Hall and ion slip effects on peristaltic flow of Jeffrey nanofluid with Joule heating

Energy Technology Data Exchange (ETDEWEB)

Hayat, T. [Department of Mathematics, Quaid-I-Azam University 45320, Islamabad 44000 (Pakistan); NAAM Research Group, Department of Mathematics, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia); Shafique, Maryam [Department of Mathematics, Quaid-I-Azam University 45320, Islamabad 44000 (Pakistan); Tanveer, A., E-mail: anum@math.qau.edu.pk [Department of Mathematics, Quaid-I-Azam University 45320, Islamabad 44000 (Pakistan); Alsaedi, A. [NAAM Research Group, Department of Mathematics, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia)

2016-06-01

This paper addresses mixed convective peristaltic flow of Jeffrey nanofluid in a channel with complaint walls. The present investigation includes the viscous dissipation, thermal radiation and Joule heating. Hall and ion slip effects are also taken into account. Related problems through long wavelength and low Reynolds number are examined for stream function, temperature and concentration. Impacts of thermal radiation, Hartman number, Brownian motion parameter, thermophoresis, Joule heating, Hall and ion slip parameters are investigated in detail. It is observed that velocity increases and temperature decreases with Hall and ion slip parameters. Further the thermal radiation on temperature has qualitatively similar role to that of Hall and ion slip effects. - Highlights: • Peristalsis in the presence of Jeffery nanofluid is formulated. • Compliant properties of channel walls are addressed. • Impact of Hall and ion slip effects is outlined. • Influence of Joule heating and radiation is investigated. • Mixed convection for both heat and mass transfer is present.

The variability of Joule heating, and its effects on the ionosphere and thermosphere

Directory of Open Access Journals (Sweden)

A. S. Rodger

2001-07-01

Full Text Available A considerable fraction of the solar wind energy that crosses the magnetopause ends up in the high-latitude thermosphere-ionosphere system as a result of Joule heating, the consequences of which are very significant and global in nature. Often Joule heating calculations use hourly averages of the electric field, rather than the time-varying electric field. This leads to an underestimation of the heating. In this paper, we determine the magnitude of the underestimation of Joule heating by analysing electric field data from the EISCAT Incoherent Scatter Radar, situated at the 67° E magnetic latitude. We find that the underestimation, using hourly-averaged electric field values, is normally ~20%, with an upper value of about 65%. We find that these values are insensitive to changes in solar flux, magnetic activity and magnetic local time, implying that the electric field fluctuations are linear related to the amplitude of the electric field. Assuming that these changes are representative of the entire auroral oval, we then use a coupled ionosphere-thermosphere model to calculate the local changes these underestimations in the heating rate cause to the neutral temperature, mean molecular mass and meridional wind. The changes in each parameter are of the order of a few percent but they result in a reduction in the peak F-region concentration of ~20% in the summer hemisphere at high latitudes, and about half of this level in the winter hemisphere. We suggest that these calculations could be used to add corrections to modelled values of Joule heating.Key words. Ionosphere (eletric fields and currents; ionospheric disturbances; polar ionosphere

Joule-Heated Molten Regolith Electrolysis Reactor Concepts for Oxygen and Metals Production on the Moon and Mars

Science.gov (United States)

Sibille, Laurent; Dominques, Jesus A.

2012-01-01

The maturation of Molten Regolith Electrolysis (MRE) as a viable technology for oxygen and metals production on explored planets relies on the realization of the self-heating mode for the reactor. Joule heat generated during regolith electrolysis creates thermal energy that should be able to maintain the molten phase (similar to electrolytic Hall-Heroult process for aluminum production). Self-heating via Joule heating offers many advantages: (1) The regolith itself is the crucible material, it protects the vessel walls (2) Simplifies the engineering of the reactor (3) Reduces power consumption (no external heating) (4) Extends the longevity of the reactor. Predictive modeling is a tool chosen to perform dimensional analysis of a self-heating reactor: (1) Multiphysics modeling (COMSOL) was selected for Joule heat generation and heat transfer (2) Objective is to identify critical dimensions for first reactor prototype.

Incorporation of the Joule Heating of highly conducting materials into the Truchas code via an asymptotic approach

Energy Technology Data Exchange (ETDEWEB)

Akcay, Cihan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Haut, Terry Scot [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Carlson, Neil N. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2016-05-21

The EM module of the Truchas code currently lacks the capability to model the Joule (Ohmic) heating of highly conducting materials that are inserted into induction furnaces from time to time to change the heating profile. This effect is difficult to simulate directly because of the requirement to resolve the extremely thin skin depth of good conductors, which is computationally costly. For example, copper has a skin depth, δ ~ 1 mm, for an oscillation frequency of tens of kHz. The industry is interested in determining what fraction of the heating power is lost to the Joule heating of these good conductors inserted inside the furnaces. The approach presented in this document is one of asymptotics where the leading order (unperturbed) solution is taken as that which emerges from solving the EM problem for a perfectly conducting insert. The conductor is treated as a boundary of the domain. The perturbative correction enters as a series expansion in terms of the dimensionless skin depth δ/L, where L is the characteristic size of the EM system. The correction at each order depends on the previous. This means that the leading order correction only depends on the unperturbed solution, in other words, it does not require Truchas to perform an additional EM field solve. Thus, the Joule heating can be captured by a clever leveraging of the existing tools in Truchas with only slight modifications.

Joule heating induced stream broadening in free-flow zone electrophoresis.

Science.gov (United States)

Dutta, Debashis

2018-03-01

The use of an electric field in free-flow zone electrophoresis (FFZE) automatically leads to Joule heating yielding a higher temperature at the center of the separation chamber relative to that around the channel walls. For small amounts of heat generated, this thermal effect introduces a variation in the equilibrium position of the analyte molecules due to the dependence of liquid viscosity and analyte diffusivity on temperature leading to a modification in the position of the analyte stream as well as the zone width. In this article, an analytic theory is presented to quantitate such effects of Joule heating on FFZE assays in the limit of small temperature differentials across the channel gap yielding a closed form expression for the stream position and zone variance under equilibrium conditions. A method-of-moments approach is employed to develop this analytic theory, which is further validated with numerical solutions of the governing equations. Interestingly, the noted analyses predict that Joule heating can drift the location of the analyte stream either way of its equilibrium position realized in the absence of any temperature rise in the system, and also tends to reduce zone dispersion. The extent of these modifications, however, is governed by the electric field induced temperature rise and three Péclet numbers evaluated based on the axial pressure-driven flow, transverse electroosmotic and electrophoretic solute velocities in the separation chamber. Monte Carlo simulations of the FFZE system further establish a time and a length scale over which the results from the analytic theory are valid. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Magnetohydrodynamics Carreau nanofluid flow over an inclined convective heated stretching cylinder with Joule heating

Directory of Open Access Journals (Sweden)

Imad Khan

Full Text Available Current work highlights the computational aspects of MHD Carreau nanofluid flow over an inclined stretching cylinder with convective boundary conditions and Joule heating. The mathematical modeling of physical problem yields nonlinear set of partial differential equations. A suitable scaling group of variables is employed on modeled equations to convert them into non-dimensional form. The integration scheme Runge-Kutta-Fehlberg on the behalf of shooting technique is utilized to solve attained set of equations. The interesting aspects of physical problem (linear momentum, energy and nanoparticles concentration are elaborated under the different parametric conditions through graphical and tabular manners. Additionally, the quantities (local skin friction coefficient, local Nusselt number and local Sherwood number which are responsible to dig out the physical phenomena in the vicinity of stretched surface are computed and delineated by varying controlling flow parameters. Keywords: MHD, Carreau nanofluid, Inclined stretching cylinder, Joule heating, Shooting technique

A numerical study of magnetohydrodynamics flow in Casson nanofluid combined with Joule heating and slip boundary conditions

Directory of Open Access Journals (Sweden)

A. Kamran

Full Text Available A numerical study of Casson nanofluid past horizontal stretching surface with magnetic effect and Joule heating are presented. Slip and thermal convective boundary conditions are considered in the study. A numerical technique of Keller box is applied to the nonlinear ODEs which are obtained by applying the similarity transformation to the nonlinear partial differential equations. The magnetic field and Joule heating effects are observed graphically. Also the strength of convective heat exchange (Nusselt number and the strength of mass exchange (Sherwood number are analyzed. It is noted that Nusselt number declines whereas Sherwood number rises by increasing Eckert number. The impact of increasing Hartman number resulted in the decrease of both Sherwood and Nusselt number. Keywords: Casson nanofluid, Magnetohydrodynamic, Joule heating, Keller box method

Statistics of Joule heating in the auroral zone and polar cap using Astrid-2 satellite Poynting flux

Directory of Open Access Journals (Sweden)

A. Olsson

2004-12-01

Full Text Available We make a statistical study of ionospheric Joule heating with the Poynting flux method using six months of Astrid-2/EMMA electric and magnetic field data during 1999 (solar maximum year. For the background magnetic field we use the IGRF model. Our results are in agreement with earlier statistical satellite studies using both the ΣPE2 method and the Poynting flux method. We present a rather comprehensive set of fitted Joule heating formulas expressing the Joule heating in given magnetic local time (MLT and invariant latitude (ILAT range under given solar illumination conditions as a function of the Kp index, the AE index, the Akasofu epsilon parameter and the solar wind kinetic energy flux. The study thus provides improved and more detailed estimates of the statistical Joule heating. Such estimates are necessary building blocks for future quantitative studies of the power budget in the magnetosphere and in the nightside auroral region. Key words. Ionosphere (electric fields and currents; ionosphere-magnetosphere interactions – Magnetospheric physics (magnetospheric configuration and dynamics

Rotating ferro-nanofluid over stretching plate under the effect of hall current and joule heating

Energy Technology Data Exchange (ETDEWEB)

Abdel-Wahed, Mohamed S., E-mail: eng_moh_sayed@live.com

2017-05-01

The behavior of boundary layer over a stretching plate filled with ferromagnetic Fe{sub 3}O{sub 4} nanoparticles and subjected to magnetic field with hall current, joule heating and nonlinear thermal radiation has been investigated. The modeling based on nonlinear partial differential equations due to continuity, momentum and heat equations, these equations transformed to a system of nonlinear ordinary differential equations using similarity transformation technique then solved numerically. The effect of hall current, joule heating and thermal radiation on the physical quantities such as surface shear stress and heat flux have been investigated and discussed. Moreover, the velocities and temperature profiles of the boundary layer under the influence of the presented external forces plotted and discussed. - Highlights: • The existence of the hall current increases the transverse velocity, as well as has a limited impact on the longitudinal velocity. • Boundary layer temperature exposed to nonlinear thermal radiation is higher than that exposed to linear thermal radiation. • Joule heating increases the boundary layer temperature near the surface especially in the linear model of thermal radiation. • Magnetic field with hall current increases the x-direction skin friction and reduces it in the y-direction.

Effect of cold cap boundary conditions on Joule-heating flow in the sloping bottom cavity

International Nuclear Information System (INIS)

Zhou, Jiaju; Tanaka, Hiromasa; Tsuzuki, Nobuyoshi; Kikura, Hiroshige

2015-01-01

Flow behavior in a sloping bottom cavity is observed to study the effect of cavity shape on flow behavior for Joule-heating flow. In the former study, a simple cubic cavity is applied to study the chaotic flow behavior of Joule-heating convection due to simplification as the real melter case is complicated. In this study, a sloping bottom cavity of the dimension one-fifth of the actual melter is applied to study the detail flow behavior. Carbon electrodes and top cooling surface are placed to make Joule-heating and the chaotic flow behavior. The working fluid is 80%wt Glycerol-water solution with LiCl as electrolyte. To observe the chaotic flow behavior spatio-temporally, Ultrasonic Velocity Profiler (UVP) is applied in this experiment to obtain the one-dimensional continuous velocity profiles in the center line of cavity. Particle Image Velocity (PIV) method is also applied to observe the two-dimensional flow behavior and to examine the cross-check between UVP and PIV for the chaotic flow behavior with temperature distribution. The flow profiles of the former cubic cavity and the sloping bottom cavity are compared changing voltage magnitude and cooling temperature of the electrodes side to analyze the effect of cavity shape under Joule-heating condition. The flow behavior in the upper part of the sloping bottom cavity is similar to that in the cubic cavity in the experiment in whole cavity, the range down-flow achieved is larger than the cubic cavity. (author)

Development of slagging system using DC joule-heating furnace; Chokuryu denki teikoshiki hai yoyu gijutsu no shohinka

Energy Technology Data Exchange (ETDEWEB)

Yoshinari, N.; Ueda, J.; Nishino, J.; Takeshige, S. [Ishikawajima-Harima Heavy Industries Co. Ltd., Tokyo (Japan)

1998-03-01

Waste disposal by incineration is in wide use, inevitably discharging the unburnt portion or ash as the residue, and the residue contains heavy metals and dioxins. New slagging technologies capable of dealing with the situation, respecting in addition the effective use of resources, are now attracting attention, and are coming into popular use. IHI has already developed three types of melting technologies, which are the residual carbon combustion type, the joule-heating furnace type, and the coke-bed furnace type, and has already delivered to clients some facilities using these technologies. In this report, the three types are outlined, and the joule-heating furnace is taken up to explain the process of development up to commercialization. In the joule-heating furnace, molten slag (resistivity several ohms/cm at 1300degC) is electrified for the melting of ash by joule heat, and the result is a high-quality slag containing less chlorine thanks to the electrochemical decomposition. Studies were conducted about exhaust gas cleaning, silent operation, and cost performance (using only one electrode), etc., by operating 2.4t/d and 10t/d demonstration plants, and the efforts have culminated in the commercialization of the technology. 6 refs., 9 figs., 7 tabs.

Startup of a Joule-heated glass melter with a graphite slurry

International Nuclear Information System (INIS)

Allen, T.L.; Porter, M.A.; Routt, K.R.

1984-01-01

Startup of a Joule-heated glass melter using a graphite slurry as a conducting medium was demonstrated. This technique can be used for the initial startup and for the restart of a melter used for vitrifying high-level radioactive waste. Theory, physical property data, and a demonstration test are reported

Jupiter Thermospheric General Circulation Model (JTGCM): Global Structure and Dynamics Driven by Auroral and Joule Heating

Science.gov (United States)

Bougher, S. W.; J. Il. Waite, Jr.; Majeed, T.

2005-01-01

A growing multispectral database plus recent Galileo descent measurements are being used to construct a self-consistent picture of the Jupiter thermosphere/ionosphere system. The proper characterization of Jupiter s upper atmosphere, embedded ionosphere, and auroral features requires the examination of underlying processes, including the feedbacks of energetics, neutral-ion dynamics, composition, and magnetospheric coupling. A fully 3-D Jupiter Thermospheric General Circulation Model (JTGCM) has been developed and exercised to address global temperatures, three-component neutral winds, and neutral-ion species distributions. The domain of this JTGCM extends from 20-microbar (capturing hydrocarbon cooling) to 1.0 x 10(exp -4) nbar (including aurora/Joule heating processes). The resulting JTGCM has been fully spun-up and integrated for greater than or equal to40 Jupiter rotations. Results from three JTGCM cases incorporating moderate auroral heating, ion drag, and moderate to strong Joule heating processes are presented. The neutral horizontal winds at ionospheric heights vary from 0.5 km/s to 1.2 km/s, atomic hydrogen is transported equatorward, and auroral exospheric temperatures range from approx.1200-1300 K to above 3000 K, depending on the magnitude of Joule heating. The equatorial temperature profiles from the JTGCM are compared with the measured temperature structure from the Galileo AS1 data set. The best fit to the Galileo data implies that the major energy source for maintaining the equatorial temperatures is due to dynamical heating induced by the low-latitude convergence of the high-latitude-driven thermospheric circulation. Overall, the Jupiter thermosphere/ionosphere system is highly variable and is shown to be strongly dependent on magnetospheric coupling which regulates Joule heating.

Incorporating Cold Cap Behavior in a Joule-heated Waste Glass Melter Model

Energy Technology Data Exchange (ETDEWEB)

Varija Agarwal; Donna Post Guillen

2013-08-01

In this paper, an overview of Joule-heated waste glass melters used in the vitrification of high level waste (HLW) is presented, with a focus on the cold cap region. This region, in which feed-to-glass conversion reactions occur, is critical in determining the melting properties of any given glass melter. An existing 1D computer model of the cold cap, implemented in MATLAB, is described in detail. This model is a standalone model that calculates cold cap properties based on boundary conditions at the top and bottom of the cold cap. Efforts to couple this cold cap model with a 3D STAR-CCM+ model of a Joule-heated melter are then described. The coupling is being implemented in ModelCenter, a software integration tool. The ultimate goal of this model is to guide the specification of melter parameters that optimize glass quality and production rate.

Diamond electrophoretic microchips-Joule heating effects

International Nuclear Information System (INIS)

Karczemska, Anna T.; Witkowski, Dariusz; Ralchenko, Victor; Bolshakov, Andrey; Sovyk, Dmitry; Lysko, Jan M.; Fijalkowski, Mateusz; Bodzenta, Jerzy; Hassard, John

2011-01-01

Microchip electrophoresis (MCE) has become a mature separation technique in the recent years. In the presented research, a polycrystalline diamond electrophoretic microchip was manufactured with a microwave plasma chemical vapour deposition (MPCVD) method. A replica technique (mould method) was used to manufacture microstructures in diamond. A numerical analysis with CoventorWare TM was used to compare thermal properties during chip electrophoresis of diamond and glass microchips of the same geometries. Temperature distributions in microchips were demonstrated. Thermal, electrical, optical, chemical and mechanical parameters of the polycrystalline diamond layers are advantageous over traditionally used materials for microfluidic devices. Especially, a very high thermal conductivity coefficient gives a possibility of very efficient dissipation of Joule heat from the diamond electrophoretic microchip. This enables manufacturing of a new generation of microdevices.

Diamond electrophoretic microchips-Joule heating effects

Energy Technology Data Exchange (ETDEWEB)

Karczemska, Anna T., E-mail: anna.karczemska@p.lodz.pl [Technical University of Lodz, Institute of Turbomachinery, 219/223 Wolczanska str., Lodz (Poland); Witkowski, Dariusz [Technical University of Lodz, Institute of Turbomachinery, 219/223 Wolczanska str., Lodz (Poland); Ralchenko, Victor, E-mail: ralchenko@nsc.gpi.ru [General Physics Institute, Russian Academy of Science, 38 Vavilov str., Moscow (Russian Federation); Bolshakov, Andrey; Sovyk, Dmitry [General Physics Institute, Russian Academy of Science, 38 Vavilov str., Moscow (Russian Federation); Lysko, Jan M., E-mail: jmlysko@ite.waw.pl [Institute of Electron Technology, Al. Lotnikow 32/46, 02-668 Warsaw (Poland); Fijalkowski, Mateusz, E-mail: petr.louda@vslib.cz [Technical University of Liberec, Faculty of Mechanical Engineering (Czech Republic); Bodzenta, Jerzy, E-mail: jerzy.bodzenta@polsl.pl [Silesian University of Technology, Institute of Physics, 2 Krzywoustego str., 44-100 Gliwice (Poland); Hassard, John, E-mail: j.hassard@imperial.ac.uk [Imperial College of Science, Technology and Medicine, London (United Kingdom)

2011-03-15

Microchip electrophoresis (MCE) has become a mature separation technique in the recent years. In the presented research, a polycrystalline diamond electrophoretic microchip was manufactured with a microwave plasma chemical vapour deposition (MPCVD) method. A replica technique (mould method) was used to manufacture microstructures in diamond. A numerical analysis with CoventorWare{sup TM} was used to compare thermal properties during chip electrophoresis of diamond and glass microchips of the same geometries. Temperature distributions in microchips were demonstrated. Thermal, electrical, optical, chemical and mechanical parameters of the polycrystalline diamond layers are advantageous over traditionally used materials for microfluidic devices. Especially, a very high thermal conductivity coefficient gives a possibility of very efficient dissipation of Joule heat from the diamond electrophoretic microchip. This enables manufacturing of a new generation of microdevices.

Joule heating and runaway electron acceleration in a solar flare

Science.gov (United States)

Holman, Gordon D.; Kundu, Mukul R.; Kane, Sharad R.

1989-01-01

The hard and soft x ray and microwave emissions from a solar flare (May 14, 1980) were analyzed and interpreted in terms of Joule heating and runaway electron acceleration in one or more current sheets. It is found that all three emissions can be generated with sub-Dreicer electric fields. The soft x ray emitting plasma can only be heated by a single current sheet if the resistivity in the sheet is well above the classical, collisional resistivity of 10(exp 7) K, 10(exp 11)/cu cm plasma. If the hard x ray emission is from thermal electrons, anomalous resistivity or densities exceeding 3 x 10(exp 12)/cu cm are required. If the hard x ray emission is from nonthermal electrons, the emissions can be produced with classical resistivity in the current sheets if the heating rate is approximately 4 times greater than that deduced from the soft x ray data (with a density of 10(exp 10)/cu cm in the soft x ray emitting region), if there are at least 10(exp 4) current sheets, and if the plasma properties in the sheets are characteristic of the superhot plasma observed in some flares by Lin et al., and with Hinotori. Most of the released energy goes directly into bulk heating, rather than accelerated particles.

Effect of Joule heating and current crowding on electromigration in mobile technology

Science.gov (United States)

Tu, K. N.; Liu, Yingxia; Li, Menglu

2017-03-01

In the present era of big data and internet of things, the use of microelectronic products in all aspects of our life is manifested by the ubiquitous presence of mobile devices as i-phones and wearable i-products. These devices are facing the need for higher power and greater functionality applications such as in i-health, yet they are limited by physical size. At the moment, software (Apps) is much ahead of hardware in mobile technology. To advance hardware, the end of Moore's law in two-dimensional integrated circuits can be extended by three-dimensional integrated circuits (3D ICs). The concept of 3D ICs has been with us for more than ten years. The challenge in 3D IC technology is dense packing by using both vertical and horizontal interconnections. Mass production of 3D IC devices is behind schedule due to cost because of low yield and uncertain reliability. Joule heating is serious in a dense structure because of heat generation and dissipation. A change of reliability paradigm has advanced from failure at a specific circuit component to failure at a system level weak-link. Currently, the electronic industry is introducing 3D IC devices in mainframe computers, where cost is not an issue, for the purpose of collecting field data of failure, especially the effect of Joule heating and current crowding on electromigration. This review will concentrate on the positive feedback between Joule heating and electromigration, resulting in an accelerated system level weak-link failure. A new driving force of electromigration, the electric potential gradient force due to current crowding, will be reviewed critically. The induced failure tends to occur in the low current density region.

Small-scale, joule-heated melting of Savannah River Plant waste glass. I. Factors affecting large-scale vitrification tests

International Nuclear Information System (INIS)

Plodinec, M.J.; Chismar, P.H.

1979-10-01

A promising method of immobilizing SRP radioactive waste solids is incorporation in borosilicate glass. In the reference vitrification process, called joule-heated melting, a mixture of glass frit and calcined waste is heated by passage of an electric current. Two problems observed in large-scale tests are foaming and formation of an insoluble slag. A small joule-heated melter was designed and built to study problems such as these. This report describes the melter, identifies factors involved in foaming and slag formation, and proposes ways to overcome these problems

Stratospheric Joule heating by lightning continuing current inferred from radio remote sensing

DEFF Research Database (Denmark)

Fullekrug, M.; Ignaccolo, M.; Kuvshinov, A.

2006-01-01

to ground deposits electrical energy into the stratosphere resulting from quasi-static ( Joule) heating. The energy deposition is dominated by the lightning continuing current, and it is similar to 10(-5) J/m(3) at 30 km height. It is speculated that the initiation of blue jets and gigantic jets...

Cathode-Control Alloying at an Au-ZnSe Nanowire Contact via in Situ Joule Heating

International Nuclear Information System (INIS)

Zeng Ya-Ping; Qu Bai-Hua; Yu Hong-Chun; Wang Yan-Guo

2012-01-01

Controllable interfacial alloying is achieved at a Au-ZnSe nanowire (M-S) contact via in situ Joule heating inside transmission electron microscopy (TEM). TEM inspection reveals that the Au electrode is locally molten at the M-S contact and the tip of the ZnSe nanowire is covered by the Au melting. Experimental evidences confirm that the alloying at the reversely biased M-S contact is due to the high resistance of the Schottky barrier at this M-S contact, coincident to cathode-control mode. Consequently, in situ Joule heating can be an effective method to improve the performance of nanoelectronics based on a metal-semiconductor-metal nanostructure. (cross-disciplinary physics and related areas of science and technology)

Acceleration of runaway electrons and Joule heating in solar flares

Science.gov (United States)

Holman, G. D.

1985-01-01

The electric field acceleration of electrons out of a thermal plasma and the simultaneous Joule heating of the plasma are studied. Acceleration and heating timescales are derived and compared, and upper limits are obtained on the acceleration volume and the rate at which electrons can be accelerated. These upper limits, determined by the maximum magnetic field strength observed in flaring regions, place stringent restrictions upon the acceleration process. The role of the plasma resistivity in these processes is examined, and possible sources of anomalous resistivity are summarized. The implications of these results for the microwave and hard X-ray emission from solar flares are examined.

Implantable polymer/metal thin film structures for the localized treatment of cancer by Joule heating

Science.gov (United States)

Kan-Dapaah, Kwabena; Rahbar, Nima; Theriault, Christian; Soboyejo, Wole

2015-04-01

This paper presents an implantable polymer/metal alloy thin film structure for localized post-operative treatment of breast cancer. A combination of experiments and models is used to study the temperature changes due to Joule heating by patterned metallic thin films embedded in poly-dimethylsiloxane. The heat conduction within the device and the surrounding normal/cancerous breast tissue is modeled with three-dimensional finite element method (FEM). The FEM simulations are used to explore the potential effects of device geometry and Joule heating on the temperature distribution and lesion (thermal dose). The FEM model is validated using a gel model that mimics biological media. The predictions are also compared to prior results from in vitro studies and relevant in vivo studies in the literature. The implications of the results are discussed for the potential application of polymer/metal thin film structures in hyperthermic treatment of cancer.

Electric fields, Joule and particle heating in the high latitude thermosphere. [Review

Energy Technology Data Exchange (ETDEWEB)

Brekke, A [Auroral Observatory, Tromsoe (Norway)

1976-08-01

A short review of the recent high latitude measurements of ionospheric electric fields is given. The importance of investigating large-scale and slowly-varying electric fields in order to study magnetospheric convection is stressed. The motion of such high energetic phenomena as auroral forms and spread E-region echoes must be treated by extreme caution when interpreted as a manifestation of convection motion. The relationship between the ionospheric source and polarization field is still an unanswered problem. It is indicated that progress can be made in this respect when electric fields and conductivities are measured simultaneously in the ionosphere. Evidence is shown at one occasion that the meridional component during an auroral sunstorm might be mainly a polarization field. The height-integrated Joule heating rate is occasionally found to be far larger than the solar radiation input at auroral altitudes. The presence of this additional heat source at any time of day is expected to have a strong impact on the global-scale atmospheric dynamics. From comparisons made between Joule and particle heating it appears that the two components are comparable. It is expected that high latitude incoherent radars will contribute substantially to the understanding of these phenomena in the near future.

The role of the rheological properties of non-newtonian fluids in controlling dispersive mixing in a batch electrophoretic cell with Joule heating

Directory of Open Access Journals (Sweden)

M.A. Bosse

2001-03-01

Full Text Available The problem of the effect of Joule heating generation on the hydrodynamic profile and the solute transport found in electrophoretic devices is addressed in this article. The research is focused on the following two problems: The first one is centered around the effect of Joule heating on the hydrodynamic velocity profile and it is referred to as "the carrier fluid problem." The other one is related to the effect of Joule heating on the solute transport inside electrophoretic cells and it is referred to as "the solute problem". The hydrodynamic aspects were studied first to yield the velocity profiles required for analysis of the solute transport problem. The velocity profile obtained in this study is analytical and the results are valid for non-Newtonian fluids carriers. To this end, the power-law model was used to study the effect of the rheology of the material in conjunction with the effect of Joule heating generation inside batch electrophoretic devices. This aspect of the research was then effectively used to study the effect of Joule heating generation on the motion of solutes (such as macromolecules under the influence of non-Newtonian carriers. This aspect of the study was performed using an area-averaging approach that yielded analytical results for the effective diffusivity of the device.

Passivation of organic light emitting diode anode grid lines by pulsed Joule heating

NARCIS (Netherlands)

Janka, M.; Gierth, R.; Rubingh, J.E.; Abendroth, M.; Eggert, M.; Moet, D.J.D.; Lupo, D.

2015-01-01

We report the self-aligned passivation of a current distribution grid for an organic light emitting diode (OLED) anode using a pulsed Joule heating method to align the passivation layer accurately on the metal grid. This method involves passing an electric current through the grid to cure a polymer

Viscous dissipation and Joule heating effects in MHD 3D flow with heat and mass fluxes

Science.gov (United States)

Muhammad, Taseer; Hayat, Tasawar; Shehzad, Sabir Ali; Alsaedi, Ahmed

2018-03-01

The present research explores the three-dimensional stretched flow of viscous fluid in the presence of prescribed heat (PHF) and concentration (PCF) fluxes. Mathematical formulation is developed in the presence of chemical reaction, viscous dissipation and Joule heating effects. Fluid is electrically conducting in the presence of an applied magnetic field. Appropriate transformations yield the nonlinear ordinary differential systems. The resulting nonlinear system has been solved. Graphs are plotted to examine the impacts of physical parameters on the temperature and concentration distributions. Skin friction coefficients and local Nusselt and Sherwood numbers are computed and analyzed.

Joule-Heated Molten Regolith Electrolysis Reactor Concepts for Oxygen and Metals Production on the Moon and Mars

Science.gov (United States)

Sibille, Laurent; Dominguez, Jesus A.

2012-01-01

The technology of direct electrolysis of molten lunar regolith to produce oxygen and molten metal alloys has progressed greatly in the last few years. The development of long-lasting inert anodes and cathode designs as well as techniques for the removal of molten products from the reactor has been demonstrated. The containment of chemically aggressive oxide and metal melts is very difficult at the operating temperatures ca. 1600 C. Containing the molten oxides in a regolith shell can solve this technical issue and can be achieved by designing a Joule-heated (sometimes called 'self-heating') reactor in which the electrolytic currents generate enough Joule heat to create a molten bath. Solutions obtained by multiphysics modeling allow the identification of the critical dimensions of concept reactors.

Literature review of arc/plasma, combustion, and joule-heated melter vitrification systems

International Nuclear Information System (INIS)

Freeman, C.J.; Abrigo, G.P.; Shafer, P.J.; Merrill, R.A.

1995-07-01

This report provides reviews of papers and reports for three basic categories of melters: arc/plasma-heated melters, combustion-heated melters, and joule-heated melters. The literature reviewed here represents those publications which may lend insight to phase I testing of low-level waste vitrification being performed at the Hanford Site in FY 1995. For each melter category, information from those papers and reports containing enough information to determine steady-state mass balance data is tabulated at the end of each section. The tables show the composition of the feed processed, the off-gas measured via decontamination factors, gross energy consumptions, and processing rates, among other data

Estimation of Joule heating and its role in nonlinear electrical response of Tb0.5Sr0.5MnO3 single crystal

Science.gov (United States)

Nhalil, Hariharan; Elizabeth, Suja

2016-12-01

Highly non-linear I-V characteristics and apparent colossal electro-resistance were observed in non-charge ordered manganite Tb0.5Sr0.5MnO3 single crystal in low temperature transport measurements. Significant changes were noticed in top surface temperature of the sample as compared to its base while passing current at low temperature. By analyzing these variations, we realize that the change in surface temperature (ΔTsur) is too small to have caused by the strong negative differential resistance. A more accurate estimation of change in the sample temperature was made by back-calculating the sample temperature from the temperature variation of resistance (R-T) data (ΔTcal), which was found to be higher than ΔTsur. This result indicates that there are large thermal gradients across the sample. The experimentally derived ΔTcal is validated with the help of a simple theoretical model and estimation of Joule heating. Pulse measurements realize substantial reduction in Joule heating. With decrease in sample thickness, Joule heating effect is found to be reduced. Our studies reveal that Joule heating plays a major role in the nonlinear electrical response of Tb0.5Sr0.5MnO3. By careful management of the duty cycle and pulse current I-V measurements, Joule heating can be mitigated to a large extent.

A Joule-Heated Melter Technology For The Treatment And Immobilization Of Low-Activity Waste

International Nuclear Information System (INIS)

Kelly, S.E.

2011-01-01

This report is one of four reports written to provide background information regarding immobilization technologies remaining under consideration for supplemental immobilization of Hanford's low-activity waste. This paper provides the reader a general understanding of joule-heated ceramic lined melters and their application to Hanford's low-activity waste.

A JOULE-HEATED MELTER TECHNOLOGY FOR THE TREATMENT AND IMMOBILIZATION OF LOW-ACTIVITY WASTE

Energy Technology Data Exchange (ETDEWEB)

KELLY SE

2011-04-07

This report is one of four reports written to provide background information regarding immobilization technologies remaining under consideration for supplemental immobilization of Hanford's low-activity waste. This paper provides the reader a general understanding of joule-heated ceramic lined melters and their application to Hanford's low-activity waste.

Polar cap index as a proxy for hemispheric Joule heating

DEFF Research Database (Denmark)

Chun, F.K.; Knipp, D.J.; McHarg, M.G.

1999-01-01

The polar cap (PC) index measures the level of geomagnetic activity in the polar cap based on magnetic perturbations from overhead ionospheric currents and distant field-aligned currents on the poleward edge of the nightside auroral oval. Because PC essentially measures the main sources of energy...... input into the polar cap, we propose to use PC as a proxy for the hemispheric Joule heat production rate (JH). In this study, JH is estimated from the Assimilative Mapping of Ionospheric Electrodynamics (AMIE) procedure. We fit hourly PC values to hourly averages of JH. Using a data base approximately...

Nanomechanical Optical Fiber with Embedded Electrodes Actuated by Joule Heating.

Science.gov (United States)

Lian, Zhenggang; Segura, Martha; Podoliak, Nina; Feng, Xian; White, Nicholas; Horak, Peter

2014-07-31

Nanomechanical optical fibers with metal electrodes embedded in the jacket were fabricated by a multi-material co-draw technique. At the center of the fibers, two glass cores suspended by thin membranes and surrounded by air form a directional coupler that is highly temperature-dependent. We demonstrate optical switching between the two fiber cores by Joule heating of the electrodes with as little as 0.4 W electrical power, thereby demonstrating an electrically actuated all-fiber microelectromechanical system (MEMS). Simulations show that the main mechanism for optical switching is the transverse thermal expansion of the fiber structure.

Study of density limit in JT-60 joule heated plasmas

Energy Technology Data Exchange (ETDEWEB)

Shirai, Hiroshi; Shimizu, Katsuhiro; Takizuka, Tomonori; Hirayama, Toshio; Azumi, Masafumi [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan). Naka Fusion Research Establishment

1995-11-01

Impurities which mingle in tokamak plasmas cause dominant radiation loss in the high density regime and the energy balance of plasma is lost. This gives rise to MHD instability and results in major disruption. Density limit in joule heated plasmas has been studied by using one dimensional transport code combined with MHD instability analysis code. When the diffusion of impurity is taken into account, the numerically obtained density limit diagram or Hugill diagram quantitatively agrees well with that obtained in the experiment. It is also clarified that the corona-equilibrium model overestimates the density limit. (author).

Nanomechanical Optical Fiber with Embedded Electrodes Actuated by Joule Heating

Science.gov (United States)

Lian, Zhenggang; Segura, Martha; Podoliak, Nina; Feng, Xian; White, Nicholas; Horak, Peter

2014-01-01

Nanomechanical optical fibers with metal electrodes embedded in the jacket were fabricated by a multi-material co-draw technique. At the center of the fibers, two glass cores suspended by thin membranes and surrounded by air form a directional coupler that is highly temperature-dependent. We demonstrate optical switching between the two fiber cores by Joule heating of the electrodes with as little as 0.4 W electrical power, thereby demonstrating an electrically actuated all-fiber microelectromechanical system (MEMS). Simulations show that the main mechanism for optical switching is the transverse thermal expansion of the fiber structure. PMID:28788148

Hall current and Joule heating effects on peristaltic flow of viscous fluid in a rotating channel with convective boundary conditions

Directory of Open Access Journals (Sweden)

Tasawar Hayat

Full Text Available The present article has been arranged to study the Hall current and Joule heating effects on peristaltic flow of viscous fluid in a channel with flexible walls. Both fluid and channel are in a state of solid body rotation. Convective conditions for heat transfer in the formulation are adopted. Viscous dissipation in energy expression is taken into account. Resulting differential systems after invoking small Reynolds number and long wavelength considerations are numerically solved. Runge-Kutta scheme of order four is implemented for the results of axial and secondary velocities, temperature and heat transfer coefficient. Comparison with previous limiting studies is shown. Outcome of new parameters of interest is analyzed. Keywords: Rotating frame, Hall current, Joule heating, Convective conditions, Wall properties

First order reversal curve analysis on NdFeB nanocomposite ribbons subjected to Joule heating treatments

Energy Technology Data Exchange (ETDEWEB)

Pampillo, L.G. [INTECIN-Instituto de Tecnologias y ciencias de la Ingenieria ' Hilario Fernandez Long' (UBA-CONICET), Facultad de Ingenieria, Paseo Colon 850 (C1063ACV), C. A. B. A. (Argentina); Saccone, F.D., E-mail: fsaccone@fi.uba.ar [INTECIN-Instituto de Tecnologias y ciencias de la Ingenieria ' Hilario Fernandez Long' (UBA-CONICET), Facultad de Ingenieria, Paseo Colon 850 (C1063ACV), C. A. B. A. (Argentina); Knobel, M. [Instituto de Fisica Gleb Wataghin-Departamento de Fisica de Materia Condensada-Universidade Estadual de Campinas, Cidade Universitaria Zeferino Vaz, Barao Geraldo 13083-970, Campinas, Sao Paulo (Brazil); Sirkin, H.R.M. [INTECIN-Instituto de Tecnologias y ciencias de la Ingenieria ' Hilario Fernandez Long' (UBA-CONICET), Facultad de Ingenieria, Paseo Colon 850 (C1063ACV), C. A. B. A. (Argentina)

2012-09-25

Highlights: Black-Right-Pointing-Pointer Nd-lean amorphous precursors subjected to Joule heating. Black-Right-Pointing-Pointer Exchange-spring magnets. Black-Right-Pointing-Pointer FORC diagrams of irreversible switching fields. Black-Right-Pointing-Pointer This last techniques helped us to verify the optimized treatments conditions. - Abstract: Amorphous precursors with composition Nd{sub 4.5}Fe{sub 72-x}Co{sub 3+x}Cr{sub 2}Al{sub 1}B{sub 17.5} (x = 0, 2, 7, 12) were thermally treated by the Joule heating technique with a linearly varying electrical current. The crystallization kinetics was followed by monitoring the resistance of the ribbons during the heating up to the final applied current. Crystallized nanostructured phases coexist with an amorphous matrix, as it was observed by means of Moessbauer Spectroscopy and X-ray diffraction. The irreversible magnetic response of the Joule heated ribbons was analyzed by the First Order Reversal Curves (FORC) diagram technique. For the optimal treatments, associated with the higher maximum energy products for each sample composition, it was found that the main interaction is of a strongly dipolar characteristic. Over annealed samples show a FORC diagram that gives into account of softening, due to grain growth, for those phases precipitated at the first crystallization stage. When it is measured at 20 K, the hardest magnetic sample (Fe = 72 at.%, Co = 3 at.%, I{sub final} = 0.5 A), exhibits a diagram with characteristics corresponding to dipolar interactions of soft phases. This fact is consistent with an enhancement of the exchange length due to the increase in the soft phase stiffness as it is expected at low temperatures.

Viscous and Joule heating effects on MHD free convection flow with variable plate temperature

International Nuclear Information System (INIS)

Hossain, M.A.

1990-09-01

A steady two-dimensional laminar boundary layer flow of a viscous incompressible and electrically conducting fluid past a vertical heated plate with variable temperature in the presence of a transverse uniform magnetic field has been investigated by bringing the effect of viscous and Joules heating. The non-dimensional boundary layer equations are solved using the implicit finite difference method along with Newton's approximation for small Prandtl number chosen as typical of coolant liquid metals at operating temperature. (author). 10 refs, 2 figs, 1 tab

In-situ TEM study on structural change and light emission of a multiwall carbon nanotube during Joule heating

Science.gov (United States)

Nishikawa, K.; Asaka, K.; Nakahara, H.; Saito, Y.

2018-01-01

Structure changes of a multiwall carbon nanotube (MWNT) during Joule heating were studied with simultaneous measurement of light emission spectra. The outer shells of the MWNT peeled off one by one because of excessive heating. All the peeled outer shells finally disappeared and inner shells whose tips were closed emerged, i.e., a new MWNT was formed. Each diameter of the shells comprising the MWNT decreased compared with those before the fracture. Light emission spectra during Joule heating of an MWNT were composed of both the blackbody radiation and characteristic peaks. The peaks in the light emission spectra shifted to higher energies in accordance with shrinkage of the inner shells. The energies of the peaks in the spectra corresponded to energy gaps between van Hove singularities calculated from the diameters of the shells, indicating that the peaks in the spectra are attributed to the interband electron transition in the MWNT.

Localized Edge Vibrations and Edge Reconstruction by Joule Heating in Graphene Nanostructures

DEFF Research Database (Denmark)

Engelund, Mads; Fürst, Joachim Alexander; Jauho, Antti-Pekka

2010-01-01

Control of the edge topology of graphene nanostructures is critical to graphene-based electronics. A means of producing atomically smooth zigzag edges using electronic current has recently been demonstrated in experiments [Jia et al., Science 323, 1701 (2009)]. We develop a microscopic theory...... for current-induced edge reconstruction using density functional theory. Our calculations provide evidence for localized vibrations at edge interfaces involving unpassivated armchair edges. We demonstrate that these vibrations couple to the current, estimate their excitation by Joule heating, and argue...

The Mayer-Joule Principle: The Foundation of the First Law of Thermodynamics

Science.gov (United States)

Newburgh, Ronald; Leff, Harvey S.

2011-01-01

To most students today the mechanical equivalent of heat, called the Mayer-Joule principle, is simply a way to convert from calories to joules and vice versa. However, in linking work and heat--once thought to be disjointed concepts--it goes far beyond unit conversion. Heat had eluded understanding for two centuries after Galileo Galilei…

Controlling the crystallization and magnetic properties of melt-spun Pr2Fe14B/α-Fe nanocomposites by Joule heating

Science.gov (United States)

Jin, Z. Q.; Cui, B. Z.; Liu, J. P.; Ding, Y.; Wang, Z. L.; Thadhani, N. N.

2004-05-01

Pr2Fe14B/α-Fe based nanocomposites have been prepared through crystallization of melt-spun amorphous Pr7Tb1Fe85Nb0.5Zr0.5B6 ribbons by means of ac Joule heating while simultaneously monitoring room-temperature electrical resistance R. The R value shows a strong variation with respect to applied current I, and is closely related to the amorphous-to-nanocrystalline phase transformation. The curve of R versus I allows one to control the crystallization behavior during Joule heating and to identify the heat-treatment conditions for optimum magnetic properties. A coercivity of 550 kA/m and a maximum energy product of 128 kJ/m3 have been obtained upon heating the amorphous ribbons at a current of 2.0 A. These properties are around 30% higher than the values of samples prepared by conventionally (furnace) annealed amorphous ribbons.

Numerical Analysis of Joule Heating Behavior and Residual Compressive Stress around Crack Tip under High Electric Load

Directory of Open Access Journals (Sweden)

Thomas Jin-Chee Liu

2017-01-01

Full Text Available This paper discusses the Joule heating effect and residual compressive stress near the crack tip under the electro-thermo-structural coupling state. For the crack tip field, the compressive condition is important for retarding or stopping the crack growth.

Electro-osmotic flow of power-law fluid and heat transfer in a micro-channel with effects of Joule heating and thermal radiation

Science.gov (United States)

Shit, G. C.; Mondal, A.; Sinha, A.; Kundu, P. K.

2016-11-01

A mathematical model has been developed for studying the electro-osmotic flow and heat transfer of bio-fluids in a micro-channel in the presence of Joule heating effects. The flow of bio-fluid is governed by the non-Newtonian power-law fluid model. The effects of thermal radiation and velocity slip condition have been examined in the case of hydrophobic channel. The Poisson-Boltzmann equation governing the electrical double layer field and a body force generated by the applied electric potential field are taken into consideration. The results presented here pertain to the case where the height of the channel is much greater than the thickness of electrical double layer comprising the Stern and diffuse layers. The expressions for flow characteristics such as velocity, temperature, shear stress and Nusselt number have been derived analytically under the purview of the present model. The results estimated on the basis of the data available in the existing scientific literatures are presented graphically. The effects of thermal radiation have an important bearing on the therapeutic procedure of hyperthermia, particularly in understanding the heat transfer in micro-channel in the presence of electric potential. The dimensionless Joule heating parameter has a reducing impact on Nusselt number for both pseudo-plastic and dilatant fluids, nevertheless its impact on Nusselt number is more pronounced for dilatant fluid. Furthermore, the effect of viscous dissipation has a significant role in controlling heat transfer and should not be neglected.

Heat treatment of whole milk by the direct joule effect--experimental and numerical approaches to fouling mechanisms.

Science.gov (United States)

Fillaudeau, L; Winterton, P; Leuliet, J C; Tissier, J P; Maury, V; Semet, F; Debreyne, P; Berthou, M; Chopard, F

2006-12-01

The development of alternative technologies such as the direct Joule effect to pasteurize and sterilize food products is of great scientific and industrial interest. Our objective was 1) to gain insight into the ability to ensure ultra-high-temperature treatment of milk and 2) to investigate the links among thermal, hydraulic, and electrical phenomena in relation to fouling in a direct Joule effect heater. The ohmic heater [OH; E perpendicular to v (where E is the electrical field and v is the velocity); P (power) = 15 kW] was composed of 5 flat rectangular cells [e (space between the plate and electrode) = 15 mm, w (wall) = 76 mm, and L (length of the plate in plate heat exchanger or electrode) = 246 mm]--3 active cells to ensure heating and 2 (at the extremities) for electrical insulation and the recovery of leakage currents. In the first step, the thermal performance of the OH was investigated vs. the flow regimen [50 conductivity of fluids (0.1 thermal approach (thermal and electrical balance, modeling of the temperature profile of a fluid) and local analysis of the wall temperature of the electrode. An empirical correlation was established to estimate the temperature gradient, T(w)-T(b) (where T(w) is the wall temperature and T(b) is the product temperature) under clean conditions (without fouling) and was used to define operating conditions for pure-volume and direct-resistance heating. In the second step, the ability of OH to ensure the ultra-high-temperature treatment of whole milk was investigated and compared with a plate heat exchanger. Special care was taken to investigate the heat transfer phenomena occurring over a range of temperatures from 105 to 138 degrees C. This temperature range corresponds to the part of the process made critical by protein and mineral fouling. The objectives were 1) to demonstrate the ability of an OH to ensure heat treatment of milk, 2) to study the thermal and hydraulic performance with an increasing power and temperature

MHD effects and heat transfer for the UCM fluid along with Joule heating and thermal radiation using Cattaneo-Christov heat flux model

Energy Technology Data Exchange (ETDEWEB)

Shah, S., E-mail: sajidshah313@yahoo.com; Hussain, S.; Sagheer, M. [Department of Mathematics, Capital University of Science and Technology, Islamabad (Pakistan)

2016-08-15

Present study examines the numerical analysis of MHD flow of Maxwell fluid with thermal radiation and Joule heating by considering the recently developed Cattaneo-Christov heat flux model which explains the time relaxation characteristics for the heat flux. The objective is to analyze the governing parameters such as viscoelastic fluid parameter, Magnetic parameter, Eckert and Prandtl number’s impact on the velocity and temperature profiles through graphs and tables. Suitable similarity transformations have been used to reduce the formulated PDEs into a system of coupled non-linear ODEs. Shooting technique has been invoked for finding the numerical solutions of the dimensionless velocity and temperature profiles. Additionally, the MATLAB built-in routine bvp4c has also been used to verify and strengthen the results obtained by shooting method. From some special cases of the present work, a comparison with the previously published results has been presented.

Steady state simulation of Joule heated ceramic melter for vitrification of high level liquid waste

Energy Technology Data Exchange (ETDEWEB)

Sugilal, G; Wattal, P K; Theyyunni, T K [Process Engineering and Systems Development Division, Bhabha Atomic Research Centre, Mumbai (India); Iyer, K N [Department of Mechanical Engineering, Indian Inst. of Tech., Mumbai (India)

1994-06-01

The Joule heated ceramic melter is emerging as an attractive alternative to metallic melters for high level waste vitrification. The inherent limitations with metallic melters viz., low capacity and short melter life, are overcome in a ceramic melter which can be adopted for continuous mode of operation. The ceramic melter has the added advantage of better operational flexibility. This paper describes the three dimensional model used for simulating the complex design conditions of the ceramic melter. (author).

Steady state simulation of Joule heated ceramic melter for vitrification of high level liquid waste

International Nuclear Information System (INIS)

Sugilal, G.; Wattal, P.K.; Theyyunni, T.K.; Iyer, K.N.

1994-01-01

The Joule heated ceramic melter is emerging as an attractive alternative to metallic melters for high level waste vitrification. The inherent limitations with metallic melters viz., low capacity and short melter life, are overcome in a ceramic melter which can be adopted for continuous mode of operation. The ceramic melter has the added advantage of better operational flexibility. This paper describes the three dimensional model used for simulating the complex design conditions of the ceramic melter. (author)

Numerical model and investigations of the externally heated valve Joule engine

Energy Technology Data Exchange (ETDEWEB)

Wojewoda, Jerzy [University of Aberdeen, School of Engineering, Fraser Noble Bldg, Aberdeen AB24 3UE (United Kingdom); Kazimierski, Zbyszko [Technical University of Lodz, Institute of Turbomachinery, 219/223 Wolczanska Str., 93-005 Lodz (Poland)

2010-05-15

The mineral fuels used recently, i.e., oil and gas, will be soon exploited out. This paper presents an idea of the engine where any fuel or solar heat can be used as a source of energy. The proposed model is an externally heated, 2-stroke, valve engine (EHVE). This is a piston-type engine, entirely different from the well-known Stirling one, which is the best known example of such a solution. It works in a closed Joule cycle and is designed to produce a moderate amount of energy. The engine is composed of typical parts met in piston designs: an expander, a compressor, a heater, a cooler and, additionally, two recirculation blowers, which consume a small amount of produced power. An additional advantage is its working medium, which may be simply atmospheric air and the engine has a conventional crankshaft and an oil lubrication system. It has already been proven that operation of the EHVE is possible with satisfactory power and efficiency at the output. Comparisons of the EHVE action with and without recirculation blowers are performed. (author)

Scrutinization of thermal radiation, viscous dissipation and Joule heating effects on Marangoni convective two-phase flow of Casson fluid with fluid-particle suspension

Science.gov (United States)

Mahanthesh, B.; Gireesha, B. J.

2018-03-01

The impact of Marangoni convection on dusty Casson fluid boundary layer flow with Joule heating and viscous dissipation aspects is addressed. The surface tension is assumed to vary linearly with temperature. Physical aspects of magnetohydrodynamics and thermal radiation are also accounted. The governing problem is modelled under boundary layer approximations for fluid phase and dust particle phase and then Runge-Kutta-Fehlberg method based numeric solutions are established. The momentum and heat transport mechanisms are focused on the result of distinct governing parameters. The Nusselt number is also calculated. It is established that the rate of heat transfer can be enhanced by suspending dust particles in the base fluid. The temperature field of fluid phase and temperature of dust phase are quite reverse for thermal dust parameter. The radiative heat, viscous dissipation and Joule heating aspects are constructive for thermal fields of fluid and dust phases. The velocity of dusty Casson fluid dominates the velocity of dusty fluid while this trend is opposite in the case of temperature. Moreover qualitative behaviour of fluid phase and dust phase temperature/velocity are similar.

Joule-Thomson expansion of Kerr-AdS black holes

Energy Technology Data Exchange (ETDEWEB)

Oekcue, Oezguer; Aydiner, Ekrem [Istanbul University, Department of Physics, Faculty of Science, Istanbul (Turkey)

2018-02-15

In this paper, we study Joule-Thomson expansion for Kerr-AdS black holes in the extended phase space. A Joule-Thomson expansion formula of Kerr-AdS black holes is derived. We investigate both isenthalpic and numerical inversion curves in the T-P plane and demonstrate the cooling-heating regions for Kerr-AdS black holes. We also calculate the ratio between minimum inversion and critical temperatures for Kerr-AdS black holes. (orig.)

Numerical simulation of tubes-in-tube heat exchanger in a mixed refrigerant Joule-Thomson cryocooler

Science.gov (United States)

Damle, R. M.; Ardhapurkar, P. M.; Atrey, M. D.

2017-02-01

Mixed refrigerant Joule-Thomson (MRJT) cryocoolers can produce cryogenic temperatures with high efficiency and low operating pressures. As compared to the high system pressures of around 150-200 bar with nitrogen, the operational pressures with non-azeotropic mixtures (e.g., nitrogen-hydrocarbons) come down to 10-25 bar. With mixtures, the heat transfer in the recuperative heat exchanger takes place in the two-phase region. The simultaneous boiling and condensation of the cold and hot gas streams lead to higher heat transfer coefficients as compared to single phase heat exchange. The two-phase heat transfer in the recuperative heat exchanger drastically affects the performance of a MRJT cryocooler. In this work, a previously reported numerical model for a simple tube-in-tube heat exchanger is extended to a multi tubes-in-tube heat exchanger with a transient formulation. Additionally, the J-T expansion process is also considered to simulate the cooling process of the heat exchanger from ambient temperature conditions. A tubes-in-tube heat exchanger offers more heat transfer area per unit volume resulting in a compact design. Also, the division of flow in multiple tubes reduces the pressure drop in the heat exchanger. Simulations with different mixtures of nitrogen-hydrocarbons are carried out and the numerical results are compared with the experimental data.

Antenna-coupled terahertz radiation from joule-heated single-wall carbon nanotubes

Directory of Open Access Journals (Sweden)

M. Muthee

2011-12-01

Full Text Available In this letter an experimental method is introduced that allows detection of terahertz (THz radiation from arrays of joule-heated Single-Walled Carbon Nanotubes (SWCNTs, by coupling this radiation through integrated antennas and a silicon lens. The radiation forms a diffraction-limited beam with a total maximum radiated power of 450 nW, significantly greater than the power estimated from Nyquist thermal noise (8 nW. The physical radiation process is unknown at this stage, but possible explanations for the high radiated power are discussed briefly. The emission has a typical bandwidth of 1.2 THz and can be tuned to different frequencies by changing the dimensions of the antennas. Arrays of the devices could be integrated in CMOS integrated circuits, and find application in THz systems, such as in near-range medical imaging.

Ozone generation by negative corona discharge: the effect of Joule heating

International Nuclear Information System (INIS)

Yanallah, K; Castellanos, A; Pontiga, F; Fernandez-Rueda, A; Belasri, A

2008-01-01

Ozone generation in pure oxygen using a wire-to-cylinder corona discharge reactor is experimentally and numerically investigated. Ozone concentration is determined by means of direct UV spectroscopy and the effects of Joule heating and ozone decomposition on the electrodes are analysed for different discharge gaps. The numerical model combines the physical processes in the corona discharge with the chemistry of ozone formation and destruction. The chemical kinetics model and the electrical model are coupled through Poisson's equation, and the current-voltage (CV) characteristic measured in experiments is used as input data to the numerical simulation. The numerical model is able to predict the radial distributions of electrons, ions, atoms and molecules for each applied voltage of the CV characteristic. In particular, the evolution of ozone density inside the discharge cell has been investigated as a function of current intensity and applied voltage

Ozone generation by negative corona discharge: the effect of Joule heating

Science.gov (United States)

Yanallah, K.; Pontiga, F.; Fernández-Rueda, A.; Castellanos, A.; Belasri, A.

2008-10-01

Ozone generation in pure oxygen using a wire-to-cylinder corona discharge reactor is experimentally and numerically investigated. Ozone concentration is determined by means of direct UV spectroscopy and the effects of Joule heating and ozone decomposition on the electrodes are analysed for different discharge gaps. The numerical model combines the physical processes in the corona discharge with the chemistry of ozone formation and destruction. The chemical kinetics model and the electrical model are coupled through Poisson's equation, and the current-voltage (CV) characteristic measured in experiments is used as input data to the numerical simulation. The numerical model is able to predict the radial distributions of electrons, ions, atoms and molecules for each applied voltage of the CV characteristic. In particular, the evolution of ozone density inside the discharge cell has been investigated as a function of current intensity and applied voltage.

Influence of radiation on MHD peristaltic blood flow through a tapered channel in presence of slip and joule heating

Science.gov (United States)

Ahamad, N. Ameer; Ravikumar, S.; Govindaraju, Kalimuthu

2017-07-01

The aim of the present attempt was to investigate an effect of slip and joule heating on MHD peristaltic Newtonian fluid through an asymmetric vertical tapered channel under influence of radiation. The Mathematical modeling is investigated by utilizing long wavelength and low Reynolds number assumptions. The effects of Hartmann number, porosity parameter, volumetric flow rate, radiation parameter, non uniform parameter, shift angle, Prandtl number, Brinkman number, heat source/sink parameter on temperature characteristics are presented graphically and discussed in detail.

