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1
Nategh, Shafigh. "Thermal Analysis and Management of High-Performance Electrical Machines." Doctoral thesis, KTH, Elektrisk energiomvandling, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-122695.
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This thesis deals with thermal management aspects of electric machinery used in high-performance applications with particular focus put on electric machines designed for hybrid electric vehicle applications. In the first part of this thesis, new thermal models of liquid (water and oil) cooled electric machines are proposed. The proposed thermal models are based on a combination of lumped parameter (LP) and numerical methods. As a first case study, a permanent-magnet assisted synchronous reluctance machine (PMaSRM) equipped with a housing water jacket is considered. Particular focus is put on the stator winding and a thermal model is proposed that divides the stator slot into a number of elliptical copper and impregna- tion layers. Additionally, an analysis, using results from a proposed simplified thermal finite element (FE) model representing only a single slot of the sta- tor and its corresponding end winding, is presented in which the number of layers and the proper connection between the parts of the LP thermal model representing the end winding and the active part of winding are determined. The approach is attractive due to its simplicity and the fact that it closely models the actual temperature distribution for common slot geometries. An oil-cooled induction machine where the oil is in direct contact with the stator laminations is also considered. Here, a multi-segment structure is proposed that divides the stator, winding and cooling system into a number of an- gular segments. Thereby, the circumferential temperature variation due to the nonuniform distribution of the coolant in the cooling channels can be predicted. In the second part of this thesis, the thermal impact of using different winding impregnation and steel lamination materials is studied. Conven- tional varnish, epoxy and a silicone based thermally conductive impregnation material are investigated and the resulting temperature distributions in three small induction machines are compared. The thermal impact of using different steel lamination materials is investigated by simulations using the developed thermal model of the water cooled PMaSRM. The differences in alloy con- tents and steel lamination thickness are studied separately and a comparison between the produced iron losses and the resulting hot-spot temperatures is presented. Finally, FE-based approaches for estimating the induced magnet eddycurrent losses in the rotor of the considered PMaSRM are reviewed and compared in the form of a case study based on simulations. A simplified three-dimensional FE model and an analytical model, both combined with time-domain 2D FE analysis, are shown to predict the induced eddy current losses with a relatively good accuracy compared to a complete 3D FE based model. Hence, the two simplified approaches are promising which motivates a possible future experimental verification.QC 20130528
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Burdett, Daniel Simon. "Analysis of thermal and compute performance of data centre servers." Thesis, University of Leeds, 2018. http://etheses.whiterose.ac.uk/20785/.
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Data centres are an increasingly large contributing factor to the consumption of electricity globally, and any improvements to their effectiveness are important in minimising their effect on the environment. This study aims to achieve this by looking at ways of understanding and more effectively utilising IT in data centre spaces. This was achieved through the testing of a range of ways of creating virtual load, and employing them on servers in a controlled thermal environment. A Generic Server Wind-tunnel was designed and built which afforded control of thermal environment and six different servers were tested within, yielding results on performance and thermal effect. Further testing was also conducted on a High Performance Computing server with a view to understanding the effect of internal temperature on performance. Transfer functions were created for each of the six servers, predicting behaviour reliability for five output functions and validating the developed methodology to an appropriate accuracy. The trends seen and the methodology presented should allowed data centre managers better insight into the behaviour of their servers.
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VanDerheyden, Andrew Louis. "Characterization of thermal coupling in chip multiprocessors." Thesis, Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/51892.
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For semiconductor processors temperature increases leakage current, which in turn in- creases the temperature of the processor. This increase in heat is seen by other parts of the processor since heat is diffusive across a processor die. In this way, cores are thermally coupled to one another such that when the temperature of one core increases, the temperatures of all cores on the same die can also increase. This increase in temperature and power consumption is not accompanied by any increase in performance. Cores on a chip can also be performance coupled to one another since cores can share data between them. These interactions between cores present new challenges to microarchitects who seek to optimize the energy consumption of a chip multiprocessor (CMP) comprised of multiple symmetric or asymmetric processing cores. This thesis seeks to understand and model the impact of thermal coupling effects between adjacent cores in a chip multiprocessor starting with measurements with a commercial multi-core processor. The hypothesis is that the thermal coupling of compute cores will be influenced by the adjacent core’s performance characteristics. Specifically, we expect thermal coupling is related to the nature of the workloads, e.g. compute intensive workloads will increase coupling over memory intensive workloads. However, we find that simpler parameters such as frequency of operation have more impact on coupling behaviors than the workload behaviors such as memory intensity or instruction retirement rates. A model is developed to capture thermal coupling effects and enable schemes to mitigate its impact.
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Kadlec, Kal, and Kal Kadlec. "Parametric Opto-Mechanical Performance Analysis of Mounted Lenses Under Thermal Loading." Thesis, The University of Arizona, 2017. http://hdl.handle.net/10150/625904.
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Mounting of lenses in opto-mechanical assemblies can create surface figure errors and refractive index changes through thermal and pre-load stresses. As lenses and barrels change in size under temperature changes, the optical performance degrades due to stress and surface deformations. Currently there is no way of determining the effect of these mechanical perturbations on the system wavefront without performing tedious finite element analysis. Most in-depth opto-mechanical analyses involve case-by-case studies with specific designs while previous general studies fail to take into account the complex geometries. The assumptions made by previous general studies ignore the effects of lens shape. These omissions can have a large effect on the stiffness, stress and surface figure error. A parametric model can combine the best of both an in-depth and general study. By parametrizing the model, a simple analysis can be executed for approximating the environmental-mechanical effects on optical performance. This eliminates the time it takes for an opto-mechanical design to be iterated for an optical or mechanical engineer. This tool could be used for early opto-mechanical design or for finite element analysis verification. The parametric model allows the exploration of the broader design study without confining it to a local design space.
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Huang, Zhaohui. "The analysis of thermal and fire performance of cementitious building components." Thesis, University of Central Lancashire, 1995. http://clok.uclan.ac.uk/1765/.
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This work is concerned with the thermal and structural behaviour of reinforced concrete members in fire conditions. The numerical analyses of temperature histories and mechanical behaviour of reinforced concrete structural members subjected to fire are the major components of this research. In this thesis a non-linear finite element procedure is proposed to predict the temperature distribution history in the cross section of structural members, such as beams composed of reinforced concrete, in fire conditions. A theoretical analysis of heat and moisture transfer in concrete was made which incorporated the simplifications that energy transfer by convection and diffusion in concrete could be neglected. However, the effect of water evaporation in concrete was considered. The thermal properties of concrete were considered as temperature and moisture dependent and the thermal properties of steel as temperature dependent only. The fire conditions were described by standard time-temperature fire curves and convection and radiation boundary conditions were used. In order to validate the model a series of verification tests have been carried out through a quantitative comparison of the model predictions against known test results. Fairly good accuracy has been found. A non-linear finite element procedure for predicting the structural behaviour of the planar reinforced concrete members is also developed. The proposed procedure is based on "plane stress" theory and an iterative, secant stiffness formulation is employed. The complex features of structural behaviour in fire conditions, such as thermal expansion, shrinkage, creep, transient strains, cracking or crushing and change of material properties with temperature are considered in this model. Predictions from the model proposed are compared against experimental results, as well as against the model proposedb y previous researchers, and a better correlation to experimental data is found. It is shown that the secant stiffness approach can provide good numerical stability for the analysis of planar reinforced concrete members in fire conditions. The model proposed in this study has the potential to predict the fire resistance of a planar reinforced concrete members with an accuracy that is adequate for practical purposes if realistic material properties are available.
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Ueda, Kimi. "A Study on Integrated Thermal Control to Improve Intellectual Work Performance." Doctoral thesis, Kyoto University, 2021. http://hdl.handle.net/2433/263750.
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Blair, Stuart R. (Stuart Ryan) 1972. "Thermal hydraulic performance analysis of a small integral pressurized water reactor core." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/17029.
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Thesis (Nucl. E. and S.M.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 2003.Includes bibliographical references (p. 117-121).
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
A thermal hydraulic analysis of the International Reactor Innovative and Secure (IRIS) core has been performed. Thermal margins for steady state and a selection of Loss Of Flow Accidents have been assessed using three methodologies to account for uncertainty. The thermal hydraulic analysis has shown that the IRIS is designed with adequate thermal margin for steady state operation, the locked rotor/shaft shear accident (LR/SS) and for variants of the partial loss of flow accident. To treat uncertainties, three methods were used, ranging from conservative, deterministic methods, to more realistic and computationally demanding Monte Carlo-based methods. To facilitate the computational requirements of the thermal hydraulic analysis, a script-based interface was created for VIPRE. This scripted interface (written in Matlab) supplants the existing file-based interface. This interface allows for repeated, automatic execution of the VIPRE code on a script-modifiable input data, and parses and stores output data to disk. This endows the analyst with much greater power to use VIPRE in parametric studies, or using the Monte Carlo-based uncertainty analysis methodology. The Matlab environment also provides powerful visualization capability that greatly eases the task of data analysis.
by Stuart R. Blair.
