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1

Joule heating versus `intrinsic' tunnelling in HTSC  

Microsoft Academic Search

I show that the `intrinsic tunnelling' (IT) characteristics of Bi2212 and Bi2201 can be reproduced if the heating caused by Joule dissipation is the only reason for nonlinearities observed in their current–voltage characteristics. Thus, experimental normal state c-axis resistance RN(T) and Newton's Law of Cooling provide a natural explanation of the divergency between the results obtained with conventional spectroscopy and

V. N. Zavaritsky

2004-01-01

2

An Analytical Model of Joule Heating in Piezoresistive Microcantilevers  

PubMed Central

The present study investigates Joule heating in piezoresistive microcantilever sensors. Joule heating and thermal deflections are a major source of noise in such sensors. This work uses analytical and numerical techniques to characterise the Joule heating in 4-layer piezoresistive microcantilevers made of silicon and silicon dioxide substrates but with the same U-shaped silicon piezoresistor. A theoretical model for predicting the temperature generated due to Joule heating is developed. The commercial finite element software ANSYS Multiphysics was used to study the effect of electrical potential on temperature and deflection produced in the cantilevers. The effect of piezoresistor width on Joule heating is also studied. Results show that Joule heating strongly depends on the applied potential and width of piezoresistor and that a silicon substrate cantilever has better thermal characteristics than a silicon dioxide cantilever.

Ansari, Mohd Zahid; Cho, Chongdu

2010-01-01

3

An analytical model of joule heating in piezoresistive microcantilevers.  

PubMed

The present study investigates Joule heating in piezoresistive microcantilever sensors. Joule heating and thermal deflections are a major source of noise in such sensors. This work uses analytical and numerical techniques to characterise the Joule heating in 4-layer piezoresistive microcantilevers made of silicon and silicon dioxide substrates but with the same U-shaped silicon piezoresistor. A theoretical model for predicting the temperature generated due to Joule heating is developed. The commercial finite element software ANSYS Multiphysics was used to study the effect of electrical potential on temperature and deflection produced in the cantilevers. The effect of piezoresistor width on Joule heating is also studied. Results show that Joule heating strongly depends on the applied potential and width of piezoresistor and that a silicon substrate cantilever has better thermal characteristics than a silicon dioxide cantilever. PMID:22163433

Ansari, Mohd Zahid; Cho, Chongdu

2010-11-01

4

Characterization of Joule heating in structured electric field environments  

Microsoft Academic Search

We have recently performed a detailed characterization of ion Joule heating perpendicular to an axial magnetic field in the laboratory in a simulated ionospheric plasma environment which contains localized electric field structuring. Since Joule heating is often regarded as an important mechanism contributing to energization of outflowing heavy ions observed by higher-altitude auroral satellites, this work has particular relevance to

David N. Walker; William E. Amatucci; Gurudas I. Ganguli

2001-01-01

5

Stability of graphene nanoribbon edges under high temperature joule heating  

NASA Astrophysics Data System (ADS)

Graphene nanoribbon edges have generated a lot of research interests recently, due to the different electronic properties of the ribbons arising from zigzag and armchair edges. Recent progress has shown that atomically smooth graphene nanoribbon edges can be produced using joule heating. In order to fully understand the joule heating process and study the stability of graphene nanoribbon edges, we investigated the temperature that is reached during the joule heating process using metal particles. Metal particles on a suspended ribbon melt and evaporate with enough resistive joule heating, thereby providing a temperature calibrator of the ribbon surface. The successive melting process also provides a temperature gradient along the ribbon length. Thermodynamic calculations are carried out to estimate the melting point of the nanoparticles as a function of decreasing size. We also investigated the different edge junctions that were formed after the joule heating process. Our results showed that certain types of zigzag-armchair edge junctions are more dominant. Another type of zigzag-armchair edge junction, which is unstable, was found to reconstruct to form a stable edge junction during joule heating.

Jia, Xiaoting; Hofmann, Mario; Meunier, Vincent; Sumpter, Bobby; Campos-Delgado, Jessica; Romo-Herrera, Jose; Kong, Jing; Terrones, Mauricio; Dresselhaus, Mildred

2010-03-01

6

Strong substrate effects of Joule heating in graphene electronics  

NASA Astrophysics Data System (ADS)

The effect of Joule heating on graphene electronic properties is investigated by self-consistent use of full-band Monte Carlo electron dynamics and three-dimensional heat transfer simulations. Several technologically important substrate materials are examined: SiO2, SiC, hexagonal BN, and diamond. Results illustrate that the choice of substrate has a major impact via heat conduction and surface polar phonon scattering. Particularly, the poor thermal conductivity of SiO2 leads to significant Joule heating and saturation velocity degradation in graphene characterized by the 1/n decay. Considering the overall characteristics, BN appears to compare favorably against the other substrate choices for graphene electronic applications.

Li, X.; Kong, B. D.; Zavada, J. M.; Kim, K. W.

2011-12-01

7

Joule Heating of the South Polar Terrain on Enceladus  

NASA Astrophysics Data System (ADS)

Accounting for the plumes and observed heat flux in the South Polar Terrain of Enceladus remains largely a mystery. We report that Joule heating in Enceladus may account for several, to a few tens of megawatts of power across the observed “tiger stripe” fractures. Electric currents passing through subsurface channels of low salinity and just a few kilometres in depth could supply a source of power to the South Polar Terrain, providing a small but previously unaccounted for contribution to the observed heat flux and plume activity. Examinations of electrical heating in the Jupiter system have led to conclusions that it is unimportant; however at Enceladus such heating may be an important contribution to localized heating and the persistence of the tiger stripes. The exclusion of salt ions during refreezing serves to enhance volumetric Joule heating and extend the lifetime of liquid water fractures in the South Polar Terrain.

Hand, K. P.; Khurana, K. K.; Chyba, C. F.

2009-12-01

8

Joule heating of the south polar terrain on Enceladus  

NASA Astrophysics Data System (ADS)

We report that Joule heating in Enceladus, resulting from the interaction of Enceladus with Saturn's magnetic field, may account for 150 kW to 52 MW of power through Enceladus. Electric currents passing through subsurface channels of low salinity and just a few kilometers in depth could supply a source of power to the south polar terrain, providing a small but previously unaccounted for contribution to the observed heat flux and plume activity. Studies of the electrical heating of Jupiter's moon Europa have concluded that electricity is a negligible heating source since no connection between the conductive subsurface and Alfvén currents has been observed. Here we show that, contrary to results for the Jupiter system, electrical heating may be a source of internal energy for Enceladus, contributing to localized heating, production of water vapor, and the persistence of the “tiger stripes.” This contribution is of order 0.001-0.25% of the total observed heat flux, and thus, Joule heating cannot explain the total south polar terrain heat anomaly. The exclusion of salt ions during refreezing serves to enhance volumetric Joule heating and could extend the lifetime of liquid water fractures in the south polar terrain.

Hand, K. P.; Khurana, K. K.; Chyba, C. F.

2011-04-01

9

Joule heating and anomalous resistivity in the solar corona  

Microsoft Academic Search

Recent radioastronomical observations of Faraday rotation in the solar corona can be interpreted as evidence for coronal currents, with values as large as 2.5×109 Amperes (Spangler, 2007). These estimates of currents are used to develop a model for Joule heating in the corona. It is assumed that the currents are concentrated in thin current sheets, as suggested by theories of

S. R. Spangler

2009-01-01

10

Joule heating of a titanium rod  

NSDL National Science Digital Library

Use the steady-state heat conduction solution for constant heat generation in a rod to determine the maximum temperature difference between the center and surface of a titanium rod heated by electric current; also sketch temperature history from the time when current is turned on.

Powell, Adam C., IV

2002-10-04

11

Joule heating and anomalous resistivity in the solar corona  

Microsoft Academic Search

Recent radioastronomical observations of Faraday rotation in the solar corona\\u000acan be interpreted as evidence for coronal currents, with values as large as\\u000a$2.5 \\\\times 10^9$ Amperes (Spangler 2007). These estimates of currents are used\\u000ato develop a model for Joule heating in the corona. It is assumed that the\\u000acurrents are concentrated in thin current sheets, as suggested by

Steven R. Spangler

2009-01-01

12

Joule heating in packed capillaries used in capillary electrochromatography.  

PubMed

Effective heat dissipation is critical for reproducible and efficient separations in electrically driven separation systems. Flow rate, retention kinetics, and analyte diffusion rates are some of the characteristics that are affected by variation in the temperature of the mobile phase inside the column. In this study, we examine the issue of Joule heating in packed capillary columns used in capillary electrochromatography (CEC). As almost all commonly used CEC packings are poor thermal conductors, it is assumed that the packing particles do not conduct heat and heat transfer is solely through the mobile phase flowing through the system. The electrical conductivity of various mobile phases was measured at different temperatures by a conductivity meter and the temperature coefficient for each mobile phase was calculated. This was followed by measurement of the electrical current at several applied voltages to calculate the conductivity of the solution within the column as a function of the applied voltage. An overall increase in the conductivity is attributed to Joule heating within the column, while a constant conductivity means good heat dissipation. A plot of conductivity versus applied voltage was used as the indicator of poor heat dissipation. Using theories that have been proposed earlier for modeling of Joule heating effects in capillary electrophoresis (CE), we estimated the temperature within CEC columns. Under mobile and stationary phase conditions typically used in CEC, heat dissipation was found to be not always efficient. Elevated temperatures within the columns in excess of 23 degrees C above ambient temperature were calculated for packed columns, and about 35 degrees C for an open column, under a given set of conditions. The results agree with recently published experimental findings with nuclear magnetic resonance (NMR) thermometry, and Raman spectroscopic measurements. PMID:12207300

Rathore, Anurag S; Reynolds, Kimberly J; Colón, Luis A

2002-09-01

13

Joule heating and anomalous resistivity in the solar corona  

NASA Astrophysics Data System (ADS)

Recent radioastronomical observations of Faraday rotation in the solar corona can be interpreted as evidence for coronal currents, with values as large as 2.5×109 Amperes (Spangler, 2007). These estimates of currents are used to develop a model for Joule heating in the corona. It is assumed that the currents are concentrated in thin current sheets, as suggested by theories of two dimensional magnetohydrodynamic turbulence. The Spitzer result for the resistivity is adopted as a lower limit to the true resistivity. The calculated volumetric heating rate is compared with an independent theoretical estimate by Cranmer et al. (2007). This latter estimate accounts for the dynamic and thermodynamic properties of the corona at a heliocentric distance of several solar radii. Our calculated Joule heating rate is less than the Cranmer et al estimate by at least a factor of 3×105. The currents inferred from the observations of Spangler (2007) are not relevant to coronal heating unless the true resistivity is enormously increased relative to the Spitzer value. However, the same model for turbulent current sheets used to calculate the heating rate also gives an electron drift speed which can be comparable to the electron thermal speed, and larger than the ion acoustic speed. It is therefore possible that the coronal current sheets are unstable to current-driven instabilities which produce high levels of waves, enhance the resistivity and thus the heating rate.

Spangler, S. R.

2009-06-01

14

Physical and numerical modeling of Joule-heated melters  

SciTech Connect

The Joule-heated ceramic-lined melter is an integral part of the high level waste immobilization process under development by the US Department of Energy. Scaleup and design of this waste glass melting furnace requires an understanding of the relationships between melting cavity design parameters and the furnace performance characteristics such as mixing, heat transfer, and electrical requirements. Developing empirical models of these relationships through actual melter testing with numerous designs would be a very costly and time consuming task. Additionally, the Pacific Northwest Laboratory (PNL) has been developing numerical models that simulate a Joule-heated melter for analyzing melter performance. This report documents the method used and results of this modeling effort. Numerical modeling results are compared with the more conventional, physical modeling results to validate the approach. Also included are the results of numerically simulating an operating research melter at PNL. Physical Joule-heated melters modeling results used for qualiying the simulation capabilities of the melter code included: (1) a melter with a single pair of electrodes and (2) a melter with a dual pair (two pairs) of electrodes. The physical model of the melter having two electrode pairs utilized a configuration with primary and secondary electrodes. The principal melter parameters (the ratio of power applied to each electrode pair, modeling fluid depth, electrode spacing) were varied in nine tests of the physical model during FY85. Code predictions were made for five of these tests. Voltage drops, temperature field data, and electric field data varied in their agreement with the physical modeling results, but in general were judged acceptable. 14 refs., 79 figs., 17 tabs.

Eyler, L.L.; Skarda, R.J.; Crowder, R.S. III; Trent, D.S.; Reid, C.R.; Lessor, D.L.

1985-10-01

15

Physical and numerical modeling of Joule-heated melters  

NASA Astrophysics Data System (ADS)

The Joule-heated ceramic-lined melter is an integral part of the high level waste immobilization process under development by the US Department of Energy. Scaleup and design of this waste glass melting furnace requires an understanding of the relationships between melting cavity design parameters and the furnace performance characteristics such as mixing, heat transfer, and electrical requirements. Developing empirical models of these relationships through actual melter testing with numerous designs would be a very costly and time consuming task. Additionally, the Pacific Northwest Laboratory (PNL) has been developing numerical models that simulate a Joule-heated melter for analyzing melter performance. This report documents the method used and results of this modeling effort. Numerical modeling results are compared with the more conventional, physical modeling results to validate the approach. Also included are the results of numerically simulating an operating research melter at PNL. Physical Joule-heated melters modeling results used for qualiying the simulation capabilities of the melter code included: (1) a melter with a single pair of electrodes and (2) a melter with a dual pair (two pairs) of electrodes. The physical model of the melter having two electrode pairs utilized a configuration with primary and secondary electrodes. The principal melter parameters (the ratio of power applied to each electrode pair, modeling fluid depth, electrode spacing) were varied in nine tests of the physical model during FY85. Code predictions were made for five of these tests. Voltage drops, temperature field data, and electric field data varied in their agreement with the physical modeling results, but in general were judged acceptable.

Eyler, L. L.; Skarda, R. J.; Crowder, R. S., III; Trent, D. S.; Reid, C. R.; Lessor, D. L.

1985-10-01

16

Breaking single-walled carbon nanotube bundles by Joule heating  

NASA Astrophysics Data System (ADS)

Electrical breakdown induced by Joule heating was employed to make a well-aligned surface structure from single-walled carbon nanotube (SWCNT) bundles. The surfaces at the breaking ends are tip abundant and composed of SWCNTs of high quality. In addition, the radial breathing mode frequencies of the CNT tips have a downshift than the as-grown SWCNTs, due to the higher thermal stability of wider SWCNTs and the strong intertube interactions. The ends can provide emission currents of about 100 ?A, and a pixel based on these potential electron emitters was developed for lateral field emission displays.

Wei, Yang; Liu, Peng; Jiang, Kaili; Liu, Liang; Fan, Shoushan

2008-07-01

17

Joule heating of the Jovian ionosphere by corotation enforcement currents  

NASA Astrophysics Data System (ADS)

A simple magnetodisk model is used to estimate the Joule heating rate, for several causes of departure from the corotation during whose enforcement heat is deposited on the Jovian magnetosphere. Following compression or expansion of the magnetosphere, the magnetospheric plasma sub- or super-rotates due to conservation of angular momentum and thermal energy is deposited in the ionosphere at a rate of 10 to the 12th W for 100,000 sec while rotational speed is adjusted toward the corotation with the planet. Day-night asymmetry in trajectory of rotational motion of plasma, due to magnetospheric configuration asymmetry, may also produce energy dissipation of a similar magnitude as the rotational speed is adjusted. The corotation enforcement current therefore deposits as much heat as the dynamo current from Io, and plays an important role in the energetics and dynamics of the Jovian magnetosphere.

Nishida, A.; Watanabe, Y.

1981-11-01

18

Electro-osmotic infusion for joule heating soil remediation techniques  

DOEpatents

Electro-osmotic infusion of ground water or chemically tailored electrolyte is used to enhance, maintain, or recondition electrical conductivity for the joule heating remediation technique. Induced flows can be used to infuse electrolyte with enhanced ionic conductivity into the vicinity of the electrodes, maintain the local saturation of near-electrode regions and resaturate a partially dried out zone with groundwater. Electro-osmotic infusion can also tailor the conductivity throughout the target layer by infusing chemically modified and/or heated electrolyte to improve conductivity contrast of the interior. Periodic polarity reversals will prevent large pH changes at the electrodes. Electro-osmotic infusion can be used to condition the electrical conductivity of the soil, particularly low permeability soil, before and during the heating operation. Electro-osmotic infusion is carried out by locating one or more electrodes adjacent the heating electrodes and applying a dc potential between two or more electrodes. Depending on the polarities of the electrodes, the induced flow will be toward the heating electrodes or away from the heating electrodes. In addition, electrodes carrying a dc potential may be located throughout the target area to tailor the conductivity of the target area.

Carrigan, Charles R. (Tracy, CA); Nitao, John J. (Castro Valley, CA)

1999-01-01

19

On the Role of Hall and Pedersen Conductivities in Determination of Ionospheric Joule Heating  

NASA Astrophysics Data System (ADS)

Ionospheric Joule heating is defined as the frictional heating which results from the collisions between the neutrals and charged particles at the ionospheric heights. These collisional processes gain importance around 120 km in the E and F regions of the ionosphere where there are more neutral atoms, and particularly at the auroral altitudes, where Hall and Pedersen conductivities are comparable to each other. The most conventional ways of calculating ionospheric Joule heating relies on the relationship between electric field and Pedersen conductivity. The role of Hall conductivity in the calculation of Joule heating still remains unclear, and in general its contribution is accepted to be minor when compared to the Pedersen currents at the first approximation. However, results from the MHD simulations show that Joule heating is reduced in the regions where Hall conductivity is close to or higher than Pedersen conductivity. These local variations also modify the global Joule heating pattern and distribution. MHD models take into account the magnetosphere and ionosphere interaction and incorporate with the ionospheric modules which include the interaction between the neutral winds and charged paricles. In this study, we have selected two isolated substorm events that occurred in March, 2008 to investigate the effects of Hall conductivity on the Joule heating. We run NASA/CCMC MHD models, e.g. SWMF/BATSRUS, during these times under concurrent solar wind and IMF conditions. The outputs from the models will be used to calculate Joule heating with the Hall conductivity effects properly included. In this presentation, we will show our preliminary results on the Joule heating rates from the models, quantify the degree of Pedersen and Hall conductivity contributions on the Joule heating, and address on their contributions on the global distribution of the Joule heating. We will also compare and discuss our findings with those available in the literature.

Ceren Kalafatoglu, Emine; Kaymaz, Zerefsan

2013-04-01

20

Height distribution of Joule heating and its influence on the thermosphere  

NASA Astrophysics Data System (ADS)

The National Center for Atmospheric Research Thermosphere-Ionosphere-Electrodynamics General Circulation Model (NCAR TIE-GCM) is employed to quantify the influence of Joule heating at different altitudes on the neutral temperature and density at 400 km for solar minimum and maximum conditions. The results show that high-altitude Joule heating is more efficient than low-altitude heating in affecting the upper thermosphere. Most of the Joule heating is deposited under 150 km, and the largest Joule heating deposition per scale height happens at about 125 km, independent of solar activity. However, the temperature and density changes at 400 km are largest for heat deposited at ˜140 km for solar minimum and ˜263 km for solar maximum. The timescale for the thermospheric response varies with the altitude of heating. Joule heating deposited at lower heights needs more time to conduct upward, and it takes more time for the thermosphere at 400 km to approach a steady state. A simple one-dimensional model is utilized to explain how the amplitude and characteristic timescale of the upper-thermosphere response to Joule heating depends on the height of heat input. The characteristic response timescale for heat deposited around 135 km is ˜6 hours, while that for heat deposited around 238 km is ˜0.5 hours. The initial temperature response at 400 km to the high-altitude heating is much stronger than the response to the low-altitude heating, but the responses become comparable after about 4 days.

Huang, Yanshi; Richmond, Arthur D.; Deng, Yue; Roble, Ray

2012-08-01

21

Magnetostriction and GMI in Joule-heated CoFeSiB glass-covered microwires  

Microsoft Academic Search

Magnetic properties (magnetostricition and hysteresis loops) and giant magnetoimpedance (GMI) are investigated in CoFeSiB amorphous glass-covered microwires Joule-heated with or without axial applied stress.

K. R. Pirota; L. Kraus; H. Chiriac; M. Knobel

2001-01-01

22

Ion Energy Balance at Joule Heating in the ''Tokamak-11'' Device.  

National Technical Information Service (NTIS)

Technique for reconstruction of the ion temperature and neutral atoms density radial distributions from chord measurements of charge- exchange atom fluxes are described. Result of plasma energy balance study at joule heating for discharges with various pl...

V. M. Leonov

1981-01-01

23

Coherent radar estimates of average high-latitude ionospheric Joule heating  

SciTech Connect

The Scandinavian Twin Auroral Radar Experiment (STARE) and Sweden and Britain Radar Experiment (SABRE) bistatic coherent radar systems have been employed to estimate the spatial and temporal variation of the ionospheric Joule heating in the combined geographic latitude range 63.8 deg - 72.6 deg (corrected geomagnetic latitude 61.5 deg - 69.3 deg) over Scandinavia. The 173 days of good observations with all four radars have been analyzed during the period 1982 to 1986 to estimate the average ionospheric electric field versus time and latitude. The AE dependent empirical model of ionospheric Pedersen conductivity of Spiro et al. (1982) has been used to calculate the Joule heating. The latitudinal and diurnal variation of Joule heating as well as the estimated mean hemispherical heating of 1.7 x 10(exp 11) W are in good agreement with earlier results. Average Joule heating was found to vary linearly with the AE, AU, and AL indices and as a second-order power law with Kp. The average Joule heating was also examined as a function of the direction and magnitude of the interplanetary magnetic field. It has been shown for the first time that the ionospheric electric field magnitude as well as the Joule heating increase with increasingly negative (southward) Bz.

Kosch, M.J.; Nielsen, E. [Max-Planck-Institut fuer Aeronomie, Katlenburg-Lindau (Germany)

1995-07-01

24

Joule heating effect on electroosmotic flow and mass species transport in a microcapillary  

Microsoft Academic Search

This study presents a numerical analysis of Joule heating effect on the electroosmotic flow and mass species transport, which has a direct application in the capillary electrophoresis based BioChip technology. A rigorous mathematic model for describing the Joule heating in an electroosmotic flow including the Poisson–Boltzmann equation, the modified Navier–Stokes equations and the energy equation is developed. All these equations

G. Y. Tang; C. Yang; J. C. Chai; H. Q. Gong

2004-01-01

25

Effects of Current Crowding and Joule Heating on Reliability of Solder Joints  

NASA Astrophysics Data System (ADS)

This study employs three-dimensional simulation to investigate the Joule heating effect under accelerated electromigration tests in flip-chip solder joints. It was found that the Joule heating effect was very seriously during high current stressing, and a hot spot exists in the solder bump. The hot-spot may play important role in the void formation and thermomigration in solder bumps during electromigration.

Liang, S. W.; Chiu, S. H.; Chen, Chih

2007-10-01

26

Thermal output of a current-carrying ferromagnetic wire: hysteresis loss versus Joule heat  

NASA Astrophysics Data System (ADS)

When an alternating current flows through a ferromagnetic wire, its thermal output is higher than predicted by the familiar Joule law. An additional contribution arises from the heat liberated due to the hysteresis loss in the self-induced magnetic field inside the wire. Simple calculations, based on the formulae derived here, show that in some cases this contribution may be comparable to, or even larger than, the Joule heat.

Ogorelec, Z.

1999-05-01

27

Low-grade thermal energy-conversion Joule effect heat engines  

Microsoft Academic Search

Low-grade thermal energy conversion is discussed with attention to energy sources, heat engines, and potential Joule engine applications. Nitinol heat engine concepts are discussed, and the Nitinol equation-of-state surfaces and transition characteristics are indicated. Bottoming cycles are considered, the untapped low-temperature water energy sources are estimated, the heat-transfer limitation of gas phase heat engines is examined, and solid-state heat engines

W. S. Ginell; J. L. McNichols; J. S. Cory

1978-01-01

28

The current sheet and Joule heating of a slender magnetic tube in the upper photosphere  

NASA Astrophysics Data System (ADS)

Joule heating in a slender magnetic flux tube is investigated. To ensure the mass flux conservation, an overshooting convective flow pattern resembling recent simulations was assumed. Even with the electrical resistivity from neutral hydrogen, the width of the current sheet was found to be about 2 km, being much smaller than the tube diameter of about 150 km, either from an exact or approximate (Gaussian) field distribution. The resultant energy flux density due to Joule heating averaged over the cylindrical cross sectional area is about 1 x 10 exp 9 erg/sq cm per sec for an assumed photospheric magnetic field of 1500 G. This amount may supply enough energy to heat the temperature minimum region of the flux tube by Delta T = 300 K in accord with observations, though the estimation of the excess radiation loss which should be supplied by the Joule heating to keep Delta T = 300 K is rather uncertain. A possible role of the Joule heating on spicule formation is briefly discussed together with discussions on the slab geometry, general flow patterns, and nonconstant field distributions inside the flux tube.

Hirayama, T.

1992-01-01

29

Size-dependent joule heating of gold nanoparticles using capacitively coupled radiofrequency fields  

Microsoft Academic Search

Capacitively coupled shortwave radiofrequency fields (13.56 MHz) resistively heat low concentrations (?1 ppm) of gold nanoparticles\\u000a with a thermal power dissipation of ?380 kW\\/g of gold. Smaller diameter gold nanoparticles (< 50 nm) heat at nearly twice\\u000a the rate of larger diameter gold nanoparticles (?50 nm), which is attributed to the higher resistivity of smaller gold nanostructures.\\u000a A Joule heating

Christine H. Moran; Sean M. Wainerdi; Tonya K. Cherukuri; Carter Kittrell; Benjamin J. Wiley; Nolan W. Nicholas; Steven A. Curley; John S. Kanzius; Paul Cherukuri

2009-01-01

30

Discretization of the Joule heating term for plasma discharge fluid models in unstructured meshes  

SciTech Connect

The fluid (continuum) approach is commonly used for simulation of plasma phenomena in electrical discharges at moderate to high pressures (>10's mTorr). The description comprises governing equations for charged and neutral species transport and energy equations for electrons and the heavy species, coupled to equations for the electromagnetic fields. The coupling of energy from the electrostatic field to the plasma species is modeled by the Joule heating term which appears in the electron and heavy species (ion) energy equations. Proper numerical discretization of this term is necessary for accurate description of discharge energetics; however, discretization of this term poses a special problem in the case of unstructured meshes owing to the arbitrary orientation of the faces enclosing each cell. We propose a method for the numerical discretization of the Joule heating term using a cell-centered finite volume approach on unstructured meshes with closed convex cells. The Joule heating term is computed by evaluating both the electric field and the species flux at the cell center. The dot product of these two vector quantities is computed to obtain the Joule heating source term. We compare two methods to evaluate the species flux at the cell center. One is based on reconstructing the fluxes at the cell centers from the fluxes at the face centers. The other recomputes the flux at the cell center using the common drift-diffusion approximation. The reconstructed flux scheme is the most stable method and yields reasonably accurate results on coarse meshes.

Deconinck, T.; Mahadevan, S. [Dept. of Aerospace Engineering and Engineering Mechanics, University of Texas at Austin, Austin, TX 78712 (United States); Raja, L.L. [Dept. of Aerospace Engineering and Engineering Mechanics, University of Texas at Austin, Austin, TX 78712 (United States)], E-mail: lraja@mail.utexas.edu

2009-07-01

31

Ionospheric Joule heating and Poynting flux in quasi-static approximation  

NASA Astrophysics Data System (ADS)

Energy flow is an important aspect of magnetosphere-ionosphere coupling. Electromagnetic energy is transported as Poynting flux from the magnetosphere to the ionosphere, where it is dissipated as Joule heating. Recently Richmond derived an "Equipotential Boundary Poynting Flux (EBPF) theorem", that the Poynting flux within a flux tube whose boundary is an equipotential curve is dissipated inside the ionospheric foot point of the flux tube. In this article we study Richmond's EBPF theorem more closely by considering the curl-free and divergence-free parts as well as the Hall and Pedersen parts of the ionospheric current system separately. Our main findings are that i) divergence-free currents are on average dissipationless, ii) the curl-free Pedersen current is responsible for the whole ionospheric Joule heating and iii) pointwise match between vertical Poynting flux and ionospheric Joule heating is broken by gradients of Hall and Pedersen conductances. Results i) and ii) hold when integrated over the whole ionosphere or any area bounded by an equipotential curve. The present study is limited to quasi-static phenomena. The more general topic of electrodynamic Joule heating and Poynting flux, including inductive effects, will be addressed in a future study.

VanhamäKi, H.; Yoshikawa, A.; Amm, O.; Fujii, R.

2012-08-01

32

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

SciTech Connect

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.

KELLY SE

2011-04-07

33

Joule heat generation in thermionic cathodes of high-pressure arc discharges  

NASA Astrophysics Data System (ADS)

The nonlinear surface heating model of plasma-cathode interaction in high-pressure arcs is extended to take into account the Joule effect inside the cathode body. Calculation results are given for different modes of current transfer to tungsten cathodes of different configurations in argon plasmas of atmospheric or higher pressures. Special attention is paid to analysis of energy balances of the cathode and the near-cathode plasma layer. In all the cases, the variation of potential inside the cathode is much smaller than the near-cathode voltage drop. However, this variation can be comparable to the volt equivalent of the energy flux from the plasma to the cathode and then the Joule effect is essential. Such is the case of the diffuse and mixed modes on rod cathodes at high currents, where the Joule heating causes a dramatic change of thermal and electrical regimes of the cathode. The Joule heating has virtually no effect over characteristics of spots on rod and infinite planar cathodes.

Benilov, M. S.; Cunha, M. D.

2013-02-01

34

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

National Technical Information Service (NTIS)

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 ...

J. A. Dominques L. Sibille

2012-01-01

35

Large-Scale Synthesis of Graphene Films by Joule-Heating-Induced Chemical Vapor Deposition  

Microsoft Academic Search

We report large-area synthesis of few-layer graphene films by chemical vapor deposition (CVD) in a cold-wall reactor. The key feature of this method is that the catalytic metal layers on the SiO2\\/Si substrates are self-heated to high growth temperature (900°C to 1000°C) by high-current Joule heating. Synthesis of high-quality graphene films, whose structural and electrical characteristics are comparable to those

Jung Min Lee; Hae Yong Jeong; Won Il Park

2010-01-01

36

STUDY OF BEHAVIOR IN THE HEAT EXCHANGER OF A MIXED GAS JOULE-THOMSON COOLER  

Microsoft Academic Search

The object of the investigation is a mixed gas Joule-Thomson (J-T) cooler. A computa- tional model was developed, which makes it possible to investigate the steady state behavior of the refrigerant in the heat exchanger of a mixed gas J-T system. The calculations show that the temperature distribution as well as the pressure distribution in the heat exchanger channels depends

A. Alexeev; A. Thiel; Ch. Haberstroh; H. Quack

37

Jupiter Thermospheric General Circulation Model (JTGCM): Global structure and dynamics driven by auroral and Joule heating  

NASA Astrophysics Data System (ADS)

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-?bar (capturing hydrocarbon cooling) to 1.0 × 10-4 nbar (including auroral/Joule heating processes). The resulting JTGCM has been fully spun-up and integrated for >=40 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 ~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 ASI 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.

Bougher, S. W.; Waite, J. H.; Majeed, T.; Gladstone, G. R.

2005-04-01

38

Microstructural and electrical characterization of Joule heat welds in ultrathin Pt wires  

NASA Astrophysics Data System (ADS)

This paper reports on the structural and electrical characteristics of Joule heat welds in ultrathin Pt wires with diameters of 600-800 nm. The wires have a bamboo structure where the crystal grains are aligned only in the axial direction. They were welded together in a self-completed manner in air by Joule heating. The electrical resistance of the welded wire system was measured using a potential drop technique. It was found by transmission electron microscope observations that the region affected by welding was very narrow and it appeared that a new grain boundary had been created in this region. Moreover, the welds were found to have good electrical characteristics and the electrical resistance at the weld depended on its cross-sectional area.

Tohmyoh, Hironori; Fujimori, Masato

2012-09-01

39

Role of joule heating in electrically-driven metal insulator transition in vanadium oxide nanowires  

NASA Astrophysics Data System (ADS)

Metal to insulator transition (MIT) in vanadium oxide system can be triggered by several external stimuli such as temperature, electric field, strain and light. Electrically driven MIT in single nanowire devices of crystalline vanadium oxide (W- doped VO2, Ag-doped V2O5) is the topic of current study. Recent works on realizing switching devices using these materials have discussed the importance of Joule heating near the transition as supposed to a purely electric field induced effect. We propose a novel method for identifying the individual roles of Joule heating and/or electric field by analyzing the frequency response of the AC electric signal near the MIT in these devices. The method may also be used in other strongly correlated electron system to delineate the roles of individual microscopic conduction mechanisms near MIT.

Singh, Sujay; Shi, Zhenzhong; Kwan, Chun Pui; Marley, Peter; Banerjee, Sarbajit; Sambandamurthy, Ganapathy

2013-03-01

40

Off-gas characteristics of liquid-fed joule-heated ceramic melters  

SciTech Connect

The off-gas characteristics of liquid-fed joule-heated ceramic melters have been investigated as a function of melter operational condition and simulated waste feed composition. The results of these studies have established the identity and behavior patterns of gaseous emissions, the characteristics of melter-generated aerosols, the nature and magnitude of melter effluent losses and the factors affecting melter operational performance. 8 figures, 16 tables.

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

1982-06-01

41

The role of Joule heating in dispersive mixing effects in electrophoretic cells: hydrodynamic considerations.  

PubMed

The analysis described in this contribution is focused on the effect of Joule heating generation on the hydrodynamics of batch electrophoretic cells (i.e., cells that do not display a forced convective term in the motion equation). The hydrodynamics of these cells is controlled by the viscous forces and by the buoyancy force caused by the temperature gradients due to the Joule heating generation. The analysis is based on differential models that lead to analytical and/or asymptotic solutions for the temperature and velocity profiles of the cell. The results are useful in determining the characteristics of the temperature and velocity profiles inside the cell. Furthermore, the results are excellent tools to be used in the analysis of the dispersive-mixing of solute when Joule heating generation must be accounted for. The analysis is performed by identifying two sequentially coupled problems. Thus, the "carrier fluid problem" and the "solute problem" are outlined. The former is associated with all the factors affecting the velocity profile and the latter is related to the convective-diffusion aspects that control the spreading of the solute inside the cell. The analysis of this contribution is centered on the discussion of the "carrier fluid problem" only. For the boundary conditions selected in the contribution, the study leads to the derivation of an analytical temperature and a "universal" velocity profile that feature the Joule heating number. The Grashof number is a scaling factor of the actual velocity profile. Several characteristics of these profiles are studied and some numerical illustrations have been included. PMID:10768789

Bosse, M A; Arce, P

2000-03-01

42

Current-controlled negative differential resistance due to Joule heating in TiO2  

Microsoft Academic Search

We show that Joule heating causes current-controlled negative differential resistance (CC-NDR) in TiO2 by constructing an analytical model of the voltage-current V(I) characteristic based on polaronic transport for Ohm's Law and Newton's Law of Cooling and fitting this model to experimental data. This threshold switching is the ``soft breakdown'' observed during electroforming of TiO2 and other transition-metal-oxide based memristors, as

A. S. Alexandrov; A. M. Bratkovsky; B. Bridle; S. E. Savel'Ev; D. B. Strukov; R. Stanley Williams

2011-01-01

43

Assessment of Joule heating and its effects on electroosmotic flow and electrophoretic transport of solutes in microfluidic channels.  

PubMed

Joule heating is inevitable when an electric field is applied across a conducting medium. It would impose limitations on the performance of electrokinetic microfluidic devices. This article presents a 3-D mathematical model for Joule heating and its effects on the EOF and electrophoretic transport of solutes in microfluidic channels. The governing equations were numerically solved using the finite-volume method. Experiments were carried out to investigate the Joule heating associated phenomena and to verify the numerical models. A rhodamine B-based thermometry technique was employed to measure the solution temperature distributions in microfluidic channels. The microparticle image velocimetry technique was used to measure the velocity profiles of EOF under the influence of Joule heating. The numerical solutions were compared with experimental results, and reasonable agreement was found. It is found that with the presence of Joule heating, the EOF velocity deviates from its normal "plug-like" profile. The numerical simulations show that Joule heating not only accelerates the sample transport but also distorts the shape of the sample band. PMID:16456892

Tang, Gongyue; Yan, Deguang; Yang, Chun; Gong, Haiqing; Chai, John Chee; Lam, Yee Cheong

2006-02-01

44

Large-Scale Synthesis of Graphene Films by Joule-Heating-Induced Chemical Vapor Deposition  

Microsoft Academic Search

We report large-area synthesis of few-layer graphene films by chemical vapor deposition (CVD) in a cold-wall reactor. The\\u000a key feature of this method is that the catalytic metal layers on the SiO2\\/Si substrates are self-heated to high growth temperature (900°C to 1000°C) by high-current Joule heating. Synthesis of high-quality\\u000a graphene films, whose structural and electrical characteristics are comparable to those

Jung Min Lee; Hae Yong Jeong; Won Il Park

2010-01-01

45

Global Joule heating index derived from thermospheric density physics-based modeling and observations  

NASA Astrophysics Data System (ADS)

The primary operational impact of upper atmospheric neutral density variability is on satellite drag. Drag is the most difficult force to model mainly because of the complexity of neutral atmosphere variations driven by solar UV and EUV radiation power, magnetospheric energy input, and the propagation from below of lower atmosphere waves. Taking into account the self-consistent interactions between neutral winds, composition, ion drifts, and ionization densities, first-principles models are able to provide a more realistic representation of neutral density than empirical models in the upper atmosphere. Their largest sources of uncertainty, however, are the semiannual variations in neutral density and the magnitude, spatial distribution, and temporal evolution of the magnetospheric energy input. In this study, results from the physics-based coupled thermosphere-ionosphere-plasmasphere electrodynamics (CTIPe) model and measurements from the CHAMP satellite are compared and used to improve the modeled thermospheric neutral density estimates. The good agreement between modeled and observed densities over an uninterrupted yearlong period of variable conditions gives confidence that the thermosphere-ionosphere system energy influx from solar radiation and magnetospheric sources is reasonable and that Joule heating, the dominant source during geomagnetically disturbed conditions, is appropriately estimated. On the basis of the correlation between neutral density and energy injection, a global time-dependent Joule heating index (JHI) is derived from the relationship between Joule heating computed by the CTIPe model and neutral density measured by the CHAMP satellite. Preliminary results show an improvement in density estimates using CTIPe JHI, demonstrating its potential for neutral density modeling applied to atmospheric drag determination.

Fedrizzi, Mariangel; Fuller-Rowell, Tim J.; Codrescu, Mihail V.

2012-03-01

46

Joule heating and thermoelectric properties in short single-walled carbon nanotubes: Electron-phonon interaction effect  

NASA Astrophysics Data System (ADS)

The electron-phonon interaction (EPI) effect in single-walled carbon nanotube is investigated by the nonequilibrium Green's function approach within the Born approximation. Special attention is paid to the EPI induced Joule heating phenomenon and the thermoelectric properties in both metallic armchair (10, 10) tube and semiconductor zigzag (10, 0) tube. For Joule heat in the metallic (10, 10) tube, the theoretical results for the breakdown bias voltage is quite comparable with the experimental value. It is found that the Joule heat can be greatly enhanced by increasing the chemical potential, while the role of the temperature is not so important for Joule heat. In the zigzag (10, 0) tube, the Joule heat is smaller than the armchair tube, resulting from nonzero bandgap in the electron band structure. For the electronic conductance Ge and electron thermal conductance ?el, the EPI has important effect at higher temperature or higher chemical potential. Compared with ballistic transport, there is an opposite tendency for Ge to decrease with increasing temperature after EPI is considered. This is due to the dominant effect of the electron phonon scattering mechanism in the electron transport in this situation. There is an interesting ``electron-drag'' phenomenon for the phonon thermal conductance in case of low temperature and high chemical potential, where phonons are dragged by electrons from low temperature region into high temperature region through EPI effect.

Jiang, Jin-Wu; Wang, Jian-Sheng

2011-12-01

47

Impact of Joule heating on the microstructure of nanoscale TiO2 resistive switching devices  

NASA Astrophysics Data System (ADS)

The microstructure of TiO2 functional layers in nanoscale resistive switching devices was analyzed using Scanning Electron and Transmission Electron Microscopies (SEM and TEM). The TiO2 layers in as-fabricated devices were amorphous with very weak lattice fringes in High Resolution TEM. After electroformation with low power dissipation (PDIS < 0.4 mW), the microstructural changes in the TiO2 layer were limited to an area approximately 75~100 nm in radius indicating that the current path and Joule heating were localized. Since the reset power (~2.4 mW) was greater than the electroformation power, switching cycles resulted in an increased area of the TiO2 affected zone and more morphological changes to the Pt electrodes and functional layers. Electroformation under large power dissipation (15 mW) led to massive redistribution of Pt, including shorting of electrodes through the oxide layer. Modeling temperature distribution in the devices found maximum temperature to be strongly dependent on the power dissipation. Computational estimates of the temperature exceed 323 °C at electroformation (0.4 mW), 819 °C at reset (2.4 mW), and the melting point of Pt electrode at large power (15 mW) dissipation. The microstructural changes appear to be caused by Joule heating during device operation.

Meng Lu, Yi; Noman, Mohammad; Picard, Yoosuf N.; Bain, James A.; Salvador, Paul A.; Skowronski, Marek

2013-04-01

48

The implications of self-consistent current density design guidelines comprehending electromigration and Joule heating for interconnect technology evolution  

Microsoft Academic Search

We comprehend both electromigration and Joule heating to study for the first time the self-consistent solutions for the maximum allowed interconnect peak current density jpeak Using worst-case heat losses, we show how these solutions can be used to generate adequately safe current density design guidelines. They indicate that thermal effects will dominate the ability to increase jpeak, rather than EM

William R. Hunter

1995-01-01

49

James Joule and meteors  

NASA Astrophysics Data System (ADS)

1989 was the hundredth anniversary of the death of James Prescott Joule, the Prescott being his mother's family name and the Joule, rhyming with cool, originating from the Derbyshire village of Youlgreave. Joule is rightly famous for his experimental efforts to establish the law of conservation of energy, and for the fact that J, the symbol known as the mechanical equivalent of heat, is named after him. Astronomically his "light has been hidden under a bushel". James Joule had a major influence on the physics of meteors.

Hughes, David W.

