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Статті в журналах з теми "Effective heat-conducting"
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Peng, Yang, Yun Mou, Tao Wang, Hao Wang, Renli Liang, Xinzhong Wang, Mingxiang Chen, and Xiaobing Luo. "Effective Heat Dissipation of QD-Based WLEDs by Stacking QD Film on Heat-Conducting Phosphor-Sapphire Composite." IEEE Transactions on Electron Devices 66, no. 6 (June 2019): 2637–42. http://dx.doi.org/10.1109/ted.2019.2907700.
Повний текст джерела
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Chumak, Kostyantyn. "The thermoelastic contact problem for wavy surfaces with a heat-conducting medium in interface gaps." Mathematics and Mechanics of Solids 23, no. 10 (August 25, 2017): 1389–406. http://dx.doi.org/10.1177/1081286517726369.
Повний текст джерелаАнотація:
This paper presents a study on the thermoelastic contact between a wavy surface and a flat surface in the presence of a heat-conducting interstitial medium in interface gaps. The influence of applied mechanical and thermal loads on the deformation of the gaps is taken into account. The contact problem is reduced to a system of singular integro-differential equations for a temperature jump across the gaps and the height of the gaps. Solutions are obtained for the cases of thermoinsulated and heat-conducting gaps. It is shown that, in contrast to the thermoinsulated gap model, the use of the heat-conducting gap model makes it possible to construct a physically correct solution of the contact problem. It is revealed that the wavy interface with heat-conducting gaps exhibits thermal rectification. The effects of the medium’s thermal conductivity, the pressure and heat flow magnitudes and the waviness amplitude on the effective thermal contact resistance and the level of thermal rectification are analysed.
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Shchipacheva, E. V., and M. K. Turdalieva. "ACCOUNTING FOR SPECIFIC HEAT LOSSES THROUGH HEAT-CONDUCTING INCLUSIONS AS AN EFFECTIVE WAY TO DETERMINE THE HEAT-PROTECTIVE PROPERTIES OF BUILDING ENCLOSING STRUCTURES." Theoretical & Applied Science 106, no. 02 (February 28, 2022): 545–52. http://dx.doi.org/10.15863/tas.2022.02.106.54.
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Vėjelienė, Jolanta. "PROCESSED STRAW AS EFFECTIVE THERMAL INSULATION FOR BUILDING ENVELOPE CONSTRUCTIONS." Engineering Structures and Technologies 4, no. 3 (October 4, 2012): 96–103. http://dx.doi.org/10.3846/2029882x.2012.730286.
Повний текст джерелаАнотація:
The efficiency of thermal insulation materials obtained from renewable resources depends on the possibilities of reducing thermal transfer via solid and gaseous conduction, thermal radiation and, in some cases, convection. The heat transfer mechanism for thermal insulation materials mostly depends on the structure and density of the material used. Efficient thermal insulation materials consist of a gaseous phase and a solid skeleton. Gas content in such materials can take more than 99% of material by volume. In this case, thermal transfer via solid conductivity is negligible. The current work analyses the possibilities of reducing heat transfer in the straw of a varying structure. For conducting experiments, barley straw was used. To evaluate the impact of straw stalk orientation in a specimen on thermal conductivity, strongly horizontally and vertically oriented specimens of straw stalks were prepared. To reduce heat transfer via gaseous conduction and convection in large cavities in straw stalks and between stalks, barley straw were chopped and defibered. In order to decrease heat transfer via radiation after thermal conductivity measurements, mechanically processed straw were coated with infrared absorbers. Due to thermal conductivity measurements of chopped and defibered straw, an optimal amount of infrared absorbers were determined.
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Manners, W. "Heat conduction through irregularly spaced plane strip contacts." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 214, no. 8 (August 1, 2000): 1049–57. http://dx.doi.org/10.1243/0954406001523515.
Повний текст джерелаАнотація:
Solutions are developed for the conductive heat flow in the xy plane where there is a uniform flow at infinite values of y, and where y = 0 represents the interface between two materials. This interface consists of an arbitrary pattern of perfectly conducting strips and non-conducting gaps. It is assumed that thermoelastic effects are negligible. The solution takes the form of an equation with one unknown parameter per gap, and these unknowns can be found by a simple solution process involving numerical integration. The effective resistance of the interface can then be determined by a simple numerical integration.
