Littérature scientifique sur le sujet « Free-surface thermal storage »
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Articles de revues sur le sujet "Free-surface thermal storage"
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Skarphagen, Helge, David Banks, Bjørn S. Frengstad et Harald Gether. « Design Considerations for Borehole Thermal Energy Storage (BTES) : A Review with Emphasis on Convective Heat Transfer ». Geofluids 2019 (22 avril 2019) : 1–26. http://dx.doi.org/10.1155/2019/4961781.
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Borehole thermal energy storage (BTES) exploits the high volumetric heat capacity of rock-forming minerals and pore water to store large quantities of heat (or cold) on a seasonal basis in the geological environment. The BTES is a volume of rock or sediment accessed via an array of borehole heat exchangers (BHE). Even well-designed BTES arrays will lose a significant quantity of heat to the adjacent and subjacent rocks/sediments and to the surface; both theoretical calculations and empirical observations suggest that seasonal thermal recovery factors in excess of 50% are difficult to obtain. Storage efficiency may be dramatically reduced in cases where (i) natural groundwater advection through the BTES removes stored heat, (ii) extensive free convection cells (thermosiphons) are allowed to form, and (iii) poor BTES design results in a high surface area/volume ratio of the array shape, allowing high conductive heat losses. The most efficient array shape will typically be a cylinder with similar dimensions of diameter and depth, preferably with an insulated top surface. Despite the potential for moderate thermal recovery, the sheer volume of thermal storage that the natural geological environment offers can still make BTES a very attractive strategy for seasonal thermal energy storage within a “smart” district heat network, especially when coupled with more efficient surficial engineered dynamic thermal energy stores (DTES).
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Gamisch, Sebastian, Stefan Gschwander et Stefan J. Rupitsch. « Numerical and Experimental Investigation of Wire Cloth Heat Exchanger for Latent Heat Storages ». Energies 14, no 22 (11 novembre 2021) : 7542. http://dx.doi.org/10.3390/en14227542.
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Latent thermal energy storages (LTES) offer a high storage density within a narrow temperature range. Due to the typically low thermal conductivity of the applied phase change materials (PCM), the power of the storages is limited. To increase the power, an efficient heat exchanger with a large heat transfer surface and a higher thermal conductivity is needed. In this article, planar wire cloth heat exchangers are investigated to obtain these properties. They investigated the first time for LTES. Therefore, we developed a finite element method (FEM) model of the heat exchanger and validated it against the experimental characterization of a prototype LTES. As PCM, the commercially available paraffin RT35HC is used. The performance of the wire cloth is compared to tube bundle heat exchanger by a parametric study. The tube diameter, tube distance, wire diameter and heat exchanger distance were varied. In addition, aluminum and stainless steel were investigated as materials for the heat exchanger. In total, 654 variants were simulated. Compared to tube bundle heat exchanger with equal tube arrangement, the wire cloth can increase the mean thermal power by a factor of 4.20 but can also reduce the storage capacity by a minimum factor of 0.85. A Pareto frontier analysis shows that for a free arrangement of parallel tubes, the tube bundle and wire cloth heat exchanger reach similar performance and storage capacities.
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Svoboda, Roman, Nicola Koutná, Daniela Košťálová, Miloš Krbal et Alena Komersová. « Indomethacin : Effect of Diffusionless Crystal Growth on Thermal Stability during Long-Term Storage ». Molecules 28, no 4 (6 février 2023) : 1568. http://dx.doi.org/10.3390/molecules28041568.
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Differential scanning calorimetry and Raman spectroscopy were used to study the nonisothermal and isothermal crystallization behavior of amorphous indomethacin powders (with particle sizes ranging from 50 to 1000 µm) and their dependence on long-term storage conditions, either 0–100 days stored freely at laboratory ambient temperatures and humidity or placed in a desiccator at 10 °C. Whereas the γ-form polymorph always dominated, the accelerated formation of the α-form was observed in situations of heightened mobility (higher temperature and heating rate), increased amounts of mechanically induced defects, and prolonged free-surface nucleation. A complex crystallization behavior with two separated crystal growth modes (originating from either the mechanical defects or the free surface) was identified both isothermally and nonisothermally. The diffusionless glass–crystal (GC) crystal growth was found to proceed during the long-term storage at 10 °C and zero humidity, at the rate of ~100 µm of the γ-form surface crystalline layer being formed in 100 days. Storage at the laboratory temperature (still below the glass transition temperature) and humidity led only to a negligible/nondetectable GC growth for the fine indomethacin powders (particle size below ~150 µm), indicating a marked suppression of GC growth by the high density of mechanical defects under these conditions. The freely stored bulk material with no mechanical damage and a smooth surface exhibited zero traces of GC growth (as confirmed by microscopy) after >150 days of storage. The accuracy of the kinetic predictions of the indomethacin crystallization behavior was rather poor due to the combined influences of the mechanical defects, competing nucleation, and crystal growth processes of the two polymorphic phases as well as the GC growth complex dependence on the storage conditions within the vicinity of the glass transition temperature. Performing paired isothermal and nonisothermal kinetic measurements is thus highly recommended in macroscopic crystallization studies of drugs with similarly complicated crystal growth behaviors.