Magnetohydrodynamic mixed convective slip flow over an inclined porous plate with viscous dissipation and Joule heating

Directory of Open Access Journals (Sweden)

S. Das

2015-06-01

Full Text Available The combined effects of viscous dissipation and Joule heating on the momentum and thermal transport for the magnetohydrodynamic flow past an inclined plate in both aiding and opposing buoyancy situations have been carried out. The governing non-linear partial differential equations are transformed into a system of coupled non-linear ordinary differential equations using similarity transformations and then solved numerically using the Runge–Kutta fourth order method with shooting technique. Numerical results are obtained for the fluid velocity, temperature as well as the shear stress and the rate of heat transfer at the plate. The results show that there are significant effects of pertinent parameters on the flow fields.

Ozone generation by negative corona discharge: the effect of Joule heating

Energy Technology Data Exchange (ETDEWEB)

Yanallah, K; Castellanos, A [Departamento de Electronica y Electromagnetismo, Universidad de Sevilla (Spain); Pontiga, F; Fernandez-Rueda, A [Departamento de Fisica Aplicada II, Universidad de Sevilla (Spain); Belasri, A [Laboratoire de Physique des Plasmas, des Materiaux Conducteur et Leurs Applications, Universite d' Oran (Algeria)

2008-10-07

Ozone generation in pure oxygen using a wire-to-cylinder corona discharge reactor is experimentally and numerically investigated. Ozone concentration is determined by means of direct UV spectroscopy and the effects of Joule heating and ozone decomposition on the electrodes are analysed for different discharge gaps. The numerical model combines the physical processes in the corona discharge with the chemistry of ozone formation and destruction. The chemical kinetics model and the electrical model are coupled through Poisson's equation, and the current-voltage (CV) characteristic measured in experiments is used as input data to the numerical simulation. The numerical model is able to predict the radial distributions of electrons, ions, atoms and molecules for each applied voltage of the CV characteristic. In particular, the evolution of ozone density inside the discharge cell has been investigated as a function of current intensity and applied voltage.

Accelerated SDS depletion from proteins by transmembrane electrophoresis: Impacts of Joule heating.

Science.gov (United States)

Unterlander, Nicole; Doucette, Alan Austin

2018-02-08

SDS plays a key role in proteomics workflows, including protein extraction, solubilization and mass-based separations (e.g. SDS-PAGE, GELFrEE). However, SDS interferes with mass spectrometry and so it must be removed prior to analysis. We recently introduced an electrophoretic platform, termed transmembrane electrophoresis (TME), enabling extensive depletion of SDS from proteins in solution with exceptional protein yields. However, our prior TME runs required 1 h to complete, being limited by Joule heating which causes protein aggregation at higher operating currents. Here, we demonstrate effective strategies to maintain lower TME sample temperatures, permitting accelerated SDS depletion. Among these strategies, the use of a magnetic stir bar to continuously agitate a model protein system (BSA) allows SDS to be depleted below 100 ppm (>98% removal) within 10 min of TME operations, while maintaining exceptional protein recovery (>95%). Moreover, these modifications allow TME to operate without any user intervention, improving throughput and robustness of the approach. Through fits of our time-course SDS depletion curves to an exponential model, we calculate SDS depletion half-lives as low as 1.2 min. This promising electrophoretic platform should provide proteomics researchers with an effective purification strategy to enable MS characterization of SDS-containing proteins. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Heat transfer analysis for magnetohydrodynamics axisymmetric flow between stretching disks in the presence of viscous dissipation and Joule heating

Directory of Open Access Journals (Sweden)

N. Khan

2015-05-01

Full Text Available The investigation of heat transfer analysis on steady MHD axi-symmetric flow between two infinite stretching disks in the presence of viscous dissipation and Joule heating is basic objective of this paper. Attention has been focused to acquire the similarity solutions of the equations governing the flow and thermal fields. The transformed boundary value problem is solved analytically using homotopy analysis method. The series solutions are developed and the convergence of these solutions is explicitly discussed. The analytical expressions for fluid velocity, pressure and temperature are constructed and analyzed for various set of parameter values. The numerical values for skin friction coefficient and the Nusselt number are presented in tabular form. Particular attention is given to the variations of Prandtl and Eckert numbers. We examined that the dimensionless temperature field is enhanced when we increase the values of Eckert number and Prandtl number.

Vitrification of Hanford wastes in a joule-heated ceramic melter and evaluation of resultant canisterized product

International Nuclear Information System (INIS)

Chapman, C.C.; Buelt, J.L.; Slate, S.C.; Katayama, Y.B.; Bunnell, L.R.

1979-08-01

Experience gained in the week-long vitrification test and characterization of the glass produced in the run support the following conclusions: The Hanford waste simulated in this test can be readily vitrified in a joule-heated ceramic melter. Physical properties of the molten glass were entirely compatible with melter operation. The average feed rate of 106 kg/h is high enough to make the ceramic melter a feasible piece of equipment for vitrifying Hanford wastes. The glass produced in this trial had good chemical durability, 6(10) -5 g/cm 2 -d. When one of the canisters was purposely dropped onto a steel pad, the damage was limited to deformation of the steel can in the impact area, cracking of a weld, and fracturing of glass in the immediate vicinity of the impact area. No glass was released from the canister as a result of the drop test. The results of this vitrification test support the technical feasibility of vitrifying Hanford wastes by means of a joule-heated ceramic melter. Surface area for large glass castings is equivalent to the mass median particle diameters between 4.27 cm (1.75 in.) and 8.91 cm (3.51 in.) even when allowed to cool rapidly by standing in ambient air. Large canisters (up to 0.91 m in dia) can be cast without large voids while standing in air if the fill rate is over 100 kg/h. 34 figures, 10 tables

Modeling principles applied to the simulation of a joule-heated glass melter

International Nuclear Information System (INIS)

Routt, K.R.

1980-05-01

Three-dimensional conservation equations applicable to the operation of a joule-heated glass melter were rigorously examined and used to develop scaling relationships for modeling purposes. By rigorous application of the conservation equations governing transfer of mass, momentum, energy, and electrical charge in three-dimensional cylindrical coordinates, scaling relationships were derived between a glass melter and a physical model for the following independent and dependent variables: geometrical size (scale), velocity, temperature, pressure, mass input rate, energy input rate, voltage, electrode current, electrode current flux, total power, and electrical resistance. The scaling relationships were then applied to the design and construction of a physical model of the semiworks glass melter for the Defense Waste Processing Facility. The design and construction of such a model using glycerine plus LiCl as a model fluid in a one-half-scale Plexiglas tank is described

Variability of Jovian ion winds: an upper limit for enhanced Joule heating

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M. B. Lystrup

2007-05-01

Full Text Available It has been proposed that short-timescale fluctuations about the mean electric field can significantly increase the upper atmospheric energy inputs at Jupiter, which may help to explain the high observed thermospheric temperatures. We present data from the first attempt to detect such variations in the Jovian ionosphere. Line-of-sight ionospheric velocity profiles in the Southern Jovian auroral/polar region are shown, derived from the Doppler shifting of H₃⁺ infrared emission spectra. These data were recently obtained from the high-resolution CSHELL spectrometer at the NASA Infrared Telescope Facility. We find that there is no variability within this data set on timescales of the order of one minute and spatial scales of 640 km, putting upper limits on the timescales of fluctuations that would be needed to enhance Joule heating.

Influence of nonlinear thermal radiation and viscous dissipation on three-dimensional flow of Jeffrey nano fluid over a stretching sheet in the presence of Joule heating

Science.gov (United States)

Ganesh Kumar, K.; Rudraswamy, N. G.; Gireesha, B. J.; Krishnamurthy, M. R.

2017-09-01

Present exploration discusses the combined effect of viscous dissipation and Joule heating on three dimensional flow and heat transfer of a Jeffrey nanofluid in the presence of nonlinear thermal radiation. Here the flow is generated over bidirectional stretching sheet in the presence of applied magnetic field by accounting thermophoresis and Brownian motion of nanoparticles. Suitable similarity transformations are employed to reduce the governing partial differential equations into coupled nonlinear ordinary differential equations. These nonlinear ordinary differential equations are solved numerically by using the Runge-Kutta-Fehlberg fourth-fifth order method with shooting technique. Graphically results are presented and discussed for various parameters. Validation of the current method is proved by comparing our results with the existing results under limiting situations. It can be concluded that combined effect of Joule and viscous heating increases the temperature profile and thermal boundary layer thickness.

Thermodynamics of acid-base dissociation of several cathinones and 1-phenylethylamine, studied by an accurate capillary electrophoresis method free from the Joule heating impact.

Science.gov (United States)

Nowak, Paweł Mateusz; Woźniakiewicz, Michał; Mitoraj, Mariusz; Sagan, Filip; Kościelniak, Paweł

2018-03-02

Capillary electrophoresis is often used to the determination of the acid-base dissociation/deprotonation constant (pK a ), and the more advanced thermodynamic quantities describing this process (ΔH°, -TΔS°). Remarkably, it is commonly overlooked that due to insufficient dissipation of Joule heating the accuracy of parameters determined using a standard approach may be questionable. In this work we show an effective method allowing to enhance reliability of these parameters, and to estimate the magnitude of errors. It relies on finding a relationship between electrophoretic mobility and actual temperature, and performing pK a determination with the corrected mobility values. It has been employed to accurately examine the thermodynamics of acid-base dissociation of several amine compounds - known for their strong dependency of pK a on temperature: six cathinones (2-methylmethcathinone, 3-methylmethcathinone, 4-methylmethcathinone, α-pyrrolidinovalerophenone, methylenedioxypyrovalerone, and ephedrone); and structurally similar 1-phenylethylamine. The average pK a error caused by Joule heating noted at 25 °C was relatively small - 0.04-0.05 pH unit, however, a more significant inaccuracy was observed in the enthalpic and, in particular, entropic terms. An alternative correction method has also been proposed, simpler and faster, but not such effective in correcting ΔH°/-TΔS° terms. The corrected thermodynamic data have been interpreted with the aid of theoretical calculations, on a ground of the enthalpy-entropy relationships and the most probable structural effects accounting for them. Finally, we have demonstrated that the thermal dependencies of electrophoretic mobility, modelled during the correction procedure, may be directly used to find optimal temperature providing a maximal separation efficiency. Copyright © 2018 Elsevier B.V. All rights reserved.

Properties of nonstationary modes of Joule heating of a low-temperature plasma

International Nuclear Information System (INIS)

Rutkevich, I.M.; Sinkevich, O.A.

1980-01-01

The qualitative properties are investigated of the one-dimensional temperature distributions and voltage-current characteristics of a low-temperature plasma under conditions of steady-state Joule heating. The analysis is carried out for arbitrary temperature dependences of the electric conductivity sigma(T) and thermal conductivity kappa(T) (for a planar geometry). Sufficient conditions are established for uniqueness of the solution of a nonlinear boundary-value problem. The effect is studied of the relative orientation of the electric current and heat flux vectors on the properties of the solutions. Examples are constructed of N-shaped, S-shaped, and more complex voltage-current characteristics for which the uniqueness conditions are violated. The relation is studied between the temperature dependences of the true and effective electric conductivities. A qualitative difference is observed in the behavior of these quantities for a function sigma (T) having a minimum. The inverse problem is considered of determining the functions sigma(T) and kappa(T) from data of electrical measurements. The role is discussed of the finite value of the thermal resistance of the walls in the generation of nonmonotone voltage-current characteristics

Design of distributed JT (Joule-Thomson) effect heat exchanger for superfluid 2 K cooling device

Science.gov (United States)

Jeong, S.; Park, C.; Kim, K.

2018-03-01

Superfluid at 2 K or below is readily obtained from liquid helium at 4.2 K by reducing its vapour pressure. For better cooling performance, however, the cold energy of vaporized helium at 2 K chamber can be effectively utilized in a recuperator which is specially designed in this paper for accomplishing so-called the distributed Joule-Thomson (JT) expansion effect. This paper describes the design methodology of distributed JT effect heat exchanger for 2 K JT cooling device. The newly developed heat exchanger allows continuous significant pressure drop at high-pressure part of the recuperative heat exchanger by using a capillary tube. Being different from conventional recuperative heat exchangers, the efficient JT effect HX must consider the pressure drop effect as well as the heat transfer characteristic. The heat exchanger for the distributed JT effect actively utilizes continuous pressure loss at the hot stream of the heat exchanger by using an OD of 0.64 mm and an ID of 0.4 mm capillary tube. The analysis is performed by dividing the heat exchanger into the multiple sub-units of the heat exchange part and JT valve. For more accurate estimation of the pressure drop of spirally wound capillary tube, preliminary experiments are carried out to investigate the friction factor at high Reynolds number. By using the developed pressure drop correlation and the heat transfer correlation, the specification of the heat exchanger with distributed JT effect for 2 K JT refrigerator is determined.

Composites of Graphene Nanoribbon Stacks and Epoxy for Joule Heating and Deicing of Surfaces.

Science.gov (United States)

Raji, Abdul-Rahman O; Varadhachary, Tanvi; Nan, Kewang; Wang, Tuo; Lin, Jian; Ji, Yongsung; Genorio, Bostjan; Zhu, Yu; Kittrell, Carter; Tour, James M

2016-02-10

A conductive composite of graphene nanoribbon (GNR) stacks and epoxy is fabricated. The epoxy is filled with the GNR stacks, which serve as a conductive additive. The GNR stacks are on average 30 nm thick, 250 nm wide, and 30 μm long. The GNR-filled epoxy composite exhibits a conductivity >100 S/m at 5 wt % GNR content. This permits application of the GNR-epoxy composite for deicing of surfaces through Joule (voltage-induced) heating generated by the voltage across the composite. A power density of 0.5 W/cm(2) was delivered to remove ∼1 cm-thick (14 g) monolith of ice from a static helicopter rotor blade surface in a -20 °C environment.

Effect of Cattaneo-Christov heat flux on buoyancy MHD nanofluid flow and heat transfer over a stretching sheet in the presence of Joule heating and thermal radiation impacts

Science.gov (United States)

Dogonchi, A. S.; Ganji, D. D.

2018-06-01

In this study, buoyancy MHD nanofluid flow and heat transfer over a stretching sheet in the presence of Joule heating and thermal radiation impacts, are studied. Cattaneo-Christov heat flux model instead of conventional Fourier's law of heat conduction is applied to investigate the heat transfer characteristics. A similarity transformation is used to transmute the governing momentum and energy equations into non-linear ordinary differential equations with the appropriate boundary conditions. The obtained non-linear ordinary differential equations are solved numerically. The impacts of diverse active parameters such as the magnetic parameter, the radiation parameter, the buoyancy parameter, the heat source parameter, the volume fraction of nanofluid and the thermal relaxation parameter are examined on the velocity and temperature profiles. In addition, the value of the Nusselt number is calculated and presented through figures. The results demonstrate that the temperature profile is lower in the case of Cattaneo-Christov heat flux model as compared to Fourier's law. Moreover, the Nusselt number raises with the raising volume fraction of nanofluid and it abates with the ascending the radiation parameter.

Hysteresis properties of conventionally annealed and Joule-heated nanocrystalline Fe73.5Cu1Nb3Si13.5B9 alloys

International Nuclear Information System (INIS)

Tiberto, P.; Basso, V.; Beatrice, C.; Bertotti, G.

1996-01-01

The dependence of magnetic properties on the thermal treatment used to induce the amorphous-to-nanocrystalline transformation in Fe 73.5 Cu 1 Nb 3 Si 13.5 B 9 alloy has been studied. Quasi-static hysteresis loops and initial permeability measurements were performed on nanocrystalline samples obtained by conventional annealing and Joule heating. A comparison between the magnetic properties of nanocrystalline samples obtained by the two heating procedures is presented. (orig.)

Development of equipments for remote dismantling of joule heated ceramic melter

International Nuclear Information System (INIS)

Badgujar, Kiran T.; Usarkar, Sachin G.; Kumar, Binu; Nair, K.N.S.

2011-01-01

Joule Heated Ceramic Melter (JHCM) technology has been adopted for industrial scale vitrification of high level liquid waste (HLLW) at Tarapur and Kalpakkam. The melter installed at Advanced Vitrification System (AVS), Tarapur has immobilized 175 m 3 of HLLW in 113 canisters containing 11533Kg of Vitrified Waste Product (VWP). The melter has been in operation for 3 years before shutdown. It is intended to demonstrate the complete procedure of dismantling of Joule Melter in 1:1 scale prior to going in for actual dismantling in the hot cell. The Melter consists of an assembly of Inconel/SS pipes and plates, fuse cast refractories, thermal insulations of various types inside a SS casing and possibly some glass which is left over in the melter. Dismantling of melter involves remote cutting of the outer casing, pipe connections, electrical connections and removal, sizing and packing of internals in a sequential manner to minimise generation of secondary waste. The challenge involves development of remotely operated multi-degrees of freedom fixtures, modification and performance testing of standard industrial cutting and breaking tools and adapting them for remote operations. The work also involves development of equipments for collection of waste generated during the dismantling operation and packaging thus in special packages. Remotely actuated fixtures have been developed for remote top plate and side electrodes cutting. Remotely operated grab has been developed for handling of loose material and grippers have been developed for handling of refractory blocks. Industrial vacuum suction device has been modified into split units to enable for reducing the spread of powder material, while dismantling in progress. The performance test of developed fixtures, equipments, cutting and breaking tools have been carried on 1:1 scale melter model. Various parameters like cutting speed, cutting tool performance, generation of waste volume has been measured and analysed for

The exact effects of radiation and joule heating on magnetohydrodynamic Marangoni convection over a flat surface

Directory of Open Access Journals (Sweden)

Khaled S.M.

2018-01-01

Full Text Available In this paper, we re-investigate the problem describing effects of radiation, Joule heating, and viscous dissipation on magnetohydrodynamic Marangoni convection boundary layer over a flat surface with suction/injection. The analytical solution obtained for the reduced system of non-linear-coupled differential equations governing the problem. Laplace transform successfully implemented to get the exact expression for the temperature profile. Furthermore, comparing the current exact results with approximate numerical results obtained using Runge-Kutta-Fehlberg method is introduced. These comparisons declare that the published numerical results agree with the current exact results. In addition, the effects of various parameters on the temperature profile are discussed graphically.

Chemical reaction for Carreau-Yasuda nanofluid flow past a nonlinear stretching sheet considering Joule heating

Science.gov (United States)

Khan, Mair; Shahid, Amna; Malik, M. Y.; Salahuddin, T.

2018-03-01

Current analysis has been made to scrutinize the consequences of chemical response against magneto-hydrodynamic Carreau-Yasuda nanofluid flow induced by a non-linear stretching surface considering zero normal flux, slip and convective boundary conditions. Joule heating effect is also considered. Appropriate similarity approach is used to convert leading system of PDE's for Carreau-Yasuda nanofluid into nonlinear ODE's. Well known mathematical scheme namely shooting method is utilized to solve the system numerically. Physical parameters, namely Weissenberg number We , thermal slip parameter δ , thermophoresis number NT, non-linear stretching parameter n, magnetic field parameter M, velocity slip parameter k , Lewis number Le, Brownian motion parameter NB, Prandtl number Pr, Eckert number Ec and chemical reaction parameter γ upon temperature, velocity and concentration profiles are visualized through graphs and tables. Numerical influence of mass and heat transfer rates and friction factor are also represented in tabular as well as graphical form respectively. Skin friction coefficient reduces when Weissenberg number We is incremented. Rate of heat transfer enhances for large values of Brownian motion constraint NB. By increasing Lewis quantity Le rate of mass transfer declines.

Electrokinetically driven continuous-flow enrichment of colloidal particles by Joule heating induced temperature gradient focusing in a convergent-divergent microfluidic structure.

Science.gov (United States)

Zhao, Cunlu; Ge, Zhengwei; Song, Yongxin; Yang, Chun

2017-09-07

Enrichment of colloidal particles in continuous flow has not only numerous applications but also poses a great challenge in controlling physical forces that are required for achieving particle enrichment. Here, we for the first time experimentally demonstrate the electrokinetically-driven continuous-flow enrichment of colloidal particles with Joule heating induced temperature gradient focusing (TGF) in a microfluidic convergent-divergent structure. We consider four mechanisms of particle transport, i.e., advection due to electroosmosis, electrophoresis, dielectrophoresis and, and further clarify their roles in the particle enrichment. It is experimentally determined and numerically verified that the particle thermophoresis plays dominant roles in enrichment of all particle sizes considered in this study and the combined effect of electroosmosis-induced advection and electrophoresis is mainly to transport particles to the zone of enrichment. Specifically, the enrichment of particles is achieved with combined DC and AC voltages rather than a sole DC or AC voltage. A numerical model is formulated with consideration of the abovementioned four mechanisms, and the model can rationalize the experimental observations. Particularly, our analysis of numerical and experimental results indicates that thermophoresis which is usually an overlooked mechanism of material transport is crucial for the successful electrokinetic enrichment of particles with Joule heating induced TGF.

Physical modeling of joule heated ceramic glass melters for high level waste immobilization

International Nuclear Information System (INIS)

Quigley, M.S.; Kreid, D.K.

1979-03-01

This study developed physical modeling techniques and apparatus suitable for experimental analysis of joule heated ceramic glass melters designed for immobilizing high level waste. The physical modeling experiments can give qualitative insight into the design and operation of prototype furnaces and, if properly verified with prototype data, the physical models could be used for quantitative analysis of specific furnaces. Based on evaluation of the results of this study, it is recommended that the following actions and investigations be undertaken: It was not shown that the isothermal boundary conditions imposed by this study established prototypic heat losses through the boundaries of the model. Prototype wall temperatures and heat fluxes should be measured to provide better verification of the accuracy of the physical model. The VECTRA computer code is a two-dimensional analytical model. Physical model runs which are isothermal in the Y direction should be made to provide two-dimensional data for more direct comparison to the VECTRA predictions. The ability of the physical model to accurately predict prototype operating conditions should be proven before the model can become a reliable design tool. This will require significantly more prototype operating and glass property data than were available at the time of this study. A complete set of measurements covering power input, heat balances, wall temperatures, glass temperatures, and glass properties should be attempted for at least one prototype run. The information could be used to verify both physical and analytical models. Particle settling and/or sludge buildup should be studied directly by observing the accumulation of the appropriate size and density particles during feeding in the physical model. New designs should be formulated and modeled to minimize the potential problems with melter operation identifed by this study

Joule heat production rate and the particle energy injection rate as a function of the geomagnetic indices AE and AL

International Nuclear Information System (INIS)

Ahn, B.; Akasofu, S.; Kamide, Y.

1983-01-01

As a part of the joint efforts of operating six meridian chains of magnetometers during the IMS, magnetic records from 71 stations are used to deduce the distribution of electric fields and currents in the polar ionosphere for March 17, 18, and 19, 1978. As a continuation of this project, we have constructed hourly distribution maps of the Joule heat production rate and their sum over the entire polar region on the three days. For this purpose the conductivity distribution is inferred at each instant partially on the basis of an empirical method devised by Ahn et al. (1982). The particle energy injection rate is estimated similarly by using an empirical method. The data set thus obtained allows us to estimate also the global Joule heat production rate U/sub J/, the global particle energy injection rate U/sub A/ and the sum U/sub Gamma/ of the two quantities. It is found that three global quantities (watt) are related almost linearly to the AE(nT) and AL(nT) indices. Our present estimates give the following relationships: U/sub J/ = 2.3 times 10 8 x AE 8 U/sub A/ = 0.6 times 10 8 x AE 8 and U/sub I/ = 2.9 times 10 8 x AE: U/sub J/ = 3.0 times 10 8 x AL 8 U/sub A/ = 0.8 times 10 8 x AL, and U/sub I/ = 3.8 times 10 8 x AL

Joule-Thomson expansion of the charged AdS black holes

International Nuclear Information System (INIS)

Oekcue, Oezguer; Aydiner, Ekrem

2017-01-01

In this paper, we study Joule-Thomson effects for charged AdS black holes. We obtain inversion temperatures and curves. We investigate similarities and differences between van der Waals fluids and charged AdS black holes for the expansion. We obtain isenthalpic curves for both systems in the T-P plane and determine the cooling-heating regions. (orig.)

Joule-Thomson expansion of the charged AdS black holes

Energy Technology Data Exchange (ETDEWEB)

Oekcue, Oezguer; Aydiner, Ekrem [Istanbul University, Department of Physics, Faculty of Science, Vezneciler, Istanbul (Turkey)

2017-01-15

In this paper, we study Joule-Thomson effects for charged AdS black holes. We obtain inversion temperatures and curves. We investigate similarities and differences between van der Waals fluids and charged AdS black holes for the expansion. We obtain isenthalpic curves for both systems in the T-P plane and determine the cooling-heating regions. (orig.)

From Joule to Caratheodory and Born: A Conceptual Evolution of the First Law of Thermodynamics

Science.gov (United States)

Rosenberg, Robert M.

2010-01-01

In the years after Joule's experiment on the equivalence of heat and work, it was taken for granted that heat and work could be independently defined and that the change in energy for a change of state is the sum of the heat and the work. Only with the work of Caratheodory and Born did it become clear that heat cannot be measured independently,…

Study of heat and mass transfer with Joule heating on magnetohydrodynamic (MHD peristaltic blood flow under the influence of Hall effect

Directory of Open Access Journals (Sweden)

M.M. Bhatti

2017-09-01

Full Text Available In this article, heat and mass transfer with Joule heating on magnetohydrodynamic (MHD peristaltic blood under the influence of Hall effect is examined. Mathematical modelling is based on momentum, energy and concentration which are taken into account using ohms law. The governing partial differential equations are further simplified by neglecting the inertial forces and long wavelength approximations. Exact solutions have been presented for velocity, temperature and concentration profile. The influence of all the physical pertinent parameters is taken into account with the help graphs. It is found that Hartmann number and Hall parameter shows opposite behaviour on velocity, temperature and concentration profile. It is worth mentioning that pressure rise also depicts opposite behaviour for Hartmann number and Hall parameter. The present analysis is also presented for Newtonian fluid (α→0 as a special case for our study. It is observed that Hall Effect and magnetic field shows opposite behaviour on velocity and temperature profile. Temperature profile increases due to the increment in Prandtl number and Eckert number. Numerical comparison is also presented between the existing published results by taking α=0,M=0 as a special case of our study.

Miniature Joule-Thomson cryocooling principles and practice

CERN Document Server

Maytal, Ben-Zion

2013-01-01

This book is the first in English being entirely dedicated to Miniature Joule-Thomson Cryocooling. The category of Joule-Thomson (JT) cryocoolers takes us back to the roots of cryogenics, in 1895, with figures like Linde and Hampson. The "cold finger" of these cryocoolers is compact, lacks moving parts, and sustains a large heat flux extraction at a steady temperature. Potentially, they cool down unbeatably fast. For example, cooling to below 100 K (minus 173 Celsius) might be accomplished within only a few seconds by liquefying argon. A level of about 120 K can be reached almost instantly with krypton. Indeed, the species of coolant plays a central role dictating the size, the intensity and the level of cryocooling. It is the JT effect that drives these cryocoolers and reflects the deviation of the "real" gas from the ideal gas properties. The nine chapters of the book are arranged in five parts. • The Common Principle of Cyrocoolers shared across the broad variety of cryocooler types • Theoretical Aspec...

Joule heating and spin-transfer torque investigated on the atomic scale using a spin-polarized scanning tunneling microscope.

Science.gov (United States)

Krause, S; Herzog, G; Schlenhoff, A; Sonntag, A; Wiesendanger, R

2011-10-28

The influence of a high spin-polarized tunnel current onto the switching behavior of a superparamagnetic nanoisland on a nonmagnetic substrate is investigated by means of spin-polarized scanning tunneling microscopy. A detailed lifetime analysis allows for a quantification of the effective temperature rise of the nanoisland and the modification of the activation energy barrier for magnetization reversal, thereby using the nanoisland as a local thermometer and spin-transfer torque analyzer. Both the Joule heating and spin-transfer torque are found to scale linearly with the tunnel current. The results are compared to experiments performed on lithographically fabricated magneto-tunnel junctions, revealing a very high spin-transfer torque switching efficiency in our experiments.

Off-gas characteristics of defense waste vitrification using liquid-fed Joule-heated ceramic melters

International Nuclear Information System (INIS)

Goles, R.W.; Sevigny, G.J.

1983-09-01

Off-gas and effluent characterization studies have been established as part of a PNL Liquid-Fed Ceramic Melter development program supporting the Savannah River Laboratory Defense Waste Processing Facility (SRL-DWPF). The objectives of these studies were to characterize the gaseous and airborne emission properties of liquid-fed joule-heated melters as a function of melter operational parameters and feed composition. All areas of off-gas interest and concern including effluent characterization, emission control, flow rate behavior and corrosion effects have been studied using alkaline and formic-acid based feed compositions. In addition, the behavioral patterns of gaseous emissions, the characteristics of melter-generated aerosols and the nature and magnitude of melter effluent losses have been established under a variety of feeding conditions with and without the use of auxiliary plenum heaters. The results of these studies have shown that particulate emissions are responsible for most radiologically important melter effluent losses. Melter-generated gases have been found to be potentially flammable as well as corrosive. Hydrogen and carbon monoxide present the greatest flammability hazard of the combustibles produced. Melter emissions of acidic volatile compounds of sulfur and the halogens have been responsible for extensive corrosion observed in melter plenums and in associated off-gas lines and processing equipment. The use of auxiliary plenum heating has had little effect upon melter off-gas characteristics other than reducing the concentrations of combustibles

Nanometer-scale temperature imaging for independent observation of Joule and Peltier effects in phase change memory devices.

Science.gov (United States)

Grosse, Kyle L; Pop, Eric; King, William P

2014-09-01

This paper reports a technique for independent observation of nanometer-scale Joule heating and thermoelectric effects, using atomic force microscopy (AFM) based measurements of nanometer-scale temperature fields. When electrical current flows through nanoscale devices and contacts the temperature distribution is governed by both Joule and thermoelectric effects. When the device is driven by an electrical current that is both periodic and bipolar, the temperature rise due to the Joule effect is at a different harmonic than the temperature rise due to the Peltier effect. An AFM tip scanning over the device can simultaneously measure all of the relevant harmonic responses, such that the Joule effect and the Peltier effect can be independently measured. Here we demonstrate the efficacy of the technique by measuring Joule and Peltier effects in phase change memory devices. By comparing the observed temperature responses of these working devices, we measure the device thermopower, which is in the range of 30 ± 3 to 250 ± 10 μV K(-1). This technique could facilitate improved measurements of thermoelectric phenomena and properties at the nanometer-scale.

Nanometer-scale temperature imaging for independent observation of Joule and Peltier effects in phase change memory devices

Energy Technology Data Exchange (ETDEWEB)

Grosse, Kyle L. [Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Pop, Eric [Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States); King, William P., E-mail: wpk@illinois.edu [Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Departments of Electrical and Computer Engineering and Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States)

2014-09-15

This paper reports a technique for independent observation of nanometer-scale Joule heating and thermoelectric effects, using atomic force microscopy (AFM) based measurements of nanometer-scale temperature fields. When electrical current flows through nanoscale devices and contacts the temperature distribution is governed by both Joule and thermoelectric effects. When the device is driven by an electrical current that is both periodic and bipolar, the temperature rise due to the Joule effect is at a different harmonic than the temperature rise due to the Peltier effect. An AFM tip scanning over the device can simultaneously measure all of the relevant harmonic responses, such that the Joule effect and the Peltier effect can be independently measured. Here we demonstrate the efficacy of the technique by measuring Joule and Peltier effects in phase change memory devices. By comparing the observed temperature responses of these working devices, we measure the device thermopower, which is in the range of 30 ± 3 to 250 ± 10 μV K{sup −1}. This technique could facilitate improved measurements of thermoelectric phenomena and properties at the nanometer-scale.

Dynamic modelling of the expansion cylinder of an open Joule cycle Ericsson engine: A bond graph approach

International Nuclear Information System (INIS)

Creyx, M.; Delacourt, E.; Morin, C.; Desmet, B.

2016-01-01

A dynamic model using the bond graph formalism of the expansion cylinder of an open Joule cycle Ericsson engine intended for a biomass-fuelled micro-CHP system is presented. Dynamic phenomena, such as the thermodynamic evolution of air, the instantaneous air mass flow rates linked to pressure drops crossing the valves, the heat transferred through the expansion cylinder wall and the mechanical friction losses, are included in the model. The influence on the Ericsson engine performances of the main operating conditions (intake air pressure and temperature, timing of intake and exhaust valve closing, rotational speed, mechanical friction losses and heat transfer at expansion cylinder wall) is studied. The operating conditions maximizing the performances of the Ericsson engine used in the a biomass-fuelled micro-CHP unit are an intake air pressure between 6 and 8 bar, a maximized intake air temperature, an adjustment of the intake and exhaust valve closing corresponding to an expansion cycle close to the theoretical Joule cycle, a rotational speed close to 800 rpm. The heat transfer at the expansion cylinder wall reduces the engine performances. - Highlights: • A bond graph dynamic model of the Ericsson engine expansion cylinder is presented. • Dynamic aspects are modelled: pressure drops, friction losses, wall heat transfer. • Influent factors and phenomena on the engine performances are investigated. • Expansion cycles close to the theoretical Joule cycle maximize the performances. • The heat transfer at the expansion chamber wall reduces the performances.

Performance Analysis of Joule-Thomson Cooler Supplied with Gas Mixtures

Science.gov (United States)

Piotrowska, A.; Chorowski, M.; Dorosz, P.

2017-02-01

Joule-Thomson (J-T) cryo-coolers working in closed cycles and supplied with gas mixtures are the subject of intensive research in different laboratories. The replacement of pure nitrogen by nitrogen-hydrocarbon mixtures allows to improve both thermodynamic parameters and economy of the refrigerators. It is possible to avoid high pressures in the heat exchanger and to use standard refrigeration compressor instead of gas bottles or high-pressure oil free compressor. Closed cycle and mixture filled Joule-Thomson cryogenic refrigerator providing 10-20 W of cooling power at temperature range 90-100 K has been designed and manufactured. Thermodynamic analysis including the optimization of the cryo-cooler mixture has been performed with ASPEN HYSYS software. The paper describes the design of the cryo-cooler and provides thermodynamic analysis of the system. The test results are presented and discussed.

Auroral energy input from energetic electrons and Joule heating at Chatanika

International Nuclear Information System (INIS)

Wickwar, V.B.; Baron, M.J.; Sears, R.D.

1975-01-01

With the incoherent scatter radar at Chatanika, Alaska, a wide variety of measurements can be made related to the ionosphere, magnetosphere, and neutral atmosphere. A significant parameter is the amount of energy transferred from the magnetosphere into the ionosphere and neutral atmosphere during periods of auroral activity. In this report a procedure is examined whereby the incident energy flux of auroral electrons is ascertained from radar measurements. As part of the process radar-determined fluxes are compared with those ascertained from simultaneous photometric observations at 4278 A. The fluxes obtained by both techniques had similar magnitudes and time variations. If it is assumed that the largest uncertainty in the radar/photometer comparison is the effective recombination coefficient, then that coefficient can also be deduced. A value 3times10 -7 cm 3 /s at about 105 km is found, which is in good agreement with other recent determinations during active auroral conditions. This technique is combined with one to ascertain the Joule heating to determine the energy input from the magnetosphere to the ionosphere in a region localized above the radar on March 22, 1973, in the midnight sector. The energy input is continuous at a significant level, i.e., greater than the 3 ergs/cm 2 that could be delivered by the sun, were it overhead. Moreover, at times, each of these inputs became as great as 30 ergs/cm 2 s

Application of Streaming Effect and Joule Heating Effect of Pulse Current in Crack Healing of Metal Materials

Directory of Open Access Journals (Sweden)

Jian Chu

2017-06-01

Full Text Available Remanufacture engineering is an emerging industry that saves resources as well as protects the environment. However, cracks on remanufactured components can result in serious trouble. Therefore, in order to avoid unnecessary waste of resources and energy, these cracks should be repaired radically in order to ensure the smooth progressing of the remanufacturing process. Consequently, the crack healing technique of metal materials is very important in the field of remanufacturing. In this study, the U-shape vane stainless steel of a centrifugal compressor which had cracks was processed by pulse current using a high pulse current discharge device, and the influence of the streaming effect and Joule heating effect of pulse current on the crack healing of metal materials was studied, aiming to provide references for the better application of this technology in the remanufacturing field in the future.

Thermodynamic optimization of mixed refrigerant Joule- Thomson systems constrained by heat transfer considerations

International Nuclear Information System (INIS)

Hinze, J F; Klein, S A; Nellis, G F

2015-01-01

Mixed refrigerant (MR) working fluids can significantly increase the cooling capacity of a Joule-Thomson (JT) cycle. The optimization of MRJT systems has been the subject of substantial research. However, most optimization techniques do not model the recuperator in sufficient detail. For example, the recuperator is usually assumed to have a heat transfer coefficient that does not vary with the mixture. Ongoing work at the University of Wisconsin-Madison has shown that the heat transfer coefficients for two-phase flow are approximately three times greater than for a single phase mixture when the mixture quality is between 15% and 85%. As a result, a system that optimizes a MR without also requiring that the flow be in this quality range may require an extremely large recuperator or not achieve the performance predicted by the model. To ensure optimal performance of the JT cycle, the MR should be selected such that it is entirely two-phase within the recuperator. To determine the optimal MR composition, a parametric study was conducted assuming a thermodynamically ideal cycle. The results of the parametric study are graphically presented on a contour plot in the parameter space consisting of the extremes of the qualities that exist within the recuperator. The contours show constant values of the normalized refrigeration power. This ‘map’ shows the effect of MR composition on the cycle performance and it can be used to select the MR that provides a high cooling load while also constraining the recuperator to be two phase. The predicted best MR composition can be used as a starting point for experimentally determining the best MR. (paper)

Joule-heated glass-furnace system for the incineration of low-level radioactive wastes

International Nuclear Information System (INIS)

Armstrong, K.M.; Klingler, L.M.; Doty, J.W.; Kramer, D.P.

1982-01-01

For the past 1-1/2 years, Mound has been preparing and evaluating a commercially available joule-heated glass furnace unit, coupled with a wet scrubbing system. The purpose of the glass furnace evaluation is to advance and document incinerator technology for such combustibles as solids, resins, and sludges, and to develop a stable waste form for subsequent disposal. Four (4) waste nonradioactive types were selected to determine the combustion efficiency of the furnace unit: (1) dry solid waste composed of paper, plastics, rubber, and cloth, (2) ion exchange resin of both the anionic and cationic type, (3) filter sludge composed of diatomaceous earth, organic cellulosic filter aid, and powdered ion exchange resin, and (4) cartridge filters having glass and plastic filter surfaces and nonmetallic cores. When completed, the combustion efficiency experiments for the proposed nonradioactive waste-types revealed the ability of the furnace to easily incinerate waste at feedrates of up to 150 lb/hr. During the course of the experiments, combustibles in the offgas remained consistently low, suggesting excellent combustion efficiency. Furthermore, ash produced by the combustion process was effectively incorporated into the melt by convective currents in the glass. Future work on the glass furnace incinerator will include spiking the waste to determine radioisotope behavior in the furnace

Simultaneous effects of slip and wall properties on MHD peristaltic motion of nanofluid with Joule heating

International Nuclear Information System (INIS)

Hayat, T.; Nisar, Z.; Ahmad, B.; Yasmin, H.

2015-01-01

This paper is devoted to the magnetohydrodynamic (MHD) peristaltic transport of nanofluid in a channel with wall properties. Flow analysis is addressed in the presence of viscous dissipation, partial slip and Joule heating effects. Mathematical modelling also includes the salient features of Brownian motion and thermophoresis. Both analytic and numerical solutions are provided. Comparison between the solutions is shown in a very good agreement. Attention is focused to the Brownian motion parameter, thermophoresis parameter, Hartman number, Eckert number and Prandtl number. Influences of various parameters on skin friction coefficient, Nusselt and Sherwood numbers are also investigated. It is found that both the temperature and nanoparticles concentration are increasing functions of Brownian motion and thermophoresis parameters. - Highlights: • Temperature rises when Brownian motion and thermophoresis effects intensify. • Temperature profile increases when thermal slip parameter increases. • Concentration field is a decreasing function of concentration slip parameter. • Temperature decreases whereas concentration increases for Hartman number

Simultaneous effects of slip and wall properties on MHD peristaltic motion of nanofluid with Joule heating

Energy Technology Data Exchange (ETDEWEB)

Hayat, T. [Department of Mathematics, Quaid-I-Azam University 45320, Islamabad 44000 (Pakistan); Nonlinear Analysis and Applied Mathematics (NAAM) Research Group, Department of Mathematics, King Abdulaziz University, P.O. Box 80257, Jeddah 21589 (Saudi Arabia); Nisar, Z. [Department of Mathematics, Quaid-I-Azam University 45320, Islamabad 44000 (Pakistan); Ahmad, B. [Nonlinear Analysis and Applied Mathematics (NAAM) Research Group, Department of Mathematics, King Abdulaziz University, P.O. Box 80257, Jeddah 21589 (Saudi Arabia); Yasmin, H., E-mail: qau2011@gmail.com [Department of Mathematics, COMSATS Institute of Information Technology, G.T. Road, Wah Cantt 47040 (Pakistan)

2015-12-01

This paper is devoted to the magnetohydrodynamic (MHD) peristaltic transport of nanofluid in a channel with wall properties. Flow analysis is addressed in the presence of viscous dissipation, partial slip and Joule heating effects. Mathematical modelling also includes the salient features of Brownian motion and thermophoresis. Both analytic and numerical solutions are provided. Comparison between the solutions is shown in a very good agreement. Attention is focused to the Brownian motion parameter, thermophoresis parameter, Hartman number, Eckert number and Prandtl number. Influences of various parameters on skin friction coefficient, Nusselt and Sherwood numbers are also investigated. It is found that both the temperature and nanoparticles concentration are increasing functions of Brownian motion and thermophoresis parameters. - Highlights: • Temperature rises when Brownian motion and thermophoresis effects intensify. • Temperature profile increases when thermal slip parameter increases. • Concentration field is a decreasing function of concentration slip parameter. • Temperature decreases whereas concentration increases for Hartman number.

Evaluation of a Novel Temperature Sensing Probe for Monitoring and Controlling Glass Temperature in a Joule-Heated Glass Melter

International Nuclear Information System (INIS)

Watkins, A. D.; Musick, C. A.; Cannon, C.; Carlson, N. M.; Mullenix, P.D.; Tillotson, R. D.

1999-01-01

A self-verifying temperature sensor that employs advanced contact thermocouple probe technology was tested in a laboratory-scale, joule-heated, refractory-lined glass melter used for radioactive waste vitrification. The novel temperature probe monitors melt temperature at any given level of the melt chamber. The data acquisition system provides the real-time temperature for molten glass. Test results indicate that the self-verifying sensor is more accurate and reliable than classic platinum/rhodium thermocouple and sheath assemblies. The results of this test are reported as well as enhancements being made to the temperature probe. To obtain more reliable temperature measurements of the molten glass for improving production efficiency and ensuring consistent glass properties, optical sensing was reviewed for application in a high temperature environment

Comparative investigation of five nanoparticles in flow of viscous fluid with Joule heating and slip due to rotating disk

Science.gov (United States)

Qayyum, Sumaira; Khan, Muhammad Ijaz; Hayat, Tasawar; Alsaedi, Ahmed

2018-04-01

Present article addresses the comparative study for flow of five water based nanofluids. Flow in presence of Joule heating is generated by rotating disk with variable thickness. Nanofluids are suspension of Silver (Ag), Copper (Cu), Copper oxide (CuO), Aluminum oxide or Alumina (Al2O3), Titanium oxide or titania (TiO2) and water. Boundary layer approximation is applied to partial differential equations. Using Von Karman transformations the partial differential equations are converted to ordinary differential equations. Convergent series solutions are obtained. Graphical results are presented to examine the behaviors of axial, radial and tangential velocities, temperature, skin friction and Nusselt number. It is observed that radial, axial and tangential velocities decay for slip parameters. Axial velocity decays for larger nanoparticle volume fraction. Effect of nanofluids on velocities dominant than base material. Temperature rises for larger Eckert number and temperature of silver water nanofluid is more because of its higher thermal conductivity. Surface drag force reduces for higher slip parameters. Transfer of heat is more for larger disk thickness index.

Influence of Ge on magnetic and structural properties of Joule-heated Co-based ribbons: Giant magnetoimpedance response

International Nuclear Information System (INIS)

Muraca, D.; Cremaschi, V.; Knobel, M.; Sirkin, H.

2008-01-01

Studies of magnetic and structural properties of Fe 3.5 Co 66.5 Si 12-x Ge x B 18 (x=0, 3, and 6) soft magnetic ribbons obtained by melt-spinning were performed. The samples were submitted to Joule-heating treatments with different maximum current values (0.01, 0.05, 0.1, 0.2, and 0.8 A, respectively) with steps of 0.01 A and times by step of 1, 2, and 10 s). X-ray diffraction, temperature dependence of magnetization (for the as-quenched samples), coercivity and giant magnetoimpedance (GMI), measured at different frequencies (100, 500, and 900 kHz, respectively) were performed. All the samples crystallized at annealing currents higher than 0.4 A, which was consistent with the magnetic hardening of the material. Coercivities less than 1 A/m were obtained for the three samples between 0.1 and 0.2 A. Maximum value of GMI response was observed for the sample without Ge in the as-quenched state

Continuum theory of the mixed-state and surface Joule effects in type-II superconductors

International Nuclear Information System (INIS)

Hocquet, T.; Mathieu, P.; Simon, Y.

1992-01-01

A phenomenological theory of vortex motion, where the mixed state is regarded as a continuum, has been proposed by two of the authors in a short previous letter. Its outlines are recalled in this paper with further comments and arguments; in particular the basic equations and their implications are discussed at some length. This theory leads to a model of pinning, from which we argue that critical currents I c , in soft type-II samples of standard bulk homogeneity, should be governed essentially by surface defects. I c is interpreted as a physically well-defined part of the total transport current I, which is flowing over a small depth close to the surface. Thus, on the scale of an ordinary sample, this part of the transport current is superficial, the remaining part I-I c being uniformly distributed over the cross section. Coherently, an analysis of the dissipation in such samples predicts that the part VI c of the total Joule effect VI must arise as surface heat sources, while the Joule effect V(I-I c ), usually associated with the steady viscous flow of vortices, is uniformly distributed in the bulk. As a proof, we present a method, using second-sound acoustics, to detect and separate surface and volume heat sources. Experimental results give clear evidence of a surface Joule effect, and support the validity of our model of surface pinning in soft materials

Polypyrrole/silver coaxial nanowire aero-sponges for temperature-independent stress sensing and stress-triggered Joule heating.

Science.gov (United States)

He, Weina; Li, Guangyong; Zhang, Shangquan; Wei, Yong; Wang, Jin; Li, Qingwen; Zhang, Xuetong

2015-04-28

To obtain ideal sensing materials with nearly zero temperature coefficient resistance (TCR) for self-temperature-compensated pressure sensors, we proposed an Incipient Network Conformal Growth (INCG) technology to prepare hybrid and elastic porous materials: the nanoparticles (NPs) are first dispersed in solvent to form an incipient network, another component is then introduced to coat the incipient network conformally via wet chemical route. The conformal coatings not only endow NPs with high stability but also offer them additional structural elasticity, meeting requirements for future generations of portable, compressive and flexible devices. The resultant polypyrrole/silver coaxial nanowire hybrid aero-sponges prepared via INCG technology have been processed into a piezoresistive sensor with highly sensing stability (low TCR 0.86 × 10(-3)/°C), sensitivity (0.33 kPa(-1)), short response time (1 ms), minimum detectable pressure (4.93 Pa) after suffering repeated stimuli, temperature change and electric heating. Moreover, a stress-triggered Joule heater can be also fabricated mainly by the PPy-Ag NW hybrid aero-sponges with nearly zero temperature coefficient.

A technical-scientific production of James Prescott Joule: a reading from the epistemology of Ludwik Fleck

Directory of Open Access Journals (Sweden)

Wellington Pereira de Queirós

2014-03-01

Full Text Available This paper aims an epistemologically analysis of the attempt of James Prescott Joule to replace the steam engine by the electric one. In this historical analysis, we use the epistemological categories: style of thinking, collective thinking, intercollective circulation of ideas and practices,Joule and other technicians in Machester received in that time financial incentives from governments and industry to replace the steam engine by the electric one, since it was in Manchester a culture of the technique of the accuracy and precision in which Joule was immersed, which allowed us to initially identify the styles of techniques thinking and experimental efficiency, However, Joule could not replace the steam engine by the electric; and the awareness of the problems faced by him, in the attempt to make such a substitution, led him to seek, through an intercollective circulation of ideas and practices, such as the studies of Faraday and Jacobi, a change of direction in his researches. According to our analysis, what happened was a change of style from a technical to a scientific thinking. In this sense, Joule began to investigate issues of a scientific nature, as the Joule’s effect and the mechanical equivalent of heat, which contributed significantly to the establishment of the principle of conservation of energy. We present here the contributions of this epistemological analysis to the discussion of questions of the nature of science in the basic education and for the training of physics teachers

Sensitivity of Micromachined Joule-Thomson Cooler to Clogging Due to Moisture

NARCIS (Netherlands)

Cao, Haishan; Vanapalli, Srinivas; Holland, Herman J.; Vermeer, Cristian Hendrik; ter Brake, Hermanus J.M.

2015-01-01

A major issue in long-term operation of micromachined Joule-Thomson coolers is the clogging of the microchannels and/or the restriction due to the deposition of water molecules present in the working fluid. In this study, we present the performance of a microcooler operated with nitrogen gas with

Numerical Study of the Magnetic Field Effects on the Heat Transfer and Entropy Generation Aspects of a Power Law Fluid over an Axisymmetric Stretching Plate Structure

Directory of Open Access Journals (Sweden)

Payam Hooshmand

2017-03-01

Full Text Available Numerical investigation of the effects of magnetic field strength, thermal radiation, Joule heating, and viscous heating on a forced convective flow of a non-Newtonian, incompressible power law fluid in an axisymmetric stretching sheet with variable temperature wall is accomplished. The power law shear thinning viscosity-shear rate model for the anisotropic solutions and the Rosseland approximation for the thermal radiation through a highly absorbing medium are considered. The temperature dependent heat sources, Joule heating, and viscous heating are considered as the source terms in the energy balance. The non-dimensional boundary layer equations are solved numerically in terms of similarity variable. A parameter study on the Nusselt number, viscous components of entropy generation, and thermal components of entropy generation in fluid is performed as a function of thermal radiation parameter (0 to 2, Brinkman number (0 to 10, Prandtl number (0 to 10, Hartmann number (0 to 1, power law index (0 to 1, and heat source coefficient (0 to 0.1.

Flower garden trees' ability to absorb solar radiation heat for local heat reduction

Science.gov (United States)

Maulana, Muhammad Ilham; Syuhada, Ahmad; Hamdani

2017-06-01

Banda Aceh as an urban area tends to have a high air temperature than its rural surroundings. A simple way to cool Banda Aceh city is by planting urban vegetation such as home gardens or parks. In addition to aesthetics, urban vegetation plays an important role as a reducer of air pollution, oxygen producer, and reducer of the heat of the environment. To create an ideal combination of plants, knowledge about the ability of plants to absorb solar radiation heat is necessary. In this study, some types of flowers commonly grown by communities around the house, such as Michelia Champaka, Saraca Asoka, Oliander, Adenium, Codiaeum Variegatum, Jas Minum Sambac, Pisonia Alba, Variegata, Apium Graveolens, Elephantopus Scaber, Randia, Cordylin.Sp, Hibiscus Rosasinensis, Agave, Lili, Amarilis, and Sesamum Indicum, were examined. The expected benefit of this research is to provide information for people, especially in Banda Aceh, on the ability of each plant relationship in absorbing heat for thermal comfort in residential environments. The flower plant which absorbs most of the sun's heat energy is Hibiscus Rosasinensis (kembang sepatu) 6.2 Joule, Elephantopus Scaber.L (tapak leman) 4.l Joule. On the other hand, the lowest heat absorption is Oliander (sakura) 0.9 Joule.

Conceptual design of a joule-heated ceramic melter for the DOE Fernald silos 1, 2, and 3 wastes

International Nuclear Information System (INIS)

Robinson, R.A.; Janke, D.S.; Peters, R.; Fekete, L.

1992-06-01

Vitrification of nuclear wastes has been under investigation since the mid-1950s. Most of the international communities experience has been with vitrification of high level nuclear wastes. In the US, this technology was developed by Battelle scientists at the DOEs Pacific Northwest Laboratories located at their Hanford site. Based on Laboratory and pilot-scale testing conducted at Hanford in the early 1970s, the DOE has constructed high level nuclear waste vitrification facilities at both Savannah River, South Carolina, and West Valley, New York, and is finalizing the design of a similar treatment facility at Hanford. Although these systems were designed to be fully remote due to the extreme radioactive hazards associated with this type of nuclear waste, technology transfer was successfully applied to the design of a vitrification process for the K-65 and uranium metal oxide wastes in a semi-remote operation at Fernald. This paper describes a conceptual design of a joule-heated, slurry-fed ceramic melter that was developed for vitrification of the DOE K-65 and metal oxide low level wastes at Fernald, Ohio

Heat dissipation research on the water-cooling channel of HL-2M in-vessel coils

Energy Technology Data Exchange (ETDEWEB)

Jiang, J., E-mail: jiangjiaming@swip.ac.cn; Liu, Y.; Chen, Q.; Ji, X.Q.

2017-04-15

Highlights: • The joule heat of in-vessel coils is very difficult to dissipate inside HL-2M vacuum vessel. • Heat dissipation model of the coil includes the joule heat model, the heat conduction model and the heat transfer model. • The CFD analysis has been done for the coil-water cooling, with comparison with the date of theoretical analysis and experiment. • The result shows water-cooling channel is good for the joule heat transfer and taken away. - Abstract: HL-2M in-vessel coils are positioned in high vacuum circumstance, and they will generate joule heat when they carry 15 kA electrical current, but joule heat is very difficult to dissipate in vacuum, so a hollow cable with 8 mm inner diameter is design as water-cooling channel for heat convection. By using the methods of the theoretical derivation, together with CFD numeric simulation method and the experiment of the heat transfer, the water channel of HL-2M in-vessel coils has been studied, and the temperature of HL-2M in-vessel coils under different cooling water flow rates is obtained and acceptable. Simultaneously, the external cooling water supply system parameters for the water-cooling channel of the coils are estimated. Three methods’ results are in good agreement; the theoretical model is verified and could be popularized for predicting the temperature rise of HL-2M in-vessel coils.

Joule-Thomson Coefficient for Strongly Interacting Unitary Fermi Gas

International Nuclear Information System (INIS)

Liao Kai; Chen Jisheng; Li Chao

2010-01-01

The Joule-Thomson effect reflects the interaction among constituent particles of macroscopic system. For classical ideal gas, the corresponding Joule-Thomson coefficient is vanishing while it is non-zero for ideal quantum gas due to the quantum degeneracy. In recent years, much attention is paid to the unitary Fermi gas with infinite two-body scattering length. According to universal analysis, the thermodynamical law of unitary Fermi gas is similar to that of non-interacting ideal gas, which can be explored by the virial theorem P = 2E/3V. Based on previous works, we further study the unitary Fermi gas properties. The effective chemical potential is introduced to characterize the nonlinear levels crossing effects in a strongly interacting medium. The changing behavior of the rescaled Joule-Thomson coefficient according to temperature manifests a quite different behavior from that for ideal Fermi gas. (general)

Joule heating effects on electromagnetohydrodynamic flow through a peristaltically induced micro-channel with different zeta potential and wall slip

Science.gov (United States)

Ranjit, N. K.; Shit, G. C.

2017-09-01

This paper aims to develop a mathematical model for magnetohydrodynamic flow of biofluids through a hydrophobic micro-channel with periodically contracting and expanding walls under the influence of an axially applied electric field. The velocity slip effects have been taken into account at the channel walls by employing different slip lengths due to hydrophobic gating. Different temperature jump factors have also been used to investigate the thermomechanical interactions at the fluid-solid interface. The electromagnetohydrodynamic flow in a microchannel is simplified under the framework of Debye-Hückel linearization approximation. We have derived the closed-form solutions for the linearized dimensionless boundary value problem under the assumptions of long wave length and low Reynolds number. The axial velocity, temperature, pressure distribution, stream function, wall shear stress and the Nusselt number have been appraised for diverse values of the parameters approaching into the problem. Our main focus is to determine the effects of different zeta potential on the axial velocity and temperature distribution under electromagnetic environment. This study puts forward an important observation that the different zeta potential plays an important role in controlling fluid velocity. The study further reveals that the temperature increases significantly with the Joule heating parameter and the Brinkman number (arises due to the dissipation of energy).

Heating experiments of JT-60

International Nuclear Information System (INIS)

1987-01-01

In JT-60, after the finish of the first stage Joule experiment, the heating facilities were installed, and the heating experiment was started in August, 1986. As to neutral beam injection, the beam injection experiment at the maximum rating 20 MW carried out, and also as to RF, the injection experiment up to 1.4 MW was carried out in both ion cyclotron and low band hybrid waves. The results worthy of special mention in the heating experiment were the success in the current drive up to 1.7 MA at maximum using low band hybrid waves and the improvement of plasma confinement characteristics obtained by the compound heating of NBI and RF. In this paper, the main results of these heating experiments and their significance are explained. The JT-60 is the testing facilities for attaining the critical plasma condition by additionally heating the plasma which is generated by Joule electric discharge with NBI and RF heatings. The experimental operation cycle of the JT-60 consists of the unit cycle of two weeks, and the number of days in operation is nine days. The temperature of heated plasma rose to 70 million deg C in the 20 MW NBI heating. Hereafter, the improvement of confinement time by increasing the stored energy of plasma is attempted. (Kako, I.)

