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1

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

2

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.

Math Forum

2001-01-01

3

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.

Francis Eberle

2007-01-01

4

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

5

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.

6

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.

Paula Woods

7

Melting Point, Boiling Point, and Symmetry  

Microsoft Academic Search

The relationship between the melting point of a compound and its chemical structure remains poorly understood. The melting point of a compound can be related to certain of its other physical chemical properties. The boiling point of a compound can be determined from additive constitutive properties, but the melting point can be estimated only with the aid of nonadditive constitutive

Robert Abramowitz; Samuel H. Yalkowsky

1990-01-01

8

The boiling point of stratospheric aerosols.  

NASA Technical Reports Server (NTRS)

A photoelectric particle counter was used for the measurement of aerosol boiling points. The operational principle involves raising the temperature of the aerosol by vigorously heating a portion of the intake tube. At or above the boiling point, the particles disintegrate rather quickly, and a noticeable effect on the size distribution and concentration is observed. Stratospheric aerosols appear to have the same volatility as a solution of 75% sulfuric acid. Chemical analysis of the aerosols indicates that there are other substances present, but that the sulfate radical is apparently the major constituent.

Rosen, J. M.

1971-01-01

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 a…

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

Boiling of the interface between two immiscible liquids below the bulk boiling temperatures of both components.  

PubMed

We consider the problem of boiling of the direct contact of two immiscible liquids. An intense vapour formation at such a direct contact is possible below the bulk boiling points of both components, meaning an effective decrease of the boiling temperature of the system. Although the phenomenon is known in science and widely employed in technology, the direct contact boiling process was thoroughly studied (both experimentally and theoretically) only for the case where one of liquids is becoming heated above its bulk boiling point. On the contrary, we address the case where both liquids remain below their bulk boiling points. In this paper we construct the theoretical description of the boiling process and discuss the actualisation of the case we consider for real systems. PMID:25403831

Pimenova, Anastasiya V; Goldobin, Denis S

2014-11-01

12

Boiling of the Interface between Two Immiscible Liquids below the Bulk Boiling Temperatures of Both Components  

E-print Network

We consider the problem of boiling of the direct contact of two immiscible liquids. An intense vapour formation at such a direct contact is possible below the bulk boiling points of both components, meaning an effective decrease of the boiling temperature of the system. Although the phenomenon is known in science and widely employed in technology, the direct contact boiling process was thoroughly studied (both experimentally and theoretically) only for the case where one of liquids is becoming heated above its bulk boiling point. On the contrary, we address the case where both liquids remain below their bulk boiling points. In this paper we construct the theoretical description of the boiling process and discuss the actualisation of the case we consider for real systems.

Pimenova, Anastasiya V

2014-01-01

13

Boiling of the Interface between Two Immiscible Liquids below the Bulk Boiling Temperatures of Both Components  

E-print Network

We consider the problem of boiling of the direct contact of two immiscible liquids. An intense vapour formation at such a direct contact is possible below the bulk boiling points of both components, meaning an effective decrease of the boiling temperature of the system. Although the phenomenon is known in science and widely employed in technology, the direct contact boiling process was thoroughly studied (both experimentally and theoretically) only for the case where one of liquids is becoming heated above its bulk boiling point. On the contrary, we address the case where both liquids remain below their bulk boiling points. In this paper we construct the theoretical description of the boiling process and discuss the actualisation of the case we consider for real systems.

Anastasiya V. Pimenova; Denis S. Goldobin

2014-10-20

14

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

15

Size-exclusion chromatography for the determination of the boiling point distribution of high-boiling petroleum fractions.  

PubMed

The paper describes a new procedure for the determination of boiling point distribution of high-boiling petroleum fractions using size-exclusion chromatography with refractive index detection. Thus far, the determination of boiling range distribution by chromatography has been accomplished using simulated distillation with gas chromatography with flame ionization detection. This study revealed that in spite of substantial differences in the separation mechanism and the detection mode, the size-exclusion chromatography technique yields similar results for the determination of boiling point distribution compared with simulated distillation and novel empty column gas chromatography. The developed procedure using size-exclusion chromatography has a substantial applicability, especially for the determination of exact final boiling point values for high-boiling mixtures, for which a standard high-temperature simulated distillation would have to be used. In this case, the precision of final boiling point determination is low due to the high final temperatures of the gas chromatograph oven and an insufficient thermal stability of both the gas chromatography stationary phase and the sample. Additionally, the use of high-performance liquid chromatography detectors more sensitive than refractive index detection allows a lower detection limit for high-molar-mass aromatic compounds, and thus increases the sensitivity of final boiling point determination. PMID:25545251

Boczkaj, Grzegorz; Przyjazny, Andrzej; Kami?ski, Marian

2015-03-01

16

A Thermodynamic Analysis to Explain the Boiling-Point Isotope Effect for Molecular Hydrogen  

NASA Astrophysics Data System (ADS)

The analysis reported provides an explanation for the boiling-point isotope effect observed for molecular hydrogen isotopes (H2, D2, and T2); that is, an explanation for the increase in normal boiling point with increasing molecular mass. The standard enthalpy of vaporization is shown to depend on molecular mass, and itself is related to temperature via a standard solution to the Clausius-Clapeyron equation. Simplification of the solution, at standard pressure, yields an expression for the normal boiling point that depends on molecular mass. An evaluation of the expression, using constants obtained from two of the boiling points in the series, allows a prediction of the third boiling point. As an example, the predicted boiling point of ditritium is 24.9 K, in close agreement with the observed value of 25.0 K.

Blane Baker, D.; Christmas, Byron K.

2000-06-01

17

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

18

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

2012-10-01

19

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

E-print Network

The phenomenon of the glass transition is an unresolved problem of 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 tau(T) from dielectric spectroscopy and dynamic light scattering covering the range 10_-12 s < tau(T) < 10^2s. 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_inf and a low-temperature regime for which E_coop(T):= E(T) - E_inf increases while cooling. A two-parameter scaling is introduced, specifically E_coop(T)/E_inf = f[lambda(T/T_A -1)], where f is an exponential function, lambda a dimensionless parameter, and T_A a reference temperature proportional to E_inf. In order to describe tau(T), in addition, the attempt time tau_inf has to be specified. Thus, a single interaction parameter E_inf extracted from the high-temperature regime together with lambda controls the temperature dependence of low-temperature cooperative dynamics.

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

2012-04-27

20

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)] [Univ. of Florida, Gainesville, FL (United States)

1998-01-01

21

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

22

QSPR models of boiling point, octanolwater partition coefficient and retention time index of polycyclic aromatic hydrocarbons  

E-print Network

QSPR models of boiling point, octanol­water partition coefficient and retention time index) is presented. Three physicochemical properties related to their environmental impact are studied: boiling point

Ferreira, Márcia M. C.

23

DENSITIES AND BOILING POINTS OF URANYL NITRATE-NITRIC ACID SOLUTIONS  

Microsoft Academic Search

The intercycle evaporators in the Chemical Processing Plant are controlled by density-measuring instruments. Because of difficulties in controlling these evaporators in a satisfactory manner, a series of investigations was begun to measure the boiling points at the elevation of the CPP, and densities near boiling temperatures of a number of solutions in the uranyl nitrate-nitric acid-water system. From these data

Perkins

1953-01-01

24

Application of the COSMO-SAC-BP Solvation Model to Predictions of Normal Boiling Temperatures for Environmentally Significant Substances  

E-print Network

Application of the COSMO-SAC-BP Solvation Model to Predictions of Normal Boiling Temperatures perturbation theory. This COSMO-SAC-BP model was previously validated to successfully correlate normal boiling, herbicides, insecticides, and drugs,. The average absolute deviation in the predicted boiling points

Goddard III, William A.

25

Estimating the physicochemical properties of polyhalogenated aromatic and aliphatic compounds using UPPER: part 1. Boiling point and melting point.  

PubMed

The UPPER (Unified Physicochemical Property Estimation Relationships) model uses enthalpic and entropic parameters to estimate 20 biologically relevant properties of organic compounds. The model has been validated by Lian and Yalkowsky on a data set of 700 hydrocarbons. The aim of this work is to expand the UPPER model to estimate the boiling and melting points of polyhalogenated compounds. In this work, 19 new group descriptors are defined and used to predict the transition temperatures of an additional 1288 compounds. The boiling points of 808 and the melting points of 742 polyhalogenated compounds are predicted with average absolute errors of 13.56 K and 25.85 K, respectively. PMID:25022475

Admire, Brittany; Lian, Bo; Yalkowsky, Samuel H

2015-01-01

26

The Boiling Point of the Radium Emanation  

Microsoft Academic Search

IT was shown by Rutherford and Soddy in 1903 that the radium emanation was condensed from the gases with which it was mixed at a temperature of about -150° C. From observations of the range of temperature of condensation and volatilisation it was concluded that the condensed emanation exerted a sensible vapour pressure. This has been confirmed by later experiments,

E. Rutherford

1909-01-01

27

Optimal boiling temperature for ORC installation  

NASA Astrophysics Data System (ADS)

In the paper a research on cost-effective optimum design boiling temperature for Organic Rankine Cycle utilizing low-temperature heat sources is presented. The ratio of the heat exchanger area of the boiler to the power output is used as the objective function. Analytical relations for heat transfer area as well power of the cycle are formulated. Evaporation temperature and inlet temperature of the heat source medium as well its mass flow rate are varied in the optimization method. The optimization is carried out for three working fluids, i.e. R 134a, water and ethanol. The objective function (economics profitability, thermodynamic efficiency) leads to different optimal working conditions in terms of evaporating temperature. Maximum power generation in the near-critical conditions of subcritical ORC is the highest. The choice of the working fluid can greatly affect the objective function which is a measure of power plant cost. Ethanol exhibits a minimum objective function but not necessarily the maximum cycle efficiency.

Mikielewicz, Jaros?aw; Mikielewicz, Dariusz

2012-09-01

28

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

29

Characterizing preferential groundwater discharge through boils using temperature  

NASA Astrophysics Data System (ADS)

In The Netherlands, preferential groundwater discharge trough boils is a key process in the salinization of deep polders. Previous work showed that boils also influence the temperature in the subsurface and of surface water. This paper elaborates on this process combining field observations with numerical modeling. As is the case for salinity, a distinct anomaly in the subsurface and surface water temperature can be attributed to boils. Lines of equal temperature are distorted towards the boil, which can be considered as an upconing of the temperature profile by analogy of the upconing of a fresh-saltwater interface. The zone of this distortion is limited to the immediate vicinity of the boil, being about 5 m in the aquitard which holds the boil's conduit, or maximum a few dozens of meters in the underlying aquifer. In the aquitard, heat transport is conduction dominated whereas this is convection dominated in the aquifer. The temperature anomaly differs from the salinity anomaly by the smaller radius of influence and faster time to reach a new steady-state of the former. Boils discharge water with a temperature equal to the mean groundwater temperature. This influences the yearly and diurnal variation of ditch water temperature in the immediate vicinity of the boil importantly but also the temperature in the downstream direction. Temporary nature of the boil (e.g. stability of the conduit, discharge rate), uncertainty on the 3D construction of the conduit and heterogeneity of the subsoil make it unlikely that temperature measurements can be interpreted further than a qualitative level.

Vandenbohede, A.; de Louw, P. G. B.; Doornenbal, P. J.

2014-03-01

30

Pervaporation of ethanol and acetone above normal boiling temperatures  

SciTech Connect

Pervaporation experiments were performed at higher than normal feed liquid boiling temperatures by applying pressure to the feed compartment. Ethanol, acetone, and aqueous ethanol solutions were pervaporated through silicone rubber dense membranes. Large increases were observed in the permeate flow as the temperature rose above the liquid boiling temperature. Separation factors in aqueous ethanol pervaporation are not affected by these increases in permeate output, and they are in the same range as those obtained in conventional pervaporation.

Windmoeller, D.; Galembeck, F. (Univ. Estadual de Campinas, Sao Paulo (Brazil))

1992-08-01

31

Boils  

MedlinePLUS

... it open at home. This can spread the infection. Continue to put warm, wet compresses on the area after the boil opens. You may need to have surgery to drain deep or large boils. Get treatment from you health ...

32

Measurement of the absolute Quantum Efficiency of Hamamatsu model R11410-10 photomultiplier tubes at low temperatures down to liquid xenon boiling point  

E-print Network

We report on the measurements of the absolute Quantum Efficiency(QE) for Hamamatsu model R11410-10 PMTs specially designed for the use in low background liquid xenon detectors. QE was measured for five PMTs in a spectral range between 154.5 nm to 400 nm at low temperatures down to -110$^0$C. It was shown that during the PMT cooldown from room temperature to -110 $^0$C (a typical PMT operation temperature in liquid xenon detectors), the absolute QE increases by a factor of 1.1 - 1.15 at 175 nm. The QE growth rate with respect to temperature is wavelength dependent peaking at about 165 nm corresponding to the fastest growth of about -0.07 %QE/$^{0}C$ and at about 200 nm corresponding to slowest growth of below -0.01 %QE/$^{0}C$. A dedicated setup and methods for PMT Quantum Efficiency measurement at low temperatures are described in details.

Lyashenko, Alexey; Snyder, Adam; Wang, Hanguo; Arisaka, Katsushi

2014-01-01

33

Measurement of the absolute Quantum Efficiency of Hamamatsu model R11410-10 photomultiplier tubes at low temperatures down to liquid xenon boiling point  

NASA Astrophysics Data System (ADS)

We report on the measurements of the absolute Quantum Efficiency(QE) for Hamamatsu model R11410-10 PMTs specially designed for the use in low background liquid xenon detectors. QE was measured for five PMTs in a spectral range between 154.5 nm to 400 nm at low temperatures down to -110°C. It was shown that during the PMT cooldown from room temperature to -110°C (a typical PMT operation temperature in liquid xenon detectors), the absolute QE increases by a factor of 1.1–1.15 at 175 nm. The QE growth rate with respect to temperature is wavelength dependent peaking at about 165 nm corresponding to the fastest growth of about -0.07%QE/°C and at about 200 nm corresponding to slowest growth of below -0.01%QE/°C. A dedicated setup and methods for PMT Quantum Efficiency measurement at low temperatures are described in details.

Lyashenko, A.; Nguyen, T.; Snyder, A.; Wang, H.; Arisaka, K.

2014-11-01

34

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

35

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. PMID:22289265

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

2012-01-01

36

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

37

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

38

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

39

Teaching Structure-Property Relationships: Investigating Molecular Structure and Boiling Point  

ERIC Educational Resources Information Center

A concise, well-organized table of the boiling points of 392 organic compounds has facilitated inquiry-based instruction in multiple scientific principles. Many individual or group learning activities can be derived from the tabulated data of molecular structure and boiling point based on the instructor's education objectives and the students'…

Murphy, Peter M.

2007-01-01

40

Boiling temperatures and enthalpy changes of Essential oils  

Microsoft Academic Search

A capillary long neck glass sample holder is proposed for the determination of boiling temperatures of essential oils containing\\u000a a majority component. Essential oils from Aniba dukei K. and Pimenta dioica L. containing linalool and eugenol, respectively, as major constituents were used after optimization of parameters such as scan\\u000a rate, sample mass and starting temperature. Best performance in the determination

J. S. Chaar; V. E. Mouchreck-Filho; Susete T. Breviglieri; É. T. G. Cavalheiro; G. O. Chierice

2004-01-01

41

Hypothetical Thermodynamic Properties: The Boiling and Critical Temperatures of Polyethylene and Polytetrafluoroethylene  

E-print Network

Hypothetical Thermodynamic Properties: The Boiling and Critical Temperatures of Polyethylene. Louis, Missouri 63121 The normal (p ) 101.325 kPa) boiling-temperature behavior of a homologous series and approximately TB() ) 915 K for those related to polytetrafluoroethylene. Normal boiling temperatures have been

Chickos, James S.

42

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.

43

The accommodation coefficient of the liquid at temperatures below the boiling  

NASA Astrophysics Data System (ADS)

Are carried out experimental investigation of the laws of vaporization at temperatures below the boiling point. Is determined the mass rate of evaporation of distilled water in large intervals of time at different temperatures in order to sound conclusions about the stationarity of the process of evaporation of the liquid in the conditions of the experiments performed, and also studied the effect of temperature on the rate of evaporation. Accommodation coefficient is defined in the mathematical expression of the law of Hertz-Knudsen for standart substance used in the experiments.

Bulba, Elena E.

2015-01-01

44

Comparative biology and chemistry of boiling point fractions from different coal liquefaction processes  

SciTech Connect

Data on the chemical composition and toxicologic activity of narrow boiling point (bp) range distillate cuts from the non-catalytic solvent refined coal-I and -II processes, as well as from the catalytic H-Coal, EDS, and integrated two-stage liquefaction processes, were compiled and compared. Results revealed that processes using catalysts contained higher concentrations of alkylated and hydrogenated polycyclic aromatic hydrocarbons (PAH). In addition, lower concentrations of nitrogen-containing polycyclic aromatic compounds (NPAC), including amino-substituted PAH, were present in those materials from processes which used some form of catalytic hydrogenation. Regardless of process, the hydrogen content decreased and the nitrogen, oxygen, and sulfur heteroatomic content of the coal liquefaction materials increased as a function of increasing distillation temperature. In addition, aliphatic hydrocarbon content decreased while the NPAC and hydroxy-substituted PAH content increased as a function of increasing bp temperature for all the coal liquefaction materials. 18 refs., 8 figs., 10 tabs.

Wright, C.W.; Chess, E.K.; Stewart, D.L.; Mahlum, D.D.; Later, D.W.; Lucke, R.B.; Pelroy, R.A.; Wilson, B.W.

1985-11-01

45

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

46

THE MEASUREMENT OF RAPID SURFACE TEMPERATURE FLUCTUATIONS DURING NUCLEATE BOILING OF WATER  

Microsoft Academic Search

The surface temperature during nucleate boiling was measured with a ; special thermocouple so designed as to measure the temperature of a small area ; and to have an extremely rapid response time. The surface temperature was found ; to drop occasionally 20 to 30 deg F in about 2 msec during the boiling of water. ; This indicates a

Franklin D. Moore; Russell B. Mesler

1961-01-01

47

What Is the Boiling Point and Heat of Vaporization of Sulfuric Acid?  

ERIC Educational Resources Information Center

Discusses the values presented in various handbooks for the boiling point and heat of vaporization of sulfuric acid, noting discrepencies. Analyzes various approaches to data presentation, discussing the data on sulfuric acid in light of the Trouton constant. Points out the need for a more critical use of tables. (JM)

Myers, R. Thomas

1983-01-01

48

Low-boiling-point solvent additives can also enable morphological control in polymer solar cells  

SciTech Connect

Processing organic photovoltaic (OPV) blend solutions with high-boiling-point solvent additives has recently been used for morphological control in bulk-heterojunction OPV cells. Here we show that even low-boiling-point solvents can be effective additives. When P3HT:PCBM OPV cells were processed with a low-boiling-point solvent tetrahydrafuran as an additive in parent solvent o-dichlorobenzene, charge extraction increased leading to fill factors as high as 69.5%, without low work-function cathodes, electrode buffer layers or thermal treatment. This was attributed to PCBM demixing from P3HT domains and better vertical phase separation, as indicated by photoluminescence lifetimes, hole mobilities, and shunt leakage currents. Dependence on solvent parameters and applicability beyond P3HT system was also investigated. (C) 2013 Elsevier B.V. All rights reserved.

Mahadevapuram, Rakesh C. [Ames Laboratory; Carr, John A. [Ames Laboratory; Chen, Yuqing [Ames Laboratory; Bose, Sayantan [Ames Laboratory; Nalwa, Kanwar S. [Ames Laboratory; Petrich, Jacob W. [Ames Laboratory; Chaudhary, Sumit [Ames Laboratory

2013-11-02

49

Evaluation on environment-friendly refrigerants with similar normal boiling points in ejector refrigeration system  

NASA Astrophysics Data System (ADS)

Based on the "hypothetical throat area" theory and the "constant-pressure mixing" theory, a thermodynamic model for ejector was set up by introducing the real properties of refrigerants. Refrigerants which have similar normal boiling points with each other may act as replacement to each other in substitute progress. In this paper, eight environment-friendly refrigerants were divided into 4 pairs for study according to their normal boiling point. In each refrigerant pair, the entrainment ratios of ejector, system COP, pump power et al. of refrigerants were compared and analyzed. Lastly, the performances of the transcritical and subcritical ejector refrigeration cycles with propylene were calculated and compared.

Wang, F.; Shen, S. Q.; Li, D. Y.

2014-12-01

50

Dependences between the boiling point of binary aqueous-organic mixtures and their composition  

NASA Astrophysics Data System (ADS)

The optimum three-parametric regression basis set that reflects the properties of permutation symmetry and takes into account the specificity of isobars of aqueous-organic mixtures is constructed. The optimum algorithm for the calculation of the regression parameters of the boiling point isobars is proposed. The parameters are calculated for a series of systems. The accuracy of the method proposed for the regression description of the dependence of the boiling point of binary aqueous-organic mixtures on the composition is determined by empirical inaccuracies and is sufficient for the most part of practical applications. Methods for increasing the accuracy of the regression description of equilibrium homogeneous systems are formulated.

Preobrazhenskii, M. P.; Rudakov, O. B.

2015-01-01

51

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

52

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

53

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

54

2007-No54-BoilingPoint Health and Greenhouse Gas Impacts of Biomass and Fossil Fuel  

E-print Network

2007-No54-BoilingPoint Theme Health and Greenhouse Gas Impacts of Biomass and Fossil Fuel Energy of fossil-fuel energy systems. These scenarios are analysed for various environmental and health impacts from fossil fuels and other energy sources reported by IEA []. In all of these countries except Kenya

Kammen, Daniel M.

55

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

56

Numerical Study of Spatial Surface Temperature and Nucleation Site Density At High Heat Flux Pool Boiling  

E-print Network

] . The results indicate that nucleate boiling curve and critical heat flux point move to the lower superheat region with increasing surface roughness, which is in a good agreement with Bereson[1] 's experiment

Maruyama, Shigeo

57

Dynamic analysis of multiple nuclear-coupled boiling channels based on a multi-point reactor model  

Microsoft Academic Search

This work investigates the non-linear dynamics and stabilities of a multiple nuclear-coupled boiling channel system based on a multi-point reactor model using the Galerkin nodal approximation method. The nodal approximation method for the multiple boiling channels developed by Lee and Pan [Lee, J.D., Pan, C., 1999. Dynamics of multiple parallel boiling channel systems with forced flows. Nucl. Eng. Des. 192,

Jin Der Lee; Chin Pan

2005-01-01

58

Study of the depression of incipient boiling temperature and the enhancement of critical heat flux induced by ultrasonic wave on horizontal plate facing upward and downward  

SciTech Connect

The effects of an ultrasonic wave on nucleate-boiling heat transfer, focusing on depression of the incipient boiling temperature and enhancement of the critical heat flux (CHF) on horizontal plate facing upward and downward, were examined. Experiments were conducted using a copper thin film and saturated R-113 liquid for a pool condition at 0.10 MPa. The incipient boiling temperature was depressed by the ultrasonic wave incidence up to 10K in reheating experiments where the heat transfer surface had been immersed in the liquid following the previous boiling experiment. On the other hand, it was minimally affected when the boiling experiment started immediately after the test surface was immersed into the liquid. These results were considered to be related to the number of active nucleation sites available. The decrease of the incipient boiling temperature as the power of the ultrasonic wave was increased, however, did not depend on the frequency. It was pointed out that the depression of the incipient boiling temperature was caused by the local pressure increase caused by the ultrasonic wave incidence. The CHF was increased by the ultrasonic wave incidence up to a factor of five and increased by the ultrasonic wave incidence up to a factor of five and increased with the power of the ultrasonic wave. The enhancement of the CHF was caused by acoustic flow near the heating surface: the coalesce bubble on the heating surface was collapsed by the acoustic flow.

Ohtake, Hiroyasu; Koizumi, Yasuo

1999-07-01

59

Experimental & Numerical Investigation of Pool Boiling on Engineered Surfaces with Integrated Thin-flim Temperature Sensors  

E-print Network

Film Thermocouples (TFT) are micro-fabricated on test substrates to measure surface temperatures. A dielectric liquid refrigerant (PF-5060) is used as test fluid. Both nucleate and lm boiling regimes are investigated for the silicon test substrates...

Sathyamurthi, Vijaykumar

2011-02-22

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

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

62

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

63

Preparation and properties of low boiling point of alcohol and acetone-based magnetic fluid  

NASA Astrophysics Data System (ADS)

Ultra-fine magnetic particles are difficult to be dispersed in low boiling point solvents such as alcohol (C 1-C 4) and acetone. In this paper, we report the preparation methods of several alcohol and acetone-based magnetic fluids. The stability of magnetic fluid depended on the HLB (hydrophile-lipophile balance) of the solvent and alkyl chain lengths of organic layers. The fluid was most stable only when the HLB value of surfactant and the solvents are similar.

Fujita, T.; Miyazaki, T.; Nishiyama, H.; Jeyadevan, B.

1999-07-01

64

Boiling Point  

NASA Technical Reports Server (NTRS)

The author recounts his experiences he helped to investigate the accident which destroyed the Space Shuttle Challenger. The focus was on how he used novel approaches to investigate heat transfer in the shuttle's hydrogen tank, after an expert he sought for advice proved unhelpful.

Jansen, Michael C.

2002-01-01

65

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

PubMed

The distribution of distillation temperatures of liquid and semi-fluid products, including petroleum fractions and products, is an important process and practical parameter. It provides information on properties of crude oil and content of particular fractions, classified on the basis of their boiling points, as well as the optimum conditions of atmospheric or vacuum distillation. At present, the distribution of distillation temperatures is often investigated by simulated distillation (SIMDIS) using capillary gas chromatography (CGC) with a short capillary column with polydimethylsiloxane as the stationary phase. This paper presents the results of investigations on the possibility of replacing currently used CGC columns for SIMDIS with a deactivated fused silica capillary tube without any stationary phase. The SIMDIS technique making use of such an empty fused silica column allows a considerable lowering of elution temperature of the analytes, which results in a decrease of the final oven temperature while ensuring a complete separation of the mixture. This eliminates the possibility of decomposition of less thermally stable mixture components and bleeding of the stationary phase which would result in an increase of the detector signal. It also improves the stability of the baseline, which is especially important in the determination of the end point of elution, which is the basis for finding the final temperature of distillation. This is the key parameter for the safety process of hydrocracking, where an excessively high final temperature of distillation of a batch can result in serious damage to an expensive catalyst bed. This paper compares the distribution of distillation temperatures of the fraction from vacuum distillation of petroleum obtained using SIMDIS with that obtained by the proposed procedure. A good agreement between the two procedures was observed. In addition, typical values of elution temperatures of n-paraffin standards obtained by the two procedures were compared. Finally, the agreement between boiling points of polar compounds determined from their retention times and actual boiling points was investigated. PMID:21153592

Boczkaj, Grzegorz; Przyjazny, Andrzej; Kami?ski, Marian

2011-03-01

66

Experimental study of flash boiling spray vaporization through quantitative vapor concentration and liquid temperature measurements  

NASA Astrophysics Data System (ADS)

Flash boiling sprays of liquid injection under superheated conditions provide the novel solutions of fast vaporization and better air-fuel mixture formation for internal combustion engines. However, the physical mechanisms of flash boiling spray vaporization are more complicated than the droplet surface vaporization due to the unique bubble generation and boiling process inside a superheated bulk liquid, which are not well understood. In this study, the vaporization of flash boiling sprays was investigated experimentally through the quantitative measurements of vapor concentration and liquid temperature. Specifically, the laser-induced exciplex fluorescence technique was applied to distinguish the liquid and vapor distributions. Quantitative vapor concentration was obtained by correlating the intensity of vapor-phase fluorescence with vapor concentration through systematic corrections and calibrations. The intensities of two wavelengths were captured simultaneously from the liquid-phase fluorescence spectra, and their intensity ratios were correlated with liquid temperature. The results show that both liquid and vapor phase of multi-hole sprays collapse toward the centerline of the spray with different mass distributions under the flash boiling conditions. Large amount of vapor aggregates along the centerline of the spray to form a "gas jet" structure, whereas the liquid distributes more uniformly with large vortexes formed in the vicinity of the spray tip. The vaporization process under the flash boiling condition is greatly enhanced due to the intense bubble generation and burst. The liquid temperature measurements show strong temperature variations inside the flash boiling sprays with hot zones present in the "gas jet" structure and vortex region. In addition, high vapor concentration and closed vortex motion seem to have inhibited the heat and mass transfer in these regions. In summary, the vapor concentration and liquid temperature provide detailed information concerning the heat and mass transfer inside flash boiling sprays, which is important for the understanding of its unique vaporization process.

Zhang, Gaoming; Hung, David L. S.; Xu, Min

2014-08-01

67

Boiling Heat Transfer Measurements on Highly Conductive Surfaces Using Microscale Heater and Temperature Arrays  

NASA Technical Reports Server (NTRS)

Two systems have been developed to study boiling heat transfer on the microscale. The first system utilizes a 32 x 32 array of diodes to measure the local temperature fluctuations during boiling on a silicon wafer heated from below. The second system utilizes an array of 96 microscale heaters each maintained at constant surface temperature using electronic feedback loops. The power required to keep each heater at constant temperature is measured, enabling the local heat transfer coefficient to be determined. Both of these systems as well as some preliminary results are discussed.

Kim, J.; Bae, S. W.; Whitten, M. W.; Mullen, J. D.; Quine, R. W.; Kalkur, T. S.

1999-01-01

68

Morphological control in polymer solar cells using low-boiling-point solvent additives  

NASA Astrophysics Data System (ADS)

In the global search for clean, renewable energy sources, organic photovoltaics (OPVs) have recently been given much attention. Popular modern-day OPVs are made from solution-processible, carbon-based polymers (e.g. the model poly(3-hexylthiophene) that are intimately blended with fullerene derivatives (e.g. [6,6]-phenyl-C71-butyric acid methyl ester) to form what is known as the dispersed bulk-heterojunction (BHJ). This BHJ architecture has produced some of the most efficient OPVs to date, with reports closing in on 10% power conversion efficiency. To push efficiencies further into double digits, many groups have identified the BHJ nanomorphology---that is, the phase separations and grain sizes within the polymer: fullerene composite---as a key aspect in need of control and improvement. As a result, many methods, including thermal annealing, slow-drying (solvent) annealing, vapor annealing, and solvent additives, have been developed and studied to promote BHJ self-organization. Processing organic photovoltaic (OPV) blend solutions with high-boiling-point solvent additives has recently been used for morphological control in BHJ OPV cells. Here we show that even low-boiling-point solvents can be effective additives. When P3HT:PCBM OPV cells were processed with a low-boiling-point solvent tetrahydrafuran as an additive in parent solvent o-dichlorobenzene, charge extraction increased leading to fill factors as high as 69.5%, without low work-function cathodes, electrode buffer layers or thermal treatment. This was attributed to PCBM demixing from P3HT domains and better vertical phase separation, as indicated by photoluminescence lifetimes, hole mobilities, and shunt leakage currents. Dependence on solvent parameters and applicability beyond P3HT system was also investigated.

Mahadevapuram, Rakesh C.

69

Phys1101, Spring 2010 Temperature Scales  

E-print Network

points 0 C water freezes 100 C water boils 0 F salt solution freezes 96 F body temperature 0 K lowest, BE Absolute zero Lowest freezing point of salt solution Freezing point of water Room temperature Boiling point

Boyd, Sylke

70

Method of and apparatus for determining deposition-point temperature  

DOEpatents

Acoustic-wave sensor apparatus and method are disclosed 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. 5 figs.

Mansure, A.J.; Spates, J.J.; Martin, S.J.

1998-10-27

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

Non-linear dynamical analyses of transient surface temperature fluctuations during subcooled pool boiling on a horizontal disk  

E-print Network

2009 Keywords: Boiling Thin film thermocouples Correlation dimension Critical heat flux Leidenfrost developed nucleate boil- ing (FDNB) $7­9 near critical heat flux (CHF) condition, and from $6.6 to 7 experiments on a 62.23 mm diameter silicon wafer using PF-5060 as the test liquid. Surface temperature data

Banerjee, Debjyoti

73

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

74

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

75

Superconducting state above the boiling point of liquid nitrogen in the GaH3 compound  

NASA Astrophysics Data System (ADS)

The thermodynamic parameters of the superconducting state in the GaH3 compound under a pressure of 120 GPa have been determined. A wide range of Coulomb pseudopotential values has been taken into account: ???<0.1,0.2>. It has been shown that, for the considered values of ??, the superconducting state is characterized by a critical temperature which is higher than the boiling temperature of liquid nitrogen: TC?(122.99,89.78) K. Other parameters significantly deviate from the predictions of BCS theory. In particular, the ratio of the energy gap to the critical temperature (R? ? 2?(0)/kBTC) changes in the range from 4.15 to 4.03. The ratio of the specific heat jump to the specific heat in the normal state (RC ? ?C(TC)/CN(TC)) takes values from 1.87 to 1.58. The parameter {R}_{{H}}\\equiv {T}_{{C}}{C}^{{N}}({T}_{{C}})/{H}_{{C}}^{2}(0), where HC is the thermodynamic critical field, is characterized in the following manner: RH?<0.147,0.150>. Finally, it has been proven that the maximum value of the electron effective mass ({m}_{{e}}^{\\star }) equals 2.66me, where the symbol me denotes the electron band mass.

Szcz??niak, R.; Durajski, A. P.

2014-01-01

76

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

77

Circumferential temperature distribution during nucleate pool boiling outside smooth and modified horizontal tubes  

SciTech Connect

In the work an approach to avoid a circumferential temperature distribution existing during nucleate pool boiling on a horizontal cylinder within low heat flux densities is presented. The idea of the approach is local heat transfer enhancement by a porous layer application on a part of the heating surface. An experiment on nucleate pool boiling heat transfer from horizontal cylinders to saturated R141b and water under atmospheric pressure is reported. Experiments have been conducted using stainless steel tubes with the outside diameter between 8 mm and 23 mm with the active length of 250 mm. The outside surface of the tubes was smooth or partially coated with a porous metallic layer. In particular, measurements of inside circumferential temperature distribution have been performed. (author)

Dominiczak, Przemyslaw R.; Cieslinski, Janusz T. [Gdansk University of Technology, Faculty of Mechanical Engineering, Narutowicza 11/12, 80-952 Gdansk (Poland)

2008-10-15

78

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

79

The use of the probability distribution function to analyze surface temperature fluctuations in pool boiling  

E-print Network

for the degree of MASTER OF SCIENCE May 1&76 M & jor Sub jc c t: Mc. c h, cnioal L'nqi neerinq THE USE OF THE PROBABILITY DISTRIBUTION FUNCI'ION TO ANALYZE SURFACE TEMPERATURE FLUCTUATIONS IN P OOL BOI LI N G A Thesis by CHAU OUI TU Approved as to style.... The temperature difference obtained by subtracting the bulk fluid temperature from the 1'q 'd t t' t p t * ' t d tl b 1' g, d denoted by 5T b. Boiling with the bulk liquid being equal sub to (or slightly higher than) the liquid saturation tempera- ture...

Tu, Chau Qui

1976-01-01

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

Experimental investigation of micro-scale temperature transients in sub-cooled flow boiling on a horizontal heater  

E-print Network

and liquid subcooling (e.g. at boiling inception and at critical heat flux). These enhancements are primar during the experiments under steady state conditions. The transient temperature data from the FFT array

Banerjee, Debjyoti

82

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

83

Calculations of Freezing Point Depression, Boiling Point Elevation, Vapor Pressure and Enthalpies of Vaporization of Electrolyte Solutions by a Modified Three-Characteristic Parameter Correlation Model  

Microsoft Academic Search

A method was proposed for calculating the thermodynamic properties, freezing point depression, boiling point elevation, vapor\\u000a pressure and enthalpy of vaporization for single solute electrolyte solutions, including aqueous and nonaqueous solutions,\\u000a based on a modified three-characteristic-parameter correlation model. When compared with the corresponding literature values,\\u000a the calculated results show that this method gives a very good approximation, especially for 1-1

Xinlei Ge; Xidong Wang

2009-01-01

84

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

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

Below and above boiling point comparison of microwave irradiation and conductive heating for municipal sludge digestion under identical heating/cooling profiles.  