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Raj, Sarath, Bibin K.S. et Reby Roy K.E. « OpenFOAM Analysis on the Comparison of Safety Requirements Provided for Water-Air and LOX-He Storage Systems ». International Journal of Occupational Safety and Health 14, no 4 (1 octobre 2024) : 436–48. http://dx.doi.org/10.3126/ijosh.v14i4.57612.
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Introduction: In storage vessels filled with cryogenic liquids thermal destratification can be effectively done by the continuous supply of bubble movements. Therefore, the pressure builds up subsequent blasting of such containers can be avoided and cryogenic storage vessels can be used safely. The Volume of Fluid (VOF) approach is utilized in the current computational analysis to examine the safety precautions, dynamics of bubble creation, and subsequent collapse of the free liquid surface in both vertically and horizontally aligned rectangular containers. Methods: In the present work, using the Volume of Fluid (VOF) method, numerically investigated the sloshing behavior within a rectangular container with a 15% free air space with double gas inlets. Results: The impact of inlet gas velocity on sloshing rate due to bubbling is investigated numerically. Also, comparative studies are carried out to investigate the variations of bubble diameter, detachment time, and bubble detachment frequencies considering water-air and LOX-He systems. The mixing behaviors in LOX due to helium bubble formation under different inlet gas velocities were also numerically investigated. The numerical results show that the average deformation index increased by 23.83% when the water-air system was replaced with the LOX-He system. Hence, it can be understood that for the storage vessels filled with cryogenic liquids more safety precautions have to be considered to avoid thermal stratification. The safety precautions include increasing the gas flow rate and including more number gas flow inlets. Conclusion: The present analysis concludes that under a given condition the free liquid surface deformation is more for the case where storage vessels filled with LOX-He. Hence, it can be understood that for the storage vessels filled with cryogenic liquids more safety precautions have to be considered to avoid thermal stratification. The safety precautions include increasing the gas flow rate and including more number gas flow inlets.
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Raj, Sarath, K. S. Bibin, K. E. Reby Roy, Bibin Prasad et J. S. Jayakumar. « Analysis of free liquid surface deformation and thermal destratification in liquid storage tanks using OpenFOAM ». Journal of Energy Storage 102 (novembre 2024) : 113848. http://dx.doi.org/10.1016/j.est.2024.113848.
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Serebrov, A. P., E. A. Kolomensky, A. K. Fomin, I. A. Krasnoschekova, A. V. Vassiljev, D. M. Prudnikov, I. V. Shoka et al. « New Neutron Lifetime Measurements with the Big Gravitational Trap and Review of Neutron Lifetime Data ». KnE Energy 3, no 1 (9 avril 2018) : 121. http://dx.doi.org/10.18502/ken.v3i1.1733.
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Neutron lifetime is one of the most important physical constants which determines parameters of the weak interaction and predictions of primordial nucleosynthesis theory. In our experiment we measure the storage time of UCN in the material trap coated with a hydrogen-free fluorine-containing polymer (Fomblin grease UT-18). The stability of this coating to multiple thermal cycles between 80 K and 300 K was tested. The achieved storage time is only 1.5% less than free neutron lifetime. Using additional surface, which can be plunged into the trap to change the collision frequency of UCN with walls, we calculate free neutron lifetime by extrapolation to zero collision frequency. The result of the measurements with this new experimental setup is
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Shen, Zhenzhen, Kun Fang, Mike Hamilton, R. Wayne Johnson, Erica Snipes et Michael Bozack. « Lead-free Solder Attach for 200°C Applications ». Additional Conferences (Device Packaging, HiTEC, HiTEN, and CICMT) 2013, HITEN (1 janvier 2013) : 000260–67. http://dx.doi.org/10.4071/hiten-wa18.
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Conventional SAC lead-free solders have a melting point of 217°C to 227°C, limiting their suitability for applications at 200°C. AgBiXTM solder has potential for 200°C applications because of its ~260°C solidus temperature. BiAgX paste has been used to assemble SiC test die to ceramic substrates with direct bond copper (DBC), reactive brazed CuMo, thick film Au, thick film PtAu, thick film PdAg and thick film Ag. Surface mount chip resistors have also been attached to thick film metallized substrates. The assembly process and initial shear strength test results are presented. Assemblies have also been subjected to thermal testing: thermal cycling (−55°C to +195°C) and high temperature (200°C) storage. The shear strength of these assemblies after thermal testing are presented and compared to initial results.
