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Gowreesunker, Baboo Lesh Singh. "Phase change thermal enery storage for the thermal control of large thermally lightweight indoor spaces." Thesis, Brunel University, 2013. http://bura.brunel.ac.uk/handle/2438/7649.
Повний текст джерелаАнотація:
Energy storage using Phase Change Materials (PCMs) offers the advantage of higher heat capacity at specific temperature ranges, compared to single phase storage. Incorporating PCMs in lightweight buildings can therefore improve the thermal mass, and reduce indoor temperature fluctuations and energy demand. Large atrium buildings, such as Airport terminal spaces, are typically thermally lightweight structures, with large open indoor spaces, large glazed envelopes, high ceilings and non-uniform internal heat gains. The Heating, Ventilation and Air-Conditioning (HVAC) systems constitute a major portion of the overall energy demand of such buildings. This study presented a case study of the energy saving potential of three different PCM systems (PCM floor tiles, PCM glazed envelope and a retrofitted PCM-HX system) in an airport terminal space. A quasi-dynamic coupled TRNSYS®-FLUENT® simulation approach was used to evaluate the energy performance of each PCM system in the space. FLUENT® simulated the indoor air-flow and PCM, whilst TRNSYS® simulated the HVAC system. Two novel PCM models were developed in FLUENT® as part of this study. The first model improved the phase change conduction model by accounting for hysteresis and non-linear enthalpy-temperature relationships, and was developed using data from Differential Scanning Calorimetry tests. This model was validated with data obtained in a custom-built test cell with different ambient and internal conditions. The second model analysed the impact of radiation on the phase change behaviour. It was developed using data from spectrophotometry tests, and was validated with data from a custom-built PCM-glazed unit. These developed phase change models were found to improve the prediction errors with respect to conventional models, and together with the enthalpy-porosity model, they were used to simulate the performance of the PCM systems in the airport terminal for different operating conditions. This study generally portrayed the benefits and flexibility of using the coupled simulation approach in evaluating the building performance with PCMs, and showed that employing PCMs in large, open and thermally lightweight spaces can be beneficial, depending on the configuration and mode of operation of the PCM system. The simulation results showed that the relative energy performance of the PCM systems relies mainly on the type and control of the system, the night recharge strategy, the latent heat capacity of the system, and the internal heat gain schedules. Semi-active systems provide more control flexibility and better energy performance than passive systems, and for the case of the airport terminal, the annual energy demands can be reduced when night ventilation of the PCM systems is not employed. The semi-active PCM-HX-8mm configuration without night ventilation, produced the highest annual energy and CO2 emissions savings of 38% and 23%, respectively, relative to a displacement conditioning (DC) system without PCM systems.
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Mahrukh, Mahrukh. "Computational modelling of thermal spraying processes." Thesis, Cranfield University, 2016. http://dspace.lib.cranfield.ac.uk/handle/1826/10039.
Повний текст джерелаАнотація:
The main aim of this project is to model the effects of varied injection parameters on the gas dynamics and droplet dynamics of the HVSFS and SP- HVOFS processes for improving the droplet breakup and evaporation to enhance the nanoparticles heating and deposition efficiency. Thermal spraying processes are widely used to generate thermal-, corrosion-, and wear-resistant layers over the machine parts, to increase the durability of the equipment under severe environmental conditions. The liquid feedstock is used to achieve nanostructured coatings. It is used either in the form of a suspension or a solution precursor. The suspension is a mixture of solid nanoparticles suspended in a liquid medium consisting, for instance, of water, ethanol, or isopropanol. This dispersion mechanism in a liquid carrier provides adequate flowability to the nanoparticles, which cannot be handled by conventional gas- based feeding systems, whereas the solution precursor is mixed at the molecular level; hence, more uniform phase composition and properties are expected in the sprayed coatings as compared to the suspension and conventional powder spraying. Firstly, experiments are conducted to analyse the effects of different precursor concentrations, solvent types and injection nozzles on the size and morphology of synthesized nanoparticles. The results indicate that the particle size increased with increasing precursor concentration due to the variations in the physical properties of the mixture solution. The higher precursor concentrations had an adverse effect on the droplet atomization and evaporation process that led to bigger size particle formation. The use of aqueous solvent has some limits and with higher precursor concentration the surface tension increases that resulted in the reduction of droplets’ disintegration, and thus bigger size precursor droplets generate larger nanoparticles. A mixture of aqueous-organic solvents and pure organic precursors are preferred to improve the process efficiency of the nanoparticles size and morphology. Furthermore, the nanoparticles size can be controlled by using liquid feedstock atomization before injecting into the HVOF torch. A new effervescent injection nozzle is designed and compared to different types of existing injection nozzles, to see the variations in the droplet disintegration, and its effects on the performance of the HVOF torch processes. It is detected that the atomization would result in smaller size particles with homogeneous morphology. In a numerical study, different droplet injection types are analysed to see their effects on the gas and droplet dynamics inside the HVOF torch. The group-type injection (GTI) and effervescent-type atomization (ETI) are used effectively to overcome the heat losses and delays in the droplet evaporation. These approaches reduce the thermal and kinetic energy losses in the suspension-fed-HVOF torch, thereby improving the coating formation. The effects of using multicomponent water-ethanol mixture injection in the HVOF torch are also modelled, and its impact on the droplet breakup and evaporation are studied. The organic solvents have a low heat of vaporization and surface tension, and can effectively be used in the HVOF spraying process over the water-based solvents. Furthermore, nanoparticles are suspended in the liquid feedstock and injected into the HVOF torch. The effect of increasing nanoparticles’ concentration in the feedstock and its consequence on the gas dynamics, droplet breakup and evaporation are analysed. The augmentation in the nanoparticles loading in the suspension droplets can decrease the droplet breakup and evaporation rate because the required heat of vaporization increases significantly. Moreover, the size of injection droplet affects the droplet fragmentation process; bigger sized droplets observed a delay in their evaporation that resulted in coating porosity. The results suggest that smaller droplet sizes are preferred in coating applications involving a higher concentration of nanoparticles with high melting point. Further, the gas flow rates (GFRs) are regulated to control the droplet dispersion, atomization and evaporation inside the solution precursor fed-HVOF torch. The size of the droplet diameter is decreased by an increment in the GFR, as higher combustion rates increase the combustion flame enthalpy and kinetic energy. Moreover, the increase in the oxygen/fuel flow rates dilutes the injected precursor. It reduces ZrO2 concentration in the process and decreases the rate of particle collision; as a result, non-agglomerated nanoparticles can be obtained.
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Jang, Tai Seung. "Thermophysiologic issues in computational human thermal models /." free to MU campus, to others for purchase, 2003. http://wwwlib.umi.com/cr/mo/fullcit?p1418034.
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Bhatnagar, Himanshu. "Computational Modeling of Failure in Thermal Barrier Coatings under Cyclic Thermal Loads." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1230741103.
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Seijas, Bellido Juan Antonio. "Computational studies of thermal transport in functional oxides." Doctoral thesis, Universitat Autònoma de Barcelona, 2019. http://hdl.handle.net/10803/669787.
Повний текст джерелаАнотація:
Esta Tesis recoge los trabajos computacionales que hemos realizado en el campo de la física de la materia condensada, enfocados en las propiedades de transporte térmico del Titanato de Plomo (PbTiO3) y el Óxido de Zinc (ZnO), ambos materiales representativos de muchos otros óxidos funcionales aislantes. El primero ha sido modelado usando un potencial de segundos principios, esto es, un potencial parametrizado mediante cálculos de primeros principios, que captura algunos efectos cuánticos que pueden ser relevantes en el material. Hemos modelado el segundo usando el potencial de Buckingham, una expresión analítica simple que parece describir el comportamiento del ZnO de forma bastante aproximada a los experimentos.This Thesis collects the computational works we have done in the field of condensed matter physics, focused on the thermal transport properties of the Lead Titanate (PbTiO3) and the Zinc Oxide (ZnO), both representative materials of many other insulating functional oxides. The first has been modeled using a second-principles potential, that is, a potential parameterized from first-principles calculations, which captures some quantum effects that can be relevant in the material. We have modeled the second one using the Buckingham's potential, a simple analytical expression that seems to describe the behavior of ZnO in a fairly approximate agreement with experiments.
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Barakat, Magdi H. "Computation of indoor airflow for thermal comfort in residential buildings." Diss., Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/23308.
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Negrão, Cezar O. R. "Conflation of computational fluid dynamics and building thermal simulation." Thesis, University of Strathclyde, 1995. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=21238.
