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1

Brake Fluid Vapor Lock Temperatures vs Equilibrium Reflux Boiling Points.  

National Technical Information Service (NTIS)

Vapor lock temperatures (VLT) were determined on dry and humidified samples of all brake fluids listed on the Qualified Products List of Federal Specification VV-B-680, Brake Fluid Automotive, and compared to the equilibrium reflux boiling points (ERBP) o...

C. B. Jordan R. G. Jamison

1974-01-01

2

International Boiling Point Project  

NSDL National Science Digital Library

The purpose of this project is to discover which factor in the experiment (room temperature, elevation, volume of water, or heating device) has the greatest influence on boiling point. Anyone can participate in this year's project. All you have to do is boil a bit of water, record a bit of information, and send it along to the website to have your results included in the database of results. Then, students can analyze all of the data to reach an answer to the question: What causes a pot of water to boil?

2009-01-01

3

Boil, Boil, Toil and Trouble: The International Boiling Point Project  

NSDL National Science Digital Library

People from all over the world boil water at different elevations and post data to discover which factor in the experiment (room temperature, elevation, volume of water, or heating device) has the greatest influence on boiling point. Anyone can boil water, record information, and send it in for inclusion in the database of results. Students can analyze all the data to answer the question: What causes a pot of water to boil? Participation is invited at any time during the project's three-month span. Developed and managed by the Center for Improved Engineering and Science Education (CIESE) at Stevens Institute of Technology in Hoboken, NJ.

Forum, Math; Center for Improved Engineering and Science Education (CIESE)

2001-01-01

4

Boiling Time and Temperature  

NSDL National Science Digital Library

The purpose of this assessment probe is to elicit students' ideas about the characteristic property of boiling point. The probe is used to find out whether students recognize that the temperature of a boiling liquid stays constant no matter how long heat is applied.

Eberle, Francis; Tugel, Joyce; Keeley, Page

2007-01-01

5

Fast etching of silicon with a smooth surface in high temperature ranges near the boiling point of KOH solution  

Microsoft Academic Search

We report the etching characteristics of Si(100) and (110) at high temperature ranges near the boiling point of KOH solutions. The etching rates of Si(100) and (110) at near the boiling point were 5–9 times and 4–20 times higher than those at 80°C in the KOH concentrations of more than 32wt.%, respectively. At 145°C in 50wt.% KOH, we can get

Hiroshi Tanaka; Shuichi Yamashita; Yoshitsugu Abe; Mitsuhiro Shikida; Kazuo Sato

2004-01-01

6

The International Boiling Point Project  

NSDL National Science Digital Library

Between September 13 and December 10, 1999, the Center for Improved Engineering and Science Education (CIESE) at the Stevens Institute of Technology in Hoboken, New Jersey invites students and adults from all over the world to participate in The International Boiling Point Project. "The purpose of this project is to discover which factor in the experiment (room temperature, elevation, volume of water, or heating device) has the greatest influence on boiling point." Students, entire classes, or anyone else interested in participation must register beforehand via an online form. Data submitted online are posted at the site. The deadline for submitting data to be included in the final database is November 19, 1999. The project is an excellent forum for engaging students in the process of simple experimentation and data collection.

7

Trends in Alkane Boiling Points  

NSDL National Science Digital Library

This activity is an investigation into the relationship between alkane length and boiling points. Students develop a mathematical model of this relationship and use it to make predictions and error analysis.

Woods, Paula

8

CONTINUOUS ANALYZER UTILIZING BOILING POINT DETERMINATION  

DOEpatents

A device is designed for continuously determining the boiling point of a mixture of liquids. The device comprises a distillation chamber for boiling a liquid; outlet conduit means for maintaining the liquid contents of said chamber at a constant level; a reflux condenser mounted above said distillation chamber; means for continuously introducing an incoming liquid sample into said reflux condenser and into intimate contact with vapors refluxing within said condenser; and means for measuring the temperature of the liquid flowing through said distillation chamber. (AEC)

Pappas, W.S.

1963-03-19

9

An Analytical Approach for Relating Boiling Points of Monofunctional Organic Compounds to Intermolecular Forces  

ERIC Educational Resources Information Center

|The boiling point of a monofunctional organic compound is expressed as the sum of two parts: a contribution to the boiling point due to the R group and a contribution due to the functional group. The boiling point in absolute temperature of the corresponding RH hydrocarbon is chosen for the contribution to the boiling point of the R group and is…

Struyf, Jef

2011-01-01

10

A Mathematical Model for Simulation of Sofiwood Drying in Temperatures above Boiling Point of Water with Special Attention to the Boundary Conditions  

Microsoft Academic Search

A mathematical model for simulation of softwood drying also in temperatures exceeding the boiling point of water is presented. The equations are formulated in a conservative form based on the classical volume averaging technique with an addition of a pressure-driven moisture flux in the boundary condition. Numerical results using the control volume method are presented to show that this term

Antti Hukka

1996-01-01

11

Relationships between melting point and boiling point of organic compounds  

SciTech Connect

Relationships between melting point and boiling point are shown to be dependent upon the molecular symmetry number and a modified count of the total number of atoms in the molecule. Using the above relationships, the boiling and melting points of nearly 1,000 non-hydrogen-bonding organic compounds have been correlated. The correlations for boiling point and melting point have root mean square errors of 28 and 36 C, respectively.

Yalkowsky, S.H.; Krzyzaniak, J.F.; Myrdal, P.B. (Univ. of Arizona, Tucson, AZ (United States). College of Pharmacy)

1994-07-01

12

Prediction of high-temperature thermodynamic properties of mixed electrolyte solutions including solubility equilibria, vapor pressure depression and boiling point elevation  

SciTech Connect

The Pitzer ion-interaction model, which is theoretically derived but uses empirical parameters evaluated from experimental data on binary and ternary aqueous mixtures, is shown to accurately predict thermodynamic properties of aqueous eletrolytes to high temperatures and concentrations and for more complex compositions. Applications of the model include calculations of solubility equilibria, vapor pressures and boiling points of electrolyte mixtures. Examples of these calculations are given below. 32 refs., 5 figs., 2 tabs.

Pabalan, R.T.; Pitzer, K.S.

1988-01-01

13

Hadronic matter near the boiling point  

Microsoft Academic Search

Summary  Hadron collisions above ?10 GeV\\/c primary laboratory momentum show an interesting global aspect (i.e. when averaged over all final channels): they can be described as a superposition of a rather special form of thermodynamics\\u000a and of the kinematics of collective motions in the forward-backward direction. The thermodynamical behaviour is similar to\\u000a that of boiling; the boiling temperatureT\\u000a 0 is not

Rolf Hagedorn

1968-01-01

14

Thermogravimetric analysis for boiling points and vapour pressure  

Microsoft Academic Search

A TGA instrument has been adapted for rapid measurement of boiling points and vapour pressure at temperatures from ambient up to 400°C and pressures from ambient down to 20 mm Hg. Samples were contained in sealed holders having a laser-drilled aperture. Several organic liquids in the 100 to 300 gMW range showed good agreement with reference vapour pressure data. Sample

J. W. Goodrum; E. M. Siesel

1996-01-01

15

From boiling point to glass transition temperature: Transport coefficients in molecular liquids follow three-parameter scaling  

NASA Astrophysics Data System (ADS)

The phenomenon of the glass transition is an unresolved problem in condensed matter physics. Its prominent feature, the super-Arrhenius temperature dependence of the transport coefficients, remains a challenge to be described over the full temperature range. For a series of molecular glass formers, we combined ?(T) collected from dielectric spectroscopy and dynamic light scattering covering a range 10-12 s < ?(T) < 102 s. Describing the dynamics in terms of an activation energy E(T), we distinguish a high-temperature regime characterized by an Arrhenius law with a constant activation energy E? and a low-temperature regime for which Ecoop(T) ? E(T)-E? increases exponentially while cooling. A scaling is introduced, specifically Ecoop(T)/E? ? exp[-?(T/TA-1)], where ? is a fragility parameter and TA a reference temperature proportional to E?. In order to describe ?(T) still the attempt time ?? has to be specified. Thus, a single interaction parameter E? describing the high-temperature regime together with ? controls the temperature dependence of low-temperature cooperative dynamics.

Schmidtke, B.; Petzold, N.; Kahlau, R.; Hofmann, M.; Rössler, E. A.

2012-10-01

16

From boiling point to glass transition temperature: transport coefficients in molecular liquids follow three-parameter scaling.  

PubMed

The phenomenon of the glass transition is an unresolved problem in condensed matter physics. Its prominent feature, the super-Arrhenius temperature dependence of the transport coefficients, remains a challenge to be described over the full temperature range. For a series of molecular glass formers, we combined ?(T) collected from dielectric spectroscopy and dynamic light scattering covering a range 10(-12) s < ?(T) < 10(2) s. Describing the dynamics in terms of an activation energy E(T), we distinguish a high-temperature regime characterized by an Arrhenius law with a constant activation energy E(?) and a low-temperature regime for which E(coop)(T) ? E(T)-E(?) increases exponentially while cooling. A scaling is introduced, specifically E(coop)(T)/E(?) [proportionality] exp[-?(T/T(A)-1)], where ? is a fragility parameter and T(A) a reference temperature proportional to E(?). In order to describe ?(T) still the attempt time ?(?) has to be specified. Thus, a single interaction parameter E(?) describing the high-temperature regime together with ? controls the temperature dependence of low-temperature cooperative dynamics. PMID:23214591

Schmidtke, B; Petzold, N; Kahlau, R; Hofmann, M; Rössler, E A

2012-10-19

17

Vapor pressure critical amplitudes from the normal boiling point  

NASA Astrophysics Data System (ADS)

The authors propose a method to estimate the two first critical amplitudes for the vapor pressure of a fluid in terms only of the reduced pressure, Pbr=Pb/Pc, and temperature, Tbr=Tb/Tc, of the normal boiling point. The method is based on the fact that the product (1-Tr)Pr presents a maximum near the critical region. Based on a study of 43 fluids, the authors found that the reduced pressure and temperature of that maximum can be obtained from simple relations in terms of the parameter h?Tbr ln Pbr/(Tbr-1). These relations are checked against additional data for 1608 fluids.

Velasco, S.; Román, F. L.; White, J. A.; Mulero, A.

2007-04-01

18

Vapor pressure and boiling point elevation of slash pine black liquors: Predictive models with statistical approach  

SciTech Connect

Vapor-liquid equilibria and boiling point elevation of slash pine kraft black liquors over a wide range of solid concentrations (up to 85% solids) has been studied. The liquors are from a statistically designed pulping experiment for pulping slash pine in a pilot scale digester with four cooking variables of effective alkali, sulfidity, cooking time, and cooking temperature. It was found that boiling point elevation of black liquors is pressure dependent, and this dependency is more significant at higher solids concentrations. The boiling point elevation data at different solids contents (at a fixed pressure) were correlated to the dissolved solids (S/(1 {minus} S)) in black liquor. Due to the solubility limit of some of the salts in black liquor, a change in the slope of the boiling point elevation as a function of the dissolved solids was observed at a concentration of around 65% solids. An empirical method was developed to describe the boiling point elevation of each liquor as a function of pressure and solids mass fraction. The boiling point elevation of slash pine black liquors was correlated quantitatively to the pulping variables, using different statistical procedures. These predictive models can be applied to determine the boiling point rise (and boiling point) of slash pine black liquors at processing conditions from the knowledge of pulping variables. The results are presented, and their utility is discussed.

Zaman, A.A.; McNally, T.W.; Fricke, A.L. [Univ. of Florida, Gainesville, FL (United States)

1998-01-01

19

New equations predict boiling point from viscosity, gravity  

SciTech Connect

A simple numerical routine computes the normal boiling point of light and heavy petroleum fractions as a function of kinematic viscosities at 100 F abd 219 F and specific gravity at 60 F. The algorithm makes use of a single nonlinear equation with one unknown variable (boiling point), which requires numerical solution. A convenient correlation generates starting values for mean average boiling point (MeABP) that are accurate enough to allow convergence in three or fewer iterations. The paper discusses the need for new equations, the new approach, and the calculations.

Gomez, J.V. [Maraven S.A., Punto Fijo (Venezuela)

1996-10-07

20

Vapor pressure and normal boiling point predictions for pure methyl esters and biodiesel fuels  

Microsoft Academic Search

Temperature dependent vapor pressures of the methyl esters of fourteen fatty acids that are commonly present in biodiesel fuels were predicted by the Antoine equation and a group contribution method. The predicted boiling points of these esters up to a pressure of 100mmHg were within ±1.0% of reported data for these two methods. Normal boiling points were determined from both

W. Yuan; A. C. Hansen; Q. Zhang

2005-01-01

21

Prediction of the boiling temperature and heat flux in sugar water solutions under pool-boiling conditions  

NASA Astrophysics Data System (ADS)

Condensing of a sugar water solution is a widely used production process, especially in food industry. In this study, boiling temperature and heat transfer of different concentration levels of sugar/water solution is experimentally studied. In the experiment, the pool boiling with constant temperature difference between surface and boiling temperature is investigated. Boiling point of sugar/water solution depends on sugar mass concentration and on vapor phase pressure. A function is suggested to calculation the boiling temperature. The experimental data and the calculated values of boiling temperature are compared. The results are verified with previous investigations. It is determined that the heat flux between surface and sugar/water solution while pool boiling displays a linear relation with water mass concentration in the solution. Heat transfer coefficient could be determined in dependency of surface temperature and sugar mass concentration. Furthermore a function is suggested to predict the heat flux for engineering purpose, which is already used in similar form for pure substances.

Özdemir, Mustafa; Pehlivan, Hüseyin

2008-05-01

22

Transient model for minimum film boiling point in sub-cooled film boiling  

Microsoft Academic Search

A complete transient dynamic model for bubble growth, neck breakup, bubble detachment, interface retraction, liquid-solid contact, initial nucleation, nucleation bubble growth, and coalesce in pool film boiling on a flat plate was developed to predict the heat-transfer coefficient, minimum film-boiling temperature and heat flux in subcooled liquids. Each submodel for each step was modeled separately and coupled to the next

L. K. T

1987-01-01

23

Boiling.  

National Technical Information Service (NTIS)

Contents: Saturated boiling, subcooled boiling, mechanism of nucleate boiling, fluid flow with boiling, boiling terminology; nucleation and bubble dynamics, nucleation from a solid surface, homogeneous nucleation and radiation effects, bubble dynamics; nu...

G. Leppert C. C. Pitts

1964-01-01

24

An electronic instrument for registration of true boiling points  

Microsoft Academic Search

A description was given of the electronics of a device used to determine the true boiling points of complex mixtures. The device operated with contactless connection of the metering pump motor and the mechanism for movement of the recorder chart. A schematic diagram of the electronics of the device was given. Also, a description of the functioning of the device

Y. M. Bugrov; D. D. Zykov; E. A. Belenov

1982-01-01

25

Life above the boiling point of water?  

Microsoft Academic Search

Summary Various extremely thermophilic archaebacteria exhibit optimum growth at above 80°C.Pyrodictium is the most thermophilic of these organisms, growing at temperatures of up to 110°C and exhibiting optimum growth at about 105°C. All of these organisms grow by diverse types of anaerobic and aerobic metabolism.

K. O. Stetter; G. Fiala; R. Huber; G. Huber; A. Segerer

1986-01-01

26

Vapor pressure and boiling point elevation of slash pine black liquors: Predictive models with statistical approach  

Microsoft Academic Search

Vapor-liquid equilibria and boiling point elevation of slash pine kraft black liquors over a wide range of solid concentrations (up to 85% solids) has been studied. The liquors are from a statistically designed pulping experiment for pulping slash pine in a pilot scale digester with four cooking variables of effective alkali, sulfidity, cooking time, and cooking temperature. It was found

A. A. Zaman; T. W. McNally; A. L. Fricke

1998-01-01

27

Prediction of boiling points of organic compounds by QSPR tools.  

PubMed

The novel electro-negativity topological descriptors of YC, WC were derived from molecular structure by equilibrium electro-negativity of atom and relative bond length of molecule. The quantitative structure-property relationships (QSPR) between descriptors of YC, WC as well as path number parameter P3 and the normal boiling points of 80 alkanes, 65 unsaturated hydrocarbons and 70 alcohols were obtained separately. The high-quality prediction models were evidenced by coefficient of determination (R(2)), the standard error (S), average absolute errors (AAE) and predictive parameters (Qext(2),RCV(2),Rm(2)). According to the regression equations, the influences of the length of carbon backbone, the size, the degree of branching of a molecule and the role of functional groups on the normal boiling point were analyzed. Comparison results with reference models demonstrated that novel topological descriptors based on the equilibrium electro-negativity of atom and the relative bond length were useful molecular descriptors for predicting the normal boiling points of organic compounds. PMID:23792208

Dai, Yi-Min; Zhu, Zhi-Ping; Cao, Zhong; Zhang, Yue-Fei; Zeng, Ju-Lan; Li, Xun

2013-05-04

28

Rapid measurements of boiling point and vapor pressure of short-chain triglycerides by thermogravimetric analysis  

Microsoft Academic Search

Temperature dependence of vapor pressure and the boiling points for tricaproin (Tcap) and tricaprylin (Tcpy) were measured\\u000a by a new rapid thermogravimetric analysis (TGA) method. Results were in agreement with data from other references. The Clausius\\/Clapeyron\\u000a model fitted Tcap and Tcpy vapor pressure data with errors of 6% or less for pressures ranging from ambient down to 20 mmHg.\\u000a This

J. W. Goodrum

1997-01-01

29

Departure from Natural Convection (DNC) in Low-Temperature Boiling Heat Transfer Encountered in Cooling Microelectronic LSI Devices  

Microsoft Academic Search

Recent experiments with low-temperature boiling heat transfer have shown that the determination of the transition point from natural convection to nucleate boiling is important in cooling microelectronic components. This paper discusses the nature of this transition, introduced here as the departure from natural convection (DNC). It is shown that the DNC, which is usually accompanied by excessive temperature overshoot, is

S. Oktay

1988-01-01

30

Evaluation of the polarity and boiling points of nitrogen-containing heterocyclic compounds by gas chromatography  

Microsoft Academic Search

Experimental gas-chromatographic data for 55 aromatic and aliphatic N-containing heterocyclic compounds and C5–C13\\u000a n-alkanes are analyzed. The polar constitutents of the boiling points (T\\u000a pol) were calculated as the difference between the boiling points measured directly and the boiling points calculated from GC\\u000a data obtained on a nonpolar column. Depending on the number, nature, and position of heteroatoms and alkyl

I. L. Zhuravleva; N. M. Emanuel

2000-01-01

31

Design of ultrasonically-activatable nanoparticles using low boiling point perfluorocarbons.  

PubMed

Recently, an interest has developed in designing biomaterials for medical ultrasonics that can provide the acoustic activity of microbubbles, but with improved stability in vivo and a smaller size distribution for extravascular interrogation. One proposed alternative is the phase-change contrast agent. Phase-change contrast agents (PCCAs) consist of perfluorocarbons (PFCs) that are initially in liquid form, but can then be vaporized with acoustic energy. Crucial parameters for PCCAs include their sensitivity to acoustic energy, their size distribution, and their stability, and this manuscript provides insight into the custom design of PCCAs for balancing these parameters. Specifically, the relationship between size, thermal stability and sensitivity to ultrasound as a function of PFC boiling point and ambient temperature is illustrated. Emulsion stability and sensitivity can be 'tuned' by mixing PFCs in the gaseous state prior to condensation. Novel observations illustrate that stable droplets can be generated from PFCs with extremely low boiling points, such as octafluoropropane (b.p. -36.7 °C), which can be vaporized with acoustic parameters lower than previously observed. Results demonstrate the potential for low boiling point PFCs as a useful new class of compounds for activatable agents, which can be tailored to the desired application. PMID:22289265

Sheeran, Paul S; Luois, Samantha H; Mullin, Lee B; Matsunaga, Terry O; Dayton, Paul A

2012-01-29

32

Design of Ultrasonically-Activatable Nanoparticles using Low Boiling Point Perfluorocarbons  

PubMed Central

Recently, an interest has developed in designing in biomaterials for medical ultrasonics that can provide the acoustic activity of microbubbles, but with improved stability in vivo and a smaller size distribution for extravascular interrogation. One proposed alternative is the phase-change contrast agent. Phase-change contrast agents (PCCAs) consist of perfluorocarbons (PFCs) that are initially in liquid form, but can then be vaporized with acoustic energy. Crucial parameters for PCCAs include their sensitivity to acoustic energy, their size distribution, and their stability, and this manuscript provides insight into the custom design of PCCAs for balancing these parameters. Specifically, the relationship between size, thermal stability and sensitivity to ultrasound as a function of PFC boiling point and ambient temperature is illustrated. Emulsion stability and sensitivity can be ‘tuned’ by mixing PFCs in the gaseous state prior to condensation. Novel observations illustrate that stable droplets can be generated from PFCs with extremely low boiling points, such as octafluoropropane (b.p. ?36.7°C), which can be vaporized with acoustic parameters lower than previously observed. Results demonstrate the potential for low boiling point PFCs as a useful new class of compounds for activatable agents, which can be tailored to the desired application.

Sheeran, Paul S.; Luois, Samantha; Mullin, Lee; Matsunaga, Terry O.

2012-01-01

33

The Gibbs Energy Basis and Construction of Boiling Point Diagrams in Binary Systems  

ERIC Educational Resources Information Center

An illustration of how excess Gibbs energies of the components in binary systems can be used to construct boiling point diagrams is given. The underlying causes of the various types of behavior of the systems in terms of intermolecular forces and the method of calculating the coexisting liquid and vapor compositions in boiling point diagrams with…

Smith, Norman O.

2004-01-01

34

Volatility and boiling points of biodiesel from vegetable oils and tallow  

Microsoft Academic Search

Quality control of fuel-related properties of Biodiesel, such as volatility, is needed to obtain consistent engine performance by fuel users. The vapor pressures and boiling points of selected methyl esters and vegetable oils are proposed as quality control metrics for Biodiesel. This type of data was obtained by a rapid new method using thermogravimetric analysis (TGA). One atmosphere boiling points

J. W. Goodrum

2002-01-01

35

Normal Boiling Points for Organic Compounds: Correlation and Prediction by a Quantitative Structure-Property Relationship  

Microsoft Academic Search

We recently reported a successful correlation of the normal boiling points of 298 organic compounds containing O, N, Cl, and Br with two molecular descriptors.1 In the present study the applicability of these two descriptors for the prediction of boiling points for various other classes of organic compounds was investigated further by employing a diverse data set of 612 organic

Alan R. Katritzky; Victor S. Lobanov; Mati Karelson

1998-01-01

36

Uniform Mems Chip Temperatures in the Nucleate Boiling Heat Transfer Region by Selecting Suitable, Medium Boiling Number Range  

Microsoft Academic Search

The not only lower but also uniform MEMS chip temperatures can be reached by selecting suitable boiling number range that ensures the nucleate boiling heat transfer. In this article, boiling heat transfer experiments in 10 silicon triangular microchannels with the hydraulic diameter of 155.4 ?m were performed using acetone as the working fluid, having the inlet liquid temperatures of 24–40°C,

J. L. Xu; Y. H. Gan

2007-01-01

37

TRANSPORT OF HIGH BOILING POINT FIRE SUPPRESSANTS IN A DROPLET-LADEN HOMOGENEOUS TURBULENT FLOW PAST A CYLINDER  

Microsoft Academic Search

Liquid agent transport was investigated around unheated and heated horizontal cylinders (to a near-surface temperature of approximately 423 K, i.e., well above the water boiling point) under ambient conditions. Experimental results are presented for a well-characterized, droplet-laden homogenous turbulent flow field, using water, methoxy-nonafluorobutane (i.e., HFE-7100, C4F9OCH3, with a boiling point of 334 K), and 1-methoxyheptafluoropropane (i.e., HFE-7000, C3F7OCH3, with

Cary Presser; C. T. Avedisian

2006-01-01

38

Spatially resolved wall temperature measurements during flow boiling in microchannels  

Microsoft Academic Search

Spatial and temporal variations of channel wall temperature during flow boiling microchannel flows using infrared thermography are presented and analyzed. In particular, the top channel wall temperature in a branching microchannel silicon heat sink is measured non-intrusively. Using this technique, time-averaged temperature measurements, with a spatial resolution of 10?m, are presented over an 18mm×18mm area of the heat sink. Also

Daniel Krebs; Vinod Narayanan; James Liburdy; Deborah Pence

2010-01-01

39

The Elevation of Boiling Points in H_2O and D_2O Electrolytes  

NASA Astrophysics Data System (ADS)

The excess enthalpy effect in cold fusion experiments for Pd/D_2O systems is subject to positive feedback, i.e., increasing the cell temperature increases the excess enthalpy . Therefore, the largest excess enthalpy effects are often observed near or at the boiling point corresponding to that of the electrolyte solution in the cell(M.H. Miles, M. Fleischmann and M.A. Imam, "Calorimetric Analysis of a Heavy Water Electrolysis Experiment Using a Pd-B Alloy Cathode", Naval Research Lab Mem. Rep.,#6320-01-8526, pp. 27-30 (2001).). However, the actual boiling point increases as the D_2O content of the cell decreases. The purpose of this project will be to compare experimental values of the change in temperature ?T obtained using H_2O and D_2O solutions with theoretical values of ?T calculated by assuming ideal solutions. The emphasis will be on higher concentrations as well as on saturated solutions where ?T values may be quite large. Preliminary results for LiOH in H_2O show reasonable agreement with ideal solution ?T values up to LiOH concentrations of 1.0 molal (m).

Miles, M. H.; Arman, H. D.; Carrick, J. D.; Gren, C. K.; Haggerty, K. A.; Kim, H. Y.; Ky, A. G.; Markham, J. E.; Meeks, C. F.; Noga, D. E.

2002-03-01

40

Boiling water with ice: Effect of pressure on the boiling point of water  

NSDL National Science Digital Library

This guided inquiry activity, in which ice is used to boil water in a Florence flask, works well in the introductory class to a chemistry or physical science course. The students will learn the difference between observation and inference and apply this understanding to various other situations in which observations and inferences must be made. The students will also use outside sources to try to explain why the activity worked.

41

Determination of organic substances with different boiling points in aqueous media by capillary gas-liquid chromatography  

Microsoft Academic Search

Studies were conducted on separation of organic substances with different boiling points and polarity when simultaneously\\u000a present in water by capillary gas-liquid chromatography on a Kristall 2000 m chromatograph. The effect of the column phase\\u000a and temperature conditions on the separation factor and component exit time was investigated. Column temperature programming\\u000a was used to reduce the component, especially heavy component,

E. A. Rogova; O. A. Roshchina; T. I. Samsonova; A. V. Genis

2009-01-01

42

Rapid thermogravimetric measurements of boiling points and vapor pressure of saturated medium- and long-chain triglycerides.  

PubMed

In developing compositional models for biomass-based diesel fuel extenders, volatility properties of medium- and long-chain saturated triglycerides are essential to predict the impact of low levels of these compounds in mixtures with short-chain triglycerides. A thermogravimetric analysis (TGA) method for rapid measurement of boiling points and vapor pressure was used to obtain data for four pure medium- and long-chain triglycerides. Normal boiling points at 1 atm and the temperature dependence of vapor pressure from 760 mm down to 25 mm Hg were obtained for trilaurin (C12:0), trimyristin (C14:0), tripalmitin (C16:0), and tristearin (C18:0). The data showed good agreement with the Clausius-Clapeyron model for temperature dependence of vapor pressure up to 1 atm pressure. The results of this study were consistent with those obtained using differential scanning calorimetry (DSC) and with data previously reported for reduced pressure. PMID:12137273

Goodrum, John W; Geller, Daniel P

2002-08-01

43

Rapid measurement of boiling points and vapor pressure of binary mixtures of short-chain triglycerides by TGA method  

Microsoft Academic Search

Thermogravimetric analysis (TGA), has been used to rapidly obtain data on the temperature dependence of vapor pressure (760, down to 20mmHg) and the boiling points for simple binary mixtures of tributyrin (C4:0), tricaproin (C6:0) and\\/or tricaprylin (C8:0). Vapor-pressure measurements were taken for binary mixtures of the aforementioned compounds as a function of mole fraction. Additional measurements of methyl esters of

J. W Goodrum; D. P Geller; S. A Lee

1998-01-01

44

Thermoplastic fusion bonding using a pressure-assisted boiling point control system.  

PubMed

A novel thermoplastic fusion bonding method using a pressure-assisted boiling point (PABP) control system was developed to apply precise temperatures and pressures during bonding. Hot embossed polymethyl methacrylate (PMMA) components containing microchannels were sealed using the PABP system. Very low aspect ratio structures (AR = 1/100, 10 ?m in depth and 1000 ?m in width) were successfully sealed without collapse or deformation. The integrity and strength of the bonds on the sealed PMMA devices were evaluated using leakage and rupture tests; no leaks were detected and failure during the rupture tests occurred at pressures greater than 496 kPa. The PABP system was used to seal 3D shaped flexible PMMA devices successfully. PMID:22728966

Park, Taehyun; Song, In-Hyouk; Park, Daniel S; You, Byoung Hee; Murphy, Michael C

2012-06-22

45

Students' Understanding of Boiling Points and Intermolecular Forces  

ERIC Educational Resources Information Center

In introductory chemistry courses students are presented with the model that matter is composed of particles, and that weak forces of attraction exist between them. This model is used to interpret phenomena such as solubility and melting points, and aids in understanding the changes in states of matter as opposed to chemical reactions. We…

Schmidt, Hans-Jurgen; Kaufmann, Birgit; Treagust, David F.

2009-01-01

46

Students' Understanding of Boiling Points and Intermolecular Forces  

ERIC Educational Resources Information Center

|In introductory chemistry courses students are presented with the model that matter is composed of particles, and that weak forces of attraction exist between them. This model is used to interpret phenomena such as solubility and melting points, and aids in understanding the changes in states of matter as opposed to chemical reactions. We…

Schmidt, Hans-Jurgen; Kaufmann, Birgit; Treagust, David F.

2009-01-01

47

Explaining Melting and Evaporation below Boiling Point. Can Software Help with Particle Ideas?  

ERIC Educational Resources Information Center

This paper reports the findings of a study exploring the use of a software package to help pupils understand particulate explanations for melting and evaporation below boiling point. Two matched classes in a primary school in Greece (ages 11-12, n = 16 and 19) were involved in a short intervention of six one hour lessons. Covering the same…

Papageorgiou, George; Johnson, Philip; Fotiades, Fotis

2008-01-01

48

A new search algorithm for QSPR\\/QSAR theories: Normal boiling points of some organic molecules  

Microsoft Academic Search

We test a new algorithm for the search of an optimal subset of molecular descriptors from a large set of them. As a practical realistic application we predict the normal boiling points of 200 organic molecules by means of molecular descriptors selected from a set of more than thousand of rigid molecular descriptors produced by the DRAGON 5 evaluation software,

Pablo R. Duchowicz; Eduardo A. Castro; Francisco M. Fernández; Maykel P. Gonzalez

2005-01-01

49

Modeling of acyclic carbonyl compounds normal boiling points by correlation weighting of nearest neighboring codes  

Microsoft Academic Search

The nearest neighboring code (NNC) is a local graph invariant. The NNC of a given vertex of the labeled hydrogen filled graph (LHFG) is a function of atom composition of the vertex neighbors. By optimization the correlation weights of different atoms and different values of the NNCs, one-variable models of the normal boiling points of carbonyl compounds have been obtained.

A. A. Toropov; A. P. Toropova

2002-01-01

50

Explaining melting and evaporation below boiling point. Can software help with particle ideas?  

Microsoft Academic Search

This paper reports the findings of a study exploring the use of a software package to help pupils understand particulate explanations for melting and evaporation below boiling point. Two matched classes in a primary school in Greece (ages 11–12, n = 16 and 19) were involved in a short intervention of six one hour lessons. Covering the same phenomena and

George Papageorgiou; Philip Johnson; Fotis Fotiades

2008-01-01

51

Explaining Melting and Evaporation below Boiling Point. Can Software Help with Particle Ideas?  

ERIC Educational Resources Information Center

|This paper reports the findings of a study exploring the use of a software package to help pupils understand particulate explanations for melting and evaporation below boiling point. Two matched classes in a primary school in Greece (ages 11-12, n = 16 and 19) were involved in a short intervention of six one hour lessons. Covering the same…

Papageorgiou, George; Johnson, Philip; Fotiades, Fotis

2008-01-01

52

Comparison of different heating methods for the temperature-controlled measurement of convective transition boiling  

SciTech Connect

For the experimental investigation of the transition boiling regime, special heating and control methods have to be introduced to ensure stability. Typical problems of all these methods are the large axial temperature gradient after the transition boiling mode first appears on the heat transfer surface and the failure of stability under some conditions. Through numerical solution of the heat conduction problem related to the temperature-controlled test section, which has a strongly nonlinear boiling topography as one of its boundary conditions, different types of heating methods can be compared in terms of axial temperature gradient, extension of the transition boiling mode, and the second-order instability.

Huang, X.C.; Bartsch, G. (Technische Univ. Berlin (Germany). Institut fuer Energietechnik)

1994-04-01

53

Quantitative Structure-Property Relationships for the Normal Boiling Temperatures of Acyclic Carbonyl Compounds  

Microsoft Academic Search

Quantitative structure-property relationships (QSPR) models for the estimation of normal boiling temperatures for a set of 200 acyclic carbonyl compounds (containing mono- and dialdehydes, mono- and diketones, keto aldehydes, and esters of monocarboxylic acids) were established with the CODESSA program. The QSPR models developed with CODESSA allow accurate computation of the boiling temperatures of organic compounds using simple constitutional, topological,

Ovidiu Ivanciuc; Teodora Ivanciuc; Alexandru T. Balaban

54

Surface boiling - an "obvious" explanation for the observed limiting temperature of finite nuclei  

NASA Astrophysics Data System (ADS)

Limits of stability of nuclear systems are explored within the framework of a finite-range interacting Fermi gas model and microcanonical thermodynamics in Thomas-Fermi approximation. It is found that with increasing excitation energy, infinite systems become unstable against volume boiling, while finite systems become subject to surface boiling, providing a natural explanation for the observed saturationlike patterns, or limiting temperature, in caloric curves. Boiling patterns of iso-asymmetric matter are discussed.

Tõke, J.

2012-07-01

55

Application of the QSPR approach to the boiling points of azeotropes.  

PubMed

CODESSA Pro derivative descriptors were calculated for a data set of 426 azeotropic mixtures by the centroid approximation and the weighted-contribution-factor approximation. The two approximations produced almost identical four-descriptor QSPR models relating the structural characteristic of the individual components of azeotropes to the azeotropic boiling points. These models were supported by internal and external validations. The descriptors contributing to the QSPR models are directly related to the three components of the enthalpy (heat) of vaporization. PMID:21449551

Katritzky, Alan R; Stoyanova-Slavova, Iva B; Tämm, Kaido; Tamm, Tarmo; Karelson, Mati

2011-03-30

56

Use of high-boiling point organic solvents for pulping oil palm empty fruit bunches  

Microsoft Academic Search

Oil palm empty fruit bunches were used as an alternative raw material to obtain cellulosic pulp. Pulping was done by using high-boiling point organic solvents of decreased polluting power relative to classical (Kraft, sulphite) solvents but affording operation at similar pressure levels.The holocellulose, ?-cellulose and lignin contents of oil palm empty fruit bunches (viz. 66.97%, 47.91% and 24.45%, respectively) are

Alejandro Rodríguez; Luis Serrano; Ana Moral; Antonio Pérez; Luis Jiménez

2008-01-01

57

Vapour pressure of isotopic liquids. I. — A, N 2 , O 2 below boiling-point  

Microsoft Academic Search

Summary  A static equilibration method was used to measure the single stage separation factor ? of isotopic pairs in the vapour liquid\\u000a equilibrium of A, N2 and O2 below boiling-point. Since the corresponding isotopic mixtures are supposed to be ideal, the vapour pressure ratio of the\\u000a studied isotopic liquids is identical to ?. Due to the sensitivity and the precision of

G. Boato; G. Scoles; M. E. Vallauri

1959-01-01

58

Estimating surface temperature in forced convection nucleate boiling - A simplified method  

Microsoft Academic Search

A simplified expression to estimate surface temperatures in forced convection boiling was developed using a liquid nitrogen data base. Using the principal of corresponding states and the Kutateladze relation for maximum pool boiling heat flux, the expression was normalized for use with other fluids. The expression was applied also to neon and water. For the neon data base, the agreement

R. C. Hendricks; S. S. Papell

1977-01-01

59

Emplacement temperatures of boiling-over pyroclastic density currents from Tungurahua and Cotopaxi volcanoes, Ecuador  

NASA Astrophysics Data System (ADS)

Pyroclastic density currents (PDC) can be sourced by collapsing columns, dome collapse, and boiling-over fountains. Although there are innumerable studies of the deposits produced by the first 2 mechanisms, pyroclastic deposits from boiling-over have not been well characterized. We are studying several pyroclastic flow deposits from two boiling over eruptions in Ecuador, Tungurahua, 2006 and Cotopaxi, 1877. These eruptions produced abundant cauliflower-textured, large (up to 1 m in diameter), fragile scoria clasts. Some evidence points to relatively low temperatures during transport. For example, some flows at Cotopaxi are unusually long and sinuous and probably influenced by melt water from the glacier that caps the cone. Additionally, un-charred vegetation and eyewitness reports of un-melted plastic in the path of pyroclastic flows at Tungurahua also support cool emplacement temperatures. On the other hand, some scoria clasts were ductile when deposited as evidenced by draped clasts. We cut 5 to 9 cm transects from rim to core of 36 lithic and juvenile samples, which were then thermally demagnetized and measured. Lithic samples from Tungurahua indicate only one flow was fully remagnetized above ~580°C, while another flow was only partially remagnetized below 210°C. All other lithics from both volcanoes were never heated to above 90°C. Juvenile clasts from Cotopaxi indicate three types of flows: currents that begin hot (above 580°C) but cool quickly (juveniles emplaced hot, but lithics emplaced cold); currents that deposit at ~330°C (two components of magnetization that intersect at 330°C in the juvenile clasts), and cold currents such as lahars. The majority of currents from Tungurahua are of the 2nd type, having emplacement temperatures of ~380°C-280°C, with the deformable juvenile clasts being hotter than the rest of the flow. Despite the intact nature of the fragile bombs, emplacement temperatures indicate that the majority of flow deposits at Tungurahua and Cotopaxi were emplaced at temperatures between 210°C and 380°C. The presence of abundant scoria bombs in other PDC deposits are likely indicative of flow and deposition at relatively low temperatures in currents produced by a boiling-over mechanism.

Rader, E. L.; Geist, D.; Geissman, J. W.; Harpp, K. S.; Dufek, J.

2011-12-01

60

A new procedure for the determination of distillation temperature distribution of high-boiling petroleum products and fractions  

Microsoft Academic Search

The distribution of distillation temperatures of liquid and semi-fluid products, including petroleum fractions and products,\\u000a is an important process and practical parameter. It provides information on properties of crude oil and content of particular\\u000a fractions, classified on the basis of their boiling points, as well as the optimum conditions of atmospheric or vacuum distillation.\\u000a At present, the distribution of distillation

Grzegorz Boczkaj; Andrzej Przyjazny; Marian Kami?ski

2011-01-01

61

A new search algorithm for QSPR/QSAR theories: Normal boiling points of some organic molecules  

NASA Astrophysics Data System (ADS)

We test a new algorithm for the search of an optimal subset of molecular descriptors from a large set of them. As a practical realistic application we predict the normal boiling points of 200 organic molecules by means of molecular descriptors selected from a set of more than thousand of rigid molecular descriptors produced by the DRAGON 5 evaluation software, plus two flexible descriptors. We thus improve previous results derived from the application of Correlation Weighting of Atomic Orbitals with Extended Connectivity of Zero- and First-Order Graphs of Atomic Orbitals.

Duchowicz, Pablo R.; Castro, Eduardo A.; Fernandez, Francisco M.; Gonzalez, Maykel P.

2005-09-01

62

Generalized syntheses of nanocrystal-graphene hybrids in high-boiling-point organic solvents  

NASA Astrophysics Data System (ADS)

Nanocrystal-graphene have been proposed as a new kind of promising hybrid for a wide range of application areas including catalysts, electronics, sensors, biomedicine, and energy storage, etc. Although a variety of methods have been developed for the preparation of hybrids, a facile and general synthetic approach is still highly required. In this study, nanocrystal-graphene hybrids were successfully synthesized in high-boiling-point organic solvents. Graphene oxide (GO) nanosheets were modified by oleylamine (OLA) to form a OLA-GO complex in order to be readily incorporated into hydrophobic synthesis. A rich library of highly crystalline nanocrystals, with types including noble metal, metal oxide, magnetic material and semiconductor were successfully grown on chemically converted graphene (CCG), which is simultaneously reduced from GO during the synthesis. High boiling-point solvents afford sufficient thermal energy to assure the high-quality crystalline nature of NCs, therefore the post-annealing process is obviated. Controlled experiments revealed that OLA-GO triggers heterogeneous nucleation and serves as excellent nuclei anchorage media. The protocol developed here brings one step closer to achieve ``unity in diversity'' on the preparation of nanocrystal-graphene hybrids.Nanocrystal-graphene have been proposed as a new kind of promising hybrid for a wide range of application areas including catalysts, electronics, sensors, biomedicine, and energy storage, etc. Although a variety of methods have been developed for the preparation of hybrids, a facile and general synthetic approach is still highly required. In this study, nanocrystal-graphene hybrids were successfully synthesized in high-boiling-point organic solvents. Graphene oxide (GO) nanosheets were modified by oleylamine (OLA) to form a OLA-GO complex in order to be readily incorporated into hydrophobic synthesis. A rich library of highly crystalline nanocrystals, with types including noble metal, metal oxide, magnetic material and semiconductor were successfully grown on chemically converted graphene (CCG), which is simultaneously reduced from GO during the synthesis. High boiling-point solvents afford sufficient thermal energy to assure the high-quality crystalline nature of NCs, therefore the post-annealing process is obviated. Controlled experiments revealed that OLA-GO triggers heterogeneous nucleation and serves as excellent nuclei anchorage media. The protocol developed here brings one step closer to achieve ``unity in diversity'' on the preparation of nanocrystal-graphene hybrids. Electronic supplementary information (ESI) available: detail of experimental parameters, AFM, FTIR, XRD, XPS spectra, and other TEM images of GO, CCG and NC-CCG. See DOI: 10.1039/c2nr30915g

Pang, Danny Wei-Ping; Yuan, Fang-Wei; Chang, Yan-Cheng; Li, Guo-An; Tuan, Hsing-Yu

2012-07-01

63

Generalized syntheses of nanocrystal-graphene hybrids in high-boiling-point organic solvents.  

PubMed

Nanocrystal-graphene have been proposed as a new kind of promising hybrid for a wide range of application areas including catalysts, electronics, sensors, biomedicine, and energy storage, etc. Although a variety of methods have been developed for the preparation of hybrids, a facile and general synthetic approach is still highly required. In this study, nanocrystal-graphene hybrids were successfully synthesized in high-boiling-point organic solvents. Graphene oxide (GO) nanosheets were modified by oleylamine (OLA) to form a OLA-GO complex in order to be readily incorporated into hydrophobic synthesis. A rich library of highly crystalline nanocrystals, with types including noble metal, metal oxide, magnetic material and semiconductor were successfully grown on chemically converted graphene (CCG), which is simultaneously reduced from GO during the synthesis. High boiling-point solvents afford sufficient thermal energy to assure the high-quality crystalline nature of NCs, therefore the post-annealing process is obviated. Controlled experiments revealed that OLA-GO triggers heterogeneous nucleation and serves as excellent nuclei anchorage media. The protocol developed here brings one step closer to achieve "unity in diversity" on the preparation of nanocrystal-graphene hybrids. PMID:22699842

Pang, Danny Wei-Ping; Yuan, Fang-Wei; Chang, Yan-Cheng; Li, Guo-An; Tuan, Hsing-Yu

2012-06-15

64

Model-based experimental analysis of pool boiling heat transfer with controlled wall temperature transients  

Microsoft Academic Search

A model-based approach for design, control, operation, and evaluation of pool boiling experiments with controlled steady-state and transient wall temperature up to 50 K\\/s is presented. Throughout all phases of the described approach, the requirements on the experimental infrastructure for reproducible boiling experiments are addressed by the integration of theoretical and experimental investigations. In the early design phase, these are

R Hohl; J Blum; M Buchholz; T Lüttich; H Auracher; W Marquardt

2001-01-01

65

Full evaporation headspace gas chromatography for sensitive determination of high boiling point volatile organic compounds in low boiling matrices.  

PubMed

Determination of volatile organic components (VOC's) is often done by static headspace gas chromatography as this technique is very robust and combines easy sample preparation with good selectivity and low detection limits. This technique is used nowadays in different applications which have in common that they have a dirty matrix which would be problematic in direct injection approaches. Headspace by nature favors the most volatile compounds, avoiding the less volatile to reach the injector and column. As a consequence, determination of a high boiling solvent in a lower boiling matrix becomes challenging. Determination of VOCs like: xylenes, cumene, N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N,N-dimethylacetamide (DMA), N-methyl-2-pyrrolidone (NMP), 1,3-dimethyl-2-imidazolidinone (DMI), benzyl alcohol (BA) and anisole in water or water soluble products are an interesting example of the arising problems. In this work, a headspace variant called full evaporation technique is worked out and validated for the mentioned solvents. Detection limits below 0.1?g/vial are reached with RSD values below 10%. Mean recovery values ranged from 92.5 to 110%. The optimized method was applied to determine residual DMSO in a water based cell culture and DMSO and DMA in tetracycline hydrochloride (a water soluble sample). PMID:24103808

Mana Kialengila, Didi; Wolfs, Kris; Bugalama, John; Van Schepdael, Ann; Adams, Erwin

2013-09-19

66

Use of a neural network to determine the normal boiling points of acyclic organic molecules containing heteroatoms  

NASA Astrophysics Data System (ADS)

Models of relationships between structure and boiling point (bp) of 185 acyclic ethers, peroxides, acetals, and their sulfur analogues were constructed by means of a multilayer Neural Network (NN) using the back-propagation algorithm. The ability of a neural network to predict the boiling point of acyclic molecules containing polar atoms is outlined. It also shows the usefulness of the so-called embedding frequencies for the characterization of chemical structures in quantitative structure-property studies. NNs proved to give better results than multiple linear regression and other models in the literature.

Cherqaoui, D.; Villemin, D.; Mesbah, A.; Cense, Jm.; Kvasnicka, V.

1995-04-01

67

Group vector space method for estimating enthalpy of vaporization of organic compounds at the normal boiling point.  