PubMed

This research provides a comprehensive comparison between microwave (MW) and conductive heating (CH) sludge pretreatments under identical heating/cooling profiles at below and above boiling point temperatures. Previous comparison studies were constrained to an uncontrolled or a single heating rate due to lack of a CH equipment simulating MW under identical thermal profiles. In this research, a novel custom-built pressure-sealed vessel which could simulate MW pretreatment under identical heating/cooling profiles was used for CH pretreatment. No statistically significant difference was proven between MW and CH pretreatments in terms of sludge solubilization, anaerobic biogas yield and organics biodegradation rate (p-value>0.05), while statistically significant effects of temperature and heating rate were observed (p-value<0.05). These results explain the contradictory results of previous studies in which only the final temperature (not heating/cooling rates) was controlled. PMID:25863200

Hosseini Koupaie, E; Eskicioglu, C

2015-07-01

87

Temperature measurements in sliding elastohydrodynamic point contacts  

NASA Technical Reports Server (NTRS)

Techniques using the infrared radiation emitted by a sliding elastohydrodynamic (EHD) point contact to measure oil film and surface temperature are discussed. Temperature distributions in the EHD contact are presented for a naphthenic mineral oil at 1.04 GN/sq m (150,000 psi) Hertz pressure and several sliding velocities. Film temperatures as high as 360 C are reported at locations near the points of minimum film thickness in the contact side lobes.

Turchina, V.; Sanborn, D. M.; Winer, W. O.

1973-01-01

88

A Determination of the Thermodynamic Temperature of the Triple Point of Neon  

NASA Astrophysics Data System (ADS)

A constant-volume gas thermometer has been used to measure the thermodynamic temperature, and also the second virial coefficient of helium 4, at the triple point of neon (24.5 K). This was carried out by measuring a relative isotherm at 24.5 K referenced to the temperature of the boiling point of hydrogen on the NPL75 temperature scale. The thermodynamic temperature values measured for the triple points of natural neon and neon 20 were (24.5570 +/- 0.0011) K and (24.5394 +/- 0.0011) K respectively. The result for natural neon agrees well with the corresponding temperature value of (24.5565 +/- 0.0011) K inferred from NPL75 and may be related to other laboratory realizations of the neon triple point through the recent international intercomparison of sealed triple-point cells.

Kemp, R. C.; Sakurai, H.

1986-01-01

89

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 T(b)/T, where T(b) 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, T(b)/T(m). When a liquid's T(b)/T(m) happens to be high, the liquid can readily be supercooled below its T(m) because the liquid's microscopic relaxation dynamics is already impeded at T(m), 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 T(b)) melting temperature, T(m), 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, T(b)/T(m). PMID:23869489

Mamontov, Eugene

2013-08-15

90

An efficient reliable method to estimate the vaporization enthalpy of pure substances according to the normal boiling temperature and critical properties  

PubMed Central

The heat of vaporization of a pure substance at its normal boiling temperature is a very important property in many chemical processes. In this work, a new empirical method was developed to predict vaporization enthalpy of pure substances. This equation is a function of normal boiling temperature, critical temperature, and critical pressure. The presented model is simple to use and provides an improvement over the existing equations for 452 pure substances in wide boiling range. The results showed that the proposed correlation is more accurate than the literature methods for pure substances in a wide boiling range (20.3–722 K). PMID:25685493

Mehmandoust, Babak; Sanjari, Ehsan; Vatani, Mostafa

2013-01-01

91

Sediment microbial communities in Great Boiling Spring are controlled by temperature and distinct from water communities  

PubMed Central

Great Boiling Spring is a large, circumneutral, geothermal spring in the US Great Basin. Twelve samples were collected from water and four different sediment sites on four different dates. Microbial community composition and diversity were assessed by PCR amplification of a portion of the small subunit rRNA gene using a universal primer set followed by pyrosequencing of the V8 region. Analysis of 164?178 quality-filtered pyrotags clearly distinguished sediment and water microbial communities. Water communities were extremely uneven and dominated by the bacterium Thermocrinis. Sediment microbial communities grouped according to temperature and sampling location, with a strong, negative, linear relationship between temperature and richness at all taxonomic levels. Two sediment locations, Site A (87–80?°C) and Site B (79?°C), were predominantly composed of single phylotypes of the bacterial lineage GAL35 (p?=36.1%), Aeropyrum (p?=16.6%), the archaeal lineage pSL4 (p?=15.9%), the archaeal lineage NAG1 (p?=10.6%) and Thermocrinis (p?=7.6%). The ammonia-oxidizing archaeon ‘Candidatus Nitrosocaldus' was relatively abundant in all sediment samples <82?°C (p?=9.51%), delineating the upper temperature limit for chemolithotrophic ammonia oxidation in this spring. This study underscores the distinctness of water and sediment communities in GBS and the importance of temperature in driving microbial diversity, composition and, ultimately, the functioning of biogeochemical cycles. PMID:23235293

Cole, Jessica K; Peacock, Joseph P; Dodsworth, Jeremy A; Williams, Amanda J; Thompson, Daniel B; Dong, Hailiang; Wu, Geng; Hedlund, Brian P

2013-01-01

92

Sediment microbial communities in Great Boiling Spring are controlled by temperature and distinct from water communities.  

PubMed

Great Boiling Spring is a large, circumneutral, geothermal spring in the US Great Basin. Twelve samples were collected from water and four different sediment sites on four different dates. Microbial community composition and diversity were assessed by PCR amplification of a portion of the small subunit rRNA gene using a universal primer set followed by pyrosequencing of the V8 region. Analysis of 164 178 quality-filtered pyrotags clearly distinguished sediment and water microbial communities. Water communities were extremely uneven and dominated by the bacterium Thermocrinis. Sediment microbial communities grouped according to temperature and sampling location, with a strong, negative, linear relationship between temperature and richness at all taxonomic levels. Two sediment locations, Site A (87-80 °C) and Site B (79 °C), were predominantly composed of single phylotypes of the bacterial lineage GAL35 (\\[pmacr]=36.1%), Aeropyrum (\\[pmacr]=16.6%), the archaeal lineage pSL4 (\\[pmacr]=15.9%), the archaeal lineage NAG1 (\\[pmacr]=10.6%) and Thermocrinis (\\[pmacr]=7.6%). The ammonia-oxidizing archaeon 'Candidatus Nitrosocaldus' was relatively abundant in all sediment samples <82 °C (\\[pmacr]=9.51%), delineating the upper temperature limit for chemolithotrophic ammonia oxidation in this spring. This study underscores the distinctness of water and sediment communities in GBS and the importance of temperature in driving microbial diversity, composition and, ultimately, the functioning of biogeochemical cycles. PMID:23235293

Cole, Jessica K; Peacock, Joseph P; Dodsworth, Jeremy A; Williams, Amanda J; Thompson, Daniel B; Dong, Hailiang; Wu, Geng; Hedlund, Brian P

2013-04-01

93

Time and Space Resolved Wall Temperature Measurements during Nucleate Boiling with Constant Heat Flux Boundary Conditions  

NASA Technical Reports Server (NTRS)

The lack of temporally and spatially resolved measurements under nucleate bubbles has complicated efforts to fully explain pool-boiling phenomena. The objective of this current work is to acquire time and space resolved temperature distributions under nucleate bubbles on a constant heat flux surface. This was performed using a microheater array with 100 micron resolution that allowed effectively simultaneous measurements of surface temperature while supplying a constant dissipative heat flux. This data is then correlated with high speed (> 1000Hz) visual recordings of the bubble growth and departure from the heater surface acquired from below and from the side of the heater. The data indicate that a significant source of energy during bubble nucleation and initial growth is the superheated layer around the bubble. Bubble coalescence was not observed to decrease surface temperature as significantly as bubble departure from the surface. Since bubble departure is typically followed by a sharp increase in the heater surface temperature, it is surmised that the departing bubble effectively removes the superheated layer, allowing a high local heat transfer rate with the bulk fluid through transient conduction/micro-convection during rewetting.

Myers, Jerry G.; Hussey, Sam W.; Yee, Glenda F.; Yerramilli, Vamsee K.; Kim, Jungho

2005-01-01

94

Determination of the Latent Heats and Triple Point of Perfluorocyclobutane  

ERIC Educational Resources Information Center

Proposes the use of Perfluorocyclobutane in physical chemistry courses to conduct experiments on latent heat, triple point temperatures and pressures, boiling points, and entropy of vaporization. (SL)

Briggs, A. G.; Strachan, A. N.

1977-01-01

95

Measurement of thermodynamic temperature of high temperature fixed points  

SciTech Connect

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. [All-Russian Research Institute for Optical and Physical Measurements (VNIIOFI), 46 Ozernaya St., Moscow 119361 (Russian Federation)] [All-Russian Research Institute for Optical and Physical Measurements (VNIIOFI), 46 Ozernaya St., Moscow 119361 (Russian Federation)

2013-09-11

96

Low Temperature Regenerators for Zero Boil-Off Liquid Hydrogen Pulse Tube Cryocoolers  

NASA Technical Reports Server (NTRS)

Recently, a great deal of attention has been focused on zero boil-off (ZBO) propellant storage as a means of minimizing the launch mass required for long-term exploration missions. A key component of ZBO systems is the cooler. Pulse tube coolers offer the advantage of zero moving mass at the cold head, and recent advances in lightweight, high efficiency cooler technology have paved the way for reliable liquid oxygen (LOx) temperature coolers to be developed which are suitable for flight ZBO systems. Liquid hydrogen (LH2) systems, however, are another matter. For ZBO liquid hydrogen systems, cooling powers of 1-5 watts are required at 20 K. The final development from tier for these coolers is to achieve high efficiency and reliability at lower operating temperatures. Most of the life-limiting issues of flight Stirling and pulse tube coolers are associated with contamination, drive mechanisms, and drive electronics. These problems are well in hand in the present generation coolers. The remaining efficiency and reliability issues reside with the low temperature regenerators. This paper will discuss advances to be made in regenerators for pulse tube LH2 ZBO coolers, present some historical background, and discuss recent progress in regenerator technology development using alloys of erbium.

Salerno, Louis J.; Kashani, Ali; Helvensteijn, Ben; Kittel, Peter; Arnoldm James O. (Technical Monitor)

2002-01-01

97

Remote temperature-set-point controller  

DOEpatents

An instrument is described for carrying out mechanical strain tests on metallic samples with the addition of means for varying the temperature with strain. The instrument includes 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 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, W.F.; Winiecki, A.L.

1984-10-17

98

Spatial and temporal variation of the surface temperature and heat flux for saturated pool nucleate boiling at lower heat fluxes  

SciTech Connect

The spatial and temporal variations of local surface temperature and heat flux for saturated pool nucleate boiling are investigated parametrically using a numerical model. The numerical model consisted of solving the three-dimensional transient heat conduction equation within the heater subjected to nucleate boiling over its upper surface. The surface topography model to distribute the cavities over the boiling surface used a Monte Carlo scheme. All cavities were assumed to be conical in shape. The cavity radii are obtained using an exponential probability density function with a known mean value. Local surface temperatures showed significant spatial and temporal variations, depending upon the surface topography and the heater material and thickness. However, the surface-averaged temperature showed practically no temporal variation. The temporal variations in local temperatures caused the surface-averaged heat flux to vary significantly. The temporal variations in the surface-averaged heat flux were similar for smooth and rough and thick and thin copper and nickel plates. Results indicated that the use of a classical energy balance equation to evaluate the surface heat flux must consider the spatial variation of the temperature. Results also showed that any thermocouple embedded beneath the surface of the heater does not follow the temporal variations at the surface.

Unal, C.; Pasamehmetoglu, K.O.

1993-10-01

99

Identification of Polybrominated Diphenyl Ether Metabolites Based on Calculated Boiling Points from COSMO-RS, Experimental Retention Times, and Mass Spectral Fragmentation Patterns.  

PubMed

The COnductor-like Screening MOdel for Realistic Solvents (COSMO-RS) was used to predict the boiling points of several polybrominated diphenyl ethers (PBDEs) and methylated derivatives (MeO-BDEs) of monohydroxylated BDE (OH-BDE) metabolites. The linear correlation obtained by plotting theoretical boiling points calculated by COSMO-RS against experimentally determined retention times from gas chromatography-mass spectrometry facilitated the identification of PBDEs and OH-BDEs. This paper demonstrates the applicability of COSMO-RS in identifying unknown PBDE metabolites of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) and 2,2',4,4',6-pentabromodiphenyl ether (BDE-100). Metabolites of BDE-47 and BDE-100 were formed through individual incubations of each PBDE with recombinant cytochrome P450 2B6. Using calculated boiling points and characteristic mass spectral fragmentation patterns of the MeO-BDE positional isomers, the identities of the unknown monohydroxylated metabolites were proposed to be 2'-hydroxy-2,3',4,4'-tetrabromodiphenyl ether (2'-OH-BDE-66) from BDE-47, and 2'-hydroxy-2,3',4,4',6-pentabromodiphenyl ether (2'-OH-BDE-119) and 4-hydroxy-2,2',3,4',6-pentabromodiphenyl ether (4-OH-BDE-91) from BDE-100. The collective use of boiling points predicted with COSMO-RS, and characteristic mass spectral fragmentation patterns provided a valuable tool toward the identification of isobaric compounds. PMID:25565148

Simpson, Scott; Gross, Michael S; Olson, James R; Zurek, Eva; Aga, Diana S

2015-02-17

100

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

101

Perfluorooctanoic acid Melting point ~55 C, boiling point ~190 C, pKa ~ 2.5, sparingly  

E-print Network

(PTFE and PVDF) · Main source of leakage to the environment - fluorotelomers used in food packaging · Du in water and polar organic solvents · Stable at normal temperatures and pressures but avoid contact coat, gloves and proper ventilation · It does not biodegrade in the environment · Is found at very low

Cohen, Robert E.

102

High flux film and transition boiling  

SciTech Connect

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 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

103

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

104

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

105

Determination of boiling point of petrochemicals by gas chromatography-mass spectrometry and multivariate regression analysis of structural activity relationship.  

PubMed

Accurate understanding of analyte boiling points (BP) is of critical importance in gas chromatographic (GC) separation and crude oil refinery operation in petrochemical industries. This study reported the first combined use of GC separation and partial-least-square (PLS1) multivariate regression analysis of petrochemical structural activity relationship (SAR) for accurate BP determination of two commercially available (D3710 and MA VHP) calibration gas mix samples. The results of the BP determination using PLS1 multivariate regression were further compared with the results of traditional simulated distillation method of BP determination. The developed PLS1 regression was able to correctly predict analytes BP in D3710 and MA VHP calibration gas mix samples, with a root-mean-square-%-relative-error (RMS%RE) of 6.4%, and 10.8% respectively. In contrast, the overall RMS%RE of 32.9% and 40.4%, respectively obtained for BP determination in D3710 and MA VHP using a traditional simulated distillation method were approximately four times larger than the corresponding RMS%RE of BP prediction using MRA, demonstrating the better predictive ability of MRA. The reported method is rapid, robust, and promising, and can be potentially used routinely for fast analysis, pattern recognition, and analyte BP determination in petrochemical industries. PMID:24881546

Fakayode, Sayo O; Mitchell, Breanna S; Pollard, David A

2014-08-01

106

Application of high-speed digital holographic interferometry for the analysis of temperature distributions and velocity fields in subcooled flow boiling  

NASA Astrophysics Data System (ADS)

Holographic interferometry can be used to visualize density fields in fluids, and thus give insight into temperature distributions in flows. A fully digital reconstruction technique for holographic interferograms is presented that allows to create high-speed interferometric recordings and gives time-resolved information about heat transfer processes. The technique can also be used for a sequential (image to image) analysis of the recordings, which offers higher sensitivity and fewer errors due to optical impurities. Experiments are conducted with a vertical flow boiling channel with one heated wall, using a low boiling fluorocarbon as working liquid in regimes of steady-state nucleate boiling at critical heat flux (CHF), steady-state film boiling and CHF transient. Recording frequencies are up to 7,000 fps. The technique is used to analyze boiling processes at different fluid subcoolings with and without added turbulence. The results give enhanced insight into the temperature distributions, effects of different flow inserts and mechanisms of heat transfer in flow boiling at high heat fluxes. Furthermore, a velocimetric application of the technique is presented using cross-correlation for tracing of density gradients both in boiling and unheated flows. This application gives insight to the velocity distributions in the liquid surrounding the vapor layer. The results show good comparison to particle image velocimetry measurements for the same setup.

Bloch, Gregor; Kuczaty, Julian; Sattelmayer, Thomas

2014-02-01

107

Highly efficient secondary dewatering of dewatered sewage sludge using low boiling point solvents.  

PubMed

Secondary dewatering of dewatered sludge is imperative to make conventional drying and incineration of sludge more economically feasible. In this study, a secondary dewatering of dewatered sludge with selected solvents (i.e. acetone and ethanol) followed by vacuum filtration and nature drying was investigated to achieve in-depth dewatering. After the entire secondary dewatering process, the sludge was shown to be odourless and the organic matter content was greatly retained. Increased mean particle size of sludge after solvent contact improved solid-liquid separation. With an acetone/sludge ratio of 3:1 (mL:g) in solvent contact and subsequent nature drying at ambient temperature after 24 h, the moisture content of sludge can be reduced to a level less than 20%. It is found that the polysaccharides were mainly precipitated by acetone, whereas the release ratios of protein and DNA were increased significantly as the added acetone volumes were elevated. During nature drying, accumulated evaporation rates of the sludge after solvent contact were 5-6 times higher than original dewatered sludge. Furthermore, sludge after acetone contact had better nature drying performance than ethanol. The two-stage dewatering involves solvent contact dewatering and solvent enhanced evaporation dewatering. Through selecting an appropriate solvent/sludge ratio as well as economical solvents and minimizing the solvent loss in a closed-pilot system, this dewatering process can be competitive in industrial applications. Therefore, this solvent-aided secondary dewatering is an energy-saving technology for effective in-depth dewatering of dewatered sludge and subsequent sludge utilization. PMID:24600846

He, Chao; Chena, Chia-Lung; Xu, Zhirong; Wang, Jing-Yuan

2014-01-01

108

Application of adjustment calculus in the nodeless Trefftz method for a problem of two-dimensional temperature field of the boiling liquid flowing in a minichannel  

NASA Astrophysics Data System (ADS)

The paper presents application of the nodeless Trefftz method to calculate temperature of the heating foil and the insulating glass pane during continuous flow of a refrigerant along a vertical minichannel. Numerical computations refer to an experiment in which the refrigerant (FC-72) enters under controlled pressure and temperature a rectangular minichannel. Initially its temperature is below the boiling point. During the flow it is heated by a heating foil. The thermosensitive liquid crystals allow to obtain twodimensional temperature field in the foil. Since the nodeless Trefftz method has very good performance for providing solutions to such problems, it was chosen as a numerical method to approximate two-dimensional temperature distribution in the protecting glass and the heating foil. Due to known temperature of the refrigerant it was also possible to evaluate the heat transfer coefficient at the foil-refrigerant interface. For expected improvement of the numerical results the nodeless Trefftz method was combined with adjustment calculus. Adjustment calculus allowed to smooth the measurements and to decrease the measurement errors. As in the case of the measurement errors, the error of the heat transfer coefficient decreased.

Ho?ejowska, Sylwia; Maciejewska, Beata; Ho?ejowski, Leszek

2014-03-01

109

High temperature gas chromatography-time-of-flight-mass spectrometry (HTGC-ToF-MS) for high-boiling compounds.  

PubMed

High temperature gas chromatography (HTGC) is a routine technique for the analysis of high boiling compounds which are eluted from the column with oven cycling up to > 400 °C. In contrast, the coupling of HTGC with mass spectrometry (HTGC-MS) has received relatively little attention. This may be due to the availability of GC columns, mass spectrometers and accessories that are able to withstand constant high temperature cycling. We have assembled a HTGC-time of flight-MS (HTGC-ToF-MS) system from readily available products that is capable of rapid (<25 min) analysis of ?C?????? hydrocarbon boiling equivalents and full mass spectral data recording up to m/z 1850. Here we report initial results from the analysis of diverse substrates including:long-chain (> C??) n-alkanes, n-acid methyl esters up to C??, triacylglycerides (TAGs) with molecular and fragment ions in a single analysis, intact wax esters from C?????, C?? glycerol alkyl glycerol tetraethers (GDGTs), and C????? metallated porphyrins. Mass spectrometry at 430 °C was achievable on a routine basis without significant thermal degradation of analytes. The method is applicable to analysis of a wide range of industrial, environmental, biological, geochemical and other samples where high molecular weight analytes are of interest. PMID:22579362

Sutton, P A; Rowland, S J

2012-06-22

110

Pyrosequencing Reveals High-Temperature Cellulolytic Microbial Consortia in Great Boiling Spring after In Situ Lignocellulose Enrichment  

PubMed Central

To characterize high-temperature cellulolytic microbial communities, two lignocellulosic substrates, ammonia fiber-explosion-treated corn stover and aspen shavings, were incubated at average temperatures of 77 and 85°C in the sediment and water column of Great Boiling Spring, Nevada. Comparison of 109,941 quality-filtered 16S rRNA gene pyrosequences (pyrotags) from eight enrichments to 37,057 quality-filtered pyrotags from corresponding natural samples revealed distinct enriched communities dominated by phylotypes related to cellulolytic and hemicellulolytic Thermotoga and Dictyoglomus, cellulolytic and sugar-fermenting Desulfurococcales, and sugar-fermenting and hydrogenotrophic Archaeoglobales. Minor enriched populations included close relatives of hydrogenotrophic Thermodesulfobacteria, the candidate bacterial phylum OP9, and candidate archaeal groups C2 and DHVE3. Enrichment temperature was the major factor influencing community composition, with a negative correlation between temperature and richness, followed by lignocellulosic substrate composition. This study establishes the importance of these groups in the natural degradation of lignocellulose at high temperatures and suggests that a substantial portion of the diversity of thermophiles contributing to consortial cellulolysis may be contained within lineages that have representatives in pure culture. PMID:23555835

Peacock, Joseph P.; Cole, Jessica K.; Murugapiran, Senthil K.; Dodsworth, Jeremy A.; Fisher, Jenny C.; Moser, Duane P.; Hedlund, Brian P.

2013-01-01

111

Optimizations of packed sorbent and inlet temperature for large volume-direct aqueous injection-gas chromatography to determine high boiling volatile organic compounds in water.  

PubMed

For the expanded application area, fast trace analysis of certain high boiling point (i.e., 150-250 °C) volatile organic compounds (HVOCs) in water, a large volume-direct aqueous injection-gas chromatography (LV-DAI-GC) method was optimized for the following parameters: packed sorbent for sample on-line pretreatment, inlet temperature and detectors configuration. Using the composite packed sorbent self-prepared with lithium chloride and a type of diatomite, the method enabled safe injection of an approximately 50-100 ?L sample at an inlet temperature of 150 °C in the splitless mode and separated HVOCs from water matrix in 2 min. Coupled with a flame ionization detector (FID), an electron capture detector (ECD) and a flame photometric detector (FPD), the method could simultaneously quantify 27 HVOCs that belong to seven subclasses (i.e., halogenated aliphatic hydrocarbons, chlorobenzenes, nitrobenzenes, anilines, phenols, polycyclic aromatic hydrocarbons and organic sulfides) in 26 min. Injecting a 50 ?L sample without any enrichment step, such as cryotrap focusing, the limits of quantification (LOQs) for the 27 HVOCs was 0.01-3 ?g/L. Replicate analyses of the 27 HVOCs spiked source and river water samples exhibited good precision (relative standard deviations ? 11.3%) and accuracy (relative errors ? 17.6%). The optimized LV-DAI-GC was robust and applicable for fast determination and automated continuous monitoring of HVOCs in surface water. PMID:24997514

Yu, Bofan; Song, Yonghui; Han, Lu; Yu, Huibin; Liu, Yang; Liu, Hongliang

2014-08-22

112

BOILING-WATER-REACTOR INSTABILITY  

Microsoft Academic Search

BS>The observed oscillatory behavior of five ANL boiling reactors---the ; Borax I, II, III, IV, and the Experimental Boiling Water Reactor---are described. ; The amplitude, frequency, temperature, and threshold of the oscillation are ; recorded. The kinetic theory of oscillations is illustrated by a simplified ; model using a single series feedback loop and linearized one group kinetic ; equations.

Thie

1958-01-01

113

Triple-Point Temperatures of 20Ne and 22Ne  

NASA Astrophysics Data System (ADS)

Interest in the triple points of neon isotopes has recently arisen as a result of the multi-institute project to understand how variations in the isotopic composition of natural neon influence the triple-point temperature of a particular sample. Given the challenges in determining with sufficiently low uncertainty both the relative isotopic concentrations, particularly of 22Ne relative to 20Ne, and the temperature differences among cells filled from different gas sources in order to determine the sensitivity coefficient with adequate confidence, modeling of the isotopic influence becomes an attractive alternative for correcting the triple points of "natural" neon samples to a common composition. The modeling requires, among other things, knowledge of the triple-point temperatures of 20Ne and 22Ne. The triple points of these pure neon isotopes have utility in their own right as secondary reference temperatures on the ITS-90, and one or both of these could replace "natural" neon in a revised International Temperature Scale or approximation to the ITS. The neon isotope triple-point temperatures (on the IPTS-68) reported by Furukawa, Kemp, and Sakurai in various publications from 1972 to 1986 predate the ITS-90, and so there is utility in contemporary measurements (on the ITS-90) with gas samples of recent production. At NRC, we find the triple point of 20Ne to be at 24.54230 K (13.80 mK below the triple point of "natural" neon) and that of 22Ne to be at 24.68889 K (132.79 mK above the triple point of "natural" neon), assuming the reference sample of "natural" neon realizes the ideal ITS-90 temperature of 24.5561 K.

Hill, K. D.; Fahr, M.

2011-01-01

114

Thermodynamic Temperatures of High-Temperature Fixed Points: Uncertainties Due to Temperature Drop and Emissivity  

NASA Astrophysics Data System (ADS)

This study forms part of the European Metrology Research Programme project implementing the New Kelvin to assign thermodynamic temperatures to a selected set of high-temperature fixed points (HTFPs), Cu, Co-C, Pt-C, and Re-C. A realistic thermal model of these HTFPs, developed in finite volume software ANSYS FLUENT, was constructed to quantify the uncertainty associated with the temperature drop across the back wall of the cell. In addition, the widely applied software package, STEEP3 was used to investigate the influence of cell emissivity. The temperature drop, , relates to the temperature difference due to the net loss of heat from the aperture of the cavity between the back wall of the cavity, viewed by the thermometer, defining the radiance temperature, and the solid-liquid interface of the alloy, defining the transition temperature of the HTFP. The actual value of can be used either as a correction (with associated uncertainty) to thermodynamic temperature evaluations of HTFPs, or as an uncertainty contribution to the overall estimated uncertainty. In addition, the effect of a range of furnace temperature profiles on the temperature drop was calculated and found to be negligible for Cu, Co-C, and Pt-C and small only for Re-C. The effective isothermal emissivity is calculated over the wavelength range from 450 nm to 850 nm for different assumed values of surface emissivity. Even when furnace temperature profiles are taken into account, the estimated emissivities change only slightly from the effective isothermal emissivity of the bare cell. These emissivity calculations are used to estimate the uncertainty in the temperature assignment due to the uncertainty in the emissivity of the blackbody.

Castro, P.; Machin, G.; Bloembergen, P.; Lowe, D.; Whittam, A.

2014-07-01

115

Subcooled forced convection boiling of trichlorotrifluoroethane  

NASA Technical Reports Server (NTRS)

Experimental heat-transfer data were obtained for the forced-convection boiling of trichlorotrifluoroethane (R-113 or Freon-113) in a vertical annular test annular test section. The 97 data points obtained covered heat transfer by forced convection, local boiling, and fully-developed boiling. Correlating methods were obtained which accurately predicted the heat flux as a function of wall superheat (boiling curve) over the range of parameters studied.

Dougall, R. S.; Panian, D. J.

1972-01-01

116

Thermal inactivation of water-borne pathogenic and indicator bacteria at sub-boiling temperatures.  

PubMed

The use of harvested rainwater in domestic hot water systems can result in optimised environmental and economic benefits to urban water cycle management, however, the water quality and health risks of such a scenario have not been adequately investigated. Thermal inactivation analyses were carried out on eight species of non-spore-forming bacteria in a water medium at temperatures relevant to domestic hot water systems (55-65 degrees C), and susceptibilities to heat stress were compared using D-values. The D-value was defined as the time required to reduce a bacterial population by 90% or 1 log reduction. The results found that both tested strains of Enterococcus faecalis were the most heat resistant of the bacteria studied, followed by the pathogens Shigella sonnei biotype A and Escherichia coli O157:H7, and the non-pathogenic E. coli O3:H6. Pseudomonas aeruginosa was found to be less resistant to heat, while Salmonella typhimurium, Serratia marcescens, Klebsiella pneumoniae and Aeromonas hydrophila displayed minimal heat resistance capacities. At 65 degrees C, little thermal resistance was demonstrated by any species, with log reductions in concentration occurring within seconds. The results of this study suggested that the temperature range from 55 to 65 degrees C was critical for effective elimination of enteric/pathogenic bacterial components and supported the thesis that hot water systems should operate at a minimum of 60 degrees C. PMID:16524613

Spinks, Anthony T; Dunstan, R H; Harrison, T; Coombes, P; Kuczera, G

2006-03-01

117

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

118

F-LE Boiling Water  

NSDL National Science Digital Library

This is a task from the Illustrative Mathematics website that is one part of a complete illustration of the standard to which it is aligned. Each task has at least one solution and some commentary that addresses important asects of the task and its potential use. Here are the first few lines of the commentary for this task: Below is a table showing the approximate boiling point of water at different elevations: Elevation (meters above sea level)Boiling Point (degrees Celsi...

2013-10-30

119

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

120

Boiling Temperature and Reversed Deliquescence Relative Humidity Measurements for Mineral Assemblages in the NaCl + NaNO 3 + KNO 3 + Ca(NO 3 ) 2 + H 2 O System  

Microsoft Academic Search

Boiling temperature measurements have been made at ambient pressure for saturated ternary solutions of NaCl + KNO3 + H2O, NaNO3 + KNO3 + H2O, and NaCl + Ca(NO3)2 + H2O over the full composition range, along with those of the single salt systems. Boiling temperatures were also measured for the four component NaCl + NaNO3 + KNO3 + H2O and

Joseph A. Rard; Kirk J. Staggs; S. Dan Day; Susan A. Carroll

2006-01-01

121

Liquid metal boiling inception  

NASA Technical Reports Server (NTRS)

An experimental study of the inception of boiling in potassium in forced convection is reported. The boiler consisted of a 0.19-inch inside diameter, niobium-1% zirconium boiler tube approximately six feet long. Heating was accomplished by direct electrical tube wall conduction. Experiments were performed with both all-liquid fill and two-phase fill startup sequences and with a range of flow rates, saturation temperatures, inert gas levels, and fill liquid temperatures. Superheat of the liquid above the equilibrium saturation temperature was observed in all the experiments. Incipient boiling liquid superheat ranged from a few degrees to several hundred. Comparisons of these data with other data and with several analytical treatments are presented.

Sabin, C. M.; Poppendiek, H. F.; Mouritzen, G.; Meckel, P. T.; Cloakey, J. E.

1972-01-01

122

Alternative Methods of Blackbody Thermodynamic Temperature Measurement Above Silver Point  

NASA Astrophysics Data System (ADS)

Presently, absolute radiometry is the main method of thermodynamic temperature determination above the silver point. The importance of such measurements has increased, as a large international project is underway aimed at assigning thermodynamic temperatures to high-temperature fixed points (HTFPs). All participants are using filter radiometers calibrated against an absolute cryogenic radiometer which, therefore, will be the basis of the provided thermodynamic temperatures of the fixed points. However, such a unified approach may lead to systematic errors (if any) common to all participants. There are methods, providing an alternative to absolute radiometry, which allow the determination of blackbody thermodynamic temperatures using relative measurements. Alternative methods, even if they have lower accuracy than absolute radiometry, could disclose some possible unrecognized systematic errors, or, on the contrary, could confirm the results obtained using absolute radiometry and increase confidence of the thermodynamic temperature determination. One such method, known as the method of ratios (i.e., double wavelength technique), is based on measuring the ratios of fluxes emitted by a blackbody in separate spectral ranges at two temperatures. This approach has been developed at VNIIOFI, but its realization met serious technical difficulties. Modern sensors with improved sensitivity and stability, extremely reproducible HTFP blackbodies, and significant progress in computational methods and computer performance provide a new chance to realize this approach with sufficient accuracy. Another method is based on comparing the ratio of fluxes measured at two wavelengths for a high-temperature blackbody with that measured for synchrotron radiation. This article overviews possibilities of the alternative methods for determination of blackbody thermodynamic temperatures by means of relative radiometry to attract attention of the thermometry and radiometry communities to the importance of international cooperation for realization of these methods.

Prokhorov, A.; Sapritsky, V.; Khlevnoy, B.; Gavrilov, V.

2015-03-01

123

Confinement by Carbon Nanotubes Drastically Alters the Boiling and Critical Behavior of Water Droplets  

E-print Network

Vapor pressure grows rapidly above the boiling temperature, and past the critical point liquid droplets disintegrate. Our atomistic simulations show that this sequence of events is reversed inside carbon nanotubes (CNT). Droplets disintegrate first and at low temperature, while pressure remains small. The droplet disintegration temperature is independent of the CNT diameter. In contrast, depending on CNT diameter, a temperature that is much higher than the bulk boiling temperature is required to raise the internal pressure. The control over pressure by CNT size can be useful for therapeutic drug delivery.

Chaban, Vitaly V; Prezhdo, Oleg V

2012-01-01

124

Complex saddle points in QCD at finite temperature and density  

NASA Astrophysics Data System (ADS)

The sign problem in QCD at finite temperature and density leads naturally to the consideration of complex saddle points of the action or effective action. The global symmetry CK of the finite-density action, where C is charge conjugation and K is complex conjugation, constrains the eigenvalues of the Polyakov loop operator P at a saddle point in such a way that the action is real at a saddle point, and net color charge is zero. The values of TrFP and TrFP† at the saddle point are real but not identical, indicating the different free energy cost associated with inserting a heavy quark versus an antiquark into the system. At such complex saddle points, the mass matrix associated with Polyakov loops may have complex eigenvalues, reflecting oscillatory behavior in color-charge densities. We illustrate these properties with a simple model which includes the one-loop contribution of gluons and two flavors of massless quarks moving in a constant Polyakov loop background. Confinement-deconfinement effects are modeled phenomenologically via an added potential term depending on the Polyakov loop eigenvalues. For sufficiently large temperature T and quark chemical potential ?, the results obtained reduce to those of perturbation theory at the complex saddle point. These results may be experimentally relevant for the compressed baryonic matter experiment at FAIR.

Nishimura, Hiromichi; Ogilvie, Michael C.; Pangeni, Kamal

2014-08-01

125

Proposed Process for Estimating Definitive Temperatures of High-Temperature Fixed Points  

NASA Astrophysics Data System (ADS)

Filter radiometric measurements of high-temperature fixed points will provide a means of realizing and disseminating the thermodynamic temperature for temperatures above the silver point, with uncertainties that are competitive with the defined ITS-90. This paper presents the analysis method proposed for determining the thermodynamic temperature of the melting transitions of Re-C, Pt-C, and Co-C eutectic fixed points by combining filter radiometer measurements by nine laboratories to obtain a single temperature for each fixed point. It discusses the key sources of error, the corrections applied for known systematic effects, and the uncertainties. These sources of error introduce correlation between the measured values; the paper describes how data can be combined in a way that accounts for that correlation.

Woolliams, E. R.; Bloembergen, P.; Machin, G.

2015-03-01

126

Microheater Array Boiling Experiment  

NASA Technical Reports Server (NTRS)

By conducting pool boiling tests in microgravity, the effect of buoyancy on the overall boiling process and the relative magnitude of other phenomena can be assessed. Data from KC-135 and sounding rocket experiments indicate little effect of gravity on boiling heat transfer at wall superheats below 25 C, despite vast differences in bubble behavior between gravity levels. In microgravity, a large primary bubble, surrounded by smaller satellite bubbles, moved over the surface, occasionally causing nucleation. Once formed, the primary bubble size remained constant for a given superheat, indicating evaporation at the bubble base is balanced with condensation on the bubble cap. The primary bubble's size increased with wall superheat. Most heaters under the primary bubble had low heat transfer rates, suggesting liquid dryout. Strong Marangoni convection developed in microgravity, forming a 'jet' into the bulk liquid that forced the bubble onto the heater. An experiment is being designed for the. Microgravity Science Glovebox. This experiment uses two 96 element microheater arrays, 2.7 and 7.0 mm in size. These heaters are individually controlled to operate at a constant temperature, measuring local heat fluxes as a function of time and space. Most boiling experiments operate at constant wall heat flux with larger heaters, allowing only time and space-averaged measurements. Each heater is about the bubble departure size in normal gravity, but significantly smaller than the bubble departure size in reduced gravity.

Kim, Jungho; McQuillen, John; Balombin, Joe

2002-01-01

127

Contrast-enhanced ultrasound imaging and in vivo circulatory kinetics with low-boiling-point nanoscale phase-change perfluorocarbon agents.  