Nucl.E.and S.M.
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Blair, Stuart R. "Thermal hydraulic performance analysis of a small integral pressurized water reactor core." Thesis, Springfield, Va. : Available from National Technical Information Service, 2003. http://handle.dtic.mil/100.2/ADA417648.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 2003.Thesis supervisor: Neil E. Todreas. Includes bibliographical references (p. 117-121). Also available online.
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Arqam, Mohammad. "Thermomechanical analysis of compact high-performance electric swashplate compressor." Thesis, Griffith University, 2021. http://hdl.handle.net/10072/410159.
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This PhD is sponsored by industry and is part of a project to develop and manufacture smart electric compressor for mobile refrigeration and air conditioning applications on commercial and heavy vehicles including industrial machinery. Compact electric compressors are of great value for the future due to the growth of the electric vehicle market. Recent advancements in the field of mobile air conditioning and refrigeration have witnessed extensive use of the swashplate compressor due to its compact structure, continuous operation, small size, light weight and better thermal comfort inside the vehicle. The design of the swashplate compressor is complex so that it requires considerable contributions from different fields of engineering viz. engineering mechanics, heat transfer and fluid dynamics. The estimate of compressor performance through modelling and experiments at the early stages of design and development serves as a useful tool for the designer. The input power, torque, in-cylinder gas pressure and temperature, flow through valves, and volumetric efficiency are important parameters to characterize the compressor performance. In this thesis, a set of practical thermomechanical models are derived and validated against experiments. An ideal gas based analytical model is developed for a 10 cylinder swashplate compressor with a view to predict its performance in terms of shaft torque and mass flow rate for a given rotational speed requiring minimal computational effort to run. Three sub-models are developed to account for the piston and swashplate kinematics and dynamics through deriving expressions for piston displacement as an explicit function of angle of rotation of swashplate and interactions between forces and moments. The compression process model is formulated to predict in-cylinder temperatures and pressures during one revolution of the swashplate together with refrigerant mass flow rate in and out of the compressor. A complete time-varying model is then developed by combining above three sub-models. Results are obtained in terms of compressor torque and volumetric efficiency and agree well with experiments. Considering the importance of refrigerant flow through reed valves affecting compressor performance, a real-gas, restricted-flow valve model is also developed and compared with the ideal-gas, ideal-valve model. Real gas properties of R134a are evaluated using NIST standard reference database. A minor-loss discharge coefficient approach is used to determine the refrigerant flow rate through reed valves. The model predicts the discharge temperature, refrigerant mass flow rate and volumetric efficiency accurately as a function of rotational speed. The effect of real gas properties, heat transfer to and from the compressor wall during compression and expansion and the valve model are analyzed. The suction side valve model is found to have the largest influence on the compressor performance as a function of rpm whereas heat transfer model has the least. The key contribution of this study is in assembling a practical combination of models that is capable of capturing the essential physics without being overly complex. To the authors’ knowledge this is the first swashplate study that shows clearly the cyclic variation in thermo-physical properties. The literature shows the dynamic characteristics of the compressor are well connected with the start-up transients of the swashplate mechanism and the suction and discharge pressures. To evaluate this, an experimentally validated transient swashplate compressor model is developed including mass moment of inertia of the pistons and swashplate to evaluate the motor torque loading during compressor start-up. The effects of essential parameters such as moment of inertia, bearing torque, viscous resistance to the piston motion, suction and discharge pressures on the compressor performance are presented. The actual start-up behavior is tracked using a high-speed data logger capturing phase currents for the BLDC motor, instantaneous power and rotational speed. The suction and discharge pressures are found to have the largest influence on the starting torque whereas rotational mass moment of inertia has the least. The original contribution of this work is in deriving a transient swashplate compressor model that includes the mass moment of inertia of the swashplate mechanism and clarifying the relative importance of line pressures, viscous losses and bearing resistance on the start-up torque. Since minimizing the size of the compact Brushless DC (BLDC) motor driving the compressor is important, it is worth optimizing the cooling performance of the electric motor. An experimentally validated computational fluid dynamics (CFD) model is developed to investigate the thermal performance of an air-cooled Brushless Direct Current (BLDC) motor driving swashplate compressor. Different fin arrangements on the motor housing are analysed including small protrusions on the fin surface. The findings show greater enhancements can be achieved by adding an extra fin in the cooling flow passage rather than through the inclusion of grooved walls. Thermographs of the motor housing are found to be in close agreement with the model predictions. The key achievement of this thermal investigation is in demonstrating air-cooling is a practical and effective alternative to refrigerant cooling of compact high performance electric swashplate compressors for mobile refrigeration and air conditioning applications. The effect of thermal resistance between the windings and stator core of an air-cooled Brushless DC motor is also investigated. Measurements are found to be in close agreement with predictions. The numerical simulations suggest significant benefits of injecting encapsulation material in the stator core to enhance heat transmission from windings to the surrounding electrical steel. To confirm this, an experimental investigation is carried out by adding thermal resin to the winding slots on 2.5 kW and 4 kW brushless DC motors. The findings show that the potting material can reduce the temperature of the windings by 10 °C to 20 °C for electrical power inputs of 2.4 kW to 3.8 kW. The winding temperature is also found to be sensitive to the winding arrangement in the stator slot. With tighter, more compact windings also leading to significant temperature reductions.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Eng & Built Env
Science, Environment, Engineering and Technology
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Amer, Elhadi M. "Thermal analysis and kinetic studies of the decomposition of some high performance polymers." Thesis, University of Salford, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.272943.
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Ledwith, Alison C. (Alison Catherine). "Thermal mass performance in residential construction : an energy analysis using a cube model." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/78146.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 233-241).
Given the pervasiveness of energy efficiency concerns in the built environment, this research aims to answer key questions regarding the performance of thermal mass construction. The work presents the Cube Model, a simplified model of the single-family home. The model combines simplified geometry and equivalent envelope parameters with accurate climate data and internal loading assumptions. The model first addresses the notion as to whether building simplification is a valid means of analysis through a calibration and validation study. Then, the model is used to address three research areas on passive thermal mass: (1) the quantification of thermal mass performance with respect to material thermal properties; (2) the optimization of thermal mass performance for given material parameters; and (3) the sensitivity of thermal mass performance to infiltration and geometry effects. The experiments for wall and slab constructions, to address the first research area, demonstrate that the energy savings from thermal mass are both climate and season dependent. Results provide the magnitude of energy savings in fifty climates across the United States. Optimization experiments on the material thickness and conductivity, to address the second research area, show that constructions do not reach peak thermal mass performance at the same thermal properties in all climates. Sensitivity analyses, to address the third research area, indicate that passive thermal mass and tight construction practices can be mutually optimized without a trade-off of energy performance. Geometry effects demonstrate that modifications in building design can either benefit or hinder the performance of passive thermal mass. The combination of the results suggests that optimum design for thermal mass performance and the resulting energy consumption are climate-dependent and sensitive to many factors aside from material thermal properties.
by Alison C. Ledwith.
S.M.
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James, Gary. "Sustainable passive solar design: thermal performance analysis of the Subiaco Sustainable Demonstration Home." Thesis, James, Gary (2004) Sustainable passive solar design: thermal performance analysis of the Subiaco Sustainable Demonstration Home. Honours thesis, Murdoch University, 2004. https://researchrepository.murdoch.edu.au/id/eprint/38400/.
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Creating the built environment seems to require the destruction of the natural environment. The impact of a building on the environment goes far beyond the space that was cleared to make way for it. Humans require resources (energy, water, materials) to continue to live, work and play in the buildings that we have created. Reducing the impact of ever-enlarging human settlements is necessary to protect the environment in which we rely so much.
The Subiaco Sustainable Demonstration Home (SSDH) is a collaborative effort between a local council and the building industry to create a house that uses fewer resources than normally built homes during its construction, use, and eventual demolition. The house has sustainability design features for water efficiency and water recycling, energy generation and efficient energy use, Universal design for the disabled, Low-allergen design to improve internal air quality, and sustainably sourced materials to minimise the cost to the environment due to its construction.
The house has also been designed using Passive Solar (PS) design, so should remain thermally comfortable inside for most of the year, without the need of active heating or cooling systems. The house follows PS principles with: house and block having a north orientation, extensive glazing (protected in summer) on the north to maximise solar exposure in winter; internal thermal mass to minimise temperature swings; insulation to control heat energy flows; good ventilation to remove heat; and zoning to maximise human comfort.