50

Thermomigration in Pb-Sn solder joints under joule heating during electric current stressing  

NASA Astrophysics Data System (ADS)

Electromigration of solder joint under high dc current density is known as a reliability concern for the future high-density flip chip packaging and power packaging. Biased mass diffusion within solder joint from cathode to anode under high dc current density is observed in these experiments. In this letter, the experiments on flip chip solder joints under dc current stressing are conducted and thermomigration due to the thermal gradient in the solder joint caused by joule heating is reported. A three-dimensional coupled electric thermal finite-element (FE) simulation of a realistic flip chip module shows the existence of thermal gradient in the solder joint which is high enough to trigger thermomigration.

Ye, Hua; Basaran, Cemal; Hopkins, Douglas

2003-02-01

51

Numerical analysis of the electrical failure of a metallic nanowire mesh due to Joule heating  

NASA Astrophysics Data System (ADS)

To precisely examine the electrical failure behavior of a metallic nanowire mesh induced by Joule heating (i.e., melting), a previously developed numerical method was modified with regard to the maximum temperature in the mesh and the electrical resistivity of the nanowire. A sample case of an Ag nanowire mesh under specific working conditions was analyzed with highly accurate numerical results. By monitoring the temperature in the mesh, the current required to trigger the melting of a mesh segment (i.e., the melting current) could be obtained. The melting process of a mesh equipped with a current source during actual operation was predicted on the basis of the obtained relationship between the melting current and the corresponding melting voltage in the numerical melting process. Local unstable and stable melting could be precisely identified for both the current-controlled and voltage-controlled current sources in the present example.

Li, Yuan; Tsuchiya, Kaoru; Tohmyoh, Hironori; Saka, Masumi

2013-08-01

52

Current-controlled negative differential resistance due to Joule heating in TiO2  

NASA Astrophysics Data System (ADS)

We show that Joule heating causes current-controlled negative differential resistance (CC-NDR) in TiO2 by constructing an analytical model of the voltage-current V(I) characteristic based on polaronic transport for Ohm's Law and Newton's Law of Cooling and fitting this model to experimental data. This threshold switching is the ``soft breakdown'' observed during electroforming of TiO2 and other transition-metal-oxide based memristors, as well as a precursor to ``ON'' or ``SET'' switching of unipolar memristors from their high to their low resistance states. The shape of the V(I) curve is a sensitive indicator of the nature of the polaronic conduction.

Alexandrov, A. S.; Bratkovsky, A. M.; Bridle, B.; Savel'Ev, S. E.; Strukov, D. B.; Stanley Williams, R.

2011-11-01

53

Current-Controlled Negative Differential Resistance Due to Joule Heating In Tio2  

NASA Astrophysics Data System (ADS)

We show that Joule heating causes current-controlled negative differential resistance (CC-NDR) in TiO2 memristive systems by constructing an analytical model of the current-voltage characteristics based on polaronic transport for Ohm's law and Newton's law of cooling and fitting this model to experimental data. This threshold switching is he ``soft breakdown'' observed during electroforming in TiO2 and other transition-metal oxide based memristors, as well as a precursor to ``ON'' or ``SET'' switching of unipolar memristors from their high to their low resistance states. The shape of the V-I curves is a sensitive indicator of the nature of the polaronic conduction, which apparently follows an adiabatic regime [1]. [4pt] [1] A.S. Alexandrov, A.M.Bratkovsky, B.Bridle, S.E.Savel'ev, D. Strukov, and R.S.Williams, Appl. Phys. Lett. 99, xxx (2011).

Bratkovsky, A. M.; Alexandrov, A. S.; Savel'Ev, S. E.; Strukov, D. B.; Williams, R. S.

2012-02-01

54

Joule heating effects on electrokinetic focusing and trapping of particles in constriction microchannels  

NASA Astrophysics Data System (ADS)

Joule heating (JH) is a ubiquitous phenomenon in electrokinetic microfluidic devices. Its effects on fluid and ionic species transport in capillary and microchip electrophoresis have been well studied. However, JH effects on the electrokinetic motion of microparticles in microchannels have been nearly unexplored in the literature. This paper presents an experimental investigation of JH effects on electrokinetic particle transport and manipulation in constriction microchannels under both pure dc and dc-biased ac electric fields. It is found that the JH effects reduce the dielectrophoretic focusing and trapping of particles, especially significant when dc-biased ac electric fields are used. These results are expected to provide a useful guidance for future designs of electrokinetic particle handling microdevices that will avoid JH effects or take advantage of them.

Zhu, Junjie; Sridharan, Sriram; Hu, Guoqing; Xuan, Xiangchun

2012-07-01

55

On the relative importance of Joule heating and the Lorentz force in generating atmospheric gravity waves and infrasound waves in the auroral electrojets  

Microsoft Academic Search

An analysis of the relative importance of the contribution from the Lorentz force and the Joule heating rate as source for the TIDs reveals that a strong height dependence must be expected. Also it is found that for horizontal electric fields larger than about 40 mV\\/m the Joule heating rate will be most dominant above 110 km.

A. Brekke

1979-01-01

56

Joule heating effects on the current carrying capacity of an organic substrate for flip-chip applications  

Microsoft Academic Search

This paper deals with the thermal effects of joule heating in a high interconnect density, thin core, buildup, organic flip chip substrate. The 535mum thick substrate consists of a 253 mum thick core with via density of about 200 mum. The typical feature sizes in the substrate are 50 micron diameter vias is the core\\/buildup layers and 12 micron thick

Varaprasad Calmidi; Irv Memis

2009-01-01

57

EFFECT OF A HEAT CONDUCTING HORIZONTAL CIRCULAR CYLINDER ON MHD MIXED CONVECTION IN A LID-DRIVEN CAVITY ALONG WITH JOULE HEATING  

Microsoft Academic Search

Magnetohydrodynamic (MHD) mixed convection in a lid- driven cavity along with joule heating is studied numerically. The cavity consists of adiabatic horizontal walls and differentially heated vertical walls, but it also contains a heat conducting horizontal circular cylinder located somewhere within the cavity. The aim of the study is to delineate the effect of such a cylinder on the flow

M. M. Rahman; M. A. H. Mamun; R. Saidur; Shuichi Nagata

2009-01-01

58

MHD Mixed Convection with Joule Heating Effect in a Lid-Driven Cavity with a Heated Semi-Circular Source Using the Finite Element Technique  

Microsoft Academic Search

A computational fluid dynamics simulation of heat transfer characteristics on the conjugate effect of Joule heating and magnetic field acting normal to the lid-driven cavity with a heated semi-circular source on one wall under constant temperature is investigated. The left wall of the cavity moves in an upward (case I) or downward (case II) direction, and buoyancy forces are also

M. M. Rahman; Hakan F. Öztop; N. A. Rahim; R. Saidur; Khaled Al-Salem

2011-01-01

59

Analysis of magnetohydrodynamic mixed convection and joule heating in lid-driven cavity having a square block  

Microsoft Academic Search

A numerical analysis is conducted to understand the effect of magnetic field and joule heating on the flow and thermal fields in a lid-driven cavity with a centered heat-conducting horizontal square block. The two sidewalls are maintained at uniform but different temperatures Th and Tc (Th?>?Tc), while the horizontal top and bottom walls are adiabatic. The left vertical wall moves

Mohammad Arif Hasan Mamun; Rahman Saidur

2011-01-01

60

A short note on Joule heating in electro-osmotic flows : A consistent non-dimensional scaling  

Microsoft Academic Search

Purpose – The purpose of this paper is to numerically model electro-osmotic flow (EOF), Joule heating and heat transfer in a channel filled with an electrolyte and to introduce a consistent non-dimensional scaling. Design\\/methodology\\/approach – The finite element method along with a fractional step method is employed. Empirical relations for temperature dependent viscosity, electrical and thermal conductivities are also employed.

P. Nithiarasu; R. W. Lewis

2008-01-01

61

Large-Scale Synthesis of Graphene Films by Joule-Heating-Induced Chemical Vapor Deposition  

NASA Astrophysics Data System (ADS)

We report large-area synthesis of few-layer graphene films by chemical vapor deposition (CVD) in a cold-wall reactor. The key feature of this method is that the catalytic metal layers on the SiO2/Si substrates are self-heated to high growth temperature (900°C to 1000°C) by high-current Joule heating. Synthesis of high-quality graphene films, whose structural and electrical characteristics are comparable to those grown by hot-wall CVD systems, was confirmed by transmission electron microscopy images, Raman spectra, and current-voltage analysis. Optical transmittance spectra of the graphene films allowed us to estimate the number of graphene layers, which revealed that high-temperature exposure of Ni thin layers to a carbon precursor (CH4) was critical in determining the number of graphene layers. In particular, exposure to CH4 for 20 s produces very thin graphene films with an optical transmittance of 93%, corresponding to an average layer number of three and a sheet resistance of ~600 ?/square.

Lee, Jung Min; Jeong, Hae Yong; Park, Won Il

2010-10-01

62

Effect of concurrent joule heat and charge trapping on RESET for NbAlO fabricated by atomic layer deposition  

PubMed Central

The RESET process of NbAlO-based resistive switching memory devices fabricated by atomic layer deposition is investigated at low temperatures from 80 to 200 K. We observed that the conduction mechanism of high resistance state changed from hopping conduction to Frenkel-Poole conduction with elevated temperature. It is found that the conductive filament rupture in RRAM RESET process can be attributed not only to the Joule heat generated by internal current flow through a filament but also to the charge trap/detrapping effect. The RESET current decreases upon heating. Meanwhile, the energy consumption also decreases exponentially. This phenomenon indicates the temperature-related charge trap/detrapping process which contributes to the RESET besides direct Joule heat.

2013-01-01

63

Giant magnetoimpedance effect in stress-joule-heated Co-based amorphous ribbons  

NASA Astrophysics Data System (ADS)

Co-based Co63Fe4B22.4Si5.6Nb5 amorphous ribbons with a width of 150 ?m and a thickness of 50 ?m were prepared by single-roller melt-spinning process. The giant magneto-impedance (GMI) effect of the stress-joule-heated ribbons under applied tensile stress ranging from 37 to 148 MPa was investigated. Experimental results show that the spectra of GMI ratio vs. external direct current (dc) field ( H ex) of the samples changes dramatically with annealing tension ( ?) and driving frequency. The single-peak (SP) GMI curve with maximum GMI ratio of 260% and magnetic field sensitivity of 52%/Oe was obtained in the sample applied tensile stress of 74 MPa at frequency of 3.6 MHz. A three-peak behaviour appeared in the samples under ? of 111 and 148 MPa. The uncommon three-peak behaviour was attributed to several factors, which effectively originated from the balance between domain-wall movement and magnetization rotation.

Chen, ShuangQin; Man, QiKui; Dun, ChaoChao; Shen, BaoLong

2012-12-01

64

Performances of the mixed-gases Joule–Thomson refrigeration cycles for cooling fixed-temperature heat loads  

Microsoft Academic Search

Numerous mixed-gases refrigeration cycle configurations based on Joule–Thomson effects were developed in the past several decades. In this paper, comprehensive thermodynamic analyses were made on two typical cycle configurations to learn their performance for cooling fixed-temperature heat loads. One is the single-stage cycle without phase separators; the other is the auto-cascade refrigeration cycle which has at least one phase separator.

M. Q. Gong; J. F. Wu; E. G. Luo

2004-01-01

65

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

Microsoft Academic Search

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

R. W. Goles; G. J. Sevigny

1983-01-01

66

A perforated plate stacked Si\\/glass heat exchanger with in-situ temperature sensing for joule-thomson coolers  

Microsoft Academic Search

This paper reports a micromachined recuperative heat exchanger integrated with in-situ temperature sensors. In this design, numerous high-conductivity silicon plates, integrated with platinum resistance temperature detectors (Pt RTDs) are fabricated and stacked alternating with low- conductivity Pyrex spacers. The device is intended for use with Joule-Thomson (J-T) coolers. The fabricated versions of the device have a footprint of 1 x

Weibin Zhu; Michael J. White; Gregory F. Nellis; Sanford A. Klein; Yogesh B. Gianchandani

2008-01-01

67

Effects of high-latitude ionospheric electric field variability on global thermospheric Joule heating and mechanical energy transfer rate  

Microsoft Academic Search

Effects of high-latitude ionospheric electric field variability on the Joule heating and mechanical energy transfer rate are investigated by incorporating realistic spatial and temporal characteristics of electric field variability derived from observations into the forcing of a thermosphere ionosphere electrodynamic general circulation model. First, the characteristics of subgrid-scale variability are examined from a spectral analysis of Dynamic Explorer-2 (DE-2) plasma

Tomoko Matsuo

2008-01-01

68

Modified data analysis for thermal conductivity measurements of polycrystalline silicon microbridges using a steady state Joule heating technique  

NASA Astrophysics Data System (ADS)

Accurate knowledge of thermophysical properties is needed to predict and optimize the thermal performance of microsystems. Thermal conductivity is experimentally determined by measuring quantities such as voltage or temperature and then inferring a thermal conductivity from a thermal model. Thermal models used for data analysis contain inherent assumptions, and the resultant thermal conductivity value is sensitive to how well the actual experimental conditions match the model assumptions. In this paper, a modified data analysis procedure for the steady state Joule heating technique is presented that accounts for bond pad effects including thermal resistance, electrical resistance, and Joule heating. This new data analysis method is used to determine the thermal conductivity of polycrystalline silicon (polysilicon) microbridges fabricated using the Sandia National Laboratories SUMMiT V™ micromachining process over the temperature range of 77-350 K, with the value at 300 K being 71.7 +/- 1.5 W/(m K). It is shown that making measurements on beams of multiple lengths is useful, if not essential, for inferring the correct thermal conductivity from steady state Joule heating measurements.

Sayer, Robert A.; Piekos, Edward S.; Phinney, Leslie M.

2012-12-01

69

Unsteady MHD natural convection from a heated vertical porous plate in a micropolar fluid with Joule heating, chemical reaction and radiation effects  

Microsoft Academic Search

The effects of Joule-heating, chemical reaction and thermal radiation on unsteady MHD natural convection from a heated vertical\\u000a porous plate in a micropolar fluid are analyzed. The partial differential equations governing the flow and heat and mass transfer\\u000a have been solved numerically using an implicit finite-difference scheme. The case corresponding to vanishing of the anti-symmetric\\u000a part of the stress tensor

Ali J. Chamkha; R. A. Mohamed; Sameh E. Ahmed

2011-01-01

70

Heat and mass transfer in magneto-biofluid flow through a non-Darcian porous medium with Joule effect  

NASA Astrophysics Data System (ADS)

In the present study, a mathematical model for the hydromagnetic non-Newtonian biofluid flow in the non-Darcy porous medium with Joule effect is proposed. A uniform magnetic field acts perpendicularly to the porous surface. The governing nonlinear partial differential equations are transformed into linear ones which are solved numerically by applying the explicit finite difference method. The effects of various parameters, like Reynolds number and hydro-magnetic, Forchheimer, and Darcian parameters, Prandtl, Eckert, and Schmidt numbers, on the velocity, temperature, and concentration are presented graphically. The results of the study can find applications in surgical operations, industrial material processing, and various heat transfer processes.

Sharma, B. K.; Mishra, A.; Gupta, S.

2013-07-01

71

Three-dimensional noninvasive ultrasound Joule heat tomography based on the acousto-electric effect using unipolar pulses: a simulation study  

NASA Astrophysics Data System (ADS)

Electrical properties of biological tissues are highly sensitive to their physiological and pathological status. Thus it is of importance to image electrical properties of biological tissues. However, spatial resolution of conventional electrical impedance tomography (EIT) is generally poor. Recently, hybrid imaging modalities combining electric conductivity contrast and ultrasonic resolution based on the acousto-electric effect has attracted considerable attention. In this study, we propose a novel three-dimensional (3D) noninvasive ultrasound Joule heat tomography (UJHT) approach based on the acousto-electric effect using unipolar ultrasound pulses. As the Joule heat density distribution is highly dependent on the conductivity distribution, an accurate and high-resolution mapping of the Joule heat density distribution is expected to give important information that is closely related to the conductivity contrast. The advantages of the proposed ultrasound Joule heat tomography using unipolar pulses include its simple inverse solution, better performance than UJHT using common bipolar pulses and its independence of a priori knowledge of the conductivity distribution of the imaging object. Computer simulation results show that using the proposed method, it is feasible to perform a high spatial resolution Joule heat imaging in an inhomogeneous conductive media. Application of this technique on tumor scanning is also investigated by a series of computer simulations.

Yang, Renhuan; Li, Xu; Song, Aiguo; He, Bin; Yan, Ruqiang

2012-11-01

72

Role of joule heating effect and bulk-surface phases in voltage-driven metal-insulator transition in VO2 crystal  

NASA Astrophysics Data System (ADS)

We report the characteristics of a voltage-induced metal-insulator transition (MIT) in macro-sized VO2 crystals. The square of MIT onset voltage (VCMIT2) value shows a linear dependence with the ambient temperature, suggesting that the Joule heating effect is the likely cause to the voltage-induced MIT. The combination of optical microscope images and Laue microdiffraction patterns show the simultaneous presence of a metallic phase in the bulk of the crystal with partially insulating surface layers even after the MIT occurs. A large asymmetry in the heating power just before and after the MIT reflects the sudden exchange of Joule heat to its environment.

Simon Mun, Bongjin; Yoon, Joonseok; Mo, Sung-Kwan; Chen, Kai; Tamura, Nobumichi; Dejoie, Catherine; Kunz, Martin; Liu, Zhi; Park, Changwoo; Moon, Kyungsun; Ju, Honglyoul

2013-08-01

73

Using the quantized mean-field method to model Joule heating in a short nano-conductor  

NASA Astrophysics Data System (ADS)

The quantized mean-field method (QMF) is an extension of the traditional mean-field method for simulating quantum mechanical systems with electrons and ions. It adds the quantum nature of the ions to the simulations. Here we transform the QMF equations from wave function form to density operator form, study the connection between QMF and the recent correlated electron ion dynamics (CEID) method, and show that QMF is a special case of CEID. Our simulations show that QMF fails to produce correct Joule heating in a nano-conductor. This is due to the mean-field approximation for the electrons. However, quantum properties of the ions, such as zero point energy, are conserved.

Kumpula, J. M.; Sutton, A. P.; Kaski, K.

2006-05-01

74

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

PubMed

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. PMID:22107658

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

2011-10-27

75

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

PubMed

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 < Re (Reynolds number) < 5,000], supplied power (0 < P < 15 kW), and electrical conductivity of fluids (0.1 < sigma(20 degrees C) < 2 S/m) under clean conditions with model fluids. This protocol enabled a global 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 difference between the inlet and outlet of the OH, 3) to define and validate a criterion to follow heat dissipation efficiency, and 4) to compare the fouling propensity with the different configurations. A heat dissipation coefficient, Rh(CO), was defined and validated to monitor the fouling propensity through global electrical and thermal parameters. Finally, a numerical simulation was developed to analyze heat profiles (wall, deposit, bulk). Because of an increasing Joule effect in the static deposit, the simulation showed how wall overheating would definitively cause fouling to spiral out of control. PMID:17106078

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

2006-12-01

76

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

Microsoft Academic Search

Magnetic records from 71 stations were employed to determine the distribution of electric fields and currents in the polar ionosphere for March 17, 18, and 19, 1978. Hourly distribution maps of the Joule heat production rate, the particle energy injection rate, and their sum over the entire polar region on the three days were calculated. For constructing the hourly distribution

B.-H. Ahn; S.-I. Akasofu; Y. Kamide

1983-01-01

77

Experimental evaluation of an adaptive Joule-Thomson cooling system including silicon-microfabricated heat exchanger and microvalve components  

PubMed Central

This article reports the evaluation of a Joule–Thomson (JT) cooling system that combines two custom micromachined components—a Si/glass-stack recuperative heat exchanger and a piezoelectrically actuated expansion microvalve. With the microvalve controlling the flow rate, this system can modulate cooling to accommodate varying refrigeration loads. The perforated plate Si/glass heat exchanger is fabricated with a stack of alternating silicon plates and Pyrex glass spacers. The microvalve utilizes a lead zirconate titanate actuator to push a Si micromachined valve seat against a glass plate, thus modulating the flow passing through the gap between the valve seat and the glass plate. The fabricated heat exchanger has a footprint of 1 × 1 cm2 and a length of 35 mm. The size of the micromachined piezoelectrically actuated valve is about 1 × 1 × 1 cm3. In JT cooling tests, the temperature of the system was successfully controlled by adjusting the input voltage of the microvalve. When the valve was fully opened (at an input voltage of ?30 V), the system cooled down to a temperature as low as 254.5 K at 430 kPa pressure difference between inlet and outlet at steady state and 234 K at 710 kPa in a transient state. The system provided cooling powers of 75 mW at 255 K and 150 mW at 258 K. Parasitic heat loads at 255 K are estimated at approximately 700 mW.

Zhu, Weibin; Park, Jong M.; White, Michael J.; Nellis, Gregory F.; Gianchandani, Yogesh B.

2011-01-01

78

Experimental evaluation of an adaptive Joule-Thomson cooling system including silicon-microfabricated heat exchanger and microvalve components.  

PubMed

This article reports the evaluation of a Joule-Thomson (JT) cooling system that combines two custom micromachined components-a Si/glass-stack recuperative heat exchanger and a piezoelectrically actuated expansion microvalve. With the microvalve controlling the flow rate, this system can modulate cooling to accommodate varying refrigeration loads. The perforated plate Si/glass heat exchanger is fabricated with a stack of alternating silicon plates and Pyrex glass spacers. The microvalve utilizes a lead zirconate titanate actuator to push a Si micromachined valve seat against a glass plate, thus modulating the flow passing through the gap between the valve seat and the glass plate. The fabricated heat exchanger has a footprint of 1 × 1 cm(2) and a length of 35 mm. The size of the micromachined piezoelectrically actuated valve is about 1 × 1 × 1 cm(3). In JT cooling tests, the temperature of the system was successfully controlled by adjusting the input voltage of the microvalve. When the valve was fully opened (at an input voltage of -30 V), the system cooled down to a temperature as low as 254.5 K at 430 kPa pressure difference between inlet and outlet at steady state and 234 K at 710 kPa in a transient state. The system provided cooling powers of 75 mW at 255 K and 150 mW at 258 K. Parasitic heat loads at 255 K are estimated at approximately 700 mW. PMID:21552354

Zhu, Weibin; Park, Jong M; White, Michael J; Nellis, Gregory F; Gianchandani, Yogesh B

2011-03-01

79

The responses of the thermospheric neutral wind circulation and temperature to intense Joule heating during geomagnetic storms  

NASA Astrophysics Data System (ADS)

The Center for Integrated Space weather Modeling (CISM) suite of models was run recently to perform an end-to-end simulation of the solar-terrestrial environment. The Coupled Magnetosphere-Ionosphere Model (CMIT) is one of the models used in this run. The CMIT has two components: the LFM global magnetosphere model and the Thermosphere-Ionosphere Nested Grid (TING) model. The CMIT was driven by the simulated solar wind data from solar coronal and solar wind models. In this paper, we present the thermosphere-ionosphere response to variations in the energy and momentum inputs from the magnetosphere under various solar wind conditions. It is found that: 1) During the IMF Bz southward period, the neutrals and ions were tightly coupled. The neutral winds followed the ion two cell-convection pattern. Their speeds were greatly enhanced due to the enhanced ion drifts during the geomagnetic storm. Neutral temperature also increased; 2) During the Bz northward, but By negative period, the ions and neutrals were less coupled. Significant Joule heating occurred, which enhanced the F-region neutral temperature to a maximum of more than 2000 K. In this period F-region neutral winds were driven mostly by the pressure gradient force instead of the ion convection pattern; 3) During the long period when IMF Bz was northward and By was close to zero, the F region neutral winds weakened significantly and neutral temperatures were greatly reduced. Features of semidiurnal tides were evident in both the neutral winds and temperatures.

Wang, W.; Burns, A. G.; Killeen, T. L.; Wiltberger, M.; Solomon, S. C.

2004-05-01

80

Joule Heating Enhanced Phase Coarsening in Sn37Pb and Sn3.5Ag0.5Cu Solder Joints during Current Stressing  

NASA Astrophysics Data System (ADS)

This paper investigated the effect of Joule heating on the phase coarsening in Sn37Pb and Sn3.5Ag0.5Cu ball grid array (BGA) solder joints stressed at -5°C and 125°C with a 6.0 × 102 A/cm2 electric current. The phase growth under current stressing was also compared with those under aging at 125°C. It was found that the current stressing produced a substantial Joule heating in the solder joints and conductive traces. Hence, the solder joints underwent a considerable temperature rise by 30 35°C when stressed at -5°C and 125°C in this study. Coarsening of Pb-rich and Ag-rich phases was confirmed to be accelerated by the current stressing as a result of enhanced diffusion at elevated temperature and atomic stimulation due to numerous collisions between electrons and atoms. Different controlling kinetics were suggested for the cases stressed or aged at different temperatures.

Wu, B. Y.; Alam, M. O.; Chan, Y. C.; Zhong, H. W.

2008-04-01

81

Fabrication of Ti-Ni Shape Memory Alloy Films by Unbalanced Magnetron Sputtering and Their Joule Heat Induced Shape Memory Behavior  

NASA Astrophysics Data System (ADS)

We have optimized the deposition conditions for fabricating Ti-Ni shape memory films by dc unbalanced magnetron sputtering using Taguchi method. The deposited films were annealed at 600°C for 60 min for crystallization and memorization into a flat shape after dissolving the Cu substrates. These films were subjected to DSC measurements and thermal cycling tests under a constant stress. The Joule heat induced shape memory behavior was also characterized by a specially designed tensile testing machine. The transformation temperature of Ni-rich films was found to be lower than RT. On the other hand, those of Ti-47˜49.4 at%Ni films were higher than RT, which means they can be expected to show the shape memory effect at RT. The Ti-47˜49.4 at%Ni films showed a perfect shape recovery under a constant stress by Joule heat of less than 0.1 J.

Inoue, Shozo; Namazu, Takahiro; Koterazawa, Keiji

82

Effect of current crowding and Joule heating on electromigration-induced failure in flip chip composite solder joints tested at room temperature  

SciTech Connect

The electromigration of flip chip solder joints consisting of 97Pb-3Sn and 37Pb-63Sn composite solders was studied under high current densities at room temperature. The mean time to failure and failure modes were found to be strongly dependent on the change in current density. The composite solder joints did not fail after 1 month stressed at 4.07x10{sup 4} A/cm{sup 2}, but failed after just 10 h of current stressing at 4.58x10{sup 4} A/cm{sup 2}. At a slightly higher current stressing of 5.00x10{sup 4} A/cm{sup 2}, the composite solder joints failed after only 0.6 h due to melting. Precipitation and growth of Cu{sub 6}Sn{sub 5} at the cathode caused the Cu under bump metallurgy to be quickly consumed and resulted in void formation at the contact area. The void reduced the contact area and displaced the electrical path, affecting the current crowding and Joule heating inside the solder bump. Significant Joule heating inside solder bumps can cause melting of the solder and quick failure. The effect of void propagation on current crowding and Joule heating was confirmed by simulation.

Nah, J.W.; Suh, J.O.; Tu, K.N. [Department of Materials Science and Engineering, University of California at Los Angeles (UCLA), Los Angeles, California 90095-1595 (United States)

2005-07-01

83

Electron kinetics and non-Joule heating in near-collisionless inductively coupled plasmas  

SciTech Connect

Electron kinetics in an inductively coupled plasma sustained by a coaxial solenoidal coil is studied for the near-collisionless regime when the electron mean free path is large compared to the tube radius. Emphasis is placed on the influence of the oscillatory magnetic field induced by the coil current and the finite dimension of the plasma on electron heating and formation of the electron distribution function (EDF). A nonlocal approach to the solution of the Boltzmann equation is developed for the near-collisionless regime when the traditional two-term Legendre expansion for the EDF is not applicable. Dynamic Monte Carlo (DMC) simulations are performed to calculate the EDF and electron heating rate in argon in the pressure range 0.3{endash}10 mTorr and driving frequency range 2{endash}40 MHz, for given distributions of electromagnetic fields. The wall potential {phi}{sub w} in DMC simulations is found self-consistently with the EDF. Simulation results indicate that the EDF of trapped electrons with total energy {var_epsilon}{lt}e{phi}{sub w} is almost isotropic and is a function solely of {var_epsilon}, while the EDF of untrapped electrons with {var_epsilon}{gt}e{phi}{sub w} is notably anisotropic and depends on the radial position. These results are in agreement with theoretical analysis. {copyright} {ital 1997} {ital The American Physical Society}

Kolobov, V.I. [Plasma Processing Laboratory, Department of Chemical Engineering, University of Houston, Houston, Texas 77204-4792 (United States); Lymberopoulos, D.P. [Applied Materials, 3100 Bowers Avenue, Santa Clara, California 95054 (United States); Economou, D.J. [Plasma Processing Laboratory, Department of Chemical Engineering, University of Houston, Houston, Texas 77204-4792 (United States)

1997-03-01

84

Effect of the joule heating on the quantum efficiency and choice of thermal conditions for high-power blue InGaN/GaN LEDs  

SciTech Connect

The heat model of a light-emitting diode (LED) with an InGaN/GaN quantum well (QW) in the active region is considered. Effects of the temperature and drive current, as well as of the size and material of the heat sink on the light output and efficiency of blue LEDs are studied. It is shown that, for optimal heat removal, decreasing of the LED efficiency as current increases to 100 mA is related to the effect of electric field on the efficiency of carrier injection into the QW. As current further increases up to 400 mA, the decrease in efficiency is caused by Joule heating. It is shown that the working current of LEDs can be increased by a factor of 5-7 under optimal heat removal conditions. Recommendations are given on the cooling of LEDs in a manner dependent on their power.

Efremov, A. A. [St. Petersburg State Polytechnical University (Russian Federation)], E-mail: eartm@mail.ru; Bochkareva, N. I.; Gorbunov, R. I.; Lavrinovich, D. A.; Rebane, Yu. T.; Tarkhin, D. V.; Shreter, Yu. G. [Russian Academy of Sciences, Ioffe Physicotechnical Institute (Russian Federation)

2006-05-15

85

James Joule and meteors  

Microsoft Academic Search

1989 was the hundredth anniversary of the death of James Prescott Joule, the Prescott being his mother's family name and the Joule, rhyming with cool, originating from the Derbyshire village of Youlgreave. Joule is rightly famous for his experimental efforts to establish the law of conservation of energy, and for the fact that J, the symbol known as the mechanical

David W. Hughes

1990-01-01

86

Effects of partial slip, viscous dissipation and Joule heating on Von Kármán flow and heat transfer of an electrically conducting non-Newtonian fluid  

NASA Astrophysics Data System (ADS)

The steady Von Kármán flow and heat transfer of an electrically conducting non-Newtonian fluid is extended to the case where the disk surface admits partial slip. The fluid is subjected to an external uniform magnetic field perpendicular to the plane of the disk. The constitutive equation of the non-Newtonian fluid is modeled by that for a Reiner-Rivlin fluid. The momentum equations give rise to highly non-linear boundary value problem. Numerical solutions for the governing non-linear equations are obtained over the entire range of the physical parameters. The effects of slip, magnetic parameter and non-Newtonian fluid characteristics on the velocity and temperature fields are discussed in detail and shown graphically. Emphasis has been laid to study the effects of viscous dissipation and Joule heating on the thermal boundary layer. It is interesting to find that the non-Newtonian cross-viscous parameter has an opposite effect to that of the slip and the magnetic parameter on the velocity and the temperature fields.

Sahoo, Bikash

2009-07-01

87

Separation of Joule Heating and Peltier Cooling via Time-Resolved X-Ray Di?raction in Si/SiGe Superlattice  

NASA Astrophysics Data System (ADS)

We present detailed measurements of the thermal pro?le in a pulsed current SiGe-based thermoelectric micro-cooler. The evolution of heat ?ow in thermoelectric materials has been previously studied using time-domain thermore?ectance imaging; however, such methods are typically only sensitive to the surface temperature of the device, and the heat ?ow into the material remains hidden. Using time-resolved x-ray di?raction, we probe the transient temperature change in both the surface gold electrode and the underlying Si/SiGe superlattice using the shift in diffraction pattern caused by thermal expansion. We are also able to resolve Joule heating vs. Peltier cooling taking place in the gold through separation of timescales made possible by the relatively short duration (100ps) of the Advanced Photon Source.

Kozina, Michael; Fuchs, Matthias; Chen, Jian; Jiang, Mason; Chen, Pice; Evans, Paul; Vermeersch, Bjorn; Bahk, Je-Hyeong; Shakouri, Ali; Brewe, Dale; Reis, David

2012-02-01

88

A governing parameter for the melting phenomenon at nanocontacts by Joule heating and its application to joining together two thin metallic wires  

SciTech Connect

For cutting and joining extremely thin metallic wires, the issue of Joule heating in the wires is considered. The middle of a section of a thin Pt wire with a diameter of about 800 nm was melted locally by a direct current supply, and the wire was cut at a predetermined point by applying a force to shear the molten part of the wire. Furthermore, a constant current was applied to a system in which the free ends of two Pt wires were contacted, and the wires were joined together. A parameter, which governs the melting phenomenon at the point of contact of very thin wires, is proposed. It was verified that the conditions required for joining thin wires were able to be determined by the parameter that depends on the applied current, the length and cross sectional area of the wires, and a function of the geometrical quantities for calibrating the thermal conditions.

Tohmyoh, Hironori [Department of Nanomechanics, Tohoku University, Aoba 6-6-01, Aramaki, Aoba-ku, Sendai 980-8579 (Japan)

2009-01-01

89

Exciton quenching by diffusion of 2,3,5,6-tetrafluoro-7,7',8,8'-tetra cyano quino dimethane and its consequences on joule heating and lifetime of organic light-emitting diodes.  

PubMed

In this Letter, the effect of F4-TCNQ insertion at the anode/hole transport layer (HTL) interface was studied on joule heating and the lifetime of organic light-emitting diodes (OLEDs). Joule heating was found to reduce significantly (pixel temperature decrease by about 10 K at a current density of 40??mA/cm2) by this insertion. However, the lifetime was found to reduce significantly with a 1 nm thick F4-TCNQ layer, and it improved by increasing the thickness of this layer. Thermal diffusion of F4-TCNQ into HTL leads to F4-TCNQ ionization by charge transfer, and drift of these molecules into the emissive layer caused faster degradation of the OLEDs. This drift was found to reduce with an increase in the thickness of F4-TCNQ. PMID:24081070

Tyagi, Priyanka; Kumar, Arunandan; Giri, Lalat Indu; Dalai, Manas Kumar; Tuli, Suneet; Kamalasanan, M N; Srivastava, Ritu

2013-10-01

90

James Prescott Joule and the Unit of Energy  

Microsoft Academic Search

A CENTURY has passed since Joule read his paper on the relation between heat and work at the meeting of the British Association at Cork on August 26, 1843. It is unfortunate that a difference of opinion has arisen about the correct pronunciation of his name and also of the word joule used to denote a unit of energy (ten

H. S. Allen

1943-01-01

91

The effects on the flow field of retaining the Joule heating and viscous dissipation term in the energy equation for the hydromagnetic free-convective oscillatory flow past a porous limiting surface, I  

Microsoft Academic Search

With viscous dissipation and Joule heating taking into account the hydromagnetic two-dimensional oscillating free-convection flow, of a viscous, incompressible and electrically conducting fluid, past an infinite vertical porous limiting surface, is studied. For the solution of the problem it is considered that, the free-stream velocity, the plate temperature and the induced magnetic field are oscillating in the time about constant

N. D. Nanousis; N. G. Kafousias

1984-01-01

92

Influence of Cu column under-bump-metallizations on current crowding and Joule heating effects of electromigration in flip-chip solder joints  

NASA Astrophysics Data System (ADS)

The electromigration behavior of SnAg solder bumps with and without Cu column under-bump-metallizations (UBMs) has been investigated under a current density of 2.16 × 104 A/cm2 at 150 °C. Different failure modes were observed for the two types of samples. In those without Cu column UBMs, when SnAg solder bumps that had implemented 2 ?m Ni UBMs were current stressed at 2.16 × 104 A/cm2, open failure occurred in the bump that had an electron flow direction from the chip side to the substrate side. However, in those with Cu column UBMs, cracks formed along the interface of Cu6Sn5 intermetallic compounds and the solder on the substrate side in the Sn-3.0Ag-0.5Cu solder bump that had an electron flow direction from the substrate side to the chip side. A three-dimensional simulation of the current density distribution was performed in order to obtain a better understanding of the current crowding behavior in solder bumps. The current crowding effect was found to account for the void formation on both the chip and the substrate side for the two kinds of solder bumps. One more important finding, as confirmed by infrared microscopy, is that the alleviation of current crowding by Cu column UBMs also helped decrease the Joule heating effect in solder bumps during current stressing. Therefore, the measured failure time for the solder joints with Cu column UBMs appears to be much longer than that of the ones with the 2 ?m Ni UBMs.

Liang, Y. C.; Tsao, W. A.; Chen, Chih; Yao, Da-Jeng; Huang, Annie T.; Lai, Yi-Shao

2012-02-01

93

Memoir of James Prescott Joule  

NASA Astrophysics Data System (ADS)

1. Introduction; 2. Parentage and early life; 3. Joule's first research; 4. Second research; 5. Third research; 6. Efforts to convince the scientific world; 7. The year 1847; 8. Joule's views accepted by Thomson, Rankine, and Clausius; 9. Middle life; 10. Later life; Appendix to page 18; Note A to page 88; Index.

Reynolds, Osborne

2011-06-01

94

A Joule Museum at Manchester  

Microsoft Academic Search

THE support of the University of Manchester and the British Society for the History of Science has been secured for the arrangement of a small museum to commemorate the work of James Prescott Joule, the discoverer of the Law of Conservation of Energy. Besides showing various original instruments and documents which belonged to Joule, it is planned to display reconstructions

L. Rosenfeld

1950-01-01

95

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

ERIC Educational Resources Information Center

|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…

Newburgh, Ronald; Leff, Harvey S.

2011-01-01

96

Implications of Auroral Electron Precipitation During the JOULE Experiment  

NASA Astrophysics Data System (ADS)

Four sounding rockets for the JOULE mission were launched three minutes apart during a substorm event on 27 March 2003 from Poker Flat Research Range in Fairbanks, Alaska. Two rockets carried scientific instruments for in-situ measurements of phenomena in the auroral region. The other two rockets carried chemical payloads suitable for measuring the neutral winds. This work focuses on a calculation of the electrojet current using two independent methods, with good agreement: (1) In-situ determination of the electric fields and charge-carrier mobilities, and (2) Ground-based measurements of the electrojet current. Implications for calculations of Joule heating will be discussed.

Slocum, P. L.; Clemmons, J. H.; Hecht, J. H.; Larsen, M. F.; Pfaff, R. F.; Steigies, C. T.; Stenbaek-Nielsen, H. C.; Strickland, D. J.

2005-05-01

97

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

Microsoft Academic Search

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 constructed an early thermometer. Independently, Julius Robert Mayer

Ronald Newburgh; Harvey S. Leff

2011-01-01

98

A Virial Treatment of the Joule and Joule-Thomson Coefficients.  

ERIC Educational Resources Information Center

|Provides background information designed to aid a physical chemistry student in using the virial equation of state in deriving expressions for other thermodynamic properties, such as writing the Joule and Joule-Thomson coefficients in terms of virial expansions. (CS)|

Rybolt, Thomas R.

1981-01-01

99

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

ERIC Educational Resources Information Center

|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,…

Rosenberg, Robert M.

2010-01-01

100

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

ERIC Educational Resources Information Center

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,…

Rosenberg, Robert M.

2010-01-01

101

Vibration-Free Joule-Thomson Cryocoolers for Distributed Microcooling  

Microsoft Academic Search

This paper reports on an innovative concept for a space-borne Joule-Thomson (J-T) cryocooler that utilizes a continuous-flow compressor to provide cooling to multiple miniature cold heads. The heat transport to each cooling site is accomplished at ambient temperature, allowing large separation distances between cryocooler components and cooling sites with minimal performance impact. The compressor uses non-contacting, gas-lubricated bearings and is

W. Chen; M. Zagarola

102

Multicomponent Gas Sorption Joule-Thomson Refrigerator.  

National Technical Information Service (NTIS)

The present invention relates to a cryogenic Joule-Thomson refrigeration capable of pumping multicomponent gases with a single stage sorption compressor system. Alternative methods of pumping a multicomponent gas with a single stage compressor are disclos...

J. Jones S. W. Petrick S. Bard

1990-01-01

103

Performance analysis of small capacity liquid nitrogen generator based on Joule-Thomson refrigerator coupled with air separation membrane  

NASA Astrophysics Data System (ADS)

Joule - Thomson small capacity refrigerators supplied with gas mixture are studied theoretically and experimentally for a variety of applications. They can be especially promising when coupled with membrane air separators. We present liquid nitrogen generation system based on Joule - Thomson cooler joined with air separation membrane. Hollow fiber membrane is used for nitrogen separation from compressed and purified atmospheric air. Joule-Thomson refrigerator operates with a dedicated nitrogen - hydrocarbons mixture and provides a cooling power used for the separated nitrogen liquefaction. Special attention has been paid to a heat exchanger coupling the Joule- Thomson refrigerator with the membrane air separator. This paper describes the system design, the procedure of its working parameters optimization and tests results.

Piotrowska-Hajnus, Agnieszka; Chorowski, Maciej

2012-06-01

104

Milk fouling at direct ohmic heating  

Microsoft Academic Search

Direct ohmic heating (Joule’s heating) is a technology to warm up the food using an electric energy where electric current is passed through a material which gets heated by virtue of its electrical resistance. Advantages over conventional indirect heating methods are speed and uniformity of heating. On the other side, the direct ohmic heating of liquid foods has some problems,

J. Stancl; R. Zitny

2010-01-01

105

The JOULE Experiment: Observations of Small-Scale Structure in the Auroral Oval During a Substorm Event  

NASA Astrophysics Data System (ADS)

The JOULE experiment was carried out at the Poker Flat Research Range in Alaska on March 27, 2003, during a substorm event in the postmidnight sector. The objective of the experiment was to measure the electric fields and the Joule heating over a range of scale sizes from approximately 1000 km to a few tens of meters with the specific goal of obtaining estimates of the contributions of the small-scale fluctuations in the forcing to the overall Joule heating rates. The instrumentation included the SuperDARN radars covering the Alaska sector which represented the largest scales, an imaging coherent scatter radar covering the intermediate scales, and two instrumented rockets covering the smallest scales. In addition, chemical tracer releases provided information about the E-region wind profiles and the horizontal gradients in the winds across the auroral oval. An overview of the experiment, the substorm event, and the measurements will be presented.

Larsen, M. F.; Bishop, R.; Zhan, T.; Pfaff, R.; Stegies, C.; Knudsen, D.; Clemmons, J.; Hecht, J.; Hysell, D.; Bahcivan, H.; Bristow, W.