PubMed

Many studies have explored phase-change contrast agents (PCCAs) that can be vaporized by an ultrasonic pulse to form microbubbles for ultrasound imaging and therapy. However, few investigations have been published on the utility and characteristics of PCCAs as contrast agents in vivo. In this study, we examine the properties of low-boiling-point nanoscale PCCAs evaluated in vivo and compare data with those for conventional microbubbles with respect to contrast generation and circulation properties. To do this, we develop a custom pulse sequence to vaporize and image PCCAs using the Verasonics research platform and a clinical array transducer. Results indicate that droplets can produce contrast enhancement similar to that of microbubbles (7.29 to 18.24 dB over baseline, depending on formulation) and can be designed to circulate for as much as 3.3 times longer than microbubbles. This study also reports for the first time the ability to capture contrast washout kinetics of the target organ as a measure of vascular perfusion. PMID:25619781

Sheeran, Paul S; Rojas, Juan D; Puett, Connor; Hjelmquist, Jordan; Arena, Christopher B; Dayton, Paul A

2015-03-01

128

Transient boiling heat transfer in saturated liquid nitrogen and F113 at standard and zero gravity  

NASA Technical Reports Server (NTRS)

Transient and steady state nucleate boiling in saturated LN2 and F113 at standard and near zero gravity conditions were investigated for the horizontal up, vertical and horizontal down orientations of the heating surface. Two distinct regimes of heat transfer mechanisms were observed during the interval from the step increase of power input to the onset of nucleate boiling: the conduction and convection dominated regimes. The time duration in each regime was considerably shorter with LN2 than with F113, and decreased as heat flux increased, as gravity was reduced, and as the orientation was changed from horizontal up to horizontal down. In transient boiling, boiling initiates at a single point following the step increase in power, and then spreads over the surface. The delay time for the inception of boiling at the first site, and the velocity of spread of boiling varies depending upon the heat flux, orientation, body force, surface roughness and liquid properties, and are a consequence of changes in boundary layer temperature levels associated with changes in natural convection. Following the step increase in power input, surface temperature overshoot and undershoot occur before the steady state boiling temperature level is established.

Oker, E.; Merte, H., Jr.

1973-01-01

129

Bilateral Comparison Between NPL and INMETRO Using a High-Temperature Fixed Point of Unknown Temperature  

NASA Astrophysics Data System (ADS)

There is an on-going requirement to perform scale comparisons above the silver point with reduced uncertainties. Previous comparisons have been performed with high stability lamps or radiation thermometers, neither of which were able to achieve the required uncertainty. Ideally a set of driftless unknown temperature fixed points would be used to compare scales, but up to now such artifacts did not exist. This study develops blind high-temperature comparison artifacts based on doped versions of the high-temperature fixed point (HTFP) Ni-C (nominal temperature ). At INMETRO three HTFP blackbodies were constructed, one of pure Ni-C and two doped with different levels of Cu. To ascertain the effect of doping on the transition temperature, the cells were compared to the reference pure Ni-C cell. The doped cells were then transported to NPL and their temperatures measured. NPL was not informed of the INMETRO result ensuring that the measurements remained blind. The cells were then returned to INMETRO and re-measured to establish their stability. The temperatures measured at INMETRO and NPL were then compared and showed very good equivalence of the scale at the fixed-point temperatures. The results of the comparison of the NPL and INMETRO temperature scale, at nominally , are reported, along with evidence of the stability of the artifacts determined from repeat measurements. These promising results indicate that it may be possible to make HTFPs with altered temperatures which are stable enough to serve as comparison artifacts.

Machin, G.; Teixeira, R.; Lu, X.; Lowe, D.

2015-03-01

130

Complex saddle points in QCD at finite temperature and density  

E-print Network

The sign problem in QCD at finite temperature and density leads naturally to the consideration of complex saddle points of the action or effective action. The global symmetry $\\mathcal{CK}$ of the finite-density action, where $\\mathcal{C}$ is charge conjugation and $\\mathcal{K}$ is complex conjugation, constrains the eigenvalues of the Polyakov loop operator $P$ at a saddle point in such a way that the action is real at a saddle point, and net color charge is zero. The values of $Tr_{F}P$ and $Tr_{F}P^{\\dagger}$ at the saddle point, are real but not identical, indicating the different free energy cost associated with inserting a heavy quark versus an antiquark into the system. At such complex saddle points, the mass matrix associated with Polyakov loops may have complex eigenvalues, reflecting oscillatory behavior in color-charge densities. We illustrate these properties with a simple model which includes the one-loop contribution of gluons and massless quarks moving in a constant Polyakov loop background. Confinement-deconfinement effects are modeled phenomenologically via an added potential term depending on the Polyakov loop eigenvalues. For sufficiently large $T$ and $\\mu$, the results obtained reduce to those of perturbation theory at the complex saddle point. These results may be experimentally relevant for the CBM experiment at FAIR.

Hiromichi Nishimura; Michael C. Ogilvie; Kamal Pangeni

2014-08-12

131

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

132

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

133

Finite-temperature critical point of a glass transition  

PubMed Central

We generalize the simplest kinetically constrained model of a glass-forming liquid by softening kinetic constraints, allowing them to be violated with a small rate. We demonstrate that this model supports a first-order dynamical (space–time) phase transition between active (fluid) and inactive (glass) phases. The first-order phase boundary in this softened model ends in a finite-temperature dynamical critical point, which may be present in natural systems. In this case, the glass phase has a very large but finite relaxation time. We discuss links between the dynamical critical point and quantum phase transitions, showing that dynamical phase transitions in d dimensions map to quantum transitions in the same dimension, and hence to classical thermodynamic phase transitions in d + 1 dimensions. PMID:20616075

Elmatad, Yael S.; Jack, Robert L.; Chandler, David; Garrahan, Juan P.

2010-01-01

134

Method for Measuring Collimator-Pointing Sensitivity to Temperature Changes  

NASA Technical Reports Server (NTRS)

For a variety of applications, it is important to measure the sensitivity of the pointing of a beam emerging from a collimator, as a function of temperature changes. A straightforward method for carrying out this measurement is based on using interferometry for monitoring the changes in beam pointing, which presents its own problems. The added temperature dependence and complexity issues relating to using an interferometer are addressed by not using an interferometer in the first place. Instead, the collimator is made part of an arrangement that uses a minimum number of low-cost, off-the-shelf materials and by using a quad diode to measure changes in beam pointing. In order to minimize the influence of the test arrangement on the outcome of the measurement, several steps are taken. The collimator assembly is placed on top of a vertical, 1-m-long, fused silica tube. The quad diode is bonded to a fused silica bar, which, in turn, is bonded to the lower end of the fused silica tube. The lower end of the tube rests on a self-aligning support piece, while the upper end of the tube is kept against two rounded setscrew tips, using a soft rubber string. This ensures that very little stress is applied to the tube as the support structure changes dimensions due to thermal expansion. Light is delivered to the collimator through a bare fiber in order to minimize variable bending torque caused by a randomly relaxing, rigid fiber jacket. In order to separate the effect of temperature on the collimator assembly from the effect temperature has on the rest of the setup, multiple measurements are taken with the collimator assembly rotated from measurement to measurement. Laboratory testing, with 1-m spacing between the collimator and the quad diode, has shown that the sensitivity of the arrangement is better than 100 nm rms, over time spans of at least one hour, if the beam path is protected from atmospheric turbulence by a tube. The equivalent sensitivity to detecting changes in pointing angle is 100 nanoradians.

Abramovici, Alex; Cox, Timothy E.; Hein, Randall C.; MacDonald, Daniel R.

2011-01-01

135

Transition boiling heat transfer from a horizontal surface  

E-print Network

An experiment, utilising a condensing fluid as the heat source, was performed to determine the heat flux vs. temperature difference curve for transition pool boiling from a horisontal surface. The boiling cure was determined ...

Berenson Paul Jerome

1960-01-01

136

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

137

High flux film and transition boiling. Final report, April 1988--January 1993  

SciTech Connect

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 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

138

Fluid inclusion from drill hole DW-5, Hohi geothermal area, Japan: Evidence of boiling and procedure for estimating CO2 content  

USGS Publications Warehouse

Fluid inclusion studies have been used to derive a model for fluid evolution in the Hohi geothermal area, Japan. Six types of fluid inclusions are found in quartz obtained from the drill core of DW-5 hole. They are: (I) primary liquid-rich with evidence of boiling; (II) primary liquid-rich without evidence of boiling; (III) primary vapor-rich (assumed to have been formed by boiling); (IV) secondary liquid-rich with evidence of boiling; (V) secondary liquid-rich without evidence of boiling; (VI) secondary vapor-rich (assumed to have been formed by boiling). Homogenization temperatures (Th) range between 196 and 347??C and the final melting point of ice (Tm) between -0.2 and -4.3??C. The CO2 content was estimated semiquantitatively to be between 0 and 0.39 wt. % based on the bubble behavior on crushing. NaCl equivalent solid solute salinity of fluid inclusions was determined as being between 0 and 6.8 wt. % after minor correction for CO2 content. Fluid inclusions in quartz provide a record of geothermal activity of early boiling and later cooling. The CO2 contents and homogenization temperatures of fluid inclusions with evidence of boiling generally increase with depth; these changes, and NaCl equivalent solid solute salinity of the fluid can be explained by an adiabatic boiling model for a CO2-bearing low-salinity fluid. Some high-salinity inclusions without CO2 are presumed to have formed by a local boiling process due to a temperature increase or a pressure decrease. The liquid-rich primary and secondary inclusions without evidence of boiling formed during the cooling process. The salinity and CO2 content of these inclusions are lower than those in the boiling fluid at the early stage, probably as a result of admixture with groundwater. ?? 1986.

Sasada, M.; Roedder, E.; Belkin, H.E.

1986-01-01

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

Visualization and void fraction measurement of decompressed boiling flow in a capillary tube  

NASA Astrophysics Data System (ADS)

A capillary tube is often used as a throttle for a refrigerating cycle. Subcooled refrigerant usually flows from a condenser into the capillary tube. Then, the refrigerant is decompressed along the capillary tube. When the static pressure falls below the saturation pressure for the liquid temperature, spontaneous boiling occurs. A vapor-liquid two-phase mixture is discharged from the tube. In designing a capillary tube, it is necessary to calculate the flow rate for given boundary conditions on pressure and temperature at the inlet and exit. Since total pressure loss is dominated by frictional and acceleration losses during two-phase flow, it is first necessary to specify the boiling inception point. However, there will be a delay in boiling inception during decompressed flow. This study aimed to clarify the boiling inception point and two-phase flow characteristics of refrigerant in a capillary tube. Refrigerant flows in a coiled copper capillary tube were visualized by neutron radiography. The one-dimensional distribution of volumetric average void fraction was measured from radiographs through image processing. From the void fraction distribution, the boiling inception point was determined. Moreover, a simplified CT method was successfully applied to a radiograph for cross-sectional measurements. The experimental results show the flow pattern transition from intermittent flow to annular flow that occurred at a void fraction of about 0.45.

Asano, H.; Murakawa, H.; Takenaka, N.; Takiguchi, K.; Okamoto, M.; Tsuchiya, T.; Kitaide, Y.; Maruyama, N.

2011-09-01

141

Boiling of nuclear liquid in the micro-canonical ensemble  

E-print Network

Boiling of nuclear liquid in the micro-canonical ensemble K. Miyazaki E-mail: miyazakiro@rio.odn.ne.jp Abstract New calculus of the liquid-gas phase transition is developed for the boiling of nuclear liquid-dependence of the nuclear symmetry energy and the critical temperature of 1 #12;Boiling of nuclear liquid in the micro

142

Development of High-Temperature Fixed Points of Unknown Temperature Suitable for Key Comparisons  

NASA Astrophysics Data System (ADS)

During the last key comparison of local realizations of the International Temperature Scale of 1990 above the silver point, which used high stability tungsten strip lamps, it became clear that these artifacts can no longer be used to evaluate the real calibration and measuring capabilities (CMCs) of the participant laboratories. The intrinsic uncertainty of the lamps is actually larger than the claimed CMCs of most national laboratories. Ideally a set of driftless robust artifacts, preferably of unknown temperature, should be used for this purpose, as this would allow CMCs to be probed at the highest level. Currently such artifacts do not exist. High-temperature fixed points (HTFPs) have been the subject of intense study for more than 10 years. The research has come to an advanced state so much that the temperatures of some of them are well known to be within 1 K. This has rendered their use as comparison artifacts questionable as any comparison would not be blind. To address this issue, doped HTFPs have been developed which have had their transition temperature altered from that of the eutectic composition. Two Ni-C-Cu cells and two Ni-C-Sn were constructed by Inmetro with different quantities of Cu and Sn, respectively. These were compared to a reference Ni-C cell (nominal transition temperature of 1329 C) and the temperature differences from the pure state determined. In this paper the design, construction, and results of long-term stability are described. These promising results indicate that it is possible to make HTFPs with altered temperatures which are stable enough to serve as comparison artifacts.

Teixeira, R.; Machin, G.; Orlando, A.

2014-04-01

143

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

144

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

145

Pool boiling of dielectric liquids on porous graphite and extended copper surfaces  

NASA Astrophysics Data System (ADS)

This work investigated pool boiling of the dielectric liquids HFE-7100 and FC-72 on plane copper and porous graphite and on copper surfaces with corner pins. The work investigated the effects of surface orientation and liquid subcooling and, for the copper surfaces with corner pins, the effect of surface roughness. In addition, investigations were made studying the heat transfer by natural convection and nucleate boiling, as well as the effects of liquid subcooling (up to 30 K) and surface inclination (0°--upward facing, to 180°--downward facing) on nucleate boiling heat transfer and Critical Heat Flux (CHF). The results are applicable to direct immersion cooling by nucleate boiling of high power computer chips dissipating 50 - 100 W/cm2 while maintaining the junction temperature for the chips below the recommended values (˜85 °C). Pool boiling experiments are performed with degassed HFE-7100 and FC-72 liquids using uniformly heated 10 x 10 mm porous graphite and copper surfaces with corner pins. The measured footprint temperatures and thermal power removed from the surfaces are used to construct the pool boiling curves and determine the critical heat flux and corresponding surface superheat. Results are compared with those obtained on plane copper of same heated footprint area. The obtained CHF values are also compared with those reported in the open literature for plane, micro-porous, and macro-structured surfaces. Digital photographs and video are obtained to help explain and interpret the results. For the first time, natural convection correlations for dielectric liquids on plane, porous, and copper with corner pins developed. These correlations are important to electronic cooling in the stand-by mode when the heat dissipation by the chips is only a few watts. Results show that the power removed by natural convection from surfaces with corner pins is 67% more than from plane Si and Cu surfaces at the same surface superheat. Using porous graphite and copper with Cu pins increases the nucleate boiling heat transfer rate over that on plane copper. On all surfaces, as the inclination angle increases, the heat transfer rate at low superheats increases slightly, then decreases with increasing angle at high superheats. However, the porous graphite and the Cu with corner pins significantly reduce the decline in boiling heat transfer rate with increasing inclination. The peak heat transfer coefficient corresponds to the minimum thermal boiling resistance and occurs at a heat flux ˜10% lower than that at CHF. Although the heat flux at the peak heat transfer coefficient is the most desirable operational point, CHF is the upper limit for cooling by nucleate boiling. Beyond CHF the electronics would overheat. Results also show that increasing the height of the corner pins increases the thermal power removed in nucleate boiling and at CHF. CHF increases linearly with increased liquid subcooling, but decreases with increased surface inclination. The decrease in CHF with increased inclination for the surfaces with corner pins is significantly smaller than on plane surfaces. For electronics cooling applications, the best mode of cooling by nucleate boiling is in saturation boiling of HFE-7100 on 5 mm tall corner pins operating at the heat flux corresponding to the minimum boiling resistance. At this condition and using the saturation temperature of HFE-7100 of 54 °C, the wall temperature is 75.2 °C, well below the limit of 85 °C. If more robust electronics are used and have a higher maximum temperature limit, boiling in 30 K subcooled liquid removed much more power. At the minimum boiling resistance, the wall temperature is 83.4 °C. (Abstract shortened by UMI.)

Parker, Jack L.

146

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

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

Spatio-temporal analysis of nucleate pool boiling: identi cation of nucleation sites using  

E-print Network

Spatio-temporal analysis of nucleate pool boiling: identi#12;cation of nucleation sites using non are often limited by the available techniques. These limitations are especially evident in nucleate boiling boiling experiment. Spatio-temporal data for the wall temperature in pool nu- cleate boiling of water

McSharry, Patrick E.

149

Temperature dependent vibrational lifetimes in supercritical fluids near the critical point  

E-print Network

Temperature dependent vibrational lifetimes in supercritical fluids near the critical point D. J) as a function of temperature at constant density in several supercritical solvents in the vicinity the critical temperature (Tc) in which the lifetime increases with increasing temperature. When the temperature

Fayer, Michael D.

150

Pool boiling heat transfer in microgravity  

Microsoft Academic Search

A temperature-controlled pool boiling (TCPB) device has been developed to study the bubble behaviors and heat transfer in\\u000a pool boiling phenomenon both in normal gravity and in microgravity. The results on heat transfer and bubble dynamic behavior\\u000a in the experiments aboard the 22nd Chinese recoverable satellite and those in normal gravity before and after the flight experiment are reported and

J. F. Zhao; S. X. Wan; G. Liu; Z. D. Li; W. R. Hu

2007-01-01

151

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

152

High temperature antenna pointing mechanism for BepiColombo mission  

Microsoft Academic Search

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

Johan A. Mürer; Richard Harper; Mike Anderson

2005-01-01

153

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

154

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

155

Water-cooled end-point boundary temperature control of hot strip via dynamic programming  

Microsoft Academic Search

In this paper, an end-point boundary temperature control approach for runout table cooling used in hot strip mills is presented. The system relies on a linearized model for describing heat radiated to the environment and heat transferred to cooling water. At first, a conventional feedforward control design to control the temperature at the end-point boundary, the only measurable controlled parameter,

Nicholas S. Samaras; Marwan A. Simaan

1998-01-01

156

Water cooled end-point boundary temperature control of hot strip via dynamic programming  

Microsoft Academic Search

This paper presents a system for end-point boundary temperature control approach, for run out table (ROT) cooling, used in hot strip mills. The system relies on a linearized model for describing heat radiated to the environment and heat transferred to cooling water. A conventional feedforward control design to control the temperature at the end boundary point, the only measurable controlled

Nicholas S. Samaras; M. A. Simaan

1997-01-01

157

Numerical solution of the point reactor kinetics equations with fuel burn-up and temperature feedback  

Microsoft Academic Search

Point reactor kinetics equations are solved numerically using one group of delayed neutrons and with fuel burn-up and temperature feedback included. To calculate the fraction of one-group delayed neutrons, a group of differential equations are solved by an implicit time method. Using point reactor kinetics equations, changes in mean neutrons density, temperature, and reactivity are calculated in different times during

S. Tashakor; G. Jahanfarnia; M. Hashemi-Tilehnoee

2010-01-01

158

?-point temperature and exponents for the bond fluctuation model  

NASA Astrophysics Data System (ADS)

We calculate the ?-temperature and the associated critical exponents for the bond fluctuation polymer model of Carmesin and Kremer in two dimensions. The critical exponent values are in agreement with the theoretical predictions. We find that the extra mobility introduced by the flexible bond serves to shift the crossover to the ideal tricritical behavior to a shorter polymer length, compared with previously studied lattice models. In particular, bond-flexible simulations with polymer lengths of the order of 50 already successfully reproduce the properties of infinite chains.

Buldyrev, Sergey V.; Sciortino, Francesco

1992-03-01

159

Development of a mechanistic model for forced convection subcooled boiling  

NASA Astrophysics Data System (ADS)

The focus of this work is on the formulation, implementation, and testing of a mechanistic model of subcooled boiling. Subcooled boiling is the process of vapor generation on a heated wall when the bulk liquid temperature is still below saturation. This is part of a larger effort by the US DoE's CASL project to apply advanced computational tools to the simulation of light water reactors. To support this effort, the formulation of the dispersed field model is described and a complete model of interfacial forces is formulated. The model has been implemented in the NPHASE-CMFD computer code with a K-epsilon model of turbulence. The interfacial force models are built on extensive work by other authors, and include novel formulations of the turbulent dispersion and lift forces. The complete model of interfacial forces is compared to experiments for adiabatic bubbly flows, including both steady-state and unsteady conditions. The same model is then applied to a transient gas/liquid flow in a complex geometry of fuel channels in a sodium fast reactor. Building on the foundation of the interfacial force model, a mechanistic model of forced-convection subcooled boiling is proposed. This model uses the heat flux partitioning concept and accounts for condensation of bubbles attached to the wall. This allows the model to capture the enhanced heat transfer associated with boiling before the point of net generation of vapor, a phenomenon consistent with existing experimental observations. The model is compared to four different experiments encompassing flows of light water, heavy water, and R12 at different pressures, in cylindrical channels, an internally heated annulus, and a rectangular channel. The experimental data includes axial and radial profiles of both liquid temperature and vapor volume fraction, and the agreement can be considered quite good. The complete model is then applied to simulations of subcooled boiling in nuclear reactor subchannels consistent with the operating conditions of the AP1000 pressurized water reactor. The effects of both axial and lateral nonuniform power distributions inside reactor fuel elements are accounted for. Boiling flows are simulated for three different computational domains of increasing complexity: a quarter-subchannel bordering a single fuel pin, two subchannels surround by an array of 2 by 3 fuel pins, and in four subchannels surrounded by an array of 3 by 3 fuel pins. The predicted behavior is consistent with expectations. In the 3 by 3 array, the two-phase coolant is predicted to flow from the hot channels to the cold channels, enhancing heat exchange between subchannels. This, in turn, demonstrates that the new model is capable of capturing the turbulence- and buoyancy-induced coolant mixing across the neighboring channels.

Shaver, Dillon R.

160

TRANSITION BOILING HEAT TRANSFER PROGRAM. Third Quarterly Progress Report, July-September 1963  

Microsoft Academic Search

Initial critical heat flux, transition boiling temperature fluctuation, ; and film boiling coefficient data were obtained on a two-rod cluster assembly at ; 1000 psia and 25 to 90% steam qualities. A representation showing the range of ; critical heat flux data is presented, and typical temperature recordings that ; indicate transition and film boiling behavior are shown. Fabrication of

E. P. ed

1963-01-01

161

EVALUATION OF ROTARY KILN INCINERATOR OPERATION AT LOW TO MODERATE TEMPERATURE CONDITIONS VOLUME 1. TECHNICAL RESULTS  

EPA Science Inventory

A test program was performed at the Environmental Protection Agency Incineration Research Facility to study the effectiveness of incineration at low-to-moderate temperatures in decontaminating soils containing organic compounds with different volatilities (boiling points). The da...

162

The Evaluation of the Emissivity and the Temperature of Cavities at the Gold Freezing Point  

NASA Astrophysics Data System (ADS)

In the present investigation, the integral equation for the temperature distribution inside the cavity at the gold freezing point, and the relation between the emissivity and the local temperature have been derived according to the basic ideas of Geist. In addition, we have calculated the changes of the temperature and emissivity of the bottom of a baffled cylindrical cavity due to the changes in the temperature of the baffle. Some typical results are given here.

Hongpan, Chen; Shouren, Chen; Zaixiang, Chu

1981-04-01

163

Enhancements of Nucleate Boiling Under Microgravity Conditions  

NASA Technical Reports Server (NTRS)

This paper presents two means for enhancing nucleate boiling and critical heat flux under microgravity conditions: using micro-configured metal-graphite composites as the boiling surface and dilute aqueous solutions of long-chain alcohols as the working fluid. In the former, thermocapillary force induced by temperature difference between the graphite-fiber tips and the metal matrix plays an important role in bubble detachment. Thus boiling-heat transfer performance does not deteriorate in a reduced-gravity environment. In the latter cases, the surface tension-temperature gradient of the long-chain alcohol solutions turns positive as the temperature exceeds a certain value. Consequently, the Marangoni effect does not impede, but rather aids in bubble departure from the heating surface. This feature is most favorable in microgravity. As a result, the bubble size of departure is substantially reduced at higher frequencies. Based on the existing experimental data, and a two-tier theoretical model, correlation formulas are derived for nucleate boiling on the copper-graphite and aluminum-graphite composite surfaces, in both the isolated and coalesced bubble regimes. In addition, performance equations for nucleate boiling and critical heat flux in dilute aqueous solutions of long-chain alcohols are obtained.

Zhang, Nengli; Chao, David F.; Yang, W. J.

2000-01-01

164

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

165

Critical heat flux and boiling heat transfer to water in a 3-mm-diameter horizontal tube.  

SciTech Connect

Boiling of the coolant in an engine, by design or by circumstance, is limited by the critical heat flux phenomenon. As a first step in providing relevant engine design information, this study experimentally addressed both rate of boiling heat transfer and conditions at the critical point of water in a horizontal tube of 2.98 mm inside diameter and 0.9144 m heated length. Experiments were performed at system pressure of 203 kPa, mass fluxes in range of 50 to 200 kg/m{sup z}s, and inlet temperatures in range of ambient to 80 C. Experimental results and comparisons with predictive correlations are presented.

Yu, W.; Wambsganss, M. W.; Hull, J. R.; France, D. M.

2000-12-04

166

Heat transport in boiling turbulent Rayleigh-B\\'{e}nard convection  

E-print Network

Boiling is an extremely effective way to promote heat transfer from a hot surface to a liquid due to several mechanisms many of which are not understood in quantitative detail. An important component of the overall process is that the buoyancy of the bubbles compounds with that of the liquid to give rise to a much enhanced natural convection. In this paper we focus specifically on this enhancement and present a numerical study of the resulting two-phase Rayleigh-B\\'enard convection process. We make no attempt to model other aspects of the boiling process such as bubble nucleation and detachment. We consider a cylindrical cell with a diameter equal to its height. The cell base and top are held at temperatures above and below the boiling point of the liquid, respectively. By keeping the temperature difference constant and changing the liquid pressure we study the effect of the liquid superheat in a Rayleigh number range that, in the absence of boiling, would be between $2\\times10^6$ and $5\\times10^9$. We find a...

Lakkaraju, Rajaram; Oresta, Paolo; Verzicco, Roberto; Lohse, Detlef; Prosperetti, Andrea

2014-01-01

167

Temperature-dependent growth mechanism and microstructure of ZnO nanostructures grown from the thermal oxidation of zinc  

NASA Astrophysics Data System (ADS)

We report a detailed study on the growth morphologies and microstructure of ZnO nanostructures formed from the oxidation of Zn at different temperatures. ZnO shows bicrystalline nanowire morphology for oxidation below the melting point of Zn, and single-crystalline morphology between the melting and boiling points of Zn, and tetrapod morphology above the boiling point of Zn. The morphological and microstructural variations are attributed to the temperature-dependent oxide growth mechanisms, i.e., the oxidation below the melting point of Zn is dominated by a solid-solid transformation process, a liquid-solid process between the melting and boiling points of Zn, and a vapor-solid process above the boiling point of Zn. The understanding of the oxide growth mechanisms from these results may have practical implications for rational control of the morphology, crystallinity, preferential growth directions, shape and aspect ratio of ZnO nanostructures

Yuan, Lu; Wang, Chao; Cai, Rongsheng; Wang, Yiqian; Zhou, Guangwen

2014-03-01

168

Changes in skin surface temperature at an acupuncture point with moxibustion  

PubMed Central

Objective This study evaluates the thermographic changes associated with moxa burner moxibustion at the SP6 acupuncture point to establish an appropriate, safe distance of efficacy for moxibustion. Methods Baseline temperature changes using a moxa burner were obtained for a paper substrate at various distances and times, and the tested with volunteers in a pilot study. A single-group trial was then conducted with 36 healthy women to monitor temperature changes on the body surface at the acupuncture point (SP6). Results Based on the temperature changes seen for the paper substrate and in the pilot study, a distance of 3?cm was chosen as the intervention distance. Moxibustion significantly increased the SP6 point skin surface temperature, with a peak increase of 11°C at 4?min (p?<0.001). This study also found that during moxibustion the temperature of the moxa burner's rubber layer and moxa cautery were 56.9±0.9°C and 65.8±1.2°C, as compared to baseline values of 35.1°C and 43.8°C (p<0.001). Conclusions We determined 3?cm was a safe distance between the moxa burner and acupuncture point. Moxibustion can increase the skin surface temperature at the SP6 point. This data will aid traditional Chinese medicine (TCM) practitioners in gauging safer treatment distances when using moxibustion treatments. PMID:23598824

Lin, Li-Mei; Wang, Shu-Fang; Lee, Ru-Ping; Hsu, Bang-Gee; Tsai, Nu-Man; Peng, Tai-Chu

2013-01-01

169

Water-cooled end-point boundary temperature control of hot strip via dynamic programming  

SciTech Connect

In this paper, an end-point boundary temperature control approach for runout table cooling used in hot strip mills is presented. The system relies on a linearized model for describing heat radiated to the environment and heat transferred to cooling water. At first, a conventional feedforward control design to control the temperature at the end-point boundary, the only measurable controlled parameter, is presented. Subsequently, a modified control scheme which uses dynamic programming to minimize the temperature error at the end-point boundary is discussed in detail. System performance analysis via simulation is presented for both control schemes. Simulation results show that temperature error minimization by dynamic programming improves system performance.

Samaras, N.S. [Danieli Automation, Pittsburgh, PA (United States)] [Danieli Automation, Pittsburgh, PA (United States); Simaan, M.A. [Univ. of Pittsburgh, PA (United States). Dept. of Electrical Engineering] [Univ. of Pittsburgh, PA (United States). Dept. of Electrical Engineering

1998-11-01

170

A fundamental study of nucleate pool boiling under microgravity  

NASA Technical Reports Server (NTRS)

An experimental study of incipient boiling in short-term microgravity and with a/g = +/- 1 for pool boiling was performed. Calibrated thin gold films sputtered on a smoothly polished quartz surface were used simultaneously for thermal resistance measurements and heating of the boiling surface. The gold films were used for both transient and quasi-steady heating surface temperature measurements. Two test vessels were constructed for precise measurement and control of fluid temperature and pressure: a laboratory pool boiling vessel for the a/g = +/- experiments and a pool boiling vessel designed for the 131 m free-fall in the NASA Lewis Research Center Microgravity Research Facility for the microgravity tests. Measurements included the heater surface temperature, the pressure near the heating surface, and the bulk liquid temperatures. High speed photography was used in the experiments. With high quality microgravity and the measured initial temperature of the quiescent test fluid, R113, the temperature distribution in the liquid at the moment of boiling inception resulting from an imposed step in heat flux is known with a certainty not possible previously. The types of boiling propagation across the large flat heating surface are categorized; the conditions necessary for their occurrence are described. Explosive boiling propagation with a striking pattern of small scale protuberances over the entire vapor mass periphery not observed previously at low heat flux levels is described. For the heater surface with a/g = -1, a step in the heater surface temperature of short duration was imposed. The resulting liquid temperature distribution at the moment of boiling inception was different from that obtained with a step in heat flux.

Ervin, Jamie S.; Merte, Herman, Jr.

1991-01-01

171

A Fundamental Study of Nucleate Pool Boiling Under Microgravity  

NASA Technical Reports Server (NTRS)

An experimental study of incipient boiling in short-term microgravity and with a/g = +/- 1 for pool boiling was performed. Calibrated thin gold films sputtered on a smoothly polished quartz surface were used simultaneously for thermal-resistance measurements and heating of the boiling surface. The gold films were used for both transient and quasi-steady heating surface temperature measurements. Two test vessels were constructed for precise measurement and control of fluid temperature and pressure: a laboratory pool boiling vessel for the a/g = +/- 1 experiments and a pool boiling vessel designed for the 131 m free-fall in the NASA Lewis Research Center Microgravity Research Facility for the microgravity tests. Measurements included the heater surface temperature, the pressure near the heating surface, the bulk liquid temperatures. High speed photography (up to 1,000 frames per second) was used in the experiments. With high quality microgravity and the measured initial temperature of the quiescent test fluid, R113, the temperature distribution in the liquid at the moment of boiling inception resulting from an imposed step in heat flux is known with a certainty not possible previously. The types of boiling propagation across the large flat heating surface, some observed here for the first time, are categorized; the conditions necessary for their occurrence are described. Explosive boiling propagation with a striking pattern of small scale protuberances over the entire vapor mass periphery not observed previously at low heat flux levels (on the order of 5 W/cm(exp 2)) is described. For the heater surface with a/g = -1, a step in the heater surface temperature of short duration was imposed. The resulting liquid temperature distribution at the moment of boiling inception was different from that obtained with a step in heat flux.

Ervin, Jamie S.; Merte, Herman, Jr.

1996-01-01

172

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

173

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

174

Stability analysis of two-dimensional pool-boiling systems M. Speetjens  

E-print Network

Stability analysis of two-dimensional pool-boiling systems M. Speetjens , A. Reusken , S. Maier In this paper we consider a model for pool-boiling systems known from the liter- ature. This model involves only the temperature distribution within the heater and models the heat exchange with the boiling medium via

175

Numerical study of bubble growth and wall heat transfer during flow boiling in a microchannel  

E-print Network

Numerical study of bubble growth and wall heat transfer during flow boiling in a microchannel A 2011 Accepted 27 January 2011 Available online 12 April 2011 Keywords: Flow boiling Microchannels saturation temperature. During flow boiling, bubbles nucleate on the microchannel walls and may grow big en

Kandlikar, Satish

176

Steady-state solutions in a nonlinear pool boiling model Michel Speetjens  

E-print Network

Steady-state solutions in a nonlinear pool boiling model Michel Speetjens , Arnold Reusken a relatively simple model for pool boiling processes. This model involves only the temperature distribution within the heater and describes the heat exchange with the boiling fluid via a nonlinear boundary

177

Spatio-temporal analysis of nucleate pool boiling: identication of nucleation sites using non-orthogonal  

E-print Network

Spatio-temporal analysis of nucleate pool boiling: identi®cation of nucleation sites using non techniques. These limitations are especially evident in nucleate boiling. This paper investigates the analysis of a sequence of temperature ®elds obtained from a pool nucleate boiling experiment. Spatio

Stevenson, Paul

178

Original article Effect of oven -heat and boiling on the germination  

E-print Network

Original article Effect of oven - heat and boiling on the germination and seedling development and Arn. seeds were heated to various temperature ranges in the oven and immersed in boiling water growth of the resultant seedlings. Immersing seeds in boiling water (100 °C) for 10s recorded the high

Paris-Sud XI, Université de

179

Influence of the wettability on the boiling onset.  

PubMed

Experimental investigation of pool boiling is conducted in stationary conditions over very smooth bronze surfaces covered by a very thin layer of gold presenting various surface treatments to isolate the role of wettability. We show that even with surfaces presenting mean roughness amplitudes below 10 nm the role of surface topography is of importance. The study shows also that wettability alone can trigger the boiling and that the boiling position on the surface can be controlled by chemical grafting using for instance alkanethiol. Moreover, boiling curves, that is, heat flux versus the surface superheat (which is the difference between the solid surface temperature and the liquid saturation temperature), are recorded and enabled to quantify, for this case, the significant reduction of the superheat at the onset of incipient boiling due to wettability. PMID:22166139

Bourdon, B; Rioboo, R; Marengo, M; Gosselin, E; De Coninck, J

2012-01-17

180

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

181

Cryogenic Boil-Off Reduction System Testing  

NASA Technical Reports Server (NTRS)

The Cryogenic Boil-Off Reduction System was tested with LH2 and LOX in a vacuum chamber to simulate space vacuum and the temperatures of low Earth orbit. Testing was successful and results validated the scaling study model that predicts active cooling reduces upper stage cryogenic propulsion mass for loiter periods greater than 2 weeks.

Plachta, David W.; Johnson, Wesley L.; Feller, Jeffery

2014-01-01

182

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

183

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

184

Modeling of Aerobrake Ballute Stagnation Point Temperature and Heat Transfer to Inflation Gas  

NASA Technical Reports Server (NTRS)

A trailing Ballute drag device concept for spacecraft aerocapture is considered. A thermal model for calculation of the Ballute membrane temperature and the inflation gas temperature is developed. An algorithm capturing the most salient features of the concept is implemented. In conjunction with the thermal model, trajectory calculations for two candidate missions, Titan Explorer and Neptune Orbiter missions, are used to estimate the stagnation point temperature and the inflation gas temperature. Radiation from both sides of the membrane at the stagnation point and conduction to the inflating gas is included. The results showed that the radiation from the membrane and to a much lesser extent conduction to the inflating gas, are likely to be the controlling heat transfer mechanisms and that the increase in gas temperature due to aerodynamic heating is of secondary importance.

Bahrami, Parviz A.

