Note: This page contains sample records for the topic joule heating from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: August 15, 2014.
1

Joule-Thomson heat exchanger and cryostat  

SciTech Connect

This patent describes a refrigerator of the type wherein a fluid is passed through the high pressure tube of a heat exchanger and then expanded through a Joule-Thomson orifice to produce refrigeration proximate the Joule-Thomson orifice. The improvement described here comprises: fibrous material disposed in the Joule-Thomson orifice which is deformed to fix the fibrous material in place, whereby the fibrous material and deformed orifice result in an orifice with large flow impedance.

Steyert, W.A.

1987-03-31

2

Optimal joule heating of the subsurface  

DOEpatents

A method for simultaneously heating the subsurface and imaging the effects of the heating. This method combines the use of tomographic imaging (electrical resistance tomography or ERT) to image electrical resistivity distribution underground, with joule heating by electrical currents injected in the ground. A potential distribution is established on a series of buried electrodes resulting in energy deposition underground which is a function of the resistivity and injection current density. Measurement of the voltages and currents also permits a tomographic reconstruction of the resistivity distribution. Using this tomographic information, the current injection pattern on the driving electrodes can be adjusted to change the current density distribution and thus optimize the heating. As the heating changes conditions, the applied current pattern can be repeatedly adjusted (based on updated resistivity tomographs) to affect real time control of the heating.

Berryman, James G. (Danville, CA); Daily, William D. (Livermore, CA)

1994-01-01

3

Optimal joule heating of the subsurface  

DOEpatents

A method for simultaneously heating the subsurface and imaging the effects of the heating is disclosed. This method combines the use of tomographic imaging (electrical resistance tomography or ERT) to image electrical resistivity distribution underground, with joule heating by electrical currents injected in the ground. A potential distribution is established on a series of buried electrodes resulting in energy deposition underground which is a function of the resistivity and injection current density. Measurement of the voltages and currents also permits a tomographic reconstruction of the resistivity distribution. Using this tomographic information, the current injection pattern on the driving electrodes can be adjusted to change the current density distribution and thus optimize the heating. As the heating changes conditions, the applied current pattern can be repeatedly adjusted (based on updated resistivity tomographs) to affect real time control of the heating.

Berryman, J.G.; Daily, W.D.

1994-07-05

4

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

5

Joule Heating and Nitric Oxide in the Thermosphere  

NASA Astrophysics Data System (ADS)

The density of nitric oxide at 150 km may be used as an indicator of Joule heating in the thermosphere. The chemical reaction between nitrogen atoms (ground state) and molecular oxygen that produces nitric oxide at this altitude is very sensitive to temperature. During a Joule heating event the temperature of the thermosphere increases by 50 to 100 K leading to an increase in the nitric oxide density by a factor of two. The density distribution of nitric oxide has been studied for a Joule heating event that occurred on September 25, 1998. The global distribution of nitric oxide density was measured from a limb-scanning instrument on the SNOE polar orbiting satellite. On September 22, electrons began to precipitate into the thermosphere causing an increase in the nitric oxide density at 110 km at auroral latitudes. On September 24, as the result of Joule heating the nitric oxide density at 150 km began to increase reaching a maximum on September 25. The increased nitric oxide density extended equatorward from auroral latitudes to 20 degrees latitude. The 150 km nitric oxide density decreased on September 26 and was back to normal levels by September 28. The electron precipitation reached its maximum on September 26 and continued through September 28. The comparison of the observed nitric oxide with model calculations of the altitude distribution of nitric oxide clearly showed the increased nitric oxide produced by Joule heating. The increased nitric oxide at 150 km was used as an indicator of Joule heating for a 935-day period from March 1998 to September 2000. Increased nitric oxide at 110 km was used as an indicator of electron precipitation for this same period. It was found that the seasonal behavior of Joule heating and electron precipitation differ, with electron precipitation events occurring more frequently during the winter seasons and Joule heating events occurring more frequently during the summer seasons.

Barth, C. A.; Bailey, S. M.; Lu, G.; Baker, D. N.

2005-12-01

6

Latitudinal variations of joule heating due to the auroral electrojets  

SciTech Connect

Empirical scaling factors between the height-integrated joule heating rate deduced from measurements of the Chatanika incoherent scatter radar and the square of magnetic perturbation at College are derived. These relationships, calculated for different situations (the eastward and westward electrojects and daytime) are then used to estimate the joule heating rate along the latitudinal extent of the auroral oval on the basis of magnetometer data from the IMS Alaska meridian chain of observations. The total heat input for a disturbed day (April 12, 1978) is estimated to be 2.8 x 10/sup 15/ J.

Duboin, M.; Kamide, Y.

1984-01-01

7

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

8

Postfabrication Electrical Trimming of Silicon Micromechanical Resonators via Joule Heating  

Microsoft Academic Search

This paper presents a method to electrically trim the resonance frequency of a silicon bulk acoustic resonator (SiBAR) after its fabrication is completed. The small volume of the mi- croresonator can be Joule heated to a sufficiently high temperature to allow for diffusion of deposited metals from its surface onto its bulk. Such high temperatures also facilitate the formation of

Ashwin K. Samarao; Farrokh Ayazi

2011-01-01

9

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

10

Ionospheric Joule Heating under the influence of Corotating Interaction Regions  

NASA Astrophysics Data System (ADS)

During the declining phase of the solar cycle, the dominant solar phenomenon affecting geomagnetic activity is coronal holes. High-speed solar winds emanate from those and when high-speed streams overtake slow-speed streams, plasma and magnetic field compressions take place. The intense compressed magnetic field regions are called corotating interaction regions, CIRs. When CIRs impinge upon the Earth's magnetosphere, they can cause geomagnetic disturbances. It has been claimed that though the average energy input rate into the magnetosphere and ionosphere during CIR intervals is not great, their long duration might cause the total energy input in the magnetosphere-ionosphere system to become even greater than during sunspot maximum conditions. The main energy input mechanism to the ionosphere is Joule heating. We have used the unique EISCAT-radar one-month measurements in March 2006 to derive the local ionospheric electric fields and Pedersen conductances. From those, the ionospheric Joule heating rates have been calculated (the possible effect of neutral winds was neglected). During the studied period, at least six several days long CIR regions were identified from the ACE-satellite data. We show that the Joule heating rate was most of the time very small and the result doesn't support the idea of large total energy input rate to the ionosphere. We also study the relationship between the Joule heating rate and the AE index as well as the local magnetic X-component. The results show that the generally used proxies are not well valid in individual events.

Aikio, Anita; Kauristie, Kirsti; Selkälä, Anne

11

Miniature Joule - Thomson liquefier with sintered heat exchanger  

NASA Astrophysics Data System (ADS)

Conventional Joule-Thomson refrigerators are made with finned, capillary tubing for the heat exchanger and a throttling valve for reducing the pressure [1]. A new kind of recuperative miniature heat-exchanger can be developed if a powder metallurgy technology is used. A high pressure capillary tube is sintered with metal powder. The grains of metal should be ball shaped or similar. In result of sintering process a good thermal contact between an outside tube surface and powder grains is achieved. The heat exchange surface is well developed and a porous sinter acts as a low pressure gas canal.

Eugeniusz, Bodio; Maciej, Chorowski; Marta, Wilczek; Arkadiusz, Bozek

12

Survey of Thermosphere Joule Heating Locations and Magnetic Disturbance Conditions  

NASA Astrophysics Data System (ADS)

Neutral density enhancements as evidence of Joule heating in the thermosphere are frequently observed in the polar cusp. Neutral density enhancements are usually investigated for selected magnetic storm events and certain disturbed magnetic conditions. A different approach is taken in this study. We first conducted a systematic survey of thermosphere heating events using the available CHAMP, GRACE and SETA accelerometer data and then examined their occurrence locations and magnetic disturbance conditions. CHAMP and GRACE data together cover ten years period from 2001 to 2010 at 300 - 500 km altitudes. SETA data are from accelerometers on sun-synchronous, low altitude satellites covering the 170-280 km altitude region during 1982 and 1983. In addition locations of intense energy deposition of Poynting fluxes observed by DMSP satellites during 2001-2005 are used to compare distributions of the neutral density hot spots. The survey indicates that neutral density enhancements were detected not only near the polar cusp but also occasionally in the polar cap region. They were observed over a wide range of magnetic activity. Large Joule heating appears to occur preferentially in the morning sector and the summer hemisphere. The results are discussed for better understanding thermospheric responses of magnetospheric energy transfer and ionospheric heating by field-aligned currents.

Lin, C. S.; Knipp, D.; Marcos, F.; Cable, S. B.; Sutton, E. K.

2011-12-01

13

Heat capacities and Joule-Thomson coefficients of HFC refrigerants  

SciTech Connect

In this report, the authors have examined the behavior of heat capacities and Joule-Thomson coefficients in low- and moderate-density regions based on recent theoretical studies of the ideal-gas heat capacity and virial coefficients of R-32, R-125, R-134a, r-143a, and R-152a. The results have been compared with those derived from empirical equations of state which have been recently developed, based on a large quantity of experimental data for these refrigerants. Both results are in good agreement. Proper behaviors for these second-derivative properties justify the use of the empirical equations of state in low-temperature and low-density regions where no experimental data are available.

Yokozeki, A.; Sato, H.; Watanabe, K. [Keio Univ., Yokohama (Japan). Dept. of System Design Engineering] [Keio Univ., Yokohama (Japan). Dept. of System Design Engineering

1999-01-01

14

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

15

Refractory electrodes for joule heating and methods of using same  

DOEpatents

A certain group of electrically conductive refractory materials presently known for use in high temperature applications as throat constructions, melter sidewalls, forehearth, stacks, port sills, hot face lining for slagging coal gasifiers, slag runners, and linings for nuclear waste encapsulation furnaces may be used as electrodes permitting joule heating at temperatures in excess of 1,200 C in excess of about 4400 hours even in the presence of transition group element(s). More specifically, the invention is an electrode for melting earthen materials, wherein the electrode is made from an electrically conductive refractory material, specifically at least one metal oxide wherein the metal is selected from the group consisting of chrome, ruthenium, rhodium, tin and combinations thereof. 2 figs.

Lamar, D.A.; Chapman, C.C.; Elliott, M.L.

1998-05-12

16

Refractory electrodes for joule heating and methods of using same  

DOEpatents

A certain group of electrically conductive refractory materials presently known for use in high temperature applications as throat constructions, melter sidewalls, forehearth, stacks, port sills, hot face lining for slagging coal gasifiers, slag runners, and linings for nuclear waste encapsulation furnaces may be used as electrodes permitting joule heating at temperatures in excess of 1200 C. in excess of about 4400 hours even in the presence of transition group element(s). More specifically, the invention is an electrode for melting earthen materials, wherein the electrode is made from an electrically conductive refractory material, specifically at least one metal oxide wherein the metal is selected from the group consisting of chrome, ruthenium, rhodium, tin and combinations thereof.

Lamar, David A. (West Richland, WA) [West Richland, WA; Chapman, Chris C. (Richland, WA) [Richland, WA; Elliott, Michael L. (Kennewick, WA) [Kennewick, WA

1998-01-01

17

Joule heating of the Jovian ionosphere by corotation enforcement currents  

SciTech Connect

Heat is deposited to the Jovian ionosphere in the course of enforcement of corotation to the outer magnetosphere. The Joule heating rate is estimated for several possible causes of departure from the corotation by making use of a simple model of the magnetodisc. Following compression or expansion of the magnetosphere, the magnetospheric plasma superrotates or subrotates in consequence of conservation of the angular momentum, and thermal energy is deposited in the ionosphere at a rate of the order of 10/sup 12/ W for about 10/sup 5/ s while rotational speed is adjusted toward the corotation with the planet. Outward diffisuion of the Iogenic plasma at a rate of 10/sup 29/ amu/s also causes ionospheric heating at a rate of 10/sup 13/ W as the ionosphere acts to drive the plasma toward the corotation. Day-night asymmetry in trajectory of rotational motion of plasma, owing to asymmetry in configuration of the magnetosphere, is also likely to produce energy dissipation of a similar magnitude as the rotational speed is adjusted continually. Thus the corotation enforcement current deposits as much heat as the dynamo current from Io and plays an important part in energetics and dynamics of the Jovian magnetosphere. The heating rate per unit area of the high-latitude ionosphere is more than approx.10 erg/cm/sup 2/ s, namely, orders of magnitude greater than the rate of the energy supply by the solar UV radiation. These numbers depend on the adopted height-integrated conductivity of 0.1 mho of the Jovian ionosphere.

Nishida, A.; Watanabe, Y.

1981-11-01

18

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

19

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

20

Local and transient structural changes in stratum corneum at high electric fields: Contribution of Joule heating  

Microsoft Academic Search

Electroporation of skin is accompanied by local heating, such that thermally induced structural changes of the stratum corneum (SC) accompany the field effect. Comparing on the time scale, the local changes in structure, temperature and conductance of the SC, during and after the pulse, it is seen that Joule heating also facilitates the subsequent molecular transport. It is found that

U. Pliquett; S. Gallo; S. W. Hui; Ch. Gusbeth; E. Neumann

2005-01-01

21

Diffusion, Fluxes, Friction Forces, and Joule Heating in Two-Temperature Multicomponent Magnetohydrodynamics  

NASA Technical Reports Server (NTRS)

The relationship between Joule heating, diffusion fluxes, and friction forces has been studied for both total and electron thermal energy equations, using general expressions for multicomponent diffusion in two-temperature plasmas with the velocity dependent Lorentz force acting on charged species in a magnetic field. It is shown that the derivation of Joule heating terms requires both diffusion fluxes and friction between species which represents the resistance experienced by the species moving at different relative velocities. It is also shown that the familiar Joule heating term in the electron thermal energy equation includes artificial effects produced by switching the convective velocity from the species velocity to the mass-weighted velocity, and thus should not be ignored even when there is no net energy dissipation.

Chang, C. H.

1999-01-01

22

Selective domain wall depinning by localized Oersted fields and Joule heating  

NASA Astrophysics Data System (ADS)

Using low temperature magnetoresistance measurements, the possibility to selectively move a domain wall locally by applying current pulses through a Au nanowire adjacent to a permalloy element is studied. We find that the domain wall depinning field is drastically modified with increasing current density due to the Joule heating and the Oersted field of the current, and controlled motion due to the Oersted field without any externally applied fields is achieved. By placing the domain wall at various distances from the Au wire, we determine the range of the Joule heating and the Oersted field and both effects can be separated.

Ilgaz, Dennis; Kläui, Mathias; Heyne, Lutz; Boulle, Olivier; Zinser, Fabian; Krzyk, Stephen; Fonin, Mikhail; Rüdiger, Ulrich; Backes, Dirk; Heyderman, Laura J.

2008-09-01

23

Performance evaluation of the recuperative heat exchanger in a miniature Joule–Thomson cooler  

Microsoft Academic Search

To develop effective heat exchangers for miniature and micro-Joule–Thomson (J–T) cooling system, the performance of the recuperative heat exchanger in a miniature J–T cooler is analyzed and evaluated. The evaluation is based on a theoretical model of the Hampson-type counter-flow heat exchanger. The effect of the pressure and temperature-dependent properties and longitudinal heat conduction are considered. The results of the

H. Xue; K. C. Ng; J. B. Wang

2001-01-01

24

Controlled Formation of Zigzag and Armchair Edges in Graphene Nanoribbons by Joule Heating  

SciTech Connect

We demonstrate and monitor an efficient edge reconstruction process, at the atomic scale, for graphite nanoribbons by Joule heating inside an integrated transmission electron microscope equipped with a scanning tunneling stage STM (TEM-STM system). During Joule annealing, sharp edges and step-edge arrays are formed, mostly with either zigzag or armchair edge configurations. Their formation is driven by both thermal and electric field related mechanisms. Model calculations show that the dominant annealing mechanisms involve point defect annealing and edge reconstruction. Joule heating is thus shown to provide an effective way to produce clean zigzag and armchair edges, which could be useful for both fundamental studies of edge reactivity, magnetism, and could provide a route for increasing carrier mobility and for the development of future electronics applications.

Sumpter, Bobby G [ORNL; Dresselhaus, M [Massachusetts Institute of Technology (MIT); Terrones Maldonado, Mauricio [ORNL; Meunier, Vincent [ORNL; Romo Herrera, Jose M [ORNL; Jia, Xiaoting [Massachusetts Institute of Technology (MIT); Hofmann, Mario [Massachusetts Institute of Technology (MIT); Campos-Delgado, Jessica [IPICyT; Reina, Alfonso [Massachusetts Institute of Technology (MIT); Kong, Jing [Massachusetts Institute of Technology (MIT); Hsieh, Ya-Ping [Massachusetts Institute of Technology (MIT); Son, Hyungbin [Massachusetts Institute of Technology (MIT)

2009-01-01

25

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

Microsoft Academic Search

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

Jin-Wu Jiang; Jian-Sheng Wang

2011-01-01

26

Local temperature redistribution and structural transition during joule-heating-driven conductance switching in VO2.  

PubMed

Joule-heating induced conductance-switching is studied in VO2 , a Mott insulator. Complementary in situ techniques including optical characterization, blackbody microscopy, scanning transmission X-ray microscopy (STXM) and numerical simulations are used. Abrupt redistribution in local temperature is shown to occur upon conductance-switching along with a structural phase transition, at the same current. PMID:23868142

Kumar, Suhas; Pickett, Matthew D; Strachan, John Paul; Gibson, Gary; Nishi, Yoshio; Williams, R Stanley

2013-11-13

27

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

Microsoft Academic Search

Joule heating in a slender magnetic flux tube is investigated. The distribution of the magnetic field and electric sheet current encircling a vertical cylindrical magnetic tube is determined by equating the converging magnetic flux, which results from the converging and downward flow of the granulation, and the dissipative expanding magnetic flux due to Ohmic decay. Here, to ensure the mass

T. Hirayama

1992-01-01

28

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

29

Modeling Joule Heating Effect on Lunar O2 Generation via Electrolytic Reduction.  

NASA Technical Reports Server (NTRS)

Kennedy Space Center is leading research work on lunar O2 generation via electrolytic reduction of regolith; the metal oxide present in the regolith is dissociated in oxygen anions and metal cations leading to the generation of gaseous oxygen at the anode and liquid metal at the cathode. Electrical resistance of molten regolith is high, leading to heating of the melt when electrical current is applied between the electrodes (Joule heating). The authors have developed a 3D model using a rigorous approach for two coupled physics (thermal and electrical potential) to not only study the effect of Joule heating on temperature distribution throughout the molten regolith but also to evaluate and optimize the design of the electrolytic cells. This paper presents the results of the thermal analysis performed on the model and used to validate the design of the electrolytic cell.

Dominquez, Jesus; Poizeau, Sophie; Sibille, Laurent

2009-01-01

30

Low-power concentration and separation using temperature gradient focusing via Joule heating.  

PubMed

We present an experimental study of temperature gradient focusing (TGF) exploiting an inherent Joule heating phenomenon. A simple variable-width PDMS device delivers rapid and repeatable focusing of model analytes using significantly lower power than conventional TGF techniques. High electric potential applied to the device induces a temperature gradient within the microchannel due to the channel's variable width, and the temperature-dependent mobility of the analytes causes focusing at a specific location. The PDMS device also shows simultaneous separation and concentration capability of a mixture of two sample analytes in less than 10 min. An experiment combining Joule heating with external heating/cooling further supports the hypothesis that temperature is indeed the dominant factor in achieving focusing with this technique. PMID:17134136

Kim, Sun Min; Sommer, Greg J; Burns, Mark A; Hasselbrink, Ernest F

2006-12-01

31

Breakdown of Richardson's Law in Electron Emission from Individual Self-Joule-Heated Carbon Nanotubes  

PubMed Central

Probing the validity of classical macroscopic physical laws at the nanoscale is important for nanoscience research. Herein, we report on experimental evidence that electron emission from individual hot carbon nanotubes (CNTs) heated by self-Joule-heating does not obey Richardson's law of thermionic emission. By using an in-situ multi-probe measurement technique, electron emission density (J) and temperature (T) of individual self-Joule-heated CNTs are simultaneously determined. Experimental ln(J/T2) ? 1/T plots are found to exhibit an upward bending feature deviating from the straight lines in Richardson plots, and the measured electron emission density is more than one order of magnitude higher than that predicted by Richardson's law. The breakdown of Richardson's law implies a much better electron emission performance of individual CNTs as compared to their macroscopic allotropes and clusters, and the need of new theoretical descriptions of electron emission from individual low-dimensional nanostructures.

Wei, Xianlong; Wang, Sheng; Chen, Qing; Peng, Lianmao

2014-01-01

32

Micro-scale heat-exchangers for Joule-Thomson cooling.  

SciTech Connect

This project focused on developing a micro-scale counter flow heat exchangers for Joule-Thomson cooling with the potential for both chip and wafer scale integration. This project is differentiated from previous work by focusing on planar, thin film micromachining instead of bulk materials. A process will be developed for fabricating all the devices mentioned above, allowing for highly integrated micro heat exchangers. The use of thin film dielectrics provides thermal isolation, increasing efficiency of the coolers compared to designs based on bulk materials, and it will allow for wafer-scale fabrication and integration. The process is intended to implement a CFHX as part of a Joule-Thomson cooling system for applications with heat loads less than 1mW. This report presents simulation results and investigation of a fabrication process for such devices.

Gross, Andrew John

2014-01-01

33

Breakdown of Richardson's Law in Electron Emission from Individual Self-Joule-Heated Carbon Nanotubes.  

PubMed

Probing the validity of classical macroscopic physical laws at the nanoscale is important for nanoscience research. Herein, we report on experimental evidence that electron emission from individual hot carbon nanotubes (CNTs) heated by self-Joule-heating does not obey Richardson's law of thermionic emission. By using an in-situ multi-probe measurement technique, electron emission density (J) and temperature (T) of individual self-Joule-heated CNTs are simultaneously determined. Experimental ln(J/T(2)) - 1/T plots are found to exhibit an upward bending feature deviating from the straight lines in Richardson plots, and the measured electron emission density is more than one order of magnitude higher than that predicted by Richardson's law. The breakdown of Richardson's law implies a much better electron emission performance of individual CNTs as compared to their macroscopic allotropes and clusters, and the need of new theoretical descriptions of electron emission from individual low-dimensional nanostructures. PMID:24869719

Wei, Xianlong; Wang, Sheng; Chen, Qing; Peng, Lianmao

2014-01-01

34

Oxygen Re-adsorption of a Single ZnO Nanobridge by Joule Heating under Ultraviolet Illumination  

NASA Astrophysics Data System (ADS)

Joule heating in ZnO nanowires is known to enhance surface reactions, including oxidation and reduction. The UV sensing behaviors of ZnO nanobridges were investigated in air and Ar ambient to study the effects of Joule heating caused by the absorption of oxygen molecules. When placed under UV illumination in air ambient, the conductance of the ZnO nanobridge decreased over a specific voltage range, while the conductance increased under similar conditions when placed in Ar ambient. Our results suggest a model of oxygen molecule absorption behaviors that is facilitated through the incorporation of Joule heating.

Yoon, Sanghwa; Lim, Jae-Hong; Yoo, Bongyoung

2012-10-01

35

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

36

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

SciTech Connect

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

Varija Agarwal; Donna Post Guillen

2013-08-01

37

Two approaches to micromachining si heat exchanger for Joule-Thomson cryosurgical probes  

Microsoft Academic Search

This paper describes results from two types of micromachined recuperative heat exchangers intended for Joule-Thomson (J-T) cryosurgical probes, which require high stream-to-stream thermal conductance while restricting parasitic stream-wise (axial) conduction. In design A, rows of fins composed of high conductivity silicon are bonded onto a 100 mum thick base plate composed of low conductivity Pyrex glass. This planar device has

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

2007-01-01

38

Improved Ionospheric Electrodynamic Models and Application to Calculating Joule Heating Rates  

NASA Technical Reports Server (NTRS)

Improved techniques have been developed for empirical modeling of the high-latitude electric potentials and magnetic field aligned currents (FAC) as a function of the solar wind parameters. The FAC model is constructed using scalar magnetic Euler potentials, and functions as a twin to the electric potential model. The improved models have more accurate field values as well as more accurate boundary locations. Non-linear saturation effects in the solar wind-magnetosphere coupling are also better reproduced. The models are constructed using a hybrid technique, which has spherical harmonic functions only within a small area at the pole. At lower latitudes the potentials are constructed from multiple Fourier series functions of longitude, at discrete latitudinal steps. It is shown that the two models can be used together in order to calculate the total Poynting flux and Joule heating in the ionosphere. An additional model of the ionospheric conductivity is not required in order to obtain the ionospheric currents and Joule heating, as the conductivity variations as a function of the solar inclination are implicitly contained within the FAC model's data. The models outputs are shown for various input conditions, as well as compared with satellite measurements. The calculations of the total Joule heating are compared with results obtained by the inversion of ground-based magnetometer measurements. Like their predecessors, these empirical models should continue to be a useful research and forecast tools.

Weimer, D. R.

2004-01-01

39

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

NASA Astrophysics Data System (ADS)

We make a statistical study of ionospheric Joule heating with the Poynting flux method using six months of Astrid-2/EMMA electric and magnetic field data during 1999 (solar maximum year). For the background magnetic field we use the IGRF model. Our results are in agreement with earlier statistical satellite studies using both the ?PE2 method and the Poynting flux method. We present a rather comprehensive set of fitted Joule heating formulas expressing the Joule heating in given magnetic local time (MLT) and invariant latitude (ILAT) range under given solar illumination conditions as a function of the Kp index, the AE index, the Akasofu epsilon parameter and the solar wind kinetic energy flux. The study thus provides improved and more detailed estimates of the statistical Joule heating. Such estimates are necessary building blocks for future quantitative studies of the power budget in the magnetosphere and in the nightside auroral region.

Olsson, A.; Janhunen, P.; Karlsson, T.; Ivchenko, N.; Blomberg, L.

2004-12-01

40

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

SciTech Connect

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

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

1995-07-01

41

Investigations on two-phase heat exchanger for mixed refrigerant Joule-Thomson cryocooler  

NASA Astrophysics Data System (ADS)

The design of the recuperative heat exchanger used to pre-cool the refrigerant mixture prior to J-T expansion is crucial for the efficient operation of the mixed refrigerant Joule- Thomson (MR J-T) cryocooler. The multi-component non-azeotropic refrigerant mixture undergoes boiling and condensation heat transfer simultaneously in the heat exchanger. Therefore, it is important to analyze the performance of the heat exchanger in terms of temperature distribution with respect to the mixture of gases used. In the present work, temperature measurements are carried out at the ends of the heat exchanger for high pressure stream, while eight sensors are installed at equal distance along the length of heat exchanger to measure temperature of low pressure stream. The paper reports variation in heat transfer coefficient along the length of the heat exchanger. The variation is discussed with respect to temperature distribution across the length and changes in thermo-physical properties of the gas mixture.

Ardhapurkar, Purushottam; Sridharan, Arunkumar; Atrey, Milind

2012-06-01

42

Joule Thomson refrigerator  

Microsoft Academic Search

A bi-directional Joule Thomson refrigerator is described, which is of simple construction at the cold end of the refrigerator. Compressed gas flowing in either direction through the Joule Thomson expander valve and becoming liquid, is captured in a container in direct continuous contact with the heat load. The Joule Thomson valve is responsive to the temperature of the working fluid

Chung K. Chan; John R. Gatewood

1988-01-01

43

Testing of a scanning adiabatic calorimeter with Joule effect heating of the sample  

NASA Astrophysics Data System (ADS)

We evaluated a scanning adiabatic resistive calorimeter (SARC) developed to measure the specific enthalpy of viscous and gel-type materials. The sample is heated employing the Joule effect. The cell is constituted by a cylindrical jacket and two pistons, and the sample is contained inside the jacket between the two pistons. The upper piston can slide to allow for thermal expansion and to keep the pressure constant. The pistons also function as electrodes for the sample. While the sample is heated through the Joule effect, the electrodes and the jacket are independently heated to the same temperature of the sample using automatic control. This minimizes the heat transport between the sample and its surroundings. The energy to the sample is supplied by applying to the electrodes an ac voltage in the kilohertz range, establishing a current in the sample and inducing electric dissipation. This energy can be measured with enough exactitude to determine the heat capacity. This apparatus also allows for the quantification of the thermal conductivity by reproducing the evolution of the temperature as heat is introduced only to one of the pistons. To this end, the system was modeled using finite element calculations. This dual capability proved to be very valuable for correction in the determination of the specific enthalpy. The performance of the SARC was evaluated by comparing the heat capacity results to those obtained by differential scanning calorimetry measurements using a commercial apparatus. The analyzed samples were zeolite, bauxite, hematite, bentonite, rice flour, corn flour, and potato starch.

Barreiro-Rodríguez, G.; Yáñez-Limón, J. M.; Contreras-Servin, C. A.; Herrera-Gomez, A.

2008-01-01

44

Conducting-probe AFM nanoscale joule heating yields charge-density-wave transition detection.  

PubMed

Several layered transition-metal dichalcogenides are studied using conducting probe AFM aiming to investigate the probe-mediated thermal processes likely to arise in the probe-substrate vicinity due to the high-current densities involved. A signature of local heating is found in the shape of current-potential (i/V) curves. The latter allows straightforward detection of a charge-density-wave (CDW) transition for 1T-TaSe(2) samples exhibiting it above room temperature. This is an illustration of a new use of conducting probe AFM to investigate solid-state bulk characteristics owing to a distinctive nanoscale Joule heating. PMID:16706457

Schneegans, Olivier; Moradpour, Alec; Wang, Kang; Leblanc, Annie; Molinié, Philippe

2006-05-25

45

Magnetospheric Structure and Atmospheric Joule Heating of Habitable Planets Orbiting M-dwarf Stars  

NASA Astrophysics Data System (ADS)

We study the magnetospheric structure and the ionospheric Joule Heating of planets orbiting M-dwarf stars in the habitable zone using a set of magnetohydrodynamic models. The stellar wind solution is used to drive a model for the planetary magnetosphere, which is coupled with a model for the planetary ionosphere. Our simulations reveal that the space environment around close-in habitable planets is extreme, and the stellar wind plasma conditions change from sub- to super-Alfvénic along the planetary orbit. As a result, the magnetospheric structure changes dramatically with a bow shock forming in the super-Alfvénic sectors, while no bow shock forms in the sub-Alfvénic sectors. The planets reside most of the time in the sub-Alfvénic sectors with poor atmospheric protection. A significant amount of Joule Heating is provided at the top of the atmosphere as a result of the intense stellar wind. For the steady-state solution, the heating is about 0.1%-3% of the total incoming stellar irradiation, and it is enhanced by 50% for the time-dependent case. The significant Joule Heating obtained here should be considered in models for the atmospheres of habitable planets in terms of the thickness of the atmosphere, the top-side temperature and density, the boundary conditions for the atmospheric pressure, and particle radiation and transport. Here we assume constant ionospheric Pedersen conductance similar to that of the Earth. The conductance could be greater due to the intense EUV radiation leading to smaller heating rates. We plan to quantify the ionospheric conductance in future study.

Cohen, O.; Drake, J. J.; Glocer, A.; Garraffo, C.; Poppenhaeger, K.; Bell, J. M.; Ridley, A. J.; Gombosi, T. I.

2014-07-01

46

On the importance of E-field variability for Joule heating in the high-latitude thermosphere  

NASA Astrophysics Data System (ADS)

Joule heating is known to be one of the major energy sources of the upper atmosphere. Knowledge of the magnitude of this source is fundamentally important to a thorough understanding of the region's physics. However, Joule heating is currently one of the largest sources of uncertainty in the thermosphere's energy budget. In numerical models the distribution of Joule heating is generally computed using mean or average convection patterns, which evolve on a relatively long time scale in response to changes in solar wind conditions. The convection patterns represent average electric potential distributions, and thus the resulting amount of Joule heating is proportional to the square of the average E-field. That method ignores the important component of Joule heating due to rapid or small-scale fluctuations in E-field or ion drifts. However, E-field fluctuations are known to exist on a variety of temporal and spatial scales, and the actual amount of Joule heating in the thermosphere is proportional to the average of the square of the E-field. The computation of the average of the square of the E-field requires knowledge of the statistical characteristics of E-field variability; thus knowledge not available at present. In this paper we assess, on the bases of theoretical considerations, the importance of E-field variability as an upper-atmosphere energy source. We show that the inclusion of E-field variability in the high-latitude convection model can significantly increase the amount of Joule heating for a given pattern.

Codrescu, M. V.; Fuller-Rowell, T. J.; Foster, J. C.

47

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

48

Joule-Heating-Induced Damage in Cu-Al Wedge Bonds Under Current Stressing  

NASA Astrophysics Data System (ADS)

Copper wires are increasingly used to replace gold wires in wire-bonding technology owing to their better electrical properties and lower cost. However, not many studies have been conducted on electromigration-induced failure of Cu wedge bonds on Al metallization. In this study, we investigated the failure mechanism of Cu-Al wedge bonds under high current stressing from 4 × 104 A/cm2 to 1 × 105 A/cm2 at ambient temperature of 175°C. The resistance evolution of samples during current stressing and the microstructure of the joint interface between the Cu wire and Al-Si bond pad were examined. The results showed that abnormal crack formation accompanying significant intermetallic compound growth was observed at the second joint of the samples, regardless of the direction of electric current for both current densities of 4 × 104 A/cm2 and 8 × 104 A/cm2. We propose that this abnormal crack formation at the second joint is mainly due to the higher temperature induced by the greater Joule heating at the second joint for the same current stressing, because of its smaller bonded area compared with the first joint. The corresponding fluxes induced by the electric current and chemical potential difference between Cu and Al were calculated and compared to explain the failure mechanism. For current density of 1 × 105 A/cm2, the Cu wire melted within 0.5 h owing to serious Joule heating.

Yang, Tsung-Han; Lin, Yu-Min; Ouyang, Fan-Yi

2014-01-01

49

Theoretical and numerical analysis of temperature gradient focusing via Joule heating.  

PubMed

We present a detailed theoretical and numerical analysis of temperature gradient focusing (TGF) via Joule heating-an analytical species concentration and separation technique relying upon the dependence of an analyte's velocity on temperature due to the temperature dependence of a buffer's ionic strength and viscosity. The governing transport equations are presented, analyzed, and implemented into a quasi-1D numerical model to predict the resulting temperature, velocity, and concentration profiles along a microchannel of varying width under an applied electric field. Numerical results show good agreement with experimental trials presented in previous work. The model is used to analyze the effects of varying certain geometrical and experimental parameters on the focusing performance of the device. Simulations also help depict the separation capability of the device, as well as the effectiveness of different buffer systems used in the technique. The analysis provides rule-of-thumb methodology for implementation of TGF into analytical systems, as well as a fundamental model applicable to any lab-on-a-chip system in which Joule heating and temperature-dependent electrokinetic transport are to be analyzed. PMID:17594010

Sommer, Greg J; Kim, Sun Min; Littrell, Robert J; Hasselbrink, Ernest F

2007-07-01

50

A model for Joule heating-induced dispersion in microchip electrophoresis.  