The house was the subject of a thermal monitoring programme throughout 2004, which will continue to January 2006. The objective of the monitoring was to record the internal thermal conditions (temperature and humidity) to determine how effective the house is in remaining within established thermal comfort levels without the need of mechanically-based heating or cooling systems.
The house has demonstrated that it can remain within human thermal comfort levels for the majority of time, but needs to be operated properly by the occupants. In order for the house to be thermally comfortable, windows and curtains need to be opened at the right time to control the flow of energy into or out of the building. The result is a healthier, more comfortable living environment that is financially and environmentally cheaper to maintain than the currently constructed housing being created elsewhere around Australia.
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Li, Jia Zheng. "A comparison of the performance of a low voltage microprobe for two thermal field emitters." Full text open access at:, 1986. http://content.ohsu.edu/u?/etd,98.
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Costanzo, Vincenzo. "Cool Roofs for improving thermal performance of existing EU office buildings." Doctoral thesis, Università di Catania, 2016. http://hdl.handle.net/10761/3822.
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Cool materials are characterized by having a high solar reflectance - which is able to reduce heat gains during daytime - and a high thermal emissivity that enables them to dissipate the heat absorbed throughout the day during night.
Despite the concept of cool roofs - i.e. the application of cool materials to roof surfaces - is well known in US since 1990s, many studies focused on their performance in both residential and commercial sectors under various climatic conditions for US countries, while only a few case studies are analyzed in EU countries.
The present thesis work aims at analyzing the thermal benefits due to their application to existing office buildings located in EU countries. Indeed, due to their weight in the existing buildings stock, as well as the very low rate of new buildings construction, the retrofit of office buildings is a topic of great concern worldwide.
After an in-depth characterization of the existing buildings stock in the EU, the thesis gives an insight into roof energy balance due to different technological solutions, showing in which cases and to what extent cool roofs are preferable.
A detailed description of the physical properties of cool materials and their availability on the market provides a solid background for the parametric analysis carried out by means of detailed numerical models that aims at evaluating cool roofs performance for various climates and office buildings configurations.
With the help of dynamic simulations, the thermal behavior of representative office buildings of the existing EU buildings stock is assessed in terms of thermal comfort and energy needs for air conditioning. The results, which consider several variations of building features that may affect the resulting energy balance, show how cool roofs are an effective strategy for reducing overheating occurrences and thus improving thermal comfort in any climate. On the other hand, potential heating penalties due to a reduction in the heat fluxes passing through the roof are taken into account, as well as the aging process of cool materials.
Finally, an economic analysis of the best performing models shows the boundaries for their economic convenience.
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Hu, Xusheng. "Study of the Thermal Performance of Metal Foam and PCM Composite for Thermal Energy Storage." Thesis, Troyes, 2021. http://www.theses.fr/2021TROY0003.
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Le but de cette thèse est d'étudier les performances thermiques d'une mousse métallique ainsi que de ses composites avec un matériau à changement de phase (MCP) en utilisant des méthodes expérimentales et numériques. La mousse métallique étudiée possède une structure cellulaire cubique. Les effets des conditions de contact et de chaleur sur le taux de stockage de chaleur dans le composite MCP sont d’abord simulés numériquement. Ensuite, la mousse métallique avec une structure cellulaire cubique est conçue et fabriquée par impression 3D. L'étude expérimentale permet par la suite d’observer l'évolution de la fusion du MCP introduit dans la mousse métallique. Parallèlement, une méthode numérique à l'échelle des pores est utilisée pour simuler les caractéristiques de transfert thermique dans le composite MCP. Il ressort des résultats que la mousse métallique d'enrobage peut réduire le temps total de fusion du matériau MCP. Compte tenu de l'influence des paramètres de morphologie de la mousse métallique, nous avons étudié numériquement le comportement thermique de la mousse métallique en variant la porosité et la densité de pores. La dernière partie de cette thèse consiste à explorer une application de la mousse métallique dans les dissipateurs thermiques à base de MCP. Les essais expérimentaux sur composite MCP permettent d’obtenir la réponse thermique des dissipateurs thermiques. Les effets de la porosité de la mousse métallique et de la puissance du chauffage sur la réponse thermique du dissipateur thermique sont également mis en évidenceThe aim of this Ph.D. thesis is to study the thermal performance of metal foam and phase change material (PCM) composite by using the experimental and numerical methods, in which metal foam possesses a cubic cell structure and is fabricated by 3D printing technique. Firstly, the effects of contact and heat conditions on heat storage rate of PCM composite are investigated to provide theoretical guidance for the practical application of PCM composite in thermal energy storage (TES) system. Then the metal foam with a cubic cell structure is designed and fabricated by 3D printing. The experimental investigation is carried out to examine the melting evolution of PCM embedded in metal foam. Meanwhile, the pore-scale numerical method is also proposed and used to investigate heat transfer characteristics of PCM composite. It is found from the results that the embedding metal foam can short the total melting time of PCM. Considering the influence of morphology parameters of metal foam, the thermal behavior of metal foam with different porosities and pore densities is numerically studied. The last part of this thesis explores the application of metal foam in PCM based heat sink. The thermal response of heat sinks using PCM composite is obtained by the experimental test, including base temperature, temperature variation, operating time and enhancement ratio of operating time. Also, the effects of the porosity of metal foam and the power level of the heater on the thermal response of heat sink are investigated
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Waata, Christine Lylin. "Coupled neutronics, thermal-hydraulics analysis of a high-performance light-water reactor fuel assembly." Karlsruhe : FZKA, 2006. http://bibliothek.fzk.de/zb/berichte/FZKA7233.pdf.
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Waata, Christine Lylin. "Coupled neutronics, thermal hydraulics analysis of a high-performance light water reactor fuel assembly." Karlsruhe FZKA, 2005. http://bibliothek.fzk.de/zb/berichte/FZKA7233.pdf.
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Neff, Clayton. "Analysis of Printed Electronic Adhesion, Electrical, Mechanical, and Thermal Performance for Resilient Hybrid Electronics." Scholar Commons, 2018. https://scholarcommons.usf.edu/etd/7551.
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Today’s state of the art additive manufacturing (AM) systems have the ability to fabricate multi-material devices with novel capabilities that were previously constrained by traditional manufacturing. AM machines fuse or deposit material in an additive fashion only where necessary, thus unlocking advantages of mass customization, no part-specific tooling, near arbitrary geometric complexity, and reduced lead times and cost. The combination of conductive ink micro-dispensing AM process with hybrid manufacturing processes including: laser machining, CNC machining, and pick & place enables the fabrication of printed electronics. Printed electronics exploit the integration of AM with hybrid processes and allow embedded and/or conformal electronics systems to be fabricated, which overcomes previously limited multi-functionality, decreases the form factor, and enhances performance. However, AM processes are still emerging technologies and lack qualification and standardization, which limits widespread application, especially in harsh environments (i.e. defense and industrial sectors).
This dissertation explores three topics of electronics integration into AM that address the path toward qualification and standardization to evaluate the performance and repeatable fabrication of printed electronics for resilience when subjected to harsh environments. These topics include: (1) the effect of smoothing processes to improve the as-printed surface finish of AM components with mechanical and electrical characterization—which highlights the lack of qualification and standardization within AM printed electronics and paves the way for the remaining topics of the dissertation, (2) harsh environmental testing (i.e. mechanical shock, thermal cycling, die shear strength) and initiation of a foundation for qualification of printed electronic components to demonstrate survivability in harsh environments, and (3) the development of standardized methods to evaluate the adhesion of conductive inks while also analyzing the effect of surface treatments on the adhesive failure mode of conductive inks.
The first topic of this dissertation addresses the as-printed surface roughness from individually fusing lines in AM extrusion processes that create semi-continuous components. In this work, the impact of surface smoothing on mechanical properties and electrical performance was measured. For the mechanical study, surface roughness was decreased with vapor smoothing by 70% while maintaining dimensional accuracy and increasing the hermetic seal to overcome the inherent porosity. However, there was little impact on the mechanical properties. For the electrical study, a vapor smoothing and a thermal smoothing process reduced the surface roughness of the surfaces of extruded substrates by 90% and 80% while also reducing measured dissipative losses up to 24% and 40% at 7 GHz, respectively.
The second topic of this dissertation addresses the survivability of printed electronic components under harsh environmental conditions by adapting test methods and conducting preliminary evaluation of multi-material AM components for initializing qualification procedures. A few of the material sets show resilience to high G impacts up to 20,000 G’s and thermal cycling in extreme temperatures (-55 to 125ºC). It was also found that coefficient of thermal expansion matching is an important consideration for multi-material printed electronics and adhesion of the conductive ink is a prerequisite for antenna survivability in harsh environments.