2012-01-01

185

Loop Heat Pipe Operation Using Heat Source Temperature for Set Point Control  

NASA Technical Reports Server (NTRS)

The LHP operating temperature is governed by the saturation temperature of its reservoir. Controlling the reservoir saturation temperature is commonly accomplished by cold biasing the reservoir and using electrical heaters to provide the required control power. Using this method, the loop operating temperature can be controlled within +/- 0.5K. However, because of the thermal resistance that exists between the heat source and the LHP evaporator, the heat source temperature will vary with its heat output even if LHP operating temperature is kept constant. Since maintaining a constant heat source temperature is of most interest, a question often raised is whether the heat source temperature can be used for LHP set point temperature control. A test program with a miniature LHP has been carried out to investigate the effects on the LHP operation when the control temperature sensor is placed on the heat source instead of the reservoir. In these tests, the LHP reservoir is cold-biased and is heated by a control heater. Tests results show that it is feasible to use the heat source temperature for feedback control of the LHP operation. Using this method, the heat source temperature can be maintained within a tight range for moderate and high powers. At low powers, however, temperature oscillations may occur due to interactions among the reservoir control heater power, the heat source mass, and the heat output from the heat source. In addition, the heat source temperature could temporarily deviate from its set point during fast thermal transients. The implication is that more sophisticated feedback control algorithms need to be implemented for LHP transient operation when the heat source temperature is used for feedback control.

Ku, Jentung; Paiva, Kleber; Mantelli, Marcia

2011-01-01

186

Temperature-programmed capillary electrophoresis for the analysis of high-melting point mutants in thalassemias.  

PubMed

The behavior of different sieving polymers for unambiguous determination of point mutations in genomic DNA, based on electrophoresis in thin capillaries, is evaluated. High melters from thalassemia patients are separated by exploiting the principle of denaturing gradient gel electrophoresis, in fact, of its variant utilizing temperature gradients (TGGE), along the migration path, encompassing the melting points of both homo- and heteroduplex, polymerase chain reaction (PCR)-amplified DNA fragments. Unlike TGGE, where the temperature gradient exists along the separation space, the denaturing temperature gradient in the fused-silica capillaries is time-programmed, so as to reach the Tm's of all species under analysis prior to electrophoretic transport past the detector window. The DNA fragments are injected in a capillary maintained (by combined chemical and thermal means) just below the expected Tm values. The deltaT applied is rather minute (1-1.5 degrees C) and the temperature gradient quite shallow (e.g., 0.05 degrees C/min). The denaturing thermal gradient is generated internally, via Joule heat produced by voltage ramps. This method is applied to the analysis of the most common point mutations in thalassemias, characterized by being high melters (in the temperature range of 60-62 degrees C) in presence of 6 M urea. Point mutants are fully resolved into a spectrum of four bands only when poly(N-acryloylaminopropanol) and hydroxyethylcellulose are used. However, the former offers the best separation capability at such high temperatures. PMID:9194597

Gelfi, C; Righetti, P G; Travi, M; Fattore, S

1997-05-01

187

Stability of cobalt–carbon high temperature fixed points doped with iron and platinum  

NASA Astrophysics Data System (ADS)

High temperature fixed points (HTFPs) are stable and repeatable and make comparison of temperature scales possible at a level of uncertainty not previously possible. However, they potentially lack objectivity if the fixed-point temperature is known. Five HTFPs were constructed, one pure Co–C, two Co–C doped with Fe and two Co–C doped with Pt of differing concentrations. The candidate dopants were identified through thermochemical modelling as likely to give maximum temperature shift with minimum increase in melting range. The temperature differences of the doped systems from the pure system were determined and it was found that the addition of Fe depressed the melting temperature and the addition of Pt elevated the melting temperature, qualitatively in line with the thermochemical modelling. The higher concentration doped HTFPs were then aged for approximately 100?h with continuous melting–freezing cycles and the difference to the undoped Co–C HTFP remeasured. These differences were found to agree with those of the unaged results within the measurement uncertainties, confirming artefact stability. It is clear that the doping of HTFPs is a powerful way of constructing stable and reliable high temperature scale comparison artefacts of unknown temperature.

K?azovická, L.; Lowe, D.; Machin, G.; Davies, H.; Rani, A.

2015-04-01

188

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. PMID:20207876

Rosa, Ghislaine; Miller, Laura; Clasen, Thomas

2010-01-01

189

Temperature-programmed capillary electrophoresis for detection of DNA point mutations.  

PubMed

A method for unambiguous determination of point mutations in genomic DNA, based on electrophoresis in thin capillaries, is reported here. The method is based on the principle of temperature gradient gel electrophoresis (TGGE), a variant of denaturing gradient gel electrophoresis (DGGE), and exploits the differential melting of mutant and wild-type PCR-amplified DNA fragments during electrophoresis through a temperature gradient. Unlike TGGE, where the temperature gradient exists along the separation space, the denaturing temperature gradient in the fused-silica capillaries is time-programmed, so as to reach the melting points (Tms) of all species under analysis prior to electrophoretic transport past the detector window. The DNA fragments are injected in a capillary maintained (by combined chemical and thermal means) just below the expected Tm values. The temperature increment applied is typically minute (1 degree -1.5 degrees C) and the sweep speed is rather shallow (e.g., 0.05 degree C/min). Additionally, the denaturing thermal gradient is not controlled externally, but generated internally by Joule heat produced by voltage ramps. Point mutants are fully resolved into a spectrum of four bands, with a dynamic range extending from 45 degrees C (low melters) up to 70 degrees C for high melters. The present method can thus be universally applied to any type of point mutation. PMID:8922636

Gelfi, C; Cremonesi, L; Ferrari, M; Righetti, P G

1996-11-01

190

Temperatures in the earth's core from melting-point measurements of iron at high static pressures  

Microsoft Academic Search

The most reliable method for determining the temperature gradient at the earth's core is the estimation of Fe and Fe-rich compounds' melting temperature at the pressure of the inner core boundary. Attention is presently given to melting-point measurements on Fe and Fe-O compounds at up to 2 Mbar. An extrapolation of these results to 3.3 Mbar yields an inner core

R. Boehler

1993-01-01

191

Temperature and Species Measurements of Combustion Produced by a 9-Point Lean Direct Injector  

NASA Technical Reports Server (NTRS)

This paper presents measurements of temperature and relative species concentrations in the combustion flowfield of a 9-point swirl venturi lean direct injector fueled with JP-8. The temperature and relative species concentrations of the flame produced by the injector were measured using spontaneous Raman scattering (SRS). Results of measurements taken at four flame conditions are presented. The species concentrations reported are measured relative to nitrogen and include oxygen, carbon dioxide, and water.

Tedder, Sarah A.; Hicks, Yolanda R.; Locke, Randy J.

2013-01-01

192

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

193

An efficient technique for the point reactor kinetics equations with Newtonian temperature feedback effects  

Microsoft Academic Search

The point reactor kinetics equations of multi-group of delayed neutrons in the presence Newtonian temperature feedback effects are a system of stiff nonlinear ordinary differential equations which have not any exact analytical solution. The efficient technique for this nonlinear system is based on changing this nonlinear system to a linear system by the predicted value of reactivity and solving this

Abdallah A. Nahla

2011-01-01

194

Boiling on Microconfigured Composite Surfaces Enhanced  

NASA Technical Reports Server (NTRS)

Boiling heat transfer is one of the key technologies for the two-phase active thermal-control system used on space platforms, as well as for the dynamic power systems aboard the International Space Station. Because it is an effective heat transfer mode, boiling is integral to many space applications, such as heat exchangers and other cooling devices. Nucleate boiling near the critical heat flux (CHF) can transport very large thermal loads with a much smaller device and much lower pumping power than for single-phase heat exchangers. However, boiling performance sharply deteriorates in a reduced-gravity environment, and operation in the CHF regime is somewhat perilous because of the risk of burnout to the device surface. New materials called microconfigured metal-graphite composites can enhance boiling. The photomicrograph shows the microconfiguration (x3000) of the copper-graphite (Cu-Gr) surface as viewed by scanning electronic microscope. The graphite fiber tips appear as plateaus with rugged surfaces embedded in the copper matrix. It has been experimentally demonstrated that this type of material manifests excellent boiling heat transfer performance characteristics and an increased CHF. Nonisothermal surfaces were less sensitive to variations of wall superheat in the CHF regime. Because of the great difference in conductivity between the copper base and the graphite fiber, the composite surfaces have a nonisothermal surface characteristic and, therefore, will have a much larger "safe" operating region in the CHF regime. In addition, the thermocapillary forces induced by the temperature differences between the fiber tips and the metal matrix play an important role in bubble detachment, and may not be adversely affected in a reduced-gravity environment. All these factors indicate that microconfigured composites may improve the reliability and economy (dominant factors in all space applications) of various thermal components found on spacecraft during future missions.

Chao, David F.

2000-01-01

195

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

196

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.

1992-01-01

197

POINT 2007: A Temperature Dependent ENDF/.B-VII.0 Data 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 publicly available nuclear data (the current ENDF/B data, available online at the National Nuclear Data Center, Brookhaven National Laboratory http://www.nndc.bnl.gov/) and publicly available computer codes (the current PREPRO codes, available on-line at the Nuclear Data Section, IAEA, Vienna, Austria http://wwwnds. iaea.or.at/ndspub/endf/prepro/). I have used these in combination to produce the temperature dependent cross sections used in applications and presented in this report. The preceding POINT 2004 report [R1] presented results for the now frozen last version of ENDF/B-VI, Release 8. The current POINT 2007 report is based on data from recently released ENDF/B-VII.0, which is the first release of ENDF/B-VII.

Cullen, D E

2007-02-13

198

Critical temperature of the leadbismuth eutectic (LBE) alloy Abdul-Majeed Azad *  

E-print Network

; boiling point = 2022 K) and Pb (melting point = 600 K; boiling point = 1837 K) as well as the Pb­Bi eutectic alloy (LBE, melting point = 396 K; boil- ing point = 1943 K) have been serious contenders for use neutron absorption and activation, high boiling point and poor interaction with water and air, etc

Azad, Abdul-Majeed

199

Ductile-Brittle Transition Temperature testing of tungsten using the three-point bend test  

SciTech Connect

Three-point bend tests were performed to determine the Ductile-Brittle Transition Temperatures (DBTTs) of forged and chemical vapor deposition (CVD) tungsten. Testing was performed under quasi-static conditions at temperatures between 23{degrees}C and 450{degrees}C using a forced-air environmental chamber. Load-displacement data from the three-point bend tests indicated that the constitutive behavior of the materials tested varied considerably. Finite element modeling of the three-point bend test was performed to investigate plastic strains induced in the samples during testing as a function of constitutive behavior. The modeling assumed plane stress conditions in the sample and simple bi-linear elastic-plastic constitutive behavior of the test material. The strains induced in the samples were found to be functions of both the yield stress and work hardening behavior of the materials. The use of the three-point bend test to determine DBTT, and the DBTTs reported for the test materials, are discussed relative to the modeling results. It is concluded that the three-point bend test has some utility in the determination of DBTTs if some caution is used in the selection of test parameters and fixture geometries. However, the three-point bed test does not provide a complete picture of the nature of the ductile-brittle transition. 12 refs., 9 figs.

Lassila, D.H.; Magness, F.; Freeman, D.

1991-03-05

200

Analysis of Screen Channel LAD Bubble Point Tests in Liquid Methane at Elevated Temperature  

NASA Technical Reports Server (NTRS)

This paper examines the effect of varying the liquid temperature and pressure on the bubble point pressure for screen channel Liquid Acquisition Devices in cryogenic liquid methane using gaseous helium across a wide range of elevated pressures and temperatures. Testing of a 325 x 2300 Dutch Twill screen sample was conducted in the Cryogenic Components Lab 7 facility at the NASA Glenn Research Center in Cleveland, Ohio. Test conditions ranged from 105 to 160K and 0.0965 - 1.78 MPa. Bubble point is shown to be a strong function of the liquid temperature and a weak function of the amount of subcooling at the LAD screen. The model predicts well for saturated liquid but under predicts the subcooled data.

Hartwig, Jason; McQuillen, John

2012-01-01

201

Estimation of the temperature dependent interaction between uncharged point defects in Si  

NASA Astrophysics Data System (ADS)

A method is described to estimate the temperature dependent interaction between two uncharged point defects in Si based on DFT calculations. As an illustration, the formation of the uncharged di-vacancy V2 is discussed, based on the temperature dependent attractive field between both vacancies. For that purpose, all irreducible configurations of two uncharged vacancies are determined, each with their weight given by the number of equivalent configurations. Using a standard 216-atoms supercell, nineteen irreducible configurations of two vacancies are obtained. The binding energies of all these configurations are calculated. Each vacancy is surrounded by several attractive sites for another vacancy. The obtained temperature dependent of total volume of these attractive sites has a radius that is closely related with the capture radius for the formation of a di-vacancy that is used in continuum theory. The presented methodology can in principle also be applied to estimate the capture radius for pair formation of any type of point defects.

Kamiyama, Eiji; Vanhellemont, Jan; Sueoka, Koji

2015-01-01

202

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

SciTech Connect

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. [National Physical Laboratory, Teddington (United Kingdom)] [National Physical Laboratory, Teddington (United Kingdom)

2013-09-11

203

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

204

Correlation Between Immersion Profile and Measured Value of Fixed-Point Temperature  

NASA Astrophysics Data System (ADS)

Assessment of thermal immersion effects in the melting and freezing points defined by the International Temperature Scale of 1990 is one of the vital issues of modern thermometry. In documents of the Consultative Committee for Thermometry, the deviation of the experimental immersion profile from the theoretical value of the hydrostatic effect at a height of about 3 cm to 5 cm from the thermometer well bottom is used for the estimation of the uncertainty due to unwanted thermal effects. This estimation assumes the occurrence of solely the hydrostatic effect all along the height of the well inner wall. Real distortions of the temperature gradient at the bottom and at the top part of the well caused by the change of heat-exchange conditions are not taken into account. To define more precisely the temperature gradient along the height of the well, a miniature PRT with a 30 mm sensitive element and a sheath length and diameter of about 60 mm and 6 mm, respectively, were used. Also, the measurements of fixed-points temperature at noticeably different slopes of immersion profiles due to variations of the thermometer heat exchange and phase transition realization conditions were produced by means of a standard platinum resistance thermometer (SPRT). The measurements were carried out at the tin and zinc freezing points. The immersion curves measured with a miniature thermometer demonstrated an increase of the temperature during its lifting in the first 1 cm to 3 cm above the bottom of the well. The measurement results at the zinc freezing point by means of the SPRT have not confirmed the correlation between the immersion curves, the received value of the Zn freezing temperature, and the estimation of its uncertainty.

Shulgat, O. S.; Fuksov, V. M.; Ivanova, A. G.; Gerasimov, S. F.; Pokhodun, A. I.

2014-04-01

205

Optimization of the thermogauge furnace for realizing high temperature fixed points  

SciTech Connect

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. [National Institute of Metrology (NIM), Beijing (China)] [National Institute of Metrology (NIM), Beijing (China); Liu, F. [AVIC China Precision Engineering Institute for Aircraft Industry, Beijing (China)] [AVIC China Precision Engineering Institute for Aircraft Industry, Beijing (China)

2013-09-11

206

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

207

Boiling incipience and convective boiling of neon and nitrogen  

NASA Technical Reports Server (NTRS)

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. This design precludes nucleate boiling in the flow channels as they are too small to handle vapor flow. Consequently, it was necessary to determine boiling incipience under the operating conditions of the magnet system. 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 and convective boiling heat transfer coefficients in uniformly heated flow channels. The accuracy of the correlating equations was then evaluated. A technique was also developed to calculate the position of boiling incipience in a uniformly heated flow channel. Comparisons made with the experimental data showed a prediction accuracy of plus or minus 15 percent

Papell, S. S.; Hendricks, R. C.

1977-01-01

208

Liquid Oxygen Liquid Acquisition Device Bubble Point Tests with High Pressure LOX at Elevated Temperatures  

NASA Technical Reports Server (NTRS)

When transferring propellant in space, it is most efficient to transfer single phase liquid from a propellant tank to an engine. In earth s gravity field or under acceleration, propellant transfer is fairly simple. However, in low gravity, withdrawing single-phase fluid becomes a challenge. A variety of propellant management devices (PMD) are used to ensure single-phase flow. One type of PMD, a liquid acquisition device (LAD) takes advantage of capillary flow and surface tension to acquire liquid. The present work reports on testing with liquid oxygen (LOX) at elevated pressures (and thus temperatures) (maximum pressure 1724 kPa and maximum temperature 122K) as part of NASA s continuing cryogenic LAD development program. These tests evaluate LAD performance for LOX stored in higher pressure vessels that may be used in propellant systems using pressure fed engines. Test data shows a significant drop in LAD bubble point values at higher liquid temperatures, consistent with lower liquid surface tension at those temperatures. Test data also indicates that there are no first order effects of helium solubility in LOX on LAD bubble point prediction. Test results here extend the range of data for LOX fluid conditions, and provide insight into factors affecting predicting LAD bubble point pressures.

Jurns, John M.; Hartwig, Jason W.

2011-01-01

209

Liquid oxygen liquid acquisition device bubble point tests with high pressure lox at elevated temperatures  

NASA Astrophysics Data System (ADS)

When transferring propellant in space, it is most efficient to transfer single phase liquid from a propellant tank to an engine. In earth's gravity field or under acceleration, propellant transfer is fairly simple. However, in low gravity, withdrawing single-phase fluid becomes a challenge. A variety of propellant management devices (PMDs) are used to ensure single-phase flow. One type of PMD, a liquid acquisition device (LAD) takes advantage of capillary flow and surface tension to acquire liquid. The present work reports on testing with liquid oxygen (LOX) at elevated pressures (and thus temperatures) (maximum pressure 1724 kPa and maximum temperature 122 K) as part of NASA's continuing cryogenic LAD development program. These tests evaluate LAD performance for LOX stored in higher pressure vessels that may be used in propellant systems using pressure fed engines. Test data shows a significant drop in LAD bubble point values at higher liquid temperatures, consistent with lower liquid surface tension at those temperatures. Test data also indicates that there are no first order effects of helium solubility in LOX on LAD bubble point prediction. Test results here extend the range of data for LOX fluid conditions, and provide insight into factors affecting predicting LAD bubble point pressures.

Jurns, J. M.; Hartwig, J. W.

2012-04-01

210

On using film boiling to thermally decompose liquid organic chemicals: Application to ethyl acetate as a model compound  

E-print Network

On using film boiling to thermally decompose liquid organic chemicals: Application to ethyl acetate 21 August 2013 Keywords: Film boiling Thermal decomposition Pyrolysis Ethyl acetate Critical heat flux (CHF) Leidenfrost point a b s t r a c t Film boiling on a horizontal tube is used to study

Walter, M.Todd

211

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

212

Boiling incipience and convective boiling of neon and nitrogen  

NASA Technical Reports Server (NTRS)

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 and convective boiling heat transfer coefficients in uniformly heated flow channels. The accuracy of the correlating equations was then evaluated. A technique was also developed to calculate the position of boiling incipience in a uniformly heated flow channel. Comparisons made with the experimental data showed a prediction accuracy of + or - 15 percent.

Papell, S. S.; Hendricks, R. C.

1977-01-01

213

Subcooled convective boiling in structured surface microchannels  

NASA Astrophysics Data System (ADS)

Experiments are performed to investigate subcooled flow boiling, on side wall cavities with angles of 60°, 90° and 120° with bottom-wall asymmetrical heating, for a microchannel heat sink containing 75 parallel 100 µm × 200 µm channels. The heated surface is made of a Cu metal sheet with/without 2 µm thickness diamond film. Tests and measurements are conducted with de-ionized water, de-ionized water + 1 vol.% MCNT additive solution, FC-72 fluids over a mass velocity range of 820-1600 kg m-2 s, inlet temperatures of 15 (8.6), 25 (13.6), 44 (24.6) and 64 °C (36.6 °C) for DI water (FC-72) and heat fluxes up to 800 W cm-2. Flow morphologies, boiling incipience, two-phase heat transfer coefficients and critical heat fluxes are obtained and presented. Both cavities' structured and sputtered diamond ultrathin film surfaces in nanofluid flow boiling in a microchannel are shown to significantly enhance heat transfer through the promotion of bubble ebullitions and to reduce boiling incipience. A significant increase in critical heat flux (CHF) is also found.

Hsieh, Shou-Shing; Lin, Chih-Yi

2010-01-01

214

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

215

Determining the structural phase transition point from the temperature of 40Ca+ Coulomb crystal  

NASA Astrophysics Data System (ADS)

We observed the linear-to-zigzag structural phase transition of a 40Ca+ crystal in a homemade linear Paul trap. The values of the total temperature of the ion crystals during the phase transition are derived using the molecular-dynamics (MD) simulation method. A series of simulations revealed that the ratio of the radial to axial secular frequencies has a dependence on the total temperature that obeys different functional forms for linear and zigzag structures, and the transition point occurs where these functions intersect; thus, the critical value of the ratio of secular frequencies that drives the structure phase transition can be derived.

Chen, Ting; Du, Li-Jun; Song, Hong-Fang; Liu, Pei-Liang; Huang, Yao; Tong, Xin; Guan, Hua; Gao, Ke-Lin

2014-12-01

216

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. PMID:23056912

Grounds, Alex; Still, Richard; Takashina, Kei

2012-01-01

217

The effect of water contamination on the dew-point temperature scale realization with humidity generators  

NASA Astrophysics Data System (ADS)

The purpose of this paper is to study the effect of contaminated water in the context of humidity generators. Investigation of different methods to determine the drop in dew-point temperature due to contamination and experiments on actual contamination rates are reported. Different methods for calculating the dew-point temperature effect from electrical conductivity and density measurements are studied with high-purity water and aqueous solutions of NaCl and LiCl. The outcomes of the calculation methods are compared with the results of direct humidity measurements. The results show that the often applied Raoult's law based calculation method is in good agreement with other methods. For studying actual contamination, water samples were kept in glass, plastic, copper and stainless-steel vessels for up to 13 months to investigate natural ionic and organic contamination in vessels with different wall materials. The amount of ionic contamination was found to be higher in copper and glass vessels than in stainless-steel and plastic vessels. The amount of organic contamination was found to be highest in the plastic vessel. In all the cases, however, the corresponding drop in dew-point temperature due to natural contamination was found to be below 0.1 mK. The largest rate of change of dew-point temperature was 26 µK/month. Thus, if proper cleanness is maintained in a humidity generator the effect of contamination of water in the saturator is insignificant compared with the major uncertainty components even in the most accurate generators today.

Vilbaste, M.; Heinonen, M.; Saks, O.; Leito, I.

2013-08-01

218

Relationship Between Ice Nucleation Temperature Depression and Equilibrium Melting Points Depression of Medaka (Oryzias latipes) Embryos  

NASA Astrophysics Data System (ADS)

We measured the ice nucleation temperature depression , ?Tf , and equilibrium melting points depression, ?Tm, of Medaka (Oryzias latipes) embryos with different cryoprotectant (ethylene glycol, 1.3-propanediol, 1.4-butanediol, glycerol aqueous solutions) treatments. Our obtained results showed the good relationship between the ?Tf ,and ?Tm all samples. In addition the value of ? , which can be obtained from the linear relationship, ?Tf =? ?Tm, were confirmed to show correlation with the value of ? , as obtained by the W/O emulsion method.

Kimizuka, Norihito; Suzuki, Toru

219

Boiling Radial Flow in Fractures of Varying  

E-print Network

SGP-TR-166 Boiling Radial Flow in Fractures of Varying Wall Porosity Robb Allan Barnitt June 2000 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

Stanford University

220

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

221

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

SciTech Connect

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 {sup 20}Ne and {sup 22}Ne. 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 {sup 22}Ne known to contain a N{sub 2} amount of 157?10{sup ?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 N{sub 2} in Ne liquidus point of 8.6(1.9) ?K ppm N{sub 2}{sup ?1}, only slightly different from the literature datum.

Pavese, F.; Steur, P. P. M.; Giraudi, D. [Istituto Nazionale di Ricerca Metrologica (INRIM), Torino (Italy)] [Istituto Nazionale di Ricerca Metrologica (INRIM), Torino (Italy)

2013-09-11

222

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

223

Microscopic explosive boiling induced by a pulsed-laser irradiation  

NASA Astrophysics Data System (ADS)

This paper presents an experimental study of microscopic explosive boiling introduced by a pulsed laser. The violent explosive boiling was observed in the liquid film, and the vapor bubbles together with liquid droplets were expelled from the platinum film. It is found that the apparent bubble nucleation temperature is a strong function of the heating rate. The pressure signal appears as continuous oscillation and is intensified as laser power density increases.

Huai, Xiulan; Wang, Guoxiang; Jin, Renxi; Yin, Tienan; Zou, Yu

2008-11-01

224

Biocomplexity of Frost-Boil Ecosystems  

NSDL National Science Digital Library

The NSF-funded project seeks to understand the complex linkages between biogeochemical cycles, vegetation, disturbance, and climate across the full summer temperature gradient in the Arctic. Researchers examine the complexity associated with self-organization in frost-boil, complexity associated with interactions between biogeochemical cycles, cryoturbation, and vegetation, and biocomplexity across spatial-temporal scales. The web site includes the project proposal, research objectives, preliminary results, maps, photographs, data sets, and publications.

2003-01-01

225

Self-propelled film-boiling liquids  

E-print Network

We report that liquids perform self-propelled motion when they are placed in contact with hot surfaces with asymmetric (ratchet-like) topology. The pumping effect is observed when the liquid is in the film-boiling regime, for many liquids and over a wide temperature range. We propose that liquid motion is driven by a viscous force exerted by vapor flow between the solid and the liquid.

H. Linke; B. J. Aleman; L. D. Melling; M. J. Taormina; M. J. Francis; C. C. Dow-Hygelund; V. Narayanan; R. P. Taylor; A. Stout

2005-12-27

226

Experimental Evidence of the Vapor Recoil Mechanism in the Boiling Crisis  

NASA Astrophysics Data System (ADS)

Boiling crisis experiments are carried out in the vicinity of the liquid-gas critical point of H2. A magnetic gravity compensation setup is used to enable nucleate boiling at near critical pressure. The measurements of the critical heat flux that defines the threshold for the boiling crisis are carried out as a function of the distance from the critical point. The obtained power law behavior and the boiling crisis dynamics agree with the predictions of the vapor recoil mechanism and disagree with the classical vapor column mechanism.

Nikolayev, V. S.; Chatain, D.; Garrabos, Y.; Beysens, D.

2006-11-01

227

Temperature determination of the Si–SiC eutectic fixed point using thermocouples  

NASA Astrophysics Data System (ADS)

The temperature of the Si–SiC eutectic fixed point for use in thermocouple thermometry has been determined. Three Si–SiC cells were fabricated from pure silicon powder within separate graphite crucibles. Each of the three cells was cycled through 17 melt–freeze cycles and subjected to temperatures above 1400?°C for a period of approximately 73?h, and none showed any sign of mechanical failure. The melting transition was measured using three types of thermocouple: one type S, one type B, and two Pt/Pd thermocouples calibrated at the fixed points of Ag, Cu, Fe–C, Co–C, and Pd (only for type B). The transition temperature, measured using the type S and two Pt/Pd thermocouples, was (1410.0 ± 0.8)?°C with k = 2. However, the measurement uncertainty using the type B thermocouple was as large as 1.5?°C (k = 2) due to the inhomogeneity of the thermocouple. The repeatability of the three Si–SiC cells was calculated to be 0.3?°C, and the extremes of the temperature measurement differed by 0.8?°C.

Suherlan; Kim, Yong-Gyoo; Joung, Wukchul; Yang, Inseok

2015-04-01

228

Fundamental Boiling and RP-1 Freezing Experiments  

NASA Technical Reports Server (NTRS)

This paper describes results from experiments performed to help understand certain aspects of the MC-1 engine prestart thermal conditioning procedure. The procedure was constrained by the fact that the engine must chill long enough to get quality LOX at the LOX pump inlet but must be short enough to prevent freezing of RP-1 in the fuel pump. A chill test of an MC-1 LOX impeller was performed in LN2 to obtain data on film boiling, transition boiling and impeller temperature histories. The transition boiling data was important to the chill time so a subsequent experiment was performed chilling simple steel plates in LOX to obtain similar data for LOX. To address the fuel freezing concern, two experiments were performed. First, fuel was frozen in a tray and its physical characteristics were observed and temperatures of the fuel were measured. The result was physical characteristics as a function of temperature. Second was an attempt to measure the frozen thickness of RP-1 on a cold wall submerged in warm RP-1 and to develop a method for calculating that thickness for other conditions.

Goode, Brian; Turner, Larry D. (Technical Monitor)

2001-01-01

229

Steady-state solutions in a three-dimensional nonlinear pool-boiling heat-transfer model  

E-print Network

Steady-state solutions in a three-dimensional nonlinear pool-boiling heat-transfer model Michel. Abstract We consider a relatively simple model for pool-boiling processes. This model in- volves only the temperature distribution within the heater and describes the heat exchange with the boiling medium via

230

Boiling Water at Hot Creek--The Dangerous and Dynamic Thermal Springs in California's Long Valley Caldera  

E-print Network

Boiling Water at Hot Creek--The Dangerous and Dynamic Thermal Springs in California's Long Valley. These springs, however, are unpredictable and can suddenly erupt with violence and at boiling temperature--were cooked instantly. (USGS photo by Chris Farrar.) impressive boiling fountains #12;HotCree k Casa Diablo

Torgersen, Christian

231

Steady-state solutions in a three-dimensional nonlinear pool-boiling heat-transfer model  

E-print Network

Steady-state solutions in a three-dimensional nonlinear pool-boiling heat-transfer model Michel. Abstract We consider a relatively simple model for pool-boiling processes. This model involves only the temperature distribution within the heater and describes the heat exchange with the boiling medium via

232

An onset of nucleate boiling criterion for horizontal flow boiling  

Microsoft Academic Search

A model to predict the onset of nucleate boiling has been successfully developed to differentiate purely convective evaporation from mixed nucleate and convective boiling during evaporation inside a horizontal tube of 14 mm I.D. Based on an extensive database collected for the natural refrigerant ammonia (R-717) over mass velocities from 10 to 140 kg · m ?2· s ?1 ,

Olivier Zürcher; John R. Thome; Daniel Favrat

2000-01-01

233

Complex saddle points and disorder lines in QCD at finite temperature and density  

NASA Astrophysics Data System (ADS)

The properties and consequences of complex saddle points are explored in phenomenological models of QCD at nonzero temperature and density. Such saddle points are a consequence of the sign problem and should be considered in both theoretical calculations and lattice simulations. Although saddle points in finite-density QCD are typically in the complex plane, they are constrained by a symmetry that simplifies analysis. We model the effective potential for Polyakov loops using two different potential terms for confinement effects and consider three different cases for quarks: very heavy quarks, massless quarks without modeling of chiral symmetry breaking effects, and light quarks with both deconfinement and chiral symmetry restoration effects included in a pair of Polyakov-Nambu-Jona Lasinio models. In all cases, we find that a single dominant complex saddle point is required for a consistent description of the model. This saddle point is generally not far from the real axis; the most easily noticed effect is a difference between the Polyakov loop expectation values ?TrFP ? and ?TrFP†? , and that is confined to a small region in the ? -T plane. In all but one case, a disorder line is found in the region of critical and/or crossover behavior. The disorder line marks the boundary between exponential decay and sinusoidally modulated exponential decay of correlation functions. Disorder line effects are potentially observable in both simulation and experiment. Precision simulations of QCD in the ? -T plane have the potential to clearly discriminate between different models of confinement.

Nishimura, Hiromichi; Ogilvie, Michael C.; Pangeni, Kamal

2015-03-01

234

A study of electrowetting-assisted boiling  

E-print Network

The classical theory of boiling heat transfer based on bubble dynamics is explained and includes a full derivation of the Rohsenow boiling correlation. An alternative, more accurate correlation for determining boiling heat ...

Bralower, Harrison L. (Harrison Louis)

2011-01-01

235

Electrical Conductivity of Molten ZnCl2 at Temperature as High as 1421 K  

NASA Astrophysics Data System (ADS)

The electrical conductivity of molten ZnCl2 was measured in a wide temperature range (?T=863 K) to a temperature as high as 1421 K that is 417 degrees above the boiling point of the salt. At the temperature maximum of the own vapor pressure of the salt reached several megapascals.

Salyulev, Alexander B.; Potapov, Alexei M.

2015-02-01

236

Temperature-dependent vibrational relaxation in polyatomic liquids: Picosecond infrared pump-probe experiments  

E-print Network

Temperature-dependent vibrational relaxation in polyatomic liquids: Picosecond infrared pump solutes in two liquids were studied as a function of temperature from the melting points to the boiling,) and chloroform (CHClJ. The temperature dependencies of the lifetimes in Ccl4 are dramatically different from

Fayer, Michael D.

237

Unorthodox bubbles when boiling in cold water  

NASA Astrophysics Data System (ADS)

High-speed movies are taken when bubbles grow at gold surfaces heated spotwise with a near-infrared laser beam heating water below the boiling point (60-70 °C) with heating powers spanning the range from very low to so high that water fails to rewet the surface after bubbles detach. Roughly half the bubbles are conventional: They grow symmetrically through evaporation until buoyancy lifts them away. Others have unorthodox shapes and appear to contribute disproportionately to heat transfer efficiency: mushroom cloud shapes, violently explosive bubbles, and cavitation events, probably stimulated by a combination of superheating, convection, turbulence, and surface dewetting during the initial bubble growth. Moreover, bubbles often follow one another in complex sequences, often beginning with an unorthodox bubble that stirs the water, followed by several conventional bubbles. This large dataset is analyzed and discussed with emphasis on how explosive phenomena such as cavitation induce discrepancies from classical expectations about boiling.

Parker, Scott; Granick, Steve

2014-01-01

238

Unorthodox bubbles when boiling in cold water.  

PubMed

High-speed movies are taken when bubbles grow at gold surfaces heated spotwise with a near-infrared laser beam heating water below the boiling point (60-70?°C) with heating powers spanning the range from very low to so high that water fails to rewet the surface after bubbles detach. Roughly half the bubbles are conventional: They grow symmetrically through evaporation until buoyancy lifts them away. Others have unorthodox shapes and appear to contribute disproportionately to heat transfer efficiency: mushroom cloud shapes, violently explosive bubbles, and cavitation events, probably stimulated by a combination of superheating, convection, turbulence, and surface dewetting during the initial bubble growth. Moreover, bubbles often follow one another in complex sequences, often beginning with an unorthodox bubble that stirs the water, followed by several conventional bubbles. This large dataset is analyzed and discussed with emphasis on how explosive phenomena such as cavitation induce discrepancies from classical expectations about boiling. PMID:24580324

Parker, Scott; Granick, Steve

2014-01-01

239

Computations of Boiling in Microgravity  

NASA Technical Reports Server (NTRS)

The absence (or reduction) of gravity, can lead to major changes in boiling heat transfer. On Earth, convection has a major effect on the heat distribution ahead of an evaporation front, and buoyancy determines the motion of the growing bubbles. In microgravity, convection and buoyancy are absent or greatly reduced and the dynamics of the growing vapor bubbles can change in a fundamental way. In particular, the lack of redistribution of heat can lead to a large superheat and explosive growth of bubbles once they form. While considerable efforts have been devoted to examining boiling experimentally, including the effect of microgravity, theoretical and computational work have been limited. Here, the growth of boiling bubbles is studied by direct numerical simulations where the flow field is fully resolved and the effects of inertia, viscosity, surface deformation, heat conduction and convection, as well as the phase change, are fully accounted for. Boiling involves both fluid flow and heat transfer and thus requires the solution of the Navier-Stokes and the energy equations. The numerical method is based on writing one set of governing transport equations which is valid in both the liquid and vapor phases. This local, single-field formulation incorporates the effect of the interface in the governing equations as source terms acting only at the interface. These sources account for surface tension and latent heat in the equations for conservation of momentum and energy as well as mass transfer across the interface due to phase change. The single-field formulation naturally incorporates the correct mass, momentum and energy balances across the interface. Integration of the conservation equations across the interface directly yields the jump conditions derived in the local instant formulation for two-phase systems. In the numerical implementation, the conservation equations for the whole computational domain (both vapor and liquid) are solved using a stationary grid and the phase boundary is followed by a moving unstructured two-dimensional grid. While two-dimensional simulations have been used for preliminary studies and to examine the resolution requirement, the focus is on fully three-dimensional simulations. The numerical methodology, including the parallelization and grid refinement strategy is discussed, and preliminary results shown. For buoyancy driven flow, the heat transfer is in good agreement with experimental correlations. The changes when gravity is turned off and/or fluid shear is added are discussed, as well as the difference between simulations of a layer freely releasing bubbles versus simulations using only one wavelength initial perturbation. Figure 1 shows the early stages of the formation of a three-dimensional bubble from a thin vapor layer. The boundary conditions are periodic in the x and y direction, the bottom is a hot and the top allows a free outflow. The jagged edge of the surface close to the bottom of the computational domain is due to some of the surface elements being on the other side of the domain and some elements not plotted by our plotting routine. In the second figure, we show the temperature distribution through two perpendicular planes.