MHD convective flow through porous medium in a horizontal channel with insulated and impermeable bottom wall in the presence of viscous dissipation and Joule heating

Directory of Open Access Journals (Sweden)

K.V.S. Raju

2014-06-01

Full Text Available This paper deals with a steady MHD forced convective flow of a viscous fluid of finite depth in a saturated porous medium over a fixed horizontal channel with thermally insulated and impermeable bottom wall in the presence of viscous dissipation and joule heating. The governing equations are solved in the closed form and the exact solutions are obtained for velocity and temperature distributions when the temperatures on the fixed bottom and on the free surface are prescribed. The expressions for flow rate, mean velocity, temperature, mean temperature, mean mixed temperature in the flow region and the Nusselt number on the free surface have been obtained. The cases of large and small values of porosity coefficients have been obtained as limiting cases. Further, the cases of small depth (shallow fluid and large depth (deep fluid are also discussed. The results are presented and discussed with the help of graphs.

Measurement and evaluation of EDM bearing currents by the normalized Joule integral

International Nuclear Information System (INIS)

Vidmar, Gregor; Miljavec, Damijan; Agrež, Dušan

2014-01-01

Apparent current density is the most common criterion used in literature to estimate bearing endangerment due to bearing currents. In the paper, a new criterion called the normalized Joule integral is proposed as a more reliable and accurate one. This approach is more general and gives good correlation between current in the bypass bridge and bearing current. Furthermore, it considers the whole current that causes bearing damage, not just its peak value. The choice of the normalized Joule integral is theoretically explained and supported by measurements and simulations. The levels of bearing endangerment related to the normalized Joule integral of bearing currents are estimated. (paper)

Joule heating induced thermomigration failure in un-powered microbumps due to thermal crosstalk in 2.5D IC technology

Energy Technology Data Exchange (ETDEWEB)

Li, Menglu; Tu, K. N., E-mail: kntu@ucla.edu [Department of Materials Science and Engineering, UCLA, Los Angeles, California 90095-1595 (United States); Kim, Dong Wook; Gu, Sam [Qualcomm, San Diego, California 92121 (United States); Parkinson, Dilworth Y.; Barnard, Harold [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

2016-08-21

Thermal-crosstalk induced thermomigration failure in un-powered microbumps has been found in 2.5D integrated circuit (IC) circuit. In 2.5D IC, a Si interposer was used between a polymer substrate and a device chip which has transistors. The interposer has no transistors. If transistors are added to the interposer chip, it becomes 3D IC. In our test structure, there are two Si chips placed horizontally on a Si interposer. The vertical connections between the interposer and the Si chips are through microbumps. We powered one daisy chain of the microbumps under one Si chip; however, the un-powered microbumps in the neighboring chip are failed with big holes in the solder layer. We find that Joule heating from the powered microbumps is transferred horizontally to the bottom of the neighboring un-powered microbumps, and creates a large temperature gradient, in the order of 1000 °C/cm, through the un-powered microbumps in the neighboring chip, so the latter failed by thermomigration. In addition, we used synchrotron radiation tomography to compare three sets of microbumps in the test structure: microbumps under electromigration, microbumps under thermomigration, and microbumps under a constant temperature thermal annealing. The results show that the microbumps under thermomigration have the largest damage. Furthermore, simulation of temperature distribution in the test structure supports the finding of thermomigration.

Craft-Joule Project: Stagnation proof transparently insulated flat plate solar collector (static)

Energy Technology Data Exchange (ETDEWEB)

Oliva, A; Cadafalch, J; Perez-Segarra, C.D. [Universitat Politecnica de Catalunya, Barcelona (Spain)] (and others)

2000-07-01

The STATIC (STAgnation proof Transparently Insulated flat plate Solar Collector) project is a Craft-Joule Project within the framework of the Non Nuclear Energy Programme Joule III coordinated by the Centre Technologic de Transferencia de Calor (CTTC). The core group of SMEs involved in the project has its main economical activity in the field of solar thermal systems at low temperature level (domestic hot water, solar heating, etc.). Beyond this, a large application potential exists for solar heating at medium temperature level (from 80 to 160 Celsius degrees) : industrial process heat, solar cooling and air conditioning, solar drying , distillation and desalination. Three of the four SME proposers are located in Southern Europe and in the Caribean, where a continuos increase of the demand for air conditioning and cooling has been demonstrated in the last years. The recent development of flat plate solar collectors with honeycomb-type transparent insulation cover has shown that this type of collectors can become a low cost alternative to evacuated tube and high concentrating CPC collectors in the medium temperature range from 80 to 160 Celsius degrees. With the expected reduction of collector cost, that forms 30%-50% of total system cost, a decisive break-through of solar thermal systems using heat in the medium temperature range can be achieved. The feasibility and good performance of these solar collectors has been proved in several prototypes. Nevertheless, up to now no commercial products are available. In order to reach this, the following developments of new concepts are necessary and are being carried out within this project: solution of the problem of overheating: development of collector versions for different working temperatures: optimization of the design with the support of high level numerical simulation. Several prototypes of the new solar collectors are being tested. System tests will also be carried or for two test arrays of optimized collector

Enhancing GMI properties of melt-extracted Co-based amorphous wires by twin-zone Joule annealing

Energy Technology Data Exchange (ETDEWEB)

Liu, J.S.; Cao, F.Y.; Xing, D.W.; Zhang, L.Y. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Qin, F.X. [Advanced Composite Center for Innovation and Science (ACCIS), Department of Aerospace Engineering, University of Bristol, University Walk, Bristol BS8 1TR (United Kingdom); Peng, H.X. [Advanced Composite Center for Innovation and Science (ACCIS), Department of Aerospace Engineering, University of Bristol, University Walk, Bristol BS8 1TR (United Kingdom); Centre for Nanoscience and Quantum Information, University of Bristol, Tyndall Avenue, Bristol BS8 1FD (United Kingdom); Xue, X. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Sun, J.F., E-mail: jfsun_hit@263.net [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)

2012-11-15

Highlights: Black-Right-Pointing-Pointer GMI effect is closely related to annealed microstructures observed by HRTEM. Black-Right-Pointing-Pointer Twin-zone Joule-heated annealing (TJHA) as a novel effective annealing treatment. Black-Right-Pointing-Pointer TJHA wires have relatively larger GMI ratio and field sensitivity. Black-Right-Pointing-Pointer From HRTEM perspective to explain the GMI peaks feature of different states wires. Black-Right-Pointing-Pointer TJHA wires are useful for high-resolution magnetic sensor applications. - Abstract: The influence of twin-zone Joule annealing (TJA) on the microstructure and magnetic properties of melt-extracted Co{sub 68.2}Fe{sub 4.3}B{sub 15}Si{sub 12.5} amorphous microwires has been investigated. Experimental results indicated that twin-zone Joule annealing treatment improved the GMI property of as-cast wires to a greater extent comparing with Joule annealing (JA) and conventional vacuum annealing (CVA) techniques. At 15 MHz, e.g., the maximum GMI ratio [{Delta}Z/Z{sub 0}]{sub max} of a TJA wire increases to 104.29%, which is more than 5 times of 20.49% for the as-cast wire, nearly two times of 56.47% for the JA wire, while the CVA wire has a decreased GMI ratio; the field response sensitivity of the TJA wire increased to 171.62%/Oe from 80.32%/Oe for the as-cast wire, exceeding the values of 140.76%/Oe for the JA wire and of 39.17%/Oe for the CVA wire. The stress or structural relaxation in TJA wire increases circumferential permeability, and magnetic moment achieves a critical state of excitation for overcoming eddy-current damping or 'nail-sticked' action in rotational magnetization process at relatively high frequency. From the microstructural point of view, the role of regularly arranged atomic micro-regions (RAAM) and of medium range order region (MROR) determines the efficiency of various annealing techniques. Conclusively, TJA is established as an efficient annealing technique to enhance the GMI effect

Model predictions for auxiliary heating in spheromaks

International Nuclear Information System (INIS)

Fauler, T.K.; Khua, D.D.

1997-01-01

Calculations are presented of the plasma temperature waited for under auxiliary heating in spheromaks. A model, ensuring good agreement of earlier experiments with joule heating results, is used. The model includes heat losses due to magnetic fluctuations and shows that the plasma temperatures of the kilo-electron-volt order may be achieved in a small device with the radius of 0.3 m only

Joule loss on a Faraday shield of JT-60 ICRF test antenna

International Nuclear Information System (INIS)

Fujii, Tsuneyuki; Saigusa, Mikio; Ikeda, Yoshitaka; Kimura, Haruyuki; Hirashima, Teruhisa; Uehara, Munenori.

1988-01-01

Joule loss on a Faraday shield of JT-60 ICRF test antenna with a conductive casing is investigated at the frequency range of 120 MHz. The magnetic field radiated from the antenna is measured by three-dimensionally scanning an rf probe both inside and outside the antenna casing. The magnetic field perpendicular to the Faraday shield, B x , is found to be the largest component near the Faraday shield. It consequently gives the major part of the joule loss on the Faraday shield. The temperature distribution of the Faraday shield due to joule loss is measured directly with a thermocamera. It is confirmed that the area of the high temperature rise is consistent with the peak positions of the B x field. Faraday shield resistance which is estimated from power measurements agrees with the theoretical value. (author)

Uncertainty evaluation for ordinary least-square fitting with arbitrary order polynomial in joule balance method

International Nuclear Information System (INIS)

You, Qiang; Xu, JinXin; Wang, Gang; Zhang, Zhonghua

2016-01-01

The ordinary least-square fitting with polynomial is used in both the dynamic phase of the watt balance method and the weighting phase of joule balance method but few researches have been conducted to evaluate the uncertainty of the fitting data in the electrical balance methods. In this paper, a matrix-calculation method for evaluating the uncertainty of the polynomial fitting data is derived and the properties of this method are studied by simulation. Based on this, another two derived methods are proposed. One is used to find the optimal fitting order for the watt or joule balance methods. Accuracy and effective factors of this method are experimented with simulations. The other is used to evaluate the uncertainty of the integral of the fitting data for joule balance, which is demonstrated with an experiment from the NIM-1 joule balance. (paper)

Electromagnetohydrodynamic flow of blood and heat transfer in a capillary with thermal radiation

International Nuclear Information System (INIS)

Sinha, A.; Shit, G.C.

2015-01-01

This paper presents a comprehensive theoretical study on heat transfer characteristics together with fully developed electromagnetohydrodynamic flow of blood through a capillary, having electrokinetic effects by considering the constant heat flux at the wall. The effect of thermal radiation and velocity slip condition have been taken into account. A rigorous mathematical model for describing Joule heating in electro-osmotic flow of blood including the Poisson–Boltzmann equation, the momentum equation and the energy equation is developed. The alterations in the thermal transport phenomenon, induced by the variation of imposed electromagnetic effects, are thoroughly explained through an elegant mathematical formalism. Results presented here pertain to the case where the height of the capillary is much greater than the thickness of electrical double layer comprising the stern and diffuse layers. The essential features of the electromagnetohydrodynamic flow of blood and associated heat transfer characteristics through capillary are clearly highlighted by the variations in the non-dimensional parameters for velocity profile, temperature profile and the Nusselt number. The study reveals that the temperature of blood can be controlled by regulating Joule heating parameter. - Highlights: • Electromagnetohydrodynamic flow of blood in capillary is studied. • Potential electric field is applied for driving elecroosmotic flow of blood. • Effect of thermal radiation, Joule heating and velocity slip is investigated. • Thermal radiation bears the significant change in the temperature field

Electromagnetohydrodynamic flow of blood and heat transfer in a capillary with thermal radiation

Energy Technology Data Exchange (ETDEWEB)

Sinha, A. [Department of Mathematics, Jadavpur University, Kolkata 700032 (India); Shit, G.C., E-mail: gopal_iitkgp@yahoo.co.in [Department of Mathematics, Jadavpur University, Kolkata 700032 (India); Institute of Mathematical Sciences, Chennai 600113 (India)

2015-03-15

This paper presents a comprehensive theoretical study on heat transfer characteristics together with fully developed electromagnetohydrodynamic flow of blood through a capillary, having electrokinetic effects by considering the constant heat flux at the wall. The effect of thermal radiation and velocity slip condition have been taken into account. A rigorous mathematical model for describing Joule heating in electro-osmotic flow of blood including the Poisson–Boltzmann equation, the momentum equation and the energy equation is developed. The alterations in the thermal transport phenomenon, induced by the variation of imposed electromagnetic effects, are thoroughly explained through an elegant mathematical formalism. Results presented here pertain to the case where the height of the capillary is much greater than the thickness of electrical double layer comprising the stern and diffuse layers. The essential features of the electromagnetohydrodynamic flow of blood and associated heat transfer characteristics through capillary are clearly highlighted by the variations in the non-dimensional parameters for velocity profile, temperature profile and the Nusselt number. The study reveals that the temperature of blood can be controlled by regulating Joule heating parameter. - Highlights: • Electromagnetohydrodynamic flow of blood in capillary is studied. • Potential electric field is applied for driving elecroosmotic flow of blood. • Effect of thermal radiation, Joule heating and velocity slip is investigated. • Thermal radiation bears the significant change in the temperature field.

Harmonisation of wind turbine certification in Europe JOULE project EWTC

Energy Technology Data Exchange (ETDEWEB)

Nath, C [Germanischer Lloyd, Hamburg (Germany); Eriksson, C [Det Norske Veritas, Hellerup (Denmark); Hulle, F van [Frans van Hulle, Petten (Netherlands); Skamris, C [Risoe National Lab., Roskilde (Denmark); Stam, W [CIWI Holland, Arnheim (Netherlands); Vionis, P [CRES, Attki (Greece)

1999-03-01

Wind turbine certification requirements are currently fairly divers within Europe. Therefore the leading European certification bodies initiated a JOULE project to harmonise the certification procedure on the basis of the current set of IEC/EN 61400 series standards. The paper presents a review of the state of the art of wind turbine certification in European countries and an outline of the sturcture of the project. The main steps of the project are (a) the collection of differences in certification practices by round robin certification of three wind turbine types; (b) assessment of the different certification results and (c) the development of a harmonised certification procedure. (au) EU-JOULE-3. 19 refs.

Electrical service and controls for Joule heating of a defense waste experimental glass melter

International Nuclear Information System (INIS)

Erickson, C.J.; Haideri, A.Q.

1983-01-01

Vitrification of radioactive liquid waste in a glass matrix is a leading candidate for long-term storage of high-level waste. This paper describes the electrical service and control system for an experimental electrically heated, nonradioactive glass melter installed at Savannah River Laboratory. Data accumulated, and design/operating experience acquired in operating this melter, are being used to design a modified melter to be installed in a processing area for use with radioactive materials

An electrical-heating and self-sensing shape memory polymer composite incorporated with carbon fiber felt

International Nuclear Information System (INIS)

Gong, Xiaobo; Leng, Jinsong; Liu, Liwu; Liu, Yanju

2016-01-01

Shape memory polymers (SMPs) have the ability to adjust their stiffness, lock a temporary shape, and recover the permanent shape upon imposing an appropriate stimulus. They have found their way into the field of morphing structures. The electrically Joule resistive heating of the conductive composite can be a desirable stimulus to activate the shape memory effect of SMPs without external heating equipment. Electro-induced SMP composites incorporated with carbon fiber felt (CFF) were explored in this work. The CFF is an excellent conductive filler which can easily spread throughout the composite. It has a huge advantage in terms of low cost, simple manufacturing process, and uniform and tunable temperature distribution while heating. A continuous and compact conductive network made of carbon fibers and the overlap joints among them was observed from the microscopy images, and this network contributes to the high conductive properties of the CFF/SMP composites. The CFF/SMP composites can be electrical-heated rapidly and uniformly, and its’ shape recovery effect can be actuated by the electrical resistance Joule heating of the CFF without an external heater. The CFF/SMP composite get higher modulus and higher strength than the pure SMP without losing any strain recovery property. The high dependence of temperature and strain on the electrical resistance also make the composite a good self-sensing material. In general, the CFF/SMP composite shows great prospects as a potential material for the future morphing structures. (paper)

Study on fabrication methods of composite structures (1st. report); Joule effect curing of CFRP composite structures and its application to bonding and repair. Fukugo zai kozo no seikei kako ho ni kansuru kenkyu (Dai 1po); CFRP kozo no Joule koka wo riyo shita cure ho to setsugoter dot hoshu e no oyo ni tsuite

Energy Technology Data Exchange (ETDEWEB)

Moriya, K. (The National Defense Academy, Kanagawa (Japan))

1990-07-05

A method for curing CFRP composite structures by using Joule effect is presented. Due to the presence of fiber to fiber contact, CFRP composites and their prepregs exhibit electrical conductivity in the direction transverse to fibers as well as in the fiber direction, and they can be considered as electrically homogeneous on a gross scale. Therefore, passing an electric current through a CFRP prepreg, it is self-heated due to the Joule effect. Feedback current control maintains the prepreg temperature at a desired level and makes the prepreg be cured by a specified cure cycle. Experimental verifiactions have been carried out to demonstrate the feasibility of the present technique. The applications to the bonding of CFRP components and to the patch repairs of effective CFRP structure are also described. 12 refs., 12 figs.

The RF voltage dependence of the electron sheath heating in low pressure capacitively coupled rf discharges

International Nuclear Information System (INIS)

Buddemeier, U.; Kortshagen, U.; Pukropski, I.

1995-01-01

In low pressure capacitively coupled RF discharges two competitive electron heating mechanisms have been discussed for some time now. At low pressures the stochastic sheath heating and for somewhat higher pressures the Joule heating in the bulk plasma have been proposed. When the pressure is increased at constant RF current density a transition from concave electron distribution functions (EDF) with a pronounced cold electron group to convex EDFs with a missing strong population of cold electrons is found. This transition was interpreted as the transition from dominant stochastic to dominant Joule heating. However, a different interpretation has been given by Kaganovich and Tsendin, who attributed the concave shaped EDFs to the spatially inhomogeneous RF field in combination with the nonlocality of the EDF

Effect of Anode Change on Heat Transfer and Magneto-hydrodynamic Flow in Aluminum Reduction Cell

Science.gov (United States)

Wang, Qiang; Li, Baokuan; Fafard, Mario

2016-02-01

In order to explore the impact of anode replacement on heat transfer and magneto-hydrodynamic flow in aluminum smelting cells, a transient three-dimensional coupled mathematical model has been developed. With a steady state magnetic field, an electrical potential approach was used to obtain electromagnetic fields. Joule heating and Lorentz force, which were the source terms in the energy and momentum equations, were updated at each iteration. The phase change of molten electrolyte (bath) was modeled by an enthalpy-based technique in which the mushy zone was treated as a porous medium with porosity equal to the liquid fraction. A reasonable agreement between the test data and simulated results was achieved. Under normal conditions, the bath at the middle of the cell is hotter, while becoming colder at the four corners. Due to the heat extracted from the bath, the temperature of the new cold anode increases over time. The temperature of the bath under the new cold anode therefore quickly drops, resulting in a decrease of the electrical conductivity. More Joule effect is created. In addition, the bath under the new cold anode gradually freezes and flows more slowly. The temperature of the new anode located at the middle of the cell rises faster because of the warmer bath. It is easier to eliminate the effect of anode change when it occurs in the middle of the cell.

Resistive heating enhanced soil vapor extraction of chlorinated solvents from trichloroethylene contaminated silty, low permeable soil

NARCIS (Netherlands)

Zutphen, M. van; Heron, G.; Enfield, C.G.; Christensen, T.H.

1998-01-01

A 2D-laboratory box experiment (12 x 56 x 116 cm) was conducted to simulate the enhancement of soil vapor extraction by the application of low frequency electrical heating Uoule heating) for the remediation of a low permeable, silty soil contaminated with trichloroethylene. Joule heating enlarged

Recent research on magnetic properties of glass-coated microwires

International Nuclear Information System (INIS)

Zhukov, A.; Zhukova, V.; Blanco, J.M.; Gonzalez, J.

2005-01-01

In this paper, we report and analyse the results of tailoring the GMI effect of glass-coated amorphous thin microwires (with the metallic nucleus diameter about 10-22 μm) by choosing the sample chemical composition, geometry (thickness of glass coating) and conditions of heat treatment by Joule heating and furnace annealing. The observed dependencies have been interpreted in terms of stress relaxation and changes of the magneto-elastic anisotropy induced by the Joule heating

Review of laser mega joule target area: Design and processes

International Nuclear Information System (INIS)

Geitzholz, M.; Lanternier, C.

2006-01-01

The Laser Mega Joule (LMJ) target area is currently designed to achieve ignition and significant fusion gain in laboratory. LMJ will be composed of 240 identical large 370 mm * 370 mm square laser beams. These beams will focus 2 mega-joules of energy at the wavelength of 351 nm on the center of an experiment chamber. Design studies for target equipment are well advanced, target chamber and target holder (concrete) works have already begun. A detailed overview of the target area equipment is presented: target chamber, frame, diagnostic inserter manipulator, final optic assembly, dual diagnostic and laser reference, non cryogenic target positioner. Recent technical and architectural choices are detailed including safety transfers and alignment processes (target, laser and diagnostic). All this target equipment allows us to optimize shot chrono-gram, from target metrology to the shot, including calibration process. (authors)

Micromachined Joule-Thomson coolers for cooling low-temperature detectors and electronics

Science.gov (United States)

ter Brake, Marcel; Lerou, P. P. P. M.; Burger, J. F.; Holland, H. J.; Derking, J. H.; Rogalla, H.

2017-11-01

The performance of electronic devices can often be improved by lowering the operating temperature resulting in lower noise and larger speed. Also, new phenomena can be applied at low temperatures, as for instance superconductivity. In order to fully exploit lowtemperature electronic devices, the cryogenic system (cooler plus interface) should be `invisible' to the user. It should be small, low-cost, low-interference, and above all very reliable (long-life). The realization of cryogenic systems fulfilling these requirements is the topic of research of the Cooling and Instrumentation group at the University of Twente. A MEMS-based cold stage was designed and prototypes were realized and tested. The cooler operates on basis of the Joule-Thomson effect. Here, a high-pressure gas expands adiabatically over a flow restriction and thus cools and liquefies. Heat from the environment (e.g., an optical detector) can be absorbed in the evaporation of the liquid. The evaporated working fluid returns to the low-pressure side of the system via a counter-flow heat exchanger. In passing this heat exchanger, it takes up heat from the incoming high-pressure gas that thus is precooled on its way to the restriction. The cold stage consists of a stack of three glass wafers. In the top wafer, a high-pressure channel is etched that ends in a flow restriction with a height of typically 300 nm. An evaporator volume crosses the center wafer into the bottom wafer. This bottom wafer contains the lowpressure channel thus forming a counter-flow heat exchanger. A design aiming at a net cooling power of 10 mW at 96 K and operating with nitrogen as the working fluid was optimized based on the minimization of entropy production. The optimum cold finger measures 28 mm x 2.2 mm x 0.8 mm operating with a nitrogen flow of 1 mg/s at a high pressure of 80 bar and a low pressure of 6 bar. The design and fabrication of the coolers will be discussed along with experimental results.

Catalytic heat exchangers - a long-term evaluation

Energy Technology Data Exchange (ETDEWEB)

Silversand, Fredrik A. [CATATOR AB, Lund (Sweden)

2003-10-01

A long-term evaluation concerning catalytic heat exchangers (CHEs) has been performed. The idea concerning CHEs was originally described in a number of reports issued by Catator almost a decade ago. The general idea with CHEs is to combust a fuel with a catalyst inside a heat exchanger to enable an effective heat transfer. The first design approaches demonstrated the function and the possibilities with CHEs but were defective concerning the heat exchanger design. Consequently, a heat exchanger company (SWEP International AB), which was specialised on brazed plate-type heat exchangers, joined the continued development project. Indeed, the new design approach containing Catator's wire-mesh catalysts and SWEP's plate-type heat exchangers enabled us to improve the concept considerably. The new design complied with a number of relevant technical demands, e.g.: Simplicity; Compactness and integration (few parts); High thermal efficiency; Low pressure drop; Excellent emissions; High turn-down ratio; Reasonable production cost. Spurred by the technical progresses, the importance of a long-term test under realistic conditions was clear. A long-term evaluation was initialised at Sydkraft Gas premises in Aastorp. The CHE was installed on a specially designed rig to enable accelerated testing with respect to the number of transients. The rig was operated continuously for 5000 hours and emission mapping was carried out at certain time intervals. Following some problems during the initial phase of the long-term evaluation, which unfortunately also delayed the project, the results indicated very stable conditions of operation. The emissions have been rather constant during the course of the test and we cannot see any tendencies to decreased performances. Indeed, the test verifies the function, operability and reliability of the CHE-concept. Apart from domestic boilers we foresee a number of interesting and relevant applications in heating and process technology. Since

Heating of microprotrusions in accelerating structures

Directory of Open Access Journals (Sweden)

A. C. Keser

2013-09-01

Full Text Available The thermal and field emission of electrons from protrusions on metal surfaces is a possible limiting factor on the performance and operation of high-gradient room temperature accelerator structures. We present here the results of extensive numerical simulations of electrical and thermal behavior of protrusions. We unify the thermal and field emission in the same numerical framework, describe bounds for the emission current and geometric enhancement, then we calculate the Nottingham and Joule heating terms and solve the heat equation to characterize the thermal evolution of emitters under rf electric field. Our findings suggest that heating is entirely due to the Nottingham effect. The time dependence of the rf field leads to a time dependent tip temperature with excursion that depends weakly on rf frequency. We build a phenomenological model to account for the effect of space charge and show that space charge eliminates the possibility of copper tip melting for tips with radii less than 10  μm with vacuum fields on their surface less than 12  GV/m, and for rf frequencies above 1 GHz.

Watt and joule balances

Science.gov (United States)

Robinson, Ian A.

2014-04-01

The time is fast approaching when the SI unit of mass will cease to be based on a single material artefact and will instead be based upon the defined value of a fundamental constant—the Planck constant—h . This change requires that techniques exist both to determine the appropriate value to be assigned to the constant, and to measure mass in terms of the redefined unit. It is important to ensure that these techniques are accurate and reliable to allow full advantage to be taken of the stability and universality provided by the new definition and to guarantee the continuity of the world's mass measurements, which can affect the measurement of many other quantities such as energy and force. Up to now, efforts to provide the basis for such a redefinition of the kilogram were mainly concerned with resolving the discrepancies between individual implementations of the two principal techniques: the x-ray crystal density (XRCD) method [1] and the watt and joule balance methods which are the subject of this special issue. The first three papers report results from the NRC and NIST watt balance groups and the NIM joule balance group. The result from the NRC (formerly the NPL Mk II) watt balance is the first to be reported with a relative standard uncertainty below 2 × 10-8 and the NIST result has a relative standard uncertainty below 5 × 10-8. Both results are shown in figure 1 along with some previous results; the result from the NIM group is not shown on the plot but has a relative uncertainty of 8.9 × 10-6 and is consistent with all the results shown. The Consultative Committee for Mass and Related Quantities (CCM) in its meeting in 2013 produced a resolution [2] which set out the requirements for the number, type and quality of results intended to support the redefinition of the kilogram and required that there should be agreement between them. These results from NRC, NIST and the IAC may be considered to meet these requirements and are likely to be widely debated

Natural convection in porous media with heat generation

International Nuclear Information System (INIS)

Hardee, H.C. Jr.; Nilson, R.H.

1976-12-01

Heat transfer characteristics of a fluid saturated porous media are investigated for the case of uniform internal heat generation with cooling from above. Analytical models of conduction and single phase cellular convection show good agreement with previous Rayleigh number correlations and with experimental data obtained by Joule heating of salt water in a sand bed. An approximate dryout criterion is also derived for two phase boiling heat transfer in a fixed bed which is neither channeled nor fluidized. Correlation of dryout data using this criterion is encouraging, especially considering the analytical rather than correlational basis of the criterion

Joule-Thief Circuit Performance for Electricity Energy Saving of Emergency Lamps

Science.gov (United States)

Nuryanto Budisusila, Eka; Arifin, Bustanul

2017-04-01

The alternative energy such as battery as power source is required as energy source failures. The other need is outdoor lighting. The electrical power source is expected to be a power saving, optimum and has long life operating. The Joule-Thief circuit is one of solution method for energy saving by using raised electromagnetic force on cored coil when there is back-current. This circuit has a transistor operated as a switch to cut voltage and current flowing along the coils. The present of current causing magnetic induction and generates energy. Experimental prototype was designed by using battery 1.5V to activate Light Emitting Diode or LED as load. The LED was connected in parallel or serial circuit configuration. The result show that the joule-thief circuit able to supply LED circuits up to 40 LEDs.

FY 2009 Annual Report of Joule Software Metric SC GG 3.1/2.5.2, Improve Computational Science Capabilities

Energy Technology Data Exchange (ETDEWEB)

Kothe, Douglas B [ORNL; Roche, Kenneth J [ORNL; Kendall, Ricky A [ORNL

2010-01-01

The Joule Software Metric for Computational Effectiveness is established by Public Authorizations PL 95-91, Department of Energy Organization Act, and PL 103-62, Government Performance and Results Act. The U.S. Office of Management and Budget (OMB) oversees the preparation and administration of the President s budget; evaluates the effectiveness of agency programs, policies, and procedures; assesses competing funding demands across agencies; and sets the funding priorities for the federal government. The OMB has the power of audit and exercises this right annually for each federal agency. According to the Government Performance and Results Act of 1993 (GPRA), federal agencies are required to develop three planning and performance documents: 1.Strategic Plan: a broad, 3 year outlook; 2.Annual Performance Plan: a focused, 1 year outlook of annual goals and objectives that is reflected in the annual budget request (What results can the agency deliver as part of its public funding?); and 3.Performance and Accountability Report: an annual report that details the previous fiscal year performance (What results did the agency produce in return for its public funding?). OMB uses its Performance Assessment Rating Tool (PART) to perform evaluations. PART has seven worksheets for seven types of agency functions. The function of Research and Development (R&D) programs is included. R&D programs are assessed on the following criteria: Does the R&D program perform a clear role? Has the program set valid long term and annual goals? Is the program well managed? Is the program achieving the results set forth in its GPRA documents? In Fiscal Year (FY) 2003, the Department of Energy Office of Science (DOE SC-1) worked directly with OMB to come to a consensus on an appropriate set of performance measures consistent with PART requirements. The scientific performance expectations of these requirements reach the scope of work conducted at the DOE national laboratories. The Joule system

Post-CHF low-void heat transfer of water: measurements in the complete transition boiling region at atmospheric pressure

International Nuclear Information System (INIS)

Johannsen, K.; Meinen, W.

1984-01-01

An experimental investigation of low-void heat transfer of water has been performed in the range of CHF and the minimum stable film boiling temperature. The heat transfer system used consists of a vertically mounted copper tube of 1 cm I.D. and 5 cm length with surface-temperature controlled, indirect Joule heating. Results are presented for upflowing water at inverted annular flow conditions in the inlet subcooling range of 2.5 - 40 0 C and mass flux range of 137-600 kg/m 2 s in terms of boiling curves and heat transfer coefficients versus wall temperature. Heat transfer in the stationary rewetting front, which occurs within the test section during operation in the transition boiling mode, is also dealt with. At high mass flux, occurrence of an inverse rewetting front has been observed. It is also noted that, at fixed location, minimum heat flux observed is usually not associated with the minimum stable film boiling temperature

Ionospheric heating with oblique high-frequency waves

International Nuclear Information System (INIS)

Field, E.C. Jr.; Bloom, R.M.; Kossey, P.A.

1990-01-01

This paper presents calculations of ionospheric electron temperature and density perturbations and ground-level signal changes produced by intense oblique high-frequency (HF) radio waves. The analysis takes into account focusing at caustics, the consequent Joule heating of the surrounding plasma, heat conduction, diffusion, and recombination processes, these being the effects of a powerful oblique modifying wave. It neglects whatever plasma instabilities might occur. The authors then seek effects on a secondary test wave that is propagated along the same path as the first. The calculations predict ground-level field strength reductions of several decibels in the test wave for modifying waves having effective radiated power (ERP) in the 85- to 90-dBW range. These field strength changes are similar in sign, magnitude, and location to ones measured in Soviet experiments. The location of the signal change is sensitive to the frequency and the model ionosphere assumed; so future experiments should employ the widest possible range of frequencies and propagation conditions. An ERP of 90 dBW seems to be a sort of threshold that, if exceeded, might result in substantial rather than small signal changes. The conclusions are based solely on Joule heating and subsequent refraction of waves passing through caustic regions

Analytical models of Ohmic heating and conventional heating in food processing

Science.gov (United States)

Serventi, A.; Bozzoli, F.; Rainieri, S.

2017-11-01

Ohmic heating is a food processing operation in which an electric current is passed through a food and the electrical resistance of the food causes the electric power to be transformed directly into heat. The heat is not delivered through a surface as in conventional heat exchangers but it is internally generated by Joule effect. Therefore, no temperature gradient is required and it origins quicker and more uniform heating within the food. On the other hand, it is associated with high energy costs and its use is limited to a particular range of food products with an appropriate electrical conductivity. Sterilization of foods by Ohmic heating has gained growing interest in the last few years. The aim of this study is to evaluate the benefits of Ohmic heating with respect to conventional heat exchangers under uniform wall temperature, a condition that is often present in industrial plants. This comparison is carried out by means of analytical models. The two different heating conditions are simulated under typical circumstances for the food industry. Particular attention is paid to the uniformity of the heat treatment and to the heating section length required in the two different conditions.

Implementation of short-term prediction

Energy Technology Data Exchange (ETDEWEB)

Landberg, L; Joensen, A; Giebel, G [and others

1999-03-01

This paper will giver a general overview of the results from a EU JOULE funded project (`Implementing short-term prediction at utilities`, JOR3-CT95-0008). Reference will be given to specialised papers where applicable. The goal of the project was to implement wind farm power output prediction systems in operational environments at a number of utilities in Europe. Two models were developed, one by Risoe and one by the Technical University of Denmark (DTU). Both prediction models used HIRLAM predictions from the Danish Meteorological Institute (DMI). (au) EFP-94; EU-JOULE. 11 refs.

Heat transfer in a magnet C

International Nuclear Information System (INIS)

Sircilli Neto, F.; Passaro, A.; Borges, E.M.

1991-01-01

The cooling systems of nuclear reactors for spacial applications include direct current electromagnetic pumps, which are used to circulate the coolant fluid thru the reactor core. In this work, the transfer of the heat generated by the electrical current in a magnet C excitation coils, which is used in a prototype pump, was evaluated. Considering the processes of heat transfer by conduction, natural convection and radiation, the results of simulation with the codes HEATING5 and AUTHEATS indicate the utilization of the 180 sup(0)C thermal class conductor for a working Joule power of 4 10 sup(4) W/m sup(3) in each magnet coil. (author)

Three-dimensional model of heat transport during In Situ Vitrification with melting and cool down

International Nuclear Information System (INIS)

Hawkes, G.L.

1993-01-01

A potential technology for permanent remediation of buried wastes is the In Situ Vitrification (ISV) process. This process uses electrical resistance heating to melt waste and contaminated soil in place to produce a durable, glasslike material that encapsulates and immobilizes buried wastes. The magnitude of the resulting electrical resistance heating is sufficient to cause soil melting. As the molten region grows, surface heat losses cause the soil near the surface to re solidify. This paper presents numerical results obtained by considering heat transport and melting when solving the conservation of mass and energy equations using finite element methods. A local heat source is calculated by solving the electric field equation and calculating a Joule Heat source term. The model considered is a three-dimensional model of the electrodes and surrounding soil. Also included in the model is subsidence; where the surface of the melted soil subsides due to the change in density when the soil melts. A power vs. time profile is implemented for typical ISV experiments. The model agrees well with experimental data for melt volume and melt shape

Power line conductor icing prevention by the Joule effect : parametric analysis and energy requirements

Energy Technology Data Exchange (ETDEWEB)

Peter, Z.; Farzaneh, M.; Kiss, L.I. [Quebec Univ., Chicoutimi, PQ (Canada). Industrial Chair on Atmospheric Icing of Power Network Equipment

2005-07-01

A mathematical model to calculate the minimum current intensity needed to prevent potentially damaging ice accretion on power line conductors was presented. The influence of atmospheric parameters such as wind speed, air temperature and liquid water were considered. Energy analysis was developed for an aluminum and steel reinforced conductor with circular cylindrical wire and concentric layers. Atmospheric parameters and the duration of the freezing conditions were considered with reference to the Joule effect. The model was then compared with experiments and simulations performed at an icing wind tunnel and in a climate room. It was determined that the equivalent thermal conductivity of the conductor should be assessed to identify the temperature distribution in the power line conductor. The radial component of the thermal conductivity was estimated on the basis of experiments performed in the wind tunnel, which provided a good estimation of the equivalent thermal conductivity and overall heat transfer coefficient around the stranded conductor. Experimental results were compared with values obtained from theoretically equivalent conductivity models. It was observed that the convective heat transfer coefficients around stranded conductors were higher than around smooth cylinders, and that the mathematical calculations slightly overestimated the wind tunnel measurements due to difficulties in estimating the wetted surface and the overall convection heat transfer coefficient around a stranded conductor. The typical range for the equivalent thermal conductivity of stranded conductors was also presented. 13 refs., 1 tab., 11 figs.

Flow boiling heat transfer coefficients at cryogenic temperatures for multi-component refrigerant mixtures of nitrogen-hydrocarbons

Science.gov (United States)

Ardhapurkar, P. M.; Sridharan, Arunkumar; Atrey, M. D.

2014-01-01

The recuperative heat exchanger governs the overall performance of the mixed refrigerant Joule-Thomson cryocooler. In these heat exchangers, the non-azeotropic refrigerant mixture of nitrogen-hydrocarbons undergoes boiling and condensation simultaneously at cryogenic temperature. Hence, the design of such heat exchanger is crucial. However, due to lack of empirical correlations to predict two-phase heat transfer coefficients of multi-component mixtures at low temperature, the design of such heat exchanger is difficult.

Variational principles in terms of entransy for heat transfer

International Nuclear Information System (INIS)

Xu, Mingtian

2012-01-01

A variational principle for heat conduction is formulated which results in the steady state heat conduction equation established from the Fourier law. Furthermore based on the thermodynamics in terms of entransy a more general functional is defined for incompressible fluids. We show that extremizing this functional gives rise to the state described by the Navier-Stokes-Fourier equations with vanishing substantive derivatives of the temperature and velocity field. In this sense one may conclude that this variational principle is consistent with the Navier-Stokes-Fourier equations. Therefore the variational principle developed in the present work demonstrates a great advantage over the minimum entropy production principle. -- Highlights: ► A variational principle for heat transfer of incompressible fluid is established in terms of entransy. ► For pure heat conduction the variational principle leads to the classical steady state heat conduction equation. ► For heat convection the variational principle is consistent with the Navier-Stokes-Fourier equations.

Ohmic Heating: Concept and Applications-A Review.

Science.gov (United States)

Kaur, Nimratbir; Singh, A K

2016-10-25

Ohmic heating, also known as Joule heating, electrical resistance heating, and direct electrical resistance heating, is a process of heating the food by passing electric current. In ohmic heating the energy is dissipated directly into the food. Electrical conductivity is a key parameter in the design of an effective ohmic heater. A large number of potential applications exist for ohmic heating, including blanching, evaporation, dehydration, fermentation, sterilization, pasteurization, and heating of foods. Beyond heating, applied electric field under ohmic heating causes electroporation of cell membranes, which increase extraction rates, and reduce gelatinization temperature and enthalpy. Ohmic heating results in faster heating of food along with maintenance of color and nutritional value of food. Water absorption index, water solubility index, thermal properties, and pasting properties are altered with the application of ohmic heating. Ohmic heating results in pre-gelatinized starches, which reduce energy requirement during processing. But its higher initial cost, lack of its applications in foods containing fats and oils, and less awareness limit its use.

Experimental investigation of heat transfer in the transition region

International Nuclear Information System (INIS)

Johannsen, K.; Weber, P.; Feng, Q.

1990-10-01

An experimental study of forced convective boiling heat transfer for upflow of water in a circular tube has been performed using a heat transfer system with temperature-controlled indirect Joule heating. By this way, complete boiling curves from incipience of boiling to fully established film boiling could be measured including the transition boiling regime. The boiling curves were traversed in a quasi-steady mode, usually by increasing the set-point wall temperature average at a constant time rate of 3.5 K/min. The vast majority of results covers the pressure range from 0.1 to 1.0 MPa, mass flux range from 25 to 200 kg/(m 2 s) and inlet subcooling from 5 to 30 K. The experimental results of transition boiling heat transfer obtained in the centre of the test section were correlated in terms of a heat flux/surface superheat relationship that was normalized by the maximum heat flux (local CHF) and its associated wall superheat, respectively, to anchor the transition boiling curve to its low temperature limit. The upper surface temperature limit of the transition boiling regime was determined by inspection of measured axial distributions of surface heat flux and corresponding wall temperature. The critical heat flux (CHF) and its corresponding wall superheat has been measured, too. These temperature-controlled results were compared also with power-controlled experiments. The data are presented in terms of a table and accurate empirical correlations following Katto's generalized correlation scheme. Taking into account previous CHF data at L/D ≤ 100 and same range of flow conditions the length effect was found to further depend on pressure and mass flux. The data for the critical wall superheat show a distinct dependence upon pressure, mass flux and inlet quality that has not been observed before with comparable clarity

Quintessence Reissner Nordström Anti de Sitter Black Holes and Joule Thomson Effect

Science.gov (United States)

Ghaffarnejad, H.; Yaraie, E.; Farsam, M.

2018-06-01

In this work we investigate corrections of the quintessence regime of the dark energy on the Joule-Thomson (JT) effect of the Reissner Nordström anti de Sitter (RNAdS) black hole. The quintessence dark energy has equation of state as p q = ω ρ q in which -1black hole mass, we calculate inversion temperature T i of the quintessence RNAdS black hole where its cooling phase is changed to heating phase at a particular (inverse) pressure P i . Position of the inverse point { T i , P i } is determined by crossing the inverse curves with the corresponding Gibbons-Hawking temperature on the T-P plan. We determine position of the inverse point versus different numerical values of the mass M and the charge Q of the quintessence AdS RN black hole. The cooling-heating phase transition (JT effect) is happened for M > Q in which the causal singularity is still covered by the horizon. Our calculations show sensitivity of the inverse point { T i , P i } position on the T-P plan to existence of the quintessence dark energy just for large numerical values of the AdS RN black holes charge Q. In other words the quintessence dark energy dose not affect on position of the inverse point when the AdS RN black hole takes on small charges.

New flow boiling heat transfer model for hydrocarbons evaporating inside horizontal tubes

International Nuclear Information System (INIS)

Chen, G. F.; Gong, M. Q.; Wu, J. F.; Zou, X.; Wang, S.

2014-01-01

Hydrocarbons have high thermodynamic performances, belong to the group of natural refrigerants, and they are the main components in mixture Joule-Thomson low temperature refrigerators (MJTR). New evaluations of nucleate boiling contribution and nucleate boiling suppression factor in flow boiling heat transfer have been proposed for hydrocarbons. A forced convection heat transfer enhancement factor correlation incorporating liquid velocity has also been proposed. In addition, the comparisons of the new model and other classic models were made to evaluate its accuracy in heat transfer prediction

Imaging radar observations of Farley Buneman waves during the JOULE II experiment

Directory of Open Access Journals (Sweden)

D. L. Hysell

2008-07-01

Full Text Available Vector electric fields and associated E×B drifts measured by a sounding rocket in the auroral zone during the NASA JOULE II experiment in January 2007, are compared with coherent scatter spectra measured by a 30 MHz radar imager in a common volume. Radar imaging permits precise collocation of the spectra with the background electric field. The Doppler shifts and spectral widths appear to be governed by the cosine and sine of the convection flow angle, respectively, and also proportional to the presumptive ion acoustic speed. The neutral wind also contributes to the Doppler shifts. These findings are consistent with those from the JOULE I experiment and also with recent numerical simulations of Farley Buneman waves and instabilities carried out by Oppenheim et al. (2008. Simple linear analysis of the waves offers some insights into the spectral moments. A formula relating the spectral width to the flow angle, ion acoustic speed, and other ionospheric parameters is derived.

On the Concept of Energy: Eclecticism and Rationality

Science.gov (United States)

Coelho, Ricardo Lopes

2014-06-01

In the theory of heat of the first half of the nineteenth century, heat was a substance. Mayer and Joule contradicted this thesis but developed different concepts of heat. Heat was a force for Mayer and a motion for Joule. Both Mayer and Joule determined the mechanical equivalent of heat. This result was, however, justified in accordance with those concepts of heat. Mayer's characterisation of force reappears in the very common textbook definition `energy cannot be created or destroyed but only transformed' and his theory led to a phenomenological approach to energy. Joule and Thomson's concept of heat led to a mechanistic approach to energy and to the common definition `energy is the capacity of doing work'. One and the same term `energy' subsumed these two approaches. The problematic concept of energy, energy as a substance, appears then as a result of an eclectic development of the concept. Another approach, which appeared in the 1860s, is directly based on the mechanical equivalent of heat and can be characterized by the use of `principle of equivalence' instead of `principle of energy conservation'. Unlike the others, this approach, which has been lost, poses no problems with the concept of energy. The problems with the energy concept as to the kind of phenomena dealt with in the present paper can, however, be overcome, as we shall see, in distinguishing between that which comes from experiments and that which is an interpretation of the experimental results within a conceptual framework.

On the Concept of Energy: Eclecticism and Rationality

Science.gov (United States)

Coelho, Ricardo Lopes

2014-01-01

In the theory of heat of the first half of the nineteenth century, heat was a substance. Mayer and Joule contradicted this thesis but developed different concepts of heat. Heat was a force for Mayer and a motion for Joule. Both Mayer and Joule determined the mechanical equivalent of heat. This result was, however, justified in accordance with…

Energetic optimization of the performances of a hot air engine for micro-CHP systems working with a Joule or an Ericsson cycle

International Nuclear Information System (INIS)

Creyx, M.; Delacourt, E.; Morin, C.; Desmet, B.; Peultier, P.

2013-01-01

The micro combined heat and electrical power systems (micro-CHP) with hot air engines are well adapted for solid biomass upgrading, in particular, the Ericsson engines working with an open cycle and an external combustion. This paper presents a model of an Ericsson engine with a compression and an expansion cylinder which allows a thermodynamic optimization of the engine performances in a global approach. A sensitive analysis on the influent parameters is carried out in order to determine the optimal working conditions of the engine: temperature and pressure range, expansion cycle shape with a late intake valve closing or an early exhaust valve closing, heat transfers through the wall of the cylinders. This study, focused on thermodynamic aspects, is a first step in the design of an Ericsson engine. -- Highlights: ► A model of Ericsson engine working with a Joule or Ericsson cycle is presented. ► Influent factors on the engine performances are investigated. ► The heat exchanges in the cylinder wall must be avoided to improve the performances. ► Closing the intake valve late and the exhaust valve early enhances the performances. ► Efficiency, indicated mean pressure, specific work are thermodynamically optimized.

Heat transfer in pool boiling liquid neon, deuterium and hydrogen, and critical heat flux in forced convection of liquid neon

International Nuclear Information System (INIS)

Astruc, J.M.

1967-12-01

In the first part, free-convection and nucleate pool boiling heat transfer (up to burn-out heat flux) between a platinum wire of 0.15 mm in diameter in neon, deuterium and hydrogen has been studied at atmospheric pressure. These measurements were continued in liquid neon up to 23 bars (Pc ≅ 26.8 b). Film boiling heat transfer coefficients have been measured in pool boiling liquid neon at atmospheric pressure with three heating wires (diameters 0.2, 0.5, 2 mm). All the results have been compared with existing correlations. The second part is devoted to measurements of the critical heat flux limiting heat transfer with small temperature differences between the wall and the liquid neon flowing inside a tube (diameters 3 x 3.5 mm) heated by joule effect on 30 cm of length. Influences of flow stability, nature of electrical current, pressure, mass flow rate and subcooling are shown. In conclusion, the similarity of the heat transfer characteristics in pool boiling as well as in forced convection of liquid neon and hydrogen is emphasized. (author) [fr

Nutritional impact of ohmic heating on fruits and vegetables—A review

Directory of Open Access Journals (Sweden)

Ranvir Kaur

2016-12-01

Full Text Available Ohmic heating, also called electrical resistance heating, joule heating, or electro-conductive heating, is an advanced thermal food processing technique where heat is internally generated in a sample due to electrical resistance when electric current is passed through it. It is a novel technique which provides rapid and uniform heating, resulting in less thermal damage to the food product. According to the recent literature, plant products are most suitable and often used for ohmic heat processing. Beyond heating of fruits and vegetables, the applied electric field under ohmic heating causes various changes in quality and nutritional parameters which include inactivation of enzymes and micro-organisms, degradation of heat-sensitive compounds, changes in cell membranes, viscosity, pH, color, and rheology. Ohmic heating rate depends on the electrical field strength and electrical conductivity of product. This review focuses on various factors affecting the electrical conductivity of fruits and vegetables and the effect of ohmic heating on their quality and nutritional properties.

Changes in the properties of superalloys by long term heating

International Nuclear Information System (INIS)

Susukida, H.; Tsuji, I.; Kawai, H.

1976-01-01

A laboratory study was conducted in order to determine the effect of long term heating (max. 10000h at 850 0 and 950 0 C) on the microstructure, tensile properties, hardness and stress rupture properties of four kinds of superalloys. These superalloys are two kinds of solid solution hardened Ni-base superalloys Hastelloy X and Inconel 617 and two kinds of dispersion strengthened Ni-base superalloys TD-Ni and TD-NiCr. The result of the study can be summarized as follows: (1) Solid solution hardened superalloys: Many precipitates were observed in the grains and on the grain boundaries after 100 hours of heating, and the precipitates became coarse-grained by over 1000 hours of heating. This tendency was remarkable when they were heated at 950 0 C. With the change of their microstructure, their mechanical properties also changed, particularly their tensile ductility decreased remarkably. (2) Dispersion strengthened superalloys: Their microstructure and mechanical properties were almost unchanged by long term heating. (3) The authors proposed ''solid solution hardening value'' in order to grasp quantitatively the solid solution hardening which has been discussed by the content of each element hitherto. (auth.)

A comparison on the heat load of HTS current leads with respect to uniform and non-uniform cross-sectional areas

Energy Technology Data Exchange (ETDEWEB)

Han, Seung Hak; Nam, Seok Ho; Lee, Je Yull; Song, Seung Hyun; Jeon, Hae Ryong; Baek, Geon Woo; Ko, Tae Kuk [Yonsei University, Seoul (Korea, Republic of); Kang, Hyoung Ku [Korea National University of Transportation, Chungju (Korea, Republic of)

2017-09-15

Current lead is a device that connects the power supply and superconducting magnets. High temperature superconductor (HTS) has lower thermal conductivity and higher current density than normal metal. For these reasons, the heat load can be reduced by replacing the normal metal of the current lead with the HTS. Conventional HTS current lead has same cross-sectional area in the axial direction. However, this is over-designed at the cold-end (4.2 K) in terms of current. The heat load can be reduced by reducing this part because the heat load is proportional to the cross-sectional area. Therefore, in this paper, heat load was calculated from the heat diffusion equation of HTS current leads with uniform and non-uniform cross-sectional areas. The cross-sectional area of the warm-end (65K) is designed considering burnout time when cooling system failure occurs. In cold-end, Joule heat and heat load due to current conduction occurs at the same time, so the cross-sectional area where the sum of the two heat is minimum is obtained. As a result of simulation, current leads for KSTAR TF coils with uniform and non-uniform cross-sectional areas were designed, and it was confirmed that the non-uniform cross-sectional areas could further reduce the heat load.

Technology, applications and modelling of ohmic heating: a review.

Science.gov (United States)

Varghese, K Shiby; Pandey, M C; Radhakrishna, K; Bawa, A S

2014-10-01

Ohmic heating or Joule heating has immense potential for achieving rapid and uniform heating in foods, providing microbiologically safe and high quality foods. This review discusses the technology behind ohmic heating, the current applications and thermal modeling of the process. The success of ohmic heating depends on the rate of heat generation in the system, the electrical conductivity of the food, electrical field strength, residence time and the method by which the food flows through the system. Ohmic heating is appropriate for processing of particulate and protein rich foods. A vast amount of work is still necessary to understand food properties in order to refine system design and maximize performance of this technology in the field of packaged foods and space food product development. Various economic studies will also play an important role in understanding the overall cost and viability of commercial application of this technology in food processing. Some of the demerits of the technology are also discussed.

Evaluation of inductive heating energy of a PF insert coil conductor by the calorimetric method (Contract research)

International Nuclear Information System (INIS)

Matsui, Kunihiro; Nabara, Yoshihiro; Nunoya, Yoshihiko; Koizumi, Norikiyo; Okuno, Kiyoshi

2009-02-01

The PF Insert Coil is a single layer solenoid coil using a superconducting conductor designed for ITER, housed in a Poloidal field coil and installed in the bore of the CS Model Coil. A stability test of the conductor will be performed in a magnetic field generated by the CS Model Coil. In this test, the inductive heat of an inductive heater attached to the conductor will be applied to initiate a normal zone in the conductor. Since the conductor for the PF Insert Coil is a cable-in-conduit conductor, it is quite difficult to estimate inductive heating energy theoretically. Thus, the inductive heating energy is measured experimentally by the calorimetric method. The heating energy is in proportion to a constant multiplied by the integrated square of an applied sinusoidal current wave over the heating period. Experimental results show that the proportional constants of the conductor, cable, conduit and dummy conductor are 0.138 [J/A 2 s], 0.028 [J/A 2 s], 0.118 [J/A 2 s] and 0.009 [J/A 2 s], respectively. The first three denote not only the inductive heating but also the joule heating of the inductive heater. The final value denotes joule heating only. Therefore, subtracting the first three constants by the last one, the proportional constants of inductive heating generated in the conductor, cable and conduit are estimated to be 0.129 [J/A 2 s], 0.019 [J/A 2 s] and 0.109 [J/A 2 s], respectively. (author)

Ohmic Heating: An Emerging Concept in Organic Synthesis.

Science.gov (United States)

Silva, Vera L M; Santos, Luis M N B F; Silva, Artur M S

2017-06-12

The ohmic heating also known as direct Joule heating, is an advanced thermal processing method, mainly used in the food industry to rapidly increase the temperature for either cooking or sterilization purposes. Its use in organic synthesis, in the heating of chemical reactors, is an emerging method that shows great potential, the development of which has started recently. This Concept article focuses on the use of ohmic heating as a new tool for organic synthesis. It presents the fundamentals of ohmic heating and makes a qualitative and quantitative comparison with other common heating methods. A brief description of the ohmic reactor prototype in operation is presented as well as recent examples of its use in organic synthesis at laboratory scale, thus showing the current state of the research. The advantages and limitations of this heating method, as well as its main current applications are also discussed. Finally, the prospects and potential implications of ohmic heating in future research in chemical synthesis are proposed. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Performance of Flow and Heat Transfer in a Hot-Dip Round Coreless Galvanizing Bath

Science.gov (United States)

Yue, Qiang; Zhang, Chengbo; Xu, Yong; Zhou, Li; Kong, Hui; Wang, Jia

2017-04-01

Flow field in a coreless hot-dip galvanizing pot was investigated through a water modeling experiment. The corresponding velocity vector was measured using an acoustic Doppler velocimeter. The flow field of molten zinc in the bath was also analyzed. Steel strip velocities from 1.7 to 2.7 m/s were adopted to determine the effect of steel strip velocity on the molten zinc flow in the bath. A large vortex filled the space at the right side of the sink roll, under linear speed from 1.0 to 2.7 m/s and width from 1.0 to 1.3 m of the steel strip, because of the effects of wall and shear stress. The results of the water modeling experiment were compared with those of numerical simulations. In the simulation, Maxwell equations were solved using finite element method to obtain magnetic flux density, electromagnetic force, and Joule heating. The Joule heating rate reached the maximum and minimum values near the side wall and at the core of the bath, respectively, because of the effect of skin and proximity. In an industrial-sized model, the molten zinc flow and temperature fields driven by electromagnetic force and Joule heating in the inductor of a coreless galvanizing bath were numerically simulated. The results indicated that the direction of electromagnetic force concentrated at the center of the galvanizing pot horizontal planes and exerted a pinch effect on molten zinc. Consequently, molten zinc in the pot was stirred by electromagnetic force. Under molten zinc flow and electromagnetic force stirring, the temperature of the molten zinc became homogeneous throughout the bath. This study provides a basis for optimizing electromagnetic fields in coreless induction pot and fine-tuning the design of steel strip parameters.

Recirculation within a glass mixture subjected to external and resistive heating

International Nuclear Information System (INIS)

Pepper, D.W.

1985-01-01

Convective motion within a glass mixture undergoing external and resistive (joule) heating is numerically simulated. A time-split finite element technique and a pseudo-pressure formulation are used to solve the two- and three-dimensional primitive equations of motion. The viscosity, thermal diffusivity, and electrical conductivity vary as a function of temperature; the temperature varies from ambient to 1150 0 C. 15 refs., 4 figs

Global effect of auroral particle and Joule heating in the undisturbed thermosphere

Science.gov (United States)

Hinton, B. B.

