Dissertations / Theses on the topic 'Thermal management of electronics'
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1
Mital, Manu. "Integrated Thermal Management Strategies for Embedded Power Electronic Modules." Diss., Virginia Tech, 2006. http://hdl.handle.net/10919/30269.
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Almost all electronic devices require efficient conversion of electrical power from one form to another. Electrical power is used world wide at the rate of approximately 12 billion kW per hour. The Center for Power Electronics Systems at Virginia Tech was established with a vision to develop an integrated systems approach via integrated power electronic modules (IPEMs) to improve the reliability, cost-effectiveness, and performance of power electronics systems. IPEMs are multi-layered structures based on embedded power technology and offer the advantage of three-dimensional (3D) packaging of electronic components in a small and compact volume, replacing the traditional wire bonding technology. They have the potential to offer reduced time and effort associated with developing and manufacturing power processors. However, placing multiple heat generating chips in a small volume also makes thermal management more challenging. With the steady increase in the heat density of the electronic packages during the last few decades, thermal management is becoming a key enabling technology for the future growth of power electronics. The focus of this work is on using computational analysis tools and experimental techniques to assess fundamental and practical cooling limitations on IPEMs, developing both passive and active integrated thermal management strategies, and creating design guidelines for IPEMs based on both thermal and thermo-mechanical stress considerations. Specifically, a commercially available finite element package is used to create a 3D geometric layout of the electronic module. The baseline finite element numerical model is validated using bench-top wind tunnel experiments. The experimental setup is also employed to characterize the thermal behavior of chips in the multi-chip package and test the applicability of superposition methodology for temperature fields of chips within multi-chip modules. Using numerical models, both passive and active integrated thermal management strategies are investigated. The passive cooling strategies include advanced ceramic materials, copper trace thickness, and structural enhancements. Active cooling strategies include double-sided cooling using traditional heat sinks, and an extension of double-sided cooling concept using microchannels integrated with the module on both sides of embedded chips. The overall result of the work presented here is the better understanding of thermal issues and limitations with IPEM technology, and development of thermal design guidelines for cooling strategies that take into consideration both thermal and thermo-mechanical performance.Ph. D.
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Wu, Yupeng. "Thermal management of concentrator photovoltaics." Thesis, University of Warwick, 2009. http://wrap.warwick.ac.uk/3218/.
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Photovoltaic Concentrator systems, which increase the solar radiation intensity on the photovoltaic cells, may reduce the system cost, if the cost of the concentrator is less than the photovoltaic material displaced. An Asymmetric Compound Parabolic Photovoltaic Concentrator (ACPPVC) for building façade integration with a solar concentration ratio of 2.0 has been designed, fabricated and experimentally characterised. The truncated ACPPVC has acceptance half angles of 0° and 55° and an absorber width of 125mm. Phase Change Materials (PCM) have been integrated to the rear of the PV panel to moderate the temperature rise of the PV and maintain good solar-electrical conversion efficiency. The thermal behaviour of a Fresnel lens PV Concentrator (FPVC) has also been studied in this work. A two-dimensional ray trace technique has been used to predict the optical performance and the angular acceptance of the ACPPVC system. The predicted highest optical efficiency was 88.67% for the ACPPVC-55 system. Extensive indoor experimental characterisation of a number of PV systems was undertaken for a range of incident solar radiation intensities using a highly collimated solar simulator developed specifically for this project. Experimental results showed that the electrical output from the ACPPVC-55 was approximately 1.8 of that of a non-concentrating PV system with similar solar cells area. The electrical conversion efficiency for the ACPPVC-55 system was further increased, when RT27 PCM was incorporated to its rear.
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Tighe, Christopher James Frederick. "Thermal management of solid state power switches." Thesis, University of Nottingham, 2011. http://eprints.nottingham.ac.uk/12714/.
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The transient temperature of solid state power switches is investigated using thermal resistance network modelling and experimental testing. The ability of a heat sink mounted to the top of the device to reduce the transient temperature is assessed. Transient temperatures for heat pulses of up to 100ms are of most interest. The transient temperature distribution inside a typical stack-up of a solid state power switch is characterised. The thermal effects of adding a heat sink to the top of the device are then assessed. A variety of heat sink thicknesses and materials are evaluated. Components of the device stack-up are varied in order to assess their affect on the effectiveness of the heat sink in reducing the device temperature. Thermal networks are successfully applied to model the transient heat conduction inside the stack-ups. This modelling technique allowed a good understanding of the thermal behaviour inside the stack-up and heat sink during the transient period. The concept of using a heat sink to suppress the transient temperature was validated experimentally on two types of solid state power switch.
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Stinnett, William A. "Thermal Management of Power Electronic Building Blocks." Thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/31389.
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Development of Power Electronic Building Block (PEBB) modules, initiated through the Office of Naval Research (ONR), is a promising enabling technology which will promote future electrical power systems. Key in this development is the thermal design of a PEBB packaging scheme that will manage the module's high heat dissipation levels. As temperatures in electronics are closely associated with operating efficiency and failure rates, management of thermal loads is necessary to ensure proper and reliable device performance.
The current work investigates the thermal design requirements for a preliminary PEBB module developed by the NSF Center for Power Electronics Systems (CPES) at Virginia Tech. This module locates four primary heat-generating devices onto a copper bonded substrate in a multi-chip module format. The thermal impact of several design variables (including heat sink quality, substrate material, device spacing, and substrate and metallization thickness) are modeled within the multi-layer thermal analysis software TAMSä. Model results are in the form of metal layer surface temperatures that closely represent the device junction temperatures. Other design constraints such as electrical and material characteristics are also considered in the thermal design.
Design results indicate for the device heat dissipation levels that a low resistance heat sink coupled with a high conductivity substrate, such as aluminum nitride, are required for acceptable device junction temperatures. Substrate performance, in the form of a spreading resistance component, will be negatively affected by a lower quality heat sink. Both forced air and cold plate cooling methods were found acceptable; factors such as environment, cost and integration will determine which solution is most feasible. Maximum surface temperatures can be lowered somewhat through adjustment of device spacing. However, this reduction was small compared to the impact on parasitic capacitance. Additionally, there is some thermal benefit to thicker high-conductivity substrates, whereas lower conductivity substrates will increase the maximum surface temperature. Thicker copper layers will prove beneficial though this benefit is not as great for higher conductivity substrates.
Also discussed are the on-going and future development efforts that are expected to require thermal consideration. These consist of a top-level thermal bus for additional heat removal, the use of metal matrix composites and concepts for multi-module integration.Master of Science
5
McGlen, Ryan James. "Advanced thermal management techniques for high power electronics devices." Thesis, University of Newcastle Upon Tyne, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.533697.
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Jakaboski, Juan-Carlos. "Innovative Thermal Management of Electronics Used in Oil Well Logging." Thesis, Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/7255.
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The oil and gas industries use sophisticated logging tools during and after drilling. These logging tools employ internal electronics for sensing viscosity, pressure, temperature, and other important quantities. To protect the sensitive electronics, which typically have a maximum allowable temperature of 100 㬠they are shielded and insulated from the harsh external drilling environment. The insulation reduces the external heat input, but it also makes rejection of the heat generated within the electronics challenging. Electronic component failures promoted by elevated temperatures, and thermal stress, require a time consuming and expensive logging tool replacement process. Better thermal management of the electronics in logging tools promises to save oil and gas companies time and money.