2003-12-01

106

James Prescott Joule and the Unit of Energy  

Microsoft Academic Search

ALTHOUGH it appears from earlier letters1 that no definite agreement can be reached about the pronunciation of `Joule', the following points may be of interest concerning a possible origin of the name and of its different pronunciations. According to A. Schuster and A. E. Shipley2: ``Joule's name appears to be derived from `Youlgrave', a village in Derbyshire where his family

K. R. Webb

1943-01-01

107

James Prescott Joule and the Unit of Energy  

Microsoft Academic Search

PROF. H. S. ALLEN'S communication in NATURE of September 25 prompts me to mention a recent conversation which I had with a Manchester man whose evidence I should have considered trustworthy. He mentioned that in his youth he had known a man who had been well acquainted with Joule, and that he had told him that Joule himself always pronounced

A. W. V. Mace

1943-01-01

108

The effects on the flow field of retaining the Joule heating and viscous dissipation term in the energy equation for the hydromagnetic free-convective oscillatory flow past a porous limiting surface, II  

Microsoft Academic Search

As the mean steady flow has been presented in Part I, only the solutions for the transient velocity profiles, transient induced magnetic field, and transient temperature profiles and the related to them quantities are presented in this work. The influence of the various parameters entering into the problem, especially of the Eckert numberE, which represents the contribution of heat in

N. G. Kafousias; N. D. Nanousis

1984-01-01

109

The Effects on the Flow Field of Retaining the Joule Heating and Viscous Dissipation Term in the Energy Equation for the Hydromagnetic Free Convective Oscillatory Flow Past a Porous Limiting Surface. II  

Microsoft Academic Search

As the mean steady flow has been presented in Part I, only the solutions for the transient velocity profiles, transient induced magnetic field, and transient temperature profiles and the quantities related to them are presented in this work. The influence of the various parameters entering into the problem, especially of the Eckert number E, which represents the contribution of heat

N. G. Kafousias; N. D. Nanousis

1984-01-01

110

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

NASA Astrophysics Data System (ADS)

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 Ic, in soft type-II samples of standard bulk homogeneity, should be governed essentially by surface defects. Ic 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-Ic being uniformly distributed over the cross section. Coherently, an analysis of the dissipation in such samples predicts that the part VIc of the total Joule effect VI must arise as surface heat sources, while the Joule effect V(I-Ic), 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.

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

1992-07-01

111

Joule-Thomson cryocooler for space applications  

Microsoft Academic Search

A J-T cryocooler is being developed for space applications. It is under laboratory testing and will be flight-tested aboard the Space Shuttle in middle to late 1997. A seal-ability study confirmed that the EDM design is robust and can accommodate a wide range of heat loads while maintaining the development heritage.

R. Levenduski; R. Scarlotti

1996-01-01

112

Nanofocus of tenth of joules and a portable plasma focus of few joules for field applications  

SciTech Connect

A repetitive pinch plasma focus that works with stored energy less than 1 J per shot has be developed at the Chilean Nuclear Energy Commission. The main features of this device, repetitive Nanofocus, are 5 nF of capacity, 5 nH of inductance, 5-10 kV charging voltage, 60-250 mJ stored energy, 5-10 kA current peak, per shot. The device has been operated at 20 Hz in hydrogen and deuterium. X-ray radiographs of materials of different thickness were obtained. Neutrons were detected using a system based upon {sup 3}He proportional counter in chare integrated mode. However, the reproducibility of this miniaturized device is low and several technological subjects have to be previously solved in order to produce neutrons for periods greater than minutes. Further studies in the Nanofocus are being carried out. In addition, a device with a stored energy of a few joules is being explored. A preliminary compact, low weight (3 kg), portable PF device (25 cmx5 cmx5 cm) for field applications has been designed. This device was designed to operate with few kilovolts (10 kV or less) with a stored energy of 2 J and a repetition rate of 10 Hz without cooling. A neutron flux of the order of 10{sup 4}-10{sup 5} n/s is expected.

Soto, Leopoldo; Pavez, Cristian; Moreno, Jose [Comision Chilena de Energia Nuclear, Casilla 188-D, Santiago (Chile); Center for Research and Applications in Plasma Physics and Pulsed Power, P4 (Chile); Tarifeno, Ariel [Center for Research and Applications in Plasma Physics and Pulsed Power, P4 (Chile); Universidad de Concepcion (Chile); Pedreros, Jose [Universidad de Santiago (Chile); Altamirano, Luis [Center for Research and Applications in Plasma Physics and Pulsed Power, P4 (Chile); Dicontek (Chile)

2009-01-21

113

James Prescott Joule and the Unit of Energy  

Microsoft Academic Search

FURTHER to Prof. H. S. Allen's communication in NATURE of September 25, I may say that Joule used to live not far from my home at Sale, near Manchester, and I have often seen his house. His name was pronounced `Joole', thus confirming Prof. G. W. O. Howe's pronunciation.

Graham Renshaw

1943-01-01

114

James Prescott Joule and the idea of energy  

Microsoft Academic Search

To commemorate the centenary of Joule's death, this article offers a brief account of the origins and development of his ideas and their incorporation into mainstream physics. The scientific, technological and social importance of his work is explained and he is shown to be a quintessential physicist.

Donald Cardwell

1989-01-01

115

James Prescott Joule and the Unit of Energy  

Microsoft Academic Search

PROF. ALLEN'S inquiries (NATURE, September 25, p. 354) confirm the conclusion reached by the late Prof. Lloyd James and reported in the Radio Times in February 1933. He found that twelve near relatives and friends of the man himself pronounced `Joule' to rhyme with cool, six more distant relatives and friends rhymed it with coal and nine other friends rhymed

J. H. Awbery

1943-01-01

116

James Prescott Joule and the idea of energy  

NASA Astrophysics Data System (ADS)

To commemorate the centenary of Joule's death, this article offers a brief account of the origins and development of his ideas and their incorporation into mainstream physics. The scientific, technological and social importance of his work is explained and he is shown to be a quintessential physicist.

Cardwell, Donald

1989-05-01

117

Comparative Exergetic Analysis of Joule-Thomson Liquefiers  

Microsoft Academic Search

The Joule-Thomson microliquefiers are very reliable and noiseless cryocoolers, specially well fitted for cryostating small electronic devices, IR detectors or cryosurgical probes. Their essential drawback is low thermodynamic efficiency imposing high supply gas pressure, usually above 10 MPa. An exergetic analysis of the microliquefier has been performed and exergy-loss sources identified. Some of the losses can be avoided if a

Maciej Chorowski

2004-01-01

118

Solid State Oxygen Compressor for Joule - Thompson Cryocoolers.  

National Technical Information Service (NTIS)

This report summarizes the work performed in the original Phase II Program and the results of the ARPA sponsored program. Prototypes of the Honey Comb Oxygen Generators (ARPA) as Solid State Oxygen Compressors for the J-T (Joule-Thomson) Cryocoolers were ...

W. N. Lawless

1997-01-01

119

FURTHER DEVELOPMENT OF A MIXED GAS JOULE THOMSON REFRIGERATOR  

Microsoft Academic Search

A mixed gas Joule Thomson refrigerator has distinct advantages over other cryocooler for certain applications. The system is compact, has good thermodynamic efficiency and low levels of vibration and noise. Further development of this refrigeration machine is possible by optimization of the gas mixture composition. A method was developed which permits a reduction by a large factor in the number

A. Alexeev; Ch. Haberstroh; H. Quack

120

Comparative Exergetic Analysis of Joule-Thomson Liquefiers  

NASA Astrophysics Data System (ADS)

The Joule-Thomson microliquefiers are very reliable and noiseless cryocoolers, specially well fitted for cryostating small electronic devices, IR detectors or cryosurgical probes. Their essential drawback is low thermodynamic efficiency imposing high supply gas pressure, usually above 10 MPa. An exergetic analysis of the microliquefier has been performed and exergy-loss sources identified. Some of the losses can be avoided if a pure gas is replaced with a proper gas mixture and in result the supply gas pressure can be lowered significantly. The efficiencies and working parameters of Joule-Thomson microliquefier fed with pure N2 and the mixtures N2 - CH4 and N2 - R13 have been estimated and measured. The mixture properties have been calculated using the Peng-Robinson equation of state. The possibility to use a liquid-solid phase transition in a cooling-power ``on-off'' control loop has been observed.

Chorowski, Maciej

2004-06-01

121

Joule-Thomson coefficients of hydrogen and methane mixtures  

Microsoft Academic Search

Joule-Thomson coefficients for two mixtures of methane and hydrogen gas with hydrogen\\/methane compositions of 0.127\\/0.873 mole fraction and 0.5657\\/0.4343 mole fraction were measured over a pressure range of 135.83-21.39 atm and a temperature range of 294.87-274.38 K. Four experimental isenthalps were generated for each mixture and the data were compared to the predicted values from the original Redlich-Kwong equation of

R. E. Randelman; L. A. Wenzel

1988-01-01

122

Heat conduction and thermal stress induced by an electric current in an infinite thin plate containing an elliptical hole with an edge crack  

Microsoft Academic Search

A uniform electric current at infinity was applied to a thin infinite conductor containing an elliptical hole with an edge crack. The electric current gives rise to two states, i.e., uniform and uneven Joule heat. These two states must be considered to analyze the heat conduction problem. The uneven Joule heat gives rise to uneven temperature and thus to heat

Norio Hasebe; Christian Bucher; Rudolf Heuer

2010-01-01

123

Multiscale Modeling of Metal-Metal Contact Dynamics under High Electromagnetic Stress: Timescales and Mechanisms for Joule Melting of Al-Cu Asperities  

Microsoft Academic Search

An analysis and initial results from a multiscale continuum-atomistic simulation of the Joule heating and melting of Cu-Al asperity contacts is presented. An analytic expression is given for the time needed to reach the Al melting point for an asperity as a function of the voltage drop and the asperity contact area. The coupled continuum-atomistic simulations capture the initial stages

Douglas Irving; Clifford Padgett; Yin Guo; John Mintmire; Donald Brenner

2008-01-01

124

Multiscale Modeling of Metal–Metal Contact Dynamics Under High Electromagnetic Stress: Timescales and Mechanisms for Joule Melting of Al–Cu Asperities  

Microsoft Academic Search

An analysis and initial results from a multiscale continuum-atomistic simulation of the Joule heating and melting of Cu-Al asperity contacts are presented. An analytic expression is given for the time needed to reach the Al melting point for an asperity as a function of the voltage drop and the asperity contact area. The coupled continuum-atomistic simulations capture the initial stages

Douglas L. Irving; Clifford W. Padgett; Yin Guo; John W. Mintmire; Donald W. Brenner

2009-01-01

125

Ohm's Law, Fick's Law, Joule's Law, and Ground Water Flow  

SciTech Connect

Starting from the contributions of Ohm, Fick and Joule during the nineteenth century, an integral expression is derived for a steady-state groundwater flow system. In general, this integral statement gives expression to the fact that the steady-state groundwater system is characterized by two dependent variables, namely, flow geometry and fluid potential. As a consequence, solving the steady-state flow problem implies the finding of optimal conditions under which flow geometry and the distribution of potentials are compatible with each other, subject to the constraint of least action. With the availability of the digital computer and powerful graphics software, this perspective opens up possibilities of understanding the groundwater flow process without resorting to the traditional differential equation. Conceptual difficulties arise in extending the integral expression to a transient groundwater flow system. These difficulties suggest that the foundations of groundwater hydraulics deserve to be reexamined.

Narasimhan, T.N.

1999-02-01

126

Heat management in aluminum\\/air batteries: Sources of heat  

Microsoft Academic Search

One of the problems with the aluminum\\/air battery is the generation of heat, during both idle and discharge periods. The main sources of heat are: (1) corrosion of the aluminum anode during the idle period; (2) inefficient, or less efficient, dissolution of anode during discharge; (3) Joule heat during discharge, and (4) non-uniform mass transfer during both discharge and idle

R. S. M. Patnaik; S. Ganesh; G. Ashok; M. Ganesan; V. Kapali

1994-01-01

127

Joule-Thomson Cooling Due to CO2 Injection into Natural GasReservoirs  

SciTech Connect

Depleted natural gas reservoirs are a promising target for Carbon Sequestration with Enhanced Gas Recovery (CSEGR). The focus of this study is on evaluating the importance of Joule-Thomson cooling during CO2 injection into depleted natural gas reservoirs. Joule-Thomson cooling is the adiabatic cooling that accompanies the expansion of a real gas. If Joule-Thomson cooling were extreme, injectivity and formation permeability could be altered by the freezing of residual water,formation of hydrates, and fracturing due to thermal stresses. The TOUGH2/EOS7C module for CO2-CH4-H2O mixtures is used as the simulation analysis tool. For verification of EOS7C, the classic Joule-Thomson expansion experiment is modeled for pure CO2 resulting in Joule-Thomson coefficients in agreement with standard references to within 5-7 percent. For demonstration purposes, CO2 injection at constant pressure and with a large pressure drop ({approx}50 bars) is presented in order to show that cooling by more than 20 C can occur by this effect. Two more-realistic constant-rate injection cases show that for typical systems in the Sacramento Valley, California, the Joule-Thomson cooling effect is minimal. This simulation study shows that for constant-rate injections into high-permeability reservoirs, the Joule-Thomson cooling effect is not expected to create significant problems for CSEGR.

Oldenburg, Curtis M.

2006-04-21

128

Final Report on the Joule-Scale Experimental Demonstration  

SciTech Connect

We describe the final results of the High Power Laser Pulse Recirculation project. We have developed and implementing a novel technique for picosecond, Joule-class laser pulse recirculation inside a passive cavity. The aim of this project was to develop technology compatible with increasing the efficiency of Compton based light sources by more than an order of magnitude. In year 1 of the project, we achieved a greater than 40 times average power enhancement of the mJ-scale laser pulses inside a passive cavity with internal focus. In year 2, we demonstrated recirculation of lasers pulses with energies up to 191 mJ at 532 nm, at a repetition rate of 10 Hz, and a pulse duration of 20 ps. In this high energy regime, we achieved up to 14 times average power enhancement inside the cavity. This enhancement factor is compatible with the new X-band based mono-energetic gamma-ray machine, Velociraptor, being constructed at LLNL. The demonstrated cavity enhancement is primarily limited by the poor spatial beam quality of the high power laser beam. We expect a nearly diffraction limited laser beam to achieve 40 times or better cavity enhancement, as demonstrated in low energy experiments in FY-07. The two primary obstacles to higher average brightness and conversion efficiency of laser pulse energy to gamma-rays are the relatively small Compton scattering cross-section and the typically low repetition rates of Joule-class interaction lasers (10 Hz). Only a small fraction (10{sup -10}) of the available laser photons is converted to gamma-rays, while the rest is discarded. To significantly reduce the average power requirements of the laser and increase the overall system efficiency, we can recirculate laser light for repeated interactions with electron bunches. Our pulse recirculation scheme is based on nonlinear frequency conversion, termed recirculation injection by nonlinear gating (RING), inside a passive cavity. The main objectives of the two year project were: (1) Validate the concept of RING pulse trapping and recirculation technique. Completed Sep. 07 (2) Develop cavity designs compatible with a laser-electron Compton light source. Completed January 08. (3) Demonstrate trapping and recirculation of laser pulses suitable for high brightness gamma-ray generation. Completed Aug. 08 Our project has established RING as a viable technology for enhancing Compton scattering based gamma-ray generation. With sufficient funding we can implement pulse recirculation on the next generation Mono-energetic Gamma-Ray machine under construction at LLNL.

Shverdin, M

2008-10-01

129

A mixed-gas miniature Joule-Thomson cooling system  

NASA Astrophysics Data System (ADS)

A mixed-gas Joule-Thomson (JT) cooling system is investigated in which a micromachined JT cold stage of 60 × 10 × 0.7 mm3 is combined with a linear compressor. The cooling system is operated between 1.3 bar and 9.4 bar with a ternary gas mixture of 39 mol% methane, 20 mol% ethane and 41 mol% isobutane. It cools down to below 130 K, and at a cold-tip temperature of 150 K, a cooling power of 46 mW is obtained at a mass-flow rate of 1.35 mg s-1. The background losses are experimentally determined to be 20 mW and are in good agreement with the calculated value of 21 mW. The linear compressor can be used to drive 19 of these miniature JT cold stages in parallel, e.g. for cooling optical detectors in future space missions. In this mode, the compressor pressure ratio is slightly less, resulting in a net cooling power of 23 mW per miniature JT cold stage.

Derking, J. H.; Vermeer, C. H.; Tirolien, T.; Crook, M. R.; ter Brake, H. J. M.

2013-10-01

130

Joule-Thomson coefficients of hydrogen and methane mixtures  

SciTech Connect

Joule-Thomson coefficients for two mixtures of methane and hydrogen gas with hydrogen/methane compositions of 0.127/0.873 mole fraction and 0.5657/0.4343 mole fraction were measured over a pressure range of 135.83-21.39 atm and a temperature range of 294.87-274.38 K. Four experimental isenthalps were generated for each mixture and the data were compared to the predicted values from the original Redlich-Kwong equation of state, with the Soave modification and with the Prausnitz modification, and with the Peng-Robinson equation of state. All the models agree well for the methane-rich mixture, with the Peng-Robinson having the lowest deviation of 3.11%. Agreement for the hydrogen-rich mixture over the entire range was found to be nonsystematic, although the equations showed small deviations for the high-pressure region. The Peng-Robinson equation showed the lowest overall deviation of 3.21%.

Randelman, R.E.; Wenzel, L.A.

1988-07-01

131

Development of a Low Noise 10 K J-T (Joule-Thomson) Refrigeration System.  

National Technical Information Service (NTIS)

This report summarizes work done on the development of a low noise Joule-Thomson, microminiature refrigeration system designed for 10 K operation. Topics discussed include: calculation of phase diagram of mixtures of certain hydrocarbon gases with nitroge...

W. A. Little

1987-01-01

132

On the Joule-Thomson integral inversion curves of quantum gases  

Microsoft Academic Search

The integral inversion curve (IIC) is the contour of all thermodynamic states (P,T) which exhibit a zero integral cooling under Joule-Thomson (isenthalpic) expansion from a pressure, P, down to ambient atmospheric pressure. This is an alternative and complementary presentation of the Joule-Thomson inversion phenomena. The traditional inversion curve is a differential one, namely, it distinguishes between states for which infinitesimal

B.-Z. Maytal; A. Shavit

1997-01-01

133

Minimum heat generation during fast magnetization switching  

NASA Astrophysics Data System (ADS)

Fast magnetization switching with minimum heat generation is explored based upon magnetization dynamics and optimal stochastic control method. For current spin current based magnetic device, pulse shape optimization provides significant Joule heating reduction. For future spintronic device without charge moving, the minimum amount of heat generated during magnetization switching is fundamentally constrained by magnetization switching speed and magnetization nonvolatility.

Wang, Xiaobin; Gu, Ying

2013-03-01

134

Performance of a MEMS Heat Exchanger for a Cryosurgical Probe  

Microsoft Academic Search

This paper presents the experimental test results for two 2 nd generation Micro-Electro- Mechanical Systems (MEMS) heat exchangers that are a composite of silicon plates with micro- machined flow passages interleaved with glass spacers. The MEMS heat exchangers were designed for use as the recuperative heat exchanger within a Joule-Thomson (JT) cycle used to energize a cryosurgical probe. The heat

M. J. White; W. Zhu; G. F. Nellis; S. A. Klein; Y. B. Gianchandani

135

Four near Zero Energy Habitat House Prototypes meet Building America 30% Mixed Humid Climate Joule Savings  

Microsoft Academic Search

This report assists DOE's Residential Integration Program meet its 30% mixed humid climate Joule savings target by documenting all four near zero energy Habitat for Humanity prototype houses in the form of a Building America Benchmark house comparison. These houses are featured in Building America FY07Best Practices manual. The construction methods, building envelope technologies, appliances and equipment of four single-family

Jeff Christian

136

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

Microsoft Academic Search

Liquid hydrogen mass flow rate, pressure drop, and temperature drop data were obtained for a number of multiple orifice Joule-Thomas 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

S. Stephen Papell; Ted W. Nyland; Naseem H. Saiyed

1992-01-01

137

Joule-Thomson valves for long term service in space cryocoolers  

Microsoft Academic Search

Joule-Thomson valves for small cryocoolers have throttling passages on the order of 0.1 millimeter in diameter. Consequently, they can become plugged easily and stop the operation of the cooler. Plugging can be caused by solid particles, liquids or gases. Plugging is usually caused by the freezing of contaminant gases from the process stream. In small open loop coolers and in

J. M. Lester; B. Benedict

1985-01-01

138

Efficiency of simple quantum engines: The Joule-Brayton and Otto cycles  

Microsoft Academic Search

Following the formalism of a quantum engine proposed by Bender et al. for a single particle of mass m confined to an infinite one-dimensional potential well of width L. we construct the isobaric and isochoric quantum analogous processes in order to analyze the efficiency of two classical thermodynamic engines: The Joule-Brayton and Otto cycles. We find that the efficiency are

L. Guzmán-Vargas; V. Granados; R. D. Mota

2002-01-01

139

Modelling of a Rotary Absorption Heat Pump.  

National Technical Information Service (NTIS)

The research was done in the framework of the JOULE II program and was funded by the Finnish government. The title of the project is 'Rotary Vapor-Recompression Heat Pump'. The objective is to develop a heat pump based on the combination of a rotary absor...

A. Keinaenen A. Karola K. Siren

1995-01-01

140

Current heating in polymer light emitting diodes  

Microsoft Academic Search

electrically driven devices. While there are many differences between optically and electrically pumped devices, the most obvious one is the existence of current and the unavoidable voltage drop associated with it. In other words, electrically pumped devices are more susceptible to Joule heating prob- lems. In this letter we examine the issue of current ~and voltage! induced heating and its

N. Tessler; N. T. Harrison; D. S. Thomas; R. H. Friend

141

Heat management in aluminum/air batteries: Sources of heat  

NASA Astrophysics Data System (ADS)

One of the problems with the aluminum/air battery is the generation of heat, during both idle and discharge periods. The main sources of heat are: (1) corrosion of the aluminum anode during the idle period; (2) inefficient, or less efficient, dissolution of anode during discharge; (3) Joule heat during discharge, and (4) non-uniform mass transfer during both discharge and idle periods. These components of heat act in a cumulative way because they are all interconnected. This paper addresses the basic reasons for the origin of these sources of heat. Suitable and practical remedial measures for the effective removal of such heat in the aluminum/air battery are suggested.

Patnaik, R. S. M.; Ganesh, S.; Ashok, G.; Ganesan, M.; Kapali, V.

1994-07-01

142

Jupiter Thermospheric General Circulation Model (JTGCM): Global structure and dynamics driven by auroral and Joule heating  

Microsoft Academic Search

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)

S. W. Bougher; J. H. Waite Jr; T. Majeed; G. R. Gladstone

2005-01-01

143

Selective Functionalization of Silicon Micro\\/Nanowire Sensors via Localized Joule Heating  

Microsoft Academic Search

A novel approach to achieve localized surface functionalization of silicon-based micro and nanoscale linear structures (e.g., silicon nanowire sensors) is proposed in this paper. This method is based upon the protection of silicon surface by hydrophobic polymer layers such as polytetrafluoroethylene (PTFE). These layers are used as a protective, patterning barrier against surface functionalization of silicon or silicon oxide surface.

Inkyu Park; Zhiyong Li; A. P. Pisano

2007-01-01

144

Multiphase, multi-electrode Joule heat computations for glass melter and in situ vitrification simulations  

Microsoft Academic Search

Waste glass melter and in situ vitrification (ISV) processes represent the combination of electrical thermal, and fluid flow phenomena to produce a stable waste-from product. Computational modeling of the thermal and fluid flow aspects of these processes provides a useful tool for assessing the potential performance of proposed system designs. These computations can be performed at a fraction of the

P. S. Lowery; D. L. Lessor

1991-01-01

145

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

PubMed

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. PMID:24153448

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

2013-10-24

146

Prediction of Joule-Thomson inversion curves for pure uids and one mixture by molecular simulation  

Microsoft Academic Search

The predictive power of a set of molecular models, which have been adjusted to vapor-liquid equilibria only, is validated. For that purpose, Joule-Thomson inver- sion curves were determined by molecular simulation for 15 pure uids, i.e. Argon, Methane, Oxygen, Nitrogen, Carbon Dioxide, Ethylene, Carbon Monoxide, R11, R23, R41, R124, R125, R134a, R143a, R152a, and for Air. Comparison of the sim-

Vrabec Gaurav; Kumar Kedia; Hans Hasse

2004-01-01

147

Prediction of Joule–Thomson inversion curves for pure fluids and one mixture by molecular simulation  

Microsoft Academic Search

The predictive power of a set of molecular models, which have been adjusted to vapor–liquid equilibria only, is validated. For that purpose, Joule–Thomson inversion curves were determined by molecular simulation for 15 pure fluids, i.e. argon, methane, oxygen, nitrogen, carbon dioxide, ethylene, carbon monoxide, R11, R23, R41, R124, R125, R134a, R143a, R152a, and for air. Comparison of the simulation results

Jadran Vrabec; Gaurav Kumar Kedia; Hans Hasse

2005-01-01

148

Clogging of Joule-Thomson Devices in Liquid Hydrogen-Lunar Lander Descent Stage Operating Regime  

Microsoft Academic Search

Joule-Thomson (J-T) devices have been identified as critical components for future space exploration missions. The NASA Constellation Program lunar architecture considers LOX\\/LH2 propulsion for the lunar lander descent stage main engine an enabling technology, ensuring the cryogenic propellants are available at the correct conditions for engine operation. This cryogenic storage system may utilize a Thermodynamic Vent System (TVS) that includes

J. M. Jurns

2010-01-01

149

CLOGGING OF JOULE-THOMSON DEVICES IN LIQUID HYDROGEN—LUNAR LANDER DESCENT STAGE OPERATING REGIME  

Microsoft Academic Search

Joule-Thomson (J-T) devices have been identified as critical components for future space exploration missions. The NASA Constellation Program lunar architecture considers LOX\\/LH2 propulsion for the lunar lander descent stage main engine an enabling technology, ensuring the cryogenic propellants are available at the correct conditions for engine operation. This cryogenic storage system may utilize a Thermodynamic Vent System (TVS) that includes

J. M. Jurns

2010-01-01

150

Efficiency of simple quantum engines: The Joule-Brayton and Otto cycles  

NASA Astrophysics Data System (ADS)

Following the formalism of a quantum engine proposed by Bender et al. for a single particle of mass m confined to an infinite one-dimensional potential well of width L. we construct the isobaric and isochoric quantum analogous processes in order to analyze the efficiency of two classical thermodynamic engines: The Joule-Brayton and Otto cycles. We find that the efficiency are analogous to those obtained for classical engines.

Guzmán-Vargas, L.; Granados, V.; Mota, R. D.

2002-11-01

151

Comparison of the fossil fuel energy requirements for solar, natural gas, and electrical water heating systems  

Microsoft Academic Search

A comparison between solar and fossil fuel heating is presented with primary attention given to cost factors. In most areas of the United States, solar heating is found to be several times more cost efficient than comparable electric water heating, and about half as efficient as natural gas water heating per Joule of energy produced. An input\\/output flow model is

J. Zucchetto; S. Brown

1977-01-01

152

Prediction of Joule Thomson inversion curves for pure fluids and one mixture by molecular simulation  

NASA Astrophysics Data System (ADS)

The predictive power of a set of molecular models, which have been adjusted to vapor liquid equilibria only, is validated. For that purpose, Joule Thomson inversion curves were determined by molecular simulation for 15 pure fluids, i.e. argon, methane, oxygen, nitrogen, carbon dioxide, ethylene, carbon monoxide, R11, R23, R41, R124, R125, R134a, R143a, R152a, and for air. Comparison of the simulation results with reference equations of state shows an excellent agreement.

Vrabec, Jadran; Kedia, Gaurav Kumar; Hasse, Hans

2005-04-01

153

Clogging in micromachined Joule-Thomson coolers: Mechanism and preventive measures  

NASA Astrophysics Data System (ADS)

Micromachined Joule-Thomson coolers can be used for cooling small electronic devices. However, a critical issue for long-term operation of these microcoolers is the clogging caused by the deposition of water that is present as impurity in the working fluid. We present a model that describes the deposition process considering diffusion and kinetics of water molecules. In addition, the deposition and sublimation process was imaged, and the experimental observation fits well to the modeling predictions. By changing the temperature profile along the microcooler, the operating time of the microcooler under test at 105 K extends from 11 to 52 h.

Cao, H. S.; Vanapalli, S.; Holland, H. J.; Vermeer, C. H.; ter Brake, H. J. M.

2013-07-01

154

Damage detection via Joule effect for multidirectional carbon fiber reinforced composites  

NASA Astrophysics Data System (ADS)

The electrical conductivity of a thin multidirectional carbon fiber reinforced composite laminates can be expressed by an equivalent symmetric second order tensor. Any change of the microstructure of the composite laminate due to an interlaminar damage locally changes the electrical conductivity tensor of the medium. Applying electric potential difference, the temperature of the medium rises, due to the Joule effect. In the presence of interlaminar damage, the developed temperature field changes locally. Following the coupled electrical/thermal solution of the problem, the mechanism of the phenomenon is elucidated and validated against experimental results by comparing the measured to calculated temperature field.

Athanasopoulos, N.; Kostopoulos, V.

2012-09-01

155

Caloria o Joule? Riserve nei confronti di un nuovo indirizzo metrologico  

Microsoft Academic Search

\\u000a Conclusioni  1)|In linea di massima e sul piano teorico possibile e legittimo esprimere la quantit di calore in unit di energia (e\\u000a suoi multipli);\\u000a \\u000a 2)|l’unit di energia pi consona a tale scopo quella prescelta dal SI, e cio il joule;\\u000a \\u000a \\u000a 3)|ma l’unificazione delle unit di misura, e in particolare l’adozione radicale del SI, indispensabile nella scienza \\u000a pura , non nella tecnica

Emanuele Djalma Vitali

1974-01-01

156

On the temperature distribution in the counter flow heat exchanger with multicomponent non-azeotropic mixtures  

Microsoft Academic Search

The influence of mixture composition on the temperature distribution in the counter flow heat exchanger used in mixture Joule–Thomson refrigerators is investigated in this paper. A perfect heat capacity matching between the supply and the return streams can be achieved by optimizing the mixture composition. The deeper reason is that in two-phase state the latent heat makes a very important

M. Q Gong; E. C Luo; J. F Wu; Y Zhou

2002-01-01

157

A high-Tc SQUID-based sensor head cooled by a Joule-Thomson cryocooler  

NASA Astrophysics Data System (ADS)

The goal of the so-called FHARMON project is to develop a high-Tc SQUID-based magnetometer system for the measurement of fetal heart activity in standard clinical environments. To lower the threshold for the application of this fetal heart monitor, it should be simple to operate. It is, therefore, advantageous to replace the liquid cryogen bath by a closed-cycle refrigerator. For this purpose, we selected a mixed-gas Joule-Thomson cooler; the APD Cryotiger©. Because of its magnetic interference, the compressor of this closed-cycle cooler will be placed at a distance of ~2 m from the actual sensor, which is an axial second order gradiometer. The gradiometer is formed by three magnetometers placed on an alumina cylinder, which is connected to the cold head of the cooler. This paper describes the sensor head in detail and reports on test experiments.

Rijpma, A. P.; Ter Brake, H. J. M.; de Vries, E.; Nijhof, N.; Holland, H. J.; Rogalla, H.

2002-08-01

158

Joule-Thomson Inversion in Vapor-Liquid-Solid Solution Systems  

NASA Astrophysics Data System (ADS)

Solid phase precipitation can greatly affect thermal effects in isenthalpic expansions; wax precipitation may occur in natural hydrocarbon systems in the range of operating conditions, the wax appearance temperature being significantly higher (as high as 350 K) for hyperbaric fluids. Recently, methods for calculating the Joule-Thomson inversion curve (JTIC) for two-phase mixtures, and for three-phase vapor-liquid-multisolid systems have been proposed. In this study, an approach for calculating the JTIC for the vapor-liquid-solid solution systems is presented. The JTIC is located by tracking extrema and angular points of enthalpy departure variations versus pressure at isothermal conditions. The proposed method is applied to several complex synthetic and naturally occurring hydrocarbon systems. The JTIC can exhibit several distinct branches (which may lie within two- or three-phase regions or follow phase boundaries), multiple inversion temperatures at fixed pressure, as well as multiple inversion pressures at given temperature.

Nichita, Dan Vladimir; Pauly, Jerome; Daridon, Jean-Luc

2009-07-01

159

Soft X-Ray Emission and Charged Particles Beams from a Plasma Focus of Hundreds Joules  

SciTech Connect

In a new stage of characterization of our plasma focus devices of hundred and tens of joules (PF-400J and PF-50J), preliminary series of measurements on soft X-ray and ion beams have been performed in the device PF-400J (176-539 J, 880 nF, T/4 {approx}300 ns). The device was operated in hydrogen to 7 mbar of pressure . The temporal and spatial X-ray characteristics are investigated by means filtered PIN diodes and a multipinhole camera. Graphite collectors, operating in the bias ion collector mode, are used to estimate the characteristic ion energy using the time flight across the probe array. The time of the ion beam emission to be correlated with plasma emission events associated with the soft X-ray pulses detected by the probes. Temporal correlations between soft X-ray signals and ion beams are performed.

Silva, Patricio; Moreno, Jose; Soto, Leopoldo [Comision Chilena de Energia Nuclear, Casilla 188-D, Santiago (Chile); Pavez, Cristian [Comision Chilena de Energia Nuclear, Casilla 188-D, Santiago (Chile); Universidad de Concepcion, Facultad de Ciencias, Departamento de Fisica, Concepcion (Chile); Arancibia, Jaime [Universidad de Chile, Facultad de Ciencias, Departamento de Fisica, Santiago (Chile)

2006-12-04

160

Characterization of steady and transient heating of interconnects - a review  

Microsoft Academic Search

Continued scaling of transistors and metal interconnects have resulted in high current densities and significant Joule heating in the metal lines, exacerbating thermally driven reliability issues in microprocessors. It is imperative, therefore, to develop an accurate and rapid predictive thermal characterization capability for on chip interconnect arrays to facilitate chip design. This is a multi-scale problem for which the traditional

Banafsheh Barabadi; Yogendra Joshi; Satish Kumar

2011-01-01

161

Self-heating in normal metals and superconductors  

Microsoft Academic Search

This review is devoted to the physics of current-carrying superconductors and normal metals having two or more stable states sustained by Joule self-heating. The creation, propagation, and localization of electrothermal domains and switching waves leading to the transition from one stable state to another in uniform and nonuniform samples are treated in detail. The connection between thermal bistability and hysteresis,

A. V. Gurevich; R. G. Mints

1987-01-01

162

Preliminary Studies of Ions Emission in a Small Plasma Focus Device of Hundreds of Joules  

SciTech Connect

Ion beam emission in plasma focus (PF) discharges was originally investigated to explain the strong forward anisotropy observed in the neutron. Several properties of PF emitted deuteron beams have been measured, including their angular distributions and energy spectra in devices operating with energies from 1 kJ to 1 MJ. At present there is a growing interest in the development of very small PF devices operating under 1 kJ. As part of the characterization program of the very low energy PF devices (<1 kJ) developed at the Chilean Nuclear Energy Commission, the charges particle emission in hydrogen (H{sub 2}) and mixture (H{sub 2}+%Ar) are being studied. In order to obtain an estimation of the ions energy spectrum and ionization grade, by using time of flight method, a graphite collector system operating in the bias ion collector mode was constructed and it is being used. Preliminary results of the ion beams measurements in different experimental conditions, at a plasma focus device of 400 joules (PF-400 J) are presented.

Moreno, Jose; Pavez, Cristian; Soto, Leopoldo [Comision Chilena de Energia Nuclear, Casilla 188-D, Santiago (Chile); Center for Research on Plasma Physics and Pulsed Power (Chile); Tarifeno, Ariel [Center for Research on Plasma Physics and Pulsed Power (Chile); Universidad de Concepcion, Concepcion (Chile); Reymond, Piotr; Verschueren, Nicolas; Ariza, Pablo [Universidad de Chile, Santiago (Chile)

2009-01-21

163

Reliable high-repetition-rate femtosecond microJoule fiber lasers for precision applications  

NASA Astrophysics Data System (ADS)

As applications demanding microJoule level pulses at "real-time" rates of delivery increase, and the expectations in terms of long-term, reliable, high quality performance become greater, fiber lasers are becoming increasingly attractive sources. When a combination of excellent beam quality, flexibility in design for repetition rate over 100 kHz - 5 MHz, and robust design for operation in a variety of environments, in a plug-and-play, non-water cooled package are necessary, IMRA"s fiber chirped-pulse amplifier (FCPA) system delivers in a compact, single-box solution. This type of laser has particular promise in precision material processing applications, enabling the use of technology that was previously considered too unstable or difficult to use. The basis for this advanced technology is a novel Yb:fiber oscillator/amplifier combination. The modular design architecture ensures a very robust construction that is well-suited to integration into commercial systems. To show the utility of such a laser in commercial applications, results of ablation thresholds and processing tests of various materials including metals and dielectrics are presented using IMRA"s FCPA &muJewel femtosecond fiber laser.

Stock, Michelle L.; Sucha, Gregg D.; Bovatsek, James; Yamamoto, Tadashi; Arai, Alan

2005-03-01

164

Statistical spatio-temporal properties of the Laser MegaJoule speckle  

SciTech Connect

This paper investigates a statistical model to describe the spatial and temporal properties of hot spots generated by the superimposition of multiple laser beams. In the context of the Laser MegaJoule design, we introduce the formula for contrasts, trajectories and velocities of the speckle pattern. Single bundle of four beams, two-cones and three-cones configurations are considered. Statistical properties of the speckle in the zone where all the beams overlap are studied with different configurations of polarizations. These properties are shown to be very different from the case of one single bundle of four beams. The configuration of polarization has only a slight effect in the two-cones or three cones configuration. Indeed, the impact of the double polarization smoothing is reduced in the area in which all the beams overlap, while it is much more significant when they split. Moreover, the size of the hot-spots decreases as the number of laser beams increases, but we show that their velocity decreases. As a matter of fact, the maximal velocity of hot spots is found to be only about 10{sup -5} of the velocity of light and the integrated contrast is about 15% when the beams overlap.

Le Cain, A.; Sajer, J. M. [CEA, DAM, CESTA, BP 2, F-33114 Le Barp (France); Riazuelo, G. [CEA, DAM, DIF, F-91297 Arpajon (France)

2012-10-15

165

Development of a low-noise 10 K J-T (Joule-Thomson) refrigeration system. Technical report (Final)  

Microsoft Academic Search

This report summarizes work done on the development of a low-noise Joule-Thomson, microminiature refrigeration system designed for 10 K operation. Topics discussed include: calculation of phase diagram of mixtures of certain hydrocarbon gases with nitrogen using the Benedict-Webb-Rubin equation of state; the setup of a magnetron-enhanced sputtering system to allow sputtering a layer of adhesive on the glass substrates with

1987-01-01

166

The State of the Neutral Atmosphere and the Electron Precipitation During JOULE From the Photometer and Electron Energy Analyzer Experiments  

Microsoft Academic Search

The JOULE rocket experiment was launched from Poker Flat Research Range at 12:09:01 UT on March 27th 2003. The payload included two instruments built at Aerospace Corporation designed to measure the neutral atmosphere and the associated particle precipitation. The photometer experiment consisted of three liquid nitrogen cooled filter photometers which measured the emission from the the N2+ (0,0) band at

J. H. Hecht; J. H. Clemmons; P. L. Slocum; D. Strickland

2003-01-01

167

Comparison of low noise cooling performance of a Joule-Thomson cooler and a pulse-tube cooler using a HT SQUID  

Microsoft Academic Search

Due to their intrinsic low mechanical vibration level both, Joule-Thomson refrigerator and Pulse-Tube refrigerator are promising candidates for low noise cooling of high-Tc SQUIDs. We report here on a test comparing the performance of a commercial Joule-Thomson cooler and a single stage Pulse-Tube cooler used to operate one and the same HT rf SQUID under comparable conditions in shielded environment.

R. Hohmann; C. Lienerth; Y. Zhang; H. Bousack; G. Thummes; C. Heiden

1999-01-01

168

Investigation of Void Nucleation and Propagation in the Joule Heating Effect During Electromigration in Flip-Chip Solder Joints  

NASA Astrophysics Data System (ADS)

This study analyzes the effect of void propagation on the temperature increase of solder joints by using x-ray microscopy, Kelvin probes, and infrared microscopy. It was found that the temperature rise due to void formation was less than 1.3°C when the voids depleted about 75% of the contact opening, even though bump resistance had increased to 10.40 times its initial value. However, the temperature rose abruptly with an increase of up to 8.0°C when the voids depleted 96.2% of the contact opening. A hot spot was observed immediately before the occurrence of open failure in the solder bump. The local increase in temperature was about 30.2°C at the spot. This spot may be the remaining contact area immediately before the occurrence of open failure.

Chang, Y. W.; Chiu, S. H.; Chen, Chih

2010-11-01

169

Two-Way Shape Change Polymeric Laminate with Fast, Large and Controllable Deformation in Response to Joule Heat.  

National Technical Information Service (NTIS)

In this project a polymeric laminate composite was fabricated from a carbon fiber reinforced plastic (CFRP) plate and a polyvinylchloride (PVC). The PVC-CFRP laminate worked as a bimorph actuator. Bending behavior of the PVC- CFRP laminate was tested by f...

H. Tamagawa

2011-01-01

170

Joule heating treatments of conductive butyl rubber\\/ceramic superconductor composites: a new way for improving the stability and reproducibility?  

Microsoft Academic Search

The present paper describes the effect of superconductors on the sintering process, apparent cross-linking density, sintering factor, hardness and volume fraction of butyl rubber (IIR) composites. Electrical conductivity and I–V characteristics at various processing conditions of IIR with different concentrations of superconductor were measured. The stability and reproducibility of IIR composites were tested. Also, the conduction mechanism of electrical conductivity

Farid El-Tantawy

2001-01-01

171

Heat dissipation from suspended self-heated nanowires: gas sensor prospective  

NASA Astrophysics Data System (ADS)

The strong temperature dependence of the electrical conductivity in semiconductors was employed for gas and pressure sensing with a self-heated Si nanowire resistor. The electrical conductivity in such a device depends on heat dissipation and partitioning inside the device and was studied comparatively for suspended and supported device architectures. The appearance of the exhaustion region in the temperature-dependent resistivity of a Joule-heated nanowire was used as a temperature marker for implementation of the quasi-constant temperature operation mode. At low pressures, the sensor is idle due to dominant heat dissipation from the nanowire to the substrate and/or electrodes. Above ca. 10 Torr the sensitivity to gases has a strong dependence on pressure as well as on the type of gas and is determined by conductive heat transfer between the nanowire surface and ambient. This implies that, in contrast to macroscopic devices, the heat dissipation via the convection mechanism does not contribute significantly to the heat transfer from the self-heated nanowire. The thermal sensitivity of the sensor to reactive gases depends on the effectiveness of the particular endothermic/exothermic reaction at the surface of the nanowire and was explored for the case of acetone–air mixture. The strong coupling of the electrical and thermal properties in the individual Joule-heated semiconducting nanowire allows fabrication of power-efficient multi-parametric nanoscopic gas/pressure sensors that are analogs of Pirani and pellistor type detectors.