PubMed

This paper presents an analytical and parameterized model for analyzing the effects of Joule heating on analyte dispersion in electrophoretic separation microchannels. We first obtain non-uniform temperature distributions in the channel resulting from Joule heating, and then determine variations in electrophoretic velocity, based on the fact that the analyte's electrophoretic mobility depends on the buffer viscosity and hence temperature. The convection-diffusion equation is then formulated and solved in terms of spatial moments of the analyte concentration. The resulting model is validated by both numerical simulations and experimental data, and holds for all mass transfer regimes, including unsteady dispersion processes that commonly occur in microchip electrophoresis. This model, which is given in terms of analytical expressions and fully parameterized with channel dimensions and material properties, applies to dispersion of analyte bands of general initial shape in straight and constant-radius-turn channels. As such, the model can be used to represent analyte dispersion in microchannels of more general shape, such as serpentine- or spiral-shaped channels. PMID:15570376

Wang, Yi; Lin, Qiao; Mukherjee, Tamal

2004-12-01

51

The numerical modelling of Joule heating effects in thoriated tungsten cathodes of high-current plasma arcs  

Microsoft Academic Search

The influence of the Joule heating on the performance of thoriated tungsten cathodes working at current densities of 103-104 A cm-2 is investigated. The variation of the degree of coverage of the cathode surface by thorium atoms is considered, together with the heat conduction and the diffusion of thorium in the cathode bulk. The nonlinear system of equations governing these

E. Casado; V. Colomer

2000-01-01

52

Microchannel heat exchanger for two-phase Mixed Refrigerant Joule Thomson process  

NASA Astrophysics Data System (ADS)

Mixed Refrigerant Joule Thomson (MR-JT) refrigerators are widely used in various kinds of cryogenic systems these days. Printed Circuit Heat Exchanger (PCHE) is one of the promising cryogenic compact recuperators for MR-JT refrigerators due to its compactness, high NTU and robustness. However, PCHE composed with microchannel bundles can cause flow mal-distribution, and it can cause the degradation of thermal performance of the system. To mitigate the flow mal-distribution problem, the cross link (or intra-layer bypass) can be adapted to parallel microchannels. Two heat exchangers are fabricated in this study; one has straight channels, and the other one has intra-layer bypass structure between channels to enhance the flow distribution. The MR-JT refrigerators are operated with these two heat exchanger and the no-load temperatures are compared. The lower no load temperature achieved with the intra-layer bypass structured heat exchanger. The results indicate that the flow mal-distribution in the microchannel heat exchanger can be mitigated with intra-layer bypass structure, and relaxation of flow mal-distribution in the heat exchanger guarantee the MR-JT refrigerator's performance.

Baek, Seungwhan; Lee, Jisung; Lee, Cheonkyu; Jeong, Sangkwon

2014-01-01

53

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

54

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

55

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

56

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

57

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

SciTech Connect

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

Routt, K.R.

1980-05-01

58

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

PubMed

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. PMID:23992528

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

2013-01-01

59

Consistent melting behavior induced by Joule heating between Ag microwire and nanowire meshes  

NASA Astrophysics Data System (ADS)

The melting behavior of an Ag microwire mesh induced by Joule heating was numerically investigated and compared with that of the corresponding Ag nanowire mesh with the same structure but different geometrical and physical properties of the wire itself. According to the relationship of melting current and melting voltage during the melting process, a similar repetitive zigzag pattern in melting behavior was discovered in both meshes. On this basis, a dimensionless parameter defined as figure of merit was proposed to characterize the current-carrying ability of the mesh. The consistent feature of figure of merit in both meshes indicates that the melting behavior of the Ag nanowire mesh can be predicted from the present results of the corresponding Ag microwire mesh with the same structure but made from a different wire (e.g., different size, different material) through simple conversion. The present findings can provide fundamental insight into the reliability analysis on the metallic nanowire mesh-based transparent conductive electrode.

Tsuchiya, Kaoru; Li, Yuan; Saka, Masumi

2014-05-01

60

Consistent melting behavior induced by Joule heating between Ag microwire and nanowire meshes  

PubMed Central

The melting behavior of an Ag microwire mesh induced by Joule heating was numerically investigated and compared with that of the corresponding Ag nanowire mesh with the same structure but different geometrical and physical properties of the wire itself. According to the relationship of melting current and melting voltage during the melting process, a similar repetitive zigzag pattern in melting behavior was discovered in both meshes. On this basis, a dimensionless parameter defined as figure of merit was proposed to characterize the current-carrying ability of the mesh. The consistent feature of figure of merit in both meshes indicates that the melting behavior of the Ag nanowire mesh can be predicted from the present results of the corresponding Ag microwire mesh with the same structure but made from a different wire (e.g., different size, different material) through simple conversion. The present findings can provide fundamental insight into the reliability analysis on the metallic nanowire mesh-based transparent conductive electrode.

2014-01-01

61

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

NASA Astrophysics Data System (ADS)

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

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

2008-10-01

62

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

63

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.

64

Study of Joule heating effects on temperature gradient in diverging microchannels for isoelectric focusing applications.  

PubMed

IEF is a high-resolution separation method taking place in a medium with continuous pH gradients, which can be set up by applying electrical field to the liquid in a diverging microchannel. The axial variation of the channel cross-sectional area will induce nonuniform Joule heating and set up temperature gradient, which will generate pH gradient when proper medium is used. In order to operationally control the thermally generated pH gradients, fundamental understanding of heat transfer phenomena in microfluidic chips with diverging microchannels must be improved. In this paper, two 3-D numerical models are presented to study heat transfer in diverging microchannels, with static and moving liquid, respectively. Through simulation, the temperature distribution for the entire chip has been revealed, including both liquid and solid regions. The model for the static liquid scenario has been compared with published results for validation. Parametric studies have showed that the channel geometry has significant effects on the peak temperature location, and the electrical conductivity of the medium and the wall boundary convection have effects on the generated temperature gradients and thus the generated pH gradients. The solution to the continuous flow model, where the medium convection is considered, shows that liquid convection has significant effects on temperature distribution and the peak temperature location. PMID:16703632

Kates, Brian; Ren, Carolyn L

2006-05-01

65

Polar thermospheric Joule heating, and redistribution of recombination energy in the upper mesosphere  

NASA Technical Reports Server (NTRS)

Kellogg (1961), suggested that transport of atomic oxygen from the summer into the winter hemisphere and subsequent release of energy by three body recombination, O+O+N2 yields O2+N2+E, may contribute significantly to the so-called mesopause temperature anomaly. Earlier model calculations have shown that Kellogg's mechanism produces about a 10-percent increase in the temperature from summer to winter at 90 km. This process, however, is partly compensated by differential heating from absorption of UV radiation associated with dissociation of O2. In the auroral region of the thermosphere, there is a steady energy dissipation by Joule heating causing a redistribution and depletion of atomic oxygen due to wind-induced diffusion. With the removal of O, latent chemical energy normally released by three body recombination is also removed, and the result is that the temperature decreases by almost 2 percent near 90 km. Through dynamic feedback, this process reduces the depletion of atomic oxygen by about 25 percent and the temperature perturbation in the exosphere from 10 to 7 percent at polar latitudes. Under the influence of the internal dynamo interaction, the prevailing zonal circulation in the upper thermosphere changes direction when the redistribution of recombination energy is considered.

Mayr, H. G.; Harris, I.; Dube, M.

1990-01-01

66

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

67

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

NASA Technical Reports Server (NTRS)

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

Sibille, Laurent; Dominguez, Jesus A.

2012-01-01

68

Local and transient structural changes in stratum corneum at high electric fields: contribution of Joule heating.  

PubMed

Electroporation of skin is accompanied by local heating, such that thermally induced structural changes of the stratum corneum (SC) accompany the field effect. Comparing on the time scale, the local changes in structure, temperature and conductance of the SC, during and after the pulse, it is seen that Joule heating also facilitates the subsequent molecular transport. It is found that the transport of medium-sized, ionic molecules occurs through localized transport regions (LTR). The size of a LTR increases with the pulse length, whereas the density of the LTRs increases with increasing voltage, for instance at U(SC=)80 V, the LTR cover approximately 0.02--1% of the surface area. The state of low resistance within the LTR is long-lived. During high voltage application, the center of the LTR is heated above the phase transition temperature of the SC lipids (70 degrees C) and the heat front propagates outwards. Inside the SC, the pulse causes aggregates of small-sized vesicles. At a higher temperature, the aggregate formation and their disappearance are delayed. Multiple pulses with the applied voltage of U(appl)=80 V induce the formation of long-lasting vesicle aggregates with a diameter of slashed circle=1--30 microm, covering 0.05--0.5% of the total sample area. The electric energy dissipated within the LTR during high voltage application is apparently sufficient to raise the temperature well above the phase transition temperature of the lipids of the SC, accounting for the conformational changes from the multi-lamella to the vesicular structures. PMID:15967399

Pliquett, U; Gallo, S; Hui, S W; Gusbeth, Ch; Neumann, E

2005-09-01

69

Fabrication and characterization of U-shaped beams for the determination of Young's modulus modification due to Joule heating of polysilicon microstructures  

Microsoft Academic Search

The modification of Young's modulus is determined before and after the Joule heating generated by a current passing through polysilicon microstructures. U-shaped overhanging polysilicon beams are specially designed and fabricated to prevent both the heat transfer to substrate and the deformation by thermal expansion. The Joule heating is performed to the beams by applying a current of 5-20 mA for

E. H. Yang; H. Fujita

1997-01-01

70

Consistent melting behavior induced by Joule heating between Ag microwire and nanowire meshes.  

PubMed

The melting behavior of an Ag microwire mesh induced by Joule heating was numerically investigated and compared with that of the corresponding Ag nanowire mesh with the same structure but different geometrical and physical properties of the wire itself. According to the relationship of melting current and melting voltage during the melting process, a similar repetitive zigzag pattern in melting behavior was discovered in both meshes. On this basis, a dimensionless parameter defined as figure of merit was proposed to characterize the current-carrying ability of the mesh. The consistent feature of figure of merit in both meshes indicates that the melting behavior of the Ag nanowire mesh can be predicted from the present results of the corresponding Ag microwire mesh with the same structure but made from a different wire (e.g., different size, different material) through simple conversion. The present findings can provide fundamental insight into the reliability analysis on the metallic nanowire mesh-based transparent conductive electrode. PMID:24910578

Tsuchiya, Kaoru; Li, Yuan; Saka, Masumi

2014-01-01

71

A dynamic molecular probe to investigate catalytic effects and Joule heating in enantioselective MEKC.  

PubMed

Enantiomerization of ferroin [tris(1,10-phenanthroline)-iron(II)-complex] was investigated by enantioselective dynamic micellar EKC. The enantiomer separation was performed in an aqueous 50 mM sodium borate/sodium dihydrogenphosphate buffer at pH 8.0 in the presence of the chiral surfactant sodium cholate. The unified equation of dynamic chromatography was employed to determine reaction rate constants from the electropherograms featured with distinct plateau formation. Activation parameters DeltaH( not equal) = 124.0 +/- 0.5 kJ/mol and DeltaS( not equal) = 121 +/- 1 J.K(-1)mol(-1) were calculated from temperature-dependent measurements between 10.0 and 27.5 degrees C in 2.5 K steps. Considering the data obtained by polarimetry of enantiomeric pure ferroin in water, it was found that enantiomerization rate in the micelle is accelerated by a factor of 12. Because of the highly positive activation entropy DeltaS( not equal), ferroin was used as a temperature-sensitive dynamic molecular probe to determine temperature deviations caused by Joule heating. PMID:17226759

Trapp, Oliver

2007-02-01

72

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

73

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

74

In-situ observation of phase transformation in amorphous silicon during Joule-heating induced crystallization process  

Microsoft Academic Search

During the Joule-heating induced crystallization (JIC) process of amorphous silicon for display applications, its phase transformation from amorphous to polycrystalline phases occurs through two different kinetic paths of either solid-to-solid or solid-to-liquid-to-solid phases. Depending on input conditions such as power density and pulsing time, each path results in nano-crystalline silicon phases or large grain structures produced by lateral growth, respectively.

Dong-Hyun Kim; Won-Eui Hong; Jae-Sang Ro; Seong Hyuk Lee; Chang-Hoon Lee; Seungho Park

2011-01-01

75

Cycling Joule Thomson refrigerator  

Microsoft Academic Search

A symmetrical adsorption pump\\/compressor system having a pair of mirror image legs and a Joule Thomson expander, or valve, interposed between the legs thereof for providing a, efficient refrigeration cycle is described. The system further includes a plurality of gas operational heat switches adapted selectively to transfer heat from a thermal load and to transfer or discharge heat through a

E. Tward

1983-01-01

76

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

77

A Joule-Thomson cooling system with a Si\\/glass heat exchanger for 0.1–1 w heat loads  

Microsoft Academic Search

This paper reports a Joule-Thomson cooling system that provides 0.1-1 W cooling power using a micromachined Si\\/glass perforated plate heat exchanger. The gas expansion is performed through a micromachined valve that is piezoelectrically actuated, or alternatively through a commercial jewel orifice. The modulated J-T system using the microvalve can achieve 254.5 K at a pressure difference of 430 kPa and

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

2009-01-01

78

Joule Thomson refrigerator  

NASA Technical Reports Server (NTRS)

A bi-directional Joule Thomson refrigerator is described, which is of simple construction at the cold end of the refrigerator. Compressed gas flowing in either direction through the Joule Thomson expander valve and becoming liquid, is captured in a container in direct continuous contact with the heat load. The Joule Thomson valve is responsive to the temperature of the working fluid near the valve, to vary the flow resistance through the valve so as to maintain a generally constant flow mass between the time that the refrigerator is first turned on and the fluid is warm, and the time when the refrigerator is near its coldest temperature and the fluid is cold. The valve is operated by differences in thermal coefficients of expansion of materials to squeeze and release a small tube which acts as the expander valve.

Chan, Chung K. (inventor); Gatewood, John R. (inventor)

1988-01-01

79

Joule Thomson refrigerator  

NASA Astrophysics Data System (ADS)

A bi-directional Joule Thomson refrigerator is described, which is of simple construction at the cold end of the refrigerator. Compressed gas flowing in either direction through the Joule Thomson expander valve and becoming liquid, is captured in a container in direct continuous contact with the heat load. The Joule Thomson valve is responsive to the temperature of the working fluid near the valve, to vary the flow resistance through the valve so as to maintain a generally constant flow mass between the time that the refrigerator is first turned on and the fluid is warm, and the time when the refrigerator is near its coldest temperature and the fluid is cold. The valve is operated by differences in thermal coefficients of expansion of materials to squeeze and release a small tube which acts as the expander valve.

Chan, Chung K.; Gatewood, John R.

1988-10-01

80

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

81

Considerable Different Frequency Dependence of Dynamic Tensile Modulus between Self-Heating (Joule Heat) and External Heating for Polymer-Nickel-Coated Carbon Fiber Composites.  

PubMed

Dynamic tensile moduli of polyethylene-nickel-coated carbon fiber (NiCF) composites with 10 and 4 vol % NiCF contents under electrical field were measured by a homemade instrument in the frequency range of 100-0.01 Hz. The drastic descent of the storage modulus of the composite with 10 vol % was verified in lower frequency range with elevating surface temperature (Ts) by self-heating (Joule heat). The composite was cut when Ts was beyond 108 °C. On the other hand, the measurement of the composite with 4 vol % beyond 88 °C was impossible, since Ts did not elevate because of the disruption of current networks. Incidentally, the dynamic tensile moduli by external heating could be measured up to 130 and 115 °C for 10 and 4 vol %, respectively, but the two composites could be elongated beyond the above temperatures. Such different properties were analyzed in terms of crystal dispersions, electrical treeing, and thermal fluctuation-induced tunneling effect. PMID:24893179

Zhang, Rong; Bin, Yuezhen; Dong, Enyuan; Matsuo, Masaru

2014-06-26

82

A procedure for the calculation of the natural gas molar heat capacity, the isentropic exponent, and the Joule–Thomson coefficient  

Microsoft Academic Search

A numerical procedure for the computation of a natural gas molar heat capacity, the isentropic exponent, and the Joule–Thomson coefficient has been derived using fundamental thermodynamic equations, DIPPR AIChE generic ideal heat capacity equations, and AGA-8 extended virial-type equations of state. The procedure is implemented using the Object-Oriented Programming (OOP) approach. The results calculated are compared with the corresponding measurement

Ivan Mari?

2007-01-01

83

Bipolar resistance switching in high-performance Cu/ZnO:Mn/Pt nonvolatile memories: active region and influence of Joule heating  

NASA Astrophysics Data System (ADS)

Manganese-doped ZnO dielectric films sandwiched between Cu and Pt electrodes were prepared and investigated for nonvolatile resistive memory applications. These structures exhibit promising bipolar resistive switching (RS) behavior with a large ON/OFF ratio (~103), suitable threshold voltages (1.4 and -0.7 V for SET and RESET, respectively), long retention (>104 s at 85 °C) and low write current (10 ?A). A study on the ZnO:Mn thickness dependence of threshold voltages reveals that RS should be an interfacial effect rather than bulk behavior. By elevating current compliance during the SET process, an anomalous transition from bistable memory switching to monostable threshold switching was observed, which is attributed to the instability of conductive filaments induced by Joule heating effects. Apart from this, fast voltage sweep cycles without efficient heat dissipation were also found to accelerate the hard dielectric breakdown of the device, reflecting the impact of accumulative Joule heating. These results reveal the possible influences of Joule heating effects on bipolar resistance switching and thus the necessity of avoiding them in future high-density memory applications. Conceivable solutions are considered to be reducing the operating currents and improving the heat dissipation of memory devices based on our experiments.

Chao Yang, Yu; Pan, Feng; Zeng, Fei

2010-02-01

84

Dual Rocket Observations of Large, Intermediate, and Short Scale Electric Fields in the Lower Auroral Ionosphere and Their Contribution to Joule Heating  

NASA Astrophysics Data System (ADS)

0n March 27, 2003, a multiple rocket and radar investigation was carried out from Poker Flat, Alaska to investigate the complex electrodynamics and neutral-plasma coupling inherent to the high latitude, lower ionosphere (100-200 km) and in particular to quantify the Joule heating in this region. Measurements within these altitudes gathered along vertical trajectories permit the Joule heating to be calculated where the Pedersen conductivity maximizes and where the ratio of the ion-neutral collision frequency to the ion gyro frequency varies considerably. Two instrumented rockets were launched into a post-midnight aurora within 3 minutes of each other, achieving apogees near 200 km while a third rocket was launched a minute later that released TMA trails to measure the neutral wind velocity. In this presentation, we focus on the in situ measurements of DC, quasi-DC, and AC electric fields gathered using the double probe technique, although we also use the measurements of plasma density, energetic electrons, and suprathermal ions to calculate conductivities and other important parameters related to Joule heating. In addition, data from the imaging coherent scatter radar provide information concerning the ambient plasma drifts and enable the in situ data to be placed in context. During the upleg of each rocket, the in situ measurements revealed ~50mV/m DC electric fields directed towards the equator that, for each rocket, became considerably structured near apogee and during the downleg portions of their trajectories. Each payload encountered intermediate (10 km - 100 km) and small scale (10m - 10 km) electric fields with the largest amplitudes along their paths typically within the range of 5-25 mV/m. Such waves can contribute significantly to Joule heating, although they are frequently not included in models due to their small spatial scales. The rocket payloads also encountered intense (~20-30 mV/m) Farley-Buneman two-stream waves with very short wavelengths (1-10m) in the auroral electrojet region (90-118 km). We use the neutral wind measurements to establish the relative frame of the ion and neutral gases and calculate the Joule heating associated with the electric fields at all scales as a function of altitude.

Pfaff, R. F.; Steigies, C.; Freudenreich, H.; Larsen, M.; Hysell, D.; Clemmons, J.; Knudsen, D.; Burchill, J.

2003-12-01

85

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

SciTech Connect

An iron phosphate composition for vitrifying a high sulfate (~17 wt%) and high alkali (~80 wt%) low activity Hanford waste, known as AZ102 LAW, has been developed for processing in a Joule Heated Melter (JHM) or a Cold Crucible Induction Melter (CCIM). This composition produced a glass waste form, designated as MS26AZ102F-2, with a waste loading of 26 wt% of the AZ102 which corresponded to a total alkali and sulfate (SO3) content of 21 and 4.2 wt%, respectively. A slurry (7M Na) of MS26AZ102F-2 simulant was melted continuously at temperatures between 1030 and 1090°C for 10 days in a small JHM at PNNL and for 7 days in a CCIM at INL. The as-cast glasses produced in both melters and in trial laboratory experiments along with their CCC-treated counterparts met the DOE LAW requirements for the Product Consistency Test (PCT) and the Vapor Hydration Test (VHT). These glass waste forms retained up to 77 % of the SO3 (3.3 wt%), 100% of the Cesium, and 33 to 44% of the rhenium, surrogate for Tc-99, all of which either exceeded or were comparable to the retention limit for these species in borosilicate glass nuclear waste form. Analyses of commercial K-3 refractory lining and the Inconel 693 metal electrodes used in JHM indicated only minimum corrosion of these components by the iron phosphate glass. This is the first time that an iron phosphate composition (slurry feed) was melted continuously in the JHM and CCIM, thereby, demonstrating that iron phosphate glasses can be used as alternative hosts for vitrifying nuclear waste.

Day, Delbert E.; Brow, R. K.; Ray, C. S.; Kim, Cheol-Woon; Reis, Signo T.; Vienna, John D.; Peeler, David K.; Johnson, Fabienne; Hansen, E. K.; Sevigny, Gary J.; Soelberg, Nicolas R.; Pegg, Ian L.; Gan, Hao

2012-01-05

86

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

87

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

88

Joule heating effect on oxide whisker growth induced by current stressing in Cu/Sn-58Bi/Cu solder joint  

NASA Astrophysics Data System (ADS)

The electromigration test was conducted in Cu/Sn-58Bi/Cu solder joint with high current density of 104 A/ cm2. Results showed that a large number of whiskers with natural weed appearance were observed at the cathode side in such a short current stressing time. Furthermore, some secondary whiskers were attached to the primary whiskers, which has never been reported before. We presumed the vapor-solid (VS) mechanism to explain the oxide whiskers growth, which was quite different from the traditional theory that the compressive stress took on the driving force. In conclusion, due to the over-Joule heating effect, the metal oxide whiskers were synthesized in bulk quantities by thermal evaporation of Sn oxide and Bi oxide.

He, Hongwen; Cao, Liqiang; Wan, Lixi; Zhao, Haiyan; Xu, Guangchen; Guo, Fu

2012-08-01

89

On spectral relaxation method approach for steady von Kármán flow of a Reiner-Rivlin fluid with Joule heating, viscous dissipation and suction/injection  

NASA Astrophysics Data System (ADS)

In this study we use the spectral relaxation method (SRM) for the solution of the steady von Kármán flow of a Reiner-Rivlin fluid with Joule heating and viscous dissipation. The spectral relaxation method is a new Chebyshev spectral collocation based iteration method that is developed from the Gauss-Seidel idea of decoupling systems of equations. In this work, we investigate the applicability of the method in solving strongly nonlinear boundary value problems of von Kármán flow type. The SRM results are validated against previous results present in the literature and with those obtained using the bvp4c, a MATLAB inbuilt routine for solving boundary value problems. The study highlights the accuracy and efficiency of the proposed SRM method in solving highly nonlinear boundary layer type equations.

Motsa, Sandile S.; Makukula, Zodwa G.

2013-03-01

90

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

NASA Astrophysics Data System (ADS)

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 and James Prescott Joule found the connection between heat and work, the Mayer-Joule principle.

Newburgh, Ronald; Leff, Harvey S.

2011-11-01

91

The joule balance in NIM of China  

NASA Astrophysics Data System (ADS)

The advantage of the joule balance over the classic watt balance is that the dynamic measurement in the watt balance is replaced by a static measurement, which makes the whole measurement procedure easier. The main problems in the joule balance are the precise measurement of mutual inductance and coil heating. These problems and recent progress in the development of the joule balance are described and discussed in this paper. The whole system is at the stage of being adjusted and improved. The principle of the joule balance has been demonstrated by a measurement of the Planck constant, h = 6.626?104(59) × 10?34 J s with an 8.9 ppm measurement uncertainty.

Zhonghua, Zhang; Qing, He; Zhengkun, Li; Bing, Han; Yunfeng, Lu; Jiang, Lan; Chen, Li; Shisong, Li; Jinxin, Xu; Nong, Wang; Gang, Wang; Hongzhi, Gong

2014-04-01

92

Ionospheric Joule heating, fast flow channels, and magnetic field line topology for IMF By-dominant conditions - Observations and comparisons with predicted reconnection jet speeds  

NASA Astrophysics Data System (ADS)

When the interplanetary magnetic field (IMF) is dawnward or duskward, magnetic merging between the IMF and the geomagnetic field occurs near the cusp on the dayside flanks of the magnetosphere. While these periods are usually considered "quiet," they can lead to intense localized energy deposition into the dayside ionosphere. We analyze two intervals during the geomagnetic storm on August 24, 2005: one with steady duskward IMF and one with steady dawnward IMF. Using outputs from the Assimilative Mapping of Ionospheric Electrodynamics (AMIE) and data from the Defense Meteorological Satellite Program, we show that intense Joule heating exists on fast ionospheric flow channels which lie on open field lines. In addition, the flow channels on open field lines have large components in the sunward direction, and therefore resist the bulk solar wind and magnetosheath flow. We compare observed velocities with predicted reconnection jet speeds using magnetosheath and cusp parameters from an MHD simulation. Results suggest that the fast ionospheric flow corresponds to portions of the reconnection jet populated by low density plasma. The importance of ionospheric conductance in determining the ionospheric flow is also discussed.

Wilder, F. D.; Crowley, G.; Eriksson, S.; Newell, P. T.; Hairston, M. R.

2012-12-01

93

Viscous dissipation and Joule heating effects on MHD-free convection from a vertical plate with power-law variation in surface temperature in the presence of Hall and ion-slip currents  

Microsoft Academic Search

An analysis is presented to study the effects of viscous dissipation and Joule heating on MHD-free convection flow past a semi-infinite vertical flat plate in the presence of the combined effect of Hall and ion-slip currents for the case of power-law variation of the wall temperature. The fluid is permeated by a strong transverse magnetic field imposed perpendicularly to the

Emad M. Abo-Eldahab; Mohamed A. El Aziz

2005-01-01

94

Electrical-Thermal Co-Simulation of 3D Integrated Systems With Micro-Fluidic Cooling and Joule Heating Effects  

Microsoft Academic Search

In this paper, the electrical-thermal co-simulation of 3DsystemswithJouleheating,fluidiccoolingandairconvectionef- fectsisproposed.Thefinite-volumemethodformulationsofvoltage distribution equation, heat equations for both fluid flow and solid medium with nonuniform mesh are explained in detail. Based on the proposed iterativeco-simulation method,package temperature distributionandvoltagedropwithJouleheatingandfluidiccooling effects can be estimated. Several packaging examples are simu- lated and the results show that with micro-channel fluidic cooling in high power density 3D integrated

Jianyong Xie; Madhavan Swaminathan

2011-01-01

95

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

96

Advances in small Joule-Thomson coolers  

NASA Astrophysics Data System (ADS)

Considerable work has been done on the development of a new type of heat exchanger for Joule Thomson, JT, coolers which is referred to as a matrix-tube heat exchanger. This has permitted coolers to be built that are smaller than conventional finned tube heat exchangers and has made it easier to build multistage and multicircuit heat exchangers. This paper discusses some characteristics of JT cooling and describes a number of different types of heat exchangers along with typical applications. Specific information is given on the size and cooling characteristic of matrix-tube-type heat exchangers.

Longsworth, Ralph C.

97

Cascade Joule-Thomson refrigerators  

SciTech Connect

The design criteria for cascade Joule-Thomson refrigerators for cooling in the temperature range from 300 K to 4.2 K were studied. The systems considered use three or four refrigeration stages with various working gases to achieve the low temperatures. Each stage results in cooling to a progressively lower temperature and provides cooling at intermediate temperatures to remove the substantial amount of parasitic heat load encountered in a typical dewar. With careful dewar design considerable cooling can be achieved with moderate gas flows. For many applications, e.g., in the cooling of sensitive sensors, the fact that the refrigerator contains no moving parts and may be remotely located from the gas source is of considerable advantage. A small compressor suitable for providing the gas flows required was constructed.

Tward, E.; Steyert, W.A.

1983-12-01

98

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

99

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

100

Ultrahigh temperature stability Joule-Thomson cooler with capability to accomodate pressure variations  

Microsoft Academic Search

A Joule-Thomson cryogenic refrigeration system capable of achieving high temperature stabilities in the presence of varying temperature, atmospheric pressure, and heat load is provided. The Joule-Thomson cryogenic refrigeration system includes a demand flow Joule-Thomson expansion valve disposed in a cryostat of the refrigeration system. The expansion valve has an adjustable orifice that controls the flow of compressed gas therethrough and

Steven Bard; Jiunn-Jeng Wu; Curtis A. Trimble

1992-01-01

101

Watt and joule balances  

NASA Astrophysics Data System (ADS)

The time is fast approaching when the SI unit of mass will cease to be based on a single material artefact and will instead be based upon the defined value of a fundamental constant—the Planck constant—h . This change requires that techniques exist both to determine the appropriate value to be assigned to the constant, and to measure mass in terms of the redefined unit. It is important to ensure that these techniques are accurate and reliable to allow full advantage to be taken of the stability and universality provided by the new definition and to guarantee the continuity of the world's mass measurements, which can affect the measurement of many other quantities such as energy and force. Up to now, efforts to provide the basis for such a redefinition of the kilogram were mainly concerned with resolving the discrepancies between individual implementations of the two principal techniques: the x-ray crystal density (XRCD) method [1] and the watt and joule balance methods which are the subject of this special issue. The first three papers report results from the NRC and NIST watt balance groups and the NIM joule balance group. The result from the NRC (formerly the NPL Mk II) watt balance is the first to be reported with a relative standard uncertainty below 2 × 10?8 and the NIST result has a relative standard uncertainty below 5 × 10?8. Both results are shown in figure 1 along with some previous results; the result from the NIM group is not shown on the plot but has a relative uncertainty of 8.9 × 10?6 and is consistent with all the results shown. The Consultative Committee for Mass and Related Quantities (CCM) in its meeting in 2013 produced a resolution [2] which set out the requirements for the number, type and quality of results intended to support the redefinition of the kilogram and required that there should be agreement between them. These results from NRC, NIST and the IAC may be considered to meet these requirements and are likely to be widely debated prior to a decision on redefinition. The CCM had already recognized that agreement was close and has set in place a process whereby redefinition can take place by 2018. The final decision will be in the hands of the Conférence Générale des Poids et Mesures (CGPM) but the results reported here should aid a positive decision. Figure 1. Figure 1. Results from recent measurements of the Planck constant. The reference for the results h 90 is derived from the conventional values of the Josephson constant K J?90 and the von Klitzing constant R K?90. The factor of ten improvement in uncertainty of the NRC watt balance result, over that achieved by the same apparatus at NPL a few years earlier, can be understood as a factor of five improvement arising from the elimination of an effect discovered at NPL that could not be eliminated before shipment to Canada and a factor of two arising from the considerable improvements made by NRC. Once the kilogram has been redefined, the watt and joule balances will complete their transitions from instruments that are primarily of interest to the electrical community for determining the SI electrical units from the mechanical units, to the principal methods by which an individual National Measurement Institute (NMI) can make an independent determination of the SI unit of mass and thereby contribute to the maintenance of national and international mass scales. This special issue gives an introduction to the diversity of techniques which are required for the operation of watt and joule balances. However it does not contain a review of existing balances; this was a deliberate decision, as a number of such review papers have been published in the past five years [3–7] and it was felt that it was not yet time for another. The first technique considered is that of gravimetry; the watt balance measures the weight Mg of a mass M , and to convert the measured weight into a mass, the value of the acceleration due to gravity g must be known, at the time of the weighing and at the centre of gravity of the mass. The paper by Liard a

Robinson, Ian A.

2014-04-01

102

Flow-calorimetric results for the massic heat capacity c p and the Joule–Thomson coefficient of CH 4 , of (0.85CH 4 + 0.15C 2H 6) , and of a mixture similar to natural gas  

Microsoft Academic Search

As a part of an international project, initiated by the Ruhrgas AG, the massic heat capacity cpand the Joule–Thomson coefficient ?JTwere measured with flow calorimeters. Great effort was made in the designing and construction of the equipment and in the experiments to reach a high accuracy of the results. The pressure range of the measurements was 0.5 MPa to 30

M. Jaeschke

2001-01-01

103

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

Microsoft Academic Search

The heat model of a light-emitting diode (LED) with an InGaN\\/GaN quantum well (QW) in the active region is considered. Effects\\u000a of the temperature and drive current, as well as of the size and material of the heat sink on the light output and efficiency\\u000a of blue LEDs are studied. It is shown that, for optimal heat removal, decreasing of

A. A. Efremov; N. I. Bochkareva; R. I. Gorbunov; D. A. Lavrinovich; Yu. T. Rebane; D. V. Tarkhin; Yu. G. Shreter

2006-01-01

104

Theoretical study on a Miniature Joule–Thomson & Bernoulli Cryocooler  

Microsoft Academic Search

In this paper, a microchannel-based cryocooler consisting of a compressor, a recuperator and a cold heat exchanger has been developed to study the feasibility of cryogenic cooling by the use of Joule–Thomson effect and Bernoulli effect. A set of governing equations including Bernoulli equations and energy equations are introduced and the performance of the cooler is calculated. The influences of

L. Y Xiong; G. Kaiser; A. Binneberg

2004-01-01

105

A Cycling Joule Thomson Refrigerator.  

National Technical Information Service (NTIS)

A symmetrical adsorption pump/compressor system having a pair of mirror image legs and a Joule-Thomson expander, or valve, interposed between the legs thereof for providing a new, efficient refrigeration cycle is described. The system further includes a p...

E. Tward

1981-01-01

106

Multicomponent gas sorption Joule-Thomson refrigeration  

NASA Technical Reports Server (NTRS)

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 disclosed. In a first embodiment, the sorbent geometry is such that a void is defined near the output of the sorption compressor. When the sorbent is cooled, the sorbent primarily adsorbs the higher boiling point gas such that the lower boiling point gas passes through the sorbent to occupy the void. When the sorbent is heated, the higher boiling point gas is desorbed at high temperature and pressure and thereafter propels the lower boiling point gas out of the sorption compressor. A mixing chamber is provided to remix the constituent gases prior to expansion of the gas through a Joule-Thomson valve. Other methods of pumping a multicomponent gas are disclosed. For example, where the sorbent is porous and the low boiling point gas does not adsorb very well, the pores of the sorbent will act as a void space for the lower boiling point gas. Alternatively, a mixed sorbent may be used where a first sorbent component physically adsorbs the high boiling point gas and where the second sorbent component chemically absorbs the low boiling point gas.

Jones, Jack A. (inventor); Petrick, S. Walter (inventor); Bard, Steven (inventor)

1991-01-01

107

Comparison between GITM simulation and JOULE rocket observation  

NASA Astrophysics Data System (ADS)

The JOULE sounding rocket experiment was carried out at the Poker Flat Research Range in Alaska on March 27, 2003. Two instrumented rockets and one chemical tracer rocket were lauched around 12:00UT, which followed many hours of geomagnetically active conditions. They measured the in-situ small-scale electric field, ion velocity and electric density in the upper mesosphere and low thermosphere. From the released trimethyl aluminum (TMA) trails, neutral wind profiles were provided. Since the Global Ionosphere Thermosphere Model (GITM) has a flexible grid structure, sub-degree resolution around the JOULE rocket position can be applied and relatively reasonable results in such a small-scale can be achived. Not only will the simulation results be compared with JOULE observations, but also the comparsion between simulations using different high-latitude drivers will be conducted. It will be shown that using AMIE results produces more accurate neutral wind patterns than empirical models, although the auroral precipitation pattern may be too wide in AMIE, producing too much E- region electron density within GITM. In order to show the significance of spatial variability, GITM will also be run with different resolutions. This study will help us validate the GITM model and understand the significance of small-scale structure to the Joule heating.

Deng, Y.; Ridley, A. J.; Zhan, T.; Larsen, M.; Pfaff, R.

