to traditional fully-conservative transient simulations, was also developed. The methodology used a unique combination of CFD solver parameters to overcome the computationally challenging problem of solving for momentum transport in time-marching mode and for a long period of physical time. The procedure was successful in providing a detailed and time-accurate flow and thermal simulation of the underhood model during transient cooling. Such simulation would not have been practically feasible with a standard transient simulation. A reduction in CPU processing time in excess of 90% was achieved with good correlation between the CFD predictions and the experimental data.
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Erhart, Kevin. "EFFICIENT LARGE SCALE TRANSIENT HEAT CONDUCTION ANALYSIS USING A PARALLELIZED BOUNDARY ELEMENT METHOD." Master's thesis, University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2973.
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A parallel domain decomposition Laplace transform Boundary Element Method, BEM, algorithm for the solution of large-scale transient heat conduction problems will be developed. This is accomplished by building on previous work by the author and including several new additions (most note-worthy is the extension to 3-D) aimed at extending the scope and improving the efficiency of this technique for large-scale problems. A Laplace transform method is utilized to avoid time marching and a Proper Orthogonal Decomposition, POD, interpolation scheme is used to improve the efficiency of the numerical Laplace inversion process. A detailed analysis of the Stehfest Transform (numerical Laplace inversion) is performed to help optimize the procedure for heat transfer problems. A domain decomposition process is described in detail and is used to significantly reduce the size of any single problem for the BEM, which greatly reduces the storage and computational burden of the BEM. The procedure is readily implemented in parallel and renders the BEM applicable to large-scale transient conduction problems on even modest computational platforms. A major benefit of the Laplace space approach described herein, is that it readily allows adaptation and integration of traditional BEM codes, as the resulting governing equations are time independent. This work includes the adaptation of two such traditional BEM codes for steady-state heat conduction, in both two and three dimensions. Verification and validation example problems are presented which show the accuracy and efficiency of the techniques. Additionally, comparisons to commercial Finite Volume Method results are shown to further prove the effectiveness.<br>M.S.M.E.<br>Department of Mechanical, Materials and Aerospace Engineering;<br>Engineering and Computer Science<br>Mechanical Engineering
11
Zengeni, Hazel C. "Transient-heat-transfer and stress analysis of a thermal-storage solar cooker module." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/92215.
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Thesis: S.B., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2014.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (page 22).<br>This paper details the analysis carried out in Solidworks to determine the best material and configuration of a thermal-storage solar cooker module.The thermal-storage solar cooker utilizes the high-latent-heat lithium nitrate releases when transitioning from liquid to solid state.However,before this process can transpire the salt has to be completely melted and the energy needed for the melting process is provided by the sun.The purpose of the module is to conduct the solar power from the heat source to the salt.In addition after the melting process,it conducts the latent energy released by the salt to the hot plate used for cooking.<br>by Hazel C. Zengeni.<br>S.B.
12
Jang, Jong Hoon. "An analysis of startup from the frozen state and transient performance of heat pipes." Diss., Georgia Institute of Technology, 1988. http://hdl.handle.net/1853/23018.
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DeBruyn, Adrian Bryan. "Integration of Combined Heat and Power Generators into Small Buildings - A Transient Analysis Approach." Thesis, University of Waterloo, 2006. http://hdl.handle.net/10012/2830.
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Small combined heat and power generators have the potential to reduce energy consumption and greenhouse gas emissions of residential buildings. Recently, much attention has been given to these units. To date, the majority of studies in this field have concentrated on the steady operational performance of a specific generator type, and the available computer models have largely been theoretical in nature. <br /><br /> The main goal of this study was to evaluate the performance of the latest combined heat and power generators, when integrated into Canadian residential homes. A fair comparison of four 1 kW (electrical) units was made. The combined heat and power units studied were based on PEM fuel cell, solid oxide fuel cell, Stirling Engine, and internal combustion engine energy converters. <br /><br /> This study utilized recent test data in an attempt to evaluate the most efficient method of integrating the combined heat and power units into residential houses. Start-up, shut down, and load change transients were incorporated into the simulations. The impact of load variations due to building thermal envelope differences and varying building heating system equipment was evaluated. The simulations were evaluated using TRNSYS software. The building heat demands were determined with eQuest hourly building simulation software. <br /><br /> All of the combined heat and power units under study were capable of providing a net annual benefit with respect to global energy and greenhouse gas emissions. The fuel cells offer the highest integrated performance, followed closely by the internal combustion engine and lastly the Stirling engine. Annual global energy savings up to 20%, and greenhouse gas savings up to 5. 5 tonnes per year can be achieved compared to the best conventional high efficiency appliances. <br /><br /> Heat demand influences performance greatly. As the thermal output of the generator unit approaches half of the average building thermal demand, the system design becomes critical. The system design is also critical when integrating with a forced air furnace. Only the PEM fuel cell unit produces clear global energy and emissions benefits when operating in the summertime.
14
Damm, David L. "Radiative and transient thermal modeling of solid oxide fuel cells." Thesis, Available online, Georgia Institute of Technology, 2005, 2005. http://etd.gatech.edu/theses/available/etd-11162005-155659/.
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Calisto, Hugo Miguel Filipe. "Transient transpiration radiometer : development of a heat flux sensor for high aggressivity environments." Doctoral thesis, Universidade de Aveiro, 2013. http://hdl.handle.net/10773/12457.
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Doutoramento em Engenharia Mecânica<br>The development of a new instrument for the measurement of convective and
radiative is proposed, based on the transient operation of a transpiration
radiometer. Current transpiration radiometers rely on steady state temperature
measurements in a porous element crossed by a know gas mass flow. As a
consequence of the porous sensing element’s intrinsically high thermal inertia,
the instrument’s time constant is in the order of several seconds. The proposed
instrument preserves established advantages of transpiration radiometers while
incorporating additional features that broaden its applicability range. The most
important developments are a significant reduction of the instrument’s response
time and the possibility of separating and measuring the convective and
radiative components of the heat flux. These objectives are achieved through
the analysis of the instrument’s transient response, a pulsed gas flow being
used to induce the transient behavior.<br>Propõe-se o desenvolvimento de um novo instrumento para medição de fluxos
de calor convectivos e radiativos, baseado na operação de um radiómetro de
transpiração em regime transitório. Os radiómetros de transpiração atuais
baseiam-se em medições de temperatura em regime estacionário num
elemento poroso atravessado por um caudal mássico gasoso conhecido.