This research focuses on this critical thermal management challenge. Specifically, this thesis describes the design, fabrication, and test of an innovative thermal management system capable of cooling commercial-off-the-shelf electronics for extended periods in harsh ambient temperatures exceeding 200 㮠Resistive heaters embedded in quad-flat-packages simulate the electronics used in oil well logging. A custom high temperature oven facilitates the evaluation of a full scale prototype of the thermal management system. We anticipate the prototype device will validate computer modeling efforts on which its design was based, and advance future designs of the thermal management system.
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Mahanta, Nayandeep Kumar. "Characterization and Analysis of Graphite Nanocomposites for Thermal Management of Electronics." Case Western Reserve University School of Graduate Studies / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=case1246546934.
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Raut, Rahul. "Thermal management of heat sensitive components in Pb-free assembly." Diss., Online access via UMI:, 2005.
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9
Pang, Ying-Feng. "Assessment of Thermal Behavior and Development of Thermal Design Guidelines for Integrated Power Electronics Modules." Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/26035.
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With the increase dependency on electricity to provide correct form of electricity for lightning, machines, and home and office appliances, the need for the introduction of high reliability power electronics in converting the raw form of electricity into efficient electricity for these applications is uprising. One of the most common failures in power electronics is temperature related failure such as overheating. To address the issue of overheating, thermal management becomes an important mission in the design of the power electronics to ensure the functional power electronics.
Different approaches are taken by academia and industry researchers to provide efficient power electronics. In particular, the Center for Power Electronics System (CPES) at Virginia Tech and four other universities presented the IPEM approach by introducing integrated power electronics modules (IPEM) as standardized units that will enable greater integration within power electronics systems and their end-use application. The IPEM approach increases the integration in the components that make up a power electronics system through novel a packaging technique known as Embedded Power technology.
While the thermal behavior of commonly used packages such as pin grid arrays (PGA), ball grid array (BGA), or quad flat pack (QFP) are well-studied, the influence of the Embedded Power packaging architecture on the overall thermal performance of the IPEMs is not well known. This motivates the presentation of this dissertation in developing an in-depth understanding on the thermal behavior of the Embedded Power modules. In addition, this dissertation outlines some general guidelines for the thermal modeling and thermal testing for the Embedded Power modules. Finally, this dissertation summarizes a few thermal design guidelines for the Embedded Power modules. Hence, this dissertation aims to present significant and generalized scientific findings for the Embedded Power packaging from the thermal perspective.
Both numerical and experimental approaches were used in the studies. Three-dimensional mathematical modeling and computational fluid dynamics (CFD) thermal analyses were performed using commercial numerical software, I-DEAS. Experiments were conducted to validate the numerical models, characterize the thermal performance of the Embedded Power modules, and investigate various cooling strategies for the Embedded Power modules. Validated thermal models were used for various thermal analyses including identifying potential thermal problems, recognizing critical thermal design parameters, and exploring different integrated cooling strategies.
This research quantifies various thermal design parameters such as the geometrical effect and the material properties on the thermal performance of the Embedded Power modules. These parameters include the chip-to-chip distance, the copper trace area, the polyimide thickness, and the ceramic materials. Since the Embedded Power technology utilizes metallization bonding as interconnection, specific design parameters such as the interconnect via holes pattern and size, the metallization thickness, as well as the metallization materials were also explored to achieve best results based on thermal and stress analyses.
With identified potential thermal problems and critical thermal design parameters, different integrated cooling strategies were studied. The concept of integrated cooling is to incorporate the cooling mechanisms into the structure of Embedded Power modules. The results showed that simple structural modifications to the current Embedded Power modules can reduce the maximum temperature of the module by as much as 24%. Further improvement can be achieved by employing double-sided cooling to the Embedded Power modules.
Based on the findings from the thermal analyses, general design guidelines were developed for future design of such Embedded Power modules. In addition, thermal modeling and testing guidelines for the Embedded Power modules were also outlined in this dissertation.Ph. D.
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Green, Craig Elkton. "Composite thermal capacitors for transient thermal management of multicore microprocessors." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/44772.
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While 3D stacked multi-processor technology offers the potential for significant computing advantages, these architectures also face the significant challenge of small, localized hotspots with very large heat fluxes due to the placement of asymmetric cores, heterogeneous devices and performance driven layouts. In this thesis, a new thermal management solution is introduced that seeks to maximize the performance of microprocessors with dynamically managed power profiles. To mitigate the non-uniformities in chip temperature profiles resulting from the dynamic power maps, solid-liquid phase change materials (PCMs) with an embedded heat spreader network are strategically positioned near localized hotspots, resulting in a large increase in the local thermal capacitance in these problematic areas.
Theoretical analysis shows that the increase in local thermal capacitance results in an almost twenty-fold increase in the time that a thermally constrained core can operate before a power gating or core migration event is required. Coupled to the PCMs are solid state coolers (SSCs) that serve as a means for fast regeneration of the PCMs during the cool down periods associated with throttling events. Using this combined PCM/SSC approach allows for devices that operate with the desirable combination of low throttling frequency and large overall core duty cycles, thus maximizing computational throughput. The impact of the thermophysical properties of the PCM on the device operating characteristics has been investigated from first principles in order to better inform the PCM selection or design process.
Complementary to the theoretical characterization of the proposed thermal solution, a prototype device called a "Composite Thermal Capacitor (CTC)" that monolithically integrates micro heaters, PCMs and a spreader matrix into a Si test chip was fabricated and tested to validate the efficacy of the concept. A prototype CTC was shown to increase allowable device operating times by over 7X and address heat fluxes of up to ~395 W/cm2. Various methods for regenerating the CTC have been investigated, including air, liquid, and solid state cooling, and operational duty cycles of over 60% have been demonstrated.
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Zampino, Marc A. "Embedded Heat Pipes in Cofired Ceramic Substrates for Enhanced Thermal Management of Electronics." FIU Digital Commons, 2001. http://digitalcommons.fiu.edu/etd/24.
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A novel and new thermal management technology for advanced ceramic microelectronic packages has been developed incorporating miniature heat pipes embedded in the ceramic substrate. The heat pipes use an axially grooved wick structure and water as the working fluid. Prototype substrate/heat pipe systems were fabricated using high temperature co-fired ceramic (alumina). The heat pipes were nominally 81 mm in length, 10 mm in width, and 4 mm in height, and were charged with approximately 50-80 mL of water. Platinum thick film heaters were fabricated on the surface of the substrate to simulate heat dissipating electronic components. Several thermocouples were affixed to the substrate to monitor temperature. One end of the substrate was affixed to a heat sink maintained at constant temperature. The prototypes were tested and shown to successful and reliably operate with thermal loads over 20 Watts, with thermal input from single and multiple sources along the surface of the substrate. Temperature distributions are discussed for the various configurations and the effective thermal resistance of the substrate/heat pipe system is calculated. Finite element analysis was used to support the experimental findings and better understand the sources of the system's thermal resistance.
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Yaddanapudi, Satvik Janardhan. "Spray Cooling with HFC-134a and HFO-1234yf for Thermal Management of Automotive Power Electronics." Thesis, University of North Texas, 2015. https://digital.library.unt.edu/ark:/67531/metadc822762/.