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Sydorets, Volodymyr, Andrey Dubko, and Volodymyr Korzhyk. "Study on the Resistive Heat Source in a Two-Phase Medium at High-Frequency Electrosurgical Intervention." Applied Mechanics and Materials 873 (November 2017): 140–44. http://dx.doi.org/10.4028/www.scientific.net/amm.873.140.
Повний текст джерелаАнотація:
Numerical analysis of distribution of resistive heat source in two-phase conducting medium (copper electrode – biological tissue) was carried out. Axisymmetric two-dimensional elliptic problem, with boundary conditions of the first and second kind was solved in the environment of MATLAB mathematical package, using the method of finite differences. Analysis results show that heat source concentration and other parameters are determined by skin effect. This fact should be taken into account in development of new effective methods of surgical treatment and respective instruments. This mathematical model can be applied in a wide frequency range for conducting materials with different conductivities.
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Romenski, E., I. Peshkov, M. Dumbser, and F. Fambri. "A new continuum model for general relativistic viscous heat-conducting media." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 378, no. 2170 (March 30, 2020): 20190175. http://dx.doi.org/10.1098/rsta.2019.0175.
Повний текст джерелаАнотація:
The lack of formulation of macroscopic equations for irreversible dynamics of viscous heat-conducting media compatible with the causality principle of Einstein’s special relativity and the Euler–Lagrange structure of general relativity is a long-lasting problem. In this paper, we propose a possible solution to this problem in the framework of SHTC equations. The approach does not rely on postulates of equilibrium irreversible thermodynamics but treats irreversible processes from the non-equilibrium point of view. Thus, each transfer process is characterized by a characteristic velocity of perturbation propagation in the non-equilibrium state, as well as by an intrinsic time/length scale of the dissipative dynamics. The resulting system of governing equations is formulated as a first-order system of hyperbolic equations with relaxation-type irreversible terms. Via a formal asymptotic analysis, we demonstrate that classical transport coefficients such as viscosity, heat conductivity, etc., are recovered in leading terms of our theory as effective transport coefficients. Some numerical examples are presented in order to demonstrate the viability of the approach. This article is part of the theme issue ‘Fundamental aspects of nonequilibrium thermodynamics’.
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Nasrin, Rehena. "Influence of centered conducting obstacle on MHD combined convection in a wavy chamber." Journal of Naval Architecture and Marine Engineering 8, no. 2 (November 22, 2011): 93–104. http://dx.doi.org/10.3329/jname.v8i2.7392.
Повний текст джерелаАнотація:
The development of centered heat conducting obstacle effect on combined magnetoconvective flow in a lid driven chamber has been numerically studied. The enclosure considered has rectangular horizontal lower surfaces and vertical side surfaces. The lower and upper surfaces are insulated. The left wall is mechanically lid driven having uniform temperature Ti and velocity v0 while other vertical side is wavy and maintains higher temperature Th than the lid. The governing two-dimensional flow equations have been solved by using Galerkin weighted residual finite element technique. The investigations are conducted for different values of Richardson number (Ri) and physical parameter i.e. diameter (D) of square solid body. Various characteristics such as streamlines, isotherms and heat transfer rate in terms of the mean Nusselt number (Nu), the average temperature (?av) of the fluid and temperature of obstacle center (?c) are presented. The results indicate that the mentioned parameters strongly affect the flow phenomenon and temperature field inside the chamber. Conducting largest obstacle is preferable for effective heat transfer mechanism in presence of magnetic field.Keywords: Combined convection, MHD, wavy chamber, heat conducting obstacle, finite element simulation.doi: http://dx.doi.org/10.3329/jname.v8i2.7392 Journal of Naval Architecture and Marine Engineering 8(2011) 93-104
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Bauwens, Luc. "Oscillating flow of a heat-conducting fluid in a narrow tube." Journal of Fluid Mechanics 324 (October 10, 1996): 135–61. http://dx.doi.org/10.1017/s0022112096007860.