The final topic of this dissertation addresses the development of semi-quantitative and quantitative measurements for standardizing adhesion testing of conductive inks while also evaluating the effect of surface treatments. Without standard adhesion measurements of conductive inks, comparisons between materials or references to application requirements cannot be determined and limit the adoption of printed electronics. The semi-quantitative method evolved from manual cross-hatch scratch testing by designing, printing, and testing a semi-automated tool, which was coined scratch adhesion tester (SAT). By cross-hatch scratch testing with a semi-automated device, the SAT bypasses the operator-to-operator variance and allows more repeatable and finer analysis/comparison across labs. Alternatively, single lap shear testing permits quantitative adhesion measurements by providing a numerical value of the nominal interfacial shear strength of a coating upon testing while also showing surface treatments can improve adhesion and alter the adhesive (i.e. the delamination) failure mode of conductive inks.
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Mayer, Jamie Lynn. "Design of a Rooftop Photovoltaic Array for the George C. Gordon Library at Worcester Polytechnic Institute: Structural, Thermal, and Performance Analysis." Digital WPI, 2010. https://digitalcommons.wpi.edu/etd-theses/368.
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In 2009, WPI formed a Presidential Task Force to engage the WPI community in sustainability research, thought, and action. One of the Presidential Task Force's specific objectives is to improve campus environmental performance, which includes energy conservation. Several new buildings such as the Bartlett Center and East Hall have utilized new green building techniques and materials. Older buildings at WPI which were built before new green building techniques and materials were developed can be equipped with photovoltaic systems to reduce the environmental impact and increase clean energy use. This thesis presents a rooftop photovoltaic array design for the George C. Gordon library at WPI which is expected to produce over 27,000 kWh and offset over 56,000 lbs of carbon dioxide emissions annually. The materials science and engineering of the photovoltaic system components are an important part of the design process. Structural and thermal modeling of photovoltaic components during the initial phase of array design is critical to the success of the PV system and maximizing the energy from the system. This thesis presents how differences in photovoltaic materials and mounting systems result in changes in lifetime and reliability. Using common wind, ice, snow and hail loads for the Worcester, MA area ANSYSâ„¢ structural simulations show that an attached mounting system is more structurally stable than a ballasted system. Using local weather data and thermal cycling, ANSYSâ„¢ thermal simulations show that silicon PV modules outperform other technologies at lower temperatures while cadmium telluride PV modules outperform other technologies at higher temperatures. It is recommended that WPI install poly-silicon PV modules, such as Evergreen Solar PV modules, to maximize power output.
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Yi, Ran. "Case study and parametric analysis of daylighting and thermal performance of atriums in subtropical climate." Thesis, University of Nottingham, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.490838.
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In the design of an atrium, good qualities of daylighting and thermal performance are expected. This thesis deals with a parametric study of geometric effect on the daylighting and thermal performance of three typical types of atriums, enclosed, linear and semi-enclosed, in the subtropical climatic area.
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Fricano, Joseph William. "Integrated fuel performance and thermal-hydraulic sub-channel models for analysis of sodium fast reactors." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/76919.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 191-197).
Sodium Fast Reactors (SFR) show promise as an effective way to produce clean safe nuclear power while properly managing the fuel cycle. Accurate computer modeling is an important step in the design and eventual licensing of SFRs. The objective of this work was to couple a model for metal fuel performance to a sub-channel analysis code to more precisely predict critical phenomena that could lead to pin failure for steady-state and transient scenarios. The fuel code that was used is the recently developed and benchmarked FEAST-METAL code. The sub-channel analysis code that was selected is COBRA-IV-I. This code was updated with current correlations for sodium for pressure drop, mixing, and heat transfer. The new code, COBRA-IV-I-MIT was then validated with experimental data from the Oak Ridge National Laboratory (ORNL) 19-Pin Bundle, the Toshiba 37-Pin Bundle, and the Westinghouse Advanced Reactors Division (WARD) 61-Pin Bundle. Important topics that were addressed for coupling the codes include the following. The importance of azimuthal effects in the fuel pin: FEAST only evaluates the fuel in two-dimensions, assuming azimuthal symmetry; however, coupling to COBRA produces an azimuthal temperature distribution. The acceptability of assuming a two-dimensional fuel rod with an average temperature was examined. Furthermore, how the fuel pin evolves over time affects the assembly geometry. How well a two-dimensional fuel rod allows for an accurate description of the changing assembly geometry was also considered. Related to this was how the evolution of the assembly geometry affects its thermal hydraulic behavior, which determined the exact form of coupling between the codes. Ultimately one-way coupling was selected with azimuthal temperature averaging around the fuel pin. The codes were coupled using a wrapper, the COBRA And FEAST Executer (CAFE), written in the Python programming language. Data from EBR-II was used to confirm and verify CAFE. It was found that the number of axial nodes used in FEAST can have a large effect on the result. Finally FEAST was used to parametrically study three different pin designs: driver fuel, radial blanket, and tight pitch breed and bum fuel. This study provides data for pin expected life in assembly design.
by Joseph William Fricano.
Ph.D.
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Afrin, Sabrina. "Thermal performance analysis of ETFE-foil panels and spaces enclosed with ETFE-foil cushion envelope." Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/43977/.
Full textAbstract:
Ethylene-tetra-fluoro-ethylene (ETFE) is a synthetic fluoropolymer. In the form of ETFE-foil it is applied in building envelopes in a single layer or more commonly, as inflatable cushions composed of multiple layers. ETFE-foils are widely used as a lightweight building envelope where high translucency, low structural weight, and complex shape is essential. However, limited research in the field of thermal performance of ETFE-foil panels and spaces enclosed with it instigated this study. Therefore, this study investigated (I) the thermal behaviour of ETFE-foil materials and the thermal performance of spaces enclosed with ETFE cushion roofs, (II) used commercially available thermal simulation software to predict the thermal performance of spaces enclosed with ETFE cushion and glass roofs and compared this with actual monitored behaviour (III) identified strategies to improve the thermal performance of spaces enclosed with ETFE cushion roofs in current and projected climate scenarios; and finally (IV) proposed design recommendations of ETFE-foil panels/cushions as a building fabric components. Material properties were investigated in laboratory based experiments. Further data were collected from two custom built outdoor test-rigs equipped with single-, two- and three-layer ETFE-foil panels. Environmental data were collected from two case study buildings to evaluate the thermal performance of the spaces enclosed with ETFE-foil cushion roofs. In addition, building simulation was conducted using EDSL TAS version 9.3.3.b to further analyse the indoor thermal environment and compare with monitored behaviour. The study identified variable thermal-optical properties of ETFE foils caused by various percentages of fritted area and its pigment density. The results also identified that the thermal environment of the test-rigs was affected by the variations in the surface temperatures of ETFE-foils and the temperature of air volume between multiple ETFE-foils (in case of two and three layer panels) by convective and radiative heat transfer mechanisms. The results from the case study buildings identified that during hot summer days, indoor air temperature and temperature stratification was higher in the atrium space enclosed with three-layer ETFE-foil cushions compared to the space enclosed with two-layer ETFE-foil cushion covered with rain mesh. However, both of the spaces were overheated during the summer of 2015. To develop an accurate simulation model for ETFE cushion roofs, a novel approach of modelling was developed. The simulation model was validated and calibrated by comparing with measured data from test-rigs and case study buildings. A comparison of predicted results of the spaces enclosed with a multi-layer ETFE-foil cushion roof and a glass roof showed that the extent of overheating was high when spaces were enclosed with glass roofs. Among two-and three-layer ETFE-foil cushion and glass roofs, two-layer ETFE-foil cushions with 75% fritting and rain mesh effectively reduced air temperature and cooling load during the peak summer period. The findings of this study will enable designers to select and develop design strategies for applying ETFE-foils in building envelopes on the basis of thermal and optical requirements. The study also suggested to change the view of current design practice that only focused on current conditions; such as the use of ETFE-foils may require more adaptive approach to mitigate overheating problems in projected climate.
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Seaman, Shane Thomas. "Material Related Effects on the Structural Thermal Optical Performance of a Thermally Tunable Narrowband Interferometric Spectral Filter." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/90799.