2006-12-01

108

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

109

Theoretical study on a Miniature Joule-Thomson & Bernoulli Cryocooler  

NASA Astrophysics Data System (ADS)

In this paper, a microchannel-based cryocooler consisting of a compressor, a recuperator and a cold heat exchanger has been developed to study the feasibility of cryogenic cooling by the use of Joule-Thomson effect and Bernoulli effect. A set of governing equations including Bernoulli equations and energy equations are introduced and the performance of the cooler is calculated. The influences of some working conditions and structure parameters on the performance of coolers are discussed in details.

Xiong, L. Y.; Kaiser, G.; Binneberg, A.

2004-11-01

110

Joule-Thomson cooling due to CO 2 injection into natural gas reservoirs  

Microsoft Academic Search

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 or heating that accompanies the expansion of a real gas. During CO2 injection into a natural gas

Curtis M. Oldenburg

2007-01-01

111

Ignition and Combustion Behavior in Solid Propellant Microsystems Using Joule-Effect Igniters  

Microsoft Academic Search

A study of solid propellant ignition and combustion of potassium dinitrobenzofuroxanate in Joule-heating pyrotechni- cal microelectromechanical systems igniters is carried out using a high-speed framing camera. The effect of igniter geometry, propel- lant formulation (binder content), fuel mass, and input power level on ignition delay time variability is investigated. Analytical heat transfer models of the ignition process were constructed based

David A. de Koninck; Danick Briand; Laurent Guillot; U. Bley; Volker Gass; Nicolaas F. de Rooij

2011-01-01

112

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

113

Shock-wave compression and Joule-Thomson expansion.  

PubMed

Structurally stable atomistic one-dimensional shock waves have long been simulated by injecting fresh cool particles and extracting old hot particles at opposite ends of a simulation box. The resulting shock profiles demonstrate tensor temperature, Txx?Tyy and Maxwell's delayed response, with stress lagging strain rate and heat flux lagging temperature gradient. Here this same geometry, supplemented by a short-ranged external "plug" field, is used to simulate steady Joule-Kelvin throttling flow of hot dense fluid through a porous plug, producing a dilute and cooler product fluid. PMID:24765974

Hoover, Wm G; Hoover, Carol G; Travis, Karl P

2014-04-11

114

Shock-Wave Compression and Joule-Thomson Expansion  

NASA Astrophysics Data System (ADS)

Structurally stable atomistic one-dimensional shock waves have long been simulated by injecting fresh cool particles and extracting old hot particles at opposite ends of a simulation box. The resulting shock profiles demonstrate tensor temperature, Txx?Tyy and Maxwell's delayed response, with stress lagging strain rate and heat flux lagging temperature gradient. Here this same geometry, supplemented by a short-ranged external "plug" field, is used to simulate steady Joule-Kelvin throttling flow of hot dense fluid through a porous plug, producing a dilute and cooler product fluid.

Hoover, Wm. G.; Hoover, Carol G.; Travis, Karl P.

2014-04-01

115

A model of a subcritical Joule-Thomson cryocooler with condensation inside the recuperator  

NASA Astrophysics Data System (ADS)

To develop a tool for predicting of heat and mass transfer in Joule-Thomson cryocoolers working at subcritical pressures, we study a counter flow heat exchanger with condensation by employing the integral method. The effects of inlet pressure and working fluid are predicted. We also show that there is an optimal value of the enthalpy difference along the heat exchanger for which its length is minimal.

Shusser, M.; Ben-Zvi, I.; Maytal, B.-Z.; Grossman, G.

2009-08-01

116

Proof-of-Principle Measurements of the Superfluid Joule-Thomson Refrigerator Concept  

Microsoft Academic Search

The performance of the first Superfluid Joule-Thomson Refrigerator (SJTR) is described. The SJTR has achieved a low temperature of 0.68 K when exhausting its waste heat to a thermal reservoir at a temperature of 1.2 K. Cooling power versus temperature measurements were conducted with two different throttles and with different compressor speeds

F. K. Miller; J. G. Brisson

2005-01-01

117

The Joule-Thomson Effect in Nitrogen  

Microsoft Academic Search

The measurements were made with the same apparatus and procedure as in the case of argon. The effect of the known impurities in the nitrogen, namely argon and oxygen, can be safely neglected. The data for the isenthalpic curves are given in detail and are plotted. The values of the Joule-Thomson coefficient, mu, over the field (-150 to 300°C and

J. R. Roebuck; H. Osterberg

1935-01-01

118

Multicomponent gas sorption Joule-Thomson refrigeration  

Microsoft Academic Search

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 disclosed. In a first embodiment, the sorbent geometry is such that a void is defined near the output of the sorption compressor. When the sorbent is

Jack A. Jones; S. Walter Petrick; Steven Bard

1991-01-01

119

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

120

Joule-Thomson Coefficients of Confined Ideal Quantum Gases  

NASA Astrophysics Data System (ADS)

By using the pressure and entropy of a system obtained from the grand potential of ideal quantum gases confined in a long tube with a fixed transverse cross section of area and the fundamental relations of thermodynamics, expression for the heat capacity at given longitudinal pressure and area of cross section is derived, from which the linear expansion coefficient and the Joule-Thomson coefficient (JTC) of the system are obtained. Moreover, the effects of the finite size on the heat capacity, expansion coefficient and JTC of the system are discussed in detail. It is significant to find that the absolute values of the JTCs of confined ideal quantum gases increase with the decrease of the systemic size and temperature.

Guo, Juncheng; Su, Guozhen; Chen, Jincan

2011-04-01

121

The Joule–Thomson effect in natural gas flow-rate measurements  

Microsoft Academic Search

A numerical procedure for the calculation of the Joule–Thomson (JT) coefficient of a natural gas is derived. The AGA-8 extended virial-type characterization equation is used to calculate the rate of change of the compression factor with respect to the temperature at constant pressure. The DIPPR\\/AIChE generic ideal heat capacity equations are used to derive the molar heat capacity of a

Ivan Mari?

2005-01-01

122

Hybrid Joule-Thomson cryogenic cooler  

NASA Astrophysics Data System (ADS)

The evolution of the hybrid Joule-Thomson cryogenic cooler is considered, taking into account the Hampson liquifier, the Hampson liquifier with precooler, and the hybrid cryogenic cooler. The Hampson liquifier uses a Joule-Thomson expansion of compressed gas to produce a liquid cryogen. A greater fraction of the gas is converted to liquid if the gas is precooled prior to expansion. The adaption of the process to spaceflight applications is discussed. Attention is given to the range of possible operating temperatures in a hybrid cooler, the refrigeration to mass ratio, problems of fluid management, cooler features and advantages, and applications of the cooler related to maintaining detector and detector-related instruments at the required low temperatures.

Annable, R. V.

123

Joule-Thomson Effect and Quantum Statistics  

Microsoft Academic Search

IN view of the numerous physical and astro-physical applications of the new quantum statistics it may be worth while to investigate the Joule-Thomson effect for a gas obeying Fermi-Dirac or Bose-Einstein statistics. The calculation is simple and runs on the usual lines. The results obtained are quite interesting. It is found that for a degenerate gas, degenerate in the sense

D. S. Kothari; B. N. Srivasava

1937-01-01

124

Joule-Thomson cooling with binary mixtures  

NASA Astrophysics Data System (ADS)

The possibility of achieving temperatures below that of liquid nitrogen for applications in miniature one-shot Joule-Thomson (J-T) coolers using a mixture of nitrogen and neon gases is discussed. An expression for the maximum inversion temperature of binary mixtures is derived. It is shown that it is possible to achieve temperatures near the triple point of nitrogen (63 K) with a mixture of neon and nitrogen.

Sreedhar, R.; Sreedhar, A. K.

1998-12-01

125

Elevated-pressure mixed-coolants Joule Thomson cryocooling  

NASA Astrophysics Data System (ADS)

This paper explores the potential of mixed coolants at elevated pressures for Joule-Thomson cryocooling. A numerical model of a Joule-Thomson cryocooler is developed that is capable of simulating operation with mixtures of up to 9 components consisting of hydrocarbons, non-flammable halogenated refrigerants, and inert gases. The numerical model is integrated with a genetic optimization algorithm, which has a high capability for convergence in an environment of discontinuities, constraints and local optima. The genetic optimization algorithm is used to select the optimal mixture compositions that separately maximizes following two objective functions at each elevated pressure for 80, 90 and 95 K cryocooling: the molar specific cooling capacity (the highest attainable is 3200 J/mol) and the produced cooling capacity per thermal conductance which is a measure of the compactness of the recuperator. The optimized cooling capacity for a non-flammable halogenated refrigerant mixture is smaller than for a hydrocarbon mixture; however, the cooling capacity of the two types of mixtures approach one another as pressure becomes higher. The coefficient of performance, the required heat transfer area and the effect of the number of components in the mixture is investigated as a function of the pressure. It is shown that mixtures with more components provide a higher cooling capacity but require larger recuperative heat exchangers. Optimized mixtures for 90 K cryocooling have similar cooling capacity as those for 80 K. Optimized compactness for 80 K is about 50% higher than can be achieved by pure nitrogen. For 90 K, no mixture provides a more compact recuperator than can be achieved using pure argon. The results are discussed in the context of potential applications for closed and open cycle cryocoolers.

Maytal, B.-Z.; Nellis, G. F.; Klein, S. A.; Pfotenhauer, J. M.

2006-01-01

126

Joule-Thomson Cooler Produces Nearly Constant Temperature  

NASA Technical Reports Server (NTRS)

Improved Joule-Thomson cooler maintains nearly constant temperature. Absolute-pressure relief valve helps stabilize temperature of cold head despite variations in atmospheric pressure. Feedback-controlled electrical heater provides additional stabilization. Demand-flow Joule-Thomson valve requires less nitrogen than fixed-orifice Joule-Thomson valve providing same amount of cooling. Provides stable low temperatures required for operation of such devices as tunable diode lasers in laboratory and balloon-borne instruments detecting contaminants in atmosphere.

Bard, Steven; Wu, Jiunn-Jeng; Trimble, Curtis A.

1992-01-01

127

Spring-Loaded Joule-Thomson Valve  

NASA Technical Reports Server (NTRS)

Improved design reduces clogging and maintains constant pressure drop as flow rate varies. Spring-Loaded Joule-Thomson Valve pressure drop regulated by spring pushing stainless-steel ball against soft brass seat. Pressure drop remains nearly constant, regardless of helium flow rate and of any gas contaminants frozen on valve seat. Because springloaded J-T valve maintains constant pressure drop, upstream roomtemperature throttle valve adjusts flow rate precisely for any given upstream pressure. In addition, new valve relatively invulnerable to frozen gas contaminants, which clog fixed-orifice J-T valves.

Jones, J. A.; Britcliffe, M. J.

1986-01-01

128

Mega-joule experiment area study, 1989  

SciTech Connect

This document contains Chapters 3 and 4 from the Mega-Joule Experiment Area Study, 1989. Water frost on the first containment wall is studied in detail in Chapter 3. Considered topics are the computer modeling of frost ablation and shock propagation and the experimental characterization of water frost. The latter is broken down into: frost crystal morphology, experiment configuration, growth rate results, density results, thermal conductivity, crush strength of frost, frost integrity, frost response to simulated soft x-rays. Chapter 4 presents information on surrounding shielding and structures to include: cryogenic spheres for first wall and coolant containment; shield tank concerning primary neutron and gamma ray shielding; and secondary shielding.

Slaughter, D.; Oirth, C.; Woodworth, J.

1995-03-09

129

A numerical study of the Hampson-type miniature Joule–Thomson cryocooler  

Microsoft Academic Search

The Hampson-type miniature Joule–Thomson (J–T) cryocooler is widely used in electronic cooling. We develop the geometry model of the Hampson-type cryocooler to better understand the double helical tube-and-fin heat exchanger. The steady-state governing equations of the cryogen, helical tube and fins, and shield are solved numerically and yield good agreements with experiment data. The conventional way of simulating a Hampson-type

Hui Tong Chua; Xiaolin Wang; Hwee Yean Teo

2006-01-01

130

Experimental and numerical study on a miniature Joule–Thomson cooler for steady-state characteristics  

Microsoft Academic Search

A miniature Joule–Thomson (JT) cooler with a recuperative heat exchanger is studied, both theoretically and experimentally, for its steady-state behaviors down to 96 K. Two unique aspects of analysis are presented in this paper. Firstly, the simulation employs a distributed approach (as opposed to a black-box) and it is performed with dynamic updating of the thermo-physical properties of the working

K. C. Ng; H. Xue; J. B. Wang

2002-01-01

131

An investigation into the mechanics of Joule-Thomson valve plug formation  

Microsoft Academic Search

Plug formation via contaminant condensation in sonic-flow Joule-Thomson (J-T) orifices was experimentally investigated. The cold end of the experimental apparatus consists of a precooler, a counterflow heat exchanger, and the J-T expander. Nitrogen gas is used as the refrigerant and water vapor is used as the contaminant. Results show that for the straight sonic orifices employed, plug formation occurred only

L. Wade; C. Donnelly; E. Joham; K. Johnson; R. Phillips

1988-01-01

132

Preliminary experimental and numerical study of transient characteristics for a Joule-Thomson cryocooler  

Microsoft Academic Search

To establish a tool for computer-aided design, a preliminary experimental and numerical study of transient characteristics for a Joule-Thomson (J-T) cryocooler is developed in the present work. A simplified transient one-dimensional model of momentum and energy transport is used to simulate the flow and heat transfer characteristics. The computational results for cool-down time agree with the experimental data. The transient

F.-C. Chou; C.-F. Pai; S. B. Chien; J. S. Chen

1995-01-01

133

Improving Control in a Joule-Thomson Refrigerator  

NASA Technical Reports Server (NTRS)

A report discusses a modified design of a Joule-Thomson (JT) refrigerator under development to be incorporated into scientific instrumentation aboard a spacecraft. In most other JT refrigerators (including common household refrigerators), the temperature of the evaporator (the cold stage) is kept within a desired narrow range by turning a compressor on and off as needed. This mode of control is inadequate for the present refrigerator because a JT-refrigerator compressor performs poorly when the flow from its evaporator varies substantially, and this refrigerator is required to maintain adequate cooling power. The proposed design modifications include changes in the arrangement of heat exchangers, addition of a clamp that would afford a controlled heat leak from a warmer to a cooler stage to smooth out temperature fluctuations in the cooler stage, and incorporation of a proportional + integral + derivative (PID) control system that would regulate the heat leak to maintain the temperature of the evaporator within a desired narrow range while keeping the amount of liquid in the evaporator within a very narrow range in order to optimize the performance of the compressor. Novelty lies in combining the temperature- and cooling-power-regulating controls into a single control system.

Borders, James; Pearson, David; Prina, Mauro

2005-01-01

134

Ultra-high temperature stability Joule-Thomson cooler with capability to accomodate pressure variations  

NASA Technical Reports Server (NTRS)

A Joule-Thomson cryogenic refrigeration system capable of achieving high temperature stabilities in the presence of varying temperature, atmospheric pressure, and heat load is provided. The Joule-Thomson cryogenic refrigeration system includes a demand flow Joule-Thomson expansion valve disposed in a cryostat of the refrigeration system. The expansion valve has an adjustable orifice that controls the flow of compressed gas therethrough and induces cooling and partial liquefaction of the gas. A recuperative heat exchanger is disposed in the cryostat and coupled to the expansion valve. A thermostatically self-regulating mechanism is disposed in the cryostat and coupled to the J-T expansion valve. The thermostatically self-regulating mechanism automatically adjusts the cross sectional area of the adjustable valve orifice in response to environmental temperature changes and changes in power dissipated at a cold head. A temperature sensing and adjusting mechanism is coupled to a cold head for adjusting the temperature of the cold head in response to the change in heat flow in the cold head. The temperature sensing and adjusting mechanism comprises a temperature sensitive diode, a wound wire heater, and an electrical feedback control circuit coupling the diode to the heater. An absolute pressure relief valve is interposed between the output of the cryostat and an exhaust port for maintaining a constant exhaust temperature in the refrigerating system, independent of the changes in atmospheric pressure.

Bard, Steven (inventor); Wu, Jiunn-Jeng (inventor); Trimble, Curtis A. (inventor)

1992-01-01

135

Ultra-high temperature stability Joule-Thomson cooler with capability to accomodate pressure variations  

NASA Astrophysics Data System (ADS)

A Joule-Thomson cryogenic refrigeration system capable of achieving high temperature stabilities in the presence of varying temperature, atmospheric pressure, and heat load is provided. The Joule-Thomson cryogenic refrigeration system includes a demand flow Joule-Thomson expansion valve disposed in a cryostat of the refrigeration system. The expansion valve has an adjustable orifice that controls the flow of compressed gas therethrough and induces cooling and partial liquefaction of the gas. A recuperative heat exchanger is disposed in the cryostat and coupled to the expansion valve. A thermostatically self-regulating mechanism is disposed in the cryostat and coupled to the J-T expansion valve. The thermostatically self-regulating mechanism automatically adjusts the cross sectional area of the adjustable valve orifice in response to environmental temperature changes and changes in power dissipated at a cold head. A temperature sensing and adjusting mechanism is coupled to a cold head for adjusting the temperature of the cold head in response to the change in heat flow in the cold head. The temperature sensing and adjusting mechanism comprises a temperature sensitive diode, a wound wire heater, and an electrical feedback control circuit coupling the diode to the heater. An absolute pressure relief valve is interposed between the output of the cryostat and an exhaust port for maintaining a constant exhaust temperature in the refrigerating system, independent of the changes in atmospheric pressure.

Bard, Steven; Wu, Jiunn-Jeng; Trimble, Curtis A.

1992-06-01

136

Minimal Joule dissipation models of magnetospheric convection  

NASA Technical Reports Server (NTRS)

This paper gives a topical review of theoretical models of magnetospheric convection based on the concept of minimal Joule dissipation. A two-dimensional slab model of the ionosphere featuring an enhanced conductivity auroral oval is used to compute high-latitude electric fields and currents. Mathematical methods used in the modeling include Fourier analysis, fast Fourier transforms, and variational calculus. Also, conformal transformations are introduced in the analysis, which enable the auroral oval to be represented as a nonconcentric, crescent-shaped figure. Convection patterns appropriate to geomagnetic quiet and disturbed conditions are computed, the differentiating variable being the relative amount of power dissipated in the magnetospheric ring current. When ring current dissipation is small, the convection electric field is restricted to high latitudes (shielding regime), and when it is large, a significant penetration of the field to low latitudes occurs, accompanied by an increase in the ratio of the region I current to the region 2 current.

Barbosa, D. D.

1988-01-01

137

Joule-Thompson cooler fabricated from microtubes of different diameters  

NASA Astrophysics Data System (ADS)

Joule-Thomson (JT) coolers have been widely used for cooling optoelectronic devices and for cryogenic applications. In the present investigation the performance and behaviors of a JT cooler fabricated from micro tubes of different diameters were studied. The cooler was comprised of circular tubes with diameters ranging from less than a hundred microns to a couple of millimeters. The smallest tube serves as a throttling device while the other tubes were used to fabricate a concentric-tube heat exchanger. Temperature drops were measured for nitrogen gas flowing through capillary tubes of different diameters and lengths. Gas dynamic theories were employed for analyzing the high- pressure gas flow in the JT cooler. Friction choking was observed under normal operating conditions, with strong compression and expansion waves appearing at the exit of the throttling tube. The simple design and configuration of the present JT cooler makes it suitable for batch fabrication using the photo lithography technique if the circular tubes are replaced by etched micron channels. This attractive feature of the micro-tube JT cooler can facilitate the integration of high-power optoelectronic devices and their cooling systems.

Chen, Kuan H.; Chen, Jing-Yu

1999-11-01

138

Mixed refrigerant Joule-Thomson sorption cryocoolers  

NASA Astrophysics Data System (ADS)

Joule-Thomson (JT) sorption cryocooling is the most mature technology for cooling from a normal Room-Temperature (RT) down to temperatures below 100 K in the absence of moving parts. Therefore, high reliability and no vibrations are attainable, in comparison with other cryocoolers. Cooling to 80 - 100 K with JT cryocoolers is often implemented with pure nitrogen. Alternatively, mixed refrigerants have been suggested for reducing the operating pressures to enable closed cycle cryocooling. There is a variety of publications describing nitrogen sorption cryocoolers with different configurations of sorption compressors. In the present research we suggest a novel sorption JT cryocooler that operates with a mixed refrigerant. Merging of sorption cryocooling and a mixed refrigerant enables the use of a simple, single stage compressor for cooling to 80 - 100 K, lower operating temperatures of the sorption cycle, and thus - reduced power consumption. In previous studies we have analyzed sorption compressors for mixed gases and mixed refrigerants for JT cryocoolers, separately. In this paper the option of mixed refrigerant sorption JT cryocoolers is explored. The considerations for developing mixed refrigerants to be driven by sorption compressors and to be utilized with JT cryocoolers are provided. It appears that, unlike with pure nitrogen, mixed refrigerants can be suitable for JT cryocooling with a single stage sorption compressor.

Tzabar, Nir; Grossman, Gershon

2014-01-01

139

The Joule-Thomson expansion coefficient by formula manipulation  

SciTech Connect

By use of formula manipulation, practical programs used to estimate the Joule-Thomson coefficients are presented in this paper. The available equations of state used include the following: van der Waals, Virial, BWR, RK, and SRK. The Joule-Thomson coefficients for nitrogen and ethane are estimated by the proposed programs, and their ability to reproduce experimental values is tested. It is found that the RK equation yields the best results for nitrogen and ethane despite its simplicity.

Hirose, Y.; Kitazawa, T. (Dept. of Industrial Chemistry, Faculty of Engineering, Tokyo Metropolitan Univ., Tokyo 158 (JP)); Yoshida, T. (Chiba Univ. (Japan). Faculty of Engineering)

1990-07-01

140

Elevated-pressure mixed-coolants Joule–Thomson cryocooling  

Microsoft Academic Search

This paper explores the potential of mixed coolants at elevated pressures for Joule–Thomson cryocooling. A numerical model of a Joule–Thomson cryocooler is developed that is capable of simulating operation with mixtures of up to 9 components consisting of hydrocarbons, non-flammable halogenated refrigerants, and inert gases. The numerical model is integrated with a genetic optimization algorithm, which has a high capability

B.-Z. Maytal; G. F. Nellis; S. A. Klein; J. M. Pfotenhauer

2006-01-01

141

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

Microsoft Academic Search

Based on the form of the n-dimensional generic power-law potential, the state equation and the heat capacity, the analytical expressions of the Joule-Thomson coefficient (JTC) for an ideal Bose gas are derived in n-dimensional potential. The effect of the spatial dimension and the external potential on the JTC are discussed, respectively. These results show that: (i) For the free ideal

Du-Qi Yuan; Can-Jun Wang

2010-01-01

142

Heat Pump Cycle with an Air--Water Working Fluid.  

National Technical Information Service (NTIS)

A new thermodynamic cycle for heat pumps is discussed. The cycle resembles the Joule cycle in that it consists of an isentropic compression, a constant pressure heat rejection, an isentropic expansion with work recovery, and a constant pressure heat addit...

E. C. Hise J. V. Wilson

1977-01-01

143

Program For Joule-Thomson Analysis Of Mixed Cryogens  

NASA Technical Reports Server (NTRS)

JTMIX computer program predicts ideal and realistic properties of mixed gases at temperatures between 65 and 80 K. Performs Joule-Thomson analysis of any gaseous mixture of neon, nitrogen, various hydrocarbons, argon, oxygen, carbon monoxide, carbon dioxide, and hydrogen sulfide. When used in conjunction with DDMIX computer program of National Institute of Standards and Technology (NIST), JTMIX accurately predicts order-of-magnitude increases in Joule-Thomson cooling capacities occuring when various hydrocarbons added to nitrogen. Also predicts boiling temperature of nitrogen depressed from normal value to as low as 60 K upon addition of neon. Written in Turbo C.

Jones, Jack A.; Lund, Alan

1994-01-01

144

Communication: Ab initio Joule-Thomson inversion data for argon  

NASA Astrophysics Data System (ADS)

The Joule-Thomson coefficient ?H(P, T) is computed from the virial equation of state up to seventh-order for argon obtained from accurate ab initio data. Higher-order corrections become increasingly more important to fit the low-temperature and low-pressure regime and to avoid the early onset of divergence in the Joule-Thomson inversion curve. Good agreement with experiment is obtained for temperatures T > 250 K. The results also illustrate the limitations of the virial equation in regions close to the critical temperature.

Wiebke, Jonas; Senn, Florian; Pahl, Elke; Schwerdtfeger, Peter

2013-02-01

145

Communication: Ab initio Joule-Thomson inversion data for argon.  

PubMed

The Joule-Thomson coefficient ?(H)(P, T) is computed from the virial equation of state up to seventh-order for argon obtained from accurate ab initio data. Higher-order corrections become increasingly more important to fit the low-temperature and low-pressure regime and to avoid the early onset of divergence in the Joule-Thomson inversion curve. Good agreement with experiment is obtained for temperatures T > 250?K. The results also illustrate the limitations of the virial equation in regions close to the critical temperature. PMID:23444990

Wiebke, Jonas; Senn, Florian; Pahl, Elke; Schwerdtfeger, Peter

2013-02-21

146

Mixed-Gas Sorption Joule-Thomson Refrigerator  

NASA Technical Reports Server (NTRS)

Proposed mixed-gas sorption Joule-Thomson refrigerator provides cooling down to temperature of 70 K. Includes only one stage and no mechanical compressor. Simpler, operates without vibrating, and consumes less power in producing same amount of cooling. Same sorption principle of operation applicable in compressor that chemisorbs oxygen or hydrogen from mixture with helium, neon, and/or other nonreactive gases.

Jones, Jack A.; Petrick, S. Walter; Bard, Steven

1991-01-01

147

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

148

Molecular Simulation of Joule–Thomson Inversion Curves  

Microsoft Academic Search

A method to determine Joule–Thomson inversion curves, using isobaric-isothermal Monte Carlo molecular simulations, is presented. The usual experimental practice to obtain the locus of points in which the isenthalpic derivative of temperature with respect to pressure vanishes is to process volumetric data by means of thermodynamic relations. This experimental procedure requires the very precise measurement of volumetric properties at conditions

C. M. Colina; E. A. Müller

1999-01-01

149

Thermodynamic optimization of sorption-based Joule–Thomson coolers  

Microsoft Academic Search

A cooler consisting of a sorption compressor with a Joule–Thomson (JT) cold stage has several advantages. These coolers have no moving parts which is attractive for a variety of reasons. Unfortunately, the efficiency of sorption-based JT coolers is in many cases relatively small. This paper presents a thermodynamic description of the compressor and the cold stage separately. Their efficiencies are

G. F. M. Wiegerinck; H. J. M. ter Brake; J. F. Burger; H. J. Holland; H. Rogalla

2007-01-01

150

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

National Technical Information Service (NTIS)

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 grou...

T. N. Narasimhan

1999-01-01

151

Regnault's Experiments on the Joule-Thomson Effect  

Microsoft Academic Search

THAT Regnault made a number of experiments similar to some of those described by Joule and Kelvin in their papers on the thermal effects of fluids in motion does not seem to be commonly known; at all events, the numerical results of his work on this subject are not often mentioned. After experimenting on the flow of gases through small

Edgar Buckingham

1907-01-01

152

Joule–Thomson coefficients of quantum ideal-gases  

Microsoft Academic Search

The temperature drop of a gas divided by its pressure drop under constant enthalpy conditions is called the Joule–Thomson coefficient (JTC) of the gas. The JTC of an ideal gas is equal to zero since its enthalpy depends on only temperature. On the other hand, this is only true for classical ideal gas which obeys the classical ideal gas equation

Hasan Sayg?n; Altu? ?i?man

2001-01-01

153

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

154

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

155

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

156

Optimization of the working fluid for a sorption-based Joule-Thomson cooler  

NASA Astrophysics Data System (ADS)

Sorption-based Joule-Thomson coolers operate vibration-free, have a potentially long life time, and cause no electromagnetic interference. Therefore, they are appealing to a wide variety of applications, such as cooling of low-noise amplifiers, superconducting electronics, and optical detectors. The required cooling temperature depends on the device to be cooled and extends into the cryogenic range well below 80 K. This paper presents the optimization of the working fluid for sorption-based JT coolers. For specific combination of the cold and warm-end temperatures, the working fluid is optimized based on the overall coefficient of performance that is defined as the heat rejected to the cold tip (i.e. the cooling energy) per unit of the heat supplied to the sorption compressor. In this study, saran carbon is considered as the sorbent material.

Wu, Y.; Zalewski, D. R.; ter Brake, Marcel

2012-06-01

157

Joule-Thomson coefficient of ideal anyons within fractional exclusion statistics  

NASA Astrophysics Data System (ADS)

The analytical expressions of the Joule-Thomson coefficient for homogeneous and harmonically trapped three-dimensional ideal anyons which obey Haldane fractional exclusion statistics are derived. For an ideal Fermi gas, the Joule-Thomson coefficient is negative, which means that there is no maximum Joule-Thomson inversion temperature. With careful study, it is found that there exists a Joule-Thomson inversion temperature in the fractional exclusion statistics model. Furthermore, the relations between the Joule-Thomson inversion temperature and the statistical parameter g are investigated.

Qin, Fang; Chen, Ji-Sheng

2011-02-01

158

Joule-Thomson coefficient of ideal anyons within fractional exclusion statistics.  

PubMed

The analytical expressions of the Joule-Thomson coefficient for homogeneous and harmonically trapped three-dimensional ideal anyons which obey Haldane fractional exclusion statistics are derived. For an ideal Fermi gas, the Joule-Thomson coefficient is negative, which means that there is no maximum Joule-Thomson inversion temperature. With careful study, it is found that there exists a Joule-Thomson inversion temperature in the fractional exclusion statistics model. Furthermore, the relations between the Joule-Thomson inversion temperature and the statistical parameter g are investigated. PMID:21405822

Qin, Fang; Chen, Ji-sheng

2011-02-01

159

Joule-Thomson coefficient of ideal anyons within fractional exclusion statistics  

SciTech Connect

The analytical expressions of the Joule-Thomson coefficient for homogeneous and harmonically trapped three-dimensional ideal anyons which obey Haldane fractional exclusion statistics are derived. For an ideal Fermi gas, the Joule-Thomson coefficient is negative, which means that there is no maximum Joule-Thomson inversion temperature. With careful study, it is found that there exists a Joule-Thomson inversion temperature in the fractional exclusion statistics model. Furthermore, the relations between the Joule-Thomson inversion temperature and the statistical parameter g are investigated.

Qin Fang; Chen Jisheng [Physics Department and Institute of Nanoscience and Nanotechnology, Central China Normal University, Wuhan 430079 (China)

2011-02-15

160

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

161

Joule-Thomson Inversion Curves by Molecular Simulation  

Microsoft Academic Search

A method to determine Joule-Thomson inversion curves, using isobaric-isothermal Monte Carlo molecular simulations, is presented. Volumetric data obtained through the simulations is interpreted by means of thermodynamic relations to obtain the locus of points in which the isenthalpic derivative of temperature with respect to pressure vanishes. The procedure is exemplified for a Lennard-Jones fluid and the low-temperature branch of the

Coray Colina; Erich A. Müller

1997-01-01

162

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

163

Improving the performance of small Joule–Thomson cryocooler  

Microsoft Academic Search

This paper presents a new cycle for improving the performance of small Joule–Thomson (JT) cryocooler by applying an additional ejector in cycle system. Based on the presented JT cycle with an additional ejector (JTE), the performance of small JT cryocooler operating with pure N2 and the mixture N2?CH4 for cryogenic applications in a temperature range of 80–130K is investigated by

Jianlin Yu

2008-01-01

164

Development of a Mixed-Refrigerant Joule-Thomson Microcryocooler  

Microsoft Academic Search

We discuss in this paper the development of a mixed-refrigerant Joule-Thomson microcryocooler (MCC) to support on-chip cooling of high temperature superconducting electronics that require less than 5 mW of net refrigeration at about 80 K. Some applications include the cooling of infrared and terahertz imaging sensors that operate at about 77 K. Terahertz sensors can be used for the imaging

P. E. Bradley; R. Radebaugh; M. Huber

165

Development of a Piezoelectric Microcompressor for a Joule Thomson Microcryocooler  

Microsoft Academic Search

In this paper we discuss the development of a microcompressor (MC) theoretically capable of delivering pressure ratios from 16:1 to 25:1 for design flow rates, of about 0.15 std. cm 3 \\/s, intended to provide flow for a mixed refrigerant Joule-Thomson (J-T) microcryocooler. The J-T microcryocooler supports on-chip cooling applications, such as terahertz and infrared imaging sen- sors operating at

M. J. Simon; C. DeLuca; Y. C. Lee; P. E. Bradley; R. Radebaugh

166

Joule—Thomson effect in liquid He II  

NASA Astrophysics Data System (ADS)

It has been shown in the present study that the Joule—Thomson coefficients of liquid He II are extraordinarily high for temperatures far below the lambda point as compared with ordinary real gases or liquids. Its effect on the throttling process of He II was shown to be quite significant and should be taken into account when dealing with transport processes of He II.

Huang, B. J.

167

Ion Flow Measurements from the JOULE Sounding Rocket Mission  

NASA Astrophysics Data System (ADS)

The JOULE sounding rocket mission was designed to investigate structured Joule dissipation in the auroral ionosphere. JOULE was launched March 27, 2003 from Poker Flat, Alaska, during a substorm. The mission included two instrumented rockets and two chemical release (TMA) rockets. One of the instrumented payloads carried a Suprathermal Ion Imager (SII) that measured 2-D (energy/angle) distributions of the core (0- 8 eV) ion population at a rate of 125 per second. SII measured one component of the ion drift velocitiy perpendicular to the magnetic field and the field-aligned component of the ion drift velocity. We present results showing good agreement between ion drifts measured perpendicular to the geomagnetic field and those inferred from an ?c E×?c B measurement, with signs of ion demagnetization as the payload reached the upper E region. Also, the SII shows evidence of downward field-aligned ion flows at altitudes of 140-170 km within a region of enhanced auroral precipitation.

Sangalli, L.; Knudsen, D.; Pfaff, R.; Burchil, J.; Larsen, M.; Clemmons, J.; Steigies, C.

2006-12-01

168

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

169

A miniature Joule-Thomson cooler for optical detectors in space.  

PubMed

The utilization of single-stage micromachined Joule-Thomson (JT) coolers for cooling small optical detectors is investigated. A design of a micromachined JT cold stage-detector system is made that focuses on the interface between a JT cold stage and detector, and on the wiring of the detector. Among various techniques, adhesive bonding is selected as most suitable technique for integrating the detector with the JT cold stage. Also, the optimum wiring of the detector is discussed. In this respect, it is important to minimize the heat conduction through the wiring. Therefore, each wire should be optimized in terms of acceptable impedance and thermal heat load. It is shown that, given a certain impedance, the conductive heat load of electrically bad conducting materials is about twice as high as that of electrically good conducting materials. A micromachined JT cold stage is designed and integrated with a dummy detector. The JT cold stage is operated at 100 K with nitrogen as the working fluid and at 140 K with methane. Net cooling powers of 143 mW and 117 mW are measured, respectively. Taking into account a radiative heat load of 40 mW, these measured values make the JT cold stage suitable for cooling a photon detector with a power dissipation up to 50 mW, allowing for another 27 to 53 mW heat load arising from the electrical leads. PMID:22559586

Derking, J H; Holland, H J; Tirolien, T; ter Brake, H J M

2012-04-01

170

A miniature Joule-Thomson cooler for optical detectors in space  

NASA Astrophysics Data System (ADS)

The utilization of single-stage micromachined Joule-Thomson (JT) coolers for cooling small optical detectors is investigated. A design of a micromachined JT cold stage-detector system is made that focuses on the interface between a JT cold stage and detector, and on the wiring of the detector. Among various techniques, adhesive bonding is selected as most suitable technique for integrating the detector with the JT cold stage. Also, the optimum wiring of the detector is discussed. In this respect, it is important to minimize the heat conduction through the wiring. Therefore, each wire should be optimized in terms of acceptable impedance and thermal heat load. It is shown that, given a certain impedance, the conductive heat load of electrically bad conducting materials is about twice as high as that of electrically good conducting materials. A micromachined JT cold stage is designed and integrated with a dummy detector. The JT cold stage is operated at 100 K with nitrogen as the working fluid and at 140 K with methane. Net cooling powers of 143 mW and 117 mW are measured, respectively. Taking into account a radiative heat load of 40 mW, these measured values make the JT cold stage suitable for cooling a photon detector with a power dissipation up to 50 mW, allowing for another 27 to 53 mW heat load arising from the electrical leads.