Повний текст джерелаАнотація:
The present work is a contribution towards the integration of building simulation tools in order to better represent the complexity of the real world. It attempts to overcome certain shortfalls of contemporary simulation applications with respect to indoor air flows. As a result, the evaluation of building energy consumption and indoor air quality is expected to be improved. Advanced fluid flow models (as employed within Building Thermal Simulation - BTS - and Computational Fluid Dynamics - CFD) with different degrees of detail were investigated and their modelling deficiencies identified. The CFD technique which defines the fluid flow on a micro scale was integrated into BTS in which fluid flow is described in a larger scale. The resulting combined approach strengthens the modelling potential of each methodology by overcoming their specific deficiencies. BTS's inability to predict air flow property gradients within a single space was surmounted and the difficult of estimating CFD boundary conditions are now supplied by BTS. The conflation approach is expected to be employed where gradients of indoor air flow properties can be considered crucial to the evaluation of thermal comfort and energy consumption. The BTS environment, ESP-r, was elected to perform the current work and a new CFD program, dfs, was specifically developed for the analysis of three-dimensional, turbulent, transient air flow. Finally, the two approaches were integrated. The integration work focuses on the CFD boundary conditions where the interactions of BTS and CFD take place; these occur at the inside zone surfaces and at the zone openings. Three conflation approaches were devised addressing different degrees of complexity and sophistication. The first one, involving the two types of zone boundaries, corresponds to a simple approach where the BTS and CFD systems exchange information without any direct interaction. The second approach consists of three other schemes to handle the thermal coupling at the internal zone surfaces. The third approach comprises coupling between the nodal network approach as employed by the BTS environment, and the continuity and momentum equations in the CFD technique. A validation methodology consisting of analytical validation, intermodel comparison and empirical validation is described and applied. The technique is shown to be adequate for modelling indoor air flows when compared to existing models. Three situations, covering the different types of air flows encountered within buildings are discussed to demonstrate the combined method's applicability when compared with the nodal network approach. Finally, general conclusions are presented and some possible future work is identified showing that the developed methodology is very promising.
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Johansson, Emma. "The thermal comfort of the cockpit: A pilot's experience." Thesis, KTH, Optimeringslära och systemteori, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-203773.
Повний текст джерелаАнотація:
Saab takes great measures to ensure that the cockpit is a great working environment for the pilot. This paper aims to expand the knowledge of thermal comfort by assembling Saab’s atmosphere-, cabin and pilot-models. In order to ensure the viability of the assembled model, a qualitative study was performed with test pilots. The interviews were reduced to a few flight cases, which were tested in the assembled model to verify that the thermal discomforts that the pilots experience could be accurately predicted. Furthermore, a prediction of comfort, according to European standards, was implemented. From the interviews situations when the pilot feel discomfort could be identified, two flight cases situations and one ground case. The model simulate how the thermal environment affect the pilot, hence only the two flight cases could be analyzed. The result from the model shows the temperature in those body parts that the pilots have expressed are uncomfortable. Predicted Mean Vote, PMV, predicts comfort on a 6-degree scale, given environment parameters such as pressure and temperature. The Predicted Percentage Dissatisfied, PPD, describes the number of people, in percent, who are uncomfortable at a given PMV. These measures of comfort were used to compute the comfort in the different parts of the body. The model simulation agrees with the pilot’s experiences in some of the body parts, but not all of them. By taking the humidity into account the simulation result may be more accurate. The humidity increases the PPD value in case 2 when the humidity increases. Finally, in order to adopt the comfort analysis presented in this paper, the model had to be revised, and updated with increased detail.Saab gör stora satsningar för att säkerställa att cockpiten är en god arbetsplats för piloten. Den här rapporten syftar till att öka kunskapen om termisk komfort genom att kombinera Saabs atmosfärs-, kabin-, och pilotmodeller. För att kunna verifiera att den kombinerade modellen beskriver verkligheten genomfördes en kvalitativ studie med testpiloter. Intervjuerna reducerades till ett par flyg-scenarier, som sedan testades i den kombinerade modellen. Detta för att kunna verifiera att de upplevda obekvämligheterna kunde förutspås. Den kombinerade modellen utökades med en prediktion av bekvämligheten enligt Europeisk standard. Ur intervjuerna kunde situationer identifieras då piloterna känner termiskt obehag. Av dessa situationer är två flygfall och ett markfall, där piloten befinner sig utanför cockpit. Modellen simulerar hur piloten påverkas av den termiska miljön i kabin, på grund av detta kunde inte markfallet analyseras. Modellsimuleringen resulterade i figurer som visar temperaturen i kroppsdelar som piloterna har uttryck känns obehagliga. Predicted Mean Vote, PMV, förutspår komfort på en 6-gradig skala givet omgivningsparametrar så som tryck och temperatur. Predicted Percentage Dissatisfied, PPD, beskriver hur stor andel, i procent, som upplever obehag vid ett givet PMV. Dessa mått på komfort användes för att beräkna komforten i de olika kroppsdelarna. Modellsimuleringen av pilotkomforten stämmer överens med det piloterna nämnde till viss del. I vissa kroppsdelar stämmer det inte överens. Då modellen inte tar hänsyn till fuktighet vid beräkning av kroppstemperaturer kan detta vara en anledning till varför den inte stämmer helt. Fuktigheten påverkar PMV och PPD beräkningarna och i fall 2 visar det sig att PPD ökar med en ökad fuktighet. Slutligen, behöver modellens ses över, och detaljgraden ökas, för att den här rapportens metoder skall vara användbara vid tillverkningen av flygplan.
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Eriksson, Christoffer. "Thermal design optimization by geometric parameterization of heat sources." Thesis, Uppsala universitet, Avdelningen för beräkningsvetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-328011.
Повний текст джерелаАнотація:
In this master thesis, a thermal design optimization has been performed. By solvingthe two dimensional steady state conduction convection equation using the finiteelement method in a unit square domain with a source term corresponding tocomponents heated by resistive heating, the objective functional was formulated as aminimization of the combination of a low temperature and small temperaturedifferences inside the domain. The design parameters are based on geometricproperties such as length, width, angle or position of the heat sources. The heatsources were parameterized by combining two smooth exponential functions thatexplicitly depended on the position and size of the heat source. The problem wasthen solved as a PDE constrained optimization problem using MATLAB's built infunction fmincon. Three different 1D test cases were implemented to investigate how the solverbehaved and that the parameterization was correctly implemented. Then the solverwas extended to 2D and three heat sources were placed in the domain. The optimalangle of rotation of the sources where the heat transfer was governed by conductionand convection were found. This was followed by an optimal placement of two heatsources in the domain. Three cases with a different convective field in each case wereinvestigated. In the last examples, four heat sources were placed inside the domain.One geometric property of each heat source was allowed to change. The fourdifferent parameters were length, width, angle of rotation and position. Themotivation was to test the functionality of the solver using different design parameterswith different sensitivities. The results showed that the derived objective functional fullfilled the purpose tominimize the temperature and temperature deviation from the mean temperature,respectively. In the 1D cases it was concluded that there exist several local minimawhen adding a heat source and a heat sink of unequal magnitude. Optimal angles ofthree heat sources in 2D showed a trivial solution and fast convergence. The optimalplacement of two heat sources converged rapidly when the forced convection was setto zero. When adding convection the number of iterations increased and the optimalplacement was highly dependent of the type of convective field and boundaryconditions. When constructing a non symmetric problem the optimization loopedover several random initial positions in order to find the best optimal solution. Forthe last examples, narrow bounds were used and the solver converged rapidly. Evenhere, the type of convective field highly affected the optimal solution.
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Xiang, Yetao. "Experimental and computational investigation of building integrated PV thermal air system combined with thermal storage." Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/42743/.
Повний текст джерелаАнотація:
Issues from global warming with increased CO2 emissions have been to a main concern over world. As an example in the UK, the energy demand in the domestic sector has risen by 17% in 2010 compared with that of 1970. Applying renewable energy is widely agreed to be the most effective and promising way to solve the problem where solar energy and photovoltaic technology have been greatly developing from the last century. Photovoltaic combines with Phase Change Material (PV/PCM) system is a hybrid solar system which uses phase change material to reduce the PV temperature and to store energy for other applications. This thesis aims to investigate the performance of a designed building integrated photovoltaic thermal system (BIPVT) with PCM as thermal storage for building applications. The research objectives are to increase the building integrated photovoltaic (BIPV) efficiency by incorporating PCM while utilising the stored heat in PCM for controlling indoor conditions and reduce the total building energy consumption. The research starts with solar energy convection technologies including solar thermal and solar photovoltaic. Then a combined technology named photovoltaic thermal system (PVT) was introduced and discussed. Research work on a different type of PVT using water and air as thermal energy medium was further reviewed and discussed. An analytical approach investigation was presented on a PVT system and the results were used to design the experiment work on PV/PCM configuration. Experiments have been carried out on a prototype PV/PCM air system using monocrystalline photovoltaic modules. Transient simulations of the system performance have also been performed using a commercial computational fluid dynamics (CFD) package based on the finite volume method. The results from simulation were validated by comparing with experimental results. The results indicated that PCM is effective in limiting temperature rise in PV device and the heat from PCM can enhance night ventilation and decrease the building energy consumption to achieve indoor thermal comfort for certain periods of time. An entire building energy simulation with designed PV/PCM air system was also carried out under real weather condition of Nottingham, UK and Shanghai, China. The result also shows a market potential of PV/PCM system and a payback time of 11 years in the UK condition if using electrical heater.
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Ababneh, Mohammed. "Novel Charging Station and Computational Modeling for High Thermal Conductivity Heat Pipe Thermal Ground Planes." University of Cincinnati / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1353950640.
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Lai, Ho-yin Albert. "Artificial intelligence based thermal comfort control with CFD modelling /." Hong Kong : University of Hong Kong, 1999. http://sunzi.lib.hku.hk/hkuto/record.jsp?B21929555.