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This study aims to experimentally investigate the spray cooling characteristics for active two-phase cooling of automotive power electronics. Tests are conducted on a small-scale, closed loop spray cooling system featuring a pressure atomized spray nozzle. Two types of refrigerants, HFC-134a (R-134a) and HFO-1234yf, are selected as the working fluids. The test section (heater), made out of oxygen-free copper, has a 1-cm2 plain, smooth surface prepared following a consistent procedure, and would serve as a baseline case. Matching size thick film resistors, attached onto the copper heaters, generate heat and simulate high heat flux power electronics devices. The tests are conducted by controlling the heat flux in increasing steps, and recording the corresponding steady-state temperatures to obtain cooling curves. The working fluid is kept at room temperature level (22oC). Performance comparisons are made based on heat transfer coefficient (HTC) and critical heat flux (CHF) values. Effects of spray characteristics and liquid flow rates on the cooling performance are investigated with the selected coolants. Three types of commercially available nozzles that generate full-cone sprays with fine droplets are utilized in the tests. Effect of liquid flow rate is evaluated varying flow rates at 2, 3, 4 ml/s. The experimental results obtained from this study provide a framework for spray cooling performance with the current and next-generation refrigerants aimed for advanced thermal management of automotive power electronics.
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Madrid, Lozano Francesc. "Thermal Conductivity and Specific Heat Measurements for Power Electronics Packaging Materials. Effective Thermal Conductivity Steady State and Transient Thermal Parameter Identification Methods." Doctoral thesis, Universitat Autònoma de Barcelona, 2005. http://hdl.handle.net/10803/5348.
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Ravinuthala, Sridhar. "Thermal management in 3D packaging." Diss., Online access via UMI:, 2008.
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Thesis (M.S.)--State University of New York at Binghamton, Thomas J. Watson School of Engineering and Applied Science, Department of Mechanical Engineering, 2008.Includes bibliographical references.
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Madhura, Hande Handattu Lall Pradeep. "Prognostics health management and damage relationships of lead-free components in thermal cycling harsh environments." Auburn, Ala, 2008. http://hdl.handle.net/10415/8.
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Chacko, Salvio. "Numerical analysis of unsteady heat transfer for thermal management." Thesis, University of Warwick, 2012. http://wrap.warwick.ac.uk/54478/.
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In this study, thermal management of Lithium ion (Li-ion) battery pack used in electric vehicle (EV) is considered. Li-ion cells generate a significant amount of heat during normal operation. Previous study has clearly identified that temperature affects the efficiency, safety, reliability and lifespan of the Li-ion battery. Therefore, a battery thermal management system (BTMS) enabling effective temperature control is essential for safety and overall performance of the Li-ion battery. Two critical aspects are key to design of efficient BTMS: firstly being able to predict the heat generated from Li-ion cells, and secondly to predict how the generated heat is removed though the cooling plate of the BTMS. To predict the heat generated from the Li-ion cell, a time-dependent, thermal behavior of a Li-ion polymer cell has been modelled for electric vehicle drive cycles with a view to developing an effective battery thermal management system. The fully coupled, new three-dimensional transient electrothermal model has proposed and implemented based on a finite volume method. To support the numerical study, a high energy density Li-ion polymer pouch cell was tested in a climatic chamber for various electric load cycles consisting of a series of charge and discharge rates, and a good agreement was found between the model predictions and the experimental data. To predict the heat removed, a numerical study has been performed on a cooling plate of a indirect liquid cooled BTMS. The BTMS has a battery cooling plate with coolant flowing through rectangular serpentine channels. The temperature distribution as well as the pressure drop across the battery cooling plate were investigated. Particular emphasis was placed on the temperature uniformity on the cooling plate surface as the lifespan of a battery is severely affected by non-uniform temperature distribution. From the simulations, it is found that the aspect ratio and the curvature have a significant effect on the surface temperature uniformity, and that a compromise of the battery cooling plate design would be required between the temperature uniformity and the pressure drop penalty. Thermal management of batteries for high discharge applications, for instance, in hybrid electric vehicle, is more challenging and typically requires turbulent heat transfer. In turbulent heat transfer not only mean temperatures but also temperature fluctuations need to be predicted correctly. For this, a numerical turbulent heat transfer of a triple jet is considered. In this study, a large eddy simulation (LES) technique was applied to predict the unsteady heat transfer behavior of turbulent flow. It is found that LES predicted the correct amplitude of temperature fluctuations which was in good agreement with the available experimental data in terms of mean, RMS, skewness and kurtosis. RANS simulations with two turbulence models were also conducted along with LES. The RANS based turbulence models produced a very small amplitude of fluctuations, and failed to predict the correct magnitude of unsteady thermal fluctuations, highlighting its limitations in unsteady turbulent heat transfer simulations. Keywords: battery thermal management; lithium-ion polymer battery; electro thermal model; EV drive cycles; finite volume method, electric vehicle; BTMS; conjugate heat transfer; battery cooling plate; rectangular serpentine channel; laminar flow; triple jet; thermal striping; mixing; thermal fatigue; LES; RANS.
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Desai, Anand Hasmukh. "Thermal management of small scale electronic systems." Diss., Online access via UMI:, 2006.
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Davidson, Jonathan. "Advanced thermal modelling and management techniques to improve power density in next generation power electronics." Thesis, University of Sheffield, 2015. http://etheses.whiterose.ac.uk/8419/.
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This thesis sets out a series of new techniques to improve the thermal management of power electronics. The work is motivated by the increasing impetus to design smaller, more energy efficient electronic power systems for a range of applications, notably electric vehicles. Thermal management is an increasingly important tool which can facilitate improvements in power density through better monitoring and control of system temperatures. This thesis seeks to deliver improvements in implementing this strategy. A review of the state of the art in thermal management is reported, focussing on temperature measurement, thermal characterisation and system modelling techniques. In addition, novel techniques for arbitrary dissipation control and die temperature measurements in semiconductor devices are presented. A novel analysis of the limitations of low-order thermal models is also described. Improvements and applications of these techniques form the basis of this thesis. The pseudorandom binary sequence (PRBS) technique for system identification is applied throughout the thesis to characterise thermal systems. A mathematical analysis is provided, together with a novel technique to determine the minimum gain which can be identified by PRBS techniques in the presence of noise. A novel improvement to the PRBS technique for typically ten times more noise resilient measurements is then developed based on mathematical mixing of different frequency PRBS signals. In parallel, a novel technique is formulated to estimate the temperature throughout a multiple device system using digital IIR filters and PRBS thermal characterisation, which achieves errors of 3-5% when demonstrated practically. By combining these techniques, a comprehensive temperature estimation and control methodology is implemented for a multiple device system under active cooling. Finally, the expansion of the proposed methodologies to steady-state die temperature estimation is presented with comparable accuracy to surface temperature measurements, increasing the usefulness of the developed techniques in a practical setting.
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Kratz, Henrik. "Integrated Communications and Thermal Management Systems for Microsystem-based Spacecraft : A Multifunctional Microsystem Approach." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Universitetsbiblioteket [distributör], 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-6316.