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Pan, Chao, Ran Ding, Li Dong, Jing Wang et Yucai Hu. « Horseradish Peroxidase-Carrying Electrospun Nonwoven Fabrics for the Treatment of o-Methoxyphenol ». Journal of Nanomaterials 2015 (2015) : 1–6. http://dx.doi.org/10.1155/2015/616879.
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The carboxyl-functionalized polystyrene (poly(styrene-co-methacrylic acid), PSMAA) nanofibers with average diameters of 250 ± 20 nm was prepared by electrospinning. PSMAA nanofibrous membrane were employed for immobilization of horseradish peroxidase (HRP) enzyme on the fibrous surface by a chemical method. The parameters about immobilizing HRP on the PSMAA nanofibers were studied and the influence on the activity of the HRP is discussed. This study showed that soap-free emulsion method is an ideal technology to modify the polystyrene surface and ultimately achieve enzyme immobilization on electrospun PSMAA nanofibers surfaces. Compared with free HRP, the acid-base stability, thermal stability, and storage stability of HRP were increased after the immobilization. The immobilized HRP maintained about 60% of its initial activity during a 20-day storage period. However, the free HRP maintained only 40% of its initial activity. The removal percentages of o-methoxyphenol (OMP) reached 80.2% after 120 min for immobilized HRP. These results suggest that the proposed scheme for immobilization of HRP has potential in industrial applications for the treatment of phenolic wastewater.
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Menchaca-Campos, Carmina, Gonzalo Martínez-Barrera, Héctor López-Valdivia, Héctor Carrasco et Alberto Álvarez-Castillo. « Post-irradiation effects on gamma-irradiated nylon 6,12 fibers ». Journal of Polymer Engineering 33, no 9 (1 décembre 2013) : 823–28. http://dx.doi.org/10.1515/polyeng-2013-0070.
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Abstract Post-irradiation effects on nylon 6,12 crystalline fibers gamma-irradiated 6 years previously (6YI) were studied, including thermal stability and morphology; their relationship with storage time was also studied. The results of these studies were compared with those obtained for non-irradiated (NI) and namely freshly irradiated (FI) crystalline fibers. The results include analyses like thermogravimetric analysis (TGA), differential thermal analysis (DTA), scanning electron microscopy (SEM) and optical images for (6YI and FI) both kinds of nylon 6,12 fibers. The results showed that the most prominent effect is related to the reaction progress. The chain scission and/or crosslinking mechanisms, as well as the free radicals, allow proceeding with the reaction, and consequently, changes on the properties of the FI samples. The melting point, degree of crystallinity, degradation temperature and morphology prove that additional chemical reactions and surface modifications keep occurring in the fibers long after the irradiation process has ended. With storage time, the surface becomes rougher, the color turns yellowish, the melting point diminishes and the degree of crystallinity increases.
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Atta, Ayman, Mahmood Abdullah, Hamad Al-Lohedan et Nermen Mohamed. « Coating Sand with New Hydrophobic and Superhydrophobic Silica/Paraffin Wax Nanocapsules for Desert Water Storage and Transportation ». Coatings 9, no 2 (17 février 2019) : 124. http://dx.doi.org/10.3390/coatings9020124.
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Paraffin wax emulsions have gained immense attention as a cheap, environment-friendly, and aroma-free material for preparing superhydrophobic coatings. In this work, paraffin wax (PWs) capsules consisting of hydrophobic silica nanoparticles were used for coating desert sand. Different types of the hydrophobic silica nanoparticles, modified with new oleylamino- and oleylamide silane precursors, were prepared in the presence and absence of paraffin waxes. The particle sizes, surface charges, thermal stability, surface morphologies, and wetting characteristics of these nanoparticles were investigated. The combination of these superhydrophobic silica nanoparticles and desert sand, showed excellent water repellency; stable water droplets remained on the sand surface, without any wetting or permeation. Furthermore, the mixing of the superhydrophobic sand with untreated sand (mixing ratio 1:10 wt %), with a thickness of 2 cm, sustained a great water-holding capacity with a water column height of 35 cm. The good thermal stability of the PWs capsules containing hydrophobic silica nanoparticles, along with their good water-holding capacity, make them potential candidates for developing superhydrophobic sand for desert water storage and transportation.
Thèses sur le sujet "Free-surface thermal storage"
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Striegel, Lucas. « Etudes numérique et expérimentale de récupérateurs d’eaux pluviales enterrés géothermiques pour le rafraîchissement passif des bâtiments ». Electronic Thesis or Diss., Strasbourg, 2024. http://www.theses.fr/2024STRAD060.