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Wang, Zhongxiao. "Parallel computation for reservoir thermal simulation An overlapping domain decomposition approach /." Ann Arbor, Mich. : Proquest, 2005. http://proquest.umi.com/pqdweb?index=0&did=954046251&SrchMode=1&sid=1&Fmt=2&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1187901937&clientId=57025.
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Nguyen, Thanh Son. "Computational modelling of thermal-hydrological-mechanical processes in geological media." Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=29096.
Повний текст джерелаАнотація:
There are a number of engineering situations where fluid-saturated geological media can be subjected to thermal effects. These include the disposal of heat-emitting nuclear fuel wastes in saturated geological formations, extraction of energy resources such as oil and natural gas by steam injection and the recovery of geothermal energy by ground source heat exchangers. The objective of this thesis is to study the coupled thermal-hydrological-mechanical (T-H-M) response of fractured geological media by the computational implementation of mathematical models. From the generalization of Biot's classical theory of consolidation of a saturated porous elastic medium to include thermal effects, we first derived the equations governing coupled T-H-M processes in saturated geological media. In order to obtain numerical solutions for the governing equations, the finite element method was used. A finite element computer code, FRACON (FRActured media CONsolidation), was developed in order to simulate plane strain and axisymmetric problems. Eight-noded isoparametric elements were developed to represent the intact regions of the geological medium, while special joint elements were developed to simulate discrete joints. The intact regions of the geological medium was assumed to exhibit linear elasticbehaviour. The joints between intact regions were modelled by constitutive relationships which reproduced both linear elastic and nonlinear elasto-plastic responses. The elasto-plastic stress-strain relationship of the joint, was formulated by appeal to classical theories of interface plasticity. The elasto-plastic model for joint behaviour thus formulated is capable of reproducing many of the fundamental features of mechanical behaviour associated with naturally occuring joints, such as dilation under shear and strain softening due to surface asperity degradation. Furthermore, the thesis presents a physically-based hydraulic model of the joint that permits the inclusion of the effecThe development of the FRACON code followed an extensive procedure of code verification via analytical solutions and intercode comparison. A unique set of benchmark problems was proposed in order to perform code verification for coupled T-H-M.
The FRACON code was used to interpret certain laboratory and field experiments, including the following: (1) coupled T-H-M laboratory experiment on a block of cementitious material; (2) lab experiments on joint shear behaviour under constant normal stress and constant normal stiffness conditions; (3) coupled shear-flow laboratory experiment on a joint; (4) Field experiments of fluid injection in a horizontal fracture in a granitic rock mass.
Lastly, the FRACON code was used to simulate the coupled T-H-M response of a rock mass to radiogenic heat from nuclear fuel wastes buried in the rock formation. The coupled H-M response of this rock mass to a future glaciation scenario was also simulated. It was shown that the mechanical/hydraulic regimes of the rock mass could be significantly changed by the above two factors. The importance of the consideration of T-H-M processes in the overall scheme of safety assessment of sites targeted for nuclear fuel waste repositories is supported by the findings of this thesis.
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Duplain, Eric. "Computational optimization of the thermal performance of internally finned ducts." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=99407.
Повний текст джерелаАнотація:
A computational methodology for the optimization of the thermal performance of straight ducts with non-twisted, uninterrupted, longitudinal internal fins is formulated and demonstrated in the context of steady, laminar, fully-developed forced convection, accounting for conjugate heat conduction in the fins. The fluid flow and heat transfer problems are solved using control-volume-based finite difference and finite element methods. The optimization is done using a gradient method. The fins shapes are approximated using non-uniform rational B-splines (NURBS). The control points of the NURBS curves are among the design variables. In the demonstration problems, the objective was to maximize the total rate of heat transfer to the fluid per unit length of the duct, subject to the constraint of keeping the corresponding pumping power constant. Results pertaining to four sample ducts with fins made of stainless steel, aluminum, and copper, and air as the working fluid, are presented and discussed.
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Paul, Steven Timothy. "A Computational Framework for Fluid-Thermal Coupling of Particle Deposits." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/83544.
Повний текст джерелаАнотація:
This thesis presents a computational framework that models the coupled behavior between sand deposits and their surrounding fluid. Particle deposits that form in gas turbine engines and industrial burners, can change flow dynamics and heat transfer, leading to performance degradation and impacting durability. The proposed coupled framework allows insight into the coupled behavior of sand deposits at high temperatures with the flow, which has not been available previously. The coupling is done by using a CFD-DEM framework in which a physics based collision model is used to predict the post-collision state-of-the-sand-particle. The collision model is sensitive to temperature dependent material properties of sand. Particle deposition is determined by the particle's softening temperature and the calculated coefficient of restitution of the collision. The multiphase treatment facilitates conduction through the porous deposit and the coupling between the deposit and the fluid field.
The coupled framework was first used to model the behavior of softened sand particles in a laminar impinging jet flow field. The temperature of the jet and the impact surface were varied(T^* = 1000 – 1600 K), to observe particle behavior under different temperature conditions. The Reynolds number(Rejet = 20, 75, 100) and particle Stokes numbers (Stp = 0.53, 0.85, 2.66, 3.19) were also varied to observe any effects the particles' responsiveness had on deposition and the flow field. The coupled framework was found to increase or decrease capture efficiency, when compared to an uncoupled simulation, by as much as 10% depending on the temperature field. Deposits that formed on the impact surface, using the coupled framework, altered the velocity field by as much as 130% but had a limited effect on the temperature field.
Simulations were also done that looked at the formation of an equilibrium deposit when a cold jet impinged on a relatively hotter surface, under continuous particle injection. An equilibrium deposit was found to form as deposited particles created a heat barrier on the high temperature surface, limiting more particle deposition. However, due to the transient nature of the system, the deposit temperature increased once deposition was halted. Further particle injection was not performed, but it can be predicted that the formed deposit would begin to grow again.
Additionally, a Large-Eddy Simulation (LES) simulation, with the inclusion of the Smagorinsky subgrid model, was performed to observe particle deposition in a turbulent flow field. Deposition of sand particles was observed as a turbulent jet (Re jet=23000,T_jet^*= 1200 K) impinged on a hotter surface(T_surf^*= 1600 K). Differences between the simulated flow field and relevant experiments were attributed to differing jet exit conditions and impact surface thermal conditions. The deposit was not substantive enough to have a significant effect on the flow field. With no difference in the flow field, no difference was found in the capture efficiency between the coupled and decoupled frameworks.Master of Science
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Mohekar, Ajit. "Computational modeling of triple layered microwave heat exchanger." Digital WPI, 2018. https://digitalcommons.wpi.edu/etd-theses/276.
Повний текст джерелаАнотація:
A microwave heat exchanger (MHE) is a device which converts microwave (MW) energy into usable form of heat energy. The working principle of the MHE is based on a collective effect of electromagnetic wave propagation, heat transfer and fluid flow, so the development of an efficient device requires complicated experimentation with processes of different physical nature. A peculiar phenomenon making the design of MHE even more challenging is extit{thermal runaway}, a nonlinear phenomenon in which a small increase in the input power gives rise to a large increase in temperature. Such high temperature may result in material damage through excessive thermal expansion, cracking, or melting. In this Thesis, we report on an initial phase in the development of a computational model which may help clarify complicated interaction between nonlinear phenomena that might be difficult to comprehend and control experimentally. We present a 2D multiphysics model mimicking operation of a layered MHE that simulates the nonlinear interaction between MW, thermal, and fluid flow phenomena involved in the operation of the MHE. The model is built for a triple layered (fluid-ceramic-fluid) MHE and is capable of capturing the S- and SS-profiles of power response curve which determines steady-state temperature solution as a function of incident power. The model is implemented on the platform of the COMSOL Multiphysics modeling software. We show that a MHE with particular thickness and dielectric properties of the layers can operate efficiently by keeping temperatures during thermal runaway under control. Overall temperatures increase rapidly as soon as the local maximum temperature reaches a critical value. This condition is held true both in absence and in presence of fluid flow. It is demonstrated that the efficiency of the MHE dramatically increases when thermal runaway is achieved. As the amount of heat energy, which is being transferred to the fluid from the heated dielectric, increases, incident power required to achieve thermal runaway also increases. It is also shown that, with appropriate length of the layered MHE, thermal runaway can be achieved at a lower power level. While the model developed in this Thesis studies the basic operation of a three layered MHE, it can further be developed to investigate optimum design parameters of the MHE of other structures so that maximum thermal efficiency is achieved.
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Abou-Ardate, Abdul Kader. "On-line computation of system operating limits with respect to thermal constraints." [Ames, Iowa : Iowa State University], 2006.
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Majumdar, Shubhaditya. "Thermal Transport in Organic-Inorganic Heterojunctions: Experimental Measurements and Computational Predictions." Research Showcase @ CMU, 2016. http://repository.cmu.edu/dissertations/839.