PubMed

The specific position of a group in the molecule has been considered, and a group vector space method for estimating enthalpy of vaporization at the normal boiling point of organic compounds has been developed. Expression for enthalpy of vaporization Delta(vap)H(T(b)) has been established and numerical values of relative group parameters obtained. The average percent deviation of estimation of Delta(vap)H(T(b)) is 1.16, which show that the present method demonstrates significant improvement in applicability to predict the enthalpy of vaporization at the normal boiling point, compared the conventional group methods. PMID:15272851

Wenying, Wei; Jinyu, Han; Wen, Xu

68

Boiling Lake of Dominica, West Indies: High-temperature volcanic crater lake dynamics  

Microsoft Academic Search

The Boiling Lake of Dominica has exhibited stable high-temperature behavior for at least 150 a. This stability is punctuated by occasional crises involving rapid filling and draining of the lake and changes in water temperature. The most recent such crisis occurred in December 2004 to April 2005. Using the results of previous theoretical and experimental work on analogue models, we

N. Fournier; F. Witham; M. Moreau-Fournier; L. Bardou

2009-01-01

69

Droplet impingement dynamics: effect of surface temperature during boiling and non-boiling conditions  

Microsoft Academic Search

This study investigates the hydrodynamic characteristics of droplet impingement on heated surfaces and compares the effect of surface temperature when using water and a nanofluid on a polished and nanostructured surface. Results are obtained for an impact Reynolds number and Weber number of approximately 1700 and 25, respectively. Three discs are used: polished silicon, nanostructured porous silicon and gold-coated polished

Jian Shen; James A. Liburdy; Deborah V. Pence; Vinod Narayanan

2009-01-01

70

Boiling Lake of Dominica, West Indies: High-temperature volcanic crater lake dynamics  

NASA Astrophysics Data System (ADS)

The Boiling Lake of Dominica has exhibited stable high-temperature behavior for at least 150 a. This stability is punctuated by occasional crises involving rapid filling and draining of the lake and changes in water temperature. The most recent such crisis occurred in December 2004 to April 2005. Using the results of previous theoretical and experimental work on analogue models, we present a combined thermal, hydrological, and fluid mechanical model of the Boiling Lake. This reveals that the lake appears to be suspended above the local water table by a constant supply of rising steam bubbles sourced from the boiling of groundwater near an igneous intrusion. The bubbles condense in the Boiling Lake, maintaining the temperature at ˜90°C. The geometry of the lake-conduit system provides a mechanism for instability, with a denser liquid lake overlying a bubbly fractured permeable conduit. Following a sufficiently large perturbation, the whole lake rapidly drains until the surface is at the local water table level. The persistent gas supply then reinitiates filling. We propose that local seismic activity may have caused shock nucleation of bubbles within the conduit and triggered the instability of the Boiling Lake.

Fournier, N.; Witham, F.; Moreau-Fournier, M.; Bardou, L.

2009-02-01

71

Method of and apparatus for determining deposition-point temperature  

DOEpatents

Acoustic-wave sensor apparatus and method for analyzing a normally liquid petroleum-based composition for monitoring deposition-point temperature. The apparatus includes at least one acoustic-wave device such as SAW, QCM, FPM, TSM or APM type devices in contact with the petroleum-based composition for sensing or detecting the surface temperature at which deposition occurs and/or rate of deposition as a function of temperature by sensing an accompanying change in frequency, phase shift, damping voltage or damping current of an electrical oscillator to a known calibrated condition. The acoustic wave device is actively cooled to monitor the deposition of constituents such as paraffins by determining the point at which solids from the liquid composition begin to form on the acoustic wave device. The acoustic wave device can be heated to melt or boil off the deposits to reset the monitor and the process can be repeated.

Mansure, Arthur J. (Albuquerque, NM); Spates, James J. (Albuquerque, NM); Martin, Stephen J. (Albuquerque, NM)

1998-01-01

72

A new method for the estimation of the normal boiling point of non-electrolyte organic compounds  

Microsoft Academic Search

A group contribution method for the estimation of the normal boiling point of non-electrolyte organic compounds was developed using experimental data for approximately 2500 components stored in the Dortmund Data Bank (DDB). Predictions are based exclusively on the molecular structure of the compound. The results of the new method are compared to currently-used methods and are shown to be far

Wilfried Cordes; Jürgen Rarey

2002-01-01

73

Experimental Research on Dryout Point of Flow Boiling in Narrow Annuli  

SciTech Connect

An experimental research on the dryout point of flow boiling in narrow annuli is conducted under low mass flux with 1.5 mm and 1.0 mm gap, respectively. Distilled water is used as work fluid, the range of pressure is from 2.0 to 4.0 MPa and that of mass flux is 26.0{approx}69.0 kg/(m{sup 2}. s). The relation of CHF and critical qualities with mass flux and pressure are revealed. It is found that the critical qualities decrease with the mass flux and increase with the inlet qualities in externally heated annuli. Under the same conditions critical qualities in outer tube are always larger than that in inner tube. KyTaTeLaDe3e's correlations is cited and modified to predict the location of dryout and proved to be not a proper one. Considering in detail the effects of the geometry of annuli and heat flux on dryout, an empirical correction is finally developed to predict dryout point in narrow annuli under low mass flux condition which has a good agreement with experimental data. (authors)

Ge Ping Wu; Sui Zheng Qiu; Guang Hai Su; Dou Nan Jia [Xi'an Jiaotong University, No.28, Xianning West Road, Xi'an, Shaanxi, 710049 (China)

2006-07-01

74

Fuel-temperature coefficient for boiling water reactor transient calculations: Its dependence on reactor conditions  

SciTech Connect

For certain reactivity insertion accidents, the fuel-temperature coefficient (FTC) determines the major component of the feedback reactivity, which limits the peak fuel enthalpy during the transient. Some contributions to the FTC from the two energy groups typically used for boiling water reactor transient analysis and the dependence of the contributions on exposure and coolant void content are discussed.

Kallfelz, J.M.; Belblidia, L.A.; Grimm, P. [Paul Scherrer Inst., Villigen (Switzerland)

1995-10-01

75

Quantitative structure-property relationship study of normal boiling points for halogen-\\/ oxygen-\\/ sulfur-containing organic compounds using the CODESSA program  

Microsoft Academic Search

QSPR (Quantitative Structure-Property Relationship) models for the estimation of boiling points of organic compounds containing halogens, oxygen, or sulfur without hydrogen bonding were established with the CODESSA (Comprehensive Descriptors for Structural and Statistical Analysis) program developed by Katritzky and coworkers. The boiling points of 185 compounds containing oxygen or sulfur can be accurately computed with a MLR (Multi-Linear Regression) equation

Ovidiu Ivanciuc; Teodora Ivanciuc; Alexandru T. Balaban

1998-01-01

76

Children's understanding of changes of state involving the gas state, Part 2: Evaporation and condensation below boiling point  

Microsoft Academic Search

Deriving from a three?year longitudinal study which explored the development of children's concept of a substance (ages 11 to 14), part 2 of this paper (see Johnson 1998b) reports findings in relation to evaporation at room temperature and condensation of atmospheric water vapour. Part one had reported findings in relation to boiling water and the development of pupils’ understanding of

Philip Johnson

1998-01-01

77

Experimental pool boiling investigations of FC72 on silicon with artificial cavities and integrated temperature microsensors  

Microsoft Academic Search

In this experimental study, fluorinert FC-72 is boiled on a silicon chip with artificial cavities and integrated microsensors. The horizontal silicon chip with dimensions of 39.5×19×0.38mm is completely immersed in FC-72. The integrated nickel–titanium temperature microsensors on the back of the chip are calibrated individually and exhibit a near-linear increase of electrical resistance with temperature. The applied heat fluxes and

C. Hutter; D. B. R. Kenning; K. Sefiane; T. G. Karayiannis; H. Lin; G. Cummins; A. J. Walton

2010-01-01

78

Chemical characterization and genotoxic potential related to boiling point for fractionally distilled SRC-I coal liquids  

SciTech Connect

This report summarizes selected research efforts oriented toward ameliorating the genotoxic potential of direct coal liquefaction materials through modification or optimization of process conditions. The studies described were conducted to evaluate the utility of optimized distillation for coal liquids from the SRC-I process. SRC-I process solvent was distilled into 50/sup 0/F-range boiling point (bp) cuts. Analysis of amino-PAH (APAH) showed that mutagenic APAHs containing 3 or more rings were found primarily in fractions boiling above 750/sup 0/F. Three microbial tester strains were used to screen for genetically active agents in the SRC-I distillate bp cuts. Reverse mutation with the Ames tester strain TA98 demonstrated that mutagens were concentrated in the bp cuts boiling above 700/sup 0/F. For this tester strain most of the genetic activity in these distillates was attributable to chemical fractions enriched in APAH having 3 or more rings. Mutagenicity data obtained with TA98 was in good agreement with sk in carcinogenesis results from the mouse-skin initiation/promotion (in vivo) test system. The strongest response in the forward mutation assay did not occur in the most carcinogenically active fractions. Results of initiation/promotion experiments used to measure the relative potency of bp cuts as initiators of mouse skin carcinogenesis again showed that fractions boiling above 750/sup 0/F. Compounds reaching their highest concentrations in the highest boiling and most carcinogenically active cut included known carcinogens such as benzo(a)pyrene and dimethyl benzanthracene. Thus, all biomedical test results indicate that consideration should be given to conducting distillation so as to minimize, in the distillate product, the concentrations of those biologically active compounds found in cuts boiling above 700/sup 0/C.

Wilson, B.W.; Pelroy, R.A.; Mahlum, D.D.

1982-07-01

79

Boiling Heat Transfer in High Temperature Generator of Absorption Chiller/Heater  

NASA Astrophysics Data System (ADS)

Heat transfer performance of forced convective boiling in high temperature generator was experimentally studied using an actual absorption chiller/heater. Measurements were made at six locations, three different levels on a couple of laterally separated lines, for the fluid rising along the rear wall of the high temperature generator furnace. Fluids tested were water and lithium bromide aqueous solution. System pressures were maintained at 96 and 24 kPa, and firing rates were changed from 100 to 40 % of the full load of the machine. Through the experiments, thermodynamic states of both of the fluids were in subcooled region at the lower and middle locations and in saturated region at the upper location. It can be suggested that saturated boiling occurs at comparatively narrow area, located at the upper zone of heat transfer surface of the generator, while forced convective heat transfer and subcooled boiling appear at the remaining broad area. Enhancement of heat transfer due to saturated boiling was not pronounced for lithium bromide aqueous solution than for water.

Furukawa, Masahiro; Enomoto, Eiichi; Sekoguchi, Kotohiko

80

The viscosity and thermal conductivity of pure monatomic gases from their normal boiling point up to 5000 K in the limit of zero density and at 0.101325 MPa  

Microsoft Academic Search

The kinetic theory of gases in the limit of zero density and that of moderately dense gases is used to generate accurate tables of the viscosity and thermal conductivity of the pure monatomic gases for zero density and for a pressure of 0.101325 MPa. The theoretically-based tables cover the temperature range from the normal boiling point of the relevant gas

E. Bich; J. Millat; E. Vogel

1990-01-01

81

Boiling Heat Transfer in High Temperature Generator of Absorption Chiller/Heater  

NASA Astrophysics Data System (ADS)

The heat transfer performance of forced convective boiling was tested using a high temperature generator of absorption chiller/heater, the rear furnace wall of which was composed of two different surfaces; i. e., plain and sprayed heated surfaces. These two surfaces were bisymmetrically set. Wall surface temperatures of both the fire and fluid sides were measured at three locations along the upward flow direction in each heated surface for determining the heat flux and heat transfer coefficient. Nickel-chromium and alumina were employed as the spray materials. The test results show that the sprayed surface can yield a marked elevation in the heat transfer performance due to boiling on the plain surface. Therefore the level of heated surface temperature is largely reduced by means of the spraying surface treatment. This implies that the spraying would much improve a corrosive condition of the heated surface.

Furukawa, Masahiro; Enomoto, Eiichi; Sekoguchi, Kotohiko

82

Experimental investigation of CHF in temperature-controlled transient boiling systems  

SciTech Connect

Experimental analysis on critical heat flux (CHF) in a temperature-controlled natural convective boiling system was examined in this work. The purpose of this study was to investigate the power transient and gap distance effects on CHF in narrow, vertical, rectangular parallel-plate flow. The time rate of the wall temperature (dT{sub w}/dt) was introduced to investigate the power transient effects during the heating and cooling modes. The results show that the transient effect during the heating process is more significant than that during the cooling process, and the CHF values increased as the gap distance increased during the heating process. The results also show that the new parameter, wall temperature rate, should be a good characteristic in transient boiling systems.

Kang, Y.T.; Christensen, R.N.

1994-12-31

83

Rapid thermogravimetric measurements of boiling points and vapor pressure of saturated medium- and long-chain triglycerides  

Microsoft Academic Search

In developing compositional models for biomass-based diesel fuel extenders, volatility properties of medium- and long-chain saturated triglycerides are essential to predict the impact of low levels of these compounds in mixtures with short-chain triglycerides. A thermogravimetric analysis (TGA) method for rapid measurement of boiling points and vapor pressure was used to obtain data for four pure medium- and long-chain triglycerides.

John W. Goodrum; Daniel P. Geller

2002-01-01

84

A Useful System for Microscale and Semi-microscale Fractional Distillation of Air-Sensitive Substances with High Boiling Points  

NASA Astrophysics Data System (ADS)

A procedure to purify air-sensitive liquids with high boiling points is proposed. Attempts to purify those compounds in a conventional short-path distillation apparatus were unsuccessful. The heat required for the vapors to overcome the relatively large vertical distance before reaching the condenser promotes their decomposition. A horizontal distilling apparatus that avoids extreme refluxing and can efficiently separate the fractions of a mixture was designed to purify these kinds of substances.

Alfredo Gutiérrez, J.

2001-05-01

85

QSPR models of boiling point, octanol–water partition coefficient and retention time index of polycyclic aromatic hydrocarbons  

Microsoft Academic Search

A Quantitative Structure–Property Relationship (QSPR) analysis and study of polycyclic aromatic hydrocarbons (PAHs) is presented. Three physicochemical properties related to their environmental impact are studied: boiling point (bp), octanol–water partition coefficient (logKow) and retention time index (RI) for reversed-phase liquid chromatography analysis. The geometry of all PAHs were optimized by the semi-empirical method AM1 and used to calculate thermodynamic, electronic,

Fabiana Alves de Lima Ribeiro; Márcia Miguel Castro Ferreira

2003-01-01

86

A Closer Look at Trends in Boiling Points of Hydrides: Using an Inquiry-Based Approach to Teach Intermolecular Forces of Attraction  

ERIC Educational Resources Information Center

|We describe how we use boiling-point trends of group IV-VII hydrides to introduce intermolecular forces in our first-year general chemistry classes. Starting with the idea that molecules in the liquid state are held together by some kind of force that must be overcome for boiling to take place, students use data analysis and critical reasoning to…

Glazier, Samantha; Marano, Nadia; Eisen, Laura

2010-01-01

87

Boiling critical point in horizontal pipes in a steam-and-water flow  

Microsoft Academic Search

The onset of boiling in a vapor-liquid medium, flowing past a horizontal steamgenerating pipe, is analyzed. The analysis is based on the hydrodynamic nature of the critical transition. An equation for calculating the critical heat flow, correlated with experimental data obtained by the authors for horizontal pipes arranged in a gap and in a bundle, is obtained.

B. S. Fokin; E. N. Goldberg

1983-01-01

88

Investigation on refrigerant R12 critical boiling point in narrow flow pipes considered as model fluid  

Microsoft Academic Search

Experimental investigations on critical heat flow rates in vertical upstream round tubes of small diameter in presence of high mass flow rates and pressures are described. Critical heat flux rates are studied on refrigerant R12 and a thermodynamical model is established, considering the phenomena of limiting quality and upstream boiling. The effects of vapor quality, pipe diameter and length, mass

Thomas Mueller-Menzel

1987-01-01

89

Computing boiling temperatures and vapor pressures in homologous series of perfluorinated oligomers  

NASA Astrophysics Data System (ADS)

Correlation relationships are proposed for computing boiling temperatures of T b oligomers with the general formula R1(CF2) n R2 at normal pressure, where R1 and R2 are arbitrary end groups and the increment of the CF2 fragment is 20.4 K. The dependences of coefficients A and B in the Clausius-Clapeyron equation (ln P = A - B/ T) on the length of the oligomer chain are determined by computing critical temperatures and pressures using an additive scheme.

Kim, I. P.

2013-07-01

90

Boiling temperatures and excess thermodynamic functions of 2-propanol- n-alkyl propanoate solutions  

NASA Astrophysics Data System (ADS)

Boiling temperatures of five binary systems are measured by ebuliometer in the pressure range of 5.333-101.3 kPa. The compositions of equilibrium vapor phases in the systems are calculated using the constructed saturated vapor pressure isotherms as a base. The excess Gibbs energies, excess enthalpies, and excess entropies of solutions are calculated from our data on liquid-vapor equilibria. Regularities in the changes of phase equilibria and thermodynamic properties of solutions with the composition and temperature of the system are established. Vapor-liquid equilibria in the systems are described by the Wilson and NRTL equations.

Suntsov, Yu. K.; Goryunov, V. A.

2012-07-01

91

Water boiling inside carbon nanotubes: toward efficient drug release.  

PubMed

We show using molecular dynamics simulation that spatial confinement of water inside carbon nanotubes (CNTs) substantially increases its boiling temperature and that a small temperature growth above the boiling point dramatically raises the inside pressure. Capillary theory successfully predicts the boiling point elevation down to 2 nm, below which large deviations between the theory and atomistic simulation take place. Water behaves qualitatively different inside narrow CNTs, exhibiting transition into an unusual phase, where pressure is gas-like and grows linearly with temperature, while the diffusion constant is temperature-independent. Precise control over boiling by CNT diameter, together with the rapid growth of inside pressure above the boiling point, suggests a novel drug delivery protocol. Polar drug molecules are packaged inside CNTs; the latter are delivered into living tissues and heated by laser. Solvent boiling facilitates drug release. PMID:21648482

Chaban, Vitaly V; Prezhdo, Oleg V

2011-06-13

92

Remote temperature-set-point controller  

DOEpatents

An instrument for carrying out mechanical strain tests on metallic samples with the addition of an electrical system for varying the temperature with strain, the instrument including opposing arms and associated equipment for holding a sample and varying the mechanical strain on the sample through a plurality of cycles of increasing and decreasing strain within predetermined limits, circuitry for producing an output signal representative of the strain during the tests, apparatus including a set point and a coil about the sample for providing a controlled temperature in the sample, and circuitry interconnected between the strain output signal and set point for varying the temperature of the sample linearly with strain during the tests.

Burke, William F. (Crest Hill, IL); Winiecki, Alan L. (Downers Grove, IL)

1986-01-01

93

Two-dimensional wall temperature measurements and heat transfer enhancement for top-heated horizontal channels with flow boiling  

Microsoft Academic Search

Two-dimensional (circumferential and axial) wall temperature distributions were measured for top-heated coolant channels with internal geometries that include smooth walls, spiral fins and both twisted tape and spiral fins. Freon-71 was the working fluid. The flow regimes studied were single-phase, subcooled flow boiling, and stratified flow boiling. The inside diameter of all test sections was near 10.0 mm. Circumferentially averaged

Ronald D. Boyd; Alvin Smith; Jerry C. Turknett

1995-01-01

94

A simple relationship between the temperature dependence of the density of liquid metals and their boiling temperatures  

Microsoft Academic Search

For elemental metals, other than those in Groups VIII and IIB, there exists a simple rela-tionship between the temperature\\u000a dependence of the liquid density, ? [=(?D\\/?T)p], and the boiling temperature,T\\u000a \\u000a B\\u000a . It is shown that the fractional change in density between 0 K andT\\u000a \\u000a B\\u000a appears to be constant;i .e ., AT\\u000a \\u000a B\\u000a \\u000a \\/d00 =-0.23. D00 is a scale

D. J. Steinberg

1974-01-01

95

Measurement of total acid number (TAN) and TAN boiling point distribution in petroleum products by electrospray ionization mass spectrometry.  

PubMed

We report a new method for rapid measurement of total acid number (TAN) and TAN boiling point (BP) distribution for petroleum crude and products. The technology is based on negative ion electrospray ionization mass spectrometry (ESI-MS) for selective ionization of petroleum acid and quantification of acid structures and molecular weight distributions. A chip-based nanoelectrospray system enables microscale (<200 mg) and higher throughput (20 samples/h) measurement. Naphthenic acid structures were assigned based on nominal masses of a set of predefined acid structures. Stearic acid is used as an internal standard to calibrate ESI-MS response factors for quantification purposes. With the use of structure-property correlations, boiling point distributions of TAN values can be calculated from the composition. The rapid measurement of TAN BP distributions by ESI is demonstrated for a series of high-TAN crudes and distillation cuts. TAN values determined by the technique agree well with those by the titration method. The distributed properties compare favorably with those measured by distillation and measurement of TAN of corresponding cuts. PMID:18179248

Qian, Kuangnan; Edwards, Kathleen E; Dechert, Gary J; Jaffe, Stephen B; Green, Larry A; Olmstead, William N

2008-01-08

96

Measurement of thermodynamic temperature of high temperature fixed points  

NASA Astrophysics Data System (ADS)

The paper is devoted to VNIIOFI's measurements of thermodynamic temperature of the high temperature fixed points Co-C, Pt-C and Re-C within the scope of the international project coordinated by the Consultative Committee for Thermometry working group 5 "Radiation Thermometry". The melting temperatures of the fixed points were measured by a radiance mode radiation thermometer calibrated against a filter radiometer with known irradiance spectral responsivity via a high temperature black body. This paper describes the facility used for the measurements, the results and estimated uncertainties.

Gavrilov, V. R.; Khlevnoy, B. B.; Otryaskin, D. A.; Grigorieva, I. A.; Samoylov, M. L.; Sapritsky, V. I.

2013-09-01

97

Performance of Temperature/Dew Point Instruments.  

National Technical Information Service (NTIS)

A series of field trials was conducted to assess the performance of temperature/dew point systems used at the US Army Dugway Proving ground, UT. Data quality was degraded by noise, calibration drift, and exposure to adverse ambient conditions. Improved no...

C. Biltoft

1982-01-01

98

Boiling temperature as a scaling parameter for the microscopic relaxation dynamics in molecular liquids.  

PubMed

At sufficiently high temperatures, the center-of-mass microscopic diffusion dynamics of liquids is characterized by a single component, often with weak temperature dependence. In this regime, the effective cage made by the neighbor particles cannot be sustained and readily breaks down, enabling long-range diffusion. As the temperature is decreased, the cage relaxation becomes impeded, leading to a higher viscosity with more pronounced temperature dependence. On the microscopic scale, the sustained caging effect leads to a separation between a faster in-cage relaxation component and a slower cage-breaking relaxation component. The evidence for the separate dynamic components, as opposed to a single stretched component, is provided by quasielastic neutron scattering experiments. We use a simple method to evaluate the extent of the dynamic components separation as a function of temperature in a group of related aromatic molecular liquids. We find that, regardless of the glass-forming capabilities or lack thereof, progressively more pronounced separation between the in-cage and cage-breaking dynamic components develops on cooling down as the ratio of Tb/T, where Tb is the boiling temperature, increases. This reflects the microscopic mechanism behind the empirical rule for the glass forming capability based on the ratio of boiling and melting temperatures, Tb/Tm. When a liquid's Tb/Tm happens to be high, the liquid can readily be supercooled below its Tm because the liquid's microscopic relaxation dynamics is already impeded at Tm, as evidenced by a sustained caging effect manifested through the separation of the in-cage and cage-breaking dynamic components. Our findings suggest certain universality in the temperature dependence of the microscopic diffusion dynamics in molecular liquids, regardless of their glass-forming capabilities. Unless the insufficiently low (with respect to Tb) melting temperature, Tm, intervenes and makes crystallization thermodynamically favorable when cage-breaking is still unimpeded and the structural relaxation is fast, the liquid is likely to become supercooled. The propensity to supercooling and eventually forming a glass is thus determined by a purely thermodynamic factor, Tb/Tm. PMID:23869489

Mamontov, Eugene

2013-08-02

99

Fundamental study of FC-72 pool boiling surface temperature fluctuations and bubble behavior  

NASA Astrophysics Data System (ADS)

A heater designed to monitor surface temperature fluctuations during pool boiling experiments while the bubbles were simultaneously being observed has been fabricated and tested. The heat source was a transparent indium tin oxide (ITO) layer commercially deposited on a fused quartz substrate. Four copper-nickel thin film thermocouples (TFTCs) on the heater surface measured the surface temperature, while a thin layer of sapphire or fused silica provided electrical insulation between the TFTCs and the ITO. The TFTCs were micro-fabricated using the liftoff process to deposit the nickel and copper metal films. The TFTC elements were 50 mum wide and overlapped to form a 25 mum by 25 mum junction. TFTC voltages were recorded by a DAQ at a sampling rate of 50 kHz. A high-speed CCD camera recorded bubble images from below the heater at 2000 frames/second. A trigger sent to the camera by the DAQ synchronized the bubble images and the surface temperature data. As the bubbles and their contact rings grew over the TFTC junction, correlations between bubble behavior and surface temperature changes were demonstrated. On the heaters with fused silica insulation layers, 1--2°C temperature drops on the order of 1 ms occurred as the contact ring moved over the TFTC junction during bubble growth and as the contact ring moved back over the TFTC junction during bubble departure. These temperature drops during bubble growth and departure were due to microlayer evaporation and liquid rewetting the heated surface, respectively. Microlayer evaporation was not distinguished as the primary method of heat removal from the surface. Heaters with sapphire insulation layers did not display the measurable temperature drops observed with the fused silica heaters. The large thermal diffusivity of the sapphire compared to the fused silica was determined as the reason for the absence of these temperature drops. These findings were confirmed by a comparison of temperature drops in a 2-D simulation of a bubble growing over the TFTC junction on both the sapphire and fused silica heater surfaces. When the fused silica heater produced a temperature drop of 1.4°C, the sapphire heater produced a drop of only 0.04°C under the same conditions. These results verified that the lack of temperature drops present in the sapphire data was due to the thermal properties of the sapphire layer. By observing the bubble departure frequency and site density on the heater, as well as the bubble departure diameter, the contribution of nucleate boiling to the overall heat removal from the surface could be calculated. These results showed that bubble vapor generation contributed to approximately 10% at 1 W/cm2, 23% at 1.75 W/cm2, and 35% at 2.9 W/cm 2 of the heat removed from a fused silica heater. Bubble growth and contact ring growth were observed and measured from images obtained with the high-speed camera. Bubble data recorded on a fused silica heater at 3 W/cm2, 4 W/cm2, and 5 W/cm 2 showed that bubble departure diameter and lifetime were negligibly affected by the increase in heat flux. Bubble and contact ring growth rates demonstrated significant differences when compared on the fused silica and sapphire heaters at 3 W/cm2. The bubble departure diameters were smaller, the bubble lifetimes were longer, and the bubble departure frequency was larger on the sapphire heater, while microlayer evaporation was faster on the fused silica heater. Additional considerations revealed that these differences may be due to surface conditions as well as differing thermal properties. Nucleate boiling curves were recorded on the fused silica and sapphire heaters by adjusting the heat flux input and monitoring the local surface temperature with the TFTCs. The resulting curves showed a temperature drop at the onset of nucleate boiling due to the increase in heat transfer coefficient associated with bubble nucleation. One of the TFTC locations on the sapphire heater frequently experienced a second temperature drop at a higher heat flux. When the heat flux was started from 1 W/cm2 instead of zer

Griffin, Alison R.

100

Phase Separation, Density Fluctuations, and Boiling Near the Liquid-Gas Critical Point  

Microsoft Academic Search

A pure liquid-gas mixture is one of the simplest examples of a soft-matter system. In fact, when co-existing gas and liquid phases of pure fluid are heated to their critical point, large-scale density fluctuations make the fluid extremely compressible (to external forces), expandable (to heating), slows the diffusive transport, and decreases the surface tension. In principle these properties and others

John Hegseth; Ana Oprisan; Arun Roy; Vadim Nikolayev; Daniel Beysens; Yves Garrabos; Carole Lecoutre-Chabot

2002-01-01

101

Further Analysis of Boiling Points of Small Molecules, CH[subscript w]F[subscript x]Cl[subscript y]Br[subscript z  

ERIC Educational Resources Information Center

|A study to present specific hypothesis that satisfactorily explain the boiling point of a number of molecules, CH[subscript w]F[subscript x]Cl[subscript y]Br[subscript z] having similar structure, and then analyze the model with the help of multiple linear regression (MLR), a data analysis tool. The MLR analysis was useful in selecting the…

Beauchamp, Guy

2005-01-01

102

Further Analysis of Boiling Points of Small Molecules, CH[subscript w]F[subscript x]Cl[subscript y]Br[subscript z  

ERIC Educational Resources Information Center

A study to present specific hypothesis that satisfactorily explain the boiling point of a number of molecules, CH[subscript w]F[subscript x]Cl[subscript y]Br[subscript z] having similar structure, and then analyze the model with the help of multiple linear regression (MLR), a data analysis tool. The MLR analysis was useful in selecting the…

Beauchamp, Guy

2005-01-01

103

Proteins from hyperthermophiles: Stability and enzymatic catalysis close to the boiling point of water  

Microsoft Academic Search

It has become clear since about a decade ago, that the biosphere contains a variety of microorganisms that can live and grow\\u000a in extreme environments. Hyperthermophilic microorganisms, present among Archaea and Bacteria, proliferate at temperatures\\u000a of around 80–100C. The majority of the genera known to date are of marine origin, however, some of them have been found in\\u000a continental hot

Rudolf Ladenstein; Garabed Antranikian

104

Characterization of the TIP4PEw water model: Vapor pressure and boiling point  

Microsoft Academic Search

The liquid-vapor-phase equilibrium properties of the previously developed TIP4P-Ew water model have been studied using thermodynamic integration free-energy simulation techniques in the temperature range of 274–400 K. We stress that free-energy results from simulations need to be corrected in order to be compared to the experiment. This is due to the fact that the thermodynamic end states accessible through simulations

Hans W. Horn; William C. Swope; Jed W. Pitera

2005-01-01

105

Characterization of the TIP4PEw water model: Vapor pressure and boiling point  

Microsoft Academic Search

The liquid-vapor-phase equilibrium properties of the previously developed TIP4P-Ew water model have been studied using thermodynamic integration free-energy simulation techniques in the temperature range of 274-400 K. We stress that free-energy results from simulations need to be corrected in order to be compared to the experiment. This is due to the fact that the thermodynamic end states accessible through simulations

Hans W. Horn; William C. Swope; Jed W. Pitera

2005-01-01

106

Process for upgrading high-boiling hydrocarbonaceous materials  

Microsoft Academic Search

This patent describes a process for upgrading a hydrocarbonaceous material having an initial boiling point at atmospheric pressure of at least about 625° F. to a product having a lower boiling point than the initial boiling point of the hydrocarbonaceous material and\\/or a higher boiling point than the final boiling point of the hydrocarbonaceous material. It comprises: heating a mixture

S. C. Paspek; J. B. Hauser; C. P. Eppig; H. A. Adams

1991-01-01

107

High flux film and transition boiling  

NASA Astrophysics Data System (ADS)

An investigation was conducted on the potential for altering the boiling curve through effects of high velocity and high subcooling. Experiments using water and Freon-113 flowing over cylindrical electrical heaters in crossflow were made to see how velocity and subcooling affect the boiling curve, especially the film and transition boiling regions. We sought subcooling levels down to near the freezing points of these two liquids to prove the concept that the critical heat flux and the minimum heat flux could be brought together, thereby averting the transition region altogether. Another emphasis was to gain insight into how the various boiling regions could be represented mathematically on various parts of the heating surface. Motivation for the research grew out of a realization that the effects of very high subcooling and velocity might be to avert the transition boiling altogether so that the unstable part of the boiling curve would not limit the application of high flux devices to temperatures less than the burnout temperatures. Summaries of results from the study are described. It shows that the potential for averting the transition region is good and points the way to further research that is needed to demonstrate the potential.

Witte, L. C.

1993-02-01

108

Boiling radial flow in fractures of varying wall porosity  

SciTech Connect

The focus of this report is the coupling of conductive heat transfer and boiling convective heat transfer, with boiling flow in a rock fracture. A series of experiments observed differences in boiling regimes and behavior, and attempted to quantify a boiling convection coefficient. The experimental study involved boiling radial flow in a simulated fracture, bounded by a variety of materials. Nonporous and impermeable aluminum, highly porous and permeable Berea sandstone, and minimally porous and permeable graywacke from The Geysers geothermal field. On nonporous surfaces, the heat flux was not strongly coupled to injection rate into the fracture. However, for porous surfaces, heat flux, and associated values of excess temperature and a boiling convection coefficient exhibited variation with injection rate. Nucleation was shown to occur not upon the visible surface of porous materials, but a distance below the surface, within the matrix. The depth of boiling was a function of injection rate, thermal power supplied to the fracture, and the porosity and permeability of the rock. Although matrix boiling beyond fracture wall may apply only to a finite radius around the point of injection, higher values of heat flux and a boiling convection coefficient may be realized with boiling in a porous, rather than nonporous surface bounded fracture.

Barnitt, Robb Allan

2000-06-01

109

Investigation of flow boiling in narrow channels by thermographic measurement of local wall temperatures  

Microsoft Academic Search

Flow boiling heat transfer characteristics of water and hydrocarbons in mini and microchannels are experimentally studied.\\u000a Two different test section geometries are employed; a circular channel with a hydraulic diameter of 1,500 ?m, and rectangular\\u000a channels with height values of 300–700 ?m and a width of 10 mm. In both facilities, the fluid flows upwards and the test sections,\\u000a made of the nickel

M. Cortina Díaz; H. Boye; I. Hapke; J. Schmidt; Y. Staate; Z. Zhekov

2006-01-01

110

New protocol for the realization of the triple points of cryogenic gases as temperature fixed points  

NASA Astrophysics Data System (ADS)

An improved protocol or measurement program is presented for the realization of the triple points of cryogenic gases as temperature fixed points. The protocol contains general recommendations in different directions: determination of the thermal parameters of the fixed-point cells containing the samples and of the apparatus, measurement conditions, series of measurements, reporting of data, establishment of an uncertainty budget, especially the reliable estimation of static and dynamic temperature-measurement errors. Such a detailed protocol is necessary for reaching the highest metrological level due to the special properties of the cryogenic gases as fixed-point substances. Considering the newest developments, the state-of-the-art level of the realization of the low-temperature fixed points is described.

Fellmuth, B.

2013-09-01

111

Simultaneous Occurrence of High Temperatures and High Dew Points.  

National Technical Information Service (NTIS)

Available information on the joint occurrence of high temperatures and dew points are presented for 17 stations (7 in Asia, 7 in Africa, 2 in North America, and 1 in Australia) in order that the geographical distribution of high temperatures and associate...

A. V. Dodd

1966-01-01

112

Leaching process of nuclear fuel in leaching solution at sub-boiling temperature.  

National Technical Information Service (NTIS)

Effects of the leaching temperature and concentration of the nitric acid on the solubility of nuclear fuel have been investigated. Fuels were fed into the solution in simulation of continuous and batch mode and the effects of leaching temperature, nitric ...

Q. Zhang Y. Chen Y. Liao S. Sun C. Zhang

1990-01-01

113

Ultra-deep desulfurization of coker and straight-run gas oils: Effect of lowering feedstock 95% boiling point  

Microsoft Academic Search

Production of diesel fuels with ultra-low-sulfur levels by deep desulfurization of gas oil feeds has received considerable importance in the petroleum refineries in recent years. The type of the gas oil feed and its distillation temperature play a key role in the deep desulfurization process. In the present research project, the effect of lowering the 95% distillation temperature (T95) of

A. Al-Barood; A. Stanislaus

2007-01-01

114

ENERGY CONSERVATION THROUGH POINT SOURCE RECYCLE WITH HIGH TEMPERATURE HYPERFILTRATION  

EPA Science Inventory

The report gives results of a study of energy conservation effects of point source recycle with high-temperature hyperfiltration (HF) in the textile industry. (HF and ultrafiltration (UF) are pressure-driven membrane processes which have potential for recycle of water, energy, an...

115

Separation of low boiling constituents from a mixed gas  

SciTech Connect

Lower boiling constituents are separated from a normally gaseous feed mixture predominating in higher boiling constituents and containing significant amounts of such lower boiling constituents and having a first pressure substantially above atmospheric pressure and a first temperature substantially below atmospheric temperature and at which first pressure and first temperature. Feed mixture includes both vapor and liquid phases, including introducing at least a portion of the vapor of the feed mixture representing a second vapor phase into a separation contacting zone adjacent the top thereof at a second pressure substantially lower than the first pressure and a second temperature substantially lower than the first temperature and introducing at least a portion of the liquid of the feed mixture representing a second liquid phase into the separation-contacting zone at a lower intermediate point at a third pressure and a third temperature approximately equal to the first pressure and the first temperature, respectively. The second pressure thus being substantially lower than the third pressure and the second temperature thus being substantially lower than the third temperature, separating the second vapor phase and the second liquid phase in the separation-contacting zone to produce a third vapor phase substantially enriched in the higher boiling constituents and a third liquid phase substantially enriched in the lower boiling constituents, introducing the third vapor phase into a fractional distillation zone adjacent the top thereof and introducing the third liquid phase into the fractional distillation zone at an upper intermediate point, fractionally distilling the third vapor phase and the third liquid phase to produce a fourth vapor phase substantially enriched in the higher boiling constituents.

Perez, E.P.

1984-06-26

116

Twelve years of high temperature fixed point research: A review  

NASA Astrophysics Data System (ADS)

A review of research into high temperature fixed points (HTFPs), since their inception at NMIJ in 1999 until 2011 is given. HTFPs discussed in this paper are those whose transition temperatures are above the freezing point of copper and based on eutectic/peritectic alloys. The paper will begin with an historical overview; including a description of the different types of modern HTFPs. The evolution of construction methods of HTFPs will be elaborated. The performance of the current generation of HTFPs will be compared to that of earlier ones. Current uses of HTFPs will be described. Finally an overview of some remaining research issues will be given including assignment of definitive thermodynamic temperatures and inclusion into the developing mise en pratique for the definition of the kelvin.

Machin, G.

2013-09-01

117

Spotlighting quantum critical points via quantum correlations at finite temperatures  

SciTech Connect

We extend the program initiated by T. Werlang et al. [Phys. Rev. Lett. 105, 095702 (2010)] in several directions. Firstly, we investigate how useful quantum correlations, such as entanglement and quantum discord, are in the detection of critical points of quantum phase transitions when the system is at finite temperatures. For that purpose we study several thermalized spin models in the thermodynamic limit, namely, the XXZ model, the XY model, and the Ising model, all of which with an external magnetic field. We compare the ability of quantum discord, entanglement, and some thermodynamic quantities to spotlight the quantum critical points for several different temperatures. Secondly, for some models we go beyond nearest neighbors and also study the behavior of entanglement and quantum discord for second nearest neighbors around the critical point at finite temperature. Finally, we furnish a more quantitative description of how good all these quantities are in spotlighting critical points of quantum phase transitions at finite T, bridging the gap between experimental data and those theoretical descriptions solely based on the unattainable absolute zero assumption.

Werlang, T.; Ribeiro, G. A. P.; Rigolin, Gustavo [Departamento de Fisica, Universidade Federal de Sao Carlos, Sao Carlos, SP 13565-905 (Brazil)

2011-06-15

118

An International Star Intercomparison of Low-Temperature Fixed Points Using Sealed Triple-Point Cells  

NASA Astrophysics Data System (ADS)

An overview of the main results of an international star intercomparison of low-temperature fixed points is given. Between 1997 and 2002, 52 sealed triple-point cells (STPCs) of the thirteen laboratories represented by the authors have been investigated at PTB. The STPCs are used to realise the triple points of hydrogen, neon, oxygen, and argon, respectively, as defining fixed points of the International Temperature Scale of 1990, ITS-90. The melting curves of all STPCs have been measured on the same experimental equipment, adhering strictly to a single measurement program. This protocol enables separation of the effects influencing the melting curves and direct comparison of the thermal behaviour of the STPCs, which are quite different with respect to design, age, gas source, and filling technology. In the paper, emphasis is given to the typical properties of the four fixed-point substances and to the spread of the STPC parameters. Connections between the star intercomparison and completed and on-going international activities, including the CIPM Key Comparisons, are also discussed.

Fellmuth, B.; Berger, D.; Wolber, L.; de Groot, M.; Head, D.; Hermier, Y.; Mao, Y. Z.; Nakano, T.; Pavese, F.; Shkraba, V.; Steele, A. G.; Steur, P. P. M.; Szmyrka-Grzebyk, A.; Tew, W. L.; Wang, L.; White, D. R.

2003-09-01

119

EFFECTS OF DISSOLVED NITROGEN ON SUBCOOLED NUCLEATE BOILING IN SANTOWAX  

Microsoft Academic Search

Ten heat transfer tests were made using Santowax R coolant samples, ; eight being continued to the burnout point. Tests were made at pressures of 90 ; and 150 psia and bulk coolant temperatures ranging between 500 and 650 deg F. ; Tests were made with both vertical and horizontal heaters. Results showed that: ; the onset of nucleate boiling

1961-01-01

120

Boiling limits in heat pipes with annular gap wick structures  

NASA Astrophysics Data System (ADS)

An analytical model has been written for predicting boiling limits in heat pipes with annular gap wick structures, both with centered and offset annuli. In the model, the liquid pressure and temperature at the evaporator stagnation point are determined, based on heat pipe hydrodynamic pressure drop correlations and radial temperature profiles corresponding to the heat flux. The model is described and compared with experimental data from boiling limit experiments performed with a K/Nb-1 percent Zr (working fluid/wick and tube material) heat pipe and a Na/SST heat pipe. The experimental data correlated well with the model for nucleation site size of 3 microns for both heat pipes.

Woloshun, K. A.; Sena, J. T.; Keddy, E. K.; Merrigan, M. A.

1990-06-01

121

Thermodynamic temperature measurements of silver freezing point and HTFPs  

NASA Astrophysics Data System (ADS)

The hybrid method, by introducing a lens to the irradiance method, was adopted to measure the thermodynamic temperature at NIM. An absolute radiation thermometer was established with two alternative filter radiometers (633nm and 900nm). The parameters of the absolute radiation thermometer were calibrated. The thermodynamic temperatures of the silver fixed point and Co-C, Pt-C, Re-C were determined. The uncertainties were 0.24K to 0.94K for FR633 and 0.34K to 1.6K for FR900 from the silver point to Re-C. The results were compared with the ITS-90 values and show a good agreement: 0.18K at Co-C, -0.11K at Pt-C and -0.24K at Re-C, which are under the estimated uncertainties.

Yuan, Z.; Lu, X.; Hao, X.; Dong, W.; Wang, T.; Lin, Y.; Wang, J.; Duan, Y.

2013-09-01

122

Generation of standard gas mixtures of halogenated, aliphatic, and aromatic compounds and prediction of the individual output rates based on molecular formula and boiling point.  

PubMed

In this work, we describe a simple diffusion capillary device for the generation of various organic test gases. Using a set of basic equations the output rate of the test gas devices can easily be predicted only based on the molecular formula and the boiling point of the compounds of interest. Since these parameters are easily accessible for a large number of potential analytes, even for those compounds which are typically not listed in physico-chemical handbooks or internet databases, the adjustment of the test gas source to the concentration range required for the individual analytical application is straightforward. The agreement of the predicted and measured values is shown to be valid for different groups of chemicals, such as halocarbons, alkanes, alkenes, and aromatic compounds and for different dimensions of the diffusion capillaries. The limits of the predictability of the output rates are explored and observed to result in an underprediction of the output rates when very thin capillaries are used. It is demonstrated that pressure variations are responsible for the observed deviation of the output rates. To overcome the influence of pressure variations and at the same time to establish a suitable test gas source for highly volatile compounds, also the usability of permeation sources is explored, for example for the generation of molecular bromine test gases. PMID:22739814

Thorenz, Ute R; Kundel, Michael; Müller, Lars; Hoffmann, Thorsten

2012-06-29

123

Characteristics of Transient Boiling Heat Transfer  

SciTech Connect

In this paper, one dimensional inverse heat conduction solution is used for a measurement of pool boiling curve. The experiments are performed under atmospheric pressure for copper, brass, carbon steel and gold. Boiling curves, including unsteady transition boiling region, are found can be traced fairly well from a simple experiment system by solving inverse heat conduction solution. Boiling curves for steady heating and transient heating, for heating process and cooling process are compared. Surface behavior around CHF point, transition boiling and film-boiling regions are observed by using a high-speed camera. The results show the practicability of the inverse heat conduction solution in tracing boiling curve and thereby supply us a new way in boiling heat transfer research. (authors)

Liu, Wei; Monde, Masanori; Mitsutake, Y. [Saga University, 1 Honjo Saga City, Saga 840-8502 (Japan)

2002-07-01

124

The succinonitrile triple-point standard: a fixed point to improve the accuracy of temperature measurements in the clinical laboratory.  

PubMed

In an investigation of the melting and freezing behavior of succinonitrile, the triple-point temperature was determined to be 58.0805 degrees C, with an estimated uncertainty of +/- 0.0015 degrees C relative to the International Practical Temperature Scale of 1968 (IPTS-68). The triple-point temperature of this material is evaluated as a temperature-fixed point, and some clinical laboratory applications of this fixed point are proposed. In conjunction with the gallium and ice points, the availability of succinonitrile permits thermistor thermometers to be calibrated accurately and easily on the IPTS-68. PMID:6861344

Mangum, B W

1983-07-01

125

High temperature antenna pointing mechanism for BepiColombo mission  

NASA Astrophysics Data System (ADS)

This paper describes the two axis Antenna Pointing Mechanism (APM) with dual frequency (X-Ka bands) Rotary Joint (RJ) developed by Kongsberg Defence and Aerospace and BAE Systems, in the frame of the ESA BepiColombo mission to the planet Mercury. The extreme environmental conditions induced by Mercury's proximity to the Sun (up to 14.500 W/m2 direct solar fluxes, up to 5000 W/m2 infrared flux and up to 1200 W/m2 albedo shine form the planet surface), have dictated the need for a specific high temperature development of the pointing mechanism and of its integrated RF Rotary Joint. Global thermal analysis of the antenna predicts qualification temperature for the elevation stage APM between 250°C and 295°C. In addition, the mechanism shall survive extreme cold temperatures during the interplanetary cruise phase. Beside the harsh environment, the stringent pointing accuracy required by the antenna high frequency operations, and the extreme dimensional stability demanded by a radio science experiment (which is using the antenna for range and range rate measurements), have introduced additional, specific challenges to the mechanism design. Innovative solutions have been deemed necessary at system architecture level, in the design of the mechanisms critical areas and in the selection of high temperature compatible materials and processes. The very high working temperature of the mechanism ruled out use of aluminium alloys, which is replaced by Titanium alloy and stainless steels. Special heat treatments of the steel are applied for minimum loss of hardness. The structures are optimised for minimum mass. To handle thermal stresses and distortion, a very compact design of the APM was performed integrating the bearings, position sensor and drive chain within minimum structural length. The Rotary Joint is a unique design tailored to the APM using a common main bearing support. Special manufacturing processes have been tested and applied for manufacture of the very compact RJ being the first of its kind (dual X-Ka band) in European space development. The twin channels are arranged concentrically, permitting continuous 360° rotation. Maximum use of waveguide has been made to minimise the loss in the Ka-band frequency channel and this leads to an unconventional design of the X-band channel. A specific effort and extensive test program at ESTL in the UK have been put in place to identify suitable high temperature solutions for the RJ and APM bearings lubrication. The high temperature demands the use of a dry lubrication system. High working loads due to thermal stresses puts extra challenge to the life duration of the dry film lubrication. Lead lubrication was initially the preferred concept, but has later in the program been substituted by MoS2 film. A design life of 20,000 cycles at 250°C and elevated load has been demonstrated for the bearings with MoS2. Special attention has been paid to the materials in the stepper motor using high temperature solder material and MoS2 dry lubrication in the bearings and gear train. The APM is designed for use of a high accuracy inductive based position sensor with remote signal and amplifier electronics. Electrical signal transfer is via a high temperature Twist Capsule. The activity has included the design, manufacturing and testing in a respresentative environment of a breadboard model of the APM and of its integrated radio frequency RJ. The breadboard does not include a position sensor or the Twist Capsule. The breadboard tests will include functional performance tests in air, vibration tests and thermal vacuum. The thermal vacuum test will include RF testing at high temperature combined with APM pointing performance.

