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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

When water does not boil at the boiling point.  

PubMed

Every schoolchild learns that, under standard pressure, pure water always boils at 100 degrees C. Except that it does not. By the late 18th century, pioneering scientists had already discovered great variations in the boiling temperature of water under fixed pressure. So, why have most of us been taught that the boiling point of water is constant? And, if it is not constant, how can it be used as a 'fixed point' for the calibration of thermometers? History of science has the answers. PMID:17336380

Chang, Hasok

2007-03-01

4

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.

5

Method for calibrating copper-constantan thermocouples at negative temperatures by means of the boiling point of water  

Microsoft Academic Search

Conclusions 1.The suggested method for calibrating copper-constantan thermocouples is based on the linear relationship of corrections to the corresponding thermal emf evaluated at a single point.2.Temperatures in the negative range (0 to -200C) are calibrated by means of the boiling point of water with an error of 0.3C.3.The interpolation of the thermal emf in the range from zero to the

A. P. Bondareva

1969-01-01

6

Melting point, boiling point, and symmetry.  

PubMed

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 parameters. The melting point of some non-hydrogen-bonding, rigid compounds can be estimated by the equation MP = 0.772 * BP + 110.8 * SIGMAL + 11.56 * ORTHO + 31.9 * EXPAN - 240.7 where MP is the melting point of the compound in Kelvin, BP is the boiling point, SIGMAL is the logarithm of the symmetry number, EXPAN is the cube of the eccentricity of the compound, and ORTHO indicates the number of groups that are ortho to another group. PMID:2235894

Abramowitz, R; Yalkowsky, S H

1990-09-01

7

Reorientational dynamics in molecular liquids as revealed by dynamic light scattering: From boiling point to glass transition temperature  

NASA Astrophysics Data System (ADS)

We determine the reorientational correlation time ? of a series of molecular liquids by performing depolarized light scattering experiments (double monochromator, Fabry-Perot interferometry, and photon correlation spectroscopy). Correlation times in the range 10-12 s-100 s are compiled, i.e., the full temperature interval between the boiling point and the glass transition temperature Tg is covered. We focus on low-Tg liquids for which the high-temperature limit ? ? 10-12 s is easily accessed by standard spectroscopic equipment (up to 440 K). Regarding the temperature dependence three interpolation formulae of ?(T) with three parameters each are tested: (i) Vogel-Fulcher-Tammann equation, (ii) the approach recently discussed by Mauro et al. [Proc. Natl. Acad. Sci. U.S.A. 106, 19780 (2009)], and (iii) our approach decomposing the activation energy E(T) in a constant high temperature value E? and a "cooperative part" Ecoop(T) depending exponentially on temperature [Schmidtke et al., Phys. Rev. E 86, 041507 (2012)], 10.1103/PhysRevE.86.041507. On the basis of the present data, approaches (i) and (ii) are insufficient as they do not provide the correct crossover to the high-temperature Arrhenius law clearly identified in the experimental data while approach (iii) reproduces the salient features of ?(T). It allows to discuss the temperature dependence of the liquid's dynamics in terms of a Ecoop(T)/E? vs. T/E? plot and suggests that E? controls the energy scale of the glass transition phenomenon.

Schmidtke, B.; Petzold, N.; Kahlau, R.; Rssler, E. A.

2013-08-01

8

Water above its boiling point: Study of the temperature and density dependence of the partial pair correlation functions. I. Neutron diffraction experiment  

Microsoft Academic Search

Neutron diffraction data on water, employing the technique of hydrogen\\/deuterium isotope substitution, are reported at three thermodynamic states above the boiling point. The structural information is analyzed in terms of the partial radial distribution functions, OO, OH, and HH, which are extracted from the neutron data. It is found that temperature affects mainly the medium and longer range order in

P. Postorino; M. A. Ricci; A. K. Soper

1994-01-01

9

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

10

Boiling Point Detector for Surface Cooking Unit  

Microsoft Academic Search

The new type of boiling point detector is discussed which detects the boiling point of water in a container irrespective of the volume of water or the type of container. This detector consists of the sensor unit using a thermistor and the signal processor unit using a one-chip 4-b microcomputer. The sensor unit is covered with a stainless casing. It

Haruo Terai; Yasumichi Kobayashi; Shigeharu Nakamoto

1984-01-01

11

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

12

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

Microsoft Academic Search

Condensing of a sugarwater solution is a widely used production process, especially in food industry. In this study, boiling\\u000a temperature and heat transfer of different concentration levels of sugar\\/water solution is experimentally studied. In the\\u000a experiment, the pool boiling with constant temperature difference between surface and boiling temperature is investigated.\\u000a Boiling point of sugar\\/water solution depends on sugar mass concentration

Mustafa zdemir; Hseyin Pehlivan

2008-01-01

13

Boiling Point of Capillary-condensed Water  

Microsoft Academic Search

A CONSIDERABLE amount of experimental work on freezing-point depressions of capillary condensates has been reported in the literature in recent years1. Carman2 has given an account of a few more properties in which capillary-held liquids differ from the same materials in bulk conditions. Boiling points of condensates, however, do not appear to have been studied in detail. We have devised

M. L. Lakhanpal; B. R. Puri

1953-01-01

14

Excess Heat In Heavy Water--Pd\\/C Catalyst Cathode (Case-Type) Electrolysis At Temperatures Near The Boiling Point  

Microsoft Academic Search

In the present work, our goal was to enhance apparent excess power by raising the temperature of the electrolyte. We believe that at a higher temperature the deuterium flux may be enhanced. The correlation (3) between the deuterium flux and the heat flow might produce greater excess power. Based on our observations of \\

QING M. WEI; XING Z. LI; YAN O. CUI

15

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

16

THE ELEVATION OF BOILING POINTS IN H2O AND D2O ELECTROLYTES  

Microsoft Academic Search

The excess enthalpy effect in cold fusion experiments for Pd\\/D2O + LiOD systems is subject to positive feedback, i.e., increasing the cell temperature increases the excess enthalpy. Therefore, the largest excess enthalpy effects are often observed near or at the boiling point corresponding to that of the electrolyte solution in the cell. The exact boiling temperatures at different electrolyte concentrations

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

2002-01-01

17

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

Microsoft Academic Search

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

L. K. T

1987-01-01

18

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

19

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

E-print Network

Perfluorooctanoic acid · Melting point ~55 °C, boiling point ~190 °C, pKa ~ 2.5, sparingly soluble in water and polar organic solvents · Stable at normal temperatures and pressures but avoid contact #12;Perfluorooctanoic acid · It concentrates on water surfaces as it is a fluoro-surfactant · Used

Cohen, Robert E.

20

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 13.56K and 25.85K, respectively. PMID:25022475

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

2015-01-01

21

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

22

Life above the boiling point of water?  

Microsoft Academic Search

Summary Various extremely thermophilic archaebacteria exhibit optimum growth at above 80C.Pyrodictium is the most thermophilic of these organisms, growing at temperatures of up to 110C and exhibiting optimum growth at about 105C. 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

23

Apparatus for the determination of the heat of evaporation of liquids of high boiling points  

Microsoft Academic Search

Two new forms of apparatus for determining the heat of evaporation of liquids of high boiling point are described, and their relative merits briefly discussed.In the one the determination is made by a measurement of the amount of liquid vapourised for a given energy supply (radiation loss being eliminated by means of a constant temperature jacket) and in the other,

J. H. Awbery; Ezer Griffiths

1923-01-01

24

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

25

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

26

Quantitative structure-property relationships for prediction of boiling point, vapor pressure, and melting point.  

PubMed

Boiling point, vapor pressure, and melting point are important physicochemical properties in the modeling of the distribution and fate of chemicals in the environment. However, such data often are not available, and therefore must be estimated. Over the years, many attempts have been made to calculate boiling points, vapor pressures, and melting points by using quantitative structure-property relationships, and this review examines and discusses the work published in this area, and concentrates particularly on recent studies. A number of software programs are commercially available for the calculation of boiling point, vapor pressure, and melting point, and these have been tested for their predictive ability with a test set of 100 organic chemicals. PMID:12924571

Dearden, John C

2003-08-01

27

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 -110C. It was shown that during the PMT cooldown from room temperature to -110C (a typical PMT operation temperature in liquid xenon detectors), the absolute QE increases by a factor of 1.11.15 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

28

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

29

The Elevation of Boiling Points in H_2O and D_2O Electrolytes  

Microsoft Academic Search

The excess enthalpy effect in cold fusion experiments for Pd\\/D_2O systems is subject to positive feedback, i.e., increasing the cell temperature increases the excess enthalpy . Therefore, the largest excess enthalpy effects are often observed near or at the boiling point corresponding to that of the electrolyte solution in the cell(M.H. Miles, M. Fleischmann and M.A. Imam, \\

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

2002-01-01

30

Development of splitsplitless PTV large-volume injection for analytes covering a wide boiling point range  

Microsoft Academic Search

A programmed-temperature vaporiser (PTV)large-volume injection (LVI) method with a two-stage evaporation process was developed capable of effectively introducing analytes covering a wide boiling-point range (from that of n-nonane to that of n-tetracontane). The method uses speed-controlled sample introduction (50 L) and a simple PTV setup with Peltier Cooling. Besides, an important cause of discrimination of high-boiling compounds in LVI was

Zoltn Szekeres; Gbor Volk; Zsuzsanna Eke

2009-01-01

31

The melting and boiling points of compounds in homologous series of monohalogenated n-alkanes  

NASA Astrophysics Data System (ADS)

The available data on the melting and boiling points in homologous series of normal 1-fluoro-, 1-chloro-, 1-bromo-, and 1-iodoalkanes were critically analyzed. A correlation was observed between the melting and boiling points of halogenated even and odd n-alkanes. This allowed us to obtain an interpolation equation for predicting compound melting points.

Bolotnikov, M. F.; Neruchev, Yu. A.

2007-08-01

32

Adhesion test with water boiling method at high-temperature  

Microsoft Academic Search

Water boiling test can evaluate the adhesion between base asphalt (A-70, etc.) and stone, but cannot evaluate the adhesion between modified asphalt , the asphalt with all kinds of anti-stripping products and stone. The reason is that modified asphalt has better adhesion than base asphalt at the same test temperature, and it is very hard to damage the adhesion interface.

Zhi Li; Xiao-ning Zhang

2011-01-01

33

A Simplified Procedure for Determining Normal Boiling Points by the Comparative Method  

Microsoft Academic Search

SWIETOSLAWSKI'S method1 for determining the normal boiling point of a substance by comparing its boiling point with that of water at three or more pressures, and applying his equation involving the ratio of the dt\\/dp coefficients of the two liquids, can be simplified by working as nearly as possible at a pressure of one normal atmosphere. If the manostat, which

Mieczyslaw Wojciechowski

1936-01-01

34

BOILING POINT --McDonald's recalls Shrek glasses due to potential  

E-print Network

NEWS BOILING POINT -- McDonald's recalls Shrek glasses due to potential cadmium risk -- The U issued by the International Agency for Research on... More Boiling point... MINUSCULE -- Sea urchins tolerate acid water -- Sea urchins are likely to be able to adapt to increasingly acidic... -- Virtual

Rogers, John A.

35

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

36

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

Microsoft Academic Search

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

Cary Presser; C. T. Avedisian

2006-01-01

37

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

NASA Astrophysics Data System (ADS)

Following an earlier paper ( J. Chem. Educ. 1997, 74, 1080-1084 ) on binary melting point diagrams, a method of constructing boiling point diagrams for each of the kinds of behavior of binary miscible liquid pairs (those without an azeotrope, those with a maximum boiling azeotrope, and those with a minimum boiling azeotrope) is described and illustrated. Necessary data are the boiling points and enthalpies of vaporization of the components, and parameters relating the activity coefficients of the liquid components to their concentrations. The procedure requires the solution of pairs of simultaneous equations by the method of successive approximation. It is shown how the resulting diagram reflects the nature of the intermolecular forces and the proximity of the boiling points of the components to each other.

Smith, Norman O.

2004-03-01

38

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

Microsoft Academic Search

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

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

2009-01-01

39

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

NASA Astrophysics Data System (ADS)

This study investigates the hydrodynamic characteristics of droplet impingement on heated surfaces and compares the effect of surface temperature when using water and a nanofluid on a polished and nanostructured surface. Results are obtained for an impact Reynolds number and Weber number of approximately 1700 and 25, respectively. Three discs are used: polished silicon, nanostructured porous silicon and gold-coated polished silicon. Seven surface temperatures, including single-phase (non-boiling) and two-phase (boiling) conditions, are included. Droplet impact velocity, transient spreading diameter and dynamic contact angle are measured. Results of water and a water-based single-wall carbon-nanotube nanofluid impinging on a polished silicon surface are compared to determine the effects of nanoparticles on impinging dynamics. The nanofluid results in larger spreading velocities, larger spreading diameters and an increase in early-stage dynamic contact angle. Results of water impinging on both polished silicon and nanostructured silicon show that the nanostructured surface enhances the heat transfer for evaporative cooling at lower surface temperatures, which is indicated by a shorter evaporation time. Using a nanofluid or a nanostructured surface can reduce the total evaporation time up to 20% and 37%, respectively. Experimental data are compared with models that predict dynamic contact angle and non-dimensional maximum spreading diameter. Results show that the molecular-kinetic theory's dynamic contact angle model agrees well with current experimental data for later times, but over-predicts at early times. Predictions of maximum spreading diameter based on surface energy analyses indicate that these models over-predict unless empirical coefficients are adjusted to fit the test conditions. This is a consequence of underestimates of the dissipative energy for the conditions studied.

