Heat removal technologies are among the most critical needs for three-dimensional (3D) stacking of high-performance microprocessors. This research reports a 3D integration platform that can support the heat removal requirements for 3D integrated circuits that contain high-performance microprocessors in the 3D stack. This work shows the use of wafer-level batch fabrication to develop advanced electrical and fluidic three-dimensional interconnect networks in a 3D stack. Fabrication results are shown for the integration of microchannels and electrical through-silicon vias (TSVs). A compact physical model is developed to determine the design trade-offs for microchannel heat sink and electrical TSV integration. An experimental thermal measurement test-bed for evaluating a 3D inter-layer liquid cooling platform is developed. Experimental thermal testing results for an air-cooled chip and a liquid-cooled chip are compared. Microchannel heat sink cooling shows a significant junction temperature and heat sink thermal resistance reduction compared to air-cooling. The on-chip integrated microchannel heat sink, which has a thermal resistance of 0.229 °C/W, enables cooling of >100W/cm² of each high-power density chip, while maintaining an average junction temperature of less than 50°C. Cooling liquid is circulated through the 3D stack (two layers) at flow rates of up to 100 ml/min. The ability to assemble chips with integrated electrical and fluidic I/Os and seal fluidic interconnections at each strata interface is demonstrated using three assembly and fluidic sealing techniques. Assembly results show the stacking of up to four chips that contain integrated electrical and fluidic I/O interconnects, with an electrical I/O density of ~1600/cm².

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.

Examensarbetets mål är att ta fram ett konceptförslag på en snabbkoppling på uppdrag av CEJN. Rapporten redovisar de metoder som använts för att nå slutligt resultat. Utvecklad snabbkoppling syftar till en marknad för vätskekylning i datacenter. CEJN önskar ligga i framkant på den expansiva marknaden, vilket kräver att tillverkningskostnaderna för befintlig aluminiumkoppling reduceras, bland annat genom materialbyte till plast. Företaget har idag ingen plasttillverkning i huset. Genereringsarbetet baseras på förstudie i form av litteraturstudier, konkurrensanalyser delvis genom demontering av befintliga produkter på marknaden, samt användartester. Prototyper har använts för test och utvärdering i flera stadier i processen. Snabbkopplingens yttre komponenter, som även visades vara de största kostnadsbärarna, utvecklades som separata delproblem så som låsmekanism, utformning av inre o-ringsspår och sammanfogning för att tillåta montering och säkerställa spillsäkerhet. Beslutsunderlag för slutliga konceptval baserades på kostnader, användande utifrån tillverkade prototyper samt utlåtanden från externa experter inom plasttillverkning, varpå konceptval kunde utföras tillsammans med uppdragsgivande företag. Dellösningarna anpassades i ett slutligt koncept som reducerar kostnader och samtidigt uppfyller krav gällande prestanda, utseende och användbarhet. Projektet med slutligt konceptförslag föreslås ligga till grund för vidareutveckling och tester för att säkerställa den högkvalitativa produkt CEJN eftersträvar. / The objective of the Bachelor thesis is to create a concept proposal in collaboration with CEJN. This report is presenting activities involved in the development process used to obtain the final result. Referring to the expansive market for liquid cooled data centres, CEJN aims to be in the leading edge with a new quick connection coupling. This demands reduction of production costs relative their existing aluminium coupling, partly by change of material to plastics. Outsourcing is relevant as the company does not produce plastic components at set. The idea generation phase has been based on a pre-study consisting of literature studies, analyses of competing products through demolition, and user tests. Prototypes have been used for testing and evaluation throughout the process. The outer components of the quick connection coupling proved to be among the costliest details. Locking mechanism, the formation of an inner slot for seals and the junction between nipple- or coupling body and back part to allow assembly and to ensure a non-drip application, have been developed separately. Decisions for final concept selection were made with the company of commission, with data regarding costs, usage interpreted from prototypes and verdicts from external experts within plastics production. Sub solutions mentioned, were combined into a final concept which reduces costs and fulfils demands regarding performance, appearance and usability. The material from the project is propositioned to form the basis for further development and testing to ensure high product quality representing CEJN.