Mürer, Johan A.; Harper, Richard; Anderson, Mike

2005-07-01

126

Temperature modulation of the transmission barrier in quantum point contacts  

NASA Astrophysics Data System (ADS)

We investigate near-equilibrium ballistic transport through a quantum point contact (QPC) along a GaAs/AlGaAs heterojunction with a transfer matrix technique as a function of temperature and the shape of the potential barrier in the QPC. Our analysis is based on a three-dimensional (3D) quantum-mechanical variational model within the Hartree-Fock approximation that takes into account the vertical depletion potential from ionized acceptors in GaAs and the gate-induced transverse confinement potential that reduce to an effective slowly varying one-dimensional (1D) potential along the narrow constriction. The calculated zero-temperature transmission exhibits a shoulder ranging from 0.3 to 0.6 depending on the length of the QPC and the profile of the barrier potential. The effect is a consequence of the compressibility peak in the 1D electron gas and is enhanced for antiferromagnetic interaction among electrons in the QPC, but is smeared out once temperature is increased by a few tenths of a Kelvin.

Sánchez, Alfredo X.; Leburton, Jean-Pierre

2013-08-01

127

The temperature dependence of mercury saturated vapor pressure over the whole range of its liquid state  

NASA Astrophysics Data System (ADS)

The Boltzmann distribution with normalization with respect to the boiling point was used to calculate the temperature dependence of vapor pressure, which included the temperature and heat of boiling only. A refined equation of mercury vaporizability with mutually consistent characteristics such as vapor pressure and the temperature and heat of boiling was obtained. The equation correctly described this dependence over the whole liquid state range, including the critical point.

Turdukozhaeva, A. M.

2012-04-01

128

Construction of high-temperature fixed-point cells for thermodynamic temperature assignment  

NASA Astrophysics Data System (ADS)

A multi-partner project is currently being conducted within Working Group 5 (Radiation thermometry) of the CIPM Consultative Committee for Thermometry (CCT), which aims at assigning thermodynamic temperatures to a selected set of high-temperature fixed-points (HTFPs) based on metal-carbon eutectics. A work package of this project (WP2) consists in producing sets of HTFP cells to serve the final phase of the project, assignment of definitive thermodynamic temperatures (WP5). The four fixed-point types are the metal-carbon eutectic points, Re-C (2474 °C), Pt-C (1739 °C), and Co-C (1324 °C), and the Cu point (1084.62 °C). The first phase of the WP2 work treats the construction of HTFP cells, which were carried out by eight National Metrology Institutes (NMIs). The cells were constructed in accordance to instructions laid out in the WP protocol, based on years of experience of WG5 member NMIs. Cells constructed in this way should, in principle, have the required performance in terms of the realized temperature, reproducibility, and long term stability. The constructed cells were then evaluated for their performance in the second phase of the WP. The WP aims at identifying at least four cells of each of the four fixed-point types to be supplied to WP5 of the CCT-WG5 research plan for final thermodynamic temperature assignment. This paper describes the first phase of the WP2. Details of the cell construction conditions and procedures are presented.

Yamada, Y.; Anhalt, K.; Battuello, M.; Bloembergen, P.; Khlevnoy, B.; Machin, G.; Matveyev, M.; Sadli, M.; Wang, T.

2013-09-01

129

Boiling liquid level sensor. [Differential cooling of bridge current heated wire  

Microsoft Academic Search

Differential cooling of a bridge current heated wire is used to sense a liquid-gas interface level. Liquid and gas temperatures should be approximately equal if the highest accuracy is required making the device particularly useful for sensing the level of electrically nonconducting liquids at their boiling points. Operating temperatures are restricted only by the requirement that the sensor wire material

Watt

1976-01-01

130

Experimental Study of Heat Transfer from Stainless Steel Foil in He II during Film Boiling State  

SciTech Connect

He II film boiling is of both academic and applied interests. However, the information about film boiling heat transfer in He II is still insufficient and needs further investigation. In the present study, a thin stainless steel foil heater (10 {mu} m thick) is used to cause boiling in He II. The heater temperature is measured to evaluate the heat transfer performance of He II film boiling under different thermal conditions. The pressure and the heater surface temperature oscillations induced by the film boiling are also simultaneously measured. The heat transfer coefficients of three kinds of boiling states: noisy film boiling, transition boiling and silent film boiling, are obtained in the present study.

Zhang, P. [Institute of Engineering Mechanics and Systems, University of Tsukuba, Tsukuba, 305-8573 (Japan); Institute of Refrigeration and Cryogenics, Shanghai Jiao Tong University, Shanghai, 200030 (China); Murakami, M. [Institute of Engineering Mechanics and Systems, University of Tsukuba, Tsukuba, 305-8573 (Japan)

2004-06-23

131

Investigation of low-temperature fixed points by an international star intercomparison of sealed triple-point cells  

NASA Astrophysics Data System (ADS)

An overview of the results of an international star intercomparison of low-temperature fixed points is given. Between 1997 and 2005, 68 sealed triple-point cells (STPCs) of the twelve laboratories represented by the authors were investigated at PTB. The STPCs are used to realize the triple points of hydrogen, neon, oxygen and argon as defining fixed points of the International Temperature Scale of 1990, ITS-90. The melting curves (MCs) of all STPCs have been measured on the same experimental equipment, adhering strictly to a single measurement program. This protocol enables separation of the effects influencing the MCs and direct comparison of the thermal behaviour of the STPCs, which are quite different with respect to design, age, gas source and filling technology. In the paper, special emphasis is given to the spread of the liquidus-point temperatures and to the uncertainty of their determination. Connections between the star intercomparison and completed and ongoing international activities are also discussed.

Fellmuth, B.; Wolber, L.; Head, D. I.; Hermier, Y.; Hill, K. D.; Nakano, T.; Pavese, F.; Peruzzi, A.; Rusby, R. L.; Shkraba, V.; Steele, A. G.; Steur, P. P. M.; Szmyrka-Grzebyk, A.; Tew, W. L.; Wang, L.; White, D. R.

2012-06-01

132

Experimental studies on the enhanced flow boiling heat transfer and pressure drop of organic fluid with high saturation temperature in vertical porous coated tube  

NASA Astrophysics Data System (ADS)

The characteristics of flow boiling heat transfer and pressure drop of organic fluid with high saturation temperature in a vertical porous coated tube are experimentally studied in this paper. The experiments are performed at evaporation pressure of 0.16-0.31MPa, mass flux of 390-790kg/m2s, and vapor quality of 0.06-0.58. The variations of heat transfer coefficient and pressure drop with vapor quality are measured and compared to the results of smooth tube. Boiling curves are generated at mass flux of 482 and 675kg/m2s. The experimental results indicate that the heat transfer coefficients of the porous tube are 1.8-3.5 times those of smooth tube, and that the frictional pressure drops of the porous tube are 1.1-2.9 times those of smooth tube. The correlations for heat transfer coefficient and frictional pressure drop are derived, in which the effect of fluid molecular weight is included. The experiments show that significant heat transfer enhancement is accompanied by a little pressure drop penalty, the application of the porous coated tube is promising in the process industries.

Yang, Dong; Shen, Zhi; Chen, Tingkuan; Zhou, Chenn Q.

2013-07-01

133

Boiling Patterns of Iso-asymmetric Nuclear Matter  

NASA Astrophysics Data System (ADS)

Limits of thermodynamic metastability of self-bound neutron-rich nuclear matter are explored within the framework of microcanonical thermodynamics of interacting Fermi Gas model in Thomas-Fermi approximation. It is found that as the excitation energy per nucleon of the system is increased beyond a certain limiting value, the system loses metastability and becomes unstable with respect to joint fluctuations in excitation energy per nucleon and in isospin per nucleon. As a result, part of the system is forced to boil off in a form of iso-rich non-equilibrated vapors. Left behind in such a process, identifiable with distillation, is a more iso-symmetric metastable residue at a temperature characteristic of its residual isospin content. With a progressing increase in the initial excitation energy per nucleon, more neutron-rich matter is boiled off and a more iso-symmetric residue is left behind with progressively increasing characteristic temperature. Eventually, when all excess neutrons are shed, the system boils uniformly with a further supply of excitation energy, leaving behind a smaller and smaller residue at a characteristic boiling-point temperature of iso-symmetric matter.

Tõke, Jan

2013-03-01

134

A noninvasive human temperature screening system with multiple detection points  

NASA Astrophysics Data System (ADS)

This paper introduces a non-invasive human temperature screening system for use in a large public area. Our key idea is to combine an image filtering process, an image morphology algorithm, and a particle analysis process in such a way that an individual's face in live thermal image can be located so that the skin temperature can be monitored and displayed. From our experiment, we find that the temperature measurement depends on each individual's response to the ambient temperature and on the contrast of the thermal image against the black body radiation source. This indicates that using the blackbody radiation source as our temperature reference does not totally compensate the fluctuation in human skin temperature. Our field test study at the triage section of Rajavithi Hospital, Thailand, shows that the maximum skin temperatures from people's faces can be simultaneously monitored and displayed in real time. In addition, the temperature value obtained from the thermal imaging camera has less fluctuation with respect to the true core body temperature once the disturbance from the surrounding environment is compensated. Hyperthermic patients can be identified with 100% sensitivity when the temperature threshold level and the offset temperature value are appropriately chosen.

Sumriddetchkajorn, Sarun; Chaitavon, Kosom

2008-05-01

135

POOL BOILING OF HIGH-FREQUENCY CONDUCTORS  

Microsoft Academic Search

This study presents development of a unique, powerful method for cooling high-frequency, AC conductors that can benefit end users of transformer windings, electrical machine windings, and magnet coils. This method of heat removal involves boiling a dielectric, fluorinert refrigerant that is in direct contact with litz wire conductors. A pool boiling test vessel is constructed, which provides for temperature control

S. E. Wright; S. Konecni; C. N. Ammerman; J. R. Sims

2001-01-01

136

46 CFR 153.908 - Cargo viscosity and melting point information; measuring cargo temperature during discharge...  

Code of Federal Regulations, 2010 CFR

...2010-10-01 false Cargo viscosity and melting point information; measuring cargo temperature...Information § 153.908 Cargo viscosity and melting point information; measuring cargo temperature...has a written statement of the cargo's melting point in °C from the cargo's...

2010-10-01

137

46 CFR 153.908 - Cargo viscosity and melting point information; measuring cargo temperature during discharge...  

Code of Federal Regulations, 2010 CFR

...2009-10-01 false Cargo viscosity and melting point information; measuring cargo temperature...Information § 153.908 Cargo viscosity and melting point information; measuring cargo temperature...has a written statement of the cargo's melting point in °C from the cargo's...

2009-10-01

138

Improved Thermal Model for the Realization of the Triple Points of Cryogenic Gases as Temperature Fixed Points  

NASA Astrophysics Data System (ADS)

The realization of the triple points of the cryogenic gases hydrogen, neon, oxygen, and argon as temperature fixed points at the highest level of accuracy requires consideration of the special properties of these fixed-point substances, as done in a general measurement protocol published elsewhere. The protocol is applied to the apparatus and methodology used for an international star intercomparison of sealed fixed-point cells. A generalized thermal model is developed to include the coexistence of different solid-liquid interfaces and various thermal resistances. This results in further components in the detailed uncertainty budget for the correction of the measuring power of the thermometer and for the extrapolation to the liquidus point. As a basis for an optimum fixed-point realization, especially an explanation is given why extremely long time periods may be necessary for the thermal recovery after pulses of the intermittent heating used for the calorimetric method.

Wolber, L.; Fellmuth, B.

2011-01-01

139

TEMPERATURE VARIATION WITH TIME IN A PERENNIALLY BOILING WELL IN THE LONG VALLEY CALDERA, MONO COUNTY, CALIFORNIA; OBSERVATIONS IN CHANCE NO. 1 (1976-1983).  

USGS Publications Warehouse

Chance No. 1 was drilled to a depth of 245. 4 m and cased to a depth of 72. 2 m in 1961. Temperature logs were obtained in 1976, 1982, and 1983, with the casing open to the atmosphere. Water was boiling at the surface of the fluid column on each occasion. Temperatures within the upper part of the cased interval remained virtually identical over the 7-year period. The small differences observed can be ascribed to convective motions in the large-diameter casing and the large geothermal gradient. Above a depth of 160 m in the open hole, temperatures have cooled 5 degree -7 degree C over the 7-year period of observation. The shape of the temperature profiles and their variation with time can be explained by an influx of cool water at about 160 m. The cooling rate is much larger between 1982 and 1983 than that between 1982 and 1976, which suggests that earthquake shaking may be a major contributing factor.

Diment, W. H.; Urban, T. C.; Nathenson, Manuel

1985-01-01

140

The Low-Temperature Handling of Navy Distillate Fuels. Phase III. The Effect of Pour-Point-Depressant Additives on Cloud-Point and Low-Temperature Fluidity.  

National Technical Information Service (NTIS)

The effect of six commercially available pour-point depressant additives on the cloud-point temperatures and 'Enjay Fluidities' of six distillate fuels was determined. Five of the six fuels were Navy Distillate types, the sixth was a Diesel Fuel, Marine. ...

E. W. White K. V. Nagy

1973-01-01

141

Phase relations and adiabats in boiling seafloor geothermal systems  

NASA Astrophysics Data System (ADS)

Observations of large salinity variations and vent temperatures in the range of 380-400°C suggest that boiling or two-phase separation may be occurring in some seafloor geothermal systems. Consideration of flow rates and the relatively small differences in density between vapors and liquids at the supercritical pressures at depth in these systems suggests that boiling is occurring under closed-system conditions. Salinity and temperature of boiling vents can be used to estimate the pressure-temperature point in the subsurface at which liquid seawater first reached the two-phase boundary. Data are reviewed to construct phase diagrams of coexisting brines and vapors in the two-phase region at pressures corresponding to those of the seafloor geothermal systems. A method is developed for calculating the enthalpy and entropy of the coexisting mixtures, and results are used to construct adiabats from the seafloor to the P-T two-phase boundary. Results for seafloor vents discharging at 2300 m below sea level indicate that a 385°C vent is composed of a brine (7% NaCl equivalent) in equilibrium with a vapor (0.1% NaCl). Brine constitutes 45% by weight of the mixture, and the fluid first boiled at approximately 1 km below the seafloor at 415°C, 330 bar. A 400°C vent is primarily vapor (88 wt.%, 0.044% NaCl) with a small amount of brine (26% NaCl) and first boiled at 2.9 km below the seafloor at 500°C, 520 bar. These results show that adiabatic decompression in the two-phase region results in dramatic cooling of the fluid mixture when there is a large fraction of vapor.

Bischoff, James L.; Pitzer, Kenneth S.

1985-11-01

142

Phase relations and adiabats in boiling seafloor geothermal systems  

USGS Publications Warehouse

Observations of large salinity variations and vent temperatures in the range of 380-400??C suggest that boiling or two-phase separation may be occurring in some seafloor geothermal systems. Consideration of flow rates and the relatively small differences in density between vapors and liquids at the supercritical pressures at depth in these systems suggests that boiling is occurring under closed-system conditions. Salinity and temperature of boiling vents can be used to estimate the pressure-temperature point in the subsurface at which liquid seawater first reached the two-phase boundary. Data are reviewed to construct phase diagrams of coexisting brines and vapors in the two-phase region at pressures corresponding to those of the seafloor geothermal systems. A method is developed for calculating the enthalpy and entropy of the coexisting mixtures, and results are used to construct adiabats from the seafloor to the P-T two-phase boundary. Results for seafloor vents discharging at 2300 m below sea level indicate that a 385??C vent is composed of a brine (7% NaCl equivalent) in equilibrium with a vapor (0.1% NaCl). Brine constitutes 45% by weight of the mixture, and the fluid first boiled at approximately 1 km below the seafloor at 415??C, 330 bar. A 400??C vent is primarily vapor (88 wt.%, 0.044% NaCl) with a small amount of brine (26% NaCl) and first boiled at 2.9 km below the seafloor at 500??C, 520 bar. These results show that adiabatic decompression in the two-phase region results in dramatic cooling of the fluid mixture when there is a large fraction of vapor. ?? 1985.

Bischoff, J. L.; Pitzer, K. S.

1985-01-01

143

Pressure-Drop Considerations in the Characterization of Dew-Point Transfer Standards at High Temperatures  

NASA Astrophysics Data System (ADS)

During calibration of precision optical dew-point hygrometers (DPHs), it is usually necessary to take into account the pressure drop induced by the gas flow between the "point of reference" and the "point of use" (mirror or measuring head of the DPH) either as a correction of the reference dew-point temperature or as part of the uncertainty estimation. At dew-point temperatures in the range of ambient temperature and below, it is sufficient to determine the pressure drop for the required gas flow, and to keep the volumetric flow constant during the measurements. In this case, it is feasible to keep the dry-gas flow into the dew-point generator constant or to measure the flow downstream the DPH at ambient temperature. In normal operation, at least one DPH in addition to the monitoring DPH are used, and this operation has to be applied to each instrument. The situation is different at high dew-point temperatures up to 95 °C, the currently achievable upper limit reported in this paper. With increasing dew-point temperatures, the reference gas contains increasing amounts of water vapour and a constant dry-gas flow will lead to a significant enhanced volume flow at the conditions at the point of use, and therefore, to a significantly varying pressure drop depending on the applied dew-point temperature. At dew-point temperatures above ambient temperature, it is also necessary to heat the reference gas and the mirror head of the DPH sufficiently to avoid condensation which will additionally increase the volume flow and the pressure drop. In this paper, a method is provided to calculate the dry-gas flow rate needed to maintain a known wet-gas flow rate through a chilled mirror for a range of temperature and pressures.

Mitter, H.; Böse, N.; Benyon, R.; Vicente, T.

2012-09-01

144

Microchannel flow boiling mechanisms leading to burnout  

SciTech Connect

The boiling mechanisms for microchannel flow are investigated when the channel cross-section in height to width is large (of order 10/1), near its single-phase optimum. A separated flow model was developed which allowed for saturated boiling near the heated base and single-phase flow elsewhere within the channel cross-section. In these high aspect ratio heat sinks, the role of subcooled boiling was found to be insignificant relative to that of saturated boiling, the latter allowing for a doubling of the applied heat load from single-phase operation before burnout was experienced. As the exit mass quality of the saturated region approached one for increasing heat flux, both the model and the experimental case indicated a burnout condition had also been approached. The model underpredicted the measured base temperature, which has been generally noted for saturated boiling in annular two-phase flow.

Landram, C.S.

1994-03-01

145

Acclimation of the temperature set-points of the heat-shock response  

Microsoft Academic Search

We surveyed studies that examined the heat-shock response (HSR) temperature set-points in response to changes in growth temperature to ask whether plasticity of the HSR set-points is common to all organisms, and whether it varies with thermal niche. Unexpectedly, sessile organisms exhibited lower acclimation in the HSR set-points compared to mobile organisms, and there was no difference in acclimation between

Deepak Barua; Scott A. Heckathorn

2004-01-01

146

The law of stable equilibrium and the entropy-based boiling curve for flow boiling  

Microsoft Academic Search

Convective flow boiling in sub-cooled fluids is recognized as one of the few means of accommodating very high heat fluxes. There are many available correlations for predicting the inner wall temperature of the heated duct in the several regimes of the empirical Nukiyama boiling curve, although unfortunately there is no physical fundamentals of such curve. Recently, the author has shown

Francisco J. Collado

2005-01-01

147

The Transition From Nucleate Boiling Towards the Convection: Application to the Quenching of Metallic Massive Parts  

SciTech Connect

In a recent study on thermal aspects of the quenching process, we developed an original device of measurement which allowed to update the competition between the heat transfer modes according to the quenching conditions and the quenched part size. One shows that, according to the range value of Biot number, the more resistive one part is, the more the boiling phases are relatively short. In order to provide relatively precise data for simulation of the quenching process in the case of strongly resistive parts from a thermal point of view, we undertook experiments on the cooling transition from nucleate boiling towards the convection. The obtained experimental results show that the temperature of transition from the nucleate boiling to the convection increases when the bath temperature decreases. We present the differences between the values of convection coefficient according to whether the bath is agitated or not. Experimental results relating are compared to some classical correlations.

Bourouga, Brahim [LTN-UMR 6607, Universite de Nantes, BP 50609 - 44306 Nantes cedex 3 (France); Gilles, Jerome [Saint-Gobain Research, BP 135, 93303 Aubervilliers Cedex (France)

2007-04-07

148

Effects of surface tension and contact angle on sensible heating and boiling incipience in dielectric falling films  

SciTech Connect

Predicting the point of incipient boiling is of paramount importance for reliable operation of liquid-cooled microelectronic heat sources during power transients. This study focuses on heat transfer from a simulated multichip module to a falling film. Experiments have been performed to develop an understanding of the influence of surface tension and wetting characteristics in sensible heat transfer and boiling incipience in free-falling dielectric (FC-72) liquid films. A correlation for the space-average heat transfer coefficient is presented which shows clear departure of FC-72 data from correlations obtained for fluids with higher surface tension. The boiling results reveal that the vanishingly small contact angle of FC-72 precluded the application of correlations currently employed to predict incipience. Also, the temperature overshoot commonly encountered upon boiling incipience in wetting fluids was nonexistent in all the experimental runs. 14 refs., 12 figs.

Marsh, W.J.; Mudawwar, I.

1988-01-01

149

Camera-based investigation of high-temperature fixed points for radiometric application  

NASA Astrophysics Data System (ADS)

A radiance camera was used to investigate the radiation field emitted by high-temperature blackbodies and fixed-point cavities up to temperatures of 3000 K. In a first step the applicability of the camera to measure the spectral radiance at such high temperatures was investigated. In a second step the radiation characteristics of several sources were studied using the camera system, in particular, large area fixed-point blackbodies of Cu, Pt-C and ZrC-C. Especially for the ZrC-C fixed points the radiation field at the cavity opening was found to be non-uniform. This observation explains systematic differences in the plateau shape of large aperture eutectic fixed-point cells for radiometers with different fields of view. Using the two-dimensional radiance distribution measured with the camera system the deviation of the temperatures measured with interference filter radiometers and radiation thermometers was studied.

Anhalt, K.; Lindner, D.; Krüger, U.; Schmidt, F.; Hartmann, J.

2009-08-01

150

SRM 1970: Succinonitrile Triple-Point Standard - A Temperature Reference Standard Near 58.08C.  

National Technical Information Service (NTIS)

Triple-point-of-succinonitrile cells have been tested and established as Standard Reference Material (SRM) 1970. Of the 115 cells tested, 109 were accepted as SRM 1970. Five of the 115 cells had triple-point temperatures lower than 58.0785C (the low-tempe...

B. W. Mangum S. El-Sabban

1985-01-01

151

Determination of Fuel/Air Mass Ratios for Jet Fuels at Their Flash Point Temperatures.  

National Technical Information Service (NTIS)

The goal of this project was to determine fuel vapor densities and, ultimately, fuel-to-air mass ratios (FAMRs) for 11 commercial jet fuels at their flash point temperatures. The vapor composition of each fuel sample was modeled at each flash point temper...

J. E. Woodrow

2006-01-01

152

A Concerted International Project to Establish High-Temperature Fixed Points for Primary Thermometry  

NASA Astrophysics Data System (ADS)

Research into high-temperature fixed points above 1,100°C has made significant progress since they were first reported in 1999. In particular, it has been established that single cells are repeatable at the sub-50 mK level, and intra-cell reproducibility at the 100 mK level has been demonstrated even at temperatures as high as 2,500°C. The fixed points have been used to compare temperature and radiometry scales over a wide temperature range, and are being developed and established as secondary references for thermocouple calibrations. However, before they can be fully accepted as primary temperature references, much work remains to be done, namely: (1) Establishment of long-term stability of the fixed-point temperature; (2) Development of robust procedures for the reliable construction of the fixed-point cells (to ensure routine intra-cell reproducibility of 100 mK); (3) Demonstration of long-term robustness of the fixed-point cells; (4) Assignment of thermodynamic temperatures to a selected set of fixed points; (5) Agreement and acceptance of these temperature values by the CCT; (6) Agreed methods on how to take full utility of these new fixed points into any future International Temperature Scale (ITS)—or the current ITS-90 via an addendum to the mise en pratique for the definition of the kelvin. To ensure that this work progresses to completion in a reasonable time frame, a research project, under the auspices of the CCT-WG5, has been formulated and is currently in progress with the aim of achieving the above mentioned targets by 2012. This article will describe this project and detail partner contributions.

Machin, G.; Bloembergen, P.; Hartmann, J.; Sadli, M.; Yamada, Y.

2007-12-01

153

Calibration and performance assessment of a temperature sensor prototype using a 1-point calibration procedure  

NASA Astrophysics Data System (ADS)

This study aims to assess the relevance of 1-point calibration procedure, within the framework of the development of a new telemetric temperature sensor. The criteria used for performance assessment were the level of accuracy, and the time of inertia of the temperature sensor prototype (TSP) tested. First, the stability of the calibration bath was assessed. Then, the accuracy of 16 prototypes was evaluated for 7 target temperatures (ranging from 29 °C to 45 °C). Finally, the inertia of TSP response was evaluated while increasing and decreasing the bath temperature. The difference between prototype and target temperature increases as bath temperature moves away from 37 °C however, the accuracy of the sensor conforms to applicable standards. Most TSP remain in the range of +/-0.2 °C for each temperature level tested, but a linear, decreasing slope is observed; prototypes underestimate high temperatures and overestimate low temperatures. Data from time of inertia assessment show that probes were within the range of +/-0.2 °C from the target temperature with a maximal delay of 150 s which satisfy standard norms. However, results indicate that a 1-point calibration procedure of the sensors appears non optimal, a 2-point calibration procedure should be performed to avoid the observed temperature data slope.

Chapon, P. A.; Gauthier, A.; Bulla, J.; Moussay, S.

2012-11-01

154

Investigation on the Curie temperature of a ferroelectric material as a temperature fixed-point  

NASA Astrophysics Data System (ADS)

In-situ calibration of thermometers in industrial processes or facilities becomes more and more important due to increasing demands for better measurement uncertainty, cost reduction and traceability of the temperature measurements. To meet these demands a new in-situ calibration method was investigated using the ferroelectric/paraelectric phase transition temperature of barium titanate (BaTiO3) as temperature reference. The phase transition temperature was estimated from the BaTiO3 dielectric permittivity characteristic by a capacitive measurement. In a series of measurements the reproducibility of this temperature and influencing quantities were investigated and a dynamic in-situ calibration method was derived.

Schalles, M.; Fröhlich, T.; Langhammer, H. T.; Boguhn, D.

2013-09-01

155

Evaporation, Boiling and Bubbles  

ERIC Educational Resources Information Center

|Evaporation and boiling are both terms applied to the change of a liquid to the vapour/gaseous state. This article argues that it is the formation of bubbles of vapour within the liquid that most clearly differentiates boiling from evaporation although only a minority of chemistry textbooks seems to mention bubble formation in this context. The…

Goodwin, Alan

2012-01-01

156

A simple boiling module  

Microsoft Academic Search

Recent efforts to visually capture the phenomena of boiling have proposed monolithic approaches that extend the basic techniques underlying existing fluid solvers. In this work, we show that if we instead treat boiling as a sep- arate computational module to be loosely coupled to an existing solver, a very easy to implement, highly efficient algorithm can be designed that produces

Theodore Kim; Mark Carlson

2007-01-01

157

Boiling fluids in a region of rapid uplift, Nanga Parbat Massif, Pakistan  

NASA Astrophysics Data System (ADS)

The Nanga Parbat massif of northern Pakistan is currently undergoing rapid uplift (approx. 5-10 mm/a), resulting in near-surface elevated temperatures. Numerous quartz veins cut geologically young structures (less than 2 Ma), attesting to widespread young fluid flow. Fluid inclusions in quartz veins are predominantly low density water vapor (down to 0.05 mg/cu m), with some low density carbon dioxide vapor, and the fluid is predominantly meteoric in origin. Fluid inclusions provide evidence for boiling near to the critical points for water and for 5 wt% NaCl solution (up to 410 C). Head-driven meteoric water was convecting in fracture permeability under hydrostatic pressures which followed the boiling point-depth curve and near-boiling springs emanate from the surface. Hydrostatic pressures persisted to depths of about 6 km below the topographic surface, or near to sea level, where the brittle-ductile transition is inferred to lie. Numerical modeling of conductive heat flow in an area of high relief during rapid uplift indicates that the shape of the near-surface conductive geotherm is significantly influenced by topographic relief. Reasonable approximations for topgraphy at Nanga Parbat produce a conductive geotherm which implies high, near-surface geothermal gradients (greater than 100 C/km, and the isotherms describe a giant pillar of heat. Above about 4 km, fluid temperature is greater than conductive rock temperature in permeable zones which carry convecting boiling meteoric fluid.

Craw, D.; Koons, P. O.; Winslow, D.; Chamberlain, C. P.; Zeitler, P.

1994-12-01

158

Realization of the Temperature Scale in the Range from 234.3 K (Hg Triple Point) to 1084.62°C (Cu Freezing Point) in Croatia  

NASA Astrophysics Data System (ADS)

This article describes the realization of the International Temperature Scale in the range from 234.3 K (mercury triple point) to 1084.62°C (copper freezing point) at the Laboratory for Process Measurement (LPM), Faculty of Mechanical Engineering and Naval Architecture (FSB), University of Zagreb. The system for the realization of the ITS-90 consists of the sealed fixed-point cells (mercury triple point, water triple point and gallium melting point) and the apparatus designed for the optimal realization of open fixed-point cells which include the gallium melting point, tin freezing point, zinc freezing point, aluminum freezing point, and copper freezing point. The maintenance of the open fixed-point cells is described, including the system for filling the cells with pure argon and for maintaining the pressure during the realization.

Zvizdic, Davor; Veliki, Tomislav; Grgec Bermanec, Lovorka

2008-06-01

159

Properties of aqueous salt solutions of poly(ethylene oxide). Cloud points, ? temperatures  

Microsoft Academic Search

The determination of the properties of aqueous salt solutions of poly(ethylene oxide) has been extended to the cloud point, and? temperature measurements have been made at several concentrations for various salts (flourides, iodides, acetates, formates, phosphates, bromides, thiosulfates and perchlorates). The resulting dependency of the critical temperatures? (mostly between 290–350 K) on the molar concentration can be expressed as sequences

M. Ataman

1987-01-01

160

Development of temperature fixed points applicable to the calibration of thermometers in magnetic fields  

Microsoft Academic Search

Two temperature fixed points, (H2O and Ar) were developed to be used under magnetic fields. They serve as ideal tools to investigate the magnetic field dependence of temperature sensors. The sensors studied are Cernox™, a platinum resistance thermometer, and a thermistor. The magnetic field effect on Cernox was found to be not larger than 5 mK under 15 T at

Koichi Nara

2004-01-01

161

POINT 2011: ENDF\\/B-VII.1 Beta2 Temperature Dependent Cross Section Library  

Microsoft Academic Search

This report is one in the series of 'POINT' reports that over the years have presented temperature dependent cross sections for the then current version of ENDF\\/B. In each case I have used my personal computer at home and publicly available data and codes. I have used these in combination to produce the temperature dependent cross sections used in applications

Cullen

2011-01-01

162

The life cycle of individual boiling bubbles: Insights from beyond optical imaging  

NASA Astrophysics Data System (ADS)

With a high-speed camera, we have investigated the dynamics of individual vapor bubbles boiling on a laser-heated surface. Their sizes and shapes as they grow and depart from a surface are correlated with simultaneous thermal imaging measurements of the boiling surface using thermoreflectance-based microscopy to measure temperatures of individual stochastic events. Analysis of both the thermal profiles and the bubble shapes suggests the presence of an evaporating liquid microlayer under the developing bubble. Tuning surface and heating properties, we control the shapes of bubbles, ranging from regular periodic growth and departure to stochastic bubbles which exhibit rapid cavitation-like expansion and collapse. Unlike typical cavitation bubbles which collapse and form jets pointed towards the surface, jets from bubbles observed during boiling were observed to be directed away from the surface. By tuning the wettability of the substrate, we will report on how wettability affects the strength and direction of these jets.

Parker, Scott; Bae, Sung Chul; Cahill, David; Granick, Steve

2012-02-01

163

Thermosyphon boiling in vertical channels  

NASA Astrophysics Data System (ADS)

The thermal characteristics of ebullient cooling systems for VHSIC and VLSI microelectronic component thermal control are studied by experimentally and analytically investigating boiling heat transfer from a pair of flat, closely spaced, isoflux plates immersed in saturated water. A theoretical model for liquid flow rate through the channel is developed and used as a basis for correlating the rate of heat transfer from the channel walls. Experimental results for wall temperature as a function of axial location, heat flux, and plate spacing are presented. The finding that the wall superheat at constant imposed heat flux decreases as the channel is narrowed is explained with the aid of a boiling thermosiphon analysis which yields the mass flux through the channel.

Bar-Cohen, A.; Schweitzer, H.

164

Boiling heat transfer from an excavated fin  

SciTech Connect

In this paper a single pin fin with excavation at base is proposed to enhance boiling heat transfer. The temperature distribution in the fin is obtained numerically by solving a two-dimensional heat conduction equation. A copper fin boiling in isopropyl alcohol is taken as an example. When the operating temperature exceeds a specific value, the heat duty decreases drastically, and the whole fin is governed by film boiling. This highest operating temperature limit (burnout) is raised by digging a hole at the fin base. Two distinct solutions are found by using different initial guesses into the code. This hysteresis effect becomes noticeable for a bigger hole. A model is also developed to predict the burnout temperatures.

Liaw, S.P.; Yeh, R.H. (Dept. of Marine Engineering and Technology, National Taiwan Ocean Univ., Keelung (TW))

1992-03-01

165

Experimental and Numerical Investigation of the Temperature Field of a Fixed-Point Cavity  

NASA Astrophysics Data System (ADS)

The temperature field non-uniformity of a blackbody cavity is one of the components of uncertainty of fixed-point realization. Here a study of the design and opportunities of the temperature furnace used in VNIIM is described. The dependence of the uniformity of a temperature field on various factors is shown by results of numerical calculations of a temperature field of VNIIM's copper and gold fixed-point cells, realized with the software packages Elcut 5.3 and Ansys 11.0. A thermophysical model of the phase transition considered as steady state with convection and radiation heat exchange to an environment is applied. The basic focus is made on calculation of the radiation heat exchange between crucible elements and the environment and a furnace cavity, as a dominating component of the heat transfer. Results using analytically and numerically calculated angular factors of radiation of heat exchange are discussed. The data obtained in measurements of a temperature field of a cavity fixed point during phase transitions of copper and gold by a spectrocomparator with high sensitivity, are also shown here. Both theoretical calculation and experiment were realized at various distributions of temperature along an external surface of a crucible. Good agreement of results between steady-state calculation of a temperature field and the measured data with the best entry conditions is observed. The average value of non-uniformity of a temperature field along a cavity for points of phase transition of copper and gold for an 88 mm long graphite crucible with a 54 mm deep, 8 mm diameter cavity was 40 mK, and the temperature drop across the graphite wall was 20 mK. In this paper the reasons for occurrence of large gradients inside a fixed-point cavity during the phase transition, received during some experimental research, are also discussed.

Fuksov, V. M.; Pohodun, A. I.; Matveyev, M. S.

2011-01-01

166

High-temperature fixed points for pre-launch calibration of earth observing sensors  

NASA Astrophysics Data System (ADS)

High-temperature fixed points of metal-carbon systems, currently the target of a project in the international thermometry standards community, is also of high interest for pre-launch radiometric calibration of hyperspectral earth observing sensor in the blue wavelengths, where the conventional copper fixed point fails to supply sufficient radiance. For such a calibration, a fixed-point possibly around 2000 K is desired. One requirement for application of the high-temperature blackbody fixed-point cell to remote sensor calibration is to increase the radiating source aperture diameter to a size large enough to target with a radiance comparator based on a grating monochromator. In this presentation, a fixed-point cell of Co-C eutectic (1597 K) for remote sensor calibration application is described. An enlarged 7-mm aperture design is employed for the fixed-point cell while at the same time retaining the outer dimension to fit in existing fixed-point furnaces. The observed plateaux showed temperature and repeatability comparable to conventional 3-mm aperture cells, while cavity breakages indicates the need for improved robustness in the crucible design. Extension of the technique to Pt-C eutectic (2011 K) or Cr3C2-C peritectic (2100 K) systems, and subsequent application to calibration of the HISUI sensor is envisaged.

Yamada, Yoshiro; Ishii, Juntaro

2011-09-01

167

Electronic rhinological thermometer for three-point air temperature measurement in nasal cavity  

NASA Astrophysics Data System (ADS)

This article describes the design and construction of diagnostic medical system for air temperature measurement in nasal cavity. Concept of three-point thermometer is connected with single point electronic thermometer for air temperature measurement in nasal cavity that was previously constructed [1]. Researches were done in Microsystems and Sensors Research Group (WUT) with cooperation of physicians and laryngologists from Otolaryngology Department, Military Medical Institute, Warsaw. Measurement system consist of microprocessor module which periodically collects samples of air temperature from different part of nasal cavity, measurement head with three temperature sensors, and computer software presenting on-line results, calculating breathing parameters and storing data in database. Air temperature is measured in nasal cavity, middle part cavity and nasopharynx during regular respiration process.

?nieg, Marcin; Paczesny, Daniel; Weremczuk, Jerzy

2008-01-01

168

Detection of Simulated Defect Using IR Temperature Sensors and One Point Heating  

PubMed Central

Infrared temperature sensors, simple device for temperature measurement, have been modified for the measurement of temperature distribution on the metal surface in a way of nondestructive detection of defects of the object. In this study, the IR sensor system is utilized for the defect detection in a cylinder with one point heating, and the performance of the system is examined with an aluminum cylinder having a simulated defect. In addition, a 3-D conduction equation is numerically solved to compare the computed temperature profile with the measured one. The experimental outcome indicates that the defect detection is readily available with the proposed device and the point heating is practical for the applications of the defect detection. It is also found that the measured temperature distribution is comparable to the computed result from the conduction equation.

Kim, Byoung Chul; Heo, Young Gun; Suh, Yong Kweon; Kim, Young Han

2008-01-01

169

Critical boiling phenomena observed in microgravity  

NASA Astrophysics Data System (ADS)

We report experimental observations of the critical boiling when co-existing gas and liquid phases of pure fluid are heated under weigthlessness through the critical point. We find that when the system's temperature T is being increased to the critical temperature Tc so that it's slightly out of equilibrium, the apparent contact angle becomes very large (up to 110 circ). The gas appears to "web" the solid surface. In addition, we detect large temperature gradients between the (hot) gas phase and the (cold) liquid phase in the interferometric cell. These unexpected results are robust: they are observed either under continuous heating (ramping) or stepping by positive temperature quenches, for various morphologies of the gas bubble and in different fluids (SF6 and CO2). The difference in isentropic thermal responses of gas and liquid during heating, due to the adiabatic heating by the "Piston Effect", is responsible for the temperature non-homogeneities. The vapour recoil force due to liquid evaporation, which is involved in the boiling crisis in heat exchangers, is presumably at the origin of the interface deformation. Nous rapportons les observations expérimentales obtenues en chaffant un fluide pur diphasique gaz-liquide en coexistence au cours de la traversée de son point critique en absence de pesanteur. Lorsque la température du système diphasique hors d'équilibre est augmentée vers la température critique, nous observons en transmission un angle de contact apparent de la vapeur très important (atteignant 110 circ), le gaz semblant "mouiller" la surface solide. De plus, d'importants gradients de température entre la phase gaz chaude et la phase liquide froide sont mesurés dans les cellules observées par interférométrie. Ces résultats inattendus sont observés pour un chauffage continu (rampe) et par trempe positive (échelon), pour différents rapports d'aspect du système diphasique, pour des cellules de CO2 et de SF6, démontrant ainsi une grande robustesse. Les réponses isentropiques différentes du gaz et du liquide lors du chauffage par effet piston sont certainement responsables des inhomogénéités de température. La force de recul de la vapeur due à l'évaporation pourrait être la cause dominante de la déformation de l'interface liquide-vapeur à l'approche de la température de transition.

Garrabos, Y.; Chabot, C.; Wunenburger, R.; Delville, J.-P.; Beysens, D.

1999-06-01

170

A new technique for the measurement of radiance temperature at the melting point  

NASA Astrophysics Data System (ADS)

Measurements of the radiance temperature of metals at their melting point received wide attention recently on account of controversial results obtained in different laboratories. During further investigations at IMGC, a new technique for radiance temperature measurements at the melting point was perfected, with numerous experiments performed at the melting point of niobium. The new technique consists in bringing the material to the melting point and interrupting the flow of current just before the specimen is destroyed. Using this method the melting plateau may be repeated several times using the same specimen. Repeatibility studies may be performed, and changes in the surface structure of the material may be evaluated. Typical results of this new technique are presented, along with a complete description of this new measurement method.

Righini, F.; Bussolino, G. C.; Rosso, A.; Spišiak, J.

1993-05-01

171

Measurement of Melting Point, Radiance Temperature (at melting point), and Electrical Resistivity (above 2,100 K) of Zirconium by a Pulse Heating Method.  

National Technical Information Service (NTIS)

A subsecond duration pulse heating method is used to measure the melting point, radiance temperature (at 650 nm) at the melting point, and electrical resistivity (above 2,100 K) of zirconium. The results yield a value of 2,128 K for the melting point on t...

A. Cezairliyan F. Righini

1975-01-01

172

Measurement of Melting Point, Radiance Temperature (at Melting Point), and Electrical Resistivity (Above 2,100 K) of Zirconium by a Pulse Heating Method.  

National Technical Information Service (NTIS)

A subsecond duration pulse heating method is used to measure the melting point, radiance temperature (at 650 nm) at the melting point, and electrical resistivity (above 2,100 K) of zirconium. The results yield a value of 2,128 K for the melting point on t...

A. Cezairliyan F. Righini

1975-01-01

173

Indirect Determination of the Thermodynamic Temperature of a Gold Fixed-Point Cell  

NASA Astrophysics Data System (ADS)

Since the value T 90(Au) was fixed on the ITS-90, some determinations of the thermodynamic temperature of the gold point have been performed which form, with other renormalized results of previous measurements by radiation thermometry, the basis for the current best estimates of ( T - T 90)Au = 39.9 mK as elaborated by the CCT-WG4. Such a value, even if consistent with the behavior of T - T 90 differences at lower temperatures, is quite influenced by the low values of T Au as determined with few radiometric measurements. At INRIM, an independent indirect determination of the thermodynamic temperature of gold was performed by means of a radiation thermometry approach. A fixed-point technique was used to realize approximated thermodynamic scales from the Zn point up to the Cu point. A Si-based standard radiation thermometer working at 900 nm and 950 nm was used. The low uncertainty presently associated to the thermodynamic temperature of fixed points and the accuracy of INRIM realizations, allowed scales with an uncertainty lower than 0.03 K in terms of the thermodynamic temperature to be realized. A fixed-point cell filled with gold, 99.999 % in purity, was measured, and its freezing temperature was determined by both interpolation and extrapolation. An average T Au = 1337.395 K was found with a combined standard uncertainty of 23 mK. Such a value is 25 mK higher than the presently available value as derived by the CCT-WG4 value of ( T - T 90)Au = 39.9 mK.

Battuello, M.; Girard, F.; Florio, M.

2010-09-01

174

Thermodynamics of Flow Boiling Heat Transfer  

NASA Astrophysics Data System (ADS)

Convective boiling in sub-cooled water flowing through a heated channel is essential in many engineering applications where high heat flux needs to be accommodated. It has been customary to represent the heat transfer by the boiling curve, which shows the heat flux versus the wall-minus-saturation temperature difference. However it is a rather complicated problem, and recent revisions of two-phase flow and heat transfer note that calculated values of boiling heat transfer coefficients present many uncertainties. Quite recently, the author has shown that the average thermal gap in the heated channel (the wall temperature minus the average temperature of the coolant) was tightly connected with the thermodynamic efficiency of a theoretical reversible engine placed in this thermal gap. In this work, whereas this correlation is checked again with data taken by General Electric (task III) for water at high pressure, a possible connection between this wall efficiency and the reversible-work theorem is explored.

Collado, F. J.

2003-05-01

175

Odd-Boiled Eggs  

ERIC Educational Resources Information Center

|At a Shabbat lunch in Madrid not long ago, the conversation turned to the question of boiling eggs. One of the guests mentioned that a Dutch rabbi he knew had heard that in order to make it more likely that boiled eggs be kosher, you should add an egg to the pot if the number you began with was even. According to the laws of Kashruth, Jews may…

Kaminsky, Kenneth; Scheman, Naomi

2010-01-01

176

Odd-Boiled Eggs  

ERIC Educational Resources Information Center

At a Shabbat lunch in Madrid not long ago, the conversation turned to the question of boiling eggs. One of the guests mentioned that a Dutch rabbi he knew had heard that in order to make it more likely that boiled eggs be kosher, you should add an egg to the pot if the number you began with was even. According to the laws of Kashruth, Jews may not…

Kaminsky, Kenneth; Scheman, Naomi

2010-01-01

177

Estimation of dew point temperature using neuro-fuzzy and neural network techniques  

NASA Astrophysics Data System (ADS)

This study investigates the ability of two different artificial neural network (ANN) models, generalized regression neural networks model (GRNNM) and Kohonen self-organizing feature maps neural networks model (KSOFM), and two different adaptive neural fuzzy inference system (ANFIS) models, ANFIS model with sub-clustering identification (ANFIS-SC) and ANFIS model with grid partitioning identification (ANFIS-GP), for estimating daily dew point temperature. The climatic data that consisted of 8 years of daily records of air temperature, sunshine hours, wind speed, saturation vapor pressure, relative humidity, and dew point temperature from three weather stations, Daego, Pohang, and Ulsan, in South Korea were used in the study. The estimates of ANN and ANFIS models were compared according to the three different statistics, root mean square errors, mean absolute errors, and determination coefficient. Comparison results revealed that the ANFIS-SC, ANFIS-GP, and GRNNM models showed almost the same accuracy and they performed better than the KSOFM model. Results also indicated that the sunshine hours, wind speed, and saturation vapor pressure have little effect on dew point temperature. It was found that the dew point temperature could be successfully estimated by using T mean and R H variables.