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Hegab, Hisham El-Sayed. "Thermal management of electronic enclosures using heat pipes." Diss., Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/17962.
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Sewall, Evan Andrew. "Development of a Thermal Management Methodology for a Front-End DPS Power Supply." Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/35488.
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Thermal management is a rapidly growing field in power electronics today. As power supply systems are designed with higher power density levels, keeping component temperatures within suitable ranges of their maximum operating limits becomes an increasingly challenging task. This project focuses on thermal management at the system level, using a 1.2 kW front-end power converter as a subject for case study. The establishment of a methodology for using the computer code I-deas to computationally simulate the thermal performance of component temperatures within the system was the primary goal.
A series of four benchmarking studies was used to verify the computational predictions. The first test compares predictions of a real system with thermocouple measurements, and the second compares computational predictions with infrared camera and thermocouple measurements on a component mounted to a heat sink. The third experiment involves using flow visualization to verify the presence of vortices in the flow field, and the fourth is a comparison of computational temperature predictions of a DC heater in a controlled flow environment.
A radiation study using the Monte Carlo ray-trace method for radiation heat transfer resulted in the reduction of some component temperature predictions of significant components. This radiation study focused on an aspect of heat transfer that is often ignored in power electronics.
A component rearrangement study was performed to establish a set of guidelines for component placement in future electronic systems. This was done through the use of a test matrix in which the converter layout was varied a number of different ways in order to help determine thermal effects. Based on the options explored and the electrical constraints on the circuit, an optimum circuit layout was suggested for maximum thermal performance.
This project provides a foundation for the thermal management of power electronics at the system level. The use of I-deas as a computational modeling tool was explored, and comparison of the code with experimental measurements helped to explore the accuracy of I-deas as a system level thermal modeling tool.Master of Science
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Pang, Ying-Feng. "Integrated Thermal Design and Optimization Study for Active Integrated Power Electronic Modules (IPEMs)." Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/34965.
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Thermal management is one of many critical tasks in the design of power electronic systems. It has become increasingly important as a result of the introduction of high power density and integrated modules. It has also been realized that higher temperatures do affect reliability due to a variety of physical failure mechanisms that involve thermal stresses and material degradation. Therefore, it is important to consider temperature as design parameter in developing power electronic modules.
The NSF Center for Power Electronics System (CPES) at Virginia Tech previously developed a first generation (Gen-I) active Integrated Power Electronics Module (IPEM). This module represents CPES's approach to design a standard power electronic module with low labor and material costs and improved reliability compared to industrial Intelligent Power Modules (IPM). A preliminary Generation II (Gen-II.A) active IPEM was built using embedded power technology, which removes the wire bonds from the Gen-I IPEM. In this module, the three primary heat-generating devices are placed on a direct bonded copper substrate in a multi-chip module format.
The overall goal of this research effort was to optimize the thermal performance of this Gen-II.A IPEM. To achieve this goal, a detailed three-dimensional active IPEM was modeled using the thermal-fluid analysis program ESC in I-DEAS to study the thermal performance of the Gen-II.A IPEM. Several design variables including the ceramic material, the ceramic thickness, and the thickness of the heat spreader were modeled to optimize IPEM geometric design and to improve the thermal performance while reducing the footprint. Input variables such as power loss and interface material thicknesses were studied in a sensitivity and uncertainty analysis. Other design constraints such as electrical design and packaging technology were also considered in the thermal optimization of the design.
A new active IPEM design named Gen-II.C was achieved with reduced-size and improved thermal and electrical performance. The success of the new design will enable the replacement of discrete components in a front-end DC/DC converter by this standard module with the best thermal and electrical performance. Future improvements can be achieved by replacing the current silicon chip with a higher thermal-conductivity material, such as silicon carbide, as the power density increases, and by, exploring other possible cooling techniques.Master of Science
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Cook, Jason Todd. "Interconnect Thermal Management of High Power Packaged Electronic Architectures." Thesis, Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/5013.
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Packaged microelectronic technology provides an efficient means to connecting high performance chips to PCBs. As area array bump density increases, joule heating will play an important role in chip and interconnect reliability. Joule heating, in addition to chip heating can significantly reduce the clock speed and I/O while increasing noise, electromigration, and leakage power.
Direct cooling of the solder bumps is a new innovative approach to removing heat from packaged high heat dissipating chips. This could be used in conjunction with top surface mounted thermal management devices to maximize heat removal. The solder bumps leave a small gap between the packaged chip and PCB, which can be utilized for incorporating a thermal management scheme. Since space is very limited, fans and conventional heat sinks are not practical solutions. Jet impingement presents a unique solution for cooling solder bumps. It has been shown that micro jets can effectively cool the top surface of laptop computer processors. They can also be used to cool the solder bumps and bottom of the chip. Micro jets are easily implemented into the PCB without compromising the electrical leads powering the chip.
A prototype printed wiring board containing micro jets was built and a dummy plastic ball grid array packaged chip with a heating element embedded in it was attached on top. A mini compressor supplied the pressure and flow rates needed to push air through the micro jet holes. The pressure, flow rate, and temperatures were measured and analyzed. A numerical model was created based on the results of the experiments. Both the experiments and model show the effectiveness of interconnect cooling.
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McMillin, Timothy Walter. "Thermal management solutions for low volume complex electronic systems." College Park, Md.: University of Maryland, 2007. http://hdl.handle.net/1903/7368.
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Thesis (M.S.) -- University of Maryland, College Park, 2007.Thesis research directed by: Dept. of Mechanical Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Wilson, Scott E. "Investigation of Copper Foam Coldplates as a High Heat Flux Electronics Cooling Solution." Thesis, Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/6944.
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Compact heat exchangers such as porous foam coldplates have great potential as a high heat flux cooling solution for electronics due to their large surface area to volume ratio and tortuous coolant path. The focus of this work was the development of unit cell modeling techniques for predicting the performance of coldplates with porous foam in the coolant path.
Multiple computational fluid dynamics (CFD) models which predict porous foam coldplate pressure drop and heat transfer performance were constructed and compared to gain insight into how to best translate the foam microstructure into unit cell model geometry. Unit cell modeling in this study was realized by applying periodic boundary conditions to the coolant entrance and exit faces of a representative unit cell. A parametric study was also undertaken which evaluated dissimilar geometry translation recommendations from the literature. The use of an effective thermal conductivity for a representative orthogonal lattice of rectangular ligaments was compared to a porosity-matching technique of a similar lattice. Model accuracy was evaluated using experimental test data collected from a porous copper foam coldplate using deionized water as coolant. The compact heat exchanger testing facility which was designed and constructed for this investigation was shown to be capable of performing tests with coolant flow rates up to 300 mL/min and heat fluxes up to 290 W/cm2. The greatest technical challenge of the testing facility design proved to be the method of applying the heat flux across a 1 cm2 contact area. Based on the computational modeling results and experimental test data, porous foam modeling recommendations and porous foam coldplate design suggestions were generated.
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Burton, Ludovic Nicolas. "Multi-Scale Thermal Modeling Methodology for High Power-Electronic Cabinets." Thesis, Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/19808.