Повний текст джерелаАнотація:
The objective of this work is to investigate thermal transport physics in organic-inorganic heterojunctions employing experimental and computational techniques. A self-assembled monolayer (SAM) junction, a two-dimensional array of ordered molecules sandwiched between two metal leads, is used as the primary investigative system. The SAM structure provides a convenient platform to isolate the junction transport properties that are otherwise difficult to characterize when using three-dimensional organic-inorganic hybrid materials with embedded interfaces. A combination of deposition and lift-off techniques are used to fabricate the SAM junctions and frequency domain thermoreflectance (FDTR) is employed to measure the junction thermal conductance. Molecular dynamics (MD) simulations are used to further probe the vibrational properties and intermolecular cooperative behavior of the junction components and identify their effects on the thermal transport trends. A statistical rough surface contact model is also developed to estimate the percentage contact area between two rough surfaces interacting through covalent bonds. The quality of contact at interfaces is crucial for the accurate interpretation of experimentally measured transport properties of such molecular junctions. I present the first-ever measurements of the thermal conductance of SAM junctions formed between metal leads with systematically mismatched phonon spectra. The experimental observation that junction thermal conductance (per molecule) decreases as the mismatch between the lead vibrational spectra increases, paired with results from MD simulations, suggest that phonons scatter elastically at the metal-SAM interfaces. Furthermore, a known discrepancy between measurements and MD predictions of SAM thermal conductance is resolved by using the contact mechanics model to predict the extent of areal contact in the metal-SAM-metal experimental junctions. Further investigations of the nature of scattering at the metal-SAM interfaces using MD simulations reveal limitations in this computational scheme to study mismatched SAM junctions. These are related to the classical nature of the MD simulations that allow vibrational coupling to occur at the metal-SAM-metal junction that is not present in the experimental system. I present methods to circumvent this limitation and validate the predicted thermal transport trends with analytical models. The statistical contact model is derived to predict areal contact between two rough surfaces interacting through covalent bonds and is validated using thermal conductance measurements of SAM junctions. The model is also capable of handling the contact between a two-dimensional surface and substrate, which is relevant for studying the contact of supported two-dimensional materials. I also present a methodology to extend this model to handle layered substrates (i.e. a substrate with layers of distinct atomic species), which are present in nanostructured devices. The effect of the cooperative behavior between molecules on thermal transport across molecular junctions is investigated using a binary SAM system. This system enables one to tailor the local molecular environment within the junction. A non-linear change in thermal conductance as a function of molecular composition of the SAM is observed indicating that the molecules are not independent heat channels. The thermal transport through the molecules that are weakly coupled to the leads is enhanced when strongly coupled molecules are placed in their vicinity. The per molecule thermal conductance increases with increasing average separation between the molecules, suggesting the challenge in predicting single molecule properties from parallel structures and vice-versa. The findings in this thesis can potentially be used to tailor transport properties of hybrid materials for devices such as thermoelectrics, light-emitting diodes, photovoltaics and electronic devices. Thermal management in such devices, which is crucial especially when they are extremely thin, can also be improved using design principles that enhance thermal transport across the organic-inorganic heterojunctions.
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Srinivasan, Sriraj Soroush Masoud. "Computational and experimental study of spontaneous thermal polymerization of alkyl acrylates /." Philadelphia, Pa. : Drexel University, 2009. http://hdl.handle.net/1860/3131.
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Romagnoli, Alessandro. "Aerodynamic and thermal characterization of turbocharger turbines : experimental and computational evaluation." Thesis, Imperial College London, 2010. http://hdl.handle.net/10044/1/6134.
Повний текст джерелаАнотація:
Turbochargers are widely used in both passenger and commercial vehicle applications to increase power density, improved fuel economy leading to significant emissions reductions. In recent years, car manufacturers have introduced turbochargers widely in the diesel market in response to the stricter regulations in exhaust emissions. Although investment in turbocharger technology has made it possible to overcome issues related to reliability and cost, research is much needed in the area of design, testing methodologies and model development. This is particularly the case when considering unsteady flow effects. Computational codes are used by engine manufacturers to predict its performance and size components; prediction accuracy is crucial in this process. This thesis contributes to this process in several ways: steady modelling and heat transfer predictions. Furthermore, most aero-thermal design and analysis codes need data for validation; often the data available falls outside the range of conditions the engine experiences in reality leading to the need to interpolate and extrapolate excessively. The current work also contributes to this area by providing extensive experimental data in a large range of conditions. A further contribution of this work is the understanding of the turbine performance under pulsating flow; it shows that this performance deviates from the commonly used quasi-steady assumption in turbocharger/engine matching. A turbocharger is subjected to high temperature conditions; heat transfer within the turbine and the compressor severely affects the compressor performance at low rotational speeds and mass flow rates. Compressor maps provided by turbocharger manufacturers do not usually take into account the effects of heat transfer; this causes a mismatch when fitting the maps into engine codes which is detrimental to the overall engine performance prediction. The experimental investigation was conducted on three different turbine designs for an automotive turbocharger. The design progression was based on a commercial nozzleless unit modified into a variable geometry single as well as a twin-entry turbine configuration. The main geometrical parameters of these turbines were kept constant to allow equivalent performance assessment. The mixed-flow rotor used in this study consists of 12 blades with a constant inlet blade angle of +20°, a cone angle of 50° and a tip diameter of 95.2mm. The variable geometry stator consists of 15 vanes fitted into a ring mechanism, capable of pivoting in the range of 40° and 80° (with reference to the radial direction). The design progression into twin-entry turbine was completed by fitting a divider (accounting for only ≈6% of the overall internal volume) within volute. The turbine response for different vane angles (40° to 70°) and mass flow ratios between the two entries of the turbine was assessed. The turbine was tested under steady and pulsating flow conditions for two rotational speeds, 27.9 rev/s·√K and 43.0 rev/s·√K, a velocity ratio (U2/Cis) of 0.3 - 1.1 and a pulse frequency of 40 - 80Hz under both in-phase and out-of-phase conditions. A meanline aerodynamic model capable of predicting the performance parameters was developed for the nozzleless and the variable geometry single-entry turbine. The former was validated against experimental results spanning an equivalent speed range of 27.9 rev/s·√K and 53.8 rev/s·√K while the latter validated against one single speed (43.0 rev/s·√K) and three different vane angle settings (40°, 60° and 70°). The wide range of tests data from the Imperial College High Speed Dynamometer enabled the evaluation of the model in areas of the maps where currently no data exists. Based on the model prediction, a breakdown aerodynamic loss analysis was performed. As for the twin-entry turbine, the interaction between the two entries was investigated. Based on experimental evidence, a map-based method was developed to uniquely correlate the flow capacity within the entries for both partial and unequal admission. An investigation into the effects of heat transfer on a turbocharger was performed using a commercial turbocharger mounted on a 2.0 litre diesel engine. The global objective of these tests was to improve the understanding of heat transfer in turbochargers under realistic engine conditions. Measurements were obtained for engine speeds between 1000 and 3000 rpm at a step of 500 rpm – for each engine speed the load applied was varied from 16 to 250 Nm. In addition to the standard set of measurements needed to define the turbo operating point, the turbocharger was equipped with 17 thermocouples positioned in different locations in order to quantify the temperatures of the components constituting the turbocharger. A simplified 1-D heat transfer model was also developed and compared with experimental measurements. The algorithms calculate the heat transferred through the turbocharger, from the hot to the cold end by means of lump capacitances. The compressor performance deterioration from the adiabatic map was then predicted and based on the data generated by the model a multiple regression analysis was developed in order to assess the main parameters affecting the compressor non-adiabatic performance.
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Yoo, Jee Soo. "Computational study on controlling the optical properties of solar thermal fuels." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/123622.
Повний текст джерелаАнотація:
Thesis: S.M., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2019Cataloged from PDF version of thesis.
Includes bibliographical references (pages 62-72).
Solar thermal fuels utilize molecules that undergo reversible photo-isomerization to convert solar energy into stored thermal energy.¹ Because solar thermal fuels produce no emissions and can store and convert energy within one material, they are an attractive option for a renewable energy source. However, it has remained a challenge to identify a suitable solar thermal fuel material that exhibits high energy density, high energy conversion efficiency, long energy storage lifetime, and can be produced at low cost. A recent proposal is a nanotemplate-photoisomer hybrid system, e.g. functionalized azobenzene, a well-known photoisomer molecule, attached to carbon nanostructure templates such as carbon nanotubes, graphene, pentacene or alkene chains. Such structures have been suggested and tested as candidate solar thermal fuel materials with high energy density and long storage time²⁻⁴ In this thesis work, we further investigated optical properties of functionalized azobenzene and geometry-modified azobenzene. We found the best structure that yields maximum optical isomerization rate for trans-azobenzene and minimum optical isomerization rate for cis-azobenzene, calculating the reaction rate based on overlap between the solar spectrum and optical spectra calculated using time-dependent density functional theory (TDDFT). We showed that energy-charged-state molecule (cis-isomer) content at the photostationary state can be improved from 73 percent for pure azobenzene to 83 percent and to 97 percent by functionalizing azobenzene and a designing different geometry for azobenzene, respectively. From this, a desired structure for nanotemplates-photoisomer hybrid system can be estimated and same calculation technique may be employed to calculate and optimize photostationary state of the nanotemplates-photoisomer hybrid system.
by Jee Soo Yoo.
S.M.
S.M. Massachusetts Institute of Technology, Department of Materials Science and Engineering
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Kurzawa, Nils [Verfasser], and Mikhail [Akademischer Betreuer] Savitski. "Computational methods for thermal stability proteomics / Nils Kurzawa ; Betreuer: Mikhail Savitski." Heidelberg : Universitätsbibliothek Heidelberg, 2021. http://d-nb.info/1235674673/34.