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

2009-11-01

40

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

PubMed

This study investigates the hydrodynamic characteristics of droplet impingement on heated surfaces and compares the effect of surface temperature when using water and a nanofluid on a polished and nanostructured surface. Results are obtained for an impact Reynolds number and Weber number of approximately 1700 and 25, respectively. Three discs are used: polished silicon, nanostructured porous silicon and gold-coated polished silicon. Seven surface temperatures, including single-phase (non-boiling) and two-phase (boiling) conditions, are included. Droplet impact velocity, transient spreading diameter and dynamic contact angle are measured. Results of water and a water-based single-wall carbon-nanotube nanofluid impinging on a polished silicon surface are compared to determine the effects of nanoparticles on impinging dynamics. The nanofluid results in larger spreading velocities, larger spreading diameters and an increase in early-stage dynamic contact angle. Results of water impinging on both polished silicon and nanostructured silicon show that the nanostructured surface enhances the heat transfer for evaporative cooling at lower surface temperatures, which is indicated by a shorter evaporation time. Using a nanofluid or a nanostructured surface can reduce the total evaporation time up to 20% and 37%, respectively. Experimental data are compared with models that predict dynamic contact angle and non-dimensional maximum spreading diameter. Results show that the molecular-kinetic theory's dynamic contact angle model agrees well with current experimental data for later times, but over-predicts at early times. Predictions of maximum spreading diameter based on surface energy analyses indicate that these models over-predict unless empirical coefficients are adjusted to fit the test conditions. This is a consequence of underestimates of the dissipative energy for the conditions studied. PMID:21715897

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

2009-11-18

41

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

42

Characterization of the TIP4P-Ew water model: Vapor pressure and boiling point  

NASA Astrophysics Data System (ADS)

The liquid-vapor-phase equilibrium properties of the previously developed TIP4P-Ew water model have been studied using thermodynamic integration free-energy simulation techniques in the temperature range of 274-400K. We stress that free-energy results from simulations need to be corrected in order to be compared to the experiment. This is due to the fact that the thermodynamic end states accessible through simulations correspond to fictitious substances (classical rigid liquids and classical rigid ideal gases) while experiments operate on real substances (liquids and real gases, with quantum effects). After applying analytical corrections the vapor pressure curve obtained from simulated free-energy changes is in excellent agreement with the experimental vapor pressure curve. The boiling point of TIP4P-Ew water under ambient pressure is found to be at 370.31.9K, about 7K higher than the boiling point of TIP4P water (363.75.1K; from simulations that employ finite range treatment of electrostatic and Lennard-Jones interactions). This is in contrast to the approximately +15K by which the temperature of the density maximum and the melting temperature of TIP4P-Ew are shifted relative to TIP4P, indicating that the temperature range over which the liquid phase of TIP4P-Ew is stable is narrower than that of TIP4P and resembles more that of real water. The quality of the vapor pressure results highlights the success of TIP4P-Ew in describing the energetic and entropic aspects of intermolecular interactions in liquid water.

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

2005-11-01

43

Characterization of the TIP4P-Ew water model: vapor pressure and boiling point.  

PubMed

The liquid-vapor-phase equilibrium properties of the previously developed TIP4P-Ew water model have been studied using thermodynamic integration free-energy simulation techniques in the temperature range of 274-400 K. We stress that free-energy results from simulations need to be corrected in order to be compared to the experiment. This is due to the fact that the thermodynamic end states accessible through simulations correspond to fictitious substances (classical rigid liquids and classical rigid ideal gases) while experiments operate on real substances (liquids and real gases, with quantum effects). After applying analytical corrections the vapor pressure curve obtained from simulated free-energy changes is in excellent agreement with the experimental vapor pressure curve. The boiling point of TIP4P-Ew water under ambient pressure is found to be at 370.3+/-1.9 K, about 7 K higher than the boiling point of TIP4P water (363.7+/-5.1 K; from simulations that employ finite range treatment of electrostatic and Lennard-Jones interactions). This is in contrast to the approximately +15 K by which the temperature of the density maximum and the melting temperature of TIP4P-Ew are shifted relative to TIP4P, indicating that the temperature range over which the liquid phase of TIP4P-Ew is stable is narrower than that of TIP4P and resembles more that of real water. The quality of the vapor pressure results highlights the success of TIP4P-Ew in describing the energetic and entropic aspects of intermolecular interactions in liquid water. PMID:16321097

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

2005-11-15

44

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

45

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

46

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

47

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

Microsoft Academic Search

This paper reports the findings of a study exploring the use of a software package to help pupils understand particulate explanations for melting and evaporation below boiling point. Two matched classes in a primary school in Greece (ages 1112, n = 16 and 19) were involved in a short intervention of six one hour lessons. Covering the same phenomena and

George Papageorgiou; Philip Johnson; Fotis Fotiades

2008-01-01

48

A CONTINUOUS BOILING POINT ANALYZER AND ITS APPLICATION TO THE HYDROGEN FLUORIDE-WATER SYSTEM  

Microsoft Academic Search

A simple and inexpensive instrument is described which provides a ; continuously recorded analysis of binary liquid or vapor mixtures by measurement ; of the boiling point. The instrnment is insensitive to flow rate within broad ; limits. The response lag is less than one minute. The instrument may be applied ; to a sample loop of a liquid or

1960-01-01

49

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.

50

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

51

THE ANALOGY BETWEEN THE BUBBLING OF AIR INTO WATER AND NUCLEATE BOILING AT SATURATION TEMPERATURE  

Microsoft Academic Search

A basis for separate consideration of the hydrodynamic and thermal ; aspects of nucleate boiling is discussed. It is shown how boiling phenomena may ; be simulated in detail by the use of porous media to introduce air bubbles into ; water. Points of similarity and equivalence are described and analyzed. (auth);

Wallis

1960-01-01

52

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

E-print Network

The objective of this investigation is to measure and analyze surface temperature fluctuations in pool boiling. The surface temperature fluctuations were recorded on silicon surfaces with and without multi-walled carbon nanotubes (MWCNT). Novel Thin...

Sathyamurthi, Vijaykumar

2011-02-22

53

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

54

Correlation between the solubility of aromatic hydrocarbons in water and micellar solutions, with their normal boiling points  

Microsoft Academic Search

A linear correlation between the logarithm of the solubility in water of aromatic hydrocarbons and their normal boiling points is shown. Similarly, the logarithm of the distribution ratio of aromatic hydrocarbons in aqueous micellar solution is shown to be linearly related to the boiling points of the hydrocarbons. 2 figures, 2 tables.

Mats Almgren; Franz Grieser; James R. Powell; J. Kerry Thomas

1979-01-01

55

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

56

Effects of Micro/Nano-Scale Surface Characteristics on the Leidenfrost Point Temperature of Water  

E-print Network

In recent film boiling heat transfer studies with nanofluids, it was reported that deposition of nanoparticles on a surface significantly increases the nominal minimum heat flux (MHF) or Leidenfrost Point (LFP) temperature, ...

Hu, Lin-Wen

57

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

E-print Network

and Polytetrafluoroethylene James S. Chickos* Department of Chemistry and Biochemistry, University of MissourisSt. Louis, St and approximately TB() ) 915 K for those related to polytetrafluoroethylene. Normal boiling temperatures have been

Chickos, James S.

58

Numerical study on temperature distribution around a boiling bubble departing from heating surface in subcooled pool  

NASA Astrophysics Data System (ADS)

In this paper, the transient three-dimensional numerical simulations based on the MARS (Multi-interface Advection and Reconstruction Solver) with the non-empirical boiling and condensation model have been conducted for an isolated boiling bubble behavior in a subcooled pool. The temperature distributions formed around the subcooled pool boiling bubble departing from a heating surface obtained by the numerical simulations were investigated. As the results, it was found that several thermal plumes with different temperature were formed during the bubble departure from the heating surface by using the volume rendering visualization technique.

Ose, Yasuo; Kunugi, Tomoaki

2014-06-01

59

Differentiation of volcanic emanation around the boiling point of water in geothermal regions in Japan  

Microsoft Academic Search

ConclusionThe nature of the differentiation of the volcanic emanations around the boiling point of water has been made clear in detail\\u000a by this study in some geothermal regions.\\/The chemical composition of the parent volcanic emanation supplied at the Atosanupuri-Kawayu\\u000a geothermal district has been calculated by the theory of the differentiation of the magmatic emanation proposed by the present\\u000a authors. The

I. Iwasaki; T. Ozawa; M. Yoshida

1966-01-01

60

Thermal Evaporation: Representation of Rise in Boiling Point of Grapefruit Juice  

Microsoft Academic Search

The rise in boiling point of grapefruit juice was experimentally measured at soluble solids concentrations in the range of 9.360.6 Brix and pressures between 6.0 10 3 and 9.0 104 Pa. Different approaches to represent experimental data, including the Dhring's rule, the Antoine equation and empirical models proposed in the literature were tested. In the range of 9.329.0

J. Telis-Romero; D. Cant-Lozano; V. R. N. Telis; A. L. Gabas

2007-01-01

61

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

62

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

63

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.

64

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

Microsoft Academic Search

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

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

2009-01-01

65

Calculation of phase equilibria for the low-boiling-point compound + solvent binary systems by group-contribution equation of state  

Microsoft Academic Search

Group parameters of low-boiling-point compounds (gaseous compounds) for a group-contribution equation of state based on a hole theory previously proposed are newly determined to predict the phase equilibria for gaseous compound+solvent systems at high temperatures and pressures. The gaseous compounds studied in this work are ethane, propane, butane, carbon dioxide and ammonia. The solvents are hydrocarbons, alcohols and water. The

Masashi Haruki; Yusuke Shimoyama; Yoshio Iwai; Yasuhiko Arai

2003-01-01

66

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

PubMed

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

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

2013-11-01

67

A circulation system with low boiling point medium to replace water-cooling medium for turbine generator stator  

Microsoft Academic Search

In this article, an evaporative cooling circulation system for turbine generator stator winding was introduced. The design has taken into account of the characteristics of the whole liquid cooling approach for the large turbine generator, the requirements for the 50MW turbine generator evaporative cooling for the stator as well as the physical and chemical characteristics of the low boiling point

Fu De Ping; Guo Jian Hong; Li Zhen Guo; Xiong Bin; Dong Hai Hong; Gu Guo Biao

2010-01-01

68

Estimation of the entropy of vaporization at the normal boiling point for azeotropic mixtures containing water, alcohol or acetic acid  

Microsoft Academic Search

The entropy of vaporization at the normal boiling point has been estimated for binary and ternary azotropic mixtures containing water, alcohol or acetic acid. For this purpose, the LeeKesler correlation, developed originally for pure substances, is used with the appropriate mixing rules to estimate the heat of vaporization of the mixtures. Estimations for the entropy of vaporization of the 97

Ya?ar Demirel

1999-01-01

69

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

70

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

71

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

72

Oxidation kinetics of micron-sized aluminum powder in high-temperature boiling water  

Microsoft Academic Search

A new efficient method of hydrogen, heat and aluminum oxide\\/hydroxide co-production is proposed. Only micron-sized aluminum powder (without any chemical activation) and usual water are used as initial reagents. For aluminum to be effectively oxidized, water is converted into the high-temperature boiling state that creates high pressure inside oxidation reactor. Paper describes the oxidation kinetics of aluminum micron powder in

M. S. Vlaskin; E. I. Shkolnikov; A. V. Bersh

2011-01-01

73

High-impulse, low-power, digital microthrusters using low boiling temperature liquid propellant with high viscosity fluid plug  

Microsoft Academic Search

High-impulse, low-power, multiple-shot digital microthrusters have been developed using low boiling temperature liquid propellant with high viscosity fluid plug. The low boiling temperature propellant is used for reducing the electrical input power required for blast pressure build-up, while the high viscosity fluid plug is intended to withhold the propellant pressure for the high-impulse blast. The three-layer microthrusters in the size

Tae Goo Kang; Sang Wook Kim; Young-Ho Cho

2002-01-01

74

Calculations of Freezing Point Depression, Boiling Point Elevation, Vapor Pressure and Enthalpies ofVaporization 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

75

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

NASA Astrophysics Data System (ADS)

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

Kim, I. P.

2013-07-01

76

Water boiling inside carbon nanotubes: toward efficient drug release.  

PubMed

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

Chaban, Vitaly V; Prezhdo, Oleg V

2011-07-26

77

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 log Kow 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

Fabiana Alves de Lima; Marcia Miguel Castro Ferreira

78

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

Microsoft Academic Search

A Quantitative StructureProperty 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), octanolwater 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; Mrcia Miguel Castro Ferreira

2003-01-01

79

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

Microsoft Academic Search

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

Thomas Mueller-Menzel

1987-01-01

80

Oxidation and formation of oxidation products of ?-carotene at boiling temperature.  

PubMed

?-Carotene is one of the most important lipid component extensively used in food industries as source of pro-vitamin A and colorant. During processing and storage ?-carotene is oxidized and degraded to various oxidation compounds. Some of these compounds are also the key aroma compounds in certain flowers, vegetables and fruits. The methods for analysis and determination of these oxidized products formed during food boiling or preparation are key to the understanding the chemistry of these compounds. This paper presents a novel analytical method incorporating high performance liquid chromatography with diode array and mass spectrometric detection for the characterization of oxidation, isomerization and oxidation products of ?-carotene in toluene at boiling temperature. HPLC and APCI-MS was optimized using oxidized sample and flow injection analysis of the standard ?-carotene respectively. ?-Carotene was oxidized in the Rancimat at 110C for 30, 60 and 90 min. The oxidized samples were than analyzed by HPLC system at 450 nm and 350 nm as well as scanning and single ion monitoring mass spectrometry. A total of ten oxidation products and three Z-isomers were reported. Extensive isomerization was observed during treatment at the control accelerated conditions. The oxidation products include five apo-carotenals, three diepoxides, one mono-epoxide and one short chain species. Results show that the method was reproducible, accurate and reliable for the separation and identification of oxidation products of ?-carotene. PMID:22387098

Zeb, Alam

2012-04-01

81

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 (20.3722K).