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Future generation of all-electric ships will be highly dependent on electric power, since every single system aboard such as the drive propulsion, the weapon system, the communication and navigation systems will be electrically powered. Power conversion modules (PCM) will be used to transform and distribute the power as desired in various zone within the ships. As power densities increase at both components and systems-levels, high-fidelity thermal models of those PCMs are indispensable to reach high performance and energy efficient designs. Efficient systems-level thermal management requires modeling and analysis of complex turbulent fluid flow and heat transfer processes across several decades of length scales.
In this thesis, a methodology for thermal modeling of complex PCM cabinets used in naval applications is offered. High fidelity computational fluid dynamics and heat transfer (CFD/HT) models are created in order to analyze the heat dissipation from the chip to the multi-cabinet level and optimize turbulent convection cooling inside the cabinet enclosure. Conventional CFD/HT modeling techniques for such complex and multi-scale systems are severely limited as a design or optimization tool. The large size of such models and the complex physics involved result in extremely slow processing time. A multi-scale approach has been developed to predict accurately the overall airflow conditions at the cabinet level as well as the airflow around components which dictates the chip temperature in details. Various models of different length scales are linked together by matching the boundary conditions. The advantage is that it allows high fidelity models at each length scale and more detailed simulations are obtained than what could have been accomplished with a single model methodology.
It was found that the power cabinets under the prescribed design parameters, experience operating point airflow rates that are much lower than the design requirements. The flow is unevenly distributed through the various bays. Approximately 90 % of the cold plenum inlet flow rate goes exclusively through Bay 1 and Bay 2. Re-circulation and reverse flow are observed in regions experiencing a lack of flow motion. As a result high temperature of the air flow and consequently high component temperatures are also experienced in the upper bays of the cabinet.
A proper orthogonal decomposition (POD) methodology has been performed to develop reduced-order compact models of the PCM cabinets. The reduced-order modeling approach based on POD reduces the numerical models containing 35 x 109 DOF down to less than 20 DOF, while still retaining a great accuracy. The reduced-order models developed yields prediction of the full-field 3-D cabinet within 30 seconds as opposed to the CFD/HT simulations that take more than 3 hours using a high power computer cluster. The reduced-order modeling methodology developed could be a useful tool to quickly and accurately characterize the thermal behavior of any electronics system and provides a good basis for thermal design and optimization purposes.
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Burzynski, Katherine Morris. "Printed Nanocomposite Heat Sinks for High-Power, Flexible Electronics." University of Dayton / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1619702252056433.
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Wang, Yong. "Microfuidic technology for integrated thermal management micromachined synthetic jet /." Available online, Georgia Institute of Technology, 2004:, 2003. http://etd.gatech.edu/theses/available/etd-04082004-180443/unrestricted/wang%5fyong%5f200312%5fphd.pdf.
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Ben, Aissia Hazem. "Model reduction for thermal management of high power electronic components for aerospace application." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSEI071.
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Dans la transition vers l’avion plus électrique, un des verrous technologiques est l'échauffement des composants électroniques ce qui affecte fortement leurs fiabilités et leurs durées de vie. Par conséquence, il est nécessaire de contrôler la température des cartes électroniques. Cette thèse a pour objectif de construire deux modèles thermiques réduits permettant de suivre en temps réel la température des composants électroniques. La différence entre le modèle réduit directe (MRD) et le modèle réduit inverse (MRI) réside dans les paramètres d'entrée et le formalisme mathématique de leurs constructions. Pour le MRD, les paramètres d'entrées sont les conditions aux limites. Ce modèle est élaboré sur deux étapes. La première étape consiste à construire une base réduite représentative de la solution en appliquant la POD (Proper Orthogonal Decomposition) sur une matrice snapshots. La matrice snapshots regroupe la solution du modèle éléments finis (MEF). La deuxième étape consiste à calculer les coordonnées d'une nouvelle solution en utilisant la projection de Galerkin du MEF sur la base réduite. Un MRD construit avec 10 modes diminue considérablement le temps de calcul et réalise une erreur absolue inférieure à 0,1 °C en dehors des variations brusques de puissance. Pour le MRI, les paramètres d'entrées sont les températures des capteurs implantés loin des composants électroniques. Ce modèle n'a pas besoin de connaitre les conditions aux limites comme le MRD. La première étape consiste à construire une base réduite qui couple les températures dans les composants électroniques et dans les capteurs de températures en utilisant la POD. La deuxième étape consiste à identifier les coordonnées des températures des composants électroniques à partir des mesures en utilisant un algorithme de minimisation. L'erreur du MRI d'ordre 3 ne dépasse pas 0,6 °C en dehors des variations brusques de puissanceIn the transition to more electric aircraft, one of the technological locks is the overheating of electronic components, which affects deeply their reliability and their lifetimes. Therefore, it is necessary to control the temperature of the electronic components. This thesis aims to build two reduced thermal models to monitor in real time the temperature of electronic components. The difference between the direct reduced model (DROM) and the inverse reduced order model (IROM) lies in the input parameters and the mathematical formalism of their constructions. For the DROM, the input parameters are the boundary conditions. This model is developed in two stages. The first step is to build a reduced base representative of the solution by applying POD (Proper Orthogonal Decomposition) on a snapshots matrix. The snapshots matrix is obtained from the finite element model (FEM) solution. The second step is to calculate the coordinates of a new solution using the Galerkin projection of the FEM on the reduced basis. A DROM built with 10 modes decreases drastically the computational time and the obtained absolute error is less than 0.1 °C except during sudden power variations. For the IROM, the input parameters are the temperature of the sensors placed far from the electronic components. This model does not need to know the boundary conditions as the DROM. The first step is to build a reduced base that couples the temperature or electronic components and the temperature of sensors using the POD. The second step is to identify the coordinates of the electronic components temperature from the measurements using a minimization algorithm. The error of the IROM of order 3 does not exceed 0.6 °C except during sudden power variations
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Wang, Yong. "Microfluidic technology for integrated thermal management: micromachined synthetic jet." Diss., Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/5438.
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Cao, Xiao. "Optimization of Bonding Geometry for a Planar Power Module to Minimize Thermal Impedance and Thermo-Mechanical Stress." Diss., Virginia Tech, 2011. http://hdl.handle.net/10919/77252.
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This study focuses on development a planar power module with low thermal impedance and thermo-mechanical stress for high density integration of power electronics systems. With the development semiconductor technology, the heat flux generated in power device keeps increasing. As a result, more and more stringent requirements were imposed on the thermal and reliability design of power electronics packaging.
In this dissertation, a boundary-dependent RC transient thermal model was developed to predict the peak transient temperature of semiconductor device in the power module. Compared to conventional RC thermal models, the RC values in the proposed model are functions of boundary conditions, geometries, and the material properties of the power module. Thus, the proposed model can provide more accurate prediction for the junction temperature of power devices under variable conditions. In addition, the transient thermal model can be extracted based on only steady-state thermal simulation, which significantly reduced the computing time.
To detect the peak transient temperature in a fully packaged power module, a method for thermal impedance measurement was proposed. In the proposed method, the gate-emitter voltage of an IGBT which is much more sensitive to the temperature change than the widely used forward voltage drop of a pn junction was monitored and used as temperature sensitive parameter. A completed test circuit was designed to measure the thermal impedance of the power module using the gate-emitter voltage. With the designed test set-up, in spite of the temperature dependency of the IGBT electrical characteristics, the power dissipation in the IGBT can be regulated to be constant by adjusting the gate voltage via feedback control during the heating phase. The developed measurement system was used to evaluate thermal performance and reliability of three different die-attach materials.