<p>  </p> <p>As the power density of computing devices increases, advanced liquid cooling thermal solutions offer an attractive thermal management approach. In particular, the low thermal resistance offered by microchannel heat sinks used in liquid cooling systems may enable increased total heat dissipation within fixed component temperature limits. There has been extensive work on the design of microchannel heat sinks, with many recent efforts to explore novel geometries and emerging manufacturing techniques. Of particular interest is additive manufacturing to allow for designs having complex, non-traditional internal geometries and package structures that cannot be made through conventional means. Despite the potential benefits for design and construction, additive manufacturing introduces new geometric uncertainties that could affect device performance. Direct metal laser sintering methods suitable for printing metal heat sinks typically produce a high internal roughness and other shape deviations in the flow paths of the final part. This extreme relative roughness and potential tortuosity in fluid flow through additively manufactured microchannels could lead to significant deviations in pressure drop and heat transfer predicted with traditional correlations and models. This work seeks to characterize the effects of high relative roughness on the friction factor and Nusselt number in additively manufactured microchannels having a rectangular cross section. Straight microchannel samples of 500 µm, 750 µm, and 1000 µm channel heights, and aspect ratios from 1 to 10 were manufactured to identify the design dimensions that resulted in visibly open channels, albeit with deviations in cross-sectional shape for submillimeter channel sizes and high internal roughness. Heat sink test samples were then printed with an array of these microchannels connected in parallel by inlet and outlet headers. Using water as the working fluid, the pressure drop and heat transfer performance of these sample heat sinks were characterized to explore how their behavior deviated from conventional predictions assuming smooth-walled channels. Flow through these additively manufactured microchannels displayed higher pressure drops than predicted, as well as a flow rate dependence of the hydrodynamic and thermal performance. These observed deviations are explored as effects of the physical conditions inside the channel as a result of additive manufacturing. Severe constriction of the channel would account for the difference in magnitude between the experimental and predicted results, while the introduction of flow redevelopment could lead to a flow rate dependence.  By further understanding the impact of these artifacts and deviations, these factors can be accounted for in the design and modelling of more complex additively manufactured heat sinks. </p>

As a valuable asset in human augmentation and medical rehabilitation, exoskeletons have become a major area for research and development. They have shown themselves to be effective tools for training and rehabilitation of individuals suffering from limited mobility. However, most exoskeletons are not capable of balancing without the assistance of crutches from the user. Leveraging technology and techniques developed for force controlled humanoid robots, a project was undertaken to develop a fully self-balancing, compliant lower-body robotic exoskeleton. Due to their many beneficial features, series elastic actuators were utilized to power the joints on the exoskeleton. This thesis details the development of four linear series elastic actuators (LSEA) as part of this project. All 12-degrees of freedom will be powered by one of these four LSEA's. Actuator requirements were developed by examining human gait data and three robot-walking simulations. These four walking scenarios were synthesized into one set of power requirements for actuator development. Using these requirements, analytical models were developed to perform component trade studies and predict the performance of the actuator. These actuators utilize high-efficacy components, parallel electric motors, and liquid cooling to attain high power-to-weight ratios, while maintaining a small lightweight design. These analyses and trade studies have resulted in the design of a dual-motor liquid-cooled actuator capable of producing a peak force 8500N with a maximum travel speed of 0.267m/s, and three different single-motor actuators capable of producing forces up to 2450N continuously, with a maximum travel speeds up to 0.767m/s. / Master of Science

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.

No atual período de incertezas na geração e transmissão de energia elétrica no Brasil, a utilização dos sistemas de cogeração com uso de gás natural, tornou-se uma grande oportunidade econômica, estratégica e tecnológica, para as pequenas e médias empresas, considerando a extensão e perspectivas de expansão da rede de distribuição de gás natural. Uma empresa farmacêutica para se manter competitiva e reduzir o impacto dos custos indiretos em seus produtos, necessitava aumentar sua linha de injetáveis, produzindo no Brasil alguns medicamentos que até então eram importados de filiais em outros países e para que isto fosse possível, teria de investir na construção de novos laboratórios, compra de equipamentos, aumento de utilidades para sua fabricação como vapor de água para injetáveis, sistema de HVAC para salas limpas, o que levaria a um aumento de consumo de energia, vapor, água de refrigeração. Este investimento inviabilizaria a produção desta nova linha de produtos, pois tanto o custo do investimento em novas centrais de utilidades, quanto mais o custo desta geração e sua manutenção, decretariam um fim para a esta empreita. Neste trabalho, apresentou-se uma alternativa como solução para viabilizar esta instalação, trocando-se os chillers convencionais por um chiller de absorção, que alem de consumir pouca energia elétrica utilizando a troca térmica entre brometo de lítio e vapor para gerar água de resfriamento para o sistema de ar condicionado, o sistema proposto proporcionou um aumento de fornecimento de vapor não só para alimentar o sistema de HVAC como para a produção da fabrica, anexo a esta caldeira de recuperação é proposto a instalação de uma turbina á gás com condições suficientes de gerar energia elétrica para todo o site e ainda ter condições de negociar o excedente de energia para ser vendido para a concessionária. O resultado deste sistema proposto demonstrou uma excelente eficiência, frente ao sistema convencional, o que tecnicamente se apresentou como muito viável. / In the current period of uncertainty in the generation and transmission of electric energy in Brazil, the use of cogeneration systems using natural gas, has become a great economic opportunity, strategic and technology for small and medium enterprises, considering the extent and prospects for expansion of the distribution of natural gas. A pharmaceutical company to remain competitive and reduce the impact of indirect costs in their products, needed to increase its line of injectables, producing here in Brazil some drugs that were previously imported from subsidiaries in other countries and to make this possible, would invest in building new laboratories, purchase equipment, increase of utilities for its manufacture steam as water for injection, the HVAC system for clean rooms, leading to an increased consumption of energy, steam, cooling water. This investment would make impracticable the production of this new line of products, therefore not only the cost of the investment in new central offices of utilities, the more the cost of this generation of utilities and its maintenance, would decree an end for the this take over on a contract basis. In this work, presented as an alternative solution to enable this facility, exchanging conventional chillers for an absorption chiller, which besides consume little electricity using the heat exchange between lithium bromide to generate steam and cooling water for the air conditioning system, the proposed system provided an increased supply of steam to feed not only the HVAC system for the production of manufactures, attached to this recovery boiler is proposed to install a gas turbine with sufficient conditions generate electricity for the entire site and still be able to trade the surplus energy to be sold to the utility. The result of this proposed system showed an excellent efficiency, compared to the conventional system, which technically is presented as very viable.