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黎浩然 and Ho-yin Albert Lai. "Artificial intelligence based thermal comfort control with CFD modelling." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1999. http://hub.hku.hk/bib/B3122278X.
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Andersson, Per-Åke. "Computation of Thermal Development in Injection Mould Filling, based on the Distance Model." Licentiate thesis, Linköping University, Linköping University, Optimization, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-5733.
Повний текст джерелаАнотація:
The heat transfer in the filling phase of injection moulding is studied, based on Gunnar Aronsson’s distance model for flow expansion ([Aronsson], 1996).
The choice of a thermoplastic materials model is motivated by general physical properties, admitting temperature and pressure dependence. Two-phase, per-phase-incompressible, power-law fluids are considered. The shear rate expression takes into account pseudo-radial flow from a point inlet.
Instead of using a finite element (FEM) solver for the momentum equations a general analytical viscosity expression is used, adjusted to current axial temperature profiles and yielding expressions for axial velocity profile, pressure distribution, frozen layer expansion and special front convection.
The nonlinear energy partial differential equation is transformed into its conservative form, expressed by the internal energy, and is solved differently in the regions of streaming and stagnant flow, respectively. A finite difference (FD) scheme is chosen using control volume discretization to keep truncation errors small in the presence of non-uniform axial node spacing. Time and pseudo-radial marching is used. A local system of nonlinear FD equations is solved. In an outer iterative procedure the position of the boundary between the “solid” and “liquid” fluid cavity parts is determined. The uniqueness of the solution is claimed. In an inner iterative procedure the axial node temperatures are found. For all physically realistic material properties the convergence is proved. In particular the assumptions needed for the Newton-Mysovskii theorem are secured. The metal mould PDE is locally solved by a series expansion. For particular material properties the same technique can be applied to the “solid” fluid.
In the circular plate application, comparisons with the commercial FEM-FD program Moldflow (Mfl) are made, on two Mfl-database materials, for which model parameters are estimated/adjusted. The resulting time evolutions of pressures and temperatures are analysed, as well as the radial and axial profiles of temperature and frozen layer. The greatest differences occur at the flow front, where Mfl neglects axial heat convection. The effects of using more and more complex material models are also investigated. Our method performance is reported.
In the polygonal star-shaped plate application a geometric cavity model is developed. Comparison runs with the commercial FEM-FD program Cadmould (Cmd) are performed, on two Cmd-database materials, in an equilateral triangular mould cavity, and materials model parameters are estimated/adjusted. The resulting average temperatures at the end of filling are compared, on rays of different angular deviation from the closest corner ray and on different concentric circles, using angular and axial (cavity-halves) symmetry. The greatest differences occur in narrow flow sectors, fatal for our 2D model for a material with non-realistic viscosity model. We present some colour plots, e.g. for the residence time.
The classical square-root increase by time of the frozen layer is used for extrapolation. It may also be part of the front model in the initial collision with the cold metal mould. An extension of the model is found which describes the radial profile of the frozen layer in the circular plate application accurately also close to the inlet.
The well-posedness of the corresponding linearized problem is studied, as well as the stability of the linearized FD-scheme.
Report code: LiU-TEK-LIC-2002:66.
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AL-AZMI, BADER SHABEEB. "ANALYSIS OF TRANSPORT MODELS AND COMPUTATION ALGORITHMS FOR FLOW THROUGH POROUS MEDIA." The Ohio State University, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=osu1051059625.
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Al-Khwaji, Abdusalam. "Computational and Experimental Modeling of the Bioheat Transfer Process of Perfusion in Tissue Applied to Burn Wounds." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/19368.
Повний текст джерелаАнотація:
A new mathematical model has been developed along with a new parameter estimation routine using surface temperature and heat flux measurements to estimate blood perfusion and thermal resistance in living tissue. Dynamic thermal measurements collected at the surface of the sensor before and after imposing a dynamic thermal cooling event are used with the model to estimate the blood perfusion, thermal resistance and core temperature. The Green\'s function based analytical solution does not require calculation of the whole tissue temperature distribution, which was not the case for the previous models. The result from the new model was proved to have better and more consistent results than previous models. The new model was validated to solve one of the unsolved biomedical problems which is the ability of detecting burn severity. The method was tested with a phantom perfusion system. The results matched known blood perfusion and thermal resistance values. The method was also tested with burns on animal models. Inflammation effects associated with the burns were studied using a newly developed term called the Burn Factor. This correlated with the severity of imposed burns.This work consists of three journal papers. The first paper introduces the mathematical model and its validation with finite-difference solutions. The second paper validates the physical aspects of the usage of the model with thermal measurement in detecting simulated burned layers and the associated perfusion. The third paper demonstrates the ability of the model to use thermal measurements to detect different burn severity of an animal model and to study the healing process.
Ph. D.
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Sazhina, E. M. "Numerical analysis of autoignition and thermal radiation processes in diesel engines." Thesis, University of Brighton, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299221.
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Badenhorst, Reginald Ivor. "Computational Fluid Dynamics analysis of flow patterns in a thermal tray dryer." Diss., University of Pretoria, 2010. http://hdl.handle.net/2263/27534.
Повний текст джерелаАнотація:
Industrial tray air-dryers are increasingly used for the drying of agricultural products. The main drawback of these dryers is the non-uniform velocity distribution in the drying zone resulting in a non-uniform drying of the product. Computational Fluid Dynamics (CFD) software was implemented to predict and decrease the non-uniform velocity distribution of various dryer configurations. Tunnel dryers in commercial use were used to obtain experimental data. The CFD results were correlated with the test data. Trolley and tray tunnel dryers provide a relatively simple, low capital intensive and versatile method for drying a wide range of products. Artificial drying has the advantage of controlled drying conditions compared to traditional sun drying. The main focus of every tunnel design should be the improvement of the quality of the product in terms of colour, texture and aroma. Increasing the evaporation rate without increasing the energy required to do so, should always be done in-line with this main objective. Many studies focus on the mango structure and food dehydration principles that influence the uniform drying product with the assumption that the airflow over the produce is uniform. Few have been conducted on the air movement inside industrial dryers. CFD analysis predicts the airflow without influencing the airflow pattern compared to the measuring equipment inside test dryers. The experimental data were obtained from an empty dryer without a flow diverter. This was compared to dryer with the flow diverter included and compared to a dryer with the trolleys, trays and mango slices included. The test results showed that turbulence created by this configuration, still played a major role in the nonuniform velocity distribution along the drying zone of the tunnel. The inclusion of a flow diverter did however dampen the swirl effect of the main fan. Measuring the velocity distribution was practically difficult with the handheld devices used, which influenced the accuracy of the measurements taken. This justified the CFD analysis in order to better visualise and predict the airflow pattern inside the dryer. The total average speed CFD results of the sections in the drying zone (without mangoes and trolleys) of the dryer without a flow diverter was 11.2% higher compared to the test results. It was 14% higher for the dryer with the flow diverter included. The dryer with the mangoes, trays, trolleys and flow diverter showed a large difference where the total average speed of the CFD analysis was 49% higher compared to the test results. The main reason for the difference of the CFD analysis compared to the measured results are the factors that influenced the uncertainty of the experimental set up. The CFD analysis showed that the coefficient of variance (CV) of the dryer with the flow diverter (mangoes and trolleys included) was 3% lower compared to the dryer without one. Various dryer configurations were analysed using the CFD software to investigate what the best combination of flow diverter, vanes and blanking-off plates would be. A dryer configuration where flow diverters (Up-and-downstream of the main fan) above the false ceiling and inside the drying zone was analysed. A 16% decrease in terms of the CV value was obtained compared to the dryer with just the flow diverter downstream of main fan above the false ceiling. There was however a large region of swirl upstream of the main above the false ceiling resulting in a larger loss of heated air through the outlet fan before it reached the drying zone. The cost of manufacturing a simple vane and flow diverter for an existing dryer is 4% of the initial building costs (excluding the initial cost of the trolleys). The overall drying uniformity of this dryer is improved according to the CFD analysis by 7%. A cost analysis (taking into account the 15 year life cycle of a dryer) in terms of the energy requirement to evaporate water from the drying zone, showed that the dryer with the flow diverter was 6% less expensive to run on a yearly basis. Labour costs will be lower due to man-hours saved in terms of sorting out the wet slices from the dried product. Resources (dryers and trolleys) that would have been used for re-drying the wet produce, could now be implemented to increase the production rate of the plant. CopyrightDissertation (MEng)--University of Pretoria, 2010.
Mechanical and Aeronautical Engineering
unrestricted
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Sagerman, Denton Gregory. "Hypersonic Experimental Aero-thermal Capability Study Through Multilevel Fidelity Computational Fluid Dynamics." University of Dayton / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1499433256220438.
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Bensassi, Khalil. "Contribution to the Numerical Modeling of the VKI Longshot Hypersonic Wind Tunnel." Doctoral thesis, Universite Libre de Bruxelles, 2014. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/229727.