Zhang, Jie; Strelcov, Evgheni; Kolmakov, Andrei

2013-11-01

172

Heat dissipation from suspended self-heated nanowires: gas sensor prospective.  

PubMed

The strong temperature dependence of the electrical conductivity in semiconductors was employed for gas and pressure sensing with a self-heated Si nanowire resistor. The electrical conductivity in such a device depends on heat dissipation and partitioning inside the device and was studied comparatively for suspended and supported device architectures. The appearance of the exhaustion region in the temperature-dependent resistivity of a Joule-heated nanowire was used as a temperature marker for implementation of the quasi-constant temperature operation mode. At low pressures, the sensor is idle due to dominant heat dissipation from the nanowire to the substrate and/or electrodes. Above ca. 10 Torr the sensitivity to gases has a strong dependence on pressure as well as on the type of gas and is determined by conductive heat transfer between the nanowire surface and ambient. This implies that, in contrast to macroscopic devices, the heat dissipation via the convection mechanism does not contribute significantly to the heat transfer from the self-heated nanowire. The thermal sensitivity of the sensor to reactive gases depends on the effectiveness of the particular endothermic/exothermic reaction at the surface of the nanowire and was explored for the case of acetone-air mixture. The strong coupling of the electrical and thermal properties in the individual Joule-heated semiconducting nanowire allows fabrication of power-efficient multi-parametric nanoscopic gas/pressure sensors that are analogs of Pirani and pellistor type detectors. PMID:24113219

Zhang, Jie; Strelcov, Evgheni; Kolmakov, Andrei

2013-10-10

173

A mathematical analysis of heating effects and electrode erosion in conical electrical arc cathodes  

Microsoft Academic Search

A spherical system of coordinates is used to solve the time-dependent heat-conduction equation for inside a conical cathode, whose surface is subjected, during arc welding processes, to complicated thermal heat-exchange effects. These arise from a variety of factors such as ion bombardment from the main body of the electrical arc, thermionic emission from the cathode's surface and Joule heating arising

Pablo Solana; Phiroze Kapadia; John Dowden

1998-01-01

174

Influence of the Joule-Thomson effect on the flow of a vapor through a micro-porous membrane  

NASA Astrophysics Data System (ADS)

The flow of a fluid near saturation through a micro-porous membrane is considered. Upstream of the membrane, the fluid is in a state of saturated vapor. Downstreams, there is unsaturated vapor which is, due to the Joule-Thomson effect, cooler than at the upstream side. The flow is described taking into account the Joule-Thomson effect and the wetting properties between the fluid and the membrane material, i.e., the capillary pressure across a curved meniscus and capillary condensation. Different types of flow occur, depending on the permeability of the membrane, on the wetting properties between the fluid and the membrane and on the pressure difference. The fluid condenses either fully or partially at the front surface of the membrane, or a liquid film forms in front of the membrane. Liquid or a two-phase mixture flows through a part or all of the membrane and evaporates either within the membrane or at the downstream front of the membrane, or the fluid evaporates at the upstream front of the membrane and vapor flows through the entire membrane. The different types of flow are discussed and the conditions under which they occur are presented.

Loimer, Thomas

2005-11-01

175

Time delay of triggered vacuum switch based on heat conduction model  

Microsoft Academic Search

The triggered vacuum switch (TVS) is a normally nonconducting device in which a high-current metal-vapor arc can be established by a suitable pulse of current to a triggering electrode. It is suggested that the initial breakdown of the trigger gap occurs in the gases desorbed from the surface of the dielectric coated on the cathode due to Joule heating. The

Liao Minfu; Duan Xiongying; Zhou Zhengyang; Zou Jiyan

2010-01-01

176

Heat transfer in GTA welding arcs  

NASA Astrophysics Data System (ADS)

Heat transfer characteristics of Gas Tungsten Arc Welding (GTAW) arcs with arc currents of 50 to 125 A and arc lengths of 3 to 11 mm were measured experimentally through wet calorimetry. The data collected were used to calculate how much heat reported to the cathode and anode and how much was lost from the arc column. A Visual Basic for Applications (VBA) macro was written to further analyze the data and account for Joule heating within the electrodes and radiation and convection losses from the arc, providing a detailed account of how heat was generated and dissipated within the system. These values were then used to calculate arc efficiencies, arc column voltages, and anode and cathode fall voltages. Trends were noted for variances in the arc column voltage, power dissipated from the arc column, and the total power dissipated by the system with changing arc length. Trends for variances in the anode and cathode fall voltages, total power dissipated, Joule heating within the torches and electrodes with changing arc current were also noted. In addition, the power distribution between the anode and cathode for each combination of arc length and arc current was examined. Keywords: Gas Tungsten Arc Welding, GTAW, anode fall, cathode fall, heat transfer, wet calorimetry

Huft, Nathan J.

177

A mathematical analysis of heating effects and electrode erosion in conical electrical arc cathodes  

NASA Astrophysics Data System (ADS)

A spherical system of coordinates is used to solve the time-dependent heat-conduction equation for inside a conical cathode, whose surface is subjected, during arc welding processes, to complicated thermal heat-exchange effects. These arise from a variety of factors such as ion bombardment from the main body of the electrical arc, thermionic emission from the cathode's surface and Joule heating arising from the main current-carrying body of the cathode. The heat-conduction equation has a time-dependent source term arising from a combination of Joule heating and thermionic emission and is solved analytically using integral transform techniques. The solution is expressed in terms of integrals. These allow the response of the cathode for various currents and cathode geometries to be studied.

Solana, Pablo; Kapadia, Phiroze; Dowden, John

1998-12-01

178

Experimental demonstration of joule-level non-collinear optical parametric chirped-pulse amplification in yttrium calcium oxyborate.  

PubMed

In this Letter, we report on what is, to our knowledge, the first experimental demonstration of yttrium calcium oxyborate (YCOB) for joule-level and broadband non-collinear optical parametric chirped-pulse amplification centered at 800 nm. Based on a Ti:sapphire chirped-pulse amplification front end, an amplified signal energy of 3.36 J was generated with a pump of 35 J in the crystal. Compressed pulse duration of 44.3 fs, with a bandwidth of 49 nm, was achieved. The results confirm that YCOB crystal is another potential alternative as a final amplifier besides Ti:sapphire in a petawatt laser at 800 nm. PMID:22627546

Yu, Lianghong; Liang, Xiaoyan; Li, Jinfeng; Wu, Anhua; Zheng, Yanqing; Lu, Xiaoming; Wang, Cheng; Leng, Yuxin; Xu, Jun; Li, Ruxin; Xu, Zhizhan

2012-05-15

179

RLCYC 75?:?a 2 kW electrically calibrated laser calorimeter designed for Laser MegaJoule diagnostics calibration  

NASA Astrophysics Data System (ADS)

RLCYC 75 is a new electrically calibrated laser calorimeter specially manufactured by Laser Metrology to calibrate energy diagnostics within the Laser MegaJoule (LMJ) facility. It consists of an optical cavity cooled by a hydraulic system. The system is designed to provide 1 µm wavelength power laser measurements with uncertainty less than 1% at 2 kW and traceability to the International System of Units (SI). In this paper, the accuracy of RLCYC 75 measurements is studied. More precisely, three points are detailed: instrumentation uncertainty estimation, equivalence between optical and electrical supply and light absorption. To this end, electrical calibration campaigns and power laser measurement campaigns are conducted. Moreover, thermal and optical models are developed. Results show that RLCYC 75 design and instrumentation are efficient enough to reach the goal of relative uncertainty of about 1% at 2 kW. RLCYC 75 will become the 2 kW laser power primary standard for LMJ applications.

Crespy, C.; Villate, D.; Soscia, M.; Coste, F.; Andre, R.

2013-02-01

180

Material End Plugging of a Laser Heated Solenoid  

Microsoft Academic Search

Polycarbonate end plugs were inserted into the ends of a fast rising, crowbarred solenoid. A 350 joule, 1.5 (mu)sec CO(,2) laser pulse focused through a small hole in the end plug heated the preionized plasma to approximately 40 eV during the initial stages of compression. Experimental parameters are: n(,e) = 3 x 10('17)cm('-3), T(,e) = T(,i) = 40 eV, B

Thomas Neil Carlstrom

1982-01-01

181

ACTIVE COMPOSITE RIGIDIZATION USING TEMPERATURE-CONTROLLED RESISTIVE HEATING  

Microsoft Academic Search

An active approach for initiating rigidization in carbon-fiber reinforced polymer (CFRP) compos- ites unites electrical resistivity to mechanical stiff- ening. Temperature control is implemented in ef- forts to reduce the curing time of the composite and to increase control of the curing process. Specif- ically, proportional-integral (PI) feedback control of internal resistive (Joule) heating establishes an electrically-controlled, thermally-activated material. Precise

Stephen A. Sarles

182

Simulation of Isoenthalps and Joule-Thomson Inversion Curves of Pure Fluids and Mixtures  

Microsoft Academic Search

This paper examines the molecular simulation of expansion and compression processes of fluids under common non-isothermal conditions. It is shown that accurate isoenthalps can be traced if simulated configurational properties obtained from the particular molecular force-field adopted are complemented by experimentally-based data for the ideal-gas contributions to the heat capacity. The simulation of inversion curves is also analyzed and found

Fernando A. Escobedo; Zhong Chen

2001-01-01

183

A Si\\/Glass Bulk-Micromachined Cryogenic Heat Exchanger for High Heat Loads: Fabrication, Test, and Application Results  

Microsoft Academic Search

This paper reports on a micromachined Si\\/glass stack recuperative heat exchanger with in situ temperature sensors. Numerous high-conductivity silicon plates with integrated platinum resistance temperature detectors (Pt RTDs) are stacked, alternating with low-conductivity Pyrex spacers. The device has a 1 ?? 1-cm2 footprint and a length of up to 3.5 cm. It is intended for use in Joule-Thomson (J-T) coolers

Weibin Zhu; Michael J. White; Gregory F. Nellis; Sanford A. Klein; Yogesh B. Gianchandani

2010-01-01

184

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

Microsoft Academic Search

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

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

2012-01-01

185

Enhanced heat transfer computations for internally cooled cable superconductor  

SciTech Connect

Superconducting magnets are built with conductors that are pool bath cooled, internally cooled with the superconductor cabled and contained within a conduit, or conduction cooled. The first two embody superconductors in direct contact with liquid helium. Practical designs of internally cooled cable superconductor (ICCS) are not cryostable. Such superconductors have shown multiple regions of stability and instability. A computational method of adjusting the heat transfer coefficient of a one dimensional system of equations to enhance joule heat removal, primarily in the central region of a pulse heated model of ICCS, has been used to attempt simulation of the multiple stability/instability experiment.

Rogers, J.D.

1985-01-01

186

Electron Heating and the Farley-Buneman Instability in the Solar Chromosphere  

Microsoft Academic Search

Convective motion in the solar chromosphere has generally more than enough energy to po-tentially explain observed heating, but the possible dissipation mechanisms disserve more con-sideration. When, driven by electric fields, neutrals and ions move at different fluid velocities, like it happens in the Earth's thermosphere, then ion-neutral collisions cause friction and Joule heating. Because of a relatively short neutral-ion collision

Stephan Buchert

2010-01-01

187

Modeling and optimization of thin disk structure for high power sub-joule laser  

NASA Astrophysics Data System (ADS)

We analyzed the transient response characteristics of Yb:YAG thin disk in to clarify the experimentally obtained advantages of pulsed pumping in 1-kHz repetition rate reported in ref. 2. We applied commercial 2D FEA software which can calculate transient response of thermal effects. The temperature distributions of thin disk in both the CW power of 125-W and the average power of pulsed 125-W have been calculated. Even the net heat power were same in both CW and pulsed pumping, the temperature distribution was lower in pulsed pumping which can provide higher O-O efficiency and smaller beam distortion. The time evolution of OPD in the pulsed pumping has been analyzed, too.

Severová, Patricie; Smrz, Martin; Chyla, Michal; Miura, Taisuke; Endo, Akira; Mocek, Tomáš

2013-05-01

188

Local thermal heating in VO2 electric-field-induced metal insulator transition  

NASA Astrophysics Data System (ADS)

Over recent years, the insulator to metal transition (IMT) of the vanadium dioxide (VO2) Mott insulator has been revisited revealing an electric-field-induced resistance switching. Whether this feature is purely due to an electrical field effect or due to some Joule heating is still under debate. Here we report a local temperature measurement in a 10?m and a 20?m VO2 junction while going through the resistance switching. The sample was placed at ?T=15K below 340K (the thermally induced insulator to metal transition). When ramping up the voltage across the junction we find that the local heating inside the VO2 junction is close to 15K. This data suggests that in these temperature, current and voltage ranges, the field induced IMT can be explained by local Joule heating. Work supported by the French ANR-09-BLAN-0388-01 and the US DOE and AFOSR.

Zimmers, A.; Aigouy, L.; Sharoni, A.; Wang, S.; Ramirez, J. G.; Schuller, I. K.

2012-02-01

189

Vibration Characterization and Reduction of a Joule-Thomson Cryocooler for a Squid-Based Metal Detection System  

NASA Astrophysics Data System (ADS)

Very sensitive high-temperature SQUID (Superconducting Quantum Interference Device) magnetometers are used for the detection of very small metal contaminants in food and other products. When the SQUIDs are cooled with liquid nitrogen, a detection sensitivity of 500 nA-m2 in a 150×150 mm2 orifice is obtained. However, when a commercial Joule-Thompson cryocooler was used, the sensitivity was reduced by a factor of 5 due to spurious magnetic signals. In this study the emphasis is on understanding noise that may be created due to mechanical vibrations in the cryocooler cold head. The natural frequencies of the cryocooler cold head are modelled and two mechanisms of noise generation are considered and analysed. Calculations show that the noise created by vibrating dipoles in the cold head may create noise of 1 pT up to 20 pT in the frequency range of 10 to 50 Hz. The vibration characteristics of several parts of the cryocooler cold head assembly were determined with a laser vibrometer, a fluxgate magnetometer and through finite element simulations. Two natural frequencies of approximately 21 and 49 Hz are particularly noticeable and are also observed in the SQUID noise. Anti-vibration measures are introduced to reduce external vibrations.

Groot, G. J. J. B. De; Santin, M. A.; Thijssen, T.

2008-03-01

190

Current-Driven Instabilities and Coronal Heating  

NASA Astrophysics Data System (ADS)

Radioastronomical observations of the solar corona have yielded measurements consistent with coronal currents ˜2.5 x10^9 Amperes inside an Amperian Loop with a width of about 35,000 km (Spangler, Astrophysical Journal, 670, 841, 2007). An estimate has been made of the coronal heating due to Joule heating by these currents. It is assumed that the current is concentrated in thin current sheets, as suggested by theories of MHD turbulence. If the Joule heating is to be astrophysically significant, the resistivity in the corona must be enhanced by about 6 orders of magnitude relative to the Spitzer value. In this paper, I explore the possibility that instabilities produced by these currents could be responsible for generating waves and turbulence which raise the resistivity to significant levels. Model-dependent calculations of the electron drift speed in the current sheets indicate that speeds of order the electron thermal speed are possible. Current-driven instabilities and their associated waves are therefore feasible. These drift speeds also exceed the ion acoustic speed, which would excite lower hybrid waves and enhance the resistivity.

Spangler, Steven

2008-11-01

191

Ionospheric heating with oblique HF waves  

SciTech Connect

This paper presents calculations of ionospheric electron density perturbations and ground-level signal changes produced by intense oblique high-frequency (HF) transmitters. Our analysis takes into account radio field 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. We then seek effects on a secondary 'test wave that is propagated along the same path as the first. Our calculations predict ground-level field-strength reductions of several dB in the test wave for modifying waves having 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. Our results are sensitive to the the model ionosphere assumed, so future experiments should employ the widest possible range of frequencies and propagation conditions. An effective power of 90 dBW seems to be a sort of threshold that, if exceeded, results in substantial rather than small signal changes. Our conclusions are based solely on joule-heating and subsequent defocusing of waves passing through caustic regions.

Field, E.C.; Bloom, R.M.

1990-10-01

192

Evaporation of refrigerants in a smooth horizontal tube: prediction of R22 and R507 heat transfer coefficients and pressure drop  

Microsoft Academic Search

This paper presents experimental heat transfer coefficients and pressure drop results obtained during the evaporation of pure R22 and the azeotropic mixture R507 (R125–R143a 50%\\/50% in weight). The test section was a smooth, horizontal, stainless steel tube (6 mm ID, 6 m length) uniformly heated by Joule effect. The effects of heat flux, mass flux and evaporation pressure on the

Adriana Greco; Giuseppe Peter Vanoli

2004-01-01

193

Improvement of heat dissipation for polydimethylsiloxane microchip electrophoresis.  

PubMed

Effective removing of Joule heat in polymer-based microchip system is an important factor for high efficient separation because of lower heat conductivity of polymers than silica or glass. In this paper, a new kind of polydimethylsiloxane (PDMS) microchip electrophoresis system integrated with a laser-induced fluorescence detector has been successfully constructed on the basis of a commercial heat sink for computer CPU (central processor unit). Experimental results on separation current using high concentration running buffers demonstrated that heat dissipation of PDMS/PDMS microchip system was significantly improved. Furthermore, with this integrated system, theoretical plate number of fluorescein using 100 mM phosphate-buffered saline + 1 mM sodium dodecyl sulfate as running buffer was determined to be 2750 (for 2.5-cm separation channel, corresponding to 110,000/m). This high separation efficiency demonstrated that such heat sink-based polymer microchip system could be effectively applied for high-concentration buffers. PMID:15584247

Zhang, Yuan; Bao, Ning; Yu, Xiao-Dong; Xu, Jing-Juan; Chen, Hong-Yuan

2004-11-19

194

1851-2004 annual heat budget of the continental landmasses  

NASA Astrophysics Data System (ADS)

Changing climate is accompanied by changing energy in various climate system components including the continental landmasses. When the temperature at ground surface rises, more heat will be deposited to the rocks beneath the ground subsurface, whereas when ground surface temperature falls, certain amount of heat will escape from the ground into the atmosphere. Based on the land-only global meteorological record, I analyze the annual heat budget of the world continents except for Antarctica. I show that between the period from 1851 to 2000 a total of 10.4 ZJ (Zetta-Joules or 1021 J) of thermal energy had been absorbed by Africa, Asia, Australia, Europe, North America, and South America landmasses. An additional 1.34 ZJ of heat has been stored beneath the ground surface of these continents over the first four years of the 21st century from 2001 to 2004. The recent global climate change has led to an intensified heating in the continental landmasses.

Huang, Shaopeng

2006-02-01

195

A theoretical estimation of the pre-breakdown-heating time in the underwater discharge acoustic source  

NASA Astrophysics Data System (ADS)

One of the common characteristics of the electrothermal breakdown in an underwater discharge acoustic source (UDAS) is the existence of a pre-breakdown-heating phase. In our experiment, two phenomena were observed: (1) the breakdown time that takes on high randomicity and obeys a “double-peak" stochastic distribution; (2) the higher salt concentration that reduces the residual voltage and causes 100% non-breakdown. The mechanism of electrothermal breakdown is analysed. To specify the end of the pre-breakdown-heating phase, a “border boiling" assumption is proposed, in which the breakdown time is assumed to be the time needed to heat the border water around the initial arc to 773 K. Based on this ‘border boiling’ assumption, the numerical simulation is performed to evaluate the effects of two heating mechanisms: the Joule heating from the ionic current, and the radiation heating from the initial arc. The simulation results verify the theoretical explanations to these two experiment phenomena: (1) the stochastic distribution of the radius of the initial arc results in the randomicity of the breakdown time; (2) the difference in efficiency between the radiation heating and the Joule heating determines that, in the case of higher salt concentration, more energy will be consumed in the pre-breakdown-heating phase.

Wang, Yi-Bo; Wang, Shang-Wu; Zeng, Xin-Wu

2012-05-01

196

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

NASA Astrophysics Data System (ADS)

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 1?m) 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.

Azerou, B.; Garnier, B.; Lahmar, J.

2012-11-01

197

Contact glow discharge electrolysis: a study on its origin in the light of the theory of hydrodynamic instabilities in local solvent vaporisation by Joule heating during electrolysis  

Microsoft Academic Search

Normal electrolysis at high voltages switches over spontaneously to contact glow discharge electrolysis. The transition is profoundly facilitated by raising the temperature and\\/or lowering the surface tension of the electrolyte. Results of a systematic study on the influence of these two factors on the breakdown voltage for normal electrolysis have been critically analysed. It has been concluded that solvent vaporisation

Susanta K. Sengupta; Ashok K. Srivastava; Rajeshwar Singh

1997-01-01

198

Use of Optical and Imaging Techniques for Inspection of Off-Line Joule-Heated Melter at the West Valley Demonstration Project  

SciTech Connect

The West Valley melter has been taken out of service. Its design is the direct ancestor of the current melter design for the Hanford Waste Treatment Plant. Over its eight years of service, the West Valley melter has endured many of the same challenges that the Hanford melter will encounter with feeds that are similar to many of the Hanford double shell tank wastes. Thus, inspection of the West Valley melter prior to its disposal could provide valuable--even crucial--information to the designers of the melters to be used at the Hanford Site, particularly if quantitative information can be obtained. The objective of Mississippi State University's Diagnostic Instrumentation and Analysis Laboratory's (DIAL) efforts is to develop, fabricate, and deploy inspection tools for the West Valley melter that will (i) be remotely operable in the West Valley process cell; (ii) provide quantitative information on melter refractory wear and deposits on the refractory; and (iii) indicate areas of heterogeneity (e.g., deposits) requiring more detailed characterization. A collaborative arrangement has been established with the West Valley Demonstration Project (WVDP) to inspect their melter.

Plodinec, M. J.; Jang, P-R; Long, Z.; Monts, D. L.; Philip, T.; Su, Y.

2003-02-25

199

Ionospheric heating with oblique high-frequency waves  

SciTech Connect

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.

Field, E.C. Jr.; Bloom, R.M. (Pacific-Sierra Research Corp., Los Angeles, CA (USA)); Kossey, P.A. (Air Force Geophysical Lab., Bedford, MA (USA))

1990-12-01

200

International Heat Flow Commission Celebrates 40 Years  

NASA Astrophysics Data System (ADS)

The outflow of heat from the Earth's interior is, in terms of energy, the most impressive terrestrial phenomenon. Its present rate of about 10?21 joules per year is order-of-magnitudes greater than the energy dissipation of earthquakes or heat loss from volcanic eruptions. The study of the Earth's internal heat plays an important role in understanding the Earth's origin, internal constitution,and plate tectonics. The thermal structure of the Earth, generally referred to as the geothermics, or also as the (terrestrial) heat flow, has been studied for a long time. However,modern geothermics,one of the fundamental geophysical disciplines, is relatively young.The International Heat Flow Commission (IHFC), under which the academic geothermal research on the international scale is organized,was created only in 1963. The IHFC, operating under the International Association of Seismology and Physics of the Earth's Interior (IASPEI),covers a broad scope of geophysical studies, and links the activities of other associations of the International Union of Geodesy and Geophysics (IUGG). These are the International Association of the Physical Sciences of the Ocean (IAPSO), the International Association of Volcanology and Chemistry of the Earth's Interior (IAVCEI), and the International Association of the Hydrological Sciences (IAHS). Geothermal research is further related to a number of geological, hydrogeological, and geochemical investigations covered by the International Union of Geological Sciences (IUGS). In their practical applications, the heat flow studies are in general related to the mission of the International Geothermal Association (IGA).

Cermak, Vladimir; Lee, H. K.

2004-01-01

201

Thermal modelling of RLCYC 75: a 2kW electrically calibrated laser calorimeter designed for Laser MegaJoule diagnostics calibration  

NASA Astrophysics Data System (ADS)

RLCYC 75 is a new electrically calibrated laser calorimeter especially manufactured by Laser Métrologie to calibrate energy diagnostics of Laser MegaJoule (LMJ). It consists of an optical cavity cooled by a hydraulic system. The system is designed to provide laser power measurements with uncertainty less than 1% at 2kW and traceability to the International System of Units (SI) thanks to electrical calibrations. In this paper, a 3D thermal model is developed to study the thermal equivalence between electrical calibration and optical measurement. The simulation results are crossed with PT100 measurements in order to validate the model. The thermal modelling of the RLCYC 75 calorimeter is a key point to analyse the calorimeter efficiency, thus this work validates the geometrical design of RLCYC 75 calorimeter.

Crespy, C.; Villate, D.; Todeschini, M.; Laville-Geay, A.; Soscia, M.

2012-11-01

202

Coupled electron-heat transport in nonuniform thin film semiconductor structures  

NASA Astrophysics Data System (ADS)

A theory of transverse electron transport coupled with heat transfer in semiconductor thin films is developed, conceptually modeling structures of modern electronics. The transverse currents generate Joule heat with positive feedback through thermally activated conductivity. This can lead to instability known as thermal runaway, or hot spot, or reversible thermal breakdown. A theory here is based on the optimum fluctuation method modified to describe saddle stationary points determining the rate of such instabilities and conditions under which they evolve. Depending on the material and system parameters, the instabilities appear in a manner of phase transitions, similar to either nucleation or spinodal decomposition.

Karpov, V. G.

2012-10-01

203

Self-heating effects on the transition to a highly dissipative state at high current density in superconducting YBa2Cu3O7-delta thin films  

Microsoft Academic Search

We report current-voltage characteristics (CVC's) and voltage against time curves at constant current on c-axis oriented YBa2Cu3O7-delta superconducting thin-film microbridges. Measurements were done up to high enough current densities to trigger the quenching, i.e., an abrupt voltage jump to a highly dissipative state. Our data analyses show that, due to the nonlinear behavior of the measured CVC's, uniform Joule heating

J. Viña; M. T. González; M. Ruibal; S. R. Currás; J. A. Veira; J. Maza; F. Vidal

2003-01-01

204

Heating system  

Microsoft Academic Search

A method for recovering waste heat from heating system exhaust gas is described. In a heating system located in a furnace room and including a furnace and an air blower for delivering air to the furnace via an inlet stack and heating pipes for the delivery of heated air from the furnace to the areas to be heated, the improvement

Anable

1975-01-01

205

Transient Heat Transfer Measurements in Forced Flow of He II at High Velocities  

SciTech Connect

Transient heat transfer is investigated in forced flow of He II for velocities up to 22 m/s. The flow is generated in a 10 mm ID, 0.85 m long straight test section instrumented with heaters, thermometers and pressure transducers. Rectangular heat pulses are generated in the flow and the temperature is measured at several locations as the pulses are carried by the forced flow with their shape being transformed by counterflow heat transfer. The linear pressure drop in the flow also results in a linear temperature gradient due to the Joule-Thomson effect and therefore has an influence in the heat transfer process. The effectiveness of the counterflow heat transfer also appears to decrease at the highest flow velocities.

Fuzier, S.; Van Stiver, S. W. [National High Magnetic Field Laboratory, Mechanical Engineering Department, FAMU-FSU College of Engineering, Tallahassee, Florida 32310 (United States)

2006-04-27

206

Numerical investigation of the plasma flow through the constrictor of arc-heated thrusters  

NASA Astrophysics Data System (ADS)

A modelling study is performed to investigate the plasma flow through the constrictor of medium-power arc-heated thrusters. The Roe scheme is employed to solve the governing equations, which take into account the effects of compressibility, Joule heating and the Lorentz force, as well as the temperature and pressure dependence of the gas properties. The modelling results show that the gas flow within the constrictor is choked by the combined effects of friction and arc heating. The computed total pressure drop within the constrictor due to friction and arc heating is about twice the dynamic head at the constrictor outlet. The effects of the arc current, inlet pressure and mass flow rate, and the constrictor length and diameter on the gas flow characteristics within the constrictor are presented and discussed. Further, it is shown that the choking effects caused by arc heating reduce the flow rate more strongly for argon and nitrogen working gases than for hydrogen working gas.

Wang, Hai-Xing; Wei, Fu-Zhi; Murphy, A. B.; Liu, Yu

2012-06-01

207

Coronal Heating and the Solar Wind Acceleration  

NASA Astrophysics Data System (ADS)

The twisting magnetic field as the DC energy injection will produce charge separation and consequently an electric field parallel to the magnetic field. Accelerated beam electrons (a few times thermal velocity) due to this electric filed will be stopped by classical collisions with ambient electrons and ions. The beam electrons, 10-3 of the bulk electrons, do not create electric currents due to the back streaming bulk electrons. Hence it is not the normal or anomalous Joule heating, but a co-spatial frictional heating, and yet bulk heating. The heating rate is the kinetic energy density of beams multiplied by the classical collision frequency, and is about 10-4 erg cm-3 s-1. It successfully reproduces observations of quiet and active regions, including the RTV scaling law. In the open field, the damping length of this Alfvénic twist is 0.4 solar radii. This is appropriate to produce slow and high-speed solar winds. Ion-cyclotron waves may be excited due to supra-thermal beams.

Hirayama, T.

208

Applicability of the Joule-Thomson Cryocooler Coupled with Membrane-Based Purification System for Liquefaction of Natural Gas in Small Quantities  

NASA Astrophysics Data System (ADS)

Joule-Thomson (J-T) cryocoolers using gas mixture have been studied theoretically and experimentally for a variety of applications. Gas separation technology using polymer membrane is emerging. In this paper the concept of coupling the J-T cooler with a hollow fiber membranes is presented. The apparatus can be used in many applications, like compressed natural gas (CNG) purification and condensation into LNG or separation and liquefaction of nitrogen from air. The paper describes the system and experimental dependence of the separated nitrogen purity on the membrane inlet air pressure. The Second Law of Thermodynamics is used to optimize the composition of the mixture for natural gas cooling and liquefaction. Possible applications of the system depend on membrane material. Membranes used in separation of N2/air or CO2/CH4 are now commercially available [2,6]. The combination of the J-T cooler with N2/air membrane enables the construction of the liquid nitrogen production system aimed at cryosurgical applications. Similarly, J-T cooler coupled with CO2/CH4 membrane can be used for purification and liquefaction of natural gas in small quantities e.g. satisfying future car refueling system needs.

Piotrowska, A.; Chorowski, M.

2008-03-01

209

Brief Heating Events Observed by EISCAT Svalbard Radar  

NASA Astrophysics Data System (ADS)

On 20-Dec-1998, the EISCAT Svalbard Radar was running in field-aligned mode from 0600-1200 UT. The auroral arc was observed by meridian scanning photometer to move from equatorward of the radar beam to poleward and back again while the radar was running, allowing measurements of the neutral temperature while the radar was measuring on closed field lines. When the auroral arc moved equatorward across the beam, 50 minutes of heating events were observed. Ion upflow is seen near all optical events, but only some show strong ion heating. Using the measured neutral temperature it is possible to estimate the scalar difference between the neutral wind and ion drift, assuming that frictional heating is the dominant ion heating mechanism. The strongest heating events do not appear to coincide spatially with optical events, rather they occur north or south of an optical event. This indicates that the heating events are caused by joule heating from reconnection-related transient flow channels.

Skjæveland; Moen, J.; Carlson, H. C.

2009-12-01

210

Heating of microprotrusions in accelerating structures  

NASA Astrophysics Data System (ADS)

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?m with vacuum fields on their surface less than 12GV/m, and for rf frequencies above 1 GHz.

Keser, A. C.; Antonsen, T. M.; Nusinovich, G. S.; Kashyn, D. G.; Jensen, K. L.

2013-09-01

211

Graphitization of amorphous carbon on a multiwall carbon nanotube surface by catalyst-free heating  

NASA Astrophysics Data System (ADS)

Structural changes in amorphous carbon coating the surfaces of multiwall carbon nanotubes (MWNTs) under applying an electric current were investigated by in situ transmission electron microscopy with simultaneous measurements of the bias voltage and electric current. Joule heating transformed amorphous carbon on the surfaces of individual MWNTs suspended between gold electrodes into graphite layers even without a metal catalyst through a phase of glasslike carbon. The MWNTs after the formation of ordered surface layers sustained a high current with a density of up to 3.1 × 108 A/cm2.

Asaka, Koji; Karita, Motoyuki; Saito, Yahachi

2011-08-01

212

Heat waves  

Microsoft Academic Search

The concept of transmission of heat by waves is reviewed and interpreted. The notion of an effective thermal conductivity, an effective heat capacity, and relaxation functions for heat and energy is introduced along lines used recently to describe the elastic response of viscous liquids. An annotated bibliography of the literature on heat waves, from the beginning until now, gives a

D. D. Joseph; Luigi Preziosi

1989-01-01

213

A novel thin-film temperature and heat-flux microsensor for heat transfer measurements in microchannels.  

PubMed

Temperature and heat-flux measurement at the microscale for convective heat-transfer studies requires highly precise, minimally intrusive sensors. For this purpose, a new generic temperature and heat-flux sensor was designed, calibrated and tested. The sensor allows measurement of temperature and heat flux distributions along the direction of flow. It is composed of forty gold thermoresistances, 85 nm thick, deposited on both sides of a borosilicate substrate. Their sensitivities are about 37.8 ?V K(-1), close to those of a K-type wire thermocouple. Using a thermoelectrical model, temperature biases due to the Joule effect were calculated using the current crossing each thermoresistance and the heat-transfer coefficient. Finally, heat-transfer measurements were performed with deionized water flowing in a straight PDMS microchannel for various Reynolds numbers. The Nusselt number was obtained for microchannels of 50 to 10 ?m span. The results were found to be in good agreement with classical Nu-Re macroscopic correlations. PMID:22179553

Hamadi, David; Garnier, Bertrand; Willaime, Herve; Monti, Fabrice; Peerhossaini, Hassan

2011-12-16

214

Ionosphere/thermosphere heating determined from dynamic magnetosphere-ionosphere/thermosphere coupling  

NASA Astrophysics Data System (ADS)

Ionosphere/thermosphere heating driven by magnetospheric convection is investigated through a three-fluid inductive (including Faraday's law) approach to describing magnetosphere-ionosphere/thermosphere coupling, for a 1-D stratified ionosphere/thermosphere in this initial study. It is shown that the response of the ionosphere/thermosphere and thus the heating is dynamic and height-dependent. The heating is essentially frictional in nature rather than Joule heating as commonly assumed. The heating rate reaches a quasi-steady state after about 25 Alfvén travel times. During the dynamic period, the heating can be enhanced and displays peaks at multiple times due to wave reflections. The dynamic heating rate can be more than twice greater than the quasi-steady state value. The heating is strongest in the E-layer but the heating rate per unit mass is concentrated around the F-layer peak height. This implies a potential mechanism of driving O+ upflow from O+ rich F-layer. It is shown that the ionosphere/thermosphere heating caused by the magnetosphere-ionosphere coupling can be simply evaluated through the relative velocity between the plasma and neutrals without invoking field-aligned currents, ionospheric conductance, and electric field. The present study provides understanding of the dynamic magnetosphere-ionosphere/thermosphere coupling from the ionospheric/thermospheric view in addition to magnetospheric perspectives.

Tu, Jiannan; Song, Paul; Vasyli?nas, Vytenis M.

2011-09-01

215

Heat removal  

Microsoft Academic Search

Studies on heat-removal technology in fusion reactors are being made at laboratories of universities and at JAERI. Activities at universities involve fundamental studies related to fluid flow and heat transfer in the MCF as well as in the ICF blanket. Activities at the JAERI involve experimental heat technology developments in the JT-60 program and fusion reactor development program. A figure

A. Inove; H. Madarame; T. Tone

1983-01-01

216

Heat exchanger  

DOEpatents

A heat exchanger is provided having first and second fluid chambers for passing primary and secondary fluids. The chambers are spaced apart and have heat pipes extending from inside one chamber to inside the other chamber. A third chamber is provided for passing a purge fluid, and the heat pipe portion between the first and second chambers lies within the third chamber.

Daman, Ernest L. (Westfield, NJ); McCallister, Robert A. (Mountain Lakes, NJ)

1979-01-01

217

A Si/Glass Bulk-Micromachined Cryogenic Heat Exchanger for High Heat Loads: Fabrication, Test, and Application Results.  

PubMed

This paper reports on a micromachined Si/glass stack recuperative heat exchanger with in situ temperature sensors. Numerous high-conductivity silicon plates with integrated platinum resistance temperature detectors (Pt RTDs) are stacked, alternating with low-conductivity Pyrex spacers. The device has a 1 x 1-cm(2) footprint and a length of up to 3.5 cm. It is intended for use in Joule-Thomson (J-T) coolers and can sustain pressure exceeding 1 MPa. Tests at cold-end inlet temperatures of 237 K-252 K show that the heat exchanger effectiveness is 0.9 with 0.039-g/s helium mass flow rate. The integrated Pt RTDs present a linear response of 0.26%-0.30%/K over an operational range of 205 K-296 K but remain usable at lower temperatures. In self-cooling tests with ethane as the working fluid, a J-T system with the heat exchanger drops 76.1 K below the inlet temperature, achieving 218.7 K for a pressure of 835.8 kPa. The system reaches 200 K in transient state; further cooling is limited by impurities that freeze within the flow stream. In J-T self-cooling tests with an external heat load, the system reaches 239 K while providing 1 W of cooling. In all cases, there is an additional parasitic heat load estimated at 300-500 mW. PMID:20490284

Zhu, Weibin; White, Michael J; Nellis, Gregory F; Klein, Sanford A; Gianchandani, Yogesh B

2010-02-01

218

A Si/Glass Bulk-Micromachined Cryogenic Heat Exchanger for High Heat Loads: Fabrication, Test, and Application Results  

PubMed Central

This paper reports on a micromachined Si/glass stack recuperative heat exchanger with in situ temperature sensors. Numerous high-conductivity silicon plates with integrated platinum resistance temperature detectors (Pt RTDs) are stacked, alternating with low-conductivity Pyrex spacers. The device has a 1 × 1-cm2 footprint and a length of up to 3.5 cm. It is intended for use in Joule–Thomson (J–T) coolers and can sustain pressure exceeding 1 MPa. Tests at cold-end inlet temperatures of 237 K–252 K show that the heat exchanger effectiveness is 0.9 with 0.039-g/s helium mass flow rate. The integrated Pt RTDs present a linear response of 0.26%–0.30%/K over an operational range of 205 K–296 K but remain usable at lower temperatures. In self-cooling tests with ethane as the working fluid, a J–T system with the heat exchanger drops 76.1 K below the inlet temperature, achieving 218.7 K for a pressure of 835.8 kPa. The system reaches 200 K in transient state; further cooling is limited by impurities that freeze within the flow stream. In J–T self-cooling tests with an external heat load, the system reaches 239 K while providing 1 W of cooling. In all cases, there is an additional parasitic heat load estimated at 300–500 mW.

Zhu, Weibin; White, Michael J.; Nellis, Gregory F.; Klein, Sanford A.; Gianchandani, Yogesh B.

2010-01-01

219

Preliminary analysis of heat pipe heat exchangers for heat recovery  

Microsoft Academic Search

A preliminary analysis of fin tube heat pipe heat exchangers for air-to-air heat recovery was conducted. The analysis uses conventional heat exchanger design techniques and a new heat pipe design technique which includes probabilistic design of artery wick heat pipes. The heat transfer capability of the heat pipes may be matched with that of the finned tubes in order to

J. O. Amode; K. T. Feldman

1975-01-01

220

Heat Related Illnesses.  

National Technical Information Service (NTIS)

Heat illnesses range in severity form mild (heat rash, heat syncope, cramps) to serious (heat exhaustion, heat injury, heat stroke). Although heat illness can occur in anyone, an increased risk is associated with a variety of environmental factors, person...

M. N. Sawka R. Carter S. N. Cheuvront

2006-01-01

221

Analytical model for self-heating in nanowire geometries  

NASA Astrophysics Data System (ADS)

An analytical closed form diffusive model is developed of Joule heating in a device consisting of a nanowire connected to two contacts on a substrate. This analytical model is compared to finite-element simulations and demonstrates excellent agreement over a wider range of system parameters in comparison to other recent models, with particularly large improvements in cases when the width of the nanowire is less than the thermal healing length of the contacts and when the thermal resistance of the contact is appreciable relative to the thermal resistance of the nanowire. The success of this model is due to more accurately accounting for the heat spreading within the contact region of a device and below the nanowire into a substrate. The heat spreading is achieved by matching the linear heat flow near the nanowire interfaces with a radially symmetric spreading solution through an interpolation function. Additional features of this model are the ability to incorporate contact resistances that may be present at the nanowire-contact interfaces, as well as accommodating materials with a linear temperature-dependent electrical resistivity.

Hunley, D. Patrick; Johnson, Stephen L.; Flores, Roel L.; Sundararajan, Abhishek; Strachan, Douglas R.

2013-06-01

222

Heating apparatus  

SciTech Connect

This patent describes a heating apparatus. It comprises a housing, means for introducing water to a plurality of water conduits of the housing, a fireplace compartment disposed within the housing, the fireplace compartment being provided with a burner, a fin coil member disposed in the upper portion of the housing and communicating with the room environment for heat emitting, the fin coil member containing a serpentine configured fin coils disposed therein for absorbing heat from the water disposed in the water conduits, a heat chamber containing the water conduits, the heat chamber connected at one end to the fireplace compartment and at the other end to a chimney disposed at the middle of the the fireplace compartment for circulating hot combustion gases therethrough and for heating the water disposed in the water conduits, the combustion gases being vented from the chimney, and at least four turbo fans communicating with the heat chamber for blowing air across the fin coil member so as to heat the air and discharge it to the room environment, and reduce noise pollution of the heating apparatus.

Woo, C.G.

1991-07-30

223

Heat Transfer  

NSDL National Science Digital Library

Students explore heat transfer and energy efficiency using the context of energy efficient houses. They gain a solid understanding of the three types of heat transfer: radiation, convection and conduction, which are explained in detail and related to the real world. They learn about the many ways solar energy is used as a renewable energy source to reduce the emission of greenhouse gasses and operating costs. Students also explore ways in which a device can capitalize on the methods of heat transfer to produce a beneficial result. They are given the tools to calculate the heat transferred between a system and its surroundings.