Tryggvason, G.; Jacqmin, Dave

2000-01-01

240

S. Wasterlain, D. Candusso, D. Hissel, F. Harel, P. Bergman, P. Menard, M. Anwar (fvrier 2010). Study of temperature, air dew point temperature and reactant flow effects on PEMFC  

E-print Network

). Study of temperature, air dew point temperature and reactant flow effects on PEMFC performances using. Elsevier. Study of temperature, air dew point temperature and reactant flow effects on PEMFC performances A single PEMFC has been operated by varying the assembly temperature, the air dew point temperature

Boyer, Edmond

241

PHYSICAL REVIEW E 89, 013011 (2014) Unorthodox bubbles when boiling in cold water  

E-print Network

-infrared laser beam heating water below the boiling point (60­70 °C) with heating powers spanning the range fromPHYSICAL REVIEW E 89, 013011 (2014) Unorthodox bubbles when boiling in cold water Scott Parker1 about boiling. DOI: 10.1103/PhysRevE.89.013011 PACS number(s): 47.55.dd, 64.60.Q-, 47.80.Jk, 47.55.pb I

Granick, Steve

242

Boiling local heat transfer enhancement in minichannels using nanofluids.  

PubMed

This paper reports an experimental study on nanofluid convective boiling heat transfer in parallel rectangular minichannels of 800 ?m hydraulic diameter. Experiments are conducted with pure water and silver nanoparticles suspended in water base fluid. Two small volume fractions of silver nanoparticles suspended in water are tested: 0.000237% and 0.000475%. The experimental results show that the local heat transfer coefficient, local heat flux, and local wall temperature are affected by silver nanoparticle concentration in water base fluid. In addition, different correlations established for boiling flow heat transfer in minichannels or macrochannels are evaluated. It is found that the correlation of Kandlikar and Balasubramanian is the closest to the water boiling heat transfer results. The boiling local heat transfer enhancement by adding silver nanoparticles in base fluid is not uniform along the channel flow. Better performances and highest effect of nanoparticle concentration on the heat transfer are obtained at the minichannels entrance. PMID:23506445

Chehade, Ali Ahmad; Gualous, Hasna Louahlia; Le Masson, Stephane; Fardoun, Farouk; Besq, Anthony

2013-01-01

243

Boiling local heat transfer enhancement in minichannels using nanofluids  

PubMed Central

This paper reports an experimental study on nanofluid convective boiling heat transfer in parallel rectangular minichannels of 800 ?m hydraulic diameter. Experiments are conducted with pure water and silver nanoparticles suspended in water base fluid. Two small volume fractions of silver nanoparticles suspended in water are tested: 0.000237% and 0.000475%. The experimental results show that the local heat transfer coefficient, local heat flux, and local wall temperature are affected by silver nanoparticle concentration in water base fluid. In addition, different correlations established for boiling flow heat transfer in minichannels or macrochannels are evaluated. It is found that the correlation of Kandlikar and Balasubramanian is the closest to the water boiling heat transfer results. The boiling local heat transfer enhancement by adding silver nanoparticles in base fluid is not uniform along the channel flow. Better performances and highest effect of nanoparticle concentration on the heat transfer are obtained at the minichannels entrance. PMID:23506445

2013-01-01

244

Localized saddle-point search and application to temperature-accelerated dynamics  

NASA Astrophysics Data System (ADS)

We present a method for speeding up temperature-accelerated dynamics (TAD) simulations by carrying out a localized saddle-point (LSAD) search. In this method, instead of using the entire system to determine the energy barriers of activated processes, the calculation is localized by only including a small chunk of atoms around the atoms directly involved in the transition. Using this method, we have obtained N-independent scaling for the computational cost of the saddle-point search as a function of system size N. The error arising from localization is analyzed using a variety of model systems, including a variety of activated processes on Ag(100) and Cu(100) surfaces, as well as multiatom moves in Cu radiation damage and metal heteroepitaxial growth. Our results show significantly improved performance of TAD with the LSAD method, for the case of Ag/Ag(100) annealing and Cu/Cu(100) growth, while maintaining a negligibly small error in energy barriers.

Shim, Yunsic; Callahan, Nathan B.; Amar, Jacques G.

2013-03-01

245

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

246

Main Results of Na-K Alloy Boiling Investigation  

SciTech Connect

Boiling experiments on eutectic sodium-potassium alloy in the model of fast reactor subassembly under conditions of low-velocity circulation carried out at the IPPE call for further investigations into numerical modeling of the process. The paper presents analysis of pin bundle liquid metal boiling, stages of the process, its characteristics (wall temperature, coolant temperature, flow rate. pressure void fraction and others), that allowed the pattern map to be drawn. The problem of conversion of the data gained in Na-K mock-up experiments to in-pile sodium reactor operating conditions is analyzed here, as well as thermodynamic similarity of liquid metal coolants and eutectic Na-K alloy. Data on bundle boiling in Na-K are presented in comparison with those in different liquid metals. Analysis of data on liquid metal heat transfer in cases of pool boiling, boiling in tubes, in slots, and in pin bundles, as well as data on critical heat flux in tubes was performed and discussed in the paper. The relationship for calculation of critical heat flux in liquid metal derived by the authors is presented. Results of numerical modeling of liquid metal boiling heat transfer during accident cooling of reactor core applied to experimental conditions of going from forced to natural circulation are presented, too. (authors)

Sorokin, G.A.; Bogoslovskaya, G.P.; Ivanov, E.F.; Sorokin, A.P. [State Scientific Center of Russian Federation Physics and Power Engineering Institute, 1 Bondarenko Sq., Obninsk, 249033, Kaluga Region (Russian Federation)

2002-07-01

247

Effects of turbulence and secondary flows on subcooled flow boiling  

NASA Astrophysics Data System (ADS)

Experiments are conducted on the influence of turbulence and longitudinal vortices on subcooled flow boiling in a vertical, rectangular channel. Different flow inserts are used to create turbulence and vortices in the channel. Studied boiling regimes range from the onset of nucleate boiling over the critical heat flux up to fully developed film boiling. A wide range of measuring techniques is applied: time averaged particle image velocimetry (PIV) is used in cold flows for the evaluation of the effects the inserts have on the flow, high speed PIV and photography are used to determine the effects on the fluid and vapor movement in boiling experiments. Digital Holographic Interferometry is used for the evaluation of temperature distributions in the boiling flow. Furthermore, optical microprobes are used to obtain pointwise measurements in areas inaccessible to the imaging techniques. The experiments show that the flow inserts can have considerable impact on the heat fluxes and the distribution of vapor and temperature along the channel. All used inserts lead to an increase in critical heat flux, which is more pronounced for stronger turbulence and higher flow rates and fluid subcoolings. The measuring techniques reveal both a better transport of vapor from the heater surface as well as an increase in mixing in the liquid phase with flow inserts.

Bloch, Gregor; Sattelmayer, Thomas

2014-03-01

248

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

PubMed Central

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

249

Pool and flow boiling in variable and microgravity  

NASA Technical Reports Server (NTRS)

As is well known, boiling is an effective mode of heat transfer in that high heat flux levels are possible with relatively small temperature differences. Its optimal application requires that the process be adequately understood. A measure of the understanding of any physical event lies in the ability to predict its behavior in terms of the relevant parameters. Despite many years of research the predictability of boiling is currently possible only for quite specialized circumstances, e.g., the critical heat flux and film boiling for the pool boiling case, and then only with special geometries. Variable gravity down to microgravity provides the opportunity to test this understanding, but possibly more important, by changing the dimensional and time scales involved permits more detailed observations of elements involved in the boiling process, and perhaps discloses phenomena heretofore unknown. The focus here is on nucleate boiling although, as will be demonstrated below, under but certain circumstances in microgravity it can take place concurrently with the dryout process. In the presence of earth gravity or forced convection effects, the latter process is usually referred to as film boiling. However, no vapor film as such forms with pool boiling in microgravity, only dryout. Initial results are presented here for pool boiling in microgravity, and were made possible at such an early date by the availability of the Get-Away-Specials (GAS). Also presented here are some results of ground testing of a flow loop for the study of low velocity boiling, eventually to take place also in microgravity. In the interim, variable buoyancy normal to the heater surface is achieved by rotation of the entire loop relative to earth gravity. Of course, this is at the expense of varying the buoyancy parallel to the heater surface. Two questions which must be resolved early in the study of flow boiling in microgravity are (1) the lower limits of liquid flow velocity where buoyancy effects become significant to the boiling process (2) the effect of lower liquid flow velocities on the Critical Heat Flux when buoyancy is removed. Results of initial efforts in these directions are presented, albeit restricted currently to the ever present earth gravity.

Merte, Herman, Jr.

1994-01-01

250

An apparatus for examining temperature-dependent changes in Raman spectra of crystals near phase-transition points  

Microsoft Academic Search

To elucidate the phase-transition mechanism in a crystal it is necessary to have information on the state in the pretransition region, viz., a narrow temperature range near the transition point in which there are very substantial changes in crystal structure. Apparatus for this purpose should provide highly accurate temperature stabilization and small steps in temperature adjustment. It is usual to

N. V. Sidorov; É. I. Mukhtarov

1982-01-01

251

Isotopic Effects on the Temperature of the Triple Point of Water  

NASA Astrophysics Data System (ADS)

An investigation into the effects of isotopic composition on the triple point temperature of water has been carried out at the National Institute of Metrology (NIM), China, since redefinition of the kelvin with respect to Vienna Standard Mean Ocean Water (V-SMOW) was officially proposed by the Consultative Committee for Thermometry (CCT) in 2005. In this paper, a comparison of four cells with isotopic analyses and relevant results corrected for isotopic composition, employing the isotope correction algorithm recommended by the CCT, is described. The results indicate that, after application of the corrections, the maximum temperature difference between the cells drops from 0.10 mK to 0.02 mK and that these cells are in good agreement within 0.02 mK. Also, temperature deviations arising from isotopic variations fall in the range from -55.9 ?K to + 40.7 ?K. We consider that the distillation temperature and degassing time of the production procedure lead to isotopic variations.

Yan, X. K.; Zhang, J. T.; Wang, Y. L.; Ma, C. F.; Duan, Y. N.

2008-02-01

252

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

253

Evidences of the fractional kinetics in temperature region: Evolution of extreme points in ibuprofen  

NASA Astrophysics Data System (ADS)

Based on a new approach presented in detail in this paper one can find new evidences of existence of the fractional kinetics not only in the frequency range. One can find rather general principles of detection of different collective motions in temperature region. These principles can be expressed in terms of an algorithm (defined in the paper as an approach). This approach includes some steps that help to separate a couple of the neighboring collective motions (expressed in the frequency range as a linear combination of two power-law exponents) from each other and establish the temperature evolution of the extreme point that follows to the generalized Vogel-Fulcher-Tamman (VFT)-equation. This experimentally confirmed fact gives new evidences for supporting of the theory of dielectric relaxation based on the fractional kinetics on the frequency/temperature domain. As an example for verification of this new approach the ibuprofen complex permittivity data measured in the wide frequency/temperature range were chosen. The reason of such selection was the following. It helps to compare the conventional study of this complex substance recently published in [1] and use possibilities of the developed approach that can add some new features to the picture obtained in the frame of the conventional treatment. We suppose that possibilities presented by new approach will be extremely useful for detection of different collective motions in other substances studied by the method of broadband dielectric spectroscopy (BDS).

Nigmatullin, Raoul R.; Brás, Ana R.; Correia, Natália T.

2010-10-01

254

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

255

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

256

Estimating the Contribution of Impurities to the Uncertainty of Metal Fixed-Point Temperatures  

NASA Astrophysics Data System (ADS)

The estimation of the uncertainty component attributable to impurities remains a central and important topic of fixed-point research. Various methods are available for this estimation, depending on the extent of the available information. The sum of individual estimates method has considerable appeal where there is adequate knowledge of the sensitivity coefficients for each of the impurity elements and sufficiently low uncertainty regarding their concentrations. The overall maximum estimate (OME) forsakes the behavior of the individual elements by assuming that the cryoscopic constant adequately represents (or is an upper bound for) the sensitivity coefficients of the individual impurities. Validation of these methods using melting and/or freezing curves is recommended to provide confidence. Recent investigations of indium, tin, and zinc fixed points are reported. Glow discharge mass spectrometry was used to determine the impurity concentrations of the metals used to fill the cells. Melting curves were analyzed to derive an experimental overall impurity concentration (assuming that all impurities have a sensitivity coefficient equivalent to that of the cryoscopic constant). The two values (chemical and experimental) for the overall impurity concentrations were then compared. Based on the data obtained, the pragmatic approach of choosing the larger of the chemical and experimentally derived quantities as the best estimate of the influence of impurities on the temperature of the freezing point is suggested rather than relying solely on the chemical analysis and the OME method to derive the uncertainty component attributable to impurities.

Hill, K. D.

2014-04-01

257

Water loss at normal enamel histological points during air drying at room temperature.  

PubMed

This in vitro study aimed to quantify water loss at histological points in ground sections of normal enamel during air drying at room temperature (25°C) and relative humidity of 50%. From each of 10 ground sections of erupted permanent human normal enamel, three histological points (n = 30) located at 100, 300 and 500 ?m from enamel surface and along a transversal following prisms paths were characterized regarding the mineral, organic and water volumes. Water loss during air drying was from 0 to 48 h. Drying occurred with both falling and constant-drying rates, and drying stabilization times (Teq ) ranged from 0.5 to 11 h with a mean 0.26 (±0.12)% weight loss. In some samples (n = 5; 15 points), Teq increased as a function of the distance from the enamel surface, and drying occurred at an apparent diffusion rate of 3.47 × 10?? cm² s?¹. Our data provide evidence of air drying resulting in air replacing enamel's loosely bound water in prisms sheaths following a unidirectional water diffusion rate of 3.47 × 10?? cm² s?¹ (from the original enamel surface inward), not necessarily resulting in water evaporating directly into air, with important implications for transport processes and optical and mechanical properties. PMID:23557383

De Medeiros, R C G; De Lima, T A S; Gouveia, C R; De Sousa, F B

2013-06-01

258

Film boiling of mercury droplets  

NASA Technical Reports Server (NTRS)

Vaporization times of mercury droplets in Leidenfrost film boiling on a flat horizontal plate are measured in an air atmosphere. Extreme care was used to prevent large amplitude droplet vibrations and surface wetting; therefore, these data can be compared to film boiling theory. Diffusion from the upper surface of the drop appears as a dominant mode of mass transfer from the drop. A closed-form analytical film boiling theory is developed to account for the diffusive evaporation. Reasonable agreement between data and theory is seen.

Baumeister, K. J.; Schoessow, G. J.; Chmielewski, C. E.

1975-01-01

259

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

260

High flux film and transition boiling  

SciTech Connect

This report is a bench-scale experiment on transition boiling. The author gives a detailed description on experimental apparatus and conditions. The visual observed boiling phenomena; nucleate boiling and film boiling, and the effect of heat transfer are also elucidated. 10 refs., 11 figs., 1 tab.

Witte, L.C.

1990-01-01

261

Influence of nanoparticles on boiling heat transfer  

Microsoft Academic Search

Two sets of experiments are performed in this work to reveal the potential effect of nanoparticles on boiling heat transfer: i) pool boiling of nanofluids on two well-defined boiling surfaces and ii) bubble formation in a quiescent pool of nanofluids under adiabatic conditions. Different to the conventional thoughts that the modification of boiling heat transfer is the result of solid

Dongsheng Wen

262

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

263

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

264

Subcooled flow boiling of fluorocarbons  

E-print Network

A study was conducted of heat transfer and hydrodynamic behavior for subcooled flow boiling of Freon-113, one of a group of fluorocarbons suitable for use in cooling of high-power-density electronic components. Problems ...

Murphy, Richard Walter

1971-01-01

265

Removal of Lead(II) from Aqueous Solutions using Pre-boiled and Formaldehyde-Treated Onion Skins as a New Adsorbent  

Microsoft Academic Search

The adsorption characteristics of Pb on pre-boiled treated onion skins (PTOS) and formaldehyde-treated onion skins (FTOS) were evaluated. The effects of Pb initial concentration, agitation rate, solution pH, and temperature on Pb adsorption were investigated in batch systems. Pb adsorption was found to increase with increase in initial concentration. The point of zero net charge (PZC) was 6.53. The optimum

Cafer Saka; Ömer ?ahin; Halil Demir; Mustafa Kahyao?lu

2011-01-01

266

Spin Glass in a Field: A New Zero-Temperature Fixed Point in Finite Dimensions  

NASA Astrophysics Data System (ADS)

By using real-space renormalization group (RG) methods, we show that spin glasses in a field display a new kind of transition in high dimensions. The corresponding critical properties and the spin-glass phase are governed by two nonperturbative zero-temperature fixed points of the RG flow. We compute the critical exponents and discuss the RG flow and its relevance for three-dimensional systems. The new spin-glass phase we discovered has unusual properties, which are intermediate between the ones conjectured by droplet and full replica symmetry-breaking theories. These results provide a new perspective on the long-standing debate about the behavior of spin glasses in a field.

Angelini, Maria Chiara; Biroli, Giulio

2015-03-01

267

Liquid phase stability under an extreme temperature gradient.  

PubMed

Using nonequilibrium molecular dynamics simulations, we subject bulk liquid to a very high-temperature gradient and observe a stable liquid phase with a local temperature well above the boiling point. Also, under this high-temperature gradient, the vapor phase exhibits condensation into a liquid at a temperature higher than the saturation temperature, indicating that the observed liquid stability is not caused by nucleation barrier kinetics. We show that, assuming local thermal equilibrium, the phase change can be understood from the thermodynamic analysis. The observed elevation of the boiling point is associated with the interplay between the "bulk" driving force for the phase change and surface tension of the liquid-vapor interface that suppresses the transformation. This phenomenon is analogous to that observed for liquids in confined geometries. In our study, however, a low-temperature liquid, rather than a solid, confines the high-temperature liquid. PMID:24329454

Liang, Zhi; Sasikumar, Kiran; Keblinski, Pawel

2013-11-27

268

Effects of temperature at constant air dew point on leaf carboxylation efficiency and CO2 compensation point of different leaf types.  

PubMed

The effect of temperature on photosynthesis at constant water-vapor pressure in the air was investigated using two sclerophyll species, Arbutus unedo and Quercus suber, and one mesophytic species, Spinacia oleracea. Photosynthesis and transpiration were measured over a range of temperatures, 20-39° C. The external concentration of CO2 was varied from 340 ?bar to near CO2 compensation. The initial slope (carboxylation efficiency, CE) of the photosynthetic response to intercellular CO2 concentration, the CO2 compensation point (?), and the extrapolated rate of CO2 released into CO2-free air (R i) were calculated. At an external CO2 concentration of 320-340 ?bar CO2, photosynthesis decreased with temperature in all species. The effect of temperature on ? was similar in all species. While CE in S. oleracea changed little with temperature, CE decreased by 50% in Q. suber as temperature increased from 25 to 34° C. Arbutus unedo also exhibited a decrease in CE at higher temperatures but not as marked as Q. suber. The absolut value of R i increased with temperature in S. oleracea, while changing little or decreasing in the sclerophylls. Variations in ? and R i of the sclerophyll species are not consistent with greater increase of respiration with temperature in the light in these species compared with S. oleracea. PMID:24241315

Weber, J A; Tenhunen, J D; Lange, O L

1985-09-01

269

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

270

POINT 2012: ENDF/B-VII.1 Final 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 [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 Data Center, Brookhaven National Laboratory, http://www.nndc.bnl.gov/) and, (2) publicly available computer codes (the current PREPRO codes, available on-line at the Nuclear Data Section, IAEA, Vienna, Austria, http://www-nds.iaea.or.at/ndspub/endf/prepro/) and, (3) My own personal computer located in my home. I have used these in combination to produce the temperature dependent cross sections used in applications and described in this report. I should mention that today anyone with a personal computer can produce these results: by its very nature I consider this data to be born in the public domain.

Cullen, D E

2012-02-26

271

A polymer electrolyte for operation at temperatures up to 200 C  

Microsoft Academic Search

In developing advanced fuel cells and other electrochemical reactors, it is desirable to combine the advantages of solid polymer electrolytes with the enhanced catalytic activity associated with temperatures above 100 C. This will require polymer electrolytes which retain high ionic conductivity at temperatures above the boiling point of water. One possibility is to equilibrate standard perfluorosulfonic acid polymer electrolytes such

R. Savinell; E. Yeager; D. Tryk; U. Landau; J. Wainright; D. Weng; K. Lux; M. Litt; C. Rogers

1994-01-01

272

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

273

Corresponding states correlation for temperature dependent surface tension of normal saturated liquids  

NASA Astrophysics Data System (ADS)

A new simple correlation based on the principle of corresponding state is proposed to estimate the temperature-dependent surface tension of normal saturated liquids. The correlation is a linear one and strongly stands for 41 saturated normal liquids. The new correlation requires only the triple point temperature, triple point surface tension and critical point temperature as input and is able to represent the experimental surface tension data for these 41 saturated normal liquids with a mean absolute average percent deviation of 1.26% in the temperature regions considered. For most substances, the temperature covers the range from the triple temperature to the one beyond the boiling temperature.

Yi, Huili; Tian, Jianxiang

2014-07-01

274

The compensation of natural temperature gradient at the measuring point during the sap flow rate determination in trees  

Microsoft Academic Search

The study summarizes the results of the influence of outer temperature gradient on the accuracy of sap flow rate measurements\\u000a in tree trunks by means of thermic-based methods. Particularly it deals with those methods based on the continual accurate\\u000a measurements of temperature differences between the heated part and the part with natural temperature, at the measuring point.\\u000a The battery of

J. ?ermák; J. Ku?era

1981-01-01

275

A cobalt carbon eutectic fixed point for the calibration of contact thermometers at temperatures above 1100 °C  

Microsoft Academic Search

A vertical cobalt-carbon (Co-C) eutectic fixed point cell was constructed at PTB to demonstrate its use for improvement of the calibration of noble-metal thermocouples at temperatures above 1100 °C. The melting and freezing temperatures of the Co-C eutectic were measured in different high-temperature furnaces at PTB and INMETRO (Brazil) to show its stability by using a Pt\\/Pd thermocouple. The reproducibility

F. Edler; A. C. Baratto

2005-01-01

276

Mechanical behavior of Anvil Points oil shale at elevated temperatures and confining pressures. [Compressive strength, ductility, fractures  

Microsoft Academic Search

Twenty-one constant strain rate compression tests have been performed on 80 ml\\/kg (20 GPT) Anvil Points oil shale at elevated temperatures (50 to 200°C) and confining pressures (0.5 to 40 MPa). The strength of oil shale increases with confining pressure and decreases with temperature. Ductility is greatly enhanced by addition of confining pressure. Elevated temperatures have little influence on ductility

Zeuch

1982-01-01

277

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

278

Construction and in-situ characterisation of high-temperature fixed point cells devoted to industrial applications  

NASA Astrophysics Data System (ADS)

Among the activities of the European Metrology Research Programme (EMRP) project HiTeMS one work package is devoted to the development and testing of industrial solutions for long-standing temperature measurement problems at the highest temperatures. LNE-Cnam, NPL, TUBITAK-UME have worked on the design of high temperature fixed points (HTFP) suitable for in-situ temperature monitoring to be implemented in the facilities of CEA (Commissariat à l'énergie atomique et aux énergies alternatives). Several high temperature fixed point cells were constructed in these three national metrology institutes (NMIs) using a rugged version of cells based on the hybrid design of the laboratory HTFP developed and continuously improved at LNE-Cnam during the last years. The fixed points of interest were Co-C, Ru-C and Re-C corresponding to melting temperatures of 1324 °C, 1953 °C and 2474 °C respectively. The cells were characterised at the NMIs after their construction. Having proved robust enough, they were transported to CEA and tested in an induction furnace and cycled from room temperature to temperatures much above the melting temperatures (> +400 °C) with extremely high heating and cooling rates (up to 10 000 K/h). All the cells withstood the tests and the melting plateaus could be observed in all cases.

Sadli, Mohamed; Bourson, Frédéric; Diril, Ahmet; Journeau, Christophe; Lowe, Dave; Parga, Clemente

2014-08-01

279

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

280

The Boiling eXperiment Facility (BXF) for the Microgravity Science Glovebox (MSG)  

NASA Technical Reports Server (NTRS)

Boiling is an effective means of cooling by removing heat from surfaces through vaporization of a working fluid. It is also affected by both the magnitude and direction of gravity. By conducting pool boiling tests in microgravity, the effect of buoyancy n the overall boiling process and the relative magnitude of other phenomena can be assessed. The Boiling eXperiment Facility (BXF) is being built for the Microgravity Science Glovebox. This facility will conduct two pool boiling studies. The first study the Microheater Array Boiling Experiment (MABE) uses two 96 element microheater arrays, 2.7 mm and 7.0 mm in size, to measure localized hear fluxes while operating at a constant temperature. The other experiment, the Nucleate Pool Boiling eXperiment (NPBX) uses a 85 mm diameter heater wafer that has been "seeded" with five individually-controlled nucleation sites to study bubble nucleation, growth, coalescence and departure. The BXF uses normal-perfluorohexane as the test fluid and will operate between pressures of 60 to 244 Pa. and temperatures of 35 to 60 C. Both sets of experimental heaters are highly instrumented. Pressure and bulk fluid temperature measurements will be made with standard rate video. A high speed video system will be used to visualize the boiling process through the bottom of the MABE heater arrays. The BXF is currently scheduled to fly on Utilization Flight-13A.1 to the ISS with facility integration into the MSG and operation during Increment 15

McQuillen, John; Chao, David; Vergilii, Frank

2006-01-01

281

Nucleate pool boiling heat transfer in aqueous surfactant solutions  

Microsoft Academic Search

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,

Vivek Mahadeorao Wasekar

2001-01-01

282

Pressure drop and heat transfer in inverted film boiling hydrogen  

Microsoft Academic Search

Two-phase boiling hydrogen pressure drop and heat transfer is studied in the context of high velocity upflow in a constant, high heat flux, steady state, internal pipe flow environment. These data were generated by NASA in the early and mid 1960s in support of the manned space flight programs. Measurements taken were local pressure, temperature, and voltage drop. System measurements

James Pasch

2006-01-01

283

Improved Method For Experiments In Vertical-Flow Boiling  

NASA Technical Reports Server (NTRS)

Improved method of experimentation in boiling and adiabatic vertical flows provides for simultaneous determination of two-phase frictional pressure drop and vapor-volume fraction. Gravitational pressure drop determined from precise measurements of temperatures and differential pressures in conjunction with quick closure of valves.

Klausner, J. F.; Chao, B. T.; Soo, S. L.

1993-01-01

284

Research on radiation detectors, boiling transients, and organic lubricants  

NASA Technical Reports Server (NTRS)

The accomplishments of a space projects research facility are presented. The subjects discussed are: (1) a study of radiation resistant semiconductor devices, (2) synthesis of high temperature organic lubricants, (3) departure from phase equilibrium during boiling transients, (4) effects of neutron irradiation on defect state in tungsten, and (5) determination of photon response function of NE-213 liquid scintillation detectors.

1974-01-01

285

Turning point temperature and competition between relativistic and ponderomotive effects in self-focusing of laser beam in plasma  

SciTech Connect

The propagation characters of Gaussian laser beam in collisionless plasma are investigated by considering the ponderomotive and relativistic nonlinearities. The second-order differential equation of dimensionless beam width parameter is solved numerically, taking into account the effect of electron temperature. The results show that the ponderomotive force does not facilitate the relativistic self-focusing in all intensity ranges. In fact, there exists a certain intensity value that, if below this value, the ponderomotive nonlinearity can contribute to the relativistic self-focusing, or obstruct it, if above. It is also indicated that there is a temperature interval in which self-focusing can occur, while the beam diverges outside of this region. In addition, the results represent the existence of a “turning point temperature” in the mentioned interval that the self-focusing has the strongest power. The value of the turning point is dependent on laser intensity in which higher intensities result in higher turning point.

Bokaei, B.; Niknam, A. R. [Laser and Plasma Research Institute, Shahid Beheshti University, G.C., Tehran (Iran, Islamic Republic of)] [Laser and Plasma Research Institute, Shahid Beheshti University, G.C., Tehran (Iran, Islamic Republic of); Jafari Milani, M. R. [Plasma Physics Research School, Tehran (Iran, Islamic Republic of)] [Plasma Physics Research School, Tehran (Iran, Islamic Republic of)

2013-10-15

286

Pool boiling on nano-finned surfaces  

E-print Network

The effect of nano-structured surfaces on pool boiling heat transfer is explored in this study. Experiments are conducted in a cubical test chamber containing fluoroinert coolant (PF5060, Manufacturer: 3M Co.) as the working fluid. Pool boiling...

Sriraman, Sharan Ram

2009-05-15

287

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

Microsoft Academic Search

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°F. Under the present conditions, even 42% of a nondistillable, nondeasphalted residue was recovered from the column at a calculated 1426°F atmospheric equivalent boiling point.

Herbert E. Schwartz; Robert G. Brownlee; Mieczyslaw M. Boduszynski; Fu. Su

1987-01-01

288

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

289

Laboratory study of non-aqueous phase liquid and water co-boiling during thermal treatment  

NASA Astrophysics Data System (ADS)

In situ thermal treatment technologies, such as electrical resistance heating and thermal conductive heating, use subsurface temperature measurements in addition to the analysis of soil and groundwater samples to monitor remediation performance. One potential indication of non-aqueous phase liquid (NAPL) removal is an increase in temperature following observations of a co-boiling plateau, during which subsurface temperatures remain constant as NAPL and water co-boil. However, observed co-boiling temperatures can be affected by the composition of the NAPL and the proximity of the NAPL to the temperature measurement location. Results of laboratory heating experiments using single-component and multi-component NAPLs showed that local-scale temperature measurements can be mistakenly interpreted as an indication of the end of NAPL-water co-boiling, and that significant NAPL saturations (1% to 9%) remain despite observed increases in temperature. Furthermore, co-boiling of multi-component NAPL results in gradually increasing temperature, rather than a co-boiling plateau. Measurements of gas production can serve as a complementary metric for assessing NAPL removal by providing a larger-scale measurement integrated over multiple smaller-scale NAPL locations. Measurements of the composition of the NAPL condensate can provide ISTT operators with information regarding the progress of NAPL removal for multi-component sources.

Zhao, C.; Mumford, K. G.; Kueper, B. H.

2014-08-01

290

Flow regimes and mechanistic modeling of critical heat flux under subcooled flow boiling conditions  

NASA Astrophysics Data System (ADS)

Thermal performance of heat flux controlled boiling heat exchangers are usually limited by the Critical Heat Flux (CHF) above which the heat transfer degrades quickly, possibly leading to heater overheating and destruction. In an effort to better understand the phenomena, a literature review of CHF experimental visualizations under subcooled flow boiling conditions was performed and systematically analyzed. Three major types of CHF flow regimes were identified (bubbly, vapor clot and slug flow regime) and a CHF flow regime map was developed, based on a dimensional analysis of the phenomena and available data. It was found that for similar geometric characteristics and pressure, a Weber number (We)/thermodynamic quality (x) map can be used to predict the CHF flow regime. Based on the experimental observations and the review of the available CHF mechanistic models under subcooled flow boiling conditions, hypothetical CHF mechanisms were selected for each CHF flow regime, all based on a concept of wall dry spot overheating, rewetting prevention and subsequent dry spot spreading. It is postulated that a high local wall superheat occurs locally in a dry area of the heated wall, due to a cyclical event inherent to the considered CHF two-phase flow regime, preventing rewetting (Leidenfrost effect). The selected modeling concept has the potential to span the CHF conditions from highly subcooled bubbly flow to early stage of annular flow. A numerical model using a two-dimensional transient thermal analysis of the heater undergoing nucleation was developed to mechanistically predict CHF in the case of a bubbly flow regime. In this type of CHF two-phase flow regime, the high local wall superheat occurs underneath a nucleating bubble at the time of bubble departure. The model simulates the spatial and temporal heater temperature variations during nucleation at the wall, accounting for the stochastic nature of the boiling phenomena. The model has also the potential to evaluate the post-DNB heater temperature up to the point of heater melting. Validation of the proposed model was performed using detailed measured wall boiling parameters near CHF, thereby bypassing most needed constitutive relations. It was found that under limiting nucleation conditions; a peak wall temperature at the time of bubble departure can be reached at CHF preventing wall cooling by quenching. The simulations show that the resulting dry patch can survive the surrounding quenching event, preventing further nucleation and leading to a fast heater temperature increase. For more practical applications, the model was applied at known CHF conditions in simple geometry coupled with one-dimensional and three-dimensional (CFD) codes. It was found that, in the case where CHF occurs under bubbly flow conditions, the local wall superheat underneath nucleating bubbles is predicted to reach the Leidenfrost temperature. However, a better knowledge of statistical variations in wall boiling parameters would be necessary to correctly capture the CHF trends with mass flux (or Weber number). In addition, consideration of relevant parameter influences on the Leidenfrost temperature and consideration of interfacial microphysics at the wall would allow improved simulation of the wall rewetting prevention and subsequent dry patch spreading.

Le Corre, Jean-Marie

291

Reconstruction of local heat fluxes in pool boiling experiments along the entire boiling curve from high  

E-print Network

Reconstruction of local heat fluxes in pool boiling experiments along the entire boiling curve from conduction problem (IHCP) defined on an irregular three-dimensional (3D) domain in pool boiling experiments heating foil pressed to the bottom of the heater. The heat flux at the inaccessible boiling side

292

Stationary points in activation energy for heat dissipated with a power law temperature-dependent viscoelastoplastic rheology  

NASA Astrophysics Data System (ADS)

We report that there exist a local maximum and minimum in the activation energy Ea describing mechanical heat dissipation of olivine for a given initial temperature and amount of deformation. The stationary point for the minimum dissipation is ~200 kJ/mol lower than that for the maximum. For larger activation energy than the stationary point for maximum dissipation, plastic deformation is sharply weakened and the temperature rise disappears altogether. Higher values of the initial temperature produce a larger local maximum for activation energy. The amount of heat dissipation increases with Ea in a nonlinear manner. Our results have direct ramifications on shear zone, which is governed by the amount of mechanical heat dissipation. We have observed them over a wide range of temperature and deformation boundary conditions. Our two-dimensional model study can provide valuable insight to enable greater predictive capability for the development of geodynamic shear zone in planetary-scale plate tectonics.

So, B.-D.; Yuen, D. A.

2014-07-01

293

Evaluation of Correlations of Flow Boiling Heat Transfer of R22 in Horizontal Channels  

PubMed Central

The calculation of two-phase flow boiling heat transfer of R22 in channels is required in a variety of applications, such as chemical process cooling systems, refrigeration, and air conditioning. A number of correlations for flow boiling heat transfer in channels have been proposed. This work evaluates the existing correlations for flow boiling heat transfer coefficient with 1669 experimental data points of flow boiling heat transfer of R22 collected from 18 published papers. The top two correlations for R22 are those of Liu and Winterton (1991) and Fang (2013), with the mean absolute deviation of 32.7% and 32.8%, respectively. More studies should be carried out to develop better ones. Effects of channel dimension and vapor quality on heat transfer are analyzed, and the results provide valuable information for further research in the correlation of two-phase flow boiling heat transfer of R22 in channels. PMID:23956695

Fang, Xiande; Li, Dingkun

2013-01-01

294

The bi-variate frequency distribution of two concurrent climatic variables: a study of temperature and dew point  

E-print Network

proper fitting of the independent daily mean temperature and dew point values. Advantages of the bi-variate normal distribution include: relative ease of probability calculations, and common attributes with the familiar normal distribution. In fact...-events in equation (3) are different from the h and k standardized values used for evaluation of equation (4). Before application of the bi-variate normal distribution can occur, the assumption of normality must be checked for the daily mean temperature and dew...