Derking, J. H.; Holland, H. J.; Tirolien, T.; ter Brake, H. J. M.

2012-04-01

171

Preliminary experimental and numerical study of transient characteristics for a Joule-Thomson cryocooler  

NASA Astrophysics Data System (ADS)

To establish a tool for computer-aided design, a preliminary experimental and numerical study of transient characteristics for a Joule-Thomson (J-T) cryocooler is developed in the present work. A simplified transient one-dimensional model of momentum and energy transport is used to simulate the flow and heat transfer characteristics. The computational results for cool-down time agree with the experimental data. The transient temperature variations of high pressure gas, tube wall, low pressure gas, glass Dewar and mandrel at the grid point near the valve exit are shown. From the spatial temperature distributions of high and low pressure gases along the finned tube at the moment of cool-down, it is proposed that the J-T cooler currently used may be reduced in terms of both size and weight; factors which are very important in a miniature J-T cryocooler.

Chou, F.-C.; Pai, C.-F.; Chien, S. B.; Chen, J. S.

172

Temperature instability comparison of micro- and mesoscale Joule-Thomson cryocoolers employing mixed refrigerants  

NASA Astrophysics Data System (ADS)

Previously we demonstrated cryogenic cooling in a Joule-Thomson (JT) microcryocooler (MCC) with mixed refrigerants operating at pressure ratios of 16:1 that achieved stable temperatures of 140 K, with transient temperatures down to 76 K, with precooling of the refrigerant to 240 K. Pre-cooling improves the minimum enthalpy difference, (?hhT)min compared with that of pure fluids. Micro-scale compressors have been unavailable to meet 16:1 ratios. By reducing the ratio to 4:1, mini-compressors become viable in the near term. Utilizing mixed refrigerants optimized for 4:1 pressure ratios we compare the performance stability of this micro-JT employing a 25 mm long multichannel glass fiber heat exchanger (outer low-pressure capillary ID/OD=536 ?m/617 ?m, inner high-pressure channels ID/OD=75 ?m/125 ?m) with a scaled up (meso-scopic) version employing a 20 cm long single channel stainless steel heat exchanger (outer low pressure channel ID/OD=580 ?m/760 ?m, inner high pressure channel ID/OD=150 ?m/266 ?m). This easy to fabricate and modify meso-scale version was fabricated to investigate the temperature instabilities of mixed refrigerants for similar operating conditions but for proportionally higher flows of ~ 30 cm3/min compared with ~ 10 cm3/min. We compare measured pressures, flow rates, temperatures, and stabilities for both micro- and meso-JT cryocoolers to better understand the causes for the temperature instabilities within the micro-JT cryocooler. KEYWORDS: Cryocooler, Joule-Thomson, microcryocooler, micro-JT, mixed

Bradley, Peter; Radebaugh, Ray; Lewis, R. J.; Lin, M.-H.; Lee, Y. C.

2012-06-01

173

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

SciTech Connect

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 a much-better-defined thickness than can be laid down using the older screen printing method; redesign of H/sub 2/ refrigerator test stage, redesign of mixed-gas heat exchanger, refrigerator fabrication, and gas cleaner.

Little, W.A.

1987-06-15

174

Development of a two-stage alternate Joule-Thomson cryo-cooler for AAWS-M risk reduction  

NASA Astrophysics Data System (ADS)

The latest in infrared imaging Focal Plane Array (FPA) technology incorporates Mercury Cadmium Telluride, a material that must be cooled to liquid nitrogen temperatures for operation. Fast cool-down, within five seconds, has been achieved under a harsh temperature environment (71 C). A Joule-Thomson Cryo-cooler employing two heat exchanger stages has been developed. High pressure krypton flows through one stage, providing initial pre-cooling, while high pressure nitrogen simultaneously flows through the other stage. The two-stage gas flow approach along with the superior pre-cooling properties of Krypton enable cool-down times of under five seconds.

Pope, Alan W.; Miller, Walter E.

1991-11-01

175

Direct molecular-level Monte Carlo simulation of Joule-Thomson processes  

Microsoft Academic Search

We present an application of the recently developed constant enthalpy-constant pressure Monte Carlo method [Smith, W. R., and Lísal, M., 2002, Phys. Rev. E, 66, 01114] for the direct simulation of Joule-Thomson expansion processes using a molecular-level system model. For the alternative refrigerant HFC-32 (CH2F2), we perform direct simulations of the isenthalpic integral Joule-Thomson effect (temperature drop) resulting from Joule-Thomson

Martin Lísal; William R. Smith; Karel Aim

2003-01-01

176

Joule-Thomson Cooling Due to CO2 Injection into Natural GasReservoirs  

Microsoft Academic Search

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

Curtis M

2006-01-01

177

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

178

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

179

CLOG RETARD OF A VORTEX THROTTLE JOULE-THOMSON CRYOCOOLER: FURTHER EXPERIMENTAL VERIFICATION  

Microsoft Academic Search

The demand of high purity gas supply for Joule-Thomson cryocoolers and liquefiers is crucial in order to avoid plug formation at the delicate throttling device. A throttle which would tolerate higher level of contamination is greatly desirable for more reliable operation. The vortex throttle has such a potential. A series of vortex throttles were applied to a miniature Joule-Thomson cryocooler

B.-Z. Maytal

2010-01-01

180

Clog Retard of a Vortex Throttle Joule-Thomson Cryocooler: Further Experimental Verification  

Microsoft Academic Search

The demand of high purity gas supply for Joule-Thomson cryocoolers and liquefiers is crucial in order to avoid plug formation at the delicate throttling device. A throttle which would tolerate higher level of contamination is greatly desirable for more reliable operation. The vortex throttle has such a potential. A series of vortex throttles were applied to a miniature Joule-Thomson cryocooler

B.-Z. Maytal

2010-01-01

181

On the connection of Joule-Thompson's coefficient with dissipation properties of filtrating media  

NASA Astrophysics Data System (ADS)

In the paper is shown that the Joule-Thompson's coefficient may be connected with dissipation properties of filtrating liquid or gas. The calculations are based on the classical Boltzmann's kinetic equation. The connection between Joule-Thompson's coefficient and the viscosity of liquid is found.

Gladkov, S. O.

2003-02-01

182

Experimental verification of a precooled mixed gas Joule-Thomson cryoprobe model  

NASA Astrophysics Data System (ADS)

Cryosurgery is a medical technique that uses a cryoprobe to apply extreme cold to undesirable tissue such as cancers. Precooled Mixed Gas Joule-Thomson (pMGJT) cycles with Hampson-style recuperators are integrated with the latest generation of cryoprobes to create more powerful and compact instruments. Selection of gas mixtures for these cycles is not a trivial process; the focus of this research is the development of a detailed model that can be integrated with an optimization algorithm to select optimal gas mixtures. A test facility has been constructed to experimentally tune and verify this model. The facility uses a commercially available cryoprobe system that was modified to integrate measurement instrumentation sufficient to determine the performance of the system and its component parts. Spatially resolved temperature measurements allow detailed measurements of the heat transfer within the recuperator and therefore computation of the spatially resolved conductance. These data can be used to study the multiphase, multicomponent heat transfer process in the complicated recuperator geometry. The optimization model has been expanded to model the pressure drop associated with the flow to more accurately predict the performance of the system. The test facility has been used to evaluate the accuracy and usefulness of this improvement.

Passow, Kendra Lynn; Skye, Harrison; Nellis, Gregory; Klein, Sanford

2012-06-01

183

Joule-Thomson cryogenic cooler with extremely high thermal stability  

NASA Technical Reports Server (NTRS)

An 80-K Joule-Thomson (J-T) cooling system designed for the Probe Infrared Laser Spectrometer (PIRLS) proposed for the Huygens Titan Probe of the Cassini Saturn orbiter mission is presented. The cryogenic cooling requirements of the PIRLS instrument are listed, and the cooler system design including details of a J-T cryostat, cold head, and dewar design is described along with the results of a thermal modeling effort and lab cooler performance testing. It is shown that by using active feedback temperature control of the cold head in combination with the self-regulating action of the J-T cryostat, a temperature stability of less than 0.1 mK/min is achieved by the cooler weighting 1.8 kg.

Bard, Steven; Wu, J. J.; Trimble, Curt

1991-01-01

184

One Joule per GFlop for BLAS2 Now!  

NASA Astrophysics Data System (ADS)

Energy consumption is today one of the major topics that the HPC community tries to tackle. In this paper, the authors present a thought experiment aiming at building a node of a supercomputer based on a GPU (Nvidia GTX280). The paper concentrate on BLAS2 operations that dominate many scientific applications. They show that it is already possible today to build a node that is able to perform one GFlop while consuming only one Joule. This corresponds to an energy reduction by one to two orders of magnitude. Technical limitations imposed by computer manufacturers hinder the realisation of such ecological resources. In a second part of the paper a new FLOPS-driven governor is presented aiming at boosting the CPU performance for applications that are not main memory access bound, and showing results on an Intel mobile processor.

Keller, Vincent; Gruber, Ralf

2010-09-01

185

Mixed-refrigerant Joule-Thomson (MR JT) mini-cryocoolers  

NASA Astrophysics Data System (ADS)

This paper presents the progress in our ongoing research on Mixed-Refrigerant (MR) Joule-Thomson (JT) cryocoolers. The research begun by exploring different MRs and testing various compressors: oil-lubricated and oil-free, reciprocating and linear, custom-made and commercial. Closed-cycle JT cryocoolers benefit from the fact that the compressor might be located far from the cold-end and thus there are no moving parts, no vibrations, and no heat emission near the cold-end. As a consequence, the compressor may be located where there are no severe size limitations, its heat can be conveniently removed, and it can be easily maintained. However, in some applications there is still a demand for a small compressor to drive a JT cryocooler although it is located far from the cooled device. Recently, we have developed a miniature oil-free compressor for MR JT cryocoolers that weighs about 700 g and its volume equals about 300 cc. The cryocooler operates with a MR that contains Ne, N2, and Hydrocarbons. This MR has been widely investigated with different compressors and varying operating conditions and proved to be stable. The current research investigates the performances of MR JT mini-cryocooler operating with the MR mentioned above, driven with our miniature compressor, and a cold-finger prototype. A Dewar with heat load of about 230 mW is cooled to about 80 K at ambient temperatures between 0°C and 40°C. The experimental results obtained are stable and demonstrate the ability to control the cooling temperature by changing the rotation speed of the compressor.

Tzabar, Nir

2014-01-01

186

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

NASA Astrophysics Data System (ADS)

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-T devices to maintain tank fluid pressure and temperature. Previous experimental investigations have indicated that J-T devices may become clogged when flowing LH2 while operating at a temperature range from 20.5 K to 24.4 K. It has been proposed that clogging is due to a trace amount of metastable, supercooled liquid neon in the regular LH2 supply. In time, flow blockage occurs from accretion of solid neon on the orifice. This clogging poses a realistic threat to spacecraft propulsion systems utilizing J-T devices in cryogenic pressure control systems. TVS failure due to J-T clogging would prevent removal of environmental heat from the propellant and potential loss of mission. This report describes J-T clogging tests performed with LH2. Tests were performed in the expected Lunar Lander operating regime, and several methods were evaluated to determine the optimum approach to mitigating the potential risk of J-T clogging.

Jurns, J. M.

2010-04-01

187

Investigation of the gas-solid Joule-Thomson effect for argon-, nitrogen-, and carbon dioxide-carbon powder aerosol systems  

SciTech Connect

An apparatus was constructed to disperse a fine powder in a flowing gas and measure the thermal changes associated with a pressure drop across a glass orifice. The gas-solid Joule-Thomson effect was examined for 12 different gas-solids systems at a temperature of 302 K, a downstream pressure of 120 kPa, pressure drops across the orifice from 5 to 45 kPa, flow rates from 2 to 14 mmol/s, and aerosol concentrations from 0 to 16 g of powder/mol of gas. The gaseous component included either argon, nitrogen, or carbon dioxide and the particulate component included either Mexican Graphite (26 m/sup 2//g), Nuchar S-C (903 m/sup 2//g), Nuchar S-A (1661 m/sup 2//g), or Super Sorb (3169 m/sup 2//g) carbon powder. A significant enhancement of the Joule-Thomson cooling effect was found for gas-porous carbon systems relative to a pure gas. The dependence of the magnitude of this effect on the gas-gas and gas-solid interactions was predicted from a virial equation of state based on statistical thermodynamic considerations. Gas-solid virial coefficients and their temperature derivatives were used in conjunction with the theoretical model as modified by heat-transport effects to assess the reliability of theory in predicting the experimentally determined gas-solid Joule-Thomson coefficients.

Rybolt, T.R.; Pierotti, R.A.

1984-05-24

188

Joule-Thomson Cooling Due to CO2 Injection into Natural Gas Reservoirs.  

National Technical Information Service (NTIS)

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....

C. M. Oldenburg

2006-01-01

189

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

190

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

191

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

192

The Joule-Thomson Coefficient for Pure Gases and Their Mixtures  

Microsoft Academic Search

The properties of the Joule-Thomson coefficient are discussed in general for pure gases, and the possibility of a nonlinear effect in binary mixtures is analyzed using the First Law of Thermodynamics and some common cubic equations of state. It is shown that although theoretically a binary mixture of gases may exhibit a Joule-Thomson effect different from the molar-weighted mean of

Jaime Wisniak

1999-01-01

193

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

194

Characteristics of Subcooled Liquid Methane During Passage Through a Spray-Bar Joule-Thompson Thermodynamic Vent System  

NASA Technical Reports Server (NTRS)

NASA s Marshall Space Flight Center (MSFC) conducted liquid methane (LCH4) testing in November 2006 using the multipurpose hydrogen test bed (MHTB) outfitted with a spray-bar thermodynamic vent system (TVS). The basic objective was to identify any unusual or unique thermodynamic characteristics associated with subcooled LCH4 that should be considered in the design of space-based TVSs. Thirteen days of testing were performed with total tank heat loads ranging from 720 W to 420 W at a fill level of approximately 90%. During an updated evaluation of the data, it was noted that as the fluid passed through the Joule Thompson expansion, thermodynamic conditions consistent with the pervasive presence of metastability were indicated. This paper describes the observed thermodynamic conditions that correspond with metastability and effects on TVS performance.

Hastings, L. J.; Bolshinskiy, L. G.; Hedayat, A.; Schnell, A.

2011-01-01

195

Effects of environmental temperature on performance of the Joule-Thomson refrigerator  

NASA Astrophysics Data System (ADS)

Miniature Joule-Thomson refrigerators have been widely used for rapid cooling of infrared detectors, probes of cryosurgery, thermal cameras, missile homing head and guidance system, due to their special features of simple configuration, compact structure and rapid cool-down characteristics. Typical performance factors of the Joule-Thomson refrigerator are cool-down time, temperature of the cold end, running time and gas consumption. Those depend on operating conditions such as the pressure of the gas, thermal environment and etc.. In this study, experimental study of a miniature Joule- Thomson refrigerator with the gas pressure up to 12 MPa were performed to investigate the effects of the thermal environment (-40 ~ 50 °C). In experiments, to obtain the information of cool-down time, gas consumption and etc., the temperature of the cold end, mass flow rate and pressure of the argon gas are simultaneously measured. The Joule-Thomson refrigerator in cold thermal environment has rapid cool-down characteristics and small gas consumption. In the cold environmental condition, the Joule-Thomson refrigerator has high mass flow rate during cool-down process and in steady state.

Hong, Yong-Ju; Kim, Hyobong; Park, Seong-Je

2012-06-01

196

Integrated Heat Switch/Oxide Sorption Compressor  

NASA Technical Reports Server (NTRS)

Thermally-driven, nonmechanical compressor uses container filled with compressed praseodymium cerium oxide powder (PrCeOx) to provide high-pressure flow of oxygen gas for driving closed-cycle Joule-Thomson-expansion refrigeration unit. Integrated heat switch/oxide sorption compressor has no moving parts except check valves, which control flow of oxygen gas between compressor and closed-cycle Joule-Thomson refrigeration system. Oxygen expelled from sorbent at high pressure by evacuating heat-switch gap and turning on heater.

Bard, Steven

1989-01-01

197

GENERAL: Joule-Thomson Coefficient for Strongly Interacting Unitary Fermi Gas  

NASA Astrophysics Data System (ADS)

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

Liao, Kai; Chen, Ji-Sheng; Li, Chao

2010-09-01

198

Low-cost Joule Thomson coolers: single-flow flat cooler and two-flow cylindrical cooler  

Microsoft Academic Search

Regardless improvements of Stirling and Pulse Tube coolers performances, Joule Thomson coolers are still interested for systems which require very fast cool down, compactness and high reliability. AIR LIQUIDE-DTA- believes that most of the future applications for Joule Thomson coolers would required devices such as single flow or dual flow coolers if manufacturers are able to increase significantly the performances

Alain Cottereau

1998-01-01

199

Warm and Hot Stamping of Ultra High Tensile Strength Steel Sheets Using Resistance Heating  

Microsoft Academic Search

A warm and hot stamping process of ultra high tensile strength steel sheets using resistance heating was developed to improve springback and formability. In this process, the decrease in temperature of the sheet before the forming is prevented by directly heating the sheets set into the dies by means of the electrical resistance, the so-called Joule heat. Since the heating

K. Mori; S. Maki; Y. Tanaka

2005-01-01

200

Transfer of gaseous oxygen from high-pressure containers and the Joule-Thomson inversion  

NASA Technical Reports Server (NTRS)

From the experiments performed in study, it was determined that oxygen transferred at ambient temperature and pressures up to 10,000 psig consistently dropped in temperature. All results therefore indicate that gaseous oxygen transferred at ambient temperature does not exhibit Joule-Thomson inversion below 10,000 psig.

Schumann, E. R.

1974-01-01

201

Properties of Gas Mixtures and Their Use in Mixed-Refrigerant Joule-Thomson Refrigerators  

Microsoft Academic Search

The Joule-Thomson (J-T) effect has been widely used for achieving low temperatures. In the past few years, much progress has been made in better understanding the working mechanism of the refrigeration method and in developing prototypes for different applications. In this talk, there are three aspects of our research work to be discussed. First, some special thermal properties of the

E. Luo; M. Gong; J. Wu; Y. Zhou

2004-01-01

202

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

National Technical Information Service (NTIS)

As a consequence of advancements in Inertial Confinement Fusion research, LLNL is developing plans for a new 1.5 to 2 mega-joule solid-state Nd:glass laser designed to achieve fusion ignition. The new design is possible in part due to advances in optical ...

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

1992-01-01

203

Exergy analysis of Joule–Thomson cryogenic refrigeration cycle with an ejector  

Microsoft Academic Search

In this paper, exergy method is applied to analyze the ejector expansion Joule–Thomson (EJT) cryogenic refrigeration cycle. The exergy destruction rate in each component of the EJT cycle is evaluated in detail. The effect of some main parameters on the exergy destruction and exergetic efficiency of the cycle is also investigated. The most significant exergy destruction rates in the cycle

Jianlin Yu; Gaolei Tian; Zong Xu

2009-01-01

204

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

205

Compensation for Joule–Thomson effect in flowrate measurements by GMDH polynomial  

Microsoft Academic Search

The international standard for flowrate measurements ISO-5167 recommends the temperature sensor to be located downstream of the differential device what may cause a significant error in the measurement of the flowrate of natural gas, especially at high differential pressure, low temperature and low diameter ratio. The flowrate generally needs to be compensated for the temperature change due to the Joule–Thomson

Ivan Maric; Ivan Ivek

2010-01-01

206

A closed cycle cascade Joule Thomson refrigerator for cooling Josephson junction magnetometers  

NASA Astrophysics Data System (ADS)

A closed cycle cascade Joule Thomson refrigerator designed to cool Josephson Junction magnetometers to liquid helium temperature is being developed. The refrigerator incorporates 4 stages of cooling using the working fluids CF4 and He. The high pressure gases are provided by a small compressor designed for this purpose. The upper stages have been operated and performance will be described.

Tward, E.; Sarwinski, R.

1985-05-01

207

Direct observation of nanoscale Peltier and Joule effects at metal-insulator domain walls in vanadium dioxide nanobeams.  

PubMed

The metal to insulator transition (MIT) of strongly correlated materials is subject to strong lattice coupling, which brings about the unique one-dimensional alignment of metal-insulator (M-I) domains along nanowires or nanobeams. Many studies have investigated the effects of stress on the MIT and hence the phase boundary, but few have directly examined the temperature profile across the metal-insulating interface. Here, we use thermoreflectance microscopy to create two-dimensional temperature maps of single-crystalline VO2 nanobeams under external bias in the phase coexisting regime. We directly observe highly localized alternating Peltier heating and cooling as well as Joule heating concentrated at the M-I domain boundaries, indicating the significance of the domain walls and band offsets. Utilizing the thermoreflectance technique, we are able to elucidate strain accumulation along the nanobeam and distinguish between two insulating phases of VO2 through detection of the opposite polarity of their respective thermoreflectance coefficients. Microelasticity theory was employed to predict favorable domain wall configurations, confirming the monoclinic phase identification. PMID:24735496

Favaloro, Tela; Suh, Joonki; Vermeersch, Bjorn; Liu, Kai; Gu, Yijia; Chen, Long-Qing; Wang, Kevin X; Wu, Junqiao; Shakouri, Ali

2014-05-14

208

JTMIX - CRYOGENIC MIXED FLUID JOULE-THOMSON ANALYSIS PROGRAM  

NASA Technical Reports Server (NTRS)

JTMIX was written to allow the prediction of both ideal and realistic properties of mixed gases in the 65-80K temperature range. It allows mixed gas J-T analysis for any fluid combination of neon, nitrogen, various hydrocarbons, argon, oxygen, carbon monoxide, carbon dioxide, and hydrogen sulfide. When used in conjunction with the NIST computer program DDMIX, JTMIX has accurately predicted order-of-magnitude increases in J-T cooling capacities when various hydrocarbons are added to nitrogen, and it predicts nitrogen normal boiling point depressions to as low as 60K when neon is added. JTMIX searches for heat exchanger "pinch points" that can result from insolubility of various components in each other. These points result in numerical solutions that cannot exist. The length of the heat exchanger is searched for such points and, if they exist, the user is warned and the temperatures and heat exchanger effectiveness are corrected to provide a real solution. JTMIX gives very good correlation (within data accuracy) to mixed gas data published by the USSR and data taken by APD for the U.S. Naval Weapons Lab. Data taken at JPL also confirms JTMIX for all cases tested. JTMIX is written in Turbo C for IBM PC compatible computers running MS-DOS. The National Institute of Standards and Technology's (NIST, Gaithersburg, MD, 301-975-2208) computer code DDMIX is required to provide mixed-fluid enthalpy data which is input into JTMIX. The standard distribution medium for this program is a 5.25 inch 360K MS-DOS format diskette. JTMIX was developed in 1991 and is a copyrighted work with all copyright vested in NASA.

Jones, J. A.

1994-01-01

209

Concentration enhancement of sample solutes in a sudden expansion microchannel with Joule heating  

Microsoft Academic Search

Microfluidic concentration of sample solutes is achieved by using temperature gradient focusing (TGF) in a microchannel with a step change in cross-section. A mathematical model is developed to describe the complex TGF processes. Scaling analysis is conducted to estimate time scales so as to simplify the proposed mathematical model. Numerical computations are performed to obtain the temperature, velocity and sample

Zhengwei Ge; Chun Yang; Gongyue Tang

2010-01-01

210

Miniature Joule Thomson (JT) CryoCoolers for Propellant Management  

NASA Technical Reports Server (NTRS)

A proof-of-concept project is proposed here that would attempt to demonstrate how miniature cryocoolers can be used to chill the vacuum jacket line of a propellant transfer line and thus to achieve transfer line pre-chill, zero boil off and possible propellant densification. The project would be performed both at UCF and KSC, with all of the cryogenic testing taking place in the KSC cryogenic test bed. A LN2 line available in that KSC test facility would serve to simulate a LOX transfer line. Under this project, miniature and highly efficient cold heads would be designed. Two identical cold heads will be fabricated and then integrated with a JT-type cryogenic system (consisting of a common compressor and a common external heat exchanger). The two cold heads will be integrated into the vacuum jacket of a LN2 line in the KSC cryo lab, where the testing will take place.

Kapat, Jay; Chow, Louis

2002-01-01

211

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

NASA Astrophysics Data System (ADS)

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

Yuan, Du-Qi; Wang, Can-Jun

2010-04-01

212

Acquisition and correlation of cryogenic nitrogen mass flow data through a multiple orifice Joule-Thomson device  

NASA Technical Reports Server (NTRS)

Liquid nitrogen mass flow rate, pressure drop, and temperature drop data were obtained for a series of multiple orifice Joule-Thomson devices, known as Visco Jets, over a wide range of flow resistance. The test rig used to acquire the data was designed to minimize heat transfer so that fluid expansion through the Visco Jets would be isenthalpic. The data include a range of fluid inlet pressures from 30 to 60 psia, fluid inlet temperatures from 118 to 164 R, outlet pressures from 2.8 to 55.8 psia, outlet temperatures from 117 to 162 R and flow rate from 0.04 to 4.0 lbm/hr of nitrogen. A flow rate equation supplied by the manufacturer was found to accurately predict single-phase (noncavitating) liquid nitrogen flow through the Visco Jets. For cavitating flow, the manufacturer's equation was found to be inaccurate. Greatly improved results were achieved with a modified version of the single-phase equation. The modification consists of a multiplication factor to the manufacturer's equation equal to one minus the downstream quality on an isenthalpic expansion of the fluid across the Visco Jet. For a range of flow resistances represented by Visco Jet Lohm ratings between 17,600 and 80,000, 100 percent of the single-phase data and 85 percent of the two-phase data fall within + or - 10 percent of predicted values.

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

1990-01-01

213

Investigation of neon-nitrogen mixed refrigerant Joule-Thomson cryocooler operating below 70 K with precooling at 100 K  

NASA Astrophysics Data System (ADS)

There has been two-stage mixed refrigerant (MR) Joule-Thomson (JT) refrigeration cycle suggested for cooling high temperature superconductor (HTS) electric power cable below 70 K. As the continuation effort of realizing the actual system, we fabricated and tested a small scale neon and nitrogen MR JT cryocooler to investigate the refrigeration characteristics and performance. The compression system of the refrigeration circuit was accomplished by modifying commercially available air-conditioning rotary compressors. Compressors stably operated at the maximum compression ratio of 31 when the suction pressure was 77 kPa. The achieved lowest temperature was 63.6 K when the heating load was 35.9 W. The measured Carnot efficiency of the present system was 6.5% which was lower than that of the designed goal of 17.4%. The low efficiency of compressor (34.5%), and the pressure drop at the compressor suction were the main reasons for this efficiency degradation. The feasibility and usefulness of neon and nitrogen MR JT refrigeration cycle was validated that the achieved minimum temperature was 63.6 K even though the pressure after the expansion was maintained by 130 kPa. The comparison between the measurement and calculation showed that each stream temperature of refrigeration cycle were predictable within 3% error by Peng-Robinson equation of state (EOS).

Lee, Jisung; Oh, Haejin; Jeong, Sangkwon

2014-05-01

214

Quantum Joule-Thomson Effect in a Saturated Homogeneous Bose Gas  

NASA Astrophysics Data System (ADS)

We study the thermodynamics of Bose-Einstein condensation in a weakly interacting quasihomogeneous atomic gas, prepared in an optical-box trap. We characterize the critical point for condensation and observe saturation of the thermal component in a partially condensed cloud, in agreement with Einstein's textbook picture of a purely statistical phase transition. Finally, we observe the quantum Joule-Thomson effect, namely isoenthalpic cooling of an (essentially) ideal gas. In our experiments this cooling occurs spontaneously, due to energy-independent collisions with the background gas in the vacuum chamber. We extract a Joule-Thomson coefficient ?JT>109 K /bar, about 10 orders of magnitude larger than observed in classical gases.

Schmidutz, Tobias F.; Gotlibovych, Igor; Gaunt, Alexander L.; Smith, Robert P.; Navon, Nir; Hadzibabic, Zoran

2014-01-01

215

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

NASA Astrophysics Data System (ADS)

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

Hysell, D. L.; Michhue, G.; Larsen, M. F.; Pfaff, R.; Nicolls, M.; Heinselman, C.; Bahcivan, H.

2008-07-01

216

Joule-Thomson inversion curves and related coefficients for several simple fluids  

NASA Technical Reports Server (NTRS)

The equations of state (PVT relations) for methane, oxygen, argon, carbon dioxide, carbon monoxide, neon, hydrogen, and helium were used to establish Joule-Thomson inversion curves for each fluid. The principle of corresponding states was applied to the inversion curves, and a generalized inversion curve for fluids with small acentric factors was developed. The quantum fluids (neon, hydrogen, and helium) were excluded from the generalization, but available data for the fluids xenon and krypton were included. The critical isenthalpic Joule-Thomson coefficient mu sub c was determined; and a simplified approximation mu sub c approximates T sub c divided by 6P sub c was found adequate, where T sub c and P sub c are the temperature and pressure at the thermodynamic critical point. The maximum inversion temperatures were obtained from the second virial coefficient (maximum (B/T)).

Hendricks, R. C.; Peller, I. C.; Baron, A. K.

1972-01-01

217

JouleTrack: a web based tool for software energy profiling  

Microsoft Academic Search

A software energy estimation methodology is presented that avoids explicit characterization of instruction energy consumption and pre-dicts energy consumption to within 3% accuracy for a set of bench-mark programs evaluated on the StrongARM SA-1100 and Hitachi SH-4 microprocessors. The tool, JouleTrack, is available as an online resource and has various estimation levels. It also isolates the switch-ing and leakage components

Amit Sinha; Anantha P. Chandrakasan

2001-01-01

218

Multilayer cloud monitoring by micro-Joule lidar based on photon counting receiver and diode laser  

Microsoft Academic Search

Multilayers clouds layer's horizons have been detected in strong snowing condition by using the micro-Joule eye-safe lidar. Lidar is based on the 1 muJ (30 ns length) pulsed diode laser, which operates with high repetition rate (up to 10 kHz) and silica (Si) photon counting receiver (Single Photon Avalanche Diode, SPAD) from Czech Technical University. Note that the unique low

S. M. Pershin; A. N. Lyash; V. S. Makarov; K. Hamal; I. Prochazka; B. Sopko

2009-01-01

219

Optimization of the working fluid in a Joule–Thomson cold stage  

Microsoft Academic Search

Vibration-free miniature Joule–Thomson (JT) coolers are of interest for cooling a wide variety of devices, including low-noise amplifiers, semiconducting and superconducting electronics, and small optical detectors used in space applications. For cooling such devices, coolers are needed which have operating temperatures within a wide temperature range of 2–250K. In this paper, the optimization of the working fluid in JT cold

J. H. Derking; H. J. M. ter Brake; A. Sirbi; M. Linder; H. Rogalla

2009-01-01

220

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

221

Virial modeling of gas-solid Joule-Thomson effect for argon-carbon aerosol  

SciTech Connect

This paper presents the history of and later experimentation with the Joule--Thomson effect. The effect is discussed in terms of its association with a gas-solid dispersion. Experimental measurements of aerosol cooling were compared to a viral model utilizing chromatographic second gas-solid viral coefficients. The author extends the application of this model to include the effects of higher order viral coefficients.

Rybolt, T.R. (Tennessee Univ., Chattanooga, TN (USA))

1989-12-01

222

A study on the transient characteristics of a self-regulating Joule-Thomson cryocooler  

Microsoft Academic Search

An experimental and numerical study of transient characteristics for the self-regulating Joule-Thomson (J-T) cryocooler is developed in the present work. The modelling of the bellows control mechanism and the simulation of the cooler system are developed. It is proved by experiment that the most important transient behaviours can be accurately predicted by the present numerical simulation. In order to rectify

S. B. Chien; L. T. Chen; F. C. Chou

1996-01-01

223

Characterization of porous sinter materials as Joule–Thomson restrictors for the Planck sorption cooler  

Microsoft Academic Search

The Planck sorption cooler cold end utilizes Joule–Thomson expansion of hydrogen to achieve temperatures below 18 K. Porous stainless steel sintered elements function as the J–T restriction. We report the flow characteristics of these porous flow restrictors, as a function of temperature over the range 19–300 K at constant pressure, and as a function of pressure at 1.4–5.5 MPa (200–800

C. G Paine

2004-01-01

224

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

225

Accurate CO 2 Joule–Thomson inversion curve by molecular simulations  

Microsoft Academic Search

We present simulation of the Joule–Thomson inversion curve (JTIC) for carbon dioxide using two different approaches based on Monte Carlo (MC) simulations in the isothermal–isobaric ensemble. We model carbon dioxide using a two-center Lennard–Jones (LJ) plus point quadrupole moment (2CLJQ) potential. We show that a precision of four significant figures in ensemble averages of thermodynamic quantities of interest is needed

Coray M. Colina; Martin L??sal; Flor R. Siperstein; Keith E. Gubbins

2002-01-01

226

Molecular simulation of the Joule–Thomson inversion curve of carbon dioxide  

Microsoft Academic Search

The complete Joule–Thomson (JT) inversion curve for carbon dioxide is calculated using molecular simulations. A two center Lennard–Jones model with an embedded point quadrupole is used to model the fluid–fluid interactions. The simulation results agree quantitatively with all available experimental data. Comparison with commonly used equations of state provides only a modest agreement, with the highest discrepancies being observed at

A. Chac??n; J. M. Vázquez; E. A. Müller

1999-01-01

227

Ultra-high temperature stability Joule-Thomson cooler with capability to accommodate pressure variations  

SciTech Connect

This patent describes an improved Joule-Thomson cryogenic refrigeration system having a cold head and a cryostat assembly connected to a source of compressed gas. It comprises an adjustable expansion valve means; a temperature sensing and adjusting means; and an absolute pressure valve means, connected to exhaust side of the valve expansion means, for maintaining a constant exhaust pressure of the system independent of changes in ambient atmospheric pressure.

Bard, S.; Wu, J.J.; Trimble, C.A.