Integrated Teaching And Learning Program

224

Pressure drop characteristics of cryogenic mixed refrigerant at macro and micro channel heat exchangers  

NASA Astrophysics Data System (ADS)

Mixed Refrigerant-Joule Thomson (MR-JT) refrigerators are widely used in various kinds of cryogenic systems these days. The temperature glide effect is one of the major features of using mixed refrigerants since a recuperative heat exchanger in a MR-JT refrigerator is utilized for mostly two-phase flow. Although a pressure drop estimation for a multi-phase and multi-component fluid in the cryogenic temperature range is necessarily required in MR-JT refrigerator heat exchanger designs, it has been rarely discussed so far. In this paper, macro heat exchangers and micro heat exchangers are compared in order to investigate the pressure drop characteristics in the experimental MR-JT refrigerator operation. The tube in tube heat exchanger (TTHE) is a well-known macro-channel heat exchanger in MR-JT refrigeration. Printed Circuit Heat Exchangers (PCHEs) have been developed as a compact heat exchanger with micro size channels. Several two-phase pressure drop correlations are examined to discuss the experimental pressure measurement results. The result of this paper shows that cryogenic mixed refrigerant pressure drop can be estimated with conventional two-phase pressure drop correlations if an appropriate flow pattern is identified.

Baek, Seungwhan; Jeong, Sangkwon; Hwang, Gyuwan

2012-12-01

225

Heat exchanger  

Microsoft Academic Search

A heat exchanger is described in which the main component is formed of a plurality of elongated strips of rigid heat conductive material. Each of the strips has a cross-sectional configuration which is elongated in a direction transverse to the elongated extent of the strip so as to provide a pair of spaced relatively thin end edges and a pair

1982-01-01

226

Heat Acclimatization.  

National Technical Information Service (NTIS)

It is apparent that there is much more to heat acclimatization than is available in the literature. Results of this study have shown that two of the four classical parameters are not reliable indicators of heat acclimatization, particularly if one is tryi...

A. R. Dasler

1971-01-01

227

Heating Mechanisms in Short-Pulse Laser-Driven Cone Targets  

SciTech Connect

The fast ignitor is a modern approach to laser fusion that uses a short-pulse laser to initiate thermonuclear burn. In its simplest form the laser launches relativistic electrons that carry its energy to a precompressed fusion target. Cones have been used to give the light access to the dense target core through the low-density ablative cloud surrounding it. Here the ANTHEM implicit hybrid simulation model shows that the peak ion temperatures measured in recent cone target experiments arose chiefly from return current joule heating, mildly supplemented by relativistic electron drag. Magnetic fields augment this heating only slightly, but capture hot electrons near the cone surface and force the hot electron stream into filaments.

Mason, R.J. [Applied Physics Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

2006-01-27

228

The Influence of Pulsed Magnet Heating on Maximal Value of Generated Magnetic Field  

NASA Astrophysics Data System (ADS)

The influence of pulsed magnet heating on the maximal value of the generated magnetic field is described. The operation of pulsed generator consisting of a capacitor bank, thyristor switch and wire wound pulsed inductor was analysed. The maximum value of the generated magnetic field and pulse duration of pulsed magnet was limited by Joule heating and mechanical stresses. Using Matlab® Simulink® software, a flexible model for simulation of thermodynamic processes in pulsed magnet was developed. The calculated results of the maximal value and distribution of magnetic field were verified experimentally and acceptable compliance was achieved using calibrated array of four pick up inductive coils for measurements of axial magnetic field and a current shunt for pulsed current measurements.

Bartkevi?ius, S.; Novickij, J.

2008-01-01

229

Evidence for ultra-fast heating in intense-laser irradiated reduced-mass targets  

SciTech Connect

We report on an experiment irradiating individual argon droplets of 20 {mu}m diameter with laser pulses of several Joule energy at intensities of 10{sup 19} W/cm{sup 2}. K-shell emission spectroscopy was employed to determine the hot electron energy fraction and the time-integrated charge-state distribution. Spectral fitting indicates that bulk temperatures up to 160 eV are reached. Modelling of the hot-electron relaxation and generation of K-shell emission with collisional hot-electron stopping only is incompatible with the experimental results, and the data suggest an additional ultra-fast (sub-ps) heating contribution. For example, including resistive heating in the modelling yields a much better agreement with the observed final bulk temperature and qualitatively reproduces the observed charge state distribution.

Neumayer, P.; Gumberidze, A.; Hochhaus, D. C. [ExtreMe Matter Institute EMMI and Research Division, GSI Helmholtzzentrum fuer Schwerionenforschung, 64291 Darmstadt (Germany); Frankfurt Institute for Advanced Studies FIAS, 60438 Frankfurt am Main (Germany); Aurand, B.; Stoehlker, T. [Helmholtzzentrum fuer Schwerionenforschung GSI, 64291 Darmstadt (Germany); Helmholtz Institute Jena, 07743 Jena (Germany); Costa Fraga, R. A.; Kalinin, A. [Institut fuer Kernphysik, J. W. Goethe University Frankfurt, 60438 Frankfurt am Main (Germany); Ecker, B. [Johannes Gutenberg University Mainz, 55099 Mainz (Germany); Helmholtz Institute Jena, 07743 Jena (Germany); Grisenti, R. E. [Institut fuer Kernphysik, J. W. Goethe University Frankfurt, 60438 Frankfurt am Main (Germany); Helmholtzzentrum fuer Schwerionenforschung GSI, 64291 Darmstadt (Germany); Kaluza, M. C. [Helmholtz Institute Jena, 07743 Jena (Germany); IOQ Institute of Optics and Quantum Electronics, University of Jena (Germany); Kuehl, T. [Johannes Gutenberg University Mainz, 55099 Mainz (Germany); Helmholtzzentrum fuer Schwerionenforschung GSI, 64291 Darmstadt (Germany); Helmholtz Institute Jena, 07743 Jena (Germany); Polz, J. [IOQ Institute of Optics and Quantum Electronics, University of Jena (Germany); Reuschl, R. [ExtreMe Matter Institute EMMI and Research Division, GSI Helmholtzzentrum fuer Schwerionenforschung, 64291 Darmstadt (Germany); Winters, D.; Winters, N.; Yin, Z. [Helmholtzzentrum fuer Schwerionenforschung GSI, 64291 Darmstadt (Germany)

2012-12-15

230

Localized Heating on Silicon Field Effect Transistors: Device Fabrication and Temperature Measurements in Fluid  

PubMed Central

We demonstrate electrically addressable localized heating in fluid at the dielectric surface of silicon-on-insulator field-effect transistors via radio-frequency Joule heating of mobile ions in the Debye layer. Measurement of fluid temperatures in close vicinity to surfaces poses a challenge due to the localized nature of the temperature profile. To address this, we developed a localized thermometry technique based on the fluorescence decay rate of covalently attached fluorophores to extract the temperature within 2 nm of any oxide surface. We demonstrate precise spatial control of voltage dependent temperature profiles on the transistor surfaces. Our results introduce a new dimension to present sensing systems by enabling dual purpose silicon transistor-heaters that serve both as field effect sensors as well as temperature controllers that could perform localized bio-chemical reactions in Lab on Chip applications.

Elibol, Oguz H.; Reddy, Bobby; Nair, Pradeep R.; Dorvel, Brian; Butler, Felice; Ahsan, Zahab; Bergstrom, Donald E.; Alam, Muhammad A.; Bashir, Rashid

2010-01-01

231

Effects of thermophoresis particle deposition and of the thermal conductivity in a porous plate with dissipative heat and mass transfer  

NASA Astrophysics Data System (ADS)

Network simulation method (NSM) is used to solve the laminar heat and mass transfer of an electrically-conducting, heat generating/absorbing fluid past a perforated horizontal surface in the presence of viscous and Joule heating problem. The governing partial differential equations are non-dimensionalized and transformed into a system of nonlinear ordinary differential similarity equations, in a single independent variable, ?. The resulting coupled, nonlinear equations are solved under appropriate transformed boundary conditions. Computations are performed for a wide range of the governing flow parameters, viz Prandtl number, thermophoretic coefficient (a function of Knudsen number), thermal conductivity parameter, wall transpiration parameter and Schmidt number. The numerical details are discussed with relevant applications. The present problem finds applications in optical fiber fabrication, aerosol filter precipitators, particle deposition on hydronautical blades, semiconductor wafer design, thermo-electronics and problems including nuclear reactor safety.

Zueco, Joaquín; Anwar Bég, O.; López-Ochoa, L. M.

2011-06-01

232

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

NASA Astrophysics Data System (ADS)

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 Péclet, 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 Péclet 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 IT of the tumor volume in which the local temperature is above a threshold temperature and the ratio IN 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 ITand IN but the nature of the temperature distribution remains unchanged.

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

2011-03-01

233

Heat pipe array heat exchanger  

Microsoft Academic Search

A heat exchanger is described for transferring heat between a first fluid and a second fluid in an absorption refrigeration system comprising: a first shell having an inlet for receiving the first fluid at a first elevated temperature and an outlet for discharging the first fluid at a first reduced temperature with the shell defining a free flow path for

Reimann

1987-01-01

234

Heat-of-Reaction Chemical Heat Pumps.  

National Technical Information Service (NTIS)

Chemical heat pumps are mechanically driven heat pumps with working fluids that undergo chemical changes or are heat-driven heat pumps in which either the driver (heat engine) or heat pump utilizes a reactive working fluid. As such, chemical heat pumps ca...

C. Bliem L. Kirol

1988-01-01

235

Corrosive resistant heat exchanger  

DOEpatents

A corrosive and errosive resistant heat exchanger which recovers heat from a contaminated heat stream. The heat exchanger utilizes a boundary layer of innocuous gas, which is continuously replenished, to protect the heat exchanger surface from the hot contaminated gas. The innocuous gas is conveyed through ducts or perforations in the heat exchanger wall. Heat from the heat stream is transferred by radiation to the heat exchanger wall. Heat is removed from the outer heat exchanger wall by a heat recovery medium.

Richlen, Scott L. (Annandale, VA)

1989-01-01

236

Heat pipe heat exchanger for heat recovery in air conditioning  

Microsoft Academic Search

The heat pipe heat exchangers are used in heat recovery applications to cool the incoming fresh air in air conditioning applications. Two streams of fresh and return air have been connected with heat pipe heat exchanger to investigate the thermal performance and effectiveness of heat recovery system. Ratios of mass flow rate between return and fresh air of 1, 1.5

Mostafa A. Abd El-Baky; Mousa M. Mohamed

2007-01-01

237

Determination of the surface heat-transfer coefficient in CE.  

PubMed

A knowledge of the heat-transfer coefficient, h(s), for the external surface of the capillary or the overall heat coefficient, h(OA), is of great value in predicting the mean increase in temperature of the electrolyte, DeltaT(Mean), during electrokinetic separations. For CE, traditional indirect methods of determining h(s) were time-consuming and tended to overestimate cooling efficiency; a novel method is introduced, which is based on curve-fitting of plots of conductance versus voltage to calculate several important parameters including DeltaT(Mean), h(s), the conductance free of Joule heating effects (G(0)) and the voltage that causes autothermal runaway, V(lim). The new method is superior to previously published methods in that it can be performed more quickly and that it corrects for systematic errors in the measurement of electric current for voltages <5 kV. These errors tended to exaggerate the cooling efficiency of commercial instruments so that the calculated increases in electrolyte temperature were smaller than their actual values. Axially averaged values for h(s) were determined for three different commercial CE instruments ranging from 164 W m(-2) K(-1) for a passively cooled instrument in a drafty environment to 460 W m(-2) K(-1) for a liquid-cooled instrument. PMID:19199294

Hruska, Vlastimil; Evenhuis, Christopher J; Guijt, Rosanne M; Macka, Miroslav; Gas, Bohuslav; Marriott, Philip J; Haddad, Paul R

2009-03-01

238

Estimated energy balance in the jovian upper atmosphere during an auroral heating event  

NASA Astrophysics Data System (ADS)

We present an analysis of a series of observations of the auroral/polar regions of Jupiter, carried out between September 8 and 11, 1998, making use of the high-resolution spectrometer, CSHELL, on the NASA InfraRed Telescope Facility (IRTF), Mauna Kea, Hawaii; these observations spanned an “auroral heating event.” This analysis combines the measured line intensities and ion velocities with a one-dimensional model vertical profile of the jovian thermosphere/ionosphere. We compute the model line intensities both assuming local thermodynamic equilibrium (LTE) and, relaxing this condition (non-LTE), through detailed balance calculations, in order to compare with the observations. Taking the model parameters derived, we calculate the changes in heating rate required to account for the modelled temperature profiles that are consistent with the measured line intensities. We compute the electron precipitation rates required to give the modelled ion densities that are consistent with the measured line intensities, and derive the corresponding Pedersen conductivities. We compute the changes in heating due to Joule heating and ion drag derived from the measured ion velocities, and modelled conductivities, making use of ion-neutral coupling coefficients derived from a 3-D global circulation model. Finally, we compute the cooling due to the downward conduction of heat and the radiation-to-space from the H3+ molecular ion and hydrocarbons. Comparison of the various heating and cooling terms enables us to investigate the balance of energy inputs into the auroral/polar atmosphere. Increases in Joule heating and ion drag are sufficient to explain the observed heating of the atmosphere; increased particle precipitation makes only a minor heating contribution. But local cooling effects—predominantly radiation-to-space—are shown to be too inefficient to allow the atmosphere to relax back to pre-event thermal conditions. Thus we conclude that this event provides observational, i.e. empirical, evidence that heat must be transported away from the auroral/polar regions by thermally or mechanically driven winds.

Melin, Henrik; Miller, Steve; Stallard, Tom; Smith, Chris; Grodent, Denis

2006-03-01

239

Heat treatment  

Microsoft Academic Search

Most ferrous materials are not subjected to a separate heat treatment. Their microstructure results directly from solidification\\u000a and\\/or controlled hot working and cooling. Semi-finished steel products (strip, section, pipe, wire) undergo a combination\\u000a of hot working and heat treatment during thermomechanical processing, which is also used e.g. for drop-forged parts. The desired\\u000a microstructure of cast iron is often obtained by

Hans Berns

240

Electromagnetic pulse\\/transient threat testing of protection devices for amateur\\/military affiliate radio system equipment. Volume 3. Test data, electromagnetic pulse testing of protection devices. Section 1. High energy pulse-device failure test. 50 ohms impedance 25,000 volts-4000 amps, 100 joules  

Microsoft Academic Search

The results of two test programs: one to evaluate existing transient suppression devices and components, and one to evaluate the response of amateur radio equipment to an electromagnetic pulse (EMP) transient environment are presented. Raw test data in the form of oscilloscope photographs for high energy pulse-device failure tests at 50 ohms impedance, 25000 volts, 400 amps, and 100 joules

D. Bodson; J. Frizzell; T. Higdon; W. Rabke

1985-01-01

241

Heat exchanger  

DOEpatents

A heat exchanger of the straight tube type in which different rates of thermal expansion between the straight tubes and the supply pipes furnishing fluid to those tubes do not result in tube failures. The supply pipes each contain a section which is of helical configuration.

Wolowodiuk, Walter (New Providence, NJ)

1976-01-06

242

Material End Plugging of a Laser Heated Solenoid.  

NASA Astrophysics Data System (ADS)

Polycarbonate end plugs were inserted into the ends of a fast rising, crowbarred solenoid. A 350 joule, 1.5 (mu)sec CO(,2) laser pulse focused through a small hole in the end plug heated the preionized plasma to approximately 40 eV during the initial stages of compression. Experimental parameters are: n(,e) = 3 x 10('17)cm('-3), T(,e) = T(,i) = 40 eV, B = 9 tesla in 2.8 (mu)sec with an L/R decay time of 50 (mu)sec, l = 20 cm, tube id = 2 cm. Diagnostics include 6 axially arrayed diamagnetic loops, double pulsed laser interferometry, streak photography, streak spectroscopy, and limited laser scattering measurements. Although the classical axial electron heat conduction time is over 25 times greater than the free-streaming time of 2 (mu)sec for these conditions, the plugs only extended the confinement time by a factor of three. Axial profiles of the energy line density indicate that the presence of material end plugs changed the dominate energy loss mechanism from axial particle flow to radial heat conduction and impurity radiation. Computer simulations indicate that the plasma lifetime is consistent with classical radial heat conduction to a cold plasma boundary. Wall ablation, due to the laser and the plasma striking the wall, has been identified as a mechanism that introduces impurities into the region surrounding the plasma. This plasma provides a heat conduction path to the wall and acts as an energy sink by radiating energy away at a high rate. Factors controlling wall ablation are the laser beam trapping efficiency of the plasma, the stability of the plasma column, and the rate of laser energy addition to the plasma with respect to the available magnetic pressure. Under various experimental conditions, all of these mechanisms have been observed in this experiment.

Carlstrom, Thomas Neil

1982-03-01

243

The effects on the flow field of retaining the Joule heating and viscous dissipation term in the energy equation for the hydromagnetic free-convective oscillatory flow past a porous limiting surface. I  

Microsoft Academic Search

The free-stream velocity, the plate temperature, and the induced magnetic field are assumed to be oscillating in time about constant mean values. The flow is subjected to a constant suction velocity through the porous surface, and a magnetic field of uniform strength is applied in a direction that is transverse to that of the flow. Analytical expressions for the flow

N. D. Nanousis; N. G. Kafousias

1984-01-01

244

Integrated Heat Pump (IHP) System Development - Air-Source IHP Control Strategy and Specifications and Ground-Source IHP Conceptual Design  

SciTech Connect

The integrated heat pump (IHP), as one appliance, can provide space cooling, heating, ventilation, and dehumidification while maintaining comfort and meeting domestic water heating needs in near-zero-energy home (NZEH) applications. In FY 2006 Oak Ridge National Laboratory (ORNL) completed development of a control strategy and system specification for an air-source IHP. The conceptual design of a ground-source IHP was also completed. Testing and analysis confirm the potential of both IHP concepts to meet NZEH energy services needs while consuming 50% less energy than a suite of equipment that meets current minimum efficiency requirements. This report is in fulfillment of an FY06 DOE Building Technologies (BT) Joule Milestone.

Murphy, Richard W [ORNL; Rice, C Keith [ORNL; Baxter, Van D [ORNL

2007-05-01

245

Ceramic heat pipe heat exchangers  

Microsoft Academic Search

High-temperature strength, resistance to corrosive atmospheres, and moderate cost combine to make ceramic materials an obvious choice for construction of high-temperature thermal energy recuperator systems. Despite these advantages, ceramic recuperators are steadily being replaced by metallic units at considerable sacrifice in maximum air or fuel preheat temperatures and hence in recovery efficiency. By constructing a recuperator from ceramic heat pipes,

W. A. Ranken

1976-01-01

246

Solar assisted heat pump heating system  

Microsoft Academic Search

A solar assisted heat pump fluid heating system capable of reliable operation at higher than normal ambient temperatures is disclosed. The system includes a collection of solar panels and primary fluid storage tanks having integral coiled heat exchangers interconnected and charged with heat transfer fluid to produce heat. Temperature sensors positioned at the panels and storage tanks transmit temperature signals

Pendergrass

1984-01-01

247

Heat pump system using waste water heat  

Microsoft Academic Search

A practical and economical heat pump system stacks the evaporator, compressor, condenser, and expander to use heat from household waste water more efficiently and effectively. A novel waste water storage tank treats the waste water to remove particulates while it supplies its warmest water to the evaporator to provide heat to the refrigerant in the heat pump unit. Heated water

Dunstan

1984-01-01

248

Geothermal district heating systems  

NASA Astrophysics Data System (ADS)

Ten district heating demonstration projects and their present status are described. The projects are Klamath County YMCA, Susanville District Heating, Klamath Falls District Heating, Reno Salem Plaza Condominium, El Centro Community Center Heating/Cooling, Haakon School and Business District Heating, St. Mary's Hospital, Diamond Ring Ranch, Pagosa Springs District Heating, and Boise District Heating.

Budney, G. S.; Childs, F.

1982-06-01

249

Geothermal district heating systems  

SciTech Connect

Ten district heating demonstration projects and their present status are described. The projects are Klamath County YMCA, Susanville District Heating, Klamath Falls District Heating, Reno Salem Plaza Condominium, El Centro Community Center Heating/Cooling, Haakon School and Business District Heating, St. Mary's Hospital, Diamond Ring Ranch, Pagosa Springs District Heating, and Boise District Heating.

Budney, G.S.; Childs, F.

1982-01-01

250

Geothermal district heating systems  

Microsoft Academic Search

Ten district heating demonstration projects and their present status are described. The projects are Klamath County YMCA, Susanville District Heating, Klamath Falls District Heating, Reno Salem Plaza Condominium, El Centro Community Center Heating\\/Cooling, Haakon School and Business District Heating, St. Mary's Hospital, Diamond Ring Ranch, Pagosa Springs District Heating, and Boise District Heating.

G. S. Budney; F. Childs

1982-01-01

251

Heat pipe system  

Microsoft Academic Search

A heat pipe diode device for transferring heat from a heat source component to a heat sink wall is described. It contains a heat pipe body member attached to the best source; the heat source having a wall forming at least a portion of the normal evaporator section of the heat pipe diode; a working fluid within the body member;

H. L. Kroebig; F. J. Riha

1974-01-01

252

On the mechanism of particle heating and acceleration in the Jovian ionosphere  

NASA Astrophysics Data System (ADS)

The acceleration mechanism of the charged particles connected with a potential difference along the Jovian magnetic field is proposed. This model is developed on the basis of the known phenomenon of the partially ionized magnetized plasma resistance increase in the presence of a nonstationary current. The region of high resistance is formed above the ionosphere plasma density maximum when the Io current tube is going through this region. For typical Jovian ionosphere conditions the resistance is increased by about seven orders. The potential difference accelerates particles up to several MeV in this region. Here, we also take into account that the efficiency of electron acceleration is limited by the Bunneman turbulence excited due to an electron-ion relative motion. The plasma is heated due to the Joule dissipation and the Bunneman turbulence by several orders of keV.

Shaposhnikov, V. E.; Zaitsev, V. V.

1993-05-01

253

Geothermal heating  

SciTech Connect

The aim of the study is to demonstrate the viability of geothermal heating projects in energy and economic terms and to provide nomograms from which an initial estimate may be made without having to use data-processing facilities. The effect of flow rate and temperature of the geothermal water on drilling and on the network, and the effect of climate on the type of housing are considered.

Aureille, M.

1982-01-01

254

High temperature heat exchangers  

SciTech Connect

This book contains the proceedings from the XVII Symposium of the International Center for Heat and Mass Transfer on High Temperature Heat Exchangers, held August 1985 in Yugoslavia. Papers were presented under the following topics: High Temperature Heat Exchangers Development; Basic Problem in High Temperature Heat Exchangers; Heat Exchangers for High Temperature Recovery; and High Temperature Heat Exchangers for Future Power Plants and Industrial Process Application. Some of the papers' titles are: Future Development of High Temperature Heat Exchangers; Regenerative and Direct Contact High Temperature Heat Exchangers; Heat Exchangers for Heat Recovery; High Temeprature Heat Transfer Augmentation; and Development of a BOF Slag Granulating and Heat Recovering System.

Mori, Y.; Sheindlin, A.E.; Afgan, N.

1986-01-01

255

Industrial Waste Heat for Greenhouse Heating.  

National Technical Information Service (NTIS)

The economical conditions of utilizing industrial waste heat for greenhouse heating has been investigated. The investment cost and yearly operational costs of greenhouses and heating systems have been calculated as a function of the temperature of waste h...

S. E. Ransmark

1983-01-01

256

Heat Rash or Prickly Heat (Miliaria Rubra)  

MedlinePLUS

newsletter | contact Share | Heat Rash or Prickly Heat (Miliaria Rubra) A parent's guide to condition and treatment information A A A This child with miliaria rubra has many red, itchy bumps in area of redness. Overview Heat rash (miliaria rubra), ...

257

Heating fireplace and heat exchanger for a heating fireplace  

Microsoft Academic Search

The floor of the furnace space (fire chamber) of the heating fireplace is constituted by a horizontal, flat part and the rear wall of the furnace space is constituted in part by a vertical, flat part of a heat exchanger serving for heating water for a hot water heater. Heat is transferred to the water on the sides of the

H. A. Burger; W. Gehrig

1984-01-01

258

Heat pipes in modern heat exchangers  

Microsoft Academic Search

Heat pipes are very flexible systems with regard to effective thermal control. They can easily be implemented as heat exchangers inside sorption and vapour-compression heat pumps, refrigerators and other types of heat transfer devices. Their heat transfer coefficient in the evaporator and condenser zones is 103–105 W\\/m2K, heat pipe thermal resistance is 0.01–0.03 K\\/W, therefore leading to smaller area and

Leonard L. Vasiliev

2005-01-01

259

Heat pipe heat exchanger design considerations  

Microsoft Academic Search

Typical heat pipe heat exchangers (HPHX) are described, along with their advantages, uses, and some problems in HPHX design, and a computer HPHX analysis program is discussed with required input data. The computer program is being developed for analysis of heat exchange performance by finned-tube HPHX and thread-puddle-artery heat pipes. Copper-water heat pipes and carbon steel-Dowtherm A heat pipes are

K. T. Feldman; D. C. Lu

1976-01-01

260

Dead heat  

SciTech Connect

This paper reports on the prospect of global warming. This paper proposes a workable solution, and a road map for getting there. The author explains how we became addicted to fossil fuels and evokes a bleak picture should this dependence continue. But the book also explores how industry can become a vehicle for solving, instead of precipitating, the global environmental crisis. The decoupling of energy from pollution can be accomplished without sacrificing prosperity by powering the economy with solar energy. Dead Heat takes us step by step to a greenhouse-friendly world fueled only by the sun.

Oppenheimer, M.; Boyle, R.H.

1990-01-01

261

Heat exchanger  

DOEpatents

A heat exchanger comparising a shell attached at its open end to one side of a tube sheet and a detachable head connected to the other side of said tube sheet. The head is divided into a first and second chamber in fluid communication with a nozzle inlet and nozzle outlet, respectively, formed in said tube sheet. A tube bundle is mounted within said shell and is provided with inlets and outlets formed in said tube sheet in communication with said first and second chambers, respectively.

Brackenbury, P.J.

1983-12-08

262

Geothermal District Heating Systems.  

National Technical Information Service (NTIS)

Ten district heating demonstration projects and their present status are described. The projects are Klamath County YMCA, Susanville District Heating, Klamath Falls District Heating, Reno Salem Plaza Condominium, El Centro Community Center Heating/Cooling...

G. S. Budney F. Childs

1982-01-01

263

Heat recovery unit  

SciTech Connect

A device is disclosed for recovery of heat from hot shell devices, particularly from motor-compressor units such as used in air conditioners, refrigeration systems and the like and which comprises a heat exchange coil in encircling, contacting heat exchange relationship to the hot shell device with circulation of a fluid through the heat exchange coil to recover normally wasted heat. Heat absorbed can be utilized to heat domestic hot water for home heating or for tap use.

Beckett, R.R.

1980-06-10

264

Solar heated building  

Microsoft Academic Search

A solar heating system for a building is disclosed. The solar heating system includes a solar collector and conduits leading from the solar collector to a plurality of heat sinks. The conduits contain an antifreeze solution for carrying the heat from the solar collector to the heat sinks. One of the heat sinks is a hot water stock tank which

Tatusmi

1981-01-01

265

Heat transfer science and technology  

Microsoft Academic Search

This book presents the papers given at a conference on heat transfer. Topics considered at the conference included two-phase flow, freezing, heat flux, natural heat convection, forced heat convection, flow visualization, boiling heat transfer, condensation heat transfer, thermal radiation, heat and mass transfer in porous media, nuclear reaction heat transfer, combustion heat transfer, high-temperature heat transfer, heat exchangers, and industrial

1987-01-01

266

Heat Rash or Prickly Heat (Miliaria Rubra)  

MedlinePLUS

... the affected areas. Self-Care Guidelines Prevention and treatment of heat rash consist of controlling heat and humidity. Acetaminophen ... heat rash include secondary infection from scratching and heat ... may need antibiotic treatment for resolution. Seek care if the rash develops ...

267

Upgrading of heat through absorption heat transformers  

Microsoft Academic Search

In this paper, we study the performance of absorption heat transformers for upgrading low-level heat. A mathematical model was developed utilizing the equation of state to calculate the properties of ammonia-water mixture. The performance of the heat transformer is defined by COP and circulation ratio. The parameters that affect the performance are level of waste heat, condenser temperature, and effectiveness

I. M Ismail

1995-01-01

268

Industrial waste heat for district heating  

Microsoft Academic Search

Presents 2 bounding evaluations of industrial waste heat availability. Surveys waste heat from 29 major industry groups at the 2-digit level in Standard Industrial Codes (SIC). Explains that waste heat availability in each industry was related to regional product sales, in order to estimate regional waste heat availability. Evaluates 4 selected industries at the 4-digit SIC level. Finds that industrial

K. L. Heitner; P. P. Brooks

1982-01-01

269

Latent Heat in Soil Heat Flux Measurements  

Technology Transfer Automated Retrieval System (TEKTRAN)

The surface energy balance includes a term for soil heat flux. Soil heat flux is difficult to measure because it includes conduction and convection heat transfer processes. Accurate representation of soil heat flux is an important consideration in many modeling and measurement applications. Yet, the...

270

Dual source heat pump  

DOEpatents

What is disclosed is a heat pump apparatus for conditioning a fluid characterized by a fluid handler and path for circulating the fluid in heat exchange relationship with a refrigerant fluid; at least two refrigerant heat exchangers, one for effecting heat exchange with the fluid and a second for effecting heat exchange between refrigerant and a heat exchange fluid and the ambient air; a compressor for efficiently compressing the refrigerant; at least one throttling valve for throttling liquid refrigerant; a refrigerant circuit; refrigerant; a source of heat exchange fluid; heat exchange fluid circulating device and heat exchange fluid circuit for circulating the heat exchange fluid in heat exchange relationship with the refrigerant; and valves or switches for selecting the heat exchangers and direction of flow of the refrigerant therethrough for selecting a particular mode of operation. The heat exchange fluid provides energy for defrosting the second heat exchanger when operating in the air source mode and also provides a alternate source of heat.

Ecker, Amir L. (Dallas, TX); Pietsch, Joseph A. (Dallas, TX)

1982-01-01

271

Segmented heat exchanger  

SciTech Connect

A segmented heat exchanger system for transferring heat energy from an exhaust fluid to a working fluid. The heat exchanger system may include a first heat exchanger for receiving incoming working fluid and the exhaust fluid. The working fluid and exhaust fluid may travel through at least a portion of the first heat exchanger in a parallel flow configuration. In addition, the heat exchanger system may include a second heat exchanger for receiving working fluid from the first heat exchanger and exhaust fluid from a third heat exchanger. The working fluid and exhaust fluid may travel through at least a portion of the second heat exchanger in a counter flow configuration. Furthermore, the heat exchanger system may include a third heat exchanger for receiving working fluid from the second heat exchanger and exhaust fluid from the first heat exchanger. The working fluid and exhaust fluid may travel through at least a portion of the third heat exchanger in a parallel flow configuration.

Baldwin, Darryl Dean (Lafayette, IN); Willi, Martin Leo (Dunlap, IL); Fiveland, Scott Byron (Metamara, IL); Timmons, Kristine Ann (Chillicothe, IL)

2010-12-14

272

Comparison and analysis of the efficiency of heat exchange of copper rod and copper wires current lead  

NASA Astrophysics Data System (ADS)

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.

Fang, J.; Yu, T.; Li, Z. M.; Wei, B.; Qiu, M.; Zhang, H. J.

2013-11-01

273

Probing fast heating in magnetic tunnel junction structures with exchange bias  

NASA Astrophysics Data System (ADS)

Heat diffusion in a magnetic tunnel junction (MTJ) having a ferromagnetic/antiferromagnetic free layer is investigated. The MTJ is heated by an electric current pulse of power PHP, flowing through the junction in current perpendicular to the plane (CPP) geometry, via Joule heat dissipation in the tunnel barrier. According to a proposed one-dimensional (1D) model of heat diffusion, when an electric voltage is applied to the MTJ, the free layer experiences a transient temperature regime, characterized by an exponential increase of its temperature TAF with a time constant ?TR, followed by a steady temperature regime characterized by TAF=TRT+?PHP, where TRT is the room temperature and ? is a constant. Magnetic transport measurements of exchange bias HEX acting on the free layer allow the determination of ? and ?TR. The experimental values of ? and ?TR are in agreement with those calculated using the 1D model and an estimation of the MTJ thermodynamic parameters based on the Dulong Petit and Widemann Franz laws.

Papusoi, C.; Sousa, R.; Herault, J.; Prejbeanu, I. L.; Dieny, B.

2008-10-01

274

Thermal Runaway.  

National Technical Information Service (NTIS)

During battery discharge, the heat generated is the sum of the Joule (resistive) and enthalpic (chemical) heating effects. Conversely, during battery charging, the heat generated is the Joule minus the enthalpic heating. If the conditions are carefully se...

H. A. Catherino

2005-01-01

275

A Study of Alfvén Wave Propagation and Heating the Chromosphere  

NASA Astrophysics Data System (ADS)

Alfvén wave propagation, reflection, and heating of the chromosphere are studied for a one-dimensional solar atmosphere by self-consistently solving plasma, neutral fluid, and Maxwell's equations with incorporation of the Hall effect and strong electron-neutral, electron-ion, and ion-neutral collisions. We have developed a numerical model based on an implicit backward difference formula of second-order accuracy both in time and space to solve stiff governing equations resulting from strong inter-species collisions. A non-reflecting boundary condition is applied to the top boundary so that the wave reflection within the simulation domain can be unambiguously determined. It is shown that due to the density gradient the Alfvén waves are partially reflected throughout the chromosphere and more strongly at higher altitudes with the strongest reflection at the transition region. The waves are damped in the lower chromosphere dominantly through Joule dissipation, producing heating strong enough to balance the radiative loss for the quiet chromosphere without invoking anomalous processes or turbulences. The heating rates are larger for weaker background magnetic fields below ~500 km with higher-frequency waves subject to heavier damping. There is an upper cutoff frequency, depending on the background magnetic field, above which the waves are completely damped. At the frequencies below which the waves are not strongly damped, the interaction of reflected waves with the upward propagating waves produces power at their double frequencies, which leads to more damping. The wave energy flux transmitted to the corona is one order of magnitude smaller than that of the driving source.

Tu, Jiannan; Song, Paul

2013-11-01

276

Solar heating  

SciTech Connect

A solar heater has an outlet conduit above an inlet conduit intercoupling a solar heating chamber with the inside of a building through a window opening. In one form the solar collecting chamber is outside the building below the window and the outlet conduit and inlet conduit are contiguous and pass through the window opening between the windowsill and the lower sash. In another form of the invention the solar collecting chambers are located beside each side of the window and joined at the top by the outlet conduit that passes through an opening between the upper window sash and the top of the window frame and at the bottom by an inlet conduit that passes through an opening between the lower sash and the windowsill. The outlet conduit carries photoelectric cells that provide electrical energy for driving a squirrel-cage fan in the outlet conduit through a mercury switch seated on a damper actuated by a bimetallic coil that closes the damper when the temperature in the outlet conduit goes below a predetermined temperature.

Resnick, M.; Startevant, R.C.

1985-01-22

277

Multiple source heat pump  

DOEpatents

A heat pump apparatus for conditioning a fluid characterized by a fluid handler and path for circulating a fluid in heat exchange relationship with a refrigerant fluid, at least three refrigerant heat exchangers, one for effecting heat exchange with the fluid, a second for effecting heat exchange with a heat exchange fluid, and a third for effecting heat exchange with ambient air; a compressor for compressing the refrigerant; at least one throttling valve connected at the inlet side of a heat exchanger in which liquid refrigerant is vaporized; a refrigerant circuit; refrigerant; a source of heat exchange fluid; heat exchange fluid circuit and pump for circulating the heat exchange fluid in heat exchange relationship with the refrigerant; and valves or switches for selecting the heat exchangers and directional flow of refrigerant therethrough for selecting a particular mode of operation. Also disclosed are a variety of embodiments, modes of operation, and schematics therefor.

Ecker, Amir L. (Duncanville, TX)

1983-01-01

278

Controlled heat pipes  

NASA Astrophysics Data System (ADS)

A thermodynamic analysis of the operation of controlled heat pipes is presented. Topics covered include a classification of controlled heat pipes; attention is given to heat pipes in the dry saturated vapor regime, with a superheated vapor, with a supercooled liquid phase, with a superheated vapor and a supercooled liquid phase, and with moist vapor. Also covered are heat pipes with passive or active control, and the classification of controlled heat pipes according to the function (application) realized. Applications include heat diodes, temperature stabilizers, a heat bridge, a heat flow regulator, and a heat switch.

Vasilev, L. L.; Konev, S. V.; Tomchak, V.; Danelevich, Ia.

1983-07-01

279

Controlled heat pipes  

NASA Astrophysics Data System (ADS)

A thermodynamic analysis of the operation of controlled heat pipes is presented. Topics covered include a classification of controlled heat pipes; attention is given to heat pipes in the dry saturated vapor regime, with a superheated vapor, with a supercooled liquid phase, with a superheated vapor and a supercooled liquid phase, and with moist vapor. Also covered are heat pipes with passive or active control, and the classification of controlled heat pipes according to the function (application) realized. Applications include heat diodes, temperature stabilizers, a heat bridge, a heat flow regulator, and a heat switch.

Vasilev, L. L.; Konev, S. V.; Tomchak, V.; Danelevich, Ia.

1984-01-01

280

Heat-of-Reaction Chemical Heat Pumps: Possible Configurations.  

National Technical Information Service (NTIS)

Chemical heat pumps utilize working fluids which undergo reversible chemical changes. Mechanically driven reactive heat pump cycles or, alternatively, heat driven heat pumps in which either heat engine or heat pump working fluid is reactive, are considere...

L. D. Kirol

1986-01-01

281

Active microchannel heat exchanger  

Microsoft Academic Search

The present invention is an active microchannel heat exchanger with an active heat source and with microchannel architecture. The active microchannel heat exchanger has (a) an exothermic reaction chamber; (b) an exhaust chamber; and (c) a heat exchanger chamber in thermal contact with the exhaust chamber, wherein (d) heat from the exothermic reaction chamber is convected by an exothermic reaction

Anna Lee Y. Tonkovich; Gary L. Roberts; Charles J. Call; Robert S. Wegeng; Yong Wang

2001-01-01

282

Nitinol heat engines  

Microsoft Academic Search

Heat engines have recently been developed which utilize the remarkable properties of a nickel-titanium alloy called Nitinol to convert heat into mechanical energy. The design, principles of operation, and performance characteristics of a small prototype Nitinol heat engine are described. Emphasis is placed on the description of a simple heat engine invented by the author, in which a specially heat-treated

A. D. Johnson

1975-01-01

283

Absorption heat pump  

Microsoft Academic Search

This disclosure documents the invention of adapting an economizer and an air heater to an absorption heat pump. The heat pump will have as its prime source of power, heat generated from burning a source of fuel. The air used in the burner will be heated above outside ambient temperatures by a source of waste heat. The warmed air will

Worsham

1981-01-01

284

Heat storing fireplace  

Microsoft Academic Search

The design of heat storing fireplace including a fire-box surrounded by a heat storage medium which is either an enclosure containing a material having a high specific heat such as sand or gravel or a large number of heat conducting bags containing a high specific heat material is given. Exhaust gases are conveyed from the fire-box to an exhaust outlet

Der M. R

1981-01-01

285

Industrial heat exchangers  

Microsoft Academic Search

This book presents the papers given at a symposium on the use of heat exchangers in the industrial plants. Topics considered include the US DOE and GRI research programs, advanced fixed boundary heat exchanger technology, commercial heat exchanger applications, thermo-hydraulic performance of heat-transfer equipment, field tests, the corrosion of heat exchanger materials, economics, cost benefit analysis, payback, and advanced assembly

A. J. Hayes; W. W. Liang; S. L. Richlen; E. S. Tabb

1985-01-01

286

Plate Fin Heat Exchanger Model with Axial Conduction and Variable Properties  

SciTech Connect

Future superconducting radio frequency (SRF) cavities, as part of Project X at Fermilab, will be cooled to superfluid helium temperatures by a cryogenic distribution system supplying cold supercritical helium. To reduce vapor fraction during the final Joule-Thomson (J-T) expansion into the superfluid helium cooling bath, counter-flow, plate-fin heat exchangers will be utilized. Due to their compact size and ease of fabrication, plate-fin heat exchangers are an effective option. However, the design of compact and high-effectiveness cryogenic heat exchangers operating at liquid helium temperatures requires consideration of axial heat conduction along the direction of flow, in addition to variable fluid properties. Here we present a numerical model that includes the effects of axial conduction and variable properties for a plate fin heat exchanger. The model is used to guide design decisions on heat exchanger material choice and geometry. In addition, the J-T expansion process is modeled with the heat exchanger to analyze the effect of heat load and cryogenic supply parameters. A numerical model that includes the effects of axial conduction and variable properties for a plate fin heat exchanger was developed and the effect of various design parameters on overall heat exchanger size was investigated. It was found that highly conductive metals should be avoided in the design of compact JT heat exchangers. For the geometry considered, the optimal conductivity is around 3.5 W/m-K and can range from 0.3-10 W/m-K without a large loss in performance. The model was implemented with an isenthalpic expansion process. Increasing the cold side inlet temperature from 2K to 2.2 K decreased the liquid fraction from 0.856 to 0.839 which corresponds to a 0.12 g/s increase in supercritical helium supply needed to maintain liquid level in the cooling bath. Lastly, it was found that the effectiveness increased when the heat load was below the design value. Therefore, the heat exchanger should be sized on the high end of the required heat load.

Hansen, B.J.; White, M.J.; Klebaner, A.; /Fermilab

2011-06-10

287

Heat exchanger sourcebook  

SciTech Connect

This book covers techniques brought about by economical computing capabilities. It is divided into the following sections: general design information; shell-and-tube heat exchangers; reboilers and condensers; plate heat exchangers; heat exchange enhancement; techniques; and fouling.

Palen, J.W.

1986-01-01

288

Prickly Heat (Miliaria)  

MedlinePLUS

Sections Skin Disorders Chapters Sweating Disorders Prickly Heat Prickly heat (miliaria) is an itchy rash caused by trapped sweat. Prickly heat develops when the narrow ducts carrying sweat to the skin ...

289

Absorption heat pump system  

DOEpatents

The efficiency of an absorption heat pump system is improved by conducting liquid from a second stage evaporator thereof to an auxiliary heat exchanger positioned downstream of a primary heat exchanger in the desorber of the system.

Grossman, G.

1982-06-16

290

Absorption heat pump system  

DOEpatents

The efficiency of an absorption heat pump system is improved by conducting liquid from a second stage evaporator thereof to an auxiliary heat exchanger positioned downstream of a primary heat exchanger in the desorber of the system.

Grossman, Gershon (Oak Ridge, TN)

1984-01-01

291

Heat Rash or Prickly Heat (Miliaria Rubra)  

MedlinePLUS

... groin and armpits. Self-Care Guidelines Prevention and treatment of heat rash consist of controlling heat and humidity. Acetaminophen ... and apply cool compresses. Do not give fluids. ... skin infection related to the heat rash or otherwise, oral or topical antibiotics may ...