Повний текст джерелаАнотація:
Thermoacoustic refrigeration occurs in periodic flow in a duct with heat transfer within the fluid and to the tube. This study considers the periodic limit cycle with large pressure oscillations that is obtained in a tube when prescribed, phase-shifted, periodic velocities at the tube ends, at frequencies lower than acoustic eigenmodes, sweep a length comparable to the tube length. The temperature differences between the two ends are of arbitrary magnitude, heat transfer in the transverse direction within the fluid is assumed to be very effective and the thermal mass of the wall is large. The geometry is two-dimensional, axisymmetric, and conduction is accounted for, not only in the fluid, but also with and within the tube wall. A perturbation solution valid in a local near-isothermal limit determines the equilibrium longitudinal temperature profile that is reached at the periodic regime, the pressure field including longitudinal gradients, and the longitudinal enthalpy flux. Results are presented for tubes open at both ends and also with one end closed. In the latter case, a singularity occurs in the temperature at the closed end, with behaviour identical to Rott's result for acoustic flow with small pressure amplitude. Other new results obtained for tubes open at both ends show that when velocities at both ends are in opposite phase, internal singularities in the temperature profiles may occur.
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Zhong, Zhong, Yuan Sun, Xiu-Qun Yang, Weidong Guo, and Haishan Chen. "A Sensitivity Study of an Effective Aerodynamic Parameter Scheme in Simulating Land–Atmosphere Interaction for a Sea–Land Breeze Case Around the Bohai Gulf of China." Journal of Hydrometeorology 18, no. 8 (July 18, 2017): 2101–15. http://dx.doi.org/10.1175/jhm-d-16-0184.1.
Повний текст джерелаАнотація:
Abstract Numerical simulations of the atmospheric boundary layer require careful representation of the surface heterogeneity, which involves the upscaling parameterization scheme for the heterogeneous surface parameters. In this study, the sensitivity comparisons of an effective aerodynamic parameter scheme against the area-weighted average scheme in simulating the land–atmosphere interaction over heterogeneous terrain were carried out by conducting multinested simulations with the Weather Research and Forecasting (WRF) Model at coarse and fine resolutions, for a typical sea–land breeze case in the Bohai Gulf of China. The results show that the limited-area model is sensitive to the aerodynamic parameter scheme and the effective aerodynamic parameter scheme exhibits a better performance in simulating the variables and parameters in the land–atmosphere interaction process, such as surface wind speed, sensible heat flux, latent heat flux, friction velocity, and surface air temperature, among others, for short-term simulations. Particularly, the underestimation of sensible heat flux and overestimation of latent heat flux over heterogeneous terrain with area-weighted average scheme for aerodynamic parameters can be improved with the effective parameter scheme in the coastal regions, where the mean simulation error with the effective parameter scheme is about one-half of that with the average scheme for sensible heat flux and one-third for latent heat flux.
Дисертації з теми "Effective heat-conducting"
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Синотин, А. М. "Автоматизация расчётов нестационарных тепловых режимов при проектировании одноблочных радиоэлектронных аппаратов". Thesis, ХНУРЕ, 2008. http://openarchive.nure.ua/handle/document/6863.
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Thesis is devoted to the research of heat exchange character in radio electronic vehicles which function in an air environment at normal atmospheric pressure; the development of calculation method of the non-stationary temperature fields of REA with the arbitrary law of change of the power dispersed elements from a temperature and time; the research of influence of structural parameters of vehicle taking into account the anisotropy of the heated areas on a heat-conducting on a general temperature condition.
First, on the basis of the conducted analytical and experimental researches, the algorithm of the thermophysical planning of onesectional radio electronic vehicles is got that allows to provide the set temperature condition on the initial stages of constructing parallell with development of electric chart and choice of element base. It considerably promotes economic efficiency of developments and eliminates the necessity of substantial changes for a construction on results checking calculations and temperature tests.
Тези доповідей конференцій з теми "Effective heat-conducting"
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Kruger, Sunita, and Leon Pretorius. "The Effect of Vertical and Horizontal Partitions on Natural Convection in a Heated Enclosure." In ASME 2013 Heat Transfer Summer Conference collocated with the ASME 2013 7th International Conference on Energy Sustainability and the ASME 2013 11th International Conference on Fuel Cell Science, Engineering and Technology. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/ht2013-17439.