Kisi, Ozgur; Kim, Sungwon; Shiri, Jalal

2013-02-01

178

Progress report for the CCT-WG5 high temperature fixed point research plan  

NASA Astrophysics Data System (ADS)

An overview of the progress in High Temperature Fixed Point (HTFP) research conducted under the auspices of the CCT-WG5 research plan is reported. In brief highlights are: Provisional long term stability of HTFPs has been demonstrated. Optimum construction methods for HTFPs have been established and high quality HTFPs of Co-C, Pt-C and Re-C have been constructed for thermodynamic temperature assignment. The major sources of uncertainty in the assignment of thermodynamic temperature have been identified and quantified. The status of absolute radiometric temperature measurement has been quantified through the circulation of a set of HTFPs. The measurement campaign to assign low uncertainty thermodynamic temperatures to a selected set of HTFPs will begin in mid-2012. It is envisaged that this will be complete by 2015 leading to HTFPs becoming routine reference standards for radiometry and high temperature metrology.

Machin, G.; Anhalt, K.; Bloembergen, P.; Sadli, M.; Yamada, Y.; Woolliams, E. R.

2013-09-01

179

Ultra-high temperature isothermal furnace liners (IFLS) for copper freeze point cells  

NASA Astrophysics Data System (ADS)

Primary Laboratories use large fixed-point cells in deep calibration furnaces utilizing heat pipes to achieve temperature uniformity. This combination of furnace, heat pipe, and cell gives the smallest of uncertainties. The heat pipe, also known as an isothermal furnace liner (IFL), has typically been manufactured with Alloy 600/601 as the envelope material since the introduction of high temperature IFLs over 40 years ago. Alloy 600/601 is a widely available high temperature material, which is compatible with Cesium, Potassium, and Sodium and has adequate oxidation resistance and reasonable high temperature strength. Advanced Cooling Technologies, Inc. (ACT) Alloy 600/Sodium IFLs are rated to 1100°C for approximately 1000 hours of operation (based on creep strength). Laboratories interested in performing calibrations and studies around the copper freezing point (1084.62°C) were frustrated by the 1000 hours at 1100°C limitation and the fact that expensive freeze-point cells were getting stuck and/or crushed inside the IFL. Because of this growing frustration/need, ACT developed an Ultra High Temperature IFL to take advantage of the exceptional high temperature strength properties of Haynes 230.

Dussinger, P. M.; Tavener, J. P.

2013-09-01

180

Operation of a low temperature absorption chiller at rating point and at reduced evaporator temperature  

NASA Astrophysics Data System (ADS)

The returned fifteen ton Solar Absorption Machine (SAM) 015 chiller was given a cursory visual inspection, some obvious problems were remedied, and then it was placed on a test stand to get a measure of dirty performance. It was then given a standard acid clean, the water side of the tubes was brushed clean, and then the machine was retested. The before and after cleaning data were compared to equivalent data taken before the machine was shipped. The second part of the work statement was to experimentally demonstrate the technical feasibility of operating the chiller at evaporator temperatures below 0(0)C (32(0)F) and identify any operational problems.

Best, R.; Biermann, W.; Reimann, R. C.

1985-01-01

181

An Investigation of the Relation Between Contact Thermometry and Dew-Point Temperature Realization  

NASA Astrophysics Data System (ADS)

Precision optical dew-point hygrometers are the most commonly used transfer standards for the comparison of dew-point temperature realizations at National Metrology Institutes (NMIs) and for disseminating traceability to calibration laboratories. These instruments have been shown to be highly reproducible when properly used. In order to obtain the best performance, the resistance of the platinum resistance thermometer (PRT) embedded in the mirror is usually measured with an external, traceable resistance bridge or digital multimeter. The relation between the conventional calibration of miniature PRTs, prior to their assembly in the mirrors of state-of-the-art optical dew-point hygrometers and their subsequent calibration as dew-point temperature measurement devices, has been investigated. Standard humidity generators of three NMIs were used to calibrate hygrometers of different designs, covering the dew-point temperature range from -75 °C to + 95 °C. The results span more than a decade, during which time successive improvements and modifications were implemented by the manufacturer. The findings are presented and discussed in the context of enabling the optimum use of these transfer standards and as a basis for determining contributions to the uncertainty in their calibration.

Benyon, R.; Böse, N.; Mitter, H.; Mutter, D.; Vicente, T.

2012-09-01

182

Cryogenic Temperature Sealed Fixed Points: a New-Generation of Modular Cells at IMGC  

Microsoft Academic Search

Mainly in the frame of the European Project MULTICELLS, IMGC developed a new generation of sealed temperature fixed-point cells (M-cells), based on the principle of modular elements, each containing one substance, several of which can be mounted in a copper frame of reduced dimensions where thermometers are fitted. The device being modular, the user can select up to six fixed

F. Pavese; D. Ferri; I. Peroni; A. Pugliese; P. P. M. Steur; B. Fellmuth; D. Head; L. Lipinski; A. Peruzzi; A. Szmyrka Grzebyk; L. Wolber

2003-01-01

183

Inverse methodology to determine mold set-point temperature in resin transfer molding process  

Microsoft Academic Search

This study consists of determining by inverse method the set-point temperature of the fluid flowing through heating plates in a Resin Transfer Molding (RTM) process tool so as to reach a predetermined thermal history in the composite part. Although the described methodology is applied in a specific mold in this paper, it remains general and may be transposed to a

Vincent Sobotka; Nicolas Lefevre; Yvon Jarny; Didier Delaunay

2010-01-01

184

Improvements in the realization of the ITS-90 over the temperature range from the melting point of gallium to the freezing point of silver at NIM  

NASA Astrophysics Data System (ADS)

The temperature primary standard over the range from the melting point of gallium to the freezing point of silver in National institute of Metrology (NIM), China, was established in the early 1990s. The performance of all of fixed-point furnaces degraded and needs to be updated due to many years of use. Nowadays, the satisfactory fixed point materials can be available with the development of the modern purification techniques. NIM plans to use a group of three cells for each defining fixed point temperature. In this way the eventual drift of individual cells can be evidenced by periodic intercomparison and this will increase the reliability in disseminating the ITS-90 in China. This article describes the recent improvements in realization of ITS-90 over temperature range from the melting point of gallium to the freezing point of silver at NIM. Taking advantages of the technological advances in the design and manufacture of furnaces, the new three-zone furnaces and the open-type fixed points were developed from the freezing point of indium to the freezing point of silver, and a furnace with the three-zone semiconductor cooling was designed to automatically realize the melting point of gallium. The reproducibility of the new melting point of gallium and the new open-type freezing points of In, Sn, Zn. Al and Ag is improved, especially the freezing points of Al and Ag with the reproducibility of 0.2mK and 0.5mK respectively. The expanded uncertainty in the realization of these defining fixed point temperatures is 0.34mK, 0.44mK, 0.54mK, 0.60mK, 1.30mK and 1.88mK respectively.

Sun, J.; Zhang, J. T.; Ping, Q.

2013-09-01

185

On the three-point function in finite temperature field theory  

NASA Astrophysics Data System (ADS)

We discuss the three-point function in finite temperature field theory. In particular we study the temperature dependence, at the one loop level, of the retarded and advanced vertex functions which can be defined both in the imaginary time and in the real time formalisms. In the high temperature limit the various vertex functions differ, in general, by terms of O(T) which are sensitive to the soft momentum scale. URA 14-36 du CNRS, associée à ENS de Lyon et au LAPP d'Annecy-le-Vieux (IN2P3-CNRS).

Aurenche, P.; Petitgirard, E.; del Río Gaztelurrutia, T.

1992-12-01

186

Temperature dependent vibrational lifetimes in supercritical fluids near the critical point  

NASA Astrophysics Data System (ADS)

Vibrational relaxation measurements on the CO asymmetric stretching mode (~1980 cm-1) of tungsten hexacarbonyl (W(CO)6) as a function of temperature at constant density in several supercritical solvents in the vicinity of the critical point are presented. In supercritical ethane, at the critical density, there is a region above the critical temperature (Tc) in which the lifetime increases with increasing temperature. When the temperature is raised sufficiently (~Tc+70 °C), the lifetime decreases with further increase in temperature. A recent hydrodynamic/thermodynamic theory of vibrational relaxation in supercritical fluids reproduces this behavior semiquantitatively. The temperature dependent data for fixed densities somewhat above and below the critical density is in better agreement with the theory. In fluoroform solvent at the critical density, the vibrational lifetime also initially increases with increasing temperature. However, in supercritical CO2 at the critical density, the temperature dependent vibrational lifetime decreases approximately linearly with temperature beginning almost immediately above Tc. The theory does not reproduce this behavior. A comparison between the absolute lifetimes in the three solvents and the temperature trends is made.

Myers, D. J.; Chen, Shirley; Shigeiwa, Motoyuki; Cherayil, Binny J.; Fayer, M. D.

1998-10-01

187

Modeling and analysis of low heat flux natural convection sodium boiling in LMFBRs  

Microsoft Academic Search

Flow excursion induced dryout at low heat flux natural convection boiling, typical of liquid metal fast breeder reactor, is addressed. Steady state calculations indicate that low quality boiling is possible up to the point of Ledinegg instability leading to flow excursion and subsequent dryout in agreement with experimental data. A flow regime-dependent dryout heat flux relationship based upon saturated boiling

M. Khatib-Rahbar; E. G. Cazzoli

1982-01-01

188

Development of a new radiometer for the thermodynamic measurement of high temperature fixed points  

NASA Astrophysics Data System (ADS)

The National Physical Laboratory (NPL) has developed a new radiometer to measure the thermodynamic melting point temperatures of high temperature fixed points with ultra-low uncertainties. In comparison with the NPL's Absolute Radiation Thermometer (ART), the "THermodynamic Optical Radiometer" (THOR) is more portable and compact, with a much lower size-of-source effect and improved performance in other parameters such as temperature sensitivity. It has been designed for calibration as a whole instrument via the radiance method, removing the need to calibrate the individual subcomponents, as required by ART, and thereby reducing uncertainties. In addition, the calibration approach has been improved through a new integrating sphere that has been designed to have greater uniformity.

Dury, M. R.; Goodman, T. M.; Lowe, D. H.; Machin, G.; Woolliams, E. R.

2013-09-01

189

Thermal runaway limit of tubular reactors, defined at the inflection point of the temperature profile  

SciTech Connect

The predicted maximum temperature difference between reacting fluid and wall to avoid thermal runaways can be exceeded in production reactors. This has been known for some time but the explanation has been lacking. The reason for this deviation was found in that the traditional approximation of the sensitivity criterion by [Delta]T [le] RT[sup 2]/E is correct for a limiting value at the inflection point but not at the hot spot, where it can be much higher. The exact expression for the limiting value at the inflection point is the total temperature derivative of the rate, and this is proven in this paper mathematically. The total temperature derivative of a rate can be measured in a few, well-designed recycle reactor experiments. Results were checked by computer simulation of tubular reactors. Matching to those predicted from CSTR or recycle reactor (RR) measurements was excellent. The proposed interpretation explains why previously predicted limits could be exceeded in practice.

Bashir, S.; Chovan, T.; Masri, B.J.; Mukherjee, A.; Pant, A.; Sen, S.; Vijayaragharvan, P. (Akron Univ., OH (United States). Dept. of Chemical Engineering); Berty, J.M. (Berty Reaction Engineers, Ltd., Fogelsville, PA (United States))

1992-09-01

190

Boiling on the surface of a rotating disc  

Microsoft Academic Search

An experimental unit to study heat-transfer characteristics while boiling at subatmospheric pressure of a horizontal smooth spinning disc was designed and built. Evaporation experiments were carried out with the speed of rotation varying from 0 to 1000 rpm and the feed flow rate from 1 to 5 litre\\/min. The boiling temperature varied between 40 and 50 °C. Water and corn

S. Yanniotis; D. Kolokotsa

1996-01-01

191

Optimization of the thermogauge furnace for realizing high temperature fixed points  

NASA Astrophysics Data System (ADS)

The thermogauge furnace was commonly used in many NMIs as a blackbody source for calibration of the radiation thermometer. It can also be used for realizing the high temperature fixed point(HTFP). According to our experience, when realizing HTFP we need the furnace provide relative good temperature uniformity to avoid the possible damage to the HTFP. To improve temperature uniformity in the furnace, the furnace tube was machined near the tube ends with a help of a simulation analysis by "ansys workbench". Temperature distributions before and after optimization were measured and compared at 1300 °C, 1700°C, 2500 °C, which roughly correspond to Co-C(1324 °C), Pt-C(1738 °C) and Re-C(2474 °C), respectively. The results clearly indicate that through machining the tube the temperature uniformity of the Thermogage furnace can be remarkably improved. A Pt-C high temperature fixed point was realized in the modified Thermogauge furnace subsequently, the plateaus were compared with what obtained using old heater, and the results were presented in this paper.

Wang, T.; Dong, W.; Liu, F.

2013-09-01

192

SHORT COMMUNICATION: Metal carbide-carbon peritectic systems as high-temperature fixed points in thermometry  

NASA Astrophysics Data System (ADS)

WC-C, Cr3C2-C and Mn7C3-C peritectic systems were investigated for their potential of serving as high-temperature reference points in thermometry. Mixtures of high-purity graphite powder with W, Cr and Mn powder of 99.99%, 99.9% and 99.95% purity by mass, respectively, were placed in graphite blackbody crucibles and melting/freezing plateaus were observed by means of a radiation thermometer. The observed melting temperatures were 2749 °C (WC-C), 1826 °C (Cr3C2-C) and 1331 °C (Mn7C3-C), with a repeatability—in each case—of 0.02 K. The melting range for WC-C and Cr3C2-C peritectics was roughly 0.1 K. WC-C showed a flat freezing plateau that agreed with the melting plateau within the repeatability. The three fixed points are possible candidates, like the metal (carbide)-carbon eutectic fixed points, in the realization of an improved high-temperature scale above the copper point.

Yamada, Y.; Wang, Y.; Sasajima, N.

2006-10-01

193

A Temperature Fixed Point Near 58C: The triple point of ultrapure succinonitrile could be used to calibrate thermometers between 0 and 100C.  

National Technical Information Service (NTIS)

This citation summarizes a one-page announcement of technology available for utilization. A new secondary 'fixed point' for defining the international Practical Temperature Scale has emerged from improved materials-processing methods for the organic subst...

1982-01-01

194

Sand boils without earthquakes  

USGS Publications Warehouse

Sedimentary deformation caused by liquefaction has become a popular means for inferring prehistoric strong earthquakes. This report describes a new mechanism for generating such features in the absence of earthquakes. Sand boils and a 180-m-long sand dike formed in Fremont Valley, California, when sediment-laden surface runoff was intercepted along the upslope part of a 500-m-long preexisting ground crack, flowed subhorizonally in the crack, and then flowed upward in the downslope part of the crack where it discharged as sand boils on the land surface. If the sand boils and their feeder dike were stratigraphically preserved, they could be misinterpreted as evidence for earthquake-induced liquefaction. -Authors

Holzer, T. L.; Clark, M. M.

1993-01-01

195

Measurement of the in freezing-point temperature: Effect of the liquid-solid interface structure  

NASA Astrophysics Data System (ADS)

The results of the experimental study of the inner interface formation process under different conditions of its initiation for the indium freezing point showed that, depending on the initiation intensity, both the planar structure of the interface on the thermometer well and a noticeable intergrowth of dendrites could be obtained. However, under some specific initiation conditions dendrites disappeared partly or completely in the process of crystallization. The value of the indium freezing point temperature was measured under realization conditions corresponding to different inner interface structure.

Ivanova, A. G.; Abasov, M. Yu.; Gerasimov, S. F.; Pokhodun, A. I.

2013-09-01

196

Experimental study on the onset of nucleate boiling in narrow channel by using grey relational analysis (GRA)  

NASA Astrophysics Data System (ADS)

The point of ONB (Onset of Nucleate Boiling) is a key point of boiling heat transfer in narrow channels. Due to the special structure and complex flow, the points of ONB in narrow channels are affected by many factors, their characteristics are not understood completely yet. In order to study relevant influence factors on ONB in narrow channel from the aspect of quantitative analysis, GRA (Grey Relational Analysis) is applied to analyze the experimental data of ONB in narrow channel by taking water as the working fluid. And then the intensity sequence of the factors that have effects on ONB are confirmed as the heat flux, outlet dryness, pressure, mass flow rate, inlet temperature and outlet temperature. Through analyzing the data of ONB of newly published literatures, the mechanisms for the main influence factors are suggested.

Han, Dong; Gao, Puzhen; Yan, Liming; Lv, Lulu

2013-07-01

197

A comparison between point- and semi-continuous sampling for assessing body temperature in a free-ranging ectotherm  

Microsoft Academic Search

We used intracoelomically implanted temperature dataloggers to obtain semi-continuous body temperature data and establish monthly thermal profiles for free-ranging rattlesnakes. We mimicked random and non-random point-sampling methods by selecting a single daily data point from all values or from restricted times of day to reflect common point-sampling constraints. Thermal profiles generated from point-sampling differed from those generated from semi-continuous sampling,

Emily N. Taylor; Dale F. DeNardo; Michael A. Malawy

2004-01-01

198

Measurement of the Melting Point Temperature of Several Lithium-Sodium-Beryllium Fluoride Salt (Flinabe) Mixtures  

SciTech Connect

The molten salt Flibe, a combination of lithium and beryllium fluorides studied for molten salt fission reactors, has been proposed as a breeder and coolant for fusion applications. The melting points of 2LiF-BeF{sub 2} and LiF-BeF{sub 2} are 460 deg. C and 363 deg. C, but LiF-BeF{sub 2} is rather viscous and has less lithium for breeding. In the Advanced Power Extraction (APEX) Program, concepts with a free flowing liquid for the first wall and blanket were investigated. Flinabe (a mixture of LiF, BeF{sub 2} and NaF) was selected for a molten salt design because a melting temperature below 350 deg. C appeared possible and this provided an attractive operating temperature window for a reactor. To confirm that a ternary salt with a low melting temperature existed, several combinations of the fluoride salts, LiF, NaF and BeF{sub 2}, were melted in a stainless steel crucible under vacuum. One had an apparent melting temperature of 305 deg. C. The test system, preparation of the mixtures, melting procedures and temperature curves for the melting and cooling are presented along with the apparent melting points. Thermal modeling of the salt pool and crucible is reported in an accompanying paper.

McDonald, J.M; Nygren, R.E.; Lutz, T.J.; Tanaka, T.J; Ulrickson, M.A.; Boyle, T.J.; Troncosa, K.P. [Sandia National Laboratories (United States)

2005-04-15

199

Influence of Point Defects on the Shear Elastic Coefficients and on the Melting Temperature of Copper  

NASA Astrophysics Data System (ADS)

We present molecular dynamics simulations of the influence of point defects on the shear elastic properties of copper. We find that vacancies do not influence these properties at all, while the introduction of interstitials causes a large reduction of the elastic coefficients. The simulations establish a phase diagram of the melting temperature as a function of the density of interstitials. A crystal having no free surface undergoes bulk mechanical melting as a result of the vanishing of C'?(C11-C12)/2 once the specific volume reaches a critical value, equal to the experimental volume of liquid phase. This critical volume is history independent, in the sense that it does not depend on whether is it reached by heating the crystal or by adding defects at a constant temperature. These results generalize the Born model of melting for the case where point defects are present.

Kanigel, Amit; Adler, Joan; Polturak, Emil

200

Zero-point motion and temperature effects on the band gap of semiconductor nanoclusters  

NASA Astrophysics Data System (ADS)

We calculate the band gap renormalization of semiconductor nanoclusters, avoiding the large computational costs associated with the calculations of the self-energy (Fan) and the Debye-Waller terms. This approach allows us to address clusters with a few hundred atoms. For Silicon nanoclusters, we obtain a band gap reduction of hundreds of of meV associated with the quantum zero point motion. This reduction rapidly increases with decreasing cluster size. Based on the Bose-Einstein distribution, we further study the temperature dependence of the band gap in semiconductor nanoclusters and find a band gap shift of -580 meV and -270 meV when going from T=0 to room temperature for silicon clusters with radius of 9.6 and 11.9 ,espectively. Furthermore, we find that the band gap renormalization of semiconductor nanoclusters is dominated by the optic-like vibrational modes with ?4 point group symmetry.

Bester, Gabriel; Han, P.

2013-03-01

201

Investigation of potential factors affecting the measurement of dew point temperature in oil-soaked transformers  

NASA Astrophysics Data System (ADS)

Moisture within a transformer's insulation system has been proven to degrade its dielectric strength. When installing a transformer in situ, one method used to calculate the moisture content of the transformer insulation is to measure the dew point temperature of the internal gas volume of the transformer tank. There are two instruments commercially available that are designed for dew point temperature measurement: the Alnor Model 7000 Dewpointer and the Vaisala DRYCAPRTM Hand-Held Dewpoint Meter DM70. Although these instruments perform an identical task, the design technology behind each instrument is vastly different. When the Alnor Dewpointer and Vaisala DM70 instruments are used to measure the dew point of the internal gas volume simultaneously from a pressurized transformer, their differences in dew point measurement have been observed to vary as much as 30 °F. There is minimal scientific research available that focuses on the process of measuring dew point of a gas inside a pressurized transformer, let alone this observed phenomenon. The primary objective of this work was to determine what effect certain factors potentially have on dew point measurements of a transformer's internal gas volume, in hopes of understanding the root cause of this phenomenon. Three factors that were studied include (1) human error, (2) the use of calibrated and out-of-calibration instruments, and (3) the presence of oil vapor gases in the dry air sample, and their subsequent effects on the Q-value of the sampled gas. After completing this portion of testing, none of the selected variables proved to be a direct cause of the observed discrepancies between the two instruments. The secondary objective was to validate the accuracy of each instrument as compared to its respective published range by testing against a known dew point temperature produced by a humidity generator. In a select operating range of -22 °F to -4 °F, both instruments were found to be accurate and within their specified tolerances. This temperature range is frequently encountered in oil-soaked transformers, and demonstrates that both instruments can measure accurately over a limited, yet common, range despite their different design methodologies. It is clear that there is another unknown factor present in oil-soaked transformers that is causing the observed discrepancy between these instruments. Future work will include testing on newly manufactured or rewound transformers in order to investigate other variables that could be causing this discrepancy.

Kraus, Adam H.

202

Choking of flow in short channels during the shock boiling of liquids  

Microsoft Academic Search

The paper considers theoretical and experimental results concerning the mass flow rate of boiling liquids, leaking through short channels into the air. The temperature dependence of mass flow rate exhibits a discontinuity corresponding to the start of choking of the channel. The choking is associated with shock boiling of the liquid, the necessary intensity of boiling being assured by fluctuating

V. P. Skripov; N. A. Shuravenko; O. A. Isaev

1978-01-01

203

Investigation of TiC C Eutectic and WC C Peritectic High-Temperature Fixed Points  

NASA Astrophysics Data System (ADS)

TiC C eutectic (2,761°C) and WC C peritectic (2,749°C) fixed points were investigated to compare their potential as high-temperature thermometric reference points. Two TiC C and three WC C fixed-point cells were constructed, and the melting and freezing plateaux were evaluated by means of radiation thermometry. The repeatability of the TiC C eutectic within a day was 60 mK with a melting range roughly 200 mK. The repeatability of the melting temperature of the WC C peritectic within 1 day was 17 mK with a melting range of ˜70 mK. The repeatability of the freezing temperature of the WC C peritectic was 21 mK with a freezing range less than 20 mK. One of the TiC C cells was constructed from a TiC and graphite powder mixture. The filling showed the reaction with the graphite crucible was suppressed and the ingot contained less voids, although the lack of high-purity TiC powder poses a problem. The WC C cells were easily constructed, like metal carbon eutectic cells, without any evident reaction with the crucible. From these results, it is concluded that the WC C peritectic has more potential than the TiC C eutectic as a high-temperature reference point. The investigation of the purification of the TiC C cell during filling and the plateau observation are also reported.

Sasajima, Naohiko; Yamada, Yoshiro

2008-06-01

204

Enzymic hydrolysis of animal fats in organic solvents at temperatures below their melting points  

Microsoft Academic Search

Lipase fromCandida rugosa catalyzed the hydrolysis of inedible beef tallow and pork lard (edible and inedible) in the presence of organic solvents\\u000a at temperatures below the melting point of the fat. Reactions were carried out at 50% substrate with 180 lipase units per\\u000a gram of fat in a two-liter reactor. In the presence of isooctane (5-10%) beef tallow yielded 94%

M. D. Virto; Jose Miguel Lascaray; Rodolfo Solozabal; Mertxe de Renobales

1991-01-01

205

Room temperature migration of ion beam injected point defects in crystalline silicon  

Microsoft Academic Search

We have investigated the room temperature diffusion and trapping phenomena of ion beam generated point defects in crystalline Si by monitoring their interaction with dopants, native contaminants such as C and O, and other defects. Spreading resistance measurements show that a small fraction (? 10?7–10?6) of the defects generated at the surface by a 40 keV Si implant is injected

Vittorio Privitera; Salvatore Coffa; Francesco Priolo; Kim Kyllesbech Larsen; Sebania Libertino; Alberto Carnera

1996-01-01

206

Temperature-dependent quantum electron transport in 2D point contacts.  

PubMed

We consider the transmission of electrons through a two-dimensional ballistic point contact in the low-conductance regime near the pinch-off region. The scattering of electrons by Friedel oscillations of charge density results in a contribution to the conductance proportional to the temperature. The sign of this linear term depends on the range of the electron-electron interaction and appears to be negative for the relevant experimental parameters. PMID:23288558

Krishtop, T V; Nagaev, K E

2013-01-03

207

Bias and temperature dependence of the 0.7 conductance anomaly in quantum point contacts  

Microsoft Academic Search

The 0.7 (2e2\\/h) conductance anomaly is studied in strongly confined, etched GaAs\\/GaAlAs quantum point contacts, by measuring the differential conductance as a function of source-drain and gate bias as well as a function of temperature. We investigate in detail how, for a given gate voltage, the differential conductance depends on the finite bias voltage and find a so-called self-gating effect,

A. Kristensen; H. Bruus; A. E. Hansen; J. B. Jensen; P. E. Lindelof; C. J. Marckmann; J. Nygård; C. B. Sørensen; F. Beuscher; A. Forchel; M. Michel

2000-01-01

208

POINT 2012: ENDF\\/B-VII.1 Final Temperature Dependent Cross Section Library  

Microsoft Academic Search

This report is one in the series of 'POINT' reports that over the years have presented temperature dependent cross sections for the then current version of ENDF\\/B [R1]. In each case I have used my personal computer at home and publicly available data and codes: (1) publicly available nuclear data (the current ENDF\\/B data, available on-line at the National Nuclear

Cullen

2012-01-01

209

Triple point temperature of neon isotopes: Dependence on nitrogen impurity and sealed-cell model  

NASA Astrophysics Data System (ADS)

This paper illustrates a study conducted at INRIM, to further check how some quantities influence the value of the triple point temperature of the neon high-purity isotopes 20Ne and 22Ne. The influence of nitrogen as a chemical impurity in neon is critical with regard to the present best total uncertainty achieved in the measurement of these triple points, but only one determination is available in the literature. Checks are reported, performed on two different samples of 22Ne known to contain a N2 amount of 157.10-6, using two different models of sealed cells. The model of the cell can, in principle, have some effects on the shape of the melting plateau or on the triple point temperature observed for the sample sealed in it. This can be due to cell thermal parameters, or because the INRIM cell element mod. c contains many copper wires closely packed, which can, in principle, constrain the interface and induce a premelting-like effect. The reported results on a cell mod. Bter show no evident effect from the cell model and provide a value for the effect of N2 in Ne liquidus point of 8.6(1.9) ?K ppm N2-1, only slightly different from the literature datum.

Pavese, F.; Steur, P. P. M.; Giraudi, D.

2013-09-01

210

Comparison of the triple-point temperatures of 20Ne, 22Ne and normal Ne  

NASA Astrophysics Data System (ADS)

At the National Metrology Institute of Japan (NMIJ), the triple points of 20Ne and 22Ne were realized using modular sealed cells, Ec3Ne20 and Ec8Ne22, made by the Istituto Nazionale di Ricerca Metrologica (INRiM) in Italy. The difference of the triple-point temperatures of 20Ne and 22Ne was estimated by using the sub-range of standard platinum resistance thermometers (SPRTs) calibrated by NMIJ on the International Temperature Scale of 1990 (ITS-90). The melting curves obtained with the Ec3Ne20 and Ec8Ne22 cells show narrow widths (0.1 mK) over a wide range of the inverse of the melted fraction (1/F) from 1/F=1 to 1/F=10. The liquidus point Ttp estimated by the melting curves from F~0.5 to F~0.85 using the Ec8Ne22 is 0.146 29 (4) K higher than that using the Ec3Ne20 cell, which is in good agreement with that observed by INRiM using the same cells. After correction of the effect of impurities and other isotopes for Ec3Ne20 and Ec8Ne22 cells, the difference of Ttp between pure 20Ne and pure 22Ne is estimated to be 0.146 61 (4) K, which is consistent with the recent results reported elsewhere. The sub-ranges of SPRTs computed by using the triple point of 20Ne or 22Ne realized by the Ec3Ne20 cell or the Ec8Ne22 cell in place of the triple point of Ne for the defining fixed point of the ITS-90 are in good agreement with those realized on the basis of the ITS-90 at NMIJ within 0.03 mK, which is much smaller than the non-uniqueness and the sub-range inconsistency of SPRTs.

Nakano, T.; Tamura, O.; Nagao, K.

2013-09-01

211

POINT 2011: ENDF/B-VII.1 Beta2 Temperature Dependent Cross Section Library  

SciTech Connect

This report is one in the series of 'POINT' reports that over the years have presented temperature dependent cross sections for the then current version of ENDF/B. In each case I have used my personal computer at home and publicly available data and codes. I have used these in combination to produce the temperature dependent cross sections used in applications and presented in this report. I should mention that today anyone with a personal computer can produce these results. The latest ENDF/B-VII.1 beta2 data library was recently and is now freely available through the National Nuclear Data Center (NNDC), Brookhaven National Laboratory. This release completely supersedes all preceding releases of ENDF/B. As distributed the ENDF/B-VII.1 data includes cross sections represented in the form of a combination of resonance parameters and/or tabulated energy dependent cross sections, nominally at 0 Kelvin temperature. For use in our applications the ENDF/B-VII.1 library has been processed into cross sections at eight neutron reactor like temperatures, between 0 and 2100 Kelvin, in steps of 300 Kelvin (the exception being 293.6 Kelvin, for exact room temperature at 20 Celsius). It has also been processed to five astrophysics like temperatures, 1, 10, 100 eV, 1 and 10 keV. For reference purposes, 300 Kelvin is approximately 1/40 eV, so that 1 eV is approximately 12,000 Kelvin. At each temperature the cross sections are tabulated and linearly interpolable in energy. All results are in the computer independent ENDF-6 character format [R2], which allows the data to be easily transported between computers. In its processed form the POINT 2011 library is approximately 16 gigabyte in size and is distributed on one compressed DVDs (see, below for the details of the contents of each DVD).

Cullen, D E

2011-04-07

212

Investigation of Furnace Uniformity and its Effect on High-Temperature Fixed-Point Performance  

NASA Astrophysics Data System (ADS)

A large-area furnace BB3500YY was designed and built at the VNIIOFI as a furnace for high-temperature metal (carbide)-carbon (M(C)-C) eutectic fixed points and was then investigated at the NMIJ. The dependence of the temperature uniformity of the furnace on various heater and cell holder arrangements was investigated. After making some improvements, the temperature of the central part of the furnace was uniform to within 2K over a length of 40 mm—the length of the fixed-point cell—at a temperature of 2,500°C. With this furnace, the melting plateaux of Re-C and TiC-C were shown to be better than those observed in other furnaces. For instance, a Re-C cell showed melting plateaux with a 0.1K melting range and a duration of about 40 min. Furthermore, to verify the capability of the furnace to fill cells, one Re-C and one TiC-C cell were made using the BB3500YY. The cells were then compared to a Re-C cell made in a Nagano furnace and a TiC-C cell filled in a BB3200pg furnace. The agreement in plateau shapes demonstrates the capability of the BB3500YY furnace to also function as a filling furnace.

Khlevnoy, B.; Sakharov, M.; Ogarev, S.; Sapritsky, V.; Yamada, Y.; Anhalt, K.

2008-02-01

213

Microbiological Effectiveness of Disinfecting Water by Boiling in Rural Guatemala  

PubMed Central

Boiling is the most common means of treating water in the home and the benchmark against which alternative point-of-use water treatment options must be compared. In a 5-week study in rural Guatemala among 45 households who claimed they always or almost always boiled their drinking water, boiling was associated with a 86.2% reduction in geometric mean thermotolerant coliforms (TTC) (N = 206, P < 0.0001). Despite consistent levels of fecal contamination in source water, 71.2% of stored water samples from self-reported boilers met the World Health Organization guidelines for safe drinking water (0 TTC/100 mL), and 10.7% fell within the commonly accepted low-risk category of (1–10 TTC/100 mL). As actually practiced in the study community, boiling significantly improved the microbiological quality of drinking water, though boiled and stored drinking water is not always free of fecal contaminations.

Rosa, Ghislaine; Miller, Laura; Clasen, Thomas

2010-01-01

214

Microbiological effectiveness of disinfecting water by boiling in rural Guatemala.  

PubMed

Boiling is the most common means of treating water in the home and the benchmark against which alternative point-of-use water treatment options must be compared. In a 5-week study in rural Guatemala among 45 households who claimed they always or almost always boiled their drinking water, boiling was associated with a 86.2% reduction in geometric mean thermotolerant coliforms (TTC) (N = 206, P < 0.0001). Despite consistent levels of fecal contamination in source water, 71.2% of stored water samples from self-reported boilers met the World Health Organization guidelines for safe drinking water (0 TTC/100 mL), and 10.7% fell within the commonly accepted low-risk category of (1-10 TTC/100 mL). As actually practiced in the study community, boiling significantly improved the microbiological quality of drinking water, though boiled and stored drinking water is not always free of fecal contaminations. PMID:20207876

Rosa, Ghislaine; Miller, Laura; Clasen, Thomas

2010-03-01

215

Thermal modelling comparing high temperature fixed point measurements by contact and non-contact thermometry  

NASA Astrophysics Data System (ADS)

This paper reports thermal modelling that aims to establish if the measurement method - either by a radiation thermometer or by a thermocouple - significantly influences the measured temperature of the high temperature fixed points Co-C, Pd-C and Ru-C. It is clear that both measurement techniques have specific physical characteristics which may affect the temperature measured during the melting plateau. With the radiation thermometer, the radiation heat transfer is directly influenced by the environment because the back-wall is effectively viewing the cold outside environment. In the case of a thermocouple direct viewing of the outside world is blocked so radiation transport is significantly reduced; however, in the case of the thermocouple there is a different component of heat transfer, namely conduction from the thermowell walls in contact with the thermocouple along the thermocouple stem itself.

Castro, P.; Machin, G.; Pearce, J. V.

2013-09-01

216

Temperature variability in X-ray bright points observed with Hinode/XRT  

NASA Astrophysics Data System (ADS)

Aims: We investigate the variability in temperature as a function of time among a sample of coronal X-ray bright points (XBPs). Methods: We analysed a 7-h (17:00-24:00 UT) long time sequence of soft X-ray images observed almost simultaneously in two filters (Ti_poly and Al_mesh) on April 14, 2007 with X-ray telescope (XRT) onboard the Hinode mission. We identified and selected 14 XBPs for a detailed analysis. The light curves of XBPs were derived using the SolarSoft library in IDL. The temperature of XBPs was determined using the calibrated temperature response curves of the two filters by means of the intensity ratio method. Results: We find that the XBPs show a high variability in their temperature and that the average temperature ranges from 1.1 MK to 3.4 MK. The variations in temperature are often correlated with changes in average X-ray emission. It is evident from the results of time series that the XBP heating rate can be highly variable on short timescales, suggesting that it has a reconnection origin.

Kariyappa, R.; Deluca, E. E.; Saar, S. H.; Golub, L.; Damé, L.; Pevtsov, A. A.; Varghese, B. A.

2011-02-01

217

Rotational and vibrational temperatures in a hydrogen discharge with a magnetic X-point  

SciTech Connect

A novel plasma source with a magnetic X-point has been developed to probe an alternative for cesium-free negative hydrogen ion production. This study presents first results for the gas and vibrational temperatures in the source at 1 Pa and various RF powers. The temperatures are obtained from analysis of the intensity distribution of the molecular Fulcher-{alpha} bands. The gas temperature increases with the RF power, while the vibrational temperature remains constant in the studied range of RF powers. Both quantities show no appreciable spatial dependence. The obtained high values of the vibrational temperatures indicate a high population of the vibrational levels, favourable for the volume negative ion production. A theoretical concept indicates the presence of an optimum value for the vibrational temperature at which the negative hydrogen ion yield by volume processes has a maximum. Coincidently, the measured value is close to this optimum. This indicates that the novel concept can provide certain advantages compared to other sources based on volume production.

Tsankov, Tsanko V.; Czarnetzki, Uwe [Institute for Plasma and Atomic Physics, Ruhr University Bochum, 44780 Bochum (Germany); Toko, Kaoru [Institute of Applied Physics, University of Tsukuba, Tsukuba, Ibaraki 305-8573 (Japan)

2012-12-15

218

Potential aerospace applications of high temperature superconductors  

Microsoft Academic Search

The recent discovery of High Temperature Superconductors (HTS) with superconducting transition temperature, T(sub c), above the boiling point of liquid nitrogen has opened the door for using these materials in new and practical applications. These materials have zero resistance to electric current, have the capability of carrying large currents and as such have the potential to be used in high

Raouf Selim

1994-01-01

219

Cryogenic Temperature Sealed Fixed Points: a New-Generation of Modular Cells at IMGC  

NASA Astrophysics Data System (ADS)

Mainly in the frame of the European Project MULTICELLS, IMGC developed a new generation of sealed temperature fixed-point cells (M-cells), based on the principle of modular elements, each containing one substance, several of which can be mounted in a copper frame of reduced dimensions where thermometers are fitted. The device being modular, the user can select up to six fixed points to be mounted each time in the device. The paper describes the design of the devices and reports on three years of testing on e-H2, Ne, O2 and Ar elements and on investigations not only at IMGC but also at INTiBS, NMi, NPL and PTB. The results obtained with the new devices are better than those obtained with the previous single-substance IMGC cells. These studies mainly concerned the effect of the geometry of the elements, which are now much smaller in size than the previous IMGC cells, on the thermal behaviour, in order to optimise the thermal response time and minimise the thermal resistance between the solid-liquid interface of the substance and the thermometers. For e-H2, the new elements also allowed investigation of the effect of the isotopic composition on the triple-point temperature.

Pavese, F.; Ferri, D.; Peroni, I.; Pugliese, A.; Steur, P. P. M.; Fellmuth, B.; Head, D.; Lipinski, L.; Peruzzi, A.; Szmyrka Grzebyk, A.; Wolber, L.

2003-09-01

220

Cloud point phenomena for POE-type nonionic surfactants in a model room temperature ionic liquid.  

PubMed

The cloud point phenomenon has been investigated for the solutions of polyoxyethylene (POE)-type nonionic surfactants (C(12)E(5), C(12)E(6), C(12)E(7), C(10)E(6), and C(14)E(6)) in 1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF(4)), a typical room temperature ionic liquid (RTIL). The cloud point, T(c), increases with the elongation of the POE chain, while decreases with the increase in the hydrocarbon chain length. This demonstrates that the solvophilicity/solvophobicity of the surfactants in RTIL comes from POE chain/hydrocarbon chain. When compared with an aqueous system, the chain length dependence of T(c) is larger for the RTIL system regarding both POE and hydrocarbon chains; in particular, hydrocarbon chain length affects T(c) much more strongly in the RTIL system than in equivalent aqueous systems. In a similar fashion to the much-studied aqueous systems, the micellar growth is also observed in this RTIL solvent as the temperature approaches T(c). The cloud point curves have been analyzed using a Flory-Huggins-type model based on phase separation in polymer solutions. PMID:18656889

Inoue, Tohru; Misono, Takeshi

2008-04-26

221

Crystallization fouling of finned tubes during pool boiling: effect of fin density  

NASA Astrophysics Data System (ADS)

Bubble characteristics such as density, size, frequency and motion are key factors that contribute to the superiority of nucleate pool boiling over other modes of heat transfer. Nevertheless, if heat transfer occurs in an environment prone to fouling, the very same parameters may lead to accelerated deposit formation due to concentration effects beneath the growing bubbles. This has led to the widely accepted design recommendation to maintain the heat transfer surface temperature below the boiling point if fouling may occur, e.g., in seawater desalination. The present paper aims at investigating the formation of deposits on finned tubes during nucleate pool boiling of CaSO4 solutions. The test finned tubes are low finned tubes with fin densities of 19 and 26 fins/in. made from Cu-Ni. The fouling experiments were carried out at atmospheric pressure for different heat fluxes ranging from 100 to 300 kW/m2 and a CaSO4 concentration of 1.6 g/L. For the sake of comparison, similar runs were performed with smooth stainless steel tubes. The results show that: (1) the fouling resistance decreases with increasing fin density, (2) fouling on the finned tubes was reduced with increasing nucleate boiling activity and (3) if any fouling layer occurred on the finned tubes it could be removed easily.

Esawy, M.; Malayeri, M. R.; Müller-Steinhagen, H.

2010-11-01

222

``MULTICELLS'': A European Project on Cryogenic Temperature Fixed Points in Sealed Cells  

NASA Astrophysics Data System (ADS)

In January 2000 a European Project called ``MULTICELLS'' started, in the field of the realisation of temperature standard fixed points in the range (2.18 to 216.6) K, ending in April 2003. Two lines of cell design were developed for both modular multi-component cells (IMGC and INM down to 13.8 K) and 4He lambda-point cells (IMGC and PTB). The cells were tested mainly by INTiBS, NMi, NPL, and PTB. Studies were performed on the thermal design and to improve the knowledge of the underlying physical chemistry, with the goal of reducing the overall uncertainty budget to less than 0.1 mK. This involved also the comparison of the new modular multi-component cells, which are made of several elements-each realising one different fixed point, e.g., e-H2, Ne, O2, and Ar, but also D2, N2 and CO2- mounted on a common frame where the thermometers are fitted, with the previous-generation cells. The new cells represent a substantial improvement in the state-of-the-art of the realisation of these fixed points and of their use for the realisation of the ITS-90 and for thermometric checkpoints. A self-contained cryogenic-free computer-run cryostat is under development as the final stage of the Project for measuring the modular cells and for thermometer intercomparison.

Pavese, F.; Fellmuth, B.; Head, D.; Hermier, Y.; Peruzzi, A.; Szmyrka Grzebyk, A.; Zanin, L.

2003-09-01

223

Heating surface thermal stabilization for pool boiling on porous coverings  

NASA Astrophysics Data System (ADS)

The paper presents the results of comprehensive research of boiling on heating surfaces covered with copper fibrous capillary-porous structures (CPSs) used as fillings in heat pipes. The studies involved experimental and theoretical investigations, including development of technologies related to lab-scale manufacturing of sintered structures. Application-related problems such as the use of boiling in heat transfer control were also taken into account. Experiments were carried out for pool boiling of distilled water, ethanol, R-113 and R-123 on coverings of porosity of 40, 70 and 85%. The scope of the paper includes the description of the experimental setup, the methods used and the study results for pool boiling with various hysteresis types. In addition, possible applications of boiling on CPSs porous coverings to heating surface temperature stabilization are proposed.

Wójcik, T. M.; Poniewski, M. E.

2012-11-01

224

Little low-power boiling never hurt anybody. [LMFBR  

SciTech Connect

Failures in the shutdown heat removal system of an LMFBR might lead to flow stagnation and coolant boiling in the reactor core. At normal operating power, the onset of sodium boiling will lead to film dryout and melting of the cladding and fuel within a few seconds. On the other hand, both calculations and currently available experimental data indicate that at heat fluxes corresponding to decay heat power levels, boiling leads to improved heat removal; and it limits the temperature rise in the fuel pins. Therefore, when setting safety criteria for decay heat removal systems, there is no reason to preclude sodium boiling per se because of heat removal considerations. As an example that illustrates the beneficial impact of coolant boiling, a case involving temporary loss of feedwater and staggered pump failures in a hypothetical, 1000-MWe loop-type reactor was run in the SASSYS-1 code.

Dunn, F.E.

1985-01-01

225

Boiling of Water Droplets Containing Dissolved Salts  

NASA Astrophysics Data System (ADS)

We conducted experiments on the effect of dissolving three different salts (sodium chloride, sodium sulphate and magnesium sulphate) in water droplets boiling on a hot stainless steel surface. Substrate temperatures were varied from 100^oC to 300^oC. We photographed droplets as they evaporated, and recorded their evaporation time. At surface temperatures that were too low to initiate nucleate boiling, all three salts were found to reduce the evaporation rate since they lower the vapor pressure of water. In the nucleate boiling regime, sodium sulphate and magnesium sulphate enhanced heat transfer because they prevented coalescence of vapor bubbles and produced foaming in the droplet, significantly reducing droplet lifetime. The ability of salts to prevent coalescence is linked to their ionic strength: electric charge accumulated on the surfaces of bubbles produces a repulsive force, preventing them from approaching each other. Sodium chloride, which has a low ionic strength, had little effect on droplet evaporation. Low concentrations (<0.3 mol/liter) of magnesium sulphate enhanced droplet boiling by promoting foaming. However high concentrations (>0.3 mol/liter) reduce droplet evaporation rates by increasing the vapour pressure of water.

Cui, Qiang; Chandra, Sanjeev; McCahan, Susan

2000-11-01

226

On the hot-spot-controlled critical heat flux mechanism in pool boiling of saturated fluids  

SciTech Connect

In this paper, we further investigate the hypothesis that the critical heat flux (CHF) occurs when some point on the heated surface reaches a high enough temperature that liquid can no longer contact that point, resulting in a gradual but continuous increase in the overall surface temperature. This hypothesis unifies the occurrence of the CHF and the quenching of hot surfaces by relating both to the same concept, i.e., the ability of a liquid to contact a hot surface. We use a two-dimensional transient conduction model to study the boiling phenomenon in the second transition region of saturated pool nucleate boiling on a horizontal surface. The heater surface is assumed to consist of two regions: a dry patch region formed as a result of complete evaporation of the thinner liquid macrolayers and a two-phase macrolayer region formed by numerous vapor stems penetrating relatively thick liquid macrolayers. The constitutive relations used to determine the stem-macrolayer configuration in the two-phase macrolayer region of the boiling surface were reevaluated for Gaertner`s clean water and water-nickel/salt solution. 29 refs.

Unal, C.; Sadasivan, P.; Nelson, R.A.

1992-05-01

227

Destabilization of film boiling  

Microsoft Academic Search

Some recent results are reviewed on the destabilization of film boiling, both under quasi-steady and fast-transient conditions, and with both solid-liquid and liquid-liquid systems. Interest has been generated in this phenomenon in connection with the triggering of vapor explosions and the rewetting of hot dry surfaces. Several theoretical and experimental models are used in calculations: an adsorption theory for the

S. G. Bankoff

1980-01-01

228

Change-point analysis for serially correlated summit temperatures in the Romanian Carpathians  

NASA Astrophysics Data System (ADS)

Characterizing climatic changes in the high-altitude mountain regions helps scientists and policy makers understand the effects of such changes on water resources, economic development, and the health of ecosystems. This paper proposes a change-point analysis to determine the time and magnitude of summer temperature changes in the summit areas of Romanian Carpathians between 1961 and 2007. Due to their altitude, massiveness, and position, Romanian Carpathians are an important barrier for different types of air masses between Western and Southeastern Europe. The results show that the change in summer temperatures occurred shortly after 1980. The average magnitude of this change is consistent with changes occurring in other parts of Southern Europe in the same time period although the magnitude of changes at individual weather stations may differ substantially. We aided our analysis by a statistical method based on regression models with serially correlated ARMA errors.