292

Stellar Magnetic Fields as a Heating Source for Extrasolar Giant Planets  

NASA Astrophysics Data System (ADS)

It has been observed that hot Jupiters located within 0.08 AU of their host stars commonly display radii in excess of those expected based on models. A number of theoretical explanations for this phenomenon have been suggested, but the ability of any one mechanism to account for the full range of observations remains to be rigorously proven. I identify an additional heating mechanism, arising from the interaction of the interplanetary magnetic field and the planetary magnetosphere, and show that this is capable of providing enough energy to explain the observed planetary radii. Such a model predicts that the degree of heating should be dependent on the stellar magnetic field, for which stellar activity serves as a proxy. Accordingly, I examine populations of hot Jupiters from the Kepler database and confirm that stellar activity (determined using Kepler CDPP levels) is correlated with the presence of planetary radii inflated beyond the basal level of R = 0.87 RJ identified by previous researchers. I propose that the primary mechanism for transferring energy from the magnetosphere to the planetary interior is Joule heating arising from global electric circuits analogous to those seen in solar system objects.

Buzasi, D.

2013-03-01

293

Heat transfer enhancement in heat exchangers  

SciTech Connect

In the power generation industry, high performance heat exchangers are needed to promote substantial improvements in effective utilization of waste heat in low temperature heat recovery applications. High performance heat exchangers are also seriously needed in low temperature power and refrigeration cycles that operate on renewable base energy sources such as ocean thermal energy conversion, geothermal and solar energy systems. Presently, the excessively large heat transfer surface area requirements prohibit cost-effective use of these systems. This paper reports on the new and promising electrohydrodynamic (EHD) technique which has demonstrated impressive potential for enhancing heat transfer in heat exchangers involving single-phase or phase-change processes. This article provides a brief description of EHD operational principles, research advancements in EHD during the past decade, and potential future EHD applications of specific interest to the HVAC and R industry.

Ohadi, M.M.

1991-12-01

294

Optimal utilization of waste heat from heat engines by use of a heat pump  

Microsoft Academic Search

The use of a heat pump to utilise the waste heat from a heat engine has been studied. The optimal heat delivered and the optimal heat pump to heat engine work ratio has been determined for externally and totally irreversible heat engines and heat pumps. The results show that the highest temperature at which the heat is delivered from the

M. M. Salah El-Din

1999-01-01

295

Two-Year Community College Chemistry: Joules.  

ERIC Educational Resources Information Center

|Describes a forensic science course designed to give criminal justice students the knowledge and technology of science to solve a crime. The article includes a listing of topic areas, suggestions for the presentation of the content material, and an outline of the content and design. (MA)|

Bardole, Ellen, Ed.; Bardole, Jay, Ed.

1978-01-01

296

The Sun's Joules. [CD-ROM].  

ERIC Educational Resources Information Center

|An educational tool concerning renewable energy and the environment, this CD-ROM provides nearly 1,000 screens of text, graphics, videos, and interactive exercises. It also provides a detailed index, charts of U.S. energy consumption by state, an energy glossary, and a list of related Web sites. This CD-ROM, additionally, offers "The School…

Center for Renewable Energy and Sustainable Tech., Washington, DC.

297

Performance of a variable conductance heat pipe heat exchanger  

Microsoft Academic Search

The performance of an air to air heat exchanger in which heat is transferred to a finned evaporator and from a finned condenser via a heat pipe was evaluated. The variable conductance heat pipe is to the condenser fins a heat source and to the evaporator fins a heat sink. The principal advantage of the variable conductance heat pipe heat

P. D. Chancelor

1983-01-01

298

REACH. Heating Units.  

ERIC Educational Resources Information Center

As a part of the REACH (Refrigeration, Electro-Mechanical, Air-Conditioning, Heating) electromechanical cluster, this student manual contains individualized units in the area of heating. The instructional units focus on electric heating systems, gas heating systems, and oil burning systems. Each unit follows a typical format that includes a unit…

Stanfield, Carter; And Others

299

Rotary magnetic heat pump  

DOEpatents

A rotary magnetic heat pump constructed without flow seals or segmented rotor accomplishes recuperation and regeneration by using split flow paths. Heat exchange fluid pumped through heat exchangers and returned to the heat pump splits into two flow components: one flowing counter to the rotor rotation and one flowing with the rotation.

Kirol, Lance D. (Shelly, ID)

1988-01-01

300

Heat absorbing window  

Microsoft Academic Search

A heat absorbing window is disclosed which can receive solar energy and transmit the illumination part of the solar energy, while utilizing the heat part of such energy to provide a source of heat for useful purposes. The window includes a frame with three window panes. The outermost pane faces the exterior and is of non-heat absorbing material. The middle

Berman

1978-01-01

301

Transient critical heat flux  

Microsoft Academic Search

The term Critical Heat Flux (CHF) is used in boiling heat transfer to describe the local value of the heat flux at which a characteristic reduction in the heat transfer coefficient first occurs. A major limitation on the thermal design of a light-water reactor (LWR) is the necessity to maintain an adequate safety margin between the CHF and the local

Pasamehmetoglu

1986-01-01

302

Woven heat exchanger  

DOEpatents

In a woven ceramic heat exchanger using the basic tube-in-shell design, each heat exchanger consisting of tube sheets and tube, is woven separately. Individual heat exchangers are assembled in cross-flow configuration. Each heat exchanger is woven from high temperature ceramic fiber, the warp is continuous from tube to tube sheet providing a smooth transition and unitized construction.

Piscitella, Roger R. (Idaho Falls, ID)

1987-01-01

303

Home heating system  

Microsoft Academic Search

A home heating system is disclosed that has a furnace with a combustion chamber for burning fuel and creating heat, and a chimney with a draft therein. An improvement is described that has an exhaust flue connected between the combustion chamber and the chimney for venting heated exhaust products from the furnace, a heat reclaimer connected into the exhaust flue

Bellaff

1980-01-01

304

Nature's Heat Exchangers.  

ERIC Educational Resources Information Center

Discusses the heat-transfer systems of different animals. Systems include heat conduction into the ground, heat transferred by convection, heat exchange in lizards, fish and polar animals, the carotid rete system, electromagnetic radiation from animals and people, and plant and animal fiber optics. (MDH)

Barnes, George

1991-01-01

305

Nature's Heat Exchangers.  

ERIC Educational Resources Information Center

|Discusses the heat-transfer systems of different animals. Systems include heat conduction into the ground, heat transferred by convection, heat exchange in lizards, fish and polar animals, the carotid rete system, electromagnetic radiation from animals and people, and plant and animal fiber optics. (MDH)|

Barnes, George

1991-01-01

306

Heat-transfer material  

NASA Astrophysics Data System (ADS)

The present invention concerns heat transfer material used for heat transfer recording, especially heat transfer material providing good recorded images on a substrate of poor surface smoothness, and the images can be corrected by a liftoff correction tape that produces adhesive properties when heated.

Katayama, Masahito; Sato, Hiroshi; Takizawa, Yoshihisa; Asaoka, Masanobu; Fukuda, Tsugihiro

1991-07-01

307

Rotary magnetic heat pump  

DOEpatents

A rotary magnetic heat pump constructed without flow seals or segmented rotor accomplishes recuperation and regeneration by using split flow paths. Heat exchange fluid pumped through heat exchangers and returned to the heat pump splits into two flow components: one flowing counter to the rotor rotation and one flowing with the rotation. 5 figs.

Kirol, L.D.

1987-02-11

308

Loop heat pipes  

Microsoft Academic Search

Loop heat pipes (LHPs) are two-phase heat-transfer devices with capillary pumping of a working fluid. They possess all the main advantages of conventional heat pipes, but owing to the original design and special properties of the capillary structure are capable of transferring heat efficiency for distances up to several meters at any orientation in the gravity field, or to several

Yu. F. Maydanik

2005-01-01

309

Multiple heat pipe heat exchanger and method for making  

Microsoft Academic Search

A heat pipe heat exchanger has a plurality of heat pipes which are interconnected so as to permit fluid communication between the pipes at least during charging so that the heat pipes may be simultaneously filled with heat transfer fluid.

Maxson

1979-01-01

310

Heat Intolerance, Heat Exhaustion Monitored: A Case Report.  

National Technical Information Service (NTIS)

A 32 year-old male (S.H.) monitored during an 8-day heat acclimation (HA) investigation, unexpectedly exhibited heat intolerance and heat exhaustion. Thirteen other males completed HA without indications of either heat intolerance or heat exhaustion. Beca...

L. E. Armstrong R. W. Hubbard P. C. Szlyk I. V. Sils W. J. Kraemer

1987-01-01

311

Heat Treating Apparatus  

DOEpatents

Apparatus for heat treating a heat treatable material including a housing having an upper opening for receiving a heat treatable material at a first temperature, a lower opening, and a chamber therebetween for heating the heat treatable material to a second temperature higher than the first temperature as the heat treatable material moves through the chamber from the upper to the lower opening. A gas supply assembly is operatively engaged to the housing at the lower opening, and includes a source of gas, a gas delivery assembly for delivering the gas through a plurality of pathways into the housing in countercurrent flow to movement of the heat treatable material, whereby the heat treatable material passes through the lower opening at the second temperature, and a control assembly for controlling conditions within the chamber to enable the heat treatable material to reach the second temperature and pass through the lower opening at the second temperature as a heated material.

De Saro, Robert (Annandale, NJ); Bateman, Willis (Sutton Colfield, GB)

2002-09-10

312

Thermoelectric heat exchange element  

DOEpatents

A thermoelectric heat exchange module includes a first substrate including a heat receptive side and a heat donative side and a series of undulatory pleats. The module may also include a thermoelectric material layer having a ZT value of 1.0 or more disposed on at least one of the heat receptive side and the heat donative side, and an electrical contact may be in electrical communication with the thermoelectric material layer.

Callas, James J. (Peoria, IL); Taher, Mahmoud A. (Peoria, IL)

2007-08-14

313

[Heat waves: health impacts].  

PubMed

During the summer of 2003, record high temperatures were reported across Europe, causing thousands of casualties. Heat waves are sporadic recurrent events, characterised by intense and prolonged heat, associated with excess mortality and morbidity. The most frequent cause of death directly attributable to heat is heat stroke but heat waves are known to cause increases in all-cause mortality, specially circulatory and respiratory mortality. Epidemiological studies demonstrate excess casualties cluster in specific risk groups. The elderly, those with chronic medical conditions and the socially isolated are particularly vulnerable. Air conditioning is the strongest protective factor against heat-related disorders. Heat waves cause disease indirectly, by aggravating chronic disorders, and directly, by causing heat-related illnesses (HRI). Classic HRI include skin eruptions, heat cramps, heat syncope, heat exhaustion and heat stroke. Heat stroke is a medical emergency characterised by hyperthermia and central nervous system dysfunction. Treatment includes immediate cooling and support of organ-system function. Despite aggressive treatment, heat stroke is often fatal and permanent neurological damage is frequent in those who survive. Heat related illness and death are preventable through behavioural adaptations, such as use of air conditioning and increased fluid intake. Other adaptation measures include heat emergency warning systems and intervention plans and environmental heat stress reduction. Heat related mortality is expected to rise as a consequence of the increasing proportion of elderly persons, the growing urban population, and the anticipated increase in number and intensity of heat waves associated with global warming. Improvements in surveillance and response capability may limit the adverse health conditions of future heat waves. It is crucial that health professionals are prepared to recognise, prevent and treat HRI and learn to cooperate with local health agencies. PMID:16684487

Marto, Natália

2006-03-06

314

SP100 Heat Source Heat Exchanger Design  

Microsoft Academic Search

A conceptual design for a liquid metal to gas counterflow heat exchanger has been developed for use in the SP-100 Closed Brayton Cycle (CBC) Space Reactor Power System (SRPS). The Heat Source Heat Exchanger (HSHX) is required to transfer 80 kWt from the 1350 K lithium reactor coolant to the He\\/Xe working fluid of the Brayton Rotating Unit (BRU). Trade

T. Ted Fallas; Andrew W. Desepte; Robert J. Hill; Georgi B. Manjarrez; Enrique R. Solorzano; Samir A. Salamah; Raphael Yahalom

1994-01-01

315

Metallic micro heat pipe heat spreader fabrication  

Microsoft Academic Search

Micro heat pipe heat spreaders (MHPHS) with three copper foil layers were designed to allow liquid and vapor flow separation to reduce viscous shear force. Two wick designs, one using 200 ?m wide etched radial grooves and the other with 100-mesh copper screens were investigated. The foils were vacuum diffusion bonded to form 31 mm×31 mm×2.7 mm heat spreader. Thermal

Shung-Wen Kang; Sheng-Hong Tsai; Ming-Han Ko

2004-01-01

316

Heat transfer from internally heated hemispherical pools  

SciTech Connect

Experiments were conducted on heat transfer from internally heated ZnSO/sub 4/-H/sub 2/O pools to the walls of hemispherical containers. This experimental technique provides data for a heat transfer system that has to date been only theoretically treated. Three different sizes of copper hemispherical containers were used: 240, 280, 320 mm in diameter. The pool container served both as a heat transfer surface and as an electrode. The opposing electrode was a copper disk, 50 mm in diameter located at the top of the pool in the center. The top surface of the pool was open to the atmosphere.

Gabor, J.D.; Ellsion, P.G.; Cassulo, J.C.

1980-01-01

317

Heat collection system  

SciTech Connect

A heat collection system is disclosed which is capable of collecting heat from an animal husbandry enclosures such as a dairy barn, and transferring the heat into a home. Animal husbandry enclosures, such as dairy barns, tend to have excess heat, even in winter, the excess heat normally being wasted. The heat is collected by a pair of evaporators located in the dairy barn, with the evaporators being oversized to limit the amount of cooling taking place in the barn. Fluid from the evaporators is compressed by compressors after which it passes through a condenser from which heat may be extracted into the home. Pressure regulating valves are provided to insure that the compressors are not overloaded and to insure that a maximum heating effect is achieved. A thermostatically controlled fan is provided to drive air across the condenser so that heat is introduced into the home.

Ramlow, B.L.; Steele, R.R.

1982-04-06

318

Alternative Heat Sources for Heat Pumps.  

National Technical Information Service (NTIS)

Solar-assisted, water source, and ground source heat pumps are described as alternatives for use in a broader range of climated than that in which air-to-air heat pumps can be used. Publications for further information on these systems are listed. (ERA ci...

1984-01-01

319

Heat transfer - Denver 1985  

SciTech Connect

This Symposium Series volume contains AIChE-sponsored session papers accepted for presentation at the 23rd National Heat Transfer Conference. The papers are grouped under the headings of: Heat Transfer for Alternate Energy Technologies; Nuclear Plant Degraded Core Cooling; Direct Flux Solar Energy Process; Numerical Methods for Multiphase Flow System and Component Analysis; General Solar Heat Transfer; Thermal Analysis of Steam Generators; Heat Transfer in Glass; Heat and Mass Transfer During Fluidized Bed Combustion; Single- and Two-Phase Process Heat Transfer.

Farukhi, N.M.

1985-01-01

320

Wound tube heat exchanger  

DOEpatents

What is disclosed is a wound tube heat exchanger in which a plurality of tubes having flattened areas are held contiguous adjacent flattened areas of tubes by a plurality of windings to give a double walled heat exchanger. The plurality of windings serve as a plurality of effective force vectors holding the conduits contiguous heat conducting walls of another conduit and result in highly efficient heat transfer. The resulting heat exchange bundle is economical and can be coiled into the desired shape. Also disclosed are specific embodiments such as the one in which the tubes are expanded against their windings after being coiled to insure highly efficient heat transfer.

Ecker, Amir L. (Duncanville, TX)

1983-01-01

321

Numerical study of heat pipe application in heat recovery systems  

Microsoft Academic Search

Heat pipes are two-phase heat transfer devices with extremely high effective thermal conductivity. They can be cylindrical or planar in structure. Heat pipes can be embedded in a metal cooling plate, which is attached to the heat source, and can also be assembled with a fin stack for fluid heat transfer. Due to the high heat transport capacity, heat exchangers

Song Lin; John Broadbent; Ryan McGlen

2005-01-01

322

The heat pipe heat exchangers: Design, technology and applications  

Microsoft Academic Search

The Heat Pipe Heat Exchanger (HPHE) is a relatively new and very attractice heat exchanger type. For a good understanding of this very special heat exchanger, a minimum knowledge of the heat pipes is required. The heat pipe and thermosyphon basic theory (including the calculation of the thermal limits) is summarized. Some information concerning the heat pipe technological aspects is

S. Chadourne

1991-01-01

323

Numerical and experimental calibration of calorimetric sample cell dedicated to nuclear heating measurements  

SciTech Connect

Online nuclear measurements inside experimental channels of MTRs are needed for experimental works (to design set-ups) and for numerical works (input data) in order to better understanding complex phenomena occurring during the accelerated ageing of materials and the irradiation of nuclear fuel. In this paper we focus only on one kind of measurements: nuclear heating performed by means of a radiometric calorimeter. The aims of numerical and experimental works are firstly to optimize the sensor response for new energy deposit ranges and then to miniaturize this sensor for JHR irradiation conditions A first calorimeter, developed previously by the CEA, is studied. It corresponds to a graphite differential calorimeter divided into two twin cells (a reference cell, and a sample one). It is used with a non adiabatic mode or heat flow mode. Experimental calibration of the sample cell is presented. In that case, energy deposit is simulated by Joule effect and the sample cell is inserted into a bath at a regulated temperature and controlled flow. The response of the sensor is shown versus electrical power imposed for two flow regimes (intensive or moderated forced convection). These experimental results are compared to numerical works and improvements are discussed. (authors)

Brun, J.; Reynard, C.; Merroun, O. [Chemistry Laboratory of Provence LCP UMR 6264 - Universite de Provence, Centre St. Jerome, Bat. Madirel, 13397 Marseille Cedex 20 (France); Lyoussi, A. [French Alternatives Energies and Atomic Energy Commission CEA, Direction de l'Energie Nucleaire DEN, Centre de Cadarache, 13108 Saint-Paul-Lez-Durance (France); Carette, M.; Janulyte, A.; Zerega, Y.; Andre, J. [Chemistry Laboratory of Provence LCP UMR 6264 - Universite de Provence, Centre St. Jerome, Bat. Madirel, 13397 Marseille Cedex 20 (France); Bignan, G.; Chauvin, J. P.; Fourmentel, D.; Gonnier, C.; Guimbal, P.; Malo, J. Y.; Villard, J. F. [French Alternatives Energies and Atomic Energy Commission CEA, Direction de l'Energie Nucleaire DEN, Centre de Cadarache, 13108 Saint-Paul-Lez-Durance (France)

2011-07-01

324

The secure heating reactor  

SciTech Connect

The SECURE heating reactor was designed by ASEA-ATOM as a realistic alternative for district heating in urban areas and for supplying heat to process industries. SECURE has unique safety characteristics, that are based on fundamental laws of physics. The safety does not depend on active components or operator intervention for shutdown and cooling of the reactor. The inherent safety characteristics of the plant cannot be affected by operator errors. Due to its very low environment impact, it can be sited close to heat consumers. The SECURE heating reactor has been shown to be competitive in comparison with other alternatives for heating Helsinki and Seoul. The SECURE heating reactor forms a basis for the power-producing SECURE-P reactor known as PIUS (Process Inherent Ultimate Safety), which is based on the same inherent safety principles. The thermohydraulic function and transient response have been demonstrated in a large electrically heated loop at the ASEA-ATOM laboratories.

Pind, C.

1987-11-01

325

Heating Methods of Forgings.  

National Technical Information Service (NTIS)

The report deals with a study of the most usual electrical heating methods of forgings. Those are investigated under ''Norwegian'' conditions. Inductive heating systems seem to be expensive and result in small return on investment for small production ser...

T. Stroemsvik

1982-01-01

326

Miniature Heat Pipes.  

National Technical Information Service (NTIS)

Small Business Innovation Research contracts from Goddard Space Flight Center to Thermacore Inc. have fostered the company work on devices tagged 'heat pipes' for space application. To control the extreme temperature ranges in space, heat pipes are import...

1997-01-01

327

Sizing plate heat exchangers  

SciTech Connect

Since their commercial debut in the 1930s, plate heat exchangers have found widespread use in the chemical process industries (CPI). Today, more than two dozen firms market this space-saving and highly efficient type of heat exchanger. One reason for the popularity of plate heat exchangers is that their overall heat-transfer coefficient (U) is superior to that of shell-and-tube heat exchangers [1,2,3,4]. In clean water-to-water service, for example, a shell-and-tube heat exchanger has a U value of 350 Btu/ft[sup 2]-h-F, much lower than the 1,000 of a plate design at the same pressure drop. However, the plate heat exchanger's much higher U values also mean that fouling factors have a much greater effect on calculations of exchanger surface area. The right fouling factor is the key to specifying plate heat exchanger areas correctly.

Kerner, J. (Alberts and Associates, Inc., Philadelphia, PA (United States))

1993-11-01

328

Heat storage material  

SciTech Connect

When strontium oxide is applied as a nucleating agent to calcium chloride-hexahydrate as a heat storage material, a supercooling phenomenon of the resulting heat storage material can be suppressed to be slight.

Yanadori, M.; Miyamoto, S.

1984-08-14

329

Pipe Heat Transfer Calculation.  

National Technical Information Service (NTIS)

This is a group of computer programs to determine heat transfer of multiple pipe systems as well as to evaluate economics of underground heat distribution systems. ...Software Description: The system is written in the FORTRAN V programming language for im...

1973-01-01

330

Metal hydride heat pump  

SciTech Connect

A metal hydride heat pump is disclosed comprising a first and a second heat medium receptacle having heat media flowing therein and a plurality of closed vessels each containing a hydrogen gas atmosphere and divided into a first chamber having a first metal hydride filled therein and a second chamber having a second metal hydride filled therein. The first and second chambers of each closed vessel are made to communicate with each other so that hydrogen gas passes from one chamber to the other but the metal hydrides do not, and a group of the first chambers of the closed vessels being located within the first heat medium receptacle and a group of the second chambers of the closed vessels being located within the second heat medium receptacle, whereby heat exchange is carried out between the heat media in the first and second heat medium receptacles and the first and second metal hydrides through the external walls of the closed vessels.

Nishizaki, T.; Miyamoto, K.; Miyamoto, M.; Nakata, Y.; Yamaji, K.; Yoshida, K.

1983-12-27

331

Thermal effects of heat-resistant rubber composites. II. Effect of BaTiO sub 3 -ceramic on thermal effects of carbon black-loaded butyl rubber  

SciTech Connect

In a trial to obtain rubber vulcanizates with improved thermal properties, butyl rubber (IIR) loaded with 20 phr BaTiO{sub 3} was mixed with 100 phr of carbon black. In this case different types of carbon blacks, namely HAF, GPF, SRF and LAMP black were used. Electrical conductivity measurements of vulcanized samples were carried out at different applied electric power. The temperature (T) produced as a result of Joule heating effects as a function of time (t) was recorded. It was found that (T-t) characteristics markedly depend on the presence of barium titanate as well as the type of carbon black. Theoretical treatment of the obtained results was carried out.

Hassan, H.H. (Cairo Univ., Giza (Egypt)); Abdel-Bary, E.M. (Mansoura Univ. (Egypt)); El-Mansy, M.K.; Shash, N.M. (Zagazig Univ. (Egypt))

1989-12-01

332

Abrasion resistant heat pipe  

DOEpatents

A specially constructed heat pipe is described for use in fluidized bed combustors. Two distinct coatings are spray coated onto a heat pipe casing constructed of low thermal expansion metal, each coating serving a different purpose. The first coating forms aluminum oxide to prevent hydrogen permeation into the heat pipe casing, and the second coating contains stabilized zirconium oxide to provide abrasion resistance while not substantially affecting the heat transfer characteristics of the system.

Ernst, D.M.

1984-10-23

333

Solar heating system  

SciTech Connect

A subterranean furnace contains a shell in which a plurality of bricks are arranged in a mass. A mirror reflects sun light into the furnace chamber and onto a magnifying glass which concentrates the heat on the bricks. Air is circulated through the furnace chamber and is heated by the heat which is stored in the bricks. A gas burner is mounted beneath the mass of bricks to supply supplemental heat when needed.

Smith, J.

1982-07-20

334

Solar heat receiver  

DOEpatents

A receiver is described for converting solar energy to heat a gas to temperatures from 700 to 900/sup 0/C. The receiver is formed to minimize impingement of radiation on the walls and to provide maximum heating at and near the entry of the gas exit. Also, the receiver is formed to provide controlled movement of the gas to be heated to minimize wall temperatures. The receiver is designed for use with gas containing fine heat absorbing particles, such as carbon particles.

Hunt, A.J.; Hansen, L.J.; Evans, D.B.

1982-09-29

335

Heat pump technology  

SciTech Connect

A comprehensive handbook on the theory and the practical aspects of heat pumps covers (1) applications and types, (2) thermodynamic principles, (3) potential heat sources, (4) considerations for calculating operating costs and economics, (5) the heat pump's position in the energy industry, (6) designs and systems, (7) development and experience, and (8) practical examples.

von Cube, H.L.; Steimle, F.

1981-01-01

336

The heat pipe  

Microsoft Academic Search

The heat pipe is a device having a high thermal conductance which utilizes the transport of a vapour and rejection of latent heat to achieve efficient thermal energy transport. The theory of heat pipes is well developed. Their use in applications involving temperatures in the cryogenic regime, and with development units running as high as 2000 degrees C, shows that

P. D. Dunn; D. A. Reay

1973-01-01

337

HEAT TRANSFER MEANS  

DOEpatents

A heat exchanger is adapted to unifomly cool a spherical surface. Equations for the design of a spherical heat exchanger hav~g tubes with a uniform center-to-center spining are given. The heat exchanger is illustrated in connection with a liquid-fueled reactor.

Fraas, A.P.; Wislicenus, G.F.

1961-07-11

338

Waste heat management guidebook  

Microsoft Academic Search

Seven papers on sources of waste heat in industrial processes and the technical and economic aspects of heat recovery are presented. A separate abstract was prepared for each chapter; one chapter, Economics of Waste Heat Recovery, by R. Ruegg of NBS, is included in Energy Abstracts for Policy Analysis (EAPA). (LCL)

K. G. Kreider; M. B. McNeil

1977-01-01

339

Heat transfer - Denver 1985  

Microsoft Academic Search

This Symposium Series volume contains AIChE-sponsored session papers accepted for presentation at the 23rd National Heat Transfer Conference. The papers are grouped under the headings of: Heat Transfer for Alternate Energy Technologies; Nuclear Plant Degraded Core Cooling; Direct Flux Solar Energy Process; Numerical Methods for Multiphase Flow System and Component Analysis; General Solar Heat Transfer; Thermal Analysis of Steam Generators;

Farukhi

1985-01-01

340

Liquid heat capacity lasers  

DOEpatents

The heat capacity laser concept is extended to systems in which the heat capacity lasing media is a liquid. The laser active liquid is circulated from a reservoir (where the bulk of the media and hence waste heat resides) through a channel so configured for both optical pumping of the media for gain and for light amplification from the resulting gain.

Comaskey, Brian J. (Walnut Creek, CA); Scheibner, Karl F. (Tracy, CA); Ault, Earl R. (Livermore, CA)

2007-05-01

341

Automotive heat pump  

Microsoft Academic Search

An apparatus and system is disclosed for extracting heat units from a relatively lower temperature zone of a cooling system for a Stirling engine and conveying the heat units to a relatively higher temperature zone serving as the passenger compartment of a vehicle. The system is reversible for either heating or cooling of the passenger compartment. The system makes it

Kreger

1978-01-01

342

Plasma heating in JET  

Microsoft Academic Search

Heating the JET plasma well above temperatures reached in the ohmic phase is the aim of the two additional heating systems planned for JET: ion cyclotron resonance heating (ICRF) and neutral beam injection (NBI). Operations with the latter started in February 1986, initially with hydrogen injection, up to a power level of 7 MW. ICRF power has been delivered to

A. Ainsworth; H. Altmann; R. J. Anderson; J. Arbez; D. Bartlett; W. Bailey; K. Behringer; E. Bertolini; P. Bertoldi; C. H. Best; V. Bhatnagar; R. J. Bickerton; G. Boissin; T. Bonicelli; S. Booth; A. Boschi; G. Bosia; M. Botman; H. Brelen; H. Brinkschulte; M. L. Browne; M. Brusati; T. Budd; M. Bures; P. Butcher; H. Buttgereit; D. Cacaut; C. Caldwell-Nichols; D. Campbell; J. Carwardine; G. Celentano; C. D. Challis; A. Cheetman; J. Christiansen; C. Christodoulopoulos; P. Chuilon; R. Claesen; J. P. Coad; M. Cooke; J. G. Cordey; W. Core; S. Corti; A. E. Costley; G. Cottrell; J. Dean; E. Deksnis; G. Deschamps; K. J. Dietz; J. Dobbing; S. E. Dorling; D. F. Duechs; G. Duesing; H. Duquenoy; L. de Kock; A. Edwards; W. Engelhardt; F. Erhorn; B. Eriksson; H. Falter; T. Hellsten; J. L. Hemmerich; R. Hemsworth; F. Hendriks; R. F. Herzog; L. Horton; J. How; M. Huart; A. Hubbard; M. Hugon; P. Jones; J. Kaeline; A. Kaellne; A. Kaye; B. E. Keen; M. Keilhacker; G. Kinahan; A. Konstantellos; P. Kupschus; P. Lallia; J. R. Last; N. Foden; C. Froger; K. Fullard; A. Galetsas; A. Gallacher; A. Gibson; R. D. Gill; A. Geode; A. Gondhalekar; N. A. Gottardi; C. Gowers; R. Granetz; B. Green; S. Gregoli; F. S. Griph; R. Haange; C. J. Hancock; P. Harbour; R. F. Herog; J. Kaellne; L. Lauro-Taroni; E. Lazzaro; R. C. Lobel; P. Lomas; M. Lorenzo-Gottardi; C. Lowry; G. Magyar; D. Maissonneir; M. Malacarne; V. Marchese; P. Massmann; P. McMullen; M. J. Mead; P. Meriguet; V. Merlo; S. Mills; P. Millward; A. Moissonnier; P. L. Mondini; P. Morgan; G. Murphy; M. F. Nave; L. Nickesson; P. Nielson; P. Noll; S. Nowak; W. Obert; B. Oliver; M. Olsson; J. O'Rourke; M. G. Pacco; J. Paillere; L. Pannacione; S. Papastergiou; D. Pasini; M. Pescatore; J. Planncoulaine; J. P. Poffe; R. Prentice; T. Raimondi; C. Raymond; P. H. Rebut; J. Removille; W. Riediker; R. Roberts; A. Rolfe; R. T. Ross; G. Sadler; J. Saffert; N. Salmon; A. Sand; A. Santagiustina; R. Saunders; M. Schmid; F. C. Schueller; K. Selin; R. Shaw; D. Sigournay; R. Simonini; P. Smeulders; L. Sonnerup; K. Sonnenberg; M. Stamp; C. A. Steed; D. Stork; P. E. Stott; T. E. Stringer; D. Summers; A. Tanga; A. Taroni; A. Terrington; A. Tesini; P. R. Thomas; E. Thompson; F. Tibone; R. Tivery; E. Usselmann; H. Van der Beken; M. Von Hellerman; J. E. Van Montfoort; T. Wade; C. Walker; B. A. Wallander; M. Walravens; K. Walter; M. L. Watkins; M. Watson; D. Webberley; J. Wesson; J. Wilks; T. Winkel; C. Woodward; M. Wykes; D. Young; L. Zennelili; J. Zwart; B. Beaumont; D. Gambier; D. Moreau; J. Ehrenberg; H. Jaeckel; S. Kissel; U. Kuephnapfel; R. Mueller; A. Staebler; A. Weller; J. H. Hamnen; M. Evrared; M. Gadeberg; K. Thomsen; P. Dupperrex; G. Tonetti; N. Lopez-Cardozo; B. Tubbing; J. Von Seggern; J. Tagle; F. Bombarda; G. Bracco; R. Giannella; R. Carolan; M. Cox; M. Forrest; D. Goodall; N. Hawkes; P. Haynes; J. Hugill; K. D. Lawson; G. McCracken; J. Partridge; N. Peacock; J. Snipes; T. Todd; H. Schamel; H. Summers; S. Tsuji; G. Tallents

1986-01-01

343

Heat exchanger antifoulant  

SciTech Connect

Disclosed is a process for reducing the fouling in a heat exchanger in which a hydrocarbon stream is heated or cooled as it passes through the heat exchanger. From 1 to 500 parts per million of a saturated sulfoxide is added to the stream to reduce fouling.

Ferm, R.L.

1984-09-04

344

Heat exchanger antifoulant  

SciTech Connect

Disclosed is a process for reducing the fouling in a heat exchanger in which a hydrocarbon stream is heated or cooled as it passes through the heat exchanger. From 1 to 500 parts per million of an alkylamino alkylphenol is added to the stream to reduce fouling.

Ferm, R.L.; Kray, L.R.

1984-03-06

345

Heat exchanger antifoulant  

SciTech Connect

Disclosed is a process for reducing the fouling in a heat exchanger in which a hydrocarbon stream is heated or cooled as it passes through the heat exchanger. From 1 to 500 parts per million of the reaction product of a polyalkylene amine and a hydroxy fatty acid are added to the stream to reduce fouling.

Ferm, R.L.

1984-02-14

346

Heat exchanger antifoulant  

SciTech Connect

Disclosed is a process for reducing the fouling in a heat exchanger in which a hydrocarbon stream is heated or cooled as it passes through the heat exchanger. From 1 to 500 parts per million of an organic hydroxylamine is added to the stream to reduce fouling.

Ferm, R. L.

1985-11-05

347

Abrasion resistant heat pipe  

Microsoft Academic Search

A specially constructed heat pipe is described for use in fluidized bed combustors. Two distinct coatings are spray coated onto a heat pipe casing constructed of low thermal expansion metal, each coating serving a different purpose. The first coating forms aluminum oxide to prevent hydrogen permeation into the heat pipe casing, and the second coating contains stabilized zirconium oxide to

1984-01-01

348

Abrasion resistant heat pipe  

Microsoft Academic Search

A specially constructed heat pipe for use in fluidized bed combustors. Two distinct coatings are spray coated onto a heat pipe casing constructed of low thermal expansion metal, each coating serving a different purpose. The first coating forms aluminum oxide to prevent hydrogen permeation into the heat pipe casing, and the second coating contains stabilized zirconium oxide to provide abrasion

Donald M

1984-01-01

349

Postharvest heat treatments  

Microsoft Academic Search

Postharvest heat treatments are being used for disinfestation and disinfection of an increasing variety of crops, including flowers, fruits and vegetables. This review focuses on the effects of heat on the commodity and its postharvest quality. The effects of a postharvest heat treatment on aspects of ripening and development of thermotolerance is discussed. Ethylene production, respiration, softening, color change and

Susan Lurie

1998-01-01

350

Air Cycle Heat Pumps.  

National Technical Information Service (NTIS)

Advantages of using air as working medium in heat pumps are, beside environmental safety, a low investment cost and a high COP. To get a high COP, the different parts of the heat pump (compressor, heat exchanger and expander) should be integrated into a s...

L. Ljung

1981-01-01

351

Microtube strip heat exchanger  

Microsoft Academic Search

The purpose of this contract has been to explore the limits of miniaturization of heat exchangers with the goals of (1) improving the theoretical understanding of laminar heat exchangers, (2) evaluating various manufacturing difficulties, and (3) identifying major applications for the technology. A low-cost, ultra-compact heat exchanger could have an enormous impact on industry in the areas of cryocoolers and

F. D. Doty

1992-01-01

352

Pitot heat pump  

Microsoft Academic Search

A pitot heat pump is described wherein a multi-stage pitot pump is employed as the compression means in a heat pump thermodynamic cycle. The heat pump is comprised of a multi-stage vapor pitot pump, liquid pitot pump, turbine, vaporizer, evaporator, condenser and expansion valve. The turbine is used to rotate a shaft to which the impellers of the pitot pump

Grose

1981-01-01

353

Heat storage systems  

Microsoft Academic Search

The present invention provides systems for transfer of heat such as useful in solar energy systems. A heat storage medium is used, preferably salt conditioned by anticaking anti-corrosive treatment whereby hydrated salts have increased utility by remaining granular during severe temperature and humidity changes, permitting the salt to be used more effectively as a heat storage and exchange medium. The

Dumbeck

1979-01-01

354

Heat transfer pipe  

Microsoft Academic Search

A heat transfer pipe for use in a heat exchanger such as air conditioner, freezer and boiler is disclosed wherein grooves are formed in the inner wall surface of the pipe, which are by far finer in size than the grooves that have been provided for the purpose of increasing the heat transfer area in general, and slanting relative to

K. Fujie; M. Itoh; T. Innami; H. Kimura; W. Nakayama; T. Yanagida

1977-01-01

355

Training in the Heat  

MedlinePLUS

... surgeon and chief of the Houston Methodist Center for Sports Medicine. "Kids need time to adjust to the heat," he said in a Houston Methodist news release. "Going from all-day air ... athletes at risk for heat-related illnesses, such as heat exhaustion or ...

356

Heat-Related Illness in Athletes  

Microsoft Academic Search

Heat stroke in athletes is entirely preventable. Exertional heat illness is generally the result of increased heat production and impaired dissipation of heat. It should be treated aggressively to avoid life-threatening complications. The continuum of heat illness includes mild disease (heat edema, heat rash, heat cramps, heat syncope), heat exhaustion, and the most severe form, potentially life-threatening heat stroke. Heat

Allyson S. Howe; Barry P. Boden

2007-01-01

357

Thermodynamic properties of supercritical n-m Lennard-Jones fluids and isochoric and isobaric heat capacity maxima and minima  

NASA Astrophysics Data System (ADS)

Molecular dynamics simulations are reported for the thermodynamic properties of n-m Lennard-Jones fluids, where n = 10 and 12, and m = 5 and 6. Results are reported for the thermal expansion coefficient, isothermal and adiabatic compressibilities, isobaric and isochoric heat capacities, Joule-Thomson coefficient, and speed of sound at supercritical conditions covering a wide range of fluid densities. The thermodynamic criteria for maxima/minima in the isochoric and isobaric heat capacities are identified and the simulation results are also compared with calculations from Lennard-Jones equations of state. The Johnson et al. [Mol. Phys. 78, 591 (1993)] equation of state can be used to reproduce all heat capacity phenomena reported [T. M. Yigzawe and R. J. Sadus, J. Chem. Phys. 138, 194502 (2013)] from molecular dynamics simulations for the 12-6 Lennard-Jones potential. Significantly, these calculations and molecular dynamics results for other n-m Lennard-Jones potentials support the existence of Cp minima at supercritical conditions. The values of n and m also have a significant influence on many other thermodynamic properties.

Mairhofer, Jonas; Sadus, Richard J.

2013-10-01

358

Thermodynamic properties of supercritical n-m Lennard-Jones fluids and isochoric and isobaric heat capacity maxima and minima.  

PubMed

Molecular dynamics simulations are reported for the thermodynamic properties of n-m Lennard-Jones fluids, where n = 10 and 12, and m = 5 and 6. Results are reported for the thermal expansion coefficient, isothermal and adiabatic compressibilities, isobaric and isochoric heat capacities, Joule-Thomson coefficient, and speed of sound at supercritical conditions covering a wide range of fluid densities. The thermodynamic criteria for maxima?minima in the isochoric and isobaric heat capacities are identified and the simulation results are also compared with calculations from Lennard-Jones equations of state. The Johnson et al. [Mol. Phys. 78, 591 (1993)] equation of state can be used to reproduce all heat capacity phenomena reported [T. M. Yigzawe and R. J. Sadus, J. Chem. Phys. 138, 194502 (2013)] from molecular dynamics simulations for the 12-6 Lennard-Jones potential. Significantly, these calculations and molecular dynamics results for other n-m Lennard-Jones potentials support the existence of Cp minima at supercritical conditions. The values of n and m also have a significant influence on many other thermodynamic properties. PMID:24160523

Mairhofer, Jonas; Sadus, Richard J

2013-10-21

359

Chemical heat pump  

DOEpatents

A chemical heat pump system is disclosed for use in heating and cooling structures such as residences or commercial buildings. The system is particularly adapted to utilizing solar energy, but also increases the efficiency of other forms of thermal energy when solar energy is not available. When solar energy is not available for relatively short periods of time, the heat storage capacity of the chemical heat pump is utilized to heat the structure as during nighttime hours. The design also permits home heating from solar energy when the sun is shining. The entire system may be conveniently rooftop located. In order to facilitate installation on existing structures, the absorber and vaporizer portions of the system may each be designed as flat, thin wall, thin pan vessels which materially increase the surface area available for heat transfer. In addition, this thin, flat configuration of the absorber and its thin walled (and therefore relatively flexible) construction permits substantial expansion and contraction of the absorber material during vaporization and absorption without generating voids which would interfere with heat transfer. The heat pump part of the system heats or cools a house or other structure through a combination of evaporation and absorption or, conversely, condensation and desorption, in a pair of containers. A set of automatic controls change the system for operation during winter and summer months and for daytime and nighttime operation to satisfactorily heat and cool a house during an entire year. The absorber chamber is subjected to solar heating during regeneration cycles and is covered by one or more layers of glass or other transparent material. Daytime home air used for heating the home is passed at appropriate flow rates between the absorber container and the first transparent cover layer in heat transfer relationship in a manner that greatly reduce eddies and resultant heat loss from the absorbant surface to ambient atmosphere.

Greiner, Leonard (2750-C Segerstrom Ave., Santa Ana, CA 92704)

1980-01-01

360

The Estimation of Heat Outputs for Road Heating Installations.  

National Technical Information Service (NTIS)

Heat transfer coefficients relating heat losses from surfaces of heated roads to wind speed and the difference between air and surface temperatures have been derived from measurements made during icy conditions. The magnitude of the heat flow downwards fr...

P. J. Williamson

1967-01-01

361

Heat-treatment options and heating times for ash firewood  

Treesearch

New regulations for heat sterilization of ash firewood require holding a core ... than the current international heating standard for treating solid wood packaging. ... factors that control the heating rate and result in differences in heating times.

362

Heating and cooling  

NSDL National Science Digital Library

Heating and cooling homes and businesses require a major energy commitment. This informational piece, part of a series about the future of energy, introduces students to the energy needed to heat and cool homes and workplaces. Students explore energy requirements in the home and at work and discuss current technologies to improve heating and cooling efficiencies. Articles on heat pumps and solar heating and cooling techniques are accessible from a sidebar. A link to a PBS NewsHour article on air conditioning efficiency and a link to material discussing alternatives to air conditioning are also provided. Copyright 2005 Eisenhower National Clearinghouse

Project, Iowa P.