Повний текст джерелаАнотація:
In this paper, turbulent buoyancy induced convection in a partitioned square cavity with conducting baffles is numerically investigated to determine overall heat transfer performance. The finite volume method using polyhedral cells is used to solve the governing mass, momentum and energy equations and to predict the flow patterns and heat transfer in the cavity. The cavity consisted of two adiabatic vertical walls, an isothermal horizontal wall located at the bottom at Th and the top wall isothermal at Tc. The configuration was investigated for Ra = 9.1 × 107 to Ra = 1.9 × 109 (turbulent). The conducting baffles are assigned various values of effective thermal resistances, calculated using thermal conductivity. The effects of these conducting baffles and their effective thermal resistance are shown in terms of temperature and velocity contour plots and average Nusselt number. Results indicated that the presence of baffles influenced the heat transfer from the hot wall considerably, and it was concluded that a partitioned enclosure containing conducting partitions can be used to represent an enclosed greenhouse containing raised benches with single/multiple racks.
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Gupta, Narendra K. "Improving Thermal Performance of Radioactive Material Drum Type Packages by Using Heat Pipes." In ASME 2007 Pressure Vessels and Piping Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/pvp2007-26043.
Повний текст джерелаАнотація:
This paper presents a feasibility study to improve thermal loading of existing radioactive material packages by using heat pipes. The concept could be used to channel heat in certain directions and dissipate to the environment. The concept is applied to a drum type package because the drum type packages are stored and transported in an upright position. This orientation is suitable for heat pipe operation that could facilitate the heat pipe implementation in the existing well proven package designs or in new designs where thermal loading is high. In this position, heat pipes utilize gravity very effectively to enhance heat flow in the upward direction Heat pipes have extremely high effective thermal conductivity that is several magnitudes higher than the most heat conducting metals. In addition, heat pipes are highly unidirectional so that the effective conductivity for heat transfer in the reverse direction is greatly reduced. The concept is applied to the 9977 package that is currently going through the DOE certification review. The paper presents computer simulations using typical of-the-shelf heat pipe available configurations and performance data for the 9977 package. A path forward is outlined for implementing the concepts for further study and prototype testing.
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Lange, C. F., M. Breuer, F. Durst, and J. M. Shi. "Numerical Assessment of Hot-Wire Data Deviations in the Vicinity of Walls." In ASME 1999 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/imece1999-0991.
Повний текст джерелаАнотація:
Abstract A detailed numerical assessment of the data deviations and the corresponding corrections needed by hot-wire anemometry (HWA) measurements in wall vicinity was performed. The aim of this study was to determine effective correction functions to HWA data for different wall materials. Two extreme cases were first investigated: a perfectly heat conducting and an adiabatic wall. In the case of the perfectly conducting wall the computed results agreed well with available experimental data for highly conducting materials. However, the numerical results for the case of an adiabatic wall contradicted previous experimental observations based on low-conducting wall materials. A close evaluation of the numerical results led to a better understanding of the physical problem and motivated the simulation of realistic wall materials, such as aluminum and glass.
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Laurien, E., and S. Becker. "Simulation of Flow and Heat Transport in a High-Temperature Reactor With Three-Dimensional Power Distribution." In ASME 2003 Heat Transfer Summer Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/ht2003-47138.
Повний текст джерелаАнотація:
A three-dimensional computational analysis is employed to investigate the transient flow and heat transport within an annular-core High-Temperature Reactor pebble bed, the blind core, and the surrounding graphite structures including 36 embedded coolant feeding channels. Well established models of pressure loss in the pebble bed, heat transfer between helium and the pebbles, and the heat transport within the porous medium by conduction and radiation (using an effective conductivity) have been implemented into an extended version of CFX-4. The graphite structures of the reflector are simulated closely coupled to the flow simulation as heat conducting solids. The model has been verified for axisymmetric power distributions by comparison with known results from 2D analysis. Various 3D-power distributions are assumed to represent a possible loss of forced cooling incident after unusual plant operation such as asymmetric positioning of absorber rods. It is confirmed, that 2D analysis is not adequate, because the predicted maximum temperature of the fuel elements after fission shutdown may exceed the maximum temperature predicted by 2D analysis.