1978-01-01

From the compositional variations observed with the neutral atmosphere composition experiment on OGO 6 and a simplified model of thermospheric dynamics, global average values of non-EUV heating are deduced. These are 0.19-0.25 mW/sq m for quiet days and 0.44-0.58 mW/sq m for ordinary days.

Polar heating in Saturn's thermosphere

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C. G. A. Smith

2005-10-01

Full Text Available A 3-D numerical global circulation model of the Kronian thermosphere has been used to investigate the influence of polar heating. The distributions of temperature and winds resulting from a general heat source in the polar regions are described. We show that both the total energy input and its vertical distribution are important to the resulting thermal structure. We find that the form of the topside heating profile is particularly important in determining exospheric temperatures. We compare our results to exospheric temperatures from Voyager occultation measurements (Smith et al., 1983; Festou and Atreya, 1982 and auroral H3+ temperatures from ground-based spectroscopic observations (e.g. Miller et al., 2000. We find that a polar heat source is consistent with both the Smith et al. determination of T∞~400 K at ~30° N and auroral temperatures. The required heat source is also consistent with recent estimates of the Joule heating rate at Saturn (Cowley et al., 2004. However, our results show that a polar heat source can probably not explain the Festou and Atreya determination of T∞~800 K at ~4° N and the auroral temperatures simultaneously. Keywords. Ionosphere (Planetary ionosphere – Magnetospherica physics (Planetary magnetospheres – Meterology and atmospheric dynamics (Thermospheric dynamics

Analytical solution to the problem of heat transfer in an MHD flow inside a channel with prescribed sinusoidal wall heat flux

International Nuclear Information System (INIS)

Zniber, K.; Oubarra, A.; Lahjomri, J.

2005-01-01

An MHD laminar flow through a two dimensional channel subjected to a uniform magnetic field and heated at the walls of the conduit over the whole length with a sinusoidal heat flux of vanishing mean value or not, is studied analytically. General expressions of the temperature distribution and of the local and mean Nusselt numbers are obtained by using the technique of linear operators in the case of negligible Joule and viscous dissipation and by taking into account the axial conduction effect. The principal results show that an increase of the local Nusselt number with Hartmann number is observed, and, far from the inlet section, the average heat transfer between the fluid and the walls shows a significant improvement at all values of Hartmann number used when the frequency of the prescribed sinusoidal wall heat flux is increasing in the case of vanishing mean value of the heat flux and this is true especially at low Peclet numbers

A study on shear behavior of R/C beams subjected to long-term heating

International Nuclear Information System (INIS)

Maruta, M.; Yamazaki, M.

1993-01-01

In nuclear power plants, many structural members are subjected to long term heating. There are few experimental data available on the behavior especially in shear of reinforced concrete (R/C) members subjected to long term heating. This paper describes a study aimed at experimentally determining the shear behavior of R/C members in nuclear power plant facilities following sustained heating at high temperatures

Near-term viability of solar heat applications for the federal sector

Science.gov (United States)

Williams, T. A.

1991-12-01

Solar thermal technologies are capable of providing heat across a wide range of temperatures, making them potentially attractive for meeting energy requirements for industrial process heat applications and institutional heating. The energy savings that could be realized by solar thermal heat are quite large, potentially several quads annually. Although technologies for delivering heat at temperatures above 100 C currently exist within industry, only a fairly small number of commercial systems have been installed to date. The objective of this paper is to investigate and discuss the prospects for near term solar heat sales to federal facilities as a mechanism for providing an early market niche to the aid the widespread development and implementation of the technology. The specific technical focus is on mid-temperature (100 to 350 C) heat demands that could be met with parabolic trough systems. Federal facilities have several features relative to private industry that may make them attractive for solar heat applications relative to other sectors. Key features are specific policy mandates for conserving energy, a long term planning horizon with well defined decision criteria, and prescribed economic return criteria for conservation and solar investments that are generally less stringent than the investment criteria used by private industry. Federal facilities also have specific difficulties in the sale of solar heat technologies that are different from those of other sectors, and strategies to mitigate these difficulties will be important. For the baseline scenario developed in this paper, the solar heat application was economically competitive with heat provided by natural gas. The system levelized energy cost was $5.9/MBtu for the solar heat case, compared to $6.8/MBtu for the life cycle fuel cost of a natural gas case. A third-party ownership would also be attractive to federal users, since it would guarantee energy savings and would not need initial federal funds.

Effect of Spatial Dimension and External Potential on Joule-Thomson Coefficients of Ideal Bose Gases

International Nuclear Information System (INIS)

Yuan Duqi; Wang Canjun

2010-01-01

Based on the form of the n-dimensional generic power-law potential, the state equation and the heat capacity, the analytical expressions of the Joule-Thomson coefficient (JTC) for an ideal Bose gas are derived in n-dimensional potential. The effect of the spatial dimension and the external potential on the JTC are discussed, respectively. These results show that: (i) For the free ideal Bose gas, when n/s ≤ 2 (n is the spatial dimension, s is the momentum index in the relation between the energy and the momentum), and T → T C (T C is the critical temperature), the JTC can obviously improve by means of changing the throttle valve's shape and decreasing the spatial dimension of gases. (ii) For the inhomogeneous external potential, the discriminant Δ = [1 - Π[ n i=1 (kT/varpi i ) 1/t i Γ(1/t i + 1)] (k is the Boltzmann Constant, T is the thermodynamic temperature, varpi i is the external field's energy), is obtained. The potential makes the JTC increase when Δ > 0, on the contrary, it makes the JTC decrease when Δ i < 1. (general)

Signal mediators at induction of heat resistance of wheat plantlets by short-term heating

Directory of Open Access Journals (Sweden)

Yu. V. Karpets

2015-12-01

Full Text Available The effects of functional interplay of calcium ions, reactive oxygen species (ROS and nitric oxide (NO in the cells of wheat plantlets roots (Triticum aestivum L. at the induction of their heat resistance by a short-term influence of hyperthermia (heating at the temperature of 42 °С during 1 minute have been investigated. The transitional increase of NO and H2O2 content, invoked by heating, was suppressed by the treatment of plantlets with the antagonists of calcium EGTA (chelator of exocellular calcium, lanthanum chloride (blocker of calcium channels of various types and neomycin (inhibitor of phosphatidylinositol-dependent phospholipase C. The rise of hydrogen peroxide content, caused by hardening, was partially suppressed by the action of inhibitors of nitrate reductase (sodium wolframate and NO-synthase (NG-nitro-L-arginine methyl ester – L-NAME, and the increasing of nitric oxide content was suppressed by the treatment of plants with the antioxidant ionol and with the scavenger of hydrogen peroxide (dimethylthiourea. These compounds and antagonists of calcium also partially removed the effect of the rise of plantlets’ heat resistance, invoked by hardening heating. The conclusion on calcium’s role in the activation of enzymatic systems, generating reactive oxygen species and nitric oxide, and on the functional interplay of these signal mediators at the induction of heat resistance of plantlets by hardening heating is made.

Temporal evolutions of electron temperature and density of turbulently-heated tokamak plasmas in TRIAM-1

Energy Technology Data Exchange (ETDEWEB)

Hiraki, N; Nakamura, K; Nakamura, Y; Itoh, S [Kyushu Univ., Fukuoka (Japan). Research Inst. for Applied Mechanics

1981-04-01

The temporal evolution of the electron temperature and density are measured in a turbulent heating experiment in TRIAM-1. Skin-like profiles of the electron temperature and density are clearly observed. The anomality in the electrical resistivity of the plasma in this skin-layer is estimated, and the plasma heating in this skin-layer is regarded as being due to anomalous joule heating arising from this anomalous resistivity. The ratio of drift velocity to electron thermal velocity in the layer is also calculated, and it is shown that the conditions needed to make the current-driven ion-acoustic instability triggerable are satisfied.

Stability improvement for coil position locking of joule balance

Science.gov (United States)

Bai, Yang; Liu, Yongmeng; Lu, Yunfeng; Hu, Pengcheng; Wang, Dawei; Li, Zhengkun; Tan, Jiubin; Zhang, Zhonghua

2017-08-01

The relative vertical position locking precision between the exciting and suspended coils is an important uncertainty for the Planck constant traceability in joule balance. In order to improve the relative vertical position locking precision, several stability experiments are conducted. The stability characteristics of the suspended and exciting coils are measured using a six-axis laser interferometer system; meanwhile, the effectiveness of the active vibration isolation table is measured using a vibration measurement sensor. The piezoelectric ceramic actuators with PID controller are used to compensate the relative vertical displacement drifts while a six-axis laser interferometer system is used to measure the positions of two coils. Experimental results show that the relative vertical position is stably locked.

Waveguide circuit for LHRF heating in 'JT-60'

International Nuclear Information System (INIS)

Uehara, Kazuya; Saegusa, Mikio; Mizuno, Takenori; Sano, Keigo; Hara, Mitsuru; Oishi, Isamu; Kanai, Takao.

1985-01-01

As the heating method for attaining the critical condition in the critical plasma experiment apparatus 'JT-60' in the Japan Atomic Energy Research Institute, in addition to Joule heating, as the second heating method, neutral beam injection heating and high frequency heating have been adopted. For this high frequency heating, several tens to 200 MHz band of ICRF heating, several hundreds MHz to several GHz band of LHRF heating and several tens to 200 GHz band of ECR heating were considered, and in the JT-60, 100 MHz band (ICRF) and 2 GHz band (LHRF) have been adopted. Furukawa Electric Co., Ltd. has engaged in the development and manufacture of the waveguides of transmission system used for this high frequency heating through NEC Corp. This high frequency heating is to heat plasma by injecting high frequency radio waves into plasma proper, and reaches 10 MW for the whole high frequency heating. The system efficiently transmitting the radio waves of large power from a Klystron as a high frequency source to the JT-60 is the transmission system. The outline of the waveguides of the 2 GHz band transmission system and the individual performance of respective waveguides are reported. (Kako, I.)

Heat Transfer Correlations for Free Convection from Suspended Microheaters

Directory of Open Access Journals (Sweden)

David GOSSELIN

2016-08-01

Full Text Available Portability and autonomy for biomedical diagnostic devices are two rising requirements. It is recognized that low-energy heating of such portable devices is of utmost importance for molecular recognition. This work focuses on screen-printed microheaters based on on Joule effect, which constitute an interesting solution for low-energy heating. An experimental study of the natural convection phenomena occurring with such microheaters is conducted. When they are suspended in the air, and because of the thinness of the supporting film, it is shown that the contributions of both the upward and downward faces have to be taken into account. A total Nusselt number and a total convective heat transfer coefficient have been used to describe the natural convection around these microheaters. In addition a relation between the Nusselt number and the Rayleigh number is derived, leading to an accurate prediction of the heating temperature (MRE< 2 %.

Magnetospheric energy inputs into the upper atmospheres of the giant planets

Directory of Open Access Journals (Sweden)

C. G. A. Smith

2005-07-01

Full Text Available We revisit the effects of Joule heating upon the upper atmospheres of Jupiter and Saturn. We show that in addition to direct Joule heating there is an additional input of kinetic energy – ion drag energy – which we quantify relative to the Joule heating. We also show that fluctuations about the mean electric field, as observed in the Earth's ionosphere, may significantly increase the Joule heating itself. For physically plausible parameters these effects may increase previous estimates of the upper atmospheric energy input at Saturn from ~10 TW to ~20 TW.

Keywords. Ionosphere (Electric fields and currents; Planetary ionosphere – Magnetospheric physics (Auroral phenomena

Shallow geothermal field in Lanzarote (Canary Island). Potential evaluation and heat extraction test

Energy Technology Data Exchange (ETDEWEB)

Diez-Gil, J.L.; Valentin, A. [Consejo Superior de Investigaciones Cientificas, Madrid (Spain); Torres, F. [Universidad de Barcelona (Spain); Albert, J.F.

1994-12-31

Boreholes were used to perform various experiments. A thermometry was carried out, as well as chemical analysis and an hydrodynamic modelling. This paper presents the scientific aims and conclusions of the whole project called ``Shallow H.D.R. geothermal field`` in Lanzarote (Canary Islands). Potential evaluation and heat extraction test are presented. (Project JOUG-0004 ES -JR - JOULE Program of the EEC). (TEC). 2 tabs.

Micro-joule pico-second range Yb3+-doped fibre laser for medical applications in acupuncture

Science.gov (United States)

Alvarez-Chavez, J. A.; Rivera-Manrique, S. I.; Jacques, S. L.

2011-08-01

The work described here is based on the optical design, simulation and on-going implementation of a pulsed (Q-switch) Yb3+-doped, 1-um diffraction-limited fibre laser with pico-second, 10 micro-Joule-range energy pulses for producing the right energy pulses which could be of benefit for patients who suffer chronic headache, photophobia, and even nausea which could is sometimes triggered by a series of factors. The specific therapeutic effect known as acupunctural analgesia is the main objective of this medium-term project. It is a simple design on which commercially available software was employed for laser cavity design. Monte Carlo technique for skin light-transport, thermal diffusion and the possible thermal de-naturalization optical study and prediction will also be included in the presentation. Full optical characterization will be included and a complete set of recent results on the laser-skin interaction and the so called moxi-bustion from the laser design will be extensively described.

Thin film heat flux sensors for accurate transient and unidirectional heat transfer analysis

International Nuclear Information System (INIS)

Azerou, B; Garnier, B; Lahmar, J

2012-01-01

Heat flux measurement is needed in many heat transfer studies. For the best unbiased heat flux sensors (HFS), the heat flux is obtained using temperature measurements at different locations and also an inverse heat conduction method (function specification...) in order to calculate the heat flux. Systematic errors can come from the uncertainty in the wire thermocouples locations and from errors in the knowledge of distances between two consecutive wire thermocouples. The main idea in this work is to use thin film thermoresistances deposited on a flexible thin polymer substrate instead of wire thermocouples welded on metallic sample. The interest of using thin film thermoresistances instead of wire thermocouples is a lower disturbance due to the smaller thickness of the thin film sensors (typically less than 1μm) and a much better knowledge of the distances between the different thin film thermoresistances which are precisely defined in the mask used for the metallic thin film pattern fabrication. In this paper, we present the fabrication of the new heat flux sensor with thin film thermoresistances, the study of the effect of the self heating (due to Joule effect in thermoresistances) and the performances of this new HFS with the comparison with classical HFS using wire thermocouples. For this study, a symmetric experimental setup is used with metallic samples equipped with an etched foil heater and both classical and new HFS. For several heating conditions, it appears that a better accuracy is always obtained with the new HFS using thin film thermoresistances.

Long-term heat stress induces the inflammatory response in dairy cows revealed by plasma proteome analysis.

Science.gov (United States)

Min, Li; Zheng, Nan; Zhao, Shengguo; Cheng, Jianbo; Yang, Yongxin; Zhang, Yangdong; Yang, Hongjian; Wang, Jiaqi

2016-03-04

In this work we employed a comparative proteomic approach to evaluate seasonal heat stress and investigate proteomic alterations in plasma of dairy cows. Twelve lactating Holstein dairy cows were used and the treatments were: heat stress (n = 6) in hot summer (at the beginning of the moderate heat stress) and no heat stress (n = 6) in spring natural ambient environment, respectively. Subsequently, heat stress treatment lasted 23 days (at the end of the moderate heat stress) to investigate the alterations of plasma proteins, which might be employed as long-term moderate heat stress response in dairy cows. Changes in plasma proteins were analyzed by two-dimensional electrophoresis (2-DE) combined with mass spectrometry. Analysis of the properties of the identified proteins revealed that the alterations of plasma proteins were related to inflammation in long-term moderate heat stress. Furthermore, the increase in plasma tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) directly demonstrated that long-term moderate heat stress caused an inflammatory response in dairy cows. Copyright © 2016 Elsevier Inc. All rights reserved.

Joule-Heated Ceramic-Lined Melter to Vitrify Liquid Radioactive Wastes Containing Am241 Generated From MOX Fuel Fabrication in Russia

International Nuclear Information System (INIS)

Smith, E C; Bowan II, B W; Pegg, I; Jardine, L J

2004-01-01

contains. Silver is widely used as an additive in glass making. However, its solubility is known to be limited in borosilicate glasses. Further, silver, which is present as a nitrate salt in the waste, can be easily reduced to molten silver in the melting process. Molten silver, if formed, would be difficult to reintroduce into the glass matrix and could pose operating difficulties for the glass melter. This will place a limitation on the waste loading of the melter feed material to prevent the separation of silver from the waste within the melter. If the silver were recovered in the MOx fabrication process, which is currently under consideration, the composition of the glass would likely be limited only by the thermal heat load from the incorporated 241 Am. The resulting mass of glass used to encapsulate the waste could then be reduced by a factor of approximately three. The vitrification process used to treat the waste stream is proposed to center on a joule-heated ceramic lined slurry fed melter. Glass furnaces of this type are used in the United States to treat high-level waste (HLW) at the: Defense Waste Processing Facility, West Valley Demonstration Project, and to process the Hanford tank waste. The waste will initially be blended with glass-forming chemicals, which are primarily sand and boric acid. The resulting slurry is pumped to the melter for conversion to glass. The melter is a ceramic lined metal box that contains a molten glass pool heated by passing electric current through the glass. Molten glass from the melter is poured into canisters to cool and solidify. They are then sealed and decontaminated to form the final waste disposal package. Emissions generated in the melter from the vitrification process are treated by an off-gas system to remove radioactive contamination and destroy nitrogen oxides (NOx)

Effect of short-term exercise-heat acclimation on ventilatory and cerebral blood flow responses to passive heating at rest in humans.

Science.gov (United States)

Fujii, Naoto; Tsuji, Bun; Honda, Yasushi; Kondo, Narihiko; Nishiyasu, Takeshi

2015-09-01

Hyperthermia induces hyperventilation and cerebral hypoperfusion in resting humans. We tested the hypothesis that short-term exercise-heat acclimation would alleviate those effects. Twenty healthy male subjects were divided into two groups that performed exercise training in the heat (TR-HEAT, n = 10) or cold (TR-COLD, n = 10). Before and after the training, the subjects in both groups participated in passive-heat tests at rest. Training was performed at 37°C (TR-HEAT) or 10°C (TR-COLD) and entailed four 20-min bouts of cycling at 50% peak oxygen uptake separated by 10-min recoveries daily for 6 consecutive days. After TR-HEAT, esophageal temperature was lowered when measured before and during passive heating, as was the esophageal temperature threshold for cutaneous active vasodilation, whereas plasma volume was increased (all P heat acclimation were not all induced by TR-COLD (all P > 0.05). TR-HEAT had no significant effect on passive heating-induced increases in minute ventilation, even when evaluated as the esophageal temperature threshold for increases in minute ventilation and the slope relating minute ventilation to esophageal temperature (all P > 0.05). By contrast, TR-HEAT attenuated the passive heating-induced reduction in the cerebral vascular conductance index (middle cerebral artery mean blood velocity/mean arterial pressure) (all P heating (all P > 0.05). These data suggest that in resting heated humans, short-term heat acclimation achieved through moderate-intensity exercise training (i.e., 50% peak oxygen uptake) in the heat does not influence hyperthermia-induced hyperventilation, but it does potentially attenuate cerebral hypoperfusion. Copyright © 2015 the American Physiological Society.

Joule-Thomson effect in a Pierce electron gun

International Nuclear Information System (INIS)

Batalin, V.A.

1982-01-01

A model which can be investigated both by means of the system of Vlasov equations and by means of ideal gas state equation is proposed for evaluation of emittance growth in the Pierce electron gun of electron beam with the limiting small distribution rate and intended for electron cooling facilities. The assumption has been made that transverse emittance growth is different from the zero. Thermodynamical approach to the problem of electron beam propagation permits to evaluate the increase of its emittance. It is shown that the increase of the electron beam emittance in the Pierce electron gun is similar to Joule-Thompson effect for gases. The effect increases with the decrease of the beam initial temperature. The increase of the emittance can become essential even in hte perfect (without aberration) Pierce optics at beam transverse temperature of the order of 0.1 eV

Parametric investigation of heating due to magnetic fluid hyperthermia in a tumor with blood perfusion

Energy Technology Data Exchange (ETDEWEB)

Liangruksa, Monrudee [Department of Engineering Science and Mechanics, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061 (United States); Ganguly, Ranjan [Department of Power Engineering, Jadavpur University, Kolkata 700098 (India); Puri, Ishwar K., E-mail: ikpuri@vt.ed [Department of Engineering Science and Mechanics, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061 (United States)

2011-03-15

Magnetic fluid hyperthermia (MFH) is a cancer treatment that can selectively elevate the tumor temperature without significantly damaging the surrounding healthy tissue. Optimal MFH design requires a fundamental parametric investigation of the heating of soft materials by magnetic fluids. We model the problem of a spherical tumor and its surrounding healthy tissue that are heated by exciting a homogeneous dispersion of magnetic nanoparticles infused only into the tumor with an external AC magnetic field. The key dimensionless parameters influencing thermotherapy are the Peclet, Fourier, and Joule numbers. Analytical solutions for transient and steady hyperthermia provide correlations between these parameters and the portions of tumor and healthy tissue that are subjected to a threshold temperature beyond which they are damaged. Increasing the ratio of the Fourier and Joule numbers also increases the tumor temperature, but doing so can damage the healthy tissue. Higher magnetic heating is required for larger Peclet numbers due to the larger convection heat loss that occurs through blood perfusion. A comparison of the model predictions with previous experimental data for MFH applied to rabbit tumors shows good agreement. The optimal MFH conditions are identified based on two indices, the fraction I{sub T} of the tumor volume in which the local temperature is above a threshold temperature and the ratio I{sub N} of the damaged normal tissue volume to the tumor tissue volume that also lies above it. The spatial variation in the nanoparticle concentration is also considered. A Gaussian distribution provides efficacy while minimizing the possibility of generating a tumor hot spot. Varying the thermal properties of tumor and normal tissue alters I{sub T}and I{sub N} but the nature of the temperature distribution remains unchanged. - Research highlights: > Analytical model of magnetic fluid hyperthermia of tumor tissue perfused with magnetic nanoparticles that is surrounded

Parametric investigation of heating due to magnetic fluid hyperthermia in a tumor with blood perfusion

International Nuclear Information System (INIS)

Liangruksa, Monrudee; Ganguly, Ranjan; Puri, Ishwar K.

2011-01-01

Magnetic fluid hyperthermia (MFH) is a cancer treatment that can selectively elevate the tumor temperature without significantly damaging the surrounding healthy tissue. Optimal MFH design requires a fundamental parametric investigation of the heating of soft materials by magnetic fluids. We model the problem of a spherical tumor and its surrounding healthy tissue that are heated by exciting a homogeneous dispersion of magnetic nanoparticles infused only into the tumor with an external AC magnetic field. The key dimensionless parameters influencing thermotherapy are the Peclet, Fourier, and Joule numbers. Analytical solutions for transient and steady hyperthermia provide correlations between these parameters and the portions of tumor and healthy tissue that are subjected to a threshold temperature beyond which they are damaged. Increasing the ratio of the Fourier and Joule numbers also increases the tumor temperature, but doing so can damage the healthy tissue. Higher magnetic heating is required for larger Peclet numbers due to the larger convection heat loss that occurs through blood perfusion. A comparison of the model predictions with previous experimental data for MFH applied to rabbit tumors shows good agreement. The optimal MFH conditions are identified based on two indices, the fraction I T of the tumor volume in which the local temperature is above a threshold temperature and the ratio I N of the damaged normal tissue volume to the tumor tissue volume that also lies above it. The spatial variation in the nanoparticle concentration is also considered. A Gaussian distribution provides efficacy while minimizing the possibility of generating a tumor hot spot. Varying the thermal properties of tumor and normal tissue alters I T and I N but the nature of the temperature distribution remains unchanged. - Research Highlights: →Analytical model of magnetic fluid hyperthermia of tumor tissue perfused with magnetic nanoparticles that is surrounded by healthy tissue

40 CFR Table 2 to Subpart D of... - TRE Parameters for NSPS Referencing Subpartsa

Science.gov (United States)

2010-07-01

...? Net heating value(MJ/scm)b Vent stream flow rate (scm/min)c Values of terms for TRE equation: TRE=A... § 65.64(h). b MJ/scm = mega Joules per standard cubic meter. c scm/min = standard cubic meters per...

Enhanced short-term sensitization of facial compared with limb heat pain.

Science.gov (United States)

Schmidt, Katharina; Schunke, Odette; Forkmann, Katarina; Bingel, Ulrike

2015-08-01

Habituation and sensitization are important features of individual sensitivity to repetitive noxious stimulation and have been investigated in numerous studies. However, it is unclear whether these phenomena vary depending on the site of stimulation. Here we compared short-term and long-term effects of painful heat stimulation on the forehead and limb using an established longitudinal heat pain paradigm performed over 8 consecutive days in 36 healthy volunteers. Participants were randomized into 2 groups; participants received repetitive heat pain stimulation either on the left volar forearm or on the left side of the forehead. Our data show a comparable degree of habituation over the course of 8 days in both groups. However, participants in the trigeminal stimulation group exhibited stronger within-session sensitization (indexed by a higher within-session increase in pain intensity ratings) than those who received the forearm stimulation. Furthermore, over the course of the experiment we found a correlation between habituation and anxiety, showing less habituation in participants with higher trait anxiety scores. Our findings are in line with somatotopic differences in response to painful stimulation and a higher proneness of trigeminal pain to sensitization processes, which might be explained by the biological relevance of the head and facial area for vital functions. The contribution of this sensitivity to the development and maintenance of clinical facial pain and headache disorders warrants further investigation. This study uses psychophysical methods to evaluate the differences in long-term habituation and short-term sensitization to heat pain between the trigeminal and spinal systems. We found stronger sensitization for trigeminal compared with nociceptive stimuli on the forearm. The contribution of this sensitivity to clinical pain states warrants further investigation. Copyright © 2015 American Pain Society. Published by Elsevier Inc. All rights reserved.

Empirical Analysis for the Heat Exchange Effectiveness of a Thermoelectric Liquid Cooling and Heating Unit

Directory of Open Access Journals (Sweden)

Hansol Lim

2018-03-01

Full Text Available This study aims to estimate the performance of thermoelectric module (TEM heat pump for simultaneous liquid cooling and heating and propose empirical models for predicting the heat exchange effectiveness. The experiments were conducted to investigate and collect the performance data of TEM heat pump where the working fluid was water. A total of 57 sets of experimental data were statistically analyzed to estimate the effects of each independent variable on the heat exchange effectiveness using analysis of variance (ANOVA. To develop the empirical model, the six design parameters were measured: the number of transfer units (NTU of the heat exchangers (i.e., water blocks, the inlet water temperatures and temperatures of water blocks at the cold and hot sides of the TEM. As a result, two polynomial equations predicting heat exchange effectiveness at the cold and hot sides of the TEM heat pump were derived as a function of the six selected design parameters. Also, the proposed models and theoretical model of conventional condenser and evaporator for heat exchange effectiveness were compared with the additional measurement data to validate the reliability of the proposed models. Consequently, two conclusions have been made: (1 the possibility of using the TEM heat pump for simultaneous cooling and heating was examined with the maximum temperature difference of 30 °C between cold and hot side of TEM, and (2 it is revealed that TEM heat pump has difference with the conventional evaporator and condenser from the comparison results between the proposed models and theoretical model due to the heat conduction and Joule effect in TEM.

Liquid hydrogen mass flow through a multiple orifice Joule-Thomson device

International Nuclear Information System (INIS)

Papell, S.S.; Nyland, T.W.; Saiyed, N.H.

1992-07-01

Liquid hydrogen mass flow rate, pressure drop, and temperature drop data were obtained for a number of multiple orifice Joule-Thomson devices known as visco jets. The present investigation continues a study to develop an equation for predicting two phase flow of cryogens through these devices. The test apparatus design allowed isenthalpic expansion of the cryogen through the visco jets. The data covered a range of inlet and outlet operating conditions. The mass flow rate range single phase or two phase was 0.015 to 0.98 lbm/hr. The manufacturer's equation was found to overpredict the single phase hydrogen data by 10 percent and the two phase data by as much as 27 percent. Two modifications of the equation resulted in a data correlation that predicts both the single and two phase flow across the visco jet. The first modification was of a theoretical nature, and the second strictly empirical. The former reduced the spread in the two phase data. It was a multiplication factor of 1-X applied to the manufacturer's equation. The parameter X is the flow quality downstream of the visco jet based on isenthalpic expansion across the device. The latter modification was a 10 percent correction term that correlated 90 percent of the single and two phase data to within +/- 10 percent scatter band. 3 refs

Direct-drive shock-ignition for the Laser MégaJoule

Directory of Open Access Journals (Sweden)

Canaud B.

2013-11-01

Full Text Available We present a review of direct-drive shock ignition studies done as an alternative for the Laser MégaJoule (LMJ. One and two dimensional systematic analyses of HiPER-like shock-ignited target designs are performed for the fuel assembly irradiation uniformity using the whole LMJ configuration or a part of the facility, and for the uniformity of the ignitor spike. High-gain shock-ignition is shown to be possible with intensity of each quad less than 1015 W/cm2 but low modes asymmetries displace the power required in the ignitor spike towards higher powers. Shock-ignition of Direct-Drive Double-Shell non-cryogenic targets is also addressed.

Theoretical analysis of oscillatory terms in lattice heat-current time correlation functions and their contributions to thermal conductivity

Science.gov (United States)

Pereverzev, Andrey; Sewell, Tommy

2018-03-01

Lattice heat-current time correlation functions for insulators and semiconductors obtained using molecular dynamics (MD) simulations exhibit features of both pure exponential decay and oscillatory-exponential decay. For some materials the oscillatory terms contribute significantly to the lattice heat conductivity calculated from the correlation functions. However, the origin of the oscillatory terms is not well understood, and their contribution to the heat conductivity is accounted for by fitting them to empirical functions. Here, a translationally invariant expression for the heat current in terms of creation and annihilation operators is derived. By using this full phonon-picture definition of the heat current and applying the relaxation-time approximation we explain, at least in part, the origin of the oscillatory terms in the lattice heat-current correlation function. We discuss the relationship between the crystal Hamiltonian and the magnitude of the oscillatory terms. A solvable one-dimensional model is used to illustrate the potential importance of terms that are omitted in the commonly used phonon-picture expression for the heat current. While the derivations are fully quantum mechanical, classical-limit expressions are provided that enable direct contact with classical quantities obtainable from MD.

Possible biphasic sweating response during short-term heat acclimation protocol for tropical natives.

Science.gov (United States)

Magalhães, Flávio de Castro; Machado-Moreira, Christiano Antônio; Vimieiro-Gomes, Ana Carolina; Silami-Garcia, Emerson; Lima, Nilo Resende Viana; Rodrigues, Luiz Oswaldo Carneiro

2006-05-01

The aim of the present study was to evaluate the sweat loss response during short-term heat acclimation in tropical natives. Six healthy young male subjects, inhabitants of a tropical region, were heat acclimated by means of nine days of one-hour heat-exercise treatments (40+/-0 degrees C and 32+/-1% relative humidity; 50% (.)VO(2peak) on a cycle ergometer). On days 1 to 9 of heat acclimation whole-body sweat loss was calculated by body weight variation corrected for body surface area. On days 1 and 9 rectal temperature (T(re)) and heart rate (HR) were measured continuously, and rating of perceived exertion (RPE) every 4 minutes. Heat acclimation was confirmed by reduced HR (day 1 rest: 77+/-5 b.min(-1); day 9 rest: 68+/-3 b.min(-1); day 1 final exercise: 161+/-15 b.min(-1); day 9 final exercise: 145+/-11 b.min(-1), p0.05) of the protocol. These findings are consistent with the heat acclimation induced adaptations and suggest a biphasic sweat response (an increase in the sweat rate in the middle of the protocol followed by return to initial values by the end of it) during short-term heat acclimation in tropical natives.

Laboratory Testing of Solar Combi System with Compact Long Term PCM Heat Storage

DEFF Research Database (Denmark)

Johansen, Jakob Berg; Englmair, Gerald; Dannemand, Mark

2016-01-01

To enable the transition from fossil fuels as a primary heat source for domestic hot water preparation and space heating solar thermal energy has great potential. The heat from the sun has the disadvantage that it is not always available when there is a demand. To solve this mismatch a thermal...... seasonal storage can be used to store excess heat from the summer to the winter when the demand is higher than the supply. Installing a long term thermal storage in a one family house it needs to be compact and sensible heat storages are not suitable. A latent heat storage with a phase change material (PCM...

Nonadiabatic heating of the central plasma sheet at substorm onset

International Nuclear Information System (INIS)

Huang, C.Y.; Frank, L.A.; Rostoker, G.; Fennell, J.; Mitchell, D.G.

1992-01-01

Heating events in the plasma sheet boundary layer and central plasma sheet are found to occur at the onset of expansive phase activity. The main effect is a dramatic increase in plasma temperature, coincident with a partial dipolarization of the magnetic field. Fluxes of energetic particles increase without dispersion during these events which occur at all radial distances up to 23 R E , the apogee of the ISEIE spacecraft. A major difference between these heating events and those observed at geosynchronous distances lies in the heating mechanism which is nonadiabatic beyond 10 R E but may be adiabatic closer to Earth. The energy required to account for the increase in plasma thermal energy is comparable with that required for Joule heating of the ionosphere. The plasma sheet must be considered as a major sink in the energy balance of substorm. The authors estimate lobe magnetic pressures during these events. Changes in lobe pressure are generally not correlated with onsets or intensifications of expansive phase activity

New class of microminiature Joule — Thomson refrigerator and vacuum package

Science.gov (United States)

Paugh, Robert L.

1990-12-01

Progress is reported on the development of a two-stage, fast cooldown Joule — Thomson refrigerator using nitrogen gas and a nitrogen — hydrocarbon gas mixture as the refrigerants. The refrigerator incorporates a microminiature Venturi pump to reduce the pressure of the exhaust of the main boiler to bring the operating temperature of the cold stage to < 70 K in as little as 10 s. The vacuum package for the refrigerator contains no organic materials and is designed to provide a ten year shelf life. Special glass strengthening techniques are being used to achieve cooler survival of acceleration tests of up to 100 000g.

3D numerical modeling of coupled phenomena in induced processes of heat treatment with malice

Directory of Open Access Journals (Sweden)

Triwong Peeteenut

2008-01-01

Full Text Available This paper describes a multi-method Malice package for three dimension coupled phenomena in induced processes of heat treatment by an algorithm weakly coupled with the Migen package integral method defining the electromagnetic model and the Flux-Expert package finite element method defining the thermal model. The integral method is well suited to inductive systems undergoing sinusoidal excitation at midrange or high frequency. The unknowns of both models are current density, scalar potential and temperature. Joule power in the electromagnetic model is generated by Eddy currents. It becomes the heat source in the thermal model.

Elementary Concepts and Fundamental Laws of the Theory of Heat

Science.gov (United States)

de Oliveira, Mário J.

2018-06-01

The elementary concepts and fundamental laws concerning the science of heat are examined from the point of view of its development with special attention to its theoretical structure. The development is divided into four periods, each one characterized by the concept that was attributed to heat. The transition from one to the next period was marked by the emergence of new concepts and new laws, and by singular events. We point out that thermodynamics, as it emerged, is founded on the elementary concepts of temperature and adiabatic wall, and on the fundamental laws: Mayer-Joule principle, or law of conservation of energy; Carnot principle, which leads to the definition of entropy; and the Clausius principle, or law of increase in entropy.

Elementary Concepts and Fundamental Laws of the Theory of Heat

Science.gov (United States)

de Oliveira, Mário J.

2018-03-01

The elementary concepts and fundamental laws concerning the science of heat are examined from the point of view of its development with special attention to its theoretical structure. The development is divided into four periods, each one characterized by the concept that was attributed to heat. The transition from one to the next period was marked by the emergence of new concepts and new laws, and by singular events. We point out that thermodynamics, as it emerged, is founded on the elementary concepts of temperature and adiabatic wall, and on the fundamental laws: Mayer-Joule principle, or law of conservation of energy; Carnot principle, which leads to the definition of entropy; and the Clausius principle, or law of increase in entropy.

First results of out-of-pile experiments concerning cooling phenomena of molten layers with internal heat sources

International Nuclear Information System (INIS)

Fieg, G.

1977-01-01

After severe hypothetical reactor accidents, large amounts of molten core material with internal heat generation may appear. It must be guaranteed that these materials can be kept within the containment. To clarify this situation, the knowledge of heat transport from liquid layers with internal heat generation is needed. First experimental results on heat transport from internally heated horizontal fluid layers are presented. The experiments have been performed in a smooth horizontal vessel with the base of 15 x 15 cm 2 . The Joule-heated liquid layer (depth L = 1 cm - 3.5 cm) is enclosed between two isothermal horizontal walls. They are polished fore parts of heat exchangers. The temperatures of the walls were held constant with thermostatically controlled water circulating through the heat exchangers. Horizontal heat fluxes were depressed by appropriate insulation of the side walls. The total heat transport to the upper and lower boundaries has been measured by the mass transport through the heat exchangers and the temperature rise of the cooling water

Polar heating in Saturn's thermosphere

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C. G. A. Smith

2005-10-01

Full Text Available A 3-D numerical global circulation model of the Kronian thermosphere has been used to investigate the influence of polar heating. The distributions of temperature and winds resulting from a general heat source in the polar regions are described. We show that both the total energy input and its vertical distribution are important to the resulting thermal structure. We find that the form of the topside heating profile is particularly important in determining exospheric temperatures. We compare our results to exospheric temperatures from Voyager occultation measurements (Smith et al., 1983; Festou and Atreya, 1982 and auroral H₃⁺ temperatures from ground-based spectroscopic observations (e.g. Miller et al., 2000. We find that a polar heat source is consistent with both the Smith et al. determination of T_∞~400 K at ~30° N and auroral temperatures. The required heat source is also consistent with recent estimates of the Joule heating rate at Saturn (Cowley et al., 2004. However, our results show that a polar heat source can probably not explain the Festou and Atreya determination of T_∞~800 K at ~4° N and the auroral temperatures simultaneously.

Keywords. Ionosphere (Planetary ionosphere – Magnetospherica physics (Planetary magnetospheres – Meterology and atmospheric dynamics (Thermospheric dynamics

How specialized volatiles respond to chronic and short-term physiological and shock heat stress in Brassica nigra.

Science.gov (United States)

Kask, Kaia; Kännaste, Astrid; Talts, Eero; Copolovici, Lucian; Niinemets, Ülo

2016-09-01

Brassicales release volatile glucosinolate breakdown products upon tissue mechanical damage, but it is unclear how the release of glucosinolate volatiles responds to abiotic stresses such as heat stress. We used three different heat treatments, simulating different dynamic temperature conditions in the field to gain insight into stress-dependent changes in volatile blends and photosynthetic characteristics in the annual herb Brassica nigra (L.) Koch. Heat stress was applied by either heating leaves through temperature response curve measurements from 20 to 40 °C (mild stress), exposing plants for 4 h to temperatures 25-44 °C (long-term stress) or shock-heating leaves to 45-50 °C. Photosynthetic reduction through temperature response curves was associated with decreased stomatal conductance, while the reduction due to long-term stress and collapse of photosynthetic activity after heat shock stress were associated with non-stomatal processes. Mild stress decreased constitutive monoterpene emissions, while long-term stress and shock stress resulted in emissions of the lipoxygenase pathway and glucosinolate volatiles. Glucosinolate volatile release was more strongly elicited by long-term stress and lipoxygenase product released by heat shock. These results demonstrate that glucosinolate volatiles constitute a major part of emission blend in heat-stressed B. nigra plants, especially upon chronic stress that leads to induction responses. © 2016 John Wiley & Sons Ltd.

Evaluating long-term performance of in situ vitrified waste forms: Methodology and results

International Nuclear Information System (INIS)

McGrail, B.P.; Olson, K.M.

1992-11-01

In situ vitrification (ISV) is an emerging technology for the remediation of hazardous and radioactive waste sites. The concept relies on the principle of Joule heating to raise the temperature of a soil between an array of electrodes above the melting temperature. After cooling, the melt solidifies into a massive glass and crystalline block similar to naturally occurring obsidian. Determining the long-term performance of ISV products in a changing regulatory environment requires a fundamental understanding of the mechanisms controlling the dissolution behavior of the material. A series of experiments was performed to determine the dissolution behavior of samples produced from the ISV processing of typical soils from the Idaho National Engineering Laboratory subsurface disposal area. Dissolution rate constant measurements were completed at 90 degrees C over the pH range 2 to 11 for one sample obtained from a field test of the ISV process

Autonomous distributed temperature sensing for long-term heated applications in remote areas

Directory of Open Access Journals (Sweden)

A.-M. Kurth

2013-02-01

Full Text Available Distributed temperature sensing (DTS is a fiber-optical method enabling simultaneous temperature measurements over long distances. Electrical resistance heating of the metallic components of the fiber-optic cable provides information on the thermal characteristics of the cable's environment, providing valuable insight into processes occurring in the surrounding medium, such as groundwater–surface water interactions, dam stability or soil moisture. Until now, heated applications required direct handling of the DTS instrument by a researcher, rendering long-term investigations in remote areas impractical due to the often difficult and time-consuming access to the field site. Remote control and automation of the DTS instrument and heating processes, however, resolve the issue with difficult access. The data can also be remotely accessed and stored on a central database. The power supply can be grid independent, although significant infrastructure investment is required here due to high power consumption during heated applications. Solar energy must be sufficient even in worst case scenarios, e.g. during long periods of intense cloud cover, to prevent system failure due to energy shortage. In combination with storage batteries and a low heating frequency, e.g. once per day or once per week (depending on the season and the solar radiation on site, issues of high power consumption may be resolved. Safety regulations dictate adequate shielding and ground-fault protection, to safeguard animals and humans from electricity and laser sources. In this paper the autonomous DTS system is presented to allow research with heated applications of DTS in remote areas for long-term investigations of temperature distributions in the environment.

Long-term heat storage in calcium sulfoaluminate cement (CSA) based concrete

Energy Technology Data Exchange (ETDEWEB)

Kaufmann, Josef P.; Winnefeld, Frank [Empa Swiss Federal Laboratories for Materials Science and Technology, Duebendorf (Switzerland). Lab. for Concrete and Construction Chemistry

2011-07-01

in (long-term) storage of process heat. Any temperature source above about 80 C may be used.

Formulation of special glass frit and its use for decontamination of Joule melter employed for vitrification of high level and radioactive liquid waste

International Nuclear Information System (INIS)

Valsala, T.P.; Mishra, P.K.; Thakur, D.A.; Ghongane, D.E.; Jayan, R.V.; Dani, U.; Sonavane, M.S.; Kulkarni, Y.

2012-01-01

Advanced vitrification system at TWMP Tarapur was used for successful vitrification of large volume of HLW stored in waste tank farm. After completion of the operational life of the joule melter, dismantling was planned. Prior to the dismantling, the hold up inventory of active glass product from the melter was flushed out using specially formulated inactive glass frit to reduce the air activity buildup in the cell during dismantling operations. The properties of the special glass frit prepared are comparable with that of the regular product glass. More than 94% of holdup activity was flushed out from the joule melter prior to the dismantling of the melter. (author)

Turbulent Dynamics of Partially-Ionized Fluids in 2D

Science.gov (United States)

Benavides, S.; Flierl, G.

2017-12-01

Ionization occurs in the upper atmospheres of Hot Jupiters, as well asthe interiors of Gas Giants, leading to Magnetohydrodynamic (MHD) effectswhich can significantly alter the flow. The interactions of these MHDregions with the non-ionized atmosphere will occur in transitionregions where only a fraction of the fluid is ionized. We areexploring the dynamics of Partially-Ionized MHD (PIMHD) using a twofluid model - one neutral and one ionized and subject to MHD -coupled by a collision, or Joule heating, term proportional to thedifference in velocities. By varying both the ionization fraction aswell as the collision frequency (coupling), we examine the parameterspace of 2D PIMHD turbulence in hopes of better understanding itscharacteristics in certain, possibly realistic, regimes. We payparticular attention to the Joule heating term and its role indissipation and energy exchange between the two species. Thisknowledge will serve as the basis to further studies in which we lookat, in a more realistic setting, the PIMHD dynamics in Gas Giant orHot Jupiter atmospheres.

Ionosphere-thermosphere energy budgets for the ICME storms of March 2013 and 2015 estimated with GITM and observational proxies

Science.gov (United States)

Verkhoglyadova, O. P.; Meng, X.; Mannucci, A. J.; Mlynczak, M. G.; Hunt, L. A.; Lu, G.

2017-09-01

The ionosphere-thermosphere (IT) energy partitioning for the interplanetary coronal mass ejection (ICME) storms of 16-19 March 2013 and 2015 is estimated with the Global Ionosphere-Thermosphere Model (GITM), empirical models and proxies derived from in situ measurements. We focus on auroral heating, Joule heating, and thermospheric cooling. Solar wind data, F10.7, OVATION Prime model and the Weimer 2005 model are used to drive GITM from above. Thermospheric nitric oxide and carbon dioxide cooling emission powers and fluxes are estimated from TIMED/SABER measurements. Assimilative mapping of ionospheric electrodynamics (AMIE) estimations of hemispheric power and Joule heating are presented, based on data from global magnetometers, the AMPERE magnetic field data, SSUSI auroral images, and the SuperDARN radar network. Modeled Joule heating and auroral heating of the IT system are mostly controlled by external driving in the March 2013 and 2015 storms, while NO cooling persists into the storm recovery phase. The total heating in the model is about 1000 GW to 3000 GW. Additionally, we intercompare contributions in selected energy channels for five coronal mass ejection-type storms modeled with GITM. Modeled auroral heating shows reasonable agreement with AMIE hemispheric power and is higher than other observational proxies. Joule heating and infrared cooling are likely underestimated in GITM. We discuss challenges and discrepancies in estimating and global modeling of the IT energy partitioning, especially Joule heating, during geomagnetic storms.

Natural convection in an adiabatic vertical channel due to a dissipated heat element

International Nuclear Information System (INIS)

Ramos, M.A.M.S.

1986-01-01

An experimental study was perfomed on natural convection heat transfer to air in a vertical channel due to an isothermal heated element attached in one of the walls of the channel. The heated element dissipates heat due to the Joule effect. To determine the heat transfer coefficient, it is necessary to evaluate the heat transferred to air by natural convenction alone. Hence, the heat lost by the element due to conduction and radiation is evaluated in order to correct the measured heat transfer. The natural-convenction heat transfer coefficient is a function of the following parameters: the temperature difference between the element and the ambient air, the position of the element in the channel, and the channel spacing. An optimal value of the channel spacing, when the heat transfer coefficient attains its maximum value, was observed for each of the temperature difference investigated. These maximum values may be up to 25% higher than the value for the case of infinite spacing. Comparisons are made with results available in the literature for similar configurations, and the values found in this work are higher. (author) [pt

Heating effects in Rio Blanco rock

International Nuclear Information System (INIS)

Taylor, R.W.; Bowen, D.W.; Rossler, P.E.

1975-01-01

Samples of ''sandstone'' from near the site of the upper Rio Blanco nuclear explosion were heated in the laboratory at temperatures between 600 and 900 0 C. The composition and amount of noncondensable (dry) gas released were measured and compared to the amount and composition of gas found underground following the explosion. The gas released from the rock heated in the laboratory contained approximately 80 percent CO 2 and 10 percent H 2 ; the balance was CO and CH 4 . With increasing temperature, the amounts of CO 2 , CO, and H 2 released increased. The composition of gas released by heating Rio Blanco rock in the laboratory is similar to the composition of gas found after the nuclear explosion except that it contains less natural gas (CH 4 , C 2 H 6 . . .). The amount of noncondensable gas released by heating the rock increases from approximately 0.1 mole/kg of rock at 600 0 C to 0.9 mole/kg at 900 0 C. Over 90 percent of the volatile components of the rock are released in less than 10 h at 900 0 C. A comparison of the amount of gas released by heating rock in the laboratory to the amount of gas released by the heat of the Rio Blanco nuclear explosion suggests that the explosion released the volatile material from about 0.42 mg of rock per joule of explosive energy (1700 to 1800 tonnes per kt). (auth)

Diamagnetic measurement of JFT-2 plasma heated by neutral beam injection

International Nuclear Information System (INIS)

Maeno, Masaki; Sengoku, Seio; Yamamoto, Shin; Suzuki, Norio; Yamauchi, Toshihiko; Kawashima, Hisato; Miura, Yukitoshi

1984-01-01

A neutral beam was injected into the plasma in the JFT-2 tokamak, and the poloidal beta value βsub(p) of the plasma was determined by a diamagnetic method in which the change in the magnetic flux due to the plasma was obtained by measuring the very small perturbation of the current in the tokamak's toroidal field coil. The ratio of the perturbed to unperturbed currents in the coil was found to be (2-3) x 10 -4 . The poloidal beta value βsub(pd) determined by this method agrees within experimental error with that obtained from magnetic and energy profile analyses. βsub(pd) increases linearly with the total power Psub(net) deposited by the neutral beam in the plasma when Psub(net)=1.5 MW. The heating efficiency of the beam injection heating was found to be lower than that of Joule heating. (author)

Interference characterisation of a commercial Joule-Thomson cooler to be used in a SQUID-based foetal heart monitor

NARCIS (Netherlands)

Bangma, M.R.; Rijpma, A.P.; Vries, de E.; Reincke, H.A.; Holland, H.J.; Brake, ter H.J.M.; Rogalla, H.

2001-01-01

At the University of Twente, a fetal heart monitor based on a high-TC SQUID magnetometer system is under development. The purpose of this system is to measure a fetal heart signal in a clin. environment. For cooling a first demonstrator version, a closed-cycle Joule-Thomson cooler from APD

Solar heat storages in district heating networks

Energy Technology Data Exchange (ETDEWEB)

Ellehauge, K. (Ellehauge og Kildemoes, AArhus (DK)); Engberg Pedersen, T. (COWI A/S, Kgs. Lyngby (DK))

2007-07-15

This report gives information on the work carried out and the results obtained in Denmark on storages for large solar heating plants in district heating networks. Especially in Denmark the share of district heating has increased to a large percentage. In 1981 around 33% of all dwellings in DK were connected to a district heating network, while the percentage in 2006 was about 60% (in total 1.5 mio. dwellings). In the report storage types for short term storage and long term storages are described. Short term storages are done as steel tanks and is well established technology widely used in district heating networks. Long term storages are experimental and used in connection with solar heating. A number of solar heating plants have been established with either short term or long term storages showing economy competitive with normal energy sources. Since, in the majority of the Danish district heating networks the heat is produced in co-generation plants, i.e. plants producing both electricity and heat for the network, special attention has been put on the use of solar energy in combination with co-generation. Part of this report describes that in the liberalized electricity market central solar heating plants can also be advantageous in combination with co-generation plants. (au)

Metal-insulator transition upon heating and negative-differential-resistive-switching induced by self-heating in BaCo0.9Ni0.1S1.8

International Nuclear Information System (INIS)

Fisher, B.; Genossar, J.; Chashka, K. B.; Patlagan, L.; Reisner, G. M.

2014-01-01

The layered compound BaCo 1−x Ni x S 2−y (0.05  1−x Ni x S 2−y (nominal x = 0.1 and y = 0.2). These were due to the steep metal to insulator transition upon heating followed by the activated behavior of the resistivity above the transition. The major role of Joule heating in switching is supported by the absence of nonlinearity in the current as function of voltage, I(V), obtained in pulsed measurements, in the range of electric fields relevant to d.c. measurements. The voltage-controlled negative differential resistance around the threshold for switching was explained by a simple model of self-heating. The main difficulty in modeling I(V) from the samples resistance as function of temperature R(T) was the progressive increase of R(T), and to a lesser extend the decrease of the resistance jumps at the transitions, caused by the damage induced by cycling through the transitions by heating or self-heating. This was dealt with by following systematically R(T) over many cycles and by using the data of R(T) in the heating cycle closest to that of the self-heating one

The role of large‐scale heat pumps for short term integration of renewable energy

DEFF Research Database (Denmark)

Mathiesen, Brian Vad; Blarke, Morten; Hansen, Kenneth

2011-01-01

technologies is focusing on natural working fluid hydrocarbons, ammonia, and carbon dioxide. Large-scale heat pumps are crucial for integrating 50% wind power as anticipated to be installed in Denmark in 2020, along with other measures. Also in the longer term heat pumps can contribute to the minimization...... savings with increased wind power and may additionally lead to economic savings in the range of 1,500-1,700 MDKK in total in the period until 2020. Furthermore, the energy system efficiency may be increased due to large heat pumps replacing boiler production. Finally data sheets for large-scale ammonium......In this report the role of large-scale heat pumps in a future energy system with increased renewable energy is presented. The main concepts for large heat pumps in district heating systems are outlined along with the development for heat pump refrigerants. The development of future heat pump...

Project Physics Text 3, The Triumph of Mechanics.

Science.gov (United States)

Harvard Univ., Cambridge, MA. Harvard Project Physics.

Mechanical theories are presented in this unit of the Project Physics text for senior high students. Collisions, Newton's laws, isolated systems, and Leibniz' concept are discussed, leading to conservation of mass and momentum. Energy conservation is analyzed in terms of mechanical energy, heat energy, steam engines, Watt's engine, Joule's…

Numerical Investigation on the Impact of Anode Change on Heat Transfer and Fluid Flow in Aluminum Smelting Cells

Science.gov (United States)

Wang, Qiang; Gosselin, Louis; Fafard, Mario; Peng, Jianping; Li, Baokuan

2016-04-01

In order to understand the impact of anode change on heat transfer and magnetohydrodynamic flow in aluminum smelting cells, a transient three-dimensional (3D) coupled mathematical model has been developed. The solutions of the mass, momentum, and energy conservation equations were simultaneously implemented by the finite volume method with full coupling of the Joule heating and Lorentz force through solving the electrical potential equation. The volume of fluid approach was employed to describe the two-phase flow. The phase change of molten electrolyte (bath) as well as molten aluminum (metal) was modeled by an enthalpy-based technique, where the mushy zone is treated as a porous medium with a porosity equal to the liquid fraction. The effect of the new anode temperature on recovery time was also analyzed. A reasonable agreement between the test data and simulated results is obtained. The results indicate that the temperature of the bath under cold anodes first decreases reaching the minimal value and rises under the effect of increasing Joule heating, and finally returns to steady state. The colder bath decays the velocity, and the around ledge becomes thicker. The lowest temperature of the bath below new anodes increases from 1118 K to 1143 K (845 °C to 870 °C) with the new anode temperature ranging from 298 K to 498 K (25°C to 225°C), and the recovery time reduces from 22.5 to 20 hours.

Roles of Clathrate Hydrates in Crustal Heating and Volatile Storage/Release on Earth, Mars, and Beyond

Science.gov (United States)

Kargel, J. S.; Beget, J.; Furfaro, R.; Prieto-Ballesteros, O.; Palmero-Rodriguez, J. A.

2007-12-01

Clathrate hydrates are stable through much of the Solar System. These materials and hydrate-like amorphous associations of water with N2, CO, CH4, CO2, O2 and other molecules could, in fact, constitute the bulk of the non-rock components of some icy satellites, comets, and Kuiper Belt Objects. CO2 clathrate is thermodynamically stable at the Martian South Pole surface and could form a significant fraction of both Martian polar caps and icy permafrost distributed across one-third of the Martian surface. CH4 clathrate is the largest clathrate material in Earth's permafrost and cold seafloor regions, and it may be a major volatile reservoir on Mars, too. CO2 clathrate is less abundant on Earth but it might store most of Mars' CO2 inventory and thus may be one of the critical components in the climate system of that planet, just as CH4 clathrate is for Earth. These ice-like phases not only store biologically, geologically, and climatologically important gases, but they also are natural thermal insulators. Thus, they retard the conductive flow of geothermal heat, and thick accumulations of them can modify geotherms, cause brines to exist where otherwise they would not, and induce low-grade metamorphism of upper crustal rocks underlying the insulating bodies. This mechanism of crustal heating may be especially important in assisting hydrogeologic activity on Mars, gas-rich carbonaceous asteroids, icy satellites, and Kuiper Belt Objects. These worlds, compared to Earth, are comparatively energy starved and frozen but may partly make up for their deficit of joules by having large accumulations of joule-conserving hydrates. Thick, continuous layers of clathrate may seal in gases and produce high gas fugacities in aquifers underlying the clathrates, thus producing gas-rich reservoirs capable of erupting violently. This may have happened repeatedly in Earth history, with global climatic consequences for abrupt climate change. We have hypothesized that such eruptions may have

Overview of the ARGOS X-ray framing camera for Laser MegaJoule

Energy Technology Data Exchange (ETDEWEB)

Trosseille, C., E-mail: clement.trosseille@cea.fr; Aubert, D.; Auger, L.; Bazzoli, S.; Brunel, P.; Burillo, M.; Chollet, C.; Jasmin, S.; Maruenda, P.; Moreau, I.; Oudot, G.; Raimbourg, J.; Soullié, G.; Stemmler, P.; Zuber, C. [CEA, DAM, DIF, F-91297 Arpajon (France); Beck, T. [CEA, DEN, CADARACHE, F-13108 St Paul lez Durance (France); Gazave, J. [CEA, DAM, CESTA, F-33116 Le Barp (France)

2014-11-15

Commissariat à l’Énergie Atomique et aux Énergies Alternatives has developed the ARGOS X-ray framing camera to perform two-dimensional, high-timing resolution imaging of an imploding target on the French high-power laser facility Laser MegaJoule. The main features of this camera are: a microchannel plate gated X-ray detector, a spring-loaded CCD camera that maintains proximity focus in any orientation, and electronics packages that provide remotely-selectable high-voltages to modify the exposure-time of the camera. These components are integrated into an “air-box” that protects them from the harsh environmental conditions. A miniaturized X-ray generator is also part of the device for in situ self-testing purposes.