2004-01-01

363

Evaluating heat tracing  

SciTech Connect

Heat tracing is a method to maintain the temperature of the contents of a pipe or container. Some applications for heat tracing include maintaining process fluids at pumpable viscosities, preventing phase change and/or component separation in liquids, and keeping water from freezing when ambient temperatures are sufficiently low. To maximize efficiency and minimize energy costs, heat tracing is used in conjunction with appropriate thermal insulation. The paper discusses the types of heat tracing (steam and electric), the evaluation of electric heat tracing, and comparing costs.

Thompson, J.C. [Raychem Corp., Menlo Park, CA (United States)

1997-09-01

364

Heat Removal with Graphene Lateral Heat Spreaders  

NASA Astrophysics Data System (ADS)

Device downscaling leads to higher chip power densities. A possible approach for heat removal from the localized hot spots is incorporation to chips of materials with high thermal conductivity. Recently, graphene and few-layer graphene (FLG) were proposed for heat removal owing to their superior thermal conductivity [1]. To evaluate the feasibility of this approach we simulated numerically heat propagation in SOI-based chip with and without graphene layers. It was found that incorporation of graphene or FLG can lead to substantial reduction of the hot spot's temperature [2]. The obtained results and are important for the design of graphene heat spreaders and interconnects [3]. [4pt] [1] A.A. Balandin, et al., Nano Lett., 8, (2008); S. Ghosh, et al., Appl. Phys. Lett., 92, (2008) [0pt] [2] S. Subrina, et al., Electron Dev. Lett., December (2009) [0pt] [3] A.A. Balandin, ``New materials can keep chips cool,'' IEEE Spectrum, October 2009

Subrina, S.; Kotchetkov, D.; Ghosh, S.; Balandin, A. A.

2010-03-01

365

Flexible heating head for induction heating  

NASA Astrophysics Data System (ADS)

An induction heating head includes a length of wire having first and second opposite ends and being wound in a flat spiral shape to form an induction coil, a capacitor connected to the first and second ends of the wire, the induction coil and capacitor defining a tank circuit, and a flexible, elastomeric body molded to encase the induction coil. When a susceptor is placed in juxtaposition to the body, and the tank circuit is powered, the susceptor is inductively heated.

Fox, Robert L.; Johnson, Samuel D.; Coultrip, Robert H.; Phillips, W. Morris

1993-11-01

366

Equivalent combined systems of three-heat-source heat pumps  

Microsoft Academic Search

In this paper, the equivalent combined systems of three-heat-source heat pumps are studied. It is pointed out that there may be three combined ways for us to conceive a reversible three-heat-source heat pump as a combined system having a reversible Carnot heat pump driven by a reversible Carnot engine. Whereas for an endoreversible three-heat-source heat pump affected by the heat

Jincan Chen; Zijun Yan

1989-01-01

367

Optimal design of the separate type heat pipe heat exchanger  

Microsoft Academic Search

Separate type heat pipe heat exchangers are often used for large-scale heat exchanging. The arrangement of such a heat exchanger\\u000a conveniently allows heat input to and output from the heat exchanger at remote locations. The traditional method of designing\\u000a an ordinary HPHE (heat pipe heat exchanger) is commonly applied in the separate type exchanger design, but the calculations\\u000a have to

Zi-tao Yu; Ya-cai Hu; Ke-fa Cen

2005-01-01

368

The use of heat pumps in district heat supply  

NASA Astrophysics Data System (ADS)

The cost elements of heat pump heat supply stations are examined and the optimum relationship between peak load boiler and heat pump output is shown. The dependence of plant size and temperature on heat generating costs is indicated and the costs of heat distribution and heat transfer are analysed. The possibility of a combined system of chop and heat pumps for the transport of heat over larger distances is shown.

Winkens, H. P.

1985-04-01

369

Heat pump apparatus  

DOEpatents

A heat pump apparatus including a compact arrangement of individual tubular reactors containing hydride-dehydride beds in opposite end sections, each pair of beds in each reactor being operable by sequential and coordinated treatment with a plurality of heat transfer fluids in a plurality of processing stages, and first and second valves located adjacent the reactor end sections with rotatable members having multiple ports and associated portions for separating the hydride beds at each of the end sections into groups and for simultaneously directing a plurality of heat transfer fluids to the different groups. As heat is being generated by a group of beds, others are being regenerated so that heat is continuously available for space heating. As each of the processing stages is completed for a hydride bed or group of beds, each valve member is rotated causing the heat transfer fluid for the heat processing stage to be directed to that bed or group of beds. Each of the end sections are arranged to form a closed perimeter and the valve member may be rotated repeatedly about the perimeter to provide a continuous operation. Both valves are driven by a common motor to provide a coordinated treatment of beds in the same reactors. The heat pump apparatus is particularly suitable for the utilization of thermal energy supplied by solar collectors and concentrators but may be used with any source of heat, including a source of low-grade heat.

Nelson, Paul A. (Wheaton, IL); Horowitz, Jeffrey S. (Woodridge, IL)

1983-01-01

370

Nanofluid heat capacities  

NASA Astrophysics Data System (ADS)

Significant increases in the heat capacity of heat transfer fluids are needed not only to reduce the costs of liquid heating and cooling processes, but also to bring clean energy producing technologies like concentrating solar power (CSP) to price parity with conventional energy generation. It has been postulated that nanofluids could have higher heat capacities than conventional fluids. In this work, nano- and micron-sized particles were added to five base fluids (poly-? olefin, mineral oil, ethylene glycol, a mixture of water and ethylene glycol, and calcium nitrate tetrahydrate), and the resulting heat capacities were measured and compared with those of the neat base fluids and the weighted average of the heat capacities of the components. The particles used were inert metals and metal oxides that did not undergo any phase transitions over the temperature range studied. In the nanofluids studied here, we found no increase in heat capacity upon the addition of the particles larger than the experimental error.

Starace, Anne K.; Gomez, Judith C.; Wang, Jun; Pradhan, Sulolit; Glatzmaier, Greg C.

2011-12-01

371

Heat Pipe Cooling System with Sensible Heat Sink.  

National Technical Information Service (NTIS)

A heat pipe cooling system which employs a sensible heat sink is discussed. With this type of system, incident aerodynamic heat is transported via a heat pipe from the stagnation region to the heat sink and absorbed by raising the temperature of the heat ...

C. C. Silverstein

1988-01-01

372

Isothermal Solar Heat Storage Materials.  

National Technical Information Service (NTIS)

A group of over 200 potential phase change heat storage materials, melting from 10-90C was identified. Laboratory tests narrowed these to materials recommended for hot faucet water, hydronic heating, forced air heating, heat pump application, radiant wall...

G. A. Lane J. S. Best

1975-01-01

373

Heat stroke and cytokines.  

PubMed

Heat stroke is a life-threatening illness that affects all segments of society, including the young, aged, sick, and healthy. The recent high death toll in France (Dorozynski, 2003) and the death of high-profile athletes has increased public awareness of the adverse effects of heat injury. However, the etiology of the long-term consequences of this syndrome remains poorly understood such that preventive/treatment strategies are needed to mitigate its debilitating effects. Cytokines are important modulators of the acute phase response (APR) to stress, infection, and inflammation. Current data implicating cytokines in heat stroke responses are mainly from correlation studies showing elevated plasma levels in heat stroke patients and experimental animal models. Correlation data fall far short of revealing the mechanisms of cytokine actions such that additional research to determine the role of these endogenous substances in the heat stroke syndrome is required. Furthermore, cytokine determinations have occurred mainly at end-stage heat stroke, such that the role of these substances in progression and long-term recovery is poorly understood. Despite several studies implicating cytokines in heat stroke pathophysiology, few studies have examined the protective effect(s) of cytokine antagonism on the morbidity and mortality of heat stroke. This is particularly surprising since heat stroke responses resemble those observed in the endotoxemic syndrome, for which a role for endogenous cytokines has been strongly implicated. The implication of cytokines as mediators of endotoxemia and the presence of circulating endotoxin in heat stroke patients suggests that much knowledge can be gained from applying our current understanding of endotoxemic pathophysiology to the study of heat stroke. Heat shock proteins (HSPs) are highly conserved proteins that function as molecular chaperones for denatured proteins and reciprocally modulate cytokine production in response to stressful stimuli. HSPs have been shown repeatedly to confer protection in heat stroke and injury models. Interactions between HSPs and cytokines have received considerable attention in the literature within the last decade such that a complex pathway of interactions between cytokines, HSPs, and endotoxin is thought to be occurring in vivo in the orchestration of the APR to heat injury. These data suggest that much of the pathophysiologic changes observed with heat stroke are not a consequence of heat exposure, per se, but are representative of interactions among these three (and presumably additional) components of the innate immune response. This chapter will provide an overview of current knowledge regarding cytokine, HSP, and endotoxin interactions in heat stroke pathophysiology. Insight is provided into the potential therapeutic benefit of cytokine neutralization for mitigation of heat stroke morbidity and mortality based on our current understanding of their role in this syndrome. PMID:17645934

Leon, Lisa R

2007-01-01

374

Heat recovery in refrigeration: I  

Microsoft Academic Search

Considers heat recovery methods, hot gas reclaim, load calculations, and piping (series and parallel) considerations with regard to refrigeration systems. Presents diagrams showing early heat recovery system; discharge gas heat recovery system with heat recovery condenser below main condenser; discharge gas heat recovery system parallel hookup; and discharge gas heat recovery system with highside float control. Explains that all refrigeration

1983-01-01

375

Heat transfer in energy problems  

NASA Astrophysics Data System (ADS)

Results of recent research are presented concerning heat transfer in energy problems, including high-temperature heat transfer, high-flux heat transfer, high-performance heat transfer, heat transfer in nonconventional energy (power and propulsion) systems, and novel heat transfer techniques. Topics discussed include studies of full-coverage film cooling, radiative properties of metals and alloys at high temperature, critical heat flux conditions in high-quality boiling systems, heat transfer characteristics of the evaporation of a liquid droplet on heated surfaces, high-performance surfaces for non-boiling heat transfer, and high performance heat transfer surfaces for boiling and condensation. Also examined are high flux heat transfer in gaseous solid suspension flow, nuclear process heat applications of high temperature heat exchange, heat transfer considerations in the use of new energy resources, and high performance mist-cooled condensers for geothermal binary cycle plants. No individual items are abstracted in this volume

Mizushina, T.; Yang, W. J.

376

Heat transfer characteristics of a gas-to-gas heat exchanger using heat pipes  

Microsoft Academic Search

The heat transfer characteristics of a gas-to-gas heat exchanger employing heat pipes as the heat transfer elements were examined. Experimental data obtained on the heat exchanger containing 66 finned heat pipes were compared with the values calculated by using various empirical and theoretical equations. A basic design procedure for gas-to-gas heat exchangers using heat pipes was then established. The results

Y. Wakiyama; K. Harada; S. Inoue; J. Fujita; H. Suematsu

1978-01-01

377

Heat-pipe Earth.  

PubMed

The heat transport and lithospheric dynamics of early Earth are currently explained by plate tectonic and vertical tectonic models, but these do not offer a global synthesis consistent with the geologic record. Here we use numerical simulations and comparison with the geologic record to explore a heat-pipe model in which volcanism dominates surface heat transport. These simulations indicate that a cold and thick lithosphere developed as a result of frequent volcanic eruptions that advected surface materials downwards. Declining heat sources over time led to an abrupt transition to plate tectonics. Consistent with model predictions, the geologic record shows rapid volcanic resurfacing, contractional deformation, a low geothermal gradient across the bulk of the lithosphere and a rapid decrease in heat-pipe volcanism after initiation of plate tectonics. The heat-pipe Earth model therefore offers a coherent geodynamic framework in which to explore the evolution of our planet before the onset of plate tectonics. PMID:24067709

Moore, William B; Webb, A Alexander G

2013-09-26

378

Induction Heating Systems  

NASA Astrophysics Data System (ADS)

Induction heating technology, a magnetic non-deforming process, was developed by Langley researchers to join plastic and composite components in space. Under NASA license, Inductron Corporation uses the process to produce induction heating systems and equipment for numerous applications. The Torobonder, a portable system, comes with a number of interchangeable heads for aircraft repair. Other developments are the E Heating Head, the Toroid Joining Gun, and the Torobrazer. These products perform bonding applications more quickly, safely and efficiently than previous methods.

1991-01-01

379

NCSX Plasma Heating Methods  

SciTech Connect

The NCSX (National Compact Stellarator Experiment) has been designed to accommodate a variety of heating systems, including ohmic heating, neutral-beam injection, and radio-frequency. Neutral beams will provide one of the primary heating methods for NCSX. In addition to plasma heating, beams are also expected to provide a means for external control over the level of toroidal plasma rotation velocity and its profile. The plan is to provide 3 MW of 50 keV balanced neutral-beam tangential injection with pulse lengths of 500 msec for initial experiments, and to be upgradeable to pulse lengths of 1.5 sec. Subsequent upgrades will add 3 MW of neutral-beam injection. This Chapter discusses the NCSX neutral-beam injection requirements and design issues, and shows how these are provided by the candidate PBX-M (Princeton Beta Experiment-Modification) neutral-beam injection system. In addition, estimations are given for beam-heating efficiencies, scaling of heating efficiency with machine size an d magnetic field level, parameter studies of the optimum beam-injection tangency radius and toroidal injection location, and loss patterns of beam ions on the vacuum chamber wall to assist placement of wall armor and for minimizing the generation of impurities by the energetic beam ions. Finally, subsequent upgrades could add an additional 6 MW of radio-frequency heating by mode-conversion ion-Bernstein wave (MCIBW) heating, and if desired as possible future upgrades, the design also will accommodate high-harmonic fast-wave and electron-cyclotron heating. The initial MCIBW heating technique and the design of the radio-frequency system lend themselves to current drive, so that if current drive became desirable for any reason only minor modifications to the heating system described here would be needed. The radio-frequency system will also be capable of localized ion heating (bulk or tail), and possibly ion-Bernstein-wave-generated sheared flows.

H.W. Kugel; D. Spong; R. Majeski; M. Zarnstorff

2003-02-28

380

NCSX Plasma Heating Methods  

SciTech Connect

The National Compact Stellarator Experiment (NCSX) has been designed to accommodate a variety of heating systems, including ohmic heating, neutral beam injection, and radio-frequency (rf). Neutral beams will provide one of the primary heating methods for NCSX. In addition to plasma heating, neutral beams are also expected to provide a means for external control over the level of toroidal plasma rotation velocity and its profile. The experimental plan requires 3 MW of 50-keV balanced neutral beam tangential injection with pulse lengths of 500 ms for initial experiments, to be upgradeable to pulse lengths of 1.5 s. Subsequent upgrades will add 3MW of neutral beam injection (NBI). This paper discusses the NCSX NBI requirements and design issues and shows how these are provided by the candidate PBX-M NBI system. In addition, estimations are given for beam heating efficiencies, scaling of heating efficiency with machine size and magnetic field level, parameter studies of the optimum beam injection tangency radius and toroidal injection location, and loss patterns of beam ions on the vacuum chamber wall to assist placement of wall armor and for minimizing the generation of impurities by the energetic beam ions. Finally, subsequent upgrades could add an additional 6 MW of rf heating by mode conversion ion Bernstein wave (MCIBW) heating, and if desired as possible future upgrades, the design also will accommodate high-harmonic fast-wave and electron cyclotron heating. The initial MCIBW heating technique and the design of the rf system lend themselves to current drive, so if current drive became desirable for any reason, only minor modifications to the heating system described here would be needed. The rf system will also be capable of localized ion heating (bulk or tail), and possiblyIBW-generated sheared flows.

H.W. Kugel, D. Spong, R. Majeski and M. Zarnstorff

2008-01-18

381

To Heat or Not to Heat?  

NSDL National Science Digital Library

Students are introduced to various types of energy with a focus on thermal energy and types of heat transfer as they are challenged to design a better travel thermos that is cost efficient, aesthetically pleasing and meets the design objective of keeping liquids hot. They base their design decisions on material properties such thermal conductivity, cost and function. These engineering and science concepts are paired with student experiences to build an understanding of heat transfer as it plays a role in their day-to-day lives. While this introduction only shows the top level concepts surrounding the mathematics associated with heat transfer; the skills become immediately useful as students apply what they know to solve an engineering challenge.

Culturally Relevant Engineering Application in Mathematics GK-12 Program,

382

Heat transport performance of axially grooved heat pipe with multiple heating points  

Microsoft Academic Search

This paper describes experimental results and a calculation method for heat transport of heat pipe with multiple heating points. The axially grooved wick heat pipe was made of aluminum alloy and its working fluid was ammonia. The maximum rates of heat transport were obtained by changing the positions and the numbers of heat sources. Based on the experimental results, a

Akihiro Miyasaka; Katsuhiko Nakajima

1989-01-01

383

Electric heating apparatus  

SciTech Connect

An electric heating apparatus is disclosed for heating foods and liquids in a cooking vessel. It's comprising: a metal upper part, having an upper cooking surface and a lower surface; a metal lower part covering the bottom of the heating apparatus, a sealable space being formed between the upper part and the lower part; and, at least one tubular heating device with a metal covering arranged in the space and having a large flat contact surface for thermally conductively engaging the lower surface of the upper metal part, the space having at least a partial vacuum formed therein, the at least partial vacuum reducing convective heat loss and imparting a concave distortion to the upper metal part which counteracts a convex distortion of the upper metal part due to expansion upon heating, thereby holding the upper metal part substantially flat during heating and maximizing surface contact between the cooking surface and a cooking vessel resting thereon, whereby heat is transferred from the cooking surface to the cooking vessel with maximum efficiency. The apparatus may also be constructed as a receptacle for directly heating foods or liquids.

Fischer, K.

1984-02-14

384

Heat Capacity Analysis Report  

SciTech Connect

The purpose of this report is to provide heat capacity values for the host and surrounding rock layers for the waste repository at Yucca Mountain. The heat capacity representations provided by this analysis are used in unsaturated zone (UZ) flow, transport, and coupled processes numerical modeling activities, and in thermal analyses as part of the design of the repository to support the license application. Among the reports that use the heat capacity values estimated in this report are the ''Multiscale Thermohydrologic Model'' report, the ''Drift Degradation Analysis'' report, the ''Ventilation Model and Analysis Report, the Igneous Intrusion Impacts on Waste Packages and Waste Forms'' report, the ''Dike/Drift Interactions report, the Drift-Scale Coupled Processes (DST and TH Seepage) Models'' report, and the ''In-Drift Natural Convection and Condensation'' report. The specific objective of this study is to determine the rock-grain and rock-mass heat capacities for the geologic stratigraphy identified in the ''Mineralogic Model (MM3.0) Report'' (BSC 2004 [DIRS 170031], Table 1-1). This report provides estimates of the heat capacity for all stratigraphic layers except the Paleozoic, for which the mineralogic abundance data required to estimate the heat capacity are not available. The temperature range of interest in this analysis is 25 C to 325 C. This interval is broken into three separate temperature sub-intervals: 25 C to 95 C, 95 C to 114 C, and 114 C to 325 C, which correspond to the preboiling, trans-boiling, and postboiling regimes. Heat capacity is defined as the amount of energy required to raise the temperature of a unit mass of material by one degree (Nimick and Connolly 1991 [DIRS 100690], p. 5). The rock-grain heat capacity is defined as the heat capacity of the rock solids (minerals), and does not include the effect of water that exists in the rock pores. By comparison, the rock-mass heat capacity considers the heat capacity of both solids and pore water. For temperatures in the trans-boiling regime (95 C to 114 C), the additional energy required to vaporize the pore water is accounted for in the rock-mass heat capacity. The rock-grain heat capacities are intended to be used in models and analyses that explicitly account for the thermodynamic effects of the water within the rock porosity. The rock-mass heat capacities are intended to be used in models and analyses that do not explicitly account for these thermodynamic effects, particularly boiling. The term specific heat is often used synonymously with heat capacity; however, the latter term is used throughout this document.

A. Findikakis

2004-11-01

385

Heat and mass exchanger  

SciTech Connect

A mass and heat exchanger includes at least one first substrate with a surface for supporting a continuous flow of a liquid thereon that either absorbs, desorbs, evaporates or condenses one or more gaseous species from or to a surrounding gas; and at least one second substrate operatively associated with the first substrate. The second substrate includes a surface for supporting the continuous flow of the liquid thereon and is adapted to carry a heat exchange fluid therethrough, wherein heat transfer occurs between the liquid and the heat exchange fluid.

Lowenstein, Andrew (Princeton, NJ); Sibilia, Marc J. (Princeton, NJ); Miller, Jeffrey A. (Hopewell, NJ); Tonon, Thomas (Princeton, NJ)

2007-09-18

386

Heat rejection system  

DOEpatents

A cooling system for rejecting waste heat consists of a cooling tower incorporating a plurality of coolant tubes provided with cooling fins and each having a plurality of cooling channels therein, means for directing a heat exchange fluid from the power plant through less than the total number of cooling channels to cool the heat exchange fluid under normal ambient temperature conditions, means for directing water through the remaining cooling channels whenever the ambient temperature rises above the temperature at which dry cooling of the heat exchange fluid is sufficient and means for cooling the water.

Smith, Gregory C. (Richland, WA); Tokarz, Richard D. (Richland, WA); Parry, Jr., Harvey L. (Richland, WA); Braun, Daniel J. (Richland, WA)

1980-01-01

387

Solar heat collector  

SciTech Connect

A compact, self-contained solar heat collector is disclosed which is particularly suited for addition to new or existing structures in the form of window shutters, exterior siding, awnings, columnar elements and the like. The exterior glazing (32) of the collector includes undulating transverse pane segments (36, 38, 118, 156), the angle of which is chosen to optimize insolation during winter months. Beneath the preferably sharp peaks and valleys of such undulations is positioned a heat absorption, storage and exchange assembly (42-64) which defines an enclosed heat transfer cavity (42, 122, 134, 142) through which a heat transfer fluid such as air is directed.

Helman, E.R.; Buford, S.P.; Christopher, J.N.; Fava, D.C.; Helman, H.A.; Holtschneider, H.B.

1984-04-17

388

Microtube strip heat exchanger  

SciTech Connect

During the last quarter, Doty Scientific, Inc. (DSI) continued to make progress on the microtube strip (MTS) heat exchanger. DSI completed a heat exchanger stress analysis of the ten-module heat exchanger bank; and, performed a shell-side flow inhomogeneity analysis of the three-module heat exchanger bank. The company produced 50 tubestrips using an in-house CNC milling machine and began pressing them onto tube arrays. DSI revised some of the tooling required to encapsulate a tube array and press tubestrips into the array to improve some of the prototype tooling. 2 refs., 4 figs.

Doty, F.D.

1991-07-08

389

HEATS: Thermal Energy Storage  

SciTech Connect

HEATS Project: The 15 projects that make up ARPA-E’s HEATS program, short for “High Energy Advanced Thermal Storage,” seek to develop revolutionary, cost-effective ways to store thermal energy. HEATS focuses on 3 specific areas: 1) developing high-temperature solar thermal energy storage capable of cost-effectively delivering electricity around the clock and thermal energy storage for nuclear power plants capable of cost-effectively meeting peak demand, 2) creating synthetic fuel efficiently from sunlight by converting sunlight into heat, and 3) using thermal energy storage to improve the driving range of electric vehicles (EVs) and also enable thermal management of internal combustion engine vehicles.

None

2012-01-01

390

Upgrading heat by a reversed absorption heat pump  

Microsoft Academic Search

Analysis of a reversed absorption heat pump's performance for upgrading low temperature waste-heat from industrial processes and solar heat from a flat-plate solar collector has been carried out. In the case of upgrading waste-heat, the ratio of output to input heat decreases as the temperature at which the output heat is needed increases. For water heating, the performance of the

T. Kiatsiriroat; S. C. Bhattacharya; P. Wibulswas

1986-01-01

391

Boiling heat transfer in compact heat exchangers  

SciTech Connect

Small circular and noncircular channels are representative of flow passages in compact evaporators and condensers. This paper describes results of an experimental study on heat transfer to the flow boiling of refrigerant- 12 in a small circular tube of diameter = 2.46 mm. The objective of the study was to assess the effect of channel size on the heat transfer coefficient and to obtain additional insights relative to the heat transfer mechanisms. The flow channel was made of brass and had an overall length of 0.9 m. The channel wall was electrically heated, and temperatures were measured on the channel wall and in the bulk fluid stream. Voltage taps were located at the same axial locations as the stream thermocouples to allow testing over an exit quality range of 0.21 to 0.94 and a large range of mass flux (63 to 832 kg/m{sup 2}s) and heat flux (2.5 to 59 kW/m{sup 2}). Saturation pressure was nearly constant, averaging 0.82 MPa for most of the testing; a few test data were also taken at a constant lower pressure of 0.52 MPa. Local heat transfer coefficients were determined experimentally. Analysis provided additional support for the conclusion, arrived at from previous studies, that a nucleation mechanism dominates for flow boiling in small channels; nevertheless, a convective-dominant region was identified at very low values of wall superheat (<{approx}3{degrees}C). Previous flow boiling studies in small channels, that did not include wall superheats this low, did not encounter the convective dominant mechanism. Conversely, cryogenic studies at very low wall superheats ({approx}l{degree}C) did not encounter the nucleation dominant regime. The apparent discrepancy is explained by the results of this study.

Tran, T.N.; Wambsganss, M.W. [Argonne National Lab., IL (United States); France, D.M. [Illinois Univ., Chicago, IL (United States). Dept. of Mechanical Engineering

1994-12-31

392

Heat Pipe Integrated Microsystems  

SciTech Connect

The trend in commercial electronics packaging to deliver ever smaller component packaging has enabled the development of new highly integrated modules meeting the demands of the next generation nano satellites. At under ten kilograms, these nano satellites will require both a greater density electronics and a melding of satellite structure and function. Better techniques must be developed to remove the subsequent heat generated by the active components required to-meet future computing requirements. Integration of commercially available electronics must be achieved without the increased costs normally associated with current generation multi chip modules. In this paper we present a method of component integration that uses silicon heat pipe technology and advanced flexible laminate circuit board technology to achieve thermal control and satellite structure. The' electronics/heat pipe stack then becomes an integral component of the spacecraft structure. Thermal management on satellites has always been a problem. The shrinking size of electronics and voltage requirements and the accompanying reduction in power dissipation has helped the situation somewhat. Nevertheless, the demands for increased onboard processing power have resulted in an ever increasing power density within the satellite body. With the introduction of nano satellites, small satellites under ten kilograms and under 1000 cubic inches, the area available on which to place hot components for proper heat dissipation has dwindled dramatically. The resulting satellite has become nearly a solid mass of electronics with nowhere to dissipate heat to space. The silicon heat pipe is attached to an aluminum frame using a thermally conductive epoxy or solder preform. The frame serves three purposes. First, the aluminum frame provides a heat conduction path from the edge of the heat pipe to radiators on the surface of the satellite. Secondly, it serves as an attachment point for extended structures attached to the satellite such as solar panels, radiators, antenna and.telescopes (for communications or sensors). Finally, the packages make thermal contact to the surface of the silicon heat pipe through soft thermal pads. Electronic components can be placed on both sides of the flexible circuit interconnect. Silicon heat pipes have a number of advantages over heat pipe constructed from other materials. Silicon heat pipes offer the ability to put the heat pipe structure beneath the active components of a processed silicon wafer. This would be one way of efficiently cooling the heat generated by wafer scale integrated systems. Using this technique, all the functions of a satellite could be reduced to a few silicon wafers. The integration of the heat pipe and the electronics would further reduce the size and weight of the satellite.

Gass, K.; Robertson, P.J.; Shul, R.; Tigges, C.

1999-03-30

393

The wire array Z-pinch: an efficient x-ray source for ICF and a new ion heating mechanism  

NASA Astrophysics Data System (ADS)

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.

Haines, M. G.

2008-10-01

394

The Wire Array Z-Pinch AN Efficient X-Ray Source for Icf and a New Ion Heating Mechanism  

NASA Astrophysics Data System (ADS)

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. First, the wires heat and form a surrounding vapor 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/vapor 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 thermalised and equipartition heats the electrons, which then radiate in a 5 ns pulse. In some conditions the energy radiated as 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 to 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.

Haines, M. G.

2009-07-01

395

Air-density-dependent model for analysis of air heating associated with streamers, leaders, and transient luminous events  

NASA Astrophysics Data System (ADS)

Blue and gigantic jets are transient luminous events in the middle atmosphere that form when conventional lightning leaders escape upward from the thundercloud. The conditions in the Earth's atmosphere (i.e., air density, reduced electric field, etc.) leading to conversion of hot leader channels driven by thermal ionization near cloud tops to nonthermal streamer forms observed at higher altitudes are not understood at present. This paper presents a formulation of a streamer-to-spark transition model that allows studies of gas dynamics and chemical kinetics involved in heating of air in streamer channels for a given air density N under assumption of constant applied electric field E. The model accounts for the dynamic expansion of the heated air in the streamer channel and resultant effects of E/N variations on plasma kinetics, the vibrational excitation of nitrogen molecules N2(v), effects of gains in electron energy in collisions with N2(v), and associative ionization processes involving N2(A3?u+) and N2(a'1?u-) species. The results are in excellent agreement with available experimental data at ground and near-ground air pressures and demonstrate that for the air densities corresponding to 0-70 km altitudes the kinetic effects lead to a significant acceleration of the heating, with effective heating times scaling closer to 1/N than to 1/N2 predicted on the basis of similarity laws for Joule heating. This acceleration is attributed to a strong reduction in electron losses due to three-body attachment and electron-ion recombination processes with reduction of air pressure.

Riousset, Jeremy A.; Pasko, Victor P.; Bourdon, Anne

2010-12-01

396

Experimental investigations of micro-scale flow and heat transfer phenomena by using molecular tagging techniques  

NASA Astrophysics Data System (ADS)

Recent progress made in the development of novel molecule-based flow diagnostic techniques, including molecular tagging velocimetry (MTV) and lifetime-based molecular tagging thermometry (MTT), to achieve simultaneous measurements of multiple important flow variables for micro-flows and micro-scale heat transfer studies is reported in this study. The focus of the work described here is the particular class of molecular tagging tracers that relies on phosphorescence. Instead of using tiny particles, especially designed phosphorescent molecules, which can be turned into long-lasting glowing marks upon excitation by photons of appropriate wavelength, are used as tracers for both flow velocity and temperature measurements. A pulsed laser is used to 'tag' the tracer molecules in the regions of interest, and the tagged molecules are imaged at two successive times within the photoluminescence lifetime of the tracer molecules. The measured Lagrangian displacement of the tagged molecules provides the estimate of the fluid velocity. The simultaneous temperature measurement is achieved by taking advantage of the temperature dependence of phosphorescence lifetime, which is estimated from the intensity ratio of the tagged molecules in the acquired two phosphorescence images. The implementation and application of the molecular tagging approach for micro-scale thermal flow studies are demonstrated by two examples. The first example is to conduct simultaneous flow velocity and temperature measurements inside a microchannel to quantify the transient behavior of electroosmotic flow (EOF) to elucidate underlying physics associated with the effects of Joule heating on electrokinematically driven flows. The second example is to examine the time evolution of the unsteady heat transfer and phase changing process inside micro-sized, icing water droplets, which is pertinent to the ice formation and accretion processes as water droplets impinge onto cold wind turbine blades.

Hu, Hui; Jin, Zheyan; Nocera, Daniel; Lum, Chee; Koochesfahani, Manoochehr

2010-08-01

397

Performance Evaluation of Heat Pipe Heat Exchanger  

Microsoft Academic Search

To the basis of first law of thermodynamics, mainly applicable to engineering calculations; to the basis of the second law of thermodynamics - entropy analysis method, can be used to apply to theoretical analysis and engineering calculations. In this paper, a single performance valuation and entropy analysis for heat recovery equipment have been used, which is to make performance evaluation

Zhang Jie; Ren Yan; Zhang Li Hong; Zhang Kang

2010-01-01

398

Radiative heat exchange between a fluidized bed and heated surface  

Microsoft Academic Search

The radiative heat exchange between a fluidized bed and a heated surface was investigated via an optical experiment employing a He-Ne laser and numerical simulation analysis. A model for predicting the radiative heat transfer is proposed that considers the thermal boundary layer near the heated surface. The numerical results indicate that radiative heat transfer is enhanced when the penetration depth

Jun Yamada; Yasuo Kurosaki; Isao Satoh; Kazuhiko Shimada

1995-01-01

399

A method of analysis for heat pipe heat exchangers  

Microsoft Academic Search

A method of analysis for the thermal performance of heat pipe heat exchangers based on the conductance model was developed in the present study. In the analysis the specific heat conductance of the heat pipe was obtained from a performance test of a single heat pipe described in the present paper and the well-known universal correlations were used to calculate

B. J. Huang; J. T. Tsuei

1985-01-01

400

Experimental investigation of a manifold heat-pipe heat exchanger  

Microsoft Academic Search

Results of experimental investigations of a heat exchanger on a manifold water heat pipe are given. An analysis is made of the temperature distribution along the heat-transfer agent path as a function of the transferred heat power. The influence of the degree of filling with the heat transfer agent on the operating characteristics of the construction is considered.

S. V. Konev; Wang Tszin'lyan; I. I. D'Yakov

1995-01-01

401

Preliminary design study of heat pipe heat exchangers  

Microsoft Academic Search

A preliminary design study was conducted in order to identify the important design parameters which can be varied to optimize overall performance of heat pipe heat exchangers. A computer program was developed to analyze the heat exchanger performance using conventional design procedures for finned tube heat exchangers and using conventional design procedures for three-puddle-artery heat pipes.

K. T. Feldman; D. C. Lu

1976-01-01

402

Heat pipe heat exchangers as energy recovery devices  

Microsoft Academic Search

Counterflow heat exchangers comprised of a bundle of heat pipes with secondary finned surfaces attached offer attractive advantages as energy recovery units. With no moving parts and wide design flexibility, these heat pipe heat exchangers are finding ever increasing usage in air-to-air heat recovery. Three general classes of applications can be identified: using energy recovery from process exhaust to regenerate

Ruch

1976-01-01

403

Heat pipes and use of heat pipes in furnace exhaust  

SciTech Connect

An array of a plurality of heat pipe are mounted in spaced relationship to one another with the hot end of the heat pipes in a heated environment, e.g. the exhaust flue of a furnace, and the cold end outside the furnace. Heat conversion equipment is connected to the cold end of the heat pipes.

Polcyn, Adam D. (Pittsburgh, PA)

2010-12-28

404

Heat transfer in a pulsating heat pipe with open end  

Microsoft Academic Search

Heat transfer in the evaporator and condenser sections of a pulsating heat pipe (PHP) with open end is modeled by analyzing thin film evaporation and condensation. The heat transfer solutions are applied to the thermal model of the pulsating heat pipe and a parametric study was performed. The results show that the heat transfer in a PHP is mainly due

Yuwen Zhang; Amir Faghri

2002-01-01

405

High Flux Heat Exchanger.  

National Technical Information Service (NTIS)

This interim report documents the results of the first two phases of a four-phase program to develop a high flux heat exchanger for cooling future high performance aircraft electronics. Phase I defines future needs for high flux heat removal in advanced m...

E. M. Flynn M. J. Mackowski

1993-01-01

406

Microwave heating of foodstuffs  

Microsoft Academic Search

The temperature distribution in a product submitted to microwave radiation is governed by the interaction and absorption of radiation by the medium and the accompanying transport processes due to the dissipation of electromagnetic energy into heat. Thus, modeling of microwave heating involves coupling the models for microwave power absorption and temperature distribution inside the product. In this study, a model

M. E. C. Oliveira; A. S. Franca

2002-01-01

407

Modelling microwave heating  

Microsoft Academic Search

Although microwave radiation is best known for heating food in the kitchen, in recent years it has found new applications in many industrial processes, such as those involving melting, smelting, sintering, drying, and joining. Heating by microwave radiation constitutes a highly coupled nonlinear problem giving rise to new and unexpected physical behavior, the best known of which is the appearance

James M Hill; Timothy R Marchant

1996-01-01

408

Mechanical Heat Flux Recorder.  

National Technical Information Service (NTIS)

The patent application describes a mechanical heat flux recorder which is based upon the shape recovery properties of a nickel - titanium alloy (NiTi). A pair of nickel-titanium strips are connected between a heat sink block enclosed in an asbestos lined ...

W. K. Smith

1974-01-01

409

Air-Heating Device.  

National Technical Information Service (NTIS)

The purpose of the patent is for an effective use of electrical energy for the heating of air. The housing of the device is made with an induction coil located on the external surface and by a heat-exchange element placed inside its cavity and made of a f...

N. T. Levin

1973-01-01

410

Waste heat boiler deskbook  

Microsoft Academic Search

Energy management programs are vital to the economic life of any industry and heat recovery boilers play a dominant role in those projects which otherwise waste energy from hot flue gases. The book addresses various aspects of heat recovery boilers, such as engineering, specifying, system design, optimization and performance evaluation. Hence engineers and managers involved in several disciplines of energy

Ganapathy

1991-01-01

411

Waste Heat Management Guidebook.  

National Technical Information Service (NTIS)

Sources of waste (i.e., discarded) heat in industrial processes are reviewed, and an overview of off-the-shelf technology available for its use is given. Discussions of waste heat measurement technology and economics are included, as are fourteen case stu...

K. G. Kreider M. B. McNeil

1977-01-01

412

Microchannel heat sink assembly  

DOEpatents

The present invention provides a microchannel heat sink with a thermal range from cryogenic temperatures to several hundred degrees centigrade. The heat sink can be used with a variety of fluids, such as cryogenic or corrosive fluids, and can be operated at a high pressure. The heat sink comprises a microchannel layer preferably formed of silicon, and a manifold layer preferably formed of glass. The manifold layer comprises an inlet groove and outlet groove which define an inlet manifold and an outlet manifold. The inlet manifold delivers coolant to the inlet section of the microchannels, and the outlet manifold receives coolant from the outlet section of the microchannels. In one embodiment, the manifold layer comprises an inlet hole extending through the manifold layer to the inlet manifold, and an outlet hole extending through the manifold layer to the outlet manifold. Coolant is supplied to the heat sink through a conduit assembly connected to the heat sink. A resilient seal, such as a gasket or an O-ring, is disposed between the conduit and the hole in the heat sink in order to provide a watertight seal. In other embodiments, the conduit assembly may comprise a metal tube which is connected to the heat sink by a soft solder. In still other embodiments, the heat sink may comprise inlet and outlet nipples. The present invention has application in supercomputers, integrated circuits and other electronic devices, and is suitable for cooling materials to superconducting temperatures. 13 figs.

Bonde, W.L.; Contolini, R.J.

1992-03-24

413

Scraped surface heat exchangers.  

PubMed

Scraped surface heat exchangers (SSHEs) are commonly used in the food, chemical, and pharmaceutical industries for heat transfer, crystallization, and other continuous processes. They are ideally suited for products that are viscous, sticky, that contain particulate matter, or that need some degree of crystallization. Since these characteristics describe a vast majority of processed foods, SSHEs are especially suited for pumpable food products. During operation, the product is brought in contact with a heat transfer surface that is rapidly and continuously scraped, thereby exposing the surface to the passage of untreated product. In addition to maintaining high and uniform heat exchange, the scraper blades also provide simultaneous mixing and agitation. Heat exchange for sticky and viscous foods such as heavy salad dressings, margarine, chocolate, peanut butter, fondant, ice cream, and shortenings is possible only by using SSHEs. High heat transfer coefficients are achieved because the boundary layer is continuously replaced by fresh material. Moreover, the product is in contact with the heating surface for only a few seconds and high temperature gradients can be used without the danger of causing undesirable reactions. SSHEs are versatile in the use of heat transfer medium and the various unit operations that can be carried out simultaneously. This article critically reviews the current understanding of the operations and applications of SSHEs. PMID:16527753

Rao, Chetan S; Hartel, Richard W

2006-01-01

414

Heat-storing composition  

SciTech Connect

A heat-storing composition comprising acetic acid and at least one of sodium acetate, ammonium acetate, potassium acetate and calcium acetate works at a desired temperature in a temperature range of 5/sup 0/-20/sup 0/ C. and is chemically stable with a high heat-storing capacity.

Koike, K.; Yanadori, M.

1983-11-01

415

Heat Treatment for Superalloy.  

National Technical Information Service (NTIS)

A cobalt-free nickel-base superalloy composed of in weight % 15 Cr - 5 Mo - 3.5 Ti - 4 Al - 0.07 (max) C - remainder Ni is given a modified heat treatment. With this heat treatment the cobalt-free alloy achieves certain of the mechanical properties of the...

F. H. Harf

1986-01-01

416

Solar heating panel arrangement  

Microsoft Academic Search

A solar heating panel arrangement and method are disclosed wherein a plurality of spherical lenses transmit and focus solar radiation onto the upper surface of a fluid passage for various relative positions of the sun. The upper surface of the passage is in heat transfer proximity to the fluid therein, causing solar radiation focused thereon to be transferred to the

1983-01-01

417

Static solar heat collectors  

Microsoft Academic Search

A load-bearing building panel capable of forming an external wall cladding or roof component has a solar heat collecting capacity in the form of channels for heat exchange fluid incorporated in the fabric of the panel. The panel is made of a structural plastics material, such as GRP. Laminate, successive layers being moulded to simulate tiles. On the back or

Brill-Edwards

1981-01-01

418

The Earth's Heat Budget  

NSDL National Science Digital Library

Hands-on laboratory activity that allows students to investigate the effects of distance and angle on the input of solar radiation at Earth's surface, the role played by albedo, the heat capacity of land and water, and how these cause the seasons. Students predict radiative heating based on simple geometry and experiment to test their hypotheses.

Plotnick, Roy; Teachers, National A.

419

Heat storage material  

SciTech Connect

A heat storage material to be used for air cooling systems is provided. This heat storage material comprises acetic acid or a mixture of acetic acid and one or more acetates and is further added with at least one anhydrous halide as nucleating agent to prevent supercooling.

Kamohara, H.; Koike, K.; Miyamoto, S.; Yanadori, M.