1992-06-09

228

Superfluid Joule–Thomson Refrigeration, a New Concept for Cooling Below 2 Kelvin  

Microsoft Academic Search

A new type of sub-Kelvin refrigerator, the superfluid Joule–Thomson refrigerator is discussed. The refrigerator uses the circulation of the 3He component of a liquid 3He–4He mixture through a throttle to provide cooling to temperatures of 0.5 K. A simple analytical model is developed to predict the cooling power for this refrigerator as function of temperature. In addition, cooling power predictions

J. G. Brisson

2000-01-01

229

HTS SQUID system with Joule-Thomson cryocooler for eddy current nondestructive evaluation of aircraft structures  

Microsoft Academic Search

For the detection of deep-lying flaws in aircraft structures, an eddy current system in conjunction with a planar SQUID gradiometer is being developed. The need for a mobile system imposes additional requirements on cooling regarding mobility, operation independent of spatial orientation, and handling. We present results on the operation of HTS SQUIDs with the commercial Joule-Thomson-cryocooler KC 100 (“cryotiger”) by

R. Hohmann; H.-J. Krause; H. Soltner; H. Zhang; C. A. Copetti; H. Bousack; A. I. Braginski; M. I. Faley

1997-01-01

230

Calculation of the Joule–Thomson inversion curves from cubic equations of state  

Microsoft Academic Search

In this paper the Joule–Thomson (JT) inversion curve has been used to test the predictive capabilities of some recent cubic equations of state. The three and two parameter cubic equations of state included modified Patel–Teja (MPT), modified Peng–Robinson (MPR) by Melhem–Saini–Goodwin, Iwai–Margerum–Lu (IML), modified Redlich–Kwong (MRK) by Souahi–Sator–Albane–Kies–Chitoure and the four parameter Trebble–Bishnoi (TB) equation of state were chosen for

Naser Seyed Matin; Behzad Haghighi

2000-01-01

231

A joule-class, TEM00 spatial profile, narrow-linewidth laser system  

Microsoft Academic Search

A Joule-class, narrow-linewidth amplifier line delivering 20 ns pulses with a TEM00 spatial profile is presented. A Q-switched Nd:YAG oscillator with an intra-cavity volume Bragg grating (VBG) is used to seed the amplifier line. A series of flashlamp-pumped Nd:YAG amplifiers consisting of a double-pass and two single-pass amplifiers boost the energy of the 21 ns pulses to 480 mJ. The

Andreas Vaupel; Nathan Bodnar; Michaël Hemmer; Martin Richardson

2011-01-01

232

Hampson’s type cryocoolers with distributed Joule-Thomson effect for mixed refrigerants closed cycle  

NASA Astrophysics Data System (ADS)

Most previous studies on Joule-Thomson cryocoolers of mixed refrigerants in a closed cycle focus on the Linde kind recuperator. The present study focuses on four constructions of Hampson’s kind miniature Joule-Thomson cryocoolers based on finned capillary tubes. The frictional pressure drop along the tubes plays the role of distributed Joule-Thomson expansion so that an additional orifice or any throttle at the cold end is eliminated. The high pressure tube is a throttle and a channel of recuperation at the same time. These coolers are tested within two closed cycle systems of different compressors and different compositions of mixed coolants. All tests were driven by the same level of discharge pressure (2.9 MPa) while the associated suction pressures and the associated reached temperatures are dependent on each particular cryocooler and on the closed cycle system. The mixture of higher specific cooling capacity cannot reach temperatures below 80 K when driven by the smaller compressor. The other mixture of lower specific cooling capacity driven by the larger compressor reaches lower temperatures. The examined parameters are the cooldown period and the reachable temperatures by each cryocooler.

Maytal, Ben-Zion

2014-05-01

233

Low-heat input cryogenic temperature control with recuperative heat-exchanger in a Joule Thomson cryocooler  

Microsoft Academic Search

The control of cryogenic temperatures is usually accomplished by a passive stage, exploiting the combined effect of a thermal mass connected to a thermal resistance; by an active control, often of a PID type, based on the combination of a dedicated sensor, a heater and a controller; or by a combination of the two. Such a system typically uses a

M. Prina; J. Borders; P. Bhandari; G. Morgante; D. Pearson; C. Paine

2004-01-01

234

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

235

A joule-class, TEM00 spatial profile, narrow-linewidth laser system  

NASA Astrophysics Data System (ADS)

A Joule-class, narrow-linewidth amplifier line delivering 20 ns pulses with a TEM00 spatial profile is presented. A Q-switched Nd:YAG oscillator with an intra-cavity volume Bragg grating (VBG) is used to seed the amplifier line. A series of flashlamp-pumped Nd:YAG amplifiers consisting of a double-pass and two single-pass amplifiers boost the energy of the 21 ns pulses to 480 mJ. The presented amplifier line will be used for fundamental studies including remote Raman spectroscopy and ns filamentation.

Vaupel, Andreas; Bodnar, Nathan; Hemmer, Michaël; Richardson, Martin

2011-02-01

236

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

237

One-Joule-per-Pulse Q-Switched 2-micron Solid State Laser  

NASA Technical Reports Server (NTRS)

Q-switched output of 1.1 J per pulse at 2-micron wavelength has been achieved in a diode pumped Ho:Tm:LuLF laser using a side-pumped rod configuration in a Master-Oscillator-Power-Amplifier (MOPA) architecture. This is the first time that a 2-micron laser has broken the Joule per pulse barrier for Q-switched operation. The total system efficiency reaches 5% and 6.2% for single and double pulse operation, respectively. The system produces excellent 1.4 times of transform limited beam quality.

Yu, Jirong; Trieu, Bo C.; Modlin, Ed A.; Singh, Upendra N.; Kavaya, Michael J.; Chen, Songsheng; Bai, Yingxin; Petzar, Pual J.; Petros, Mulugeta

2005-01-01

238

Development of a hardened imaging system for the Laser MegaJoule  

NASA Astrophysics Data System (ADS)

The Laser MegaJoule (LMJ) facility will host inertial confinement fusion experiments in order to achieve ignition by imploding a Deuterium-Tritium microballoon. In this context an X-ray imager is necessary to diagnose the core size and shape of the DT-target in the 10-100 keV band in complement of neutron imaging system. Such a diagnostic will be composed of two parts: an X-ray optical system and a detection assembly. Each element will be affected by the harsh environment created by fusion reactions.

Rousseau, A.; Darbon, S.; Troussel, P.; Caillaud, T.; Bourgade, J. L.; Turk, G.; Vigne, E.; Hamel, M.; Larour, J.; Bradley, D.; Smalyuk, V.; Bell, P.

2013-11-01

239

Local heating-induced plastic deformation in resistive switching devices  

Microsoft Academic Search

Resistive switching is frequently associated with local heating of the switching structure. The mechanical effect of such heating on Pt\\/SrTiO3 (001) Schottky barriers and on Pt\\/SrZrO3\\/SrRuO3\\/SrTiO3 switching devices was examined. The extent and magnitude of Joule heating was assessed using IR microscopy at power dissipation levels similar to what others have reported during electroforming. Lines aligned along the [100] and

W. Jiang; R. J. Kamaladasa; Y. M. Lu; A. Vicari; R. Berechman; P. A. Salvador; J. A. Bain; Y. N. Picard; M. Skowronski

2011-01-01

240

Measurements of Plasma Density in a Fast and Compact Plasma Focus Operating at Hundreds of Joules  

NASA Astrophysics Data System (ADS)

It is known that there are plasma parameters that remain relatively constant for plasma focus facilities operating in a wide range of de energy, from 1kJ to 1MJ, such as: electron density, temperature and plasma energy density. Particularly the electron density is of the order of 1025m-3. Recently the experimental studies in plasma focus has been extended to devices operating under 1kJ, in the range of hundreds and tens of joules. In this work an optical refractive system was implemented in order to measure the electron density in a plasma focus devices of hundred of joules, PF-400J (880 nF, 30 kV, 120 kA, 400 J, 300 ns time to peak current, dI/dt~4×1011 A/s. The plasma discharge was synchronized with a pulsed Nd-YAG laser (~6ns FWHM at 532nm) in order to obtain optical diagnostics as interferometry and Schlieren. An electron density of (0.9+/-0.25)×1025m-3 was obtained at the axis of the plasma column close to the pinch time. This value is of the same order that the obtained in devices oparating in the energy range of 1kJ to 1MJ.

Pavez, Cristian; Silva, Patricio; Moreno, José; Soto, Leopoldo

2006-12-01

241

GEM-CEDAR Study of Ionospheric Energy Input and Joule Dissipation  

NASA Technical Reports Server (NTRS)

We are studying ionospheric model performance for six events selected for the GEM-CEDAR modeling challenge. DMSP measurements of electric and magnetic fields are converted into Poynting Flux values that estimate the energy input into the ionosphere. Models generate rates of ionospheric Joule dissipation that are compared to the energy influx. Models include the ionosphere models CTIPe and Weimer and the ionospheric electrodynamic outputs of global magnetosphere models SWMF, LFM, and OpenGGCM. This study evaluates the model performance in terms of overall balance between energy influx and dissipation and tests the assumption that Joule dissipation occurs locally where electromagnetic energy flux enters the ionosphere. We present results in terms of skill scores now commonly used in metrics and validation studies and we can measure the agreement in terms of temporal and spatial distribution of dissipation (i.e, location of auroral activity) along passes of the DMSP satellite with the passes' proximity to the magnetic pole and solar wind activity level.

Rastaetter, Lutz; Kuznetsova, Maria M.; Shim, Jasoon

2012-01-01

242

Measurements of Plasma Density in a Fast and Compact Plasma Focus Operating at Hundreds of Joules  

SciTech Connect

It is known that there are plasma parameters that remain relatively constant for plasma focus facilities operating in a wide range of de energy, from 1kJ to 1MJ, such as: electron density, temperature and plasma energy density. Particularly the electron density is of the order of 1025m-3. Recently the experimental studies in plasma focus has been extended to devices operating under 1kJ, in the range of hundreds and tens of joules. In this work an optical refractive system was implemented in order to measure the electron density in a plasma focus devices of hundred of joules, PF-400J (880 nF, 30 kV, 120 kA, 400 J, 300 ns time to peak current, dI/dt{approx}4x1011 A/s. The plasma discharge was synchronized with a pulsed Nd-YAG laser ({approx}6ns FWHM at 532nm) in order to obtain optical diagnostics as interferometry and Schlieren. An electron density of (0.9{+-}0.25)x1025m-3 was obtained at the axis of the plasma column close to the pinch time. This value is of the same order that the obtained in devices oparating in the energy range of 1kJ to 1MJ.

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

2006-12-04

243

Clog Retard of a Vortex Throttle Joule-Thomson Cryocooler: Further Experimental Verification  

NASA Astrophysics Data System (ADS)

The demand of high purity gas supply for Joule-Thomson cryocoolers and liquefiers is crucial in order to avoid plug formation at the delicate throttling device. A throttle which would tolerate higher level of contamination is greatly desirable for more reliable operation. The vortex throttle has such a potential. A series of vortex throttles were applied to a miniature Joule-Thomson cryocooler and tested with precisely contaminated coolant. The instantaneous flow rate and the mode of its decay indicate the rate and nature of plug formation. Each experiment was a simultaneous run of two cryocoolers in parallel at similar conditions: one with a traditional throttle of short hole, and the other one with the vortex throttle. The clog retard behavior of the vortex throttle was verified. It runs about 2.5 times longer than the traditional one, while being fed by water vapor contaminated nitrogen at the levels of 5 and 17 PPM. The contamination level by carbon dioxide was 80 PPM and exhibited a different behavior of clog formation. Its effect on the cryocooler temperature stability with the vortex throttle was quite minor.

Maytal, B.-Z.

2010-04-01

244

Thermodynamical calculation of metal heating in nanosecond exploding wire and foil experiments  

Microsoft Academic Search

A method of thermodynamical calculation of thin metal wire heating during its electrical explosion is discussed. The technique is based on a calculation of Joule energy deposition taking into account the current wave form and the temperature dependence of the resistivity and heat capacity of the metal. Comparing the calculation to a set of exploding tungsten wire experiments demonstrates good

G. S. Sarkisov; S. E. Rosenthal; K. W. Struve

2007-01-01

245

Two-Phase Cryogenic Heat Exchanger for the Thermodynamic Vent System  

NASA Technical Reports Server (NTRS)

A two-phase cryogenic heat exchanger for a thermodynamic vent system was designed and analyzed, and the predicted performance was compared with test results. A method for determining the required size of the Joule-Thomson device was also developed. Numerous sensitivity studies were performed to show that the design was robust and possessed a comfortable capacity margin. The comparison with the test results showed very similar heat extraction performance for similar inlet conditions. It was also shown that estimates for Joule- Thomson device flow rates and exit quality can vary significantly and these need to be accommodated for with a robust system design.

Christie, Robert J.

2011-01-01

246

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

Microsoft Academic Search

At the University of Twente, a foetal heart monitor based on a high-TC SQUID magnetometer system is under development. The purpose of this system is to measure a foetal heart signal in a clinical environment. For cooling a first demonstrator version, a closed-cycle Joule–Thomson cooler from APD Cryogenics – the Cryotiger® – was selected. In this work, the Cryotiger is

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

2001-01-01

247

Determination of the Joule–Thomson coefficient in problems of measuring the flow rate of natural gas  

Microsoft Academic Search

Existing methods of calculating the Joule–Thomson coefficient for natural gas are analyzed. A procedure for use in calculations\\u000a of gas flow rate employing the variable pressure drop method is proposed which gives increased measurement accuracy by eliminating\\u000a the additional error in determining the temperature of the natural gas.

E. P. Pistun; F. D. Matiko; O. Ya. Masnyak

2009-01-01

248

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

NASA Astrophysics Data System (ADS)

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

Hubert, S.; Prévot, V.

2013-11-01

249

Optimization of the working fluid for a sorption-based Joule-Thomson cooler  

NASA Astrophysics Data System (ADS)

Sorption-based Joule-Thomson coolers operate vibration-free, have a potentially long life time, and cause no electromagnetic interference. Therefore, they are appealing to a wide variety of applications, such as cooling of low-noise amplifiers, superconducting electronics, and optical detectors. The required cooling temperature depends on the device to be cooled and extends into the cryogenic range well below 80 K. This paper presents a generalized methodology for optimization in a sorption-based JT cooler. The analysis is based on the inherent properties of the fluids and the adsorbent. By using this method, the working fluid of a JT cooler driven by a single-stage sorption compressor is optimized for two ranges of cold-tip operating temperatures: 65-160 K and 16-38 K. The optimization method is also extended to two-stage compression and specifically nitrogen and carbon monoxide are considered.

Wu, Y.; Zalewski, D. R.; Vermeer, C. H.; ter Brake, H. J. M.

2013-12-01

250

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

251

Studies on a 100-joule-class UV-pre-ionized TEA CO2 laser  

NASA Astrophysics Data System (ADS)

The studies on a 1 00-Joule-class UV-preionized TEA (transversely excited atmospheric) CO2 laser are reported. A maximum pulse energy 1 15 J was obtained by using an energy-optimized gas mixture of C02/N2/H2 =3/15/2 and a Marx pulse generator discharge circuit. The temporal waveform of the laser pulse with the optimized gas mixture consists of a sharp spike of 250 ns and a tail of 4 µs in full width at half maximum (FWHM). Simple air breathing laser propulsion was demonstrated, a high impulse coupling coefficient 390 N/MW was obtained at the pulse energy 60 J, which shows the attractive point ofthe UV-preionized TEA CO2 laser.

Zuo, Duluo; Lu, Hong; Cheng, Zuhai

2005-03-01

252

Advancements in clog resistant and demand flow Joule-Thomson cryostats  

NASA Astrophysics Data System (ADS)

A cryostat composed of a special anti-clogging Joule-Thomson (J-T) expansion nozzle combined with demand flow regulation, derived from differential thermal expansion, was developed in the recent past. This new type of cryostat has proved to be remarkably rugged and highly resistant to blockage by contaminants in the gas flow. In addition, the cryostat has displayed surprisingly stable temperature characteristics. The new cryostat design has now been applied to a variety of systems with different fluids and special requirements over a range of refrigeration capacities. This paper discusses some of the interesting situations and problems encountered in devising new variations of the basic design. Recent applications include use of liquid cryogen working fluid, modular designs, and variable capacity systems.

Prentice, J. W.; Walker, G.; Zylstra, S. G.

253

The Experimental Evaluation of a Proof of Principle Superfluid Joule-Thomson Refrigerator  

NASA Astrophysics Data System (ADS)

The performance of a new type of sub-Kelvin refrigerator, the superfluid Joule-Thomson refrigerator, has been experimentally verified. This refrigerator uses a liquid superfluid mixture of 3He and 4He as the working fluid and depends on the non-ideal-gas-like behavior of the 3He component in this mixture to provide cooling when one component of the mixture is passed through a throttle. The refrigerator achieved an ultimate low temperature of 0.68 K when operating with a 3% 3He mixture. When operating with a 5% mixture the cooling power above 0.73 K was greater than with a 3% mixture but the ultimate low temperature was higher (0.71 K). The effect of 3He concentration of the working fluid on the performance of the refrigerator is discussed.

Miller, F. K.; Brisson, J. G.

2006-04-01

254

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

255

Large cooling power hybrid Gifford mac Mahon / Joule Thomson refrigerator andliquefier  

NASA Astrophysics Data System (ADS)

In this paper, we present two refrigerators using Joule Thomson cycle providing cooling powers of 4.5 W at 4.4 K and using Gifford Mac Mahon cryocoolers for the precooling. Several smaller machines have been developped in our laboratory with refrigeration capacity ranging from 100 mW up to 1.5 W in the temperature range 3 K to 4.4 K. In the present case, to increase the cooling power, we introduced a three stage precooling scheme using a liquid nitrogen vessel plus the two stages of a Gifford Mac Mahon cryocooler. Cooldown and operation of the system are fully automatic. The first refrigerator is used to cool two Nb 3Sn superconducting coils having a maximum field of 11.8 T. The second system is an helium liquefier, designed to produce more than 1 liter per hour.

Poncet, Jean-Marc; Claudet, Gérard; Lagnier, Robert; Ravex, Alain

256

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

257

Ohmic heating, line tying, and preionization in Hanbit  

Microsoft Academic Search

Initial attempts have been made at Ohmic (Joule) heating, stabilization, and preionization in Hanbit using an electron-emitting hot cathode in conjunction with a reflex discharge. The hot cathode was constructed using a set of LaB6 discs heated internally with current through carbon rods. The cathode was mounted in the cusp section of Hanbit on magnetic field lines connected to the

J. S. Hong; A. C. England; M. Kwon; J. H. Choi

2003-01-01

258

Flow boiling heat transfer with HFC mixtures in a smooth horizontal tube. Part II: Assessment of predictive methods  

Microsoft Academic Search

In tube heat transfer characteristics of R410A and R404A have been experimentally investigated in a smooth horizontal tube made of stainless steel with an inner diameter of 6 mm and a length of 6 m, uniformly heated by the Joule effect. The evaporation pressures has been varied within the range from 3 to 12 bar, the refrigerant mass flux within

A. Greco; G. P. Vanoli

2005-01-01

259

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

260

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

2013-11-01

261

Deposition of the Joule Energy in Initial Stage of Wire Explosion  

NASA Astrophysics Data System (ADS)

The Joule energy deposition in the initial stages of exploding wires has been investigated. A Maxwell 40151-B trigger generator, producing a maximum current of 3kA and voltage of 120kV, with current rise times of 170A/ns in a fast regime and 22A/ns in a slow regime, was used in the explosion of different fine wires. The wires were 2 cm in length and 4-40 microns in diameter. Current, voltage, current and voltage derivatives, wire boundary evolution, interferometry, shadowgraphy, absorbography, time-resolved self-luminosity imaging, emitted light intensity were monitored in the experiment. The evolution of wire diameter was determined using a diode laser back lighter and streak camera. Two significantly different modes of wire explosion have been found: fast and slow. It has been found that electronic emission from wire surface plays important role in the Joule energy deposition inside the wire. This effect is especially important for refractory metals. earn certain regime of slow explosion modes, part of the wire can be left non-evaporated. Fast explosion mode significantly increases energy deposition into the wire. Fast exploding wire is extended with the greatest velocity and emits the highest level of specific light radiation. The temporal shape of radiation in fast exploding mode is dependent only on wire substance. Slow explosion mode gives a smaller velocity of extension and weak light radiation. It has been shown experimentally that for fast exploding mode, velocity of wire extension is inversely proportional to the square of vaporization energy. Fast-induced transparency has been observed for low vaporization energy substances. It’s happening due to liquid-to-gas transition. No induced transparency has been observed for slow explosion mode because phase transition through the boiling. Our fast exploding results correspond to overcritical phase transitions, when boiling processes is suppressed by external pressure of magnetic field. In this case wire is expanded like whole gas volume and “cold core” phenomenon is absent for fast regime of explosion.

Sarkisov, G. S.; Bauer, B. S.; de Groot, J. S.

2000-10-01

262

Thermoelectric heating of Ge2Sb2Te5 in phase change memory devices  

NASA Astrophysics Data System (ADS)

We report on the demonstration of the active thermoelectric application to nanometer-scaled semiconductor devices. The thermoelectric heating already exists during programming in conventional phase change memory (PRAM) cells, which is only a minor supplement to Joule heating. Here, by rigorously designing devices, we have demonstrated an unprecedentedly high efficiency of PRAM, where the majority of the heat is supplied by the thermoelectric effect.

Suh, Dong-Seok; Kim, Cheolkyu; Kim, Kijoon H. P.; Kang, Youn-Seon; Lee, Tae-Yon; Khang, Yoonho; Park, Tae Sang; Yoon, Young-Gui; Im, Jino; Ihm, Jisoon

2010-03-01

263

Prediction of the Attractive Branch of the Effective Pair Potential Using the Joule–Thomson Inversion Curve  

Microsoft Academic Search

In the present work, the attractive branch of the effective pair potential is predicted by using p–v–T data of the Joule–Thomson inversion curve. It is concluded that all loci of the thermodynamic states of the inversion curve correspond to the attractive branch of the effective pair potential. It is also predicted that the minimum of the effective pair potential well,

E. Keshavarzi; G. Parsafar; B. Najafi

1999-01-01

264

Experimental investigation on mixed refrigerant Joule–Thomson cryocooler with flammable and non-flammable refrigerant mixtures  

Microsoft Academic Search

The mixed refrigerant Joule–Thomson (MR J–T) cryocoolers have a wide application area covering the temperature range from 80K to 200K. The significant advantages of the system are simplicity of its design and working reliability with high level performance. The present paper discusses the experimental results of MR J–T cooler with different flammable and non-flammable mixture compositions. The work highlights the

N. S. Walimbe; K. G. Narayankhedkar; M. D. Atrey

2010-01-01

265

Measurements of the isobaric enthalpy increment and the isenthalpic Joule–Thomson effect of (methane + water) and (methane + ethane + water)  

Microsoft Academic Search

The direct measurement of caloric properties of model systems for natural gas is of great technical interest. Therefore, integral Joule–Thomson effects and isobaric enthalpy increments have been measured for two (methane+ethane+water) compositions and three (methane+water) compositions. The flow calorimeter facility used is described. The temperature range from near mixture dew point temperature toT=600 K and pressures up to 7 MPa

C. Day; M. Stephan; L. R. Oellrich

1997-01-01

266

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

SciTech Connect

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

Papell, S.S.; Nyland, T.W.; Saiyed, N.H. (Analex Corp., Brook Park, OH (United States) NASA, Lewis Research Center, Cleveland, OH (United States))

1992-07-01

267

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

NASA Technical Reports Server (NTRS)

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 data covered a range of inlet and outlet operating conditions. The mass flow rate range single phase or two phase was 0.015 to 0.98 lbm/hr. The manufacturer's equation was found to overpredict the single phase hydrogen data by 10 percent and the two phase data by as much as 27 percent. Two modifications of the equation resulted in a data correlation that predicts both the single and two phase flow across the visco jet. The first modification was of a theoretical nature, and the second strictly empirical. The former reduced the spread in the two phase data. It was a multiplication factor of 1 - X applied to the manufacturer's equation. The parameter X is the flow quality downstream of the visco jet based on isenthalpic expansion across the device. The latter modification was a 10 percent correction term that correlated 90 percent of the single and two phase data to within +/- 10 percent scatter band.

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

1992-01-01

268

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

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

269

Experimental Investigation on Mixed-Refrigerant for Closed-Cycle Joule-Thomson Cryocoolers  

NASA Astrophysics Data System (ADS)

Mixed-Refrigerant (MR) Joule-Thomson (JT) cryocoolers have being under development in our laboratory for various applications during the last few years. We have tested several MRs at different operation conditions and with a few different compressors. One major requirement, that is common to all applications, is a fixed cooling-temperature within all expected environmental conditions, especially different ambient temperatures. Unlike with pure gases, the cold temperature obtained with JT cryocoolers operating with MRs is not constant and depends on the ambient temperature. The present paper gives experimental results for two setups with a single MR (Ne+N2+HCs) that was selected according to previous researches. The experiments included two types of compressors, one is oil-lubricated and the other is oil-free. As a result of this experimental research we have mapped the MR performances over a wide range of operating conditions: high pressures of 2.1 to 2.9 MPa and low pressures of 0.083 to 0.134 MPa for ambient temperatures between -40 to 65° C. A method for improving the cold-temperature stability is also demonstrated.

Tzabar, N.; Lapp, Z.

2010-04-01

270

Visco Jet Joule-Thomson Device Characterization Tests in Liquid Methane  

NASA Technical Reports Server (NTRS)

Joule-Thomson (J-T) devices have been identified as critical components for Thermodynamic Vent Systems (TVS) planned for future space exploration missions. Lee Visco Jets (The Lee Company) (Ref. 4) are one type of J-T device that may be used for LCH4 propellant systems. Visco Jets have been previously tested and characterized in LN2 and LH2 (Refs. 6 and 7), but have not been characterized in LOX or LCH4. Previous Visco Jet tests with LH2 resulted in clogging of the Visco Jet orifice under certain conditions. It has been postulated that this clogging was due to the presence of neon impurities in the LH2 that solidified in the orifices. Visco Jets therefore require testing in LCH4 to verify that they will not clog under normal operating conditions. This report describes a series of tests that were performed at the NASA Glenn Research Center to determine if Visco Jets would clog under normal operating conditions with LCH4 propellant. Test results from this program indicate that no decrease in flow rate was observed for the Visco Jets tested, and that current equation used for predicting flow rate appears to under-predict actual flow at high Lohm ratings.

Jurns, John M.

2009-01-01

271

Characterization of a two-stage 30 K Joule-Thomson microcooler  

NASA Astrophysics Data System (ADS)

Micromachined cryocoolers are attractive tools for cooling electronic chips and devices to cryogenic temperatures. A two-stage 30 K microcooler operating with nitrogen and hydrogen gas is fabricated using micromachining technology. The nitrogen and hydrogen stages cool down to about 94 and 30 K, respectively, using Joule-Thomson expansion in a restriction with a height of 1.10 ?m. The nitrogen stage is typically operated between 1.1 bar at the low-pressure side and 85.1 bar at the high-pressure side. The hydrogen stage has a low pressure of 5.7 bar, whereas the high pressure is varied between 45.5 and 60.4 bar. In changing the pressure settings, the cooling power can more or less be exchanged between the two stages. These typically range from 21 to 84 mW at 95 K at the nitrogen stage, corresponding to 30 to 5 mW at 31-32 K at the hydrogen stage. This paper discusses the characterization of this two-stage microcooler. Experimental results on cool down and cooling power are compared to dynamic modeling predictions.

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

2013-06-01

272

Prediction of final temperature following Joule-Thomson expansion of nitrogen gas  

NASA Astrophysics Data System (ADS)

This paper shows a theoretical prediction of the final temperature Ta which can be obtained using the Joule-Thomson (J-T) effect by expanding nitrogen gas across a throttling valve to 0.101 MPa. An iteration method using the J-T coefficient ? is first used to predict Ta. The Benedict-Webb-Rubin (BWR) and Redlich-Kwong (RK) equations are used to determine the specific volume and the derivatives of properties, respectively. Values of Ta can be well predicted by a five-step expansion simulation, except for cases where the isenthalpic lines to 0.101 M Pa cross a region around T = 120-160 K and P = 6.0 M Pa. In this region, calculated ? are lower than the experimental data. By equalizing the value of enthalpy after expansion to that before expansion and using the Peng-Robinson (PR) equation to calculate the departure function, the values of Ta can also be well predicted by the second method, except for Pb > 3.5 MPa in the cases where Tb = 170 and 150 K.

Chou, F.-C.; Wu, S.-M.; Pai, C.-F.

273

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

274

Idealized Closed Form Performance Modeling of a Closed Cycle Joule-Thomson Cryocooler  

NASA Astrophysics Data System (ADS)

The characteristic parameters of a closed cycle Joule-Thomson cryocooler would be: the charging pressure, discharge and suction volumes of the loop, volumetric displacement of the compressor and the extent of throttling restriction. A series of idealizing assumption are applied. The volumetric behavior of the coolant is assumed to obey the ideal gas equation. The recuperator and compressor's volumetric delivery are completely efficient. There are no pressure losses along the circulating path. On this basis is developed a closed form model of the system, interrelating the relevant parameters. Performance at steady state is expressed in terms of the circulating flow rate, discharge and suction pressures and cooling power. The model predicts the optimal size of equivalent orifice and the maximized cooling power. Also derived is the hydrodynamic time constant of building up the discharge pressure. This analysis is relevant for mixed coolants as well as for pure coolants closed cycles. The former typically employ lower pressure and therefore the idealized assumptions are even more applicable.

Maytal, B.-Z.

2004-06-01

275

Numerical analysis of the direct drive illumination uniformity for the Laser MegaJoule facility  

NASA Astrophysics Data System (ADS)

The illumination uniformity provided during the initial imprinting phase of the laser foot pulse in a direct drive scenario at the Laser MegaJoule facility has been analyzed. This study analyzes the quality of the illumination of a spherical capsule and concerns the uniformity of the first shock generate in the absorber of an Inertial Confinement Fusion capsule. Four configurations making use of all or some of the 80 laser beams organized in the 20 quads of the cones at 49° and 131° with respect to the polar axis have been considered in order to assemble the foot pulse. Elliptical and circular super-gaussian laser intensity profiles taking into account beam-to-beam power imbalance (10%), pointing error (50 ?m), and target positioning (20 ?m) have been considered. It has been found that the use of the Polar Direct Drive technique can in some cases reduce the irradiation non-uniformity by a factor as high as 50%. In all cases, elliptical profile provides better results in comparison with the circular one and it is shown that the minimum of the non-uniformity is also a function of the capsule radius.

Temporal, M.; Canaud, B.; Garbett, W. J.; Ramis, R.

2014-01-01

276

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

277

Study of organic contamination induced by outgassing materials. Application to the Laser MégaJoule optics  

NASA Astrophysics Data System (ADS)

Organic contamination may decrease the targeted performances of coated surfaces. To study the contamination induced by surrounding materials, a method using a thermal extractor is presented in the first part of this work. Besides its normal operation (analyses of outgassing compounds from a material), this device is used in an original way to contaminate and decontaminate samples. Efficiency of contamination and decontamination protocols are assessed by automated thermal desorption and gas chromatography coupled with mass spectrometry and by secondary ion mass spectrometry coupled with a time of flight mass analyzer. This enables to study the contamination induced by a bulk material outgassing and to take in consideration the possible competition between outgassed species. This method is then applied to investigate contamination of Laser MégaJoule sol-gel coated optics by a retractable sheath. The impact of the temperature on the outgassing of the sheath has been highlighted. Increasing temperature from 30 to 50 °C enables the outgassing of organophosphorous compounds and increases the outgassing of oxygenated compounds and phthalates. Chemical analyses of contaminated optics have highlighted affinities between the sol-gel coating and phthalates and organophosphorous, and low affinities with aromatics and terpens. Finally, samples with increasing levels of contamination have been realized. However a saturation phenomenon is observed at 90 ng cm-2.

Favrat, O.; Mangote, B.; Tovena-Pécault, I.; Néauport, J.

2014-02-01

278

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

NASA Astrophysics Data System (ADS)

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

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

1992-07-01

279

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

NASA Astrophysics Data System (ADS)

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 data covered a range of inlet and outlet operating conditions. The mass flow rate range single phase or two phase was 0.015 to 0.98 lbm/hr. The manufacturer's equation was found to overpredict the single phase hydrogen data by 10 percent and the two phase data by as much as 27 percent. Two modifications of the equation resulted in a data correlation that predicts both the single and two phase flow across the visco jet. The first modification was of a theoretical nature, and the second strictly empirical. The former reduced the spread in the two phase data. It was a multiplication factor of 1 - X applied to the manufacturer's equation. The parameter X is the flow quality downstream of the visco jet based on isenthalpic expansion across the device. The latter modification was a 10 percent correction term that correlated 90 percent of the single and two phase data to within +/- 10 percent scatter band.

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

280

Joule-Thomson valves for long term service in space cryocoolers  

NASA Astrophysics Data System (ADS)

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 closed loop coolers where periodic maintenance is allowed, the problem is overcome by using careful assembly techniques, pure process gases, warm filters and cold adsorbers. A more thorough approach is required for closed loop cryocoolers which must operate unattended for long periods. This paper presents the results of an effort to solve this problem. The causes of plugging are examined, and various ways to eliminate plugging are discussed. Finally, the development of a J-T defroster is explained. It is concluded that a combination of preventive measures and a defroster will reduce the chance of cooler failure by plugging to such a degree that J-T coolers can be used for long term space missions.

Lester, J. M.; Benedict, B.

1985-05-01

281

Properties of Gas Mixtures and Their Use in Mixed-Refrigerant Joule-Thomson Refrigerators  

NASA Astrophysics Data System (ADS)

The Joule-Thomson (J-T) effect has been widely used for achieving low temperatures. In the past few years, much progress has been made in better understanding the working mechanism of the refrigeration method and in developing prototypes for different applications. In this talk, there are three aspects of our research work to be discussed. First, some special thermal properties of the mixtures for achieving liquid nitrogen temperature range will be presented. Secondly, some important conclusions from the optimization of various mixed-refrigerant J-T cycles such as a simple J-T cycle and an auto-cascade mixed-refrigerant J-T cycle will be presented. Moreover, an auto-cascade, mixed-refrigerant J-T refrigerator with a special mixture capable of achieving about 50K will be mentioned. Finally, various prototypes based on the mixed-refrigerant refrigeration technology will be described. These applications include miniature J-T cryocoolers for cooling infrared detectors and high-temperature superconducting devices, cryosurgical knife for medical treatment, low-temperature refrigerators for biological storage and so forth. The on-going research work and unanswered questions for this technology will be also discussed.

Luo, E.; Gong, M.; Wu, J.; Zhou, Y.

2004-06-01

282

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

283

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.

284

Nonlinear aspects of the solar coronal heating  

NASA Astrophysics Data System (ADS)

The heating of the solar coronal plasma has remained one of the most important problems in solar physics. An explanation of the electron and ion heating rests on the identification of the energy source and appropriate physical mechanisms via which the energy can be channelled to the plasma particles. In this paper, we discuss two important nonlinear aspects of the electron and ion heating caused by finite amplitude obliquely propagating dispersive Alfvén (DA) waves and magnetic field-aligned circularly polarized electromagnetic ion cyclotron Alfvén (EMICA) waves that may exist in the solar terrestrial environment. Specifically, DA waves may contribute to the solar coronal electron heating via Joule heating involving electron wave interactions, and resonant ion EMICA wave interactions may contribute to differential ion heating in the solar corona.

Shukla, P. K.; Bingham, R.; Eliasson, B.; Dieckmann, M. E.; Stenflo, L.

2006-12-01

285

Experimental and numerical investigation into the joule heating effect for electrokinetically driven microfluidic chips utilizing total internal reflection fluorescence microscopy  

Microsoft Academic Search

This paper presents a detection scheme for analyzing the temperature distribution nearby the channel wall in a microfluidic\\u000a chip utilizing a temperature-dependent fluorescence dye. An advanced optical microscope system—total internal reflection fluorescence\\u000a microscope (TIRFM) is used for measuring the temperature distribution on the channel wall at the point of electroosmotic flow\\u000a in an electrokinetically driven microfluidic chip. In order to

Lung-Ming Fu; Jing-Hui Wang; Wen-Bo Luo; Che-Hsin Lin

2009-01-01

286

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

287

CROSS-DISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY: Analysis and finite element simulation of electromagnetic heating in the nitride MOCVD reactor  

NASA Astrophysics Data System (ADS)

Electromagnetic field distribution in the vertical metal organic chemical vapour deposition (MOCVD) reactor is simulated by using the finite element method (FEM). The effects of alternating current frequency, intensity, coil turn number and the distance between the coil turns on the distribution of the Joule heat are analysed separately, and their relations to the value of Joule heat are also investigated. The temperature distribution on the susceptor is also obtained. It is observed that the results of the simulation are in good agreement with previous measurements.