A novel TRNSYS type for short-term borehole heat exchanger simulation: B2G model

International Nuclear Information System (INIS)

De Rosa, Mattia; Ruiz-Calvo, Félix; Corberán, José M.; Montagud, Carla; Tagliafico, Luca A.

2015-01-01

Highlights: • A novel dynamic borehole heat exchanger model is presented. • Theoretical approach for model parameters calculation is described. • The short-term model is validated against experimental data of a real GSHP. • Strong dynamic conditions due to the ON–OFF regulation are investigated. - Abstract: Models of ground source heat pump (GSHP) systems are used as an aid for the correct design and optimization of the system. For this purpose, it is necessary to develop models which correctly reproduce the dynamic thermal behavior of each component in a short-term basis. Since the borehole heat exchanger (BHE) is one of the main components, special attention should be paid to ensuring a good accuracy on the prediction of the short-term response of the boreholes. The BHE models found in literature which are suitable for short-term simulations usually present high computational costs. In this work, a novel TRNSYS type implementing a borehole-to-ground (B2G) model, developed for modeling the short-term dynamic performance of a BHE with low computational cost, is presented. The model has been validated against experimental data from a GSHP system located at Universitat Politècnica de València, Spain. Validation results show the ability of the model to reproduce the short-term behavior of the borehole, both for a step-test and under normal operating conditions

Transient Performance of Air-cooled Condensing Heat Exchanger in Long-term Passive Cooling System during Decay Heat Load

Energy Technology Data Exchange (ETDEWEB)

Kim, Myoung Jun; Lee, Hee Joon [Kookmin University, Seoul (Korea, Republic of); Moon, Joo Hyung; Bae, Youngmin; Kim, Young-In [KAERI, Daejeon (Korea, Republic of)

2015-05-15

In the event of a 'loss of coolant accident'(LOCA) and a non-LOCA, the secondary passive cooling system would be activated to cool the steam in a condensing heat exchanger that is immersed in an emergency cooldown tank (ECT). Currently, the capacities of these ECTs are designed to be sufficient to remove the sensible and residual heat from the reactor coolant system for 72 hours after the occurrence of an accident. After the operation of a conventional passive cooling system for an extended period, however, the water level falls as a result of the evaporation from the ECT, as steam is emitted from the open top of the tank. Therefore, the tank should be refilled regularly from an auxiliary water supply system when the system is used for more than 72 hours. Otherwise, the system would fail to dissipate heat from the condensing heat exchanger due to the loss of the cooling water. Ultimately, the functionality of the passive cooling system would be seriously compromised. As a passive means of overcoming the water depletion in the tank, Kim et al. applied for a Korean patent covering the concept of a long-term passive cooling system for an ECT even after 72 hours. This study presents transient performance of ECT with installing air-cooled condensing heat exchanger under decay heat load. The cooling capacity of an air-cooled condensing heat exchanger was evaluated to determine its practicality.

The dismantling of the one-third-scale Joule ceramic melter and preliminary investigation of electrode corrosion

International Nuclear Information System (INIS)

Morris, J.B.; Walmsley, D.; Hollinrake, A.; Horsley, G.

1986-01-01

The Harwell one-third scale Joule ceramic melter was dismantled to discover the cause of a fall in electric resistance. The two inconel-690 electrodes were corroded over the lower 40mm sections and were examined by optical and electron microscopy. Sedimentation of Ru species on the floor of the melter may have led to corrosion of the electrodes. Glass withdrawn from the canisters was analyzed for evidence of a segregation mechanism. (UK)

High-power optical coatings for a mega-joule class ICF laser

International Nuclear Information System (INIS)

Kozlowski, M.R.; Thomas, I.M.; Campbell, J.H.; Rainer, F.

1992-11-01

As a consequence of advancements in Inertial Confinement Fusion research, LLNL is developing plans for a new 1.5 to 2 mega-joule solid-state Nd:glass laser designed to achieve fusion ignition. The new design is possible in part due to advances in optical coatings suitable for high power laser systems. High damage threshold mirrors and polarizers are comprised of electron beam deposited dielectric multilayers. Subthreshold illumination, or laser conditioning, of the multilayer coatings results in an increase in the damage thresholds by factors of 2 to 3 at 1.06μm, thus meeting the fluence requirements of the advanced architecture. For anti-reflective coatings, protective organic coatings for non-linear crystals and phase plates for beam smoothing, sol-gel films provide high damage thresholds coatings at low cost

Efficient heat generation in large-area graphene films by electromagnetic wave absorption

Science.gov (United States)

Kang, Sangmin; Choi, Haehyun; Lee, Soo Bin; Park, Seong Chae; Park, Jong Bo; Lee, Sangkyu; Kim, Youngsoo; Hong, Byung Hee

2017-06-01

Graphene has been intensively studied due to its outstanding electrical and thermal properties. Recently, it was found that the heat generation by Joule heating of graphene is limited by the conductivity of graphene. Here we suggest an alternative method to generate heat on a large-area graphene film more efficiently by utilizing the unique electromagnetic (EM) wave absorption property of graphene. The EM wave induces an oscillating magnetic moment generated by the orbital motion of moving electrons, which efficiently absorbs the EM energy and dissipate it as a thermal energy. In this case, the mobility of electron is more important than the conductivity, because the EM-induced diamagnetic moment is directly proportional to the speed of electron in an orbital motion. To control the charge carrier mobility of graphene we functionalized substrates with self-assembled monolayers (SAM). As the result, we find that the graphene showing the Dirac voltage close to zero can be more efficiently heated by EM waves. In addition, the temperature gradient also depends on the number of graphene. We expect that the efficient and fast heating of graphene films by EM waves can be utilized for smart heating windows and defogging windshields.

Prediction of long-term precipitate evolution in austenitic heat-resistant steels

Energy Technology Data Exchange (ETDEWEB)

Shim, Jae-Hyeok; Jung, Woo-Sang; Cho, Young Whan [Korea Institute of Science and Technology, Seoul (Korea, Republic of). Materials/Devices Div.; Kozeschnik, Ernst [Vienna Univ. of Technology (Austria). Inst. of Materials Science and Technology

2010-07-01

Numerical prediction of the long-term precipitate evolution in five different austenitic heat-resistant stainless steels, NF709, Super304H, Sanicro25, CF8C-PLUS and HTUPS has been carried out. MX and M{sub 23}C{sub 6} are predicted to remain as major precipitates during long-term aging in these steels. The addition of 3 wt% Cu produces very fine Cu-rich precipitates during aging in Super304H and Sanicro25. It is found that the amount of Z phase start to increase remarkably between 1,000 and 10,000 hours of aging at the expense of MX precipitates in the steels containing a high nitrogen content. However, the growth rate of Z phase is relatively slow and its average size reaches at most a few tens of nanometers after 100,000 hours of aging at 700 C, compared with 9-12% Cr ferritic/martensitic heat-resistant steels. The predicted precipitation sequence and precipitate size during aging are in general agreement with experimental observations. (orig.)

Controlled heat flux measurement across a closing nanoscale gap and its comparison to theory

Energy Technology Data Exchange (ETDEWEB)

Ma, Y.; Ghafari, A.; Budaev, B. V.; Bogy, D. B., E-mail: dbogy@berkeley.edu [Department of mechanical Engineering, Computer Mechanics Lab, University of California, Berkeley, California 94720 (United States)

2016-05-23

We present here a controlled measurement of heat flux across a closing gap that is initially less than 10 nm wide between two solid surfaces at different temperatures. The measured heat transfer is compared with our published theoretical analyses of this phenomenon that show thermal radiation dominates the heat transfer for gaps wider than about 1–2 nm, but phonon conduction dominates between 1 and 2 nm and contact. The experiments employ a thermal actuator mounted on a rocking base block for coarse positioning that supplies Joule heating to an embedded element to cause thermal expansion of a localized region for less than 10 nm spacing control, together with an embedded near-surface resistive temperature sensor to measure its temperature change due to the heat flux across the gap. The measured results are in general agreement with the theoretical predictions, and they also agree with common sense expectations. This paper not only shows nano-scale heat transfer measurement across a closing gap, it also lends additional strong support to the validity of the referenced theoretical developments. The proposed experimental approach can provide support to design of future devices for nano-scale heat transfer measurement.

Heat capacity and Joule-Thomson coefficient of selected n-alkanes at 0.1 and 10 MPa in broad temperature ranges

DEFF Research Database (Denmark)

Regueira Muñiz, Teresa; Varzandeh, Farhad; Stenby, Erling Halfdan

2017-01-01

Isobaric heat capacity of six n-alkanes, i.e. n-hexane, n-octane, n-decane, n-dodecane, n-tetradecane and n-hexadecane, was determined with a Calvet type differential heat-flux calorimeter at 0.1 and 10 MPa in a broad temperature range. The measured isobaric heat capacity data were combined...

Steady state heat transfer experimental studies of LHC superconducting cables operating in cryogenic environment of superfluid helium

CERN Document Server

Santandrea, Dario; Tuccillo, Raffaele; Granieri, Pier Paolo

The heat management is a basic and fundamental aspect of the superconducting magnets used in the CERN Large Hadron Collider. Indeed, the coil temperature must be kept below the critical value, despite the heat which can be generated or deposited in the magnet during the normal operations. Therefore, this thesis work aims at determining the heating power which can be extracted from the superconducting cables of the LHC, specially through their electrical insulation which represents the main thermal barrier. An experimental measurement campaign in superfluid helium bath was performed on several samples reproducting the main LHC magnets. The heating power was generated in the sample by Joule heating and the temperature increase was measured by means of Cernox bare chip and thermocouples. An innovative instrumentation technique which also includes the in-situ calibration of the thermocouples was developed. A thorough uncertainty analysis on the overall measurement chain concluded the experimental setup. The prese...

Experimental data on heat flux distribution from a volumetrically heated pool with frozen boundaries

International Nuclear Information System (INIS)

Helle, Maria; Kymaelaeinen, Olli; Tuomisto, Harri

1999-01-01

The COPO II experiments are confirmatory experiments and a continuation project to the earlier COPO I experiments. As in COPO 1, a molten corium pool on the lower head of a RPV is simulated by a two - dimensional slice of it in linear scale 1:2. The corium is simulated by water-zinc sulfate solution with volumetric Joule heating. The heat flux distribution on the boundaries and the temperature distribution in the pool are measured. The major new feature in COPO II is the cooling arrangement which is based on circulation of liquid nitrogen on the outside of the pool boundaries. The use of liquid nitrogen leads to formation of ice on the inside of boundaries. Two geometrically different versions of the COPO II facility have been constructed: one with a tori-spherical bottom shape, simulating the RPV of a VVER-440 reactor as COPO I, and another one with semicircular bottom simulating a western PWR such as AP600. The modified Rayleigh number in the COPO II experiments corresponds to the one in a prototypic corium pool (∼ 10 15 ). This paper reports results from the COPO II-Lo and COPO II-AP experiments with homogenous pool. Results indicate that the upward heat fluxes are in agreement with the results of the COPO I experiments. Also, as expected, the time averaged upward heat flux profile was relatively flat. On the other hand, the heat fluxes at the side and bottom boundaries of the pool were slightly higher in COPO II-Lo than in COPO I. In COPO II-AP, the average heat transfer coefficients to the curved boundary were higher than predicted by Jahn's and Mayinger's correlation, but slightly lower than in BALI experiments. (authors)

Electrical initiation of an energetic nanolaminate film

Science.gov (United States)

Tringe, Joseph W.; Gash, Alexander E.; Barbee, Jr., Troy W.

2010-03-30

A heating apparatus comprising an energetic nanolaminate film that produces heat when initiated, a power source that provides an electric current, and a control that initiates the energetic nanolaminate film by directing the electric current to the energetic nanolaminate film and joule heating the energetic nanolaminate film to an initiation temperature. Also a method of heating comprising providing an energetic nanolaminate film that produces heat when initiated, and initiating the energetic nanolaminate film by directing an electric current to the energetic nanolaminate film and joule heating the energetic nanolaminate film to an initiation temperature.

Flux loss and heating during the formation of a field-reversed configuration

International Nuclear Information System (INIS)

Sgro, A.G.; Armstrong, W.T.; Lipson, J.; Tuszewski, M.G.; Cochrane, J.C.

1982-01-01

The simulated time evolution of magnetic field profiles and trapped flux in a field-reversed configuration, when compared with the experiment, implies that the rapid decay of the initial reversed flux is due to a resistivity that is anomalously enhanced over its classical value. A tenuous plasma between the field-reversed configuration and the wall carries a significant fraction of the current, and about half of the anomalous Joule heating must be deposited directly in the ions in order to calculate the correct ion temperature. The fractional flux retention is most sensitive to an increase of applied bias field

Description of processes for the immobilization of selected transuranic wastes

International Nuclear Information System (INIS)

Timmerman, C.L.

1980-12-01

Processed sludge and incinerator-ash wastes contaminated with transuranic (TRU) elements may require immobilization to prevent the release of these elements to the environment. As part of the TRU Waste Immobilization Program sponsored by the Department of Energy (DOE), the Pacific Northwest Laboratory is developing applicable waste-form and processing technology that may meet this need. This report defines and describes processes that are capable of immobilizing a selected TRU waste-stream consisting of a blend of three parts process sludge and one part incinerator ash. These selected waste streams are based on the compositions and generation rates of the waste processing and incineration facility at the Rocky Flats Plant. The specific waste forms that could be produced by the described processes include: in-can melted borosilicate-glass monolith; joule-heated melter borosilicate-glass monolith or marble; joule-heated melter aluminosilicate-glass monolith or marble; joule-heated melter basaltic-glass monolith or marble; joule-heated melter glass-ceramic monolith; cast-cement monolith; pressed-cement pellet; and cold-pressed sintered-ceramic pellet

Wear, creep, and frictional heating of femoral implant articulating surfaces and the effect on long-term performance--Part II, Friction, heating, and torque.

Science.gov (United States)

Davidson, J A; Schwartz, G; Lynch, G; Gir, S

1988-04-01

In Part I, (J.A. Davidson and G. Schwartz, "Wear, creep, and frictional heating of femoral implant articulating surfaces and the effect on long-term performance--Part I, A review," J. Biomed. Mater. Res., 21, 000-000 (1987) it was shown that lubrication of the artificial hip joint was complex and that long-term performance is governed by the combined wear, creep, and to a lesser extent, oxidation degradation of the articulating materials. Importantly, it was shown that a tendency for heating exists during articulation in the hip joint and that elevated temperatures can increase the wear, creep, and oxidation degradation rate of UHMWPE. The present study was performed to examine closely the propensity to generate heat during articulation in a hip joint simulator. The systems investigated were polished Co-Cr-Mo alloy articulating against UHMWPE, polished alumina ceramic against UHMWPE, and polished alumina against itself. Frictional torque was also evaluated for each system at various levels of applied loads. A walking load history was used in both the frictional heating and torque tests. The majority of tests were performed with 5 mL of water lubricant. However, the effect of various concentrations of hyaluronic acid was also evaluated. Results showed frictional heating to occur in all three systems, reaching an equilibrium after roughly 30 min articulation time. Ceramic systems showed reduced levels of heating compared to the cobalt alloy-UHMWPE system. The level of frictional torque for each system ranked similar to their respective tendencies to generate heat. Hyaluronic acid had little effect, while dry conditions and the presence of small quantities of bone cement powder in water lubricant significantly increased frictional torque.

Testing of a 4 K to 2 K heat exchanger with an intermediate pressure drop

Energy Technology Data Exchange (ETDEWEB)

Knudsen, Peter N. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Ganni, Venkatarao [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

2015-12-01

Most large sub-atmospheric helium refrigeration systems incorporate a heat exchanger at the load, or in the distribution system, to counter-flow the sub-atmospheric return with the super-critical or liquid supply. A significant process improvement is theoretically obtainable by handling the exergy loss across the Joule-Thompson throttling valve supplying the flow to the load in a simple but different manner. As briefly outlined in previous publications, the exergy loss can be minimized by allowing the supply flow pressure to decrease to a sub-atmospheric pressure concurrent with heat exchange flow from the load. One practical implementation is to sub-divide the supply flow pressure drop between two heat exchanger sections, incorporating an intermediate pressure drop. Such a test is being performed at Jefferson Lab's Cryogenic Test Facility (CTF). This paper will briefly discuss the theory, practical implementation and test results and analysis obtained to date.

Effect of short- and long-term heat stress on the conception risk of dairy cows under natural service and artificial insemination breeding programs.

Science.gov (United States)

Schüller, L-K; Burfeind, O; Heuwieser, W

2016-04-01

The objectives of this retrospective study were to examine the effect of heat stress on natural service and artificial insemination (AI) breeding methods. We investigated the influence of short- and long-term heat stress on the conception risk (CR) of dairy cows bred by natural service or by AI with frozen-thawed or fresh semen. In addition, the relationship between breeding method and parity was determined. Cows bred by AI with frozen-thawed semen exposed to long-term heat stress (mean temperature-humidity index ≥73 in the period 21d before breeding) were 63% less likely to get pregnant compared with cows not exposed to heat stress. Cows bred by AI with fresh semen were 80% less likely to get pregnant during periods of short-term heat stress than during periods without heat stress. Furthermore, multiparous cows bred by AI with frozen-thawed or fresh semen were 22 and 67% less likely to get pregnant, respectively, than primiparous cows. No influence of heat stress or parity was noted on the CR of cows bred by natural service. The present study indicates that the likelihood of dairy cows becoming pregnant is reduced by short- and long-term heat stress depending on the type of semen employed. In particular, CR of cows inseminated with fresh semen is negatively affected by short-term heat stress and CR of cows inseminated with frozen-thawed semen is negatively affected by long-term heat stress. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Heat balance structure of canopies at extreme precipitation in view of long-term records

International Nuclear Information System (INIS)

Bubnowska, J.; Gąsiorek, E.; Łabędzki, L.; Musiał, E.

2005-01-01

Increasing frequency of extreme weather conditions is attributed to the global variations in climate. Heat balance of substrate is one of the processes affecting the climate. Variations of heat balance in spring wheat during the growing seasons (April-August) and in potatoes during the growing seasons (May-September) with maximal and minimal precipitation are confronted here with long term changes of the balance. Two regions Wroclaw-Swojec (1964-2000) and Bydgoszcz (1945-2003) were involved in the study [pl

Sound speed of isobaric heat capacity in the saturated and superheated vapour of cesium, rubidium and potassium

International Nuclear Information System (INIS)

Novikov, I.I.; Roschupkin, V.V.

1985-01-01

The paper reviews the work carried out on the thermodynamic properties of alkali metal vapours. The most systematic investigations concern the sound velocity measurements for saturated and superheated vapours of caesium, for saturated vapour of rubidium, and for superheated vapour of potassium. The Joule-Thompson coefficient has been studied in caesium vapour, and the isobaric heat capacity of potassium vapour has also been examined. The experimental methods for all these experiments are described, and the data obtained are presented in tabular form. (U.K.)

Particle Acceleration and Plasma Heating in the Chromosphere

Science.gov (United States)

Zaitsev, V. V.; Stepanov, A. V.

2015-12-01

We propose a new mechanism of electron acceleration and plasma heating in the solar chromosphere, based on the magnetic Rayleigh-Taylor instability. The instability develops at the chromospheric footpoints of a flare loop and deforms the local magnetic field. As a result, the electric current in the loop varies, and a resulting inductive electric field appears. A pulse of the induced electric field, together with the pulse of the electric current, propagates along the loop with the Alfvén velocity and begins to accelerate electrons up to an energy of about 1 MeV. Accelerated particles are thermalized in the dense layers of the chromosphere with the plasma density n ≈10^{14} - 10^{15} cm^{-3}, heating them to a temperature of about several million degrees. Joule dissipation of the electric current pulse heats the chromosphere at heights that correspond to densities n ≤10^{11} - 10^{13} cm^{-3}. Observations with the New Solar Telescope at Big Bear Solar Observatory indicate that chromospheric footpoints of coronal loops might be heated to coronal temperatures and that hot plasma might be injected upwards, which brightens ultra-fine loops from the photosphere to the base of the corona. Thereby, recent observations of the Sun and the model we propose stimulate a déjà vu - they are reminiscent of the concept of the chromospheric flare.

Marangoni convection in Casson liquid flow due to an infinite disk with exponential space dependent heat source and cross-diffusion effects

Science.gov (United States)

Mahanthesh, B.; Gireesha, B. J.; Shashikumar, N. S.; Hayat, T.; Alsaedi, A.

2018-06-01

Present work aims to investigate the features of the exponential space dependent heat source (ESHS) and cross-diffusion effects in Marangoni convective heat mass transfer flow due to an infinite disk. Flow analysis is comprised with magnetohydrodynamics (MHD). The effects of Joule heating, viscous dissipation and solar radiation are also utilized. The thermal and solute field on the disk surface varies in a quadratic manner. The ordinary differential equations have been obtained by utilizing Von Kármán transformations. The resulting problem under consideration is solved numerically via Runge-Kutta-Fehlberg based shooting scheme. The effects of involved pertinent flow parameters are explored by graphical illustrations. Results point out that the ESHS effect dominates thermal dependent heat source effect on thermal boundary layer growth. The concentration and temperature distributions and their associated layer thicknesses are enhanced by Marangoni effect.

Long-term trends of heat stress and energy use implications in subtropical climates

Energy Technology Data Exchange (ETDEWEB)

Lam, Joseph C.; Wan, Kevin K.W.; Wong, S.L.; Lam, Tony N.T. [Building Energy Research Group, Department of Building and Construction, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong SAR (China)

2010-02-15

Past and future trends of human comfort in terms of heat and cold stresses under the local subtropical climates using measured meteorological data as well as predictions from general climate models were investigated. Summer discomfort showed an increasing trend (and winter discomfort a decreasing trend) over the past 41 years from 1968 to 2008. Monthly mean minimum and maximum temperatures and moisture content predictions from a general climate model (MIROC3.2-H) were used to determine summer and winter discomfort for future years (2009-2100) based on two emissions scenarios B1 and A1B (low and medium forcing). The 92-year (2009-2100) mean cold stress would be reduced from the 41-year (1968-2008) mean value of 8.7 to about three for both emissions scenarios. The 92-year mean heat stress would be 115.9 and 120.6 for B1 and A1B, respectively, representing 31.6% and 36.9% increase over the 1968-2008 long-term average of 88.1. These suggest that the already small winter heating requirement in subtropical Hong Kong would become even more insignificant in future years, whereas the increasing trend of summer discomfort would result in more cooling demand in the built environment. (author)

Effects of long-term heat stress and dietary restriction on the expression of genes of steroidogenic pathway and small heat-shock proteins in rat testicular tissue.

Science.gov (United States)

Bozkaya, F; Atli, M O; Guzeloglu, A; Kayis, S A; Yildirim, M E; Kurar, E; Yilmaz, R; Aydilek, N

2017-08-01

The aim was to investigate the effects of long-term heat stress and dietary restriction on the expression of certain genes involving in steroidogenic pathway and small heat-shock proteins (sHSPs) in rat testis. Sprague Dawley rats (n = 24) were equally divided into four groups. Group I and II were kept at an ambient temperature of 22°C, while Groups III and IV were reared at 38°C for 9 weeks. Feed was freely available for Group I and Group III, while Group II and Group IV were fed 60% of the diet consumed by their ad libitum counterparts. At the end of 9 weeks, testicles were collected under euthanasia. Total RNA was isolated from testis tissue samples. Expression profiles of the genes encoding androgen-binding protein, follicle-stimulating hormone receptor, androgen receptor, luteinising hormone receptor, steroidogenic acute regulatory protein (StAR), cyclooxygenase-2 and sHSP genes were assessed at mRNA levels using qPCR. Long-term heat stress decreased the expression of StAR and HspB10 genes while dietary restriction upregulated StAR gene expression. The results suggested that long-term heat stress negatively affected the expression of StAR and HspB10 genes and the dietary restriction was able to reverse negative effect of heat stress on the expression of StAR gene in rat testis. © 2016 Blackwell Verlag GmbH.

Isothermal calorimeter for measurements of time-dependent heat generation rate in individual supercapacitor electrodes

Science.gov (United States)

Munteshari, Obaidallah; Lau, Jonathan; Krishnan, Atindra; Dunn, Bruce; Pilon, Laurent

2018-01-01

Heat generation in electric double layer capacitors (EDLCs) may lead to temperature rise and reduce their lifetime and performance. This study aims to measure the time-dependent heat generation rate in individual carbon electrode of EDLCs under various charging conditions. First, the design, fabrication, and validation of an isothermal calorimeter are presented. The calorimeter consisted of two thermoelectric heat flux sensors connected to a data acquisition system, two identical and cold plates fed with a circulating coolant, and an electrochemical test section connected to a potentiostat/galvanostat system. The EDLC cells consisted of two identical activated carbon electrodes and a separator immersed in an electrolyte. Measurements were performed on three cells with different electrolytes under galvanostatic cycling for different current density and polarity. The measured time-averaged irreversible heat generation rate was in excellent agreement with predictions for Joule heating. The reversible heat generation rate in the positive electrode was exothermic during charging and endothermic during discharging. By contrast, the negative electrode featured both exothermic and endothermic heat generation during both charging and discharging. The results of this study can be used to validate existing thermal models, to develop thermal management strategies, and to gain insight into physicochemical phenomena taking place during operation.

Energy-Saving Sintering of Electrically Conductive Powders by Modified Pulsed Electric Current Heating Using an Electrically Nonconductive Die

Science.gov (United States)

Ito, Mikio; Kawahara, Kenta; Araki, Keita

2014-04-01

Sintering of Cu and thermoelectric Ca3Co4O9 was tried using a modified pulsed electric current sintering (PECS) process, where an electrically nonconductive die was used instead of a conventional graphite die. The pulsed electric current flowed through graphite punches and sample powder, which caused the Joule heating of the powder compact itself, resulting in sintering under smaller power consumption. Especially for the Ca3Co4O9 powder, densification during sintering was also accelerated by this modified PECS process.

Extreme degree of ionization in homogenous micro-capillary plasma columns heated by ultrafast current pulses.

Science.gov (United States)

Avaria, G; Grisham, M; Li, J; Tomasel, F G; Shlyaptsev, V N; Busquet, M; Woolston, M; Rocca, J J

2015-03-06

Homogeneous plasma columns with ionization levels typical of megaampere discharges are created by rapidly heating gas-filled 520-μm-diameter channels with nanosecond rise time current pulses of 40 kA. Current densities of up to 0.3  GA cm^{-2} greatly increase Joule heating with respect to conventional capillary discharge Z pinches, reaching unprecedented degrees of ionization for a high-Z plasma column heated by a current pulse of remarkably low amplitude. Dense xenon plasmas are ionized to Xe^{28+}, while xenon impurities in hydrogen discharges reach Xe^{30+}. The unique characteristics of these hot, ∼300:1 length-to-diameter aspect ratio plasmas allow the observation of unexpected spectroscopic phenomena. Axial spectra show the unusual dominance of the intercombination line over the resonance line of He-like Al by nearly an order of magnitude, caused by differences in opacities in the axial and radial directions. These plasma columns could enable the development of sub-10-nm x-ray lasers.

The effect of local heat on term neonates pain intensity during heel-blood sampling

Directory of Open Access Journals (Sweden)

R. GHobadi Mohebi

2017-04-01

Full Text Available Aims: Newborns are more sensitive to pain than adults and are more susceptible to the long-term complications of pain. So, it is necessary to use procedures for reducing pain in newborns. The aim of this study was to determine the effect of local heat on the pain intensity of heel-blood sampling in the term newborns. Material & Methods: In this randomized controlled clinical trial study, in 2012, 63 healthy 3 to 5-day newborns who were referred to Shahid Delkhah Health Center in Ferdows were selected by random sampling method and randomly divided into 3 groups (21 people in each group: test (heat, placebo (sound and control. The pain intensity of newborns before, during and after heel-blood sampling was evaluated. The data collection tools were demographic questionnaire and Neonatal Infant Pain Scale (NIPS. Data were analyzed by SPSS 14.5 software and chi-square test, one-way ANOVA, Tukey's post hoc test, and ANOVA with repeated observations. Finding: The mean pain intensity in the three groups was not significantly different before intervention (p=0.86, but the mean pain intensity was lower in the test group than in the other two groups (p=0.006. After heel-blood sampling, the mean pain intensity was the least in the test group and was the most in the control group (p<0.001. Conclusion: Local heat during and after heel blood sampling decreases pain intensity in the term newborns.

A numerical model for boiling heat transfer coefficient of zeotropic mixtures

Science.gov (United States)

Barraza Vicencio, Rodrigo; Caviedes Aedo, Eduardo

2017-12-01

Zeotropic mixtures never have the same liquid and vapor composition in the liquid-vapor equilibrium. Also, the bubble and the dew point are separated; this gap is called glide temperature (Tglide). Those characteristics have made these mixtures suitable for cryogenics Joule-Thomson (JT) refrigeration cycles. Zeotropic mixtures as working fluid in JT cycles improve their performance in an order of magnitude. Optimization of JT cycles have earned substantial importance for cryogenics applications (e.g, gas liquefaction, cryosurgery probes, cooling of infrared sensors, cryopreservation, and biomedical samples). Heat exchangers design on those cycles is a critical point; consequently, heat transfer coefficient and pressure drop of two-phase zeotropic mixtures are relevant. In this work, it will be applied a methodology in order to calculate the local convective heat transfer coefficients based on the law of the wall approach for turbulent flows. The flow and heat transfer characteristics of zeotropic mixtures in a heated horizontal tube are investigated numerically. The temperature profile and heat transfer coefficient for zeotropic mixtures of different bulk compositions are analysed. The numerical model has been developed and locally applied in a fully developed, constant temperature wall, and two-phase annular flow in a duct. Numerical results have been obtained using this model taking into account continuity, momentum, and energy equations. Local heat transfer coefficient results are compared with available experimental data published by Barraza et al. (2016), and they have shown good agreement.

Fiscal 1993 investigational report on heat pump heat storage technology; 1993 nendo heat pump chikunetsu gijutsu ni kansuru chosa hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

1994-03-01

This project is for an investigation into the heat pump (HP) use heat storage technology, with the aim of clarifying the present status of HP heat storage technology, the utilization status, and the developmental trend of technology and of contributing to the spread of heat energy effective use using HP heat storage technology and to the promotion of the technical development. Accordingly, the evaluation of the following was made: sensible heat (SH), latent heat (LH), chemical heat storage technology (CH), and heat storage technology (HS). Investigations were made on the sensible heat use heat storage technology of water, brine, stone, soil, etc. in terms of SH; the phase change sensible heat use heat storage technology of ice, hydrate salt, paraffins, etc. in terms of LH; hydration, hydroxide, 2-propanol pyrolysis, adsorption of silica gel, zeolite and water, and heat storage technology using metal hydride, etc. in terms of CH. In terms of HS, the following were studied and evaluated from the study results of the heat storage system in which HP is applied to the sensible heat and latent heat type heat storage technology: contribution to the power load levelling and the reduction of heat source capacity, heat recovery and the use of unused energy, improvement of the system efficiency by combining HP and heat storage technology. 24 refs., 242 figs., 56 tabs.

Dynamic design of gas sorption J-T refrigerator

Science.gov (United States)

Chan, C. K.

1986-01-01

A long-life Joule-Thomson refrigerator which is heat powered, involves no sealing, and has few mechanical parts is desirable for long-term sensor cooling in space. In the gas-sorption J-T refrigerator, cooling is achieved by gas sorption (either adsorption or absorption) processes. Currently, a modular, single-stage refrigerator is being designed and built to be operated at 20 K. The design was analyzed using a dynamic model, which is described here. The model includes the kinetics of the compressors and the heat switches, the heat transfer of the pre-coolers and the heat exchangers, the on/off ratio of the check valves, and the impedance of the J-T valve. The cooling power, the cycle time, and the operating conditions were obtained in terms of the power input, the heat sink temperature, and the J-T impedance.

X-ray calibration facility for plasma diagnostics of the MegaJoule laser

International Nuclear Information System (INIS)

Hubert, S.; Prevot, V.

2013-01-01

The Laser MegaJoule (LMJ) located at CEA-CESTA will be equipped with x-ray plasma diagnostics using different kinds of x-ray components such as filters, mirrors, crystals, detectors and cameras. To guarantee LMJ measurements, detectors such as x-ray cameras need to be regularly calibrated. An x-ray laboratory is devoted to this task and performs absolute x-ray calibrations for similar x-ray cameras running on Laser Integration Line (LIL). This paper presents the x-ray calibration bench with its x-ray tube based High Energy x-ray Source (HEXS) and some calibration results. By mean of an ingenious transposition system under vacuum absolute x-ray calibration of x-ray cameras, like streak and stripline ones, can be carried out. Coupled to a new collimation system with micrometric accuracy on aperture sensitivity quantum efficiency measurements can be achieved with reduced uncertainties. (authors)

Comparison of the Thermal Response of Two Calorimetric Cells Dedicated to Nuclear Heating Measurements during Calibration

International Nuclear Information System (INIS)

Brun, J.; Reynard, C.; De-Vita, C.; Carette, M.; Muraglia, M.; Lyoussi, A.; Fourmentel, D.; Guimbal, P.; Villard, J-F.

2013-06-01

Nuclear heating is a key parameter which contributes to the thermal design and the quality of in-pile experiments performed in Material Testing Reactors (MTRs) for the study of nuclear materials and fuels under irradiation. Nuclear heating is typically measured in MTRs by radiometric calorimeters. However this kind of sensor has to be suited and improved in perspective of the new experimental conditions inside the channels of Jules Horowitz Reactor (JHR). In this paper, we study the responses of two non adiabatic differential calorimeter cells having the same geometric design, but different dimensions. These experimental works are carried out during a preliminary out-of-pile calibration operating procedure of these sensors which consists in simulating the sample heating by Joule effect. The influence of the imposed electrical power and of the forced cooling flow is determined on the sensor calibration curves. A more sensitive sensor leads to a quadratic calibration curve. This behavior difference of the two calorimetric configurations is explained by means of temperature and heat flux measurements performed with a new instrumented jacket. (authors)

Long-term effects of multiple borehole heat exchangers; Langzeiteffekt von Mehrfach-Erdwaermesonden

Energy Technology Data Exchange (ETDEWEB)

Pahud, D. [Scuola universitaria professionale della Svizzera italiana (SUPSI), Dipartimento delle costruzioni e del territorio (DCT), Laboratorio di energia, ecologia ed economia LEEE, Canobbio (Switzerland); Kohl, T.; Meguel, T. [Geoenergie c/o GeoWatt, Zuerich (Switzerland); Brenni, R. [Eidgenoessische Technische Hochschule (ETH), Institut fuer Geophysik, Zuerich (Switzerland)

2002-07-01

This report for the Swiss Federal Office of Energy (SFOE) presents the results of a study made on the mutual influence of borehole heat exchangers (BHE) used for ground-coupled heat pump systems over longer periods of time (tens to hundreds of years) using simulation programmes. A comparison is made between the two programmes SBM (used in 'g-function' mode) and FRACTure (using finite elements) that were used in the first phase of the project to simulate the mutual effects between three BHEs. The authors consider that the programmes, which use completely different algorithms, both provide reliable results when used to simulate BHE systems. The results of the second phase of the project, where the 'g-function' concept was used to calculate the long-term influence of two and three-borehole configurations, are presented in graphical form. Calculations made for varying thermal conductivity, borehole depth and spacing, time periods and heat extraction rates are presented, whereby local groundwater flows are not taken into account.

Methods for characterizing convective cryoprobe heat transfer in ultrasound gel phantoms.

Science.gov (United States)

Etheridge, Michael L; Choi, Jeunghwan; Ramadhyani, Satish; Bischof, John C

2013-02-01

While cryosurgery has proven capable in treating of a variety of conditions, it has met with some resistance among physicians, in part due to shortcomings in the ability to predict treatment outcomes. Here we attempt to address several key issues related to predictive modeling by demonstrating methods for accurately characterizing heat transfer from cryoprobes, report temperature dependent thermal properties for ultrasound gel (a convenient tissue phantom) down to cryogenic temperatures, and demonstrate the ability of convective exchange heat transfer boundary conditions to accurately describe freezing in the case of single and multiple interacting cryoprobe(s). Temperature dependent changes in the specific heat and thermal conductivity for ultrasound gel are reported down to -150 °C for the first time here and these data were used to accurately describe freezing in ultrasound gel in subsequent modeling. Freezing around a single and two interacting cryoprobe(s) was characterized in the ultrasound gel phantom by mapping the temperature in and around the "iceball" with carefully placed thermocouple arrays. These experimental data were fit with finite-element modeling in COMSOL Multiphysics, which was used to investigate the sensitivity and effectiveness of convective boundary conditions in describing heat transfer from the cryoprobes. Heat transfer at the probe tip was described in terms of a convective coefficient and the cryogen temperature. While model accuracy depended strongly on spatial (i.e., along the exchange surface) variation in the convective coefficient, it was much less sensitive to spatial and transient variations in the cryogen temperature parameter. The optimized fit, convective exchange conditions for the single-probe case also provided close agreement with the experimental data for the case of two interacting cryoprobes, suggesting that this basic characterization and modeling approach can be extended to accurately describe more complicated

Characterizing Long-Term Groundwater Conditions and Lithology for the Design of Large-Scale Borehole Heat Exchangers

Science.gov (United States)

Smith, David Charles

Construction of large scale ground coupled heat pump (GCHP) systems that operate with hundreds or even thousands of boreholes for the borehole heat exchangers (BHE) has increased in recent years with many coming on line in the past 10 years. Many large institutions are constructing these systems because of their ability to store energy in the subsurface for indoor cooling during the warm summer months and extract that energy for heating during the cool winter months. Despite the increase in GCHP system systems constructed, there have been few long term studies on how these large systems interact with the subsurface. The thermal response test (TRT) is the industry standard for determining the thermal properties of the rock and soil. The TRT is limited in that it can only be used to determine the effective thermal conductivity over the whole length of a single borehole at the time that it is administered. The TRT cannot account for long-term changes in the aquifer saturation, changes in groundwater flow, or characterize different rock and soil units by effectiveness for heat storage. This study established new methods and also the need for the characterization of the subsurface for the purpose of design and long-term monitoring for GCHP systems. These new methods show that characterizing the long-term changes in aquifer saturation and groundwater flow, and characterizing different rock and soil units are an important part of the design and planning process of these systems. A greater understanding of how large-scale GCHP systems interact with the subsurface will result in designs that perform more efficiently over a longer period of time and expensive modifications due to unforeseen changes in system performance will be reduced.

Long-term variability of heat waves in Argentina and recurrence probability of the severe 2008 heat wave in Buenos Aires

Czech Academy of Sciences Publication Activity Database

Rusticucci, M.; Kyselý, Jan; Almeira, G.; Lhotka, Ondřej

2016-01-01

Roč. 124, č. 3 (2016), s. 679-689 ISSN 0177-798X R&D Projects: GA MŠk 7AMB15AR001 Institutional support: RVO:68378289 Keywords : heat waves * long-term variability * climate extremes Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 2.640, year: 2016 http://link.springer.com/article/10.1007%2Fs00704-015-1445-7

Long-Term Monitoring of Mini-Split Ductless Heat Pumps in the Northeast

Energy Technology Data Exchange (ETDEWEB)

Ueno, K.; Loomis, H.

2015-06-01

Transformations, Inc. has extensive experience building their high performance housing at a variety of Massachusetts locations, in both a production and custom home setting. The majority of their construction uses mini-split heat pumps (MSHPs) for space conditioning. This research covered the long-term performance of MSHPs in Zone 5A; it is the culmination of up to 3 years' worth of monitoring in a set of eight houses. This research examined electricity use of MSHPs, distributions of interior temperatures and humidity when using simplified (two-point) heating systems in high-performance housing, and the impact of open-door/closed-door status on temperature distributions. The use of simplified space conditioning distribution (through use of MSHPs) provides significant first cost savings, which are used to offset the increased investment in the building enclosure.

ESTUDIO EXPERIMENTAL DE UNA DESCARGA PLASMA FOCUS RAPIDA OPERADA EN EL RANGO DE DECENAS DE JOULES EMITIENDO NEUTRONES

OpenAIRE

TARIFEÑO SALDIVIA; ARIEL ESTEBAN; TARIFEÑO SALDIVIA; ARIEL ESTEBAN

2011-01-01

En esta investigación doctoral se estudió experimentalmente una descarga plasma focus operada a decenas de joules y decenas de kiloamperes. El dispositivo genera una descarga coaxial por medio de un arreglo de electrodos los cuales consisten de un electrodo central, un aislante cilíndrico y un electrodo exterior. La descarga es alimentada por un generador capacitivo y se opera a presiones de algunos milibar. Los parámetros eléctricos típicos del dispositivo, denominado PF-50J, son T/4 ...

Influence of the number of cones on speckle patterns in the Laser MegaJoule configuration

International Nuclear Information System (INIS)

Le Cain, A.; Riazuelo, G.; Sajer, J. M.

2013-01-01

This paper investigates statistical properties of hot spots when speckle patterns are generated by the superimposition of multiple laser beams in a 2 cone and a 3 cone Laser MegaJoule configuration in the zone where all the beams overlap. Three different cases of polarizations are investigated: P polarization, S polarization and the case of Double Polarization Smoothing (DPS). It is found that the sizes of the speckles depend on the choice of the polarization and that DPS seems to be the best option in both configurations. It is shown that the longitudinal radius of the hot spots in a 2 cone configuration is bigger than in a 3 cone configuration. (authors)

Volatility and entrainment of feed components and product glass characteristics during pilot-scale vitrification of simulated Hanford site low-level waste

International Nuclear Information System (INIS)

Shade, J.W.

1996-01-01

Commercially available melter technologies were tested for application to vitrification of Hanford site low-level waste (LLW). Testing was conducted at vendor facilities using a non-radioactive LLW simulant. Technologies tested included four Joule-heated melter types, a carbon electrode melter, a cyclone combustion melter, and a plasma torch-fired melter. A variety of samples were collected during the vendor tests and analyzed to provide data to support evaluation of the technologies. This paper describes the evaluation of melter feed component volatility and entrainment losses and product glass samples produced during the vendor tests. All vendors produced glasses that met minimum leach criteria established for the test glass formulations, although in many cases the waste oxide loading was less than intended. Entrainment was much lower in Joule-heated systems than in the combustion or plasma torch-fired systems. Volatility of alkali metals, halogens, B, Mo, and P were severe for non-Joule-heated systems. While losses of sulfur were significant for all systems, the volatility of other components was greatly reduced for some configurations of Joule-heated melters. Data on approaches to reduce NO x generation, resulting from high nitrate and nitrite content in the double-shell slurry feed, are also presented

Preliminary experiments to simulate glass/electrode interactions within a Joule Ceramic Melter

International Nuclear Information System (INIS)

Dalton, J.T.; Paige, E.L.; Sutcliffe, P.W.

1986-01-01

Preliminary isothermal corrosion tests have been made on Inconel 690 coupon samples immersed in Harvest II M9 glass with and without excess additions of Li 2 O (1.5%) and RuO 2 (20%) together with TeO 2 (2%) at 1200 0 C for periods up to 100 hours. Inconel 690 corrosion and the products and ruthenium redox conditions within the glass approximate to those observed in the 1/3rd scale Joule Ceramic Melter operations. Corrosion takes place by an oxidation mechanism to form a chromium-rich surface oxide, and dissolution of this surface oxide by the surrounding glass. Additions of excess Li 2 O increase the corrosion rate of Inconel 690, whereas RuO 2 + TeO 2 are neutral. The latter however have a marked effect in lowering the room temperature resistivity by at least 5 orders of magnitude even though relatively small fraction of the RuO 2 precipitates were reduced to ruthenium metal. (author)

Effect of Ponderomotive Terms on Heat Flux in Laser-Produced Plasmas

Science.gov (United States)

Li, G.

2005-10-01

A laser electromagnetic field introduces ponderomotive termsootnotetextV. N. Goncharov and G. Li, Phys. Plasmas 11, 5680 (2004). in the heat flux in a plasma. To account for the nonlocal effects in the ponderomotive terms, first, the kinetic equation coupled with the Maxwell equations is numerically solved for the isotropic part of the electron distribution function. Such an equation includes self-consistent electromagnetic fields and laser absorption through the inverse bremsstrahlung. Then, the anisotropic part is found by solving a simplified Fokker--Planck equation. Using the distribution function, the electric current and heat flux are obtained and substituted into the hydrocode LILAC to simulate ICF implosions. The simulation results are compared against the existing nonlocal electron conduction modelsootnotetextG. P. Schurtz, P. D. Nicola"i, and M. Busquet, Phys. Plasmas 9, 4238 (2000). and Fokker--Planck simulations. This work was supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC52-92SF19460.

Resistive Heating and Ion Drag in Saturn's Thermosphere

Science.gov (United States)

Vriesema, Jess William; Koskinen, Tommi; Yelle, Roger V.

2017-10-01

One of the most puzzling observations of the jovian planets is that the thermospheres of Jupiter, Saturn, Uranus and Neptune are all several times hotter than solar heating can account for (Strobel and Smith 1973; Yelle and Miller 2004; Muller-Wodarg et al. 2006). On Saturn, resistive heating appears sufficient to explain these temperatures in auroral regions, but the particular mechanism(s) responsible for heating the lower latitudes remains unclear. The most commonly proposed heating mechanisms are breaking gravity waves and auroral heating at the poles followed by redistribution of energy to mid-and low latitudes. Both of these energy sources are potentially important but also come with significant problems. Wave heating would have to be continuous and global to produce consistently elevated temperatures and the strong Coriolis forces coupled with polar ion drag appear to hinder redistribution of auroral energy (see Strobel et al. 2016 for review). Here we explore an alternative: wind-driven electrodynamics that can alter circulation and produce substantial heating outside of the auroral region. Smith (2013) showed this in-situ mechanism to be potentially significant in Jupiter’s thermosphere. We present new results from an axisymmetric, steady-state model that calculates resistive (Joule) heating rates through rigorous solutions of the electrodynamic equations for the coupled neutral atmosphere and ionosphere of Saturn. At present, we assume a dipole magnetic field and neglect any contributions from the magnetosphere. We use ion mixing ratios from the model of Kim et al. (2014) and the observed temperature-pressure profile from Koskinen et al. (2015) to calculate the generalized conductivity tensor as described by Koskinen et al. (2014). We calculate the current density under the assumption that it has no divergence and use it to calculate the resistive heating rates and ion drag. Our results suggest that resistive heating and ion drag at low latitudes likely

A self-heating study on multi-finger AlGaN/GaN high electron mobility transistors

International Nuclear Information System (INIS)

Yang Liyuan; Ai Shan; Chen Yonghe; Cao Mengyi; Zhang Kai; Ma Xiaohua; Hao Yue

2013-01-01

Self-heating in multi-finger AlGaN/GaN high-electron-mobility transistors (HEMTs) is investigated by measurements and modeling of device junction temperature under steady-state operation. Measurements are carried out using micro-Raman scattering to obtain the detailed and accurate temperature distribution of the device. The device peak temperature corresponds to the high field region at the drain side of gate edge. The channel temperature of the device is modeled using a combined electro-thermal model considering 2DEG transport characteristics and the Joule heating power distribution. The results reveal excellent correlation to the micro-Raman measurements, validating our model for the design of better cooled structures. Furthermore, the influence of layout design on the channel temperature of multi-finger AlGaN/GaN HEMTs is studied using the proposed electro-thermal model, allowing for device optimization. (semiconductor devices)

Thermotolerance and Photosystem II Behaviour in Co-occuring Temperate Tree Species Exposed to Short-term Extreme Heat Waves

Science.gov (United States)

Guha, A.; Warren, J.; Cummings, C.; Han, J.

2017-12-01

Thermal stress can induce irreversible photodamage with longer consequences for plant metabolism. We focused on photosystem II (PSII) behaviour to understand how this complex responds in different co-occuring temperate trees exposed to short-term extreme heat waves. The study was designed for understanding complex heat tolerance mechanisms in trees. During manipulative heat-wave experiments, we monitored instantaneous PSII performance and tracked both transient and chronic PSII damages using chlorophyll a fluorescence characteristics. Fluorescence signals were used to simulate PSII bioenergetic processes. The light (Fv'/Fm') and dark-adapted (Fv/Fm) fluorescence traits including fast induction kinetics (OJIP), electron transport rate, PSII operating efficiency and quenching capacities were significantly affected by the heat treatments. Loss in PSII efficiency was more apparent in species like black cottonwood, yellow poplar, walnuts and conifers, whereas oaks maintained relatively better PSII functions. The post-heat recovery of Fv/Fm varied across the studied species showing differential carry over effects. PSII down-regulation was one of dominant factors for the loss in operational photosynthesis during extreme heat wave events. Both light and dark-adapted fluorescence characteristics showed loss in photo-regulatory functions and photodamage. Some resilient species showed rapid recovery from transient PSII damage, whereas fingerprints of chronic PSII damage were observed in susceptibles. Thresholds for Fv/Fm and non-photochemical quenching were identified for the studied species. PSII malfunctioning was largely associated with the observed photosynthetic down-regulation during heat wave treatments, however, its physiological recovery should be a key factor to determine species resilience to short-term extreme heat wave events.

Citrate-capped gold nanoparticle electrophoretic heat production in response to a time-varying radiofrequency electric-field.

Science.gov (United States)

Corr, Stuart J; Raoof, Mustafa; Mackeyev, Yuri; Phounsavath, Sophia; Cheney, Matthew A; Cisneros, Brandon T; Shur, Michael; Gozin, Michael; McNally, Patrick J; Wilson, Lon J; Curley, Steven A

2012-11-15

The evaluation of heat production from gold nanoparticles (AuNPs) irradiated with radiofrequency (RF) energy has been problematic due to Joule heating of their background ionic buffer suspensions. Insights into the physical heating mechanism of nanomaterials under RF excitations must be obtained if they are to have applications in fields such as nanoparticle-targeted hyperthermia for cancer therapy. By developing a purification protocol which allows for highly-stable and concentrated solutions of citrate-capped AuNPs to be suspended in high-resistivity water, we show herein, for the first time, that heat production is only evident for AuNPs of diameters ≤ 10 nm, indicating a unique size-dependent heating behavior not previously observed. Heat production has also shown to be linearly dependent on both AuNP concentration and total surface area, and severely attenuated upon AuNP aggregation. These relationships have been further validated using permittivity analysis across a frequency range of 10 MHz to 3 GHz, as well as static conductivity measurements. Theoretical evaluations suggest that the heating mechanism can be modeled by the electrophoretic oscillation of charged AuNPs across finite length scales in response to a time-varying electric field. It is anticipated these results will assist future development of nanoparticle-assisted heat production by RF fields for applications such as targeted cancer hyperthermia.

Effects of heat input on mechanical properties of metal inert gas welded 1.6 mm thick galvanized steel sheet

International Nuclear Information System (INIS)

Rafiqul, M I; Ishak, M; Rahman, M M

2012-01-01

It is usually a lot easier and less expensive to galvanize steel before it is welded into useful products. Galvanizing afterwards is almost impossible. In this research work, Galvanized Steel was welded by using the ER 308L stainless steel filler material. This work was done to find out an alternative way of welding and investigate the effects of heat input on the mechanical properties of butt welded joints of Galvanized Steel. A 13.7 kW maximum capacity MIG welding machine was used to join 1.6 mm thick sheet of galvanized steel with V groove and no gap between mm. Heat inputs was gradually increased from 21.06 to 25.07 joules/mm in this study. The result shows almost macro defects free welding and with increasing heat input the ultimate tensile strength and welding efficiency decrease. The Vickers hardness also decreases at HAZ with increasing heat input and for each individual specimen; hardness was lowest in heat affected zone (HAZ), intermediate in base metal and maximum in welded zone. The fracture for all specimens was in the heat affected zone while testing in the universal testing machine.

Effects of heat input on mechanical properties of metal inert gas welded 1.6 mm thick galvanized steel sheet

Science.gov (United States)

Rafiqul, M. I.; Ishak, M.; Rahman, M. M.

2012-09-01

It is usually a lot easier and less expensive to galvanize steel before it is welded into useful products. Galvanizing afterwards is almost impossible. In this research work, Galvanized Steel was welded by using the ER 308L stainless steel filler material. This work was done to find out an alternative way of welding and investigate the effects of heat input on the mechanical properties of butt welded joints of Galvanized Steel. A 13.7 kW maximum capacity MIG welding machine was used to join 1.6 mm thick sheet of galvanized steel with V groove and no gap between mm. Heat inputs was gradually increased from 21.06 to 25.07 joules/mm in this study. The result shows almost macro defects free welding and with increasing heat input the ultimate tensile strength and welding efficiency decrease. The Vickers hardness also decreases at HAZ with increasing heat input and for each individual specimen; hardness was lowest in heat affected zone (HAZ), intermediate in base metal and maximum in welded zone. The fracture for all specimens was in the heat affected zone while testing in the universal testing machine.

Sorption heat storage for long-term low-temperature applications: A review on the advancements at material and prototype scale

NARCIS (Netherlands)

Scapino, L.; Zondag, H.A.; Van Bael, J.; Diriken, J.; Rindt, C.C.M.

2017-01-01

Sorption heat storage has the potential to store large amounts of thermal energy from renewables and other distributed energy sources. This article provides an overview on the recent advancements on long-term sorption heat storage at material- and prototype- scales. The focus is on applications

Interaction Between Short-Term Heat Pretreatment and Avermectin On 2nd Instar Larvae of Diamondback Moth, Plutella Xylostella (Linn)

Science.gov (United States)

Gu, Xiaojun; Tian, Sufen; Wang, Dehui; Gao, Fei

2009-01-01

Based on the cooperative virulence index (c.f.), the interaction effect between short-term heat pretreatment and avermectin on 2nd instar larvae of diamondback moth (DBM), Plutella xylostella (Linnaeus), was assessed. The results suggested that the interaction results between short-term heat pretreatment and avermectin on the tested insects varied with temperature level as well as its duration and avermectin concentration. Interaction between heat pretreatment at 30°C and avermectin mainly resulted in addition. Meanwhile, pretreatment at 35°C for 2 or 4 h could antagonize the toxicity of avermectin at lower concentrations, which indicated a hormetic effect occurred. The results indicate that cooperative virulence index (c.f.) may be adopted in hormetic effect assessment. PMID:19809544

Identification of coronal heating events in 3D simulations

Science.gov (United States)

Kanella, Charalambos; Gudiksen, Boris V.

2017-07-01

Context. The solar coronal heating problem has been an open question in the science community since 1939. One of the proposed models for the transport and release of mechanical energy generated in the sub-photospheric layers and photosphere is the magnetic reconnection model that incorporates Ohmic heating, which releases a part of the energy stored in the magnetic field. In this model many unresolved flaring events occur in the solar corona, releasing enough energy to heat the corona. Aims: The problem with the verification and quantification of this model is that we cannot resolve small scale events due to limitations of the current observational instrumentation. Flaring events have scaling behavior extending from large X-class flares down to the so far unobserved nanoflares. Histograms of observable characteristics of flares show powerlaw behavior for energy release rate, size, and total energy. Depending on the powerlaw index of the energy release, nanoflares might be an important candidate for coronal heating; we seek to find that index. Methods: In this paper we employ a numerical three-dimensional (3D)-magnetohydrodynamic (MHD) simulation produced by the numerical code Bifrost, which enables us to look into smaller structures, and a new technique to identify the 3D heating events at a specific instant. The quantity we explore is the Joule heating, a term calculated directly by the code, which is explicitly correlated with the magnetic reconnection because it depends on the curl of the magnetic field. Results: We are able to identify 4136 events in a volume 24 × 24 × 9.5 Mm3 (I.e., 768 × 786 × 331 grid cells) of a specific snapshot. We find a powerlaw slope of the released energy per second equal to αP = 1.5 ± 0.02, and two powerlaw slopes of the identified volume equal to αV = 1.53 ± 0.03 and αV = 2.53 ± 0.22. The identified energy events do not represent all the released energy, but of the identified events, the total energy of the largest events

Plasma skin regeneration technology.

Science.gov (United States)

Bogle, M A

2006-09-01

Plasma skin regeneration (PSR) technology uses energy delivered from plasma rather than light or radiofrequency. Plasma is the fourth state of matter in which electrons are stripped from atoms to form an ionized gas. The plasma is emitted in a millisecond pulse to deliver energy to target tissue upon contact without reliance on skin chromophores. The technology can be used at varying energies for different depths of effect, from superficial epidermal sloughing to deeper dermal heating. With the Portrait PSR device (Rhytec, Inc.) there are three treatment guidelines termed PSR1, PSR2, and PSR3. The PSR1 protocol uses a series of low-energy treatments (1.0,1.2 Joules) spaced 3 weeks apart. The PSR2 protocol uses one high-energy pass (3.0, 4.0 Joules) performed in a single treatment, and the PSR3 protocol uses two high-energy passes (3.0 4.0 Joules) performed in a single treatment. All protocols improve fine lines, textural irregularities, and dyspigmentation; however, skin tightening is probably more pronounced with the high-energy treatments.

Physiological and molecular evidence of differential short-term heat tolerance in Mediterranean seagrasses.