Full textAbstract:
High Spectral Resolution Lidar (HSRL) is a backscatter lidar technique that employs an optical/spectral filter to distinguish between particulate (Mie) and molecular (Rayleigh) backscattered light. By separating the two types of returns, higher accuracy measurements are possible that will enable improved climate models, air quality measurements, and climate forecasting. A spaceborne HSRL instrument can provide great impact in these areas by enabling near-continuous measurements across the Earth, however the optical filter technology has typically been too complex for reliable long-duration space flight due to the need for complicated and costly electro-optic feedback loops, extra alignment detectors, and additional laser sources. Furthermore, these complexities limit the filter from use in other applications. In this research, a high-performance, ultra-narrowband interferometric optical filter with a specific thermo-optical behavior has been designed and built. The interferometer has been designed such that it can be reliably adjusted/tuned by simply monitoring and adjusting the temperature. The greatly reduced operational complexity was made possible through high-accuracy thermal characterization of the interferometer materials, combined with detailed Structural-Thermal-Optical-Performance (STOP) modeling to capture the complicated interactions between the materials. The overall design process, fabrication procedures, and characterization of the optical filter are presented.Doctor of Philosophy
LiDAR (an acronym for Light Detection and Ranging) is a technology that can be used to measure properties of the atmosphere. It is similar to radar, but uses much smaller light waves rather than larger radio waves, enabling more detailed information to be obtained. High Spectral Resolution Lidar (HSRL) is a lidar technique that uses a high precision optical filter to distinguish between light that scatters from particulates (such as dust, smoke, or fog) and light that scatters from molecules (such as oxygen, nitrogen, or carbon dioxide) in the atmosphere. By separating the two types of backscattered light, higher accuracy measurements are possible that will enable improvements in climate models, air quality measurements, and climate forecasting. A spaceborne HSRL instrument can provide great impact in these areas by enabling near-continuous measurements across the Earth; however, the optical filter technology has typically been too complex for reliable long-duration spaceflight due to the need for complicated and expensive additional hardware. In this research, a high-performance HSRL optical filter that can be reliably operated by simply monitoring and adjusting the temperature has been designed, built, and tested. The greatly-reduced operational complexity has been made possible through a new process that enables more accurate prediction of the complicated interactions between the materials of the optical filter. This process is based on a combination of high-accuracy characterization of the materials and detailed structural-thermal-optical-performance (STOP) modeling. The overall design process, fabrication procedures, and characterization of the optical filter are presented.
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Chayopitak, Nattapon. "Performance Assessment and Design Optimization of Linear Synchronous Motors for Manufacturing Applications." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/16281.
Full textAbstract:
The major contributions of this thesis are categorized into three areas: (i) magnetic modeling, (ii) optimal performance assessment and (iii) multi-objective design methodology of the linear permanent-magnet (LPM) and linear variable reluctance (LVR) motors for manufacturing automation applications. The target application is to perform repetitive point-to-point positioning tasks on a continuous basis under temperature constraints. Through simplification, the constraint on temperature rise may be replaced by a constraint on average power dissipation, provided that the thermal resistance is constant and known.
The basic framework of analysis is first introduced for a class of idealized linear synchronous (LS) motors, where magnetic saturation and spatial harmonics are neglected, to provide clarity and insight. The physics-based force models for the LPM and LVR motors, including spatial harmonics and magnetic saturation as appropriate, are then developed. Due to magnetic linearity, the force model of the LPM motor is derived from the analytical solution of the Poisson Equation. A nonlinear magnetic circuit analysis model is developed for the LVR motor that includes both spatial harmonics and magnetic saturation. The accuracy of both force models are verified by finite element analysis.
Applying those force models, the optimal performance assessment of the LPM and LVR motors is explored using the mathematical framework discussed for the idealized LS motors. In particular, the relationship between travel time and travel distance is characterized in terms of average power dissipation. The performance assessment methodologies developed here may be applied to any motor technology used in manufacturing automation applications.
The multi-objective design optimization problem is then defined and software for its solution is developed using Monte-Carlo synthesis, the performance assessment tools and dominance-based sorting. Design results for the LPM and LVR motors are then presented. Future research is discussed as the conclusion of the thesis.
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Bornkessel, Thomas [Verfasser]. "Numerical Analysis of the Mechanical Performance and the Thermal Loads of Ground-Based Telescopes / Thomas Bornkessel." Aachen : Shaker, 2007. http://d-nb.info/1166508897/34.
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Li, Y. "Thermal performance analysis of a PCM combined solar chimney system for natural ventilation and heating/cooling." Thesis, Coventry University, 2013. http://curve.coventry.ac.uk/open/items/0bca9412-8b49-4d3c-84e5-453e315d4c6b/1.
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Solar chimney is an important passive design strategy to maximize solar gain to enhance buoyancy effect for achieving adequate air flow rate and a desired level of thermal comfort inside a building. Therefore, solar chimney has the potential advantages over mechanical ventilation systems in terms of energy requirement, economic and environmental benefits. The main aim of this project is to study the technical feasibility of a solar chimney incorporating latent heat storage (LHS) system for domestic heating and cooling applications. The research work carried out and reported in this thesis includes: the development of a detailed theoretical model to calculate the phase change material (PCM) mass for solar chimney under specific climatic condition, the development of a CFD model to optimise the channel depth and the inlet and outlet sizes for the solar chimney geometry, experimental and numerical investigations of the thermal performance of the proposed system using a prototype set-up, a parametric study on the proposed system to identify significant parameters that affect the system performance was carried out by using the verified numerical model. The numerical and experimental study showed that the numerical model has the ability to calculate the PCM mass for the proposed system for the given weather conditions. The optimum PCM should be selected on the basis of its melting temperature, rather than its other properties such as latent heat. The experimental work on the thermal performance of the proposed system has been carried out. The results indicated that the LHS based solar chimney is technically viable. The outlet air temperature and the air flow rate varied within a small range during phase change transition period which are important for a solar air heating system. A numerical model was developed to reproduce the experimental conditions in terms of closed mode and open mode. The model results were in a close agreement with the experimental results particularly the simulated results for the discharging process. With the verified model, a comprehensive parametric analysis intended to optimise the thermal performance of proposed the system was performed. The results analysed are quantified in terms of charging/discharging time of the PCM, temperature difference between outlet air and inlet air of the solar chimney, and mass flow rate of the chimney, which are the most important quantities of the proposed system.
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Yu, Chien Long, and 尤金龍. "The Performance Analysis of Thermal Modulesat Various Pitch of FinsThe Performance Analysis of Thermal Modulesat Various Pitch of FinsThe Performance Analysis of Thermal Modulesat Various Pitch of FinsThe Performance Analysis of Thermal Modules at V." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/20711558229471564304.
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碩士國立中興大學
機械工程學系
94
The purpose of this experiment is to discuss the performance of the RHE thermal module. We will define 4 models to discuss. Type A is fin pitch 1.8mm (43 pieces)、Type B is fin pitch 1.8mm (29 pieces) and 2.1mm (12 pieces)、Type C is fin pitch 1.8mm (29 pieces) and 2.5mm (10 pieces)、Type D is fin pitch 1.8mm (15 pieces) and 1.575mm (16 pieces) and 2.1mm (12 pieces). The parameters of CPU heat transfer are 60W、70W、80W、90W and 100W. According to the experiment’s results, we learned that the fin pitch is the critical factor that will influence thermal resistance and performance of the heat pipe. When the CPU is 60W, the regular arrangement of fins compared to irregular arrangement will result in 11~20% decrease of thermal resistance in the heat pipe. When the CPU is 100W, the thermal resistance of the heat pipe will decrease 22%~29%. When the CPU is between 60W~90W, the slope of the heat pipe temperature curve changes gradually, meaning the heat transfer is under the limit of heat transfer. When the CPU is over 90W, the slope of the heat pipe temperature curve increases faster, the cause of this increase is that the capillarity can not bear the heat transfer, which we call heat pipe “dry out”.
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Li, Meng-Zung, and 李孟哲. "Thermal Performance Analysis of A LEDProjector by Thermal Network Method." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/q4tkes.
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碩士國立臺灣海洋大學
機械與機電工程學系
106
Optical engine technology is getting more mature nowadays. The utilization of LED light sources has reached maximum. Since the conversion efficiency of the LED power goes higher, modern projectors are becoming more compact, compared with their big and heavy predecessors in the past. However, due to the strict limitations in the temperatures of LED sources, precision control of thermal and flow fields is essential, and it is also necessary to enhance heat dissipation rate in the projectors. In addition to compactness, shape plays another important role in attracting consumers. Ventholes though necessary, are usually not desirable. Therefore it is proposed to drill ventholes in the bottom face of the projector. Doing this, the design of the projector shape will be less limited and the products could be more attractive and popular. This study employs thermal resistance network method to develop the thermal model of the entire LED projector. Experiments associated with simulations are conducted in the first stage of work, where a commercial code ICEPAK is used. Experimental data are compared with the numerical results favorably. Cooling improvements and analyses of several representative cases are performed in the second stage of work. Thermal performance for each case is investigated by examining the total thermal resistance in the thermal resistance network. Numerical results dictate details of thermal and flow fields with emphasis on the impacts of locations of the inlet and the exits. Under one inlet condition, recirculation of waste heat appeared due to short distance between the inlet and the outlets. It is quite difficult to separate the inflow from the outflow within limited space in the projector. Therefore we chose to drill ventholes on the four sides of the bottom along with putting the fan in the center and removing the fan case. It was found that heated air flows out of the projector smoothly, and the high-temperature components cool down significantly along with some temperature increase in the low-temperature components. As such, the temperature field tends to be evenly distributed . Hence the difficulty in cooling due to setting ventholes on the bottom face has been resolved effectively.