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Vaitheeswaran, Pavan Kumar, and Ganesh Subbarayan. "Estimation of Effective Thermal and Mechanical Properties of Particulate Thermal Interface Materials (TIMs) by a Random Network Model." In 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/ipack2017-74129.
Повний текст джерелаАнотація:
Particulate thermal interface materials (TIMs) are commonly used to transport heat from chip to heat sink. While high thermal conductance is achieved by large volume loadings of highly conducting particles in a compliant matrix, small volume loadings of stiff particles will ensure reduced thermal stresses in the brittle silicon device. Developing numerical models to estimate effective thermal and mechanical properties of TIM systems would help optimize TIM performance with respect to these conflicting requirements. Classical models, often based on single particle solutions or regular arrangement of particles, are insufficient as real-life TIM systems contain a distriubtion of particles at high volume fractions, where classical models are invalid. In our earlier work, a computationally efficient random network model was developed to estimate the effective thermal conductivity of TIM systems [1,2]. This model is extended in this paper to estimate the effective elastic modulus of TIMs. Realistic microstructures are simulated and analyzed using the proposed method. Factors affecting the modulus (volume fraction and particle size distribution) are also studied.
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Gunes, Hasan, Sertac Cadırcı, and Kenan Gocmen. "Numerical Simulation of Mixed Convection in a Rectangular Cavity With Multiple Heat Sources." In ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-11472.
Повний текст джерелаАнотація:
A numerical study is presented for a mixed convection in a two-dimensional partially open rectangular cavity. The uniform heat-flux, discrete heat sources are flush-mounted on three identical heat conducting vertical boards, which are mounted on the bottom wall of a partially open cavity. An external airflow enters the cavity through an opening (inlet) in the left vertical wall and exits from the opposite opening (outlet) in the right vertical wall. In this paper, the effect of the number of boards on the flow and thermal field characteristics are investigated and compared with a single board case, where appropriate. The simulations are carried out for wide ranges of Reynolds number and Richardson number (buoyancy parameter, Ri = Gr/Re2) for a working fluid of air (Pr = 0.71). The solutions were found to be time-independent for only sufficiently low values of Re and Ri. For large Re and/or Ri, the oscillatory flow is analyzed by considering time-histories, frequencies and instantaneous snapshots for the field variables. The effect of the oscillatory flow on the heat removal from the heat source is discussed. It was observed that with the onset of oscillatory flow, the re-circulating cells set into motion and thus considerable reduction in the maximum dimensionless temperature is achieved, making the cooling with convection as an effective mode of heat transfer. The results also indicate that the Reynolds number and Richardson number have a strong effect on the temperature and velocity distributions as well as the average Nusselt number evaluated over the heat source.
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Nara, S., P. Bhattacharya, P. Vijayan, W. Lai, W. Rosenthal, P. E. Phelan, R. S. Prasher, D. W. Song, and J. Wang. "Experimental Determination of the Effect of Varying the Base Fluid on Static Thermal Conductivity of Nanofluids." In ASME 2005 International Mechanical Engineering Congress and Exposition. ASMEDC, 2005. http://dx.doi.org/10.1115/imece2005-81494.
Повний текст джерелаАнотація:
The heat transfer abilities of fluids can be improved by adding small particles of sizes of the order of nanometers. Recently a lot of research has been done in evaluating the thermal conductivity of nanofluids using various nanoparticles. In our present work we address this issue by conducting a series of experiments to determine the effective thermal conductivity of alumina-nanofluids by varying the base fluid with water and antifreeze liquids like ethylene glycol and propylene glycol. Temperature oscillation method is used to find the thermal conductivity of the nanofluid. The results show the thermal conductivity enhancement of nanofluids depends on viscosity of the base fluid. Finally the results are validated with a recently proposed theoretical model.
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Ono, Naoki, Atsushi Hamaoka, and Yuta Otsubo. "Fluid Motion and Heat Transfer of Boiling With Impinging Flow in a Mini-Tube With Nonlinear Thermocapillary Solutions." In 2010 14th International Heat Transfer Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/ihtc14-22498.