Croitoru, Adina-Eliza; Drignei, Dorin; Holobaca, Iulian-Horia; Dragota, Carmen Sofia

2012-04-01

229

Self-validating type C thermocouples to 2300 °C using high temperature fixed points  

NASA Astrophysics Data System (ADS)

Above 1500 °C, tungsten-rhenium (W-Re) thermocouples are the most commonly used contact thermometers because they are practical and inexpensive. However in general loss of calibration is very rapid, and, due to their embrittlement at high temperature, it is generally not possible to remove them for recalibration from the process environments in which they are used. Even if removal for recalibration was possible this would be of, at best, very limited use due to large inhomogeneity effects. Ideally, these thermocouples require some mechanism to monitor their drift in-situ. In this study, we describe self-validation of Type C (W5%Re/W26%Re) thermocouples by means of miniature high temperature fixed points comprising crucibles containing respectively Co-C, Pt-C, Ru-C, and Ir-C eutectic alloys. An overview of developments in this area is presented.

Pearce, J. V.; Elliott, C. J.; Machin, G.; Ongrai, O.

2013-09-01

230

Note: atmospheric point discharge current measurements using a temperature-compensated logarithmic current amplifier.  

PubMed

Measurements of atmospheric corona currents have been made for over 100 years to indicate the atmospheric electric field. Corona currents vary substantially, in polarity and in magnitude. The instrument described here uses a sharp point sensor connected to a temperature compensated bi-polar logarithmic current amplifier. Calibrations over a range of currents from ±10 fA to ±3 ?A and across ±20 °C show it has an excellent logarithmic response over six orders of magnitude from 1 pA to 1 ?A in both polarities for the range of atmospheric temperatures likely to be encountered in the southern UK. Comparison with atmospheric electric field measurements during disturbed weather confirms that bipolar electric fields induce corona currents of corresponding sign, with magnitudes ~0.5 ?A. PMID:23822390

Marlton, G J; Harrison, R G; Nicoll, K A

2013-06-01

231

A miniature high-temperature fixed point for self-validation of type C thermocouples  

NASA Astrophysics Data System (ADS)

Reliable high-temperature (>1500 °C) measurement is crucial for a wide range of industrial processes as well as specialized applications, e.g. aerospace. The most common type of sensor used for high-temperature measurement is the thermocouple. At and above 1500 °C, tungsten-rhenium (W-Re) thermocouples are the most commonly used temperature sensors due to their utility up to 2300 °C. However, the achievable accuracy of W-Re thermocouples is seriously limited by the effects of their inhomogeneity, drift and hysteresis. Furthermore, due to their embrittlement at high temperature, the removal of these thermocouples from environments such as nuclear power plants or materials processing furnaces for recalibration is generally not possible. Even if removal for recalibration were possible, this would be of, at best, very limited use due to large inhomogeneity effects. Ideally, these thermocouples require some mechanism to monitor their drift in situ. In this study, we describe a miniature Co-C eutectic fixed-point cell to evaluate the stability of type C (W5%Re/W26%Re) thermocouples by means of in situ calibration.

Ongrai, O.; Pearce, J. V.; Machin, G.; Sweeney, S. J.

2011-10-01

232

An updated global grid point surface air temperature anomaly data set: 1851--1990  

SciTech Connect

This document presents land-based monthly surface air temperature anomalies (departures from a 1951--1970 reference period mean) on a 5{degree} latitude by 10{degree} longitude global grid. Monthly surface air temperature anomalies (departures from a 1957--1975 reference period mean) for the Antarctic (grid points from 65{degree}S to 85{degree}S) are presented in a similar way as a separate data set. The data were derived primarily from the World Weather Records and the archives of the United Kingdom Meteorological Office. This long-term record of temperature anomalies may be used in studies addressing possible greenhouse-gas-induced climate changes. To date, the data have been employed in generating regional, hemispheric, and global time series for determining whether recent (i.e., post-1900) warming trends have taken place. This document also presents the monthly mean temperature records for the individual stations that were used to generate the set of gridded anomalies. The periods of record vary by station. Northern Hemisphere station data have been corrected for inhomogeneities, while Southern Hemisphere data are presented in uncorrected form. 14 refs., 11 figs., 10 tabs.

Sepanski, R.J.; Boden, T.A.; Daniels, R.C.

1991-10-01

233

Simulated distillation of high-boiling petroleum fractions by capillary supercritical fluid chromatography and vacuum thermal gravimetric analysis  

SciTech Connect

Capillary supercritical fluid chromatography (SFC) and vacuum thermal gravimetric analysis (VTGA) were utilized for simulated distillation (SIMDIS) of high-boiling petroleum fractions obtained by short-path vacuum distillation. The SFC method covers the approximate boiling range of 250-1400/sup 0/F. Under the present conditions, even 42% of a nondistillable, nondeasphalted residue was recovered from the column at a calculated 1426/sup 0/F atmospheric equivalent boiling point. The influence of temperature and pressure on resolution and retention was studied. SFC-SIMDIS was performed by using linear pressure programming at 100/sup 0/C, as compared to 400/sup 0/C+ temperatures required for comparable samples when capillary gas chromatography (GC) is employed. Polysiloxane-coated, 50-..mu..m-i.d. columns permitted fast analyses (30-min run time) yet maintained adequate resolution for SIMDIS analysis. VTGA-SIMDIS data of samples in the 500-1000/sup 0/F boiling range yielded excellent correlation with actual distillation data. However, thermal analysis revealed decomposition of samples at temperatures exceeding ca. 370/sup 0/C. The validity of the SFC method was demonstrated by comparing SFC-SIMDIS data with those obtained by GC and VTGA.

Schwartz, H.E.; Brownlee, R.G.; Boduszynski, M.M.; Su, F.

1987-05-15

234

Measurement of the melting point temperature of several lithium-sodium-beryllium fluoride salt (FLINABE) mixtures.  

SciTech Connect

The molten salt Flibe, a combination of lithium and beryllium flourides, was studied for molten salt fission reactors and has been proposed as a breeder and coolant for the fusion applications. 2LiF-BeF{sub 2} melts at 460 C. LiF-BeF{sub 2} melts at a lower temperature, 363 C, but is rather viscous and has less lithium breeder. In the Advanced Power Extraction (APEX) Program, concepts with a free flowing ternary molten salt for the first wall surface and blanket were investigated. The molten salt (FLiNaBe, a ternary mixture of LiF, BeF2 and NaF) salt was selected because a melting temperature below 350 C that would provide an attractive operating temperature window for a reactor application appeared possible. This information came from a Russian binary phase diagram and a US ternary phase diagram in the 1960's that were not wholly consistent. To confirm that a ternary salt with a low melting temperature existed, several combinations of the fluoride salts, LiF, NaF and, BeF{sub 2}, were melted in a small stainless steel crucible under vacuum. The proportions of the three salts were selected to yield conglomerate salts with as low a melting temperature as possible. The temperature of the salts and the crucible were recorded during the melting and subsequent re-solidification using a thermocouple directly in the salt pool and two thermocouples embedded in the crucible. One mixture had an apparent melting temperature of 305 C. Particular attention was paid to the cooling curve of the salt temperature to observe evidence of any mixed intermediate phases between the fully liquid and fully solid states. The clarity, texture, and thickness were observed and noted as well. The test system, preparation of the mixtures, and the melting procedure are described. The temperature curves for the melting and cooling of each of the mixtures are presented along with the apparent melting points. Thermal modeling of the salt pool and crucible was also done and is reported in a separate paper.

Boyle, Timothy J.; Troncosa, Kenneth P.; Nygren, Richard Einar; Lutz, Thomas Joseph; McDonald, Jimmie M.; Tanaka, Tina Joan; Ulrickson, Michael Andrew

2004-09-01

235

Statistical methods for change-point detection in surface temperature records  

NASA Astrophysics Data System (ADS)

We describe several statistical methods to detect possible change-points in a time series of values of surface temperature measured at a meteorological station, and to assess the statistical significance of such changes, taking into account the natural variability of the measured values, and the autocorrelations between them. These methods serve to determine whether the record may suffer from biases unrelated to the climate signal, hence whether there may be a need for adjustments as considered by M. J. Menne and C. N. Williams (2009) "Homogenization of Temperature Series via Pairwise Comparisons", Journal of Climate 22 (7), 1700-1717. We also review methods to characterize patterns of seasonality (seasonal decomposition using monthly medians or robust local regression), and explain the role they play in the imputation of missing values, and in enabling robust decompositions of the measured values into a seasonal component, a possible climate signal, and a station-specific remainder. The methods for change-point detection that we describe include statistical process control, wavelet multi-resolution analysis, adaptive weights smoothing, and a Bayesian procedure, all of which are applicable to single station records.

Pintar, A. L.; Possolo, A.; Zhang, N. F.

2013-09-01

236

Measurement Uncertainty of Dew-Point Temperature in a Two-Pressure Humidity Generator  

NASA Astrophysics Data System (ADS)

This article describes the measurement uncertainty evaluation of the dew-point temperature when using a two-pressure humidity generator as a reference standard. The estimation of the dew-point temperature involves the solution of a non-linear equation for which iterative solution techniques, such as the Newton-Raphson method, are required. Previous studies have already been carried out using the GUM method and the Monte Carlo method but have not discussed the impact of the approximate numerical method used to provide the temperature estimation. One of the aims of this article is to take this approximation into account. Following the guidelines presented in the GUM Supplement 1, two alternative approaches can be developed: the forward measurement uncertainty propagation by the Monte Carlo method when using the Newton-Raphson numerical procedure; and the inverse measurement uncertainty propagation by Bayesian inference, based on prior available information regarding the usual dispersion of values obtained by the calibration process. The measurement uncertainties obtained using these two methods can be compared with previous results. Other relevant issues concerning this research are the broad application to measurements that require hygrometric conditions obtained from two-pressure humidity generators and, also, the ability to provide a solution that can be applied to similar iterative models. The research also studied the factors influencing both the use of the Monte Carlo method (such as the seed value and the convergence parameter) and the inverse uncertainty propagation using Bayesian inference (such as the pre-assigned tolerance, prior estimate, and standard deviation) in terms of their accuracy and adequacy.

Martins, L. Lages; Ribeiro, A. Silva; Alves e Sousa, J.; Forbes, Alistair B.

2012-09-01

237

Effects of different methods of preparation of ice mantles of triple point of water cells on the temporal behaviour of the triple-point temperatures  

Microsoft Academic Search

We report results of an investigation of the temporal variation of the temperature of triple point of water (TPW) cells, in which the ice mantles were prepared by four different techniques using: (i) solid CO2, (ii) an immersion cooler, (iii) liquid-nitrogen-cooled rods, and (iv) liquid nitrogen (LN), first passing cold nitrogen vapours and then LN directly into the wells of

G T Furukawa; B W Mangum; G F Strouse

1997-01-01

238

Effects of different Methods of Preparation of Ice Mantles of Triple Point of Water Cells on the Temporal Behaviour of the Triple-Point Temperatures.  

National Technical Information Service (NTIS)

We report results of an investigation of the temporal variation of the temperature of triple point of water (TPW) cells, in which the ice mantles were prepared by four different techniques using: (1) solid carbon dioxide, (2) an immersion cooler, (3) liqu...

B. W. Mangum G. F. Strouse G. T. Furukawa

2008-01-01

239

Cryogenic Propellant Boil-Off Reduction System  

NASA Astrophysics Data System (ADS)

Lunar missions under consideration would benefit from incorporation of high specific impulse propellants such as LH2 and LO2, even with their accompanying boil-off losses necessary to maintain a steady tank pressure. This paper addresses a cryogenic propellant boil-off reduction system to minimize or eliminate boil-off. Concepts to do so were considered under the In-Space Cryogenic Propellant Depot Project. Specific to that was an investigation of cryocooler integration concepts for relatively large depot sized propellant tanks. One concept proved promising-it served to efficiently move heat to the cryocooler even over long distances via a compressed helium loop. The analyses and designs for this were incorporated into NASA Glenn Research Center's Cryogenic Analysis Tool. That design approach is explained and shown herein. Analysis shows that, when compared to passive only cryogenic storage, the boil-off reduction system begins to reduce system mass if durations are as low as 40 days for LH2, and 14 days for LO2. In addition, a method of cooling LH2 tanks is presented that precludes development issues associated with LH2 temperature cryocoolers.

Plachta, D. W.; Christie, R. J.; Carlberg, E.; Feller, J. R.

2008-03-01

240

A New Oftimal Control Strategy for a Nuclear Boiling Water Reactor  

Microsoft Academic Search

Application of optimal control theory to a boiling water nuclear reactor is the theme of this paper. The nonlinear model of the direct cycle 159 MW (th) Big Rock Point boiling water reactor derived on the basis of physical laws and empirical relations is linearized around an operating point and the model is verified against experimental results. The optimal control

M. Gopal; P. Pratapachandran Nair

1985-01-01

241

Enhanced Droplet Control by Transition Boiling  

PubMed Central

A droplet of water on a heated surface can levitate over a film of gas produced by its own evaporation in the Leidenfrost effect. When the surface is prepared with ratchet-like saw-teeth topography, these droplets can self-propel and can even climb uphill. However, the extent to which the droplets can be controlled is limited by the physics of the Leidenfrost effect. Here, we show that transition boiling can be induced even at very high surface temperatures and provide additional control over the droplets. Ratchets with acute protrusions enable droplets to climb steeper inclines while ratchets with sub-structures enable their direction of motion to be controlled by varying the temperature of the surface. The droplets' departure from the Leidenfrost regime is assessed by analysing the sound produced by their boiling. We anticipate these techniques will enable the development of more sophisticated methods for controlling small droplets and heat transfer.

Grounds, Alex; Still, Richard; Takashina, Kei

2012-01-01

242

Consistency of the National Realization of Dew-Point Temperature Using Standard Humidity Generators  

NASA Astrophysics Data System (ADS)

The comparison of two high-range standard humidity generators used by Instituto Nacional de Técnica Aeroespacial to realize dew-point temperature in the range from -10 °C to +95 °C has been performed using state-of-the art transfer standards and measurement procedures, over their overlapping range from -10 °C to +75 °C. The aim of this study is to investigate the level of agreement between the two generators, to determine any bias, and to quantify the level of consistency of the two realizations. The measurement procedures adopted to minimize the effect of the influence factors due to the transfer standards are described, and the results are discussed in the context of the declared calibration and measurement capabilities (CMCs).

Benyon, R.; Vicente, T.

2012-09-01

243

Fluctuation-Induced Heat Release from Temperature-Quenched Nuclear Spins near a Quantum Critical Point  

NASA Astrophysics Data System (ADS)

The quasi-two-dimensional quantum antiferromagnet Cr(diethylenetriamine)(O2)2.H2O [1] has a magnetic-field-tuned quantum critical point (QCP) at 12.3 T, where a highly polarized antiferromagnetic phase turns into a field-induced ferromagnetic phase. We report a novel relaxation phenomenon near this QCP: quantum-fluctuation-driven annealing of hydrogen nuclear spins frozen in a non-equilibrium high-energy state by temperature quenching. This relaxation phenomenon, with readily detectable heat release from the nuclear spins as they are annealed, reveals the extent of a quantum critical region around the QCP and provides a unique avenue to investigate the dynamics of the divergent quantum fluctuations that underlie quantum criticality. [1] C. M. Ramsey et al., Chem. Mater. 15, 92 (2003).

Kim, Y. H.; Kaur, N.; Atkins, B. M.; Dalal, N. S.; Takano, Y.

2010-03-01

244

Bubble point measurements of the system butane + octylbenzene in the temperature range 290--450 K  

SciTech Connect

As a part of research on nitrogen displacement in light-oil reservoirs, the phase behavior of mixtures of a model oil and nitrogen is studied. The model oil consists of methane, butane, and tetradecane or octylbenzene. For reliable phase behavior calculations in the multicomponent system at reservoir conditions -- about 370 K and 50 MPa in the North Sea -- measurements are needed of at least the binary sub-systems in the temperature and pressure range of interest, in order to determine binary interaction coefficients. Bubble points of butane + octylbenzene at eight different mole fractions have been determined at 290--440 K using the synthetic method. The raw experimental data have been fitted using the Peng-Robinson and the Soave-Redlich-Kwong equations of state in combination with a number of different mixing rules.

Leeuw, V.V. de; Poot, W.; Loos, T.W. de; Swaan Arons, J. de (Delft Univ. of Technology (Netherlands). Lab. of Applied Thermodynamics and Phase Equilibria)

1994-01-01

245

Geothermal point sources identified in a fumarolic ice cave on Erebus volcano, Antarctica using fiber optic distributed temperature sensing  

Microsoft Academic Search

Point sources of volcanic gas supply heat to the Erebus fumarolic ice cavesFlank degassing on Erebus is modulated by barometric pressureDTS is a useful, economical tool for monitoring low temperature fumaroles

Aaron Curtis; Philip Kyle

2011-01-01

246

Boiling incipience and convective boiling of neon and nitrogen  

Microsoft Academic Search

Forced convection and subcooled boiling heat transfer data for liquid nitrogen and liquid neon were obtained in support of a design study for a 30 tesla cryomagnet cooled by forced convection of liquid neon. The cryogen data obtained over a range of system pressures, fluid flow rates, and applied heat fluxes were used to develop correlations for predicting boiling incipience

S. S. Papell; R. C. Hendricks

1977-01-01

247

Results from Boiling Temperature Measurements for Saturated Solutions in the Systems NaCl + Ca(NO3)2 + H2O, NaNO3 + KNO3 + H2O, and NaCl + KNO3 + H2O, and Dry Out Temperatures for NaCl + NaNO3 + KNO3 + Ca(NO3)2 + H2O  

SciTech Connect

Boiling temperature measurements have been made for saturated ternary solutions of NaCl + KNO{sub 3} + H{sub 2}O and NaNO{sub 3} + KNO{sub 3} + H{sub 2}O at three selected salt ratios and for NaCl + Ca(NO{sub 3}){sub 2} + H{sub 2}O over the full composition range. The maximum boiling temperature found for the NaCl + Ca(NO{sub 3}){sub 2} + H{sub 2}O system is 164.7 {+-} 0.6 C, and the composition is estimated to occur at x(Ca(NO{sub 3}){sub 2}) {approx} 0.25. Experiments were also performed for the five component NaCl + NaNO{sub 3} + KNO{sub 3} + Ca(NO{sub 3}){sub 2} + H{sub 2}O mixtures with the molar ratio of NaCl:NaNO{sub 3}:KNO{sub 3} held essentially constant at 1:0.9780:1.1468 as the solute mole fraction of Ca(NO{sub 3}){sub 2}, x(Ca(NO{sub 3}){sub 2}), was varied between 0 and 0.25. The NaCl + NaNO{sub 3} + KNO{sub 3} + Ca(NO{sub 3}){sub 2} + H{sub 2}O system forms low melting mixtures and thus boiling temperatures for saturated were not determined. Instead, the temperatures corresponding to the cessation of boiling (i.e., dry out temperatures) of these liquid mixtures were determined. These dry out temperatures range from {approx} 300 C when x(Ca(NO{sub 3}){sub 2}) = 0 to {ge} 400 C when x(Ca(NO{sub 3}){sub 2}) = 0.20 and 0.25. The investigated mixture compositions correspond to some of the major mineral assemblages that are predicted to control the deliquescence relative humidity of salts formed by leaching dust samples from the proposed nuclear repository at Yucca Mountain, Nevada.

Rard, J A

2005-11-29

248

Boiling of droplets on a hot surface in low gravity  

Microsoft Academic Search

The boiling of single droplets of water and n-heptane on a hot stainless steel surface was observed in a low gravity environment, obtained on board a platform in free fall. Droplet impact was photographed using a single-shot flash-photographic method. Surface temperature variation during droplet impact was recorded using a fast-response thermocouple. Droplets could not be maintained in stable film boiling

Y. M. Qiao; S. Chandra

1996-01-01

249

SRM 1970: Succinonitrile Triple-Point Standard--A Temperature Reference Standard Near 58.08C.  

National Technical Information Service (NTIS)

Triple-point-of-succinonitrile cells have been tested and established as Standard Reference Material (SRM) 1970. Of the 115 cells tested, 109 were accepted as SRM 1970. Five of the 115 cells had triple-point temperatures lower than 58.0785 deg.C (the low-...

B. W. Mangum S. El-Sabban

1986-01-01

250

An Intercomparison of a Two-Pressure\\/Two-Temperature Frost Point Generator and Chilled Mirror Condensation Hygrometer  

Microsoft Academic Search

Dew point sensors are used in industry to detect the presence of small levels of water vapor. Critical measurements in compressed air, breathing air, metals processing, battery making, plastics processing, natural gas and petrochemical production require water vapor levels to remain in the 1- 6000 PPMv (parts per million by volume) or equivalent -76 to 0ºC Td (frost point temperature)

Ken Soleyn

251

Spectral and Total Effective Emissivity of a High-Temperature Fixed-Point Radiator Considered in Relation to the Temperature Drop Across its Back Wall  

NASA Astrophysics Data System (ADS)

In this article, calculations of the spectral and total cavity emissivity of a high-temperature fixed-point radiator by means of the Monte Carlo technique in conjunction with calculations of the temperature drop across its back wall using the finite-element approach are presented. The temperature drop across the back wall of a fixed-point cavity radiator is influenced by the heat exchange within the cavity and between the cavity and the front end of the associated furnace. The special effects of these influences were virtually neglected in earlier estimates of the temperature drop for high-temperature fixed-point radiators, resulting in an overestimation of the value of this parameter. These same effects have a non-negligible influence on the cavity emissivity. Even though the heat exchange between the furnace and cavity enhances the temperature uniformity within the cavity, it appears that the cavity cannot be assumed to be isothermal for the case considered, as is usually taken for granted when dealing with fixed-point cavity radiators. Since the temperature drop and total emissivity are affected by the same thermophysical processes, there exists a correlation between these parameters, which might find practical application. To provide experimental evidence to the findings inferred from the calculations, results of measurements of the cavity radiance-temperature of two high-temperature fixed-point cells are presented, enclosing an ingot of eutectic Re-C, for which the cavities are provided with different apertures. For ? = 650 nm, the measured differences in cavity radiance-temperature are shown to be compatible with the differences in radiance temperature calculated for these cavities.

Bloembergen, P.; Khlevnoy, B. B.; Jimeno Largo, P.; Yamada, Y.

2008-02-01

252

Temperature and thermo-optic coefficient measurements using optical fibre long period gratings operating at phase matching turning point  

NASA Astrophysics Data System (ADS)

The response of optical fibre long period gratings (LPGs), fabricated with precise control of the grating period to operate at or near the phase matching turning point (PMTP), to temperature was studied. The effect of the grating period on sensor performance was studied. The sensitivity of the LPG operating at the phase matching turning point to temperature was 0.99 nm/°C for 111.5 ?m grating period that is ca. 7 times higher than that of an LPG operating far from turning point. The possibility of using LPG sensors to determine the thermo-optic coefficient of the surrounding material was explored.

Korposh, S.; Wong, R.; James, S.; Tatam, R.

2013-05-01

253

Development of alternate cut-flower rose greenhouse temperature set-points based on calorimetric plant tissue evaluation  

Microsoft Academic Search

Energy utilization for heating is one of the most expensive greenhouse climate control operations. The temperature set-point is determined by many interrelated environmental, physiological, and economic factors but is fundamentally driven by the required growth rate of the plant or crop for quality and profitability. Temperatures are maintained to maximize production and affect timing of harvest of greenhouse-grown crops. In

Michael Raviv; Shlomit Medina; Ceasara Wendin; J. Heinrich Lieth

2010-01-01

254

Penalized Maximal F Test for Detecting Change Points of Temperature and Wind Speed Data Series  

NASA Astrophysics Data System (ADS)

The homogeneity of the climate record continues to receive considerable attention. Time series are commonly contaminated by non-climatic discontinuities that result from station relocations, observation time changes, and station specific trends related to environmental changes in the proximity of the observation sites. Several statistical methods have been proposed for detecting undocumented shifts. Wang Xiaolan et al. proposed the penalized maximal F test (PMFT) for detecting undocumented mean shifts that are not accompanied by any sudden change in the linear trend of time series. This method is based on the penalized maximal F test, which are embedded in a recursive testing algorithm, with the lag-1 autocorrelation (if any) of the time series being empirically accounted for. In this research the PMFT method is used for detecting the shifts of long time series of temperature and wind speed data series over China. The monthly average temperature data of about tens of meteorological observing stations and the annual average wind speed data of 753 meteorological observing stations have been detected. The results show that this homogeneity detection method works well for these two meteorological data series over China. 1. Results of monthly average temperature data series To create a reference time series is sometimes very useful for homogeneity detection, while it is difficult to get a good reference time series especially for the hundred-year long temperature data with a lot of year data lost over China. The PMFT method are used without building a references series to detecting the change points of the monthly average maximum temperature of twelve meteorological stations and the monthly average minimum temperature of twenty-nine stations. The results show that this method is fit for the homogeneous detection and we needn't interpolating the data and building a reference time series before the detection. Although discontinuities in temperature time series can be caused by any number of changes in, for example, sensor type, and even the observation schedule, station relocations are the likely cause of the majority of abrupt shifts identified in the temperature series evaluated here. 2. Results of annual average wind speed data series 52 of the data series are too short to be detected among 753 meteorological observing stations. A total of 356 change points over 271 stations are detected of the annual average wind speed time series, which accounts for 38.7% of the evaluated stations. The homogeneous data series are of 231 stations and another 199 stations are not significant that can be considered as homogeneous, which accounts for 61.3% of the evaluated stations. It is found that the data of 61.3% stations are homogeneity among the detected 701 stations, which shows that the homogeneity of the annual average wind speed is good. The change points of the annual average wind speed range from 1 to 2. The changes of instrument and location are the main reason for the non-homogeneity, while the change of the type of the observation instrument for the wind speed is the most important reason for the non-homogeneity of the annual average wind speed over China. The environment change seems not so remarkable, because the relocation and the instrument change may take place at the same time to conceal the effect of the environment change. All of the works we have done are the preliminary experiments of using this method. Although we get some results, there are still a lot of works need to do because the wind speed data are so special and the probability distribution are not the exact Gaussian distribution. At the same time the data of the wind speed are affected mostly by the topography and the barriers aside of the observation fields. The use of reference series can help to diminish departure from Gaussian distribution. We will do more experiments on detecting of the wind speed data. What the important thing is that rely on most detail metadata information to help the work of homogeneity detection.

Cao, L.; Liu, X.; Li, Q.

2009-04-01

255

Computational fluid dynamics simulations of jet fuel flow near the freeze point temperature  

NASA Astrophysics Data System (ADS)

Under low-temperature environmental conditions, the cooling of aircraft fuel results in reduced fluidity with the potential for freezing. Therefore, it is important to study the flow and heat transfer phenomena that occur in an aircraft fuel tank near the freeze point temperature of jet fuels. The purpose of this dissertation is to study the effects of low temperatures on the flow, heat transfer and freezing of commercial and military jet fuels. The research is accomplished with the help of computational models of a thermal simulator tank and a quartz duct. Experimental results with the thermal simulator tank show that fuel flowability and pumpability decrease substantially as temperature is reduced. Time-dependent temperature and velocity distributions were numerically simulated for static cooling. Measured properties were used in all the computational fluid dynamics simulations. The calculations show that stringers, ribs, and other structures strongly promote fuel cooling. Also, the cooler, denser fuel resides near the bottom surface of the fuel tank simulator. The presence of an ullage space within the tank was found to strongly influence the fuel temperature profile by sometimes reducing cooling from the upper surface. Moreover, since the presence of ullage space is an explosion risk, some military aircraft fuel tanks are fitted with explosion suppressant polyurethane foam. To study the effect of foam on the flowability and heat transfer inside the simulator tank, the wing tank thermal simulator was filled with military specified polyurethane foam. The tank was simultaneously drained and cooled and the mass flow rate results showed that flowability of the fuel is not affected by the presence of foam. However, the presence of foam certainly affected the heat transfer phenomenon inside the fuel tank when the simulator tank was cooled and drained simultaneously. To study the freezing behavior of jet fuel under forced flow conditions, a quartz duct was fabricated. The duct walls were cooled below the solidification temperatures of JP-8 and JPTS fuel samples. Freezing was also simulated using computational fluid dynamics, and the validity of the calculations was established by comparing them with experimental measurements. This work demonstrates that computational fluid dynamics techniques can potentially be used to predict fuel hold-up in aircraft fuel tanks. The effect of flow rate on solidification was also simulated, and it was found that lower flow rates result in relatively more solidification of the fuel than do higher flow rates. The simulations of the freezing behaviors of JP-8 and JPTS samples were found to have essentially the same value of morphology constant. However, the crystal structures of these two fuels were studied in experiments and were found to be very different. This shows the inability of the model to capture small-scale details like the crystal microstructure. However, this limitation is not fatal here because the focus is on the overall flow and freezing behavior of jet fuels. The model was successful in predicting the freezing behavior by comparing the calculated frozen area obtained by the model with the measured area.

Assudani, Rajee

256

Pulsatile fluidic pump performance at elevated temperatures  

Microsoft Academic Search

A series of tests were conducted to evaluate the performance of a pulsatile fluidic pump operating with simulated fuel solution at high temperatures. A computer program was written to model the performance of the system. Test results indicate little change in pump peformance at temperatues up to the boiling point of the solution. The computer model predicted pumping system performance

J. G. Morgan; W. D. Holland

1988-01-01

257

State-of-the-Art Overview of Boiling and Two-Phase Flows in Microchannels  

Microsoft Academic Search

A state-of-the-art overview of recent work on boiling and two-phase flows in microchannels are reviewed, focusing primarily on the high points of recent developments. The topics covered include critical heat fluxes and their prediction in microchannels, new two-phase flow pattern maps, flow regimes and visualization in microchannels, boiling phenomena and flow instabilities in multi-microchannel cooling elements, flow boiling prediction methods

John R. Thome

2006-01-01

258

Notched Three-Point Bend Testing of GFRP Woven Laminates at Cryogenic Temperatures and Analysis of Fracture and Damage Properties  

Microsoft Academic Search

The cryogenic damage and fracture properties of GFRP (glass fiber reinforced polymer) woven laminates has been investigated theoretically and experimentally. Three-point bend tests were carried out with SENB (single-edge-notched bend) specimens at room temperature, liquid nitrogen temperature and liquid helium temperature. SENB specimens with different widths and thicknesses were prepared and tested. The results of SENB specimens were compared with

K. Sanada; Y. Shindo

2006-01-01

259

Boiling incipience in a reboiler tube  

SciTech Connect

This heating surface and liquid temperature distributions were experimentally obtained to identify the boiling incipience conditions in a single vertical tube thermosiphon reboiler with water, acetone, ethanol, and ethylene glycol as test liquids. The test section was an electrically heated stainless steel tube of 25.56-mm i.d. and 1900 mm long. The uniform heat flux values were used in the range of 3800--40 000 W/m{sup 2}, while inlet liquid subcooling were varied from 0.2 to 45.5{degrees} C. The liquid submergence was maintained around 100, 75, 50 and 30%. All the data were generated at 1-atm pressure. The maximum superheats attained around boiling incipience were taken from the wall temperature distributions and correlated with heat flux and physical properties of liquids using the expression of Yin and Abdelmessih. The heated sections required for onset of fully developed boiling with net vapor generation were determined assuming a thermal equilibrium model. In this paper a dimensionless correlation relating these values with heat flux, liquid subcooling, and submergence is proposed.

Ali, H.; Alam, S.S. (Dept. of Chemical Engineering, Aligarh Muslim Univ., Aligarh 202 002 (IN))

1991-03-01

260

Temperature dependence of the point defect properties of GaN thin films studied by terahertz time-domain spectroscopy  

NASA Astrophysics Data System (ADS)

The dielectric functions of GaN for the temperature and frequency ranges of 10-300 K and 0.3-1 THz are obtained using terahertz time-domain spectroscopy. It is found that there are oscillations of the dielectric functions at various temperatures. Physically, the oscillation behavior is attributed to the resonance states of the point defects in the material. Furthermore, the dielectric functions are well fitted by the combination of the simple Drude model together with the classical damped oscillator model. According to the values of the fitting parameters, the concentration and electron lifetime of the point defects for various temperatures are determined, and the temperature dependences of them are in accordance with the previously reported result. Therefore, terahertz time-domain spectroscopy can be considered as a promising technique for investigating the relevant characteristics of the point defects in semiconductor materials.

Fang, HeNan; Zhang, Rong; Liu, Bin; Li, YeCao; Fu, DeYi; Li, Yi; Xie, ZiLi; Zhuang, Zhe; Zheng, YouDou; Wu, JingBo; Jin, BiaoBing; Chen, Jian; Wu, PeiHeng

2013-09-01

261

Development of a High-Temperature Coolant for Advanced Diesel Engines.  

National Technical Information Service (NTIS)

This study sought to develop a high-temperature coolant for future advanced military diesel engines capable of operating at high temperatures (up to 150 C). The desirable coolant for high-temperature application must have a high boiling point, a low freez...

I. S. Rhee

1984-01-01

262

SIMULATION OF OSCILLATIONS IN BOILING FLOW IN A NATURAL CIRCULATION EVAPORATOR  

Microsoft Academic Search

This article presents both experimental and theoretical investigations on the nature of oscillations of void fraction and temperature in a boiling natural circulation loop of a short-tube natural circulation evaporator at low pressure and low heat flux conditions. The experimental study includes online measurement of void fraction and temperature in the loop. The proposed moving boundary model equations for boiling

S. Paruya; P. Bhattacharya

2008-01-01

263

EFFECT OF GAS CONTENT ON ONB POINT FOR SANTOWAX OM + 30 w\\/o HB  

Microsoft Academic Search

The ONB (onset of nucleate boiling) point of Santowax OM I 30 wt% HB ; (high boilers) in forced convection was measured as a function of the dissolved ; nitrogen content at velocities of 5 and 30 ft\\/sec, pressures of 150 and 200 psig, ; and bulk temperatures of 650 and 700 deg F. The data were too meager to

C. E. Pocock; A. F. Lillie

1963-01-01

264

Branching points in the low-temperature dipolar hard sphere fluid  

NASA Astrophysics Data System (ADS)

In this contribution, we investigate the low-temperature, low-density behaviour of dipolar hard-sphere (DHS) particles, i.e., hard spheres with dipoles embedded in their centre. We aim at describing the DHS fluid in terms of a network of chains and rings (the fundamental clusters) held together by branching points (defects) of different nature. We first introduce a systematic way of classifying inter-cluster connections according to their topology, and then employ this classification to analyse the geometric and thermodynamic properties of each class of defects, as extracted from state-of-the-art equilibrium Monte Carlo simulations. By computing the average density and energetic cost of each defect class, we find that the relevant contribution to inter-cluster interactions is indeed provided by (rare) three-way junctions and by four-way junctions arising from parallel or anti-parallel locally linear aggregates. All other (numerous) defects are either intra-cluster or associated to low cluster-cluster interaction energies, suggesting that these defects do not play a significant part in the thermodynamic description of the self-assembly processes of dipolar hard spheres.

Rovigatti, Lorenzo; Kantorovich, Sofia; Ivanov, Alexey O.; Tavares, José Maria; Sciortino, Francesco

2013-10-01

265

Observed changes in relative humidity and dew point temperature in coastal regions of Iran  

NASA Astrophysics Data System (ADS)

The analysis of trends in hydroclimatic parameters and assessment of their statistical significance have recently received a great concern to clarify whether or not there is an obvious climate change. In the current study, parametric linear regression and nonparametric Mann-Kendall tests were applied for detecting annual and seasonal trends in the relative humidity (RH) and dew point temperature ( T dew) time series at ten coastal weather stations in Iran during 1966-2005. The serial structure of the data was considered, and the significant serial correlations were eliminated using the trend-free pre-whitening method. The results showed that annual RH increased by 1.03 and 0.28 %/decade at the northern and southern coastal regions of the country, respectively, while annual T dew increased by 0.29 and 0.15°C per decade at the northern and southern regions, respectively. The significant trends were frequent in the T dew series, but they were observed only at 2 out of the 50 RH series. The results showed that the difference between the results of the parametric and nonparametric tests was small, although the parametric test detected larger significant trends in the RH and T dew time series. Furthermore, the differences between the results of the trend tests were not related to the normality of the statistical distribution.

Hosseinzadeh Talaee, P.; Sabziparvar, A. A.; Tabari, Hossein

2012-12-01

266

Effect of anions on the cloud point temperature of aqueous poly(2-ethyl-2-oxazoline) solutions.  

PubMed

Poly(2-alkyl-2-oxazoline)s have recently gained attention in especially biological applications due to their lower critical solution temperature being close to the body temperature and their biocompatibility. The understanding of how cloud point temperature (T(c)) depends on the salt concentration and the molecular mechanisms responsible for such behavior are important to tune T(c) as desired by the applications. In this paper, we report the effect of a series of sodium salts on T(c) of aqueous poly(2-ethyl-2-oxazoline) (PEOX) solutions by dynamic light scattering. PEOX samples having four different molecular weights were investigated, and the results were compared with those of poly(N-isopropylacrylamide) (PNIPAM), the mostly investigated and used thermoresponsive polymer. Kosmotropic anions decreased T(c) linearly while chaotropic anions increased T(c) nonlinearly with salt concentration. The contributions of different mechanisms to T(c) change have been discussed. Our results indicate that the dominant mechanism is the dehydration of PEOX for divalent kosmotropic anions (CO(3)(2-), SO(4)(2-), S(2)O(3)(2-)) and direct binding for chaotropic anions (NO(3)(-), I(-), ClO(4)(-), SCN(-)). For the remaining monovalent kosmotropic anions (H(2)PO(4)(-), F(-), Cl(-), Br(-)), a combination of dehydration and surface tension mechanisms was in effect. The additional contribution of the surface tension mechanism for the monovalent kosmotropic anions was inferred for different molecular weight PEOX samples and also for PNIPAM. With PEOX molecular weight decreasing from 500,000 to 5000 g/mol, T(c) decreased less with salt concentration which was attributed to the contribution of the surface tension mechanism. For PEOX samples, the decrease of T(c) with kosmotropic anion concentration was faster compared to PNIPAM due to differences in their chemical structure. Our results show that the molecular mechanisms of interactions between PEOX chains and specific anions can simply be inferred from determination of T(c) by a common technique-dynamic light scattering. PMID:23181762

Tatar Güner, P?nar; Demirel, A Levent

2012-12-04

267

A novel role of three dimensional graphene foam to prevent heater failure during boiling.  

PubMed

We report a novel boiling heat transfer (NBHT) in reduced graphene oxide (RGO) suspended in water (RGO colloid) near critical heat flux (CHF), which is traditionally the dangerous limitation of nucleate boiling heat transfer because of heater failure. When the heat flux reaches the maximum value (CHF) in RGO colloid pool boiling, the wall temperature increases gradually and slowly with an almost constant heat flux, contrary to the rapid wall temperature increase found during water pool boiling. The gained time by NBHT would provide the safer margin of the heat transfer and the amazing impact on the thermal system as the first report of graphene application. In addition, the CHF and boiling heat transfer performance also increase. This novel boiling phenomenon can effectively prevent heater failure because of the role played by the self-assembled three-dimensional foam-like graphene network (SFG). PMID:23743619

Ahn, Ho Seon; Kim, Ji Min; Park, Chibeom; Jang, Ji-Wook; Lee, Jae Sung; Kim, Hyungdae; Kaviany, Massoud; Kim, Moo Hwan

2013-01-01

268

A Novel Role of Three Dimensional Graphene Foam to Prevent Heater Failure during Boiling  

NASA Astrophysics Data System (ADS)

We report a novel boiling heat transfer (NBHT) in reduced graphene oxide (RGO) suspended in water (RGO colloid) near critical heat flux (CHF), which is traditionally the dangerous limitation of nucleate boiling heat transfer because of heater failure. When the heat flux reaches the maximum value (CHF) in RGO colloid pool boiling, the wall temperature increases gradually and slowly with an almost constant heat flux, contrary to the rapid wall temperature increase found during water pool boiling. The gained time by NBHT would provide the safer margin of the heat transfer and the amazing impact on the thermal system as the first report of graphene application. In addition, the CHF and boiling heat transfer performance also increase. This novel boiling phenomenon can effectively prevent heater failure because of the role played by the self-assembled three-dimensional foam-like graphene network (SFG).

Ahn, Ho Seon; Kim, Ji Min; Park, Chibeom; Jang, Ji-Wook; Lee, Jae Sung; Kim, Hyungdae; Kaviany, Massoud; Kim, Moo Hwan

2013-06-01

269

Experimental study of surfactant effects on pool boiling heat transfer  

SciTech Connect

In the first part of this work, nucleate boiling of aqueous solutions of sodium lauryl sulfate (SLS) over relatively wide ranges of concentration and heat flux was carried out in a pool boiling apparatus. The experimental results show that a small amount of surface active additive makes the nucleate boiling heat transfer coefficient h considerably higher, and that there is an optimum additive concentration for higher heat fluxes. Beyond this optimum point, further increase in additive concentration makes h lower. In the second part of this work, nucleate boiling heat transfer rate for n-propanol-water binary mixtures with various amounts of sodium lauryl sulfate were measured in the same pool boiling apparatus. The importance of the mass diffusion effect, which is caused by preferential evaporation of the more volatile component at the vapor-liquid interface on the boiling of the binary mixture, has been confirmed. However, it is shown that the effect exerted by the addition of a surfactant dominates over the mass diffusion effect in dilute binary mixtures.

Ying Liang Tzan; Yu Min Yang (National Cheng Kung Univ., Tainan (Taiwan))

1990-02-01

270

Improvements in Predicting Void Fraction in Subcooled Boiling  

SciTech Connect

A simple two-phase thermal-hydraulic tool with the drift-flux model has been used to develop a subcooled boiling model. The tool is composed of four governing equations: mixture mass, vapor mass, mixture momentum, and mixture enthalpy. Using the developed tool, various subcooled boiling models were investigated through the published experimental data. In the process of evaluation, two models were developed associated with the subcooled boiling. First, the Saha and Zuber correlation predicting the point of the net vapor generation was modified to consider the thermal and dynamic effects at the high-velocity region. Second, the pumping factor model was developed using the pi-theorem based on parameters related to the bubble generation mechanism, and it produced an additional parameter: the boiling number. The proposed models and several other models were evaluated against a series of subcooled flow boiling experiments at the pressure range of 1 to 146.8 bars. From the root-mean-square analysis for the predicted void fraction in the subcooled boiling region, the results of the proposed model presented the best predictions for the whole-pressure ranges. Also, the implementation of the developed models into RELAP5/MOD3.3 brought about improved results compared to those of the default model of the code.

Ha, Kwi Seok [Korea Atomic Energy Research Institute (Korea, Republic of); Lee, Yong Bum [Korea Atomic Energy Research Institute (Korea, Republic of); No, Hee Cheon [Korea Advanced Institute of Science and Technology (Korea, Republic of)

2005-06-15

271

Research on temperature calibration of extended area blackbody based on two-point multi-section linear correction algorithm  

NASA Astrophysics Data System (ADS)

The spectral radiation of extended area blackbody source is widely used to provide a reference for absolute temperature in infrared test and calibration. Thus the temperature accuracy of extended area blackbody is a critical parameter to determine the performance of test and calibration system. The temperature of emissive surface is measured and controlled by Platinum resistance temperature sensor. A variety of techniques have been developed for improving the temperature accuracy of extended area blackbody. In order to overcome nonlinear error caused by the Platinum resistance temperature sensor, a calibration method based on two-point multi-section linear correction algorithm is proposed. The tests verify that the method enhances the calibration accuracy of temperature accuracy of extended area blackbody and satisfies the requirements of high precision tests on metrological quality.

Han, Shun-li; Hu, Wei-liang; Luo, Wen-jian; Wang, Rui-xia

2013-08-01

272

Investigation of transition boiling under conditions of unsteady cooling  

Microsoft Academic Search

In the present paper, a unified approximation function describing the time dependence of the wall temperature in the unsteady cooling of a solid body under conditions of successive transition from film (via transient) to bubble boiling is proposed. Expressions in the form of infinite series of the approximation parameters are derived for the heat flux density and the surface temperature.

I. I. Berlin; E. K. Kalinin; V. V. Kostiuk

1979-01-01

273

Route to Room-Temperature Superconductivity from a Practical Point of View  

Microsoft Academic Search

To synthesize a new superconductor which has a critical temperature, Tc, exceeding the room temperature, one needs to know what chemical components to start with. This chapter presents analysis of experimental data which allow one to draw a conclusion about components and the structure of a potential room-temperature superconductor. The two essential components of a room temperature superconductor are large

A. Mourachkine

2007-01-01

274

A novel method for the determination of the boiling range of liquid fuels by thermogravimetric analysis  

SciTech Connect

The most widely used separation technique in the petroleum industry as well as in much of the chemical industry is distillation. This is particularly true of all liquid fuel production processes, including coal-derived liquid fuels, and shale oil as well as petroleum. To design and operate a suitable distillation column system requires a knowledge of the boiling point distribution of the materials to be separated. In recognition of this need, the ASTM developed the classical distillation procedures of ASTM D86, D216, D447, D850, and D1078. Since these methods required a relatively large sample and are not particularly precise, the widely used simulated distillation analysis based on gas chromatography (ASTM D3710-83) was introduced. This method requires only a small sample size and is reasonably rapid. However, it is limited to materials boiling below about 350{degrees}C. Above that temperature the column packing becomes unstable and the materials being analyzed tend to crack. Also the results measured by the SimDis GC method are determined by the interactions between the tested sample and the selected column packing. Therefore the GC method is not fundamentally a determination of the boiling range of the sample mixture but rather a measure of the range of interactions of the sample with the packing. This report describes the evaluation of a vacuum distillate and resid to test the use of thermal gravimetric analysis.

Huang, He; Wang, Keyu; Wang, Shaojie [Univ. of Delaware, Newark, DE (United States)] [and others

1995-12-31

275

POOL BOILING OF HIGH-FREQUENCY CONDUCTORS  

SciTech Connect

This study presents development of a unique, powerful method for cooling high-frequency, AC conductors that can benefit end users of transformer windings, electrical machine windings, and magnet coils. This method of heat removal involves boiling a dielectric, fluorinert refrigerant that is in direct contact with litz wire conductors. A pool boiling test vessel is constructed, which provides for temperature control of the pool of fluorinert liquid. The test vessel is fitted with viewing ports so that the experiments are observed and studied with the aid of high-speed photography. Tests are performed on a variety of litz wire conductors. The boiling heat transfer coefficient is dependent on the conductor surface roughness. The size of the features on the conductor surface depends on the single-strand wire gage from which the conductor is constructed. All tests are performed with the conductors mounted horizontally. These tests are performed using a DC power supply. The results of these experiments will aid in the design of future cooling systems.

Wright, S. E. (Spencer E.); Konecni, S. (Snezana); Ammerman, C. N. (Curtt N.); Sims, J. R. (James R.)