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Chen, To-Ying, and 陳拓穎. "Dynamic Analysis for Heat Pipe Thermal Performance." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/53922983316491704495.
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碩士國立臺灣大學
機械工程學研究所
96
In recent years, the growth of chip performance and manufacturing technology results in high power dissipation and high operating temperature. Therefore, this research is focusing on setting up the experiment methodology and measurement procedure for heat pipe. By using the dynamic heating experiment and steady performance test to compare and analysis the heat pipe response. For performance estimation, using the result of dynamic temperature changes to come out with a new concept for dynamic performance. This concept could shorten the measuring time to 10-15 minutes and the dynamic and steady performance would be similar. In addition, this concept could save measuring time and simplify research applications. For heat pipe test, by experimental parameters to analysis heat pipe to make criterion and standard testing procedure. The main experimental parameters include the wick structure, fill ratio and different shape of heat pipe. In addition, by numerical analysis and measurements to find out the dynamic temperature response of heat pipe, and then set up experimental parameters. Under these conditions, we could reduce the time on testing parameters and analysis principles.
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Yang, Chia-an, and 楊嘉安. "Thermal performance analysis of large power system by thermal network method." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/05550437855496269341.
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碩士國立臺灣海洋大學
輪機工程學系
104
Study through thermal network analysis discuss large power system thermal performance. Study is divided into two phases. The first phase, discussion of a 450 HP vehicle power systems. Establishment of a CFD simulation model by the vehicle thermal performance experiments into idling state and dynamic operation. Idling equivalent model (Case1-0) error is less than 3.2%, the equivalent dynamic operating model (CaseM1-0) error is less than 11.8%. Case1-0 power system total thermal resistance is 1.982×10-2 ℃/W, and the average coefficient of thermal convection is 36.974 W/m2 ∙ K. CaseM1-0 power system total thermal resistance is 2.888×10-3 ℃ /W, and the average coefficient of thermal convection is 88.190 W/m2 ∙ K. Studies set up 15 different powertrain simulation model. Idling called Case1-1~Case3-4, and dynamic called CaseM1-1~CaseM3-4. Case 2-2 compare with Case 1-0, the total thermal resistance decreased 1.564%, and the average coefficient of thermal convection enhanced 40.366%. The cooling effect is best. CaseM3-2 compare with CaseM1-0, the total thermal resistance decreased 18.182%, and the average coefficient of thermal onvection enhanced 31.897%. The cooling effect is best. The second phase, discuss a 16154 HP marine power systems heat distribution.Through thermal network diagram, discuss the amount of heat transfer in analysis model, including engine, bearings, turbochargers and generator. The simulation results show, engine room power system total thermal resistance is 5.229×10-5 ℃/W, and the average coefficient of thermal convection is 6.234 W/m2 ∙ K. Study presents a thermal resistance network diagram, can reduce the diesel engine power system simulation model established time. It can be used as a power system total thermal resistance of the power system to assess the thermal performance better or worse.
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Sung, Hsien-Chao, and 宋賢超. "Energy Performance Analysis of A Photovoltaic Thermal System." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/79136704206098179038.
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碩士國立交通大學
平面顯示技術碩士學位學程
100
Earth's primary energy reserves are limited, and the world's oil depletion in the useful life of about 45 years, to reduce fossil fuels dependence, the world is actively developing renewable energy. IEA forecast the future of global primary energy demand annual average growth rate of about 1.6% in 2008 and 2030 shows that the human energy dependence are inextricably linked. However, solar year, about 23,000 TWy / year, this energy compared and other energy sources is far greater than human needs. Actively develop and put into application will solve the energy crisis and one of the best way to create human pinnacle of revolution. Nowaday the worldwide countries take the research on renewable energy,saving energy and environmental protection to take new resource from using technology of solar,which mainly applied on solar thermal energy and solar power. In solar electricity, solar cell absorb 400 ~ 1000nm solar spectrum and absorption of photons into electrical energy,which was not been transferred are one of important research objects on saving energy and environmental protection , its mainly application under the law of conservation of energy ,60% to 70% will be converted into thermal energy and raise the back side temperature on photovoltaic modules (PV module) , usually the temperature came up to 75 ° C even higher, the actual maximum power (Pmax) of the solar cells was less than Standard test Condition(STC) reduced around 18% to 25%(relative value). PV module power generation efficiency is affected by the characteristics of the temperature coefficient, under STC model the photovoltaic chip with packaged we found its temperature coefficient of its power generation efficiency, when it in crystalline photovoltaic modules the characteristics of the power generation efficiency decrease from 0.4 to 0.5% as the temperature increasese 1℃, then in Amorphous Si photovoltaic modules will be reduced by about 0.25%. In this study provide the concept of design applications of solar photovoltaic and collector efficiency (PV / T), heat the back of the photovoltaic modules with high thermal conductivity materials (such as copper or aluminum) collector, to achieve the purpose of cooling and thermal storage by the thermal conduction and convection. PV / T module is to enhance the effectiveness of the integrated solar applications, In addition, Taiwan's renewable energy incentive measures to aid the express solar water heater performance standards must be greater than or equal to 50%,in this research develop production of PV / T system energy efficiency (electricity & heat) is greater than 50% as an indicator.The key point in development PV / T modules is to ensure whether there is a good combination between the PV modules and solar collector, the collector pipe design (tube number, diameter, flow channel configuration, material) package adhesive material shallwith high thermal conductivity and excellent electrical insulation, insulation capacity also determine the collection efficiency. After that developed the three PV / T module, in which Type-1 PV / T module has the best performance,the collection efficiency (ηt) can came to 60.55% when the inlet and ambient temperature set as the same degree with the open circuit voltage state. In addition, if connected to the MPPT function electronic load state, when the inlet and ambient temperature is set the same degree, the collection efficiency (ηt) up to 47.45%, 13.25% power generation efficiency, the overall efficiency of 60.70%. In this study, also development Type-1 PV / T module for system performance testing,as results the thermal efficiency up to 42.49% (water temperature is upgrade to 10℃), the power generation efficiency to 13.05%, the comprehensive energy efficiency by 55.54%, it was reached the index of the experimental design.And also under TRNSYS, (Transient Cycle Systems, Dynamic Simulation Program) software simulation and designed PV / T system,compare the measured data and simulation data , TRNSYS simulation of the relative error is less than 10%.
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Chang, Nai-Yuan, and 張乃元. "Night Ventilation in Buildings: Indoor Thermal Performance Analysis." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/61070822031974783267.
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碩士國立臺灣大學
土木工程學研究所
97
In Taiwan, building design with an acceptable indoor thermal quality still lacks the awareness of energy consumption then has always depended heavily on high energy consumption techniques instead of energy-effective strategies. One of the energy-effective strategies referred to as night ventilation may be used to eliminate or decrease energy consumption. For this indoor thermal performance analysis, a prediction method has been developed through the model referred to as the spatial model. The relevant studies have been made but only in terms of a less general class of equations and very few attempts at deriving the solutions. This study proposes to go a little further into the details, which may be used to acquire the design guidelines for energy-conscious buildings.
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Huang, Chi-Yao, and 黃啟堯. "Thermal Performance Analysis of Vapor Chamber Heat Spreader." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/62739280238878489897.
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碩士淡江大學
機械與機電工程學系碩士班
96
The main purpose of present study is to investigate the effect of various wicks and filling rate on vapor chamber heat spreader thermal performance. The T5 type vapor chamber has a dimension of 90.83mm×87.63mm×3.9mm, and the sintered columns made of copper powder were used as the wick. The R0 has a dimension of 58mm×58mm×6mm, and the capillary wick design was consisted of radial rectangular grooved. Thermal performance of the vapor chambers were evaluated experimentally in a fan-heat sink CPU test apparatus with heating area of 31mm 31mm and 13.97mm 13.97mm. The clamping pressure between the vapor chamber and the heat sink was maintained at 12.5kgf during the test. After the evaluation, the T5 type vapor chamber with 35% D.I water filling rate showed the lowest evaporator-to-ambient resistance of 0.368℃/W, corresponding to a 14.62% decrease in thermal resistance at an input power of 122Watts, as compared to the system with copper plate. The results also showed a temperature difference lower than 1.69℃ on the entire condenser section, implied that the heat were spread uniformly to the heat sink. The R0 vapor chamber with 20% D.I water filling rate has the best performance as compared to the other filling rates. At the input power of 73Watts, the thermal resistance was 0.778℃/W, and it was still higher than copper plate about 0.446℃/W. We infer that larger channel width may cause poor capillarity.