Como consequência da inércia térmica intrinsecamente elevada do elemento
sensível poroso, a constante de tempo do instrumento é da ordem dos
segundos. O instrumento proposto preservará as vantagens estabelecidas dos
radiómetros de transpiração incorporando características adicionais que
alargarão a gama de aplicabilidade. As novas características mais importantes
serão uma redução significativa do tempo de resposta do instrumento e a
possibilidade de medir separadamente as componentes radiativa e convectiva
do fluxo de calor. Estes objetivos serão conseguidos através da análise da
resposta transitória do instrumento, utilizando-se um caudal pulsado de gás
para induzir o comportamento transitório.
16
Hernandez-Ontiveros, Cesar F. "Numerical analysis of heat transfer during jet impingement on curved surfaces." [Tampa, Fla.] : University of South Florida, 2007. http://purl.fcla.edu/usf/dc/et/SFE0002123.
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Rowe, Scott Christian. "Pilot Plant Analysis, Experiments, and Control for the Hybridization of Transient Solar Heat with Conventional Utilities." Thesis, University of Colorado at Boulder, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10791867.
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<p> The direct capture of solar heat is now commercial for electrical generation at 550 °C (1000 °F), which has provoked interest in solar driven approaches to commodity and fuels production at higher temperatures. However, conventional commodity and fuels facilities often operate continuously regardless of weather and nighttime conditions. Conversely, direct sunlight is immediately lost upon shading by clouds and sunset. Beyond inconvenience, this intermittency has the potential to destroy high temperature equipment through thermal fatigue and thermal shock. To overcome interruptions in solar availability we propose the inclusion of direct sunlight in commodities and fuels production as a supplement to conventional electrical heating. Within this regime conventional utilities are ideally sourced from sustainable stored or orthogonal energy sources. Control is needed to substitute solar, which can be lost within seconds during transient weather, with electrical heat. To explore control strategies for the alternation of solar and electrical heat a new facility was constructed at the University of Colorado, Boulder. Specifically, a 45 kW 18 lamp high-flux solar simulator was erected that approximates the sunlight found in actual concentrated solar plants. Calorimetry was analyzed for the measurement of extreme radiance in this testbed. Results from calorimeter design were applied to radiation measurement from the lamps, which were capable of delivering 9.076±0.190 kW of power to a ?10 cm target with a peak flux of 12.50 MW/m<sup>2</sup> (12,500 “suns”). During this characterization a previously unknown observer effect was seen that differentiates radiative heat from lamps and the energy delivered by sunlight in actual concentrated solar facilities. This characterization allowed confident experimentation within the lamp testbed for control studies on a 15 kW solar-electric tube furnace for commodities and fuels production. Furnace electric heat was manipulated by four different linear control strategies for the rejection weather transients reproduced by the high-flux solar simulator lamps. These included feedback, feedforward feedback, model predictive control, and model predictive control with a weather forecast. It was found that model predictive control with a forecast best maintained furnace conditions. Prior researchers have suggested that forecasts would be useful in solar control, which was shown across simulation and experiment.</p><p>
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Heinz, Karl R. "The application of Brian's method to the solution of transient heat conduction problems in cylindrical geometries." Thesis, Monterey, California. Naval Postgraduate School, 1988. http://hdl.handle.net/10945/22907.
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Approved for public release; distribution is unlimited<br>A FORTRAN 77 computer code employing an adaptation of the finite differencing algorithm proposed by
Brian was developed for the solution of transient heat conduction problems in cylindrical geometries. Validation of code was accomplished by comparison with an analytic solution derived for a
model with symmetric, linear boundary conditions. Accuracy of results for asymmetric and non-linear boundary conditions was determined by comparison with a similarly validated code employing the explicit method. Code effectiveness was then demonstrated by conducting a transient temperature analysis for a simulated earth-orbiting satellite. Brian's method demonstrated unconditional stability with associated significant reductions in execution time compared to the explicit
method. The effects of discretization error on the accuracy of results require further investigation.<br>http://archive.org/details/applicationofbri00hein<br>Lieutenant Commander, United States Navy
19
French, L. de F. "Transient nonlinear heat transfer analysis using the finite element method in the context of the requirements of thermal analysis in a mine." Master's thesis, University of Cape Town, 1990. http://hdl.handle.net/11427/8297.
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Bibliography: leaves 106-108.<br>The aim of this thesis is to develop a computer program, together with a users' guide, to analyse two-dimensional; nonlinear, transient heat conduction in non-isotropic solids using the finite element method. This program is an extension of an existing program that analyses thermomechanical stress in solids which may have prescribed temperature and flux boundary conditions. The program has been extended using the requirements for modelling heat transfer in mines as a guide. The theory of conduction, thermal radiation, convection and heat transfer due to evaporation and condensation is presented.
20
Payette, Gregory Steven. "Mathematical modeling of evaporative cooling of moisture bearing epoxy composite plates." Texas A&M University, 2003. http://hdl.handle.net/1969.1/3857.
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Research is performed to assess the potential of surface moisture evaporative
cooling from composite plates as a means of reducing the external temperature of
military aircraft. To assess the feasibility of evaporative cooling for this application, a
simplified theoretical model of the phenomenon is formulated. The model consists of a
flat composite plate at an initial uniform temperature, T0. The plate also possesses an
initial moisture (molecular water) content, M0. The plate is oriented vertically and at t=0
s, one surface is exposed to a free stream of air at an elevated temperature. The other
surface is exposed to stagnant air at the same temperature as the plateÂs initial
temperature.
The equations associated with energy and mass transport for the model are
developed from the conservation laws per the continuum mechanics hypothesis.
Constitutive equations and assumptions are introduced to express the two nonlinear
partial differential equations in terms of the temperature, T, and the partial density of
molecular water, ρw. These equations are approximated using a weak form Galerkin
finite element formulation and the αÂfamily of time approximation. An algorithm and accompanying computer program written in the Matlab programming language are
presented for solving the nonlinear algebraic equations at successive time steps. The
Matlab program is used to generate results for plates possessing a variety of initial
moisture concentrations, M0, and diffusion coefficients, D.