Zeitler, Jon William

1991-01-01

295

Preliminary analysis of rapid boiling heat transfer  

Microsoft Academic Search

Rapid boiling is a transient heat transfer phenomenon which occurs when a subcooled or saturated liquid quickly enters a highly metastable state. The preliminary analyses of the rapid boiling heat transfer are carried out in the paper. A physical process model is suggested for describing the rapid boiling heat transfer and a boundary microlayer on the heating surface is put

Jinliang Wang

2000-01-01

296

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

297

Acoustically enhanced boiling heat transfer  

NASA Astrophysics Data System (ADS)

An acoustic field generated by a light-weight, low-power acoustic driver is shown to increase the critical heat flux during pool boiling by about 17%. It does this by facilitating the removal of vapor bubbles from the heated surface and suppressing the instability that leads to the transition to film boiling at the critical heat flux. Bubble removal is enhanced because the acoustic field induces capillary waves on the surface of a vapor bubble that interact with the bubble contact line on the heated surface causing the contact line to contract and detach the bubble from the surface. The acoustic field also produces a radiation pressure that helps to facilitate the bubble detachment process and also suppresses the transition to film boiling. The mechanisms associated with these interactions are explored using three different experimental setups with acoustic forcing: an air bubble on the underside of a horizontal surface, a single vapor bubble on the top side of a horizontal heated surface, and pool boiling from a horizontal heated surface. Measurements of the capillary waves induced on the bubbles, bubble motion, and heat transfer from the heated surface were performed to isolate and identify the dominant forces involved in these acoustically forced motions.

Douglas, Zachary; Boziuk, Thomas R.; Smith, Marc K.; Glezer, Ari

2012-05-01

298

Design, fabrication, packaging and testing of thin film thermocouples for boiling studies  

E-print Network

and fluctuations during boiling. Microfabricated thin film thermocouples were used in this study. The main aim of this study was to develop a repeatable procedure for fabrication of thin film thermocouples and to test them by measuring surface temperatures during...

Sinha, Nipun

2009-06-02

299

One of the limitations of using refrigerant mixtures to achieve capacity modulation is that the range of capacity control and the temperature glide are both functions of the difference  

E-print Network

is that the range of capacity control and the temperature glide are both functions of the difference in boiling. A decision was made to adjust the entering water temperatures to yield equivalent saturation pressures points of the two pure components. For applications in residential heat pumps, the temperature glide

Oak Ridge National Laboratory

300

A universal reduced glass transition temperature for liquids  

NASA Technical Reports Server (NTRS)

Data on the dependence of the glass transition temperature on the molecular structure for low-molecular-weight liquids are analyzed in order to determine whether Boyer's reduced glass transition temperature (1952) is a universal constant as proposed. It is shown that the Boyer ratio varies widely depending on the chemical nature of the molecule. It is pointed out that a characteristic temperature ratio, defined by the ratio of the sum of the melting temperature and the boiling temperature to the sum of the glass transition temperature and the boiling temperature, is a universal constant independent of the molecular structure of the liquid. The average value of the ratio obtained from data for 65 liquids is 1.15.

Fedors, R. F.

1979-01-01

301

Optical temperature point-sensor array for oil and gas down-hole applications  

NASA Astrophysics Data System (ADS)

An armored, 1/4" cabled, temperature sensor array was developed for oil and gas down-hole applications using Bragg gratings written into large diameter, single-mode cane waveguides to provide strain-isolated temperature sensor elements. The temperature sensor array was deployed and evaluated in a test-well. A measured temperature 1-? deviation of better than 0.002°C and an overnight stability range of 0.02°C were demonstrated.

Taverner, D.; Dowd, E.; Grunbeck, J.; Dunphy, J.; Daigle, G.; Jones, R.; Norton, D.; MacDougall, T.

2008-04-01

302

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

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Cargo viscosity and melting point information; measuring...Cargo Information § 153.908 Cargo viscosity and melting point information; measuring...For Category A or B NLS, the cargo's viscosity at 20 °C in mPa.s and, if the...

2012-10-01

303

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

Code of Federal Regulations, 2014 CFR

...2014-10-01 2014-10-01 false Cargo viscosity and melting point information; measuring...Cargo Information § 153.908 Cargo viscosity and melting point information; measuring...For Category A or B NLS, the cargo's viscosity at 20 °C in mPa.s and, if the...

2014-10-01

304

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

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Cargo viscosity and melting point information; measuring...Cargo Information § 153.908 Cargo viscosity and melting point information; measuring...For Category A or B NLS, the cargo's viscosity at 20 °C in mPa.s and, if the...

2013-10-01

305

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

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Cargo viscosity and melting point information; measuring...Cargo Information § 153.908 Cargo viscosity and melting point information; measuring...For Category A or B NLS, the cargo's viscosity at 20 °C in mPa.s and, if the...

2010-10-01

306

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

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Cargo viscosity and melting point information; measuring...Cargo Information § 153.908 Cargo viscosity and melting point information; measuring...For Category A or B NLS, the cargo's viscosity at 20 °C in mPa.s and, if the...

2011-10-01

307

Temperature dependence of the dielectric function and of the parameters of critical point transitions of CdTe  

NASA Astrophysics Data System (ADS)

The dielectric function ? of CdTe is deduced from spectroscopic ellipsometry measurements performed from 0.7 to 5.5 eV. For the first time ? is given for temperatures increasing from 20 to 370 K. ? variations with photon energy are analysed within the standard critical point model (SCP). The variations, with temperature, of the CP parameters are given, discussed and compared with known data. For T < 80 K the dielectric response is completely governed by the exciton near the fundamental gap E0. The contribution of this bound state decreases with T but remains high at room temperature. The transition at E1 is likely to correspond to a quasi bound state interacting with the continuum in the entire temperature range studied. Only one critical point is seen in the vicinity of E2 which behaves like a two dimensional transition at a saddle point. The weak variations of the spin-orbit splittings ?0 and ?1 with temperature are explained as resulting from the choice of lineshapes used to fit experimental data.

Benhlal, J. T.; Strauch, K.; Granger, R.; Triboulet, R.

1999-05-01

308

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

NASA Astrophysics Data System (ADS)

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.; Kimura, N.; Murakami, M.; Yamamoto, I.

2004-06-01

309

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

310

Subcooled flow film boiling across a horizontal cylinder. Part I. Analytical model  

SciTech Connect

An analytical model of stable subcooled flow film boiling on the front of a horizontal cylinder and a model for the wake region downstream of the flow separation points were developed. The flow and temperature fields upstream of the separation points were represented by a 'local-similarity' solution obtained through a rigorous mathematical transformation. The transformed governing equations were solved numerically using a finite-difference scheme. Numerical solutions for the vapor layer thickness, the velocity, and the temperature fields were obtained for both the liquid and vapor layers. The results showed that the liquid boundary layer was thicker than the vapor film. Increases in the liquid subcooling and in the free-stream velocity decreased the vapor layer thickness. The influence of convection in the vapor layer is small yielding a near-linear temperature distribution. A two-dimensional vapor wake model was developed based on mass and energy balances. Numerical solutions, including the vapor layer thickness and the temperature field of the front part and the wake part, were matched at the separation points. The results showed that increases in the liquid subcooling decreased the vapor layer thickness. Heat transfer in the wake region can amount up to 20 percent of the heat transfer in the forward region and should not be neglected especially at high subcooling. 19 refs., 8 figs.

Chou, X.S.; Witte, L.C. (Univ. of Houston, TX (United States))

1995-02-01

311

Microscale Heaters Detailed Boiling Behavior in Normal Gravity and Microgravity  

NASA Technical Reports Server (NTRS)

Pool boiling in microgravity is an area of both scientific and practical interest. Conducting tests in microgravity, as well as lunar and Martian gravity, makes it possible to assess the effect of the density difference between the vapor and liquid phases on the overall boiling process and to assess the relative magnitude of these effects in comparison to other "forces" and phenomena, such as surface tension forces, liquid momentum forces, and microlayer evaporation. The microscale heater developed under a NASA Glenn Research Center grant serves as a unique tool to probe the fundamental mechanisms associated with pool boiling. An experimental package was designed and built by the University of Maryland and tested on the NASA Johnson Space Center KC-135 experimental aircraft and a NASA WFF Terrier Orion Sounding Rocket under NASA Grants NAG3-2228 and NCC3-783. A square array of 96 microscale heaters was constructed and installed into a special boiling chamber. A fluorinert, FC-72, was used as the test fluid. A variety of tests were conducted at different pressures, heater wall temperatures, bulk fluid temperatures, and gravity levels.

McQuillen, John B.

2002-01-01

312

Marangoni Effects in the Boiling of Binary Fluid Mixtures  

NASA Technical Reports Server (NTRS)

Results of very recent experimental studies indicate that during nucleate boiling in some binary mixture, Marangoni effects augment the gravity driven flow of liquid towards the heated surface. With gravity present, it is impossible to separate the two effects. The reduced gravity environment gives an unique opportunity to explore th role of Marangoni effects on the boiling mechanisms free of gravitational body forces that obscure the role of such effects. However, recent experimental results suggest that under reduced gravity conditions, Marangoni effects is the dominant mechanism of vapor-liquid exchange at the surface for some binary mixture. To further explore such effects, experiments have been conducted with water/2-propanol mixtures at three different concentrations under normal gravity with different orientations of the heater surface and under reduce gravity aboard the DC-9 aircraft at NASA Lewis Research Center. The system pressure was sub atmospheric (approx. 8 kP at 1g(n)) and the bulk liquid temperature varied from low subcooling to near saturation. The molar concentrations of 2-propanol tested were 0.015, 0.025, and 0.1. Boiling curves were obtained both for high gravity (approx. 2g(n)) and reduce gravity (approx. 0.01g(n)). For each concentration of 2-propanol, the critical heat flux has been determined in the flight experiments only for reduced gravity conditions. Comparison of boiling curves and CHF obtained under l-g(n) an reduced gravity indicates that boiling mechanism in this mixtures is nearly independent of gravity. The results also indicate that the Marangoni mechanism is strong enough in these mixtures to sustain the boiling under reduced gravity conditions.

Ahmed, Sayeed; Carey, Van P.; Motil, Brian

1996-01-01

313

Loop Heat Pipe Transient Behavior Using Heat Source Temperature for Set Point Control with Thermoelectric Converter on Reservoir  

NASA Technical Reports Server (NTRS)

The LHP operating temperature is governed by the saturation temperature of its reservoir. Controlling the reservoir saturation temperature is commonly done by cold biasing the reservoir and using electrical heaters to provide the required control power. With this method, the loop operating temperature can be controlled within 0.5K or better. However, because the thermal resistance that exists between the heat source and the LHP evaporator, the heat source temperature will vary with its heat output even if the LHP operating temperature is kept constant. Since maintaining a constant heat source temperature is of most interest, a question often raised is whether the heat source temperature can be used for LHP set point temperature control. A test program with a miniature LHP was carried out to investigate the effects on the LHP operation when the control temperature sensor was placed on the heat source instead of the reservoir. In these tests, the LHP reservoir was cold-biased and was heated by a control heater. Test results show that it was feasible to use the heat source temperature for feedback control of the LHP operation. In particular, when a thermoelectric converter was used as the reservoir control heater, the heat source temperature could be maintained within a tight range using a proportional-integral-derivative or on/off control algorithm. Moreover, because the TEC could provide both heating and cooling to the reservoir, temperature oscillations during fast transients such as loop startup could be eliminated or substantially reduced when compared to using an electrical heater as the control heater.

Ku, Jentung; Paiva, Kleber; Mantelli, Marcia

2011-01-01

314

High freezing point fuels used for aviation turbine engines  

NASA Technical Reports Server (NTRS)

Broadened-specification aviation fuels could be produced from a greater fraction of crude source material with improvements in fuel supply and price. These fuels, particularly those with increased final boiling temperatures, would have higher freezing temperatures than current aviation turbine fuels. For the small but significant fraction of commercial flights where low fuel temperatures make higher freezing-point fuel use unacceptable, adaptations to the fuel or fuel system may be made to accommodate this fuel. Several techniques are discussed. Fuel heating is the most promising concept. One simple design uses existing heat rejection from the fuel-lubricating oil cooler, another uses an engine-driven generator for electrical heating.

Friedman, R.

1979-01-01

315

156 IEEE TRANSACTIONS ON COMPONENTS AND PACKAGING TECHNOLOGIES, VOL. 32, NO. 1, MARCH 2009 Pool Boiling Experiments on  

E-print Network

). Index Terms--Carbon nanotube, cooling, critical heat flux (CHF), film boiling, Leidenfrost point heat flux (CHF) by 40%. Increasing the height of the MWCNTs is also found to extend the wall super heat Boiling Experiments on a Nano-Structured Surface Hee Seok Ahn, Vijaykumar Sathyamurthi, and Debjyoti

Banerjee, Debjyoti

316

Computations of Boiling in Microgravity  

NASA Technical Reports Server (NTRS)

The absence (or reduction) of gravity, can lead to major changes in boiling heat transfer. On Earth, convection has a major effect on the heat distribution ahead of an evaporation front, and buoyancy determines the motion of the growing bubbles. In microgravity, convection and buoyancy are absent or greatly reduced and the dynamics of the growing vapor bubbles can change in a fundamental way. In particular, the lack of redistribution of heat can lead to a large superheat and explosive growth of bubbles once they form. While considerable efforts have been devoted to examining boiling experimentally, including the effect of microgravity, theoretical and computational work is limited to very simple models. In this project, the growth of boiling bubbles is studied by direct numerical simulations where the flow field is fully resolved and the effects of inertia, viscosity, surface deformation, heat conduction and convection, as well as the phase change, are fully accounted for. The proposed work is based on previously funded NASA work that allowed us to develop a two-dimensional numerical method for boiling flows and to demonstrate the ability of the method to simulate film boiling. While numerical simulations of multi-fluid flows have been advanced in a major way during the last five years, or so, similar capability for flows with phase change are still in their infancy. Although the feasibility of the proposed approach has been demonstrated, it has yet to be extended and applied to fully three-dimensional simulations. Here, a fully three-dimensional, parallel, grid adaptive code will be developed. The numerical method will be used to study nucleate boiling in microgravity, with particular emphasis on two aspects of the problem: 1) Examination of the growth of bubbles at a wall nucleation site and the instabilities of rapidly growing bubbles. Particular emphasis will be put on accurately capturing the thin wall layer left behind as a bubble expands along a wall, on computing instabilities on bubble surfaces as bubbles grow, and on quantifying the effects of both these phenomena on heat transfer; and 2) Examination of the effect of shear flow on bubble growth and heat transfer.

Tryggvason, Gretar; Jacqmin, David

1999-01-01

317

LANDSCAPE SCALE NON-POINT SOURCE POLLUTION TEMPERATURE ASSESSMENT AND TMDL DEVELOPMENT  

EPA Science Inventory

THIS IS AN ONGOING PROJECT. Elevated river temperature is a significant water quality issue in the Pacific Northwest. For example, over 12,000 miles of perennial streams are designated 303(d) water quality limited due to temperature violation in the State of Oregon. Over t...

318

Boyle temperature as a point of ideal gas in gentile statistics and its economic interpretation  

NASA Astrophysics Data System (ADS)

Boyle temperature is interpreted as the temperature at which the formation of dimers becomes impossible. To Irving Fisher's correspondence principle we assign two more quantities: the number of degrees of freedom, and credit. We determine the danger level of the mass of money M when the mutual trust between economic agents begins to fall.

Maslov, V. P.; Maslova, T. V.

2014-07-01

319

Size-asymmetric primitive model at low temperature: description of ion pairing and location of the critical point.  

PubMed

We argue that Bjerrum's approach to ion pairing is inappropriate for the size-asymmetric primitive model in the neighborhood of its critical point, and propose a new approach based on the Stillinger-Lovett pairing procedure. The new approach recursively scales up the ion size until linear approximations are suitable for analyzing such a model. To locate the critical point, a residual van der Waals interaction between pairs is added, with an energy cutoff adjusted to match the critical temperature of the restricted primitive model. The locations and downward trends of T(c) and rho(c) with asymmetry are found to compare favorably with simulations. PMID:16384317

Zhou, Weimin; Percus, Jerome K

2005-12-01

320

Size-Asymmetric Primitive Model at Low Temperature: Description of Ion Pairing and Location of the Critical Point  

NASA Astrophysics Data System (ADS)

We argue that Bjerrum’s approach to ion pairing is inappropriate for the size-asymmetric primitive model in the neighborhood of its critical point, and propose a new approach based on the Stillinger-Lovett pairing procedure. The new approach recursively scales up the ion size until linear approximations are suitable for analyzing such a model. To locate the critical point, a residual van der Waals interaction between pairs is added, with an energy cutoff adjusted to match the critical temperature of the restricted primitive model. The locations and downward trends of Tc and ?c with asymmetry are found to compare favorably with simulations.

Zhou, Weimin; Percus, Jerome K.

2005-12-01

321

The Physics of Boiling at Burnout  

NASA Technical Reports Server (NTRS)

The basic elements of a new experimental approach for the investigation of burnout in pool boiling are presented. The approach consists of the combined use of ultrathin (nano-scale) heaters and high speed infrared imaging of the heater temperature pattern as a whole, in conjunction with highly detailed control and characterization of heater morphology at the nano and micron scales. It is shown that the burnout phenomenon can be resolved in both space and time. Ultrathin heaters capable of dissipating power levels, at steady-state, of over 1 MW/square m are demonstrated. A separation of scales is identified and it is used to transfer the focus of attention from the complexity of the two-phase mixing layer in the vicinity of the heater to a micron-scaled microlayer and nucleation and associated film-disruption processes within it.

Theofanous, T. G.; Tu, J. P.; Dinh, T. N.; Salmassi, T.; Dinh, A. T.; Gasljevic, K.

2000-01-01

322

A review on saturated boiling of liquids on tube bundles  

NASA Astrophysics Data System (ADS)

A review of recent investigation on boiling of saturated liquids over plain and enhanced tube bundles has been carried out taking the earlier review works as reference point. The experimental observations of various geometry and performance parameters studied by researchers are analyzed keeping current demand of industries in design and development of compact, efficient heat exchanging devices. The study shows that tube spacing plays an important role in determination of compactness of the heat exchanger.

Swain, Abhilas; Das, Mihir Kumar

2014-05-01

323

Modeling acid-gas generation from boiling chloride brines  

PubMed Central

Background This study investigates the generation of HCl and other acid gases from boiling calcium chloride dominated waters at atmospheric pressure, primarily using numerical modeling. The main focus of this investigation relates to the long-term geologic disposal of nuclear waste at Yucca Mountain, Nevada, where pore waters around waste-emplacement tunnels are expected to undergo boiling and evaporative concentration as a result of the heat released by spent nuclear fuel. Processes that are modeled include boiling of highly concentrated solutions, gas transport, and gas condensation accompanied by the dissociation of acid gases, causing low-pH condensate. Results Simple calculations are first carried out to evaluate condensate pH as a function of HCl gas fugacity and condensed water fraction for a vapor equilibrated with saturated calcium chloride brine at 50-150°C and 1 bar. The distillation of a calcium-chloride-dominated brine is then simulated with a reactive transport model using a brine composition representative of partially evaporated calcium-rich pore waters at Yucca Mountain. Results show a significant increase in boiling temperature from evaporative concentration, as well as low pH in condensates, particularly for dynamic systems where partial condensation takes place, which result in enrichment of HCl in condensates. These results are in qualitative agreement with experimental data from other studies. Conclusion The combination of reactive transport with multicomponent brine chemistry to study evaporation, boiling, and the potential for acid gas generation at the proposed Yucca Mountain repository is seen as an improvement relative to previously applied simpler batch evaporation models. This approach allows the evaluation of thermal, hydrological, and chemical (THC) processes in a coupled manner, and modeling of settings much more relevant to actual field conditions than the distillation experiment considered. The actual and modeled distillation experiments do not represent expected conditions in an emplacement drift, but nevertheless illustrate the potential for acid-gas generation at moderate temperatures (<150°C). PMID:19917082

2009-01-01

324

Modeling acid-gas generation from boiling chloride brines  

SciTech Connect

This study investigates the generation of HCl and other acid gases from boiling calcium chloride dominated waters at atmospheric pressure, primarily using numerical modeling. The main focus of this investigation relates to the long-term geologic disposal of nuclear waste at Yucca Mountain, Nevada, where pore waters around waste-emplacement tunnels are expected to undergo boiling and evaporative concentration as a result of the heat released by spent nuclear fuel. Processes that are modeled include boiling of highly concentrated solutions, gas transport, and gas condensation accompanied by the dissociation of acid gases, causing low-pH condensate. Simple calculations are first carried out to evaluate condensate pH as a function of HCl gas fugacity and condensed water fraction for a vapor equilibrated with saturated calcium chloride brine at 50-150 C and 1 bar. The distillation of a calcium-chloride-dominated brine is then simulated with a reactive transport model using a brine composition representative of partially evaporated calcium-rich pore waters at Yucca Mountain. Results show a significant increase in boiling temperature from evaporative concentration, as well as low pH in condensates, particularly for dynamic systems where partial condensation takes place, which result in enrichment of HCl in condensates. These results are in qualitative agreement with experimental data from other studies. The combination of reactive transport with multicomponent brine chemistry to study evaporation, boiling, and the potential for acid gas generation at the proposed Yucca Mountain repository is seen as an improvement relative to previously applied simpler batch evaporation models. This approach allows the evaluation of thermal, hydrological, and chemical (THC) processes in a coupled manner, and modeling of settings much more relevant to actual field conditions than the distillation experiment considered. The actual and modeled distillation experiments do not represent expected conditions in an emplacement drift, but nevertheless illustrate the potential for acid-gas generation at moderate temperatures (<150 C).

Zhang, Guoxiang; Spycher, Nicolas; Sonnenthal, Eric; Steefel, Carl

2009-11-16

325

Heat Transfer Performances of Pool Boiling on Metal-Graphite Composite Surfaces  

NASA Technical Reports Server (NTRS)

Nucleate boiling, especially near the critical heat flux (CHF), can provide excellent economy along with high efficiency of heat transfer. However, the performance of nucleate boiling may deteriorate in a reduced gravity environment and the nucleate boiling usually has a potentially dangerous characteristic in CHF regime. That is, any slight overload can result in burnout of the boiling surface because the heat transfer will suddenly move into the film-boiling regime. Therefore, enhancement of nucleate boiling heat transfer becomes more important in reduced gravity environments. Enhancing nucleate boiling and critical heat flux can be reached using micro-configured metal-graphite composites as the boiling surface. Thermocapillary force induced by temperature difference between the graphite-fiber tips and the metal matrix, which is independent of gravity, will play an important role in bubble detachment. Thus boiling heat transfer performance does not deteriorate in a reduced-gravity environment. Based on the existing experimental data, and a two-tier theoretical model, correlation formulas are derived for nucleate boiling on the copper-graphite and aluminum-graphite composite surfaces, in both the isolated and coalesced bubble regimes. Experimental studies were performed on nucleate pool boiling of pentane on cooper-graphite (Cu-Gr) and aluminum-graphite (Al-Gr) composite surfaces with various fiber volume concentrations for heat fluxes up to 35 W per square centimeter. It is revealed that a significant enhancement in boiling heat transfer performance on the composite surfaces is achieved, due to the presence of micro-graphite fibers embedded in the matrix. The onset of nucleate boiling (the isolated bubble regime) occurs at wall superheat of about 10 C for the Cu-Gr surface and 15 C for the Al-Gr surface, much lower than their respective pure metal surfaces. Transition from an isolated bubble regime to a coalesced bubble regime in boiling occurs at a superheat of about 14 C on Cu-Gr surface and 19 C on Al-Gr surface.

Zhang, Nengli; Chao, David F.; Yang, Wen-Jei

2000-01-01

326

Pervaporation investigation of recovery of volatile compounds from brown crab boiling juice.  

PubMed

Pervaporation has been used to obtain aroma concentrates from brown crab boiling juice. The boiling juice and the obtained permeate have been analysed by Headspace Solid Phase Dynamic Extraction Gas Chromatography/Mass Spectrometry. The effect of feed temperature on the pervaporation performance of the membrane has been analysed. The permeate aroma profile, at 25?? and 40??, was different from that of the boiling juice. Enrichment factors for some of the volatile compounds were much lower than those obtained in model aqueous dilute solutions. Pervaporation performance can be significantly improved by modifying the permeant circuit to include two condensation stages. PMID:23897977

Martínez, Rodrigo; Sanz, M Teresa; Beltrán, Sagrario

2014-10-01

327

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

328

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

SciTech Connect

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

Chen, G. F.; Gong, M. Q.; Wu, J. F.; Zou, X. [Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, P.O. Box 2711, 35, Beijing, 100190 (China); Wang, S. [Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, P.O. Box 2711, 35, Beijing, 100190 (China); University of Chinese Academy of Science, No. 19 YuQuan Road, Beijing, 100049 (China)

2014-01-29

329

Saturated nucleate pool boiling of oxygen under magnetically-enhanced effective gravity  

E-print Network

We investigate the effect of enhancing gravity on saturated nucleate pool boiling of oxygen for effective gravities of 1g, 6.0g, and 16g (g=9.8 m/s^2) at a saturation pressure of 760 torr and for heat fluxes of 10 ~ 3000 W/m^2. The effective gravity on the oxygen is increased by applying a magnetic body force generated by a superconducting solenoid. We measure the heater temperature (expressed as a reduced superheat) as a function of heat flux and fit this data to a piecewise power-law/linear boiling curve. At low heat flux (boiling curve over our applied gravity range.

T. A. Corcovilos; M. E. Turk; D. M. Strayer; N. N. Asplund; N. -C. Yeh

2007-02-01

330

Rotational cars application to simultaneous and multiple-point temperature and concentration determination in a turbulent flow  

NASA Technical Reports Server (NTRS)

Coherent Anti-stokes Raman Scattering (CARS) from the pure rotational Raman lines of N2 is employed to measure the instantaneous rotational temperature of N2 gas at room temperature and below with good spatial resolution. A broad-bandwidth dye laser is used to obtain the entire rotational spectrum from a signal laser pulse; the CARS signal is then dispersed by a spectrograph and recorded on an optical multichannel analyzer. A best-fit temperature is found in several seconds with the aid of a computer for each experimental spectrum by a least squares comparison with calculated spectra. The model used to calculate the theoretical spectra incorporates the temperature and pressure dependence of the pressure-broadened rotational Raman lines, includes the nonresonant background susceptibility, and assumes that the pump laser has a finite linewidth. Temperatures are fit to experimental spectra recorded over the temperature range of 135 to 296K, and over the pressure range of 0.13 to 15.3 atm. In addition to the spatially resolved single point work, we have used multipoint CARS to obtain information from many spatially resolved volume elements along a cylindrical line (0.1 x 0.1 x 2.0 mm). We also obtained qualitative information on the instantaneous species concentration and temperature at 20 spatially resolved volume elements (0.1 x 0.1 x 0.1 mm) along a line.

Snow, J. B.; Murphy, D. V.; Chang, R. K.

1984-01-01

331

A study of forced convection boiling under reduced gravity  

NASA Technical Reports Server (NTRS)

This report presents the results of activities conducted over the period 1/2/85-12/31/90, in which the study of forced convection boiling under reduced gravity was initiated. The study seeks to improve the understanding of the basic processes that constitute forced convection boiling by removing the buoyancy effects which may mask other phenomena. Specific objectives may also be expressed in terms of the following questions: (1) what effects, if any, will the removal of body forces to the lowest possible levels have on the forced convection boiling heat transfer processes in well-defined and meaningful circumstances? (this includes those effects and processes associated with the nucleation or onset of boiling during the transient increase in heater surface temperature, as well as the heat transfer and vapor bubble behaviors with established or steady-state conditions); and (2) if such effects are present, what are the boundaries of the relevant parameters such as heat flux, heater surface superheat, fluid velocity, bulk subcooling, and geometric/orientation relationships within which such effects will be produced?

Merte, Herman, Jr.

1992-01-01

332

Steady State Film Boiling Heat Transfer Simulated With Trace V4.160  

SciTech Connect

This paper presents the results of the assessment and analysis of TRACE v4.160 heat transfer predictions in the post-CHF (critical heat flux) region and discusses the possibilities to improve the TRACE v4.160 code predictions in the film boiling heat transfer when applying different film boiling correlations. For this purpose, the TRACE v4.160-calculated film boiling heat flux and the resulting maximum inner wall temperatures during film boiling in single tubes were compared with experimental data obtained at the Royal Institute of Technology (KTH) in Stockholm, Sweden. The experimental database included measurements for pressures ranging from 30 to 200 bar and coolant mass fluxes from 500 to 3000 kg/m{sup 2}s. It was found that TRACE v4.160 does not produce correct predictions of the film boiling heat flux, and consequently of the maximum inner wall temperature in the test section, under the wide range of conditions documented in the KTH experiments. In particular, it was found that the standard TRACE v4.160 under-predicts the film boiling heat transfer coefficient at low pressure-low mass flux and high pressure-high mass flux conditions. For most of the rest of the investigated range of parameters, TRACE v4.160 over-predicts the film boiling heat transfer coefficient, which can lead to non-conservative predictions in applications to nuclear power plant analyses. Since no satisfactory agreement with the experimental database was obtained with the standard TRACE v4.160 film boiling heat transfer correlations, we have added seven film boiling correlations to TRACE v4.160 in order to investigate the possibility to improve the code predictions for the conditions similar to the KTH tests. The film boiling correlations were selected among the most commonly used film boiling correlations found in the open literature, namely Groeneveld 5.7, Bishop (2 correlations), Tong, Konkov, Miropolskii and Groeneveld-Delorme correlations. The only correlation among the investigated, which resulted in a significant improvement of TRACE predictions, was the Groeneveld 5.7. It was found, that replacing the current film boiling correlation (Dougall-Rohsenow) for the wall-togas heat transfer with Groeneveld 5.7 improves the code predictions for the film boiling heat transfer at high qualities in single tubes in the entire range of pressure and coolant mass flux considered. (authors)

Audrius Jasiulevicius; Rafael Macian-Juan [Paul Scherrer Institute, 5232 Villigen PSI, Schweiz (Switzerland)

2006-07-01

333

Effects of temperature, oxygen concentration, leaf age and seasonal variations on the CO 2 compensation point of Lolium perenne L  

Microsoft Academic Search

Various factors affect the CO2 compensation point of detached leaves of Lolium perenne L. These include oxygen concentration, temperature, leaf age, and season (spring and summer). Analysis of the results using the model of G.D. Farquhar, S. von Caemmerer and J.A. Berry (1980) Planta 149, 78–90, indicates that some of the CO2 evolved by leaves in the light is derived

J. Azcón-Bieto; G. D. Farquhar; A. Caballero

1981-01-01

334

Investigation of the effects of pressure gradient, temperature and wall temperature ratio on the stagnation point heat transfer for circular cylinders and gas turbine vanes  

NASA Technical Reports Server (NTRS)

Low and high pressure shock tubes were designed and constructed for the purpose of obtaining heat transfer data over a temperature range of 390 to 2500 K, pressures of 0.3 to 42 atm, and Mach numbers of 0.15 to 1.5 with and without pressure gradient. A square test section with adjustable top and bottom walls was constructed to produce the favorable and adverse pressure gradient over the flat plate with heat gages. A water cooled gas turbine nozzle cascade which is attached to the high pressure shock tube was obtained to measuse the heat flux over pressure and suction surfaces. Thin-film platinum heat gages with a response time of a few microseconds were developed and used to measure the heat flux for laminar, transition, and turbulent boundary layers. The laminar boundary heat flux on the shock tube wall agreed with Mirel's flat plate theory. Stagnation point heat transfer for circular cylinders at low temperature compared with the theoretical prediction, but for a gas temperature of 922 K the heat fluxes were higher than the predicted values. Preliminary flat plate heat transfer data were measured for laminar, transition, and turbulent boundary layers with and without pressure gradients for free-stream temperatures of 350 to 2575 K and flow Mach numbers of 0.11 to 1.9. The experimental heat flux data were correlated with the laminar and turbulent theories and the agreement was good at low temperatures which was not the case for higher temperatures.

Nagamatsu, H. T.; Duffy, R. E.

1984-01-01

335

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

SciTech Connect

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. [Division of Thermometry and Materials Evaluation, National Institute of Metrology, Beijing, China, 100013 (China)] [Division of Thermometry and Materials Evaluation, National Institute of Metrology, Beijing, China, 100013 (China)

2013-09-11

336

Microscale schlieren visualization of near-bubble mass transport during boiling of 2-propanol/water mixtures in a square capillary  

NASA Astrophysics Data System (ADS)

In this study, we successfully utilize the microscale schlieren method to visualize the microscale mass transport near the vapor-liquid interface during boiling of 2-propanol/water mixtures in a square capillary. Because the variation in the refractive index with composition is much greater than that with temperature, the microscale schlieren method proves to be a powerful tool for investigating the solutocapillary convection without the interference of thermocapillarity. When the difference between the equilibrium vapor and liquid mole fractions is large, we observe high concentration gradients near the vapor-liquid interface due to both mass diffusion and the solutocapillary effects. Although the solutocapillary convection is decidedly affected by the eruptive nature of the boiling process, the near-bubble mass transport still plays a vital role in boiling heat transfer. In a square capillary of d = 900 ?m, mass diffusion dominates and the depletion of 2-propanol near the vapor-liquid interface increases. This leads to an increase in the local bubble point causing the deterioration of heat transfer for 2-propanol/water mixtures. However, in the smaller square capillary of d = 500 ?m, the solutocapillary effect becomes more important. The induced convection near the contact line helps to augment the boiling heat transfer at x = 0.015, despite the fact that mass diffusion tends to cause a higher concentration gradient normal to the bubble front during the boiling process. Herein, we prove that the microscale schlieren method is able to provide valuable insight into the leverage between different mechanisms in heat transfer during the vaporization process of 2-propanol/water mixtures in a square capillary.

Sun, Chen-li; Huang, Chien-Yuan

2014-07-01

337

Temperature-pressure scaling for air-fluidized grains on approaches to Point J  

E-print Network

We present experiments on a monolayer of air-fluidized beads in which a jamming transition is approached by increasing pressure, increasing packing fraction, and decreasing kinetic energy. This is accomplished, along with a noninvasive measurement of pressure, by tilting the system and examining behavior vs depth. We construct an equation of state and analyze relaxation time vs effective temperature. By making time and effective temperature dimensionless using factors of pressure, bead size, and bead mass, we obtain a good collapse of the data but to a functional form that differs from that of thermal hard-sphere systems. The relaxation time appears to diverge only as the effective temperature to pressure ratio goes to zero.

L. J. Daniels; T. K. Haxton; N. Xu; A. J. Liu; D. J. Durian

2011-10-25

338

Length Scale and Gravity Effects on Microgravity Boiling Heat Transfer  

NASA Technical Reports Server (NTRS)

Boiling is a complex phenomenon where hydrodynamics, heat transfer, mass transfer, and interfacial phenomena are tightly interwoven. An understanding of boiling and critical heat flux in microgravity environments is of importance to space based hardware and processes such as heat exchange, cryogenic fuel storage and transportation, electronic cooling, and material processing due to the large amounts of heat that can be removed with relatively little increase in temperature. Although research in this area has been performed in the past four decades, the mechanisms by which heat is removed from surfaces in microgravity are still unclear. In earth gravity, buoyancy is an important parameter that affects boiling heat transfer through the rate at which bubbles are removed from the surface. A simple model describing the bubble departure size based on a quasistatic force balance between buoyancy and surface tension is given by the Fritz [I] relation: Bo(exp 1/2) = 0.0208 theta where Bo is the ratio between buoyancy and surface tension forces. For small, rapidly growing bubbles, inertia associated with the induced liquid motion can also cause bubble departure. In microgravity, the magnitude of effects related to natural convection and buoyancy are small and physical mechanisms normally masked by natural convection in earth gravity such as Marangoni convection can substantially influence the boiling and vapor bubble dynamics. CHF (critical heat transfer) is also substantially affected by microgravity. In 1 g environments, Bo has been used as a correlating parameter for CHF. Zuber's CHF model for an infinite horizontal surface assumes that vapor columns formed by the merger of bubbles become unstable due to a Helmholtz instability blocking the supply of liquid to the surface. The jets are spaced lambda(sub D) apart, where lambda(sub D) = 2pi square root of 3[(sigma)/(g(rho(sub l) - rho(sub v)](exp 1/2) = 2pi square root of 3 L Bo(exp -1/2) = square root of 3 lambda(sub c) and is the wavelength that amplifies most rapidly. The critical wavelength, lambda(sub c), is the wavelength below which a vapor layer underneath a liquid layer is stable. For heaters with Bo smaller than about 3 (heaters smaller than lambda(sub D)), the above model is not applicable, and surface tension effects dominate. Bubble coalescence is thought to be the mechanism for CHF under these conditions. Small Bo can result by decreasing the size of a heater in earth gravity, or by operating a large heater in a lower gravity environment. In the microgravity of space, even large heaters can have low Bo, and models based on Helmholtz instability should not be applicable. The macrolayer model of Haramura and Katto is dimensionally equivalent to Zuber's model and has the same dependence on gravity, so it should not be applicable as well. The goal of this work is to determine how boiling heat transfer mechanisms in a low-g environment are altered from those at higher gravity levels. Boiling data using a microheater array was obtained under gravity environments ranging from 1.8 g to 0.02 g with heater sizes ranging from 2.7 mm to 1 mm. The boiling behavior for 2.7 mm at 0.02 g looked quite similar to boiling on the 1 mm heater at 1 g-the formation of a large primary bubble surrounded by smaller satellite bubbles was observed under both conditions. The similarity suggests that for heaters smaller than some fraction of I(sub c), coalescence and surface tension dominate boiling heat transfer. It also suggests that microgravity boiling can be studied by studying boiling on very small heaters.