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Ye, Nan-Zhe, and 葉哲男. "Thermal-Hydraulic Performance Analysis of Finned-Tube Heat Exchanger." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/52672649266360130858.
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碩士國立成功大學
機械工程學系
89
ABSTRACT This paper includes two parts. The first one is a three-dimensional numerical thermal-hydraulic study of the slit fin and tube heat exchanger. The second one is to measure the local heat transfer coefficient for the staggered and in-lined fin and tube heat exchangers using the infrared thermovision. In the numerical study of the slit finned-tube heat exchanger： Two different slit numbers (2 and 4) are investigated in detail for the Reynolds number ReH (based on the fin spacing and frontal velocity) ranging from 100 to 1100. Numerical results indicate that as the slit numbers are increased from 2 to 4, the average Nusselt number is increased from 6.9 to 27.8% compared to the plain fin surface. In infrared thermovision experimental part: The testes were performed in an open wind tunnel with infrared thermovision to measure the thermal field on the fin surface. The results indicated that for equal Reynolds number, the heat transfer coefficient for the staggered arrangement is 15% higher than that for in-lined arrangement.
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Liao, Wei-Chih, and 廖瑋智. "Thermal Performance Analysis on Optimun Computer Heat-Dissipation System." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/53338548415895686109.
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碩士國立成功大學
工程科學系專班
96
Because high-tech electric products bring forth the new through the old, they cause the higher and higher power as their computing speeds become faster and faster. The resulting high temperature is the major damage cause for electronic components. To face this problem, module factories has successfully developed a kind of module that could dissipate up to 160 W. However, it needs extra equipment and cost. In this study, the positions of CPU in a computer sever are changed, their effects on the heat dissipation are investigated and the optimal heat-dissipation cases are found. In this thesis, three primary subjects are studied: (1) the performance comparison of the heat dissipation for different CPU powers and positions in a closed system, (2) the performance comparison of the heat dissipation for different CPU powers and positions with different number and locations of electric fan, (3) the performance comparison of the heat dissipation for fixed CPU power and position with different air tunnels and different fan sizes, number and positions. From the experimental results, it can be found that the thermal resistance of the whole system decreases linearly with the increase of the CPU power. The best CPU position for heat dissipation is located at the bottom portion of a computer case, from which the heated air rises up to the upper portion of the case and goes out to the external environment due to the force convection caused by the electrical fan installed in the upper part of the case. In the installation of the air tunnel for the thermal module, if the air tunnel goes straight, the air in the tunnel has the smaller flow resistance and then takes away the heat from the CPU through the module more efficiently.
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Wu, Jhih-rong, and 吳志榮. "Thermal Performance Analysis of Cooling Water Loop in HVACSystems." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/41534063530431385037.
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碩士國立中山大學
機械與機電工程學系研究所
94
It is a common problem that the cooling water loop in an HVAC or refrigeration plant is suffering from scaling, corrosion, and bacteria attacks, especially in an open-loop designs. The reason is that, through the open water loop, various kinds of contaminants were trapped and migrated along the water flow, causing condenser scaling, which in turn, leading to its poor thermal performances. The experiment conducted in this study revealed that each condenser temperature increase of 1 ℃, accounts for a COP decrease of 2.4% to 2.8%.Serious scaling problem might even lead to system malfunction, and hazardous environmental problems. Conventionally, water-treatment in the condenser cooling water loop can be categorized into two parts, namely, the chemical and the physical methods. The chemical treatment is mainly performed by injecting chemicals, mostly acids, into the water loop so that it can circulate through the system and causing scales to peer off from the condenser tubes. In response to the cry of environmental protection, physical treatment has become increasingly important, which utilizes magnetic forces as the primary working principle. The main theme of this study is to validate this principle by full-scale experiments. The Zeta Rod system has been developed under the DLVO theory, with significant performance and is environmentally friendly. Experimental investigation has been performed in comparing the temperature differentials across a condenser, before and after the treatment. The result validated that it has increased from 3.9℃ to 4.2℃ and enhanced the thermal performances of the condenser accordingly.
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Chang, Nai-Chien, and 張乃建. "THERMAL PERFORMANCE ANALYSIS OF HEAT SINK FOR ELECTRONIC PACKAGE." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/16767088761039723223.
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碩士元智大學
機械工程學系
90
Both numerical and experimental approached have been used to investigate the thermal performance of heat sinks for electronic packages. The effects of operating parameters include inlet air velocity and temperature, size and power of heat source, different geometries and material properties of heat sinks, etc. on the thermal resistance of heat sink have been studied. The numerical results are also compared to the corresponding experimental results. The results show that the thermal resistance of heat sink will decrease with the increase of thermal conductivity of heat sink, size of heat sink, size of heat source and inlet air velocity. However, there is little effect of the power of heat source and inlet air temperature on the thermal resistance of heat sink. The highest temperature of the heat sink increases almost linearly with the increase of the power and the inlet air temperature. The results also show that the increase of the gap size in a straight plate fin will reduce the size of heat sink and therefore will increase its thermal resistance. It is also found that the increase of the height of heat sink may not improve the thermal resistance. Finally, the discrepancy between the numerical and experimental results may be due to the contact resistance between the heat source and the heat sink. The difference can be reduced by increase the pressure on the heat sink.
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TANG, CHUNG-YEN, and 唐崇嚴. "Performance Evaluation and Thermal Analysis of Hydrostatic Rotary Tables." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/83h2u8.
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Lo, Chien-Chi, and 羅千琪. "Experimental Analysis of Thermal Performance for Automotive Backlight Modules." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/wb6x76.
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碩士中原大學
機械工程研究所
107
Automotive display is not only used in the system of car navigation. The diversified applications go with the trend of internet of vehicle technology, autonomous vehicle, and automobile entertainment. The increasing demand also helps the growing of the automotive display market. The design specifications of automotive display are becoming rigorous, such as the sharpness presentation, color saturation, and panel downsizing solution. All of the above may lead to the overheating of the LED in the backlight module display. Therefore, how to design the backlight module to improve the heat dissipation efficiency is an important issue. The purpose of this study is to investigate the influence of materials of the backlight module on the thermal performance. Without affecting the structural strength and restriction of the appearance of the backlight modules, the different thickness of thermal tape and different materials of the metal frame were used. The modules were tested in the constant temperature and humidity machine to inspect the dissipation performance of each module.
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Yang, Wan-Erh, and 楊婉兒. "Thermal Performance Simulation Analysis of Military Computer Cooler Improvement." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/s69t2s.
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碩士國立臺北科技大學
能源與冷凍空調工程系
106
With the need for computing performance, market for military computers will increase significantly. However, in order to meet the various restrictions of military use and computers, the costs incurred in the R&D phase are considerable. Therefore, this paper will focus on the thermal design of military computer components provided by A company. Based on the original design of the aluminum chassis radiator as a basis for the study of this paper, the use of ANSYS Icepak simulation analysis software compared various heat dissipation schemes caused by the heat transfer performance changes in order to reduce the design cost. In conformity with its external specifications, this study explored the changes in various heat sink parameters and whether the addition of heat pipes had an effect on the overall thermal performance. According to the simulation results, the effect of the change in the thickness of the heatsink base and the parameters of the fins on the overall thermal performance is small. However, in the case of heat pipes added, the heatsink base material changes have little effect on the overall thermal performance. If a heat pipe is added to the radiator base, it is not necessary to add copper to increase its thermal performance, so as to avoid unnecessary cost and weight increase. In the case of forced convection, when the wind speed exceeds 2m/s, the effect on increasing the cooling effect is already very small. Therefore, when the wind speed reaches 2m/s, increasing the wind speed will only result in a waste of fan power, but it will not be able to significantly increase the cooling effect.
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RATAN, RAHUL. "THERMAL PERFORMANCE AND SIMULATION ANALYSIS OF SOLAR UPDRAFT TOWER." Thesis, 2019. http://dspace.dtu.ac.in:8080/jspui/handle/repository/17079.