1985-05-21

420

Heat-recovery economics  

Microsoft Academic Search

Payback period is discussed as a criterion for making an investment decision. To demonstrate the method of determining payback periods and the present worth cost of a heat-reclaim system, an actual case is examined where a decision had to be made whether or not a heat-reclaim system should be installed in a student dining hall of a college in New

Yanuck

1981-01-01

421

Microchannel heat sink assembly  

DOEpatents

The present invention provides a microchannel heat sink with a thermal range from cryogenic temperatures to several hundred degrees centigrade. The heat sink can be used with a variety of fluids, such as cryogenic or corrosive fluids, and can be operated at a high pressure. The heat sink comprises a microchannel layer preferably formed of silicon, and a manifold layer preferably formed of glass. The manifold layer comprises an inlet groove and outlet groove which define an inlet manifold and an outlet manifold. The inlet manifold delivers coolant to the inlet section of the microchannels, and the outlet manifold receives coolant from the outlet section of the microchannels. In one embodiment, the manifold layer comprises an inlet hole extending through the manifold layer to the inlet manifold, and an outlet hole extending through the manifold layer to the outlet manifold. Coolant is supplied to the heat sink through a conduit assembly connected to the heat sink. A resilient seal, such as a gasket or an O-ring, is disposed between the conduit and the hole in the heat sink in order to provide a watetight seal. In other embodiments, the conduit assembly may comprise a metal tube which is connected to the heat sink by a soft solder. In still other embodiments, the heat sink may comprise inlet and outlet nipples. The present invention has application in supercomputers, integrated circuits and other electronic devices, and is suitable for cooling materials to superconducting temperatures.

Bonde, Wayne L. (Livermore, CA); Contolini, Robert J. (Pleasanton, CA)

1992-01-01

422

Soil Heat Flow Model  

Microsoft Academic Search

The Penman-Monteith method for estimating evapotranspiration (ET) has been recommended by FAO. This method requires measures of temperature, wind speed, relative humidity and heat flow in the soil. This last variable is rarely available. Soil heat flow is generally small compared to the net radiation, and many times is ignored in the energy balance. Nevertheless, the addition or subtraction of

E. Varas; C. Nunez; F. J. Meza

2008-01-01

423

Chemical heat pump  

DOEpatents

A chemical heat pump system is disclosed for use in heating and cooling structures such as residences or commercial buildings. The system is particularly adapted to utilizing solar energy, but also increases the efficiency of other forms of thermal energy when solar energy is not available. When solar energy is not available for relatively short periods of time, the heat storage capacity of the chemical heat pump is utilized to heat the structure, as during nighttime hours. The design also permits home heating from solar energy when the sun is shining. The entire system may be conveniently rooftop located. In order to facilitate installation on existing structures, the absorber and vaporizer portions of the system may each be designed as flat, thin wall, thin pan vessels which materially increase the surface area available for heat transfer. In addition, this thin, flat configuration of the absorber and its thin walled (and therefore relatively flexible) construction permits substantial expansion and contraction of the absorber material during vaporization and absorption without generating voids which would interfere with heat transfer.

Greiner, Leonard (2853-A Hickory Pl., Costa Mesa, CA 92626)

1984-01-01

424

Chemical heat pump  

DOEpatents

A chemical heat pump system is disclosed for use in heating and cooling structures such as residences or commercial buildings. The system is particularly adapted to utilizing solar energy, but also increases the efficiency of other forms of thermal energy when solar energy is not available. When solar energy is not available for relatively short periods of time, the heat storage capacity of the chemical heat pump is utilized to heat the structure, as during nighttime hours. The design also permits home heating from solar energy when the sun is shining. The entire system may be conveniently rooftop located. In order to faciliate installation on existing structures, the absorber and vaporizer portions of the system may each be designed as flat, thin wall, thin pan vessels which materially increase the surface area available for heat transfer. In addition, this thin, flat configuration of the absorber and its thin walled (and therefore relatively flexible) construction permits substantial expansion and contraction of the absorber material during vaporization and absorption without generating voids which would interfere with heat transfer.

Greiner, Leonard (2853-A Hickory Pl., Costa Mesa, CA 92626)

1984-01-01

425

Chemical heat pump  

DOEpatents

A chemical heat pump system is disclosed for use in heating and cooling structures such as residences or commercial buildings. The system is particularly adapted to utilizing solar energy, but also increases the efficiency of other forms of thermal energy when solar energy is not available. When solar energy is not available for relatively short periods of time, the heat storage capacity of the chemical heat pump is utilized to heat the structure, as during nighttime hours. The design also permits home heating from solar energy when the sun is shining. The entire system may be conveniently rooftop located. In order to facilitate intallation on existing structures, the absorber and vaporizer portions of the system may each be designed as flat, thin wall, thin pan vessels which materially increase the surface area available for heat transfer. In addition, this thin, flat configuration of the absorber and its thin walled (and therefore relatively flexible) construction permits substantial expansion and contraction of the absorber material during vaporization and absorption without generating voids which would interfere with heat transfer.

Greiner, Leonard (2853-A Hickory Pl., Costa Mesa, CA 92626)

1984-01-01

426

Chemical heat pump  

DOEpatents

A chemical heat pump system is disclosed for use in heating and cooling structures such as residences or commercial buildings. The system is particularly adapted to utilizing solar energy, but also increases the efficiency of other forms of thermal energy when solar energy is not available. When solar energy is not available for relatively short periods of time, the heat storage capacity of the chemical heat pump is utilized to heat the structure, as during nighttime hours. The design also permits home heating from solar energy when the sun is shining. The entire system may be conveniently rooftop located. In order to facilitate installation on existing structures, the absorber and vaporizer portions of the system may each be designed as flat, thin wall, thin pan vessels which materially increase the surface area available for heat transfer. In addition, this thin, flat configuration of the absorber and its thin walled (and therefore relatively flexible) construction permits substantial expansion and contraction of the absorber material during vaporization and absorption without generating voids which would interfere with heat transfer.

Greiner, Leonard (2853-A Hickory Pl., Costa Mesa, CA 92626)

1981-01-01

427

Vacuum powered heat exchanger  

SciTech Connect

In an internal combustion engine including an oil lubrication system, a liquid cooling system, and an improved air intake system is described. The improved air intake system comprises: a housing including a first opening in one end, which opening is open to the atmosphere and a second opening comprising an air outlet opening in the other end open to the air intake manifold of the engine, a heat exchanger positioned in the first opening. The heat exchanger consists of a series of coils positioned in the flow path of the atmospheric air as it enters the housing, the heat exchanger being fluidly connected to either the engine lubrication system or the cooling system to provide a warm heat source for the incoming air to the housing, acceleration means positioned in the housing downstream of the heat exchanger, the acceleration means comprising a honeycomb structure positioned across the air intake flow path. The honey-comb structure includes a multitude of honey combed mini-venturi cells through which the heated air flows in an accelerated mode, a removable air filter positioned between the heat exchanger and the acceleration means and a single opening provided in the housing through which the air filter can be passed and removed, and additional openings in the housing positioned downstream of the heat exchanger and upstream of the air filter, the additional openings including removable flaps for opening and closing the openings to control the temperature of the air flowing through the housing.

Ruffolo, R.F.

1986-06-24

428

Microscale Evaporation Heat Transfer  

Microsoft Academic Search

In this work, microscale evaporation heat transfer and capillary phenomena for ultra thin liquid film area are presented. The interface shapes of curved liquid film in rectangular minichannel and in vicinity of liquid-vapor-solid contact line are determined by a numerical solution of simplified conduction through liquid layer. The data of numerical calculation of local heat transfer in rectangular channel and

V. V. Kuznetsov; S. A. Safonov

429

Heat transfer in pipes  

Microsoft Academic Search

The heat transfer from hot water to a cold copper pipe in laminar and turbulent flow condition is determined. The mean flow through velocity in the pipe, relative test length and initial temperature in the vessel were varied extensively during tests. Measurements confirm Nusselt's theory for large test lengths in laminar range. A new equation is derived for heat transfer

T. Burbach

1985-01-01

430

Waste heat recovery system  

SciTech Connect

This invention relates to a system for reclaiming or recovering heat which would otherwise be lost from a heating plant. The invention accordingly relates to a heating plant incorporating a plurality of boilers, including a stand-by boiler, there being means for supplying fuel and air to at least one of said boilers, except for the stand-by boiler, and flue gas exhaust ducts associated with each of such boilers. The improvement according to the invention is a waste heat recovery system wherein the flue gas exhaust duct from said at least one boiler is operatively connected to the stand-by boiler for the circulation of hot flue gases therethrough in contact with its heat exchange surfaces thereby to effect the heating of water passing through the standby boiler thereby to recover a portion of the heat energy in the flue gases. The system further includes a means for controlling the temperature of the water in the stand-by boiler at temperatures above those necessary to avoid excessive cooling of the flue gases within the stand-by boiler and consequent undesired condensation of certain flue gas components on its heat exchange surfaces.

Beckett, A.

1983-02-01

431

Passive Solar Heating Residences.  

National Technical Information Service (NTIS)

Passive solar heating systems can supply a major portion of a house's heating load if properly designed. The four basic concepts used are direct gain, thermal storage in wall or roof, solar greenhouse and convective loop. In most applications some of thes...

W. E. Olson

1979-01-01

432

Radioisotopic heat source  

DOEpatents

Disclosed is a radioisotopic heat source and method for a long life electrical generator. The source includes plutonium dioxide shards and yttrium or hafnium in a container of tantalum-tungsten-hafnium alloy, all being in a nickel alloy outer container, and subjected to heat treatment of from about 1570$sup 0$F to about 1720$sup 0$F for about one h. (auth)

Jones, G.J.; Selle, J.E.; Teaney, P.E.

1975-09-30

433

Multi source heat pump air conditioning system  

Microsoft Academic Search

An air conditioning system is described utilizing low temperature heating sources of the environment to maximize the heat coefficient of performance by conserving subterranean heat, atmospheric heat, solar heat, and auxiliary heat sources in combination with a reversible-cycle water source heat pump by absorption of heat energy into a liquid (water). Said heat energy is applied to the heat pump

Meckler

1979-01-01

434

Solar heating system  

DOEpatents

An improved solar heating system in which the incident radiation of the sun is absorbed on collector panels, transferred to a storage unit and then distributed as heat for a building and the like. The improvement is obtained by utilizing a storage unit comprising separate compartments containing an array of materials having different melting points ranging from 75.degree. to 180.degree. F. The materials in the storage system are melted in accordance with the amount of heat absorbed from the sun and then transferred to the storage system. An efficient low volume storage system is provided by utilizing the latent heat of fusion of the materials as they change states in storing and releasing heat for distribution.

Schreyer, James M. (Oak Ridge, TN); Dorsey, George F. (Concord, TN)

1982-01-01

435

Improved solar heating systems  

DOEpatents

An improved solar heating system is described in which the incident radiation of the sun is absorbed on collector panels, transferred to a storage unit and then distributed as heat for a building and the like. The improvement is obtained by utilizing a storage unit comprising separate compartments containing an array of materials having different melting points ranging from 75 to 180/sup 0/F. The materials in the storage system are melted in accordance with the amount of heat absorbed from the sun and then transferred to the storage system. An efficient low volume storage system is provided by utilizing the latent heat of fusion of the materials as they change states in storing ad releasing heat for distribution.

Schreyer, J.M.; Dorsey, G.F.

1980-05-16

436

Heat transfer effect on the specific heating load of heat pumps  

Microsoft Academic Search

The maximum possible specific heating load that can be obtained from two-heat-reservoir heat pumps with a set of high-temperature heat sinks and low-temperature heat sources is analyzed. The heat pumps considered in this paper include (1) externally and internally reversible, (2) externally irreversible and internally reversible, (3) externally reversible and internally irreversible and (4) externally and internally irreversible heat pumps.

Lingen Chen; Chih Wu; Fengrui Sun

1997-01-01

437

Lightweight long life heat exchanger  

Microsoft Academic Search

A shuttle orbiter flight configuration aluminum heat exchanger was designed, fabricated, and tested. The heat exchanger utilized aluminum clad titanium composite parting sheets for protection against parting sheet pin hole corrosion. The heat exchanger, which is fully interchangeable with the shuttle condensing heat exchanger, includes slurpers (a means for removing condensed water from the downstream face of the heat exchanger),

E. K. Moore

1976-01-01

438

Experimental research on heat transfer of pulsating heat pipe  

NASA Astrophysics Data System (ADS)

Experimental research was conducted to understand heat transfer characteristic of pulsating heat pipe in this paper, and the PHP is made of high quality glass capillary tube. Under different fill ratio, heat transfer rate and many other influence factors, the flow patterns were observed in the start-up, transition and stable stage. The effects of heating position on heat transfer were discussed. The experimental results indicate that no annular flow appears in top heating condition. Under different fill ratios and heat transfer rate, the flow pattern in PHP is transferred from bulk flow to semi-annular flow and annular flow, and the performance of heat transfer is improved for down heating case. The experimental results indicate that the total heat resistant of PHP is increased with fill ratio, and heat transfer rate achieves optimum at filling rate 50%. But for pulsating heat pipe with changing diameters the thermal resistance is higher than that with uniform diameters.

Li, Jia; Yan, Li

2008-06-01

439

2. SALEMBROSIUS CONTINUOUS GASFIRED HEAT TREATING LINE AT HEAT TREATMENT ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

2. SALEM-BROSIUS CONTINUOUS GAS-FIRED HEAT TREATING LINE AT HEAT TREATMENT PLANT OF THE DUQUESNE WORKS. - U.S. Steel Duquesne Works, Heat Treatment Plant, Along Monongahela River, Duquesne, Allegheny County, PA

440

PreHeat: controlling home heating using occupancy prediction  

Microsoft Academic Search

Home heating is a major factor in worldwide energy use. Our system, PreHeat, aims to more efficiently heat homes by using occupancy sensing and occupancy prediction to automatically control home heating. We deployed PreHeat in five homes, three in the US and two in the UK. In UK homes, we controlled heating on a per-room basis to enable further energy

James Scott; A. J. Bernheim Brush; John Krumm; Brian Meyers; Michael Hazas; Stephen Hodges; Nicolas Villar

2011-01-01

441

Progress in heat pipe and porous heat exchanger technology  

Microsoft Academic Search

This is a review of the papers presented at the 1st International Heat Pipe Conference held in Stuttgart, 15-17 October 1973. The review deals with heat pipe application in different branches of technology, heat- and mass-transfer processes in heat pipes, design of variable-conductance heat pipes, optimization of their parameters, operation of heat pipes under weightlessness and in the field of

A. V. Luikov; L. L. Vasiliev

1975-01-01

442

Analysis and application of the heat pipe heat exchanger  

Microsoft Academic Search

Heat pipe heat exchangers offer many advantages over more conventional heat exchangers, particularly for gas-to-gas application. Proper application of these devices depends on the conditions imposed by the process from which waste heat is to be recovered, and some of the more common constraints are analyzed. The overall operation of heat pipe heat exchangers is best studied using effectiveness-NTU calculations,

T. H. Sun; R. C. Prager

1978-01-01

443

The Coronal Heating Paradox  

NASA Astrophysics Data System (ADS)

The ``coronal heating problem'' has been with us over 60 years, and hundreds of theoretical models have been proposed without an obvious solution in sight. In this paper we point out that observations show no evidence for local heating in the solar corona, but rather for heating below the corona in the transition region and upper chromosphere, with subsequent chromospheric evaporation as known in flares. New observational evidence for this scenario comes from (1) the temperature evolution of coronal loops, (2) the overdensity of hot coronal loops, (3) upflows in coronal loops, (4) the Doppler shift in coronal loops, (5) upward propagating waves, (6) the energy balance in coronal loops, (7) the magnetic complexity in the transition region, (8) the altitude of nanoflares and microflares, (9) the cross section of elementary loops, as well as (10) 3D MHD simulations of coronal heating. The phrase ``coronal heating problem'' is therefore a paradoxical misnomer for what should rather be addressed as the ``chromospheric heating problem'' and ``coronal loop filling process.'' This paradigm shift substantially reduces the number of relevant theoretical models for coronal heating in active regions and the quiet Sun, but our arguments do not apply to coronal holes and the extended heliospheric corona.

Aschwanden, Markus J.; Winebarger, Amy; Tsiklauri, David; Peter, Hardi

2007-04-01

444

Ceramic heat recuperators for industrial heat recovery  

Microsoft Academic Search

A cordierite (magnesium aluminum silicate) recuperator was designed for relatively small furnaces with firing rates of 0.3 MM to 0.6 MM Btu\\/h and with exhaust gas temperatures of 1500 F to 2600 F. Five demonstration programs were performed to determine the heat transfer performance of the device, establish the energy savings by recovery, demonstrate the durability of the ceramic core,

J. J. Cleveland; J. M. Gonzalez; K. H. Kohnken; W. J. Rebello

1980-01-01

445

FPD plasma heating systems  

SciTech Connect

Tandem mirror devices rely on a number of plasma heating systems to create and maintain potential and density profiles which axially confine the central cell and provide MHD stability. The Fusion Power Demonstrator (FPD) tandem mirror study was carried out in three stages, each facility was configured with a slightly different mission and set of constraints. Although the heating system requirements varied in the three stages, the potential peak and thermal barrier ECRH systems and the sloshing ion neutral beam system were common elements of the configurations. The heating systems' requirements, the design approach, and the systems' description are presented.

Freije, S.A.

1985-07-01

446

Stirling engine heating system  

SciTech Connect

A hot gas engine is described wherein a working gas flows back and forth in a closed path between a relatively cooler compression cylinder side of the engine and a relatively hotter expansion cylinder side of the engine and the path contains means including a heat source and a heat sink acting upon the gas in cooperation with the compression and expansion cylinders to cause the gas to execute a thermodynamic cycle wherein useful mechanical output power is developed by the engine, the improvement in the heat source which comprises a plurality of individual tubes each forming a portion of the closed path for the working gas.

Johansson, L.N.; Houtman, W.H.; Percival, W.H.

1988-06-28

447

Heat storage system adapted for incongruently melting heat storage materials and congruently melting heat storage materials  

Microsoft Academic Search

A heat storage article adapted for prevention of stratification of incongruently melting heat storage materials, such as eutectic salts, and adapted for use with congruently melting heat storage materials, such as paraffins. The article is comprised of a concrete stone composition, a certain portion of which is comprised of metallic heat transfer materials in order to increase heat transfer through

Schoenfelder

1980-01-01

448

Inner heat source model with heat and moisture transfer in soil around the underground heat exchanger  

Microsoft Academic Search

This paper presents an inner heat source model of underground heat exchanger based on the heat and mass transfer theory in soil. A number of factors such as moisture movement in soil, soil type, and soil property were taken into account in the model. The underground heat exchanger was simplified as the equivalent inner heat source term in the model.

Xinguo Li; Jun Zhao; Qian Zhou

2005-01-01

449

Innovation: the induction heated screw.  

National Technical Information Service (NTIS)

The Research and Development Division at EDF has developed an original technique for heating, drying or baking powder products: the induction heated Archimedes screw. Its main characteristic is simultaneous heating of the screw and the sleeve. (author). 4...

B. Paya

1993-01-01

450

Measuring the Heats of Water.  

ERIC Educational Resources Information Center

|Uses common equipment (tea kettle and vacuum bottles) to precisely measure the specific heat, latent heat of fusion, and latent heat of vaporization of water. Provides descriptions for all three experiments. (MVL)|

Hunt, James L.; Tegart, Tracy L.

1994-01-01

451

Measuring the Heats of Water.  

ERIC Educational Resources Information Center

Uses common equipment (tea kettle and vacuum bottles) to precisely measure the specific heat, latent heat of fusion, and latent heat of vaporization of water. Provides descriptions for all three experiments. (MVL)

Hunt, James L.; Tegart, Tracy L.

1994-01-01

452

Heat Exhaustion, First Aid  

MedlinePLUS

... illness. Heat illness occurs when a person's core body temperature rises above a safe level of the body's ... or all of the following symptoms: A high body temperature (above 102° F) Skin that is red and ...

453

Heat Cramps, First Aid  

MedlinePLUS

... illness. Heat illness occurs when a person's core body temperature rises above a safe level of the body's ... or all of the following symptoms: A high body temperature (above 102° F) Skin that is red and ...

454

Heat leak measurements facility  

SciTech Connect

Heat leak measurements of superconducting magnet suspension systems, and multilayer insulation (MLI) systems are important for the optimum design of magnet cryostats. For this purpose, a cryogenic test facility was developed having a versatile functional end in which test components of differing geometrical configurations can be installed and evaluated. This paper details the test facility design and operating parameters. Experimental results of heat leak measurements to 4.5 K obtained on a post type support system having heat intercepts at 10 K and 80 K are presented. Included are measurements obtained while operating the 10 K intercept at temperatures above 10 K, i.e., in the 10-40 K range. Also reported is a description of the test facility conversion for a heat load study of several MLI systems with variations of MLI installation technique. The results of the first MLI system tested are presented.

Gonczy, J.D.; Kuchnir, M.; Nicol, T.H.; Niemann, R.C.; Powers, R.J.

1985-09-01

455

Understanding heat exchanger systems  

SciTech Connect

Many of the complaints heard about steam heat exchangers--water hammer, corrosion, and freezing--often are not caused by the unit itself but, rather, are problems within the system. Diagnosing and overcoming problems in existing systems or designing new ones properly requires a thorough understanding not only of the heat exchanger, but all of the components that make up the overall system. Many types of heat exchangers are available today (shell-and-tube, plate-and-frame, coil, tank heaters, and plate coils). The same basic principles and similar controls apply to all. Although the examples in this article consider the shell-and-tube style, the concepts apply to all types of steam heat exchangers.

Hughes, B. [ITT Fluid Technology, Guelph, Ontario (Canada)

1997-04-01

456

Climate Wisconsin: Extreme Heat  

NSDL National Science Digital Library

This short video addresses the effects of heat waves on human populations, with African American residents of Milwaukee, Wisconsin, as the visual subjects. The narrative is done by a young spoken- word artist.

Board, Wisconsin E.; Wisconsin, Climate

457

Greywater Heat Exchanger.  

National Technical Information Service (NTIS)

A kilowatt meter and water meter were installed to monitor pregreywater usage. The design considerations, the heat exchanger construction and installation, and the monitoring of usage levels are described. (ERA citation 09:040361)

D. Holmberg

1983-01-01

458

Greywater heat exchanger  

SciTech Connect

A kilowatt meter and water meter were installed to monitor pregreywater usage. The design considerations, the heat exchanger construction and installation, and the monitoring of usage levels are described.

Holmberg, D.

1983-11-21

459

Composite heat damage assessment  

SciTech Connect

The effects of heat damage were determined on the residual mechanical, physical, and chemical properties of IM6/3501-6 laminates, and potential nondestructive techniques to detect and assess material heat damage were evaluated. About one thousand preconditioned specimens were exposed to elevated temperatures, then cooled to room temperature and tested in compression, flexure, interlaminar shear, shore-D hardness, weight loss, and change in thickness. Specimens experienced significant and irreversible reduction in their residual properties when exposed to temperatures exceeding the material upper service temperature of this material (350{degrees}F). The Diffuse Reflectance Infrared Fourier Transform and Laser-Pumped Fluorescence techniques were found to be capable of rapid, in-service, nondestructive detection and quantitation of heat damage in IM6/3501- 6. These techniques also have the potential applicability to detect and assess heat damage effects in other polymer matrix composites.

Janke, C.J.; Wachter, E.A. [Oak Ridge National Lab., TN (United States); Philpot, H.E. [Oak Ridge K-25 Site, TN (United States); Powell, G.L. [Oak Ridge Y-12 Plant, TN (United States)

1993-12-31

460

Investment casting heat transfer  

NSDL National Science Digital Library

Calculate temperature profile and Biot number in mixed conduction and convection/radiation heat transfer from liquid metal through a ceramic mold to the environment, and suggest a design change to reduce the probability of shattering due to thermal stress.

Powell, Adam C., IV

2004-12-15

461

Pipe Heat Transfer Calculation.  

National Technical Information Service (NTIS)

This citation summarizes a one-page announcement of technology available for utilization. Underground heat distribution systems for a complex of buildings have been widely used in the United States for the past several decades. Only recently underground c...

1983-01-01

462

Apply the Heat Chart  

Center for Food Safety and Applied Nutrition (CFSAN)

Text VersionPage 1. Apply the Heat Chart * With a 3 minute rest time. Refrigerator Temperatures Freezer Temperatures Poultry, Stuffing ... More results from www.fda.gov/downloads/food/foodborneillnesscontaminants

463

NGNP Process Heat Utilization: Liquid Metal Phase Change Heat Exchanger  

SciTech Connect

One key long-standing issue that must be overcome to fully realize the successful growth of nuclear power is to determine other benefits of nuclear energy apart from meeting the electricity demands. The Next Generation Nuclear Plant (NGNP) will most likely be producing electricity and heat for the production of hydrogen and/or oil retrieval from oil sands and oil shale to help in our national pursuit of energy independence. For nuclear process heat to be utilized, intermediate heat exchange is required to transfer heat from the NGNP to the hydrogen plant or oil recovery field in the most efficient way possible. Development of nuclear reactor - process heat technology has intensified the interest in liquid metals as heat transfer media because of their ideal transport properties. Liquid metal heat exchangers are not new in practical applications. An important rational for considering liquid metals is the potential convective heat transfer is among the highest known. Thus explains the interest in liquid metals as coolant for intermediate heat exchange from NGNP. For process heat it is desired that, intermediate heat exchangers (IHX) transfer heat from the NGNP in the most efficient way possible. The production of electric power at higher efficiency via the Brayton Cycle, and hydrogen production, requires both heat at higher temperatures and high effectiveness compact heat exchangers to transfer heat to either the power or process cycle. Compact heat exchangers maximize the heat transfer surface area per volume of heat exchanger; this has the benefit of reducing heat exchanger size and heat losses. High temperature IHX design requirements are governed in part by the allowable temperature drop between the outlet and inlet of the NGNP. In order to improve the characteristics of heat transfer, liquid metal phase change heat exchangers may be more effective and efficient. This paper explores the overall heat transfer characteristics and pressure drop of the phase change heat exchanger with Na as the heat exchanger coolant. In order to design a very efficient and effective heat exchanger one must optimize the design such that we have a high heat transfer and a lower pressure drop, but there is always a trade-off between them. Based on NGNP operational parameters, a heat exchanger analysis with the sodium phase change will be presented to show that the heat exchanger has the potential for highly effective heat transfer, within a small volume at reasonable cost.

Piyush Sabharwall; Mike Patterson; Vivek Utgikar; Fred Gunnerson

2008-09-01

464

Geo-heat center  

SciTech Connect

A summary is presented of the Geo-Heat Center from its origin in 1974. The GHC has been involved in a number of studies and projects. A few of these are: construction of a greenhouse based on geothermal applications, an aquaculture project raising freshwater Malaysian prawns, an investigation of ground water characteristics and corrosion problems associated with the use of geothermal waters, and the assessment of the potential utilization of direct-heat applications of geothermal energy for an agribusiness.

Lienau, P.J.; Fornes, A.O.

1983-01-01

465

Heat storage technology update  

Microsoft Academic Search

One way to reduce vehicle cold-start emissions of unburned fuel is to reduce catalyst light-off time. The U.S. Environmental Protection Agency (EPA) has evaluated several electrically heated catalyst (EHC) technologies with favorable results at ambient temperatures of 24C and [minus]7C. The resistive heating elements reduce the time during which the catalyst remains ineffective because of insufficient warming by the cold

K. H. Hellman; G. K. Piotrowski; R. M. Schaefer

1993-01-01

466

Heat Preservation and Processing  

Microsoft Academic Search

\\u000a Of the various means of preserving foods, the use of heat finds very wide application. The simple acts of cooking, frying,\\u000a broiling, or otherwise heating foods prior to consumption are forms of food preservation. In addition to making foods more\\u000a tender and palatable, cooking destroys a large proportion of the microorganisms and natural enzymes in foods; thus, cooked\\u000a foods generally

Dennis R. Heldman

467

Solar heating and cooling.  

PubMed

Solar energy is discussed as an energy resource that can be converted into useful energy forms to meet a variety of energy needs. The review briefly explains the nature of this energy resource, the kinds of applications that can be made useful, and the status of several systems to which it has been applied. More specifically, information on solar collectors, solar water heating, solar heating of buildings, solar cooling plus other applications, are included. PMID:1010737

Duffie, J A

1976-01-01

468

Visualization of heat transfer  

NASA Astrophysics Data System (ADS)

A survey of recently published papers which describe new experimental methods for heat transfer visualization or the application of such methods for investigating heat transfer problems is presented. The study of surface flow patterns and wall temperature by the oil-flow technique, the naphthalene sublimation technique, and temperature-sensitive paints is considered. The use of tracer materials to visualize the flow field is discussed, and optical methods of visualizing the field are described, presenting photographic illustrations.

Merzkirch, W.

469

Freezable heat pipe  

DOEpatents

A heat pipe whose fluid can be repeatedly frozen and thawed without damage to the casing. An additional part is added to a conventional heat pipe. This addition is a simple porous structure, such as a cylinder, self-supporting and free standing, which is dimensioned with its diameter not spanning the inside transverse dimension of the casing, and with its length surpassing the depth of maximum liquid.

Ernst, Donald M. (Leola, PA); Sanzi, James L. (Lancaster, PA)

1981-02-03

470

Microtube Strip Heat Exchanger  

SciTech Connect

Doty Scientific (DSI) believes their Microtube-Strip Heat Exchanger will contribute significantly to (a) the closed Brayton cycles being pursued at MIT, NASA, and elsewhere; (b) reverse Brayton cycle cryocoolers, currently being investigated by NASA for space missions, being applied to MRI superconducting magnets; and (c) high-efficiency cryogenic gas separation schemes for CO{sub 2} removal from exhaust stacks. The goal of this current study is to show the potential for substantial progress in high-effectiveness, low-cost, gas-to-gas heat exchangers for diverse applications at temperatures from below 100 K to above 1000 K. To date, the highest effectiveness measured is about 98%, and relative pressure drops below 0.1% with a specific conductance of about 45 W/kgK are reported. During the pre-award period DSI built and tested a 3-module heat exchanger bank using 103-tube microtube strip (MTS) modules. To add to their analytical capabilities, DSI has acquired computational fluid dynamics (CFD) software. This report describes the pre-award work and the status of the ten tasks of the current project, which are: analyze flow distribution and thermal stresses within individual modules; design a heat exchanger bank of ten modules with 400 microtube per module; obtain production quality tubestrip die and AISI 304 tubestrips; obtain production quality microtubing; construct revised MTS heat exchanger; construct dies and fixtures for prototype heat exchanger; construct 100 MTS modules; assemble 8-10 prototype MTS heat exchangers; test prototype MTS heat exchanger; and verify test through independent means. 7 refs., 9 figs. 1 tab. (CK)

Doty, F.D.

1990-12-27

471

HEAT OF HYDRATION OF SALTSTONE MIXES-MEASUREMENT BY ISOTHERMAL CALORIMETRY  

SciTech Connect

This report provides initial results on the measurement of heat of hydration of Saltstone mixes using isothermal calorimetry. The results were obtained using a recently purchased TAM Air Model 3116 Isothermal Conduction Calorimeter. Heat of hydration is an important property of Saltstone mixes. Greater amounts of heat will increase the temperature of the curing mix in the vaults and limit the processing rate. The heat of hydration also reflects the extent of the hydraulic reactions that turn the fluid mixture into a ''stone like'' solid and consequently impacts performance properties such as permeability. Determining which factors control these reactions, as monitored by the heat of hydration, is an important goal of the variability study. Experiments with mixes of portland cement in water demonstrated that the heats measured by this technique over a seven day period match very well with the literature values of (1) seven day heats of hydration using the standard test method for heat of hydration of hydraulic cement, ASTM C 186-05 and (2) heats of hydration measured using isothermal calorimetry. The heats of hydration of portland cement or blast furnace slag in a Modular Caustic Side Solvent Extraction Unit (MCU) simulant revealed that if the cure temperature is maintained at 25 C, the amount of heat released over a seven day period is roughly 62% less than the heat released by portland cement in water. Furthermore, both the blast furnace slag and the portland cement were found to be equivalent in heat production over the seven day period in MCU. This equivalency is due to the activation of the slag by the greater than 1 Molar free hydroxide ion concentration in the simulant. Results using premix (a blend of 10% cement, 45% blast furnace slag, and 45% fly ash) in MCU, Deliquification, Dissolution and Adjustment (DDA) and Salt Waste Processing Facility (SWPF) simulants reveal that the fly ash had not significantly reacted (undergone hydration reactions) after seven days (most likely less than 5%). There were clear differences in the amount of heat released and the peak times of heat release for the three different simulants. It turns out that SWPF simulant mixes give off greater heat than does MCU and DDA simulant mixes. The temperature dependence of the heat of hydration was measured by carrying out these measurements at 25, 40 and 55 C. In general, the peak times shifted to shorter times as the isothermal temperature increased and the amount of heat released was independent of temperature for DDA and MCU but slightly higher at higher temperatures for SWPF. The goal of this study is to apply this technique to the measurement of the heat of hydration of mixes that will be made as part of the variability study. It is important to understand which variables will impact (and to what extent) the amount of heat generated and the peak times for the heat release. Those variables that can be controlled can then be tuned to adjust the heat of hydration as long as the other properties are still acceptable. The first application of heat of hydration measurements to the variability study was completed and the results presented in this report. These measurements were made using Phase VI mixes (SWPF simulants) following a statistical design that included variation in the compositional and operational variables. Variation in both the amount of heat released and the peak times for the heat release were observed. The measured ranges were 23 Joules per gram of premix for the heat release and 23 hours for the peak time of heat release at 25 C. Linear models with high R{sup 2} values and no statistical evidence for lack of fit were developed that relate the amount of heat release and the peak time for heat release for the Phase VI mixes to certain variables. The amount of heat released was a function of the aluminate and portland cement concentrations as well as the temperature of mixing. The peak time for heat release was a function of aluminate, portland cement and total nitrate plus nitrite concentrations. A comparison was made of the mea

Harbour, J; Vickie Williams, V; Tommy Edwards, T

2007-07-02

472

Convective heat flow probe  

DOEpatents

A convective heat flow probe device is provided which measures heat flow and fluid flow magnitude in the formation surrounding a borehole. The probe comprises an elongate housing adapted to be lowered down into the borehole; a plurality of heaters extending along the probe for heating the formation surrounding the borehole; a plurality of temperature sensors arranged around the periphery of the probe for measuring the temperature of the surrounding formation after heating thereof by the heater elements. The temperature sensors and heater elements are mounted in a plurality of separate heater pads which are supported by the housing and which are adapted to be radially expanded into firm engagement with the walls of the borehole. The heat supplied by the heater elements and the temperatures measured by the temperature sensors are monitored and used in providing the desired measurements. The outer peripheral surfaces of the heater pads are configured as segments of a cylinder and form a full cylinder when taken together. A plurality of temperature sensors are located on each pad so as to extend along the length and across the width thereof, with a heating element being located in each pad beneath the temperature sensors. An expansion mechanism driven by a clamping motor provides expansion and retraction of the heater pads and expandable packer-type seals are provided along the probe above and below the heater pads.

Dunn, James C. (Albuquerque, NM); Hardee, Harry C. (Albuquerque, NM); Striker, Richard P. (Albuquerque, NM)

1985-01-01

473

Convective heat flow probe  

DOEpatents

A convective heat flow probe device is provided which measures heat flow and fluid flow magnitude in the formation surrounding a borehole. The probe comprises an elongate housing adapted to be lowered down into the borehole; a plurality of heaters extending along the probe for heating the formation surrounding the borehole; a plurality of temperature sensors arranged around the periphery of the probe for measuring the temperature of the surrounding formation after heating thereof by the heater elements. The temperature sensors and heater elements are mounted in a plurality of separate heater pads which are supported by the housing and which are adapted to be radially expanded into firm engagement with the walls of the borehole. The heat supplied by the heater elements and the temperatures measured by the temperature sensors are monitored and used in providing the desired measurements. The outer peripheral surfaces of the heater pads are configured as segments of a cylinder and form a full cylinder when taken together. A plurality of temperature sensors are located on each pad so as to extend along the length and across the width thereof, with a heating element being located in each pad beneath the temperature sensors. An expansion mechanism driven by a clamping motor provides expansion and retraction of the heater pads and expandable packet-type seals are provided along the probe above and below the heater pads.

Dunn, J.C.; Hardee, H.C.; Striker, R.P.

1984-01-09

474

Understand spiral heat exchangers  

SciTech Connect

Shell-and-tube heat exchangers are standard in most chemical process industries (CPI) applications. However, they do have limitations related to thermal efficiency, mechanical design, and maintenance requirements that will not allow the standard straight-tube fixed-tubesheet shell-and-tube (S and T) heat exchanger to work properly in certain applications. It is in these problem areas that spiral heat exchangers (SHEs) have been used successfully worldwide for over 60 years. The SHE can be a viable alternative to the complex and often expensive shell-and-tube heat exchanger. The SHEs' unique spiral countercurrent monochannel design gives them exceptionally high heat-transfer rates and low fouling tendencies. The mechanical configuration of the SHE also allows full access to all heat-transfer surfaces for simplified inspection, maintenance, and cleaning. This article describes how SHEs operate, discusses their advantages in terms of thermal efficiency, fouling, mechanical design, and maintenance characteristics, and provides guidance on choosing between spiral and tubular exchangers.

Bailey, K.M.

1994-05-01

475

Intrinsically irreversible heat engine  

DOEpatents

A class of heat engines based on an intrinsically irreversible heat transfer process is disclosed. In a typical embodiment the engine comprises a compressible fluid that is cyclically compressed and expanded while at the same time being driven in reciprocal motion by a positive displacement drive means. A second thermodynamic medium is maintained in imperfect thermal contact with the fluid and bears a broken thermodynamic symmetry with respect to the fluid. The second thermodynamic medium is a structure adapted to have a low fluid flow impedance with respect to the compressible fluid, and which is further adapted to be in only moderate thermal contact with the fluid. In operation, thermal energy is pumped along the second medium due to a phase lag between the cyclical heating and cooling of the fluid and the resulting heat conduction between the fluid and the medium. In a preferred embodiment the engine comprises an acoustical drive and a housing containing a gas which is driven at a resonant frequency so as to be maintained in a standing wave. Operation of the engine at acoustic frequencies improves the power density and coefficient of performance. The second thermodynamic medium can be coupled to suitable heat exchangers to utilize the engine as a simple refrigeration device having no mechanical moving parts. Alternatively, the engine is reversible in function so as to be utilizable as a prime mover by coupling it to suitable sources and sinks of heat.

Wheatley, J.C.; Swift, G.W.; Migliori, A.

1984-01-01

476

Intrinsically irreversible heat engine  

DOEpatents

A class of heat engines based on an intrinsically irreversible heat transfer process is disclosed. In a typical embodiment the engine comprises a compressible fluid that is cyclically compressed and expanded while at the same time being driven in reciprocal motion by a positive displacement drive means. A second thermodynamic medium is maintained in imperfect thermal contact with the fluid and bears a broken thermodynamic symmetry with respect to the fluid. The second thermodynamic medium is a structure adapted to have a low fluid flow impedance with respect to the compressible fluid, and which is further adapted to be in only moderate thermal contact with the fluid. In operation, thermal energy is pumped along the second medium due to a phase lag between the cyclical heating and cooling of the fluid and the resulting heat conduction between the fluid and the medium. In a preferred embodiment the engine comprises an acoustical drive and a housing containing a gas which is driven at a resonant frequency so as to be maintained in a standing wave. Operation of the engine at acoustic frequencies improves the power density and coefficient of performance. The second thermodynamic medium can be coupled to suitable heat exchangers to utilize the engine as a simple refrigeration device having no mechanical moving parts. Alternatively, the engine is reversible in function so as to be utilizable as a prime mover by coupling it to suitable sources and sinks of heat. 11 figs.

Wheatley, J.C.; Swift, G.W.; Migliori, A.

1984-12-25

477

Radial flow heat exchanger  

DOEpatents

A radial flow heat exchanger (20) having a plurality of first passages (24) for transporting a first fluid (25) and a plurality of second passages (26) for transporting a second fluid (27). The first and second passages are arranged in stacked, alternating relationship, are separated from one another by relatively thin plates (30) and (32), and surround a central axis (22). The thickness of the first and second passages are selected so that the first and second fluids, respectively, are transported with laminar flow through the passages. To enhance thermal energy transfer between first and second passages, the latter are arranged so each first passage is in thermal communication with an associated second passage along substantially its entire length, and vice versa with respect to the second passages. The heat exchangers may be stacked to achieve a modular heat exchange assembly (300). Certain heat exchangers in the assembly may be designed slightly differently than other heat exchangers to address changes in fluid properties during transport through the heat exchanger, so as to enhance overall thermal effectiveness of the assembly.

Valenzuela, Javier (Hanover, NH)

2001-01-01

478

Moist Heat or Dry Heat for Delayed Onset Muscle Soreness  

PubMed Central

Background Heat is commonly used in physical therapy following exercise induced delayed onset muscle soreness (DOMS). Most heat modalities used in a clinical setting for DOMS are only applied for 5 to 20 minutes. This minimal heat exposure causes little, if any, change in deep tissue temperature. For this reason, long duration dry chemical heat packs are used at home to slowly and safely warm tissue and reduce potential heat damage while reducing pain associated from DOMS. Clinically, it has been shown that moist heat penetrates deep tissue faster than dry heat. Therefore, in home use chemical moist heat may be more efficacious than dry heat to provide pain relief and reduce tissue damage following exercise DOMS. However, chemical moist heat only lasts for 2 hours compared to the 8 hours duration of chemical dry heat packs. The purpose of this study was to compare the beneficial effect of dry heat versus moist heat on 100 young subjects after exercise induce DOMS. Methods One hundred subjects exercised for 15 minutes accomplishing squats. Before and for 3 days after, strength, muscle soreness, tissue resistance, and the force to passively move the knee were recorded. Heat and moist heat were applied in different groups either immediately after exercise or 24 hours later. Results The research results of this study showed that immediate application of heat, either dry (8 hours application) or moist (2 hours application), had a similar preservation of quadriceps muscle strength and muscle activity. Results also revealed that the greatest pain reduction was shown after immediate application of moist heat. Never the less, immediate application of dry heat had a similar effect but to a lesser extent. Conclusion It should be noted that moist heat had not only similar benefits of dry heat but in some cases enhanced benefits, and with only 25% of the time of application of the dry heat.

Petrofsky, Jerrold; Berk, Lee; Bains, Gurinder; Khowailed, Iman Akef; Hui, Timothy; Granado, Michael; Laymon, Mike; Lee, Haneul

2013-01-01

479

Heat Transfer Augmentation in a Compact Heat Exchange Pedestal Array.  

National Technical Information Service (NTIS)

A compact heat exchanger pedestal array for augmenting heat transfer in a machine is disclosed. The compact heat exchanger pedestal array includes a wall having first and second surfaces. The first surface faces a heated flow path and the second surface p...

C. R. Joe P. M. Lutjen

2004-01-01

480

Investigation of waste heat recovery utilizing fluidized bed heat exchangers  

Microsoft Academic Search

An experimental and analytical investigation was conducted to evaluate the economic potential of shallow fluidized bed heat exchangers to recover the waste heat in the exhaust gases from large diesel engines. The program involved: (1) experiments to measure the heat transfer, pressure loss, and fouling characteristics of a commercially available shallow fluidized bed heat exchanger, and (2) conceptual design of

1978-01-01

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