Повний текст джерелаАнотація:
Boiling heat transfer with impinging flow can be an effective way for cooling a small heated area such as CPUs and laser emitting devices. In the phenomena the movement of liquid layer on the heated surface strongly affects the detachment of boiling bubbles and the heat flux. In this study, nonlinear thermocapillary solutions such as button aqueous solutions were applied to this type of boiling with impinging flow aiming to promote heat transfer. These solutions have special characteristics that the surface tension increases as the temperature is raised over some temperature. It is expected that this tendency about the surface tension will promote the wetting of the heated surface and the detachment of boiling bubbles. In the experiment, T-shaped mini tubes were built with quartz tubes and used for flow boiling. The inner diameter of the tube was 2 mm and the outer diameter was 4 mm. The liquid flow impinged at the junction point where small area was heated by using a conducting thin film coated at the outer surface of the tube. The test fluids were butanol aqueous solution and pure water. The flow rate of the liquid was the order of 1 ml/min, the concentration of the butanol aqueous solution was 7.15 wt %. The liquid motion was observed by CCD video camera system. It was found from the experiment that the motion of the liquid layer of the butanol solution at the impinging area was very different from that of pure water. The layer of the butanol solution tended to extend to the hotter part of the heated area. In another experiment for precisely fixing the imposed heat flux value, T-shaped mini channel with small copper surface installed for heating the fluid was prepared. The cross section of the channel was rectangular shape of 3 mm × 3 mm, and the entire channel was made of insulating polymer material. It was found that the heat transfer of the boiling with impinging flow in using butanol solution was more promoted than that in using pure water.
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Ahuja, Yogita, Raafat Ibrahim, Anna Paradowska, and Daniel Riley. "Probeless Tool Aided Friction Stir Welding as a Fabrication Technique for Tungsten Embedded Mechanical Composite of Copper." In ASME 2014 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/pvp2014-28571.
Повний текст джерелаАнотація:
Friction stir welding (FSW) is a relatively new solid state metallurgical joining technique. It flourishes on the simple principle of utilising frictional heat by the stirring motion of a non-consumable rotating tool to create the seam. Feasibility of FSW aided by a newly designed probeless tool was investigated for fabricating copper-tungsten mechanical composite. The most effective parameter combination was determined by conducting a parametric study of the probeless tool aided FSW copper. Strength of the mechanical composite fabricated at this condition was evaluated through punch shear testing. Punch shear testing established that the friction stir welded interface of the copper-tungsten composite was 87% as strong as the base metal (i.e. copper). Advantages of the designed technique have been summarised.
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Sinha, Ashish, Krishna Kota, Pablo Hidalgo, Yogendra Joshi, and Ari Glezer. "Novel Immersion Cooling Technique for a 3D Chip Stack." In ASME 2013 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/ipack2013-73039.
Повний текст джерелаАнотація:
An experimental investigation of a scheme for cooling electronics packaged in a 3D stack arrangement will be presented in this paper. The scheme utilizes immersion cooling of the stacked electronics in an enclosure filled with a dielectric fluid. Convection and conduction within the dielectric fluid drive heat from the 3D stack to the walls of the enclosure from where a ‘synthetic jet /fan air-cooled heat sink’ ultimately dissipates heat to the ambient. Four layers of thick film heaters embedded in FR-4 sheets, each attached to thin copper plates (innovatively stacked in a pyramidal arrangement for conducting heat laterally to the dielectric fluid and simultaneously promoting natural convection in the fluid), were used to simulate a 3D stack of electronics. For a comparative study, several runs were carried out, where the enclosure was filled with dielectric fluid (FC-770), FC-770 in combination with copper wool (with a goal of enhancing heat transfer in FC-770), and water. For a 40 W total power input to the stack, it was observed that the thermal resistance for heat dissipation to ambient from the four heaters varied from 1.67 K/W to 1.96 K/W with FC-770, 1.47 K/W to 1.87 K/W with FC-770 combined with copper wool, and 1.06 K/W to 1.50 K/W with water. The proposed cooling solution is passive and scalable, and is demonstrated to be practicable and effective in cooling 3D stacked electronics.