Li, Zhi-Ming; Hao, Yue; Zhang, Jin-Cheng; Xu, Sheng-Rui; Ni, Jin-Yu; Zhou, Xiao-Wei

2009-11-01

288

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

289

Variation of TMA Optical Spectra With Altitude as Observed During the JOULE-2 and HEX-2 Rocket Experiments  

NASA Astrophysics Data System (ADS)

During the JOULE-2 and HEX-2 rocket experiments a total of 7 rockets releasing tri-methyl aluminum (TMA) were launched from the Poker Flat Research Range. Four of the TMA trails were observed with a video imaging spectrograph located at Poker Flat: two during the JOULE-2 experiment in the 400 to 650 nm wavelength range, and two during the HEX-2 experiment in the 615 nm to 890 nm wavelength range. The spectrograph has an angular extent of about 10 degrees along the slit and a spectral resolution of 8 nm. The spectra show that the TMA emissions comprise a broadband continuum, with no significant narrowband emission or molecular band structure apparent. When spectra are compared for TMA released at different altitudes, the continuum shows no difference between 400 nm and 600 nm. However, at wavelengths longer than 650 nm, spectra from 100 km altitude show 20 to 40% greater intensity than spectra from 90 km, when normalized at 615 nm. Proposed mechanisms for photon production in TMA generally invoke a catalytic cycle of chemiluminescence reactions between AlO and O, O2, and in some cases OH and H2O. We report the quantitative variation in spectrum with altitude for TMA in these two releases, ongoing work to use (rarely calibrated) literature data on AlO chemiluminescent reactions to determine the most likely mechanism for photon production in TMA releases, and speculate on whether the spectrum of a TMA release can help reveal geophysical information in the upper atmosphere.

Hampton, D. L.; Conde, M.; Craven, J. D.

2007-12-01

290

Mechanisms of heat transport across a nano-scale gap in heat assisted magnetic recording  

NASA Astrophysics Data System (ADS)

This paper compares different mechanisms of heat transport across nano-scale gaps and discusses the role of electromagnetic phenomena in heat transport in general nano-scale layered structures. The results of the analysis suggest that heat transfer across sub-5 nm gaps like that appearing in prototypes of heat assisted magnetic recording (HAMR) systems is dominated by direct intermolecular interactions between the separated bodies and is little affected by electromagnetic radiation. The analysis further suggests that local heating for HAMR with sub-5 nm spacing can be more efficiently achieved by a Joule heater that is simpler to fabricate than laser-based optical systems and is less destructive for the nano-scale transducers than laser radiation, which may lead to their structural damage and short duration life of nanoscale transducers.

Budaev, Bair V.; Bogy, David B.

2012-06-01

291

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

292

Joule-Thomson inversion curves of mixtures by molecular simulation in comparison to advanced equations of state: natural gas as an example  

Microsoft Academic Search

Molecular modelling and simulation as well as four equations of state (EOS) are applied to natural gas mixtures regarding Joule-Thomson (JT) inversion. JT inversion curves are determined by molecular simulation for six different natural gas mixtures consisting of methane, nitrogen, carbon dioxide and ethane. These components are also regarded as pure fluids, leading to a total of ten studied systems.

J. Vrabec; A. Kumar; H. Hasse

2009-01-01

293

Joule–Thomson inversion curves of mixtures by molecular simulation in comparison to advanced equations of state: Natural gas as an example  

Microsoft Academic Search

Molecular modelling and simulation as well as four equations of state (EOS) are applied to natural gas mixtures regarding Joule–Thomson (JT) inversion. JT inversion curves are determined by molecular simulation for six different natural gas mixtures consisting of methane, nitrogen, carbon dioxide and ethane. These components are also regarded as pure fluids, leading to a total of 10 studied systems.

Jadran Vrabec; Ashish Kumar; Hans Hasse

2007-01-01

294

Existence and uniqueness for the equations of the joule-thomson effect  

Microsoft Academic Search

The electrical heating of a conductor obeying the Wiedemann-Pranz law is studied taking into account the Thomson's effect. Using a suitable transformation, the nonlinear elliptic system governing the problem is put in divergence form. The new formulation permits to find a bound for the temperature, to prove a theorem of existence and, in a special case, a result of uniqueness

Giovanni Cimatti

1991-01-01

295

Experimental investigation on mixed refrigerant Joule-Thomson cryocooler with flammable and non-flammable refrigerant mixtures  

NASA Astrophysics Data System (ADS)

The mixed refrigerant Joule-Thomson (MR J-T) cryocoolers have a wide application area covering the temperature range from 80 K to 200 K. The significant advantages of the system are simplicity of its design and working reliability with high level performance. The present paper discusses the experimental results of MR J-T cooler with different flammable and non-flammable mixture compositions. The work highlights the use of pressure-enthalpy and temperature-enthalpy diagrams for these mixtures to support the experimental results. A record lowest temperature of 65 K and a cooling capacity of 6 W at 80 K are obtained for a single stage MR J-T system starting at 300 K. Further, using a mixture of minimum flammable refrigerants, temperatures below 100 K is achieved.

Walimbe, N. S.; Narayankhedkar, K. G.; Atrey, M. D.

2010-10-01

296

Scaling, stability, and fusion mechanisms. Studies using plasma focus devices from tens of kilojoules to tenth of joules  

SciTech Connect

Fusion studies using plasma focus devices from tens of kilojoules to less than one joule performed at the Chilean Nuclear Energy Commission are presented. The similarity of the physical behavior and the scaling observed in these machines are emphasized. Experiments on actual devices show that scaling holds at least through six order of magnitude. In particular all of these devices, from the largest to the smallest, keep the same quantity of energy per particle. Therefore, fusion reactions are possible to be obtained in ultraminiature devices (driven by generators of 0.1 J), as they are in the bigger devices (driven by generators of 1 MJ). However, the stability of the plasma depends on the size and energy of the device.

Soto, Leopoldo; Pavez, Cristian; Moreno, Jose; Cardenas, Miguel [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)

2009-01-21

297

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

298

Use of a Joule-Thomson micro-refrigerator to cool a radio-frequency coil for magnetic resonance microscopy  

NASA Astrophysics Data System (ADS)

A method is described for cryogenically cooling a rf detector coil, as used in high-resolution magnetic resonance imaging (MRI), to enhance image signal-to-noise ratio (SNR). By incorporating the rf coil into a Joule-Thomson micro-refrigerator, the coil is precision-cooled to 70 K using only a source of high-pressure nitrogen gas at room temperature, avoiding the need for liquid cryogens. The rf coil is insulated by a glass vacuum dewar that permits its use in proximity to biological tissues. Design and operation of the cryogenic system are described and its performance is demonstrated in a 1.5 T clinical MRI scanner with images of a water phantom and a sheep intervertebral disc specimen. SNR gains of two to three times were obtained, compared to a similar coil at room temperature. The potential of this technology for local high-resolution MRI is discussed.

Wright, A. C.; Song, H. K.; Elliott, D. M.; Wehrli, F. W.

2005-01-01

299

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

300

The solar coronal electron heating by short wavelength electromagnetic modes  

NASA Astrophysics Data System (ADS)

The electron heating of the solar coronal plasma has remained as one of the most important problems in solar physics. An explanation of the electron heating rests on the identification of the energy source and appropriate physical mechanisms via which the energy can be channelled to the electrons. Our objective here is to present an estimate for the electron heat in grate in the presence of finite amplitude short wavelength in comparison with the ion gyroradius dispersive electromagnetic (SWDEM) waves that propagate obliquely to the magnetic field in the solar corona, Specifically, it is demonstrated that the SWDEM waves can significantly contribute to the solar coronal electron heating via Joule heating involving electron-SWEDEM wave interactions. .

Shukla, Padma; Bingham, Robert; Stenflo, Lennart; Eliasson, B.

2010-11-01

301

The solar coronal electron heating by short wavelength electromagnetic modes  

NASA Astrophysics Data System (ADS)

The electron heating of the solar coronal plasma has remained as one of the most important problems in solar physics. An explanation of the electron heating rests on the identification of the energy source and appropriate physical mechanisms via which the energy can be channelled to the electrons. Our objective here is to present an estimate for the electron heating rate in the presence of finite amplitude short wavelength (in comparison with the ion gyroradius) dispersive electromagnetic (SWDEM) waves that propagate obliquely to the magnetic field in the solar corona. Specifically, it is demonstrated that the SWDEM waves can significantly contribute to the solar coronal electron heating via Joule heating involving electron-SWDEM wave interactions.

Shukla, P. K.; Bingham, R.

2006-10-01

302

Heat transfer coefficient measurements for mixed gas working fluids at cryogenic temperatures  

Microsoft Academic Search

The use of mixed gas working fluids has become common in Joule–Thomson type cryocoolers for a variety of applications. However, there is very little data or theory currently available regarding the heat transfer coefficient associated with these multi-component, multi-phase mixtures at cryogenic temperatures. This paper describes an experimental test facility and procedure that has been used to make careful measurements

Gregory Nellis; Cory Hughes; John Pfotenhauer

2005-01-01

303

Assessment of Zr–V–Fe getter alloy for gas-gap heat switches  

Microsoft Academic Search

A commercial Zr–V–Fe alloy (i.e. SAES Getters trade name alloy St-172) has been assessed as reversible hydrogen storage material for use in actuators of gas-gap heat switches. For applications involving hydride compressors in closed-cycle Joule–Thomson sorption cryocoolers, the actuator need to produce a conducting (i.e. ON) state pressure above 670 Pa and an insulating (i.e. OFF) state pressure below 0.13

M Prina; J. G Kulleck; R. C Bowman

2002-01-01

304

Aerothermal Heating Predictions for Mars Microprobe  

NASA Technical Reports Server (NTRS)

A combination of computational predictions and experimental measurements of the aerothermal heating expected on the two Mars Microprobes during their entry to Mars are presented. The maximum, non-ablating, heating rate at the vehicle's stagnation point (at alpha = 0 degrees) is predicted for an undershoot trajectory to be 194 Watts per square centimeters with associated stagnation point pressure of 0.064 atm. Maximum stagnation point pressure occurs later during the undershoot trajectory and is 0.094 atm. From computations at seven overshoot-trajectory points, the maximum heat load expected at the stagnation point is near 8800 Joules per square centimeter. Heat rates and heat loads on the vehicle's afterbody are much lower than the forebody. At zero degree angle-of-attack, heating over much of the hemi-spherical afterbody is predicted to be less than 2 percent of the stagnation point value. Good qualitative agreement is demonstrated for forebody and afterbody heating between CFD calculations at Mars entry conditions and experimental thermographic phosphor measurements from the Langley 20-Inch Mach 6 Air Tunnel. A novel approach which incorporates six degree-of-freedom trajectory simulations to perform a statistical estimate of the effect of angle-of-attack, and other off-nominal conditions, on heating is included.

Mitcheltree, R. A.; DiFulvio, M.; Horvath, T. J.; Braun, R. D.

1998-01-01

305

The finite-amplitude behavior of the Joule mode under astrophysical conditions  

NASA Technical Reports Server (NTRS)

Magnetized astrophysical plasmas reveal a great deal of structure when spatially resolved. One possible explanation for this structuring is based on the existence of filamenting instabilities driven by radiation. In this paper, previous linear calculations are extended by considering the weakly nonlinear (finite-amplitude) development of such filamenting instabilities in magnetized unstratified plasmas. It is shown that under most conditions these instabilities (in particular, the Jouse model) are unstable at finite amplitude; in particular, in the temperature and plasma-beta domains characteristic of, for example, much of the solar transition region, these modes - which can be linearly stable under these conditions - become unstable to finite-amplitude perturbations. The relevance of this to the problem of heating the solar low transition region by current dissipation is discussed.

Bodo, G.; Massaglia, S.; Rosner, R.; Ferrari, A.

1991-01-01

306

Radio-frequency heating plans for CTX  

SciTech Connect

Even with present efforts to reduce impurity levels in the CTX experiment, electron thermal conduction and residual impurity radiation may still cause substantial cooling of the plasma toroid by the time it has formed inside the flux conserver. Auxiliary heating of the stable structure is needed. If an energy of several hundred joules is to be supplied over a hundred-microsecond time scale, several megawatts of power are required. Such levels can be achieved from pulsed rf sources at frequencies in the ion-cyclotron range and below (0.1 to 10 MHz). Encouraged by the successes reported from other experiments in this regime, we are undertaking the development of an rf heating system for CTX.

Knox, S.O.; Wright, B.L.

1981-01-01

307

Measurement and control of the movable coil position of a joule balance with a system based on a laser heterodyne interferometer  

NASA Astrophysics Data System (ADS)

A system based on laser heterodyne interferometer is proposed in this paper to measure and control the movable coil position of a joule balance. A damping system is used to suppress the movement of the movable coil in the horizontal direction while a piezoelectric ceramic control unit with PID controller is used to inhibit the vibration and long term drift of the movable coil in the vertical direction. The effectiveness of the proposed method in measuring and controlling the movable coil position of a joule balance is proved through experiments. Experimental results indicate that the displacement of the movable coil in the vertical direction can be reduced from 400 to 50 nm while its drift is successfully inhibited.

Yang, Hongxing; Lu, Yunfeng; Hu, Pengcheng; Li, Zhengkun; Zeng, Tao; He, Qing; Zhang, Zhonghua; Tan, Jiubin

2014-06-01

308

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

309

Nanoparticle heating: nanoscale to bulk effects of electromagnetically heated iron oxide and gold for biomedical applications  

NASA Astrophysics Data System (ADS)

Biomedical applications of nanoparticle heating range in scale from molecular activation (i.e. molecular beacons, protein denaturation, lipid melting and drug release), cellular heating (i.e. nanophotolysis and membrane permeability control and rupture) to whole tumor heating (deep and superficial). This work will present a review on the heating of two classes of biologically compatible metallic nanoparticles: iron oxide and gold with particular focus on spatial and temporal scales of the heating event. The size range of nanoparticles under discussion will focus predominantly in the 10 - 200 nm diameter size range. Mechanisms of heating range from Néelian and Brownian relaxation due to magnetic susceptibility at 100s of kHz, optical absorption due to VIS and NIR lasers and "Joule" heating at higher frequency RF (13.56 MHz). The heat generation of individual nanoparticles and the thermal responses at nano-, micro-, and macroscales are presented. This review will also discuss how to estimate a specific absorption rate (SAR, W/g) based on individual nanoparticles heating in bulk samples. Experimental setups are designed to measure the SAR and the results are compared with theoretical predictions.

Qin, Zhenpeng; Etheridge, Michael; Bischof, John C.

2011-02-01

310

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

Microsoft Academic Search

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

A. Piotrowska; M. Chorowski

2008-01-01

311

Numerical studies of fluid leakage from a geologic disposal reservoir for CO2 show self-limiting feedback between fluid flow and heat transfer  

NASA Astrophysics Data System (ADS)

Leakage of CO2 from a hypothetical geologic storage reservoir along an idealized fault zone has been simulated, including transitions between supercritical, liquid, and gaseous CO2. We find strong non-isothermal effects due to boiling and Joule-Thomson cooling of expanding CO2. Leakage fluxes are limited by limitations in conductive heat transfer to the fault zone. The interplay between multiphase flow and heat transfer effects produces non-monotonic leakage behavior.

Pruess, Karsten

2005-07-01

312

Numerical Studies of Fluid Leakage from a Geologic DisposalReservoir for CO2 Show Self-Limiting Feedback between Fluid Flow and HeatTransfer  

SciTech Connect

Leakage of CO2 from a hypothetical geologic storage reservoir along an idealized fault zone has been simulated, including transitions between supercritical, liquid, and gaseous CO2. We find strong non-isothermal effects due to boiling and Joule-Thomson cooling of expanding CO2. Leakage fluxes are limited by limitations in conductive heat transfer to the fault zone. The interplay between multiphase flow and heat transfer effects produces non-monotonic leakage behavior.

Pruess, Karsten

2005-03-22

313

Numerical studies of fluid leakage from a geologic disposal reservoir for CO2 show self-limiting feedback between fluid flow and heat transfer  

Microsoft Academic Search

Leakage of CO2 from a hypothetical geologic storage reservoir along an idealized fault zone has been simulated, including transitions between supercritical, liquid, and gaseous CO2. We find strong non-isothermal effects due to boiling and Joule-Thomson cooling of expanding CO2. Leakage fluxes are limited by limitations in conductive heat transfer to the fault zone. The interplay between multiphase flow and heat

Karsten Pruess

2005-01-01

314

Heating with waste heat  

SciTech Connect

Most of the power consumed in the gaseous diffusion process is converted into heat of compression, which is removed from the process gas and rejected into the atmosphere by recirculating cooling water over cooling towers. The water being handled through the X-333 and X-330 Process Buildings can be heated to 140 to 150/sup 0/F for heating use. The Gas Centrifuge Enrichment Plant is provided with a recirculating heating water (RHW) system which uses X-330 water and wasted heat. The RHW flow is diagrammed. (DLC)

Beabout, R.W.

1986-09-02

315

Beam-driven return current instability and anomalous plasma heating in solar flares  

NASA Astrophysics Data System (ADS)

The authors consider the problem of ion-acoustic wave generation, and resultant anomalous Joule heating, by a return current driven unstable by a small-area thick-target electron beam in solar flares. They demonstrate the existence of two quite distinct types of ion-acoustic unstable heating regimes: marginally stable heating and a "catastrophic" heating regime. For the marginally stable case electron and ion heating equations are solved numerically. Rapid anomalous Ohmic heating occurs then in a substantial plasma volume. This large hot plasma emits thermal bremsstrahlung hard X-rays (?20 keV) comparable to, or exceeding, the nonthermal bremsstrahlung. This means that with small beam areas, this indirect mechanism can result in a higher hard X-ray bremsstrahlung efficiency than in a conventional collisional thick target. The catastrophic heating regime is discussed qualitatively.

Cromwell, D.; McQuillan, P.; Brown, J. C.

1988-09-01

316

Experimental study of a mixed refrigerant Joule-Thomson cryocooler using a commercial air-conditioning scroll compressor  

NASA Astrophysics Data System (ADS)

Mixed refrigerant Joule-Thomson (MR J-T) cryocoolers have been used to create cryogenic temperatures and are simple, efficient, cheap, and durable. However, compressors for MR J-T cryocoolers still require optimization. As the MR J-T cryocooler uses a commercial scroll compressor developed for air-conditioning systems, compressor overheating due to the use of less optimized refrigerants may not be negligible, and could cause compressor malfunction due to burn-out of scroll tip seals. Therefore, in the present study, the authors propose procedures to optimize compressor operation to avoid the overheating issue when the MR J-T cryocooler is used with a commercial oil lubricated scroll compressor, and the present experimental results obtained for a MR J-T cryocooler. A single stage 1.49 kW (2 HP) scroll compressor designed for R22 utilizing a mixture of nitrogen and hydrocarbons was used in the present study. As was expected, compressor overheating and irreversible high temperatures at a compressor discharge port were found at the beginning of compressor operation, which is critical, and hence, the authors used a water injection cooling system for the compressor to alleviate temperature overshooting. In addition, a portion of refrigerant in the high-pressure stream was by-passed into the compressor suction port. This allowed an adequate compression ratio, prevented excessive temperature increases at the compressor discharge, and eventually enabled the MR J-T cryocooler to operate stably at 121 K. The study shows that commercial oil lubricated scroll compressors can be used for MR J-T cryocooling systems if care is exercised to avoid compressor overheating.

Lee, Jisung; Lee, Kyungsoo; Jeong, Sangkwon

2013-05-01

317

Highly lead-loaded red plastic scintillators as an X-ray imaging system for the Laser Mega Joule  

SciTech Connect

The scope of this project intends to record spatially resolved images of core shape and size of a DT micro-balloon during Inertial Confinement Fusion (ICF) experiments at Laser Mega Joule facility (LMJ). We need to develop an X-ray imaging system which can operate in the radiative background generated by an ignition shot of ICF. The scintillator is a part of the imaging system and has to gather a compromise of scintillating properties (scintillating efficiency, decay time, emission wavelength) so as to both operate in the hard radiative environment and to allow the acquisition of spatially resolved images. Inorganic scintillators cannot be used because no compromise can be found regarding the expected scintillating properties, most of them are not fast enough and emit blue light. Organic scintillators are generally fast, but present low X-ray absorption in the 10 to 40 keV range, that does not permit the acquisition of spatially resolved images. To this aim, we have developed highly lead-loaded and red-fluorescent fast plastic scintillators. Such a combination is not currently available via scintillator suppliers, since they propose only blue-fluorescent plastic scintillators doped with up to 12%w Pb. Thus, incorporation ratio up to 27%w Pb has been reached in our laboratory, which can afford a plastic scintillator with an outstanding Z{sub eff} close to 50. X-rays in the 10 to 40 keV range can thus be detected with a higher probability of photoelectric effect than for classic organic scintillators, such as NE102. The strong orange-red fluorescence can be filtered, so that we can eliminate residual Cerenkov light, generated by {gamma}-ray absorption in glass parts of the imaging system. Decay times of our scintillators evaluated under UV excitation were estimated to be in the range 10 to 13 ns. (authors)

Hamel, M.; Normand, S. [CEA, LIST, Laboratoire Capteurs et Architectures Electroniques, F-91191 Gif-sur-Yvette (France); Turk, G.; Darbon, S. [CEA, DAM, DIF, F-91297 Arpajon (France)

2011-07-01

318

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

319

An evaluation of the inlet flow reduction for a cable in conduit conductor by rapid heating  

NASA Astrophysics Data System (ADS)

The flow reduction of forced flow superconducting coil with a cable in conduit (CIC) conductor has been studied for AC losses due to pulsed operation. In this paper, the flow reduction by rapid heating is described for forced flow superconducting coil with a CIC conductor. The phenomenon of flow reduction of the forced flow coil has been applied for coil quench detection and has been developed by Japan Atomic Energy Research Institute (JAERI). It is named the "fluid method" and essential technology for quench detection of large-scale forced flow superconducting coil as fusion magnets and superconducting magnetic energy storage (SMES) coil. In the fluid method, the inlet flow reduction is caused by Joule heating on the normal zone of superconducting coil. The fluid method has no electric noise in its detection. This is an advantage for pulsed operation in comparison with other electrical quench detection systems. On the other hand, there are no quantitative considerations between the inlet flow reduction and Joule heating of the coil inside in previous studies. The flow reduction for the quench detection has been determined by the operation experience of forced flow superconducting coil. The purpose of this paper is an estimation of the relation between the inlet flow reduction and Joule heating at coil quench. First, the inlet flow reduction was obtained by experiment in which the sample has an inductive heater for the quench emulation. Second, the evaluation model was proposed and its model showed good agreement between the inlet flow reduction and heat generation of the coil inside by rapid heating as coil quench.

Sugimoto, Makoto; Isono, Takaaki; Koizumi, Norikiyo; Nishijima, Gen; Matsui, Kunihiro; Nunoya, Yoshihiko; Takahashi, Yoshikazu; Tsuji, Hiroshi

320

MHD three-dimensional flow of couple stress fluid with Newtonian heating  

NASA Astrophysics Data System (ADS)

Effects of Newtonian heating on the magnetohydrodynamic (MHD) three-dimensional flow past a stretching surface are analyzed. Mathematical formulation is completed using constitutive equations of couple stress fluid. A constant magnetic field normal to the surface is applied. Viscous dissipation and Joule heating effects are present. The transformation procedure reduces the involved partial differential equations into the ordinary differential equations. Series solutions of the resulting systems are constructed. The convergence of the obtained series solutions is seen through graphical results and tabular values. Numerical values of skin friction and the Nusselt number for different parameters are also tabulated and analyzed.

Ramzan, M.; Farooq, M.; Alsaedi, A.; Hayat, T.

2013-05-01

321

Evaluation of the invasion heat for the HTS current lead using YBCO  

NASA Astrophysics Data System (ADS)

Current leads using high- TC superconductors (HTS current leads) are one of cryogenic key devices to assemble compact superconducting magnets such as applied for maglev trains etc. It is essential to evaluate effective thermal conductance through a HTS current lead package together with evaluating Joule heat and critical current for efficient design that has high current capacity and low heat invasion. We have designed the 500 A class HTS current lead package using a YBCO rod whose size is ? 3 × 30 mm, and developed an apparatus to measure its heat invasion. Temperature drop as a function of heat flow between the two ends of the package was measured by a conventional steady heat flow method. The quantity of heat invasion of the package under typical practical conditions, from 80 K hot end to 20 K cold end, was 163 mW. This value was simulated to the total value of 158 mW by counting contributions of all the component materials.

Endoh, R.; Kato, H.; Izumi, T.; Shiohara, Y.

322

Numerical studies of fluid leakage from a geologic disposal reservoir for CO{sub 2} show self-limiting feedback between fluid flow and heat transfer - article no. L14404  

SciTech Connect

Leakage of CO{sub 2} from a hypothetical geologic storage reservoir along an idealized fault zone has been simulated, including transitions between supercritical, liquid, and gaseous CO{sub 2}. We find strong non-isothermal effects due to boiling and Joule-Thomson cooling of expanding CO{sub 2}. Leakage fluxes are limited by limitations in conductive heat transfer to the fault zone. The interplay between multiphase flow and heat transfer effects produces non-monotonic leakage behavior.

Pruess, K. [University of California at Berkeley, Berkeley, CA (US). Lawrence Berkeley Lab.

2005-07-29

323

Multi-meter fiber-delivery and pulse self-compression of milli-Joule femtosecond laser and fiber-aided laser-micromachining.  

PubMed

We report on damage-free fiber-guidance of milli-Joule energy-level and 600-femtosecond laser pulses into hypocycloid core-contour Kagome hollow-core photonic crystal fibers. Up to 10 meter-long fibers were used to successfully deliver Yb-laser pulses in robustly single-mode fashion. Different pulse propagation regimes were demonstrated by simply changing the fiber dispersion and gas. Self-compression to ~50 fs, and intensity-level nearing petawatt/cm2 were achieved. Finally, free focusing-optics laser-micromachining was also demonstrated on different materials. PMID:24921775

Debord, B; Alharbi, M; Vincetti, L; Husakou, A; Fourcade-Dutin, C; Hoenninger, C; Mottay, E; Gérôme, F; Benabid, F

2014-05-01

324

A combined pressure-controlled scanning calorimetry and Monte Carlo determination of the Joule-Thomson inversion curve. Application to methane.  

PubMed

A combination of a pressure-controlled scanning calorimetry (PCSC) and Monte Carlo simulations (MCS) is presented for an unequivocal determination of the Joule-Thomson inversion curve (JTIC) with high accuracy over wide ranges of pressure and temperature. The MCS performed with the fluctuation method are fast and easy to operate, but the results can vary significantly depend on the set of primary molecular data needed for the calculations. The PCSC is an experimental and more laborious technique, but supplies data of high quality. Thus, it can be used to check the MCS data and to verify the molecular parameters used for the calculations. Such a combined procedure was used in the present study for determination of the JTIC for methane, for which a correlation equation was established valid from 302.9 to 586.5 K. A combination of a direct experimental technique with molecular simulations permits also to better understand the complex behavior of the Joule-Thomson inversion phenomenon over wide ranges of pressure and temperature. PMID:16539511

Bessières, D; Randzio, S L; Piñeiro, M M; Lafitte, Th; Daridon, J-L

2006-03-23

325

Memory switching in In-Te glasses: results of heat-transport measurements  

NASA Astrophysics Data System (ADS)

Even 33 years after the discovery of electrical switching in chalcogenide glasses, a complete understanding of the mechanisms responsible for this phenomenon is lacking. It is believed that threshold switching in chalcogenide glasses is electronic in origin whereas memory switching is of thermal origin. According to the thermal model, the ON state during memory switching is caused by a thermal breakdown of the steady state of the material when the heat generated by Joule heating cannot be removed fast enough by thermal conduction. Joule heating causes crystallization of the glass into fine filaments resulting in excess carrier concentration in the current path due to the large electric field present. Even though electrical conductivity and related properties of a number of materials have been investigated during and after switching, no measurements seem to have been done to determine the variation in thermal conductivity and related properties during switching. In this paper we report the results of our measurements of thermal conductivity and heat capacity of In-Te glasses, which exhibit clear memory type electrical switching at threshold fields in 80-140 V cm-1 range. Measurements have been made on bulk samples using an improved photothermal technique. Results show that thermal conductivity of the samples increase considerably during electrical switching, whereas heat capacity remains more or less constant. The results are discussed in the light of the thermal model for memory switching applicable to Te-based chalcogenide glasses.

Rajesh, R.; Philip, J.

2003-02-01

326

Bipolar resistance switching in high-performance Cu\\/ZnO:Mn\\/Pt nonvolatile memories: active region and influence of Joule heating  

Microsoft Academic Search

Manganese-doped ZnO dielectric films sandwiched between Cu and Pt electrodes were prepared and investigated for nonvolatile resistive memory applications. These structures exhibit promising bipolar resistive switching (RS) behavior with a large ON\\/OFF ratio (~103), suitable threshold voltages (1.4 and -0.7 V for SET and RESET, respectively), long retention (>104 s at 85 °C) and low write current (10 muA). A

Yu Chao Yang; Feng Pan; Fei Zeng

2010-01-01

327

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

Microsoft Academic Search

The governments of the United Stated of America and the Russian Federation (RF) signed an Agreement September 1, 2000 to dispose of weapons plutonium that has been designated as no longer required for defense purposes. The Agreement declares that each country will disposition 34MT of excess weapons grade plutonium from their stockpiles. The preferred disposition technology is the fabrication of

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

2004-01-01

328

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

329

Heat Without Heat  

NASA Astrophysics Data System (ADS)

Logic of the Second Law of Thermodynamics demands acquisition of naked entropy. Accordingly, the leanest liaison between systems is not a diathermic membrane, it is a purely informational tickler, leaking no appreciable energy. The subsystem here is a thermodynamic universe, which gets `heated' entropically, yet without gaining calories. Quantum Mechanics graciously supports that(Lubkin, E. and Lubkin, T., International Journal of Theoretical Physics,32), 933-943 (1993) (at a cost of about 1 bit) through entanglement---across this least permeable of membranes---with what is beyond that universe. Heat without heat(Also v. forthcoming Proceedings of the 4th Drexel University Conference of September 1994) is the aspirin for Boltzmann's headache, conserving entropy in mechanical isolation, even while increasing entropy in thermodynamic isolation.

Lubkin, Elihu

1997-04-01

330

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

331

Electrical heating of soils using high efficiency electrode patterns and power phases  

DOEpatents

Powerline-frequency electrical (joule) heating of soils using a high efficiency electrode configuration and power phase arrangement. The electrode configuration consists of several heating or current injection electrodes around the periphery of a volume of soil to be heated, all electrodes being connected to one phase of a multi-phase or a single-phase power system, and a return or extraction electrode or electrodes located inside the volume to be heated being connected to the remaining phases of the multi-phase power system or to the neutral side of the single-phase power source. This electrode configuration and power phase arrangement can be utilized anywhere where powerline frequency soil heating is applicable and thus has many potential uses including removal of volatile organic compounds such as gasoline and tricholorethylene (TCE) from contaminated areas.

Buettner, Harley M. (Livermore, CA)

1999-01-01

332

Heat Pipes  

ERIC Educational Resources Information Center

Describes the construction, function, and applications of heat pipes. Suggests using the heat pipe to teach principles related to heat transfer and gives sources for obtaining instructional kits for this purpose. (GS)

Lewis, J.

1975-01-01

333

Optical cell with periodic resistive heating for the measurement of heat, mass, and thermal diffusions in liquid mixtures  

SciTech Connect

A new technique for the measurement of heat, mass, and thermal diffusions in liquids has been developed. Similar to laser induced dynamic gratings, a temperature grating is created in the sample. Thermal expansion transforms the temperature into a refractive-index grating, which is read by diffraction of a readout laser beam. In a multicomponent mixture an additional concentration grating is formed by thermal diffusion driven by the temperature gradients of the temperature grating. Differently to laser induced dynamic grating experiments we use Joule heating instead of optical heating. For that purpose we have built cuvettes which have a grating of transparent conducting strips on the inner side of one of their windows. If heated by an electric current a temperature grating will build up in the sample. Both the heat equation and the extended diffusion equation have been solved in two dimensions to allow for quantitative data analysis. Our apparatus and method of analysis have been validated by measurements of heat, mass, and thermal diffusions in pure and binary liquids. Heat diffusion can be correctly determined as was shown for pure toluene, pure dodecane, and the symmetric mixture of isobutylbenzene dodecane. Mass and thermal diffusions were studied in the three symmetric mixtures of dodecane, isobutylbenzene, and tetralin. The obtained diffusion and Soret coefficients agree with the literature values within the experimental errors. Uncompensated transient heating effects limit the resolution of the experimental technique.

Hartung, M.; Koehler, W. [Physikalisches Institut, Universitaet Bayreuth, D-95440 Bayreuth (Germany)

2007-08-15

334

Optical cell with periodic resistive heating for the measurement of heat, mass, and thermal diffusions in liquid mixtures  

NASA Astrophysics Data System (ADS)

A new technique for the measurement of heat, mass, and thermal diffusions in liquids has been developed. Similar to laser induced dynamic gratings, a temperature grating is created in the sample. Thermal expansion transforms the temperature into a refractive-index grating, which is read by diffraction of a readout laser beam. In a multicomponent mixture an additional concentration grating is formed by thermal diffusion driven by the temperature gradients of the temperature grating. Differently to laser induced dynamic grating experiments we use Joule heating instead of optical heating. For that purpose we have built cuvettes which have a grating of transparent conducting strips on the inner side of one of their windows. If heated by an electric current a temperature grating will build up in the sample. Both the heat equation and the extended diffusion equation have been solved in two dimensions to allow for quantitative data analysis. Our apparatus and method of analysis have been validated by measurements of heat, mass, and thermal diffusions in pure and binary liquids. Heat diffusion can be correctly determined as was shown for pure toluene, pure dodecane, and the symmetric mixture of isobutylbenzene dodecane. Mass and thermal diffusions were studied in the three symmetric mixtures of dodecane, isobutylbenzene, and tetralin. The obtained diffusion and Soret coefficients agree with the literature values within the experimental errors. Uncompensated transient heating effects limit the resolution of the experimental technique.

Hartung, M.; Köhler, W.

2007-08-01

335

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

336

Heat pumps  

NSDL National Science Digital Library

What electric heating system is the most efficient in moderate climates? This reading, part of a series about the future of energy, introduces students to the modern heat pump. Students read about the efficiency of heat pumps and the three types currently being used in homes. A simple explanation of how a heat pump works is offered. Copyright 2005 Eisenhower National Clearinghouse

Project, Iowa P.

2004-01-01

337

Pathways to thermospheric heating via cusp electron precipitation  

NASA Astrophysics Data System (ADS)

The effects of precipitating soft electrons on the thermospheric mass density in the dayside cusp region are investigated using the coupled magnetosphere-ionosphere thermosphere model (CMIT). Simulation results show that while soft electrons have relatively minor effects on the interaction between the magnetosphere and ionosphere, they can significantly modify the mass density of the thermosphere in the dayside cusp region. Event simulations show that the CMIT model is capable of reproducing the mass density enhancement measured by the CHAMP and GRACE satellite at 400 km. The efficiencies of the direct and indirect thermospheric heating processes associated with precipitating soft electrons are investigated using ideal and event-based CMIT simulations. Preliminary results show that direct heating from soft electrons to thermospheric neutrals only has little effect on the neutral temperature and density, and indirect heating is the dominant process in the thermospheric neutral density enhancement. In the indirect heating process, precipitating soft electrons enhance the altitude profile of F-region Pedersen conductivity, which modifies the altitude distribution of the Joule heating in the cusp region and causes the enhancement of neutral temperature and density more efficiently than the direct heating process.