Mehmandoust, Babak; Sanjari, Ehsan; Vatani, Mostafa

2013-01-01

82

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

83

Remote temperature-set-point controller  

DOEpatents

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

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

1986-01-01

84

Determining factors for anodic polarization curves of typical structural materials of boiling water reactors in high temperature high purity water  

Microsoft Academic Search

In order to examine the anodic polarization characteristics of typical structural materials of boiling water reactors (BWRs), the anodic polarization curves of type 316L stainless steel (316L SS) and Alloy 182 were measured in deaerated high purity water at 553K using the previously reported measurement method which was confirmed suitable for high temperature high purity water. In order to

Masahiko Tachibana; Kazushige Ishida; Yoichi Wada; Ryosuke Shimizu; Nobuyuki Ota; Nobuyoshi Hara

2012-01-01

85

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

86

Dual reference point temperature interrogating method for distributed temperature sensor  

NASA Astrophysics Data System (ADS)

A novel method based on dual temperature reference points is presented to interrogate the temperature in a distributed temperature sensing (DTS) system. This new method is suitable to overcome deficiencies due to the impact of DC offsets and the gain difference in the two signal channels of the sensing system during temperature interrogation. Moreover, this method can in most cases avoid the need to calibrate the gain and DC offsets in the receiver, data acquisition and conversion. An improved temperature interrogation formula is presented and the experimental results show that this method can efficiently estimate the channel amplification and system DC offset, thus improving the system accuracy.

Ma, Xin; Ju, Fang; Chang, Jun; Wang, Weijie; Wang, Zongliang

2013-10-01

87

QSPR modelling of normal boiling points and octanol\\/water partition coefficient for acyclic and cyclic hydrocarbons using SMILES-based optimal descriptors  

Microsoft Academic Search

Predictive quantitative structure - property relationships (QSPR) have been established for normal boiling points and octanol\\/water\\u000a partition coefficient for acyclic and cyclic hydrocarbons using optimal descriptors calculated with simplified molecular input\\u000a line entry system (SMILES). The probabilistic criteria for a rational definition of the domain of applicability of these models\\u000a are discussed.

A. A. Toropov; A. P. Toropova; E. Benfenati

2010-01-01

88

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

Microsoft Academic Search

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

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

2005-01-01

89

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 80100C. 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

90

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

Microsoft Academic Search

The liquid-vapor-phase equilibrium properties of the previously developed TIP4P-Ew water model have been studied using thermodynamic integration free-energy simulation techniques in the temperature range of 274400 K. We stress that free-energy results from simulations need to be corrected in order to be compared to the experiment. This is due to the fact that the thermodynamic end states accessible through simulations

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

2005-01-01

91

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

E-print Network

count level for saturated boiling of 2 propanol at T f ? 207 F c m: 0 3 26oF 58 X] 1 Figur e Page 30 A probability distribution curve at T sur f 207 F (2-propanol, T = 181 F, f 58 05 HZ, db setting = 14) 3'- A truncated probability... Counter CHAPTER VII EXPERIMENTAL RESUT TS. CHAPTER VIII DISCUSSION AN 3 CONC( U ' LORS REF RENCES. 43 43 5(i 7 'j 7 I V) 11 NOIIENCLATVRE. APPENDIX I A sample of data and results for saturated boiling of 2 ? propanol at T = 207 R o surf...

Tu, Chau Qui

2012-06-07

92

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

93

To boil or not to boil -- A study of bubble embryo dormancy limits  

SciTech Connect

In the literature, particularly for refrigerants, experimental studies on the superheat required to initiate nucleate boiling tend to be widely scattered, not only among investigators but even for repeated tests by the same investigator. This study provides an explanation of why this occurs and how to avoid such scatter in future tests. With few exceptions, only re-entrant surface cavities are capable of containing dormant vapor bubble embryos. These dormant embryos are essential to initiate nucleate boiling from a cavity. The temperature (wall superheat) range over which an embryo is stable depends upon the cavity shape, neck size, and the fluid surface tension and thermal properties. Above the upper wall-superheat limit, nucleate boiling occurs. Below the lower limit, the embryo will quench (vanish) and cannot be reactivated by increasing the wall superheat. This study makes the following points, for a given cavity shape, fluid, and pressure (1) The larger the cavity neck radius, the smaller the wall-superheat range over which an embryo can exist. (2) Upon cooling any surface, the boiling cavity with the smallest neck radius will be the first to stop boiling but will require the greatest reduction in wall superheat to quench its embryo. (3) Each site that retains a (dormant) vapor embryo will resume boiling at the same wall-superheat at which it ceased boiling. (4) Small cavities can have a shape such that their vapor embryos will always exist, regardless of the wall temperature. Boiling can always be reinitiated from them. (5) Any wall subject to boiling has a memory. The greater the past wall-subcooling, the greater will be the wall-superheat required to initiate boiling. (6) The wall memory can be erased with sufficient wall-superheat and the presence of vapor.

Martin-Dominguez, I.R. [Inst. Politecnico Nacional-CIIDIR Unidad Durango, Durango City (Mexico); McDonald, T.W. [Univ. of Windsor, Ontario (Canada)

1997-12-31

94

Comparative study of water boiling in a vertical tube under temperature-controlled or heat-flux-controlled boundary conditions. [LMFBR  

Microsoft Academic Search

The Simulant Boiling Flow Visualization (SBFV) loop is an experimental facility where natural-convection boiling of water was accomplished in a transparent vertical tube by using hot glycerine; thus, direct observation was possible. As a result, heating was obtained through a temperature-controlled rather than a power-controlled boundary condition. To compare the SBFV data with previous experiments using a stainless steel test

Carbajo

1983-01-01

95

Numerical modelling of temperature fields in the flow boiling liquid through a vertical minichannel with an enhanced heating surface  

NASA Astrophysics Data System (ADS)

The paper presents results of heat transfer research on flow boiling in a rectangular minichannel positioned vertically, with an enhanced surface. One of the channel walls was made of thin foil powered by direct current. This foil is enhanced on the side contacting fluid in the minichannel. It is possible to observe both surfaces of the minichannel through two openings covered with glass panes. One allows detecting temperature of the plain side of the foil by liquid crystal thermography. The opposite surface of the minichannel (from the enhanced side of the foil) can be observed through the other glass pane. The observations of the flow structures allowed to calculate the void fraction for some cross-sections of selected two phase flow images. In mathematical modelling of the considered process stationary heat transfer in a glass pane, heating foil and boiling liquid can be described with Laplace equation, Poisson equation and energy equation, respectively. For completeness of the model a corresponding system of boundary conditions was given. The two-dimensional temperature fields of glass pane, heating foil and fluid was computed with the Trefftz method. The equalizing calculus used to smooth the measured data has reduced errors.

Ho?ejowska, Sylwia; Piasecka, Magdalena

2014-03-01

96

Ch.5 Global Temperatures Temperature Concepts  

E-print Network

and Heat #12; Fahrenheit (ºF) ice melting point at 32ºF, boiling point of water at 212ºF Celsius (ºC) ice melting point at 0ºC, boiling point of water at sea level at 100 ºC Kelvin (K) Absolute zero cover Land-water heating differences Principal Temperature Controls #12;Latitude and Temperature From

Pan, Feifei

97

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 85C 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

98

Effects of Micro/Nano-Scale Surface Characteristics on the Leidenfrost Point Temperature of Water  

NASA Astrophysics Data System (ADS)

In recent film boiling heat transfer studies with nanofluids, it was reported that deposition of nanoparticles on a surface significantly increases the nominal minimum heat flux (MHF) or Leidenfrost Point (LFP) temperature, considerably accelerating the transient cooling of overheated objects. It was suggested that the thin nanoparticle deposition layer and the resulting changes in the physico-chemical characteristics of the hot surface, such as surface roughness height, wettability and porosity, could greatly affect quenching phenomena. In this study, a set of water-droplet LFP tests are conducted using custom-fabricated surfaces which systemically separate the effects of surface roughness height (0-15 um), wettability (0-83) and nanoporosity (?23 nm). In addition, high-speed imaging of the evaporating droplets is used to explore the influence of these surface characteristics on the intermittent solid-liquid contacts in film boiling. The obtained results reveal that nanoporosity (not solely high surface wettability) is the crucial feature in efficiently increasing the LFP temperature by initiating heterogeneous nucleation of bubbles during short-lived solid-liquid contacts, which results in disruption of the vapor film, and that micro-posts on the surface intensify such effects by promoting intermittent liquid-surface contacts.

Kim, Hyungdae; Truong, Bao; Buongiorno, Jacopo; Hu, Lin-Wen

99

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

100

THE EFFECT OF TEMPERATURE ON THE ABSORPTION OF WATER BY SODA-BOILED COTTON  

Microsoft Academic Search

Little work has hitherto been published on the effect of temperature on the absorption of water by cotton, and no data were available for temperatures higher than 38C. The present experiments deal with the absorption of water by cotton, at all humidities and at temperatures up to 110C., the data being therefore of practical application not only to the testing

Alexander Robert Urquhart; Alexander Mitchell Williams

1924-01-01

101

Temperature (T) degrees Celsius (oC) arbitrary scale from 0oC at melting point of ice to 100oC at  

E-print Network

C at melting point of ice to 100oC at boiling point of water Also (Kelvin, K) = oC plus 273.15 0 K is absolute be much stronger than it is (ie larger drop of temperature with altitude) without the global water cycle ­ a measure of the amount of invisible (or gaseous) water (vapour) dissolved in the air relative

Allan, Richard P.

102

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

E-print Network

and thermal transport processes, resulting in enhanced local and global heat flux values. Boiling incipience and liquid subcooling (e.g. at boiling inception and at critical heat flux). These enhancements are primar is clamped on a constant heat flux type calorimeter consisting of a vertical copper cylinder with embedded

Banerjee, Debjyoti

103

Frequency analysis of fluctuations of the temperature of a heater and of sound noise in boiling used for the diagnostics of the changes in the heat-transfer regimes  

NASA Astrophysics Data System (ADS)

The present paper reports the results of the experimental investigations into the density of distribution of the temperature and sound noise in boiling on a heat-releasing surface. The experiments were carried out with the heater in a pool of water subcooled below the saturation temperature at the atmospheric pressure. There has been established a correlation between spectral characteristics of temperature fluctuations and sound noise associated with boiling. On the basis of the analysis of spectral characteristics and the density of distribution of temperature fluctuations, the method for the classification of boiling regimes has been suggested.

Deev, V. I.; Kutsenko, K. V.; Lavrukhin, A. A.; Maslov, Yu. A.; Delov, M. I.

2014-08-01

104

Boiling liquid cauldron status report  

SciTech Connect

The progress made over the past year in assessing the feasibility of the high-temperature, boiling cauldron blanket concept for the tanden mirror reactor is reviewed. The status of the proposed experiments and recently revised estimates of the vapor void fraction in the boiling pool are discussed.

Hoffman, M.A.

1980-12-28

105

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

106

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...

107

On the Estimations of Micelle-Water Partition Constants for Solutes from Their Octanol-Water Partition Constants, Normal Boiling Points, Aqueous Solubilities, and Group and Bond Contribution Schemes  

Microsoft Academic Search

Five different estimation procedures for micelle-water partition constants for organic solutes are discussed. The procedures are based on 1) knowledge of octanol-water partition constants for the solutes, 2) aqueous solubilities of the solutes, 3) normal boiling points of the solutes, 4) a bond contribution scheme, and 5) a group contribution scheme. Available data in the literature including our own are

K. T. Valsaraj; L. J. Thibodeaux

1990-01-01

108

4-50 A vertical piston-cylinder device is filled with water and covered with a 20-kg piston that serves as the lid. The boiling temperature of water is to be determined.  

E-print Network

that serves as the lid. The boiling temperature of water is to be determined. Analysis The pressure/m1000 kPa1 m0.01 )m/skg)(9.81(20 kPa)(100 22 2 atm ¸ ¸ ¹ · ¨ ¨ © § A mg PP The boiling temperature4-24 4-50 A vertical piston-cylinder device is filled with water and covered with a 20-kg piston

Bahrami, Majid

109

In-situ Stress Measurements on SUS316L Stainless Steel in High Temperature Water Simulated Boiling Water Reactor  

Microsoft Academic Search

An in-situ straining device has been developed, which enables one to apply a load of 240 N to a specimen in hot water at 561 K and a pressure of 8 MPa, simulating the environment in a boiling water reactor (BWR). The device is equipped with sapphire glass windows for a light path, that is, the device can be used

A. Yamamoto; S. Nakahigashi; M. Terasawa; T. Mitamura; Y. Akiniwa; T. Yamada; L. Liu; T. Shobu; H. Tsubakino

2007-01-01

110

Ferredoxin from the hyperthermophile Thermotoga maritima is stable beyond the boiling point of water 1 1 Edited by R Huber  

Microsoft Academic Search

Heat-stable proteins from hyperthermophilic microorganisms are ideally suited for investigating protein stability and evolution. We measured with differential scanning calorimetry and optical absorption spectroscopy the thermal stability of [4Fe-4S] ferredoxin from Thermotoga maritima (tfdx), which is a small electron transfer protein. The results are consistent with two-state unfolding at the record denaturation temperature of 125C. According to the crystal structure

Wolfgang Pfeil; Ulrike Gesierich; Gerd R Kleemann; Reinhard Sterner

1997-01-01

111

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

112

Confinement by carbon nanotubes drastically alters the boiling and critical behavior of water droplets.  