Science.gov (United States)

Marín-Guirao, Lazaro; Ruiz, Juan M; Dattolo, Emanuela; Garcia-Munoz, Rocio; Procaccini, Gabriele

2016-06-27

The increase in extreme heat events associated to global warming threatens seagrass ecosystems, likely by affecting key plant physiological processes such as photosynthesis and respiration. Understanding species' ability to acclimate to warming is crucial to better predict their future trends. Here, we study tolerance to warming in two key Mediterranean seagrasses, Posidonia oceanica and Cymodocea nodosa. Stress responses of shallow and deep plants were followed during and after short-term heat exposure in mesocosms by coupling photo-physiological measures with analysis of expression of photosynthesis and stress-related genes. Contrasting tolerance and capacity to heat acclimation were shown by shallow and deep P. oceanica ecotypes. While shallow plants acclimated through respiratory homeostasis and activation of photo-protective mechanisms, deep ones experienced photosynthetic injury and impaired carbon balance. This suggests that P. oceanica ecotypes are thermally adapted to local conditions and that Mediterranean warming will likely diversely affect deep and shallow meadow stands. On the other hand, contrasting mechanisms of heat-acclimation were adopted by the two species. P. oceanica regulates photosynthesis and respiration at the level of control plants while C. nodosa balances both processes at enhanced rates. These acclimation discrepancies are discussed in relation to inherent attributes of the two species.

Physiological and molecular evidence of differential short-term heat tolerance in Mediterranean seagrasses

Science.gov (United States)

Marín-Guirao, Lazaro; Ruiz, Juan M.; Dattolo, Emanuela; Garcia-Munoz, Rocio; Procaccini, Gabriele

2016-06-01

The increase in extreme heat events associated to global warming threatens seagrass ecosystems, likely by affecting key plant physiological processes such as photosynthesis and respiration. Understanding species’ ability to acclimate to warming is crucial to better predict their future trends. Here, we study tolerance to warming in two key Mediterranean seagrasses, Posidonia oceanica and Cymodocea nodosa. Stress responses of shallow and deep plants were followed during and after short-term heat exposure in mesocosms by coupling photo-physiological measures with analysis of expression of photosynthesis and stress-related genes. Contrasting tolerance and capacity to heat acclimation were shown by shallow and deep P. oceanica ecotypes. While shallow plants acclimated through respiratory homeostasis and activation of photo-protective mechanisms, deep ones experienced photosynthetic injury and impaired carbon balance. This suggests that P. oceanica ecotypes are thermally adapted to local conditions and that Mediterranean warming will likely diversely affect deep and shallow meadow stands. On the other hand, contrasting mechanisms of heat-acclimation were adopted by the two species. P. oceanica regulates photosynthesis and respiration at the level of control plants while C. nodosa balances both processes at enhanced rates. These acclimation discrepancies are discussed in relation to inherent attributes of the two species.

Polarity-Free Resistive Switching Characteristics of CuxO Films for Non-volatile Memory Applications

International Nuclear Information System (INIS)

Hang-Bing, Lv; Peng, Zhou; Xiu-Feng, Fu; Ming, Yin; Ya-Li, Song; Li, Tang; Ting-Ao, Tang; Yin-Yin, Lin

2008-01-01

Resistive switching characteristics of Cu x O films grown by plasma oxidation process at room temperature are investigated. Both bipolar and unipolar stable resistive switching behaviours are observed and confirmed by repeated current–voltage measurements. It is found that the RESET current is dependent on SET compliance current. The mechanism behind this new phenomenon can be understood in terms of conductive filaments formation/rupture with the contribution of Joule heating

Numerical and experimental investigation of melting with internal heat generation within cylindrical enclosures

Energy Technology Data Exchange (ETDEWEB)

Amber Shrivastava; Brian Williams; Ali S. Siahpush; Bruce Savage; John Crepeau

2014-06-01

There have been significant efforts by the heat transfer community to investigate the melting phenomenon of materials. These efforts have included the analytical development of equations to represent melting, numerical development of computer codes to assist in modeling the phenomena, and collection of experimental data. The understanding of the melting phenomenon has application in several areas of interest, for example, the melting of a Phase Change Material (PCM) used as a thermal storage medium as well as the melting of the fuel bundle in a nuclear power plant during an accident scenario. The objective of this research is two-fold. First a numerical investigation, using computational fluid dynamics (CFD), of melting with internal heat generation for a vertical cylindrical geometry is presented. Second, to the best of authors knowledge, there are very limited number of engineering experimental results available for the case of melting with Internal Heat Generation (IHG). An experiment was performed to produce such data using resistive, or Joule, heating as the IHG mechanism. The numerical results are compared against the experimental results and showed favorable correlation. Uncertainties in the numerical and experimental analysis are discussed. Based on the numerical and experimental analysis, recommendations are made for future work.

Changing the energy climate: clean and green heat from grass biofuel pellets

International Nuclear Information System (INIS)

Jannasch, R.; Samson, R.; DeMaio, A.; Adams, T.; Ho Lem, C.

2001-01-01

Uncertain energy supplies and international agreements to reduce greenhouse gas (GHG) emissions have created unique opportunities for biofuel development. Pelleted fuels from warm season grasses such as switchgrass (Panicum virgatum) can be grown for $3-4/GigaJoule (GJ) with only minor emissions of CO 2 . Using close-coupled gasifer combustion technology, switchgrass fuel pellets emit 86%, 91%, 71% and 89% less CO 2 than electricity, heating oil, natural gas and propane, respectively. Every 100 ha of switchgrass converted into pellet form and used to displace fossil fuel for space-heating prevents the emission of 1000 tonnes of CO 2 . Heating an average Ontario house with a 90GJ heat demand costs $1213 with switchgrass pellets compared to $2234, $1664, $882 and $3251 with electricity, heating oil, natural gas and propane, respectively. An estimated 23.4 million acres of agricultural land in Canada could potentially be converted to perennial grass biofuel production. The depressed farm sector would benefit economically from energy farming. Low-grade heat energy derived from grass pellets could displace some of the 30,000 GigaWatt Hours of electricity currently used for home heating in Quebec, Ontario and Manitoba. Surplus electricity could be exported or used to replace nuclear or coal burning plants. Contrary to prevailing beliefs that reducing GHG emissions will raise societal energy costs, pelletized grass biofuels could provide consumers with less expensive and more GHG-friendly heating options than most fossil energy sources. If the political support and direction exist to implement the Kyoto Protocol as intended, grass pellets could well become a heating fuel of choice in North America. (author)

Experimental similitude determination of the influence of perturbations in the thickness of a heating channel on the isolated wall temperatures (1960); Determination experimentale en similitude de l'influence de perturbations dans l'epaisseur d'un canal chauffant sur les temperatures de la paroi isolee (1960)

Energy Technology Data Exchange (ETDEWEB)

Vernier, Ph [Commissariat a l' Energie Atomique, Grenoble (France).Centre d' Etudes Nucleaires; Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

1960-07-01

A study is made of the local heating phenomena produced on the isolated wall of a channel heated by the Joule effect by a sudden fluctuation in the conducting thickness. By the use of an experimental scale model it has been possible to measure the differences in the isolated wall temperature along the abscissa of the perturbation. The tests carried out show that the temperature differences are contained within a range of {+-} 4 per cent with respect to the temperature differences between the isolated and the isolated walls. (author) [French] On analyse le phenomene thermique local cree sur la paroi isolee d'un canal chauffe par effet Joule, par une perturbation brusque de l'epaisseur conductrice. Un modele experimental a l'echelle a permis de mesurer les ecarts de temperature de la paroi isolee a l'abscisse de la perturbation. Les essais realises ont montre que les ecarts de temperature se situaient dans une bande de {+-} 4 pour cent par rapport a l'ecart de temperature moyen entre paroi isolee et paroi refroidie. (auteur)

Experimental study on transient boiling heat transfer

International Nuclear Information System (INIS)

Visentini, R.

2012-01-01

Boiling phenomena can be found in the everyday life, thus a lot of studies are devoted to them, especially in steady state conditions. Transient boiling is less known but still interesting as it is involved in the nuclear safety prevention. In this context, the present work was supported by the French Institute of Nuclear Safety (IRSN). In fact, the IRSN wanted to clarify what happens during a Reactivity-initiated Accident (RIA). This accident occurs when the bars that control the nuclear reactions break down and a high power peak is passed from the nuclear fuel bar to the surrounding fluid. The temperature of the nuclear fuel bar wall increases and the fluid vaporises instantaneously. Previous studies on a fuel bar or on a metal tube heated by Joule effect were done in the past in order to understand the rapid boiling phenomena during a RIA. However, the measurements were not really accurate because the measurement techniques were not able to follow rapid phenomena. The main goal of this work was to create an experimental facility able to simulate the RIA boiling conditions but at small scale in order to better understand the boiling characteristics when the heated-wall temperature increases rapidly. Moreover, the experimental set-up was meant to be able to produce less-rapid transients as well, in order to give information on transient boiling in general. The facility was built at the Fluid-Mechanics Institute of Toulouse. The core consists of a metal half-cylinder heated by Joule effect, placed in a half-annulus section. The inner half cylinder is made of a 50 microns thick stainless steel foil. Its diameter is 8 mm, and its length 200 mm. The outer part is a 34 mm internal diameter glass half cylinder. The semi-annular section is filled with a coolant, named HFE7000. The configuration allows to work in similarity conditions. The heated part can be place inside a loop in order to study the flow effect. The fluid temperature influence is taken into account as

A form of MHD universal equations of unsteady incompressible fluid flow with variable elctroconductivity on heated moving plate

Directory of Open Access Journals (Sweden)

Boričić Zoran

2005-01-01

Full Text Available This paper deals with laminar, unsteady flow of viscous, incompressible and electro conductive fluid caused by variable motion of flat plate. Fluid electro conductivity is variable. Velocity of the plate is time function. Plate moves in its own plane and in "still" fluid. Present external magnetic filed is perpendicular to the plate. Plate temperature is a function of longitudinal coordinate and time. Viscous dissipation, Joule heat, Hole and polarization effects are neglected. For obtaining of universal equations system general similarity method is used as well as impulse and energy equation of described problem.

Advances towards a portable pulsed source of neutrons and X-ray with energy of work close to 1 Joule

International Nuclear Information System (INIS)

Soto, Leopoldo; Pavez, C.; Moreno, Jose; Clausse, Alejandro; Barbaglia, Mario O.

2005-01-01

Plasma Focus devices are pulsed sources of X and neutron radiation from intense electrical discharges in deuterium. Classically these devices operate at energies between a few KJ to 1 MJ. In this work we present the design and feasibility studies of a Plasma Focus operating at energies close to 1 Joule. Experimental evidence of focalization is presented, and the optimum parameter relations at such low energies are discussed. The results indicate the device will be able to emit pulses about 1000 neutrons per J. (author) [es

Heat networks in France in 2014. Heat networks: which price for the consumer?

International Nuclear Information System (INIS)

Reynaud, Didier; Gong, Zheng; Moreau, Sylvain; Bottin, Anne; Reperant, Patricia

2016-04-01

A first document publishes and comments various statistics regarding heat networks in France in 2014: distribution in terms of quantity of supplied heat, main urban units, distribution in terms of urban unit size and in terms of community type (land, isolated town, outskirts, centre town). It also indicates the types, percentages and evolution of energies consumed in these heat networks, the shares of fossil and renewable energies, and the distribution of networks in terms of energy type. Some regional data are briefly commented (energy shares in each region, number of primary housing connected to an urban heating network). This publication also indicates methodological aspects and the definitions of the main components and characteristics of a heat network. Notably based on some of these data, the second document comments the price of heat supplied in these heat networks in 2014 as these prices are not regulated and depend on agreements between clients and providers. These prices are analysed in terms of linear thermal density, of heat quantity supplied by delivery point, of sector (industry, housing, office building), of rate of renewable energy, and of operator status (public service delegation or private ownership)

ALPHA - The long-term passive decay heat removal and aerosol retention program

International Nuclear Information System (INIS)

Guentay, S.; Varadi, G.; Dreier, J.

1996-01-01

The Paul Scherrer Institute initiated the major new experimental and analytical program ALPHA in 1990. The program is aimed at understanding the long-term decay heat removal and aerosol questions for the next generation of Passive Light Water Reactors. The ALPHA project currently includes four major items: the large-scale, integral system behaviour test facility PANDA, which will be used to examine multidimensional effects of the SBWR decay heat removal system; an investigation of the thermal hydraulics of natural convection and mixing in pools and large volumes (LINX); a separate-effects study of aerosols transport and deposition in plenum and tubes (AIDA); while finally, data from the PANDA facility and supporting separate effects tests will be used to develop and qualify models and provide validation of relevant system codes. The paper briefly reviews the above four topics and current status of the experimental facilities. (author). 3 refs, 12 figs

ALPHA - The long-term passive decay heat removal and aerosol retention program

Energy Technology Data Exchange (ETDEWEB)

Guentay, S; Varadi, G; Dreier, J [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

1996-12-01

The Paul Scherrer Institute initiated the major new experimental and analytical program ALPHA in 1990. The program is aimed at understanding the long-term decay heat removal and aerosol questions for the next generation of Passive Light Water Reactors. The ALPHA project currently includes four major items: the large-scale, integral system behaviour test facility PANDA, which will be used to examine multidimensional effects of the SBWR decay heat removal system; an investigation of the thermal hydraulics of natural convection and mixing in pools and large volumes (LINX); a separate-effects study of aerosols transport and deposition in plenum and tubes (AIDA); while finally, data from the PANDA facility and supporting separate effects tests will be used to develop and qualify models and provide validation of relevant system codes. The paper briefly reviews the above four topics and current status of the experimental facilities. (author). 3 refs, 12 figs.

Specific heat, polarization and heat conduction in microwave heating systems: A nonequilibrium thermodynamic point of view

International Nuclear Information System (INIS)

Bergese, Paolo

2006-01-01

A microwave (MW) field can induce in a dielectric material an oscillatory polarization. By this mechanism part of the energy carried by the waves is converted into chaotic agitation, and the material heats up. MW heating is a nonequilibrium phenomenon, while conventional heating can generally be considered as quasi-static. Excess (or nonthermal) effects of MWs with respect to conventional heating lie in this difference. Macroscopically, MW heating can be described in the framework of linear nonequilibrium thermodynamics (NET). This approach indicates that in a dielectric material under MW heating the specific heat has a dynamic component linked to the variation of polarization with temperature, and that polarization and heat conduction are intertwined. In particular, linear NET provides a new phenomenological equation for heat conduction that is composed of the classic Fourier's law and an additional term due to polarization relaxation. This term quantitatively describes the excess effect of MWs on thermal conduction

MHD rotating flow and heat transfer through a channel with Hall effects

International Nuclear Information System (INIS)

Ghosh, Sushil Kumar

2016-01-01

The present investigation is the flow and heat transfer of a viscous fluid through a rotating channel about the vertical axis under the influence of transverse magnetic field. The linear temperature dependent density has been introduced along with the induced magnetic field in horizontal directions. To study the temperature distribution, the energy equation consisting of viscous dissipation and joule heating term is solved analytically. The velocity distribution in axial and vertical directions is found to be interesting such as the magnetic Reynolds number and the parameter appears due to buoyancy forces have a substantial contribution to influence the flow pattern. Also the results obtained in the study for magnetic induction variables as well as temperature distribution put forward some significant insight in the fluid flow and heat transfer. The important observation of the present study is that the temperature distribution takes the higher values in the vicinity of the upper wall and this happens due to the fact of buoyancy force and channel rotation. This is a key parameter to worm up or cool down the fluid in a useful purposes. - Highlights: • The important observation of the present study is that the temperature distribution takes the higher values in the vicinity of the upper wall and this happens due to the fact of buoyancy force and channel rotation. • Buoyancy is a key parameter to worm up or cool down the fluid in useful purposes. • It may be predicted that the effect of buoyancy force and magnetic induction force suppress the flow at the lower wall and the effect of the forces lost its potential at the layers near to the upper walls. • It may suggest that the bouncy effect has more prominent role in the fluid flow phenomena as well as heat transfer than magnetic induction and Lorentz force. • The rotation enhances the advantage of circulation of fluid in up and down and tries to make the heat balance within the layers. Our result is true

Ignition and burn propagation with suprathermal electron auxiliary heating

International Nuclear Information System (INIS)

Han Shensheng; Wu Yanqing

2000-01-01

The rapid development in ultrahigh-intensity lasers has allowed the exploration of applying an auxiliary heating technique in inertial confinement fusion (ICF) research. It is hoped that, compared with the 'standard fast ignition' scheme, raising the temperature of a hot-spot over the ignition threshold based on the shock-heated temperature will greatly reduce the required output energy of an ignition ultrahigh-intensity pulse. One of the key issues in ICF auxiliary heating is: how can we transport the exogenous energy efficiently into the hot-spot of compressed DT fuel? A scheme is proposed with three phases. First, a partial-spherical-shell capsule, such as double-conical target, is imploded as in the conventional approach to inertial fusion to assemble a high-density fuel configuration with a hot-spot of temperature lower than the ignition threshold. Second, a hole is bored through the shell outside the hot-spot by suprathermal electron explosion boring. Finally, the fuel is ignited by suprathermal electrons produced in the high-intensity ignition laser-plasma interactions. Calculations with a simple hybrid model show that the new scheme can possibly lead to ignition and burn propagation with a total drive energy of a few tens of kilojoules and an output energy as low as hundreds of joules for a single ignition ultrahigh-intensity pulse. (author)

Online short-term forecast of greenhouse heat load using a weather forecast service

DEFF Research Database (Denmark)

Vogler-Finck, P. J.C.; Bacher, P.; Madsen, Henrik

2017-01-01

the performance of recursive least squares for predicting the heat load of individual greenhouses in an online manner. Predictor inputs (weekly curves terms and weather forecast inputs) are selected in an automated manner using a forward selection approach. Historical load measurements from 5 Danish greenhouses...... mean square error of the prediction was within 8–20% of the peak load for the set of consumers over the 8 months period considered....

Heat pumps in district heating networks

DEFF Research Database (Denmark)

Ommen, Torben Schmidt; Markussen, Wiebke Brix; Elmegaard, Brian

constraints limit the power plants. Efficient heat pumps can be used to decouple the constraints of electricity and heat production, while maintaining the high energy efficiency needed to match the politically agreed carbon emission goals. The requirements in terms of COP, location, capacity and economy...... and strategic planning in the energy sector. The paper presents a case study of optimal implementation of heat pumps in the present energy system of the Copenhagen area. By introduction of the correct capacity of heat pumps, a 1,6 % reduction in fuel consumption for electricity and heat production can...

Impact of environmental contamination on laser induced damage of silica optics in Laser MegaJoule; Impact de l'environnement sur l'endommagement laser des optiques de silice du Laser MegaJoule

Energy Technology Data Exchange (ETDEWEB)

Bien-Aime, K.

2009-11-15

Laser induced damage impact of molecular contamination on fused polished silica samples in a context of high power laser fusion facility, such as Laser MegaJoule (LMJ) has been studied. One of the possible causes of laser induced degradation of optical component is the adsorption of molecular or particular contamination on optical surfaces. In the peculiar case of LMJ, laser irradiation conditions are a fluence of 10 J/cm{sup 2}, a wavelength of 351 nm, a pulse duration of 3 ns for a single shot/days frequency. Critical compounds have been identified thanks to environmental measurements, analysis of material outgassing, and identification of surface contamination in the critical environments. Experiments of controlled contamination involving these compounds have been conducted in order to understand and model mechanisms of laser damage. Various hypotheses are proposed to explain the damage mechanism. (author)

Changes in antioxidants are critical in determining cell responses to short- and long-term heat stress.

Science.gov (United States)

Sgobba, Alessandra; Paradiso, Annalisa; Dipierro, Silvio; De Gara, Laura; de Pinto, Maria Concetta

2015-01-01

Heat stress can have deleterious effects on plant growth by impairing several physiological processes. Plants have several defense mechanisms that enable them to cope with high temperatures. The synthesis and accumulation of heat shock proteins (HSPs), as well as the maintenance of an opportune redox balance play key roles in conferring thermotolerance to plants. In this study changes in redox parameters, the activity and/or expression of reactive oxygen species (ROS) scavenging enzymes and the expression of two HSPs were studied in tobacco Bright Yellow-2 (TBY-2) cells subjected to moderate short-term heat stress (SHS) and long-term heat stress (LHS). The results indicate that TBY-2 cells subjected to SHS suddenly and transiently enhance antioxidant systems, thus maintaining redox homeostasis and avoiding oxidative damage. The simultaneous increase in HSPs overcomes the SHS and maintains the metabolic functionality of cells. In contrast the exposure of cells to LHS significantly reduces cell growth and increases cell death. In the first phase of LHS, cells enhance antioxidant systems to prevent the formation of an oxidizing environment. Under prolonged heat stress, the antioxidant systems, and particularly the enzymatic ones, are inactivated. As a consequence, an increase in H2 O2 , lipid peroxidation and protein oxidation occurs. This establishment of oxidative stress could be responsible for the increased cell death. The rescue of cell growth and cell viability, observed when TBY-2 cells were pretreated with galactone-γ-lactone, the last precursor of ascorbate, and glutathione before exposure to LHS, highlights the crucial role of antioxidants in the acquisition of basal thermotolerance. © 2014 Scandinavian Plant Physiology Society.

Analysis of self-heating of thermally assisted spin-transfer torque magnetic random access memory

Directory of Open Access Journals (Sweden)

Austin Deschenes

2016-11-01

Full Text Available Thermal assistance has been shown to significantly reduce the required operation power for spin torque transfer magnetic random access memory (STT-MRAM. Proposed heating methods include modified material stack compositions that result in increased self-heating or external heat sources. In this work we analyze the self-heating process of a standard perpendicular magnetic anisotropy STT-MRAM device through numerical simulations in order to understand the relative contributions of Joule, thermoelectric Peltier and Thomson, and tunneling junction heating. A 2D rotationally symmetric numerical model is used to solve the coupled electro-thermal equations including thermoelectric effects and heat absorbed or released at the tunneling junction. We compare self-heating for different common passivation materials, positive and negative electrical current polarity, and different device thermal anchoring and boundaries resistance configurations. The variations considered are found to result in significant differences in maximum temperatures reached. Average increases of 3 K, 10 K, and 100 K for different passivation materials, positive and negative polarity, and different thermal anchoring configurations, respectively, are observed. The highest temperatures, up to 424 K, are obtained for silicon dioxide as the passivation material, positive polarity, and low thermal anchoring with thermal boundary resistance configurations. Interestingly it is also found that due to the tunneling heat, Peltier effect, device geometry, and numerous interfacial layers around the magnetic tunnel junction (MTJ, most of the heat is dissipated on the lower potential side of the magnetic junction. This asymmetry in heating, which has also been observed experimentally, is important as thermally assisted switching requires heating of the free layer specifically and this will be significantly different for the two polarity operations, set and reset.

Thermal electron heating rate: a derivation

International Nuclear Information System (INIS)

Hoegy, W.R.

1983-11-01

The thermal electron heating rate is an important heat source term in the ionospheric electron energy balance equation, representing heating by photoelectrons or by precipitating higher energy electrons. A formula for the thermal electron heating rate is derived from the kinetic equation using the electron-electron collision operator as given by the unified theory of Kihara and Aono. This collision operator includes collective interactions to produce a finite collision operator with an exact Coulomb logarithm term. The derived heating rate O(e) is the sum of three terms, O(e) O(p) + S + O(int), which are respectively: (1) primary electron production term giving the heating from newly created electrons that have not yet suffered collisions with the ambient electrons, (2) a heating term evaluated on the energy surface m(e)/2 E(T) at the transition between Maxwellian and tail electrons at E(T), and (3) the integral term representing heating of Maxwellian electrons by energetic tail electrons at energies ET. Published ionospheric electron temperature studies used only the integral term O(int) with differing lower integration limits. Use of the incomplete heating rate could lead to erroneous conclusions regarding electron heat balance, since O(e) is greater than O(int) by as much as a factor of two

Temperature control at DBS electrodes using a heat sink: experimentally validated FEM model of DBS lead architecture

Science.gov (United States)

Elwassif, Maged M.; Datta, Abhishek; Rahman, Asif; Bikson, Marom

2012-08-01

There is a growing interest in the use of deep brain stimulation (DBS) for the treatment of medically refractory movement disorders and other neurological and psychiatric conditions. The extent of temperature increases around DBS electrodes during normal operation (joule heating and increased metabolic activity) or coupling with an external source (e.g. magnetic resonance imaging) remains poorly understood and methods to mitigate temperature increases are being actively investigated. We developed a heat transfer finite element method (FEM) simulation of DBS incorporating the realistic architecture of Medtronic 3389 leads. The temperature changes were analyzed considering different electrode configurations, stimulation protocols and tissue properties. The heat-transfer model results were then validated using micro-thermocouple measurements during DBS lead stimulation in a saline bath. FEM results indicate that lead design (materials and geometry) may have a central role in controlling temperature rise by conducting heat. We show how modifying lead design can effectively control temperature increases. The robustness of this heat-sink approach over complimentary heat-mitigation technologies follows from several features: (1) it is insensitive to the mechanisms of heating (e.g. nature of magnetic coupling); (2) it does not interfere with device efficacy; and (3) can be practically implemented in a broad range of implanted devices without modifying the normal device operations or the implant procedure.

Triggering and guiding high-voltage large-scale leader discharges with sub-joule ultrashort laser pulses

International Nuclear Information System (INIS)

Pepin, H.; Comtois, D.; Vidal, F.; Chien, C.Y.; Desparois, A.; Johnston, T.W.; Kieffer, J.C.; La Fontaine, B.; Martin, F.; Rizk, F.A.M.; Potvin, C.; Couture, P.; Mercure, H.P.; Bondiou-Clergerie, A.; Lalande, P.; Gallimberti, I.

2001-01-01

The triggering and guiding of leader discharges using a plasma channel created by a sub-joule ultrashort laser pulse have been studied in a megavolt large-scale electrode configuration (3-7 m rod-plane air gap). By focusing the laser close to the positive rod electrode it has been possible, with a 400 mJ pulse, to trigger and guide leaders over distances of 3 m, to lower the leader inception voltage by 50%, and to increase the leader velocity by a factor of 10. The dynamics of the breakdown discharges with and without the laser pulse have been analyzed by means of a streak camera and of electric field and current probes. Numerical simulations have successfully reproduced many of the experimental results obtained with and without the presence of the laser plasma channel

Residential proximity to major roads and term low birth weight: the roles of air pollution, heat, noise, and road-adjacent trees.

Science.gov (United States)

Dadvand, Payam; Ostro, Bart; Figueras, Francesc; Foraster, Maria; Basagaña, Xavier; Valentín, Antònia; Martinez, David; Beelen, Rob; Cirach, Marta; Hoek, Gerard; Jerrett, Michael; Brunekreef, Bert; Nieuwenhuijsen, Mark J

2014-07-01

Maternal residential proximity to roads has been associated with adverse pregnancy outcomes. However, there is no study investigating mediators or buffering effects of road-adjacent trees on this association. We investigated the association between mothers' residential proximity to major roads and term low birth weight (LBW), while exploring possible mediating roles of air pollution (PM(2.5), PM(2.5-10), PM(10), PM(2.5) absorbance, nitrogen dioxide, and nitrogen oxides), heat, and noise and buffering effect of road-adjacent trees on this association. This cohort study was based on 6438 singleton term births in Barcelona, Spain (2001-2005). Road proximity was measured as both continuous distance to and living within 200 m from a major road. We assessed individual exposures to air pollution, noise, and heat using, respectively, temporally adjusted land-use regression models, annual averages of 24-hour noise levels across 50 m and 250 m, and average of satellite-derived land-surface temperature in a 50-m buffer around each residential address. We used vegetation continuous fields to abstract tree coverage in a 200-m buffer around major roads. Living within 200 m of major roads was associated with a 46% increase in term LBW risk; an interquartile range increase in heat exposure with an 18% increase; and third-trimester exposure to PM(2.5), PM(2.5-10), and PM10 with 24%, 25%, and 26% increases, respectively. Air pollution and heat exposures together explained about one-third of the association between residential proximity to major roads and term LBW. Our observations on the buffering of this association by road-adjacent trees were not consistent between our 2 measures of proximity to major roads. An increased risk of term LBW associated with proximity to major roads was partly mediated by air pollution and heat exposures.

Long-Term Heating to Improve Receiver Performance

Energy Technology Data Exchange (ETDEWEB)

Glatzmaier, Greg C.; Cable, Robert; Newmarker, Marc

2017-06-27

The buildup of hydrogen in the heat transfer fluid (HTF) that circulates through components of parabolic trough power plants decreases receiver thermal efficiency, and ultimately, it decreases plant performance and electricity output. The generation and occurrence of hydrogen in the HTF provides the driving force for hydrogen to permeate from the HTF through the absorber tube wall and into the receiver annulus. Getters adsorb hydrogen from the annulus volume until they saturate and are no longer able to maintain low hydrogen pressure. The increase in hydrogen pressure within the annulus significantly degrades thermal performance of the receiver and decreases overall power-plant efficiency. NREL and Acciona Energy North America (Acciona) are developing a method to control the levels of dissolved hydrogen in the circulating HTF. The basic approach is to remove hydrogen from the expansion tanks of the HTF subsystem at a rate that maintains hydrogen in the circulating HTF to a target level. Full-plant steady-state models developed by the National Renewable Energy Laboratory (NREL) predict that if hydrogen is removed from the HTF within the expansion tanks, the HTF that circulates through the collector field remains essentially free of hydrogen until the HTF returns to the power block in the hot headers. One of the key findings of our modeling is the prediction that hydrogen will reverse-permeate out of the receiver annulus if dissolved hydrogen in the HTF is kept sufficiently low. To test this prediction, we performed extended heating of an in-service receiver that initially had high levels of hydrogen in its annulus. The heating was performed using NREL's receiver test stand. Results of our testing showed that receiver heat loss steadily decreased with daily heating, resulting in a corresponding improvement in receiver thermal efficiency.

Heat and mass transfer effects on MHD viscoelastic fluid over a stretching sheet through porous medium in presence of chemical reaction

Directory of Open Access Journals (Sweden)

Manoj Kumar Nayak

2016-03-01

Full Text Available An attempt has been made to study the heat and mass transfer effects in a boundary layer flow through porous medium of an electrically conducting viscoelastic fluid subject to transverse magnetic field in the presence of heat source/sink and chemical reaction. It has been considered the effects of radiation, viscous and Joule dissipations and internal heat generation/absorption. Closed form solutions for the boundary layer equations of viscoelastic, second-grade and Walters׳ B′ fluid models are obtained. The method of solution involves similarity transformation. The transformed equations of thermal and mass transport are solved by applying Kummer׳s function. The solutions of temperature field for both prescribed surface temperature (PST as well as prescribed surface heat flux (PHF are obtained. It is important to remark that the interaction of magnetic field is found to be counterproductive in enhancing velocity and concentration distribution whereas the presence of chemical reaction as well as porous matrix with moderate values of magnetic parameter reduces the temperature and concentration fields at all points of flow domain.

Development of a Novel Method for the Exploration of the Thermal Response of Superfluid Helium Cooled Superconducting Cables to Pulse Heat Loads

Science.gov (United States)

Winkler, T.; Koettig, T.; van Weelderen, R.; Bremer, J.; ter Brake, H. J. M.

Management of transient heat deposition in superconducting magnets and its extraction from the aforementioned is becoming increasingly important to bring high energy particle accelerator performance to higher beam energies and intensities. Precise knowledge of transient heat deposition phenomena in the magnet cables will permit to push the operation of these magnets as close as possible to their current sharing limit, without unduly provoking magnet quenches. With the prospect of operating the Large Hadron Collider at CERN at higher beam energies and intensities an investigation into the response to transient heat loads of LHC magnets, operating in pressurized superfluid helium, is being performed. The more frequently used approach mimics the cable geometry by resistive wires and uses Joule-heating to deposit energy. Instead, to approximate as closely as possible the real magnet conditions, a novel method for depositing heat in cable stacks made out of superconducting magnet-cables has been developed. The goal is to measure the temperature difference as a function of time between the cable stack and the superfluid helium bath depending on heat load and heat pulse length. The heat generation in the superconducting cable and precise measurement of small temperature differences are major challenges. The functional principle and experimental set-up are presented together with proof of principle measurements.

The impact of short-term heat storage on the ice-albedo feedback loop

Science.gov (United States)

Polashenski, C.; Wright, N.; Perovich, D. K.; Song, A.; Deeb, E. J.

2016-12-01

The partitioning of solar energy in the ice-ocean-atmosphere environment is a powerful control over Arctic sea ice mass balance. Ongoing transitions of the sea ice toward a younger, thinner state are enhancing absorption of solar energy and contributing to further declines in sea ice in a classic ice-albedo feedback. Here we investigate the solar energy balance over shorter timescales. In particular, we are concerned with short term delays in the transfer of absorbed solar energy to the ice caused by heat storage in the upper ocean. By delaying the realization of ice melt, and hence albedo decline, heat storage processes effectively retard the intra-season ice-albedo feedback. We seek to quantify the impact and variability of such intra-season storage delays on full season energy absorption. We use in-situ data collected from Arctic Observing Network (AON) sea ice sites, synthesized with the results of imagery processed from high resolution optical satellites, and basin-scale remote sensing products to approach the topic. AON buoys are used to monitor the storage and flux of heat, while satellite imagery allows us to quantify the evolution of surrounding ice conditions and predict the aggregate scale solar absorption. We use several test sites as illustrative cases and demonstrate that temporary heat storage can have substantial impacts on seasonal energy absorption and ice loss. A companion to this work is presented by N. Wright at this meeting.

On variations of space-heating energy use in office buildings

International Nuclear Information System (INIS)

Lin, Hung-Wen; Hong, Tianzhen

2013-01-01

Highlights: • Space heating is the largest energy end use in the U.S. building sector. • A key design and operational parameters have the most influence on space heating. • Simulated results were benchmarked against actual results to analyze discrepancies. • Yearly weather changes have significant impact on space heating energy use. • Findings enable stakeholders to make better decisions on energy efficiency. - Abstract: Space heating is the largest energy end use, consuming more than seven quintillion joules of site energy annually in the U.S. building sector. A few recent studies showed discrepancies in simulated space-heating energy use among different building energy modeling programs, and the simulated results are suspected to be underpredicting reality. While various uncertainties are associated with building simulations, especially when simulations are performed by different modelers using different simulation programs for buildings with different configurations, it is crucial to identify and evaluate key driving factors to space-heating energy use in order to support the design and operation of low-energy buildings. In this study, 10 design and operation parameters for space-heating systems of two prototypical office buildings in each of three U.S. heating climates are identified and evaluated, using building simulations with EnergyPlus, to determine the most influential parameters and their impacts on variations of space-heating energy use. The influence of annual weather change on space-heating energy is also investigated using 30-year actual weather data. The simulated space-heating energy use is further benchmarked against those from similar actual office buildings in two U.S. commercial-building databases to better understand the discrepancies between simulated and actual energy use. In summary, variations of both the simulated and actual space-heating energy use of office buildings in all three heating climates can be very large. However

Uncertainty estimation of non-ideal analog switches using programmable Josephson voltage standards for mutual inductance measurement in the joule balance

International Nuclear Information System (INIS)

Wang, Gang; Zhang, Zhonghua; Li, Zhengkun; Xu, Jinxin; You, Qiang

2016-01-01

Measurement of the mutual inductance is one of the key techniques in the joule balance to determine the Planck constant h, where a standard-square-wave compensation method was proposed to accurately measure the dc value of the mutual inductance. With this method, analog switches are used to compose an analog-switch signal generator to synthesize the excitation and compensation voltages. However, the accuracy of the compensation voltage is influenced by the non-ideal behaviors of analog-switches. In this paper, the effect from these non-ideal switches is analyzed in detail and evaluated with the equivalent circuits. A programmable Josephson voltage standard (PJVS) is used to generate a reference compensation voltage to measure the time integration of the voltage waveform generated by the analog-switch signal generator. Moreover, the effect is also evaluated experimentally by comparing the difference between the mutual inductance measured with the analog-switch signal generator and the value determined by the PJVS-analog-switch generator alternately in the same mutual inductance measurement system. The result shows that the impact of analog switches is 1.97  ×  10 −7 with an uncertainty of 1.83  ×  10 −7 (k  =  1) and confirms that the analog switch method can be used regularly instead of the PJVS in the mutual inductance measurement for the joule balance experiment. (paper)

Doctor Julius Robert Mayer and Energy Processes in Living Systems

Science.gov (United States)

Erlichson, Herman

2007-01-01

The overwhelming majority of important papers in physics are written by physicists. But the physician Julius Robert Mayer (1814-1878, see photo) did a valid theoretical calculation of the mechanical equivalent of heat just before Joule reported on his results from his well-known paddle-wheel experiments. Joule is well-known to physics people and…

Metal-insulator transition upon heating and negative-differential-resistive-switching induced by self-heating in BaCo{sub 0.9}Ni{sub 0.1}S{sub 1.8}

Energy Technology Data Exchange (ETDEWEB)

Fisher, B.; Genossar, J.; Chashka, K. B.; Patlagan, L.; Reisner, G. M. [Physics Department, Technion-Israel Institute of Technology, Haifa 32000 (Israel)

2014-04-14

The layered compound BaCo{sub 1−x}Ni{sub x}S{sub 2−y} (0.05 < x < 0.2 and 0.05 < y < 0.2) exhibits an unusual first-order structural and electronic phase transition from a low-T monoclinic paramagnetic metal to a high-T tetragonal antiferromagnetic insulator around 200 K with huge hysteresis (∼40 K) and large volume change (∼0.01). Here, we report on unusual voltage-controlled resistive switching followed by current-controlled resistive switching induced by self-heating in polycrystalline BaCo{sub 1−x}Ni{sub x}S{sub 2−y} (nominal x = 0.1 and y = 0.2). These were due to the steep metal to insulator transition upon heating followed by the activated behavior of the resistivity above the transition. The major role of Joule heating in switching is supported by the absence of nonlinearity in the current as function of voltage, I(V), obtained in pulsed measurements, in the range of electric fields relevant to d.c. measurements. The voltage-controlled negative differential resistance around the threshold for switching was explained by a simple model of self-heating. The main difficulty in modeling I(V) from the samples resistance as function of temperature R(T) was the progressive increase of R(T), and to a lesser extend the decrease of the resistance jumps at the transitions, caused by the damage induced by cycling through the transitions by heating or self-heating. This was dealt with by following systematically R(T) over many cycles and by using the data of R(T) in the heating cycle closest to that of the self-heating one.

Compact Representation for Specific Heat of Interacting Fermion Systems in Terms of Fully Renormalized Matsubara Green Function

OpenAIRE

Miyake, Kazumasa; Tsuruta, Atsushi

2015-01-01

On the basis of the Luttinger-Ward formalism for the thermodynamic potential, the specific heat of single-component interacting fermion systems with fixed chemical potential is compactly expressed in terms of the fully renormalized Matsubara Green function.

Isobaric specific heat capacity of water and aqueous cesium chloride solutions for temperatures between 298 K and 370 K at p = 0.1 MPa

International Nuclear Information System (INIS)

Lourenco, M.J.V.; Santos, F.J.V.; Ramires, M.L.V.; Nieto de Castro, C.A.

2006-01-01

There has been some controversy regarding the uncertainty of measurements of thermal properties using differential scanning calorimeters, namely heat capacity of liquids. A differential scanning calorimeter calibrated in enthalpy and temperature was used to measure the isobaric specific heat capacity of water and aqueous solutions of cesium chloride, in the temperature range 298 K to 370 K, for molalities up 3.2 mol . kg -1 , at p = 0.1 MPa, with an estimated uncertainty (ISO definition) better than 1.1%, at a 95% confidence level. The measurements are completely traceable to SI units of energy and temperature. The results obtained were correlated as a function of temperature and molality and compared with other authors, obtained by different methods and permit to conclude that a DSC calibrated by Joule effect is capable of very accurate measurements of the isobaric heat capacity of liquids, traceable to SI units of measurement

Transient heat transfer analysis of superconducting magnetic levitating flywheel rotor operating in vacuum

Energy Technology Data Exchange (ETDEWEB)

Mochida, A.; Kudo, K.; Higasa, H.

1999-07-01

In the present study, transient temperature rise is analyzed in a flywheel type power storage system operated in vacuum environment. The flywheel rotor is levitated by high-temperature-superconducting magnetic bearing to reduce the bearing loss. Though the superconductor is cooled by liquid nitrogen, the temperature of the whole system rises due to Joule heating in the coils of the bearings and the motor during the operation. If the temperature should reach the critical temperature of the permanent magnet used for the magnetic bearings after long time operation, the magnetic bearings lose their effect. The heat generated in the levitated rotor diffuses within it by heat conduction and finally emitted to its surrounding solid materials by thermal radiation from the rotor surfaces across vacuum layer. Numerical simulation is carried out calculating the transient radiative-conductive heat transfer and time-dependent profiles of temperature within the rotor are obtained. The results are compared with the experimentally obtained temperatures by measured a test model of 1kWh power storage and the measured profiles of the temperature rise of the rotor fit very well with the calculated ones. Using this simulation tool, the effects of the surface emissivity of the materials of the rotor and the stator, the temperature of the surrounding casings and the thermal conductivity of the materials on the temperature profiles in the system are estimated.

Impact of environmental contamination on laser induced damage of silica optics in Laser MegaJoule

International Nuclear Information System (INIS)

Bien-Aime, K.

2009-11-01

Laser induced damage impact of molecular contamination on fused polished silica samples in a context of high power laser fusion facility, such as Laser MegaJoule (LMJ) has been studied. One of the possible causes of laser induced degradation of optical component is the adsorption of molecular or particular contamination on optical surfaces. In the peculiar case of LMJ, laser irradiation conditions are a fluence of 10 J/cm 2 , a wavelength of 351 nm, a pulse duration of 3 ns for a single shot/days frequency. Critical compounds have been identified thanks to environmental measurements, analysis of material outgassing, and identification of surface contamination in the critical environments. Experiments of controlled contamination involving these compounds have been conducted in order to understand and model mechanisms of laser damage. Various hypotheses are proposed to explain the damage mechanism. (author)

Heat pipes for ground heating and cooling

Energy Technology Data Exchange (ETDEWEB)

Vasiliev, L L

1988-01-01

Different versions of heat pipe ground heating and cooling devices are considered. Solar energy, biomass, ground stored energy, recovered heat of industrial enterprises and ambient cold air are used as energy and cold sources. Heat pipe utilization of air in winter makes it possible to design accumulators of cold and ensures deep freezing of ground in order to increase its mechanical strength when building roadways through the swamps and ponds in Siberia. Long-term underground heat storage systems are considered, in which the solar and biomass energy is accumulated and then transferred to heat dwellings and greenhouses, as well as to remove snow from roadways with the help of heat pipes and solar collectors.

Long term performance of a solar floor and hot water heating house; Taiyonetsu yukadanbo kyuto jutaku no choki seino

Energy Technology Data Exchange (ETDEWEB)

Udagawa, M [Kogakuin University, Tokyo (Japan)

1997-11-25

Outlined herein are measured energy consumption followed for 12 years for a totally electrified solar house with a floor-heating and hot-water heating system. In the solar system, hot water generated by the solar collector is sent, via a surge tank, to a living room, dining room and study to heat their concrete floors, and recycled back to the collector after heating the heat-storage tank for hot water supply. The collector is of plate type, consisting of 6 units, each with a white glass sheet as the heat-collecting membrane for selectively absorbing heat. Its total heat-collecting area is 11.4m{sup 2}. Long-term performance of the solar system installed for floor and hot-water heating in a totally electrified solar house, is analyzed by the measured results collected for 12 years. The house consumes secondary energy of 11.7MWh/year on the average, which is approximately 20% lower that that required for a house of the equivalent size. The solar system has been operated smoothly, to supply 46 and 35% of the required heat for hot-water and floor heating. It is however estimated that annual heat loss reaches 34% in the hot-water heating system, including that in the electric hot-water generator, and prevention of heat loss is one of the major themes for the future system designs. 4 refs., 5 figs.

Iron Phosphate Glass for Vitrifying Hanford AZ102 LAW in Joule Heated and Cold Crucible Induction Melters - 12240

Energy Technology Data Exchange (ETDEWEB)

Day, Delbert E.; Brow, Richard K.; Ray, Chandra S.; Reis, Signo T. [Missouri University of Science and Technology, 1870 Miner Circle, Rolla, MO 65409 (United States); Kim, Cheol-Woon [MO-SCI Corporation, 4040 HyPoint North, Rolla, MO 65401 (United States); Vienna, John D.; Sevigny, Gary [Pacific North West National Laboratory, Battelle Blvd., Richland, WA 99352 (United States); Peeler, David; Johnson, Fabienne C.; Hansen, Eric K. [Savannah River National Laboratory, Savannah River Site, 999-W, Aiken, SC 29803 (United States); Soelberg, Nick [Idaho National Laboratory, 2525 Fremont Avenue, Idaho Falls, ID 83415 (United States); Pegg, Ian L.; Gan, Hao [Catholic University of America, 620 Michigan Avenue, N.E., Washington, DC 20064 (United States)

2012-07-01

An iron phosphate composition for vitrifying a high sulfate (∼17 wt%) and high alkali (∼80 wt%) Hanford low activity waste (LAW), known as AZ-102 LAW, has been developed for processing in a Joule Heated Melter (JHM) or a Cold Crucible Induction Melter (CCIM). This composition produced a glass waste form, designated as MS26AZ102F-2, with a waste loading of 26 wt% of the AZ-102 which corresponded to a total alkali and sulfate (represented as SO{sub 3}) content of 21 and 4.4 wt%, respectively. A slurry (7 M Na{sup +}) of MS26AZ102F-2 simulant was melted continuously at temperatures between 1030 and 1090 deg. C for 10 days in a small JHM at PNNL and for 70 hours in a CCIM at INL. The as-cast glasses produced in both melters and in trial laboratory experiments along with their canister centerline cooled (CCC) counterparts met the requirements for the Product Consistency Test (PCT) and the Vapor Hydration Test (VHT) responses in the Hanford Tank Waste Treatment and Immobilization Plant (WTP) Contract. These glass waste forms retained up to 77 % of the SO{sub 3} (3.3 wt%), 100% of the Cesium, and 33 to 44% of the rhenium (used as a surrogate for Tc) all of which either exceeded or were comparable to the retention limit for these species in borosilicate glass nuclear waste form. Analyses of commercial K-3 refractory lining and the Inconel 693 metal electrodes used in JHM indicated only minimum corrosion of these components by the iron phosphate glass. This is the first time that an iron phosphate composition was melted continuously in a slurry fed JHM and in the US, thereby, demonstrating that iron phosphate glasses can be used as alternative hosts for vitrifying nuclear waste. The following conclusions are drawn from the results of the present work. (1) An iron phosphate composition, designated as MS26AZ102F-2, containing 26 wt% of the simulated high sulfate (17 wt%), high alkali (80 wt%) Hanford AZ-102 LAW meets all the criteria for processing in a JHM and CCIM. This

Electrically controllable twisted-coiled artificial muscle actuators using surface-modified polyester fibers

Science.gov (United States)

Park, Jungwoo; Yoo, Ji Wang; Seo, Hee Won; Lee, Youngkwan; Suhr, Jonghwan; Moon, Hyungpil; Koo, Ja Choon; Ryeol Choi, Hyouk; Hunt, Robert; Kim, Kwang Jin; Kim, Soo Hyun; Nam, Jae-Do

2017-03-01

As a new class of thermally activated actuators based on polymeric fibers, we investigated polyethylene terephthalate (PET) yarns for the development of a twisted-coiled polymer fiber actuator (TCA). The PET yarn TCA exhibited the maximum linear actuation up to 8.9% by external heating at above the glass transition temperature, 160 °C-180 °C. The payload of the actuator was successfully correlated with the preload and training-load conditions by an empirical equation. Furthermore, the PET-based TCA was electrically driven by Joule heating after the PET surface was metallization with silver. For the fast and precise control of PET yarn TCA, electroless silver plating was conducted to form electrical conductive layers on the PET fiber surface. The silver plated PET-based TCA was tested by Joule heating and the tensile actuation was increased up to 12.1% (6 V) due to the enhanced surface hardness and slippage of PET fibers. Overall, silver plating of the polymeric yarn provided a fast actuation speed and enhanced actuation performance of the TCA actuator by Joule heating, providing a great potential for being used in artificial muscle for biomimetic machines including robots, industrial actuators and powered exoskeletons.

Estimation of performance of a J-T refrigerators operating with nitrogen-hydrocarbon mixtures and a coiled tubes-in-tube heat exchanger

Science.gov (United States)

Satya Meher, R.; Venkatarathnam, G.

2018-06-01

The exergy efficiency of Joule-Thomson (J-T) refrigerators operating with mixtures (MRC systems) strongly depends on the choice of refrigerant mixture and the performance of the heat exchanger used. Helically coiled, multiple tubes-in-tube heat exchangers with an effectiveness of over 96% are widely used in these types of systems. All the current studies focus only on the different heat transfer correlations and the uncertainty in predicting performance of the heat exchanger alone. The main focus of this work is to estimate the uncertainty in cooling capacity when the homogenous model is used by comparing the theoretical and experimental studies. The comparisons have been extended to some two-phase models present in the literature as well. Experiments have been carried out on a J-T refrigerator at a fixed heat load of 10 W with different nitrogen-hydrocarbon mixtures in the evaporator temperature range of 100-120 K. Different heat transfer models have been used to predict the temperature profiles as well as the cooling capacity of the refrigerator. The results show that the homogenous two-phase flow model is probably the most suitable model for rating the cooling capacity of a J-T refrigerator operating with nitrogen-hydrocarbon mixtures.

Thermal modeling of cylindrical lithium ion battery during discharge cycle

International Nuclear Information System (INIS)

Jeon, Dong Hyup; Baek, Seung Man

2011-01-01

Highlights: → Transient and thermo-electric finite element analysis (FEA) of cylindrical lithium ion (Li-ion) battery was presented. → This model provides the thermal behavior of Li-ion battery during discharge cycle. → A LiCoO 2 /C battery at various discharge rates was investigated. → The contribution of heat source due to joule heating was significant at a high discharge rate. → The contribution of heat source due to entropy change was dominant at a low discharge rate. - Abstract: Transient and thermo-electric finite element analysis (FEA) of cylindrical lithium ion (Li-ion) battery was presented. The simplified model by adopting a cylindrical coordinate was employed. This model provides the thermal behavior of Li-ion battery during discharge cycle. The mathematical model solves conservation of energy considering heat generations due to both joule heating and entropy change. A LiCoO 2 /C battery at various discharge rates was investigated. The temperature profile from simulation had similar tendency with experiment. The temperature profile was decomposed with contributions of each heat sources and was presented at several discharge rates. It was found that the contribution of heat source due to joule heating was significant at a high discharge rate, whereas that due to entropy change was dominant at a low discharge rate. Also the effect of cooling condition and the LiNiCoMnO 2 /C battery were analyzed for the purpose of temperature reduction.

Optimal usage of low temperature heat sources to supply district heating by heat pumps

DEFF Research Database (Denmark)

Pieper, Henrik; Ommen, Torben Schmidt; Markussen, Wiebke Brix

2017-01-01

This paper presents a theoretical study on the optimal usage of different low temperature heat sources to supply district heating by heat pumps. The study is based on data for the Copenhagen region. The heat sources were prioritized based on the coefficient of performance calculated for each hour...... and the covered demand of each heat source as well as required peak unit capacity. The results showed that heat pumps using different heat sources yield better performance than a heat pump based on a single one. The performance was influenced by the composition of the different heat sources. It was found that 78......% groundwater, 22% seawater and 0% air resulted in highest COP of 3.33 for the given heat demand. Furthermore, the implementation of rule based short term storage made peak units redundant. The variation in base load capacity showed that heat pumps utilizing the analyzed heat sources could perform very...

Combined heat and power production planning in a waste-to-energy plant on a short-term basis

International Nuclear Information System (INIS)

Touš, Michal; Pavlas, Martin; Putna, Ondřej; Stehlík, Petr; Crha, Lukáš

2015-01-01

In many cases, WtE (waste-to-energy) plants are CHP (combined heat and power) producers. They are often integrated into a central heating system and they also export electricity to the grid. Therefore, they have to plan their operation on a long-term basis (months, years) as well as on a short-term basis (hours, days). Simulation models can effectively support decision making in CHP production planning. In general, CHP production planning on a short-term basis is a challenging task for WtE plants. This article presents a simulation based support. It is demonstrated on an example involving a real WtE plant. Most of the models of relevant WtE sub-systems (boilers, steam turbine) are developed using operational data and applying linear regression and artificial neural network technique. The process randomness given mainly by fluctuating heating value of waste leads to uncertainty in a calculation of CHP production and a stochastic approach is appropriate. The models of the sub-systems are, therefore, extended of a stochastic part and Monte-Carlo simulation is applied. Compared to the current planning strategy in the involved WtE plant, the stochastic simulation based planning provides increased CHP production resulting in better net thermal efficiency and increased revenue. This is demonstrated through a comparison using real operational data. - Highlights: • Introduction of a stochastic model of a CHP production in a waste-to-energy plant. • An application of the model for the next day CHP production planning. • Better net thermal efficiency and therefore increased revenue achieved.

Effect of short-term heat acclimation on endurance time and skin blood flow in trained athletes

Directory of Open Access Journals (Sweden)

Chen TI

2013-06-01

Full Text Available Tsung-I Chen,1,2 Pu-Hsi Tsai,3 Jui-Hsing Lin,4 Ning-Yuean Lee,5 Michael TC Liang61Graduate Institute of Sport Science, National Taiwan Sport University, Taoyuan, 2Center for Physical Education, Tzu Chi University, Hualien, 3Department of Sport and Leisure, National Quemoy University, Kinmen, 4Department of Physical Education, National Pingtung University of Education, Pingtung, 5College of Living Technology, Tainan University of Technology, Tainan, Taiwan; 6Department of Kinesiology and Health Promotion, California State Polytechnic University, Pomona, CA, USABackground: To examine whether short-term, ie, five daily sessions, vigorous dynamic cycling exercise and heat exposure could achieve heat acclimation in trained athletes and the effect of heat acclimation on cutaneous blood flow in the active and nonactive limb.Methods: Fourteen male badminton and table tennis athletes (age = 19.6 ± 1.2 years were randomized into a heat acclimation (EXP, n = 7 or nonheat acclimation (CON, n = 7 group. For 5 consecutive days, the EXP group was trained using an upright leg cycle ergometer in a hot environment (38.4°C ± 0.4°C, while the CON group trained in a thermoneutral environment (24.1°C ± 0.3°C. For both groups, the training intensity and duration increased from a work rate of 10% below ventilatory threshold (VT and 25 minutes per session on day 1, to 10% above VT and 45 minutes per session on day 5. Subjects performed two incremental leg cycle exercise tests to exhaustion at baseline and post-training in both hot and thermoneutral conditions. Study outcome measurements include: maximum oxygen uptake (VO2max; exercise heart rate (HR; O2 pulse; exercise time to exhaustion (tmax; skin blood flow in the upper arm (SkBFa and quadriceps (SkBFq; and mean skin (Tsk.Results: The significant heat-acclimated outcome measurements obtained during high-intensity leg cycling exercise in the high ambient environment are: (1 56%–100% reduction in cutaneous

Heavy-ion driver parametric studies and choice of a base 5 mega-joule driver design

International Nuclear Information System (INIS)

Bieri, R.; Meier, W.

1992-01-01

Parametric studies to optimize heavy-ion driver designs are described and an optimized 5 MJ driver design is described. Parametric studies are done on driver parameters including driver energy, number of beams, type of superconductor used in focusing magnets, maximum magnetic field allowed at the superconducting windings, axial quadrupole field packing fraction, ion mass, and ion charge state. All modeled drivers use the maximum beam currents allowed by the Maschke limits; driver scaling is described in a companion paper. The optimized driver described is conservative and cost effective. The base driver direct costs are only $120/Joule, and the base driver uses no recirculation, beam combination, or beam separation. The low driver cost achieved is due, in part, to the use of compact Nb 3 Sn quadrupole arrays, but results primarily from optimization over the large, multi-dimensional, parameter space available for heavy-ion drivers

Luminescence Materials as Nanoparticle Thermal Sensors

Science.gov (United States)

2016-06-01

3!:!-!A!" Light path Power meter Silicon detector ...222 newton (N) Energy/Work/Power electron volt (eV) 1.602 177 × 10 –19 joule (J) erg 1 × 10 –7 joule (J) kiloton (kt) (TNT equivalent) 4.184...ionizing radiation fill the trapping centers heating light detector conduction band valence band traps 2. exposure to temperature profile partially empties

Creep and long-term strength of heat-resistant steels with different structures with the account taken of the type of stress deviator

International Nuclear Information System (INIS)

Giginyak, F.F.; Dragunov, Yu.G.; Mozharovskaya, T.N.; Titov, V.F.

1993-01-01

The results of the experimental investigations into creep and long-term strength of heat-resistant steels 15Kh2MFA and 15Kh2NMFA in the initial state and after heat-treatment simulating the metal irradiation embrittlement at the end of the product service date under static loading at the complex stress state and at high temperatures are presented. The experimentally substantiated equations of state describing creep and long-term stability of materials taking into account the type of the stress state are derived. (author)

Electrical sintering of silver nanoparticle ink studied by in-situ TEM probing.