Full textAbstract:
The world community is deeply worried about the rapid depletion of fossil fuels which are not only non-renewable but also emit greenhouse gases by the combustion of fossil fuels. There can be two ways to combat such situations, the first one is the replacement of fossil fuels with renewable sources of energy and the other one is to aware the community to use the resources wisely keeping in mind the sustainable use of resources for future generations. It is very aptly said by Mahatma Gandhi “The world has enough for everyone’s need, but not for anyone's greed”. Using energy efficiently can reduce the use of fossil fuels but using renewable sources of energy can completely eliminate its use. Solar energy, wind energy, hydro energy, geothermal energy, and biomass energy are considered as the major sources of renewable energy. Ocean energy, tidal energy, and wave energy are also considered as sources of renewable form of energy but much work has to be done to make these energies more affordable for the common people. Among all the forms of renewable energy, Solar energy is the one which is the most popularly known renewable form of energy and mostly all other forms of renewable energy have their origin directly or indirectly from solar energy (i.e. Sun). Therefore, the sun is the ultimate source of energy and is considered as a parent which gives birth to all other forms of energy and can power the future technologies. Solar Updraft Tower is one such technology which can power the needs of the future at minimum of the cost. A decent attempt to evaluate the performance of Solar Updraft Tower has been made by setting up an experimental model on rooftop of Mechanical Engineering Department, Delhi Technological University. The maximum collector efficiency was observes as 53.48% on Day-3 at 12:00 hrs while the minimum as 10.74% on Day-1 at 8:00 hrs. The maximum chimney efficiency of 0.67% was observed on Day-2 at 17:00 hrs while the minimum chimney efficiency was observed as 0.06% on Day-1 at 11:00 hrs. The maximum overall thermal efficiency of 9.98% was observed on Day-1 at 18:00 hrs while the minimum overall thermal efficiency was observed as 1.68% on Day-1 at 09:00 hrs.
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Bhatti, Jasleen. "Performance analysis of passive (Greenhouse) and active biogas heating system." Thesis, 2016. http://localhost:8080/xmlui/handle/12345678/7186.
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Chen, Sith-Ming, and 陳世明. "Three-dimensional thermal-hydraulic performance analysis of high performance louvered-finned heat exchanger." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/18504944826969591821.
Full textAbstract:
碩士國立成功大學
機械工程學系碩博士班
91
Fluid flow and heat transfer over louver finned-tube heat exchangers under the dry condition were studied numerically and experimentally in the first year. The effects of different geometrical factor, including louver angle (15°,20°,25°), fin pitch (6, 8, 12 fins/inch), and louver pitch (1mm, 0.75mm) are investigated in detail for different Reynolds numbers. Numerical results indicate that both average Nusselt number and pressure drop coefficient are increased as louver angle is increased for the equal louver pitch；while for equal louver angle, they are increased as the fin pitch is decreased, and increased as the louver pitch is decreased. A comparison of the numerical results with the available experimental data was also presented.
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Chi, Zhongzhe. "Thermal performance analysis and geometrical optimization of automotive brake rotors." Thesis, 2008. http://hdl.handle.net/10155/15.
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The heat dissipation and thermal performance of ventilated brake discs strongly
depends on the aerodynamic characteristics of the air flow through the rotor
passages. In this thesis, the thermal convection is analyzed using an analytical
method, and the velocity distribution, temperature contours and Nusselt number are
determined. Then numerical models for different rotors, pillar post rotors and vane
rotors are generated and numerical simulations are conducted to determine the
desired parameters. To analyze more realistic vane and pillar post rotor models,
commercial CFD software packages, Fluent and Gambit, are used to simulate the
heat flux rate, air flow rate, velocity distributions, temperature contours, and
pressure distributions inside the rotors. Furthermore, sensitivity studies have been
performed, to determine the effects of a different number of vanes or pillar posts,
inner and outer radii and various angles of vanes. To automate the tedious and
repetitive design process of the disc rotor, a design synthesis framework, iSIGHT,
is used to integrate the geometrical modeling using GAMBIT and numerical
simulations based on FLUENT. Through this integrated design synthesis process,
the disc rotor geometrical optimization is performed using design of experiment
studies.UOIT
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Parsons, James. "Performance Analysis of a Residential, Wind-Energy Thermal Storage System." 2011. http://hdl.handle.net/10222/14296.
Full textAbstract:
Wind-generated electricity is presented as a means to reduce anthropogenic greenhouse gas emissions and improve a region’s energy security. The variable nature of wind-electricity means that electricity providers face challenges when trying to incorporate it to meet the service requirements of on-demand electricity. In the residential sector in a northern country like Canada, the largest and most important energy demand is in the heating service.
In regions where there is a good wind regime, much of their energy needs could be met with wind. Newspaper headlines read that a given new wind farm installation will produce enough electricity to power thousands of homes. The important temporal factor is excluded from these calculations. The moment electricity from wind is available does not always correspond to when energy is required—an energy storage mechanism is needed to address this problem. This thesis addresses the question of the degree to which electricity produced from wind and employing thermal storage using commercially available electric hot water tanks can meet the demand for both space heating and domestic hot water in the residential sector. Maximizing usage of a renewable wind resource will result in both reduced greenhouse gas emissions and improved energy security for that region.
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Chiou, Nien-fong, and 邱能豐. "Thermal Hydraulic Performance Analysis Wavy Fin-and-Tub Heat Exchangers." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/61087082729716604681.
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碩士國立成功大學
機械工程學系
86
An experimental study was carried out to examine the effect of waffle height, including three different values oh waffle height: 1.18 mm, 1.32 mm and 1.58 mm, on the heat transfer and friction characteristics of typical fin-and-tube heat exchanger having wavy fins. A total of twenty seven samples of heat exchangers, including twenty one of them having wavy fins and the other four having plain fin configurations were tested. During the experiments, the water inlet temperature was held at 65.0±0.3℃, Frontal The test results indicate that the effect of waffle height on the heat transfer enchancement ratio, compare to plain-fin counterpart, the heat transfer coefficient and pressure drop are increased as the waffle height is increased. In addition, as the frontal velocity is increased, the effects of waffle height on heat transfer coefficient and pressure drop are more significant. The enchancement of heat transfer coefficient for the small waffle height Pd=1.18 mm relative to the plain fin surface is negligibl
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Liaw, Wen-Long, and 廖文龍. "The Opitamal Analysis of Thermal Performance in Crossflow Heat Exchanger." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/02736400851773476729.
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碩士大同工學院
機械工程研究所
81
The present study is investigate the effectiveness of direct transfer type, crossflow heat exchanger with neither fluid mixed due to the influnce of the aspect ratio, capacity ratio and conductance ratio. FAM (finite analytic method) is utilized in the two fluid flows and FDM(finite difference method)is utilized in the separator sheet to analyze the exchanger effectiveness.Numerical results show the comparison between he finite analytic method and finite difference method in the different boundary form of the insulatededge and the different node-point in the separator sheet. The present study is also to propose the useful modification in the finite analytic method. Next,the optimun aspect ratio is found with various parameters like as capacity rate and conductance ratio.
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Wen-Jer, Hsu, and 許文哲. "The analysis of thermal performance of electroosmotic flow in microchannels." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/53850495354646501678.
Full textAbstract:
博士國立中興大學
應用數學系所
97
This thesis contains three parts： 1.A numerical analysis is performed to explore the heat transfer characteristics of mixed electroosmotic and pressure-driven flows in a microtube with constant wall temperature. Thermally fully-developed flow with Joule heating is considered. The Joule heating is generated by imposed voltage gradient and can be regarded as volumetric heat source. The analysis combines energy equation with overall energy balance equation for a control element to generate a nondimensional governing equation. Of interest are the effects of the relative duct radius a (ratio of the duct radius to Debye length), the pressure gradient parameter P (ratio of pressure gradient to electroosmotic forces) and the Joule number S (ratio of heat generation due to Joule heating to heat transfer at the wall) on the temperature distribution and the local heat transfer rate. The results indicate that the Nusselt number increases with an increase in the relative duct radius and the Joule number or a decrease in the pressure gradient parameter. 2.The electrolyte fluid flow between outer rectangular microchannel and inner cylinder. An external electrical field is applied along the axial direction. The flow field is assumed hydrodynamically fully developed . Since the cross section of the geometry is irregular, it is necessary to transform the governing equations from physical domain to computational domain. The resulting equations are thus discretized by finite difference methods and evaluated by Gauss–Seidel technique. The electrical potential, velocity and temperature equations are solved subsequently. As the electroosmotic flow is commonly used for electrical cooling, the bottom boundary condition is set to constant heat flux . The calculation results show that an increase in the value of kR decreases the width of EDL, and thus the electrical potential drops dramatically after leaving the boundary. Also, when the Pe number increases, the temperature distribution profile is no longer parabolic, which is the case for most other situation. 3.The geometric condition of this part is as same as that for part 2, except that external electrical field is applied along the negative y direction. The flow field is solved by vorticity-stream function formulation. The governing equations are first transformed from physical domain to computational domain and discretized by finite difference methods and evaluated by Gauss–Seidel technique. The effects of parameters kR, Re, , on flow field are evaluated for the cases of various displacement of circular cylinder. The results show that these parameters have tremendous impact on both the number and position of recirculation zone.
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Hung, Juen-Ping, and 洪諄屏. "Performance Analysis of Vapor Chamber Thermal Modules With impinging jet." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/02352857493362002294.
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LI, ZHI-LIANG, and 李志良. "The optimal analysis of thermal performance in rotary heat exchanger." Thesis, 1992. http://ndltd.ncl.edu.tw/handle/17572933207272814680.
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