PubMed

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 low. 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. PMID:22352413

Chaban, Vitaly V; Prezhdo, Victor V; Prezhdo, Oleg V

2012-03-27

113

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 of water at 1 atm Celsius 273.15 C 17.8 C 0 C 25 C 100 C Fahrenheit 459.67 F 0 F 32 F 77 F 212 F Kelvin 0K

Boyd, Sylke

114

2-80 The average temperature of the atmosphere is expressed as Tatm = 288.15 6.5z where z is altitude in km. The temperature outside an airplane cruising at 12,000 m is to be determined.  

E-print Network

temperature scale is proposed, and a value of 1000 S is assigned to the boiling point of water. The ice point it differs from the other absolute temperature scales by a constant only. The boiling temperature of water scales are related to each other by T S T K( ) ( ) . ( ) 1000 373.15 26799 T K The ice point of water

Bahrami, Majid

115

Enhanced convective and film boiling heat transfer by surface gas injection  

SciTech Connect

Heat transfer measurements were made for stable film boiling of water over a horizontal, flat stainless steel plate from the minimum film boiling point temperature, T{sub SURFACE} {approximately}500K, to T{sub SURFACE} {approximately}950K. The pressure at the plate was approximately 1 atmosphere and the temperature of the water pool was maintained at saturation. The data were compared to the Berenson film-boiling model, which was developed for minimum film-boiling-point conditions. The model accurately represented the data near the minimum film-boiling point and at the highest temperatures measured, as long it was corrected for the heat transferred by radiation. On the average, the experimental data lay within {plus_minus}7% of the model. Measurements of heat transfer were made without film boiling for nitrogen jetting into an overlying pool of water from nine 1-mm- diameter holes, drilled in the heat transfer plate. The heat flux was maintained constant at approximately 26.4 kW/m{sup 2}. For water-pool heights of less than 6cm the heat transfer coefficient deceased linearly with a decrease in heights. Above 6cm the heat transfer coefficient was unaffected. For the entire range of gas velocities measured [0 to 8.5 cm/s], the magnitude of the magnitude of the heat transfer coefficient only changed by approximately 20%. The heat transfer data bound the Konsetov model for turbulent pool heat transfer which was developed for vertical heat transfer surfaces. This agreement suggests that surface orientation may not be important when the gas jets do not locally affect the surface heat transfer. Finally, a database was developed for heat transfer from the plate with both film boiling and gas jetting occurring simultaneously, in a pool of water maintained at its saturation temperature. The effect of passing nitrogen through established film boiling is to increase the heat transfer from that surface. 60 refs.

Duignan, M.R.; Greene, G.A. [Brookhaven National Lab., Upton, NY (United States); Irvine, T.F., Jr. [State Univ. of New York, Stony Brook, NY (United States). Dept. of Mechanical Engineering

1992-04-01

116

Enhanced convective and film boiling heat transfer by surface gas injection  

SciTech Connect

Heat transfer measurements were made for stable film boiling of water over a horizontal, flat stainless steel plate from the minimum film boiling point temperature, T{sub SURFACE} {approximately}500K, to T{sub SURFACE} {approximately}950K. The pressure at the plate was approximately 1 atmosphere and the temperature of the water pool was maintained at saturation. The data were compared to the Berenson film-boiling model, which was developed for minimum film-boiling-point conditions. The model accurately represented the data near the minimum film-boiling point and at the highest temperatures measured, as long it was corrected for the heat transferred by radiation. On the average, the experimental data lay within {plus minus}7% of the model. Measurements of heat transfer were made without film boiling for nitrogen jetting into an overlying pool of water from nine 1-mm- diameter holes, drilled in the heat transfer plate. The heat flux was maintained constant at approximately 26.4 kW/m{sup 2}. For water-pool heights of less than 6cm the heat transfer coefficient deceased linearly with a decrease in heights. Above 6cm the heat transfer coefficient was unaffected. For the entire range of gas velocities measured (0 to 8.5 cm/s), the magnitude of the magnitude of the heat transfer coefficient only changed by approximately 20%. The heat transfer data bound the Konsetov model for turbulent pool heat transfer which was developed for vertical heat transfer surfaces. This agreement suggests that surface orientation may not be important when the gas jets do not locally affect the surface heat transfer. Finally, a database was developed for heat transfer from the plate with both film boiling and gas jetting occurring simultaneously, in a pool of water maintained at its saturation temperature. The effect of passing nitrogen through established film boiling is to increase the heat transfer from that surface. 60 refs.

Duignan, M.R.; Greene, G.A. (Brookhaven National Lab., Upton, NY (United States)); Irvine, T.F., Jr. (State Univ. of New York, Stony Brook, NY (United States). Dept. of Mechanical Engineering)

1992-04-01

117

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

118

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

119

Melting Temperature of High-Temperature Fixed Points for Thermocouple Calibrations  

NASA Astrophysics Data System (ADS)

Thermocouples can be calibrated at pure metal ingot-based fixed points at temperatures up to the freezing point of copper (1084.62 C). For Pt/Pd thermocouples, the deviation from the accepted reference function very often takes an approximately linear form up to the copper fixed point. The calibration of Pt/Pd thermocouples may therefore be more amenable to extrapolation than that of Pt/Pt-Rh thermocouples. Here, the melting temperatures of a Co-C and a Pd-C eutectic fixed point are determined by extrapolating the deviation functions of several Pt/Pd thermocouples, after the fashion of Edler et al. The results are compared with the melting temperatures measured using non-contact radiation thermometry. The expanded uncertainty ( k = 2) of the melting temperatures determined by extrapolation of the Pt/Pd thermocouple calibrations is 0.32 C for the Co-C fixed point, and 0.49 C for the Pd-C fixed point. For both fixed points, these uncertainties are comparable to those of non-contact radiation thermometry measurements. While a number of assumptions are made in performing the extrapolation of the calibrations, the method does appear to offer a useful complement to non-contact radiation thermometry measurements.

Pearce, J. V.; Montag, V.; Lowe, D.; Dong, W.

2011-01-01

120

Simultaneous Treatment of Vapor Pressures and Related Thermal Data Between the Triple and Normal Boiling Temperatures for n-Alkanes C5-C20  

NASA Astrophysics Data System (ADS)

Experimental vapor pressures, calorimetric enthalpies of vaporization and differences between the heat capacities of the ideal gas and the liquid for n-alkanes C5 to C20 between the triple and normal boiling temperatures have been treated simultaneously. Attention was focused particularly on the region of low pressures where vapor pressure data are scarce and subject to important systematic errors. The reliability and consistency of data fro different sources was evaluated and the three parameter Cox equation was used to correlate simultaneously as a function of temperature the selected values of different properties. The recommended vapor pressures and thermal data resulting from this procedure are mutually consistent over the homologous series and present a considerable refinement particularly at lower pressures.

Růi?ka, Kv?toslav; Majer, Vladimr

1994-01-01

121

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

122

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

123

Programmed temperature vaporizing injector to filter off disturbing high boiling and involatile material for on-line high performance liquid chromatography gas chromatography with on-column transfer.  

PubMed

Insertion of a programmed temperature vaporizing (PTV) injector under conditions of concurrent solvent recondensation (CSR) into the on-line HPLC-GC interface for on-column transfer (such as the retention gap technique with partially concurrent eluent evaporation) enables filtering off high boiling or involatile sample constituents by a desorption temperature adjusted to the required cut-off. Details of this technique were investigated and optimized. Memory effects, observed when transferred liquid was sucked backwards between the transfer line and the wall of the injector liner, can be kept low by a small purge flow rate through the transfer line at the end of the transfer and the release of the liquid through a narrow bore capillary kept away from the liner wall. The column entrance should be within the well heated zone of the injector to prevent losses of solute material retained on the liner wall during the splitless period. The desorption temperature must be maintained until an elevated oven temperature is reached to prevent peak broadening resulting of a cool inlet section in the bottom part of the injector. PMID:23394744

Biedermann, Maurus; Grob, Koni

2013-03-15

124

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

125

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

126

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

127

Distributed Fiber-Bragg Grating Temperature Sensors for Real-Time Multiple-Point Temperature Monitoring  

NASA Astrophysics Data System (ADS)

Distributed fiber-optic temperature sensors (DFOTS) are being increasingly deployed in applications requiring 2D or 3D temperature profiling. Fiber Bragg Gratings (FBG's), through the shift of their Bragg wavelength, are well suited for such applications due to their immunity to electromagnetic interference and small physical size and thermal inertia of the sensing element. These characteristics are complemented by the easiness of combining individual gratings in series or parallel arrays that can monitor systems with characteristic dimensions from as small as a few millimeters to as large as several kilometers. To highlight this versatility, we report on the study of two FBG arrays for temperature monitoring. A series array obtained by inserting several discrete FBG's operating at different Bragg wavelengths on a 5-km long fiber strand is used to monitor the temperature at predetermined points along the fiber link. A second, parallel array of FBG's is used to monitor the temperature in a cross-section of a 3 ml vial containing a ferrofluid in magnetic field. The temperature resolution in both cases is better than 1 C. The longitudinal spatial resolution is 5 mm, and the lateral spatial resolution for the parallel array is better than 1 mm.

Rablau, Corneliu; Murphy, Simon

2008-03-01

128

Microchannel flow boiling mechanisms leading to burnout  

SciTech Connect

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

Landram, C.S.

1994-03-01

129

2015 Pearson Education, Inc. Chapter 5 Global Temperatures  

E-print Network

point of water at 212ºF · Celsius (°C) ­ Ice melting point at 0°C, boiling point of water at sea level and Heat Transfer #12;© 2015 Pearson Education, Inc. · Fahrenheit (°F) ­ Ice melting point at 32°F, boiling of land versus water that produce continental effects and marine effects on temperatures, and utilize

Pan, Feifei

130

Outline of Pool Boiling Experiment for Nucleate Boiling Heat Transfer by Aircraft Experiment  

Microsoft Academic Search

Investigation of mechanisms in nucleate boiling in microgravity is essential for the development of high efficiency thermal management systems in space. A transparent heating surface with multiple arrays of 88 thin film temperature sensors and mini-heaters was developed for the clarification of boiling heat transfer mechanisms in microgravity through the study of the relation between local heat transfer coefficients and

Oleg Kabov; Queeckers Patrick; Sergey Chikov; Yusuke Kotani; Yoshino Sakata; Yuka Asada; Tadashi Nagayasu; Yoichi Sato; Yasuhisa Shinmoto; Osamu Kawanami; Haruhiko Ohta

2009-01-01

131

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.

132

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

Code of Federal Regulations, 2012 CFR

...melting point information; measuring cargo temperature during discharge: Categories A, B...melting point information; measuring cargo temperature during discharge: Categories A, B...exceeds 25 mPa.s at 20 C, the temperature at which the viscosity is 25...

2012-10-01

133

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

...melting point information; measuring cargo temperature during discharge: Categories A, B...melting point information; measuring cargo temperature during discharge: Categories A, B...exceeds 25 mPa.s at 20 C, the temperature at which the viscosity is 25...

2014-10-01

134

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

Code of Federal Regulations, 2013 CFR

...melting point information; measuring cargo temperature during discharge: Categories A, B...melting point information; measuring cargo temperature during discharge: Categories A, B...exceeds 25 mPa.s at 20 C, the temperature at which the viscosity is 25...

2013-10-01

135

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

Code of Federal Regulations, 2011 CFR

...melting point information; measuring cargo temperature during discharge: Categories A, B...melting point information; measuring cargo temperature during discharge: Categories A, B...exceeds 25 mPa.s at 20 C, the temperature at which the viscosity is 25...

2011-10-01

136

Boiling temperature measurement for water, methanol, ethanol and their binary mixtures in the presence of a hydrochloric or acetic salt of mono-, di- or tri-ethanolamine at 101.3 kPa  

Microsoft Academic Search

The boiling temperature at atmospheric pressure were measured for 12 binary systems within the range T=(316 to 379) K and 7 ternary systems using a dual circulation. The systems studied contained water, methanol or ethanol with the following ionic liquids (ILs): monoethanolammonium acetate ([HEMA][Ac]), diethanolammonium acetate ([HDEA][Ac]), triethanolammonium acetate ([HTEA][Ac]) and diethanolammonium chloride ([HDEA]Cl). The experimental VLE results of the

Jun-feng Wang; Xue-mei Li; Hong Meng; Chun-xi Li; Zi-hao Wang

2009-01-01

137

Chiral interface at the finite temperature transition point of QCD  

NASA Technical Reports Server (NTRS)

The domain wall between coexisting chirally symmetric and broken symmetry regions is studied in a saddle point approximation to the effective three-flavor sigma model. In the chiral limit the surface tension varies in the range ((40 to -50)MeV)(exp 3). The width of the domain wall is estimated to be approximately or equal to 4.5 fm.

Frei, Z.; Patkos, A.

1990-01-01

138

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

139

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

140

Two-point boundary temperature control of hot strip via water cooling  

Microsoft Academic Search

This paper presents a two-point boundary temperature control system 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 basic feedforward control design to control the temperature at the second boundary point, the only measurable controlled parameter,

Nicholas S. Samaras; Marwan A. Simaan

1997-01-01

141

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

142

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.