Zhang, B.; Varney, R. H.; Lotko, W.; Wiltberger, M. J.; Wang, W.; Lei, J.; Lyon, J.; Schmitt, P.

2013-12-01

338

Heat transfer in microwave heating  

NASA Astrophysics Data System (ADS)

Heat transfer is considered as one of the most critical issues for design and implement of large-scale microwave heating systems, in which improvement of the microwave absorption of materials and suppression of uneven temperature distribution are the two main objectives. The present work focuses on the analysis of heat transfer in microwave heating for achieving highly efficient microwave assisted steelmaking through the investigations on the following aspects: (1) characterization of microwave dissipation using the derived equations, (2) quantification of magnetic loss, (3) determination of microwave absorption properties of materials, (4) modeling of microwave propagation, (5) simulation of heat transfer, and (6) improvement of microwave absorption and heating uniformity. Microwave heating is attributed to the heat generation in materials, which depends on the microwave dissipation. To theoretically characterize microwave heating, simplified equations for determining the transverse electromagnetic mode (TEM) power penetration depth, microwave field attenuation length, and half-power depth of microwaves in materials having both magnetic and dielectric responses were derived. It was followed by developing a simplified equation for quantifying magnetic loss in materials under microwave irradiation to demonstrate the importance of magnetic loss in microwave heating. The permittivity and permeability measurements of various materials, namely, hematite, magnetite concentrate, wüstite, and coal were performed. Microwave loss calculations for these materials were carried out. It is suggested that magnetic loss can play a major role in the heating of magnetic dielectrics. Microwave propagation in various media was predicted using the finite-difference time-domain method. For lossy magnetic dielectrics, the dissipation of microwaves in the medium is ascribed to the decay of both electric and magnetic fields. The heat transfer process in microwave heating of magnetite, which is a typical magnetic dielectric, was simulated by using an explicit finite-difference approach. It is demonstrated that the heat generation due to microwave irradiation dominates the initial temperature rise in the heating and the heat radiation heavily affects the temperature distribution, giving rise to a hot spot in the predicted temperature profile. Microwave heating at 915 MHz exhibits better heating homogeneity than that at 2450 MHz due to larger microwave penetration depth. To minimize/avoid temperature nonuniformity during microwave heating the optimization of object dimension should be considered. The calculated reflection loss over the temperature range of heating is found to be useful for obtaining a rapid optimization of absorber dimension, which increases microwave absorption and achieves relatively uniform heating. To further improve the heating effectiveness, a function for evaluating absorber impedance matching in microwave heating was proposed. It is found that the maximum absorption is associated with perfect impedance matching, which can be achieved by either selecting a reasonable sample dimension or modifying the microwave parameters of the sample.

Peng, Zhiwei

339

Heat Pipes  

NASA Technical Reports Server (NTRS)

Heat Pipes were originally developed by NASA and the Los Alamos Scientific Laboratory during the 1960s to dissipate excessive heat build- up in critical areas of spacecraft and maintain even temperatures of satellites. Heat pipes are tubular devices where a working fluid alternately evaporates and condenses, transferring heat from one region of the tube to another. KONA Corporation refined and applied the same technology to solve complex heating requirements of hot runner systems in injection molds. KONA Hot Runner Systems are used throughout the plastics industry for products ranging in size from tiny medical devices to large single cavity automobile bumpers and instrument panels.

1996-01-01

340

Heat Pipes  

NASA Technical Reports Server (NTRS)

Phoenix Refrigeration Systems, Inc.'s heat pipe addition to the Phoenix 2000, a supermarket rooftop refrigeration/air conditioning system, resulted from the company's participation in a field test of heat pipes. Originally developed by NASA to control temperatures in space electronic systems, the heat pipe is a simple, effective, heat transfer system. It has been used successfully in candy storage facilities where it has provided significant energy savings. Additional data is expected to fully quantify the impact of the heat pipes on supermarket air conditioning systems.

1991-01-01

341

Multiphysics Modeling for Dimensional Analysis of a Self-Heated Molten Regolith Electrolysis Reactor for Oxygen and Metals Production on the Moon and Mars  

NASA Technical Reports Server (NTRS)

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

Dominguez, Jesus; Sibille, Laurent

2010-01-01

342

New Li-ion Battery Evaluation Research Based on Thermal Property and Heat Generation Behavior of Battery  

NASA Astrophysics Data System (ADS)

We do a new Li-ion battery evaluation research on the effects of cell resistance and polarization on the energy loss in batteries based on thermal property and heat generation behavior of battery. Series of 18650 cells with different capacities and electrode materials are evaluated by measuring input and output energy which change with charge-discharge time and current. Based on the results of these tests, we build a model of energy loss in cells' charge-discharge process, which include Joule heat and polarization heat impact factors. It was reported that Joule heat was caused by cell resistance, which included DC-resistance and reaction resistance, and reaction resistance could not be easily obtained through routine test method. Using this new method, we can get the total resistance R and the polarization parameter ?. The relationship between R, ?, and temperature is also investigated in order to build a general model for series of different Li-ion batteries, and the research can be used in the performance evaluation, state of charge prediction and the measuring of consistency of the batteries.

Lv, Zhe; Guo, Xun; Qiu, Xin-ping

2012-12-01

343

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

344

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

345

Heated Goggles  

NASA Technical Reports Server (NTRS)

The electrically heated ski goggles shown incorporate technology similar to that once used in Apollo astronauts' helmet visors, and for the same reason-providing fogfree sight in an activity that demands total vision. Defogging is accomplished by applying heat to prevent moisture condensation. Electric heat is supplied by a small battery built into the h goggles' headband. Heat is spread across the lenses by means of an invisible coating of electrically conductive metallic film. The goggles were introduced to the market last fall. They were designed by Sierracin Corporation, Sylmar, California, specialists in the field of heated transparent materials. The company produces heated windshields for military planes and for such civil aircraft as the Boeing 747, McDonnell Douglas DC-10 and Lockheed L-1011 TriStar.

1978-01-01

346

Measurements of ions emission using ToF method and CR39 SSNTD in a Small Plasma Focus device of Hundreds of Joules  

NASA Astrophysics Data System (ADS)

Ion beam emission in plasma focus (PF) discharges was originally investigated to explain the strong forward anisotropy observed in the neutron emission when D2 is used as filling gas in the PF devices. Several properties of emitted deuteron beam, including its angular distribution and energy spectra in PF devices operating at energies from 1kJ to 1MJ, have been measured. At present there is a growing interest in the development of very small PF devices operating under 1kJ. As part of the very low energy (< 1kJ) PF devices physics characterization program carried out at the Chilean Nuclear Energy Commission, the charged particle emission is being studied when hydrogen (H2) and mixture (H2+ %Ar) is used as filling gas in the PF device. The experiments have been performed in a plasma focus device of 400 joules (PF-400J). In order to estimate the ion beam energy spectrum and its ionization degree, by means of the time of flight method, a graphite collector system operating in the bias ion collector mode was constructed. On the other hand, measurements of the energy and flux of the ions have been corroborated using CR39 SSNTD. Preliminary results mainly show the presence of hydrogen ions with an average energy of 40keV. Also, in some cases, copper (from anode) and aluminum (from insulator) ions with energies lower than 1keV have been observed.

Moreno, José; Pedreros, José; Soto, Leopoldo

2014-05-01

347

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

348

Magnetic and magnetoimpedance studies on controlled Joule annealed amorphous Co73Fe4.5Ni0.5Mn0.5Nb0.5Si4.2B16.8 alloy  

NASA Astrophysics Data System (ADS)

We report magnetic and magnetoimpedance (MI) properties of as-quenched and Joule annealed (with and without external magnetic field) amorphous Co73Fe4.5Ni0.5Mn0.5Nb0.5Si4.2B16.8 alloy composition. The Joule annealing in the presence of magnetic field induces not only surface microstructural changes but also favourable anisotropy. Dc magnetic measurements show controlled annealing enhances soft magnetic nature of the sample. Virgin ribbons show MS ˜ 125 emu/g with ?r ˜ 104 and exhibit large MI ratio of ˜100% at 3 MHz frequency. This MI ratio was further enhanced to 152% on Joule annealing (current density 0.85 × 107 A/m2) in the presence of applied magnetic field of 500 Oe. The field dependence MI shows a double-peak feature in as-spun ribbons, which is significantly enhanced for field annealed (FA) samples. The enhancement in MI and magnetic field sensitivity (?) in FA amorphous ribbons is attributed to the development of nanograins on the surface layer that strengthens the transverse magnetic structure.

Kumar Manna, Subhendu; Srinivas, V.

2014-05-01

349

Studies of heat source driven natural convection. Ph.D. Thesis. Technical Report, Jul. 1974 - Aug. 1975  

NASA Technical Reports Server (NTRS)

Natural convection energy transport in a horizontal layer of internally heated fluid was measured for Rayleigh numbers from 1890 to 2.17 x 10 to the 12th power. The fluid layer is bounded below by a rigid zero-heat-flux surface and above by a rigid constant-temperature surface. Joule heating by an alternating current passing horizontally through the layer provides the uniform volumetric energy source. The overall steady-state heat transfer coefficient at the upper surface was determined by measuring the temperature difference across the layer and power input to the fluid. The correlation between the Nusselt and Rayleigh numbers for the data of the present study and the data of the Kulacki study is given.

Kulacki, F. A.; Emara, A. A.

1975-01-01

350

Helium isotopes in Icelandic geothermal systems: II. Helium-heat relationships  

SciTech Connect

A model has been developed that relates the [sup 3]He content of the reservoir fluid to the fluid enthalpy. In contrast to oceanic hydrothermal systems that display a uniform [sup 3]He/enthalpy ratio (0.4-14 [times] 10[sup 6] atoms of [sup 3]He/joule), Icelandic systems vary by [approx] 1000 (0.4-400 [times] 10[sup 6] atoms/joule). A process that preferentially extracts helium relative to heat from a cooling magma produces high [sup 3]He/enthalpy ratios for young systems (e.g., Krafla) and low [sup 3]He/enthalpy ratios for aging magmatic systems (e.g., Hveragaerdi). Using the highest [sup 3]He/heat ratios measured in the fluid, estimates of initial gas concentrations in the basalt are made for [sup 3]He (5 [times] 10[sup [minus]10] cc/g) and carbon (1200 ppm). Low temperature wells near Geysir in southwest Iceland appear to result from mixing of high temperature fluid (>200[degree]C) and cold groundwater along a curve of constant [sup 3]He/enthalpy.

Poreda, R.J. (Univ. of Rochester, NY (United States)); Arnorsson, S. (Univ. of Iceland, Reykjavik (Iceland))

1992-12-01

351

Heat Problems.  

ERIC Educational Resources Information Center

Heat problems and heat cramps related to jogging can be caused by fluid imbalances, medications, dietary insufficiency, vomiting or diarrhea, among other factors. If the condition keeps reoccurring, the advice of a physician should be sought. Some preventive measures that can be taken include: (1) running during the cooler hours of the day; (2)…

Connors, G. Patrick

352

Heat illness.  

PubMed

A 17-year-old girl collapsed during a field hockey practice on a hot August afternoon, apparently suffering from heat illness, which is responsible for about 5,000 deaths annually. A panel of experts explores this girl's case, discusses heat illness in general, and makes recommendations about diagnosis, prevention, and treatment. PMID:2398843

Buss, D D; Kelly, J M; Reinholtz, G D; Roberts, W O; Fischer, D A

1990-08-01

353

Heat reclaimer  

SciTech Connect

A device for reclaiming heat from stove pipes and the like. A semi-circular shaped hollow enclosed housing with a highly thermal-conductive concave surface is mounted contactingly to surround approximately one-half of the circumference of the stove pipe. The concave surface is formed to contact the pipe at a maximum number of points along that surface. The hollow interior of the housing contains thin multi-surfaced projections which are integral with the concave surface and conductively transfer heat from the stove pipe and concave surface to heat the air in the housing. A fan blower is attached via an air conduit to an entrance opening in the housing. When turned on, the blower pushes the heated interior air out a plurality of air exit openings in the ends of the housing and brings in lower temperature outside air for heating.

Parham, F.

1985-04-09

354

Small-angle x-ray scattering study of phase separation in amorphous alloys during heating with use of synchrotron radiation  

NASA Astrophysics Data System (ADS)

Some recent reports suggest that amorphous Pd46Ni36P18 and Cu50Zr50 alloys phase separate during heating at temperatures 50-200 K below their crystallization temperatures. We have therefore obtained improved small-angle x-ray scattering (SAXS) measurements during heating of these alloys using a new experimental setup. The experimental improvements included in-the-beam heating using the very-high-intensity x-ray radiation available at the Synchrotron Radiation Laboratory, K.E.K., the use of Joule self-heating of the samples, which is made possible by the high resistivity of the amorphous phase and the use of regularly shaped, constant thickness amorphous tapes obtained by planar flow casting. No evidence of phase separation during heating prior to crystallization was obtained in glassy Pd46Ni36P18 and Cu50Zr50 alloys.

Yavari, A. R.; Osamura, K.; Okuda, H.; Amemia, Y.

1988-05-01

355

Heat collector  

DOEpatents

A heat collector and method suitable for efficiently and cheaply collecting solar and other thermal energy are provided. The collector employs a heat pipe in a gravity-assist mode and is not evacuated. The collector has many advantages, some of which include ease of assembly, reduced structural stresses on the heat pipe enclosure, and a low total materials cost requirement. Natural convective forces drive the collector, which after startup operates entirely passively due in part to differences in molecular weights of gaseous components within the collector.

Merrigan, M.A.

1981-06-29

356

Heat collector  

DOEpatents

A heat collector and method suitable for efficiently and cheaply collecting solar and other thermal energy are provided. The collector employs a heat pipe in a gravity-assist mode and is not evacuated. The collector has many advantages, some of which include ease of assembly, reduced structural stresses on the heat pipe enclosure, and a low total materials cost requirement. Natural convective forces drive the collector, which after startup operates entirely passively due in part to differences in molecular weights of gaseous components within the collector.

Merrigan, Michael A. (Santa Cruz, NM)

1984-01-01

357

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

358

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

359

Electrically heated liquid tank employing heat pipe heat transfer means  

Microsoft Academic Search

The heating apparatus for applying heat to the interior of a chamber includes a modular, removable, electrical, heat-producing unit and a heat pipe mountable in a wall of the chamber with one end of the pipe arranged to receive heat from the electrical heat producing unit exterior of the housing and with another end of the pipe constructed and arranged

Shutt

1978-01-01

360

Thermodynamical calculation of metal heating in nanosecond exploding wire and foil experiments  

SciTech Connect

A method of thermodynamical calculation of thin metal wire heating during its electrical explosion is discussed. The technique is based on a calculation of Joule energy deposition taking into account the current wave form and the temperature dependence of the resistivity and heat capacity of the metal. Comparing the calculation to a set of exploding tungsten wire experiments demonstrates good agreement up to the time of melting. Good agreement is also demonstrated with resistive magnetohydrodynamics simulation. A similar thermodynamical calculation for Mo, Ti, Ni, Fe, Al, and Cu shows good agreement with experimental data. The thermodynamical technique is useful for verification of the voltage measurements in exploding wire experiments. This technique also shows good agreement with an exploding W foil experiment.

Sarkisov, G. S.; Rosenthal, S. E.; Struve, K. W. [Ktech Corporation, 10800 Gibson Boulevard, Albuquerque, New Mexico 87123 (United States); Sandia National Laboratories, Albuquerque, New Mexico 87110 (United States)

2007-04-15

361

Thermodynamical calculation of metal heating in nanosecond exploding wire and foil experiments.  

PubMed

A method of thermodynamical calculation of thin metal wire heating during its electrical explosion is discussed. The technique is based on a calculation of Joule energy deposition taking into account the current wave form and the temperature dependence of the resistivity and heat capacity of the metal. Comparing the calculation to a set of exploding tungsten wire experiments demonstrates good agreement up to the time of melting. Good agreement is also demonstrated with resistive magnetohydrodynamics simulation. A similar thermodynamical calculation for Mo, Ti, Ni, Fe, Al, and Cu shows good agreement with experimental data. The thermodynamical technique is useful for verification of the voltage measurements in exploding wire experiments. This technique also shows good agreement with an exploding W foil experiment. PMID:17477658

Sarkisov, G S; Rosenthal, S E; Struve, K W

2007-04-01

362

Heating mechanisms in short-pulse laser-driven cone targets.  

PubMed

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. PMID:16486715

Mason, R J

2006-01-27

363

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

364

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

365

Coal Heating District Heating Plants.  

National Technical Information Service (NTIS)

The Elektrisitetsforsyningens Forskningsinstitutt (EFI) has considered the Norwegian district heating potential. The remaining demand is 7 TWh and parts of it may be covered by coal when local energy resources are utilized to a reasonable extent. Two plan...

J. Hustad G. Syvertsen P. Walde

1983-01-01

366

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

367

Heat Pipes  

NASA Technical Reports Server (NTRS)

Bobs Candies, Inc. produces some 24 million pounds of candy a year, much of it 'Christmas candy.' To meet Christmas demand, it must produce year-round. Thousands of cases of candy must be stored a good part of the year in two huge warehouses. The candy is very sensitive to temperature. The warehouses must be maintained at temperatures of 78-80 degrees Fahrenheit with relative humidities of 38- 42 percent. Such precise climate control of enormous buildings can be very expensive. In 1985, energy costs for the single warehouse ran to more than $57,000 for the year. NASA and the Florida Solar Energy Center (FSEC) were adapting heat pipe technology to control humidity in building environments. The heat pipes handle the jobs of precooling and reheating without using energy. The company contacted a FSEC systems engineer and from that contact eventually emerged a cooperative test project to install a heat pipe system at Bobs' warehouses, operate it for a period of time to determine accurately the cost benefits, and gather data applicable to development of future heat pipe systems. Installation was completed in mid-1987 and data collection is still in progress. In 1989, total energy cost for two warehouses, with the heat pipes complementing the air conditioning system was $28,706, and that figures out to a cost reduction.

1990-01-01

368

Temperature Control at DBS Electrodes using Heat Sink: Experimentally Validated FEM Model of DBS lead Architecture  

PubMed Central

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

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

2012-01-01

369

A propagating heat wave model of skin electroporation  

PubMed Central

The main barrier to transdermal drug delivery in human skin is the stratum corneum. Pulsed electric fields (PEFs) of sufficient amplitude can create new aqueous pathways across this barrier and enhance drug delivery through the skin. Here, we describe a model of pore formation between adjacent corneocytes that predicts the following sequence of events: (1) the PEF rapidly charges the stratum corneum near the electrode until the transepidermal potential difference is large enough to drive water into a small region of the stratum corneum, creating new aqueous pathways. (2) PEFs then drive a high current density through this newly created electropore to generate Joule heating that warms the pore perimeter. (3) This temperature rise at the perimeter increases the probability of further electroporation there as the local sphingolipids reach their phase transition temperature. (4) This heat-generated wave of further electroporation propagates outward until the surface area of the pore becomes so large that the reduced current density no longer generates sufficient heat to reach the phase transition temperature of the sphingolipids. (5) Cooling and partial recovery occurs after the field pulse. This process yields large, high permeability regions in the stratum corneum at which molecules can more readily cross this skin barrier. We present a model for this process that predicts that the initial radius of the first aqueous pathway is approximately 5 nm for a transdermal voltage of 60 V at room temperature.

Pliquett, Uwe; Gusbeth, Ch.; Nuccitelli, Richard

2011-01-01

370

A propagating heat wave model of skin electroporation.  

PubMed

The main barrier to transdermal drug delivery in human skin is the stratum corneum. Pulsed electric fields (PEFs) of sufficient amplitude can create new aqueous pathways across this barrier and enhance drug delivery through the skin. Here, we describe a model of pore formation between adjacent corneocytes that predicts the following sequence of events: (1) the PEF rapidly charges the stratum corneum near the electrode until the transepidermal potential difference is large enough to drive water into a small region of the stratum corneum, creating new aqueous pathways. (2) PEFs then drive a high current density through this newly created electropore to generate Joule heating that warms the pore perimeter. (3) This temperature rise at the perimeter increases the probability of further electroporation there as the local sphingolipids reach their phase transition temperature. (4) This heat-generated wave of further electroporation propagates outward until the surface area of the pore becomes so large that the reduced current density no longer generates sufficient heat to reach the phase transition temperature of the sphingolipids. (5) Cooling and partial recovery occurs after the field pulse. This process yields large, high permeability regions in the stratum corneum at which molecules can more readily cross this skin barrier. We present a model for this process that predicts that the initial radius of the first aqueous pathway is approximately 5nm for a transdermal voltage of 60V at room temperature. PMID:18190931

Pliquett, Uwe; Gusbeth, Ch; Nuccitelli, Richard

2008-03-21

371

Heat exchanger  

SciTech Connect

A heat exchanger having primary and secondary conduits in heat-exchanging relationship is described comprising: at least one serpentine tube having parallel sections connected by reverse bends, the serpentine tube constituting one of the conduits; a group of open-ended tubes disposed adjacent to the parallel sections, the open-ended tubes constituting the other of the conduits, and forming a continuous mass of contacting tubes extending between and surrounding the serpentine tube sections; and means securing the mass of tubes together to form a predetermined cross-section of the entirety of the mass of open-ended tubes and tube sections.

Drury, C.R.

1988-02-02

372

Joule-Thomson data curves  

NASA Technical Reports Server (NTRS)

Series of graphs shows temperature-pressure relationship for air, nitrogen, helium, oxygen, and hydrogen when flowing across line restriction over wide range of temperatures and pressures. Graphs can be applied as engineering guides for component manufacturers and piping system designers.

Beimgraben, H. W.

1976-01-01

373

Radiant heating  

Microsoft Academic Search

Compared with previous designs, this radiant heater is simpler to construct, operates better in dusty atmospheres, and has a cooler frame that allows it to be placed closer to the materials being heated. Ideal for textile or paper drying, the heater has a conduit for noncombustible gas that extends around the panel, discharging the cool gas to keep the combustion

1981-01-01

374

Flash Heating  

NASA Astrophysics Data System (ADS)

Meteorites contain millimeter-sized objects called chondrules. They were melted in the solar nebula, the cloud of gas and dust in which the Sun and planets formed. Numerous experiments on rock powders have been done to understand the melting process and the cooling rates chondrules experienced. Most meteorite specialists believe that chondrules formed by flash heating, with almost instantaneous melting, though the length of time they remained molten is uncertain. Can conventional laboratory furnaces heat rock powders rapidly enough to flash melt them? Susan Maharaj and Roger Hewins (Rutgers University, New Brunswick) tested this idea by inserting tiny wires of pure elements (which have precise melting temperatures) into compressed rock powders about 3.5 mm in diameter, and placing the samples into a furnace heated to a range of temperatures. They found that at 1600 C, a sample took only six seconds to reach 1538 C. When placed into a furnace at 1500 C, samples took ten seconds to reach 1495 C. This shows that the flash heating process can be studied in conventional laboratory furnaces.

Taylor, G. J.

2000-03-01

375

Cooling and heating system utilizing solar heat  

SciTech Connect

A cooling and heating system utilizing solar heat comprises a heat collector for heating a circulating heat medium with solar heat, an absorption refrigerator operable with the heat medium heated by the heat collector and serving as a generating heat source to provide a chilled medium, and an air-conditioning unit for circulating the chilled medium or the heated medium alternatively therethrough to cool or heat the space to be airconditioned. The system further comprises a bypass line provided with an auxiliary refrigerator of the dual-effect type and connected to an intermediate portion of a line extending from the absorption refrigerator to the air-conditioning unit for supplying chilled medium or the heated medium to the unit. Change -over means is provided for passing the chilled medium or the heated medium through the bypass line.

Katayama, K.; Yukimachi, K.

1981-05-26

376

Waste Heat Recovery from High Temperature Off-Gases from Electric Arc Furnace  

SciTech Connect

This article presents a study and review of available waste heat in high temperature Electric Arc Furnace (EAF) off gases and heat recovery techniques/methods from these gases. It gives details of the quality and quantity of the sensible and chemical waste heat in typical EAF off gases, energy savings potential by recovering part of this heat, a comprehensive review of currently used waste heat recovery methods and potential for use of advanced designs to achieve a much higher level of heat recovery including scrap preheating, steam production and electric power generation. Based on our preliminary analysis, currently, for all electric arc furnaces used in the US steel industry, the energy savings potential is equivalent to approximately 31 trillion Btu per year or 32.7 peta Joules per year (approximately $182 million US dollars/year). This article describes the EAF off-gas enthalpy model developed at Oak Ridge National Laboratory (ORNL) to calculate available and recoverable heat energy for a given stream of exhaust gases coming out of one or multiple EAF furnaces. This Excel based model calculates sensible and chemical enthalpy of the EAF off-gases during tap to tap time accounting for variation in quantity and quality of off gases. The model can be used to estimate energy saved through scrap preheating and other possible uses such as steam generation and electric power generation using off gas waste heat. This article includes a review of the historical development of existing waste heat recovery methods, their operations, and advantages/limitations of these methods. This paper also describes a program to develop and test advanced concepts for scrap preheating, steam production and electricity generation through use of waste heat recovery from the chemical and sensible heat contained in the EAF off gases with addition of minimum amount of dilution or cooling air upstream of pollution control equipment such as bag houses.

Nimbalkar, Sachin U [ORNL] [ORNL; Thekdi, Arvind [E3M Inc] [E3M Inc; Keiser, James R [ORNL] [ORNL; Storey, John Morse [ORNL] [ORNL

2014-01-01

377

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

378

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

379

Heat Transfer  

NSDL National Science Digital Library

In this inquiry activity students explore how heat transfers from one substance to another This inquiry activity was developed by a K-12 science teacher in the American Physiological SocietyÃÂs 2006 Frontiers in Physiology Program. The NSES Standards addressed by this activity are current as of the year of development. For more information on the Frontiers in Physiology Program, please visit www.frontiersinphys.org.

Ms. Leslie Van (Montgomery Blair High School)

2006-04-01

380

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

381

Infrared radiant heating  

Microsoft Academic Search

Retrofitting convective forced air heating systems with infrared (IR) systems can save as much as 50 percent of the total heating bill. Infrared heating is more efficient for two reasons: it can be directed to heat only occupied space; and it does not heat the air in a space, it only heats people and objects. Infrared heating works best where

S. Cannon; M. Rocha

1996-01-01

382

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

PubMed Central

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

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

2013-01-01

383

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

384

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

385

Heat-Transfer Coupling For Heat Pipes  

NASA Technical Reports Server (NTRS)

Proposed welded heat-transfer coupling joins set of heat pipes to thermoelectric converter. Design avoids difficult brazing operation. Includes pair of mating flanged cups. Upper cup integral part of housing of thermoelectric converter, while lower cup integral part of plate supporting filled heat pipes. Heat pipes prefilled. Heat of welding applied around periphery of coupling, far enough from heat pipes so it would not degrade working fluid or create excessive vapor pressure in the pipes.

Nesmith, Bill J.

1991-01-01

386

Hydride heat pump with heat regenerator  

NASA Technical Reports Server (NTRS)

A regenerative hydride heat pump process and system is provided which can regenerate a high percentage of the sensible heat of the system. A series of at least four canisters containing a lower temperature performing hydride and a series of at least four canisters containing a higher temperature performing hydride is provided. Each canister contains a heat conductive passageway through which a heat transfer fluid is circulated so that sensible heat is regenerated. The process and system are useful for air conditioning rooms, providing room heat in the winter or for hot water heating throughout the year, and, in general, for pumping heat from a lower temperature to a higher temperature.

Jones, Jack A. (Inventor)

1991-01-01

387

Ion-neutral coupling in the high-latitude F region Evaluation of ion heating terms from Dynamics Explorer 2  

NASA Technical Reports Server (NTRS)

Ion and neutral motions in the high latitude F layer were studied simultaneously during six passes of the Dynamics Explorer 2 spacecraft. The passes were made over the south polar cap in October 1981. An ion energy balance equation was defined to express the exchange of energy between the F layer and other atmospheric constituents. A momentum equation expressed the momentum exchange between the species. An approximate form of the energy balance equation was also formulated. The time constant for ion-neutral collisional momentum transfer significantly affected Joule heating in the F layer. Regions of large velocity disparities and ion temperature enhancements were detected as hot spots. The results indicate that a feedback mechanism may arise in terms of neutral compositional changes and enhanced ionospheric recombination. The approximate equation furnished values for ion heating rates which matched the data.

Killeen, T. L.; Hays, P. B.; Carignan, G. R.; Heelis, R. A.; Hanson, W. B.; Spencer, N. W.; Brace, L. H.

1984-01-01

388

Transient Heat Transport in Subcooled He II Associated with JT Effect  

SciTech Connect

Transient heat transport in subcooled He II has been investigated in a 1 m long rectangular channel with distributed contractions: one-closed end has a heater, while the other end is open to the He II bath. Experiments were conducted applying heat pulses and recording the temperature profile with seven Allan Bradley resistors placed along the channel. Cernox sensor was indium soldered on the heater surface to monitor the onset of film boiling. As the onset of heat pulse, the pressure at the heater surface increased because of phase change from subcooled He II to He I. Further increasing of heat pulse leads to coexistence of triple-phase, He I vapor layer, He I and subcooled He II, at the vicinity of heater surface. These effects induced instantaneous He II temperature drop along the channel, which is caused by Joule-Thomson (JT) effect. A simple model gives an approximate mechanism of pressure increase in the channel. The paper describes transient heat transport mechanism in the channel and discusses JT effect within the channel.

Maekawa, R.; Iwamoto, A.; Hamaguchi, S. [National Institute for Fusion Science, Toki, Gifu 509-5292 (Japan)

2004-06-23

389

Heat production in the windings of the stators of electric machines under stationary condition  

NASA Astrophysics Data System (ADS)

In electric machines due to high currents and resistive losses (joule heating) heat is produced. To avoid damages by overheating the design of effective cooling systems is required. Therefore the knowledge of heat sources and heat transfer processes is necessary. The purpose of this paper is to illustrate a good and effective calculation method for the temperature analysis based on homogenization techniques. These methods have been applied for the stator windings in a slot of an electric machine consisting of copper wires and resin. The key quantity here is an effective thermal conductivity, which characterizes the heterogeneous wire resin-arrangement inside the stator slot. To illustrate the applicability of the method, the analysis of a simplified, homogenized model is compared with the detailed analysis of temperature behavior inside a slot of an electric machine according to the heat generation. We considered here only the stationary situation. The achieved numerical results are accurate and show that the applied homogenization technique works in practice. Finally the results of simulations for the two cases, the original model of the slot and the homogenized model chosen for the slot (unit cell), are compared to experimental results.

Alebouyeh Samami, Behzad; Pieper, Martin; Breitbach, Gerd; Hodapp, Josef

2014-05-01

390

Transient Heat Transport in Subcooled He II Associated with JT Effect  

NASA Astrophysics Data System (ADS)

Transient heat transport in subcooled He II has been investigated in a 1 m long rectangular channel with distributed contractions: one-closed end has a heater, while the other end is open to the He II bath. Experiments were conducted applying heat pulses and recording the temperature profile with seven Allan Bradley resistors placed along the channel. Cernox sensor was indium soldered on the heater surface to monitor the onset of film boiling. As the onset of heat pulse, the pressure at the heater surface increased because of phase change from subcooled He II to He I. Further increasing of heat pulse leads to coexistence of triple-phase, He I vapor layer, He I and subcooled He II, at the vicinity of heater surface. These effects induced instantaneous He II temperature drop along the channel, which is caused by Joule-Thomson (JT) effect. A simple model gives an approximate mechanism of pressure increase in the channel. The paper describes transient heat transport mechanism in the channel and discusses JT effect within the channel.

Maekawa, R.; Iwamoto, A.; Hamaguchi, S.

2004-06-01

391

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

392

Direct electric field heating and acceleration of electrons in solar flares  

NASA Technical Reports Server (NTRS)

We show that the observed properties of solar flare X-ray and microwave emission can be explained through the Joule heating and electric field acceleration of runaway electrons in current channels. The global properties of the flaring region required for this are presented. We have fit a hybrid thermal/nonthermal electron distribution, consisting of hot, isothermal electrons with a nonthermal tail of runaway electrons, to high-resolution hard X-ray and microwave spectra and have obtained excellent fits to both. The hybrid model relaxes the electron number and energy flux requirements for the hard X-ray emission over those of a purely nonthermal model. The model also provides explanations for several previously unexplained aspects of the high-resolution microwave spectra. The fit parameters can be related to physical properties (such as the electric field strength in the current channels) of the acceleration region.

Holman, Gordon D.; Benka, Stephen G.

1992-01-01

393

Segmented heat exchanger  

DOEpatents

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

394

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

395

Geothermal heat pumps for heating and cooling  

NASA Astrophysics Data System (ADS)

Naval Facilities Engineering Service Center (NFESC) has been tasked by Naval Shore Facilities Energy Office to evaluate the NAS Patuxent River ground-source heat pump (GHP) installation. A large part of a building's energy consumption consists of heating and air conditioning for occupant comfort. The space heating requirements are normally met by fossil-fuel-fired equipment or electric resistance heating. Cooling is provided by either air conditioners or heat pumps, both using electricity as an energy source.

Garg, Suresh C.

1994-03-01

396

Ceramics in heat exchangers  

Microsoft Academic Search

This book presents the papers given at a conference on the testing of ceramics for heat exchangers. Topics considered at the conference included advanced heat-transfer systems, heat recovery equipment, air-to-air heat exchangers, fluidized bed heat-recovery boilers, industrial heat recovery, potential materials, materials development and evaluation, chemical vapor deposition, product testing, fracture properties, and the durability of silicon carbide heat-exchanger tubes

B. D. Foster; J. B. Patton

1984-01-01

397

High heat flux single phase heat exchanger  

NASA Technical Reports Server (NTRS)

This paper presents the results obtained to date in a program to develop a high heat flux, single-phase heat exchanger for spacecraft thermal management. The intended application is a net generation interface heat exchanger to couple the crew module water thermal bus to the two-phase ammonia main thermal bus in the Space Station Freedom. The large size of the interface heat exchanger is dictated by the relatively poor water-side heat transfer characteristics. The objective of this program is to develop a single-phase heat transfer approach which can achieve heat fluxes and heat transfer coefficients comparable to those of the evaporation ammonia side. A new heat exchanger concept has been developed to meet these objecties. The main feature of this heat exchanger is that it can achieve very high heat fluxes with a pressure drop one to two orders of magnitude lower than those of previous microchannel or jet impingement high heat flux heat exchangers. This paper describes proof-of-concept experiments performed in air and water and presents analytical model of the heat exchanger.

Valenzuela, Javier A.; Izenson, Michael G.

1990-01-01

398

Heating Up  

NSDL National Science Digital Library

This interactive, online activity introduces the idea that everything emits electromagnetic radiation, including students. Students discover how the light emitted from an object (a robot) changes as the object is heated. A graph shows the amount of light the robot emits in each wavelength region as the robot reaches higher temperatures. Students are challenged to relate the peak of the emitted light from the robot to the color it appears, thus connecting the temperature of an object with the color of light it emits. Students apply this information by plotting the peak wavelengths of four stars of their choice, and then determine the temperature of each. Upon completion of this activity, students will have identified peak wavelengths from graphical data and applied this concept to determine the relationship between temperature and star color. Students may complete this activity independently or in small groups. Detailed teacher pages, identified as Teaching Tips on the title page of the activity, provide science background information, lesson plan ideas, related resources, and alignment with national education standards. This activity is part of the online exploration "Star Light, Star Bright" that focuses on the electromagnetic spectrum and that is available on the Amazing Space website.