Kim, Jungho; McQuillen, John; Balombin, Joe

2002-01-01

339

Efficiency of a solar collector with internal boiling  

SciTech Connect

The behavior of a solar collector with a boiling fluid is analyzed to provide a simple algebraic model for future systems simulations, and to provide guidance for testing. The efficiency equation is developed in a form linear in the difference between inlet and saturation (boiling) temperatures, whereas the expression upon which ASHRAE Standard 109P is based utilizes the difference between inlet and ambient temperatures. The coefficient of the revised linear term is a week function of collector parameters, weather, and subcooling of the working fluid. For a glazed flat-plate collector with metal absorber, the coefficient is effectively constant. Therefore, testing at multiple values of insolation and subcooling, as specified by ASHRAE 109P, should not be necessary for most collectors. The influences of collector properties and operating conditions on efficiency are examined.

Neeper, D.A.

1986-06-01

340

Efficiency of a solar collector with internal boiling  

SciTech Connect

The behavior of a solar collector with a boiling fluid is analyzed to provide a simple algebraic model for future systems simulations, and to provide guidance for testing. The efficiency equation is developed in a form linear in the difference between inlet and saturation (boiling) temperatures, whereas the expression upon which ASHRAE Standard 109P is based utilizes the difference between inlet and ambient temperatures. The coefficient of the revised linear term is a weak function of collector parameters, weather, and subcooling of the working fluid. For a glazed flat-plate collector with metal absorber, the coefficient is effectively constant. Therefore, testing at multiple values of insolation and subcooling, as specified by ASHRAE 109P, should not be necessary for most collectors. The influences of collector properties and operating conditions on efficiency are examined.

Neeper, D.A.

1986-01-01

341

CONVECTIVE HEAT TRANSFER OF BINARY MIXTURES UNDER FLOW BOILING CONDITIONS  

E-print Network

CONVECTIVE HEAT TRANSFER OF BINARY MIXTURES UNDER FLOW BOILING CONDITIONS E. V. McAssey Jr results are presented for the heat transfer coefficient under flow boiling conditions for water-phase non-boiling region through the fully developed subcooled flow boiling region to saturated boiling

Kandlikar, Satish

342

Near-critical fluid boiling  

NASA Astrophysics Data System (ADS)

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 Alice-II instrument, to suppress buoyancy driven flows and gravitational constraints on the liquid-gas interface. We have found that when the system's temperature T is increased at a constant rate past the critical temperature, TC, so that it’s slightly out of equilibrium, several unusual phenomena occur. The gas phase (or low density regions above TC) of the fluid gains a higher temperature than the hot wall and the wetting film on the wall shows large variations in thickness (0.023mm) that forms spatial structures. When the large gas bubble makes contact with a side-wall heating surface, it spreads on the heating surface making a large spreading angle (over 180º), so that the bubble's shape is significantly changed. This last unexpected result is robust, i.e., it is observed either under continuous heating (ramping) or stepping by positive temperature quenches, for various morphologies of the gas bubble and in different fluids. We consider as possible causes of the spreading phenomenon both a surface-tension gradient, due to a temperature gradient along the interface, and the vapor recoil force, due to evaporation. It appears that the vapor recoil force has a more dominant divergence and explains qualitatively the large apparent contact angle far below TC.

Hegseth, John; Nikolayev, Vadim; Garrabos, Yves; Beysens, Daniel

2001-03-01

343

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

344

Protein and energy utilization of boiled rice-legume diets and boiled cereals in growing rats  

Microsoft Academic Search

In growing rats, boiled milled rice-legume diets (2:1 N ratio) had lower energy digestigibility than boiled milled rice and equal if not better true digestibility, biological value, and net protein utilization (NPU). Rice-soybean diets showed better NPU than the other rice-legume diets. Boiled whole-grain corn and sorghum had lower digstible energy and NPU than boiled milled rice. NPU of the

Bjørn O. Eggum; Bienvenido O. Juliano; Maria Gracia; B. Ibabao; Consuelo M. Perez; Virgilio R. Carangal

1987-01-01

345

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 fluorides studied for molten salt fission reactors, has been proposed as a breeder and coolant for fusion applications. The melting points of 2LiF-BeFâ and LiF-BeFâ are 460 deg. C and 363 deg. C, but LiF-BeFâ is rather viscous and has less lithium for breeding. In the Advanced Power Extraction (APEX)

J. M McDonald; R. E. Nygren; T. J. Lutz; T. J Tanaka; M. A. Ulrickson; T. J. Boyle; K. P. Troncosa

2005-01-01

346

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

347

Effect of copper coatings on the crack resistance and temperature microyield point in silicon crystals  

NASA Astrophysics Data System (ADS)

The crack resistance of silicon samples with copper coatings has been studied at room temperature. It has been shown that the deposition of copper coatings on the silicon surface is accompanied by an increase in the crack resistance factor and the formation of regions with dislocations in external load zones, which indicates plastic deformation in the brittle fracture zone.

Makara, V. A.; Steblenko, L. P.; Vesna, G. V.; Naumenko, S. N.; Kurilyuk, A. N.

2015-02-01

348

Transient Boiling of Sodium in a Seven-Pin Bundle under Loss-of-Flow Conditions  

Microsoft Academic Search

Transient sodium boiling experiments have been conducted in an electrically heated 7-pin bundle under loss-of-flow conditions. Each run was made by reducing or stopping the inlet flow at constant heater power.There was no strong effect of temperature ramp rate on the incipient-boiling (IB) wall superheat and the data were scattered with values as high as ~190°C in the range of

Yoshihiro KIKUCHI

1978-01-01

349

Mechanical behavior of Anvil Points oil shale at elevated temperatures and confining pressures. [Compressive strength, ductility, fractures  

SciTech Connect

Twenty-one constant strain rate compression tests have been performed on 80 ml/kg (20 GPT) Anvil Points oil shale at elevated temperatures (50 to 200/sup 0/C) and confining pressures (0.5 to 40 MPa). The strength of oil shale increases with confining pressure and decreases with temperature. Ductility is greatly enhanced by addition of confining pressure. Elevated temperatures have little influence on ductility at low confining pressures; however, at greater confining pressures, temperature exerts a progressively stronger influence on ductility. A purely empirical failure law, incorporating the effects of temperature and confining pressure, has been fitted to the data. The failure law is in good agreement with the results of other studies on the compressive strength of oil shale. All specimens in this study exhibited some fracturing in post-test examination. However, with increasing temperature and confining pressure, plots of compressive differential stress versus axial strain tend to level off after an initial transient period of increasing stress. This indicates that (1) we are approaching the brittle-ductile transition, and (2) time-dependent effects may be important under physical conditions comparable to those of this study.

Zeuch, D.H.

1982-04-01

350

The Neutrino Factory and Muon Collider Collaboration Low-Melting-Temperature Metals  

E-print Network

/gm. Boiling point of bismuth alloys 1600 C. Specific heat 0.13 J/gm. 200 J for T = 1500 C. no boiling: Eddy currents; boiling. 2 #12;The Neutrino Factory and Muon Collider Collaboration Element Atomic Density Melting Boiling Heat Heat of Thermal Number Temp. Temp. Capacity Vapor. Cond. (gm/cm3 ) ( C) ( C

McDonald, Kirk

351

Transient boiling in two-phase helium natural circulation loops  

NASA Astrophysics Data System (ADS)

Two-phase helium natural circulation loops are used for cooling large superconducting magnets, as CMS for LHC. During normal operation or in the case of incidents, transients are exerted on the cooling system. Here a cooling system of this type is studied experimentally. Sudden power changes are operated on a vertical-heated-section natural convection loop, simulating a fast increase of heat deposition on magnet cooling pipes. Mass flow rate, heated section wall temperature and pressure drop variations are measured as a function of time, to assess the time behavior concerning the boiling regime according to the values of power injected on the heated section. The boiling curves and critical heat flux (CHF) values have been obtained in steady state. Temperature evolution has been observed in order to explore the operating ranges where heat transfer is deteriorated. Premature film boiling has been observed during transients on the heated section in some power ranges, even at appreciably lower values than the CHF. A way of attenuating these undesired temperature excursions has been identified through the application of high enough initial heating power.

Furci, H.; Baudouy, B.; Four, A.; Meuris, C.

2014-01-01

352

High-freezing-point fuels used for aviation turbine engines  

NASA Technical Reports Server (NTRS)

Broadened-specification aviation fuels could be produced from a greater fraction of crude source material with improvements in fuel supply and price. These fuels, particularly those with increased final boiling temperatures, would have higher freezing temperatures than current aviation turbine fuels. The higher-freezing-point fuels can be substituted in the majority of present commercial flights, since temperature data indicate that in-flight fuel temperatures are relatively mild. For the small but significant fraction of commercial flights where low fuel temperatures make higher freezing-point fuel use unacceptable, adaptations to the fuel or fuel system may be made to accommodate this fuel. Several techniques are discussed. Fuel heating is the most promising concept. One simple system design uses existing heat rejection from the fuel-lubricating oil cooler, another uses an engine-driven generator for electrical heating. Both systems offer advantages that outweigh the obvious penalties.

Friedman, R.

1979-01-01

353

Native point defects in low-temperature-grown GaAs  

NASA Astrophysics Data System (ADS)

We present structural and electronic data which indicate that the dominant defects in GaAs grown at low temperatures (LT GaAs) by molecular beam epitaxy (MBE) are As antisites (AsGa) and Ga vacancies (VGa), with negligible amounts of As interstitials (Asi). We show that the change of lattice parameter correlates with the concentration of AsGa, and that AsGa alone can account for the lattice expansion. We also show that the total concentration of AsGa has a characteristic second power dependence on the concentration of AsGa in the positive charge state for the material grown at different temperatures. This can be understood provided that VGa defects are the acceptors responsible for the carrier compensation. Our results are consistent with most experimental results and the theoretical expectation from the calculation of defect formation energies. We find that the conclusion may also be true in As-rich bulk GaAs.

Liu, X.; Prasad, A.; Nishio, J.; Weber, E. R.; Liliental-Weber, Z.; Walukiewicz, W.

1995-07-01

354

Weak shock waves in isotropic solids at finite temperatures up to the melting point  

Microsoft Academic Search

Propagation speeds and Rankine–Hugoniot relations for weak shock waves in isotropic solids are derived analytically in order\\u000a to elucidate mechanical and thermal properties of the waves. In the analysis, we adopt a new continuum model for the solids,\\u000a which takes into account explicitly microscopic thermal vibration of the constituent atoms. As the model is valid in a wide\\u000a temperature range

C. Currò; M. Sugiyama; H. Suzumura; G. Valenti

2007-01-01

355

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

356

Boils  

MedlinePLUS

... American Osteopathic College of Dermatology. Community Search Search » Sign In Remember Me Forgot your password? Haven't registered yet? more Calendar 4/23/2015 » 4/26/2015 2015 AOCD Spring Current Concepts in Dermatology Meeting 3/30/2016 » ...

357

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

358

21 CFR 872.6710 - Boiling water sterilizer.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Boiling water sterilizer. 872.6710 Section... Miscellaneous Devices § 872.6710 Boiling water sterilizer. (a) Identification. A boiling water sterilizer is an AC-powered...

2011-04-01

359

21 CFR 872.6710 - Boiling water sterilizer.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 false Boiling water sterilizer. 872.6710 Section... Miscellaneous Devices § 872.6710 Boiling water sterilizer. (a) Identification. A boiling water sterilizer is an AC-powered...

2012-04-01

360

21 CFR 872.6710 - Boiling water sterilizer.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Boiling water sterilizer. 872.6710 Section... Miscellaneous Devices § 872.6710 Boiling water sterilizer. (a) Identification. A boiling water sterilizer is an AC-powered...

2013-04-01

361

21 CFR 872.6710 - Boiling water sterilizer.  

Code of Federal Regulations, 2014 CFR

...2014-04-01 2014-04-01 false Boiling water sterilizer. 872.6710 Section... Miscellaneous Devices § 872.6710 Boiling water sterilizer. (a) Identification. A boiling water sterilizer is an AC-powered...

2014-04-01

362

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

363

Influence of the ambient temperature during heat pipe manufacturing on its function and heat transport ability  

NASA Astrophysics Data System (ADS)

Heat pipe is heat transfer device working at a minimum temperature difference of evaporator and condenser. Operating temperature of the heat pipe determine by properties of the working substance and pressure achieved during production. The contribution is focused on the determining the effect of the initial surrounding temperature where the heat pipe is manufactured and on the obtaining performance characteristics produced heat pipes in dependence of manufacturing temperature. Generally hold, that the boiling point of the working liquid decrease with decreasing ambient pressure. Based on this can be suppose that producing of lower ambient temperature during heat pipe manufacturing, will create the lower pressure, the boiling point of the working fluid will lower too and the heat pipe should be better performance characteristics.

?aja, A.; Nemec, P.; Malcho, M.

2014-03-01

364

A nonparametric temperature controller with nonlinear negative reaction for multi-point rapid MR-guided HIFU ablation.  

PubMed

Magnetic resonance-guided high intensity focused ultrasound (MRgHIFU) is a noninvasive method for thermal ablation, which exploits the capabilities of magnetic resonance imaging (MRI) for excellent visualization of the target and for near real-time thermometry. Oncological quality of ablation may be obtained by volumetric sonication under automatic feedback control of the temperature. For this purpose, a new nonparametric (i.e., model independent) temperature controller, using nonlinear negative reaction, was designed and evaluated for the iterated sonication of a prescribed pattern of foci. The main objective was to achieve the same thermal history at each sonication point during volumetric MRgHIFU. Differently sized linear and circular trajectories were investigated ex vivo and in vivo using a phased-array HIFU transducer. A clinical 3T MRI scanner was used and the temperature elevation was measured in five slices simultaneously with a voxel size of 1 ×1 ×5 mm(3) and temporal resolution of 4 s. In vivo results indicated a similar thermal history of each sonicated focus along the prescribed pattern, that was 17.3 ± 0.5 °C as compared to 16 °C prescribed temperature elevation. The spatio-temporal control of the temperature also enabled meaningful comparison of various sonication patterns in terms of dosimetry and near-field safety. The thermal build-up tended to drift downwards in the HIFU transducer with a circular scan. PMID:24893259

Petrusca, Lorena; Auboiroux, Vincent; Goget, Thomas; Viallon, Magalie; Muller, Arnaud; Gross, Patrick; Becker, Christoph D; Salomir, Rares

2014-06-01

365

Relationships between membrane water molecules and Patman equilibration kinetics at temperatures far above the phosphatidylcholine melting point.  

PubMed

The naphthalene-based fluorescent probes Patman and Laurdan detect bilayer polarity at the level of the phospholipid glycerol backbone. This polarity increases with temperature in the liquid-crystalline phase of phosphatidylcholines and was observed even 90°C above the melting temperature. This study explores mechanisms associated with this phenomenon. Measurements of probe anisotropy and experiments conducted at 1M NaCl or KCl (to reduce water permittivity) revealed that this effect represents interactions of water molecules with the probes without proportional increases in probe mobility. Furthermore, comparison of emission spectra to Monte Carlo simulations indicated that the increased polarity represents elevation in probe access to water molecules rather than increased mobility of relevant bilayer waters. Equilibration of these probes with the membrane involves at least two steps which were distinguished by the membrane microenvironment reported by the probe. The difference in those microenvironments also changed with temperature in the liquid-crystalline phase in that the equilibrium state was less polar than the initial environment detected by Patman at temperatures near the melting point, more polar at higher temperatures, and again less polar as temperature was raised further. Laurdan also displayed this level of complexity during equilibration, although the relationship to temperature differed quantitatively from that experienced by Patman. This kinetic approach provides a novel way to study in molecular detail basic principles of what happens to the membrane environment around an individual amphipathic molecule as it penetrates the bilayer. Moreover, it provides evidence of unexpected and interesting membrane behaviors far from the phase transition. PMID:25559316

Vaughn, Alexandra R; Bell, Thomas A; Gibbons, Elizabeth; Askew, Caitlin; Franchino, Hannabeth; Hirsche, Kelsey; Kemsley, Linea; Melchor, Stephanie; Moulton, Emma; Schwab, Morgan; Nelson, Jennifer; Bell, John D

2015-04-01

366

SWR 1000: The Innovative Boiling Water Reactor  

Microsoft Academic Search

Framatome ANP has developed the boiling water reactor SWR 1000 in close cooperation with German nuclear utilities and with support from various European partners. This advanced reactor design marks a new era in the successful tradition of boiling water reactor technology and, with a gross electric output of between 1290 and 1330 MW, is aimed at assuring competitive power generating

Werner Brettschuh; Greg Hudson

2004-01-01

367

Pool Boiling Experiment Has Five Successful Flights  

NASA Technical Reports Server (NTRS)

The Pool Boiling Experiment (PBE) is designed to improve understanding of the fundamental mechanisms that constitute nucleate pool boiling. Nucleate pool boiling is a process wherein a stagnant pool of liquid is in contact with a surface that can supply heat to the liquid. If the liquid absorbs enough heat, a vapor bubble can be formed. This process occurs when a pot of water boils. On Earth, gravity tends to remove the vapor bubble from the heating surface because it is dominated by buoyant convection. In the orbiting space shuttle, however, buoyant convection has much less of an effect because the forces of gravity are very small. The Pool Boiling Experiment was initiated to provide insight into this nucleate boiling process, which has many earthbound applications in steamgeneration power plants, petroleum plants, and other chemical plants. In addition, by using the test fluid R-113, the Pool Boiling Experiment can provide some basic understanding of the boiling behavior of cryogenic fluids without the large cost of an experiment using an actual cryogen.

Chiaramonte, Fran

1997-01-01

368

Pool Boiling Experiment Has Successful Flights  

NASA Technical Reports Server (NTRS)

The Pool Boiling Experiment (PBE) is designed to improve understanding of the fundamental mechanisms that constitute nucleate pool boiling. Nucleate pool boiling is a process wherein a stagnant pool of liquid is in contact with a surface that can supply heat to the liquid. If the liquid absorbs enough heat, a vapor bubble can be formed. This process occurs when a pot of water boils. On Earth, gravity tends to remove the vapor bubble from the heating surface because it is dominated by buoyant convection. In the orbiting space shuttle, however, buoyant convection has much less of an effect because the forces of gravity are very small. The Pool Boiling Experiment was initiated to provide insight into this nucleate boiling process, which has many Earthbound applications, such as steam-generation power plants, petroleum, and other chemical plants. Also, by using the test fluid R-113, the Pool Boiling Experiment can provide some basic understanding of the boiling behavior of cryogenic fluids without the large cost of an experiment using an actual cryogen.

1996-01-01

369

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

370

Testing for the Gaussian nature of cosmological density perturbations through the three-point temperature correlation function  

NASA Technical Reports Server (NTRS)

One of the crucial aspects of density perturbations that are produced by the standard inflation scenario is that they are Gaussian where seeds produced by topological defects tend to be non-Gaussian. The three-point correlation function of the temperature anisotropy of the cosmic microwave background radiation (CBR) provides a sensitive test of this aspect of the primordial density field. In this paper, this function is calculated in the general context of various allowed non-Gaussian models. It is shown that the Cosmic Background Explorer and the forthcoming South Pole and balloon CBR anisotropy data may be able to provide a crucial test of the Gaussian nature of the perturbations.

Luo, Xiaochun; Schramm, David N.

1993-01-01

371

A New Theory of Nucleate Pool Boiling in Arbitrary Gravity  

NASA Technical Reports Server (NTRS)

Heat transfer rates specific to nucleate pool boiling under various conditions are determined by the dynamics of vapour bubbles that are originated and grow at nucleation sites of a superheated surface. A new dynamic theory of these bubbles has been recently developed on the basis of the thermodynamics of irreversible processes. In contrast to other existing models based on empirically postulated equations for bubble growth and motion, this theory does not contain unwarrantable assumptions, and both the equations are rigorously derived within the framework of a unified approach. The conclusions of the theory are drastically different from those of the conventional models. The bubbles are shown to detach themselves under combined action of buoyancy and a surface tension force that is proven to add to buoyancy in bubble detachment, but not the other way round as is commonly presumed. The theory ensures a sound understanding of a number of so far unexplained phenomena, such as effect caused by gravity level and surface tension on the bubble growth rate and dependence of the bubble characteristics at detachment on the liquid thermophysical parameters and relevant temperature differences. The theoretical predictions are shown to be in a satisfactory qualitative and quantitative agreement with observations. When being applied to heat transfer at nucleate pool boiling, this bubble dynamic theory offers an opportunity to considerably improve the main formulae that are generally used to correlate experimental findings and to design boiling heat removal in various industrial applications. Moreover, the theory makes possible to pose and study a great deal of new problems of essential impact in practice. Two such problems are considered in detail. One problem concerns the development of a principally novel physical model for the first crisis of boiling. This model allows for evaluating critical boiling heat fluxes under various conditions, and in particular at different gravity levels, with a good agreement with experimental evidence. The other problem bears upon equilibrium shapes of a detached bubble near a heated surface in exceedingly low gravity. In low gravity or in weightlessness, the bubble can remain in the close vicinity of the surface for a long time, and its shape is greatly affected by the Marangoni effect due to both temperature and possible surfactant concentration being nonuniform along the interface. The bubble performs at these conditions like a heat pipe, with evaporation at the bubble lower boundary and condensation at its upper boundary, and ultimately ensures a substantial increase in heat removal as compared with that in normal gravity. Some other problems relevant to nucleate pool and forced convection boiling heat transfer are also discussed.

Buyevich, Y. A.; Webbon, Bruce W.

1995-01-01

372

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

SciTech Connect

At the National Metrology Institute of Japan (NMIJ), the triple points of {sup 20}Ne and {sup 22}Ne 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 {sup 20}Ne and {sup 22}Ne 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 T{sub tp} 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 T{sub tp} between pure {sup 20}Ne and pure {sup 22}Ne 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 {sup 20}Ne or {sup 22}Ne 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. [National Metrology Institute of Japan (NMIJ), AIST, Tsukuba (Japan)] [National Metrology Institute of Japan (NMIJ), AIST, Tsukuba (Japan); Nagao, K. [Geochemical Research Center, Graduate School of Science, University of Tokyo, Tokyo (Japan)] [Geochemical Research Center, Graduate School of Science, University of Tokyo, Tokyo (Japan)

2013-09-11

373

A dual-unit pressure sensor for on-chip self-compensation of zero-point temperature drift  

NASA Astrophysics Data System (ADS)

A novel dual-unit piezoresistive pressure sensor, consisting of a sensing unit and a dummy unit, is proposed and developed for on-chip self-compensation for zero-point temperature drift. With an MIS (microholes inter-etch and sealing) process implemented only from the front side of single (1?1?1) silicon wafers, a pressure sensitive unit and another identically structured pressure insensitive dummy unit are compactly integrated on-chip to eliminate unbalance factors induced zero-point temperature-drift by mutual compensation between the two units. Besides, both units are physically suspended from silicon substrate to further suppress packaging-stress induced temperature drift. A simultaneously processes ventilation hole-channel structure is connected with the pressure reference cavity of the dummy unit to make it insensitive to detected pressure. In spite of the additional dummy unit, the sensor chip dimensions are still as small as 1.2?mm × 1.2?mm × 0.4?mm. The proposed dual-unit sensor is fabricated and tested, with the tested sensitivity being 0.104?mV?kPa-1 3.3?V-1, nonlinearity of less than 0.08% · FSO and overall accuracy error of ± 0.18% · FSO. Without using any extra compensation method, the sensor features an ultra-low temperature coefficient of offset (TCO) of 0.002%?°C-1 · FSO that is much better than the performance of conventional pressure sensors. The highly stable and small-sized sensors are promising for low cost production and applications.

Wang, Jiachou; Li, Xinxin

2014-08-01

374

Dirac point and transconductance of top-gated graphene field-effect transistors operating at elevated temperature  

SciTech Connect

Top-gated graphene field-effect transistors (GFETs) have been fabricated using bilayer epitaxial graphene grown on the Si-face of 4H-SiC substrates by thermal decomposition of silicon carbide in high vacuum. Graphene films were characterized by Raman spectroscopy, Atomic Force Microscopy, Scanning Tunnelling Microscopy, and Hall measurements to estimate graphene thickness, morphology, and charge transport properties. A 27?nm thick Al{sub 2}O{sub 3} gate dielectric was grown by atomic layer deposition with an e-beam evaporated Al seed layer. Electrical characterization of the GFETs has been performed at operating temperatures up to 100?°C limited by deterioration of the gate dielectric performance at higher temperatures. Devices displayed stable operation with the gate oxide dielectric strength exceeding 4.5 MV/cm at 100?°C. Significant shifting of the charge neutrality point and an increase of the peak transconductance were observed in the GFETs as the operating temperature was elevated from room temperature to 100?°C.

Hopf, T.; Vassilevski, K. V., E-mail: k.vasilevskiy@ncl.ac.uk; Escobedo-Cousin, E.; King, P. J.; Wright, N. G.; O'Neill, A. G.; Horsfall, A. B.; Goss, J. P. [School of Electrical and Electronic Engineering, Newcastle University, Newcastle upon Tyne NE1 7RU (United Kingdom); Wells, G. H.; Hunt, M. R. C. [Department of Physics, Durham University, Durham DH1 3LE (United Kingdom)

2014-10-21

375

Photonically enhanced flow boiling in a channel coated with carbon nanotubes  

NASA Astrophysics Data System (ADS)

High heat dissipation rates are enabled by multi-phase cooling schemes owing to latent heat uptake. We demonstrate enhanced flow boiling from a carbon nanotube (CNT)-coated copper surface exposed to low-intensity ultraviolet (UV)-visible excitation. Compared to non-illuminated results, the average boiling incipience temperature decreased by 4.6 °C and heat transfer coefficients improved by 41.5% with light exposure. These improved results are attributed to augmented hydrophilicity upon exposure to UV light and possible nanoscale opto-thermal effects, and suggest opportunities for active temperature control of temperature-sensitive devices.

Kousalya, Arun S.; Hunter, Chad N.; Putnam, Shawn A.; Miller, Timothy; Fisher, Timothy S.

2012-02-01

376

Development of a general purpose subgrid wall boiling model from improved physical understanding for use in computational fluid dynamics  

E-print Network

Advanced modeling capabilities were developed for application to subcooled flow boiling through this work. The target was to introduce, and demonstrate, all necessary mechanisms required to accurately predict the temperature ...

Gilman, Lindsey Anne

2014-01-01

377

Film boiling on the inside of vertical tubes with upward flow of the fluid at low qualities  

E-print Network

Flow regimes, local heat transfer coefficients, and temperature distributions along the wall have been studied for film boiling inside a vertical tube with upward flow of a saturated liquid. The area of interest has been ...

Dougall, R. S.

1963-01-01

378

The high temperature three point bend testing of proton irradiated 316L stainless steel and Mod 9Cr 1Mo  

NASA Astrophysics Data System (ADS)

The predicted operating conditions for a lead-bismuth eutectic target to be used in an accelerator driven system for the Advanced Fuel Cycle Initiative span a temperature range of 300-600 °C while being irradiated by a high energy (˜600 MeV) proton beam. Such spallation conditions lead to high displacement rates coupled with high accumulation rates of helium and hydrogen up to 150 appm/dpa. Some candidate materials for these applications include Mod9Cr-1Mo and 316L stainless steel. To investigate the effect of irradiation on these materials, the mechanical properties are being measured through three point bend testing on Mod 9Cr-1Mo and 316L at 25, 250, 350 and 500 °C after irradiation in a high energy proton beam (500-800 MeV) to a dose of 9.8 dpa at temperatures from 200 to 320 °C. By comparing measurements made in bending to tensile measurements measured on identically irradiated materials, a measurement of 0.2% offset yield stress was obtained from 0.05% offset yield stress measured in three point bend testing. Yield stress increased by more than a factor of two after irradiation to 9.8 dpa. Observation of the outer fiber surface of 316L showed very localized deformation when tested after irradiation at 70 °C and deformation on multiple slip systems when tested after irradiation at 250-320 °C.

Maloy, Stuart A.; Zubelewicz, A.; Romero, T.; James, M. R.; Sommer, W. F.; Dai, Y.

2005-08-01

379

Acoustically Enhanced Boiling Heat Transfer  

E-print Network

An acoustic field is used to increase the critical heat flux (CHF) of a flat-boiling-heat-transfer surface. The increase is a result of the acoustic effects on the vapor bubbles. Experiments are performed to explore the effects of an acoustic field on vapor bubbles in the vicinity of a rigid-heated wall. Work includes the construction of a novel heater used to produce a single vapor bubble of a prescribed size and at a prescribed location on a flatboiling surface for better study of an individual vapor bubble's reaction to the acoustic field. Work also includes application of the results from the single-bubble heater to a calibrated-copper heater used for quantifying the improvements in CHF.

Z. W. Douglas; M. K. Smith; A. Glezer

2008-01-07

380

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

381

Enhanced Heat Rejection of Microscale Geometries in Convective Flow Boiling Evaporators  

NASA Astrophysics Data System (ADS)

Four surfaces have been designed, fabricated and tested under convective flow boiling (CFB) conditions in an open loop configuration. They contain features in the 10 micron range and were tested with flow velocities under 3 mm/s. To accomplish these flow rates, this work utilizes a constant pressure potential driving flow, instead of the constant flow rate imposed with a syringe pump. This limited device flooding. The evaporation surfaces were tested to the point of dry-out at three different pressure potentials: 150, 650, and 1150 Pa, across a range of powers from 25 W/cm2 to 50 W/cm2. Temperature data was collected from an IR Camera and showed that fluctuations in the wall temperatures exceed 5 °C in more than 50% of the tests and reached differences as high as 23 °C. The wall temperature instabilities in CFB indicate that one temperature may be inaccurate and that by including time as a variable a better understanding of the behaviour at this scale may be revealed.

Safford Smith, L. M.; Connacher, W. J.; Cheng, J. C.; Pisano, A. P.

2013-12-01

382

Final report for the APMP.T-K4: Comparison of realizations of aluminium freezing-point temperatures  

NASA Astrophysics Data System (ADS)

The comparison APMP.T-K4 is the regional extension of the CCT-K4: an intercomparison of the realizations of the freezing-points of Al (660.323 °C) and Ag (961.78 °C). The comparison was organized in two loops and four sub-loops with high temperature standard platinum resistance thermometers (HTSPRTs) as transfer thermometers in the freezing-point comparisons. The comparison involved eight APMP NMIs (KRISS, NMIJ, SCL, NMC, CMS, NIMT, SIRIM, NPL), and KRISS and NMIJ acted as linking laboratories to the CCT-K4. The transfer HTSPRTs showed a strong drift during the transportation between the NMIs. In the case of the Ag freezing-point comparison, the comparison results were scattered much more than expected. In the APMP meeting held in 2009, the participants agreed that the Ag comparison results would be omitted in the report. It revealed that the measurement results at the Al freezing-point of participants were in agreement with the key comparison reference value of the CCT-K4 within 4 mK except for one laboratory. Details of the comparison results, the uncertainty evaluation and the drift of the HTSPRTs are described in this report. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCT, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Gam, K. S.; Joung, W.; Yamazawa, K.; Cheung, C. P.; Y Kho, H.; Wang, L.; Tsai, S. F.; Norranim, U.; Hafidzah, O.; Gupta, J. K.

2013-01-01

383

Development, solar test, and evaluation of a high-temperature air receiver for point-focusing parabolic dish applications  

SciTech Connect

A high temperature solar receiver was fabricated and tested in excess of 1370 C on an 11-meter-diameter test bed concentrator at the Jet Propulsion Laboratory Parabolic Dish Test Site, Edwards, California. The 60-kilowatt thermal receiver design utilizes state-of-the-art silicon carbide honeycomb matrix panels to receive and transfer the solar energy and mullite elements for thermal buffer storage. Solar tests were conducted with indicated air exit temperatures ranging from 885 C (1625 F) to 1427 C (2600 F), mass flow rates of 75 to 105 g/sec (0.16 to 0.23 lbm/sec), and pressures up to 265 kPa absolute (38.4 psia). Estimates of efficiency are 59.7% at 1120 C (2048 F) to 80.6% at 885 C (1625 F) when aperture spillage losses are considered separately. Results are presented which demonstrate the feasibility of this innovative receiver concept for point-focusing parabolic dish applications over a wide temperature range.

Hanseth, E.J.

1981-01-01

384

Development, solar test, and evaluation of a high-temperature air receiver for point-focusing parabolic dish applications  

NASA Astrophysics Data System (ADS)

A high temperature solar receiver was fabricated and tested in excess of 1370 C on an 11-meter-diameter test bed concentrator at the Jet Propulsion Laboratory Parabolic Dish Test Site, Edwards, California. The 60-kilowatt thermal receiver design utilizes state-of-the-art silicon carbide honeycomb matrix panels to receive and transfer the solar energy and mullite elements for thermal buffer storage. Solar tests were conducted with indicated air exit temperatures ranging from 885 C (1625 F) to 1427 C (2600 F), mass flow rates of 75 to 105 g/sec (0.16 to 0.23 lbm/sec), and pressures up to 265 kPa absolute (38.4 psia). Estimates of efficiency are 59.7% at 1120 C (2048 F) to 80.6% at 885 C (1625 F) when aperture spillage losses are considered separately. Results are presented which demonstrate the feasibility of this innovative receiver concept for point-focusing parabolic dish applications over a wide temperature range.

Hanseth, E. J.

1981-12-01

385

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

386

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

387

Folding and Unfolding of an Elastinlike Oligopeptide: ``Inverse Temperature Transition,'' Reentrance, and Hydrogen-Bond Dynamics  

NASA Astrophysics Data System (ADS)

The temperature-dependent behavior of a solvated oligopeptide, GVG(VPGVG), is investigated. Spectroscopic measurements, thermodynamic measurements, and molecular dynamics simulations find that this elastinlike octapeptide behaves as a two-state system that undergoes an “inverse temperature” folding transition and reentrant unfolding close to the boiling point of water. A molecular picture of these processes is presented, emphasizing changes in the dynamics of hydrogen bonding at the protein/water interface and peptide backbone librational entropy.

Schreiner, Eduard; Nicolini, Chiara; Ludolph, Björn; Ravindra, Revanur; Otte, Nikolaj; Kohlmeyer, Axel; Rousseau, Roger; Winter, Roland; Marx, Dominik

2004-04-01

388

A Study of Nucleate Boiling with Forced Convection in Microgravity  

NASA Technical Reports Server (NTRS)

Boiling is a rather imprecise term applied to the process of evaporation in which the rate of liquid-vapor phase change is large. In seeking to determine the role and significance of body forces on the process, of which buoyancy or gravity is just one agent, it becomes necessary to define the term more precisely. It is generally characterized by the formation and growth of individual vapor bubbles arising from heat transfer to the liquid, either at a solid/liquid or liquid/liquid interface, or volumetrically. The terms 'bubble' boiling and 'nucleate' boiling are frequently used, in recognition of the interactions of surface tension and other forces in producing discrete bubbles at distinctive locations (although not always). Primary considerations are that evaporation can occur only at existing liquid-vapor interfaces, so that attention must be given to the formation of an interface (the nucleation process), and that the latent heat for this evaporation can come only from the superheated liquid, so that attention must also be given to the temperature distributions in the liquid.

Merte, Herman, Jr.

1996-01-01

389

On the Boiling Points of the Alkyl Halides.  

ERIC Educational Resources Information Center

Discusses the variety of explanations in organic chemistry textbooks of a physical property of organic compounds. Focuses on those concepts explaining attractive forces between molecules. Concludes that induction interactions play a major role in alkyl halides and other polar organic molecules and should be given wider exposure in chemistry texts.…

Correia, John

1988-01-01

390

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.