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Face au changement climatique, caractérisé notamment par des périodes caniculaires plus longues et intenses, mais aussi par une disponibilité irrégulière de la ressource en eau, il est nécessaire d’apporter des solutions sobres en consommations énergétiques pour renforcer la résilience des bâtiments. Les cuves de récupération d’eaux de pluie enterrées sont des systèmes de plus en plus exploités qui permettent la gestion et le stockage de l’eau. En y immergeant un échangeur de chaleur, il est possible de profiter de l’effet géothermique de l’eau et du sol environnant pour rafraîchir les bâtiments de façon passive. Ce travail de recherche vise à étudier les performances et la faisabilité de ces systèmes hybrides. Un modèle numérique a été développé et validé grâce aux données recueillies par l’instrumentation de prototypes à l’échelle 1 pendant près de trois ans. L’exploitation du modèle a mis en évidence les facteurs influents du système. Des règles de prédimensionnement pour évaluer la quantité d’énergie potentiellement récupérable ont ensuite été établies. Le modèle du système a ensuite été intégré dans un outil de simulation énergétique du bâtiment pour évaluer les gains en termes de confort des occupantsIn the face of climate change, characterized by longer and more intense heatwaves, as well as irregular availability of water resources, it is essential to provide energy-efficient solutions to strengthen the resilience of buildings. Underground rainwater tanks are increasingly being exploited as systems for managing and storing water. By immersing a heat exchanger in the tank, it is possible to harness the geothermal effect of the water and surrounding soil to passively cool buildings. This research aims to study the performance and feasibility of these hybrid systems. A numerical model was developed and validated using data collected from the monitoring of full-scale prototypes over a period of nearly three years. The model was used to highlight the key factors influencing the system. The model was used to identify the factors influencing the system. Presizing rules were then established to assess the amount of energy that could potentially be recovered. The system model was then integrated into a building energy simulation tool to assess the gains in terms of occupant comfort
Chapitres de livres sur le sujet "Free-surface thermal storage"
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Chen, Cheng-Meng. « Free-Standing Graphene Film with High Conductivity by Thermal Reduction of Self-assembled Graphene Oxide Film ». Dans Surface Chemistry and Macroscopic Assembly of Graphene for Application in Energy Storage, 97–110. Berlin, Heidelberg : Springer Berlin Heidelberg, 2015. http://dx.doi.org/10.1007/978-3-662-48676-4_4.
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Vishnu, S. B., et Biju T. Kuzhiveli. « Effect of Roughness Elements on the Evolution of Thermal Stratification in a Cryogenic Propellant Tank ». Dans Low-Temperature Technologies [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.98404.
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The cryogenic propulsion era started with the use of liquid rockets. These rocket engines use propellants in liquid form with reasonably high density, allowing reduced tank size with a high mass ratio. Cryogenic engines are designed for liquid fuels that have to be held in liquid form at cryogenic temperature and gas at normal temperatures. Since propellants are stored at their boiling temperature or subcooled condition, minimal heat infiltration itself causes thermal stratification and self-pressurization. Due to stratification, the state of propellant inside the tank varies, and it is essential to keep the propellant properties in a predefined state for restarting the cryogenic engine after the coast phase. The propellant’s condition at the inlet of the propellant feed system or turbo pump must fall within a narrow range. If the inlet temperature is above the cavitation value, cavitation will likely to happen to result in the probable destruction of the flight vehicle. The present work aims to find an effective method to reduce the stratification phenomenon in a cryogenic storage tank. From previous studies, it is observed that the shape of the inner wall surface of the storage tank plays an essential role in the development of the stratified layer. A CFD model is established to predict the rate of self-pressurization in a liquid hydrogen container. The Volume of Fluid (VOF) method is used to predict the liquid–vapor interface movement, and the Lee phase change model is adopted for evaporation and condensation calculations. A detailed study has been conducted on a cylindrical storage tank with an iso grid and rib structure. The development of the stratified layer in the presence of iso grid and ribs are entirely different. The buoyancy-driven free convection flow over iso grid structure result in velocity and temperature profile that differs significantly from a smooth wall case. The thermal boundary layer was always more significant for iso grid type obstruction, and these obstructions induces streamline deflection and recirculation zones, which enhances heat transfer to bulk liquid. A larger self-pressurization rate is observed for tanks with an iso grid structure. The presence of ribs results in the reduction of upward buoyancy flow near the tank surface, whereas streamline deflection and recirculation zones were also perceptible. As the number of ribs increases, it nullifies the effect of the formation of recirculation zones. Finally, a maximum reduction of 32.89% in the self-pressurization rate is achieved with the incorporation of the rib structure in the tank wall.
Actes de conférences sur le sujet "Free-surface thermal storage"
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Fukui, Shigehisa, Yuki Okamura et Hiroshige Matsuoka. « Thermo-Molecular Gas-Film Lubrication (t-MGL) Analysis in the Free Molecular Limit : Effects of Accommodation Coefficients on Static Pressure ». Dans ASME 2016 Conference on Information Storage and Processing Systems. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/isps2016-9594.