2001-01-01

276

Flow boiling test of GDP replacement coolants  

SciTech Connect

The tests were part of the CFC replacement program to identify and test alternate coolants to replace CFC-114 being used in the uranium enrichment plants at Paducah and Portsmouth. The coolants tested, C{sub 4}F{sub 10} and C{sub 4}F{sub 8}, were selected based on their compatibility with the uranium hexafluoride process gas and how well the boiling temperature and vapor pressure matched that of CFC-114. However, the heat of vaporization of both coolants is lower than that of CFC-114 requiring larger coolant mass flow than CFC-114 to remove the same amount of heat. The vapor pressure of these coolants is higher than CFC-114 within the cascade operational range, and each coolant can be used as a replacement coolant with some limitation at 3,300 hp operation. The results of the CFC-114/C{sub 4}F{sub 10} mixture tests show boiling heat transfer coefficient degraded to a minimum value with about 25% C{sub 4}F{sub 10} weight mixture in CFC-114 and the degree of degradation is about 20% from that of CFC-114 boiling heat transfer coefficient. This report consists of the final reports from Cudo Technologies, Ltd.

Park, S.H. [comp.

1995-08-01

277

Heat transfer to boiling liquids in a single vertical tube thermosiphon reboiler  

Microsoft Academic Search

An experimental investigation of heat transfer to boiling liquids has been carried out on a single tube natural circulation reboiler. Experiments were performed with distilled water, methanol, benzene, toluene, and ethylene glycol to cover a wide range of boiling points and thermophysical properties. The heat transfer section consisted of an electrically heated stainless steel tube 25.56 mm I.D. and 1900

S. S. Alam

1995-01-01

278

Probability of Film Boiling Burnout.  

National Technical Information Service (NTIS)

The power of some SRP fuel assemblies is limited by the burnout safety factor (BOSF) in some applications. This power limitation is unnecessarily restrictive, because the current conservatism in predicting film boiling burnout is unusually large compared ...

R. H. Towell

1966-01-01

279

Flow Boiling and Condensation Experiment  

NASA Video Gallery

The Flow Boiling and Condensation Experiment is another investigation that examines the flow of a mixture of liquids and the vapors they produce when in contact with hot space system equipment. Cooling hot surfaces in these systems occur when cool liquids vaporize or boil when flowing past the hot surface. Scientists recognize the lack of understanding of the behavior of mixtures of liquids and their vapor flow in condensers and boilers in low gravity. This video shows condensation film in microgravity.

Kristine Rainey

2013-01-11

280

The Variation with Temperature of the Principal Elastic Moduli of NaCl near the Melting Point  

Microsoft Academic Search

The principal elastic moduli of single crystal rods of NaCl were measured over the temperature range 20°C to 804°C, the melting point. The measurements were carried out by means of a tripartite piezoelectric oscillator consisting of a quartz crystal driver, an intermediate fused silica bar, and the NaCl specimen. The shear constants C44 and (C11-C12) decrease nearly linearly with temperature,

Lloyd Hunter

1942-01-01

281

Thermal Characteristics of the NIST Fixed-Point Cells, Furnaces, and Maintenance Baths Over the Temperature Range from 83.8058 K to 1234.93K.  

National Technical Information Service (NTIS)

The optimal realization of an International Temperature Scale of 1990 (ITS-90) defining fixed-point temperature, for an accurate calibration of a (high-temperature) standard platinum resistance thermometer ((HT)SPRT), critically depends on the thermal cha...

G. F. Strouse G. T. Furukawa

2008-01-01

282

Hourly predictive Levenberg-Marquardt ANN and multi linear regression models for predicting of dew point temperature  

NASA Astrophysics Data System (ADS)

In this study, the ability of two models of multi linear regression (MLR) and Levenberg-Marquardt (LM) feed-forward neural network was examined to estimate the hourly dew point temperature. Dew point temperature is the temperature at which water vapor in the air condenses into liquid. This temperature can be useful in estimating meteorological variables such as fog, rain, snow, dew, and evapotranspiration and in investigating agronomical issues as stomatal closure in plants. The availability of hourly records of climatic data (air temperature, relative humidity and pressure) which could be used to predict dew point temperature initiated the practice of modeling. Additionally, the wind vector (wind speed magnitude and direction) and conceptual input of weather condition were employed as other input variables. The three quantitative standard statistical performance evaluation measures, i.e. the root mean squared error, mean absolute error, and absolute logarithmic Nash-Sutcliffe efficiency coefficient ( {| {{{Log}}({{NS}})} |} ) were employed to evaluate the performances of the developed models. The results showed that applying wind vector and weather condition as input vectors along with meteorological variables could slightly increase the ANN and MLR predictive accuracy. The results also revealed that LM-NN was superior to MLR model and the best performance was obtained by considering all potential input variables in terms of different evaluation criteria.

Zounemat-Kermani, Mohammad

2012-08-01

283

Vigilance system in rails for train hot point temperatures during circulation  

Microsoft Academic Search

Wheels, hubs and brake discs in a train during its circulation are under mechanical strains that make its temperature increase above the environment temperature. Mechanical defects in those elements produce an excessive friction and, as a consequence of it, an important increment of its temperature in relation to normal values. Detecting these anomalies is essential to avoid accidents and it

Francisco J. Meca Meca; Francisco J. Rodriguez Sanchez; Manuel Mazo Quintas; Juan J. Garcia Dominguez; Rafael Fonolla Navarro; Eduardo Sebastian Martinez; Jose A. Jimenez Calvo; Diego Lillo Rodriguez; Miguel A. Garcia Garrido

2000-01-01

284

Nonlinear dynamics in horizontal film boiling  

NASA Astrophysics Data System (ADS)

This work focuses on the thin vapor film which develops between an evaporating liquid and a solid heating surface during horizontal film boiling. In the absence of evaporative effects, the film is Rayleigh-Taylor unstable and releases a vapor bubble as it collapses. This instability is suppressed by evaporation. Two solution methods are used to study this problem. First, the long- wave approximation results in a strongly-nonlinear evolution equation which retains the leading-order effects of gravity, surface tension, van der Waals forces, evaporation and viscous flow in the vapor. When this simpler equation is no longer valid, a boundary element method follows the dynamics up to the point where the vapor bubble pinches-off from the film. In the isothermal case, the film is always unstable, and the minimum film thickness tends to zero. In saturated film boiling, the film is still unstable, but its thickness never drops below a minimum value, and liquid-solid contact is suppressed during the entire bubble-release cycle. In subcooled film boiling, there is a simple steady-state solution, a constant-thickness vapor film determined by a simple heat-conduction balance. This is linearly stable for large subcooling, and a bifurcation analysis determines a supercritical branch of stable, spatially-periodic solutions for weak van der Waals forces. Numerical methods extend this solution branch into the strongly-nonlinear regime revealing a hysteresis loop near the bifurcation point and a secondary bifurcation to a branch of travelling waves which is stable under certain conditions. For less subcooling, vapor bubbles develop, but their growth is slower, and the total heat transfer is higher than in the saturated case.

Panzarella, Charles Henry

1998-11-01

285

Blue light-emitting-diode-pumped point temperature sensor based on a fluorescence intensity ratio in Pr 3+ : ZBLAN glass  

Microsoft Academic Search

A fluorescence intensity ratio technique has been applied to Pr3+: ZBLAN glass, realising a point temperature sensor. We present data for a blue light emitting diode-pumped prototype which\\u000a provides accurate and self-referenced measurements.

Eric Maurice; Gerard Monnom; Greg W. Baxter; Scott A. Wade; Bill P. Petreski; Stephen F. Collins

1997-01-01

286

The intrinsic crossing point of the magnetization vs. temperature curves in superconducting cuprates in the high-magnetic-field limit  

Microsoft Academic Search

The crossing point of the magnetization vs. temperature curves that appears below Tc in highly anisotropic superconducting cuprates was measured in different compounds, with a different number, N, of superconducting CuO2 layers per periodicity length, s, and also with different values of s. By correcting the measurements from different extrinsic inhomogeneity effects through the Meissner fraction, it is demonstrated experimentally

J. Mosqueira; J. A. Campá; A. Maignan; I. Rasines; A. Revcolevschi; C. Torrón; J. A. Veira; F. Vidal

1998-01-01

287

Influence of impurities on the fixed-point temperature of zinc: estimations by the SIE method and practical limitations  

NASA Astrophysics Data System (ADS)

This publication deals with the practical challenge of describing the impurity influence on the fixed-point temperature of zinc. For this, the sum of individual estimate (SIE) approach is applied to miniaturized fixed-point cells (MFPC) filled with high-purity zinc that can be used in industrial applications. This includes comparative analyses by glow discharge mass spectroscopy as well as mass spectroscopy with inductive coupled plasma to quantify the impurity concentrations in zinc. Furthermore, the element-specific and concentration-dependent temperature deviations are presented for the fixed-point material zinc. For this, binary phase diagrams as well as thermal calculations and experimental data were analysed to extract the relevant sensitivity coefficients. Besides, results from SIE analyses of MFPCs are presented and their uncertainties are compared. On this basis, practical limits of the SIE method are identified and discussed.

Krapf, G.; Mammen, H.; Blumröder, G.; Fröhlich, T.

2012-07-01

288

Influence of Marangoni convection on pool boiling  

NASA Astrophysics Data System (ADS)

Heat transfer mechanisms operating in low-temperature pool boiling under microgravity are investigated, with particular attention to the role of surface-tension-driven convection (Marangoni convection). Results of numerical calculations with a model of a vapor bubble at a heated wall, as described by Zell and Straub (1989), showed that Marangoni convection is a significant contributing factor to the heat transfer under microgravity. The Marangoni convection is responsible for the transport of energy from the top of the bubble into the bulk of the fluid.

Vogel, B.; Straub, J.

1990-05-01

289

The initial freezing point temperature of beef rises with the rise in pH: a short communication.  

PubMed

This study tested the hypothesis that the initial freezing point temperature of meat is affected by pH. Sixty four bovine M. longissimus thoracis et lumborum were classified into two ultimate pH groups: low (<5.8) and high pH (>6.2) and their cooling and freezing point temperatures were determined. The initial freezing temperatures for beef ranged from -0.9 to -1.5°C (?=0.6°C) with the higher and lower temperatures associated with high and low ultimate pH respectively. There was a significant correlation (r=+0.73, P<0.01) between beef pH and freezing point temperature in the present study. The outcome of this study has implications for the meat industry where evidence of freezing (ice formation) in a shipment as a result of high pH meat could result in a container load of valuable chilled product being downgraded to a lower value frozen product. PMID:23410892

Farouk, M M; Kemp, R M; Cartwright, S; North, M

2013-01-11

290

Heat Transfer Coefficient Measurement Study of Several Film Boiling Modes in Subcooled He II  

SciTech Connect

This study was carried out for more detailed information about film boiling heat transfer in subcooled superfluid helium (He II). A number of film boiling modes were experimentally investigated in a wide range of the pressure from the atmospheric pressure down to the saturated vapor pressure. A thin stainless steel foil heater was used to cause film boiling and as a temperature sensor to measure the heater surface temperature. The results drawn from the heat transfer coefficient measurement give a support to the previous conclusion reached by visualization and pressure measurement studies that two film boiling modes appear in subcooled He II, that is the strongly subcooled film boiling mode and the weakly subcooled film boiling mode. It is, however, found that the dependence of the heat transfer coefficient on pressure was much different from those of conventional fluids. The heat transfer coefficient weakly decrease with the pressure in the weakly subcooled film boiling, and on the other hand it is almost independent of the pressure in the strongly film boiling. The peak of heat transfer coefficient appears at about 8 kPa in the transition region between the weakly subcooled and the noisy film boiling modes.

Takada, S.; Murakami, M.; Nozawa, M. [Graduate School of Systems and Information Engineering, University of Tsukuba, Tennodai 1-1-1, Tsukuba 305-8573 (Japan); Kimura, N. [Cryogenics Science Center, Applied Research Laboratory, High energy Accelerator Research Organization, Oho 1-1, Tsukuba 305-0801 (Japan)

2006-04-27

291

Electrical effects in measurements at the silver point using high temperature SPRTs  

NASA Astrophysics Data System (ADS)

In this work, measurements at the silver point using various types of HTSPRT are conducted, with a focus on finding a reliable thermal and electrical condition for an HTSPRT calibration. Sodium heat pipe furnaces, operating on DC power supply, are used. A platinum wire is bound to the graphite crucible of one of silver point cells used, through which a DC voltage bias can be provided. The effect of the DC voltage bias and of the heat pipe ground-connection to the HTSPRT reading at silver point is evaluated. Cell comparisons are also performed at various ground-connection conditions. A method for estimating the uncertainty due to such effect in an HTSPRT calibration at silver point is proposed.

Widiatmo, J. V.; Harada, K.; Yamazawa, K.; Tamba, J.; Arai, M.

2013-09-01

292

VERIFICATION AND VALIDATION OF ONE DIMENSIONAL MODELS USED IN SUBCOOLED FLOW BOILING ANALYSIS  

Microsoft Academic Search

Subcooled flow boiling occurs in many industrial applications and it is characterized by large heat transfer coefficients. However, this efficient heat transfer mechanism is limited by the critical heat flux, where the heat transfer coefficient decreases leading to a fast heater temperature excursion, potentially leading to heater melting and destruction. Subcooled flow boiling is especially important in water-cooled nuclear power

Francisco A. Braz Filho; Alexandre D. Caldeira; Eduardo M. Borges

293

46 CFR 154.709 - Cargo boil-off as fuel: Gas detection equipment.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 false Cargo boil-off as fuel: Gas detection equipment. 154...VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and...Pressure and Temperature Control § 154.709 Cargo boil-off as fuel: Gas detection equipment....

2010-10-01

294

46 CFR 154.709 - Cargo boil-off as fuel: Gas detection equipment.  

Code of Federal Regulations, 2010 CFR

...2009-10-01 false Cargo boil-off as fuel: Gas detection equipment. 154...VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and...Pressure and Temperature Control § 154.709 Cargo boil-off as fuel: Gas detection equipment....

2009-10-01

295

Influence of sintering on deposit formation during pool boiling of calcium sulphate solutions  

Microsoft Academic Search

The objective of this work is to determine the influence of sintering effects on crystalline deposits formed during pool boiling of CaSO4 solutions. Fouling experiments have been performed with plain tubes where the surface temperature of the heating element was varied to investigate its effect on boiling and crystallisation. Samples of the deposit layers were removed at the end of

M. Esawy; M. S. Abd-Elhady; M. R. Malayeri; H. Müller-Steinhagen

2010-01-01

296

RUBI -a Reference mUltiscale Boiling Investigation for the Fluid Science Laboratory  

Microsoft Academic Search

Boiling is a two-phase heat transfer process where large heat fluxes can be transferred with small driving temperature differences. The high performance of boiling makes the process very interesting for heat transfer applications and it is widely used in industry for example in power plants, refrigeration systems, and electronics cooling. Nevertheless, due to the large number of involved phenomena and

Nils Schweizer; Marco Stelzer; Olaf Schoele-Schulz; Gerold Picker; Hans Ranebo; Jan Dettmann; Olivier Minster; Balazs Toth; Josef Winter; Lounes Tadrist; Peter Stephan; Walter Grassi; Paolo di Marco; Catherine Colin; Gian Piero Celata; John Thome; Oleg Kabov

2010-01-01

297

Multi-point local temperature measurements inside the conducting plates in turbulent thermal convection  

NASA Astrophysics Data System (ADS)

An experimental study of local temperature statistics in turbulent thermal convection is presented. The emissions of plumes and plume clusters are detected by an array of thermistors embedded in the top and bottom plates of a 1 m diameter convection cell. We found that the product S_TS_{T'} of the temperature skewness S_T and the skewness of the temperature time derivative S_{T'} from the embedded thermistors may be used as a measure of the intensity of plume emissions and that S_TS_{T'} exhibits a pattern that corresponds well to the orientation of the large-scale circulation in the convecting flow. This is despite the fact that the temperature distribution across the plates is highly uniform, as indicated by the mean temperature of the embedded thermistors. By comparing the spatial distributions of S_TS_{T'} and of the RMS temperature sigma, we further find that the maximum temperature fluctuations take place in regions dominated by plume mixing instead of regions of plume emission. It is also found that temperature fluctuations inside the conducting plates have the same statistical and scaling properties as those in the cell centre.

Sun, Chao; Xia, Ke-Qing

298

Study on the melting and freezing behaviour of high temperature binary eutectic fixed points using differential scanning calorimetry  

NASA Astrophysics Data System (ADS)

We have measured the heat flux accompanying the melting or freezing of metal (or metalloid)-carbon eutectics, using differential scanning calorimetry (DSC) to identify appropriate binary systems for secondary thermometry fixed points. Well-known alloy systems such as Fe-C and Ni-C showed reproducible endothermic and exothermic peaks that represent melting and freezing reactions in the DSC measurement. Furthermore, a new Si-C system with a eutectic composition showed reproducible melting and freezing peaks in the DSC measurements. Based on the results by DSC, we identified the Si-SiC eutectic point as a possible eutectic fixed point. To confirm this possibility, we made a Si-SiC cell for thermocouple thermometry and measured its melting and freezing characteristics using a Pt/Pd thermocouple. The melting temperature of the Si-SiC eutectic was reproducible to within 0.02 °C (one standard deviation). From the results, we found that Si-SiC has possibility as a new eutectic fixed point at temperatures around 1400 °C. We also concluded that DSC analysis could be used to measure the reproducibility of freezing and melting reactions that are to be used as fixed points for thermometry, because it is a rapid and easy-to-use tool for characterizing the thermal behaviour of materials with only a small sample.

Kwon, Su Yong; Kim, Yong-Gyoo; Yang, Inseok

2010-06-01

299

High-transition-temperature superconducting quantum interference devices  

Microsoft Academic Search

The advent of high-Tc superconductors gave great impetus to the development of thin-film superconducting quantum interference devices (SQUIDs) for operation at temperatures up to the boiling point of liquid nitrogen, 77 K. The spectral density of the white flux noise can be calculated analytically for rf SQUIDs and by computer simulation for dc SQUIDs; however, observed noise spectral densities are

D. Koelle; R. Kleiner; F. Ludwig; E. Dantsker; John Clarke

1999-01-01

300

Dependence of the Q 10 values on the depth of the soil temperature measuring point  

Microsoft Academic Search

The parameter Q10 is commonly used to express the relationship between soil CO2 efflux and soil temperature. One advantage of this parameter is its application in a model expression of respiration losses\\u000a of different ecosystems. Correct specification of Q10 in these models is indispensable. Soil surface CO2 efflux and soil temperature at different depths were measured in a 21-year-old Norway

Marian Pavelka; Manuel Acosta; Michal V. Marek; Werner Kutsch; Dalibor Janous

2007-01-01

301

Variation of Film Boiling Modes in He II from Strongly to Weakly Subcooled States  

SciTech Connect

Film boiling modes in both subcooled and saturated superfluid helium (He II) were experimentally investigated. The visual observation and the transient pressure and temperature measurements were performed to extract some characteristics of each boiling mode. The classification of all four film boiling modes, strongly subcooled and weakly subcooled modes in subcooled He II (He IIp) and noisy and silent film boiling modes in saturated He II (He IIs), was drawn on the boiling mode map. It was found from the heater temperature measurement that the boiling heat transfer is enhanced in the weakly subcooled mode compared with in the strongly subcooled mode. In the weakly subcooled mode, the vapor behavior is much activated by the instability in vapor-liquid interface. The boundary region between the strongly and the weakly subcooled modes becomes thick as the rise of He II temperature or the increase of the heat flux. The noisy film boiling does not occur at the pressure above 9 kPa, though it appears at the pressure above p{lambda}. It is found that in the region adjacent to the lambda line He I film boiling mode occurs even in He II.

Nozawa, M.; Murakami, M.; Takada, S. [Graduate School of Systems and Information Engineering, University of Tsukuba, Tennodai 1-1-1, Tsukuba, 305-8573 (Japan); Kimura, N. [Cryogenics Science Center, Applied Research Laboratory, High Energy Accelerator Research Organization, Oho 1-1, Tsukuba, 305-0801 (Japan)

2006-04-27

302

Comparisons of temperature, pressure and humidity measurements by balloon-borne radiosondes and frost point hygrometers during MOHAVE 2009  

NASA Astrophysics Data System (ADS)

We compare coincident, balloon-borne, in situ measurements of temperature and pressure by two radiosondes (Vaisala RS92, Intermet iMet-1-RSB) and measurements of relative humidity (RH) by Vaisala RS92 sondes and frost point hygrometers. Data from a total of 28 balloon flights with mixed payloads are analyzed in 1-km altitude bins to quantify measurement biases between sensors and how they vary with altitude. The disparities between sensors determined here are compared to measurement uncertainties quoted by the two radiosonde manufacturers. Our comparisons expose several flight profiles with anomalously large measurement differences. Excluding these anomalous profiles, 33 % of RS92-iMet median temperature differences exceed the uncertainty limits calculated from manufacturer-quoted uncertainties. A statistically significant, altitude-independent bias of about 0.5 ± 0.2 °C is revealed for the RS92-iMet temperature differences. Similarly, 23 % of RS92-iMet median pressure differences exceed the quoted uncertainty limits, with 83 % of these excessive differences above 16 km altitude. The pressure differences are altitude dependent, increasing from -0.6 ± 0.9 hPa at the surface to 0.7 ± 0.1 hPa above 15 km. Temperature and pressure differences between redundant RS92 sondes on the same balloon exceed manufacturer-quoted reproducibility limits 20 % and 2 % of the time, respectively, with most of the excessive differences belonging to anomalous difference profiles. Relative humidity measurements by RS92 sondes are compared to other RS92 sondes and to RH values calculated using frost point hygrometer measurements and coincident radiosonde temperature measurements. For some flights the RH differences are anomalously large, but in general are within the ±5 % RH measurement uncertainty limits quoted for the RS92. The quantitative effects of RS92 and iMet pressure and temperature differences on frost point-based water vapor mixing ratios and RH values, respectively, are also presented.

Hurst, D. F.; Hall, E. G.; Jordan, A. F.; Miloshevich, L. M.; Whiteman, D. N.; Leblanc, T.; Walsh, D.; Vömel, H.; Oltmans, S. J.

2011-07-01

303

Enhancement of pool boiling from a vertical rod using guide disks  

SciTech Connect

This report provides experimental and theoretical investigation of the boiling process which used a system of evenly spaced disks to constrain the path of bubbles from point origin to point of collapse. The experiments identified five distinct heat-transfer regimes, two of which (flange and strobe) are unique to this geometry and cannot be explained by conventional heat-transfer correlations. Bubble and wave models developed for flange and strobe boiling, respectively, predict these phenomena with reasonable success.

Whitehouse, J.C.

1992-01-01

304

Enhancement of pool boiling from a vertical rod using guide disks  

SciTech Connect

This report provides experimental and theoretical investigation of the boiling process which used a system of evenly spaced disks to constrain the path of bubbles from point origin to point of collapse. The experiments identified five distinct heat-transfer regimes, two of which (flange and strobe) are unique to this geometry and cannot be explained by conventional heat-transfer correlations. Bubble and wave models developed for flange and strobe boiling, respectively, predict these phenomena with reasonable success.

Whitehouse, J.C.

1992-11-01

305

Impurity concentration behaviors in a boiling tubesheet crevice  

Microsoft Academic Search

The impurity concentration behavior of a boiling crevice packed with magnetite particles was investigated with thermocouples and electrodes for the measurement of temperature and electrochemical corrosion potential (ECP), respectively, in order to understand chemical change in a pressurized water reactor (PWR) steam generator (SG) crevice. A secondary solution composed of 50ppm Na and 200ppb hydrogen was supplied at a flow

Chi Bum Bahn; Si Hyoung Oh; Byung Gi Park; Il Soon Hwang; In Hyoung Rhee; Uh Chul Kim; Jung Won Na

2003-01-01

306

Assessment of RETRAN-3D Boiling Models Against Experimental Subcooled Boiling Tube Data  

SciTech Connect

Subcooled and saturated nucleate boiling are important physical processes in boiling water reactors (BWRs) under operating and transient conditions and in pressurized water reactors (PWRs) under transient conditions. Good predictions of such processes by system codes such as RETRAN-3D are, therefore, important from a safety and operational point of view.For this reason, and continuing the validation efforts carried out in the STARS Project at Paul Scherrer Institute, data from experiments in a uniformly heated tube carried out by Bartolomey et al. have been used to assess the subcooled and saturated nucleate boiling models in RETRAN-3D. These experiments were performed at high ({approx}15-MPa) and medium ({approx}7-, 4-, and 3-MPa) pressures. The heat flux (2210 to 420 kW/m{sup 2}) and mass flux (2123 to 405 kg/s m{sup 2}) were selected to cover a range of values spanning operating and transient situations in both BWRs and PWRs.This paper reports on the results obtained with both the four- and five-equation RETRAN-3D flow models. The results show that both models used in RETRAN-3D provide good estimates of subcooled and saturated nucleate boiling in heated tubes. The four-equation model, which makes use of the Electric Power Research Institute void fraction profile fitting model for the reactivity feedback only, shows the best performance for high mass fluxes, whereas the five-equation model, which directly computes the vaporization rate, performs better at low mass fluxes and relatively high heat fluxes.In addition to the results from RETRAN-3D, results obtained with the system code RELAP-5 are included in the plots and used to support the conclusions and to perform a comparative analysis of the methods used by the codes.

Macian, Rafael; Coddington, Paul; Stangroom, Paul [Paul Scherrer Institute (Switzerland)

2003-04-15

307

Measuring of temperatures of phase objects using a point-diffraction interferometer plate made with the thermocavitation process  

NASA Astrophysics Data System (ADS)

An optical system formed by four point-diffraction interferometers is used for measuring the refractive index distribution of a phase object. The phase of the object is assumed enough smooth to be computed in terms of the Radon Transform and it is processed with a tomographic iterative algorithm. Then, the associated refractive index distribution is calculated. To recovery the phase from the inteferograms we use the Kreis method, which is useful for interferograms having only few fringes. As an application of our technique, the temperature distribution of a candle flame is retrieved, this was made with the aid of the Gladstone-Dale equation. We also describe the process of manufacturing the point-diffraction interferometer (PDI) plates. These were made by means of the thermocavitation process. The obtained three dimensional distribution of temperature is presented.

Aguilar, Juan C.; Berriel-Valdos, L. R.; Aguilar, J. Felix; Mejia-Romero, S.

308

An InGaAs detector based radiation thermometer and fixed-point blackbodies for temperature scale realization at NIM  

NASA Astrophysics Data System (ADS)

In this paper, we describe an InGaAs detector based radiation thermometer (IRT) and new design of fixed-point blackbodies, including Sn, Zn, Al and Cu, for the establishment of a temperature scale from 200 °C to 1085 °C at the National Institute of Metrology of China. The construction and calibration of the IRT with the four fixed-point blackbodies are described. Characteristics of the IRT, such as the size-of-source effect, the amplifier performance and its stability are determined. The design of the four fixed-points, with 10 mm diameter of aperture and 0.9999 emissivity, is described. The uncertainty of the scale realization is elaborated.

Hao, X.; Yuan, Z.; Wang, J.; Lu, X.

2013-09-01

309

Comparisons of temperature, pressure and humidity measurements by balloon-borne radiosondes and frost point hygrometers during MOHAVE 2009  

Microsoft Academic Search

We compare coincident, balloon-borne, in situ measurements of temperature and pressure by two radiosondes (Vaisala RS92, Intermet iMet-1-RSB) and measurements of relative humidity (RH) by Vaisala RS92 sondes and frost point hygrometers. Data from a total of 28 balloon flights with mixed payloads are analyzed in 1-km altitude bins to quantify measurement biases between sensors and how they vary with

D. F. Hurst; E. G. Hall; A. F. Jordan; L. M. Miloshevich; D. N. Whiteman; T. Leblanc; D. Walsh; H. Vömel; S. J. Oltmans

2011-01-01

310

Temperature-plant pigment-optical relations in a recurrent offshore mesoscale eddy near Point Conception, California  

Microsoft Academic Search

The temperature-plant pigment-optical structure of a mesoscale anticyclonic eddy consistently found in shipboard surveys and satellite-sensed data several hundred kilometers southwest of Point Conception, California, is described on three different time scales (100-day mesoscale, annual, and several-year). The satellite coastal zone color scanner (CZCS) ocean color imagery detected the near-surface chlorophyll structure of the eddy, but in situ optical and

James J. Simpson; Chester J. Koblinsky; José Pelaez; Loren R. Haury; David Wiesenhahn

1986-01-01

311

Zero-point spin deviations and critical temperatures of the A-, C- and G-type antiferrimagnets  

Microsoft Academic Search

The Green function analysis of the zero-point spin deviation and the critical temperature has been performed for the A-, C- and G-type antiferrimagnets, and the numerical results are compared with those of the NaCl-type antiferromagnet. The author wishes to express his thanks to Professor N. Uryû and Dr. I. Kimura for their helpful discussions and critical readings of the manuscript.

T. Idogaki

1976-01-01

312

Development of a Multi-Point Pyrometer System (MPPS) for measuring surface temperature and emissivity  

SciTech Connect

In support of the US DOE MHD research program, the Diagnostic Instrumentation and Analysis Laboratory (DIAL) has been actively engaged in developing and applying advanced optical diagnostic techniques and instrumentation systems to high temperature coal-fired gas streams for over a decade. One of the earliest diagnostic systems developed by DIAL was a two color pyrometer (TCP). In this system, two commercial single-color pyrometers and a microprocessor system were used to form a TCP which can make accurate measurements of surfaces of unknown emissivity and temperature. This system has been used extensively to make measurements in support of the national MHD program. This report describes this system.

Benton, R.D.; Jang, Ping-Rey

1993-06-01

313

Advances in Enhanced Boiling Heat Transfer From Electronic Components  

NASA Astrophysics Data System (ADS)

This paper reviews recent advances in enhancing boiling heat transfer from electronic components immersed in dielectric liquids by use of surface microstructures. The microstructures developed include rough surfaces produced by sanding, vapor blasting hard particles, sputtering of SiO2 followed by wet etching of the surface, chemical vapor deposition of SiO2 film etc., laser-drilled cavities, a brush-like structure (dendritic structure), reentrant and micro-reentrant cavities, microfins, and porous structures fabricated by alumina particle spraying and painting of silver flakes, diamond particles, aluminum particles and copper particles. Heat sink studs with drilled holes, microfins, multi-layered micro-channels and pores, and pin fins with and without microporous coating have also been developed. The height of microstructure ranges from 0 to 12mm. The primary issues discussed are the mitigation of temperature overshoot at boiling incipience, enhancement of nucleate boiling heat transfer and increasing the critical heat flux.

Honda, Hiroshi; Wei, Jinjia

314

Pool boiling on a large horizontal flat resistance heater  

NASA Astrophysics Data System (ADS)

Results are presented of experiments on n-pentane/Freon-113 system, carried out to investigate the film-transition boiling region where liquid-solid contacts contribute significantly to the local heat flux, using a large flat horizontal resistance heater mounted on a ceramic insulating substrate. After steady film boiling was reached, the heat flux was decreased and recorded simultaneously with the temperature measured by thermocouples attached to the lower side of the heater surface. It is shown that the observed data on the quasi-linear film boiling regime are better represented by Berenson's (1960) correlation than by Klimenko's (1981) correlation. Burnout values measured for Freon-113 compared reasonably well to available correlations for the flat plate geometry.

Reguillot, F.; Witte, L.; Lienhard, J.; Poniewski, M.

1992-08-01

315

Occurrence of extremely low cold point tropopause temperature during summer monsoon season: ARMEX campaign and CHAMP and COSMIC satellite observations  

NASA Astrophysics Data System (ADS)

Extreme low cold point tropopause (CPT) temperatures (T ? 191 K) are often observed during the monsoon season over the Bay of Bengal (BOB) and adjoining areas. This paper reports frequent occurrences of extreme low CPT temperature over the Arabian Sea (AS) and adjoining areas using radiosonde observations during the Arabian Sea Monsoon Experiment (ARMEX) from 24 June to 15 August 2002. Day-to-day variations in temperature at CPT and at the 100 hPa level observed during the ARMEX campaign show modulation by the wave activity with a period of ˜15 days, and it is observed to be closely associated with the Tropical Easterly Jet (TEJ). Characteristics of wave modulating the temperature at the CPT and at the 100 hPa level are brought out and discussed. Spatial and temporal distribution of low CPT temperature over a wide scale is examined using CHAMP and COSMIC satellite temperature data. These observations show occurrences of low CPT temperatures during the early period of the monsoon season over BOB, AS, and adjoining areas, which often extend to Africa's Horn region. An enhanced low CPT temperature occurrence during the early part of the monsoon appears to be due to the modulation of outgoing long wave-radiation (OLR), CPT temperature, and height by intraseasonal oscillation. Modulation of CPT by intraseasonal oscillation suggests that this oscillation could contribute to dehydration of the lower stratosphere. In addition, a close association is noted between the seasonal variations of the latitude of low CPT temperature and low OLR, which is similar to the anticipated seasonal movement of the Intertropical Convergence Zone (ITCZ).

Jain, A. R.; Panwar, Vivek; Johny, C. J.; Mandal, T. K.; Rao, V. R.; Gautam, Rishu; Dhaka, S. K.

2011-02-01

316

Boiling heat transfer in compact heat exchangers  

SciTech Connect

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

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

1994-12-31

317

"Sand Boil" on Bay Bridge  

USGS Multimedia Gallery

"Sand boil" or sand volcano measuring 2 m (6.6 ft) in length erupted in median of Interstate Highway 80 west of the Bay Bridge toll plaza when ground shaking transformed loose water-saturated deposit of subsurface sand into a sand-water slurry (liquefaction). Vented sand contains-marine shell f...

2009-01-26

318

Thermosyphon boiling in vertical channels  

Microsoft Academic Search

The thermal characteristics of ebullient cooling systems for VHSIC and VLSI microelectronic component thermal control are studied by experimentally and analytically investigating boiling heat transfer from a pair of flat, closely spaced, isoflux plates immersed in saturated water. A theoretical model for liquid flow rate through the channel is developed and used as a basis for correlating the rate of

A. Bar-Cohen; H. Schweitzer

1983-01-01

319

Boiling liquid engine cooling system  

Microsoft Academic Search

A boiling liquid cooling system is described for an engine, comprising: means defining in the engine a coolant jacket into which coolant is introduced in liquid state and from which coolant is discharged in gaseous state; a radiator into which gaseous coolant from the coolant jacket is introduced to be liquified; an electric pump for pumping the coolant thus liquified

N. Miura; Y. Hayashi

1987-01-01

320

Room-temperature ferromagnetism in graphite driven by two-dimensional networks of point defects  

Microsoft Academic Search

Understanding the mechanism of ferromagnetism in carbon-based materials, which contain only s and p electrons in contrast to traditional ferromagnets based on 3d or 4f electrons, is challenging. Here, we demonstrate direct evidence for ferromagnetic order locally at defect structures in highly oriented pyrolytic graphite (HOPG) with magnetic force microscopy and in bulk magnetization measurements at room temperature. Magnetic impurities

J. ?ervenka; M. I. Katsnelson; C. F. J. Flipse

2009-01-01

321

Coherent anti-stokes Raman spectroscopy system for point temperature and major species concentration measurement  

SciTech Connect

The Coherent anti-Stokes Raman Spectroscopy system (CARS) has been developed as a laser-based, advanced, combustion-diagnostic technique to measure temperature and major species concentration. Principles of operation, description of the system and its capabilities, and operational details of this instrument are presented in this report.

Singh, J.P.; Yueh, Fang-Yu

1993-10-01

322

On the Curie points and high temperature susceptibilities of Heisenberg model ferromagnetics  

Microsoft Academic Search

The first six coefficients in the expansion of the susceptibility ?, and its inverse, ? , in ascending powers of the reciprocal temperature, have been determined for the Heisenberg model of a ferromagnetic, for any spin value, S, and any lattice. The first five coefficients appropriate to the magnetic specific heat, C, have also been found. For the body-centred and

G. S. Rushbrooke; P. J. Wood

1958-01-01

323

Effect of inclination on film boiling  

Microsoft Academic Search

The object of this paper is to present and discuss the experimental data obtained for the transfer of heat under film boiling conditions from flat surfaces at various orientations. The test fluid for all cases was nitrogen. The boiling surfaces were electrically heated Inconel plates. Film boiling performance has been obtained for a heated flat surface oriented with respect to

H. J. Sauer Jr.; S.-C. Lin

1974-01-01

324

ON THE STABILITY OF BOILING HEAT TRANSFER  

Microsoft Academic Search

Boiling heat transfer in the nucleate region is reviewed. The ; transition film-boiling region is analyzed by considering the stability of a ; plane vortex sheet separating two inviscid fluids. Using the classical results ; of Helmholtz Kelvan and Rayleigh expressions have been derived that predict the ; maximum and minimum heat-transfer rates in the nucleate and the film-boiling ;

N. Zuber

1958-01-01

325

Boiling kinetics of superheated liquid helium-4  

SciTech Connect

This paper studies the superheat of liquid helium /sup 4/He by the method of measurement of mean lifetimes in a pure bubble chamber. The experimental setup and methods of measurements are described. This method allowed the authors to observe the temperature dependence of nucleation rate at a fixed pressure. Measurements were carried out in the pressure range from 0.50 to 1.20 atm. The temperatures of attainable superheat were compared with the Doering-Volmer homogeneous nucleation theory and with the experimental data obtained by the pulse method and the method of continuous isobaric heating by other investigators. Two peculiarities of boiling of superheated liquid helium have been revealed and interpreted. The influence of electron bubbles, the dependence of surface tension on the curvature of interface, and ionizing background radiation on nucleation kinetics are discussed.

Semenova, N.M.; Ermakov, G.V.

1989-01-01

326

A Time-Domain Sub-Micro Watt Temperature Sensor With Digital Set-Point Programming  

Microsoft Academic Search

To realize the on-chip temperature monitoring of VLSI circuits, an accurate time-domain low-power CMOS thermostat based on delay lines is proposed. Contrary to the voltage-domain predecessors, the proposed circuit can benefit from the performance enhancement due to the scaling down of fabrication processes. By replacing R-string voltage division and voltage comparator with delay line time division and time comparator, only

Poki Chen; Tuo-Kuang Chen; Yu-Shin Wang; Chun-Chi Chen

2009-01-01

327

Hydrogen bonded polymeric multilayer films assembled below and above the cloud point temperature.  

PubMed

Polymeric multilayer films assembled via hydrogen-bonding are witnessing increased interest from the scientific community. Here we report on hydrogen bonded multilayers of tannic acid and neutral poly(2-oxazoline)s. Importantly we demonstrate, to the best of our knowledge, for the first time that a temperature responsive polymer, in this case poly(2-(n-propyl)-2-oxazline), can be assembled below and above its TCP with distinctly different growth mechanisms. PMID:24022339

da Fonseca Antunes, André B; Dierendonck, Marijke; Vancoillie, Gertjan; Remon, Jean Paul; Hoogenboom, Richard; De Geest, Bruno G

2013-09-24

328

Measurement of the melting point temperature of several lithium-sodium-beryllium fluoride salt (FLINABE) mixtures  

Microsoft Academic Search

The molten salt Flibe, a combination of lithium and beryllium flourides, was studied for molten salt fission reactors and has been proposed as a breeder and coolant for the fusion applications. 2LiF-BeF melts at 460 C. LiF-BeF melts at a lower temperature, 363 C, but is rather viscous and has less lithium breeder. In the Advanced Power Extraction (APEX) Program,

Timothy J. Boyle; Kenneth P. Troncosa; Richard Einar Nygren; Thomas Joseph Lutz; Jimmie M. McDonald; Tina Joan Tanaka; Michael Andrew Ulrickson

2004-01-01

329

46 CFR 154.707 - Cargo boil-off as fuel: Ventilation.  

Code of Federal Regulations, 2012 CFR

...CARGOES SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Cargo Pressure and Temperature Control § 154.707 Cargo boil-off as fuel: Ventilation. (a) A...

2012-10-01

330

46 CFR 154.709 - Cargo boil-off as fuel: Gas detection equipment.  

Code of Federal Regulations, 2011 CFR

...CARGOES SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Cargo Pressure and Temperature Control § 154.709 Cargo boil-off as fuel: Gas detection equipment. (a)...

2011-10-01

331

46 CFR 154.705 - Cargo boil-off as fuel: General.  

Code of Federal Regulations, 2011 CFR

...CARGOES SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Cargo Pressure and Temperature Control § 154.705 Cargo boil-off as fuel: General. (a) Each cargo...

2011-10-01

332

46 CFR 154.707 - Cargo boil-off as fuel: Ventilation.  

Code of Federal Regulations, 2011 CFR

...CARGOES SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Cargo Pressure and Temperature Control § 154.707 Cargo boil-off as fuel: Ventilation. (a) A...

2011-10-01

333

46 CFR 154.705 - Cargo boil-off as fuel: General.  

Code of Federal Regulations, 2012 CFR

...CARGOES SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Cargo Pressure and Temperature Control § 154.705 Cargo boil-off as fuel: General. (a) Each cargo...

2012-10-01

334

46 CFR 154.709 - Cargo boil-off as fuel: Gas detection equipment.  

Code of Federal Regulations, 2012 CFR

...CARGOES SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Cargo Pressure and Temperature Control § 154.709 Cargo boil-off as fuel: Gas detection equipment. (a)...

2012-10-01

335

Two-Dimensional Calculation of Sodium Boiling in sub-Assemblies.  

National Technical Information Service (NTIS)

The geometrical differences between interior and peripheral subchannels affect the flow and temperature fields inside a subassembly. In the case of a loss of flow without scram, these effects are enhanced after boiling has started in the hottest region, d...

D. Grand G. Basque

1979-01-01

336

46 CFR 154.706 - Cargo boil-off as fuel: Fuel lines.  

Code of Federal Regulations, 2010 CFR

...CARRYING BULK LIQUEFIED GASES Design, Construction...Pressure and Temperature Control § 154.706 Cargo boil-off as fuel: Fuel lines. (a) Gas fuel lines must not pass...accommodation, service, or control spaces. Each gas...

2009-10-01

337

46 CFR 154.706 - Cargo boil-off as fuel: Fuel lines.  

Code of Federal Regulations, 2010 CFR

...CARRYING BULK LIQUEFIED GASES Design, Construction...Pressure and Temperature Control § 154.706 Cargo boil-off as fuel: Fuel lines. (a) Gas fuel lines must not pass...accommodation, service, or control spaces. Each gas...

2010-10-01

338

Evaluation of the Long-Term Stability and Temperature Coefficient of Dew-Point Hygrometers  

NASA Astrophysics Data System (ADS)

The continuous quest for improved specifications of optical dew-point hygrometers has raised customer expectations on the performance of these devices. In the absence of a long calibration history, users with a limited prior experience in the measurement of humidity, place reliance on manufacturer specifications to estimate long-term stability. While this might be reasonable in the case of measurement of electrical quantities, in humidity it can lead to optimistic estimations of uncertainty. This article reports a study of the long-term stability of some hygrometers and the analysis of their performance as monitored through regular calibration. The results of the investigations provide some typical, realistic uncertainties associated with the long-term stability of instruments used in calibration and testing laboratories. Together, these uncertainties can help in establishing initial contributions in uncertainty budgets, as well as in setting the minimum calibration requirements, based on the evaluation of dominant influence quantities.

Benyon, R.; Vicente, T.; Hernández, P.; De Rivas, L.; Conde, F.

2012-09-01

339

Investigation of the Equivalence of National Dew-Point Temperature Realizations in the -50 °C to + 20 °C Range  

NASA Astrophysics Data System (ADS)

In the field of humidity quantities, the first CIPM key comparison, CCT-K6 is at its end. The corresponding European regional key comparison, EUROMET.T-K6, was completed in early 2008, about 4 years after the starting initial measurements in the project. In total, 24 NMIs from different countries took part in the comparison. This number includes 22 EURAMET countries, and Russia and South Africa. The comparison covered the dew-point temperature range from -50 °C to +20 °C. It was carried out in three parallel loops, each with two chilled mirror hygrometers as transfer standards in each loop. The comparison scheme was designed to ensure high quality results with evenly spread workload for the participants. It is shown that the standard uncertainty due to the long-term instability was smaller than 0.008 °C in all loops. The standard uncertainties due to links between the loops were found to be smaller than 0.025 °C at -50 °C and 0.010 °C elsewhere. Conclusions on the equivalence of the dew-point temperature standards are drawn on the basis of calculated bilateral degrees of equivalence and deviations from the EURAMET comparison reference values (ERV). Taking into account 16 different primary dew-point realizations and 8 secondary realizations, the results demonstrate the equivalence of a large number of laboratories at an uncertainty level that is better than achieved in other multilateral comparisons so far in the humidity field.

Heinonen, Martti; Anagnostou, Miltiadis; Bell, Stephanie; Stevens, Mark; Benyon, Robert; Bergerud, Reidun Anita; Bojkovski, Jovan; Bosma, Rien; Nielsen, Jan; Böse, Norbert; Cromwell, Plunkett; Kartal Dogan, Aliye; Aytekin, Seda; Uytun, Ali; Fernicola, Vito; Flakiewicz, Krzysztof; Blanquart, Bertrand; Hudoklin, Domen; Jacobson, Per; Kentved, Anders; Lóio, Isabel; Mamontov, George; Masarykova, Alexandra; Mitter, Helmut; Mnguni, Regina; Otych, Jan; Steiner, Anton; Szilágyi Zsófia, Nagyné; Zvizdic, Davor

2012-09-01

340

Response of copper to shock-wave loading at temperatures up to the melting point  

NASA Astrophysics Data System (ADS)

The evolution of elastic-plastic shock waves as a function of the propagation distance has been studied in 99.999% purity polycrystalline copper over the 300 to 1353 K temperature range. The free surface velocity histories of shock-loaded samples 0.1 to 2.0 mm in thickness have been recorded using the velocity interferometer. The measured decay of the elastic precursor waves has been converted into relationships between the shear stress at Hugoniot elastic limit and the initial plastic strain rate. Independently of the temperature, the initial densities of mobile dislocations in a range of 2.5×106 cm-2 to 5×108 cm-2 are required to provide observed initial strain rates varied from 2.3×103 s-1 to 2×106 s-1. Above 1100 K, the shape of the elastic precursor wave changes with the appearance of a sharp spike at its front part. This change is treated in terms of nucleation and multiplication of mobile dislocations. An analysis of the rise times of the plastic shock waves has shown that for the same level of shear stress, the plastic strain rates after a 2% compressive strain increase with respect to those just behind the elastic precursor front by a factor of 300 at 300 K and by a factor of 30 at 1353 K.

Zaretsky, E. B.; Kanel, G. I.

2013-08-01

341

Local Sodium Boiling behind Local Flow Blockage in Simulated LMFBR Fuel Subassembly  

Microsoft Academic Search

This paper deals with local sodium boiling in the downstream of a six-subchannel blockage in an electrically heated LMFBR fuel subassembly mock-up.The first series of experiments were conducted to measure temperature distributions in the downstream of the blockage under non-boiling conditions. The measured temperature rise due to the blockage agreed fairly well with the calculation by the LOCK code.The second

Yoshihiro KIKUCHI; Yoshimichi DAIGO; Akira OHTSUBO

1977-01-01

342

STUDY OF THE CRITICAL POINT IN LATTICE QCD AT HIGH TEMPERATURE AND DENSITY.  