From the prediction of the proposed thermal model, it was found that the conventional single-sided power module with wirebond connection cannot achieve both good steady-state and transient thermal performance under high heat transfer coefficient conditions. As a result, a plate-bonded planar power module was designed to resolve the issue. The comparison of thermal performance for conventional power module and the plate-bonded power module shows that the plate-bonded power module has both better steady-state and transient thermal performance than the wirebonded power module. However, due to CTE mismatch between the copper plate and the silicon device, large thermo-mechanical stress is induced in the bonding layer of the power module. To reduce the stress in the plate-bonded power module, an improved structure called trenched copper plate structure was proposed. In the proposed structure, the large copper plate on top of the semiconductor can be partitioned into several smaller pieces that are connected together using a thin layer copper foil. The FEM simulation shows that, with the improved structure, the maximum von Mises stress and plastic strain in the solder layer were reduced by 18.7% and 67.8%, respectively. However, the thermal impedance of the power module increases with reduction of the stress. Therefore, the trade-off between these two factors was discussed. To verify better reliability brought by the trenched copper plate structure, twenty-four samples with three different copper plate structures were fabricated and thermally cycled from -40°C to 105°C. To detect the failure at the bonding layer, the curvature of these samples were measured using laser scanning before and after cycling. By monitoring the change of curvature, the degradation of bonding layer can be detected. Experimental results showed that the samples with different copper plate structure had similar curvature before thermal cycle. The curvatures of the samples with single copper plate decreased more than 80% after only 100 cycles. For the samples with 2 × 2 copper plate and the samples with 3 × 3 copper plate, the curvatures became 75.8% and 77.5% of the original values, respectively, indicating better reliability than the samples with single copper plate. The x-ray pictures of cross-sectioned samples confirmed that after 300 cycles, the bonding layer for the sample with single copper plate has many cracks and delaminations starting from the edge.Ph. D.
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Sahu, Vivek. "Hybrid solid-state/fluidic cooling for thermal management of electronic components." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/45817.
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A novel hybrid cooling scheme is proposed to remove non-uniform heat flux in real time from the microprocessor. It consists of a liquid cooled microchannel heat sink to remove the lower background heat flux and superlattice coolers to dissipate the high heat flux present at the hotspots. Superlattice coolers (SLC) are solid-state devices, which work on thermoelectric effect, and provide localized cooling for hotspots. SLCs offer some unique advantage over conventional cooling solutions. They are CMOS compatible and can be easily fabricated in any shape or size. They are more reliable as they don't contain any moving parts. They can remove high heat flux from localized regions and provide faster time response. Experimental devices are fabricated to characterize the steady-state, as well as transient performance, of the hybrid cooling scheme. Performance of the hybrid cooling scheme has been examined under various operating conditions. Effects of various geometric parameters have also been thoroughly studied. Heat flux in excess of 300 W/cm² has been successfully dissipated from localized hotspots. Maximum cooling at the hotspot is observed to be more than 6 K. Parasitic heat transfer to the superlattice cooler drastically affects its performance. Thermal resistance between ground electrode and heat sink, as well as thermal resistance between ground electrode and superlattice cooler, affect the parasitic heat transfer from to the superlattice cooler. Two different test devices are fabricated specifically to examine the effect of both thermal resistances. An electro-thermal model is developed to study the thermal coupling between two superlattice coolers. Thermal coupling significantly affects the performance of an array of superlattice coolers. Several operating parameters (activation current, location of ground electrode, choice of working fluid) affect thermal coupling between superlattice coolers, which has been computationally as well as experimentally studied. Transient response of the superlattice cooler has also been examined through experiments and computational modeling. Response time of the superlattice cooler has been reported to be less than 35 µs.
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Altalidi, Sulaiman Saleh. "Two-Phase Spray Cooling with HFC-134a and HFO-1234yf for Thermal Management of Automotive Power Electronics using Practical Enhanced Surfaces." Thesis, University of North Texas, 2017. https://digital.library.unt.edu/ark:/67531/metadc1011876/.
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The objective of this research was to investigate the performance of two-phase spray cooling with HFC-134a and HFO-1234yf refrigerants using practical enhanced heat transfer surfaces. Results of the study were expected to provide a quantitative spray cooling performance comparison with working fluids representing the current and next-generation mobile air conditioning refrigerants, and demonstrate the feasibility of this approach as an alternative active cooling technology for the thermal management of high heat flux power electronics (i.e., IGBTs) in electric-drive vehicles. Potential benefits of two-phase spray cooling include achieving more efficient and reliable operation, as well as compact and lightweight system design that would lead to cost reduction. The experimental work involved testing of four different enhanced boiling surfaces in comparison to a plain reference surface, using a commercial pressure-atomizing spray nozzle at a range of liquid flow rates for each refrigerant to determine the spray cooling performance with respect to heat transfer coefficient (HTC) and critical heat flux (CHF). The heater surfaces were prepared using dual-stage electroplating, brush coating, sanding, and particle blasting, all featuring "practical" room temperature processes that do not require specialized equipment. Based on the obtained results, HFC-134a provided a better heat transfer performance through higher HTC and CHF values compared to HFO-1234yf at all tested surfaces and flow rates. While majority of the tested surfaces provided comparable HTC and modestly higher CHF values compared to the reference surface, one of the enhanced surfaces offered significant heat transfer enhancement.
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Krist, Michael S. "The Design and Manufacture of a Light Emitting Diode Package for General Lighting." DigitalCommons@CalPoly, 2010. https://digitalcommons.calpoly.edu/theses/255.
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Lighting technologies have evolved over the years to become higher quality, more efficient sources of light. LEDs are poised to become the market standard for general lighting because they are the most power efficient form of lighting and do not contain hazardous materials. Unfortunately, LEDs pose unique problems because advanced thermal management is required to remove the high heat fluxes generated by such relatively small devices. These problems have already been overcome with complex packaging and exotic materials, but high costs are preventing this technology from displacing current lighting technologies.
The purpose of this study is to develop a low-cost LED lighting package capable of successfully managing heat. Several designs were created and analyzed based on cost, thermal performance, ease of manufacturing, and reliability. A unique design was created which meet these requirements. This design was eventually assembled as a prototype and initial testing was conducted. This thesis reviews the design process and eventual results of the LED package design.
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Tse, Ka Chun. "Carbon nanotube based advanced thin interface materials for thermal management /." View abstract or full-text, 2007. http://library.ust.hk/cgi/db/thesis.pl?CHEM%202007%20TSE.
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Baranyai, Roland. "Novel materials and methods for thermal management of GaN-based electronic devices." Thesis, University of Bristol, 2016. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.742981.
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Smarra, Devin. "Thermal Management and Packaging Techniques for High Performance Electrical Systems." University of Dayton / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1591122977788952.
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Jain, Sameer. "Research and application of a thermal management device (CoolCap TM) for electronic assemblies." Diss., Online access via UMI:, 2006.
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Minter, Dion Len. "Development of Strategies in Finding the Optimal Cooling of Systems of Integrated Circuits." Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/9961.