Directory of Open Access Journals (Sweden)

Magnus Hummelgård

Full Text Available Metallic nanoparticle inks are used for printed electronics, but to reach acceptable conductivity the structures need to be sintered, usually using a furnace. Recently, sintering by direct resistive heating has been demonstrated. For a microscopic understanding of this Joule heating sintering method, we studied the entire process in real time inside a transmission electron microscope equipped with a movable electrical probe. We found an onset of Joule heating induced sintering and coalescence of nanoparticles at power levels of 0.1-10 mW/μm³. In addition, a carbonization of the organic shells that stabilize the nanoparticles were found, with a conductivity of 4 10⁵ Sm⁻¹.

Dynamic design of gas sorption J-T refrigerator

International Nuclear Information System (INIS)

Chan, C.K.

1986-01-01

A long-life Joule-Thomson refrigerator which is heat powered, involves no sealing, and has few mechanical parts and is desirable for longterm sensor cooling in space. In the gas-sorption J-T refrigerator, cooling is achieved by gas sorption (either adsorption or absorption) processes. Currently, a modular, single-stage refrigerator is being designed and built to be operated at 20 K. The design was analyzed using a dynamic model, which is described here. The model includes the kinetics of the compressors and the heat switches, the heat transfer of the pre-coolers and the heat exchangers, the on/off ratio of the check valves, and the impedance of the J-T valve. The cooling power, the cycle time, and the operating conditions were obtained in terms of the power input, the heat sink temperature, and the J-T impedance

Wind power integration using individual heat pumps – Analysis of different heat storage options

DEFF Research Database (Denmark)

Hedegaard, Karsten; Mathiesen, Brian Vad; Lund, Henrik

2012-01-01

Significant installations of individual heat pumps are expected in future energy systems due to their economic competitiveness. This case study of the Danish energy system in 2020 with 50% wind power shows that individual heat pumps and heat storages can contribute to the integration of wind power....... Heat accumulation tanks and passive heat storage in the construction are investigated as two alternative storage options in terms of their ability to increase wind power utilisation and to provide cost-effective fuel savings. Results show that passive heat storage can enable equivalent to larger...... reductions in excess electricity production and fuel consumption than heat accumulation tanks. Moreover, passive heat storage is found to be significantly more cost-effective than heat accumulation tanks. In terms of reducing fuel consumption of the energy system, the installation of heat pumps is the most...

Eddy damping effect of additional conductors in superconducting levitation systems

Energy Technology Data Exchange (ETDEWEB)

Jiang, Zhao-Fei; Gou, Xiao-Fan, E-mail: xfgou@hhu.edu.cn

2015-12-15

Highlights: • In this article, for the eddy current damper attached to the HTSC, we • quantitatively investigated the damping coefficient c, damping ratio, Joule heating of the copper damper, and the vibration frequency of the PM as well. • presented four different arrangements of the copper damper, and comparatively studied their damping effects and Joule heating, and finally proposed the most advisable arrangement. - Abstract: Passive superconducting levitation systems consisting of a high temperature superconductor (HTSC) and a permanent magnet (PM) have demonstrated several fascinating applications such as the maglev system, flywheel energy storage. Generally, for the HTSC–PM levitation system, the HTSC with higher critical current density J{sub c} can obtain larger magnetic force to make the PM levitate over the HTSC (or suspended below the HTSC), however, the process of the vibration of the levitated PM, provides very limited inherent damping (essentially hysteresis). To improve the dynamic stability of the levitated PM, eddy damping of additional conductors can be considered as the most simple and effective approach. In this article, for the HTSC–PM levitation system with an additional copper damper attached to the HTSC, we numerically and comprehensively investigated the damping coefficient c, damping ratio, Joule heating of the copper damper, and the vibration frequency of the PM as well. Furthermore, we comparatively studied four different arrangements of the copper damper, on the comprehensive analyzed the damping effect, efficiency (defined by c/V{sub Cu}, in which V{sub Cu} is the volume of the damper) and Joule heating, and finally presented the most advisable arrangement.

Chem Gems & Joules

Science.gov (United States)

Mason, Diana S.

2002-09-01

Learn about the chemistry (and some physics) of optical discs such as CDs, CD-ROMs, and DVDs from David Birkett (p 1081). Beginning on p 1088, Johnson and Yalkowsky present some neat models (commercial or build-yourself) that assemble of their own accord into appropriate structures for liquid and solid water. Do you need a low-cost, small-scale heating device? How about adapting a soldering iron as described on p 1109? If you are interested in cooperative learning, the comparison with lecturing that begins on p 1131 will provide useful information. The latest in our series commemorating the centenary of the Nobel Prizes begins on p 1055. The many interconnections among the research of prizewinners described in this series provides interesting tidbits to humanize chemical kinetics. Do you have hydrogen peroxide, sulfur, or potassium chromate in your lab or chemical storage area? Learn about hazards of these substances from the letter to the editor on p 1070 and the CLIPs on p 1063, p 1064, and p 1065. Finally, keep up with chemical education news at the ACS and the NSF by reading the statements of candidates for the ACS presidency (p 1036 and p 1037) and the commentary by Ellis on p 1034.

New waste heat district heating system with combined heat and power based on absorption heat exchange cycle in China

International Nuclear Information System (INIS)

Sun Fangtian; Fu Lin; Zhang Shigang; Sun Jian

2012-01-01

A new waste heat district heating system with combined heat and power based on absorption heat exchange cycle (DHAC) was developed to increase the heating capacity of combined heat and power (CHP) through waste heat recovery, and enhance heat transmission capacity of the existing primary side district heating network through decreasing return water temperature by new type absorption heat exchanger (AHE). The DHAC system and a conventional district heating system based on CHP (CDH) were analyzed in terms of both thermodynamics and economics. Compared to CDH, the DHAC increased heating capacity by 31% and increased heat transmission capacity of the existing primary side district heating network by 75%. The results showed that the exergetic efficiency of DHAC was 10.41% higher and the product exergy monetary cost was 36.6¥/GJ less than a CHD. DHAC is an effective way to increase thermal utilization factor of CHP, and to reduce district heating cost. - Highlights: ► Absorption heat pumps are used to recover waste heat in CHP. ► Absorption heat exchanger can reduce exergy loss in the heat transfer process. ► New waste heat heating system (DHAC) can increase heating capacity of CHP by 31%. ► DHAC can enhance heat transmission capacity of the primary pipe network by 75%. ► DHAC system has the higher exergetic efficiency and the better economic benefit.

HEATING MECHANISMS IN THE LOW SOLAR ATMOSPHERE THROUGH MAGNETIC RECONNECTION IN CURRENT SHEETS

Energy Technology Data Exchange (ETDEWEB)

Ni, Lei; Lin, Jun [Yunnan Observatories, Chinese Academy of Sciences, Kunming 650011 (China); Roussev, Ilia I. [Division of Geosciences, National Science Foundation Arlington, Virginia (United States); Schmieder, Brigitte, E-mail: leini@ynao.ac.cn [Observatoire de Paris, LESIA, Meudon (France)

2016-12-01

We simulate several magnetic reconnection processes in the low solar chromosphere/photosphere; the radiation cooling, heat conduction and ambipolar diffusion are all included. Our numerical results indicate that both the high temperature (≳8 × 10{sup 4} K) and low temperature (∼10{sup 4} K) magnetic reconnection events can happen in the low solar atmosphere (100–600 km above the solar surface). The plasma β controlled by plasma density and magnetic fields is one important factor to decide how much the plasma can be heated up. The low temperature event is formed in a high β magnetic reconnection process, Joule heating is the main mechanism to heat plasma and the maximum temperature increase is only several thousand Kelvin. The high temperature explosions can be generated in a low β magnetic reconnection process, slow and fast-mode shocks attached at the edges of the well developed plasmoids are the main physical mechanisms to heat the plasma from several thousand Kelvin to over 8 × 10{sup 4} K. Gravity in the low chromosphere can strongly hinder the plasmoid instability and the formation of slow-mode shocks in a vertical current sheet. Only small secondary islands are formed; these islands, however, are not as well developed as those in the horizontal current sheets. This work can be applied to understand the heating mechanism in the low solar atmosphere and could possibly be extended to explain the formation of common low temperature Ellerman bombs (∼10{sup 4} K) and the high temperature Interface Region Imaging Spectrograph (IRIS) bombs (≳8 × 10{sup 4}) in the future.

Preliminary Analysis on Heat Removal Capacity of Passive Air-Water Combined Cooling Heat Exchanger Using MARS

International Nuclear Information System (INIS)

Kim, Seung-Sin; Jeon, Seong-Su; Hong, Soon-Joon; Bae, Sung-Won; Kwon, Tae-Soon

2015-01-01

Current design requirement for working time of PAFS heat exchanger is about 8 hours. Thus, it is not satisfied with the required cooling capability for the long term SBO(Station Black-Out) situation that is required to over 72 hours cooling. Therefore PAFS is needed to change of design for 72 hours cooling. In order to acquirement of long terms cooling using PAFS, heat exchanger tube has to be submerged in water tank for long time. However, water in the tank is evaporated by transferred heat from heat exchanger tubes, so water level is gradually lowered as time goes on. The heat removal capacity of air cooling heat exchanger is core parameter that is used for decision of applicability on passive air-water combined cooling system using PAFS in long term cooling. In this study, the development of MARS input model and plant accident analysis are performed for the prediction of the heat removal capacity of air cooling heat exchanger. From analysis result, it is known that inflow air velocity is the decisive factor of the heat removal capacity and predicted air velocity is lower than required air velocity. But present heat transfer model and predicted air velocity have uncertainty. So, if changed design of PAFS that has over 4.6 kW heat removal capacity in each tube, this type heat exchanger can be applied to long term cooling of the nuclear power plant

Study on heat transfer process during leaks of high pressure argon through a realistic crack

International Nuclear Information System (INIS)

Ai, Gang; Liu, Yinghua; Wah Ng, Heong

2016-01-01

This paper proposes a method for simulating the heat transfer process of high pressure argon gas leaking through a narrow crack which causes the Joule-Thomson cooling effect (JT cooling effect). A once-through (decoupled) model was developed to firstly calculate the gas pressure drop at different crack depth, followed by the temperature drop. A MATLAB code was also developed to iteratively calculate the properties of leaking gas in a crack which was fitted as formula as boundary conditions in heat transfer simulation in COMSOL program. The simulated lowest temperature of the test plate in the vicinity of the crack is 13.8 C after decreasing from the temperature of 30 C with initial argon gas pressure of 91 bar. An experiment test rig designed and tested under the same conditions showed a good agreement between the simulation and experiment at the obtained lowest temperature in the test plate. The method is useful for predicting the lowest temperature in the vicinity of the crack caused by the JT cooling effect. (authors)

Impact of Joule heating, roughness, and contaminants on the relative hardness of polycrystalline gold

International Nuclear Information System (INIS)

Freeze, Christopher R; Ji, Xiaoyin; Irving, Douglas L; Kingon, Angus I

2013-01-01

Asperities play a central role in the mechanical and electrical properties of contacting surfaces. Changes in trends of uniaxial compression of an asperity tip in contact with a polycrystalline substrate as a function of substrate geometry, compressive stress and applied voltage are investigated here by implementation of a coupled continuum and atomistic approach. Surprisingly, an unmodified Au polycrystalline substrate is found to be softer than one containing a void for conditions of high stress and an applied voltage of 0.2 V. This is explained in terms of the temperature distribution and weakening of Au as a function of temperature. The findings in this communication are important to the design of materials for electrical contacts because applied conditions may play a role in reversing relative hardness of the materials for conditions experienced during operation. (fast track communication)

Generalized irreversible heat-engine experiencing a complex heat-transfer law

International Nuclear Information System (INIS)

Chen Lingen; Li Jun; Sun Fengrui

2008-01-01

The fundamental optimal relation between optimal power-output and efficiency of a generalized irreversible Carnot heat-engine is derived based on a generalized heat-transfer law, including a generalized convective heat-transfer law and a generalized radiative heat-transfer law, q ∝ (ΔT n ) m . The generalized irreversible Carnot-engine model incorporates several internal and external irreversibilities, such as heat resistance, bypass heat-leak, friction, turbulence and other undesirable irreversibility factors. The added irreversibilities, besides heat resistance, are characterized by a constant parameter and a constant coefficient. The effects of heat-transfer laws and various loss terms are analyzed. The results obtained corroborate those in the literature

Distributed heat generation in a district heating system

OpenAIRE

Lennermo, Gunnar; Lauenberg, Patrick

2016-01-01

District heating (OH) systems need to be improved  regarding integration  of decentralised  heat generation. Micro production, prosumers and smart grids are terms becoming more and more common  in  connection  to  the  power  grid.  Concerning district  heating,  the  development  is slower, although improving. Today there are a number of such decentralised units for heat generation,  mainly  solar,  that have been partly evaluated.  Previous  studies  have shown  that there is a need to deve...

Spatial Heat Planning and Heat Demand Reductions in Buildings

DEFF Research Database (Denmark)

Nielsen, Steffen

2013-01-01

to an energy system based 100% on renewable energy is not just a fi-ne-tuning of the existing system, but is a fundamental change of the entire energy system. However, similar to the use of fossil fuels, biomass re-sources, which account of a large share of the renewable energy sources, are limited in relation...... long-term savings in investments in production capacity and fuel costs. Through a case study, the amount of these long-term sav-ings is compared to the costs of implementing heat savings. The case study shows that heat reductions of roughly 50% are feasible if the long-term costs are included. Savings...

Floquet prethermalization and regimes of heating in a periodically driven, interacting quantum system

Science.gov (United States)

Weidinger, Simon; Knap, Michael

We study the regimes of heating in the periodically driven O (N) -model, which represents a generic model for interacting quantum many-body systems. By computing the absorbed energy with a non-equilibrium Keldysh Green's function approach, we establish three dynamical regimes: at short times a single-particle dominated regime, at intermediate times a stable Floquet prethermal regime in which the system ceases to absorb, and at parametrically late times a thermalizing regime. Our simulations suggest that in the thermalizing regime the absorbed energy grows algebraically in time with an the exponent that approaches the universal value of 1 / 2 , and is thus significantly slower than linear Joule heating. Our results demonstrate the parametric stability of prethermal states in a generic many-body system driven at frequencies that are comparable to its microscopic scales. This paves the way for realizing exotic quantum phases, such as time crystals or interacting topological phases, in the prethermal regime of interacting Floquet systems. We acknowledge support from the Technical University of Munich - Institute for Advanced Study, funded by the German Excellence Initiative and the European Union FP7 under Grant agreement 291763, and from the DFG Grant No. KN 1254/1-1.

Long-term modelling of Carbon Capture and Storage, Nuclear Fusion, and large-scale District Heating

DEFF Research Database (Denmark)

Grohnheit, Poul Erik; Korsholm, Søren Bang; Lüthje, Mikael

2011-01-01

before 2050. The modelling tools developed by the International Energy Agency (IEA) Implementing Agreement ETSAP include both multi-regional global and long-term energy models till 2100, as well as national or regional models with shorter time horizons. Examples are the EFDA-TIMES model, focusing...... on nuclear fusion and the Pan European TIMES model, respectively. In the next decades CCS can be a driver for the development and expansion of large-scale district heating systems, which are currently widespread in Europe, Korea and China, and with large potentials in North America. If fusion will replace...... fossil fuel power plants with CCS in the second half of the century, the same infrastructure for heat distribution can be used which will support the penetration of both technologies. This paper will address the issue of infrastructure development and the use of CCS and fusion technologies using...

Renewable heat: Waste heat, an emerging sector full of resources. An eco-district fed by the heat from a data center; Integrating objectives matching the ambitions, clear and on the long term; High-energy wastes in Brittany: Brest is securing its heat network with multiple energies

International Nuclear Information System (INIS)

Richard, Aude

2017-01-01

This file on renewable heat contains four articles which themes are: waste heat (from incineration plants or industrial sites) is an emerging sector full of resources, which benefits now of a financial subsidy from ADEME, the French organization for energy and environment; an example is given with Chamtor, a highly energy-consuming cereal transformer. The second article presents an urban eco-district in Paris that is fed by the heat issued by a data center. The third article (Integrating objectives matching the ambitions, clear and on the long term) presents some recommendations from the French Renewable Energy Association (SER) towards a better energy valorization of residual wastes. The fourth article presents two examples of energy valorization of wastes in Brittany, one with the valorization of high-energy solid wastes for supplying heat to a milk farm and greenhouses, the other one concerns the development of a heat network supplied by an incineration plant, with a mix of energy sources such as wastes, wood and gas, and a special juridical scheme

Design of closed-loop nitrogen Joule-Thomson refrigeration cycle for 67 K with sub-atmospheric device

Energy Technology Data Exchange (ETDEWEB)

Lee, C.; Lee, J.; Jeong, S. [Cryogenic Engineering Laboratory, Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

2013-05-15

Closed-loop J-T (Joule-Thomson) refrigeration cycle is advantageous compared to common open loop N{sub 2} decompression system in terms of nitrogen consumption. In this study, two closed-loop pure N{sub 2} J-T refrigeration systems with sub-atmospheric device for cooling High Temperature Superconductor (HTS) power cable are investigated. J-T cooling systems include 2-stage compressor, 2-stage precooling cycle, J-T valve and a cold compressor or an auxiliary vacuum pump at the room temperature. The cold compressor and the vacuum pump are installed after the J-T valve to create sub-atmospheric condition. The temperature of 67 K is possible by lowering the pressure up to 24 kPa at the cold part. The optimized hydrocarbon mixed refrigerant (MR) J-T system is applied for precooling stage. The cold head of precooling MR J-T have the temperature from 120 K to 150 K. The various characteristics of cold compressor are investigated and applied to design parameter of the cold compressor. The Carnot efficiency of cold compressor system is calculated as 16.7% and that of vacuum pump system as 16.4%. The efficiency difference between the cold compressor system and the vacuum pump system is due to difference of enthalpy change at cryogenic temperature, enthalpy change at room temperature and different work load at the pre-cooling cycle. The efficiency of neon-nitrogen MR J-T system is also presented for comparison with the sub-atmospheric devices. These systems have several pros and cons in comparison to typical MR J-T systems such as vacuum line maintainability, system's COP and etc. In this paper, the detailed design of the subcooled N{sub 2} J-T systems are examined and some practical issues of the sub-atmospheric devices are discussed.

Analytical solution for Joule-Thomson cooling during CO2 geo-sequestration in depleted oil and gas reservoirs

Energy Technology Data Exchange (ETDEWEB)

Mathias, S.A.; Gluyas, J.G.; Oldenburg, C.M.; Tsang, C.-F.

2010-05-21

Mathematical tools are needed to screen out sites where Joule-Thomson cooling is a prohibitive factor for CO{sub 2} geo-sequestration and to design approaches to mitigate the effect. In this paper, a simple analytical solution is developed by invoking steady-state flow and constant thermophysical properties. The analytical solution allows fast evaluation of spatiotemporal temperature fields, resulting from constant-rate CO{sub 2} injection. The applicability of the analytical solution is demonstrated by comparison with non-isothermal simulation results from the reservoir simulator TOUGH2. Analysis confirms that for an injection rate of 3 kg s{sup -1} (0.1 MT yr{sup -1}) into moderately warm (>40 C) and permeable formations (>10{sup -14} m{sup 2} (10 mD)), JTC is unlikely to be a problem for initial reservoir pressures as low as 2 MPa (290 psi).

effect of brinkman number and magnetic field on laminar convection ...

African Journals Online (AJOL)

Joseph et al.

Science World Journal Vol 12(No 4) 2017 ... Joule heating on the fully developed MHD flow with heat transfer .... fluid in a vertical parallel – plate with effect of magnetic field and ..... Plates Channel, Proceedings of the 2013 International.

Induction Heating on Dynamic Tensile Tests in CEA Saclay

International Nuclear Information System (INIS)

Averty, X.; Yvon, P.; Duguay, C.; Pizzanelli, J. P.; Basini, V.

2001-01-01

The LCMI (Laboratory for characterization of irradiated materials), located in CEA from Saclay, is in charge of the mechanical tests on irradiated materials. The dynamic tensile testing machine, in a hot cell equipped with two remote handling, has been first improved in 1995, to fulfill the French safety programs on Reactivity Initiated Accident (RIA). One objective of this machine is to obtain mechanical property data on current Zircaloy cladding types needed to quality the cladding's response under RIA or LOCA transient loading and thermal conditions. For the RIA, this means testing at strain rates up to 5 s' and heating rates up to 200 degree centigree-s''-1, while for Loss of Coolant Accidents (LOCA) testing at strain rates of 10''-3 s''-1 and heating rates of 20 degree centigree s''-1 would be appropriate. The tensile samples are machined with a spark erosion machine, directly from pieces of cladding previously de fueled. Two kinds of samples can be machined in the cladding. Axial samples in order to test axial mechanical characteristics Ring samples in order to test transverse mechanical characteristics, more representative of RIA conditions. On one hand, the axial tensile tests were performed using the Joule effect, and heating rates up to about 500 degree centigree .s''-1 were obtained. This enabled us to perform the axial tests in a satisfactory manner. On the other hand, the tensile ring were first performed in a vertical furnace with a heating rate about 0.2 degree centigree.s''-1 and a thermal stability about 1 degree centigree. For temperatures above 480 degree centigree, the mechanical characteristics showed a sharp drop which could be attributed to irradiation defect annealing. Therefore we have recently developed an induction heating system to reach heating rates high enough (200 degree centigree.s''-1) to prevent any significant annealing before performing the ring tensile tests. To apply a uniaxial tangential tension, two matching half

Effect of short-term heat acclimation training on kinetics of lactate removal following maximal exercise.

Science.gov (United States)

Dileo, Tsavis D; Powell, Jeffrey B; Kang, Hyoung K; Roberge, Raymond J; Coca, Aitor; Kim, Jung-Hyun

2016-01-01

Heat acclimation (HA) evokes numerous physiological adaptations, improves heat tolerance and has also been shown to enhance lactate (LA) responses during exercise, similar to that seen with endurance training. The purpose of this study was to examine whether HA improves the body's ability to remove LA during recovery following maximal exercise. Ten healthy men completed two trials of maximal treadmill exercise (pre- and post-HA) separated by 5 days of HA. Each day of HA consisted of two 45 minute periods of cycling at ~50% VO2max separated by a 15min rest period in an environmental chamber (T(db) 45° C, RH 20%). In pre-/post-HA trials, venous blood was collected during 60 minutes of recovery to determine LA concentrations and removal kinetics (A2: amplitude and y2: velocity constant) using bi-exponential curve fitting. Physiological adaptation to heat was significantly developed during HA, as evidenced by end-exercise T(re) (DAY1 vs. 5) (38.89±0.56 vs. 38.66±0.44° C), T(sk) (38.07±0.51 vs. 37.66±0.48° C), HR (175.0±9.9 vs. 165.0±18.5 beats·min(-1)), and sweat rate (1.24 ±.26 vs. 1.47 ±0.27 L·min(-1)) (PLA concentrations (LA(0min): 8.78±1.08 vs. 8.69±1.23; LA(peak): 10.97±1.77 vs. 10.95±1.46; and La(60min); 2.88±0.82 vs. 2.96±0.93 mmol·L(-1)) or removal kinetics (A2: -13.05±7.05 vs -15.59±7.90 mmol.L(-1) and y2: 0.02±0.01 vs. 0.03±.01 min(-1)). The present study concluded that, while effective in inducing thermo-physiological adaptations to heat stress, short-term HA does not improve the body's ability to remove LA following maximal exercise. Therefore, athletes and workers seeking faster LA recovery from intense physical activity may not benefit from short-term HA.

A Numerical Study on Phonon Spectral Contributions to Thermal Conduction in Silicon-on-Insulator Transistor Using Electron-Phonon Interaction Model

Energy Technology Data Exchange (ETDEWEB)

Kang, Hyung-sun; Koh, Young Ha; Jin, Jae Sik [Chosun College of Science and Technology, Gwangju (Korea, Republic of)

2017-06-15

The aim of this study is to understand the phonon transfer characteristics of a silicon thin film transistor. For this purpose, the Joule heating mechanism was considered through the electron-phonon interaction model whose validation has been done. The phonon transport characteristics were investigated in terms of phonon mean free path for the variations in the device power and silicon layer thickness from 41 nm to 177 nm. The results may be used for developing the thermal design strategy for achieving reliability and efficiency of the silicon-on-insulator (SOI) transistor, further, they will increase the understanding of heat conduction in SOI systems, which are very important in the semiconductor industry and the nano-fabrication technology.

Online short-term heat load forecasting for single family houses

DEFF Research Database (Denmark)

Bacher, Peder; Madsen, Henrik; Nielsen, Henrik Aalborg

2013-01-01

. Every hour the hourly heat load for each house the following two days is forecasted. The forecast models are adaptive linear time-series models and the climate inputs used are: ambient temperature, global radiation, and wind speed. A computationally efficient recursive least squares scheme is used......This paper presents a method for forecasting the load for heating in a single-family house. Both space and hot tap water heating are forecasted. The forecasting model is built using data from sixteen houses in Sønderborg, Denmark, combined with local climate measurements and weather forecasts...... variations in the heat load signal (predominant only for some houses), peaks presumably from showers, shifts in resident behavior, and uncertainty of the weather forecasts for longer horizons, especially for the solar radiation....

Short-term heat acclimation improves the determinants of endurance performance and 5-km running performance in the heat.

Science.gov (United States)

James, Carl A; Richardson, Alan J; Watt, Peter W; Willmott, Ashley G B; Gibson, Oliver R; Maxwell, Neil S

2017-03-01

This study investigated the effect of 5 days of controlled short-term heat acclimation (STHA) on the determinants of endurance performance and 5-km performance in runners, relative to the impairment afforded by moderate heat stress. A control group (CON), matched for total work and power output (2.7 W·kg -1 ), differentiated thermal and exercise contributions of STHA on exercise performance. Seventeen participants (10 STHA, 7 CON) completed graded exercise tests (GXTs) in cool (13 °C, 50% relative humidity (RH), pre-training) and hot conditions (32 °C, 60% RH, pre- and post-training), as well as 5-km time trials (TTs) in the heat, pre- and post-training. STHA reduced resting (p = 0.01) and exercising (p = 0.04) core temperature alongside a smaller change in thermal sensation (p = 0.04). Both groups improved the lactate threshold (LT, p = 0.021), lactate turnpoint (LTP, p = 0.005) and velocity at maximal oxygen consumption (vV̇O 2max ; p = 0.031) similarly. Statistical differences between training methods were observed in TT performance (STHA, -6.2(5.5)%; CON, -0.6(1.7)%, p = 0.029) and total running time during the GXT (STHA, +20.8(12.7)%; CON, +9.8(1.2)%, p = 0.006). There were large mean differences in change in maximal oxygen consumption between STHA +4.0(2.2) mL·kg -1 ·min -1 (7.3(4.0)%) and CON +1.9(3.7) mL·kg -1 ·min -1 (3.8(7.2)%). Running economy (RE) deteriorated following both training programmes (p = 0.008). Similarly, RE was impaired in the cool GXT, relative to the hot GXT (p = 0.004). STHA improved endurance running performance in comparison with work-matched normothermic training, despite equality of adaptation for typical determinants of performance (LT, LTP, vV̇O 2max ). Accordingly, these data highlight the ergogenic effect of STHA, potentially via greater improvements in maximal oxygen consumption and specific thermoregulatory and associated thermal perception adaptations absent in normothermic training.

Comparison and analysis of the efficiency of heat exchange of copper rod and copper wires current lead

International Nuclear Information System (INIS)

Fang, J.; Yu, T.; Li, Z.M.; Wei, B.; Qiu, M.; Zhang, H.J.

2013-01-01

Highlights: •An optimized design of HTS binary current leads is proposed. •Temperature distributions of two different current leads are calculated. •Experiments are done to certify the calculated temperature distributions. •The experiments proved that the copper wires increase security margins. -- Abstract: Current leads are the key components that connect the low-temperature and high temperature parts of the cryogenic system. Owing to the wide range of temperatures, current leads are the main sources of heat leakage. Since the HTS tapes have no resistance and the generated Joule heat is almost zero, HTS binary current leads can reduce heat leakage compared to the conventional leads. However, heat will still be generated and conducted to the cryogenic system through the copper parts of the HTS current leads. In order to reduce heat leakage by the copper parts of the HTS current leads, this paper presents an optimized design of the copper parts of HTS binary current leads. Inside the leads, the copper wires were applied as an alternative to the copper rod without changing the overall dimensions. Firstly, the differential function of heat transfer was derived. By solving the function, the optimum number of the copper wires and the temperature distribution of two different current leads were gotten. Then the experiment of the temperature distribution was done, and the experimental results were basically the same with the calculative results. The simulation and related experiments proved that the copper wire can increase security margins and reduce maximum temperatures under the same shunt current

Comparison and analysis of the efficiency of heat exchange of copper rod and copper wires current lead

Energy Technology Data Exchange (ETDEWEB)

Fang, J., E-mail: fangseer@sina.com [School of Electrical Engineering, Beijing Jiaotong University, Beijing (China); Yu, T. [School of Electrical Engineering, Beijing Jiaotong University, Beijing (China); Li, Z.M.; Wei, B.; Qiu, M.; Zhang, H.J. [China Electric Power Research Institute, Haidian District, Beijing (China)

2013-11-15

Highlights: •An optimized design of HTS binary current leads is proposed. •Temperature distributions of two different current leads are calculated. •Experiments are done to certify the calculated temperature distributions. •The experiments proved that the copper wires increase security margins. -- Abstract: Current leads are the key components that connect the low-temperature and high temperature parts of the cryogenic system. Owing to the wide range of temperatures, current leads are the main sources of heat leakage. Since the HTS tapes have no resistance and the generated Joule heat is almost zero, HTS binary current leads can reduce heat leakage compared to the conventional leads. However, heat will still be generated and conducted to the cryogenic system through the copper parts of the HTS current leads. In order to reduce heat leakage by the copper parts of the HTS current leads, this paper presents an optimized design of the copper parts of HTS binary current leads. Inside the leads, the copper wires were applied as an alternative to the copper rod without changing the overall dimensions. Firstly, the differential function of heat transfer was derived. By solving the function, the optimum number of the copper wires and the temperature distribution of two different current leads were gotten. Then the experiment of the temperature distribution was done, and the experimental results were basically the same with the calculative results. The simulation and related experiments proved that the copper wire can increase security margins and reduce maximum temperatures under the same shunt current.

Preliminary Studies on Aerodynamic Control with Direct Current Discharge at Hypersonic Speed

Science.gov (United States)

Watanabe, Yasumasa; Takama, Yoshiki; Imamura, Osamu; Watanuki, Tadaharu; Suzuki, Kojiro

A new idea of an aerodynamic control device for hypersonic vehicles using plasma discharges is presented. The effect of DC plasma discharge on a hypersonic flow is examined with both experiments and CFD analyses. It is revealed that the surface pressure upstream of plasma area significantly increases, which would be preferable in realizing a new aerodynamic control devices. Such pressure rise is also observed in the result of analyses of the Navier-Stokes equations with energy addition that simulates the Joule heating of a plasma discharge. It is revealed that the pressure rise due to the existence of the plasma discharge can be qualitatively explained as an effect of Joule heating.

Multiphysics Modeling for Dimensional Analysis of a Self-Heated Molten Regolith Electrolysis Reactor for Oxygen and Metals Production on the Moon and Mars

Science.gov (United States)

Dominguez, Jesus A.; Sibille, Laurent

2010-01-01

The technology of direct electrolysis of molten lunar regolith to produce oxygen and molten metal alloys has progressed greatly in the last few years. The development of long-lasting inert anodes and cathode designs as well as techniques for the removal of molten products from the reactor has been demonstrated. The containment of chemically aggressive oxide and metal melts is very difficult at the operating temperatures ca 1600 C. Containing the molten oxides in a regolith shell can solve this technical issue and can be achieved by designing a self-heating reactor in which the electrolytic currents generate enough Joule heat to create a molten bath. In a first phase, a thermal analysis model was built to study the formation of a melt of lunar basaltic regolith irradiated by a focused solar beam This mode of heating was selected because it relies on radiative heat transfer, which is the dominant mode of transfer of energy in melts at 1600 C. Knowing and setting the Gaussian-type heat flux from the concentrated solar beam and the phase and temperature dependent thermal properties, the model predicts the dimensions and temperature profile of the melt. A validation of the model is presented in this paper through the experimental formation of a spherical cap melt realized by others. The Orbitec/PSI experimental setup uses an 3.6-cm diameter concentrated solar beam to create a hemispheric melt in a bed of lunar regolith simulant contained in a large pot. Upon cooling, the dimensions of the vitrified melt are measured to validate the thermal model. In a second phase, the model is augmented by multiphysics components to compute the passage of electrical currents between electrodes inserted in the molten regolith. The current through the melt generates Joule heating due to the high resistivity of the medium and this energy is transferred into the melt by conduction, convection and primarily by radiation. The model faces challenges in two major areas, the change of phase as

Operation experiences of the JT-60 first walls during high-power additional heating experiments

International Nuclear Information System (INIS)

Takatsu, H.; Ando, T.; Yamamoto, M.; Arai, T.; Kodama, K.; Suzuki, M.; Shimizu, M.

1989-01-01

JT-60 started its operation in May 1985 with TiC-coated molybdenum or Inconel 625 first walls. They provided very clean surfaces as well as superior plasma characteristics during Joule heating discharges. Though 20 μm-thick TiC coatings showed good adhesion characteristics, melting of the TiC coating and also the molybdenum or Inconel 625 substrate was observed at some specific spots, and an influx of heavy metals to the main plasma was inevitable during discharges. Initial results of the additional heating experiments showed degrading effects of locally melted TiC-coated molybdenum or Inconel 625 on plasma operation. Therefore, about a half of the TiC-coated first walls were removed and new graphite first walls were installed during the venting period from April to May 1987. The start-up of the discharge conditioning after installation of a significant number of graphite tiles was very rapid. Flexibility in plasma operation was increased, and JT-60 extended the operation region beyond its original specifications. The graphite first walls of the main chamber performed admirably and maintained their integrity under the conditions of plasma current and additional heating power up to 3.2 MA and 30 MW, respectively. On the other hand, the number of damaged divertor plates was much larger than that expected. The reason of unexpected failure is now under examination. (orig.)

Heat Roadmap Europe

DEFF Research Database (Denmark)

Hansen, Kenneth; Connolly, David; Lund, Henrik

2015-01-01

The cost of heat savings in buildings increase as more heat savings are achieved due to the state of the building stock and hence, alternatives other than savings typically become more economically feasible at a certain level of heat reductions. It is important to identify when the cost of heat...... savings become more expensive than the cost of sustainable heat supply, so society does not overinvest in heat saving measures. This study first investigates the heat saving potentials for different countries in Europe, along with their associated costs, followed by a comparison with alternative ways...... of supplying sustainable heating. Different heat production options are included in terms of individual and community heating systems. Furthermore, the levelised cost of supplying sustainable heat is estimated for both a single technology and from an energy system perspective. The results are analysed...

Evaluating work/recovery schedules in terms of whole body heat storage

Energy Technology Data Exchange (ETDEWEB)

Hardcastle, S.G. [Natural Resources Canada, Sudbury, ON (Canada). CANMET Mining and Mineral Sciences Laboratories; Stapleton, J.M.; Kenny, G.P. [Ottawa Univ., Ottawa, ON (Canada). School of Human Kinetics, Human and Environmental Physiology Research Unit; Allen, C. [Vale Inco, Copper Cliff, ON (Canada)

2010-07-01

This paper reported on heat stress related research aimed at better managing the heat exposure of underground miners. The potential for underground miners to experience heat stress or strain is increasing due to greater mining depth; mechanization, and a trend towards larger diesel equipment; an aging workforce; an increasing amount of personal protective equipment worn to prevent injuries (that has led to most of the miner's body being covered) and increases in the surface climate that are superimposed through the underground workplace. This paper focused on research involving metabolic heat storage and the possibility of heat strain from elevated core temperatures. It targeted work/recovery cycles and the recovery strategies between work bouts. The first study examined the cumulative change in body heat content for a moderate metabolic rate and increasing the recovery allocation as per the TLV screening criteria to offset an increase in the wet bulb globe temperature (WBGT). The second study examined strategies that could be used between work bouts and how they affect the thermoregulatory system, heat generation or losses and net cumulative heat storage. The calorimeter based work suggested that a miner's clothing may be improved to promote evaporative cooling, and that work recovery regimes could be modified to maximize recovery. 10 refs., 1 tab., 6 figs.

Derivation of effectiveness-NTU method for heat exchangers with heat leak; TOPICAL

International Nuclear Information System (INIS)

William M. Soyars

2001-01-01

A powerful and useful method for heat exchanger analysis is the effectiveness-NTU method. The equations for this technique presented in textbooks, however, are limited to the case where all of the heat transfer occurs between the two fluid streams. In an application of interest to us, cryogenic heat exchangers, we wish to consider a heat leak term. Thus, we have derived equations for the(var e psilon)-NTU method with heat leak involved. The cases to be studied include evaporators, condensers, and counter-flow, with heat leak both in and out

Application of heat pipes in nuclear reactors for passive heat removal

Energy Technology Data Exchange (ETDEWEB)

Haque, Z.; Yetisir, M., E-mail: haquez@aecl.ca [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada)

2013-07-01

This paper introduces a number of potential heat pipe applications in passive (i.e., not requiring external power) nuclear reactor heat removal. Heat pipes are particularly suitable for small reactors as the demand for heat removal is significantly less than commercial nuclear power plants, and passive and reliable heat removal is required. The use of heat pipes has been proposed in many small reactor designs for passive heat removal from the reactor core. This paper presents the application of heat pipes in AECL's Nuclear Battery design, a small reactor concept developed by AECL. Other potential applications of heat pipes include transferring excess heat from containment to the atmosphere by integrating low-temperature heat pipes into the containment building (to ensure long-term cooling following a station blackout), and passively cooling spent fuel bays. (author)

Short-term heat load forecasting for single family houses

DEFF Research Database (Denmark)

Bacher, Peder; Madsen, Henrik; Nielsen, Henrik Aalborg

2013-01-01

This paper presents a method for forecasting the load for space heating in a single-family house. The forecasting model is built using data from sixteen houses located in Sønderborg, Denmark, combined with local climate measurements and weather forecasts. Every hour the hourly heat load for each...... house the following two days is forecasted. The forecast models are adaptive linear time-series models and the climate inputs used are: ambient temperature, global radiation and wind speed. A computationally efficient recursive least squares scheme is used. The models are optimized to fit the individual...... noise and that practically all correlation to the climate variables are removed. Furthermore, the results show that the forecasting errors mainly are related to: unpredictable high frequency variations in the heat load signal (predominant only for some houses), shifts in resident behavior patterns...

A short-term supranutritional vitamin E supplementation alleviated respiratory alkalosis but did not reduce oxidative stress in heat stressed pigs

Directory of Open Access Journals (Sweden)

Fan Liu

2018-02-01

Full Text Available Objective Heat stress (HS triggers oxidative stress and respiratory alkalosis in pigs. The objective of this experiment was to study whether a short-term supranutritional amount of dietary vitamin E (VE can mitigate oxidative stress and respiratory alkalosis in heat-stressed pigs. Methods A total of 24 pigs were given either a control diet (17 IU/kg VE or a high VE (200 IU/kg VE; HiVE diet for 14 d, then exposed to thermoneutral (TN; 20°C, 45% humidity or HS (35°C, 35% to 45% humidity, 8 h daily conditions for 7 d. Respiration rate and rectal temperature were measured three times daily during the thermal exposure. Blood gas variables and oxidative stress markers were studied in blood samples collected on d 7. Results Although HiVE diet did not affect the elevated rectal temperature or respiration rate observed during HS, it alleviated (all p<0.05 for diet×temperature the loss of blood CO2 partial pressure and bicarbonate, as well as the increase in blood pH in the heat-stressed pigs. The HS reduced (p = 0.003 plasma biological antioxidant potential (BAP and tended to increase (p = 0.067 advanced oxidized protein products (AOPP in the heat-stressed pigs, suggesting HS triggers oxidative stress. The HiVE diet did not affect plasma BAP or AOPP. Only under TN conditions the HiVE diet reduced the plasma reactive oxygen metabolites (p<0.05 for diet× temperature. Conclusion A short-term supplementation with 200 IU/kg VE partially alleviated respiratory alkalosis but did not reduce oxidative stress in heat-stressed pigs.

Steady-state analytical model of suspended p-type 3C-SiC bridges under consideration of Joule heating

Science.gov (United States)

Balakrishnan, Vivekananthan; Dinh, Toan; Phan, Hoang-Phuong; Kozeki, Takahiro; Namazu, Takahiro; Viet Dao, Dzung; Nguyen, Nam-Trung

2017-07-01

This paper reports an analytical model and its validation for a released microscale heater made of 3C-SiC thin films. A model for the equivalent electrical and thermal parameters was developed for the two-layer multi-segment heat and electric conduction. The model is based on a 1D energy equation, which considers the temperature-dependent resistivity and allows for the prediction of voltage-current and power-current characteristics of the microheater. The steady-state analytical model was validated by experimental characterization. The results, in particular the nonlinearity caused by temperature dependency, are in good agreement. The low power consumption of the order of 0.18 mW at approximately 310 K indicates the potential use of the structure as thermal sensors in portable applications.

CRBRP decay heat removal systems

International Nuclear Information System (INIS)

Hottel, R.E.; Louison, R.; Boardman, C.E.; Kiley, M.J.

1977-01-01

The Decay Heat Removal Systems for the Clinch River Breeder Reactor Plant (CRBRP) are designed to adequately remove sensible and decay heat from the reactor following normal shutdown, operational occurrences, and postulated accidents on both a short term and a long term basis. The Decay Heat Removal Systems are composed of the Main Heat Transport System, the Main Condenser and Feedwater System, the Steam Generator Auxiliary Heat Removal System (SGAHRS), and the Direct Heat Removal Service (DHRS). The overall design of the CRBRP Decay Heat Removal Systems and the operation under normal and off-normal conditions is examined. The redundancies of the system design, such as the four decay heat removal paths, the emergency diesel power supplies, and the auxiliary feedwater pumps, and the diversities of the design such as forced circulation/natural circulation and AC Power/DC Power are presented. In addition to overall design and system capabilities, the detailed designs for the Protected Air Cooled Condensers (PACC) and the Air Blast Heat Exchangers (ABHX) are presented

Assessment of the Long Term Trends in Extreme Heat Events and the Associated Health Impacts in the United States

Science.gov (United States)

Bell, J.; Rennie, J.; Kunkel, K.; Herring, S.; Cullen, H. M.

2017-12-01

Land surface air temperature products have been essential for monitoring the evolution of the climate system. Before a temperature dataset is included in such reports, it is important that non-climatic influences be removed or changed so the dataset is considered homogenous. These inhomogeneities include changes in station location, instrumentation and observing practices. While many homogenized products exist on the monthly time scale, few daily products exist, due to the complication of removing breakpoints that are truly inhomogeneous rather than solely by chance (for example, sharp changes due to synoptic conditions). Recently, a sub monthly homogenized dataset has been developed using data and software provided by NOAA's National Centers for Environmental Information (NCEI). Homogeneous daily data are useful for identification and attribution of extreme heat events over a period of time. Projections of increasing temperatures are expected to result in corresponding increases in the frequency, duration, and intensity of extreme heat events. It is also established that extreme heat events can have significant public health impacts, including short-term increases in mortality and morbidity. In addition, it can exacerbate chronic health conditions in vulnerable populations, including renal and cardiovascular issues. To understand how heat events impact a specific population, it will be important to connect observations on the duration and intensity of extreme heat events with health impacts data including insurance claims and hospital admissions data. This presentation will explain the methodology to identify extreme heat events, provide a climatology of heat event onset, length and severity, and explore a case study of an anomalous heat event with available health data.

Gasification technologies for heat and power from biomass

NARCIS (Netherlands)

Beenackers, AACM; Maniatis, K; Kaltschmitt, M; Bridgwater, AV

1997-01-01

A critical review is presented of biomass gasifier systems presently commercially available or under development. Advantages and possible problem areas are discussed in relation to particular applications. Both large and small scale technologies are reviewed. Catalysed by the EC JOULE and AIR

Modelling of the draining of a molten glass heated by induction

International Nuclear Information System (INIS)

Lima-Da-Silva, Marcio

2014-01-01

This thesis is part of the development of a new technology of oxides melting in a furnace heated by induction. The technology studied involves strong interactions between electromagnetic, thermal and hydrodynamic phenomena in a flow with physical properties strongly dependents of the temperature. The aim of the thesis is the modelling of the process by coupling closely the Joule heating, the mechanical stirring and the draining of the furnace. The modeling of the time evolution of the interface between glass and air during the emptying of the cold crucible was performed. Regarding the methodology, we chose to combine two scientific codes: Flux for the electromagnetic calculation and Fluent for thermal-hydraulics. The evolution of the free surface was treated by the multiphasic method 'Volume-Of-Fluid - VOF' and the mechanical stirring by the 'Moving Reference Frame' and the 'Sliding Mesh'. First of all, we considered the draining of a tank filled with a silicon oil of high-viscosity without mechanical stirring. This initial model took into account studies of hydraulic similarity between the silicon oil and the glass. Then we superimposed the forced flow creates by the mechanical stirrer, the thermal and the electromagnetic phenomena in order to model the flow of the molten glass. The final model can provide various parameters, including the time needed to drain the furnace, the heat transfer flux and the time evolution of the mass flow rate and of the temperature inside de furnace. (author) [fr

Effects of Short-Term Thermal Alteration on Organic Matter in Experimentally-Heated Tagish Lake Observed by Raman Spectroscopy

Science.gov (United States)

Chan, Q. H. S.; Nakato, A.; Zolensky, M. E.; Nakamura, T.; Kebukawa, Y.; Maisano, J.; Colbert, M.; Martinez, J. E.

2017-01-01

Carbonaceous chondrites exhibit a wide range of aqueous and thermal alteration characteristics, while some are known to demonstrate mineralogical and petrologic evidence of having been thermally metamorphosed after aqueous alteration. This group of meteorites are commonly referred as thermally met-amorphosed carbonaceous chondrites (TMCCs), and their reflectance spectra show resemblances to that of C-type asteroids which typically have low albedos. This suggests that the surfaces of the C-type asteroids are also composed of both hydrous and dehydrated minerals, and thus TMCCs are among the best samples that can be studied in laboratory to reveal the true nature of the C-type asteroids. Although TMCCs are usually meteorites that were previously categorized as CI and CM chondrites, they are not strictly CI/CM because they exhibit isotopic and petrographic characteristics that significantly deviate from typical CI/CM. More appropriately, they are called CI-like and/or CM-like chondrites. Typical examples of TMCCs include the C2-ung/CM2TIV Belgica (B)-7904 and Yamato (Y) 86720. Thermal alteration is virtually complete in these meteorites and thus they are considered typical end-members of TMCCs exhibiting complete dehydration of matrix phyllosilicates. The estimated heating conditions are 10 to 103 days at 700 C to 1 to 100 hours at 890 C, i.e. short-term heating induced by impact and/or solar radiation. While the petrology and chemistry of TMCCs have only recently been extensively characterized, we have just begun to study in detail their organic contents. In order to understand how short-term heating affects the maturity of insoluble organic matter (IOM) in hydrous chondrites, we investigated experimentally-heated Tagish Lake meteorite using Raman spectroscopy, as the chemical and bulk oxygen isotopic compositions of the matrix of the carbonate (CO3)-poor lithology of the Tagish Lake (hereafter Tag) meteorite bears similarities to the TMCCs.

Refrigeration Playbook. Heat Reclaim; Optimizing Heat Rejection and Refrigeration Heat Reclaim for Supermarket Energy Conservation

Energy Technology Data Exchange (ETDEWEB)

Reis, Chuck [CTA Architects Engineers, Boise, ID (United States); Nelson, Eric [CTA Architects Engineers, Boise, ID (United States); Armer, James [CTA Architects Engineers, Boise, ID (United States); Johnson, Tim [CTA Architects Engineers, Boise, ID (United States); Hirsch, Adam [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Doebber, Ian [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

2015-03-01

The purpose of this playbook and accompanying spreadsheets is to generalize the detailed CBP analysis and to put tools in the hands of experienced refrigeration designers to evaluate multiple applications of refrigeration waste heat reclaim across the United States. Supermarkets with large portfolios of similar buildings can use these tools to assess the impact of large-scale implementation of heat reclaim systems. In addition, the playbook provides best practices for implementing heat reclaim systems to achieve the best long-term performance possible. It includes guidance on operations and maintenance as well as measurement and verification.

Thermodynamics and Mechanical Equivalent of Heat

Science.gov (United States)

Kipnis, Nahum

2014-01-01

This paper is the first part of a three-part project "How the principle of energy conservation evolved between 1842 and 1870: the view of a participant". This paper aims at showing how the new ideas of Mayer and Joule were received, what constituted the new theory in the period under study, and how it was supported experimentally. A…

Modelling of the Peltier effect in magnetic multilayers

NARCIS (Netherlands)

Juarez-Acosta, I.; Olivares-Robles, M.A.; Bosu, S.; Sakuraba, Y.; Kubota, T.; Takahashi, S.; Takanashi, K.; Bauer, G.E.W.

2016-01-01

We model the charge, spin, and heat currents in ferromagnetic metal?normal metal?normal metal trilayer structures in the two current model, taking into account bulk and interface thermoelectric properties as well as Joule heating. The results include the temperature distribution as well as

Ammonia and Carbon Dioxide Heat Pumps for Heat Recovery in Industry

DEFF Research Database (Denmark)

Brix, Wiebke; Christensen, Stefan W.; Markussen, Michael M.

2012-01-01

. Calculations of cycle performances are performed using a reference cycle for both ammonia and carbon dioxide as refrigerant. For each cycle a thorough sensitivity analysis reveals that the forward and return temperatures of the heat sink (condenser or gas cooler) of the heat pump are most important......This paper presents a generic, numerical study of high temperature heat pumps for waste heat recovery in industry using ammonia and carbon dioxide as refrigerants. A study of compressors available on the market today, gives a possible application range of the heat pumps in terms of temperatures...... conclusion is that ammonia heat pumps are best at heat sink inlet temperatures above 28°C and CO2 is best below 24°C, independent of other parameters....

A Reconsideration of the Link between the Energetics of Water and of ATP Hydrolysis Energy in the Power Strokes of Molecular Motors in Protein Structures

Directory of Open Access Journals (Sweden)

Wilfred F. Widdas

2008-09-01

Full Text Available Mechanical energy from oxygen metabolism by mammalian tissues has been studied since 1837. The production of heat by mechanical work was studied by Fick in about 1860. Prior to Fick’s work, energetics were revised by Joule’s experiments which founded the First Law of Thermodynamics. Fenn in 1923/24 found that frog muscle contractions generated extra heat proportional to the amount of work done in shortening the muscle. This was fully consistent with the Joule, Helmholtz concept used for the First Law of Thermodynamics. The link between the energetics of water and ATP hydrolysis in molecular motors is recommended for reconsideration.

On Heat Transfer through a Solid Slab Heated Uniformly and Periodically: Determination of Thermal Properties

Science.gov (United States)

Rojas-Trigos, J. B.; Bermejo-Arenas, J. A.; Marin, E.

2012-01-01

In this paper, some heat transfer characteristics through a sample that is uniformly heated on one of its surfaces by a power density modulated by a periodical square wave are discussed. The solution of this problem has two contributions, comprising a transient term and an oscillatory term, superposed to it. The analytical solution is compared to…

Equatorial heat accumulation as a long-term trigger of permanent Antarctic ice sheets during the Cenozoic.

Science.gov (United States)

Tremblin, Maxime; Hermoso, Michaël; Minoletti, Fabrice

2016-10-18

Growth of the first permanent Antarctic ice sheets at the Eocene-Oligocene Transition (EOT), ∼33.7 million years ago, indicates a major climate shift within long-term Cenozoic cooling. The driving mechanisms that set the stage for this glaciation event are not well constrained, however, owing to large uncertainties in temperature reconstructions during the Eocene, especially at lower latitudes. To address this deficiency, we used recent developments in coccolith biogeochemistry to reconstruct equatorial Atlantic sea surface temperature (SST) and atmospheric pCO 2 values from pelagic sequences preceding and spanning the EOT. We found significantly more variability in equatorial SSTs than previously reported, with pronounced cooling from the Early to Middle Eocene and subsequent warming during the Late Eocene. Thus, we show that the Antarctic glaciation at the Eocene-Oligocene boundary was preceded by a period of heat accumulation in the low latitudes, likely focused in a progressively contracting South Atlantic gyre, which contributed to cooling high-latitude austral regions. This prominent redistribution of heat corresponds to the emplacement of a strong meridional temperature gradient that typifies icehouse climate conditions. Our equatorial coccolith-derived geochemical record thus highlights an important period of global climatic and oceanic upheaval, which began 4 million years before the EOT and, superimposed on a long-term pCO 2 decline, drove the Earth system toward a glacial tipping point in the Cenozoic.

Cyclotron heating rate in a parabolic mirror

International Nuclear Information System (INIS)

Smith, P.K.

1984-01-01

Cyclotron resonance heating rates are found for a parabolic magnetic mirror. The equation of motion for perpendicular velocity is solved, including the radial magnetic field terms neglected in earlier papers. The expression for heating rate involves an infinite series of Anger's and Weber's functions, compared with a single term of the unrevised expression. The new results show an increase of heating rate compared with previous results. A simple expression is given for the ratio of the heating rates. (author)

Analysis of an underground electric heating system with short-term energy storage

Energy Technology Data Exchange (ETDEWEB)

Ramadan, B.H. [Michigan State Univ., East Lansing, MI (United States). Dept. of Mechanical Engineering

1994-12-31

The principal commercially active heat storage application in which concrete is used as the storage medium is in the use of subfloor electric heaters embedded in a layer of sand. The resistance heaters are energized when utility offpeak rates are in effect. The sand bed and the concrete floor are then heated to some predetermined temperature, and the floor releases heat slowly and remains warm during the subsequent period of high demand. Analysis of the slab-heating system for varying design parameters, such as the depth of the placement of the heaters, the sand properties, the energy input, and the insulation thickness, was considered. The system was also optimized based on life-cycle costs. The suitability of using this system for heating a warehouse in four representative cities in the United States was also considered The response of the system was found to be greatly influenced by the depth of the placement of the heaters, the sand`s moisture content, and the heating strategy. Optimum insulation levels were determined for the prototypical building in all four of the representative cities. Because of the difficulty of controlling the energy release from the heating mats, this system may not be suitable for heating residential and office buildings but may be more appropriate for heating maintenance and storage facilities.

Multidirectional Artificial Muscles from Nylon.

Science.gov (United States)

Mirvakili, Seyed M; Hunter, Ian W

2017-01-01

Multidirectional artificial muscles are made from highly oriented nylon filaments. Thanks to the low thermal conductivity of nylon and its anisotropic thermal expansion, bending occurs when a nylon beam is differentially heated. This heat can be generated via a Joule heating mechanism or high power laser pulses. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Short-term effect of superficial heat treatment on paraspinal muscle activity, stature recovery, and psychological factors in patients with chronic low back pain.

Science.gov (United States)

Lewis, Sandra E; Holmes, Paul S; Woby, Steve R; Hindle, Jackie; Fowler, Neil E

2012-02-01

To test the hypothesis that patients with chronic low back pain (CLBP) would have reduced paraspinal muscle activity when wearing a heat wrap and that this would be associated with increased stature recovery and short-term improvements in psychological factors. A within-subject repeated-measures design. Muscle activity and stature recovery were assessed before and after a 40-minute unloading period, both without a heat wrap and after 2 hours of wear. Questionnaires were completed after both sessions. Hospital physiotherapy department. Patients with CLBP (n=24; age, 48.0±9.0 y; height, 166.6±7.3 cm; body mass, 80.2±12.9 kg) and asymptomatic participants (n=11; age, 47.9±15.4 y; height, 168.7±11.6 cm; body mass, 69.3±13.1 kg) took part in the investigation. Patients on the waiting list for 2 physiotherapist-led rehabilitation programs, and those who had attended the programs during the previous 2 years, were invited to participate. Superficial heat wrap. Paraspinal muscle activity, stature recovery over a 40-minute unloading period, pain, disability, and psychological factors. For the CLBP patients only, the heat wrap was associated with a reduction in nonnormalized muscle activity and a positive short-term effect on self-report of disability, pain-related anxiety, catastrophizing, and self-efficacy. Changes in muscle activity were correlated with changes in stature recovery, and both were also correlated to changes in psychological factors. Use of the heat wrap was associated with a decrease in muscle activity and a short-term improvement in certain aspects of well-being for the CLBP patients. The results confirm the link between the biomechanical and psychological outcome measures. Copyright © 2012 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Physical Analysis of an Electric Resistor Heating

Science.gov (United States)

Perea Martins, J. E. M.

2018-01-01

This work describes a simple experiment to measure the resistor temperature as a function of the applied power and proves that it is an efficient way to introduce some important physical concepts in classroom, including the Joule's first law, hot-spot temperature, thermal resistance, thermal dissipation constant, time constant and the Newton's law…

Impact of high-latitude energy input on the mid- and low-latitude ionosphere and thermosphere

Science.gov (United States)

Lu, G.; Sheng, C.