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In order to examine thermo-molecular gas film lubrication (t-MGL) characteristics with a temperature distribution at the disk or slider surfaces for spacings of several nanometers, the free molecular t-MGL equation considering temperature distributions and accommodation coefficients at the boundaries was established. By analyzing pressure generated by the wedge effect (slider inclination) and the thermal wedge effect (boundary temperature distributions), it is revealed that, as the accommodation coefficient, α0, of the running disk or the boundary surface with a temperature distribution decreases, that is, as the ratio of specular reflection increases, the pressure generation decreases, whereas as the accommodation coefficient, α1, of the stationary slider surface or the boundary surface without a temperature distribution decreases, the pressure generation increases.
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Maccarini, Alessandro, Michael Wetter, Davide Varesano, Martin Bloemendal, Alireza Afshari et Angelo Zarrella. « Low-order aquifer thermal energy storage model for geothermal system simulation ». Dans 15th International Modelica Conference 2023, Aachen, October 9-11. Linköping University Electronic Press, 2023. http://dx.doi.org/10.3384/ecp204389.
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This paper presents a low order aquifer thermal energy storage (ATES) model for simulation of combined subsurface and above-surface energy systems. The model is included in the Modelica IBPSA Library, which is a free open-source library with basic models for building and district energy and control systems. The model uses a lumped-component method, in which the transient conductive-convective heat and mass transfer equation is radially discretized. To verify the accuracy of the model, we present an intra-model comparison from a simulation test suite. Results show that the Modelica ATES model is in good agreement, with a normalized mean bias error for yearly variation of aquifer temperatures of 1.6×10−2 and 9×10−5 at 1 m and 10 m distance from the well.
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Avanessian, Tadeh, et Gisuk Hwang. « Adsorption-Based Thermal Rectifier ». Dans ASME 2015 13th International Conference on Nanochannels, Microchannels, and Minichannels collocated with the ASME 2015 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/icnmm2015-48508.
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Controlling thermal energy transport (thermal diode) for the desired direction is crucial to improve the efficiency of thermal energy transport, conversion, and storage systems as electrical diodes significantly impact on modern electronic systems. The degree of thermal rectification is measured by the difference between the heat transfer rate in favorable and unfavorable directions to the heat transfer rate in the unfavorable direction. A gas-filled, nano-gap structure with two different surface coatings is considered to design the thermal rectifier. In such a structure where the characteristic length scale is similar to the order of the mean free path of the fluid particles (Knudsen flow regime), the effective thermal conductivity is dominantly controlled by the gas-surface interaction, i.e., thermal accommodation coefficient. For the thermal rectification, the adsorption-based, nonlinear thermal accommodation coefficient change is a key design parameter. Here, these are examined using the kinetic theory for various pressure and temperature ranges. Optimal material selections are also discussed.
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Pavlidis, Georges, James Dallas, Sukwon Choi, Shyh-Chiang Shen et Samuel Graham. « Steady State and Transient Thermal Characterization of Vertical GaN PIN Diodes ». Dans ASME 2017 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems collocated with the ASME 2017 Conference on Information Storage and Processing Systems. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/ipack2017-74149.
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In this work, we investigate the thermal response of GaN PIN diodes grown on a sapphire substrate and compare the results to GaN PIN diodes grown on a free standing GaN substrate (FS-GaN). Until now, thermal characterization techniques have been developed to assess the temperature distribution across lateral devices. Raman thermometry has shown to accurately measure the temperature rise across the depth of the GaN layer. Implementing this technique to assess the temperature distribution across the depth of a vertical GaN device is more challenging since a volumetric depth average is measured. The use of TiO2 nanoparticles is shown to overcome this issue and reduce the uncertainty in the peak temperature by probing a surface temperature on top of the device. For the sapphire substrate, an additional temperature rise of about 15 K was seen on the surface of the PIN diode as compared to the average in the bulk. While the steady state thermal measurements show an accurate estimation of the device’s peak temperature, the PIN diodes are normally operated under pulsed conditions and the thermal response of these devices under periodic joule heating must be assessed. A recently developed transient thermoreflectance imaging technique (TTI) is used in this study to monitor transient temperature rise and decay of top metal contact. Under the same biasing conditions, the FS-GaN PIN diode is found to result in less than half the temperature rise obtained by the sapphire substrate diode. Extracting time constants, a longer rise and decay is also observed in the sapphire substrate diode.
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Huang, Yong, Qing Gao, Yan Liu et Y. Y. Yan. « Investigation of Thermal Characteristics on Simultaneous Snow and Melt in Road ». Dans ASME 2010 International Mechanical Engineering Congress and Exposition. ASMEDC, 2010. http://dx.doi.org/10.1115/imece2010-40041.