399

Implications of a heuristic model of auroral Farley Buneman waves and heating  

NASA Astrophysics Data System (ADS)

The global implications, particularly with respect to altitude dependence, of the heuristic model of Farley Buneman waves put forward initially by Milikh and Dimant (2002) are studied. This model prescribes a relationship between the background convection electric field that excites the waves and the transverse electric fields of the waves that grow in response. It also prescribes the magnetic aspect angle of the waves, which is related to their ability to heat the auroral E region. The prescription is based on the condition of marginal stability. We reformulate the basic model, which is local, and embed it in the SAMI2 ionospheric model, which includes wave and Joule heating, heat transport, cooling, temperature-dependent collisions, and related chemistry. Within the limits of its underlying assumptions, the combined model can be used to predict the phase-speeds and magnetic-aspect widths of Farley Buneman waves in the auroral zone and the heating they can cause, all as functions of altitude. Model predictions are compared with experimental results, and the efficacy of the model assessed. This modeling exercise highlights the importance of the thickness of the layer in which Farley Buneman waves exist, the strong variations in wave characteristics across the layer, and the consequences this has for coherent scatter radar measurements of the phenomenon.

Hysell, D. L.; Miceli, R. J.; Huba, J. D.

2013-09-01

400

Acceleration of solar wind in polar coronal holes by induction heating  

NASA Technical Reports Server (NTRS)

The universal induction heating mechanism supplying with the energy all the processes of coronal heating and the solar wind acceleration is developed. The observed relative 'trembling' of photospheric super-large scale magnetic fields with quasi-periods of 1-4 days amounts 30-40 percent in amplitude. The inductive electric field appears in the corona. The electric currents cause the Joule dissipation. The uneven heating leads to the solar wind acceleration. A model is suggested in which high-speed streams in space are caused by the combination of the enhanced inductive energy flux from the solar coronal active regions; the work against the regular magnetic field; losses from coronal emission. The consideration is made in terms of the dissipative solar wind theory with the finite electrical conductivity of plasma. The leakage of plasma and the energy flux across the magnetic field, caused by the induction heating processes, are taken into account. The polar coronal holes (and the mid-latitude ones) are indicators of energy transfer balance but not direct sources of high-speed streams in the solar wind.

Chertkov, A. D.; Shkrebets, A. E.; Arkhipov, Yu. V.; Soldatov, V. A.

1995-01-01

401

Natural convection heat transfer on surfaces of copper micro-wires  

NASA Astrophysics Data System (ADS)

The natural convection heat transfer characteristics and mechanism for copper micro-wires in water and air were investigated experimentally and numerically. The wires with diameters of 39.9, 65.8 and 119.1 ?m were placed horizontally in water inside of a sealed tube and in air of a large room, respectively. Using Joule heating, the heat transfer coefficients and Nusselt numbers of natural convection for micro-wires in ultra pure water and air were obtained. A three dimensional incompressible numerical model was used to investigate the natural convection, and the prediction with this model was in reasonable accordance with the experimental results. With the decrease of micro-wire diameter, the heat transfer coefficient of natural convection on the surface of micro-wire becomes larger, while the Nu number of natural convection decreases in water and air. Besides, the change rate of Nu number in water decreases apparently with the increase of heat flux and the decrease of wire diameter, which is larger than that in air. The thickness of boundary layer on the wall of micro-wire becomes thinner with the decrease of diameter in both water and air, but the ratio of boundary layer thickness in water to the diameter increases. However, there is almost no change of this ratio for natural convection in air. As a result, the proportion of conduction in total heat transfer of natural convection in water increases, while the convective heat transfer decreases. The velocity distribution, temperature field and the boundary layer in the natural convection were compared with those of tube with conventional dimension. It was found that the boundary layer around the micro-wire is an oval-shaped film on the surface, which was different from that around the conventional tube. This apparently reduces the convection strength in the natural convection, thus the heat transfer presents a conduction characteristic.

Guan, Ning; Liu, Zhigang; Zhang, Chengwu; Jiang, Guilin

2014-02-01

402

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

403

Solar heating system  

SciTech Connect

A solar heating system comprises a heat accumulating structure for heating both air and water in which both the heated air and water are directed to an object to be heated such as a commercial building or private residence. The heat accumulating structure is below ground and includes a magnifying glass forming the roof thereof and protruding above ground, the magnifying glass concentrating the rays of the sun into the heat accumulating structure which includes a lower portion containing water and an air space thereabove. The solar heating system includes a piping arrangement whereby heated water can be directed to the object to be heated and piped away. Likewise a heat trunk line and return air line is included for utilizing the heated air formed in the air space of the heat accumulating structure.

Hall, R.L.

1982-03-16

404

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

405

Mantle heat flow  

Microsoft Academic Search

A map of the heat flux out of the earth's mantle has been prepared by subtracting the heat flow arising in the earth's crust from the surface heat flow. In continental areas the crustal contribution of the enriched zone is determined from the parameters of the linear heat flow-heat production relationship q0 = q* + bA0 in areas where such

Henry N. Pollack; David S. Chapman

1977-01-01

406

Heat pipe technology  

NASA Technical Reports Server (NTRS)

A bibliography of heat pipe technology to provide a summary of research projects conducted on heat pipes is presented. The subjects duscussed are: (1) heat pipe applications, (2) heat pipe theory, (3) design and fabrication, (4) testing and operation, (5) subject and author index, and (6) heat pipe related patents.

1972-01-01

407

Heat pump defrosting operation  

Microsoft Academic Search

This patent describes improvements to the method of defrosting operation of a heat pump having a compressor, an interior heat exchanger, an exterior heat exchanger, an exterior fan for moving exterior air past the exterior heat exchanger, and a thermostatic control means for cycling the compressor on and off in accordance with heating demand. The improvement comprises: operating the exterior

M. Levine; J. Russo; V. Rigotti; N. Skogler

1990-01-01

408

Heat pump defrosting operation  

Microsoft Academic Search

This patent describes an improvement to the method of defrosting operation of a heat pump having a compressor, an interior heat exchanger, an exterior heat exchanger, an exterior fan for moving exterior air past the exterior heat enchanger, and a thermostatic control means for cycling the compressor on and off in accordance with heating demand. The improvement comprises: measuring at

M. Levine; J. Russo; V. Rigotti; N. Skogler

1990-01-01

409

Waste heat recovery device  

Microsoft Academic Search

A cascade heat exchange system is described in which the heat given off in condensing a superheated vaporized refrigerant is used to vaporize carbon dioxide and to add sensible heat to a water system. The superheated discharge vapor of a refrigeration system is pumped into the shell side of a heat exchange vessel, where evaporative tube bundles absorb heat from

Barrow

1980-01-01

410

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

411

Critical heat flux around strongly heated nanoparticles.  

PubMed

We study heat transfer from a heated nanoparticle into surrounding fluid using molecular dynamics simulations. We show that the fluid next to the nanoparticle can be heated well above its boiling point without a phase change. Under increasing nanoparticle temperature, the heat flux saturates, which is in sharp contrast with the case of flat interfaces, where a critical heat flux is observed followed by development of a vapor layer and heat flux drop. These differences in heat transfer are explained by the curvature-induced pressure close to the nanoparticle, which inhibits boiling. When the nanoparticle temperature is much larger than the critical fluid temperature, a very large temperature gradient develops, resulting in close to ambient temperature just a radius away from the particle surface. The behavior reported allows us to interpret recent experiments where nanoparticles can be heated up to the melting point, without observing boiling of the surrounding liquid. PMID:19391744

Merabia, Samy; Keblinski, Pawel; Joly, Laurent; Lewis, Laurent J; Barrat, Jean-Louis

2009-02-01

412

Heat flow through extended surface heat exchangers  

SciTech Connect

Contents of this book include the one-dimensional analysis of fin assembly heat transfer, the two dimensional analysis of fin assembly heat transfer, the analysis of fin radiation and the applicability of the perfect contact assumption.

Manzoor, M.

1984-01-01

413

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

414

A Study of Alfven Wave Propagation and Heating the Chromosphere  

NASA Astrophysics Data System (ADS)

Alfven wave propagation, reflection and heating of the solar atmosphere are studied for a one-dimensional solar atmosphere by self-consistently solving plasma and neutral fluid equations and Maxwell's equations with incorporation of the Hall effect, strong electron-neutral, electron-ion, and ion-neutral collisions. The governing equations are very stiff because of the strong coupling between the charged and neutral fluids. We have developed a numerical model based on an implicit backward difference formula (BDF2) of second order accuracy both in time and space to overcome the stiffness. A non-reflecting boundary condition is applied to the top boundary of the simulation domain so that the wave reflection within the domain due to the density gradient can be unambiguously determined. It is shown that the Alfven waves are partially reflected throughout the chromosphere. The reflection is increasingly stronger at higher altitudes and the strongest reflection occurs at the transition region. The waves are damped in the lower chromosphere dominantly through Joule dissipation due to electron collisions with neutrals and ions. The heating resulting from the wave damping is strong enough to balance the radiation energy loss for the quiet chromosphere. The collisional dissipation of the Alfven waves in the weakly collisional corona is negligible. The heating rates are larger for weaker background magnetic fields. In addition, higher frequency waves are 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 waves may be strongly reflected at the transition region. The reflected waves interacting with the upward propagating waves may produce power at their double frequencies, which leads to more damping. Due to the reflection and damping, the energy flux of the waves transmitted to the corona is one order of magnitude smaller than that of the driving source.

Tu, J.; Song, P.

2013-12-01

415

Heat transport and solidification in the electromagnetic casting of aluminum alloys: Part II. Development of a mathematical model and comparison with experimental results  

NASA Astrophysics Data System (ADS)

In this second article of a two-part series, a mathematical model for heat transport and solidification of aluminum in electromagnetic casting is developed. The model is a three-dimensional one but involves a simplified treatment of convective heat transport in the liquid metal pool. Heat conduction in the solid was thought to play a dominant role in heat transport, and the thermal properties of the two alloys used in measurements reported in Part I (AA 5182 and 3104) were measured independently for input to the model. Heat transfer into the water sprays impacting the sides of the ingot was approximated using a heat-transfer coefficient from direct chill casting; because this heat-transfer step appears not to be rate determining for solidification and cooling of most of the ingot, there is little inaccuracy involved in this approximation. Joule heating was incorporated into some of the computations, which were carried out using the finite element software FIDAP. There was good agreement between the computed results and extensive thermocouple measurements (reported in Part I) made on a pilot-scale caster at Reynolds Metals Company (Richmond, VA).

Prasso, D. C.; Evans, J. W.; Wilson, I. J.

1995-02-01

416

CONJUGATE HEAT TRANSFER IN PLATE HEAT EXCHANGERS  

Microsoft Academic Search

In a real plate heat exchanger (PHX), heat transfer from the hot to the cold fluid is a conjugate problem, in which longitudinal heat conduction (LHC) along the walls plays some role. Large-scale LHC is always detrimental to the exchanger's effectiveness. On the contrary, if significant non-uniformities exist in the distribution of either convective heat transfer coefficient, small-scale LHC may

Michele Ciofalo

2004-01-01

417

Enhancement of heat transfer in waste-heat heat exchangers  

SciTech Connect

The Fluidfire shallow fluidized bed heat transfer facility was modified during this program to give increased air flow capacity and to allow testing with different distributor plates and with two-stage heat exchangers. Tests were conducted using this heat transfer facility to investigate the effect of reduced distributor plate pressure loss and amount and type of bed material on the heat transfer performance of a single-stage fluidized bed heat exchanger. Elutriation from the bed was measured for different bed materials and distributor plates; alternate heat exchanger surfaces having different fin spacings were also tested. Two types of two-stage fluidized bed heat exchangers were tested: one having a baffle (having almost no pressure loss) located between the stages and which allowed bed material to recirculate between upper and lower beds; the second having two distributor plates in series with no recirculation of the bed material. The results obtained in the experimental program were used in conceptual design studies of multi-stage fluidized bed heat exchangers for waste heat recovery from diesel engine exhaust gases. Information was obtained from the literature and from diesel engine manufacturers to determine allowable diesel engine operating back pressures. The costs were estimated for two- and three-stage designs and were compared with costs obtained previously for single-stage fluidized bed and conventional heat exchanger designs.

Not Available

1980-07-01

418

Heat Island Effect  

MedlinePLUS

... to learn more. More Information on Urban Heat Islands Heat Island Basics Chapter from EPA’s Reducing Urban ... Island Video Segments What Is an Urban Heat Island? As urban areas develop, changes occur in their ...

419

Interconnecting District Heating Networks.  

National Technical Information Service (NTIS)

The National Energy Administration has, on behalf of the Swedish Government, investigated the potential for interconnecting district heating networks in Sweden. The purpose is twofold: by creating a large heat load, cheap energy sources like waste heat ca...

1985-01-01

420

Regenerative adsorbent heat pump  

NASA Technical Reports Server (NTRS)

A regenerative adsorbent heat pump process and system is provided which can regenerate a high percentage of the sensible heat of the system and at least a portion of the heat of adsorption. A series of at least four compressors containing an adsorbent is provided. A large amount of heat is transferred from compressor to compressor so that heat is regenerated. The process and system are useful for air conditioning rooms, providing room heat in the winter or for hot water heating throughout the year, and, in general, for pumping heat from a lower temperature to a higher temperature.

Jones, Jack A. (Inventor)

1991-01-01

421

Rotary magnetic heat pump  

SciTech Connect

Magnetic heat pumps use the magneto-caloric effect to produce entropy changes necessary for heat pumping. A rotary magnetic heat pump has been analyzed and computer models have been developed. The contribution of viscous heat to the regenerator heat balance has been found to significantly restrict performance. The contribution of viscous heating is at least as important as the temperature differences required for regenerator heat transfer. Multiple magnet coils on a single rotor reduce the viscous work per field change cycle and result in greatly improved performance. Operation at 80% of Carnot efficiency with a heat pumping rate of 10 kW per kilogram of magnetic material is predicted.

Kirol, L.D.; Mills, J.I.

1984-01-01

422

Active heat pipe solar water heating system  

SciTech Connect

An ''active heat pipe'' solar water heating system is described. In its primary mode it transfers solar radiation energy from a high temperature solar evaporator to a low temperature water storage tank. For this mode to work properly, refrigerant must be circulated by a variable speed pump/compressor. It is expected that this system will offer better efficiency than conventional solar water systems and heat pump water heaters. This paper summarizes the benefits of active refrigeration cycle control and presents some simulation results comparing active heat pipe solar water heating systems to conventional systems.

Yoshino, H.; Kasayi, H.; Otsuka, N.; Thompson, P.

1983-08-01

423

Surface heating greenhouses with waste heat  

SciTech Connect

Surface heating of greenhouses is described as being accomplished by applying waste heated water on the outside of the greenhouse at the ridge and allowing this water to flow in a thin layer over the roof and sidewall surfaces. The water is then collected in gutters and returned to its source. The main advantages of this heating system over others for heating greenhouses with waste heat are its low capital costs and the fact that it can utilize wastes at quite low temperatures. 3 refs.

Walker, P.N.; Rand, H.J.

1980-01-01

424

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

425

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

426

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

427

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

428

Hot water heating system  

Microsoft Academic Search

A solar hot water heating system has a primary tank heated by solar energy utilizing a heat transfer medium circulated between a solar collector and a heat exchanger located in the primary tank. Usually a back-up tank is provided to supplement the solar system. The primary tank receives cold water from a pressurized source. Its hot water outlet is connected

1984-01-01

429

Infrared Radiant Heating.  

National Technical Information Service (NTIS)

Retrofitting convective forced air heating systems with infrared (IR) systems can save as much as 50 percent of the total heating bill. Infrared heating is more efficient for two reasons: it can be directed to heat only occupied space; and it does not hea...

S. Cannon M. Rocha

1996-01-01

430

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

431

Engineering heat transfer  

Microsoft Academic Search

The basic concepts of heat transfer are set forth, and the fundamentals of numerical analysis appropriate to solving heat transfer problems are covered. In some example problems, numerical solutions, flow charts, example FORTRAN programs, and computer output are given. Conduction, convection, thermal radiation, and combined mechanisms of heat transfer are investigated. A chapter on heat transfer equipment is given, and

J. R. Welty

1974-01-01

432

STELLAR MAGNETIC FIELDS AS A HEATING SOURCE FOR EXTRASOLAR GIANT PLANETS  

SciTech Connect

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 R{sub J} 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., E-mail: dbuzasi@fgcu.edu [College of Arts and Sciences, Florida Gulf Coast University, Fort Myers, FL 33965 (United States)

2013-03-10

433

Characterizing Heat Spreading and Performance Degradation in Organic Light-Emitting Diodes  

NASA Astrophysics Data System (ADS)

In this work, we present for the first time high resolution thermal images of operating organic light-emitting diodes (OLEDs) and show that the surface temperature of these devices can be used to map current density and identify the origin of localized defects and performance degradation. Both luminance and lifetime of OLEDs decrease dramatically with increased operating temperature due to self-heating. Furthermore, localized Joule heating at defects results in local hot spots, thus degrading the brightness homogeneity, altering the electro-optical characteristics of the OLED, and leading to electrode delamination and black spots. Increasing the lifetime of OLEDs clearly relies at least in part on improved thermal management. Using thermoreflectance microscopy, we observed evidence of the correlation between structural defects and areas of low current density by examining areas of operating devices which showed visual damage and had a low relative surface temperature. We also show the validity of using thermoreflectance microscopy to perform basic characterization of operating OLEDs, such as examining diode behavior, extrapolating material qualities such as diffusivity and conductivity, and quantifying the heat flow through working devices.

Plunk, Amelia; Davis, Andrew; Al-Hemyari, Kadhair; Arango, Alexi; Carter, Kenneth; Hudgings, Janice

2012-02-01

434

Characteristics of the heat resistant FBG sensor under laser cladding condition  

NASA Astrophysics Data System (ADS)

We have developed heat resistant strain sensors using laser processing techniques. The application is aimed at structural health monitoring for high temperature piping systems. This situation requires extraordinary durability such as radiation resistance and noise isolation due to adverse conditions caused by nuclear reactions or electro-magnetic pulses. We proposed that a Fiber Bragg Grating (FBG) sensor made by femtosecond laser processing could be the best candidate. The combination of fabric reinforcement and a heatproof adhesive mold successfully protected the fragile optical fiber once the fiber was installed on the piping material's surface. To make the best use of the heat-resistant characteristic, we fixed the FBG sensor by metal mold. A groove was processed onto the surface of a SUS metal plate with a grindstone. We used a Quasi-CW laser to weld a filler wire onto the plate. The optical fiber was situated under the filler wire before was heated by laser pulses with 10 joule energy and a duration of 10 ms. A series of weld pool formed a sealing clad on the groove. The FBG sensor was buried at a depth of 1 mm over a length of 1 cm. No degradation in its reflection spectra was detected before and after the processing. The FBG sensor can detect the vibration of the plate caused by impact shocks. In this paper, the Bragg peak shift of the FBG sensor under laser cladding condition has been discussed.

Nishimura, A.; Terada, T.

2014-02-01

435

Conditions for Aeronomic Applicability of the Classical Electron Heat Conduction Formula  

NASA Technical Reports Server (NTRS)

Conditions for the applicability of the classical formula for heat conduction in the electrons in ionized gas are investigated. In a fully ionised gas ( V(sub en) much greater than V(sub ei)), when the mean free path for electron-electron (or electron-ion) collisions is much larger than the characteristic thermal scale length of the observed system, the conditions for applicability break down. In the case of the Venus ionosphere this breakdown is indicated for a large fraction of the electron temperature data from altitudes greater than 180 km, for electron densities less than 10(exp 4)/cc cm. In a partially ionised gas such that V(sub en) much greater than V(sub ei) there is breakdown of the formula not only when the mean free path of electrons greatly exceeds the thermal scale length, but also when the gradient of neutral particle density exceeds the electron thermal gradient. It is shown that electron heat conduction may be neglected in estimating the temperature of joule heated electrons by observed strong 100 Hz electric fields when the conduction flux is limited by the saturation flux. The results of this paper support our earlier aeronomical arguments against the hypothesis of planetary scale whistlers for the 100 Hz electric field signal. In turn this means that data from the 100 Hz signal may not be used to support the case for lightning on Venus.

Cole, K. D.; Hoegy, W. R.

1998-01-01

436

Thulium-170 heat source  

DOEpatents

An isotopic heat source is formed using stacks of thin individual layers of a refractory isotopic fuel, preferably thulium oxide, alternating with layers of a low atomic weight diluent, preferably graphite. The graphite serves several functions: to act as a moderator during neutron irradiation, to minimize bremsstrahlung radiation, and to facilitate heat transfer. The fuel stacks are inserted into a heat block, which is encased in a sealed, insulated and shielded structural container. Heat pipes are inserted in the heat block and contain a working fluid. The heat pipe working fluid transfers heat from the heat block to a heat exchanger for power conversion. Single phase gas pressure controls the flow of the working fluid for maximum heat exchange and to provide passive cooling.

Walter, Carl E. (Pleasanton, CA); Van Konynenburg, Richard (Livermore, CA); VanSant, James H. (Tracy, CA)

1992-01-01

437

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

438

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

439

Heat cascading regenerative sorption heat pump  

NASA Technical Reports Server (NTRS)

A simple heat cascading regenerative sorption heat pump process with rejected or waste heat from a higher temperature chemisorption circuit (HTCC) powering a lower temperature physisorption circuit (LTPC) which provides a 30% total improvement over simple regenerative physisorption compression heat pumps when ammonia is both the chemisorbate and physisorbate, and a total improvement of 50% or more for LTPC having two pressure stages. The HTCC contains ammonia and a chemisorbent therefor contained in a plurality of canisters, a condenser-evaporator-radiator system, and a heater, operatively connected together. The LTPC contains ammonia and a physisorbent therefor contained in a plurality of compressors, a condenser-evaporator-radiator system, operatively connected together. A closed heat transfer circuit (CHTC) is provided which contains a flowing heat transfer liquid (FHTL) in thermal communication with each canister and each compressor for cascading heat from the HTCC to the LTPC. Heat is regenerated within the LTPC by transferring heat from one compressor to another. In one embodiment the regeneration is performed by another CHTC containing another FHTL in thermal communication with each compressor. In another embodiment the HTCC powers a lower temperature ammonia water absorption circuit (LTAWAC) which contains a generator-absorber system containing the absorbent, and a condenser-evaporator-radiator system, operatively connected together. The absorbent is water or an absorbent aqueous solution. A CHTC is provided which contains a FHTL in thermal communication with the generator for cascading heat from the HTCC to the LTAWAC. Heat is regenerated within the LTAWAC by transferring heat from the generator to the absorber. The chemical composition of the chemisorbent is different than the chemical composition of the physisorbent, and the absorbent. The chemical composition of the FHTL is different than the chemisorbent, the physisorbent, the absorbent, and ammonia.

Jones, Jack A. (Inventor)

1995-01-01

440

Evaluation of potential nonisothermal processes and heat transport during CO2 sequestration  

NASA Astrophysics Data System (ADS)

Injection of CO2 may perturb subsurface temperatures, leading to a dynamic temperature system in the storage formation and adjacent seal strata. In most cases, the individual effects from wellbore dynamics, solvation reactions, and phase changes are incremental, but collectively these relevant processes may cause significant temperature changes compared to ambient conditions. In this work, we evaluated several potential nonisothermal effects resulting from CO2 injection activity. These include the Joule-Thomson (heating and cooling) effect, exothermic CO2 dissolution, and heat changes associated with concomitant water vaporization. Results suggest that three effects: a) the adiabatic (de-) compression of CO2, b) the frictional energy losses, and c) conductive heat exchange between the injected CO2 and surrounding fluid/rock, govern the resulting CO2 thermal profiles within an injection well. In addition, as supercritical-phase CO2 comes into contact with formation brine, the CO2 will dissolve into the aqueous phase, and such dissolution is exothermic at typical conditions for CO2 sequestration. However, we still seek a better understanding of heat effects associated with water vaporization into the supercritical-phase CO2. Finally, sensitivity studies, simulating supercritical-phase CO2 injection into a 1-D radially symmetric domain, are conducted to evaluate the magnitude of different heat disequilibrium potentials and spatial location in the CO2 plume affected by thermal processes. In addition, time-scales associated with migration rates of temperature fronts, pressure pulses, and dissolved- and supercritical-phase CO2 profiles are investigated with a function of heat capacities of rock, different effective thermal conductivities, permeabilities, and porosities. Our results demonstrate that adiabatic CO2 compression occurring in injection wells could have the most significant impact on the temperature change whilst the exothermic CO2 dissolution occurred at the largest spatial domain.

Han, Weon Shik; Stillman, Greg A.; Lu, Meng; Lu, Chuan; McPherson, Brian J.; Park, Eungyu

2010-07-01

441

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

442

Infrared radiant heating  

SciTech Connect

Retrofitting convective forced air heating systems with infrared (IR) systems can save as much as 50 percent of the total heating bill. Infrared heating is more efficient for two reasons: it can be directed to heat only occupied space; and it does not heat the air in a space, it only heats people and objects. Infrared heating works best where convective heaters are not practical. Large open bay buildings, such as hangars, workshops, and warehouses, with large volumes of air to be heated and plenty of unoccupied space are good candidates for retrofit. This TechData Sheet will help activity personnel understand infrared radiant heating, and identify opportunities for energy-conserving retrofit projects.

Cannon, S.; Rocha, M.

1996-05-01

443

Heat Pipe Technology  

NASA Technical Reports Server (NTRS)

The heat pipe, a sealed chamber whose walls are lined with a "wick," a thin capillary network containing a working fluid in liquid form was developed for a heat distribution system for non-rotating satellites. Use of the heat pipe provides a continuous heat transfer mechanism. "Heat tubes" that improve temperature control in plastics manufacturing equipment incorporated the heat pipe technology. James M. Stewart, an independent consultant, patented the heat tubes he developed and granted a license to Kona Corporation. The Kona Nozzle for heaterless injection molding gets heat for its operation from an external source and has no internal heating bands, reducing machine maintenance and also eliminating electrical hazards associated with heater bands. The nozzles are used by Eastman Kodak, Bic Pen Corporation, Polaroid, Tupperware, Ford Motor Company, RCA, and Western Electric in the molding of their products.

1981-01-01

444

Solar heating system  

SciTech Connect

A solar heating system including a flat plate solar collector having a heat absorber woven basket fashion across a riser grid system containing suitable flow medium for being heated by the solar radiation. A heat exchange column is coupled to the riser grid system for extracting the heat from the flow medium to provide it to heating, hot water, and the like. The heat exchange column includes a number of continuous coils placed within a tank and having a circulating loop pass a liquid from the bottom of the tank to the top of the tank where it will flow over all of the coils transferring heat from one coil to the other. The flow is controlled by means of the load demand and the available supply of heat. Excess heat is stored in a heat storage system having a plurality of blocks of Glauber salt containing matrix material through which pass pipes containing the heated liquid. One of the riser grid systems can be utilized as part of an absorption cycle air conditioning system by passing the heated fluid medium into a regenerator placed adjacent to the collector to effectively form a distillation process. In place of the liquid solar collector, an air heating solar collector is also provided.

Steinberg, A.

1984-02-07

445

Heat pipes for industrial waste heat recovery  

Microsoft Academic Search

Development work on the high temperature ceramic recuperator at Los Alamos National Laboratory is described and involved material investigations, fabrication methods development, compatibility tests, heat pipe operation, and the modeling of application conditions based on current industrial usage. Solid ceramic heat pipes, ceramic coated refractory pipes, and high-temperature oxide protected metallic pipes are investigated. Economic studies of the use of

M. A. Merrigan

1981-01-01

446

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

NASA Astrophysics Data System (ADS)

The layered compound BaCo1-xNixS2-y (0.05 < x < 0.2 and 0.05 < y < 0.2) exhibits an unusual first-order structural and electronic phase transition from a low-T monoclinic paramagnetic metal to a high-T tetragonal antiferromagnetic insulator around 200 K with huge hysteresis (˜40 K) and large volume change (˜0.01). Here, we report on unusual voltage-controlled resistive switching followed by current-controlled resistive switching induced by self-heating in polycrystalline BaCo1-xNixS2-y (nominal x = 0.1 and y = 0.2). These were due to the steep metal to insulator transition upon heating followed by the activated behavior of the resistivity above the transition. The major role of Joule heating in switching is supported by the absence of nonlinearity in the current as function of voltage, I(V), obtained in pulsed measurements, in the range of electric fields relevant to d.c. measurements. The voltage-controlled negative differential resistance around the threshold for switching was explained by a simple model of self-heating. The main difficulty in modeling I(V) from the samples resistance as function of temperature R(T) was the progressive increase of R(T), and to a lesser extend the decrease of the resistance jumps at the transitions, caused by the damage induced by cycling through the transitions by heating or self-heating. This was dealt with by following systematically R(T) over many cycles and by using the data of R(T) in the heating cycle closest to that of the self-heating one.

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

2014-04-01

447

Heat transfer system  

DOEpatents

A heat transfer system for a nuclear reactor. Heat transfer is accomplished within a sealed vapor chamber which is substantially evacuated prior to use. A heat transfer medium, which is liquid at the design operating temperatures, transfers heat from tubes interposed in the reactor primary loop to spaced tubes connected to a steam line for power generation purposes. Heat transfer is accomplished by a two-phase liquid-vapor-liquid process as used in heat pipes. Condensible gases are removed from the vapor chamber through a vertical extension in open communication with the chamber interior.

McGuire, Joseph C. (Richland, WA)

1982-01-01

448

Heat transfer system  

DOEpatents

A heat transfer system for a nuclear reactor is described. Heat transfer is accomplished within a sealed vapor chamber which is substantially evacuated prior to use. A heat transfer medium, which is liquid at the design operating temperatures, transfers heat from tubes interposed in the reactor primary loop to spaced tubes connected to a steam line for power generation purposes. Heat transfer is accomplished by a two-phase liquid-vapor-liquid process as used in heat pipes. Condensible gases are removed from the vapor chamber through a vertical extension in open communication with the chamber interior.

Not Available

1980-03-07

449

Microscale Regenerative Heat Exchanger  

NASA Technical Reports Server (NTRS)

The device described herein is designed primarily for use as a regenerative heat exchanger in a miniature Stirling engine or Stirling-cycle heat pump. A regenerative heat exchanger (sometimes called, simply, a "regenerator" in the Stirling-engine art) is basically a thermal capacitor: Its role in the Stirling cycle is to alternately accept heat from, then deliver heat to, an oscillating flow of a working fluid between compression and expansion volumes, without introducing an excessive pressure drop. These volumes are at different temperatures, and conduction of heat between these volumes is undesirable because it reduces the energy-conversion efficiency of the Stirling cycle.

Moran, Matthew E.; Stelter, Stephan; Stelter, Manfred

2006-01-01

450

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

451

Heat Transfer Through Fabrics.  

National Technical Information Service (NTIS)

Heat is transferred through fabrics by convection, conduction and radiation and under certain circumstances by vaporization. Each mode is subject to different physical principles but the effect of the total heat absorbed by underlying skin is the same: if...

A. M. Stoll M. A. Chianta

1970-01-01

452

An electrohydrodynamic heat pipe  

NASA Technical Reports Server (NTRS)

Dielectric liquid for transfer of heat provides liquid flow from the condenser section to the evaporator section in conventional heat pipes. Working fluid is guided or pumped by an array of wire electrodes connected to a high-voltage source.

Jones, T. B.

1972-01-01

453

Heat Wave Safety Checklist  

MedlinePLUS

... heat has caused more deaths than all other weather events, including floods. A heat wave is a ... stroke include hot, red skin which may be dry or moist; changes in consciousness; vomiting; and high ...

454

Monogroove liquid heat exchanger  

NASA Technical Reports Server (NTRS)

A liquid supply control is disclosed for a heat transfer system which transports heat by liquid-vapor phase change of a working fluid. An assembly (10) of monogroove heat pipe legs (15) can be operated automatically as either heat acquisition devices or heat discharge sources. The liquid channels (27) of the heat pipe legs (15) are connected to a reservoir (35) which is filled and drained by respective filling and draining valves (30, 32). Information from liquid level sensors (50, 51) on the reservoir (35) is combined (60) with temperature information (55) from the liquid heat exchanger (12) and temperature information (56) from the assembly vapor conduit (42) to regulate filling and draining of the reservoir (35), so that the reservoir (35) in turn serves the liquid supply/drain needs of the heat pipe legs (15), on demand, by passive capillary action (20, 28).

Brown, Richard F. (Inventor); Edelstein, Fred (Inventor)

1990-01-01

455

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

456

Compact, super heat exchanger  

NASA Technical Reports Server (NTRS)

Heat exchanger uses porous media to enhance heat transfer through walls of cooling channels, thereby lowering wall temperature. Porous media within cooling channel increases internal surface area from which heat can be transferred to coolant. Comparison data shows wall has lower temperature and coolant has higher temperature when porous medium is used within heat exchanger. Media can be sintered powedered metal, metal fibers, woven wire layers, or any porous metal having desired permeability and porosity.

Fortini, A.; Kazaroff, J. M.

1980-01-01

457

Urban Heat Islands  

NSDL National Science Digital Library

In this activity, students learn about the urban heat island effect by investigating which areas of their schoolyard have higher temperatures - trees, grass, asphalt, and other materials. Based on their results, they hypothesize how concentrations of surfaces that absorb heat might affect the temperature in cities - the urban heat island effect. Then they analyze data about the history of Los Angeles heat waves and look for patterns in the Los Angeles climate data and explore patterns.

Gardiner, Lisa; Universe, Windows T.

458

Isolated quantum heat engine.  

PubMed

We present a theoretical and numerical analysis of a quantum system that is capable of functioning as a heat engine. This system could be realized experimentally using cold bosonic atoms confined to a double well potential that is created by splitting a harmonic trap with a focused laser. The system shows thermalization, and can model a reversible heat engine cycle. This is the first demonstration of the operation of a heat engine with a finite quantum heat bath. PMID:22463540

Fialko, O; Hallwood, D W

2012-02-24

459

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

460

Methods of Heat Transfer  

NSDL National Science Digital Library

To help students better understand conduction, convection, and radiation as methods of heat transfer in solids, liquids and gases. Let's look at all three methods of heat transfer ... Overview of Conduction, Convection, Radiation Conduction- 1. Explain what happens as heat energy is supplied to one part of a solid. 2. Explain how energy is transferred by conduction through a solid. Convection- 1. What is ?anything fluid? ? Include two examples. 2. Describe how and why heat is transferred in ...

Carlone, Mrs.

2006-11-12

461

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

462

Abrasion resistant heat pipe  

DOEpatents

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 resistance while not substantially affecting the heat transfer characteristics of the system.

Ernst, Donald M. (Leola, PA)

1984-10-23

463

Heat pipes for industrial waste heat recovery  

NASA Astrophysics Data System (ADS)

Development work on the high temperature ceramic recuperator at Los Alamos National Laboratory is described and involved material investigations, fabrication methods development, compatibility tests, heat pipe operation, and the modeling of application conditions based on current industrial usage. Solid ceramic heat pipes, ceramic coated refractory pipes, and high-temperature oxide protected metallic pipes are investigated. Economic studies of the use of heat pipe based recuperators in industrial furnaces are conducted and payback periods determined as a function of material, fabrication, and installation cost.

Merrigan, M. A.

1981-01-01

464

Heat pipes for industrial waste heat recovery  

SciTech Connect

Development work on the high temperature ceramic recuperator at Los Alamos National Laboratory is described and involved material investigations, fabrication methods development, compatibility tests, heat pipe operation, and the modeling of application conditions based on current industrial usage. Solid ceramic heat pipes, ceramic coated refractory pipes, and high-temperature oxide protected metallic pipes have been investigated. Economic studies of the use of heat