Повний текст джерелаАнотація:
The numerical modelling of the VKI-Longshot facility remains a challeng-ing task as it requires multi-physical numerical methods in order to simulate all the components. In the current dissertation, numerical tools were developed in order to study each component of the facility separately and a deep investigations of each stage of the shot were performed. This helped to better understand the different processes involved in the flow development inside this hypersonic wind tunnel. However the numerical computation of different regions of the facility treated as independent from each others remains an approximation at best.The accuracy of the rebuilding code for determining the free stream conditions and the total enthalpy in the VKI-Longshot facility was investigated by using a series of unsteady numerical computations of axisymmetric hypersonic flow over a heat flux probe. Good agreement was obtained between the numerical results and the measured data for both the stagnation pressure and the heat flux dur- ing the useful test time.The driver-driven part of the Longshot facility was modelled using the quasi one-dimensional Lagrangian solver L1d2. The three main conditions used for the experiments —low, medium and high Reynolds number —were considered.The chambrage effect due to the junction between the driver and the driven tubes in the VKI-Longshot facility was investigated. The computation showed great ben- efit of the chambrage in increasing the speed of the piston and thus the final compression ratio of the test gas.Two dimensional simulations of the flow in the driver and the driven tube were performed using Arbitrary Lagrangian Eulerian (ALE) solver in COOLFLuiD. A parallel multi-domain strategy was developed in order to integrate the moving piston within the computational domain.The computed pressure in the reservoir is compared to the one provided by the experiment and good agreement was obtained for both con- editions.Finally, an attempt was made to compute the starting process of the flow in the contoured nozzle. The transient computation of the flow showed how the primary shock initiates the flow in the nozzle before reaching the exit plan at time of 1.5 [ms] after the diaphragm rupture. The complex interactions of the reflected shocks in the throat raise the temperature above 9500 [K] which was not expected. Chemical dissociation of Nitrogen was not taken into account during this transient investigation which may play a key role considering the range of temperature reached near the throat.Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished
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De, Abreu Negreiros Bianca. "Building design and environmental performance : thermal comfort through thermal mass and natural ventilation in social housing in Northeast Brazil." Thesis, University of Manchester, 2018. https://www.research.manchester.ac.uk/portal/en/theses/building-design-and-environmental-performance-thermal-comfort-through-thermal-mass-and-natural-ventilation-in-social-housing-in-northeast-brazil(71a83bde-8a7c-43d1-a181-2bb340dcb639).html.
Повний текст джерелаАнотація:
Environmental consciousness leads the construction industry to greater concerns about local adaptation, less waste of resources and energy efficiency In Brazil, earth construction is a feasible approach to house building in many locations and can play a useful part in resolving the housing problems faced by that country, being already a popular approach to providing affordable housing for low income groups within the population, particularly in the Northeast Region of the country, although usually not built correctly. Although used since the colonial period, from 1500, knowledge around earth systems is not formally embedded within the Brazilian building standards and this is unhelpful in terms of promoting quality of performance of buildings thus constructed. For example, appropriate use of high thermal mass in conjunction with natural ventilation, which is frequently used in Brazil due to energy costs, can significantly influence the thermal comfort within residences, but appropriate guidance is lacking. This research considers the combined effects of earth construction and natural ventilation upon thermal comfort within social housing in Northeast Brazil. The main thesis hypothesis is that the use of thermal mass provided by earth construction combined with natural ventilation results in acceptable levels of thermal performance with respect to thermal comfort in both hot and humid and hot and dry climates. The aim is to evaluate the thermal performance of high thermal mass dwellings using adobe system combined with natural ventilation in the bioclimatic zones of Brazil's Northeast Region. The method explores thermal performance simulation using Design Builder, a graphical interface for Energy Plus program. The assessment uses parametric analysis and the adaptive thermal comfort index from de Dear and Brager (1998). The results suggest that earth construction provides a high number of comfort hours in all bioclimatic zones in Northeast Brazil and ventilation use enhances the comfort sensation.
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Farhoudi, Yalda. "Measurement and computation of thermal stresses in injection molding of amorphous and crystalline polymers." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0018/NQ44426.pdf.
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Hernandez, Tascon Mauricio. "Experimental and computational evaluation of thermal performance and overheating in double skin facades." Thesis, University of Nottingham, 2008. http://eprints.nottingham.ac.uk/10628/.
Повний текст джерелаАнотація:
Double Skin Facades (DSFs) have been developed as an alternative technology to improve the thermal performance of conventional fully glazed buildings. Nevertheless, there is little test information on the behaviour and real performance of DSFs. This is specifically the case when the facade has to perform under extreme or moderate summer conditions. The characteristics of thermal overheating of a specific type of DSF with various configurations and its practical control have not been subjected to systematic experimental and computational investigations. This research which is based on an existent load of knowledge, carried out experiments of a full-scale one-storey laboratory chamber of a selected type of Double Skin Facade in which a comparative analysis of the thermal performance is assessed, CFD simulations of the experimental model and a Field Case Study of an existing building in the United Kingdom is also monitored. The basic thermal behaviour in the facade cavity and adjacent room is investigated by a series of parametric studies and basic flow field investigations. Section models of the DSF chamber and the case building were made and modelled using CFD in order to visualise the thermal and airflow behaviour inside the DSF complementing the experimental and field work. The modelling work has demonstrated the feasibility and versatility of the technique for probing the flow and thermal behaviour of double skin facades. It was found that natural ventilation through the cavity by a series of controlled opening shafts on the upper and lower facade are effective means to reduce DSF overheating. It was also observed that the optical properties of cavity elements, cavity depth size, solar control and the basic operation of the facade are key issues to address in order to prevent overheating and additional heat loads from the facade.
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Charmeau, Anne. "A computational thermal-fluid modeling approach to pulsed and steady gas core reactors." [Gainesville, Fla.] : University of Florida, 2004. http://purl.fcla.edu/fcla/etd/UFE0003720.
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Zhang, Hantao S. M. Massachusetts Institute of Technology. "Computational investigation of the thermal conductivities and phonon properties of strontium cobalt oxides." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/123356.
Повний текст джерелаАнотація:
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Thesis: S.M., Massachusetts Institute of Technology, Department of Nuclear Science and Engineering, 2019
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 87-91).
The thermal conductivities of electrochemically tuned strontium cobalt oxides (SCO) are significantly different among the perovskite SrCoO3 (P-SCO), the brownmillerite SrCoO2.5 (BM-SCO) and the hydrogenated HSrCoO2.5 (H-SCO)1. The underlying mechanism causing this large difference is still unclear. And phonon properties in SCO have not been investigated thoroughly or have some contradictive predictions. In this work, we have calculated the thermal conductivities in P-SCO and BM-SCO by applying molecular and lattice dynamics, and successfully reconstructed the large difference of the thermal conductivities, consistent with measurements. Furthermore, several phonon properties including heat capacities, group velocities, lifetimes and mean free paths have been calculated, and the key roles of local atomic environment and crystal symmetry in determining the thermal conductivities have been identified. We have also analyzed the impact of interfaces, isotropic strains and defects on thermal conductivities, predicted the neutron scattering intensity in P-SCO, and tested the accuracy and performance of molecular dynamics based on deep learning. Additionally, even though the calculations about the phonon properties in H-SCO are not complete, it still offers some inspirations about its thermal conductivity. The thorough investigations about the phonon properties and the mechanisms determining the thermal conductivities in SCO may benefit future research about tunable thermal conductivities in complex oxides.
by Hantao Zhang.
S.M.
S.M. Massachusetts Institute of Technology, Department of Nuclear Science and Engineering
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Osborn, Tim H. "COMPUTATIONAL DESIGN AND CHARACTERIZATION OF SILICENE NANOSTRUCTURES FOR ELECTRICAL AND THERMAL TRANSPORT APPLICATIONS." Wright State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=wright1401712678.
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Batkam, Hemo Serge. "Thermique multidomaines en simulation numérique du remplissage 3D." Paris, ENMP, 2002. http://www.theses.fr/2002ENMP0001.