143

Chapter 1: Measurements in ! Temperature  

E-print Network

,000,000 mL 1000 mL #12;Chapter 1: Measurements in Chemistry ! Temperature in °C Water freezing point: 0 oC boiling point: 100 oC Chapter 1: Measurements in Chemistry ! Amount Mole (mol); SI standard 1 mol contains

Zakarian, Armen

144

Cathodic polarization curves of the oxygen reduction reaction on various structural materials of boiling water reactors in high temperaturehigh purity water  

Microsoft Academic Search

Cathodic polarization curves of the O2 reduction reaction were measured by using electrodes made from typical structural materials of boiling water reactors (BWRs) to evaluate the effects of kind of material on the electrochemical corrosion potential (ECP) calculation. To estimate ECPs at any region in the BWRs on the basis of the BWR environmental conditions, anodic and cathodic polarization curves

Masahiko Tachibana; Kazushige Ishida; Yoichi Wada; Ryosuke Shimizu; Nobuyuki Ota; Nobuyoshi Hara

2012-01-01

145

Zirconium phosphate as the proton conducting material in direct hydrocarbon polymer electrolyte membrane fuel cells operating above the boiling point of water  

Microsoft Academic Search

Zirconium phosphate (ZrP) was investigated as a possible proton conductor material in direct hydrocarbon polymer electrolyte membrane (PEM) fuel cells that operate at greater temperatures than conventional PEM fuel cells. Amorphous zirconium phosphate was synthesized in this work by precipitation at room temperature via reaction of ZrOCl2 with H3PO4 aqueous solutions. The conductivity of the synthesized ZrP materials were 7.0410?5Scm?1

Amani Al-Othman; Andr Y. Tremblay; Wendy Pell; Sadok Letaief; Tara J. Burchell; Brant A. Peppley; Marten Ternan

2010-01-01

146

Defect pressure, formation volume, and temperature dependence of formation properties of point defects in ionic solids  

E-print Network

dependence of the volume and the enthalpy of formation of equilibrium defects is understood in termsDefect pressure, formation volume, and temperature dependence of formation properties of point of the temperature dependence of the shear moduli. The high-temperature anomalies of defect formation volume, tracer

Boyer, Edmond

147

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

148

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

149

Boiling on the surface of a rotating disc  

Microsoft Academic Search

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

S. Yanniotis; D. Kolokotsa

1996-01-01

150

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

Microsoft Academic Search

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

Koichi Nara

2004-01-01

151

Distributed Fiber-Bragg Grating Temperature Sensors for Real-Time MultiplePoint Temperature Monitoring  

Microsoft Academic Search

Distributed fiber-optic temperature sensors (DFOTS) are being increasingly deployed in applications requiring 2D or 3D temperature profiling. Fiber Bragg Gratings (FBG's), through the shift of their Bragg wavelength, are well suited for such applications due to their immunity to electromagnetic interference and small physical size and thermal inertia of the sensing element. These characteristics are complemented by the easiness of

Corneliu Rablau; Simon Murphy

2008-01-01

152

Curie point, susceptibility, and temperature measurements of rapidly heated ferromagnetic wires.  

PubMed

This article describes a technique to measure the temperature of a resistively heated ferromagnetic wire. The wire's temperature rapidly increases, a scenario in which a thermocouple or thermistor's thermal inertia prevents it from keeping up with the rapid temperature variation. The temperature is derived from electrical measurands (voltage and current) and time, as well as thermophysical data such as heat losses and emissivity, and is based on a dynamical thermal-electrical energy conservation principle. We go on to use our technique for the quantitative determination of the Curie point as well as the magnetic susceptibility at elevated temperatures. The results are in good agreement with accepted values. PMID:21198044

Anwar, Muhammad Sabieh; Zia, Wasif

2010-12-01

153

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

154

Applications of statistical models to synchronous climate variables: a case study of temperature and dew point for College Station, Texas  

E-print Network

Concurrent hourly temperature-dew point and temperature-dew point depression data were fitted to the bivariate normal distribution for the six months of January, March, May, July, September, and November for College Station, Texas. Calculations...

O'Brien, Charles F.

1995-01-01

155

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

156

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

157

Temperature dependence of water activity in aqueous solutions of sucrose  

Microsoft Academic Search

A comprehensive experimental data analysis was performed to evaluate the effect of temperature on the water activity coefficient and selected excess thermodynamic functions for aqueous solutions of sucrose. A four-suffix Margules equation with temperature-dependent parameters was used to fit thermodynamic data such as the vapor pressure, boiling point, osmotic coefficient, freezing point, sucrose solubility, heat of dilution and specific heat

Maciej Starzak; Mohamed Mathlouthi

2006-01-01

158

Simulation study based on the single-point temperature monitoring system of LabVIEW  

NASA Astrophysics Data System (ADS)

This paper takes LabVIEW2012 as a development platform, creating a J-type thermocouple sensor and the NI USB-6229 data acquisition card and other hardware emulation circuitry which combined with the PC designed a single-point temperature monitoring system. Through simulation experiments, the system has a collection interval, the sampling rate per channel sampling on the temperature limit set by the user function and it also has the function of real-time display the current temperature, the temperature limit alarm, maximum temperature, minimum temperature display and a temperature history data query. This system can be used for temperature monitoring of life, research, industrial control, environmental monitoring, biomedical, tobacco processing, greenhouse cultivation, livestock breeding and other fields, which has important significance and practical value.

Wu, Yongling; Yang, Na; Liu, Shuping; Pan, Xiaohui; Wang, Wenjiang

2014-12-01

159

Realization of Low-Temperature Fixed Points of the ITS-90 at NMIJ/AIST  

NASA Astrophysics Data System (ADS)

A new model of sealed cells with three thermometer wells for calibration of capsule-type thermometers at low-temperature fixed points of the International Temperature Scale of 1990 has been developed at the National Metrology Institute of Japan (NMIJ). The melting curves of Ar and O2 obtained using the new cells show very flat plateaux and a linear temperature dependence as a function of the inverse liquid fraction (1/ F) over the range 1/ F = 1 to 1/ F = 20 with a narrow melting curve width of 0.1 mK. The melting curves of Ne obtained with the new cell also show very flat plateaux and approximately linear temperature dependence versus 1/ F and a narrow melting curve width of 0.1 mK, though with a slight concave structure at high 1/ F. The melting temperatures with the new cells agree with previous NMIJ sealed cells within 10 ?K, which is similar to the reproducibility of the realization of the triple points at NMIJ. The source dependence of the triple-point temperature of Ne was investigated by filling two of the new cells from different sources of Ne. The difference in the realized triple point temperatures between the two sources is 0.031 mK, consistent with that estimated from isotope analysis. The uncertainties in the calibration of standard platinum resistance thermometers at the low-temperature fixed points are summarized. The uncertainty of the calibration at the triple point of e-H2 has been reduced to about one-third of its value without the correction by making the isotopic correction on the basis of the technical annex for the ITS-90 in the mise en pratique for the definition of the kelvin.

Nakano, T.; Tamura, O.; Sakurai, H.

2007-12-01

160

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

161

Natural saltwater upconing by boils: field measurements and numerical modeling  

NASA Astrophysics Data System (ADS)

In this study, natural saltwater upconing by boils was investigated using field measurements and numerical simulations. As one-quarter of The Netherlands lies below mean sea level, the upward flow of saline groundwater leads to the salinization of surface waters for large areas, impacting on agriculture and aquatic ecosystems. The largest seepage fluxes are found in deep polders with surface water levels maintained as low as 6 to 8 m below sea level. Recent studies showed that preferential groundwater discharge through boils is the dominant salinization source in these deep polders. Boils occur as conduits in the upper aquitard that connect the underlying aquifer to the surface through which groundwater discharges at high velocities. Groundwater preferentially discharging through boils contains up to hundred times more salt than diffuse forms of groundwater discharge. The upconing of deep saline groundwater induced by the localized, high-velocity flow through boils is the mechanism that leads to the high boil water salinities. The local boil system and associated natural salt water upconing were explored in the field in three different hydrogeological settings. Measurements of the aquifer salinity distribution, temperature, boil discharge, boil salinity and aquifer heads showed that the preferential flow through boils creates localized and narrow saltwater upconing spikes. The possibility to seal the boil at its source vent as a measure to abate surface water salinization was explored in the field. Numerical modeling with the code SEAWAT was applied to investigate the upconing processes in more detail. The field measurements were largely reproduced by the numerical model. 56 different cases, which differ in aquifer properties, salinity distribution, boil discharge and lateral regional flow,were defined to determine the most important boil salinity controlling factors. For each upconing case the sources of boil water, i.e. the contribution to boil discharge from different aquifer depths, were derived from the model results. The contributing depth distributions showed a form opposite to the aquifer salinity distribution, with higher contributions from shallower and less saline groundwater. This illustrates the importance of the density distribution in the aquifer on the saltwater upconing mechanism. The numerical results showed that the most important factors controlling the contributing depths and boil salinity are boil discharge, the horizontal hydraulic conductivity of the aquifer, the depth of the interface and the salinity (and therefore density) contrast within the aquifer. Within a small area of clustered boils, boil salinity varies between individual boils and is determined by the combination of its discharge and its position within the boil area, whereas the total discharge of boil clusters is the principal factor that controls natural saltwater upconing and total salt loads. Regional lateral flow had a large impact on the upconing mechanism in terms of flow patterns but had a minor effect on both the contribution of saline and fresh groundwater to boil discharge and boil salinity. Both measurements and model results will be presented at the EGU.

de Louw, Perry; Vandenbohede, Alexander; Werner, Adrian; Oude Essink, Gualbert

2013-04-01

162

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

163

Solar water boiling device  

Microsoft Academic Search

A solar water boiling device having an insulated enclosure with an opening in its front provided with a light-transmissive cover. Within the enclosure is a water container preferably formed as a discrete unit separable from the enclosure. The enclosure provides insulation such that heat losses through its side and rear walls are small compared with heat loss through the cover.

Burkhardt

1985-01-01

164

Physics based boiling simulation  

Microsoft Academic Search

In order to animate complex fluid motion, computer animators have to rely on simulation systems that automat- ically generate the dynamics in a physics-based manner. We focus in this paper on the phenomenon of boiling, which, due to its complex formulation and physics, has seen very little work done in the graphics field. We pro- pose a new Eulerian method

Viorel Mihalef; B. Unlusu; Dimitris N. Metaxas; Mark Sussman; M. Yousuff Hussaini

2006-01-01

165

Microbiological effectiveness of disinfecting water by boiling in rural Guatemala.  

PubMed

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

Rosa, Ghislaine; Miller, Laura; Clasen, Thomas

2010-03-01

166

Melting Temperatures of Eutectic Fixed-Point Cells Usable for the Calibration of Contact Thermometers  

NASA Astrophysics Data System (ADS)

The objective of the present investigation was the determination of the melting temperatures of the eutectic compounds Fe C, Co C, and Ni C. Six eutectic fixed-point cells of the Physikalisch-Technische Bundesanstalt (PTB) (Fe C1, Fe C2, Co C1, Co C2, Ni C1, and Ni C2) and two cells of the Brazilian National Metrological Institute (Inmetro) (Fe C1V and Ni C1V), useable for the calibration of contact thermometers, were investigated. Their melting temperatures were calculated by extrapolation of the emf-temperature characteristics of four stable Pt/Pd thermocouples, which were calibrated at the eutectic fixed points and at conventional fixed points of the International Temperature Scale of 1990 (ITS-90). On the basis of the eight eutectic fixed-point cells and seven independent calibration runs, the melting temperatures of the Fe C, Co C, and Ni C eutectics resulted in 1153.67 0.15C, 1323.81 0.27C, and 1328.48 0.20C, respectively, with expanded uncertainties corresponding to a coverage factor of k = 2.

Edler, F.; Ederer, P.; Baratto, A. C.; Vieira, H. D.

2007-12-01

167

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

SciTech Connect

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

Machin, G.; Woolliams, E. R. [National Physical Laboratory (NPL), Hampton Road, Teddington, Middlesex,TW11 0LW (United Kingdom)] [National Physical Laboratory (NPL), Hampton Road, Teddington, Middlesex,TW11 0LW (United Kingdom); Anhalt, K. [Physikalisch-Technische Bundesanstalt (PTB), Abbestrasse 2-12, 10587 Berlin (Germany)] [Physikalisch-Technische Bundesanstalt (PTB), Abbestrasse 2-12, 10587 Berlin (Germany); Bloembergen, P. [National Institute of Metrology (NIM), Bei San Huan Dong Lu No. 18, Beijing, 100013 (China)] [National Institute of Metrology (NIM), Bei San Huan Dong Lu No. 18, Beijing, 100013 (China); Sadli, M. [Laboratoire Commun de Mtrologie (LNE-Cnam), 61, rue du Landy, 93210 Saint-Denis, La Plaine (France)] [Laboratoire Commun de Mtrologie (LNE-Cnam), 61, rue du Landy, 93210 Saint-Denis, La Plaine (France); Yamada, Y. [National Measurement Institute of Japan (NMIJ), AIST, Tsukuba, Ibaraki (Japan)] [National Measurement Institute of Japan (NMIJ), AIST, Tsukuba, Ibaraki (Japan)

2013-09-11

168

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

169

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

170

Little low-power boiling never hurt anybody. [LMFBR  

SciTech Connect

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

Dunn, F.E.