SciTech Connect

We propose a method to probe the nature of phase transitions in lattice QCD at finite temperature and density, which is based on the investigation of an effective potential as a function of the average plaquette. We analyze data obtained in a simulation of two-flavor QCD using p4-improved staggered quarks with bare quark mass m/T = 0.4, and find that a first order phase transition line appears in the high density regime for {mu}{sub q}/T {approx}> 2.5. The effective potential as a function of the quark number density is also studied. We calculate the chemical potential as a function of the density from the canonical partition function and discuss the existence of the first order phase transition line.

EJIRI,S.

2007-07-30

343

Environment-dependent long-range structural distortion in a temperature-sensitive point mutant  

PubMed Central

Extensive environment-dependent rearrangement of the helix-turn-helix DNA recognition region and adjacent l-tryptophan binding pocket is reported in the crystal structure of dimeric E. coli trp aporepressor with point mutation Leu75Phe. In one of two subunits, the eight residues immediately C-terminal to the mutation are shifted forward in helical register by three positions, and the five following residues form an extrahelical loop accommodating the register shift. In contrast, the second subunit has wildtype-like conformation, as do both subunits in an isomorphous wildtype control structure. Treated together as an ensemble pair, the distorted and wildtype-like conformations of the mutant apoprotein agree more fully than either conformation alone with previously reported NOE measurements, and account more completely for its diverse biochemical and biophysical properties. The register-shifted segment Ile79-Ala80-Thr81-Ile82-Thr83 is helical in both conformations despite low helical propensity, suggesting an important structural role for the steric constraints imposed by ?-branched residues in helical conformation.

Carey, Jannette; Benoff, Brian; Harish, Balasubramanian; Yuan, Lara; Lawson, Catherine L

2012-01-01

344

Experimental study of temperature effect on the growth and collapse of cavitation bubbles near a rigid boundary  

NASA Astrophysics Data System (ADS)

The effect of temperature on the dynamics of a laser-induced cavitation bubble is studied experimentally. The growth and collapse of the cavitation bubble are measured by two sensitive fiber-optic sensors based on optical beam deflection (OBD). Cavitation bubble tests are performed in water at different temperatures, and the temperature ranges from freezing point (0°C) to near boiling point. The results indicate that both the maximum bubble radius and bubble lifetime are increased with the increase of temperature. During the stage of bubble rapidly collapsing in the vicinity of a solid surface, besides laser ablation effect, both the first and second liquid-jet-induced impulses are also observed. They are both increased with liquid temperature increasing, and then reach a peak, followed by a decrease. The peak appears at the temperature which is approximately the average of freezing and boiling points. The mechanism of liquid temperature influence on cavitation erosion is also discussed.

Liu, Xiu-mei; Long, Zheng; He, Jie; Li, Bei-bei; Liu, Xin-hua; Zhao, Ji-yun; Lu, Jian; Ni, Xiao-wu

2013-07-01

345

Variation of Subcooled Film Boiling State in He II with the Pressure  

SciTech Connect

The characteristic feature of subcooled film boiling in He II was experimentally studied. The visual observation and the transient pressure and temperature measurements were performed to investigate the variation of the subcooled film boiling state with the pressure. In the highly subcooled state, the boiling state was relatively stable and little dynamic behavior of the vapor layer was observed. The pressure and temperature oscillations were hardly detected. As the pressure is reduced and consequently the degree of subcooling decreases, the thickness of vapor layer becomes thick and the dynamic behavior gradually becomes violent. The pressure and temperature oscillations appear with a very high frequency around several kHz. As the pressure further decreases to near the lambda pressure, the boiling state changes to much more violent boiling state with a frequency of several hundred Hz. A vapor bubble repeats formation and crush periodically, which apparently resembles noisy film boiling in saturated He II. The boundary between the stable and the unstable boilings seems to be in the pressure higher than the lambda pressure.

Nozawa, M.; Murakami, M.; Yamamoto, I. [Institute of Engineering Mechanics and Systems, University of Tsukuba, Tennodai 1-1-1, Tsukuba 305-8573 (Japan); Kimura, N. [Cryogenics Science Center, Applied Research Laboratory, High Energy Accelerator Research Organization, Oho 1-1, Tsukuba 305-0801 (Japan)

2004-06-23

346

The role of implantation-induced point defects for the redistribution of oxygen in silicon at high-temperature processing  

NASA Astrophysics Data System (ADS)

The excess of implantation-induced point defects controls the oxygen redistribution in silicon during a high-temperature treatment, such as in separation-by-implanted-oxygen, and defines the energy-dose window for the formation of a perfect homogeneous and planar buried oxide layer. Quantitative relations are given between the distribution of the initially generated excess defects and the finally formed oxide layer. Implantation-induced defects also explain the depth positions of different oxide precipitate layers and of silicon islands inside the oxide layer. Other defects as, e.g., dislocations, which form during thermal treatment, may relocate the energy-dose window toward a lower oxygen dose.

Kögler, R.; Ou, X.; Skorupa, W.; Möller, W.

2008-11-01

347

ATWS Analysis with an Advanced Boiling Curve Approach within COBRA 3-CP  

SciTech Connect

In 2005 the German Reactor Safety Commission issued specific requirements on core coolability demonstration for PWR ATWS (anticipated transients without scram). Thereupon AREVA NP performed detailed analyses for all German PWRs. For a German KONVOI plant the results of an ATWS licensing analysis are presented. The plant dynamic behavior is calculated with NLOOP, while the hot channel analysis is performed with the thermal hydraulic computer code COBRA 3-CP. The application of the fuel rod model included in COBRA 3-CP is essential for this type of analysis. Since DNB (departure from nucleate boiling) occurs, the advanced post DNB model (advanced boiling curve approach) of COBRA 3-CP is used. The results are compared with those gained with the standard BEEST model. The analyzed ATWS case is the emergency power case 'loss of main heat sink with station service power supply unavailable'. Due to the decreasing coolant flow rate during the transient the core attains film boiling conditions. The results of the hot channel analysis strongly depend on the performance of the boiling curve model. The BEEST model is based on pool boiling conditions whereas typical PWR conditions - even in most transients - are characterized by forced flow for which the advanced boiling curve approach is particularly suitable. Compared with the BEEST model the advanced boiling curve approach in COBRA 3-CP yields earlier rewetting, i.e. a shorter period in film boiling. Consequently, the fuel rod cladding temperatures, that increase significantly due to film boiling, drop back earlier and the high temperature oxidation is significantly diminished. The Baker-Just-Correlation was used to calculate the value of equivalent cladding reacted (ECR), i.e. the reduction of cladding thickness due to corrosion throughout the transient. Based on the BEEST model the ECR value amounts to 0.4% whereas the advanced boiling curve only leads to an ECR value of 0.2%. Both values provide large margins to the 17% ECR limit. The maximum cladding temperature calculated with both models is almost identical. It results in approximately 830 deg. C, i.e. far below the embrittlement temperature (stipulated at 1200 deg. C). Core coolability was demonstrated with both models, with the BEEST model and with the advanced boiling curve approach. However, the advanced boiling curve approach results in more realistic values and reveals that a much higher safety margin exists. This advantage can be applied to all types of transient hot channel analyses which have to treat film boiling phases. (authors)

Gensler, A.; Knoll, A.; Kuehnel, K. [AREVA, AREVA NP GmbH, Freyeslebenstr. 1, D-91058 Erlangen (Germany)

2007-07-01

348

Self-overcoming of the boiling condition by pressure increment in a water target irradiated by proton beam  

NASA Astrophysics Data System (ADS)

An experiment was conducted to examine and visualize the boiling phenomena inside a water target by irradiating it with a proton beam from MC-50 cyclotron. The boiling phenomena were recorded with a CMOS camera. While an increase of the fraction of the water vapor volume is generally considered to be normal when water is boiled by a proton beam, our experiment showed the opposite result. The volume expansion of the liquid water exceeded the compressibility of the initial air volume. A grid structure in front of the entrance window foil held the target volume constant. Therefore, the phenomena inside the target underwent an isochoric process, and the pressure inside the target was increased rapidly beyond the pressure at the boiling point. Consequently, there was no more bulk boiling in the Bragg-peak region in the target water. Our results show that the boiling of the water can be controlled by controlling the equilibrium pressure of the water target.

Hong, Bong Hwan; Kang, Joonsun; Jung, In Su; Ram, Han Ga; Park, Yeun Soo; Cho, Hyung Hee

2013-11-01

349

Temperature, pressure and high-fidelity pointing knowledge for solar occultation using 2D focal plane arrays  

NASA Astrophysics Data System (ADS)

Accurate simultaneous retrievals of temperature and pressure are key to retrieving high quality mixing ratio profiles from occultation sensors. Equally important is accurate determination of the vertical separation between measurement points. Traditionally, these tasks are complicated by platform motion and CO2 model errors. We present a new approach that is independent of platform motion and CO2 concentration, using inexpensive modern 2D focal-plane arrays and an innovative refraction-angle measurement. This provides both accurate temperature retrievals and precise vertical separation of measurement samples, greatly improving the quality of mixing ratio retrievals. We show recent studies demonstrating the expected performance of the SOFIE instrument (Solar Occultation For Ice Experiment) to be launched as part of the AIM (Aeronomy of Ice Mission) in September 2006. This system will have the ability to retrieve accurate temperature, through mild particulate contamination (such as volcanic aerosol and cirrus) from cloud-top to stratopause, independent of mixing ratio knowledge. Additional CO2 absorption channels will provide retrieved temperature and CO2 mixing ratios through the mesosphere and into the lower thermosphere.

Gordley, Larry L.; McHugh, Martin J.; Hervig, Mark E.; Burton, John C.; Liu, Liang; Magill, Brian E.; Russell, James M.

2005-08-01

350

Nucleate pool boiling heat transfer in aqueous surfactant solutions  

NASA Astrophysics Data System (ADS)

Saturated, nucleate pool boiling in aqueous surfactant solutions is investigated experimentally. Also, the role of Marangoni convection, driven both by temperature and surfactant concentration gradients at the vapor-liquid interface of a nucleating bubble is computationally explored. Experimental measurements of dynamic and equilibrium sigma using the maximum bubble pressure method indicate dynamic sigma to be higher than the corresponding equilibrium value, both at room and elevated temperatures. Also, nonionic surfactants (Triton X-100, Triton X-305) show larger sigma depression than anionic surfactants (SDS, SLES), and a normalized representation of their dynamic adsorption isotherms is shown to be helpful in generalizing the surfactant effectiveness to reduce surface tension. The dynamic sigma has a primary role in the modification of bubble dynamics and associated heat transfer, and is dictated by the adsorption kinetics of the surfactant molecules at boiling temperatures. In general, an enhancement in heat transfer is observed, which is characterized by an early incipience and an optimum boiling performance at or around the critical micelle concentration of the surfactant. The optimum performances, typically in the fully developed boiling regime ( q''w > 100 kW/m2), show a reverse trend with respect to surfactant molecular weights M, i.e., higher molecular weight additives promote lower enhancement. Normalized boiling performance using the respective solution's dynamic sigma correlates heat transfer coefficient by M-0.5 for anionics and M 0 for nonionics. This has been shown to be brought about by the surfactant concentration and its interfacial activity in a concentration sublayer around the growing vapor bubble, which governs the bubble growth behavior through the mechanism of dynamic sigma. The ionic nature of the surfactant influences the thickness and molecular makeup of the enveloping sublayer, thereby affecting the bubble dynamics and boiling heat transfer. Finally, the computational modeling of Marangoni convection for boiling nuclei at short time transients shows similarity solutions for pure water, and reduced convection with a peak in circulation strength in the presence of surfactants. The peaking corresponds to the characteristic surfactant adsorption time, which has been shown to depend solely upon the surfactant bulk concentration. For the absence of surfactant surface convection, an enhancement in Marangoni convection is observed. Furthermore, for the investigated range of parameters and time scales, the surfactant adsorption at the interface is not characterized by the presence of a stagnant cap. (Abstract shortened by UMI.)

Wasekar, Vivek Mahadeorao

351

Microbiological Effectiveness and Cost of Disinfecting Water by Boiling in Semi-urban India  

Microsoft Academic Search

Despite shortcomings, boiling is the most common means of treating water at home and the benchmark against which emerging point-of-use water treatment approaches are measured. In a 5-month study, we assessed the microbiological effectiveness and cost of the practice among 218 self-reported boilers relying on unprotected water supplies. Boiling was associated with a 99% reduction in geometric mean fecal coliforms

Thomas Clasen; Catherine McLaughlin; Neeru Nayaar; Sophie Boisson; Romesh Gupta; Dolly Desai; Nimish Shah

2008-01-01

352

Predictive Models for the Velocity of Sound in Liquid Metallic Elements at Their Melting-Point Temperatures  

NASA Astrophysics Data System (ADS)

Nowadays, accurate and reliable data for the thermophysical properties of almost all liquid metallic elements are indispensable in the field of materials process science ( e.g., for computer simulation studies of the fluid flow in a vessel or the solidification of a metallic element). The dimensionless common parameters (denoted by ? {/E 1/2} and ? {/T 1/2}), extracted from the velocity of sound, provide for better predictions of the thermophysical properties of liquid metallic elements such as surface tension, viscosity, self-diffusion, thermal expansion, and evaporation enthalpy, because these two parameters characterize the state of the liquid metallic atom ( i.e., an atom’s hardness or softness and its anharmonic motions). The usefulness of reliable predictive models in many engineering situations is clear; in the field of materials process science and engineering, both “accuracy” and “universality” are required of any model for predicting the thermophysical properties of liquid metallic elements. In view of the accuracy and universality of a model, predictive models for the velocity of sound in liquid metallic elements at their melting-point temperatures were investigated; the performances of several models were evaluated by comparing experimental values for the melting-point sound velocity in various liquid metallic elements with those calculated from these models, using a relative standard deviation as a yardstick. Of these, two simple models in terms of well-known physical quantities, presented by the authors, give very good agreement with the experimental data. Excluding only a few metals, calculated sound-velocity values fall, or almost fall, within the range of uncertainties associated with experimental measurements of high-melting-point or reactive metals. It can safely be said that the two models for melting-point sound velocity in liquid metallic elements are endowed with the necessary conditions of being predictive.

Iida, Takamichi; Guthrie, Roderick

2009-12-01

353

Dew Point  

NSDL National Science Digital Library

Determine the dew point temperature for your classroom through a hands-on experiment. Use humidity and temperature probes to investigate the temperature at which it would rain in your classroom! Learn about water density and the conditions necessary to produce fog or rain.

Consortium, The C.

2011-12-13

354

EHD enhancement of nucleate boiling. [Electrohydrodynamic  

SciTech Connect

This paper describes: (a) an experimental investigation into the effect of an electric field applied to pool boiling of Freon (R114) on a finned tube and (b) a theoretical model of electrically enhanced nucleate boiling applicable to simple surfaces only. Experimental results have shown electrohydrodynamic (EHD) enhancement of heat transfer to be manifest in two ways: (1) elimination of boiling hysteresis, (2) augmentation of nulceate boiling heat transfer coefficients by up to an order of magnitude. These effects were also observed in electrically enhanced boiling of Freon/oil mixtures. A new analytical model is described whereby EHD nucleate boiling data from previous studies (employing simple apparatus comprising heated wires with concentric cylinder electrodes) have been correlated for the first time using the concept of an electrical influence number. This dimensionless parameter is based upon the relationship between applied electric field intensity and changes in bubble departure diameter at a heat transfer surface.

Cooper, P. (Univ. of Wollongong, New South Wales (Australia))

1990-05-01

355

Experimental demonstration of contaminant removal from fractured rock by boiling.  

PubMed

This study was conducted to experimentally demonstrate removal of a chlorinated volatile organic compound from fractured rock by boiling. A Berea sandstone core was contaminated by injecting water containing dissolved 1,2-DCA (253 mg/L) and sodium bromide (144 mg/L). During heating, the core was sealed except for one end, which was open to the atmosphere to simulate an open fracture. A temperature gradient toward the outlet was observed when boiling occurred in the core. This indicates that steam was generated and a pressure gradient developed toward the outlet, pushing steam vapor and liquid water toward the outlet. As boiling occurred, the concentration of 1,2-DCA in the condensed effluent peaked up to 6.1 times higher than the injected concentration. When 38% of the pore volume of condensate was produced, essentially 100% of the 1,2-DCA was recovered. Nonvolatile bromide concentration in the condensate was used as an indicator of the produced steam quality (vapor mass fraction) because it can only be removed as a solute, and not as a vapor. A higher produced steam quality corresponds to more concentrated 1,2-DCA removal from the core, demonstrating that the chlorinated volatile compound is primarily removed by partitioning into vapor phase flow. This study has experimentally demonstrated that boiling is an effective mechanism for CVOC removal from the rock matrix. PMID:20666474

Chen, Fei; Liu, Xiaoling; Falta, Ronald W; Murdoch, Lawrence C

2010-08-15

356

Evolution of SF[sub 6] pressure at constant volume versus temperature between liquefaction point and +20[degree]C  

SciTech Connect

Switchgear must be able to operate within a temperature range anywhere from [minus]50 C to +55 C. The practical problem of how to perform significant tests at +20 C then presents itself. It becomes mandatory to know the equivalent of the density at the lowest temperature to which the switchgear will be subjected. A perfect mathematical knowledge of SF[sub 6] evolution at constant volume versus temperature between the liquefaction point and +20 C is then very important. There exists today three main state equations used by SF[sub 6] switchgear users and manufacturers and they do not truly agree between themselves. The authors evaluate them and also describe a simple experiment as defined by E. Thuries to check these state equations. The last part of the paper describes various experimental data that drive one to establish a state equation using the new notion of fugacity. The last part of the paper compares this state equation based on fugacity and the other equations as used today against the results of the new SF[sub 6] Thuries experiment.

Thuries, E.; Girodet, A.; Collet, M. (GEC Alsthom T D, Villeurbanne (France). Research Center)

1994-07-01

357

49 CFR 173.224 - Packaging and control and emergency temperatures for self-reactive materials.  

Code of Federal Regulations, 2011 CFR

...control temperatures must be determined in accordance with § 173.21(f). 2. With a compatible diluent having a boiling point of not less than 150 °C. 3. Samples may only be offered for transportation under the provisions of...

2011-10-01

358

49 CFR 173.224 - Packaging and control and emergency temperatures for self-reactive materials.  

Code of Federal Regulations, 2012 CFR

...control temperatures must be determined in accordance with § 173.21(f). 2. With a compatible diluent having a boiling point of not less than 150 °C. 3. Samples may only be offered for transportation under the provisions of...

2012-10-01

359

Solvent Refined Coal (SRC) process. Selected physical, chemical, and thermodynamic properties of narrow boiling range coal liquids for the SRC-II process. Interim report, March 1980February 1981  

Microsoft Academic Search

Physical, chemical, and thermodynamic properties of coal liquids as a function of boiling range via the pseudocomponent approach are needed for process design now that various direct coal liquefaction processes are being scaled to semi-commercial size. Products from the SRC-II processing of a high volatile bituminous coal were distilled into narrow boiling fractions with average boiling points ranging up to

Gray

1981-01-01

360

Experimental Study of Steady-State Boiling of Sodium Flowing in a Single-Pin Annular Channel  

Microsoft Academic Search

An experimental study was carried out on steady-state boiling of sodium flowing in the annular channel formed around an electrically heated simulation of a fuel pin. In the present experiment, the inlet temperature and flow rate were held constant, and the heat flux was gradually increased up to the inception of boiling. Thereafter, the heat flux was further increased step

Yoshihiro KIKUCHI; Kazuo HAGA; Tadao TAKAHASHI

1975-01-01

361

Boiling heat transfer on large diamond and SiC heaters: The influence of thermal wall properties  

Microsoft Academic Search

Pool boiling experiments were performed on large synthetic diamond and SiC substrates with integrated heating and temperature sensor elements. The boiling fluid was pure water at atmospheric pressure. The two heating substrates were identical with regard to geometry and design, and were mainly comparable in terms of surface roughness and static contact angle. This enabled the influence of the thermal

Stefan aus der Wiesche; Ufuk Bardas; Stephan Uhkötter

2011-01-01

362

Numerical analysis of contaminant removal from fractured rock during boiling.  

PubMed

A multiphase heat transfer numerical model is used to simulate a laboratory experiment of contaminant removal at boiling temperatures from a rock core representing the matrix adjacent to a fracture. The simulated temperature, condensate production, contaminant and bromide concentrations are similar to experimental data. A key observation from the experiment and simulation is that boiling out approximately 1/2 pore volume (50 mL) of water results in the removal of essentially 100% of the dissolved volatile contaminant (1,2-DCA). A field-scale simulation using the multiple interacting continua (MINC) discretization approach is conducted to illustrate possible applications of thermal remediation of fractured geologic media, assuming uniform heating. The results show that after 28% of the pore water (including both steam vapor and liquid water) was extracted, and essentially all the 1,2-DCA mass (more than 99%) was removed. PMID:22579665

Chen, Fei; Falta, Ronald W; Murdoch, Lawrence C

2012-04-16

363

Boiling radial flow in fractures of varying wall porosity  

Microsoft Academic Search

The focus of this report is the coupling of conductive heat transfer and boiling convective heat transfer, with boiling flow in a rock fracture. A series of experiments observed differences in boiling regimes and behavior, and attempted to quantify a boiling convection coefficient. The experimental study involved boiling radial flow in a simulated fracture, bounded by a variety of materials.

Robb Allan Barnitt; Robb Allan

2000-01-01

364

The Driving Force of Frost Boils and Hummocks Formation  

Microsoft Academic Search

Formation of frost boils has several aspects to be explained, including the bowl shape of boils, the formation of an organic layer at the periphery of the frost boils, the elevated center of the boils, and resistance of the soil surface to vegetation colonization. Genesis of frost boils and hummocks have been widely attributed to cryoturbation-a complex of seasonally interchanging

Y. Shur; C. Ping

2003-01-01

365

Aging study of boiling water reactor high pressure injection systems  

Microsoft Academic Search

The purpose of high pressure injection systems is to maintain an adequate coolant level in reactor pressure vessels, so that the fuel cladding temperature does not exceed 1,200°C (2,200°F), and to permit plant shutdown during a variety of design basis loss-of-coolant accidents. This report presents the results of a study on aging performed for high pressure injection systems of boiling

D. A. Conley; J. L. Edson; C. F. Fineman

1995-01-01

366

Impurity concentration behaviors in a boiling tubesheet crevice  

Microsoft Academic Search

In a locally restricted geometry on the secondary side of steam generator (SG) in a pressurized water reactor (PWR), impurities in bulk water can concentrate by boiling processes to extreme pH that may then accelerate the corrosion of tubing and adjacent materials. To simulate a real SG tubesheet crevice, a high temperature\\/high pressure (HT\\/HP) crevice simulation system was constructed. The

Chi Bum Bahn; Si Hyoung Oh; Byung Gi Park; Il Soon Hwang; In Hyoung Rhee; Uh Chul Kim; Jung Won Na

2003-01-01

367

Aromatics saturation process for diesel boiling-range hydrocarbons  

Microsoft Academic Search

This patent describes a process for the concomitant hydrogenation of aromatics and sulfur-bearing hydrocarbons in an aromatics- and sulfur-bearing hydrocarbon feedstock having substantially all of this components boiling in the range of abut 200°F to about 900°F. It comprises: contacting at a temperature between about 600°F. and abut 750°F and a pressure between about 650 psi and about 2500 psi

Bhan

1991-01-01

368

MECHANISM OF CRYSTALLIZATION FOULING DURING POOL BOILING OF FINNED TUBES  

Microsoft Academic Search

The formation of deposits on heat transfer surfaces is the main hurdle in optimum operation of thermal desalination units. It is, therefore, common practice to operate these units i.e. MSF under sub-atmospheric pressure to boil saline water below saturation temperature of which depositions occurs. However this comes with high price-tag for excessive use of energy for pumping. Alternative and environmentally-

M. Esawy; M. R. Malayeri; H. Müller-Steinhagen

369

Our Educational Melting Pot: Have We Reached the Boiling Point?  

ERIC Educational Resources Information Center

|The articles and excerpts in this collection illustrate the complexity of the melting pot concept. Multiculturalism has become a watchword in American life and education, but it may be that in trying to atone for past transgressions educators and others are simply going too far. These essays illustrate some of the problems of a multicultural…

Lauderdale, Katherine Lynn, Ed.; Bonilla, Carlos A., Ed.

370

Apparatus for pumping liquids at or below the boiling point  

DOEpatents

A pump comprises a housing having an inlet and an outlet. An impeller assembly mounted for rotation within the housing includes a first impeller piece having a first mating surface thereon and a second impeller piece having a second mating surface therein. The second mating surface of the second impeller piece includes at least one groove therein so that at least one flow channel is defined between the groove and the first mating surface of the first impeller piece. A drive system operatively associated with the impeller assembly rotates the impeller assembly within the housing.

Bingham, Dennis N. (Idaho Falls, ID)

2002-01-01

371

Induction heating pure vapor source of high temperature melting point materials on electron cyclotron resonance ion source  

SciTech Connect

Multicharged ions that are needed are produced from solid pure material with high melting point in an electron cyclotron resonance ion source. We develop an evaporator by using induction heating (IH) with multilayer induction coil, which is made from bare molybdenum or tungsten wire without water cooling and surrounding the pure vaporized material. We optimize the shapes of induction coil and vaporized materials and operation of rf power supply. We conduct experiment to investigate the reproducibility and stability in the operation and heating efficiency. IH evaporator produces pure material vapor because materials directly heated by eddy currents have no contact with insulated materials, which are usually impurity gas sources. The power and the frequency of the induction currents range from 100 to 900 W and from 48 to 23 kHz, respectively. The working pressure is about 10{sup -4}-10{sup -3} Pa. We measure the temperature of the vaporized materials with different shapes, and compare them with the result of modeling. We estimate the efficiency of the IH vapor source. We are aiming at the evaporator's higher melting point material than that of iron.

Kutsumi, Osamu; Kato, Yushi; Matsui, Yuuki; Sato, Fuminobu; Iida, Toshiyuki [Division of Electrical, Electronic and Information Engineering, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita-shi, Osaka 565-0871 (Japan); Kitagawa, Atsushi; Muramatsu, Masayuki [National Institute of Radiological Science (NRIS), 4-9-1 Anagawa, Inage, Chiba 263-8555 (Japan); Uchida, Takashi; Yoshida, Yoshikazu [Bio-Nano Electronics Research Centre, Toyo University, 2100 Kujirai, Kawagoe, Saitama 350-8585 (Japan)

2010-02-15

372

[Cavitation and boiling of bubbles at the focal region during high intensity focused ultrasound exposure].  

PubMed

High intensity focused ultrasound (HIFU) is a very complex transient process and can cause tissue coagulation necrosis. The cavitation and boiling behaviour of bubbles in the focal region play very important roles throughout an injury process. This paper reviews the research done by domestic and foreign scholars on behaviours of bubbles in HIFU irradiation process and summarizes in the focal region bubble cavitation and boiling generation, related detective means and relationships with hyperecho, temperature rise of the focus and injury shape. PMID:23198445

Zhong, Mingsong; Ai, Huijian; Li, Faqi

2012-10-01

373

Prediction and measurement of incipient boiling heat flux in micro-channel heat sinks  

Microsoft Academic Search

Experiments were performed to measure the incipient boiling heat flux in a heat sink containing 21 rectangular (231 ?m wide and 713 ?m deep) micro-channels. Tests were performed using deionized water with inlet liquid velocities of 0.13–1.44 m\\/s, inlet temperatures of 30, 60 and 90 °C, and an outlet pressure of 1.2 bar. Using a microscope, boiling incipience was identified

Weilin Qu; Issam Mudawar

2002-01-01

374

New Method of Filling of High-Temperature Fixed-Point Cells Based on Metal-Carbon Eutectics/Peritectics  

NASA Astrophysics Data System (ADS)

A new method of filling of high-temperature fixed-point cells based on metal-carbon eutectics and peritectics is suggested and tested. In this method a metal and carbon powder mixture is introduced not directly into the crucible, but into an additional container located just above the crucible. The mixture melts inside the container, and the already molten eutectic drops through a small hole in the bottom of the container and fills the crucible drop by drop. The method can be used to obtain a uniform ingot without porous or foundry cavities, to minimize the risk of contamination, and to avoid some other disadvantages. The method was applied to fabricate Re-C and WC-C cells using 5N purity materials. The cells demonstrated a good plateau shape with melting ranges of 0.2 K and 80 mK for Re-C and WC-C, respectively. The Re-C cell was compared with a cell built at NMIJ and showed good agreement with a difference of melting temperatures of only 45 mK.

Khlevnoy, B. B.; Grigoryeva, I. A.; Ibragimov, N. A.

2011-08-01

375

Goals Requirements and Design Implications for the Advanced High-TemperatureReactor  

Microsoft Academic Search

The Advanced High-Temperature Reactor (AHTR), also called the liquid-salt-cooled Very High-Temperature Reactor (LS-VHTR), is a new reactor concept that has been under development for several years. The AHTR combines four existing technologies to create a new reactor option: graphite- matrix, coated-particle fuels (the same fuel as used in high- temperature gas-cooled reactors); a liquid-fluoride-salt coolant with a boiling point near

Charles W. Forsberg

376

Effect of temperature of CO2 injection on the pH and freezing point of milks and creams.  

PubMed

The objectives of this study were to measure the impact of CO2 injection temperature (0 degree C and 40 degrees C) on the pH and freezing point (FP) of (a) milks with different fat contents (i.e., 0, 15, 30%) and (b) creams with 15% fat but different fat characteristics. Skim milk and unhomogenized creams containing 15 and 30% fat were prepared from the same batch of whole milk and were carbonated at 0 and 40 degrees C in a continuous flow CO2 injection unit (230 ml/min). At 0 degree C, milk fat was mostly solid; at 40 degrees C, milk fat was liquid. At the same total CO2 concentration with CO2 injection at 0 degree C, milk with a higher fat content had a lower pH and FP, while with CO2 injection at 40 degrees C, milks with 0%, 15%, and 30% fat had the same pH. This indicated that less CO2 was dissolved in the fat portion of the milk when the CO2 was injected at 0 degree C than when it was injected at 40 degrees C. Three creams, 15% unhomogenized cream, 15% butter oil emulsion in skim milk, and 15% vegetable oil emulsion in skim milk were also carbonated and analyzed as described above. Vegetable oil was liquid at both 0 and 40 degrees C. At a CO2 injection temperature of 0 degree C, the 15% vegetable oil emulsion had a slightly higher pH than the 15% butter oil emulsion and the 15% unhomogenized cream, indicating that the liquid vegetable oil dissolved more CO2 than the mostly solid milk fat and butter oil. No difference in the pH or FP of the 15% unhomogenized cream and 15% butter oil emulsion was observed when CO2 was injected at 0 degree C, suggesting that homogenization or physical dispersion of milk fat globules did not influence the amount of CO2 dissolved in milk fat at a CO2 injection temperature of 0 degree C. At a CO2 injection temperature of 40 degrees C and at the same total CO2 concentration, the 15% unhomogenized cream, 15% vegetable oil emulsion, and 15% butter oil emulsion had similar pH. At the same total concentration of CO2 in cream, injection of CO2 at low temperature (i.e., < 4 degrees C) may produce a better antimicrobial effect during refrigerated shelf life due to the higher concentration of CO2 in the skim portion of the cream. PMID:12778568

Ma, Y; Barbano, D M

2003-05-01

377

21 CFR 872.6710 - Boiling water sterilizer.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Boiling water sterilizer. 872.6710 Section... Miscellaneous Devices § 872.6710 Boiling water sterilizer. (a) Identification. A boiling water sterilizer is an AC-powered...

2010-04-01

378

21 CFR 872.6710 - Boiling water sterilizer.  

Code of Federal Regulations, 2010 CFR

...2009-04-01 2009-04-01 false Boiling water sterilizer. 872.6710 Section... Miscellaneous Devices § 872.6710 Boiling water sterilizer. (a) Identification. A boiling water sterilizer is an AC-powered...

2009-04-01

379

Temperature dependent droplet impact dynamics on flat and textured surfaces  

NASA Astrophysics Data System (ADS)

Droplet impact dynamics determines the performance of surfaces used in many applications such as anti-icing, condensation, boiling, and heat transfer. We study impact dynamics of water droplets on surfaces with chemistry/texture ranging from hydrophilic to superhydrophobic and across a temperature range spanning below freezing to near boiling conditions. Droplet retraction shows very strong temperature dependence especially on hydrophilic surfaces; it is seen that lower substrate temperatures lead to lesser retraction. Physics-based analyses show that the increased viscosity associated with lower temperatures combined with an increased work of adhesion can explain the decreased retraction. The present findings serve as a starting point to guide further studies of dynamic fluid-surface interaction at various temperatures.

Alizadeh, Azar; Bahadur, Vaibhav; Zhong, Sheng; Shang, Wen; Li, Ri; Ruud, James; Yamada, Masako; Ge, Liehui; Dhinojwala, Ali; Sohal, Manohar

2012-03-01

380

Modeling and analysis of low heat flux natural convection sodium boiling in LMFBRs  

SciTech Connect

Flow excursion induced dryout at low heat flux natural convection boiling, typical of liquid metal fast breeder reactor, is addressed. Steady state calculations indicate that low quality boiling is possible up to the point of Ledinegg instability leading to flow excursion and subsequent dryout in agreement with experimental data. A flow regime-dependent dryout heat flux relationship based upon saturated boiling criterion is also presented. Transient analysis indicates that premature flow excursion can not be ruled out and sodium boiling is highly transient dependent. Analysis of a high heat flux forced convection, loss-of-flow transient shows a significantly faster flow excursion leading to dryout in excellent agreement with parallel calculations using the two-dimensional THORAX code. 31 refs., 25 figs., 6 tabs.

Khatib-Rahbar, M.; Cazzoli, E.G.

1982-09-01

381

Critical heat flowrates in subcooled flow boiling  

Microsoft Academic Search

Matters related to calculating critical heat flowrates during boiling in a highly subcooled flow are considered. Existing\\u000a data on heat transfer for swirl flow with one-sided heating are analyzed, and a formula for calculating critical heat flowrates\\u000a is proposed. The conditions under which the thermodynamic limit of boiling is reached are analyzed.

A. V. Dedov

2010-01-01

382

Boiling nucleation during liquid flow in microchannels  

Microsoft Academic Search

The boiling of liquids in microchannels\\/microstructures is currently of great interest due to its very unusual phenomena and its many potential applications in a wide variety of advanced technologies. The thermodynamic aspects of phase transformations of liquids in microchannels was analyzed to further understand the boiling characteristics and to determine the conditions under which a portion of such liquids is

X. F. Peng; H. Y. Hu; B. X. Wang

1998-01-01

383

CORROSION OF AIR PREHEATER TUBES OF OIL SHALE CFB BOILER. PART I. DEW POINT OF FLUE GAS AND LOW-TEMPERATURE CORROSION  

Microsoft Academic Search

The damage to air preheater (APH) tubes in the zones where air and gas temperatures are low discovered in CFB boilers at Estonian oil shale power plants was indicative of low-temperature corrosion (LTC). To establish damage causes, samples of ash deposits from boiler heating surfaces and APH corroded tubes were collected and chemically analysed, visual observations were conducted, dew point

T. PIHU; H. ARRO; A. PRIKK; R. ROOTAMM; A. KONIST

2009-01-01

384

Effects of Temperature and pH on Reduction of Bacteria in a Point-of-Use Drinking Water Treatment Product for Emergency Relief  

PubMed Central

The effects of temperature and pH on the water treatment performance of a point-of-use (POU) coagulant/disinfectant product were evaluated. Cold temperatures (?5°C) reduced the bactericidal efficiency of the product with regard to Escherichia coli and total coliform log10 reductions.

Marois-Fiset, Jean-Thomas; Carabin, Anne; Lavoie, Audrey

2013-01-01

385

Effects of temperature and pH on reduction of bacteria in a point-of-use drinking water treatment product for emergency relief.  

PubMed

The effects of temperature and pH on the water treatment performance of a point-of-use (POU) coagulant/disinfectant product were evaluated. Cold temperatures (?5°C) reduced the bactericidal efficiency of the product with regard to Escherichia coli and total coliform log(10) reductions. PMID:23335762

Marois-Fiset, Jean-Thomas; Carabin, Anne; Lavoie, Audrey; Dorea, Caetano C

2013-01-18

386

Considerations in predicting burnout of cylinders in flow boiling  

NASA Astrophysics Data System (ADS)

Previous investigations of the critical heat flux in flow boiling have resulted in widely different hydrodynamic mechanisms for the occurrence of burnout. Results of the present study indicate that existing models are not completely realistic representations of the process. The present study sorts out the infuences of the far-wake bubble breakoff and vapor sheet characteristics, gravity, surface wettability, and heater surface temperature distribution on the peak heat flux in flow boiling on cylindrical heaters. The results indicate that burnout is dictated by near-surface effects. The controlling factor appears to be the vapor escape pattern close to the heater surface. It is also shown that a deficiency of liquid at the downstream end of the heater surface is not the cause of burnout.

Sadasivan, P.; Lienhard, J. H.

1992-02-01

387

Considerations in predicting burnout of cylinders in flow boiling  

SciTech Connect

Previous investigations of the critical heat flux in flow boiling have resulted in widely different hydrodynamic mechanisms for the occurrence of burnout. Results of the present study indicate that existing models are not completely realistic representations of the process. The present study sorts out the influences of the far-wake bubble breakoff and vapor sheet characteristics, gravity, surface wettability, and heater surface temperature distribution on the peak heat flux in flow boiling on cylindrical heaters. The results indicate that burnout is dictated by near-surface effects. The controlling factor appears to be the vapor escape pattern close to the heater surface. It is also shown that a deficiency of liquid at the downstream end of the heater surface is not the cause of burnout.

Sadasivan, P.; Lienhard, J.H. (Univ. of Houston, TX (United States))

1992-02-01

388

Analytical model for the inverted annular film boiling region  

SciTech Connect

Inverted Annular Film Boiling (IAFB) is a phenomenon that is thought to occur during the reflood phase of a loss-of-coolant-accident (LOCA) in a pressurized water reactor. IAFB has been observed in simulated reflood experiments through externally heated quartz tubes. This boiling regime lies immediately upstream of the quench front. It is characterized by a vertical flowing liquid column separated from the hot fuel rods by a very thin vapor film. Its importance derives from the impact it has on the peak fuel rod temperature following a LOCA. This paper reviews past research on IAFB and present a new analytical model. It identifies recent advancements and areas needed for improvements and better understanding. A new analytical model is developed which overcomes some of the earlier shortcomings. Specifically, the new model results in a heat transfer coefficient which accounts for the effect of coolant subcooling and mass flux. Comparisons are made and good agreement is obtained with single tube reflood experiments.

Vreeland, D.G.

1989-01-01

389

Communication: High speed optical investigations of a character of boiling-up onset.  

PubMed

In this communication, we discuss the phenomenon of attainable superheat of liquid and the peculiarities of its release by spontaneous boiling-up. We have combined the apparatus for superheating, namely, bubble chamber, with a high speed micro-optical method for detailed monitoring of the initial stage of boiling-up. In experiments on the isothermal pressure drop, it was found that the boiling-up onset of n-hexane is accompanied by characteristic step signal. The signal has proved to be typical of the heterogeneous character of boiling-up onset in a whole range of superheating degrees. The performance of the method for investigation of the refractive index and density for superheated liquids as functions of temperature and pressure has been revealed. The experimental error is estimated to be 0.1%. PMID:22260557

Gurashkin, A L; Starostin, A A; Ermakov, G V; Skripov, P V

2012-01-14

390

VLA Shows "Boiling" in Atmosphere of Betelgeuse  

NASA Astrophysics Data System (ADS)

A team of astronomers says that observations with the National Science Foundation's Very Large Array (VLA) radio telescope show that a neighboring bloated star has giant convective plumes propelling gas from its surface (photosphere) up into the star's atmosphere. This new information contradicts long-held ideas that such stellar atmospheres are more uniform, and may resolve questions about how the star's atmosphere attains its enormous size as well as how dust and gas is driven away from the star. Jeremy Lim of the Academia Sinica Institute of Astronomy & Astrophysics in Taiwan; Chris Carilli, Anthony Beasley, and Ralph Marson of the National Radio Astronomy Observatory (NRAO) in Socorro, NM; and Stephen White of the University of Maryland studied the red-supergiant star Betelgeuse, about 430 light-years away in the constellation Orion. They reported their findings in the April 9 issue of the scientific journal Nature. "These radio-telescope images confirm that Betelgeuse -- already more than 600 times larger than our Sun -- has a dense atmosphere that extends to many times larger still than the star itself," said Lim. "The highest-resolution image shows the star's atmosphere to have a remarkably complex structure." "To our surprise," added White, "the images also show that most of the gas in the atmosphere is only about as hot as that on the surface. Previously, all of it was thought to be very much hotter." The astronomers used the VLA to make images of Betelgeuse at a variety of radio frequencies. The series of radio observations measured the temperature of the star's atmosphere at different heights. Previous observations with the Hubble Space Telescope (HST) at ultraviolet wavelengths showed that the star's atmosphere contains very hot gas at about twice the surface temperature. The VLA images showed that there also is lower-temperature gas throughout the atmosphere. This gas is near the surface temperature at low heights and decreases in temperature progressively outwards. Although its existence was not previously suspected, this lower-temperature gas turns out to be the most abundant constituent of Betelgeuse's atmosphere. "This alters our basic understanding of red-supergiant star atmospheres," explains Lim. "Instead of the star's atmosphere expanding uniformly because of gas heated to very high temperatures near its surface, it now appears that several giant convection cells propel gas from the star's surface into its atmosphere. This creates the complex structure we observe for Betelgeuse's atmosphere." Betelgeuse can be likened to an enormous "boiling" ball of gas heated by the release of energy from nuclear fusion in its core. The circulating boiling pattern -- convection -- appears as large regions of hot upwelling gas on the star's surface. "The idea that red-supergiant stars have enormous convection cells is not new," noted Marson. "This was suggested by Martin Schwarzschild more than 20 years ago, and was seen in optical images of Betelgeuse's surface in 1990." The new picture of Betelgeuse's atmosphere also helps resolve the mystery of how massive amounts of dust and gas are expelled from red supergiant stars, an important source of enrichment for the interstellar medium. If their atmospheres were entirely very hot at lower levels, dust grains would not be able to condense there. Dust grains could possibly condense at higher levels, but there they would not get enough "push" from the star's radiation to explain their outward movement. In the new picture, the relatively cool environment at lower levels allows dust grains to condense effectively; here they can be strongly propelled by the more-intense starlight, carrying gas with them. Indeed, dust has previously been inferred to form sporadically near Betelgeuse's surface, but its presence there was difficult to reconcile with the old picture. "This method for propelling the mass outflows of red giant and supergiant stars was proposed by Sun Kwok i

1998-04-01

391

Inactivation of Salmonella enteritidis during boiling of eggs.  

PubMed

A series of inactivation curves for Salmonella enteritidis were determined for boiling eggs using different conditions of time and temperature. No significant influence of egg weight could be found on the temperature evolution in the yolk. The inactivation curves consistently showed an initial slow decline in bacterial number at lower temperatures, after which a very rapid inactivation took place. It was not possible to reproduce this behavior using a traditional inactivation model. A pragmatic model existing in two parts was therefore constructed. When the temperature is below a certain threshold, the inactivation follows a second order temperature dependence. Above the temperature threshold, standard Bigelow inactivation kinetics are assumed. This model could describe the data reasonably well, provided that the decimal reduction time in the Bigelow model was assumed to be different for a fast or slow heating process, respectively. The results suggest that the bacteria are more resistant towards a slower heating process, which is confirmed by analyzing the raw data. A fail-safe model can be obtained by using the parameters associated with the slow heating process. The statistical properties of the calibrated model are satisfactory, and a cross-validation shows that it can be used for egg boiling conditions outside its calibration range. PMID:12505456

Grijspeerdt, Koen; Herman, Lieve

2003-01-26

392

Incipient boiling superheat and critical heat flux in liquid sodium. Effect of the pre-pressure on the heated surface.  

National Technical Information Service (NTIS)

Incipient boiling superheat and critical heat flux on a horizontal cylinder in liquid sodium have been systematically measured to know effects of the history of experimental condition, the cold-trap temperature, subcooling of the liquid sodium. The effect...

M. Shiotsu Y. Shirai K. Hata Y. Takeuchi K. Hama

1998-01-01

393

Boiling Heat Transfer to Halogenated Hydrocarbon Refrigerants  

NASA Astrophysics Data System (ADS)

The current state of knowledge on heat transfer to boiling refrigerants (halogenated hydrocarbons) in a pool and flowing inside a horizontal tube is reviewed with an emphasis on information relevant to the design of refrigerant evaporators, and some recommendations are made for future research. The review covers two-phase flow pattern, heat transfer characteristics, correlation of heat transfer coefficient, influence of oil, heat transfer augmentation, boiling from tube-bundle, influence of return bend, burnout heat flux, film boiling, dryout and post-dryout heat transfer.

Yoshida, Suguru; Fujita, Yasunobu

394

Transient and steady-state measurement of boiling heat transfer from impinging jets  

Microsoft Academic Search

Free-surface liquid jets are frequently used in primary metals processing operations to control cooling rates, thereby influencing the metallurgical and mechanical properties of finished products. The hydrodynamics and heat transfer of jet impingement boiling from high temperature surfaces (exceeding the temperature corresponding to maximum heat flux) are still poorly understood and modeled. In an effort to address these deficiencies, this

David Eric Hall

1998-01-01

395

Boiling and condensing pumped loop microgravity experiment  

NASA Astrophysics Data System (ADS)

Aircraft testing of a boiling and condensing (two-phase) pumped loop system was conducted to investigate transient induced by low gravity (Keplerian) maneuvers. The experiment, unchanged, will repeat a selected aircraft test sequence during its flight aboard a suborbital rocket. Such a test of a two-phase system has never been done. A comparison of aircraft and rocket data, particularly equilibrium conditions, may validate aircraft testing of similar systems: Aircraft testing has been completed and preliminary results indicate that local transients induced by Keplerian maneuvers do not generate sizeable or lasting feedback. System feedback, expected to damp exponentially with loop transit time, ?loop (20 stemperature transients having shorter equilibrium times, ?local (5

Standley, Vaughn H.; Fairchild, Jerry F.

1991-01-01

396

Boiling and condensing pumped loop microgravity experiment  

SciTech Connect

Aircraft testing of a boiling and condensing (two-phase) pumped loop system was conducted to investigate transient induced by low gravity (Keplerian) maneuvers. The experiment, unchanged, will repeat a selected aircraft test sequence during its flight aboard a suborbital rocket. Such a test of a two-phase system has never been done. A comparison of aircraft and rocket data, particularly equilibrium conditions, may validate aircraft testing of similar systems: Aircraft testing has been completed and preliminary results indicate that local transients induced by Keplerian maneuvers do not generate sizeable or lasting feedback. System feedback, expected to damp exponentially with loop transit time, {theta}{sub loop} (20 s{lt}{theta}{sub loop}{lt}30 s) is negligible compared to local temperature transients having shorter equilibrium times, {theta}{sub local} (5{lt}{theta}{sub local}{lt}10 s). Since {theta}{sub local} is typically 2 to 5 times shorter than the duration of low gravity, {ital t}{sub 0{minus}{ital g}} (20 s{lt}t{sub 0{minus}{ital g}}{lt}25 s), equilibrium conditions are approximated. Transients following a transition from normal to low gravity resulted from destratification of hot and cold fluid, loss of the liquid convection component in laminar flows, and a reduction in condensing heat transfer.