Повний текст джерелаАнотація:
Du fait des caractéristiques spécifiques des polymères fondus (forte dissipation d’énergie mécanique, faible conductivité thermique, thermodépendance de la viscosité, chocs thermiques aux parois du moule), la modélisation et la résolution du problème thermique constituent un enjeu majeur dans la simulation numérique du procédé d’injection. Pour s’affranchir des problèmes d’instabilités engendrés par les approches de Galerkin standard, nous avons proposé dans ce travail une méthode originale basée sur une technique d’éléments finis espace-temps discontinus. L’interpolation spatiale consiste en l’utilisation d’éléments mixtes de bas ordre P0/P0+ en température/flux de chaleur. En temps, la température et le flux sont interpolés par des polynômes de degré n. La formulation spatio-temporelle résultante est locale et facile à implémenter. Elle a révélé de bonnes propriétés de stabilité, de robustesse, et est apparue efficace pour traiter simultanément des problèmes à convection dominante et des problèmes à diffusion dominante. Rapide, elle a permis de réduire considérablement les temps de calcul par rapport aux approches explicites. Une difficulté supplémentaire pour prédire correctement les transferts thermiques dans le polymère est la détermination de conditions aux limites réalistes à la paroi de la cavité. D’où l’intérêt de les repousser plus loin, à l’extérieur des outillages ou dans les canaux de régulation. Nous avons proposé un schéma numérique qui permet de prendre en compte la thermique des domaines environnants la cavité (approche multidomaines). Ce schéma ne nécessite pas la coïncidence des maillages à l’interface entre les différents domaines. Un traitement spécial aux interfaces permet de gérer naturellement les échanges thermiques entre deux domaines en contact, sans qu’il soit nécessaire de spécifier un coefficient de transfert à l’interface. L’ensemble des méthodes numériques développées ont été validées sur des solutions analytiques, puis implémentées dans le solveur thermique du logiciel REM3D®. Plusieurs exemples de remplissage 3D complexes, incluant un couplage thermomécanique dans la cavité, et éventuellement une thermique du moule et des inserts dans la cavité (injection/surmoulage) sont proposésSolving the thermal problem is a key point for the numerical simulation of injection molding. The main causes of the numerical difficulties encountered by classical Galerkin techniques are the specific characters of molten polymers: high energy dissipation, low thermal conductivity, thermal shocks at the mold wall, thermal dependence of rheology. In this contribution, we have developed a space-time finite element method to solve the heat equation. A discontinuous Galerkin technique using P0/P0+ elements is proposed for the steady problem. The transient problem is treated with a discontinuous high order finite element in time method. The so-built scheme is local and easy to implement. It reveals good properties of stability, robustness and speed. Its appears to be efficient both for convection dominant and diffusion dominant equations, and is therefore suitable for injection molding process. Another difficulty when modelling the thermal exchanges in the polymer is to define accurate boundary conditions at the cavity frontier. We have investigated a numerical scheme which allows to couple the computations in the polymer with thermal computations in domains surrounding the cavity (multidomain approach). This scheme does not require coincident meshes between the domains. A specific processing at the interfaces guarantees natural thermal exchanges between two domains in contact, with no regard of any particular heat exchange coefficient specified at the interface. All the proposed methods have been validated through analytic examples, then integrated to the thermal solver of REM3D® software. Several examples of complex 3D mold filling, including thermomechanical coupling in the cavity, and possibly thermal coupling in the mold or in inserts (overmolding injection process) are given
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Cunsolo, Salvatore. "Radiative properties computational modeling of porous cellular materials." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEI005/document.
Повний текст джерелаАнотація:
Les transferts thermiques par rayonnement dans des mousses sont modélisés à partir de la morphologie du matériau et des propriétés de sa phase solide. Dans ce travail de thèse, une attention particulière est portée sur les modèles radiatifs de Monte Carlo. Les différentes approches d’homogénéisation telles que « Homogeneous Phase » (HPA) and « Multi Phase » (MPA) sont discutées et comparées. Des développements novateurs sont proposés pour améliorer la précision des résultats. Nos avancées permettent de générer numériquement trois types de mousses périodiques couvrant un large domaine de matériaux cellulaires: mousse à pores fermés à haute porosité, mousse à cellules ouvertes à basse et haute porosité. Pour ces dernières, des comparaisons morphologiques avec des données expérimentales tomographiques, montrent des résultats satisfaisants et tendent à valider nos modèles de génération. Des mousses dont la phase solide est opaque ont tout d’abord été étudiées. Nos simulations ont permis de trouver de nouvelles lois analytiques précises permettant d’estimer les propriétés radiatives de ces matériaux à partir de données morphologiques. Ensuite, nous avons considéré des mousses, dont la phase solide est semi transparente. La modélisation du transfert radiatif au sein de ces milieux cellulaires est plus complexe. Les méthodes de modélisation des propriétés radiatives de la littérature, HPA et MPA, sont testées. Des simulations de Monte carlo directes dans les matériaux ont permis de mettre en exergue les limites de ces modèles. Des modèles novateurs ont été proposés afin d’ améliorer la précision des simulations. Ils sont basés sur une méthode hybride directe-inverse et une modification de l’équation de transfert radiatif classique. Ces nouveaux modèles (HPA+ et MPA+) ont été testés sur un ensemble varié de morphologies générées numériquement. Les modèles améliorés sont systématiquement plus précis que les modèles existantsCellular media such as plastic, ceramic and metal foams present specific characteristics that make them interesting for a number of applications related to thermal engineering. Their ability to minimize natural convection makes them ideal candidates for insulation applications, while the high specific surface and permeability to fluid of open cell foams makes them interesting heat transfer enhancers. In addition, their permeability to light makes them an ideal candidate for thermal radiation based applications, such as porous burners or solar energy collectors. In many of these application, thermal radiation heat transfer can have a significant influence on the heat transfer process. Both accurate radiation models and accurate morphological models of the structure of the foam are required. This work provides an original contribution on both these accounts. A discussion of the literature on numerical methods for radiation heat transfer in cellular media is presented, with focus on Monte Carlo methods. Homogeneous Phase (HPA) and Multi Phase (MPA) methods are discussed. Further efforts are required to accurately model and digitally replicate of foam morphologies. Our goal is to digitally generate three commonly occurring types of foam structures, covering a large range of real materials: high-porosity open cell foams, high-porosity closed cell foams, low-porosity open-cell structures. For high-porosity open cell foams, the automated parametric digital generation technique was validated against a dataset consisting of raw morphological data obtained by tomographic analysis. The generation capabilities were then applied to parametrically investigate the influence of morphological parameters on the radiative properties (namely, the extinction coefficient) of an opaque open-cell foam. Highly accurate analytical relationships were subsequently deduced and validated by comparison with results obtained from tomography samples. Modeling radiation in foams with a semi-transparent solid phase is substantially more complex. A Direct Monte-Carlo Homogenization reference technique is proposed, that allows to simulate radiation within arbitrary cavities and calculate macroscopic radiative quantities based on a Representative Elementary Volume (REV) of cellular material. The technique is validated against full scale Monte Carlo simulations. Improvements of the existing Homogeneous Phase and Multi Phase approach are proposed, through extensive use of inverse methods and the addition of one equation to take into account specific phenomena taking place in the semi-transparent solid phase. The resulting Improved Homogenized Approaches are extensively tested by comparing them with Direct Monte Carlo Homogenization simulations and existing homogenized models, on a varied set of morphologies making full use of the previously developed digital generation techniques. The improved models consistently outperform existing homogenized models
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Iyer, Kaushik A. "Quantitative characterization of thermophysical properties in computational heat transfer." Full text open access at:, 1993. http://content.ohsu.edu/u?/etd,273.
Повний текст джерела
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Davies, Gareth Frank. "Development of a predictive model of the performance of domestic gas ovens using computational fluid dynamics." Thesis, London South Bank University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263995.
Повний текст джерела
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Aldeeb, Abdulrehman Ahmed. "Systematic approach for chemical reactivity evaluation." Diss., Texas A&M University, 2003. http://hdl.handle.net/1969.1/159.
Повний текст джерелаАнотація:
Under certain conditions, reactive chemicals may proceed into uncontrolled chemical reaction pathways with rapid and significant increases in temperature, pressure, and/or gas evolution. Reactive chemicals have been involved in many industrial incidents, and have harmed people, property, and the environment. Evaluation of reactive chemical hazards is critical to design and operate safer chemical plant processes. Much effort is needed for experimental techniques, mainly calorimetric analysis, to measure thermal reactivity of chemical systems. Studying all the various reaction pathways experimentally however is very expensive and time consuming. Therefore, it is essential to employ simplified screening tools and other methods to reduce the number of experiments and to identify the most energetic pathways. A systematic approach is presented for the evaluation of reactive chemical hazards. This approach is based on a combination of computational methods, correlations, and experimental thermal analysis techniques. The presented approach will help to focus the experimental work to the most hazardous reaction scenarios with a better understanding of the reactive system chemistry. Computational methods are used to predict reaction stoichiometries, thermodynamics, and kinetics, which then are used to exclude thermodynamically infeasible and non-hazardous reaction pathways. Computational methods included: (1) molecular group contribution methods, (2) computational quantum chemistry methods, and (3) correlations based on thermodynamic-energy relationships. The experimental techniques are used to evaluate the most energetic systems for more accurate thermodynamic and kinetics parameters, or to replace inadequate numerical methods. The Reactive System Screening Tool (RSST) and the Automatic Pressure Tracking Adiabatic Calorimeter (APTAC) were employed to evaluate the reactive systems experimentally. The RSST detected exothermic behavior and measured the overall liberated energy. The APTAC simulated near-adiabatic runaway scenarios for more accurate thermodynamic and kinetic parameters. The validity of this approach was investigated through the evaluation of potentially hazardous reactive systems, including decomposition of di-tert-butyl peroxide, copolymerization of styrene-acrylonitrile, and polymerization of 1,3-butadiene.
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Nie, Qihong. "Experimentally validated multiscale thermal modeling of electronic cabinets." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26492.
Повний текст джерелаАнотація:
Thesis (Ph.D)--Mechanical Engineering, Georgia Institute of Technology, 2009.Committee Chair: Joshi, Yogendra; Committee Member: Gallivan, Martha; Committee Member: Graham, Samuel; Committee Member: Yeung, Pui-Kuen; Committee Member: Zhang, Zhuomin. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Guo, Zuojun. "Structural Stability of Nucleic Acids and Peptides: a Theoretical and Computational Study." Thesis, Boston College, 2012. http://hdl.handle.net/2345/3782.