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The task of thermal management in electrical systems has never been simple and has only become more difficult in recent years as the power electronics industry pushes towards devices with higher power densities. At the Center for Power Electronic Systems (CPES), a new approach to power electronic design is being implemented with the Integrated Power Electronic Module (IPEM). It is believed that an IPEM-based design approach will significantly enhance the competitiveness of the U.S. electronics industry, revolutionize the power electronics industry, and overcome many of the technology limits in today's industry by driving down the cost of manufacturing and design turnaround time. But with increased component integration comes the increased risk of component failure due to overheating. This thesis addresses the issues associated with the thermal management of integrated power electronic devices.
Two studies are presented in this thesis. The focus of these studies is on the thermal design of a DC-DC front-end power converter developed at CPES with an IPEM-based approach. The first study investigates how the system would respond when the fan location and heat sink fin arrangement are varied in order to optimize the effects of conduction and forced-convection heat transfer to cool the system. The set-up of an experimental test is presented, and the results are compared to the thermal model. The second study presents an improved methodology for the thermal modeling of large-scale electrical systems and their many subsystems. A zoom-in/zoom-out approach is used to overcome the computational limitations associated with modeling large systems. The analysis performed in this paper was completed using I-DEAS©,, a three-dimensional finite element analysis (FEA) program which allows the thermal designer to simulate the affects of conduction and convection heat transfer in a forced-air cooling environment.Master of Science
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Sinha, Ashish. "An adsorption based cooling solution for electronics used in thermally harsh environments." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/37077.
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Growing need for application of electronics at temperatures beyond their rated limit, (usually > 150 °C) and the non availability of high temperature compatible electronics necessitates thermal management solutions that should be compact, scalable, reliable and be able to work in environments characterized by high temperature (150 -250 °C), mechanical shock and vibrations. In this backdrop the proposed research aims at realization of an adsorption cooling system for evaporator temperatures in the range of 140 °C-150 °C, and condenser temperature in the range of 160 °C-200 °C. Adsorption cooling systems have few moving parts (hence less maintenance issues), and the use of Thermo-Electric (TE) devices to regenerate heat of adsorption in between adsorbent beds enhances the compactness and efficiency of the overall 'ThermoElectric-Adsorption' (TEA) system. The work presented identifies the challenges involved and respective solutions for high temperature application. An experimental set up was fabricated to demonstrate system operation and mathematical models developed to benchmark experimental results. Also, it should be noted that TEA system comprises TE and adsorption chillers. A TE device can be a compact cooler in its own right. Hence a comparison of the performance of TEA and TE cooling systems has also been presented.
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Murthy, Sunil S. "Thin two-phase heat spreaders with boiling enhancement microstructures for thermal management of electronic systems." College Park, Md. : University of Maryland, 2004. http://hdl.handle.net/1903/179.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2004.Thesis research directed by: Mechanical Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Nie, Qihong. "Experimentally validated multiscale thermal modeling of electronic cabinets." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26492.
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Thesis (Ph.D)--Mechanical Engineering, Georgia Institute of Technology, 2009.Committee Chair: Joshi, Yogendra; Committee Member: Gallivan, Martha; Committee Member: Graham, Samuel; Committee Member: Yeung, Pui-Kuen; Committee Member: Zhang, Zhuomin. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Fältström, Love. "Graphite sheets and graphite gap pads used as thermal interface materials : A thermal and mechanical evaluation." Thesis, KTH, Tillämpad termodynamik och kylteknik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-147339.
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The electronic market is continually moving towards higher power densities. As a result, the demand on the cooling is increasing. Focus has to be put on the whole thermal management chain, from the component to be cooled to the ambient. Thermal interface materials are used to efficiently transfer heat between two mating surfaces or in some cases across larger gaps. There are several different thermal interface materials with various application areas, advantages and disadvantages. This study aimed to evaluate thermal and mechanical properties of graphite sheets and graphite gap pads. The work was done in cooperation with Ericsson AB. A test rig based on the ASTM D5470 standard was used to measure the thermal resistance and thermal conductivity of the materials at different pressures. It was found that several graphite sheets and gap pads performed better than the materials used in Ericsson’s products today. According to the tests, the thermal resistance could be reduced by about 50 % for the graphite sheets and 90 % for the graphite gap pads. That was also verified by placing the materials in a radio unit and comparing the results with a reference test. Both thermal values and mechanical values were better than for the reference materials. However, the long term reliability of graphite gap pads could be an issue and needs to be examined further.Elektronikbranschen rör sig mot högre elektriska effektertätheter, det vill säga högre effekt per volymenhet. Som en följd av detta ökar också efterfrågan på god kylning. Kylningen måste hanteras på alla nivåer, från komponenten som ska kylas, ända ut till omgivningen. Termiska interface material (TIM) används för att förbättra värmeöverföringen mellan två ytor i kontakt med varandra eller för att leda värmen över större gap. Det finns flera olika TIM med olika tillämpningsområden, fördelar och nackdelar. Denna studie gick ut på att utvärdera termiska och mekaniska egenskaper hos grafitfilmer och så kallade ”graphite gap pads” då de används som TIM. Projektet gjordes i sammarbete med Ericsson AB. En testuppställning baserat på ASTM D5470-standarden användes för att utvärdera värmeledningsförmågan och den termiska resistansen hos de olika materialen vid olika trycknivåer. Resultaten visade att flera grafitfilmer och ”gap pads” presterade bättre än materialen som används Ericssons produkter idag. Enligt testerna skulle den termiska resistansen kunna minskas med 50 % för grafitfilmerna och 90 % för ”gap padsen”. Materialens fördelaktiga egenskaper verifierades i en radioenhet där temperaturerna kunde sänkas i jämförelse med ett referenstest med standard-TIM. De nya materialen var mjukare än referensmaterialen och skulle därför inte orsaka några mekaniska problem vid användning. Den långsiktiga tillförlitligheten för grafitbaserade ”gap pads” måste dock undersökas vidare eftersom de elektriskt ledande materialen skulle kunna skapa kortslutningar på kretskorten.
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Alrasheed, Mohammed R. A. "A modified particle swarm optimization and its application in thermal management of an electronic cooling system." Thesis, University of British Columbia, 2011. http://hdl.handle.net/2429/37900.
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Particle Swarm Optimization (PSO) is an evolutionary computation technique, which has been inspired by the group behavior of animals such as schools of fish and flocks of birds. It has shown its effectiveness as an efficient, fast and simple method of optimization. The applicability of PSO in the design optimization of heat sinks is studied in this thesis. The results show that the PSO is an appropriate optimization tool for use in heat sink design.PSO has common problems that other evolutionary methods suffer from. For example, in some cases premature convergence can occur where particles tend to be trapped at local optima and not able to escape in seeking the global optimum. To overcome these problems, some modifications are suggested and evaluated in the present work. These modifications are found to improve the convergence rate and to enhance the robustness of the method. The specific modifications developed for PSO and evaluated in the thesis are: (1) Chaotic Acceleration Factor (2) Chaotic Inertia Factor (3) Global Best Mutation The performance of these modifications is tested through benchmarks problems, which are commonly found and used in the optimization literature. Detailed comparative analysis of the modifications to the classical PSO approach is made, which demonstrates the potential performance improvements. In particular, the modified PSO algorithms are applied to problems with nonlinear constraints. The non-stationary, multi-stage penalty method (PFM) is implemented to handle nonlinear constraints. Pressure vessel optimization and welded beam optimization are two common engineering problems that are used for testing the performance of optimization algorithms and are used here as benchmark testing examples. It is found that the modified PSO algorithms, as developed in this work, outperform many classical and evolutionary optimization algorithms in solving nonlinear constraint problems. The modified PSO algorithm is applied in heat sink design and detailed results are presented. The commercially available software package Ansys Icepak is used in the present work to solve the heat and flow equations in implementing the optimal design variables resulting from the modified PSO algorithms. The main contributions the work are summarized and suggestions are made for possible future work.