Surface temperature profiles, over time, of moisture bearing specimens are
compared with the temperature profiles of dry composite plates. It is evident from the
results that M0 and D affect the surface temperature of a moist plate. Surface
temperature profiles are shown to decrease with increasing M0 and/or D. In particular,
dry and moist specimens are shown to differ in final temperatures by as much as 30°C
over a 900 s interval when M0 = 30% and D is on the order of 10Â8m2/s (T0 = 25°C,
h = 60 W/m2°C, T∞ = 90°C).
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Rao, P. Sharath Chandra. "Analysis of fluid circulation in a spherical cryogenic storage tank and conjugate heat transfer in a circular microtube." [Tampa, Fla.] : University of South Florida, 2004. http://purl.fcla.edu/fcla/etd/SFE0000461.
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Hawn, David Phillip. "Development of a Dynamic Model of a Counterflow Compact Heat Exchanger for Simulation of the GT-MHR Recuperator using MATLAB and Simulink." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1236091152.
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Elsheikh, Mutasim Mohamed Sarour. "Numerical Simulations of Heat Transfer Processes in a Dehumidifying Wavy Fin and a Confined Liquid Jet Impingement on Various Surfaces." Scholar Commons, 2011. http://scholarcommons.usf.edu/etd/3090.
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This thesis consists of two different research problems. In the first one, the heat transfer characteristic of wavy fin assembly with dehumidification is carried out. In general, fin tube heat exchangers are employed in a wide variety of engineering applications, such as cooling coils for air conditioning, air pre-heaters in power plants and for heat dissipation from engine coolants in automobile radiators. In these heat exchangers, a heat transfer fluid such as water, oil, or refrigerant, flows through a parallel tube bank, while a second heat transfer fluid, such as air, is directed across the tubes. Since the principal resistance is much greater on the air side than on the tube side, enhanced surfaces in the form of wavy fins are used in air-cooled heat exchangers to improve the overall heat transfer performance. In heating, ventilation, and air conditioning systems (HVAC), the air stream is cooled and dehumidified as it passes through the cooling coils, circulating the refrigerant. Heat and mass transfer take place when the coil surface temperature in most cooling coils is below the dew point temperature of the air being cooled. This thesis presents a simplified analysis of combined heat and mass transfer in wavy-finned cooling coils by considering condensing water film resistance for a fully wet fin in dehumidifier coil operation during air condition. The effects of variation of the cold fluid temperature (-5˚C - 5˚C), air side temperature (25˚C - 35˚C), and relative humidity (50% - 70%) on the dimensionless temperature distribution and the augmentation factor are investigated and compared with those under dry conditions. In addition, comparison of the wavy fin with straight radial or rectangular fin under the same conditions were investigated and the results show that the wavy fin has better heat dissipation because of the greater area. The results demonstrate that the overall fin efficiency is dependent on the relative humidity of the surrounding air and the total surface area of the fin. In addition, the findings of the present work are in good agreement with experimental data.
The second problem investigated is the heat transfer analysis of confined liquid jet impingement on various surfaces. The objective of this computational study is to characterize the convective heat transfer of a confined liquid jet impinging on a curved surface of a solid body, while the body is being supplied with a uniform heat flux at its opposite flat surface. Both convex and concave configurations of the curved surface are investigated. The confinement plate has the same shape as the curved surface. Calculations were done for various solid materials, namely copper, aluminum, Constantan, and silicon; at two-dimensional jet. For this research, Reynolds numbers ranging from 750 to 2000 for various nozzle widths channel spacing, radii of curvature, and base thicknesses of the solid body, were used. Results are presented in terms of dimensionless solid-fluid interface temperature, heat transfer coefficient, and local and average Nusselt numbers. The increments of Reynolds numbers increase local Nusselt numbers over the entire solid-fluid interface. Decreasing the nozzle width, channel spacing, plate thickness or curved surface radius of curvature all enhanced the local Nusselt number. Results show that a convex surface is more effective compared to a flat or concave surface. Numerical simulation results are validated by comparing them with experimental data for flat and concave surfaces.
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Lallave-Cortes, Jorge C. "Numerical heat transfer during partially-confined, confined, and free liquid jet impingement with rotation and chemical mechanical planarization process modeling." [Tampa, Fla] : University of South Florida, 2009. http://purl.fcla.edu/usf/dc/et/SFE0002968.
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Tyukov, Alexei Evgen'evich. "Stochastic and asymptotic analysis applied to the study of stochastic models of classical and quantum mechanics." Thesis, Nottingham Trent University, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366087.
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Guven, Ibrahim. "A coupled finite element-boundary element method for two dimensional transient heat conduction and thermoelastic analyses." Diss., The University of Arizona, 2000. http://hdl.handle.net/10150/289183.
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A new algorithm for coupling boundary and finite element methods is developed for transient two dimensional heat conduction and thermoelastic analyses of regions with dissimilar materials and geometric discontinuities. Such regions are susceptible to failure initiation in electronic devices. As the component size decreases while enhancing performance, the accurate prediction of thermal and thermoelastic response of such devices is critical for achieving acceptable design. This study concerns both the conduction heat transfer and thermoelasticity. Solution to transient heat conduction equation provides the non-uniform thermal field for the thermoelastic analysis. Although the finite element method (FEM) is highly efficient and commonly used, its application with conventional elements to complex layered structures with length parameters varying in order of magnitudes leads to inaccurate and mesh dependent results. The accuracy of the results from the boundary element method (BEM) formulation, which requires computationally intensive integration schemes, is much higher than that of the FEM. This new algorithm combines the advantages of both methods while not requiring the commonly accepted iterations along the interfaces between BEM and FEM domains. The BEM part of the solution, acting as a global element, captures the singular nature of the solution variables arising from geometrical and material discontinuities and, eliminates the mesh dependency.
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Lee, Eung-Sun. "A large-strain, transient-dynamic analysis of head-injury problems by the finite element method." Diss., Georgia Institute of Technology, 1990. http://hdl.handle.net/1853/20753.