Повний текст джерелаАнотація:
Thesis advisor: Udayan MohantyIn chapter one, two simple models are used to estimate the electrostatic contributions to the stiffness of short DNA fragments. The first model views DNA as two strands that are appropriately parameterized and are wrapped helically around a straight cylinder radius equal to the radius of the DNA molecule. The potential energy of the DNA due to phosphate-phosphate electrostatic interactions is evaluated assuming that the charges interact through Debye-Hückle potentials. This potential energy is compared with the potential energy as computed using our second model in which DNA is viewed as two helical strands wrapping around a curved tube whose cross-section is a disk of radius equal to the radius of the DNA. The results are compared with counterion condensation models and experimental data (Guo et al. J. Phys. Chem. B, 2008, 112, 16163-16169). In chapter two, the fidelity of translation selection begins with the base pairing of codon-anticodon complex between the mRNA and tRNAs. Binding of cognate and near-cognate tRNAs induces 30S subunit of the ribosome to wrap around the ternary complex, EF-Tu(GTP)aa-tRNA. We have proposed that large thermal fluctuations play a crucial role in the selection process. The binding energies of over a dozen unique site-bound magnesium structural motifs are investigated and provide insights into the nature of interaction of divalent metal ions with the ribosome (Guo et al. Proc. Nat. Acad. Sci. 2011, 108, 3947-3951). In chapter three, we use extensive molecular dynamics simulations to study a series of stapled alpha helical peptides over a range of temperatures in solution. The peptides are found to exhibit substantial variations in predicted helicities that are in good agreement with the experimental value. In addition, we find significant variation in local structural flexibility of the peptides with the position of the linker, which appears to be more closely related to the observed differences in activity than the absolute alpha helical stability (Guo et al. Chem. Biol. Drug. Des. 2010, 75, 348-359.). In chapter four, the alpha helical conformation and structural stability of single and double stapled all-hydrocarbon cross-linked p53 peptides in solution and when bound to MDM2 is investigated. We determined the effects of the peptide sequence, the stereochemistry of the cross-linker, the conformation of the double bond in the alkene bridge, the length of the bridge, on the relative stability of the alpha helix structure. The conformation population distribution indicates a fully helical state and several partially folded states. The distribution of dihedral pairs of the stapled peptides in the bound state indicates a significant population around the alpha helical region. Sequences over which the linker spans tend to have the highest helical occupancy. Significant helical content is observed for a double stapled p53 peptide at 575 K. The probability to form native contacts is increased when the stapled peptides are bound to MDM2. The distribution of the end-to-end distance of the peptides is bimodal
Thesis (PhD) — Boston College, 2012
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Chemistry
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Somani, Ankit. "Advanced thermal management strategies for energy-efficient data centers." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/26527.
Повний текст джерелаАнотація:
Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2009.Committee Chair: Joshi, Yogendra; Committee Member: ghiaasiaan, mostafa; Committee Member: Schwan, Karsten. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Moghimi, Ardekani Mohammad. "Optical thermal and economic optimisation of a linear Fresnel collector." Thesis, University of Pretoria, 2017. http://hdl.handle.net/2263/61313.
Повний текст джерелаАнотація:
Solar energy is one of a very few low-carbon energy technologies with the enormous potential to grow to a large scale. Currently, solar power is generated via the photovoltaic (PV) and concentrating solar power (CSP) technologies. The ability of CSPs to scale up renewable energy at the utility level, as well as to store energy for electrical power generation even under circumstances when the sun is not available (after sunset or on a cloudy day), makes this technology an attractive option for sustainable clean energy. The levelised electricity cost (LEC) of CSP with thermal storage was about 0.16-0.196 Euro/kWh in 2013 (Kost et al., 2013). However, lowering LEC and harvesting more solar energy from CSPs in future motivate researchers to work harder towards the optimisation of such plants. The situation tempts people and governments to invest more in this ultimate clean source of energy while shifting the energy consumption statistics of their societies from fossil fuels to solar energy.
Usually, researchers just concentrate on the optimisation of technical aspects of CSP plants (thermal and/or optical optimisation). However, the technical optimisation of a plant while disregarding economic goals cannot produce a fruitful design and in some cases may lead to an increase in the expenses of the plant, which could result in an increase in the generated electrical power price.
The study focused on a comprehensive optimisation of one of the main CSP technology types, the linear Fresnel collector (LFC). In the study, the entire LFC solar domain was considered in an optimisation process to maximise the harvested solar heat flux throughout an imaginary summer day (optical goal), and to minimise cavity receiver heat losses (thermal goal) as well as minimising the manufacturing cost of the plant (economic goal). To illustrate the optimisation process, an LFC was considered with 12 design parameters influencing three objectives, and a unique combination of the parameters was found, which optimised the performance. In this regard, different engineering tools and approaches were introduced in the study, e.g., for the calculation of thermal goals, Computational Fluid Dynamics (CFD) and view area approaches were suggested, and for tackling optical goals, CFD and Monte-Carlo based ray-tracing approaches were introduced. The applicability of the introduced methods for the optimisation process was discussed through case study simulations. The study showed that for the intensive optimisation process of an LFC plant, using the Monte Carlo-based ray-tracing as high fidelity approach for the optical optimisation objective, and view area as a low fidelity approach for the thermal optimisation objective, made more sense due to the saving in computational cost without sacrificing accuracy, in comparison with other combinations of the suggested approaches.
The study approaches can be developed for the optimisation of other CSP technologies after some modification and manipulation. The techniques provide alternative options for future researchers to choose the best approach in tackling the optimisation of a CSP plant regarding the nature of optimisation, computational cost and accuracy of the process.Thesis (PhD)--University of Pretoria, 2017.
Mechanical and Aeronautical Engineering
PhD
Unrestricted
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Wang, Liang. "Experimental and Computational Investigation of Thermal-Flow Characteristics of Gas Turbine Reverse-Flow Combustor." ScholarWorks@UNO, 2010. http://scholarworks.uno.edu/td/1212.
Повний текст джерелаАнотація:
Reverse-flow combustors have been used in heavy land-based gas turbines for many decades. A sheath is typically installed to provide cooling at an expense of large pressure losses, through small jet impingement cooling and strong forced convention channel flow. With the modern advancement in metallurgy and thermal-barrier coating technologies, it may become possible to remove this sheath to recover the pressure losses without melting the combustor chamber. However, without the sheath, the flow inside the dump diffuser may exert nonuniform cooling on the combustion chamber. Therefore, the objective of this project is to investigate the flow pattern, pressure drop, and heat transfer in the dump-diffuser reverse-flow combustor with and without sheath to determine if the sheath could be removed. The investigation was conducted through both experimental and computational simulation. The results show that 3.3% pressure losses could be recovered and the highest wall temperature will increase 18% without the sheath.
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Knutsen, Christopher. "Thermal analysis of the internal climate condition of a house using a computational model." Master's thesis, Faculty of Engineering and the Built Environment, 2021. http://hdl.handle.net/11427/32740.
Повний текст джерелаАнотація:
The internal thermal climatic condition of a house is directly affected by how the building envelope (walls, windows and roof) is designed to suit the environment it is exposed to. The way in which the building envelope is constructed has a great affect on the energy required for heating and cooling to maintain human thermal comfort. Understanding how the internal climatic conditions react to the building envelope construction is therefore of great value. This study investigates how the thermal behaviour inside of a simple house reacts to changes made to the building envelope with the objective to predict how these changes will affect human thermal comfort when optimising the design of the house. A three-dimensional numerical model was created using computational fluid dynamic code (Ansys Fluent) to solve the governing equations that describe the thermal properties inside of a simple house. The geometries and thermophysical properties of the model were altered to simulate changes in the building envelope design to determine how these changes affect the internal thermal climate for both summer and winter environmental conditions. Changes that were made to the building envelope geometry and thermophysical properties include: thickness of the exterior walls, size of the window, and the walls and window glazing constant of emissivity. Results showed that there is a substantial difference in indoor temperatures, and heating and cooling patterns, between summer and winter environmental conditions. The thickness of the walls and size of the windows had a minimal effect on internal climate. It was found that the emissivity of the walls and window glazing had a significant effect on the internal climate conditions, where lowering the constant of emissivity allowed for more stable thermal conditions within the human comfort range.
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Iwashita, Takuya. "Computational Studies on the Dynamics of Small-Particle Suspensions using Meso-Scale Modeling." 京都大学 (Kyoto University), 2009. http://hdl.handle.net/2433/77956.
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Cruz, Ethan E. "Coupled inviscid-viscous solution methodology for bounded domains: Application to data center thermal management." Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/54316.
Повний текст джерелаАнотація:
Computational fluid dynamics and heat transfer (CFD/HT) models have been employed as the dominant technique for the design and optimization of both new and existing data centers. Inviscid modeling has shown great speed advantages over the full Navier-Stokes CFD/HT models (over 20 times faster), but is incapable of capturing the physics in the viscous regions of the domain. A coupled inviscid-viscous solution method (CIVSM) for bounded domains has been developed in order to increase both the solution speed and accuracy of CFD/HT models. The methodology consists of an iterative solution technique that divides the full domain into multiple regions consisting of at least one set of viscous, inviscid, and interface regions. The full steady, Reynolds-Averaged Navier-Stokes (RANS) equations with turbulence modeling are used to solve the viscous domain, while the inviscid domain is solved using the Euler equations. By combining the increased speed of the inviscid solver in the inviscid regions, along with the viscous solver’s ability to capture the turbulent flow physics in the viscous regions, a faster and potentially more accurate solution can be obtained for bounded domains that contain inviscid regions which encompass more than half of the domain, such as data centers.