1985-01-01

171

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

172

Experimental study on subcooled flow boiling on heating surfaces with different thermal conductivities  

NASA Astrophysics Data System (ADS)

Subcooled flow boiling is generally characterized by high heat transfer capacity and low wall superheat, which is essential for cooling applications requiring high heat transfer rate, such as nuclear reactors and fossil boilers. In this study, subcooled flow boiling on copper and stainless steel heating surfaces was experimentally investigated from both macroscopic and microscopic points of view. Flow boiling heat flux and heat transfer coefficient were experimentally measured on both surfaces under different conditions, such as pressure, flow rate and inlet subcooling. Significant boiling heat transfer coefficient differences were found between the copper and the stainless steel heating surfaces. To explain the different flow boiling behaviors on these two heating surfaces, nucleation site density and bubble dynamics were visually observed and measured at different experimental conditions utilizing a high-speed digital video camera. These two parameters are believed to be keys in determining flow boiling heat flux. Wall superheat, critical cavity size and wall heat flux were used to correlate with nucleation site density data. Among them, wall heat flux shows the best correlation for eliminating both pressure and surface property effects. The observed nucleation site distribution shows a random distribution. When compared to the spatial Poisson distribution, similarity between them was found, while the measured nucleation site distribution is more uniform. From experimental observations, for the two surface materials investigated, which have similar surface wettability but sharply different thermal properties, bubble dynamics displayed fairly similar behavior. The obtained experimental results indicate that thermal conductivity of heating surface material plays an important role in boiling heat transfer. This is due to thermal conductivity having a significant impact on the lateral heat conduction at the heating surface and consequently temperature uniformity of the heating surface. A model was then developed and solved numerically for heat conduction at the heating surface when bubbles are present. Several key parameters which impact lateral heat conduction and surface temperature profile were studied. These parameters include material thermal conductivity, bubble size, heating surface thickness, etc. Numerical results show that, temperature profile on the heating surface tends to be more uniform and have a lower average value on a heating surface with higher thermal conductivity, which agrees well with the experimental observation.

Zou, Ling

173

A probe for measuring temperature and pressure at the same points in a gas stream  

NASA Technical Reports Server (NTRS)

Design features and characteristics of a means for measuring total temperature and total pressure at a single point in a gas stream are presented. A rake that provides five such combination measurements is described. Experimental data are included for the aerodynamic recovery and time response of the temperature sensor and for the flow-angle sensitivity of both the temperature and pressure sensors. Data were obtained over a subsonic Mach number range of 0.3 to 0.9 as well as at a Mach number of 1.4.

Krause, L. N.; Glawe, G. E.; Dudzinski, T. J.

1972-01-01

174

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.; Bse, N.; Mitter, H.; Mutter, D.; Vicente, T.

2012-09-01

175

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

176

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

177

Finite-temperature three-point function in 2D CFT  

NASA Astrophysics Data System (ADS)

We calculate the finite temperature three-point correlation function for primary fields in a 2D conformal field theory in momentum space. This result has applications to any strongly coupled field theory with a 2D CFT dual, as well as to Kerr/CFT.

Becker, Melanie; Cabrera, Yaniel; Su, Ning

2014-09-01

178

Measurement of Sticky Point Temperature of Coffee Powder with a Rheometer  

Technology Transfer Automated Retrieval System (TEKTRAN)

Sticky point temperature (Ts) measurement for hygroscopic food and biomaterial powders is traditionally performed with complex glass instruments. This property is used to characterize material stickiness, which substantially affects the flow and physical behavior of powders. In this research study w...

179

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

180

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

SciTech Connect

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

Sun, J.; Zhang, J. T.; Ping, Q. [National institute of Metrology, Beijing (China)] [National institute of Metrology, Beijing (China)

2013-09-11

181

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

182

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, 1700C, 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

183

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

184

Cryogenic Boil-Off Reduction System Testing  

NASA Technical Reports Server (NTRS)

Cryogenic propellants such as liquid hydrogen (LH2) and liquid oxygen (LO2) are a part of NASA's future space exploration due to the high specific impulse that can be achieved using engines suitable for moving 10's to 100's of metric tons of payload mass to destinations outside of low earth orbit. However, the low storage temperatures of LH2 and LO2 cause substantial boil-off losses for missions with durations greater than several days. The losses can be greatly reduced by incorporating high performance cryocooler technology to intercept heat load to the propellant tanks and by the integration of self-supporting multi-layer insulation. The active thermal control technology under development is the integration of the reverse turbo- Brayton cycle cryocooler to the propellant tank through a distributed cooling network of tubes coupled to a shield in the tank insulation and to the tank wall itself. Also, the self-supporting insulation technology was utilized under the shield to obtain needed tank applied LH2 performance. These elements were recently tested at NASA Glenn Research Center in a series of three tests, two that reduced LH2 boil-off and one to eliminate LO2 boil-off. This test series was conducted in a vacuum chamber that replicated the vacuum of space and the temperatures of low Earth orbit. The test results show that LH2 boil-off was reduced 60% by the cryocooler system operating at 90K and that robust LO2 zero boil-off storage, including full tank pressure control was achieved.

Plachta, David W.; Johnson, Wesley L.; Feller, Jeffrey R.

2014-01-01

185

Heat transfer analyses of liquid heated boiling fluids with attention to transition boiling  

Microsoft Academic Search

Four major methods of analysis were developed for the turbulent flow of a liquid metal in an annulus under a thermally developing condition with arbitrary axial wall temperature distribution. The methods were applied to measurements made in two large scale test facilities, at Argonne National Laboratory and Westinghouse Electric Corp., where water boiling inside of a tube was the forcing

Shin

1986-01-01

186

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

187

Natural Convection Boiling Potassium Flow Loop  

NASA Astrophysics Data System (ADS)

The conceptual design of a natural convection boiling potassium flow loop (at the 1 gm/sec flow rate) is described. This flow loop is designed to study the effects of solute mass transport between various solid phase construction materials and the potassium working fluid as well as the effects of the boiling heat transfer coefficient on such parameters as: wetting contact angle, artificial cavity size and surface number density, viscosity, surface tension, fluid velocity, and the acceleration field (among other things). For mass transport, the equilibrium parameters (that is: Gibbs Free Energy of Formation, Enthalpy of Formation, Entropy, and activity coefficient) for each important solute species will be estimated along with the temperature dependent forward kinetic rate constants between the solid and liquid phases. For the boiling heat transfer coefficient, the effects of wall superheat and hydraulic stability will also be investigated. The natural convection boiling potassium flow loop hardware will be constructed from special stainless steels (so that vacuum operation with refractory materials is not required) and will contain appropriate oxygen getters and electrochemical cells for controlling the amount of detrimental compound oxides in the potassium melt.

Shimkevich, Alexander L.; Ivanovsky, Michael N.; Morozov, Valentine A.; Sprouse, Kenneth M.

1994-07-01

188

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

189

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

190

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

191

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

192

Estimation of the global average temperature with optimally weighted point gauges  

NASA Technical Reports Server (NTRS)

This paper considers the minimum mean squared error (MSE) incurred in estimating an idealized Earth's global average temperature with a finite network of point gauges located over the globe. We follow the spectral MSE formalism given by North et al. (1992) and derive the optimal weights for N gauges in the problem of estimating the Earth's global average temperature. Our results suggest that for commonly used configurations the variance of the estimate due to sampling error can be reduced by as much as 50%.

Hardin, James W.; Upson, Robert B.

1993-01-01

193

How Does Water Boil?  

NASA Astrophysics Data System (ADS)

Insight into the boiling of water is obtained from molecular dynamics simulations. The process is initiated by the spontaneous formation of small vacuum cavities in liquid water. By themselves, these defects are very short lived. If, however, several cavities occur at close distances, they are likely to merge into larger vacuum holes. At the liquid-vapor interfaces, single or small groups of water molecules tend to leave the liquid surface. Once the system is propagated beyond the transition state, these evaporation events outnumber the competing reintegration into the hydrogen-bonded network.

Zahn, Dirk

2004-11-01

194

How does water boil?  

PubMed

Insight into the boiling of water is obtained from molecular dynamics simulations. The process is initiated by the spontaneous formation of small vacuum cavities in liquid water. By themselves, these defects are very short lived. If, however, several cavities occur at close distances, they are likely to merge into larger vacuum holes. At the liquid-vapor interfaces, single or small groups of water molecules tend to leave the liquid surface. Once the system is propagated beyond the transition state, these evaporation events outnumber the competing reintegration into the hydrogen-bonded network. PMID:15601117

Zahn, Dirk

2004-11-26

195

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

196

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

197

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

Microsoft Academic Search

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

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

1991-01-01

198

Temperature-dependent heat sources or sinks in a stagnation point flow  

Microsoft Academic Search

SummaryAn analytical study has been made to determine the heat transfer characteristics of a stagnation point flow in which there\\u000a are temperature-dependent heat sources or sinks. Results have been obtained for both strong and weak sources or sinks for\\u000a a Prandtl number of 0.7. An analytical method, applicable to all Prandtl numbers, was utilized which circumvented the need\\u000a for extensive

E. M. Sparrow; R. D. Cess

1961-01-01

199

Polarization-Switching FBG Interrogator for Distributed Point Measurement of Magnetic Field Strength and Temperature  

Microsoft Academic Search

We report on the design and implementation of a novel optical fiber system for dual point measurement of magnetic field strength and temperature. The system incorporates a polar- ization switching technique that enables ratiometric processing of the orthogonal circularly polarized reflections from low-bire- fringence fiber Bragg gratings. High-resolution magneto-optical measurement of either static or dynamic magnetic fields may be achieved

Philip Orr; Pawe? Niewczas

2011-01-01

200

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

201

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

202

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

203

Non-equilibrium critical point in Be-doped low-temperature-grown GaAs  

NASA Astrophysics Data System (ADS)

We studied the transition process of antisite arsenic defects in Be-doped low-temperature-grown GaAs layers by measuring the magnetization. This material exhibits bistability at non-equilibrium; at a fixed temperature in a fixed magnetic field a sample relaxes towards two different states, depending on the preceding cooling process. We observed anomalously large magnetization fluctuations in macroscopic samples during the transition from bistability to monostability with gradual change of the temperature. Slowing down of the relaxation of the magnetization is observed as a sample approaches the transition into monostability. Large fluctuations observed from a two-piece sample exhibit intermittent bursts by high-pass filtering and follow a generalized Gumbel probability density distribution. These observations suggest a possibility of the occurrence of a non-equilibrium critical point in this material. Microscopic processes underlying the observed phenomena are discussed with results of first-principles calculations of strain fields.

Ambri Mohamed, Mohd; Tien Lam, Pham; Otsuka, N.

2013-02-01

204

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

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

205

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

SciTech Connect

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

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

2012-12-15

206

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

207

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

208

Effect of additives on the cloud point temperature of 2-hydroxy-3-isopropoxypropyl starch solutions.  

PubMed

Temperature-responsive polymers with a lower critical solution temperature (LCST) have attracted much attention in biomedical and biotechnological fields. It is important to tune their cloud point temperature (Tc) in a broad temperature range as desired by the applications. In this study, new thermo-responsive 2-hydroxy-3-isopropoxypropyl starches (HIPS) was synthesized using Hylon V starch as raw material and isopropyl glycidyl ether as hydrophobic reagent. The phase transition behavior of HIPS and their Tc were determined by spectrophotometry. The effects of several conditions on the Tc of the HIPS were also investigated, which indicated that varying the molar substitution (MS) of HIPS can adjust Tc in a broad temperature range from 69 to 28 C by changing the hydrophobic-hydrophilic balance of starch. The phase transition became fast and the Tc decreased with increasing polymer concentration. The effect of a series of sodium salts on the Tc of aqueous HIPS solutions was reported and the effectiveness of ions follows a trend, known as Hofmeister series. Several organic solvents were selected and the organic additives with small molecular weight can also regulate the Tc of HIPS in a certain range by changing the polymer-water interactions. PMID:24007363

Ju, Benzhi; Cao, Shouqin; Zhang, Shufen

2013-10-01

209

Boiling local heat transfer enhancement in minichannels using nanofluids  

NASA Astrophysics Data System (ADS)

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.

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

2013-03-01

210

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

211

PERSPECTIVES OF HIGH TEMPERATURE ELECTROLYSIS USING S. H. JENSEN and M. MOGENSEN  

E-print Network

. All heat sources with temperatures above 100 °C (the boiling point of water) are extremely beneficial1 PERSPECTIVES OF HIGH TEMPERATURE ELECTROLYSIS USING SOEC S. H. JENSEN and M. MOGENSEN Materials be produced. Here the production of H2 and CH4 using high temperature electrolysis of steam and CO2

212

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

213

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

NASA Astrophysics Data System (ADS)

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 of all measured electromotive forces at the inflection points of the melting curves amounts to a value of about 0.06 C. No drift in the melting temperature was observed. Therefore, the Co-C eutectic fixed point cell can be used as an adequate transfer standard for dissemination of the International Temperature Scale of 1990 (ITS-90) in the temperature range above the freezing point of copper.

Edler, F.; Baratto, A. C.

2005-08-01

214

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

215

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

216

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

NASA Astrophysics Data System (ADS)

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

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

2013-06-01

217

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

218

Boiling phenomena in near-critical SF6 observed in weightlessness  

NASA Astrophysics Data System (ADS)

Boiling phenomena in the two-phase region of SF6 close to its critical point have been observed using the high-quality thermal and optical environment of the CNES dedicated facility ALI-DECLIC on board the International Space Station (ISS). The weightlessness environment of the fluid, which cancels buoyancy forces and favorites the three-dimensional spherical shape of the gas bubble, is proven to be an irreplaceable powerful tool for boiling studies. To identify each key mechanism of the boiling phenomena, the ALI-DECLIC experiments have benefited from (i) the well-adapted design of the test cells, (ii) the high-fidelity of the ALI insert teleoperation when long-duration experiment in stable thermal and microgravity environment are required and (iii) the high repeatability of the controlled thermal disturbances. These key mechanisms were observed by light transmission and interferometry technique independently with two sample cells filled with pure SF6 at a near-critical density. The fluid samples are driven away from thermal equilibrium by using a heater directly implemented in the fluid, or a surface heater on a sapphire optical window. In the interferometry cell, the bulk massive heater distinguishes two symmetrical two-phase domains. The modification of the gas bubble shape is observed during heating. In the direct observation cell, the gas bubble is separated by a liquid film from the thin layered transparent heater deposited on the sapphire window. The liquid film drying and the triple contact line motion during heating are observed using light transmission. The experiments have been performed in a temperature range of 10 K below the critical temperature Tc, with special attention to the range 0.1 mK?T-T?3 mK very close to the critical temperature. The unique advantage of this investigation is to provide opportunities to observe the boiling phenomena at very low heat fluxes, thanks to the fine adjustment of the liquid-vapor properties, (e.g. surface tension), by precise control of the distance to the critical point. We present the new observations of the gas bubble spreading over the heating surface which characterizes the regime where vapor bubbles nucleate separately and grow, as well as liquid drying, vapor film formation, triple contact line motion, which are the key mechanisms at the origin of the boiling crisis when the formed vapor film reduces the heat transfer drastically at the heater wall.