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Xing, Mian. "Validation of TRACE Code against ROSA/LSTF Test for SBLOCA of Pressure Vessel Upper-Head Small Break." Thesis, KTH, Kärnkraftsäkerhet, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-95745.
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OECD/NEA ROSA/LSTF project tests are performed on the Large Scale Test Facility (LSTF). LSTF is a full-height, full-pressure and 1/48 volumetrically-scaled two-loop system which aims to simulate Japanese Tsuruga-2 Westinghouse-type 4-loop PWR. ROSA-V Test 6-1 simulates a pressure vessel (PV) upper-head small break loss-of-coolant accident (SBLOCA) with a break size equivalent to 1.9% of the volumetrically scaled cross-sectional area of the reference PWR cold leg.The main objective of present thesis is to build a TRACE calculation model for simulating thermal hydraulic behaviors in LSTF and PV upper-head SBLOCA, so as to assess different modeling options and parameters of TRACE code. The results show that TRACE code well reproduce the complex physical phenomena involved in this type of SBLOCA scenarios. Almost all the events in the experiment are well predicted by the model based on TRACE code. In addition, the sensitivity of different models and parameters are investigated. For example, the code slightly overestimates the break mass flow from upper head which affects the accuracy of the results significantly. The rising of core exit temperature (CET) is significantly influenced by the flow area of leakage between downcomer and hot leg. Besides, the effect of the break location, low pressure injection system (LPIS) and accumulator setup are also studied.
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Dias, Marcio Soares. "Desenvolvimento de modelos analiticos para propriedades termicas e condução de calor transiente em varetas combustiveis nucleares." [s.n.], 2007. http://repositorio.unicamp.br/jspui/handle/REPOSIP/266280.
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Orientadores: Elizabete Jordão, Vanderley de Vasconcelos<br>Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica<br>Made available in DSpace on 2018-08-08T15:54:28Z (GMT). No. of bitstreams: 1
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Previous issue date: 2007<br>Resumo: A dependência com a temperatura das propriedades térmicas dos materiais faz com que a análise do transiente térmico em varetas combustíveis de reatores nucleares seja não-linear. Tradicionalmente, métodos de diferenças finitas ou de elementos finitos são utilizados para resolver este problema. A remoção efetiva do calor gerado nas varetas combustíveis constitui uma das considerações primárias no projeto de reatores nucleares. Os fabricantes de combustíveis nucleares e as geradoras de energia elétrica de fonte nuclear devem demonstrar a segurança do reator através da análise dos resultados de situações transientes diversas. Estes transientes podem ocorrer tanto em operação normal, quanto em situações de acidentes e devem ser analisados para assegurar que a vareta combustível manterá sua integridade para todas estas condições. A equação de transferência de calor para o combustível é não-linear. Esta equação não-linear de diferenciais parciais pode ser convertida em uma forma linear por meio da transformação baseada nas propriedades térmicas. Este trabalho apresenta a análise teórica aplicada no desenvolvimento de um modelo analítico, aqui chamado de variacionais relativos e direcionado para a modelagem de propriedades térmicas de materiais cerâmicos de aplicação nuclear, em particular o dióxido de urânio, UO2, e o óxido de alumínio, Al2O3. As propriedades térmicas modeladas são aquelas envolvidas no processo de condução de calor em materiais cristalinos: expansão térmica, calor específico, condutividade térmica e as suas formas integrais. No processo de avaliação de dados foram utilizados cerca de 5500 medidas de propriedades físicas e térmicas disponíveis na literatura aberta. Com base neste desenvolvimento é estabelecida a relação linear entre a variação de entalpia e a integral de condutividade térmica do UO2. Esta relação permite resolver, analiticamente, as distribuições espacial e temporal de temperaturas no combustível nuclear para as condições de estado estacionário e de transiente. A solução encontrada aplica-se igualmente outros sistemas onde o balanço de energia seja determinado pelo equilíbrio entre calor armazenado e calor transportado. A modelagem analítica desenvolvida amplia as possibilidades de avaliação crítica da consistência de propriedades térmicas e físicas dos materiais<br>Abstract: The temperature dependence of the material thermal properties makes the transient thermal analysis of reactor fuel pins to be non-linear. Traditionally, finite difference or finite element methods have been used to solve this problem. Effective heat removal from the fuel pins of a nuclear reactor poses one of the primary considerations in reactor design. Nuclear fuel vendors and nuclear electricity utilities must demonstrate the safety of the reactor by thorough examination of the outcome of various transient situations. These transient effects may occur in normal operation as well as in accident situations and must be analysed to insure the fuel pin maintains its integrity. The governing heat transfer equation for the fuel is non-linear. This non-linear, partial differential equation can be recast into a linear form by introducing a transformation based on material property. This work presents the theoretical analyses to develop a analytical model, here named model of relative variationals, for modelling of thermal properties of nuclear ceramic materials, in matter uranium dioxide, UO2, and aluminium oxide, Al2O3. The modeled thermal properties are those involved in the process of heat transport in crystalline materials: thermal expansion, specific heat, thermal conductivity and their integral forms. In the data evaluation process were used about 5500 measures of physical and thermal properties available in the open literature. Based on this development, the linear relationship has been established between the UO2 enthalpy and thermal conductivity integral. This relationship enables the heat conduction equation to be solved analytically for steady state and transient conditions. The solution is also applied in other systems where the balance of energy is determined by the equilibrium between stored heat and transported heat. The developed analytical modelling enlarges the possibilities for critical evaluation of the thermal and physical properties of the materials<br>Doutorado<br>Sistemas de Processos Quimicos e Informatica<br>Doutor em Engenharia Química
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de, Vries Tialda. "Let's head to the food store : An analysis of accessibility to food stores in rural and urban Västerbotten." Thesis, Umeå universitet, Institutionen för geografi, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-187661.
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Food is of great importance to daily life. Food stores and supermarkets are the key places to get food for both the urban and rural populations. This study presents the accessibility of urban and rural food stores in Västerbotten County. A GIS-based analysis created service areas around the food stores using the road network in Västerbotten. These service areas were created for two different forms of transport, driving and public transport. The public transport service areas made us of the GTFS tool within ArcGIS pro. The population within and not within these service areas were counted as having access and not having access to the food stores in the time cost model. Compared to the urban population, the rural population has less access to the food stores in both the driving and public transport service areas. For both the urban and rural populations, accessibility with the car is higher than when taking public transport options.