Standley, V.H.; Fairchild, J.F. (Weapons Laboratory, Technology Assessment Directorate, Space Nuclear Power Branch, Kirtland AFB, New Mexico (USA))

1991-01-10

397

Apparatus for regulating the temperature of a casting mold  

US Patent & Trademark Office Database

A serial flow of a variable-boiling point volatile fluid is established through the wall of a casting mold and through a heater and condenser associated therewith by means of a pump. The condenser includes a lower portion in the path of flow of the volatile liquid, and an upper portion through which an auxiliary conduit extends, such conduit conveying a variable flow of coolant through the upper condenser portion. Changes in vapor pressure of the volatile liquid as the temperature in the mold changes are detected in the upper portion of the condenser by a suitable sensing device, and the output indication of the latter is employed to control a regulating valve for the auxiliary conduit to vary the flow of coolant in the auxiliary conduit. Such variations in flow, in turn, serve to adjust the vapor pressure, and thus the boiling point, of the volatile liquid and to thereby help compensate for temperature changes in the casting mold.

Kostura; Michal (Snina, CS); Pandula; Jan (Snina, CS); Harmansky; Absolon (Snina, CS); Smiga; Slavomir (Snina, CS); Kepic; Stefan (Snina, CS)

1978-02-07

398

Characteristics of nucleate pool boiling from porous metallic coatings  

Microsoft Academic Search

A study of pool boiling from a commercial porous metallic matrix surface is reported. The excellent steady boiling characteristics of this type of surface are confirmed; however, high wall superheats are required in most cases to initate boiling. The resultant boiling curve hysteresis does not appear to have been previously reported in the literature. This effect is indicated in recent

A. E. Bergles; M. C. Chyu

1982-01-01

399

Mechanisms of Boiling in Microchannels: Critical Assessment  

NASA Astrophysics Data System (ADS)

Numerous characteristic trends and effects have been observed in published studies on two-phase micro-channel boiling heat transfer. While macro-scale flow boiling heat transfer may be decomposed into nucleate and convective boiling contributions, at the micro-scale the extent of these two important mechanisms remains unclear. Although many experimental studies have proposed nucleate boiling as the dominant micro-scale mechanism, based on the strong dependence of the heat transfer coefficient on the heat flux similar to nucleate pool boiling, they fall short when it comes to actual physical proof. A strong presence of nucleate boiling is reasonably associated to a flow of bubbles with sizes ranging from the microscopic scale to the magnitude of the channel diameter. The bubbly flow pattern, which well adapts to this description, is observed however only over an extremely limited range of low vapor qualities (typically for x <0.01-0.05). Furthermore, at intermediate and high vapor qualities, when the flow assumes the annular configuration and a convective behavior is expected to dominate the heat transfer process, the experimental evidence yields entirely counter intuitive results, with heat transfer coefficients often decreasing with increasing vapor quality rather than increasing as in macro-scale channels, and with a much diminished heat flux dependency as would be expected. In summary, convective boiling in micro-channels has revealed to be much more complex than originally thought. The present review aims at describing and analyzing the boiling mechanisms that have been proposed for two-phase micro-channel flows, confronting them with the available experimental heat transfer results, while highlighting those questions that, to date, remain unanswered.

Thome, J. R.; Consolini, L.

400

Visualizational study on nucleate pool boiling phenomena  

NASA Astrophysics Data System (ADS)

It is important to visualize the intricate bubble behavior and the strong agitation of liquid near the heating surface to clarify the details concerning boiling mechanism. The visualization of nucleate pool boiling phenomena was confirmed by means of shadowgraphy using a still- camera (Nikon Photomic Camera) with the speed of 2000 frames per second. Illumination was provided by a photo spotlight or a stroboscope. The photographs show that the boiling phenomena and bubbles' behavior are varied for the heat flux of nucleate pool boiling based on the experiments. By considering the effect of revolving angle and the influence of a space between a tube and a tube, experiments have been carried out to investigate the nucleate pool boiling phenomena on horizontal stainless-steel-multi-tube in saturated distilled water. These experiments were performed for atmospheric pressure, for a stainless-tube diameter of 1.0 mm for a length of 80 mm, for a region of natural convection to nucleate boiling near burnout. From these results, photographs show that the successive motion and shape of bubbles during their process of detachment on the heating tube surface varied with increasing heat flux.

Kamei, Shuya

1993-01-01

401

The Variation of the Adiabatic and Isothermal Elastic Moduli and Coefficient of Thermal Expansion with Temperature through the lambda-Point Transition in Ammonium Chloride  

Microsoft Academic Search

Measurements of the temperature variation of the adiabatic and isothermal Young's and rigidity moduli and of the coefficient of thermal expansion of pressed specimens of ammonium chloride in the neighborhood of the lambda-point transition at 242.8°K are reported. It is found that a large difference exists between the adiabatic and isothermal compressibilities below the critical temperature, and hence a large

Andrew W. Lawson

1940-01-01

402

Henry`s law constant for selected volatile organic compounds in high-boiling oils  

SciTech Connect

Absorption systems are often used to remove and recover organic vapors from process air/gas streams. A high boiling and inert liquid like silicone oil is an excellent absorbent for volatile organic compounds in air. Henry`s law constants of four different volatile organic compounds, namely, acetone, methanol, methylene chloride, and toluene between air and high-boiling oils were determined experimentally by the headspace-GC technique over a temperature range. The Henry`s law constants were fitted as a function of temperature to an equation.

Poddar, T.K.; Sirkar, K.K. [New Jersey Inst. of Tech., Newark, NJ (United States). Dept. of Chemical Engineering, Chemistry and Environmental Science

1996-11-01

403

Characterization of laser-tissue interaction processes by low-boiling emitted substances  

NASA Astrophysics Data System (ADS)

Main point in this study was the investigation of the gaseous and low-boiling substances produced in the laser plume during cw CO2 laser and XeCl laser irradiation of tissue by gas chromatography (GC)/mass spectrometry. The characteristic emitted amounts of chemicals were determined quantitatively using porcine muscular tissue. The produced components were used to determine the character of the chemical reaction conditions inside the interaction zone. It was found that the temperature, and the water content of the tissue are the main parameter determining kind and amount of the emitted substances. The relative intensity of the GC peak of benzene corresponds to a high temperature inside the interaction area while a relative strong methylbutanal peak is connected with a lower temperature which favors Maillard type reaction products. The water content of the tissue determines the extent of oxidation processes during laser tissue interaction. For that reason the moisture in the tissue is the most important parameter to reduce the emission of harmful chemicals in the laser plume. The same methods of investigation are applicable to characterize the interaction of a controlled and an uncontrolled rf electrosurgery device with tissue. The results obtained with model tissue are in agreement with the situation characteristic in laser surgery.

Weigmann, Hans-Juergen; Lademann, Juergen; Serfling, Ulrike; Lehnert, W.; Sterry, Wolfram; Meffert, H.

1996-01-01

404

Results of the DF-4 BWR (boiling water reactor) control blade-channel box test  

SciTech Connect

The DF-4 in-pile fuel damage experiment investigated the behavior of boiling water reactor (BWR) fuel canisters and control blades in the high temperature environment of an unrecovered reactor accident. This experiment, which was carried out in the Annular Core Research Reactor (ACRR) at Sandia National Laboratories, was performed under the USNRC's internationally sponsored severe fuel damage (SFD) program. The DF-4 test is described herein and results from the experiment are presented. Important findings from the DF-4 test include the low temperature melting of the stainless steel control blade caused by reaction with the B{sub 4}C, and the subsequent low temperature attack of the Zr-4 channel box by the relocating molten blade components. Hydrogen generation was found to continue throughout the experiment, diminishing slightly following the relocation of molten oxidizing zircaloy to the lower extreme of the test bundle. A large blockage which was formed from this material continued to oxidize while steam was being fed into the the test bundle. The results of this test have provided information on the initial stages of core melt progression in BWR geometry involving the heatup and cladding oxidation stages of a severe accident and terminating at the point of melting and relocation of the metallic core components. The information is useful in modeling melt progression in BWR core geometry, and provides engineering insight into the key phenomena controlling these processes. 12 refs., 12 figs.

Gauntt, R.O.; Gasser, R.D.

1990-10-01

405

Automatic spatial and temporal temperature control for MR-guided focused ultrasound using fast 3D MR thermometry and multispiral trajectory of the focal point.  

PubMed

Of the different modalities to induce local hyperthermia, focused ultrasound is the only noninvasive technology available at the moment. In addition to the 3D localization of the target region, it has been shown that MRI can provide real-time thermometry and allows online, automatic control of temperature evolution of the focal point. Treatment of a large tissue volume (as compared to the focal spot size, i.e., the ultrasound wavelength) can be achieved rapidly by moving the focal point along an inside-out spiral trajectory. It has been shown previously that under linear conditions of energy deposition versus temperature, the spatial profile of the temperature within a large area can be controlled. In this study, a proportional, integral, and derivative (PID) spatial-and-temporal controller is described for the control of the temperature evolution within the target region under more variable conditions. The aim was to reach a predefined temperature profile after a few successive trajectories. Heat conduction in tissue is exploited to obtain a uniform temperature increase in a volume using discrete sonications without any waiting time. Input data sets consisted of 3D temperature maps provided online by a MR scanner. For each new trajectory, the controller recalculates the number of sonications per surface unit (spatial density of points describing the trajectory) and the applied power. Its performance was tested ex vivo and in vivo. Diameters of the target region ranged from 9 mm to 19 mm. Targeted temperature increase ranged from +8 degrees C to +18 degrees C. Spatiotemporal temperature control showed good stability and fast convergence, for both circular and elliptic ROIs. PMID:15508173

Mougenot, Charles; Salomir, Rares; Palussière, Jean; Grenier, Nicolas; Moonen, Chrit T W

2004-11-01

406

Koyuten sen'i kinzoku silicide no koon tokusei ni kansuru kenkyu. (Study on high temperature characteristics of silicide, high melting point transition metal).  

National Technical Information Service (NTIS)

A study was conducted on silicide of Mo, Nb, Ta and W to obtain basic data on its commercialization as high temperature structural materials. A possibility was found out of manufacturing ingots of MSi2 (M: transition metal) with a high melting point by th...

1994-01-01

407

Retrieval of temperature and tangent altitude pointing from limb emission spectra recorded from space by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS)  

Microsoft Academic Search

Retrieval of abundances of atmospheric species from limb infrared emission spectra requires accurate knowledge of the pointing of the instrument in terms of elevation, as well as temperature and pressure profiles. An optimal estimation-based method is presented to infer these quantities from measured spectra. The successful and efficient joint retrieval of these largely correlated quantities depends strongly on the proper

T. von Clarmann; N. Glatthor; U. Grabowski; M. Höpfner; S. Kellmann; M. Kiefer; A. Linden; G. M. Tsidu; M. Milz; T. Steck; G. P. Stiller; D. Y. Wang; H. Fischer; B. Funke; S. Gil-López; M. López-Puertas

2003-01-01

408

Molar heat capacity at constant volume of difluoromethane (R32) and pentafluoroethane (R125) from the triple-point temperature to 345 K at pressures to 35 MPa  

Microsoft Academic Search

Molar heat capacities at constant volume (Cv) of dill uoromethane (R32) and pentalluoroethane (R125) were measured with an adiabatic calorimeter. Temperatures ranged from their triple points to 345 K, and pressures up to 35 MPa. Measurements were conducted on the liquid in equilibrium with its vapor and on compressed liquid samples. The samples were of a high purity, verified by

T. O. Lueddecke; J. W. Magee

1996-01-01

409

Molar heat capacity at constant volume of difluoromethane (R32) and pentafluoroethane (R125) from the triple-point temperature to 345 K at pressures to 35 MPa  

Microsoft Academic Search

Molar heat capacities at constant volume ( C v) of dill uoromethane (R32) and pentalluoroethane (R125) were measured with an adiabatic calorimeter. Temperatures ranged from their triple points to 345 K, and pressures up to 35 MPa. Measurements were conducted on the liquid in equilibrium with its vapor and on compressed liquid samples. The samples were of a high purity,

T. O. Lüddecke; J. W. Magee

1996-01-01

410

IMPORTANCE OF HIGH POWER DENSITY BOILING-WATER REACTOR DEVELOPMENT TO WIDE SPREAD ECONOMIC NUCLEAR POWER  

Microsoft Academic Search

The goals, economic advantages, and status of high power density ; development in boiling water reactors are discussed. The incentives and ; disadvantages of high power density development are compared, and it is concluded ; that the development will lead to reduced nuclear power costs. High power ; density operating experience will be acquired from the Big Rock Point Nuclear

D. H. Imhoff; S. Levy

1962-01-01

411

Contaminant Recovery during In-Situ Boiling in Rock  

NASA Astrophysics Data System (ADS)

In-situ boiling may be an effective mechanism for removing contaminants from tight rock matrix where they would otherwise be all but inaccessible. Heating the matrix above the boiling temperature and then depressurizing will induce boiling that leads to large gas-phase pressure gradients and a steam stripping effect that can remove the contaminants from the matrix. Despite the promise of this process, it has not yet been demonstrated in the field or laboratory, and the controlling parameters and limits of the process are poorly understood. The objective of this project is to characterize mass transfer during boiling in saturated rock. We built an experimental apparatus to heat cores (5cmx30cm) of contaminated rock in a pressurized vessel. The core was sealed in Teflon tube with metal end caps and wrapped with a strip heater. Additional heaters were located in the end caps. Sensors were placed on the surface and embedded within the core to monitor the temperature. An insulation layer covered the strip heater to minimize the heat loss. A recent test was conducted using Berea sandstone (18 millidarcy) initially saturated with de-aired water and contaminated by injecting 200ml (about 2 pore volumes) containing 200mg/L of 1,2-dichloroethane (1,2-DCA), 10 mg/L of chlorobenzene (CB), and 195 mg/L sodium bromide (NaBr). The solution was circulated and both inlet and outlet concentrations were monitored. After the contaminant injection, both the inlet and outlet valves were closed and the core was heated at a constant power of 31.3 watts. Pressure and temperature increased for 3 hours until temperatures exceeded 100 C. A valve on the outlet tube was opened and steam flow started immediately and was routed through a condenser. Concentrations of chlorinated solvents in the outflow increased abruptly to between 6 and 10 times the input concentration. The concentrations decreased after a few 10s of ml were recovered, and at least 80 to 90 percent of the contaminant masses were recovered in less than half of a pore volume of water. Interestingly, bromide was essentially absent from the recovered water containing the chlorinated solvents. These observations indicate that contaminants were stripped by a continuous steam phase that developed in the pore space of the sandstone throughout the length of the core. Volatile compounds were effectively transported to the steam-filled channels while leaving the non-volatile ionic compounds behind in the remaining water. This is significant because experimentally demonstrating this steam stripping mechanism is the first step toward developing a technique for effectively recovering contaminants from the matrix of fractured rock.

Chen, F.; Liu, X.; Falta, R. W.; Murdoch, L. C.

2009-12-01

412

Direct measurement of facet temperature up to melting point and COD in high-power 980-nm semiconductor diode lasers  

Microsoft Academic Search

The authors describe a straightforward experimental technique for measuring the facet temperature of a semiconductor laser under high-power operation by analyzing the laser emission itself. By applying this technique to 1-mm-long 980-nm lasers with 6- and 9-?m-wide tapers, they measure a large increase in facet temperature under both continuous wave (CW) and pulsed operation. Under CW operation, the facet temperature

Stephen John Sweeney; Leslie Jamieson Lyons; Alfred R. Adams; Daren Alfred Lock

2003-01-01

413

Boiling inception in volume-heated liquids  

SciTech Connect

Analysis of the transition phase of a hypothetical core disruptive accident in an LMFBR has indicated that the core would probably consist of a boiling mixture of fuel and steel, temporarily confined by massive blockages of fuel and/or steel, both above and below. Recriticality of the core depends to a great extent upon the hydrodynamic state of the fuel/steel mixture. Experiments have been performed with non-reactor materials to determine the behavior of such pools, in particular the average and local distribution of vapor. These experiments indicate that one dimensional drift flux calculations are not satisfactory for determining void profiles in internally boiling liquids, since they neither predict the boiling onset and stratified behavior nor agree with measured void profile data. This observation casts serious doubt upon the applicability of hydrodynamic analog experiments for determination of void distribution behavior of volumetrically boiling liquids. Further analysis is underway to develop appropriate models for the prediction of vapor distribution in volume-heated liquids to include determination of boiling onset as well as subsequent void fraction distribution. 9 refs., 2 figs.

Greene, G.A.; Reilly, S.M.

1981-01-01

414

A Study of the Microwave Brightness Temperature of Snow from the Point of View of Strong Fluctuation Theory  

Microsoft Academic Search

An application of strong fluctuation theory to the computation of the brightness temperature of dry and wet isothermal snowpacks is made. The numerical problems associated with computations are analyzed for the case of plane boundaries but arbitrary structure in the vertical direction. Comparisons of computed effective dielectric constants as well as brightness temperatures with experimental observations are made. The generally

Alex Stogryn

1986-01-01

415

The influence of oil on nucleate pool boiling heat transfer  

NASA Astrophysics Data System (ADS)

The influence of various oil contents in R134a is investigated for nucleate pool boiling on copper tubes either sandblasted or with enhanced heating surfaces (GEWA-B tube). Polyolester oils (POE) (Reniso Triton) with medium viscosity 55 cSt (SE55) and high viscosity 170 cSt (SE170) were used. Heat transfer coefficients were obtained for boiling temperatures between -28.6 and +20.1°C. The oil content varied from 0 to 5% mass fraction. For the sandblasted tube and the SE55 oil the heat transfer coefficients for the refrigerant/oil-mixture can be higher or lower than those for the pure refrigerant, depending on oil mass fraction, boiling temperature and heat flux. In some cases the highest heat transfer coefficients were obtained at a mass fraction of 3%. For the 170 cSt oil there is a clear decrease in heat transfer for all variations except for a heat flux 4,000 W/m2 and -10.1°C at 0.5% oil content. The heat transfer coefficients are compared to those in the literature for a smooth stainless steel tube and a platinum wire. For the enhanced tube and 55 cSt oil the heat transfer coefficients are clearly below those for pure refrigerant in all cases. The experimental results for the sandblasted tube are compared with the correlation by Jensen and Jackman. The calculated values are within +20 and -40% for the medium viscosity oil and between +50% and -40% for the high viscosity oil. A correlation for predicting oil-degradation effects on enhanced surfaces does not exist.

Spindler, Klaus; Hahne, Erich

2009-05-01

416

A Mid-IR Pyrometer Calibrated with High-Temperature Fixed Points for Improved Scale Realization to 2,500°C  

NASA Astrophysics Data System (ADS)

Glass surface temperature can be measured using a radiation thermometer operating at a mid-IR wavelength, typically the 3 5 ?m band, where the glass is opaque. For optical fiber preforms, the temperature measurement requirement may exceed 2,200°C. Scale realization at national measurement institutes at these temperatures is usually carried out at short wavelengths, typically less than 1 ?m. The mismatch in wavelength can lead to significant uncertainties when calibrating a radiation thermometer working at 3 5 ?m. To overcome this, a narrow band 3.95 ?m radiation thermometer has been built that is designed to be used from 1,000 to 2,500°C. It is calibrated by measurement of high-temperature metal carbon eutectic fixed-points. The instrument is based on silicon lenses, with a liquid nitrogen (LN2)-cooled InSb detector, and narrow-band interference filter. An anti-reflection coated objective lens/aperture stop focuses onto a field stop giving a 1 mm target, then a collimating lens, and glare stop. All parts visible to the detector, other than the target area, are either at LN2 temperature or are part of a temperature-stabilized housing. A relay-operated shutter that blocks the field stop is used to subtract the background. The size-of-source effect of the instrument has been measured. Gold-point measurements have been made to assess the stability. The device has been calibrated using high-temperature fixed points. A three-parameter fit has been applied and the resultant scale compared to an ITS-90 realization.

Lowe, David; McEvoy, H. C.; Owen, M.

2007-12-01

417

Flow Boiling Heat Transfer to Lithium Bromide Aqueous Solution in Subcooled Region  

NASA Astrophysics Data System (ADS)

A theoretical prediction model of the boiling heat transfer coefficient in the subcooled region for water and lithium bromide aqueous solution flowing in a rectangular channel is proposed. In the present heat transfer model, a heat flux is assumed to consist of both the forced convective and the boiling effect components. The forced convective component is evaluated from the empirical correlation of convective heat transfer coefficient for single-phase flow considering the effect of increase of liquid velocity due to net vapor generation. Empirical correlations for determining the heat flux due to the boiling effect and the quality at the onset point of net vapor generation are obtained from the data presented in the first report1). Agreement between the present theoretical prediction and the experimental data is satisfactorily good both for water and lithium bromide aqueous solution.

Kaji, Masao; Furukawa, Masahiro; Nishizumi, Takeharu; Ozaki, Shinji; Sekoguchi, Kotohiko

418

Wave soldering with a low melting point Bi-Sn Alloy: Effects of soldering temperatures and circuit board finishes  

Microsoft Academic Search

Wave soldering with low solid fluxes at temperatures as low as 175C on test boards with a Cu\\/Imidazole surface finish has\\u000a been shown to be feasible using a Pb-free, Bi-45%Sn-0.33%Ag solder that melts at temperatures of ?140?145C. Other surface\\u000a finishes such as Pd\\/Ni, Au\\/Ni, and Bi exhibit unacceptable soldering at temperatures below 210C. Intermediate in performance\\u000a are Sn surface finishes,

M. Mc Cormack; I. Artaki; S. Jin; A. M. Jackson; D. M. Machusak; G. W. Kammlott; D. W. Finley

1996-01-01

419

The study of Curie point shifts in Fe(Ni)-based glasses induced by hydrogen absorption and low temperature storage  

NASA Astrophysics Data System (ADS)

In this contribution, the influence of hydrogen absorption and low temperature treatments (77K) on the evolution of amorphous Curie temperature shift (?TCam) is investigated in some of FeNi and Fe-based glasses. TC shifts of both types of alloys are surprisingly stable at higher temperatures and behave as a structural imprint in the investigated samples. The origin of these structural imprints is analyzed on the basis of Bethe-Slater conception, supposing the existence of quenched-in phase reminiscences in glassy alloys, being inherited from the super-cooled melt.

Bán, K.; Ková?, J.; Novák, L.

2009-01-01

420

Leidenfrost point reduction on micropatterned metallic surfaces.  

PubMed

Droplets are able to levitate when deposited over a hot surface exceeding a critical temperature. This is known as the Leidenfrost effect. This phenomenon occurs when the surface is heated above the so-called Leidenfrost point (LFP), above which the vapor film between the droplet and hot surface is able to levitate the droplet. Such a critical temperature depends on several factors. One of the most studied parameters has been the surface roughness. Almost all of the experimental studies in the literature have concluded that the LFP increases with the roughness. According to these results, it seems that the roughness is detrimental for the stability of the vapor film. In contrast with these results, we present here a micropatterned surface that significantly reduces the LFP. The temperature increase, relative to the boiling point, required to reach the LFP is 70% lower than that on the flat surface. The reasons for such an effect are qualitatively and quantitatively discussed with a simple semiempirical model. This result can be relevant to save energy in applications that take advantage of the Leidenfrost effect for drop control or drag reduction. PMID:23020737

del Cerro, Daniel Arnaldo; Marín, Alvaro G; Römer, Gertwillem R B E; Pathiraj, B; Lohse, Detlef; Huis in 't Veld, Albertus J

2012-10-08

421

Boiling as Household Water Treatment in Cambodia: A Longitudinal Study of Boiling Practice and Microbiological Effectiveness  

PubMed Central

This paper focuses on the consistency of use and microbiological effectiveness of boiling as it is practiced in one study site in peri-urban Cambodia. We followed 60 randomly selected households in Kandal Province over 6 months to collect longitudinal data on water boiling practices and effectiveness in reducing Escherichia coli in household drinking water. Despite > 90% of households reporting that they used boiling as a means of drinking water treatment, an average of only 31% of households had boiled water on hand at follow-up visits, suggesting that actual use may be lower than self-reported use. We collected 369 matched untreated and boiled water samples. Mean reduction of E. coli was 98.5%; 162 samples (44%) of boiled samples were free of E. coli (< 1 colony-forming unit [cfu]/100 mL), and 270 samples (73%) had < 10 cfu/100 mL. Storing boiled water in a covered container was associated with safer product water than storage in an uncovered container.

Brown, Joseph; Sobsey, Mark D.

2012-01-01

422

6. View of first panel point from south end showing ...  

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

6. View of first panel point from south end showing chord, diagonals and vertical member connection at pin - Bridge No. 2.4, Spanning Boiling Fork Creek at Railroad Milepost JC-2.4, Decherd, Franklin County, TN

423

Prediction of Flash Point Temperature of Organic Compounds Using a Hybrid Method of Group Contribution + Neural Network + Particle Swarm Optimization  

Microsoft Academic Search

The flash points of organic compounds were estimated using a hybrid method that includes a simple group contribution method (GCM) implemented in an artificial neural network (ANN) with particle swarm optimization (PSO). Different topologies of a multilayer neural network were studied and the optimum architecture was determined. Property data of 350 compounds were used for training the network. To discriminate

Juan A. Lazzús

2010-01-01

424

Experimental study and modeling of nucleate boiling during free planar liquid jet impingement  

Microsoft Academic Search

Determination of boiling heat transfer rate during liquid jet impingement cooling (LJIC) depends on the intensity of bubble generation that is dependent on many flow and surface conditions such as jet velocity, liquid temperature, and surface superheat. Many empirical correlations have been developed previously to determine the total wall heat flux under various LJIC flow velocity, subcooling and surface superheat.

Ahmed M. T Omar

2010-01-01

425

Mechanism supported by extensive experimental evidence to explain high heat fluxes observed during nucleate boiling  

Microsoft Academic Search

The mechanism responsible for high heat transfer rates occurring in nucleate boiling when liquid films exist on the heating surface is described. High-speed cinematography and simultaneous transient surface temperature measurements provide a basis for describing the mechanism. In a liquid film, bubbles grow and detach rapidly. The film is quickly renewed. A liquid microlayer exists beneath a bubble its entire

Russell Mesler

1976-01-01

426

Microelectronic cooling by enhanced pool boiling of a dielectric fluorocarbon liquid  

SciTech Connect

An experimental study of boiling heat transfer from a simulated microelectronic component immersed in a stagnant pool of the dielectric Fluorinert (FC-72) is presented. Various enhancement surfaces were attached to an electrically heated copper calorimeter bar having a vertically oriented heat transfer surface area of 12.7 {times} 12.7 mm{sup 2}. A number of enhancement schemes aimed at a reduction of the incipience temperature overshoot were tested, employing various arrangement of fins, studs, grooves, and vapor-trapping cavities. Atmospheric pressure testing revealed a variation in the magnitude of boiling curve incipience temperature excursion as a function of both macro- and microcharacterization of the surface geometry and initial conditions (pressure and temperature history) prior to boiling. Increased incipience temperatures accompanied prolonged periods of nonboiling. It is assumed that this is due to vapor embryos within surface cavities collapsing to smaller radii. Large artificially created cavities (0.3 mm diameter) were found incapable of maintaining a stable vapor embryo for time periods greater than 10 min. In comparison to flat surfaces, low-profile surface geometries having a structure scale of the order of one bubble departure diameter resulted in significant enhancement of nucleate boiling while drilled surfaces had minimal effectiveness. Surface finish and artificial cavities had no effect on CHF, but levels of critical heat flux computed on base area were strongly dependent on macrogeometry, due in part to increased surface area.

Anderson, T.M.; Mudawar, I. (Purdue Univ., West Lafayette, IN (United States))

1989-08-01

427

Effect of irradiation in extending the storage life of boiled Chub mackerel (Rastrelliger spp).  

National Technical Information Service (NTIS)

Effect of irradiation at doses of 0.1, 0.2, or 0.3 Mrad in extending the storage life of boiled Chub mackerel held at room temperature was described. Total aerobic count, trimethylamine nitrogen, and total volatile basic nitrogen contents were used and ob...

P. Loaharanu C. Prompubesara S. Songprasertchai K. Kraisorn

1971-01-01

428

The stress corrosion cracking behavior of austenitic stainless steels in boiling magnesium chloride solutions  

Microsoft Academic Search

The change in the mechanism of stress corrosion cracking with test temperature for Type 304, 310 and 316 austenitic stainless steels was investigated in boiling saturated magnesium chloride solutions using a constant load method. Three parameters (time to failure; tf, steady-state elongation rate; lss and transition time at which a linear increase in elongation starts to deviate; tss) obtained from

Osama M. Alyousif; Rokuro Nishimura

2007-01-01

429

COTTAP; A computer code for simulation of thermal transients in secondary containments of boiling water reactors  

Microsoft Academic Search

This paper reports on the Compartment Transient Temperature Analysis Program (COTTAP) postaccident boiling water reactor (BWR) secondary containment thermal analysis. The code makes use of previously developed implicit temporal integration methods and sparse matrix inversion techniques to allow modeling of an entire BWR secondary containment. Investigations were made with a model consisting of 121 compartments and 767 heat-conducting slabs. The

M. A. Chaiko; M. J. Murphy

1991-01-01

430

A STUDY ON THE CRITICAL HEAT FLUX TEMPERATURE  

Microsoft Academic Search

A boiling curve has a functional relationship between the transferred heat flux and surface temperature of the heated wall. The maximum heat flux is usually called Critical Heat Flux in a boiling curve. Critical Heat Flux (CHF) is the maximum rate of thermal energy that can be transferred per surface area. Dryout and departure from nucleate boiling (DNB) distinguish two

Sabiha Yildiz; Gerhart Bartsch

431

Apparatus to measure liquid helium boil-off from low-loss superconducting current leads  

SciTech Connect

A low-loss liquid helium dewar was constructed to measure the liquid helium boil-off rate from high-temperature superconducting current leads. The dewar has a measured background heat leakage rate of 12 mW. Equations calculating the heat leakage rate from the measured vapor mass flow rate in liquid helium boil-off experiments are derived. Parameters that affect the experiments, such as density ratio, absolute pressure, and rate of pressure variation, are discussed. This study is important as superconducting current leads may be used in superconducting magnetic energy storage systems.

Cha, Y.S.; Niemann, R.C.; Hull, J.R. [Argonne National Lab., IL (United States). Energy Technology Div.

1995-06-01

432

Near-critical fluid boiling  

Microsoft Academic Search

When co-existing gas and liquid phases of pure fluid are heated through their critical point, large scale density fluctuations make the fluid extremely compressible, expandable, slows the diffusive transport, and decreases the contact-angle to zero (perfect wetting by the liquid phase). We have performed experiments on near-critical fluids in weightlessness on several missions on the Mir space station using the

John Hegseth; Vadim Nikolayev; Yves Garrabos; Daniel Beysens

2001-01-01

433

Influence of the temperature and rate of generation of point defects on the processes of deformation-induced segregation in the Fe-Cr-Ni alloy  

Microsoft Academic Search

The process of nickel segregation at grain boundaries in the Fe-Cr-Ni alloy upon severe plastic deformation has been investigated\\u000a depending on the temperature. The kinetics of the formation of segregates has been studied by numerically solving diffusion\\u000a equations that take into account the generation and absorption of point defects and their mutual recombination. It has been\\u000a shown that the Ni

S. A. Starikov; A. R. Kuznetsov; V. V. Sagaradze; V. A. Pechenkin; I. A. Stepanov

2010-01-01

434

An Investigation of Graduate Scientists' Understandings of Evaporation and Boiling.  

ERIC Educational Resources Information Center

|Uses a video presentation of six situations relating to the evaporation and boiling of liquids and the escape of dissolved gases from solution and investigates graduate scientists' understanding of the concepts of boiling and evaporation. (Author/YDS)|

Goodwin, Alan; Orlik, Yuri

2000-01-01

435

An Investigation of Graduate Scientists' Understandings of Evaporation and Boiling.  

ERIC Educational Resources Information Center

Uses a video presentation of six situations relating to the evaporation and boiling of liquids and the escape of dissolved gases from solution and investigates graduate scientists' understanding of the concepts of boiling and evaporation. (Author/YDS)

Goodwin, Alan; Orlik, Yuri

2000-01-01

436

Estimating the Impurity Concentration Factor on the Boiling Heat Transfer Surface of a Simulated Steam-Generator Tube-Support-Plate Crevice Using an In Situ High-Temperature Conductivity Measurement Technique  

SciTech Connect

To clarify the concentration behavior of sodium hydroxide, which is a representative impurity in the pressurized water reactor (PWR) secondary water coolant of a heat transfer crevice, an in situ high-temperature aqueous conductivity measurement cell was designed with the simulated tube support plate crevice of a PWR steam generator. The concentration factors of sodium hydroxide were calculated from the results of the conductivity measurement, and the effects of heat flux and solution temperature on the concentration factors were also examined. The conductivities in the crevice were measured in deaerated sodium hydroxide aqueous solutions in a range from 260 to 280 deg. C.The main test results show that the conductivity of high-temperature water increased with an increase of concentration and temperature in the deaerated sodium hydroxide solution and that the conductivity in the tube-tube-support-plate crevice was higher than that of bulk water because of concentrated sodium hydroxide in a crevice. Therefore, this method is applicable to evaluation of the impurity concentration behavior in a crevice. The calculated results of the concentration factor reveal that the factor was {approx}2000 in the range of the heat flux, i.e., the range for the region of a dry and wet condition, and the concentration factors in the sodium hydroxide solutions were lower than those of the field data.

Kawamura, Hirotaka; Hirano, Hideo [Central Research Institute of the Electric Power Industry (Japan)

2000-03-15

437

Fugacity coefficients of H 2 , CO 2 , CH 4 , H 2 O and of H 2 O- CO 2 CH 4 mixtures: A virial equation treatment for moderate pressures and temperatures applicable to calculations of hydrothermal boiling  

Microsoft Academic Search

Equations derived from a quadratic virial equation in pressure, with virial coefficients expressed as a function of temperature, are fitted to published P - V - T and solubility data to yield values of second and third virial coefficients for pure and mixed gases. These coefficients are not virial coefficients sensu stricto and are used to compute fugacity coefficients of

Nicolas F. Spycher; Mark H. Reed

1988-01-01

438

Heat rejection from R744 flow under uniform temperature cooling in a horizontal smooth tube around the critical point  

Microsoft Academic Search

Heat rejection from CO2 flow near the critical point, where commercial refrigerators spend most of their operating hours, was investigated in this study. Experimental results on the heat transfer coefficient and pressure drop of mass flux from 100 to 240 kg m?2 s?1 at pressures from 5 to 7.5 MPa in a horizontal smooth tube of 6.1 mm inner diameter are provided and compared with

Chieko Kondou; Pega Hrnjak

2011-01-01

439

Effect of prescribed temperature on mixed convection boundary layer in the unsteady stagnation point flow toward a stretching vertical sheet  

NASA Astrophysics Data System (ADS)

The solution to the unsteady mixed convection boundary layer flow and heat transfer problem due to a stretching vertical surface is presented in this paper. The unsteadiness in the flow and temperature fields is caused by the time-dependent of the stretching velocity and the surface temperature. The effects of the unsteadiness parameter, buoyancy parameter and Prandtl number on the flow and heat transfer characteristics are thoroughly examined. It is observed that the solutions exist for all values of buoyancy parameter. Comparison with known results for steady-state flow is excellent.

Nik Long, N. M. A.; Koo, L. F.; Wong, T. J.; Suali, M.

2013-09-01

440

Thermal analysis of a solar collector containing a boiling fluid  

SciTech Connect

The thermal performance of a flat-plate solar collector containing a boiling fluid is analyzed for steady-state thermosiphon operation. Collectors containing a boiling fluid have a thermal efficiency that is inherently greater than a non-boiling collector having the same value of the thermal parameter a (see Nomenclature). The general validity of the analysis is established by experimental data taken on an R-11 charged boiling collector in natural sunlight.

Al-Tamimi, A.I.; Clark, J.A.

1983-06-01

441

Vacuum membrane distillation by microchip with temperature gradient.  

PubMed

A multilayered microchip (25 x 95 mm) used for vacuum distillation is designed, fabricated and tested by rectification of a water-methanol mixture. The polymer chip employs a cooling channel to generate a temperature gradient along a distillation channel below, which is separated into a channel (72 microm deep) for liquid phase and a channel (72 microm deep) for vapor phase by an incorporated microporous poly(tetrafluoroethylene) (PTFE) membrane. The temperature gradient is controlled by adjusting hotplate temperature and flow rate of cooling water to make the temperatures in the stripping section higher than the increasing boiling points of the water-enriched liquids and the temperatures in the rectifying section lower than the decreasing dew points of the methanol-enriched vapors. The effects of temperature gradient, feed composition, feed flow rate and membrane pore size on the micro distillation are also investigated. A theoretical plate number up to 1.8 is achieved at the optimum conditions. PMID:20300677

Zhang, Yaopeng; Kato, Shinji; Anazawa, Takanori

2010-01-18

442

Boiling and condensing pumped loop microgravity experiment  

Microsoft Academic Search

Aircraft testing of a boiling and condensing (two-phase) pumped loop system was conducted to investigate transient induced by low gravity (Keplerian) maneuvers. The experiment, unchanged, will repeat a selected aircraft test sequence during its flight aboard a suborbital rocket. Such a test of a two-phase system has never been done. A comparison of aircraft and rocket data, particularly equilibrium conditions,

Vaughn H. Standley; Jerry F. Fairchild

1991-01-01

443

Sampling System for a Boiling Reactor NPP.  

National Technical Information Service (NTIS)

Investigations and pilot running of the nuclear power plant with a VK-50 boiling reactor reveal the necessity of normalizing the design system of water sampling and of mandatory replacement of the needle-type throttle device by a helical one. A method for...

A. I. Zabelin E. D. Yakovleva Y. A. Solov'ev

1976-01-01

444

Big Bubbles in Boiling Liquids: Students' Views  

ERIC Educational Resources Information Center

|The aim of this study was to elicit students' conceptions about big bubbles in boiling liquids (water, ethanol and aqueous CuSO[subscript 4] solution). The study is based on twenty-four students at different ages and grades. The clinical interviews technique was conducted to solicit students' conceptions and the interviews were analyzed to…

Costu, Bayram

2008-01-01

445

THE HALDEN BOILING HEAVY WATER REACTOR  

Microsoft Academic Search

The project, officiaily designated as HBWR, was undertaken in 1956 by ; the Norwegian Institutt for Atomenergi as builder and owner. Project HBWR was ; conceived as a nuclear power experiment for the studying of the physical and ; technological aspects of a heavy water moderated reactor under boiling conditions ; at a power level above 10 Mw thermal. The

N. Hidle; O. Dahl

1959-01-01

446

Pool boiling heat transfer to electrolyte solutions  

Microsoft Academic Search

Pool boiling heat transfer coefficients were measured for solutions of salts with positive solubility in water. The effect of the dissolved salts on nucleation site density, bubble departure diameter and bubble frequency was also investigated. The results show that at low heat fluxes heat transfer coefficients can be considerably lower than corresponding values for distilled water. At high heat fluxes

M. Jamialahmadi; A. Helalizadeh; H. Müller-Steinhagen

2004-01-01

447

Classic and Hard-Boiled Detective Fiction.  

ERIC Educational Resources Information Center

|Through an analysis of several stories, this paper defines the similarities and differences between classic and hard-boiled detective fiction. The characters and plots of three stories are discussed: "The Red House" by A. A. Milne; "I, The Jury" by Mickey Spillane; and "League of Frightened Men" by Rex Stout. The classic detective story is…

Reilly, John M.

448

Aspects of proximity effect in tunneling and point-contact spectroscopies of high-critical-temperature superconductors  

Microsoft Academic Search

In this paper the possibility that high critical temperature superconductor (HCTS) electrodes are non homogeneous is considered. The effect of such a configuration on current vs. voltage characteristics in HCTS junctions is analyzed and modelled in significative limits. Typical features, such as the depression of gap structures and finite zero bias conductances, are explained according to the proposed model. This

Francesco Tafuri; A. DiChiara; F. Fontana; G. Peluso

1994-01-01

449

Genetic toxicity of high-boiling petroleum substances.  

PubMed

There are several specific types of high-boiling petroleum substances (HBPS) having final boiling points >343°C, in which genetic toxicity can be related to the content of polycyclic aromatic compounds (PACs), specifically crude oils, gas oils, heavy fuel oils, lubricant base oils, waxes and aromatic extracts. Evaluation of optimized Salmonella tests covering over 250 samples from 43 types of HBPS revealed that gene mutation can be determined for these substances using a protocol optimized for the detection of mutagenic PAC. The outcomes of modified Salmonella assays can be predicted using HBPS compositional information as input to a newly developed statistical model. The general outcome of the optimized Salmonella assay can be predicted for an untested substance based on its Aromatic Ring Class (ARC) profile. Review of the results from numerous cytogenetic tests showed that although a few positive study results have been reported, most HBPS do not produce chromosomal effects when tested in rodent bone marrow assays or in in vitro chromosomal aberration assays. Results of both bacterial and cytogenetic studies can be used to satisfy genetic toxicity endpoints for the HBPS category substances. PMID:23685115

McKee, Richard H; Schreiner, Ceinwen A; Nicolich, Mark J; Gray, Thomas M

2013-05-14

450

Facilitating Conceptual Change in Students' Understanding of Boiling Concept  

NASA Astrophysics Data System (ADS)

The objective of this study was to construct a teaching strategy for facilitating students' conceptual understanding of the boiling concept. The study is based on 52 freshman students in the primary science education department. Students' ideas were elicited by a test consisting of nine questions. Conceptual change strategy was designed based on students' alternative conceptions. Conceptual change in students' understanding of boiling was evaluated by administering a pre-, post- and delayed post-test. The test scores were analysed both by qualitative and quantitative methods. Statistical analysis using one-way ANOVA of student test scores pointed to statistically significant differences in the tests and total scores ( p < 0.05). Quantitative analysis of students' responses on each test revealed different schema about changing their knowledge system. Both qualitative and quantitative analyses suggest that the teaching activities facilitated students' conceptual understanding. No statistically significant differences were found between post-test and delayed post-test scores, suggesting that the teaching strategy enabled students to retain their new conceptions in the long-term memory.

Co?tu, Bayram; Ayas, Alipa?a; Niaz, Mansoor; Ünal, Suat; Çalik, Muammer

2007-12-01

451

Certain Results of a Cinematographic Study of Bulk Boiling.  

National Technical Information Service (NTIS)

Modern ideas on the boiling process are based on the surface mechanism of heat exchange between a heat-releasing surface and a fluid heat-receiving coolant. Boiling bubbles can form at the surface or in the liquid. If in the liquid, the boiling is called ...

E. G. Prokofev V. N. Drulis Y. P. Yakovlev

1972-01-01

452

Fundamental issues related to flow boiling in minichannels and microchannels  

Microsoft Academic Search

Flow boiling in small hydraulic diameter channels is becoming increasingly important in many diverse applications. The previous studies addressing the effects of the channel size on the flow patterns, and heat transfer and pressure drop performance are reviewed in the present paper. The fundamental questions related to the presence of nucleate boiling and characteristics of flow boiling in microchannels and

Satish G. Kandlikar

2002-01-01

453

Molar heat capacity at constant volume of difluoromethane (R32) and pentafluoroethane (R125) from the triple-point temperature to 345 K at pressures to 35 MPa  

NASA Astrophysics Data System (ADS)

Molar heat capacities at constant volume ( C v) of dill uoromethane (R32) and pentalluoroethane (R125) were measured with an adiabatic calorimeter. Temperatures ranged from their triple points to 345 K, and pressures up to 35 MPa. Measurements were conducted on the liquid in equilibrium with its vapor and on compressed liquid samples. The samples were of a high purity, verified by chemical analysis of each fluid. For the samples, calorimetric results were obtained for two-phase ( C {v/(2)}), saturated liquid ( C ? or C' x ), and singlephase ( C v) molar heat capacities. The C ? data were used to estimate vapor pressures for values less than 0.3 MPa by applying a thermodynamic relationship between the saturated liquid heat capacity and the temperature derivatives of the vapor pressure. The triple-point temperature ( T tr) and the enthalpy of fusion (?fus H) were also measured for each substance. The principal sources of uncertainty are the temperature rise measurement and the change-ofvolume work adjustment. The expanded uncertainty (at the two-sigma level) for C v is estimated to be 0.7%, for C {v/(2)} it is 0.5%, and for C ? it is 0.7%.

Lüddecke, T. O.; Magee, J. W.

1996-07-01

454

Molar heat capacity at constant volume of difluoromethane (R32) and pentafluoroethane (R125) from the triple-point temperature to 345 K at pressures to 35 MPa  

SciTech Connect

Molar heat capacities at constant volume (C{sub v}) of difluoromethane (R32) and pentafluoroethane (R125) were measured with an adiabatic calorimeter. Temperatures ranged from their triple points to 345 K, and pressures up to 35 MPa. Measurements were conducted on the liquid in equilibrium with its vapor and on compressed liquid samples. The samples were of a high purity, verified by chemical analysis of each fluid. For the samples, calorimetric results were obtained for two-phase (C{sub v}{sup (2)}), saturated liquid (C{sub {sigma}} or C {prime}{sub x}), and single-phase (C{sub v}) molar heat capacities. The C{sub {sigma}} data were used to estimate vapor pressures for values less than 0.3 MPa by applying a thermodynamic relationship between the saturated liquid heat capacity and the temperature derivatives of the vapor pressure. The triple-point temperature (T{sub tr}) and the enthalpy of fusion ({Delta}{sub fus}H) were also measured for each substance. The principal sources of uncertainty are the temperature rise measurement and the change-of-volume work adjustment. The expanded uncertainty (at the two-sigma level) for C{sub v} is estimated to be 0.7%, for C{sub v}{sup (2)} it is 0.5%, and for C{sub {sigma}} it is 0.7%.

Lueddecke, T.O.; Magee, J.W. [National Inst. of Standards and Technology, Boulder, CO (United States)

1996-07-01

455

Cavity-to-cavity interaction in nucleate boiling: The effect of heat conduction within the heater  

SciTech Connect

This paper presents a numerical study aimed at analyzing bubble behavior as a function of site location. The effects of site distribution on the nucleate boiling curve are examined. Simple local-instantaneous models that mimic the bubble behavior on the boiling surface were implemented into a three-dimensional finite control volume conduction code. For a given site density, sample cases were run for uniform and nonuniform site distribution. The authors results indicate considerable deviation from linearized theories that always assume a uniform distribution. It is shown that bubble emission frequency is a strong function of site location. Consequently, the bubble flux density is shown to deviate from a simple periodic behavior with increasing nonuniformity in site distribution. This study further indicates that a uniform site distribution results in minimum area- and time-averaged surface superheat and minimum temperature variations on the boiling surface. As the distribution becomes less uniform, average surface temperature and surface temperature variations along the boiling surface increase. 19 refs., 1