2017-12-01

High-latitude energy input has a profound impact on the ionosphere and thermosphere especially during geomagnetic storms. Intense auroral particle precipitation ionizes neutral gases and modifies ionospheric conductivity; collisions between neutrals and fast-moving ions accelerate the neutral winds and produce Joule frictional heating; and the excess Joule and particle heating causes atmospheric upwelling and changes neutral composition due to the rising of the heavier, molecular-rich air. In addition, impulsive Joule heating launches large-scale gravity waves that propagate equatorward toward middle and low latitudes and even into the opposite hemisphere, altering the mean global circulation of the thermosphere. Furthermore, high-latitude electric field can also directly penetrate to lower latitudes under rapidly changing external conditions, causing prompt ionospheric variations in the mid- and low-latitude regions. To study the effects of high-latitude energy input, we apply the different convection and auroral precipitation patterns based on both empirical models and the AMIE outputs. We investigate how the mid- and low-latitude regions respond to the different specifications of high-latitude energy input. The main purpose of the study is to delineate the various dynamical, electrodynamical, and chemical processes and to determine their relative importance in the resulting ionospheric and thermospheric properties at mid and low latitudes.

Temperature effects on the electrohydrodynamic and electrokinetic behaviour of ion-selective nanochannels

International Nuclear Information System (INIS)

Wood, Jeffery A; Benneker, Anne M; Lammertink, Rob G H

2016-01-01

A non-isothermal formulation of the Poisson–Nernst–Planck with Navier–Stokes equations is used to study the influence of heating effects in the form of Joule heating and viscous dissipation and imposed temperature gradients on a microchannel/nanochannel system. The system is solved numerically under various cases in order to determine the influence of temperature-related effects on ion-selectivity, flux and fluid flow profiles, as well as coupling between these phenomena. It is demonstrated that for a larger reservoir system, the effects of Joule heating and viscous dissipation only become relevant for higher salt concentrations and electric field strengths than are compatible with ion-selectivity due to Debye layer overlap. More interestingly, it is shown that using different temperature reservoirs can have a strong influence on ion-selectivity, as well as the induced electrohydrodynamic flows. (paper)

Development of engineering scale HLLW vitrification technique at PNC

International Nuclear Information System (INIS)

Nagaki, H.; Oguino, N.; Tsunoda, N.; Segawa, T.

1979-01-01

Some processes have been investigated to develop the technology of solidification of the high-level radioactive liquid waste generated from the nuclear fuel reprocessing plant operated by the Power Reactor and Nuclear Fuel Development Corporation (PNC) at Tokai-mura. This report covers the present state of development of a Joule-heated ceramic melter and a direct megahertz induction-heated melter. Engineering-scale tests have been performed with both melters. The Joule-heated melter could produce 45 kg or 16 liters of glass per hour. The direct-induction furnace was able to melt 5 kg or 1.8 liters of glass per hour. Both melters were composed of electrofused cast refractory brick. Thus it was possible to melt the glass at above 1200 0 C. Glass produced at higher melting temperatures is generally superior. 3 figures, 2 tables

Experimental investigation of pool boiling heat transfer and critical heat flux on a downward facing surface

International Nuclear Information System (INIS)

Gocmanac, M.; Luxat, J.C.

2012-01-01

A separate effects experimental study of heat transfer and Critical Heat Flux (CHF) on a downward facing plate in subcooled water pool boiling is described. Two geometries of downwards facing surfaces are studied. The first is termed the 'confined' study in which bubble motion is restricted to the heated surface. The second is termed the 'unconfined' study where individual bubbles are free to move along the heated surface and vent in any direction. The method used in the confined study is novel and involves the placement of a lip surrounding the heated surface. The CHF as a function of angle of inclination of the surface is presented and is in good agreement with other experimental data from somewhat different test geometries. (author)

Consideration of critical heat flux margin prediction by subcooled or low quality critical heat flux correlations

International Nuclear Information System (INIS)

Hejzlar, P.; Todreas, N.E.

1996-01-01

The accurate prediction of the critical heat flux (CHF) margin which is a key design parameter in a variety of cooling and heating systems is of high importance. These margins are, for the low quality region, typically expressed in terms of critical heat flux ratios using the direct substitution method. Using a simple example of a heated tube, it is shown that CHF correlations of a certain type often used to predict CHF margins, expressed in this manner, may yield different results, strongly dependent on the correlation in use. It is argued that the application of the heat balance method to such correlations, which leads to expressing the CHF margins in terms of the critical power ratio, may be more appropriate. (orig.)

German central solar heating plants with seasonal heat storage

Energy Technology Data Exchange (ETDEWEB)

Bauer, D.; Marx, R.; Nussbicker-Lux, J.; Ochs, F.; Heidemann, W. [Institute of Thermodynamics and Thermal Engineering (ITW), University of Stuttgart, Pfaffenwaldring 6, D-70550 Stuttgart (Germany); Mueller-Steinhagen, H. [Institute of Thermodynamics and Thermal Engineering (ITW), University of Stuttgart, Pfaffenwaldring 6, D-70550 Stuttgart (Germany); Institute of Technical Thermodynamics (ITT), German Aerospace Centre (DLR), Stuttgart (Germany)

2010-04-15

Central solar heating plants contribute to the reduction of CO{sub 2}-emissions and global warming. The combination of central solar heating plants with seasonal heat storage enables high solar fractions of 50% and more. Several pilot central solar heating plants with seasonal heat storage (CSHPSS) built in Germany since 1996 have proven the appropriate operation of these systems and confirmed the high solar fractions. Four different types of seasonal thermal energy stores have been developed, tested and monitored under realistic operation conditions: Hot-water thermal energy store (e.g. in Friedrichshafen), gravel-water thermal energy store (e.g. in Steinfurt-Borghorst), borehole thermal energy store (in Neckarsulm) and aquifer thermal energy store (in Rostock). In this paper, measured heat balances of several German CSHPSS are presented. The different types of thermal energy stores and the affiliated central solar heating plants and district heating systems are described. Their operational characteristics are compared using measured data gained from an extensive monitoring program. Thus long-term operational experiences such as the influence of net return temperatures are shown. (author)

Heat transfer in intermediate heat exchanger under low flow rate conditions

International Nuclear Information System (INIS)

Mochizuki, H.

2008-01-01

The present paper describes the heat transfer in intermediate heat exchangers (IHXs) of liquid metal cooled fast reactors when flow rate is low such as a natural circulation condition. Although empirical correlations of heat transfer coefficients for IHX were derived using test data at the fast reactor 'Monju' and 'Joyo' and also at the 50 MW steam generator facility, the heat transfer coefficient was very low compared to the well known correlation for liquid metals proposed by Seban-Shimazaki. The heat conduction in IHX was discussed as a possible cause of the low Nusselt number. As a result, the heat conduction is not significant under the natural circulation condition, and the heat conduction term in the energy equation can be neglected in the one-dimensional plant dynamics calculation. (authors)

High-frequency plasma oscillations

Energy Technology Data Exchange (ETDEWEB)

Akhiezer, A I; Fainberg, Y B; Sitenko, A G; Stepanov, K; Kurilko, V; Gorbatenko, M; Kirochkin, U [Academy of Sciences of the Ukrainian SSR (USSR)

1958-07-01

It is well known that the electrical conductivity of a plasma, the ion-electron equilibration time, and the time required to heat the electron component of the plasma all increase greatly with increasing temperature. Consequently, the usual method of Joule heating a plasma may be difficult to apply in the region of high temperatures (> 10{sup 6}K), especially if the plasma current alone, without any additional measures, is used to generate magnetic fields for the confinement of the plasma. Therefore, it is of interest to study methods of plasma heating that do not directly use Joule heat, especially methods by which energy is directly supplied to the ion component during the time between collisions. Some of these methods make use of ionic resonance as well as other resonance phenomena which can occur in plasma in an external magnetic field. This paper deals with certain aspects of the theory of high-frequency plasma oscillations.

Scaling vectors of attoJoule per bit modulators

Science.gov (United States)

Sorger, Volker J.; Amin, Rubab; Khurgin, Jacob B.; Ma, Zhizhen; Dalir, Hamed; Khan, Sikandar

2018-01-01

Electro-optic modulation performs the conversion between the electrical and optical domain with applications in data communication for optical interconnects, but also for novel optical computing algorithms such as providing nonlinearity at the output stage of optical perceptrons in neuromorphic analog optical computing. While resembling an optical transistor, the weak light-matter-interaction makes modulators 105 times larger compared to their electronic counterparts. Since the clock frequency for photonics on-chip has a power-overhead sweet-spot around tens of GHz, ultrafast modulation may only be required in long-distance communication, not for short on-chip links. Hence, the search is open for power-efficient on-chip modulators beyond the solutions offered by foundries to date. Here, we show scaling vectors towards atto-Joule per bit efficient modulators on-chip as well as some experimental demonstrations of novel plasmonic modulators with sub-fJ/bit efficiencies. Our parametric study of placing different actively modulated materials into plasmonic versus photonic optical modes shows that 2D materials overcompensate their miniscule modal overlap by their unity-high index change. Furthermore, we reveal that the metal used in plasmonic-based modulators not only serves as an electrical contact, but also enables low electrical series resistances leading to near-ideal capacitors. We then discuss the first experimental demonstration of a photon-plasmon-hybrid graphene-based electro-absorption modulator on silicon. The device shows a sub-1 V steep switching enabled by near-ideal electrostatics delivering a high 0.05 dB V-1 μm-1 performance requiring only 110 aJ/bit. Improving on this demonstration, we discuss a plasmonic slot-based graphene modulator design, where the polarization of the plasmonic mode aligns with graphene’s in-plane dimension; where a push-pull dual-gating scheme enables 2 dB V-1 μm-1 efficient modulation allowing the device to be just 770 nm

Study of the valorisation of thermal storage and of power-to-heat. Study report + Study synthesis

International Nuclear Information System (INIS)

Canal, Patrick; Gerbaud, Manon; Mouret, Sylvain; Chammas, Maxime; Attard, Pierre; Bucy, Jacques de; Lochmann, Hugo; Le Gars, Loic; Payen, Luc; Lesueur, Herve

2016-11-01

of description of the various technologies (sensitive heat storage, latent heat storage, thermochemical heat storage, thermodynamic power-to-heat, power-to-heat based on the Joule effect) and sheets of presentation of case studies

Application of the time dependent suction to free convection laminar flow in the presence of transverse magnetic field

International Nuclear Information System (INIS)

Agrawal, H.L.; Ram, P.C.

1980-01-01

The laminar unsteady free convection and heat transfer of an electrically conducting fluid past a porous vertical flat plate in the presence of uniform transverse magnetic field is investigated when the free stream velocity and suction at the plate are oscillatory functions of time, viscous dissipation term and Joul's dissipation term have been neglected at low velocity. Expressions for velocity and temperature distributions have been obtained in the non-dimensional forms and the skin-friction has been calculated. The skin-friction decreases by increasing Hartmann number. The suction is applied to check the growth of the boundary layer. This study is likely to have bearing on the problem of boundary layer control and transpiration cooling. (author)

Effects of energetic electrons on the electrodynamics in the ionosphere

Directory of Open Access Journals (Sweden)

A. Aksnes

2004-01-01

Full Text Available From the observations by the PIXIE and UVI cameras on board the Polar satellite, we derive global maps of the precipitating electron energy spectra from less than 1keV to 100keV. Based on the electron spectra, we generate instantaneous global maps of Hall and Pedersen conductances. The UVI camera provides good coverage of the lower electron energies contributing most to the Pedersen conductance, while PIXIE captures the high energy component of the precipitating electrons affecting the Hall conductance. By characterizing the energetic electrons from some tens of keV and up to about 100keV using PIXIE X-ray measurements, we will, in most cases, calculate a larger electron flux at higher energies than estimated from a simple extrapolation of derived electron spectra from UVI alone. Instantaneous global conductance maps derived with and without inclusion of PIXIE data have been implemented in the Assimilative Mapping of Ionospheric Electrodynamics (AMIE procedure, to study the effects of energetic electrons on electrodynamical parameters in the ionosphere. We find that the improved electron spectral characterization using PIXIE data most often results in a larger Hall conductance and a smaller inferred electric field. In some localized regions the increase in the Hall conductance can exceed 100%. On the contrary, the Pedersen conductance remains more or less unaffected by the inclusion of the PIXIE data. The calculated polar cap potential drop may decrease more than 10%, resulting in a reduction of the estimated Joule heating integrated over the Northern Hemisphere by up to 20%. Locally, Joule heating may decrease more than 50% in some regions. We also find that the calculated energy flux by precipitating electrons increases around 5% when including the PIXIE data. Combined with the reduction of Joule heating, this results in a decrease in the ratio between Joule heating and energy flux, sometimes exceeding 25%. An investigation of the relationship

Heat Saving Strategies in Sustainable Smart Energy Systems

DEFF Research Database (Denmark)

Lund, Henrik; Thellufsen, Jakob Zinck; Aggerholm, Søren

that a least‐cost strategy will be to provide approximately 2/3 of the heat demand from district heating and the rest from individual heat pumps. Keywords: Energy Efficiency, Renewable energy, Heating strategy, Heat savings, District heating, Smart energy......One of the important issues related to the implementation of future sustainable smart energy systems based on renewable energy sources is the heating of buildings. Especially, when it comes to long‐term investment in savings and heating infrastructures it is essential to identify long‐term least......‐cost strategies. With Denmark as a case, this paper investigates to which extent heat should be saved rather than produced and to which extent district heating infrastructures, rather than individual heating solutions, should be used. Based on a concrete proposal to implement the Danish governmental long...

Heat Roadmap Europe

DEFF Research Database (Denmark)

Connolly, David

2017-01-01

This paper compares the electricity, heating, and cooling sectors at national level for various European countries. Annual energy demands are compared for all 28 EU countries, while peak hourly demands are compared for four countries that vary significantly. The results indicate that the heat...... demand is currently the largest of the three demand types considered in terms of both annual and peak demands: it is the largest annual demand in 25 of the 28 EU countries, and it represents the largest peak demand in all four countries analysed. Electricity, heating, and cooling demands are all likely...... that the demand for electricity could double compared to today, depending on how these changes occur. Considering the scale of additional electricity required to electrify future heating and cooling demands, heat pumps should be prioritised over electric heating and other alternatives, such as district heating...

Ammonia and Carbon Dioxide Heat Pumps for Heat Recovery in Industry

OpenAIRE

Brix, Wiebke; Christensen, Stefan W.; Markussen, Michael M.; Reinholdt, Lars; Elmegaard, Brian

2012-01-01

This paper presents a generic, numerical study of high temperature heat pumps for waste heat recovery in industry using ammonia and carbon dioxide as refrigerants. A study of compressors available on the market today, gives a possible application range of the heat pumps in terms of temperatures. Calculations of cycle performances are performed using a reference cycle for both ammonia and carbon dioxide as refrigerant. For each cycle a thorough sensitivity analysis reveals that the forward and...

STUDY OF THE IMPACT OF THERMAL DRIFT ON RELIABILITY OF PRESSURE SENSORS

Directory of Open Access Journals (Sweden)

ABDELAZIZ BEDDIAF

2017-10-01

Full Text Available Piezoresistive pressure sensors, using a Wheatstone bridge with the piezoresistors, are typically supplied with a voltage ranging from 3 to 10 V involve thermal drift caused by Joule heating. In this paper, an accurate numerical model for optimization and predicting the thermal drift in piezoresistive pressure sensors due to the electric heater in its piezoresistors is adopted. In this case, by using the solution of 2D heat transfer equation considering Joule heating in Cartesian coordinates for the transient regime, we determine how the temperature affects the sensor when the supply voltage is applied. For this, the elevation of temperature due to the Joule heating has been calculated for various values of supply voltage and for several operating times of the sensor; by varying different geometrical parameters. Otherwise, the variation of the coefficient 44 in p-Si and pressure sensitivity as a function of the applied potential, as well as, for various times, for different dimensions of the device, have been also established. It is observed that the electrical heating leads to an important temperature rise in the piezoresistor. Consequently, it causes drift in the pressure sensitivity of the sensor upon application of a voltage. Finally, this work allows us to evaluate the reliability of sensors. Also, it permits to predict their behaviour against temperature due to the application of a voltage of a bridge and to minimize this effect by optimizing the geometrical parameters of the sensor and by reducing the supply voltage.

Actions of magnetospheres on planetary atmospheres

International Nuclear Information System (INIS)

Hultqvist, Bengt.

1989-12-01

Planet Earth is rather special in terms of transfer of magnetospheric energy to the atmosphere (apart from Jupiter, which is extreme in almost all respects). The auroral particle energy input rate to the atmosphere per unit area, and therefore the resulting auroral emission intensity, is second only to that of Jupiter. The contribution of the Joule heating to the heating of the upper atmosphere, measured in terms of the energetic particle precipitation power, is probably larger on Earth than on all the other planets, possibly with the exception of Uranus (and perhaps Neptune, which we know nothing of when this is written). For all those planets which have a corotating plasmasphere extending to the magnetopause, the Joule heating power is small compared with the precipitating particle power. The extremely successful Pioneer and Voyager missions have provided us with most impressive sets of data from the outer planets and Phobos has recently added unique new data from Mars. Still, the conclusion that the observational basis for our understanding of the physics of the magnetosphere-atmosphere interactions at all the planets other than Earth is very limited, is a self-evident one. Even at Earth many aspects of this interaction are frontline areas of research. The grand tour of the Voyagers has demonstrated very clearly how different the magnetospheres and atmospheres of the various planets are and the very high degree of complexity of the plasma systems around the planets. Most questions of physics are still unanswered; those related to source and sink processes of the plasma and energetic particles being one set of examples. The Galileo and Cassini-Huygens missions will certainly contribute in very important ways to the answering of many open questions. (147 refs.)

Advances in Large-Scale Solar Heating and Long Term Storage in Denmark

DEFF Research Database (Denmark)

Heller, Alfred

2000-01-01

According to (the) information from the European Large-Scale Solar Heating Network, (See http://www.hvac.chalmers.se/cshp/), the area of installed solar collectors for large-scale application is in Europe, approximately 8 mill m2, corresponding to about 4000 MW thermal power. The 11 plants...... the last 10 years and the corresponding cost per collector area for the final installed plant is kept constant, even so the solar production is increased. Unfortunately large-scale seasonal storage was not able to keep up with the advances in solar technology, at least for pit water and gravel storage...... of the total 51 plants are equipped with long-term storage. In Denmark, 7 plants are installed, comprising of approx. 18,000-m2 collector area with new plants planned. The development of these plants and the involved technologies will be presented in this paper, with a focus on the improvements for Danish...

Numerical solutions for magnetohydrodynamic flow of nanofluid over a bidirectional non-linear stretching surface with prescribed surface heat flux boundary

International Nuclear Information System (INIS)

Mahanthesh, B.; Gireesha, B.J.; Gorla, R.S. Reddy; Abbasi, F.M.; Shehzad, S.A.

2016-01-01

Numerical solutions of three-dimensional flow over a non-linear stretching surface are developed in this article. An electrically conducting flow of viscous nanoliquid is considered. Heat transfer phenomenon is accounted under thermal radiation, Joule heating and viscous dissipation effects. We considered the variable heat flux condition at the surface of sheet. The governing mathematical equations are reduced to nonlinear ordinary differential systems through suitable dimensionless variables. A well-known shooting technique is implemented to obtain the results of dimensionless velocities and temperature. The obtained results are plotted for multiple values of pertinent parameters to discuss the salient features of these parameters on fluid velocity and temperature. The expressions of skin-friction coefficient and Nusselt number are computed and analyzed comprehensively through numerical values. A comparison of present results with the previous results in absence of nanoparticle volume fraction, mixed convection and magnetic field is computed and an excellent agreement noticed. We also computed the results for both linear and non-linear stretching sheet cases. - Highlights: • Hydromagnetic flow of nanofluid over a bidirectional non-linear stretching surface is examined. • Cu, Al 2 O3 and TiO 2 types nanoparticles are taken into account. • Numerical solutions have been computed and addressed. • The values of skin-friction and Nusselt number are presented.

Performance of an Atkinson cycle with heat transfer, friction and variable specific-heats of the working fluid

International Nuclear Information System (INIS)

Ge Yanlin; Chen Lingen; Sun, Fengrui; Wu Chih

2006-01-01

The performance of an air standard Atkinson cycle with heat-transfer loss, friction-like term loss and variable specific-heats of the working fluid is analyzed using finite-time thermodynamics. The relations between the power output and the compression ratio, between the thermal efficiency and the compression ratio, as well as the optimal relation between the power output and the efficiency of the cycle are derived by detailed numerical examples. Moreover, the effects of variable specific-heats of the working fluid and the friction-like term loss on the irreversible cycle performance are analyzed. The results show that the effects of variable specific-heats of working fluid and friction-like term loss on the irreversible cycle performance should be considered in cycle analysis. The results obtained in this paper provide guidance for the design of Atkinson engines

Interferometric density measurements in the divertor and edge plasma regions for the additionally heated JT-60 plasmas

International Nuclear Information System (INIS)

Fukuda, T.; Yoshida, H.; Nagashima, A.; Ishida, S.; Kikuchi, M.; Yokomizo, H.

1989-01-01

The first divertor plasma density measurement and the interferometric edge plasma density measurement with boundary condition preserving millimeter waveguides were demonstrated to elucidate the mutual correlation among the divertor plasma, scrape-off layer plasma and the bulk plasma properties in the additionally heated JT-60 plasmas. The electron density in the divertor region exhibited a nonlinear dependence on the bulk plasma density for the joule-heated plasmas. When neutral beam heating is applied on the plasmas with the electron density above 2x10 19 /m 3 , however, the bulk plasma density is scraped off from the outer region to lead to density clamping, and the electron density in the divertor region rapidly increases over 1x10 20 /m 3 , from which we can deduce that the particle flow along the magnetic field is dominant, resulting in the apparent degradation of the particle confinement time. As for the case when neutral beam injection is applied to low-density plasmas, the bulk plasma electron density profile becomes flattened to yield a smaller density increase in the divertor region and no density clamping of the bulk plasma was observed. Simulation analysis which correlates the transport of the divertor plasma and the scrape-off layer plasma was also carried out to find the consistency with the experimental results. (orig.)

The Temperature and Salinity Variabilities at Cisadane Estuary

Directory of Open Access Journals (Sweden)

Hadikusumah

2008-11-01

Full Text Available The study was conducted at Cisadane Estuary at 18 oceanographic station in Transition Monsoon Season I, East Monsoon Season, and Transition Monsoon Season II from 2003 to 2005. The area of the study was located at the longitude of 106.58° - 106.70° E and the latitude of 5.96° - 6.02°S. The measurements of temperature, salinity, tubidity and light transmision used CTD (Conductivity, Temperature and Depth Model SBE-19. The result shows that the temperature and salinity vertical profil variabilities at Cisadane Estuary underwent a change in the influence of Transition Monsoon Season I, East Monsoon Season, and Transition Monsoon Season II, for example it was obtained the leg time of the maximum salinity of Transition Monsoon Season II as the same as that of East Monsoon Season. Based on the horizontal and vertical distribution pattern analysis of the interaction between low salinity fresh water of Cisadane River and high salinity sea water of Java Sea, it was also influenced by the season variability and tide. The surface layer was much more influenced by the low salinity and the heat of sunray (seasonal variability with the weaker intensity to the lower layer. The change of the heat energy by the increase of seasonal temperature occurred in September 2003 to May 2004 ((ΔE = 600.6 ⋅ 105 Joule, July to November 2005 (ΔE = 84.9 Joule. The decrease of the heat energy occurred in June to September 2003 ((-267.6 ⋅ 105, May ke October 2004 (ΔE = 189.3 ⋅ 105 Joule and October 2004 to July 2005 (ΔE = -215.4 ⋅ 105 Joule.

Nuclear heat source design for an advanced HTGR process heat plant

International Nuclear Information System (INIS)

McDonald, C.F.; O'Hanlon, T.W.

1983-01-01

A high-temperature gas-cooled reactor (HTGR) coupled with a chemical process facility could produce synthetic fuels (i.e., oil, gasoline, aviation fuel, methanol, hydrogen, etc.) in the long term using low-grade carbon sources (e.g., coal, oil shale, etc.). The ultimate high-temperature capability of an advanced HTGR variant is being studied for nuclear process heat. This paper discusses a process heat plant with a 2240-MW(t) nuclear heat source, a reactor outlet temperature of 950 0 C, and a direct reforming process. The nuclear heat source outputs principally hydrogen-rich synthesis gas that can be used as a feedstock for synthetic fuel production. This paper emphasizes the design of the nuclear heat source and discusses the major components and a deployment strategy to realize an advanced HTGR process heat plant concept

Numerical Study of the Dynamic Response of Heat and Mass Transfer to Operation Mode Switching of a Unitized Regenerative Fuel Cell

Directory of Open Access Journals (Sweden)

Hong Xiao

2016-12-01

Full Text Available Knowledge concerning the complicated changes of mass and heat transfer is desired to improve the performance and durability of unitized regenerative fuel cells (URFCs. In this study, a transient, non-isothermal, single-phase, and multi-physics mathematical model for a URFC based on the proton exchange membrane is generated to investigate transient responses in the process of operation mode switching from fuel cell (FC to electrolysis cell (EC. Various heat generation mechanisms, including Joule heat, reaction heat, and the heat attributed to activation polarizations, have been considered in the transient model coupled with electrochemical reaction and mass transfer in porous electrodes. The polarization curves of the steady-state models are validated by experimental data in the literatures. Numerical results reveal that current density, gas mass fractions, and temperature suddenly change with the sudden change of operating voltage in the mode switching process. The response time of temperature is longer than that of current density and gas mass fractions. In both FC and EC modes, the cell temperature and gradient of gas mass fraction in the oxygen side are larger than that in the hydrogen side. The temperature difference of the entire cell is less than 1.5 K. The highest temperature appears at oxygen-side catalyst layer under the FC mode and at membrane under a more stable EC mode. The cell is exothermic all the time. These dynamic responses and phenomena have important implications for heat analysis and provide proven guidelines for the improvement of URFCs mode switching.

Field performance of wood-burning and coal-burning appliances in Crested Butte during the 1989-90 heating season. Final report

International Nuclear Information System (INIS)

Jaasma, D.R.; Champion, M.R.; Gundappa, M.

1991-10-01

The field performance of woodburning and coalburning appliances in and around Crested Butte, CO, has been evaluated. Measurements included particulate matter (PM), carbon monoxide (CO), and weekly average burn rates. Woodburning appliances included conventional airtight stoves, EPA-certified catalytic stoves, and EPA-certified noncatalytic stoves. Compared to the emissions measured from conventional stoves, the certified stoves reduced PM emission factors (g/kg) by 53% and CO emission factors by 49%. Coalburning appliances included a commercial scale boiler, a residential stoker, and hand-fired coalstove. The coalburning appliances were compared to conventional woodstoves on a grams of pollutant per joule of heat output basis. The automatically stoked coal appliances reduced PM and CO emissions by roughly 84% and 85%, respectively. The hand-fired stove was cleaner than expected, reducing PM by 55% and CO by 27%

Nanometer-scale temperature measurements of phase change memory and carbon nanomaterials

Science.gov (United States)

Grosse, Kyle Lane

This work investigates nanometer-scale thermometry and thermal transport in new electronic devices to mitigate future electronic energy consumption. Nanometer-scale thermal transport is integral to electronic energy consumption and limits current electronic performance. New electronic devices are required to improve future electronic performance and energy consumption, but heat generation is not well understood in these new technologies. Thermal transport deviates significantly at the nanometer-scale from macroscopic systems as low dimensional materials, grain structure, interfaces, and thermoelectric effects can dominate electronic performance. This work develops and implements an atomic force microscopy (AFM) based nanometer-scale thermometry technique, known as scanning Joule expansion microscopy (SJEM), to measure nanometer-scale heat generation in new graphene and phase change memory (PCM) devices, which have potential to improve performance and energy consumption of future electronics. Nanometer-scale thermometry of chemical vapor deposition (CVD) grown graphene measured the heat generation at graphene wrinkles and grain boundaries (GBs). Graphene is an atomically-thin, two dimensional (2D) carbon material with promising applications in new electronic devices. Comparing measurements and predictions of CVD graphene heating predicted the resistivity, voltage drop, and temperature rise across the one dimensional (1D) GB defects. This work measured the nanometer-scale temperature rise of thin film Ge2Sb2Te5 (GST) based PCM due to Joule, thermoelectric, interface, and grain structure effects. PCM has potential to reduce energy consumption and improve performance of future electronic memory. A new nanometer-scale thermometry technique is developed for independent and direct observation of Joule and thermoelectric effects at the nanometer-scale, and the technique is demonstrated by SJEM measurements of GST devices. Uniform heating and GST properties are observed for

Flexible use of electricity in heat-only district heating plants

Directory of Open Access Journals (Sweden)

Erik Trømborg

2017-01-01

Full Text Available European energy systems are in a period of significant transition, with the increasing shares of variable renewable energy (VRE and less flexible fossil-based generation units as predominant factors. The supply-side changes are expected to cause large short-term electricity price volatility. More frequent periods of low electricity prices may mean that electric use in flexible heating systems will become more profitable, and such flexible heating systems may, in turn, improve the integration of increasing shares of VRE. The objective of this study is to analyze the likely future of Nordic electricity price levels and variations and how the expected prices might affect the use of electricity and thermal storage in heat-only district heating plants. We apply the North European energy market model Balmorel to provide scenarios for future hourly electricity prices in years with normal, high, and low inflow levels to the hydro power system. The simulation tool energyPRO is subsequently applied to quantify how these electricity price scenarios affect the hourly use of thermal storage and individual boilers in heat-only district heating plants located in Norway. The two studied example plants use wood chips or heat pump as base load representing common technologies for district heating in Norway. The Balmorel results show that annual differences in inflow is still a decisive factor for Norwegian and Nordic electricity prices in year 2030 and that short-term (daily price variability is expected to increase. In the plant-level simulations, we find that tank storage, which is currently installed in only a few district heating plants in Norway, is a profitable flexibility option that will significantly reduce the use of fossil peak load in both biomass and heat-pump-based systems. Installation of an electric boiler in addition to tank storage is profitable in the heat pump system due to the limited capacity of the heat pump. Electricity will hence, to a

Numerical Modeling of Fin and Tube Heat Exchanger for Waste Heat Recovery

DEFF Research Database (Denmark)

Singh, Shobhana; Sørensen, Kim; Condra, Thomas Joseph

In the present work, multiphysics numerical modeling is carried out to predict the performance of a liquid-gas fin and tube heat exchanger design. Three-dimensional (3D) steady-state numerical model using commercial software COMSOL based on finite element method (FEM) is developed. The study...... associates conjugate heat transfer phenomenon with the turbulent flow to describe the variable temperature and velocity profile. The performance of heat exchanger design is investigated in terms of overall heat transfer coefficient, Nusselt number, Colburn j-factor, flow resistance factor, and efficiency...... between fin and tube. The present numerical model predicts the performance of the heat exchanger design, therefore, can be applied to existing waste heat recovery systems to improve the overall performance with optimized design and process-dependent parameters....

Development of a hermetically sealed brushless DC motor for a J-T cryocooler

Science.gov (United States)

Joscelyn, Edwin; Hochler, Irwin; Ferri, Andrew; Rott, Heinz; Soukaris, Ted

1996-01-01

This development was sponsored by Ball Aerospace for the Cryogenic On-Orbit LongLife Active Refrigerator (COOLLAR) program. The cryocooler is designed to cool objects to 65 K and operate in space for at least 7 years. The system also imports minimal impact to the spacecraft in terms of vibration and heat. The basic Joule-Thompson cycle involves compressing a working fluid, nitrogen in this case, at near-constant temperature from 17.2 KPa to 6.89 MPa. The nitrogen is then expanded through a Joule-Thompson valve. The pure nitrogen gas must be kept clean; therefore, any contamination from motor organic materials must be eliminated. This requirement drove the design towards sealing of the motor within a titanium housing without sacrificing motor performance. It is estimated that an unsealed motor would have contributed 1.65 g of contaminants, due to the organic insulation and potting materials, over the 7-year life. This paper describes the motor electrical and mechanical design, as well as the sealing difficulties encountered, along with their solutions.

Thermodynamics and heat power

CERN Document Server

Granet, Irving

2014-01-01

Fundamental ConceptsIntroductionThermodynamic SystemsTemperatureForce and MassElementary Kinetic Theory of GasesPressureReviewKey TermsEquations Developed in This ChapterQuestionsProblemsWork, Energy, and HeatIntroductionWorkEnergyInternal EnergyPotential EnergyKinetic EnergyHeatFlow WorkNonflow WorkReviewKey TermsEquations Developed in This ChapterQuestionsProblemsFirst Law of ThermodynamicsIntroductionFirst Law of ThermodynamicsNonflow SystemSteady-Flow SystemApplications of First Law of ThermodynamicsReviewKey TermsEquations Developed in This ChapterQuestionsProblemsThe Second Law of ThermodynamicsIntroductionReversibility-Second Law of ThermodynamicsThe Carnot CycleEntropyReviewKey TermsEquations Developed in This ChapterQuestionsProblemsProperties of Liquids and GasesIntroductionLiquids and VaporsThermodynamic Properties of SteamComputerized PropertiesThermodynamic DiagramsProcessesReviewKey TermsEquations Developed in This ChapterQuestionsProblemsThe Ideal GasIntroductionBasic ConsiderationsSpecific Hea...

Heat treatment effect on structure and long-term rupture strength of γ/γ'-MeC nickel eutectic. Length memory effect

International Nuclear Information System (INIS)

Kishkin, S.T.; Svetlov, I.L.; Sorokina, L.P.; Morozova, S.G.; Golubovskij, E.R.; Yushakova, F.V.

1983-01-01

Heat treatment effect on structure, phase composition and long-term rupture strength of the directional eutectics on the nickel base with γ/γ'-MeC structure is studied at 900-1100 deg C. It is shown that quenching from the temperature of complete dissolving of γ'-phase and ageing (900 deg - 30 hr) provide an optimum size and morphology of the γ-phase and an increase of the long-term rupture strength at 900 and 1000 deg C. Repeated thermal treatment of cimens tested during definite time restores their structure, mechanical properties and dimensions

Investigation of pressure drop in capillary tube for mixed refrigerant Joule-Thomson cryocooler

International Nuclear Information System (INIS)

Ardhapurkar, P. M.; Sridharan, Arunkumar; Atrey, M. D.

2014-01-01

A capillary tube is commonly used in small capacity refrigeration and air-conditioning systems. It is also a preferred expansion device in mixed refrigerant Joule-Thomson (MR J-T) cryocoolers, since it is inexpensive and simple in configuration. However, the flow inside a capillary tube is complex, since flashing process that occurs in case of refrigeration and air-conditioning systems is metastable. A mixture of refrigerants such as nitrogen, methane, ethane, propane and iso-butane expands below its inversion temperature in the capillary tube of MR J-T cryocooler and reaches cryogenic temperature. The mass flow rate of refrigerant mixture circulating through capillary tube depends on the pressure difference across it. There are many empirical correlations which predict pressure drop across the capillary tube. However, they have not been tested for refrigerant mixtures and for operating conditions of the cryocooler. The present paper assesses the existing empirical correlations for predicting overall pressure drop across the capillary tube for the MR J-T cryocooler. The empirical correlations refer to homogeneous as well as separated flow models. Experiments are carried out to measure the overall pressure drop across the capillary tube for the cooler. Three different compositions of refrigerant mixture are used to study the pressure drop variations. The predicted overall pressure drop across the capillary tube is compared with the experimentally obtained value. The predictions obtained using homogeneous model show better match with the experimental results compared to separated flow models

Condensation heat transfer coefficient of air-cooled condensing heat exchanger of emergency cooldown tank in long-term passive cooling system

International Nuclear Information System (INIS)

Huh, Seon Jeong; Lee, Hee Joon; Moon, Joo Hyung; Bae, Youngmin; Kim, Young In

2017-01-01

For the design purpose of air-cooled condensing heat exchanger of emergency cooldown tank, average condensation heat transfer coefficient inside a circular tube was reduced by a thermal sizing program using the experimental data of Kim et al. It was compared to the existing condensation heat transfer correlations. Moreover, a sensitivity analysis of both inside condensation and outside air natural convection correlations was performed. Although condensation heat transfer did not play a great role to design over 10 3 W/m 2 /K, the improved Shah's correlation gives the best prediction for the design. Consequently, air natural convection coefficient significantly affects the design of air-cooled condensing heat exchanger. (author)

Evaporation heat transfer of hot water from horizontal free service

International Nuclear Information System (INIS)

Koizumi, Y.; Ebihara, Y.; Hirota, T.; Murase, M.

2011-01-01

Evaporation heat transfer from the hot water flow to the cold air flow in a horizontal duct was examined. Hot water was in the range of 35 o C ~ 65 o C. Cold air was approximately 25 o C. The air velocity was varied from 0.0656 m/s ~ 1.41 m/s. The heat transfer rate from the water flow to the air flow became large with an increase in the air velocity. The higher the water temperature was, the larger the heat transfer rate was. When the total heat flux from water to the air flow is divided into two terms; the evaporation term and the forced flow convection term, the evaporation term dominate main part and that is about 90 ~ 80 % of the total heat flux. The measured values of the evaporation term and the forced flow convection term were larger than the predicted because of the effect of the diffusion of evaporated vapor. The correlation to predict the heat transfer from the hot water flow to the cold air flow with the evaporation was developed by modifying the laminar flow mass transfer correlation and the laminar forced convection heat transfer correlation. Good results were obtained. (author)

Evaporation heat transfer of hot water from horizontal free service

Energy Technology Data Exchange (ETDEWEB)

Koizumi, Y.; Ebihara, Y.; Hirota, T. [Shinshu Univ., Ueda, Nagano (Japan); Murase, M. [INSS, Mihama-cho, Fukui (Japan)

2011-07-01

Evaporation heat transfer from the hot water flow to the cold air flow in a horizontal duct was examined. Hot water was in the range of 35{sup o}C ~ 65{sup o}C. Cold air was approximately 25{sup o}C. The air velocity was varied from 0.0656 m/s ~ 1.41 m/s. The heat transfer rate from the water flow to the air flow became large with an increase in the air velocity. The higher the water temperature was, the larger the heat transfer rate was. When the total heat flux from water to the air flow is divided into two terms; the evaporation term and the forced flow convection term, the evaporation term dominate main part and that is about 90 ~ 80 % of the total heat flux. The measured values of the evaporation term and the forced flow convection term were larger than the predicted because of the effect of the diffusion of evaporated vapor. The correlation to predict the heat transfer from the hot water flow to the cold air flow with the evaporation was developed by modifying the laminar flow mass transfer correlation and the laminar forced convection heat transfer correlation. Good results were obtained. (author)

Visualisation of heat transfer in laminar flows

NARCIS (Netherlands)

Speetjens, M.F.M.; Steenhoven, van A.A.

2009-01-01

Heat transfer in fluid flows traditionally is examined in terms of temperature field and heat-transfer coefficients at non-adiabatic walls. However, heat transfer may alternatively be considered as the transport of thermal energy by the total convective-conductive heat flux in a way analogous to the

Long-term impacts of prescribed burns on soil thermal conductivity and soil heating at a Colorado Rocky Mountain site: a data/model fusion study

Science.gov (United States)

W. J. Massman; J. M. Frank; N. B. Reisch

2008-01-01

Heating any soil during a sufficiently intense wild fire or prescribed burn can alter that soil irreversibly, resulting in many significant, and well studied, long-term biological, chemical, and hydrological effects. On the other hand, much less is known about how fire affects the thermal properties and the long-term thermal regime of soils. Such knowledge is important...

Study on heat transfer from hot water to air with evaporation. 2nd report

International Nuclear Information System (INIS)

Yamaji, Tatsuya; Hirota, Tatsuya; Koizumi, Yasuo; Murase, Michio

2013-01-01

Heat transfer from hot water flow to cold air flow was examined. In the present study, the air flow was in turbulent flow condition. When the heat flux from the water flow to the air flow is divides into two terms of an evaporation term and a convection term, the evaporation term is much higher than the convection term; approximately 80 ∼ 60% of the total heat flux since latent heat is taken into the air flow by evaporating vapor. The convection term was approximately two times of the single-phase heat transfer rate with no evaporation. By making use of the analogy between the mass transfer and the heat transfer, and the single-phase heat transfer correlation, the predicting method of the heat transfer rate with the evaporation was developed. (author)

Global measures of ionospheric electrodynamic activity inferred from combined incoherent scatter radar and ground magnetometer observations

International Nuclear Information System (INIS)

Richmond, A.D.; Kamide, Y.; Akasofu, S.I.; Alcayde, D.; Blanc, M.; De LaBeaujardiere, O.; Evans, D.S.; Foster, J.C.; Holt, J.M.; Friis-Christensen, E.; Pellinen, R.J.; Senior, C.; Zaitzev, A.N.

1990-01-01

An analysis of several global measures of high-latitude ionospheric electrodynamic activity is undertakn on the basis of results obtained from the Assimilative Mapping of Ionospheric Electrodynamics (AMIE) procedure applied to incoherent scatter radar and ground magnetometer observatons for January 18-19, 1984. Different global measures of electric potentials, currents, resistances, and energy transfer from the magnetosphere show temporal variations that are generally well correlated. The authors present parameterizations of thees quantities in terms of the AE index and the hemispheric power index of precipitating auroral particles. It is shown how error estimates of the mapped electric fields can be used to correct the estimation of Joule heating. Global measures of potential drop, field-aligned current, and Joule heating as obtained by the AMIE procedure are compared with similar measures presented in previous studies. Agreement is found to within the uncertainties inherent in each study. The mean potential drop through which field-aligned currents flow in closing through the ionosphere is approximately 28% of the total polar cap potential drop under all conditions during these 2 days. They note that order-of-magnitude differences can appear when comparing different global measures of total electric current flow and of effective resistances of the global circuit, so that care must be exercised in choosing characteristic values of these parameters for circuit-analogy studies of ionosphere-magnetosphere electrodynamic coupling

Effect of two dimensional heat conduction within the wall on heat transfer of a tube partially heated on its circumference

International Nuclear Information System (INIS)

Satoh, Isao; Kurosaki, Yasuo

1987-01-01

This paper dealt with the numerical calculations of the heat transfer of a tube partially heated on its circumference, considering two-dimensional heat conduction within the wall. The contribution of the unheated region of the tube wall to heat tranfer of the heated region was explained by the term of 'fin efficiency of psuedo-fin', it was clarified that the fin efficiency of the unheated region was little affected by the temperature difference between the inner and outer surfaces of the wall, and could be approximated by the fin efficency of a rectangular fin. Both the circumferential and radial heat conductions within the wall affected the temperature difference between the inner and outer surfaces of the heated region; however, the effect of the temperature difference on the circumferentially average Nusselt number could be obtained by using the analytical solution of radially one-dimensional heat conduction. Using these results, a diagram showing the effect of wall conduction on heat transfer, which is useful for designing the circumferentially nonuniformly heated coolant passages, was obtained. (author)

Modelling aluminium wire bond reliability in high power OMP devices

NARCIS (Netherlands)

Kregting, R.; Yuan, C.A.; Xiao, A.; Bruijn, F. de

2011-01-01

In a RF power application such as the OMP, the wires are subjected to high current (because of the high power) and high temperature (because of the heat from IC and joule-heating from the wire itself). Moreover, the wire shape is essential to the RF performance. Hence, the aluminium wire is

Electrical power supply and controls for a remotely operated glass melter for nuclear waste

International Nuclear Information System (INIS)

Haideri, A.Q.

1985-01-01

An electrical power supply, controls and instruments used for a joule heated glass melter for nuclear waste are discussed. Remotely replaceable interconnection wiring assemblies for power, controls and instruments are also described

The long-term effects of a life-prolonging heat treatment on the Drosophila melanogaster transcriptome suggest that heat shock proteins extend lifespan

DEFF Research Database (Denmark)

Sarup, Pernille Merete; Sørensen, Peter; Loeschcke, Volker

2014-01-01

Heat-induced hormesis, i.e. the beneficial effect of mild heat-induced stress, increases the average lifespan of many organisms. This effect, which depends on the heat shock factor, decreases the log mortality rate weeks after the stress has ceased. To identify candidate genes that mediate......-treated flies. Several hsp70 probe sets were up-regulated 1.7–2-fold in the mildly stressed flies weeks after the last heat treatment (P shock protein, Hsp70, is reported to return to normal levels of expression shortly after heat stress. We...... conclude that the heat shock response, and Hsp70 in particular, may be central to the heat-induced increase in the average lifespan in flies that are exposed to mild heat stress early in life....

Heat generation and heating limits for the IRUS LLRW disposal facility

International Nuclear Information System (INIS)

Donders, R.E.; Caron, F.

1995-10-01

Heat generation from radioactive decay and chemical degradation must be considered when implementing low-level radioactive waste (LLRW) disposal. This is particularly important when considering the management of spent radioisotope sources. Heating considerations and temperature calculations for the proposed IRUS (Intrusion Resistant Underground Structure) near-surface disposal facility are presented. Heat transfer calculations were performed using a finite element code with realistic but somewhat conservative heat transfer parameters and environmental boundary conditions. The softening-temperature of the bitumen waste-form (38 deg C) was found to be the factor that limits the heat generation rate in the facility. This limits the IRUS heat rate, assuming a uniform source term, to 0.34 W/m 3 . If a reduced general heat-limit is considered, then some higher-heat packages can be accepted with restrictions placed on their location within the facility. For most LLRW, heat generation from radioactive decay and degradation are a small fraction of the IRUS heating limits. However, heating restrictions will impact on the disposal of higher-activity radioactive sources. High activity 60 Co sources will require decay-storage periods of about 70 years, and some 137 Cs will need to bed disposed of in facilities designed for higher-heat waste. (author). 21 refs., 8 tabs., 2 figs

Impact of parasitic thermal effects on thermoelectric property measurements by Harman method

International Nuclear Information System (INIS)

Kwon, Beomjin; Baek, Seung-Hyub; Keun Kim, Seong; Kim, Jin-Sang

2014-01-01

Harman method is a rapid and simple technique to measure thermoelectric properties. However, its validity has been often questioned due to the over-simplified assumptions that this method relies on. Here, we quantitatively investigate the influence of the previously ignored parasitic thermal effects on the Harman method and develop a method to determine an intrinsic ZT. We expand the original Harman relation with three extra terms: heat losses via both the lead wires and radiation, and Joule heating within the sample. Based on the expanded Harman relation, we use differential measurement of the sample geometry to measure the intrinsic ZT. To separately evaluate the parasitic terms, the measured ZTs with systematically varied sample geometries and the lead wire types are fitted to the expanded relation. A huge discrepancy (∼28%) of the measured ZTs depending on the measurement configuration is observed. We are able to separately evaluate those parasitic terms. This work will help to evaluate the intrinsic thermoelectric property with Harman method by eliminating ambiguities coming from extrinsic effects

Improvement in transdermal drug delivery performance by graphite oxide/temperature-responsive hydrogel composites with micro heater

International Nuclear Information System (INIS)

Yun, Jumi; Lee, Dae Hoon; Im, Ji Sun; Kim, Hyung-Il

2012-01-01

Transdermal drug delivery system (TDDS) was prepared with temperature-responsive hydrogel. The graphite was oxidized and incorporated into hydrogel matrix to improve the thermal response of hydrogel. The micro heater was fabricated to control the temperature precisely by adopting a joule heating method. The drug in hydrogel was delivered through a hairless mouse skin by controlling temperature. The efficiency of drug delivery was improved obviously by incorporation of graphite oxide due to the excellent thermal conductivity and the increased interfacial affinity between graphite oxide and hydrogel matrix. The fabricated micro heater was effective in controlling the temperature over lower critical solution temperature of hydrogel precisely with a small voltage less than 1 V. The cell viability test on graphite oxide composite hydrogel showed enough safety for using as a transdermal drug delivery patch. The performance of TDDS could be improved noticeably based on temperature-responsive hydrogel, thermally conductive graphite oxide, and efficient micro heater. - Graphical abstract: The high-performance transdermal drug delivery system could be prepared by combining temperature-responsive hydrogel, thermally conductive graphite oxide with improved interfacial affinity, and efficient micro heater fabricated by a joule heating method. Highlights: ► High performance of transdermal drug delivery system with an easy control of voltage. ► Improved thermal response of hydrogel by graphite oxide incorporation. ► Efficient micro heater fabricated by a joule heating method.

Effect of annealing on the second harmonic amplitude of Giant Magneto-Impedance (GMI) voltage of a Co-Fe-Si-B amorphous wire

Energy Technology Data Exchange (ETDEWEB)

Pal, S.K. [National Metallurgical Laboratory, Jamshedpur 831007 (India)], E-mail: skp@nmlindia.org; Panda, A.K.; Mitra, A. [National Metallurgical Laboratory, Jamshedpur 831007 (India)

2008-02-15

Second harmonic amplitude (V{sub 2f}) of Giant Magneto-Impedance (GMI) voltage of (Fe{sub 6}Co{sub 94}){sub 72.5}Si{sub 12.5}B{sub 15} amorphous wires has been studied systematically for as-cast and Joule-heated states. Joule heating was carried out at current densities (J) of 20-40 A/mm{sup 2} for a period of 1-300 min. The amplitude of the second harmonic voltage (V{sub 2f}) initially increased with J, attained maximum and then decreased. The maximum amplitude of V{sub 2f} was observed for the sample annealed at J=25 A/mm{sup 2} for 5 min. The second harmonic peak shifted towards the higher field side with the increase of annealing current density and annealing period (t{sub p}). Few-fold increase in the amplitude of the second harmonic voltage (V{sub 2f}) was observed due to the presence of a small dc bias current (I{sub b}) of amplitude 1 mA. The asymmetry in V{sub 2f} was also observed in a Joule-heated sample. The observed asymmetry has been correlated with the bias field generated between the surface crystallized layer and the amorphous core. A small bias current of amplitude of 1 mA was applied along the direction of the applied field to minimize the asymmetry.

A short-term supranutritional vitamin E supplementation alleviated respiratory alkalosis but did not reduce oxidative stress in heat stressed pigs.

Science.gov (United States)

Liu, Fan; Celi, Pietro; Chauhan, Surinder Singh; Cottrell, Jeremy James; Leury, Brian Joseph; Dunshea, Frank Rowland

2018-02-01

Heat stress (HS) triggers oxidative stress and respiratory alkalosis in pigs. The objective of this experiment was to study whether a short-term supranutritional amount of dietary vitamin E (VE) can mitigate oxidative stress and respiratory alkalosis in heat-stressed pigs. A total of 24 pigs were given either a control diet (17 IU/kg VE) or a high VE (200 IU/kg VE; HiVE) diet for 14 d, then exposed to thermoneutral (TN; 20°C, 45% humidity) or HS (35°C, 35% to 45% humidity, 8 h daily) conditions for 7 d. Respiration rate and rectal temperature were measured three times daily during the thermal exposure. Blood gas variables and oxidative stress markers were studied in blood samples collected on d 7. Although HiVE diet did not affect the elevated rectal temperature or respiration rate observed during HS, it alleviated (all prespiratory alkalosis but did not reduce oxidative stress in heat-stressed pigs.

Electrical energy use in different heating systems for early weaned piglets

Energy Technology Data Exchange (ETDEWEB)

Sarubbi, J. [Federal Univ. of Santa Maria, Palmeira das Missoes, RS (Brazil). Dept. of Animal Science; Campinas State Univ., Sao Paulo (Brazil). College of Agricultural Engineering; Rossi, L.A.; Moura, D.J.; Oliveira, R.A.; David, E. [Campinas State Univ., Sao Paulo (Brazil). College of Agricultural Engineering

2010-07-01

This study compared the electrical energy use and thermal comfort conditions associated with 3 heating technologies used in piglet farms. Heating systems for piglets in nursery and farrowing can be improved to conserve energy without affecting the welfare of the animals. The evaluation was conducted at a commercial farm in a subtropical climate area of Brazil. Each treatment involved 150 weaned piglets at 21 days-old. The systems were designed to keep the piglets at 28 to 30 degrees C for 14 days. Suspended electrical resistors, heated floors and convection heating were the 3 heating technologies examined during this study which evaluated the electrical energy consumption, maximum power demand requirements and dry-bulb temperature. The study also assessed the specific consumption in terms of kWh/kg of live produced body mass as well as the efficiency of heating system in terms of degrees C per cubic metre of air. In terms of electrical energy use, the best heating system was the heated floor. However, the electrical resistance heating system was the best in terms of thermal comfort.

The wire array Z-pinch: an efficient x-ray source for ICF and a new ion heating mechanism

Science.gov (United States)

Haines, M. G.

2008-10-01

The Z-pinch provides an efficient x-ray source for driving a hohlraum for inertial confinement fusion. The basic physics of wire-array implosions is reviewed. It can be understood in several sequential stages. Firstly, the wires heat and form a surrounding vapour which ionizes, causing the current to transfer to this lower resistance. The J×B global force leads to ejection of this plasma towards the axis to form a precursor plasma. The wire cores continue to ablate due to the heat flux from the Joule-heated nearby plasma. The cooling of this plasma by the wire-cores leads to a low magnetic Reynolds number so that the precursor plasma carries little or no current. When gaps appear in the liquid/vapour cores the plasma temperature and Reynolds number rise and this plasma accelerates in towards the axis carrying the current. This is the main implosion, and it sweeps up earlier ablated plasma, which acts to reduce Rayleigh-Taylor growth. At stagnation, the ion kinetic energy is thermalized and equipartition heats the electrons, which then radiate in a 5 ns pulse. In some conditions the energy radiated by soft x-rays exceeds the ion kinetic energy by a factor of 3 or 4. A theory has been developed to explain this in which fine-scale, fast growing m= 0 MHD instabilities grow to saturation, viscous dissipation of which leads to ion heating, followed by equipartition. World record ion temperatures of 2-3 billion Kelvin were predicted, and measured at Sandia National Laboratory. Lastly, progress in capsule implosions and in application to inertial fusion energy is reported.

Effects of heat transfer, friction and variable specific heats of working fluid on performance of an irreversible dual cycle

International Nuclear Information System (INIS)

Chen Lingen; Ge Yanlin; Sun Fengrui; Wu Chih

2006-01-01

The thermodynamic performance of an air standard dual cycle with heat transfer loss, friction like term loss and variable specific heats of working fluid is analyzed. The relations between the power output and the compression ratio, between the thermal efficiency and the compression ratio, as well as the optimal relation between power output and the efficiency of the cycle, are derived by detailed numerical examples. Moreover, the effects of variable specific heats of the working fluid and the friction like term loss on the irreversible cycle performance are analyzed. The results show that the effects of variable specific heats of working fluid and friction like term loss on the cycle performance are obvious, and they should be considered in practical cycle analysis. The results obtained in this paper may provide guidance for the design of practical internal combustion engines

A highly crystalline single Au wire network as a high temperature transparent heater

Science.gov (United States)

Rao, K. D. M.; Kulkarni, Giridhar U.

2014-05-01

A transparent conductor which can generate high temperatures finds important applications in optoelectronics. In this article, a wire network made of Au on quartz is shown to serve as an effective high temperature transparent heater. The heater has been fabricated by depositing Au onto a cracked sacrificial template. The highly interconnected Au wire network thus formed exhibited a transmittance of ~87% in a wide spectral range with a sheet resistance of 5.4 Ω □-1. By passing current through the network, it could be joule heated to ~600 °C within a few seconds. The extraordinary thermal performance and stability owe much to the seamless junctions present in the wire network. Furthermore, the wire network gets self-annealed through joule heating as seen from its increased crystallinity. Interestingly, both transmittance and sheet resistance improved following annealing to 92% and 3.2 Ω □-1, respectively. A transparent conductor which can generate high temperatures finds important applications in optoelectronics. In this article, a wire network made of Au on quartz is shown to serve as an effective high temperature transparent heater. The heater has been fabricated by depositing Au onto a cracked sacrificial template. The highly interconnected Au wire network thus formed exhibited a transmittance of ~87% in a wide spectral range with a sheet resistance of 5.4 Ω □-1. By passing current through the network, it could be joule heated to ~600 °C within a few seconds. The extraordinary thermal performance and stability owe much to the seamless junctions present in the wire network. Furthermore, the wire network gets self-annealed through joule heating as seen from its increased crystallinity. Interestingly, both transmittance and sheet resistance improved following annealing to 92% and 3.2 Ω □-1, respectively. Electronic supplementary information (ESI) available: Optical micrographs, EDAX, XRD, SEM and TEM images of Au metal wires. See DOI: 10.1039/c4nr00869c

Heat treatment of long term serviced Cr – Mo cast steel

Directory of Open Access Journals (Sweden)

G. Golanski

2010-01-01

Full Text Available The paper presents results of research on the influence of heat treatment on the structure and properties of L20HM cast steel after long term operation at elevated temperature. Investigated cast steel was taken out from an outer frame of a steam turbine serviced for 167 424 hours at the temp. of 535 oC and pressure 12.75 MPa. In post-operating condition the investigated cast steel was characterized by mechanical properties below the required minimum and by high brittleness. Performed research on the influence of austenitizing parameters has revealed that the range of austenitizing temperatures for the examined cast steel: Ac3 + 30 ÷ 60 oC ensures obtaining of a fine austenite grain, homogeneous in size. It has been proved that tempering of bainititc – ferritic structure above 680 ÷ 690 oC causes an increase of impact energy along with a decrease of mechanical properties below the required minimum. Moreover, it has been noticed that applying of under-annealing instead of tempering, after full-annealing, guarantees the required impact energy of KV > 27J, with the mechanical properties similar to those after service.

Large deviations in stochastic heat-conduction processes provide a gradient-flow structure for heat conduction

International Nuclear Information System (INIS)