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Bjärnhall, Gunilla. "Analysis of Angiographies in Human Healthy Eyes and in Open-angle Glaucoma : Retinal Mean Transit Time and Optic Nerve Head Circulation." Doctoral thesis, Uppsala universitet, Institutionen för neurovetenskap, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-9398.
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Purpose of the studies was to develop a more robust technique to determine retinal mean transit time in healthy and in glaucoma eyes and to evaluate the circulation of the optic nerve head in glaucoma patients. The retinal mean transit time impulse-response method was evaluated in human healthy eyes and normal values and reproducibility were tested. Fluorescein and indocyanine green angiographies were recorded and the pictures were analyzed to obtain retinal mean transit time and to evaluate the proportion of low-fluorescent pixels of the optic nerve head in the glaucoma patients. Visual field defects were correlated to loss of neuroretinal rim area. A disturbed circulation was observed in the glaucoma patients, whether primary or secondary to loss of nerve fibre tissue can not be determined from these studies.
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Boehm, Christian Reiner. "Gene expression control for synthetic patterning of bacterial populations and plants." Thesis, University of Cambridge, 2017. https://www.repository.cam.ac.uk/handle/1810/267842.
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The development of shape in multicellular organisms has intrigued human minds for millenia. Empowered by modern genetic techniques, molecular biologists are now striving to not only dissect developmental processes, but to exploit their modularity for the design of custom living systems used in bioproduction, remediation, and regenerative medicine. Currently, our capacity to harness this potential is fundamentally limited by a lack of spatiotemporal control over gene expression in multicellular systems. While several synthetic genetic circuits for control of multicellular patterning have been reported, hierarchical induction of gene expression domains has received little attention from synthetic biologists, despite its fundamental role in biological self-organization. In this thesis, I introduce the first synthetic genetic system implementing population-based AND logic for programmed hierarchical patterning of bacterial populations of Escherichia coli, and address fundamental prerequisites for implementation of an analogous genetic circuit into the emergent multicellular plant model Marchantia polymorpha. In both model systems, I explore the use of bacteriophage T7 RNA polymerase as a gene expression engine to control synthetic patterning across populations of cells. In E. coli, I developed a ratiometric assay of bacteriophage T7 RNA polymerase activity, which I used to systematically characterize different intact and split enzyme variants. I utilized the best-performing variant to build a three-color patterning system responsive to two different homoserine lactones. I validated the AND gate-like behavior of this system both in cell suspension and in surface culture. Then, I used the synthetic circuit in a membrane-based spatial assay to demonstrate programmed hierarchical patterning of gene expression across bacterial populations. To prepare the adaption of bacteriophage T7 RNA polymerase-driven synthetic patterning from the prokaryote E. coli to the eukaryote M. polymorpha, I developed a toolbox of genetic elements for spatial gene expression control in the liverwort: I analyzed codon usage across the transcriptome of M. polymorpha, and used insights gained to design codon-optimized fluorescent reporters successfully expressed from its nuclear and chloroplast genomes. For targeting of bacteriophage T7 RNA polymerase to these cellular compartments, I functionally validated nuclear localization signals and chloroplast transit peptides. For spatiotemporal control of bacteriophage T7 RNA polymerase in M. polymorpha, I characterized spatially restricted and inducible promoters. For facilitated posttranscriptional processing of target transcripts, I functionally validated viral enhancer sequences in M. polymorpha. Taking advantage of this genetic toolbox, I introduced inducible nuclear-targeted bacteriophage T7 RNA polymerase into M. polymorpha. I showed implementation of the bacteriophage T7 RNA polymerase/PT7 expression system accompanied by hypermethylation of its target nuclear transgene. My observations suggest operation of efficient epigenetic gene silencing in M. polymorpha, and guide future efforts in chassis engineering of this multicellular plant model. Furthermore, my results encourage utilization of spatiotemporally controlled bacteriophage T7 RNA polymerase as a targeted silencing system for functional genomic studies and morphogenetic engineering in the liverwort. Taken together, the work presented enhances our capacity for spatiotemporal gene expression control in bacterial populations and plants, facilitating future efforts in synthetic morphogenesis for applications in synthetic biology and metabolic engineering.
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Yu, Yueh-chang, and 余岳璋. "Network Analysis of Heat Pipe Transient Heat-Transfer." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/15985636624229966700.
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碩士<br>義守大學<br>機械與自動化工程學系碩士班<br>96<br>With the development of miniaturized and high power electronic devices in recent years, electronic heat dissipating apparatus have become important. The heat pipe is a simple and power-free device that is characterized by a high heat transfer capacity and a short thermal response time. The heat pipe is important to notebook and miniaturizion of the information products heat dissipation problem in the future. In this study, a numerical model is presented to simulate transient heat-pipe heating-up and cooling-down processes. The analysis included the heat conduction in the wall and liquid-wick region as well as in the vapor space. The heat pipe is treated as a single system, with a conjugate solution technique in which the heat transfer through the wall, wick, and vapor phase are solved simultaneously. The energy conservation equations are transformed into a linear system of first-order ordinary different equations which can be solved by Gear’s method. Validated by comparisons with previous experimental and more sophisticated numerical models, the present model can be used as a preliminary design tool to simplify heat pipe design scheme.
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Regulagadda, Prashant. "Transient heat transfer analysis of heat exchangers in a Marnoch Heat Engine." Thesis, 2009. http://hdl.handle.net/10155/72.
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The Marnoch heat engine (MHE) is a new type of power generation device that is under research and development at the University of Ontario Institute of Technology. In this thesis, the transient heat transfer behaviour of the source heat exchanger of the Marnoch heat engine is studied, and its operation for laminar and turbulent flows is modelled. The temperature variations of the working fluid, the heating fluid and the wall, are calculated. The temperature distribution of the fluids and the wall over the length of the heat exchanger is also calculated. It is found that the temperature of the working fluid rises sharply to a peak and then gradually decreases. The wall temperature decreases exponentially, and the temperature of the heating fluid falls sharply, and then gradually decreases. A base model for the step change in the mass flow of the working fluid is developed and compared against past works for the purpose of validation.<br>UOIT
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Chan, Ying-han, and 詹英瀚. "Transient analysis of a cylindrical heat equation with a heat source." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/68623568062278517915.