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An automatically controlled hydronic ice-snow melting (HISM) technology in road coupled with slab solar collection (SSC) and underground thermal energy storage (UTES) has become an increasingly sustainable and important measure in road engineering and heat engineering An experiment on the hydronic snow melting system with coil pipe imbedded in road was implemented to investigate the thermal characteristics of simultaneous snow and melt in road. Research focused on the active sync process of road snow melting in the different pitch pipe, snow melt patterns, surface temperature, unit area heat consumption and unit length temperature difference, etc, and explored factors of impact characteristics, and recognized a synchronous process. The result shows that the smaller pipe pitch of dense arrangement is, the higher snow free area ratio is and the effect of snow removal is better. Actually the short duration of snow melting needs big heat load and heat consumption. The arrangement of small pitch can support big heating intensity. In the simultaneous snow and melt, a short duration of snow melting and timely melting must be fulfilled as quickly as possible and it can significantly shorten the lifetime of snow accumulated on road. But a big heating system will be required and it leads to a large initial investment.
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Bula, Antonio J., Muhammad M. Rahman et John E. Leland. « Transient Axial Free Jet Impinging Over a Flat Uniformly Heated Disk : Solid–Fluid Properties Effects ». Dans ASME 2000 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/imece2000-1543.
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Abstract Transient conjugate heat transfer process during axial free jet impingement on a solid disk of finite thickness was considered. As the fluid reached steady state, power was turned on and a uniform heat flux was imposed on the disk at its opposite surface. The numerical model considered both solid and fluid regions. Equations for conservation of mass, momentum, and energy were solved in the liquid region taking into account the transport processes at the inlet and exit boundaries, as well as at the solid-liquid and liquid-gas interfaces. Inside the solid, only the heat conduction equation was solved. The shape and location of the free surface (liquid-gas interface) was determined iteratively as a part of the solution process by satisfying the kinematic condition as well as the balance of normal and shear forces at this interface. A non-uniform grid distribution, captured from a systematic grid-independence study, was used to adequately accommodate large variations near the solid-fluid interface. Computed results include the simulation of six different substrate materials namely, aluminum, constantan, copper, diamond, silicon, and silver, and three different impinging liquids, FC - 77, Mil - 7808, and water. The solids and fluids selected covered a wide range of possibilities of conjugate heat transfer phenomena. The analysis performed showed that the thermal storage capacity, defined as density times specific heat, is an important factor defining which material will attain steady state faster during conjugate heat transfer process, like the thermal diffusivity does it for pure conduction heat transfer.
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Mallampati, Sandeep, Liang Yin, David Shaddock, Harry Schoeller et Junghyun Cho. « Lead-Free Alternatives for Interconnects in High-Temperature Electronics ». Dans ASME 2017 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems collocated with the ASME 2017 Conference on Information Storage and Processing Systems. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/ipack2017-74169.
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Predominant high melting point solders for high temperature and harsh environment electronics (operating temperatures from 200 to 250°C) are Pb-based systems, which are being subjected to RoHS regulations because of their toxic nature. In this study, high bismuth (Bi) alloy compositions with Bi-XSb-10Cu (X from 10 wt.% to 20 wt.%) were designed and developed to evaluate their potential as high-temperature, Pb-free replacements. Reflow processes were developed to make die-attach samples made out of the cast Bi alloys. In particular, die-attach joints made out of Bi-15Sb-10Cu alloy exhibited an average shear strength of 24 MPa, which is comparable to that of commercially available high Pb solders. These alloy compositions also retained original shear strength even after thermal shock between −55°C and +200°C and high temperature storage at 200°C. Brittle interfacial fracture sometimes occurred along the interfacial NiSb layer formed between Bi(Sb) matrix and Ni metallized surface. In addition, heat dissipation capabilities, using flash diffusivity, were measured on the die-attach assembly, compared to the corresponding bulk alloys. The thermal conductivity of all the Bi-Sb alloys was higher than that of pure Bi. By creating high volume fraction of precipitates in a die-attach joint microstructure, it was feasible to further increase thermal conductivity of this joint to 24 W/m·K, which is three times higher than that of pure Bi (8 W/m·K). Bi-15Sb-10Cu alloy has so far shown the most promising performance as a die-attach material for high temperature applications (operated over 200°C). Hence, this alloy was further studied to evaluate its potential for plastic deformation. Bi-15Sb-10Cu alloy has shown limited plastic deformation in room temperature tensile testing, in which premature fracture occurred via the cracks propagated on the (111) cleavage planes of rhombohedral crystal structure of the Bi(Sb) matrix. The same alloy has, however, shown up to 7% plastic strain under tension when tested at 175°C. The cleavage planes, which became oriented at smaller angles to the tensile stress, contributed to improved plasticity in the high temperature test.