Звіти організацій з теми "Effective heat-conducting"
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Weinschenk, Craig, and Jack Regan. Analysis of Search and Rescue Tactics in Single-Story Single-Family Homes Part II: Kitchen and Living Room Fires. UL's Fire Safety Research Institute, May 2022. http://dx.doi.org/10.54206/102376/zkxw6893.
Повний текст джерелаАнотація:
Prior full-scale fire service research on the residential fireground has focused the impact of ventilation and suppression tactics on fire dynamics. This study builds upon prior research by conducting 10 experiments a purpose-built single-story, single-family residential structure to quantify the im- pact of how search and rescue tactics are coupled with ventilation and suppression actions and timing. Each fully furnished structure included four bedrooms, 2 bathrooms and an open-floor kitchen and living room. The structures were instrumented to quantify post-ignition toxic gas and thermal conditions. Temperature, velocity, and pressure were measured to evaluate the fire dynamics. Gas concentrations and heat fluxes were measured to quantify toxic and thermal exposures. Across this series of experiments, the impact of isolation of fire and non-fire compartments, the timing of search actions relative to suppression actions, and the influence of isolation, elevation, and path of travel during rescue were examined with respect to firefighter safety and occupant tenability. Similar to previous experiments in both purpose-built and acquired structure, the data showed that prior intervention locations lower in elevation and/or behind closed doors had lower toxic gas and thermal exposures compared to locations at higher elevations or locations that were not isolated. Lower elevations were also shown to have lower toxic gas and thermal exposures during the removal of occupants as part of rescue operations. For scenarios where search operations occurred prior to suppression, isolation of spaces from flow paths connected to the fire compartment was shown to be effective at reducing the thermal operating class for firefighters and the toxic and thermal exposure rates compared to spaces that were not isolated. Following isolation, exterior ventilation was found to further reduce the toxic gas and thermal exposures in the protected space. Suppression, from either interior and exterior positions, was effective at reducing the thermal operating class for searching firefighters and the rate of thermal exposure increase to occupants. Following suppression, additional exterior ventilation increased the rate at which gas concentrations returned to pre-ignition levels.
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Weinschenk, Craig. Analysis of Search and Rescue Tactics in Single-Story Single-Family Homes Part I: Bedroom Fires. UL's Fire Safety Research Institute, May 2022. http://dx.doi.org/10.54206/102376/dptn2682.
Повний текст джерелаАнотація:
Prior full-scale fire service research on the residential fireground has focused the impact of ventilation and suppression tactics on fire dynamics. This study builds upon prior research by conducting 11 experiments a purpose-built single-story, single-family residential structure to quantify the im- pact of how search and rescue tactics are coupled with ventilation and suppression actions and timing. Each fully furnished structure included four bedrooms, 2 bathrooms and an open-floor kitchen and living room. The structures were instrumented to quantify post-ignition toxic gas and thermal conditions. Temperature, velocity, and pressure were measured to evaluate the fire dynamics. Gas concentrations and heat fluxes were measured to quantify toxic and thermal exposures. Across this series of experiments, the impact of isolation of fire and non-fire compartments, the timing of search actions relative to suppression actions, and the influence of isolation, elevation, and path of travel during rescue were examined with respect to firefighter safety and occupant tenability. Similar to previous experiments in both purpose-built and acquired structure, the data showed that prior intervention locations lower in elevation and/or behind closed doors had lower toxic gas and thermal exposures compared to locations at higher elevations or locations that were not isolated. Lower elevations were also shown to have lower toxic gas and thermal exposures during the removal of occupants as part of rescue operations. For scenarios where search operations occurred prior to suppression, isolation of spaces from flow paths connected to the fire compartment was shown to be effective at reducing the thermal operating class for firefighters and the toxic and thermal exposure rates compared to spaces that were not isolated. Following isolation, exterior ventilation was found to further reduce the toxic gas and thermal exposures in the protected space. Suppression, from either interior and exterior positions, was effective at reducing the thermal operating class for searching firefighters and the rate of thermal exposure increase to occupants. Following suppression, additional exterior ventilation increased the rate at which gas concentrations returned to pre-ignition levels.