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Minichiello, Angela. "The development of a Heat Transfer Module (HTM) for the thermal management of sealed electronic enclosures." Thesis, Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/16358.
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Remella, Siva Rama Karthik. "Operation and Heuristic Design of Closed Loop Two-Phase Wicked Thermosyphons (CLTPWT) for Cooling Light Emitting Diodes (LEDs)." University of Cincinnati / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1522314073895889.
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Russell, Griffith B. "Local-and system-level thermal management of a single level integrated module (SLIM) using synthetic jet actuators." Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/18908.
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Wei, Xiaojin. "Stacked Microchannel Heat Sinks for Liquid Cooling of Microelectronics Devices." Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/4873.
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A stacked microchannel heat sink was developed to provide efficient cooling for microelectronics devices at a relatively low pressure drop while maintaining chip temperature uniformity. Microfabrication techniques were employed to fabricate the stacked microchannel structure, and experiments were conducted to study its thermal performance. A total thermal resistance of less than 0.1 K/W was demonstrated for both counter flow and parallel flow configurations. The effects of flow direction and interlayer flow rate ratio were investigated. It was found that for the low flow rate range the parallel flow arrangement results in a better overall thermal performance than the counter flow arrangement; whereas, for the large flow rate range, the total thermal resistances for both the counter flow and parallel flow configurations are indistinguishable. On the other hand, the counter flow arrangement provides better temperature uniformity for the entire flow rate range tested. The effects of localized heating on the overall thermal performance were examined by selectively applying electrical power to the heaters. Numerical simulations were conducted to study the conjugate heat transfer inside the stacked microchannels. Negative heat flux conditions were found near the outlets of the microchannels for the counter flow arrangement. This is particularly evident for small flow rates. The numerical results clearly explain why the total thermal resistance for counter flow arrangement is larger than that for the parallel flow at low flow rates.
In addition, laminar flow inside the microchannels were characterized using Micro-PIV techniques. Microchannels of different width were fabricated in silicon, the smallest channel measuring 34 mm in width. Measurements were conducted at various channel depths. Measured velocity profiles at these depths were found to be in reasonable agreement with laminar flow theory. Micro-PIV measurement found that the maximum velocity is shifted significantly towards the top of the microchannels due to the sidewall slope, a common issue faced with DRIE etching. Numerical simulations were conducted to investigate the effects of the sidewall slope on the flow and heat transfer. The results show that the effects of large sidewall slope on heat transfer are significant; whereas, the effects on pressure drop are not as pronounced.
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Zhang, Shuangfeng. "Wide Bandgap Semiconductor Components Integration in a PCB Substrate for the Development of a High Density Power Electronics Converter." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS398/document.
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Les nouveaux composants à semi-conducteur de type grand gap ont été développés pour des applications de conversion de puissance en raison de leurs hautes fréquences de commutation (de centaine kHz à quelques MHz) et pertes faibles. Afin de bien profiter ses avantages, la technologie des circuits imprimés (PCB) est intéressante pour une intégration à haute densité de puissance grâce à sa flexibilité et son faible coût. Cependant, à cause de la mauvaise conductivité thermique du matériau FR-4 utilisé pour le substrat PCB et la haute densité de puissance réalisée, il est primordial de trouver des solutions thermiques pour améliorer les performances thermiques de la structure de PCB. Dans cette thèse, trois solutions thermiques pour les structures de PCB ont été proposées, y compris des solutions avec des vias thermiques, de cuivre épais sur le substrat de PCB ainsi que des dispositifs de refroidissement thermoélectrique (TEC). Nos études sont basées sur la modélisation électrothermique et la méthode d’éléments finis en 3D. Tout d’abord, l’optimisation des paramètres des vias (diamètre, épaisseur de placage, surface formée par des vias, la distance entre des vias etc.) a été réalisée pour optimiser l’effet de refroidissement. Ensuite, on constate que les performances thermiques des structures de PCB peuvent être améliorées en utilisant cuivre épais sur le substrat de PCB. Cuivre épais augmente le flux thermique latéral dans la couche de cuivre. Les influences de l’épaisseur de cuivre (35 à 500 µm) ont été étudiées. Cette solution est facile à réaliser et peut être combinée à d’autres solutions de refroidissement. Enfin, le dispositif thermoélectrique comme les modules Peltier est une technologie de refroidissement local. Les influences des paramètres de Peltier (Propriétés du matériau thermoélectrique, nombre d’éléments Peltier, distance entre la source de chaleur et les dispositifs Peltier, etc.) ont été identifiées. Il est démontré que des modules Peltier ont l’application potentielle pour le développement d’intégration de PCB attendu que son active contrôle des températuresThe emerging wide bandgap (WBG) semiconductor devices have been developed for power conversion applications instead of silicon devices due to higher switching frequencies (from few 100 kHz to several MHz) and lower on-state losses resulting in a better efficiency. In order to take full advantage of the WBG components, PCB technology is attractive for high power density integration thanks to its flexibility and low cost. However, due to poor thermal conductivity of the commonly used material Flame Retardant-4 (FR4), efficient thermal solutions are becoming a challenging issue in integrated power boards based on PCB substrates. So it is of the first importance to seek technological means in order to improve the thermal performances. In this thesis, three main thermal management solutions for PCB structures have been investigated including thermal vias, thick copper thickness on the PCB substrate as well as thermoelectric cooling (TEC) devices. Our studies are based on the electro-thermal modeling and 3D finite element (FE) methods. Firstly, optimization of the thermal via parameters (via diameter, via plating thickness, via-cluster surface, via pattern, pitch distance between vias etc.) has been realized to improve their cooing performances. We presented and evaluated thermal performances of the PCB structures by analyzing the thermal resistance of the PCB substrate with different thermal vias. Secondly, it is found that thermal performances of the PCB structures can be enhanced by using thick copper thickness on top of the PCB substrate, which increases the lateral heat flux along the copper layer. Influences of the copper thickness (35 µm to 500 µm) has been discussed. This solution is easy to realize and can be combined with other cooling solutions. Thirdly, thermoelectric cooler like Peltier device is a solid-state cooling technology that can meet the local cooling requirements. Influences of Peltier parameters (Thermoelectric material properties, number of Peltier elements, distance between the heating source and the Peltier devices etc.) have been identified. All these analyses demonstrate the potential application of Peltier devices placed beside the heating source for PCB structures, which is a benefit for developing the embedding technology in such structures
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Ongkodjojo, Ong Andojo. "Electrohydrodynamic Microfabricated Ionic Wind Pumps for Electronics Cooling Applications." Case Western Reserve University School of Graduate Studies / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=case1354638816.
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