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Srinivasan, G., R. Murcko et K. Srihari. « Evaluation of Secondary Wire Bond Integrity on Ag Plated and Ni/Pd Based Lead Frame Plating Finishes ». Dans ASME 2009 InterPACK Conference collocated with the ASME 2009 Summer Heat Transfer Conference and the ASME 2009 3rd International Conference on Energy Sustainability. ASMEDC, 2009. http://dx.doi.org/10.1115/interpack2009-89241.
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As the legislatures demand the use of lead (Pb) free plating finishes in lead frame manufacturing, different plating finishes are being offered by the lead frame makers. Lead frames are most often designed with two different Pb free plating finishes, primarily tin and nickel/palladium (Ni/Pd) based. The tin post mold plated lead frames use silver selective plating on the lead fingers for secondary wire bonding whereas the pre-plated Ni/Pd based lead frames use the same Ni/Pd based finish throughout. Enhanced versions of Ni/Pd based plating finishes such as nickel/palladium/gold (Ni/Pd/Au), nickel/palladium/gold-palladium (Ni/Pd/Au-Pd) and nickel/palladium/gold-silver (Ni/Pd/Au – Ag) are now available to further improve the wirebondability, solderability and reliability of the package. The development of a new lead frame finish involves a wide variety of concerns which must be addressed and thus mandates further evaluation of these new structures. Using the common Pb free lead frame plating finish of selectively plated silver (Ag) as the basis, a comparative approach was used to evaluate the secondary wire bond integrity of a 25 micron (1 mil) thick gold wire on Ni/Pd based lead frame plating finishes. The integrity of the secondary wire bonds for different plating finishes was investigated at various assembly thermal exposure stages using the wire pull strength test as the arbiter. Reliability tests, such as High Temperature Storage (HTS) and Unbiased Highly Accelerated Stress Test (UBHAST), were also conducted. Finally, failure analysis was conducted with the help of metallographic cross sectioning, SEM/EDX (Scanning Electron Microscope/Energy Dispersive X-ray) analysis and statistical analysis of the wire pull strength test results. Before wire bonding the lead frames, the plating surface was investigated for its surface integrity with the help of plating quality tests, such as: (i) adhesive tape test, (ii) bend test, (iii) heating test and the (iv) scribing test. Also, since wire pull is a destructive test, a statistical method called a nested gauge R&R study was used to estimate the repeatability and reproducibility of the measurement system. Failure analysis showed that there were silver and copper migrations over the Ag plated lead frame when exposed to a high temperature storage test at 175°C for 1000 hrs, but this did not affect the bond integrity. However, the Ni/Pd based lead frames did not show any metal migration since nickel acts as a barrier against the base metal diffusion.
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Lall, Pradeep, Vishal Mehta, Jeff Suhling et Ken Blecker. « High-G Level Shock Damage-Accrual in Doped/Undoped SnAgCu Solders Under 100°C Sustained Operation Up to 1-Year ». Dans ASME 2023 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems. American Society of Mechanical Engineers, 2023. http://dx.doi.org/10.1115/ipack2023-111981.
Texte intégralRésumé :
Abstract In the automotive, oil & gas, aerospace, and medical technology sectors, electronic parts are frequently subjected to higher strain loads as a result of shocks, vibrations, and drop-impact circumstances. The electrical parts in such applications are frequently exposed to severe low and high temperatures ranging from −65°C to 200°C. Furthermore, in the critical environment, these electronic equipment can be exposed to high strain rates ranging from 1 to 100 per second. SAC solder alloys are the primary alloys used to replace tin-lead solders in electronic assembly applications. Surface mount, wave soldering, and hand soldering applications have all demonstrated the effectiveness of SAC solder alloys. Numerous doped solder alloys, such as SAC-Q, SAC-R, Innolot, M758 etc. have recently been introduced in electronic components. Mechanical characteristics and statistics for lead-free solder alloys are critical for enhancing electronic package durability at high temperatures and strain rates. Additionally, thermal aging causes microstructure changes, and can significantly affect the mechanical characteristics of solder alloys. There are not enough results are available for the mechanical properties of solder alloys with extreme low to high working temperatures. Additionally, there is currently a lack of published literature on the mechanical performance of lead-free alloys under the harsh conditions of high-temperature vibration, drop, and shock. SAC Solders are tested and examined for this study at working temperatures ranging from −65°C to 200°C and at strain rates of up to 75 per second for up to 1 year of isothermal aging with a storage temperature of 100°C. Also, the obtained experimental findings and data were fitted to the Anand viscoplasticity model, and the Anand constants were determined by calculating the stress-strain behavior reported for operating temperatures ranging from −65°C to +200°C. In addition, FE analysis for drop/shock events for 1500g, for BGA package assembly with PCB has been performed. Hysteresis stress-strain curves and plastic work density curves for the solder ball joints are examined under various thermal aging circumstances for drop/shock events. Effect of various operating temperatures and aging durations on hysteresis loops and plastic work densities have been studied.