This work deals with design of thermal source of panel shape for scientific biological application. Panel has adjustable surface temperature and thermal gradient. The first part of this work concern with design and numerical modeling of the thermal system, application of materials and arrangement of thermal and cooling devices – Peltier elements. Second part of this work is about construction of the panel and experimental measurement.

Batteries are promising sources of green and sustainable energy that have been widely used in various applications. Lithium-ion batteries (LIBs) have an important role in the energy storage sector due to its high specific energy and energy density relative to other rechargeable batteries. The main challenges for keeping the LIBs to work under safe conditions, and at high performance are strongly related to the battery thermal management. In this study, a critical literature review is first carried out to present the technology development status of the battery thermal management system (BTMS) based on air and liquid cooling for the application of battery energy storage systems (BESS). It was found that more attention has paid to the BTMS for electrical vehicle (EV) applications than for stationary BESS. Even though the active forced air cooling is the most commonly used method for stationary BESS, limited technical information is available. Liquid cooling has widely been used in EV applications with different system configurations and cooling patterns; nevertheless, the application for BESS is hard to find in literature.To ensure and analyze the performance of air and liquid cooling system, a battery and thermal model developed to be used for modeling of BTMS. The models are based on the car company BMW EV battery pack, which using Nickel Manganese Cobalt Oxide (NMC) prismatic lithium-ion cell. Both air and liquid cooling have been studied to evaluate the thermal performance of LIBs under the two cooling systems.According to the result, the air and liquid cooling are capable of maintaining BESS under safe operation conditions, but with considering some limits. The air-cooling is more suitable for low surrounding temperature or at low charging/discharge rate (C-rate), while liquid cooling enables BESS to operate at higher C-rates and higher surrounding temperatures. However, the requirement on the maximum temperature difference within a cell will limits the application of liquid cooling in some discharge cases at high C-rate. Finally, this work suggests that specific attention should be paid to the pack design. The design of the BMW pack is compact, which makes the air-cooling performance less efficient because of the air circulation inside the pack is low and liquid cooling is more suitable for this type of compact battery pack.

Batteries play an important role in a sustainable future. As the development for better andsmarter batteries continues, new areas of use emerge boosting its demand. Controlling thetemperature of a battery cell is a vital objective to ensure its longevity and performance. Bothcooling and heating methods can be applied to keep the temperature within a certain rangedepending on its need. This study will review the technical aspects of lithium-ion batteries,observe the different thermal management systems and cooling methods, and lastly examinethe required cooling flow needed for a battery cell to prevent its temperature from rising tocritical levels during its discharge. Using CFD ANSYS Fluent as a simulation tool, the resultsshow that different charging rates, in terms of C-rate, require different rates of mass flow tocontrol the temperature. Simulating the cell with natural convection, the cell peaks at hightemperatures even at lower C-rates, reaching up to 36,4°C and 48,8°C for 1C and 2C,respectively. Applying the cooling method with a flow rate of 0,0077kg/s reduces thetemperature significantly, resulting in temperatures of 26,95°C and 31,27°C for 1C and 2C,respectively.