391

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

392

Enhancement in NGL production and improvement in water dew point temperature by optimization of slug catchers’ pressures in water dew point adjustment unit  

Microsoft Academic Search

The water dew point adjustment is one of the most important processes in all gas refineries which reduces the water content of gas to some allowable limit and separates the heavy hydrocarbons from gas. In Sarkhun gas refinery, natural gas dehydration and hydrocarbon dew point adjustment are performed by cooling method. Diethylene glycol (DEG) is injected to gas–gas heat exchanger

M. R. Rahimpour; M. Seifi; K. Paymooni; A. Shariati; S. Raeissi

2011-01-01

393

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

394

The Isolated Bubble Regime in Pool Nucleate Boiling  

NASA Technical Reports Server (NTRS)

We consider an isolated bubble boiling regime in which vapour bubbles are intermittently produced at a prearranged set of nucleation site on an upward facing overheated wall plane. In this boiling regime, the bubbles depart from the wall and move as separate entities. Except in the matter of rise velocity, the bubbles do not interfere and are independent of one another. However, the rise velocity is dependent on bubble volume concentration in the bulk. Heat transfer properties specific to this regime cannot be described without bubble detachment size, and we apply our previously developed dynamic theory of vapour bubble growth and detachment to determine this size. Bubble growth is presumed to be thermally controlled. Two limiting cases of bubble evolution are considered: the one in which buoyancy prevails in promoting bubble detachment and the one in which surface tension prevails. We prove termination of the isolated regime of pool nucleate boiling to result from one of the four possible causes, depending on relevant parameters values. The first cause consists in the fact that the upward flow of rising bubbles hampers the downward liquid flow, and under certain conditions, prevents the liquid from coming to the wall in an amount that would be sufficient to compensate for vapour removal from the wall. The second cause is due to the lateral coalescence of growing bubbles that are attached to their corresponding nucleation sites, with ensuing generation of larger bubbles and extended vapour patches near the wall. The other two causes involve longitudinal coalescence either 1) immediately in the wall vicinity, accompanied by the establishment of the multiple bubble boiling regime, or 2) in the bulk, with the formation of vapour columns. The longitudinal coalescence in the bulk is shown to be the most important cause. The critical wall temperature and the heat flux density associated with isolated bubble regime termination are found to be functions of the physical and operating parameters and are discussed in detail.

Buyevich, Y. A.; Webbon, Bruce W.; Callaway, Robert (Technical Monitor)

1995-01-01

395

Design, Construction, and Qualification of a Microscale Heater Array for Use in Boiling Heat Transfer  

NASA Technical Reports Server (NTRS)

Boiling heat transfer is an efficient means of heat transfer because a large amount of heat can be removed from a surface using a relatively small temperature difference between the surface and the bulk liquid. However, the mechanisms that govern boiling heat transfer are not well understood. Measurements of wall temperature and heat flux near the wall would add to the database of knowledge which is necessary to understand the mechanisms of nucleate boiling. A heater array has been developed which contains 96 heater elements within a 2.5 mm square area. The temperature of each heater element is held constant by an electronic control system similar to a hot-wire anemometer. The voltage that is being applied to each heater element can be measured and digitized using a high-speed A/D converter, and this digital information can be compiled into a series of heat-flux maps. Information for up to 10,000 heat flux maps can be obtained each second. The heater control system, the A/D system and the heater array construction are described in detail. Results are presented which show that this is an effective method of measuring the local heat flux during nucleate and transition boiling. Heat flux maps are obtained for pool boiling in FC-72 on a horizontal surface. Local heat flux variations are shown to be three to six times larger than variations in the spatially averaged heat flux.

Rule, T. D.; Kim, J.; Kalkur, T. S.

1998-01-01

396

Nucleate boiling bubble growth and departure  

E-print Network

The vapor bubble formation on the heating surface during pool boiling has been studied experimentally. Experiments were made at the atmospheric pressure 28 psi and 40 psi, using degassed distilled water and ethanol. The ...

Staniszewski, Bogumil E.

1959-01-01

397

Pool boiling heat transfer characteristics of nanofluids  

E-print Network

Nanofluids are engineered colloidal suspensions of nanoparticles in water, and exhibit a very significant enhancement (up to 200%) of the boiling Critical Heat Flux (CHF) at modest nanoparticle concentrations (50.1% by ...

Kim, Sung Joong, Ph. D. Massachusetts Institute of Technology

2007-01-01

398

Boiling heat transfer in a vertical microchannel: Local estimation during flow boiling with a non intrusive method  

E-print Network

Boiling heat transfer in a vertical microchannel: Local estimation during flow boiling with a non the results of experimental and numerical studies concerning boiling heat transfer inside vertical of boiling flows in microscale's geometry, it is vital to quantify these transfers. To achieve this goal

399

Indo-Pacific Warm Pool Area Expansion, Modoki Activity, and Tropical Cold-Point Tropopause Temperature Variations  

PubMed Central

The tropical cold-point tropopause temperature (CPTT), a potentially important indicator of global climate change, is of particular importance for understanding changes in stratospheric water vapor levels. Since the 1980s, the tropical CPTT has shown not only interannual variations, but also a decreasing trend. However, the factors controlling the variations in the tropical CPTT since the 1980s remain elusive. The present study reveals that the continuous expansion of the area of the Indo-Pacific warm pool (IPWP) since the 1980s represents an increase in the total heat energy of the IPWP available to heat the tropospheric air, which is likely to expand as a result. This process lifts the tropical cold-point tropopause height (CPTH) and leads to the observed long-term cooling trend of the tropical CPTT. In addition, our analysis shows that Modoki activity is an important factor in modulating the interannual variations of the tropical CPTT through significant effects on overshooting convection. PMID:24686481

Xie, Fei; Li, Jianping; Tian, Wenshou; Li, Yanjie; Feng, Juan

2014-01-01

400

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

401

Temperature Differences in the Cepheid Instability Strip Require Differences in the Period-Luminosity Relation in Slope and Zero Point  

NASA Astrophysics Data System (ADS)

A graphical and an algebraic demonstration is made to show why the slope and zero point of the Cepheid period-luminosity (P-L) relation is rigidly coupled with the slope and zero point of the Cepheid instability strip in the HR diagram. In this way it is shown why it is logically inconsistent to adopt a fixed P-L slope for all galaxies if the intrinsic color-period relations differ in slope for some of them. The graphical demonstration of this inconsistency uses an arbitrary (toy) ridgeline in the instability strip, while the algebraic demonstration uses the pulsation equation into which the observed P-L relations for the Galaxy and the LMC are put to predict the temperature zero points and slopes of the instability strips. Agreement between the predicted and the observed slopes in the instability strips argue that the observed P-L differences between the Galaxy and LMC are real. The direct evidence for different P-L slopes in different galaxies is displayed by comparing the Cepheid data in the Galaxy, the combined data in NGC 3351 and NGC 4321, in M31, LMC, SMC, IC 1613, NGC 3109, and in Sextans A+B. The P-L slopes for the Galaxy, NGC 3351, NGC 4321, and M31 are nearly identical and are the steepest in the sample. The P-L slopes decrease monotonically with metallicity in the order listed, showing that the P-L relation is not the same in different galaxies, complicating their use in calibrating the extragalactic distance scale.

Sandage, Allan; Tammann, G. A.

2008-10-01

402

Characteristics of Pool Boiling on Graphite-Copper Composite Surfaces  

NASA Technical Reports Server (NTRS)

Nucleate pool boiling performance of different liquids on graphite-copper composite (Gr-Cu) surfaces has been experimentally studied and modeled. Both highly wetting fluids, such as freon-113 and pentane, and a moderately wetting fluid (water) were tested on the Gr-Cu surfaces with different graphite-fiber volume fractions to reveal the enhancement effects of the composite surfaces on the nucleate pool boiling. Results of the experiments show that the graphite-fiber volume fraction has an optimum value. The Gr-Cu composite surface with 25 percent graphite-fiber volume (f=0.25) has a maximum enhancement effect on the nucleate boiling heat transfer comparing to the pure copper surface. For the highly wetting fluid, the nucleate boiling heat transfer is generally enhanced on the Gr- Cu composite surfaces by 3 to 6 times shown. In the low heat flux region, the enhancement is over 6 times, but in the high heat flux region, the enhancement is reduced to about 40%. For the moderately wetting fluid (water), stronger enhancement of nucleate boiling heat transfer is achieved on the composite surface. It shown the experimental results in which one observes the nucleate boiling heat transfer enhancement of 5 to 10 times in the low heat flux region and an enhancement of 3 to 5 times in the high heat flux region. Photographs of bubble departure during the initial stage of nucleate boiling indicate that the bubbles detached from the composite surface are much smaller in diameter than those detached from the pure copper surface. Typical photographs are presented.It shows that the bubbles departed from the composite surface have diameters of only O(0.1) mm, while those departed from the pure copper surface have diameters of O(1) mm. It is also found that the bubbles depart from the composite surface at a much higher frequency, thus forming vapor columns. These two phenomena combined with high thermal conductivity of the graphite fiber are considered the mechanisms for such a significant augmentation in nucleate boiling heat transfer on the composite surfaces. A physical model is developed to describe the phenomenon of bubble departure from the composite surface: The preferred site of bubble nucleation is the fiber tip because of higher tip temperature than the surrounding copper base and poor wettability of the graphite tip compared with that of the base material (copper). The high evaporation rate near the contact line produces the vapor cutback due to the vapor recoil pushing the three-phase line outwards from the fiber tip, and so a neck of the bubble is formed near the bubble bottom. Evaporation and surface tension accelerate the necking process and finally result in the bubble departure while a new small bubble is formed at the tip when the surface tension pushes the three-phase line back to the tip. The process is schematically shown. The proposed model is based on and confirmed by experimental results.

Zhang, Nengli; Chao, David F.; Yang, Wen-Jei

2002-01-01

403

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.

2012-07-19

404

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

405

Facilitating Students' Conceptual Understanding of Boiling Using a Four-Step Constructivist Teaching Method  

ERIC Educational Resources Information Center

The aim of the work presented here was to devise an activity associated with factors affecting boiling points. The intervention used a four-step constructivist-based teaching strategy, which was subsequently evaluated by a cohort of students. Data collection consisted of application of a purpose designed questionnaire consisting of four open-ended…

Calik, Muammer

2008-01-01

406

Lattice Boltzmann modeling of boiling heat transfer: The boiling curve and the effects of wettability  

E-print Network

A hybrid thermal lattice Boltzmann (LB) model is presented to simulate thermal multiphase flows with phase change based on an improved pseudopotential LB approach [Q. Li, K. H. Luo, and X. J. Li, Phys. Rev. E 87, 053301 (2013)]. The present model does not suffer from the spurious term caused by the forcing-term effect, which was encountered in some previous thermal LB models for liquid-vapor phase change. Using the model, the liquid-vapor boiling process is simulated. The boiling curve together with the three boiling stages (nucleate boiling, transition boiling, and film boiling) is numerically reproduced in the LB community for the first time. The numerical results show that the basic features and the fundamental characteristics of boiling heat transfer are well captured, such as the severe fluctuation of transient heat flux in the transition boiling and the feature that the maximum heat transfer coefficient lies at a lower wall superheat than that of the maximum heat flux. Furthermore, the effects of the he...

Li, Q; Francois, M M; He, Y L; Luo, K H

2015-01-01

407

Radiance Temperatures (in the Wavelength Range 530 to 1500 nm) of Nickel at Its Melting Point by a Pulse-Heating Technique  

NASA Astrophysics Data System (ADS)

The radiance temperatures (at seven wavelengths in the range 530 to 1500 nm) of nickel at its melting point were measured by a pulse-heating technique. The method is based on rapid resistive self-heating of the specimen from room temperature to its melting point in less than 1 s and on simultaneously measuring specimen radiance temperatures every 0.5 ms. Melting of the specimen was manifested by a plateau in the radiance temperature-versus-time function for each wavelength. The melting-point radiance temperatures for a given specimen were determined by averaging the measured temperatures along the plateau at each wavelength. The melting-point radiance temperatures for nickel, as determined by averaging the results at each wavelength for 25 specimens, are: 1641 K at 530 nm, 1615 K at 627 nm, 1606 K at 657 nm, 1589 K at 722 nm, 1564 K at 812 nm, 1538 K at 908 nm, and 1381 K at 1500 nm. Based on uncertainties arising from pyrometry and specimen conditions, the combined uncertainty (two standard-deviation level) is about ± 6 K for the reported values in the range 530 to 900 nm and is about ± 8 K for the reported value at 1500 nm.

Kaschnitz, E.; McClure, J. L.; Cezairliyan, A.

1998-11-01

408

Cryogenic Boil-Off Reduction System  

NASA Astrophysics Data System (ADS)

A computational model of the cryogenic boil-off reduction system being developed by NASA as part of the Cryogenic Propellant Storage and Transfer technology maturation project has been applied to a range of propellant storage tanks sizes for high-performing in-space cryogenic propulsion applications. This effort focuses on the scaling of multi-layer insulation (MLI), cryocoolers, broad area cooling shields, radiators, solar arrays, and tanks for liquid hydrogen propellant storage tanks ranging from 2 to 10 m in diameter. Component scaling equations were incorporated into the Cryogenic Analysis Tool, a spreadsheet-based tool used to perform system-level parametric studies. The primary addition to the evolution of this updated tool is the integration of a scaling method for reverse turbo-Brayton cycle cryocoolers, as well as the development and inclusion of Self-Supporting Multi-Layer Insulation. Mass, power, and sizing relationships are traded parametrically to establish the appropriate loiter period beyond which this boil-off reduction system application reduces mass. The projected benefit compares passive thermal control to active thermal control, where active thermal control is evaluated for reduced boil-off with a 90 K shield, zero boil-off with a single heat interception stage at the tank wall, and zero boil-off with a second interception stage at a 90 K shield. Parametric studies show a benefit over passive storage at loiter durations under one month, in addition to showing a benefit for two-stage zero boil-off in terms of reducing power and mass as compared to single stage zero boil-off. Furthermore, active cooling reduces the effect of varied multi-layer insulation performance, which, historically, has been shown to be significant.

Plachta, David W.; Guzik, Monica C.

2014-03-01

409

A fuzzy logic-controlled thermal process for simultaneous pasteurization and cooking of soft-boiled eggs  

Microsoft Academic Search

A fuzzy logic-based design of control for a unique thermal process in the food industry is presented. Products of the thermal process are pasteurized soft-boiled eggs. The function of temperature vs. time is unique in its shape and in its required precision, since the constraints of pasteurization and cooking of soft-boiled eggs are technically contradictory. Both processes can coexist only

Primoz Podržaj; Marjan Jenko

2010-01-01

410

A statistical technique for the investigation of weak points and degradation of high-temperature superconductor tapes  

NASA Astrophysics Data System (ADS)

Recent technological developments in manufacturing high-temperature superconductor (HTSC) tapes have improved their mechanical and electrical performances considerably. Now, a near future when HTSC cables will become a reality can finally be forecast. This brings about the need for work in the field of quality control and diagnostics of HTSC tapes. A new methodology for the analysis of the behaviour of tapes aged under different kinds of mechanical stresses is presented in this paper. The methodology is based on a probabilistic approach, where the two-parameter Weibull function is used to fit the cumulative and density probability distributions obtained from experimental V-I characteristics by numerical-analytical differentiation. Experimental results relevant to both long-term (aging) and short-term tests performed on 2223-BSCCO tapes are presented and discussed. It is shown that the time behaviour of Weibull function parameters provides useful information on the level of aging and on the kind of damage occurring to the tapes. In particular, the comparison between the results obtained from long-term and short-term tests, as well as from different types of mechanical stresses, points out that the shape of probability distributions constitutes a valuable diagnostic tool to distinguish between local or overall degradation and helps in identifying damage location.

Montanari, G. C.; Ghinello, I.; Gherardi, L.; Caracino, P.; Mele, R.

1998-05-01

411

The characteristics of super-elastic Ni-Ti wires in three-point bending. Part I: The effect of temperature.  

PubMed

The load-deflection behaviour of a number of commercially available superalloy nickel-titanium orthodontic wires has been examined in three-point bending over the temperature range 5-50 degrees C. The loading and unloading curves and plateau regions are found to be closely related to temperature with the stiffness decreasing quite dramatically over a narrow temperature range. The position of this range depends on the material being tested as there are marked differences due to the differing processing methods of the manufacturer. Force values at mouth temperature can differ by 600 per cent for wires of the same nominal diameter made by different manufacturers. PMID:7805815

Tonner, R I; Waters, N E

1994-10-01

412

Enhanced Boiling on Micro-Configured Composite Surfaces Under Microgravity Conditions  

NASA Technical Reports Server (NTRS)

In order to accommodate the growing thermal management needs of future space platforms, several two-phase active thermal control systems (ATCSs) have evolved and were included in the designs of space stations. Compared to the pumped single-phase liquid loops used in the conventional Space Transportation System and Spacelab, ATCSs offer significant benefits that may be realized by adopting a two-phase fluid-loop system. Alternately, dynamic power systems (DPSs), based on the Rankine cycle, seem inevitably to be required to supply the electrical power requirements of expanding space activities. Boiling heat transfer is one of the key technologies for both ATCSs and DPSs. Nucleate boiling near critical heat flux (CHF) can transport very large thermal loads with much smaller device size and much lower pumping power. However, boiling performance deteriorates in a reduced gravity environment and operation in the CHF regime is precarious because any slight overload will cause the heat transfer to suddenly move to the film boiling regime, which in turn, will result in burnout of the heat transfer surfaces. New materials, such as micro-configured metal-graphite composites, can provide a solution for boiling enhancement. It has been shown experimentally that this type of material manifests outstanding boiling heat transfer performance and their CHF is also extended to higher values. Due to the high thermal conductivity of graphite fiber (up to 1,200 W/m-K in the fiber direction), the composite surfaces are non-isothermal during the boiling process. The composite surfaces are believed to have a much wider safe operating region (a more uniform boiling curve in the CHF regime) because non-isothermal surfaces have been found to be less sensitive to variations of wall superheat in the CHF regime. The thermocapillary forces formed by the temperature difference between the fiber tips and the metal matrix play a more important role than the buoyancy in the bubble detachment, for the bubble detachment manifests itself by a necking process which should not be weakened by reduced gravity. In addition, the composite surfaces introduce no extra pressure drop, no fouling and do not impose significant primary or maintenance costs. All of these suggest that this type of composite is an ideal material for the challenge of accounting for both reliability and economy of the relevant components applied in the ATCSs, the DPSs and other devices in future space missions. The aim of the proposed work is to experimentally investigate high nucleate pool boiling performance on a micro-configured metal-graphite composite surface and to determine the mechanisms of the nucleate boiling heat transfer both experimentally and theoretically. Freon-113 and water will be used as the test liquids to investigate wettability effects on boiling characteristics. The Cu-Gr and Al-Gr composites with various volume fractions of graphite fibers will be tested to obtain the heat transfer characteristic data in the nucleate boiling region and in the CHF regime. In the experiments, the bubble emission and coalescence processes will be recorded by a video camera with a magnifying borescope probe immersed in the working fluid. The temperature profile in the thermal boundary layer on the composite surfaces will be measured by a group of micro thermocouples consisting of four ultra fine micro thermocouples. This instrument was developed and successfully used to measure the temperature profile of evaporating liquid thin layers by the proposers in a study performed at the NASA/Lewis Research Center. A two tier model to explain the nucleate boiling process and the performance enhancement on the composite surfaces has been suggested by the authors. According to the model, the thicknesses of the microlayer and the macrolayer underneath the bubbles and mushrooms, can be estimated by the geometry of the composite surface. The experimental results will be compared to the predictions from the model, and in turn, to revise and improve it.

Zhang, Nengli; Chai, An-Ti

1999-01-01

413

Enhancement of natural convection and pool boiling heat transfer via ultrasonic vibration  

Microsoft Academic Search

We report the relationship between the flow behavior induced by ultrasonic vibration and the consequent heat transfer enhancement in natural convection and pool boiling regimes. A thin platinum wire works as both a heat source and a temperature sensor. A high speed video imaging system is employed to observe the behavior of cavitation and thermal bubbles. Experimental results show that

Ho-Young Kim; Yi Gu Kim; Byung Ha Kang

2004-01-01

414

Magnetic resonance imaging of boiling induced by high intensity focused ultrasound.  

PubMed

Both mechanically induced acoustic cavitation and thermally induced boiling can occur during high intensity focused ultrasound (HIFU) medical therapy. The goal was to monitor the temperature as boiling was approached using magnetic resonance imaging (MRI). Tissue phantoms were heated for 20 s in a 4.7-T magnet using a 2-MHz HIFU source with an aperture and radius of curvature of 44 mm. The peak focal pressure was 27.5 MPa with corresponding beam width of 0.5 mm. The temperature measured in a single MRI voxel by water proton resonance frequency shift attained a maximum value of only 73 degrees C after 7 s of continuous HIFU exposure when boiling started. Boiling was detected by visual observation, by appearance on the MR images, and by a marked change in the HIFU source power. Nonlinear modeling of the acoustic field combined with a heat transfer equation predicted 100 degrees C after 7 s of exposure. Averaging of the calculated temperature field over the volume of the MRI voxel (0.3 x 0.5 x 2 mm(3)) yielded a maximum of 73 degrees C that agreed with the MR thermometry measurement. These results have implications for the use of MRI-determined temperature values to guide treatments with clinical HIFU systems. PMID:19354416

Khokhlova, Tatiana D; Canney, Michael S; Lee, Donghoon; Marro, Kenneth I; Crum, Lawrence A; Khokhlova, Vera A; Bailey, Michael R

2009-04-01

415

Measurement of the fractal order of wall void fraction during nucleate boiling  

E-print Network

Elsevier Inc. All rights reserved. Keywords: Correlation dimension; Box counting; Critical heat flux; Image temperature fluctuation measurements. In this study experiments were performed at different wall superheats to the classical boiling experiments of Zuber (1959), and Berenson (1961). The earlier classical approaches

Banerjee, Debjyoti

416

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

417

Magnetic resonance imaging of boiling induced by high intensity focused ultrasound  

PubMed Central

Both mechanically induced acoustic cavitation and thermally induced boiling can occur during high intensity focused ultrasound (HIFU) medical therapy. The goal was to monitor the temperature as boiling was approached using magnetic resonance imaging (MRI). Tissue phantoms were heated for 20 s in a 4.7-T magnet using a 2-MHz HIFU source with an aperture and radius of curvature of 44 mm. The peak focal pressure was 27.5 MPa with corresponding beam width of 0.5 mm. The temperature measured in a single MRI voxel by water proton resonance frequency shift attained a maximum value of only 73 °C after 7 s of continuous HIFU exposure when boiling started. Boiling was detected by visual observation, by appearance on the MR images, and by a marked change in the HIFU source power. Nonlinear modeling of the acoustic field combined with a heat transfer equation predicted 100 °C after 7 s of exposure. Averaging of the calculated temperature field over the volume of the MRI voxel (0.3×0.5×2 mm3) yielded a maximum of 73 °C that agreed with the MR thermometry measurement. These results have implications for the use of MRI-determined temperature values to guide treatments with clinical HIFU systems. PMID:19354416

Khokhlova, Tatiana D.; Canney, Michael S.; Lee, Donghoon; Marro, Kenneth I.; Crum, Lawrence A.; Khokhlova, Vera A.; Bailey, Michael R.

2009-01-01

418

The Nitrogen Boil-Off Method for Measuring AC Losses in HTS Coils  

Microsoft Academic Search

We have developed a novel apparatus for applying a nitrogen boil-off method as a mean of making calorimetric measurements and allowing for simple measuring and evaluating of AC losses in HTS coils at liquid nitrogen temperature. With the ability to measure AC loss generated in superconductors directly, this method produces more reliable data than that obtained by general, electro-magnetic measurements.

H. Okamoto; F. Sumiyoshi; K. Miyoshi; Y. Suzuki

2006-01-01

419

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

420

Pool boiling on nano-finned surfaces  

E-print Network

with sub-cooling of 45 K. They further studied the effect of micro-fins and submicron-scale roughness on boiling of FC-72. They found that the fins with submicron-scale roughness showed the greatest enhancement (1.8 – 2.3 times that of the bare surface... POOL BOILING ON NANO-FINNED SURFACES A Thesis by SHARAN RAM SRIRAMAN Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE...

Sriraman, Sharan Ram

2008-10-10

421

Method and apparatus for catalytically converting fractions of crude oil boiling above gasoline  

SciTech Connect

A method is described for upgrading a residual portion of a crude oil to form gasoline and light cycle oil which includes: (a) separating a residual portion of crude oil into a relatively low boiling fraction comprising atmospheric gas oil from a higher boiling fraction of the residual oil, (b) solvent deasphalting at least the resid portion of vacuum distillation of the higher boiling fraction and recovering a deasphalted oil product from a deasphalting solvent selected from propane, butane, pentane, hexane and combinations thereof, (c) partially hydrogenating the deasphalted oil product in the presence of a heavy vacuum gas oil fraction boiling intermediate the light vacuum gas oil and the vacuum resid, (d) passing the partially hydrogenated oil product mixed with an atomizing diluent material in contact with an upwardly flowing low coke producing crystalline zeolite containing catalyst suspended in a gas comprising hydrogen in a first riser heavy oil feed hydrocarbon conversion zone, (e) passing the separated low boiling fraction of crude oil with light vacuum gas oil in contact with a separate rising suspension of the elevated temperature low coke producing crystalline zeolite containing catalyst suspended in a gas comprising hydrogen in a second riser hydrocarbon conversion zone.

Farnsworth, C.D.

1986-04-22

422

Flow boiling with enhancement devices for cold plate coolant channel design  

NASA Technical Reports Server (NTRS)

Future space exploration and commercialization will require more efficient heat rejection systems. For the required heat transfer rates, such systems must use advanced heat transfer techniques. Forced two phase flow boiling heat transfer with enhancements falls in this category. However, moderate to high quality two phase systems tend to require higher pressure losses. This report is divided into two major parts: (1) Multidimensional wall temperature measurement and heat transfer enhancement for top heated horizontal channels with flow boiling; and (2) Improved analytical heat transfer data reduction for a single side heated coolant channel. Part 1 summarizes over forty experiments which involve both single phase convection and flow boiling in a horizontal channel heated externally from the top side. Part 2 contains parametric dimensionless curves with parameters such as the coolant channel radius ratio, the Biot number, and the circumferential coordinate.

Boyd, Ronald D.

1991-01-01

423

Impact of boiling conditions on the molecular and sensory profile of a vegetable broth.  

PubMed

Low-pressure cooking has recently been identified as an alternative to ambient and high-pressure cooking to provide food with enhanced organoleptic properties. This work investigates the impact of the cooking process at different pressures on the molecular and sensory profile of a vegetable broth. Experimental results showed similar sensory and chemical profiles of vegetable broths when boiling at 0.93 and 1.5 bar, while an enhancement of sulfur volatile compounds correlated with a greater leek content and savory aroma was observed when boiling at low pressure (80 °C/0.48 bar). Thus, low-pressure cooking would allow preserving the most labile volatiles likely due to the lower water boiling temperature and the reduced level of oxygen. This study evidenced chemical and sensory impact of pressure during cooking and demonstrated that the flavor profile of culinary preparations can be enhanced by applying low-pressure conditions. PMID:25579390

Mougin, Alice; Mauroux, Olivier; Matthey-Doret, Walter; Barcos, Eugenia Maria; Beaud, Fernand; Bousbaine, Ahmed; Viton, Florian; Smarrito-Menozzi, Candice

2015-02-11

424

Surface Boiling - a New Type of Instability of Highly Excited Atomic Nuclei  

E-print Network

The evolution of the nuclear matter density distribution with excitation energy is studied 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, both infinite and finite systems become unstable against infinitesimal matter density fluctuations, albeit in different ways. In modeling, this instability reveals itself via an apparent negative heat capacity of the system and is seen to result in the volume boiling in the case of infinite matter and surface boiling in the case of finite systems. The latter phenomenon of surface boiling is unique to small systems and it appears to provide a natural explanation for the observed saturation-like patterns in what is commonly termed caloric curves and what represents functional dependence of nuclear temperature on the excitation energy.

Tõke, J

2012-01-01

425

Surface Boiling - a New Type of Instability of Highly Excited Atomic Nuclei  

E-print Network

The evolution of the nuclear matter density distribution with excitation energy is studied 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, both infinite and finite systems become unstable against infinitesimal matter density fluctuations, albeit in different ways. In modeling, this instability reveals itself via an apparent negative heat capacity of the system and is seen to result in the volume boiling in the case of infinite matter and surface boiling in the case of finite systems. The latter phenomenon of surface boiling is unique to small systems and it appears to provide a natural explanation for the observed saturation-like patterns in what is commonly termed caloric curves and what represents functional dependence of nuclear temperature on the excitation energy.

J. Tõke; W. U. Schröder

2012-07-16

426

The role of surface conditions in nucleate boiling  

E-print Network

Nucleation from a single cavity has been stuied indicating that cavity gemtry is aportant in two ways. The mouth diameter determines the superheat nmeded to initiate boiling and its shape determines its stability one boiling ...

Griffith, P.

1958-01-01

427

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

428

Boiling and condensation in a liquid-filled enclosure  

E-print Network

A combined experimental and analytical investigation of boiling and condensation in a liquid-filled enclosure, with water and Freon- 113 as the working fluids, is described. The operating characteristics of a boiling system, ...

Bar-Cohen Avram

1971-01-01

429

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

430

High temperature exposure of in-situ thermocouple fixed-point cells: stability with up to three months of continuous use  

NASA Astrophysics Data System (ADS)

To categorise thermocouples in batches, manufacturers state an expected operating tolerance for when the thermocouples are as-new. In use, thermocouple behaviour can rapidly change and the tolerance becomes invalid, especially when used at high temperatures (i.e. above 1000?°C) as the processes leading to de-calibration, such as oxidation and contamination, can be very fast and lead to erroneous readings. In-situ thermocouple self-validation provides a method to track the drift and correct the thermocouple reading in real-time, but it must be shown to be reliable. Two miniature temperature fixed-point cells designed at NPL for in-situ thermocouple self-validation, the first containing a Pt-C eutectic alloy and the second containing a Ru-C eutectic alloy, have been exposed to temperatures close to their melting point for 2200?h and 1570?h, respectively, and continuously, for up to three months. Recalibration after this long-term high-temperature exposure, where a tantalum-sheathed thermocouple was always in place, is used to show that no significant change of the temperature reference point (the melting temperature) has occurred in either the Pt-C ingot or the Ru-C ingot, over timescales far longer than previously demonstrated and approaching that required by industry for practical use of the device.

Elliott, C. J.; Greenen, A.; Lowe, D.; Pearce, J. V.; Machin, G.

2015-04-01

431

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

432

NISTIR 5780 Enhancement of R123 Pool Boiling by the  

E-print Network

NISTIR 5780 Enhancement of R123 Pool Boiling by the Addition of N-Hexane Mark A. Kedzierski Enhancement of R123 Pool Boiling by the Addition of N-Hexane Mark A. Kedzierski March 1996 00, Ct of pool boiling performance of a GEWA-TTM surface for three fluids: (1) pure R123, (2) R123/n-hexane (99

Oak Ridge National Laboratory

433

Boiling heat transfer in rectangular microchannels with reentrant cavities  

E-print Network

Boiling heat transfer in rectangular microchannels with reentrant cavities Ali Kosßar, Chih Available online 18 August 2005 Abstract This paper investigates flow boiling of water in microchannels (28­445 W/cm2 ) and mass velocities (41­302 kg/m2 s). High Boiling number and Reynolds number have

Peles, Yoav

434

Boiling in microchannels: a review of experiment and theory  

Microsoft Academic Search

A summary of recent research on boiling in microchannels is presented. The review addresses the topics of macroscale versus microscale heat transfer, two-phase flow regimes, flow boiling heat transfer results for microchannels, heat transfer mechanisms in microchannels and flow boiling models for microchannels. In microchannels, the most dominant flow regime appears to be the elongated bubble mode that can persist

John R. Thome

2004-01-01

435

Nucleation characteristics and stability considerations during flow boiling in microchannels  

E-print Network

Nucleation characteristics and stability considerations during flow boiling in microchannels Satish; received in revised form 25 September 2005; accepted 3 October 2005 Abstract Flow boiling in microchannels in the flow boiling stability. To understand the role of local conditions on nucleation, the available

Kandlikar, Satish

436

ADVANCED POWER PLANT MODELING WITH APPLICATIONS TO THE ADVANCED BOILING  

E-print Network

ADVANCED POWER PLANT MODELING WITH APPLICATIONS TO THE ADVANCED BOILING WATER REACTOR AND THE HEAT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2. Advanced Boiling Water Reactor - General Description . . . . . . . . . . . 3 2.1 Modifications-Dimensional Continuity Wave Equation for Boiling Mixtures . . 10 3.2.1 Derivation of Equation

Mitchell, John E.

437

EFFECT OF SURFACE CHARACTERISTICS ON FLOW BOILING HEAT TRANSFER  

E-print Network

EFFECT OF SURFACE CHARACTERISTICS ON FLOW BOILING HEAT TRANSFER Satish G. Kandlikar and Paul H ABSTRACT It is well known that the surface structure affects the pool boiling heat transfer from a heater characteristics. This fact is utilized in developing structured and sintered surfaces for enhanced boiling

Kandlikar, Satish

438

Mechanism of nucleate pool boiling heat transfer to sodium and the criterion for stable boiling  

E-print Network

A comparison between liquid metals and other common fluids, like water, is made as regards to the various stages of nucleate pool boiling. It is suggested that for liquid metals the stage of building the thermal layer plays ...

Shai, Isaac

1967-01-01

439

Transition from film boiling to nucleate boiling in forced convection vertical flow  

E-print Network

The mechanism of collapse of forced cnnvection annular vertical flow film boiling, with liquid core, is investigated using liquid nitrogen at low pressures. The report includes the effect of heat flux from the buss bar. ...

Iloeje, Onwuamaeze C.

1972-01-01

440

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 defined…

Reilly, John M.

441

Future directions in boiling water reactor design  

Microsoft Academic Search

The Advances Boiling Water Reactor (ABWR) is being developed by an international team of BWR manufacturers to respond to worldwide utility needs in the l1980's. Major objectives of the ABWR program are design simplification; improved safety and reliability; reduced construction, fuel and operating costs; improved maneuverability; and reduced occupational exposure and radwaste. The ABWR incorporate the best proven features from

D. R. Wilkins; J. D. Duncan; S. A. Hucik; J. I. Sweeney

1988-01-01

442

Simplified boiling water reactor passive safety features  

Microsoft Academic Search

This paper discusses the system functions and related hardware of key passive safety features of the simplified boiling water reactor (SBWR). The SBWR is a nominal 600-MW(electric) BWR that incorporates simplified systems and passive emergency equipment to enhance reactor operability and safety in an economical design that can be rapidly constructed. The SBWR reactor system is based on a nuclear

H. A. Upton; F. E. Cooke; J. K. Sawabe

1993-01-01

443

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

444

Boiling Crisis as a Critical Phenomenon  

NASA Astrophysics Data System (ADS)

We present the first experimental study of intermittency and avalanche distribution during a boiling crisis. To understand the emergence of power law statistics we propose a simple spin model capturing the measured critical exponent. The model suggests that behind the critical heat flux is a percolation phenomenon involving drying-rewetting competition close to the hot surface.

Lloveras, P.; Salvat-Pujol, F.; Truskinovsky, L.; Vives, E.

2012-05-01

445

The Plausibility of Boiling Geysers on Triton  

NASA Technical Reports Server (NTRS)

A mechanism is suggested and modeled whereby there may be boiling geysers on Triton. The geysers would be of nitrogen considering that Voyager detected cryovolcanic activity, that solid nitrogen conducts heat much less than water ice, and that there is internal heat on Triton.

Duxbury, N. S.; Brown, R. H.

1995-01-01

446

Electrohydrodynamic Pool Boiling in Reduced Gravity  

NASA Technical Reports Server (NTRS)

This research is concerned with studying the effects of applied electric fields on pool boiling in a reduced-gravity environment. Experiments are conducted at the NASA Lewis 2.2 sec Drop tower using a drop rig constructed at UC Davis. In the experiments, a platinum wire is heated while immersed in saturated liquid refrigerants (FC-72 and FC-87), or water, causing vapor formation at the wire surface. Electric fields are applied between the wire surface and an outer screen electrode that surrounds the wire. Preliminary normal-gravity experiments with water have demonstrated that applied electric fields generated by the rig electronics can influence boiling characteristics. Reduced-gravity experiments will be performed in the summer of 1996. The experiments will provide fundamental data on electric field strengths required to disrupt film boiling (for various wire heat generation input rates) in reduced gravity for a cylindrical geometry. The experiments should also shed light on the roles of characteristic bubble generation times and charge relaxation times in determining the effects of electric fields on pool boiling. Normal-gravity comparison experiments will also be performed.

Shaw, Benjamin D.; Stahl, S. L.

1996-01-01

447

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

448

Temperature dependence of the mechanical properties of melt-processed Dy Ba Cu O bulk superconductors evaluated by three point bending tests  

NASA Astrophysics Data System (ADS)

Dy-Ba-Cu-O bulk superconductor has an excellent capability of trapping magnetic flux and lower heat conductivity at cryogenic temperatures as compared with Y-Ba-Cu-O bulk superconductor. The Young's modulus and the bending strength in the range from room temperature to 7 K were measured by the three-point bending tests using