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碩士<br>桃園創新技術學院<br>材料應用科技研究所<br>101<br>This paper mainly discusses the cylindrical heat equation with a heat source. Transient heat transfer was analyzed. By different Biot numbers the temperature distribution and transient heat transfer was studied.Partial differential equations expressed the transient temperature formula. By using the separation of variables, P.D.E converted into multiple single variables of ordinary differential equations. Then the O.D.E was solved by Fourier's law, Bessel functions, and integral factor. The analytical solution of Partial differential equations was reached, and The diagram showed the temperature distribution, heat flux along with distance and time.The results Present that the greater Biot number would induced the greater convection effects, and results a better heat dissipation.
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Li, Yung-Yuan, and 李永元. "Inverse Analysis of Transient Heat Source from Arc Erosion." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/28824641948583198421.
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碩士<br>國立中山大學<br>機械工程學系研究所<br>89<br>An inverse method is developed to analyze the transient heat source from arc erosion. The temperature at the contour of arc erosion is assumed as melting point. And the temperature in grid points at the last time is calculated by interpolation, which include measurement errors. Then, the unknown parameters of transient heat source can be solved by linear least-squares error method. These parameters are plasma radius at the anode surface grows with time, arc power, and plasma flushing efficiency on the anode. Because the temperature in measuring points includes measurement errors, the exact solution can be found when fewer unknowns are considered. The inverse method is sensitivity to measurement errors.
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Yang, Cheng Yu, and 楊政諭. "Analysis of Transient Response of Horizontal Cylindrical Heat ipe." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/32283214915711650424.
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SU, RONG-JIA, and 蘇榮家. "Analysis of the transient heat transter of two dimensional fins." Thesis, 1988. http://ndltd.ncl.edu.tw/handle/03855398532185924757.
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Chen, Yi-Hung, and 陳翊航. "The transient heat transfer analysis of percutaneous laser disc decompression." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/74704591846881926683.
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碩士<br>遠東科技大學<br>機械研究所<br>97<br>This study is to discuss the variation of different surgical conditions while PLDD is processing. The multiphysics analysis algorithm is used to understand the temperature and stress distribution of the whole domain and heat transfer phenomena under the different kinds of laser heating rate and patients. In this study, the effect of thermal conductivity related about the patient’s age will be illustrated. In addition, the temperature profile is predicted as the heat transfer phenomena can be handled on the surgical process. In future, we expect that this result can be used to handle the PLDD in the pre-surgical simulation.
This study is to obtain the thermal structure conjugated phenomena under the different surgical conditions while percutaneous laser disc decompression (PLDD) is processing. PLDD is a minimal invasive surgery which through the laser vaporizes the herniation of disc. By this technology, we can remove or release the compression on nerve root and reduce the volume of herniation to decompress. The 3D thermal structure conjugated model of COMSOL is used in this study. We discuss the parameters of the PLDD, such as laser power, laser moving speed and the content of water. The temperature profile of the intervertebral disk is obtained and reveals the relations among these parameters. These results are expected to be a pre-surgical analysis to benefit the PLDD processing.
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Hubbell, James Edward. "The analysis of transient heat conduction for ground heat exchangers using analytical and numerical methods." 1996. https://scholarworks.umass.edu/dissertations/AAI9638973.
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The two dimensional transient heat conduction surrounding ground heat exchangers in clay soils is investigated analytically and numerically using finite element methods. The study is directed towards the application of the ground heat exchangers in a central solar heating plant with seasonal storage (CSHPSS). The analytical solution to the transient heat conduction for both the borehole and the U-tube configurations are presented. The analytical solution to the transient heat conduction in the hollow cylinder geometry is derived in cylindrical coordinates using the separation of variables method. The results of this solution are used to validate the finite element models of the borehole geometry. The procedures for developing the finite element models are included. The finite element modeling was extended to the geometry of the U-tube ground heat exchanger. Results are presented for the transient heat exchange performance of the U-tube for variations in geometry, material properties, and boundary conditions. The solution of the heat conduction in a circular region with two internal point sources of energy generation is derived in cylindrical coordinates to approximate the heat transfer for the U-tube geometry. The temperature profiles of the analytical solution compared closely to the finite element model of the U-tube geometry despite the inherent differences of the two models. The finite element models were further used to demonstrate that the geometry of the borehole can be used to approximate the transient thermal performance of a U-tube ground heat exchanger. The heat exchange performance of the two configurations compared closely over time beyond a short initial transient period.
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Yu-ChengChiang and 江諭承. "2D Transient Anisotropic Heat Conduction Analysis by the Boundary Element Method." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/09714810504535636801.
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碩士<br>國立成功大學<br>航空太空工程學系<br>103<br>Despite the extensive study of the transient thermal conduction analysis for isotropic media by the boundary element method, its relevant researches in anisotropic transient heat conduction still remain extremely scarce indeed. In the thesis, the author applies the time-stepping scheme [2] for the transient effect and also the domain mapping scheme proposed by Shiah and Tan [4] to treat the anisotropy. For the transient analysis, the fundamental solution of the Helmholz equation is applied. For the domain mapping scheme, coordinates of the boundary are transformed to a new coordinate system by the anisotropic heat conductivities, where the transformed domain is considered to have equivalent isotropic heat conduction. Thus, the anisotropic thermal field in the original domain can be directly obtained via solving the corresponding isotropic one in the distorted domain. For the present boundary element analysis, the both schemes are jointly applied to solve for the problem of transient heat conduction in anisotropic media. In the end, a few benchmark examples are studied by the proposed schemes and the results are compared with finite element analysis.
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HUANG, SHAO-CHIH, and 黃紹志. "Transient Heat Transfer Analysis of a Heated Cylinder in Mixed Convection." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/05006577772410158819.