Lecoutre, Carole; Garrabos, Yves; Beysens, Daniel; Nikolayev, Vadim; Hahn, Inseob

2014-07-01

219

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

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

220

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

PubMed

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

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

2013-06-01

221

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

222

Complex Saddle Points and Disorder Lines in QCD at finite temperature and density  

E-print Network

The properties and consequences of complex saddle points are explored in phenomenological models of QCD at non-zero 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 PNJL 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 $\\left\\langle {\\rm Tr}_{F}P\\right\\rangle $ and $\\left\\langle {\\rm Tr}_{F}P^{\\dagger}\\right\\rangle $, and that is confined to small region in the $\\mu-T$ 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 $\\mu-T$ plane have the potential to clearly discriminate between different models of confinement.

Hiromichi Nishimura; Michael C. Ogilvie; Kamal Pangeni

2014-11-18

223

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

224

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

225

Correlation for the variations with temperature of solute solubilities in high temperature water  

Microsoft Academic Search

Methods for estimating solute solubilities in high temperature water both below and above its boiling point (under pressure) are needed for applications of this medium in processing applications such as sub-critical water extraction, reaction chemistry in heated water, and in the material sciences. There is a paucity of data and correlative methods for estimating solute solubilities under these conditions; the

Jos M. del Valle; Juan C. de la Fuente; Keerthi Srinivas; Jerry W. King

2011-01-01

226

Natural-convection film-boiling heat transfer. IV - Experiments of subcooled film boiling with long vapor film  

NASA Astrophysics Data System (ADS)

Heat transfer in natural-convection film boiling with long vapor film is investigated experimentally. Experiments of film boiling on horizontal cylinders of large diameter and long vertical cylinders are conducted to investigate the effect of liquid subcooling on film-boiling heat transfer. The test liquid is R-113 at atmospheric pressure. For cylinders of both types, local heat transfer coefficients of saturated and subcooled film boiling are much higher than the predictions from two-phase boundary layer theory. In the case of vertical cylinders, local heat transfer coefficients do not depend on the distance from the stagnation point even if the liquid is subcooled. In the case of horizontal cylinders of large diameter, the local value of saturated film boiling does not strongly depend on the distance from the stagnation point, but it comes to depend on the distance with increasing subcooling. In particular, the local value reaches a maximum at a distance from the stagnation point. As for averaged heat transfer coefficients of horizontal cylinders of large diameter, they increase with increasing subcooling but do not depend on the diameter even under subcooled conditions.

Ohtake, Hiroyasu; Nishio, Shigefumi

1992-03-01

227

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

NASA Astrophysics Data System (ADS)

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

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

2012-09-01

228

ECI International Conference on Boiling Heat Transfer Spoleto, 7-12 May 2006  

E-print Network

of the gas-liquid critical point) of the fluid under study, e.g. for water or freon at atmospheric pressure. CHF is then large (of the order of several MW/m2 for water) and the boiling close to it is indeedECI International Conference on Boiling Heat Transfer Spoleto, 7-12 May 2006 IS CHF TRIGGERED

Nikolayev, Vadim S.

229

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 very low to so high that water fails to rewet the surface after bubbles detach. Roughly half

Granick, Steve

230

Nonlinear dynamics of a nuclear-coupled boiling channel with forced flows  

Microsoft Academic Search

The nonlinear dynamics of a nuclear-coupled boiling channel with forced flows was explored on the basis of the Galerkin nodal approximation method for the channel fluid flow and point kinetics for the neutron field dynamics. The marginal stability boundary (MSB) for a Freon boiling channel predicted by the model agreed well with experimental data from previous available literature, thereby verifying

Y. N. Lin; J. D. Lee; Chin Pan

1998-01-01

231

One-point functions in finite volume/temperature: a case study  

NASA Astrophysics Data System (ADS)

We consider finite volume (or equivalently, finite temperature) expectation values of local operators in integrable quantum field theories using a combination of numerical and analytical approaches. It is shown that the truncated conformal space approach, when supplemented with a recently proposed renormalization group, can be sufficiently extended to the low-energy regime that it can be matched with high precision by the low-temperature expansion proposed by Leclair and Mussardo. Besides verifying the consistency of the two descriptions, their combination leads to an evaluation of expectation values which is valid to a very high precision for all volume/temperature scales. As a side result of the investigation, we also discuss some unexpected singularities in the framework recently proposed by Pozsgay and Takcs for the description of matrix elements of local operators in finite volume, and show that while some of these singularities are resolved by the inclusion of the class of exponential finite size corrections known as ?-terms, these latter corrections themselves lead to the appearance of new singularities. We point out that a fully consistent description of finite volume matrix elements is expected to be free of singularities, and therefore a more complete and systematic understanding of exponential finite size corrections is necessary.

Szcsnyi, I. M.; Takcs, G.; Watts, G. M. T.

2013-08-01

232

Simultaneous Contact and Non-contact Measurements of the Melting Temperature of a Ni C Fixed-Point Cell  

NASA Astrophysics Data System (ADS)

A novel fixed-point cell design that allows simultaneous measurements using contact and non-contact thermometers was developed and investigated at PTB to realize the nickel-carbon (Ni C) fixed-point. The melting temperature indicated by the LP3 radiation thermometer amounted to (1328.86 0.52)C ( k = 2). The melting temperature of the Ni C fixed-point cell was also calculated by extrapolating the emf-temperature characteristics of two Pt/Pd thermocouples based on their calibrations at conventional fixed points of the ITS-90. The melting temperature of the Ni C eutectic amounts to (1328.44 0.45)C using thermocouple Pt/Pd 01/04, and to (1328.53 0.46)C using thermocouple Pt/Pd 01/05, with uncertainties for k = 2. The contact and non-contact thermometers agree well within the combined uncertainties.

Edler, F.; Hartmann, J.

2007-12-01

233

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

E-print Network

of the requirements for the degree of MASTER OF SCIENCE December 1991 Major Subject: Meteorology THE BI-VARIATE FREQUENCY DISTRIBUTION OF TWO CONCURRENT CLIMATIC VARIABLES: A STUDY OF TEMPERATURE AND DEW POINT A Thesis by JON WILLIAM ZEITLER Approved... Study of Temperature and Dew Point (December 1991). Jon William Zeitler, B. S. , iowa State University Chair of Advisory Comminee; Prof. John F. Griffiths The bi-variate normal distribution was fitted for the mid-season months of January, April, July...

Zeitler, Jon William

1991-01-01

234

Phase Transitions of the Flux Line Lattice in High-Temperature Superconductors with Weak Columnar and Point Disorder  

Microsoft Academic Search

We study the effects of weak point and columnar disorder on the vortex-lattice phase transitions in high temperature superconductors. The combined effect of thermal fluctuations and of quenched disorder is investigated using a simplified cage model. For point disorder we use the mapping to a directed polymer in a disordered medium in 2+1 dimensions. For columnar disorder the problem is

Yadin Y. Goldschmidt

1997-01-01

235

The supercooling and high temperature stupor points of the adult lesser mealworm Alphitobius diaperinus(Coleoptera: Tenebrionidae)  

Microsoft Academic Search

Potential thermobiological limits in adult lesser mealworms Alphitobius diaperinus were assessed during winter by measuring individual supercooling points (SCP) and thermostupor points (TSP). Two experimental conditions were tested: (i) SCP and TSP measured at 100% r.h.; (ii) SCP with specimens which survive to the TSP at 0% r.h.. The absolute temperature range compatible with life between the two limits SCP

C. Salin; P. Vernon; G. Vannier

1998-01-01

236

Hybrid Interrogation System for Distributed Fiber Strain Sensors and Point Temperature Sensors Based on Pulse Correlation and FBGs  

Microsoft Academic Search

A hybrid interrogation scheme for distributed strain sensors and point temperature sensors is proposed and its feasibility is demonstrated. It exploits the advantages of distributed sensors and point sensors simultaneously. The proposed interrogation scheme uses a wavelength tunable pulse source and wavelength-dependent reflectors for region selective sensing. Experimental results confirm its linear response and a resolution of 0.02% of the

Antonio Bueno; Koji Nonaka; Salvador Sales

2009-01-01

237

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

PubMed

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. PMID:23485271

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

2013-03-01

238

Estimating the Temperatures of Exoplanets 145 Because many exoplanets orbit their  

E-print Network

is frozen (0 C = 273 K) or near its boiling point (100 C or 373 K). Due to orbital conditions, this very 'winter' at aphelion, it is at -62 C which is below the freezing point of water, and similar to the most in elliptical paths, they experience large swings in temperature. Generally, organisms can not survive if water

239

Prediction of the critical heat flux in water subcooled flow boiling using a new mechanistic approach  

Microsoft Academic Search

A thorough examination of the results of existing models based on the liquid sublayer dryout theory suggested the need to postulate a new mechanism to predict the CHF in subcooled water flow boiling. Considering that we have local boiling with bulk subcooled conditions, there will be a distance from the wall at which the fluid temperature is equal to the

G. P. Celata; M. Cumo; Y. Katto; A. Mariani

1999-01-01

240

Flow pattern transition instability during flow boiling in a single microchannel  

Microsoft Academic Search

We studied the unique characteristics of flow boiling in a single microchannel, including the periodic pressure drop, mass flow rate, and temperature fluctuations, in terms of a long time period. Experiments were conducted using a single horizontal microchannel and deionized water to study boiling instabilities at very small mass and heat flow rate conditions. A Polydimethylsiloxane (PDMS) rectangular single microchannel

Cheol Huh; Jeongbae Kim; Moo Hwan Kim

2007-01-01

241

The search for an economic domain of operation when grinding below the film boiling limit  

Microsoft Academic Search

An investigation has been conducted to determine whether an economic domain of shallow-cut grinding exists below the film boiling temperature. It identifies the potential benefits of grinding below film boiling and provides preliminary theoretical evidence based on accepted thermal analyses in grinding and the results of previous research. The evidence shows that an economic domain in shallow-cut grinding could exist.

J. W. Kim; T. D. Howes; H. Gupta

1997-01-01

242

Calibration of copper-constantan thermocouples at low temperatures  

Microsoft Academic Search

1.Since the realization of fixed points is quite simple, the thermocouple calibration procedure with the aid of three fixed points of mercury freezing, dry ice volatilization, and nitrogen boiling can be used in any test laboratory.2.In the 0 to-200C temperature range one can use a simplified method of calibration at two fixed points of dry ice volatilization (or mercury freezing)

A. P. Bondareva

1970-01-01

243

A Fundamental Study of Nucleate Pool Boiling Under Microgravity. Final report  

SciTech Connect

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 = {minus}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, J.S.; Merte, H. Jr.

1996-03-01

244

Experimental studies of MLI systems at very low boundary temperatures  

Microsoft Academic Search

Experimental results for various multilayer insulation (MLI) systems are summarized for two sizes of tank calorimeters. The cold side boundary temperature was normal boiling point (NBP) helium (4.2 K) with hot boundaries between 30 and 130 K. Heat rate data were obtained for double aluminized Mylar (DAM) and double goldizer Mylar (DGM) radiation shields and for a wide variety of

I. E. Spradley; T. C. Nast; D. J. Frank

1990-01-01

245

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

246

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

247

Boiling heat transfer on fins - experimental and numerical procedure  

NASA Astrophysics Data System (ADS)

The paper presents the research methodology, the test facility and the results of investigations into non-isothermal surfaces in water boiling at atmospheric pressure, together with a discussion of errors. The investigations were conducted for two aluminium samples with technically smooth surfaces and thickness of 4 mm and 10 mm, respectively. For the sample of lower thickness, on the basis of the surface temperature distribution measured with an infrared camera, the local heat flux and the heat transfer coefficient were determined and shown in the form of a boiling curve. For the thicker sample, for which 1-D model cannot be used, numerical calculations were conducted. They resulted in obtaining the values of the local heat flux on the surface the invisible to the infrared, camera i.e. on the side on which the boiling of the medium proceeds.

Orzechowski, T.; Tyburczyk, A.

2014-03-01

248

Phase transitions of the flux-line lattice in high-temperature superconductors with weak columnar and point disorder  

NASA Astrophysics Data System (ADS)

We study the effects of weak point and columnar disorder on the vortex-lattice phase transitions in high-temperature superconductors. The combined effect of thermal fluctuations and of quenched disorder is investigated using a simplified cage model. For point disorder we use the mapping to a directed polymer in a disordered medium in 2+1 dimensions. For columnar disorder the problem is mapped into a quantum particle in a harmonic and a random potential. We use the variational approximation to show that point and columnar disorder have opposite effect on the position of the melting line as is observed experimentally. For point disorder, replica symmetry breaking plays a role at the transition into a vortex glass at low temperatures.

Goldschmidt, Yadin Y.