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Regan, Jack, and Robin Zevotek. Evaluation of the Thermal Conditions and Smoke Obscuration of Live Fire Training Fuel Packages. UL Firefighter Safety Research Institute, March 2019. http://dx.doi.org/10.54206/102376/karu4002.
Повний текст джерелаАнотація:
Firefighters routinely conduct live fire training in an effort to prepare themselves for the challenges of the fire ground. While conducting realistic live fire training is important, it also carries inherent risks. This is highlighted by several live fire training incidents in which an inappropriate fuel load contributed to the death of participants. NFPA 1403: Standard on Live Fire Training Evolutions was first established in response to a live fire training incident in which several firefighters died. Among the stipulations in NFPA 1403 is that the fuel load shall be composed of wood-based fuels. The challenge of balancing safety with fidelity has led instructors to explore a variety of different methods to create more realistic training conditions. A series of experiments was conducted in order to characterize common training fuels, compare these training fuels to furnishings, and examine the performance of these training fuels in a metal container prop. Heat release rate (HRR) characterization of training fuels indicated that wood-based training fuels had a constant effective heat of combustion. Depending on the method used, this value was between 13.6 and 13.9 MJ/kg. This indicates that, even in engineered wood products, wood is the primary material responsible for combustion. In order to further explore the conclusions from the HRR testing, additional experiments were conducted in an L-shaped metal training prop. The results of these experiments highlighted a number of considerations for firefighter training. Thermal conditions consistent with “realistic fires” could be produced using NFPA 1403 compliant fuels, and in fact the thermal conditions produced by larger wood-based fuel packages were more severe than those produced by fuel packages with a small amount of synthetic fuel. The fuel package used in training evolutions should reflect the training prop or building being used, the available ventilation, and the intended lesson. Fuel load weight and orientation are both important considerations when designing a fuel package. The training considerations drawn from this report will help to increase firefighters’ understanding of fire dynamics, and help instructors better understand fuel packages and the fire dynamics that they produce.
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Weinschenk, Craig, and Keith Stakes. Analysis of Search and Rescue Tactics in Single-Story Single-Family Homes Part III: Tactical Considerations. UL's Fire Safety Research Institute, May 2022. http://dx.doi.org/10.54206/102376/xsla7995.
Повний текст джерелаАнотація:
Prior full-scale fire service research on the residential fireground has focused the impact of ventilation and suppression tactics on fire dynamics. This study builds upon prior research by conducting 21 experiments in two identical purpose-built single-story, single-family residential structures to quantify the impact of how search and rescue tactics are coupled with ventilation and suppression actions and timing. Each fully furnished structure included four bedrooms, 2 bathrooms and an open-floor kitchen and living room. The structures were instrumented to quantify post-ignition toxic gas and thermal conditions. Temperature, velocity, and pressure were measured to evaluate the fire dynamics. Gas concentrations and heat fluxes were measured to quantify toxic and thermal exposures. Eleven experiments examined bedroom fires, eight examined kitchen fires, and two examined living room fires. Across this series of experiments, the impact of isolation of fire and non-fire compartments, the timing of search actions relative to suppression actions, and the influence of isolation, elevation, and path of travel during rescue were examined with respect to firefighter safety and occupant tenability. Similar to previous experiments in both purpose-built and acquired structure, the data showed that prior intervention locations lower in elevation and/or behind closed doors had lower toxic gas and thermal exposures compared to locations at higher elevations or locations that were not isolated. Lower elevations were also shown to have lower toxic gas and thermal exposures during the removal of occupants as part of rescue operations. For scenarios where search operations occurred prior to suppression, isolation of spaces from flow paths connected to the fire compartment was shown to be effective at reducing the thermal operating class for firefighters and the toxic and thermal exposure rates compared to spaces that were not isolated. Following isolation, exterior ventilation was found to further reduce the toxic gas and thermal exposures in the protected space. Suppression, from either interior and exterior positions, was effective at reducing the thermal operating class for searching firefighters and the rate of thermal exposure increase to occupants. Following suppression, additional exterior ventilation increased the rate at which gas concentrations returned to pre-ignition levels.