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碩士<br>中華大學<br>機械工程學系<br>105<br>Transient heat transfer analysis of a heated cylinder was solved by a differential scheme based on the compressible Navier-Stokes equations. The local Nusselt number distribution for the current work compared very well with those reported in the literature for forced convection flows. The effect of superimposed thermal buoyancy was studied for various Reynolds numbers, Richardson numbers and orientation of thermal buoyancy. For aiding configuration of thermal buoyancy, the unsteady periodic flows become steady separated flows behind the heated cylinder. Further increase the buoyant force can suppress flow separation. The distributions of pressure coefficient, skin friction coefficient and Nusselt number and contours of isotherm, vorticity and streamline were used to substantiate the above findings.
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康振雄. "Transient heat transfer analysis of squeeze casting for A356 aluminum alloy." Thesis, 1988. http://ndltd.ncl.edu.tw/handle/15211412080059401898.
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HAO, CHANG JHIH, and 張智豪. "Measurement and Analysis of Transient Supercooling Heat Transfer Performance for Thermoelectric Coolers." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/3fdp4f.
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碩士<br>國立臺北科技大學<br>冷凍空調工程系所<br>105<br>Along with the appearance of semiconductor thermoelectric material, thermoelectric cooler (TEC) has been widely applied in many engineering applications, such as health care, space mission, military, industry and so on. Compared with the traditional refrigeration technology, thermoelectric cooler has the advantages of small volume, fast response, no moving parts and environmental friendly. There is no breakthrough of material, so that the rate of the thermoelectric cooling is low. However, due to the development of the semiconductor thermoelectric material, it raises the function of thermoelectric cooler. The arrangement of the thermoelectric coolers in series or in parallel can increase the higher power output. It is helpful to develop a system with longer service life, lower repairing cost, and faster cooling speed. To understand how to enhance the refrigeration capacity of thermoelectric cooler, the combined experimental and numerical methods are used to study the transient supercooling heat transfer characteristic of the thermoelectric coolers of single-stage or two-stage structure subjected to current pulse with various pulse amplitudes, widths, and shapes. Choosing the thermoelectric cooler (TEC) with the rated current at 2A and keeping the hot end of a TEC module being cooled by a heat sink. The cold end of a TEC is assumed to be thermally insulated. Next, to set up the numerical analysis, the predicted results of the single-stage TEC are obtained firstly to find out the optimal current parameters. And then, applying the same current parameters to the two-stage TECs and comparing theupercooling performance between single–and two-stage TECs. Finally, the predicted results are compared with the measured data The main findings of this work are as follows. (1) As compared with a single-stage counterpart, when a step current pulse is supplied to a two-stage TEC, a larger cold-end temperature drop, a weaker temperature overshoot, and a longer holding time of supercooling state are observed, indicating that the combination of cascade TEC design and transient supercooling effect do indeed increase the maximum temperature drop across TECs. The main mechanism for the improved supercooling lies in that the enhanced Peltier cooling on the hot stage makes more Joule heat generated within the cold stage transfer to the hot end of the cold stage. (2) The better supercooling characteristics can be obtained by properly choosing the pulse amplitude, width, and shape. By means of larger amplitudes and/or lower power exponents of time, a larger cold-end temperature drop can be achieved. However, when the transient supercooling is required for a longer time, then larger pulse widths and/or high exponent powers are preferred.
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Chen, Chih-Chung, and 陳志忠. "The Transient Heat Transfer Analysis and Aimulation of Percutaneous Laser Disc Decompression." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/31838897220978036489.
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博士<br>國立臺南大學<br>機電系統工程研究所<br>103<br>The purpose of this study is to discuss the temperature and stress distribution problem of the interverbral disc while the surgical operation of PLDD is processing. This study also further discuss the water content of disc changes with age to cause variation of thermal conductivity thermal expansion coefficient specific heat and related parameters, and the effect of thermal conductivity related about the patient’s age will be illustrated. The 3D thermal structure conjugated model of the multiphysics analysis algorithm is used to understand the temperature and stress distribution of the whole domain and heat transfer phenomena under the different kinds of laser heating rate and patients. The temperature profile of the intervertebral disk is obtained and reveals the relations among the parameters. The temperature profile is predicted as the heat transfer phenomena can be handled on the surgical process. In the future, we expect that this result can be used to handle the PLDD in the pre-surgical simulation.
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HUANG, WEI-BANG, and 黃維邦. "Analysis on the transient heat transfer of layerhed media heated by periodic moving heat source with hyperbolic heat conduction equation." Thesis, 1989. http://ndltd.ncl.edu.tw/handle/95645761027905713070.
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Ni, Chien-Wu, and 倪建武. "Transient analysis of two-dimensional rectangular plate and cylinder fin with periodic heat." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/76452350120381979177.
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碩士<br>逢甲大學<br>應用數學系<br>88<br>Discussing the periodic heat of the transient state suddenly transfer to the root of two-dimensional rectangular plate fin and cylinder fin. The upside、underside and tip of the rectangular plate fin all have different heat convection effect. According to different Biot Number, there have different temperature distribution and heat transfer state.
(1)The analysis of the heat transfer of the two dimensional rectangular via using eigenfunction expansion method to fit、top and bottom boundary condition and to compact variable. And to utilize coordinate transform making the homogeneous of right and left boundary condition of the two dimensional rectangular plate. Similarly, to utilize eigenfunction expansion method to satisfy the right and left boundary condition of the two dimensional rectangular plate and to compact variable. The resolute answer of the two dimensional rectangular plate would be achieved via fundamental the differential equation method of the single variable.
(2)When we research the analysis of the heat transfer of the two-dimensional cylinder fin, as result of the symmetry of the cylinder fin, we only consider one chamfer. The research method primarily uses zero Bessel function to transfer the equation of the cylinder fin to dimensionless heat transfer equation. satisfy that the center temperature is finite , so we could resolve by using function to be eigenfunction expansion. It would be satisfied the right and left boundary condition of the two-dimensional cylinder fin via the eigenfunction function expansion. The analytical answer of the two dimensional cylinder would be solved by using a general method of single variable differential equation.
(3)To solve the analysis and numerical solution of rectangular plate fin and cylinder fin using the method of numerical analysis. Compare the equivalent of analysis and numerical solution and non-dimensional heat transfer rate.