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Muhammad, Moin, Saja Al Balushi et Carrie Murtland. « Harvesting Geothermal Energy from Produced Reservoir Fluids Eliminates CO2 Emission from Production Facility Operations ». Dans International Petroleum Technology Conference. IPTC, 2022. http://dx.doi.org/10.2523/iptc-22313-ea.
Texte intégralRésumé :
Abstract Objective ICE thermal Harvesting has developed a patented technology to convert neglected thermal energy existing in producing oil and gas wells to 100% emissions free electrical power to fulfil in-field power needs and improve operators’ emissions profile. By leveraging advanced process design and automation, heat is harvested and converted to electricity which is then safely delivered to local equipment, the grid, or energy storage fields. During production of oil and gas from high-temperature, high-pressure formations, reservoir fluids are sent through a surface choke reducing the pressure prior to flowing to surface production equipment and pipelines. Flowing pressures before a choke can be as high as 10,000 psi and will most commonly be reduced to pressures below 1,400 psi. This pressure regulation is critical to both limit unmitigated flow from the well, optimizing the ultimate recovery from the reservoir, as well as to protect surface assets from potentially damaging flowing pressures. However, as the flowing pressure is reduced, the temperature as a result also drops significantly and the thermal energy is lost. Additionally, due to the depth of many of these producer wells, the fluid being produced from the subterranean reservoirs contain large amounts of thermal energy. Currently, this thermal energy is unutilized because there is no existing methodology or technology to effectively capture this thermal energy or convert it to electrical power. Based on the EIA estimates, there are roughly 900,000 producing wells across US lands and waters. From conservative initial ICE estimates, at least 7,500 of these well sites have the potential to be utilized for this application. With electric power rates of ICE packages varying from 125kW to 210kW, this would equate to 937,500 MW to 1,575,000 MW of emissions free power production for consumption within the United States. Contrary to previous past projects exploring similar technologies aiming to utilize oil and gas wells as geothermal reserviors, the requirement of continuously pumping large volumes of fresh water downhole is eliminated by utilizing producing wells instead of reconditioning de-commissioned wells. Because the wells are already producing, the ICE system relies on the reservoir pressure or others production lift mechnism to push the oil and gas stream back to surface, rather than pumping large volumes of fluid downhole to recover the geothermal energy. The benefit of this is reducing the parasitic loads imposed by pumping fluid downhole, ultimately improving net power output by over 50%. ICE's innovations to date have been primarily centered around the harvesting of one or more heat sources, aggregating those heat sources in an optimal manner through a patented process loop, and modulating heat transfer through automated control methods. This controlled thermal product is then transferred to the Organic Rankine Cycle generator portion of the system for conversion to electricity. Building upon decades of experience in the electrification of oilfield services, ICE engineers designed the system to be highly mobile, modular, and scalable to comply with the demands of remote oilfield operations. Contrary to other heat-to-power systems, the ICE system does not necessitate civil infrastructure work or the employment of EPC firms to install. ICE systems are planned to be installed in processes spanning several industrial spaces including cement manufacturing, power production, and industrial manufacturing; anywhere large industrial cooling is required, there exists opportunity to implement ICE technology. The initial strong interest from oil and gas operators has caused the initial deployments to focus on the energy sector. These applications are found across the oil and gas value chain, ranging from upstream, midstream, and downstream processes. For this overview, two ICE system applications will be described. For the first application, thermal energy will be harvested from aggregated oil production from 11 conventional wells. As liquid production is aggregated in-field and routed toward initial processing, the production stream will flow though ICE Thermal Harvesting's system, where heat will be extracted from the stream. The second application will harvest thermal energy from natural gas wells. In this application, hot, high- pressure gas from two wells will flow through the ICE system in the vicinity of the wellhead where flowing pressures are still high. Wellhead temperatures of these wells are greater than 230 degrees Fahrenheit. The ICE system is expected to have a cooling impact of over 40 degrees Fahrenheit on the gas stream during the power production process, which will greatly reduce the cooling duty required on location. Both projects will be executed in three phases: Phase 1: Assessing the feasibility of power production from subject assets by evaluating production dataPhase 2: Utilizing the measured heat within the subject assets, ICE will finalize engineering design on heat exchange equipment best suited to harvest the maximum amount of thermal energy from production streams.Phase 3: Critical parameters will be continuously monitored remotely. Optimization engineering to be performed to maximize power production from the system to achieve as close to 125kW nameplate output as possible.