The center temperature distributions of the rectangular plate have apparent differentia with different the Biot Number and thickness. The center temperature will gradually descend with raising the Biot Number. When the Biot Number of the end arise, then the temperature distribution of the end will show constringency status. The center temperature distributions of the cylinder fin have apparent differentia with different the Biot Number and thickness. When the Biot Number of the end arise, then the temperature distribution of the end will show constringency status. When the Biot Number is very small, the slope of he center temperature distribution of the different thick fin is still identical. The temporal heat transfer rate will be difficult to reach steady state with arising thickness.
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Miao, Lin Chun, and 林純妙. "Transient analysis of two-dimensional rectangular plate and cylinder fin with heat flux." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/72762366778049522880.
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碩士<br>逢甲大學<br>應用數學系<br>88<br>Discussing the heat flux of the transient state suddenly transfer to the root of two-dimensional rectangular plate fin and cylinder fin. The upside、underside and tip of the rectangular plate fin all have different heat convection effect. According to different Biot Number, there have different temperature distribution and heat transfer state. (1)The analysis of the heat transfer of the two dimensional rectangular via using eigenfunction expansion method to fit、top and bottom boundary condition and to compact variable. And to utilize coordinate transform making the homogeneous of right and left boundary condition of the two dimensional rectangular plate. Similarly, to utilize eigenfunction expansion method to satisfy the right and left boundary condition of two dimensional rectangular plate and to compact variable. The resolute answer of the two dimensional rectangular plate would be achieved via fundamental the differential equation method of the single variable. (2)When we research the analysis of the heat transfer of the two dimensional cylinder fin, as result of the symmetry of the cylinder fin, we only consider one chamfer. The research method primarily uses zero Bessel function to transfer the equation of the cylinder fin to dimensionless heat transfer equation. satisfy that the center temperature is finite , so we could resolve by using function to be eigenfunction expansion. It would be satisfied the right and left boundary condition of the two dimensional cylinder fin via the eigenfunction function expansion. The analytical answer of the two dimensional cylinder would be solved by using a general method of single variable differential equation. To solve the analysis and numerical solution using the method of numerical analysis and the program of Matlab. Compare the equivalent of analysis and numerical solution and non-dimensional heat transfer rate.
The center temperature distributions of the rectangular plate have apparent differentia with different the Biot Number and thickness. The center temperature will gradually descend with raising the Biot Number. When the Biot Number of the end arise , then the temperature distribution of the end will show constringency status. When the Biot Number is very small , the slope of he center temperature distribution of the different thick fin is still identical. The diversity of temperature would be more with more small thickness. Heat quantity would be faster accumulated and lost. The temporal heat transfer rate will be difficult to reach steady state with arising thickness.
The center temperature distributions of the cylinder fin have apparent differentia with different the Biot Number and thickness. The center temperature will gradually descend with raising the Biot Number. The heat quantity would be more accumulated with more large thickness. When the Biot Number of the end arise , then the temperature distribution of the end will show constringency status. When the Biot Number is very small , the slope of he center temperature distribution of the different thick fin is still identical. The temporal heat transfer rate will be difficult to reach steady state with arising thickness.
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Wheeler, Adam (Adam Richard). "Modeling and analysis of a heat transport transient test facility for space nuclear systems." Thesis, 2013. http://hdl.handle.net/1957/38011.
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The purpose of this thesis is to design a robust test facility for a small space nuclear power system and model its physical behavior under different scenarios. The test facility will be used to simulate a 1-10kWe nuclear reactor, its electrical generation, and heat removal capabilities. This simulator will be used to explore, test and understand the steady-state and transient operation capabilities of small space nuclear power systems. Currently, the system is planned to operate on a variable, electrical heat source directly connected to heat pipes. The heat pipes are to be stainless steel with a water working fluid. These heat pipes will then be connected to a power conversion simulator or actual power conversion technologies. The power conversion simulator is connected to a radiator using a water based heat pipe network using fins and connecting plates in a cylindrical geometry.
Modeling of the facility was performed using two different analysis programs, STELLA and SolidWorks. STELLA was used as a lumped sum heat transport code, and SolidWorks was used as a more accurate system to verify the validity of STELLA's results. Both programs were used to analyze startup, heat pipe failures, and loss of power
conversion with the end goal of finding safe operational transient scenarios for the transient test facility.<br>Graduation date: 2013
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Ye, Tian-Li, and 葉恬利. "Steady & Transient Response Analysis Of Overclocking Power Of Slim Heat Pipe Thermal Modules." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/r9k4q3.
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碩士<br>國立臺北科技大學<br>製造科技研究所<br>106<br>ABSTRACT
Title: Steady & Transient Response Analysis Of Overclocking Power Of Slim Heat
Pipe Thermal Modules
Pages: 100
School: National Taipei University of Technology
Department: Graduate Institute of Manufacturing Technology
Time: August, 2018
Degree: Master
Researcher: Tian-Li Ye
Advisor: Chin-Shu Wang Ph.D.
Keywords: Heat pipe, Simulation, Transient response Analysis
With the development of science and technology industry, CPU wafer efficiency of 3C products is improved gradually towards the trend of thinner and higher. The heat produced by the wafer is also higher than the past, hence heat dissipation of electronic products becomes a new problem, which desire to be solved. In mid-end and high-end electronic products, heat pipe is the most important part in the thermal module. The performance of heat pipe determines the efficiency of the thermal module primarily.
Recently, CPU chips of portable electronic products will make the sudden impulse by thermal shock. This impact will decline the performance of the system dramatically. In order to reduce the risk of shutting down in the system, the transient response which is the mechanism that will be upgraded with the transient high temperature generated by the wafer must be studied.
We expect to find out the theoretical curve in this research by the results of the simulation analysis and experiment. From the results of this research, it is highly precise that error of thermal resistance of module in analysis of steady state simulated by Flotherm is barely 6.2%. However, in analysis of transient state, it is observed that the difference in judgment on failure time between simulation and experiment in various power of overclocking of module is 44~75 seconds. The higher overclocking power is, the less difference in time will be. In order to minimize the time gap, thermal conductivity of heat pipe is raised up twice as much as general setting in simulation of transient state. As a result, it is able to be in 60 seconds. In addition, the difference in temperature from evaporation to condensation has been much less after adjusting thermal conductivity.