1997-08-01

249

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

250

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

PubMed

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. PMID:24950371

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

2014-08-01

251

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

252

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

253

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

254

Detection of the end point temperature of thermal denatured protein in fish and chicken meat through SDS-PAGE electrophoresis  

NASA Astrophysics Data System (ADS)

Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) was applied in the detection of the end point temperature (EPT) of thermal denatured protein in fish and meat in this study. It was also used in studying the thermal denatured temperature range of proteins in salmon and chicken meat. The results show that the temperature ranges of denatured proteins were from 65C to 75C, and these temperature ranges were influenced by the processing methods. Through SDS-PAGE, the features of repeated heating thermal denatured proteins under the same temperature and processing time were studied. The electrophoresis patterns of thermal denatured proteins determined through repeated heating at the same temperature did not exhibit any change. For the detection of cooked fish and meat samples, they were subjected to applying the SDS-PAGE method, which revealed an EPT ranging from 60C to 80C.

Gao, Hongwei; Mao, Mao; Liang, Chengzhu; Lin, Chao; Xiang, Jianhai

2009-03-01

255

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

Microsoft Academic Search

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

Lloyd Hunter

1942-01-01

256

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

...STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Cargo Pressure and Temperature Control 154.707 Cargo boil-off as fuel: Ventilation. (a) A ventilation hood or casing must be...

2014-10-01

257

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

...STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Cargo Pressure and Temperature Control 154.706 Cargo boil-off as fuel: Fuel lines. (a) Gas fuel lines must not pass through...

2014-10-01

258

46 CFR 154.708 - Cargo boil-off as fuel: Valves.  

...STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Cargo Pressure and Temperature Control 154.708 Cargo boil-off as fuel: Valves. (a) Gas fuel lines to the gas consuming equipment...

2014-10-01

259

Experimental and Analytical Study of Lead-Bismuth-Water Direct Contact Boiling Two-Phase Flow  

Microsoft Academic Search

The characteristics of lead-bismuth(Pb-Bi)-water boiling two-phase flow were investigated experimentally and analytically using a Pb-Bi-water direct contact boiling two-phase flow loop. Pb-Bi flow rates and void fraction were measured in a vertical circular tube at conditions of system pressure 7MPa, liquid metal temperature 460C and injected water temperature 220C. The drift-flux model with the assumption that bubble sizes were dependent

Novitrian; Vaclav Dostal; Minoru Takahashi

2007-01-01

260

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

261

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, Connecticut Global Fuel Cell Center Department of Electrical & Computer Engineering, 44 Weaver Road, Unit 5233

Boyer, Edmond

262

A molecular dynamics simulation of the melting points and glass transition temperatures of myo-and neo-inositol  

E-print Network

A molecular dynamics simulation of the melting points and glass transition temperatures of myo simulations and that molecular dynamics techniques, combined with this force field, can be used to simulate have attempted to simulate, usu- ally by molecular dynamics techniques, the glass transition

de Gispert, Adrià

263

An optical fibre system design enabling simultaneous point measurement of magnetic field strength and temperature using low-birefringence FBGs  

Microsoft Academic Search

Fibre measurement of key parameters in nuclear fusion reactor environments, such as the magnetic field strength and temperature, is highly desirable due to the convenience and robustness of optical fibre sensors when compared with conventional electrical sensors. Presently, fibre point sensors for magnetic field are based predominantly on magnetostriction which limits their applicability to this environment. We present an optical

P. Orr; P. Niewczas

2010-01-01

264

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

E-print Network

neutron absorption and activation, high boiling point and poor interaction with water and air, etc point and poor interaction with water and air, etc.). Analysis of hypothetical accidents is of relevance; boiling point = 2022 K) and Pb (melting point = 600 K; boiling point = 1837 K) as well as the Pb

Azad, Abdul-Majeed

265

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

266

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

SciTech Connect

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

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

2004-06-23

267

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

PubMed

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

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

2013-05-01

268

Trend analysis and change point detection of annual and seasonal precipitation and temperature series over southwest Iran  

NASA Astrophysics Data System (ADS)

This paper presents results of trend analysis and change point detection of annual and seasonal precipitation, and mean temperature (TM), maximum temperature (TMAX) and minimum temperature (TMIN) time series of the period 1950-2007. Investigations were carried out for 50 precipitation stations and 39 temperature stations located in southwest Iran. Three statistical tests including Pettitt's test, Sequential Mann-Kendall test (SQ-MK test) and Mann-Kendall rank test (MK-test) were used for the analysis. The results obtained for precipitation series indicated that most stations showed insignificant trends in annual and seasonal series. Out of the stations which showed significant trends, highest numbers were observed during winter season while no significant trends were detected in summer precipitation. Moreover, no decreasing significant trends were detected by statistical tests in annual and seasonal precipitation series. The analysis of temperature trends revealed a significant increase during summer and spring seasons. TMAX was more stable than TMIN and TM, and winter was stable compared to summer, spring and autumn seasons. The results of change point detection indicated that most of the positive significant mutation points in TM, TMAX and TMIN began in the 1990s.

Zarenistanak, Mohammad; Dhorde, Amit G.; Kripalani, R. H.

2014-03-01

269

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

270

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

NASA Astrophysics Data System (ADS)

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

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

2013-07-01

271

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

272

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

273

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

274

Evaluation of methods for characterizing the melting curves of a high temperature cobalt-carbon fixed point to define and determine its melting temperature  

NASA Astrophysics Data System (ADS)

The future mise en pratique for the realization of the kelvin will be founded on the melting temperatures of particular metal-carbon eutectic alloys as thermodynamic temperature references. However, at the moment there is no consensus on what should be taken as the melting temperature. An ideal melting or freezing curve should be a completely flat plateau at a specific temperature. Any departure from the ideal is due to shortcomings in the realization and should be accommodated within the uncertainty budget. However, for the proposed alloy-based fixed points, melting takes place over typically some hundreds of millikelvins. Including the entire melting range within the uncertainties would lead to an unnecessarily pessimistic view of the utility of these as reference standards. Therefore, detailed analysis of the shape of the melting curve is needed to give a value associated with some identifiable aspect of the phase transition. A range of approaches are or could be used; some purely practical, determining the point of inflection (POI) of the melting curve, some attempting to extrapolate to the liquidus temperature just at the end of melting, and a method that claims to give the liquidus temperature and an impurity correction based on the analytical Scheil model of solidification that has not previously been applied to eutectic melting. The different methods have been applied to cobalt-carbon melting curves that were obtained under conditions for which the Scheil model might be valid. In the light of the findings of this study it is recommended that the POI continue to be used as a pragmatic measure of temperature but where required a specified limits approach should be used to define and determine the melting temperature.

Lowe, David; Machin, Graham

2012-06-01

275

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

276

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...

277

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

NASA Astrophysics Data System (ADS)

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

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

2010-06-01

278

Nucleate pool boiling in the long duration low gravity environment of the Space Shuttle  

NASA Technical Reports Server (NTRS)

The results are presented of an experimental study of nucleate pool boiling performed in the low gravity environment of the space shuttle. Photographic observations of pool boiling in Freon 113 were obtained during the 'Tank Pressure Control Experiment,' flown on the Space Transportation System, STS-43 in August 1991. Nucleate boiling data from large (relative to bubble size) flat heating surfaces (0.1046 by 0.0742 m) was obtained at very low heat fluxes (0.22 to 1.19 kW/sq m). The system pressure and the bulk liquid subcooling varied in the range of 40 to 60 kPa and 3 to 5 C respectively. Thirty-eight boiling tests, each of 10-min duration for a given heat flux, were conducted. Measurements included the heater power, heater surface temperature, the liquid temperature and the system pressure as functions of heating time. Video data of the first 2 min of heating was recorded for each test. In some tests the video clearly shows the inception of boiling and the growth and departure of bubbles from the surface during the first 2 min of heating. In the absence of video data, the heater temperature variation during heating shows the inception of boiling and stable nucleate boiling. During the stable nucleate boiling, the wall superheat varied between 2.8 to 3.8 C for heat fluxes in the range of 0.95 to 1.19 kW/sq m. The wall superheat at the inception of boiling varied between 2 to 13 C.

Hasan, M. M.; Lin, C. S.; Knoll, R. H.; Bentz, M. D.; Meserole, J. S.

1993-01-01

279

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

280

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

281

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

282

Experimental demonstration of contaminant removal from fractured rock by boiling.  

PubMed

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

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

2010-08-15

283

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

284

Performance of the NO{sub x} emissions advisor and advanced steam temperature control at Possum Point Station  

SciTech Connect

Virginia Power installed Stone and Webster`s NO{sub x} Emissions Advisor and Advanced Steam Temperature Control Systems on Possum Point Units 3 and 4 during the Spring of 1995 to achieve near-term NO{sub x} compliance objectives and improve thermal performance. The installation of the advanced control and automation systems was integrated into the existing control system using standard hardware and software. The advanced control systems operate under Windows-NT on a Pentium personal computer (PC) in a multi-process environment, exchanging data with the distributed control system (DCS) through a dedicated serial link. Testing has demonstrated NO, reductions of greater than 20 percent through the application of the NO{sub x} Emissions Advisor on these units, while maintaining steam temperatures and unit efficiency. Possum Point Power Station Units 3 and 4 are pulverized coal, tangentially fired boilers, producing 107 and 232 MW, respectively.

Leigh, M. [Virginia Power Co., Glen Allen, VA (United States); Labbe, D. [Stone and Webster Engineering Corp., Boston, MA (United States)

1995-10-01

285

Effects of temperature generated from the Holmium: YAG laser on human osteoblasts in monolayer tissue culture.  

PubMed

With the use of lasers for ablation purposes in spinal surgery, the tissue temperature increases above the boiling point of water, leading to tissue ablation by vaporisation. Due to the thermal environment engendered by the use of lasers, there is concern about the safety of the surrounding important structures, such as dura mater, dorsal root ganglia, and nerve roots. PMID:22057464

Hafez, Moustafa I; Sandison, Anne; Coombs, Richard R H; McCarthy, Ian D; Hafez, Al-Shymaa M

2012-01-01

286

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

287

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

288

Numerical analysis of contaminant removal from fractured rock during boiling  

NASA Astrophysics Data System (ADS)

A multiphase heat transfer numerical model is used to simulate a laboratory experiment of contaminant removal at boiling temperatures from a rock core representing the matrix adjacent to a fracture. The simulated temperature, condensate production, contaminant and bromide concentrations are similar to experimental data. A key observation from the experiment and simulation is that boiling out approximately 1/2 pore volume (50 mL) of water results in the removal of essentially 100% of the dissolved volatile contaminant (1,2-DCA). A field-scale simulation using the multiple interacting continua (MINC) discretization approach is conducted to illustrate possible applications of thermal remediation of fractured geologic media, assuming uniform heating. The results show that after 28% of the pore water (including both steam vapor and liquid water) was extracted, and essentially all the 1,2-DCA mass (more than 99%) was removed.

Chen, Fei; Falta, Ronald W.; Murdoch, Lawrence C.

2012-06-01

289

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

290

Numerical analysis of contaminant removal from fractured rock during boiling.  

PubMed

A multiphase heat transfer numerical model is used to simulate a laboratory experiment of contaminant removal at boiling temperatures from a rock core representing the matrix adjacent to a fracture. The simulated temperature, condensate production, contaminant and bromide concentrations are similar to experimental data. A key observation from the experiment and simulation is that boiling out approximately 1/2 pore volume (50 mL) of water results in the removal of essentially 100% of the dissolved volatile contaminant (1,2-DCA). A field-scale simulation using the multiple interacting continua (MINC) discretization approach is conducted to illustrate possible applications of thermal remediation of fractured geologic media, assuming uniform heating. The results show that after 28% of the pore water (including both steam vapor and liquid water) was extracted, and essentially all the 1,2-DCA mass (more than 99%) was removed. PMID:22579665

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

2012-06-01

291

Investigations of Mechanisms Associated with Nucleate Boiling Under Microgravity Conditions  

NASA Astrophysics Data System (ADS)

In this work a building block type of approach is used so that a basic understanding of the processes that contribute to nucleate boiling heat fluxes under microgravity conditions can be developed. This understanding will lead to development of a mechanistic model for nucleate boiling heat transfer which could eventually be used as a design tool in space applications. Task Description Task 1: Fabrication of the Experimental Setup. Under this task, the test section and liquid holding and viewing chambers will be fabricated. Artificial cylinder cavities will be formed on silicon wafers. A single cavity and two or four cavities, with a prescribed spacing and size, will be formed. The desired nucleation wall superheat will be used to determine the size of the mouth of the cavities. Task 2: Experiments. The basic experiments for flow and temperature field around single and multiple (2 or 4 separated or merged bubbles growing on downward facing or inclined surfaces) will be carried out under normal gravity conditions. The experiments will be conducted at one atmosphere pressure, but liquid subcooling will be varied from 0 to 30C. Water and PF-5050 will be used as test liquids. Task 3: Analytical/Numerical Models. In this task, transient temperature and flow field in vapor and liquid will be determined during growth of a single bubble. Analysis will include the evolution of the vapor-liquid interface and development of microlayer underneath the bubbles. For merged bubbles, detailed calculations of flow and temperature field will be carried out for transient shapes of vapor stems supporting a large bubble and the corresponding evaporation rate. Flow and temperature field for a bubble sliding along a heated wall will also be determined. Microgravity conditions will be simulated and a framework of a numerical tool for prediction of nucleate boiling heat fluxes under microgravity conditions will be developed. Task 4: Experiments in a KC-135. To understand bubble growth and detachment behavior of single or large merged bubbles, boiling experiments will be conducted under low gravity (10-2 g) conditions of the aircraft. In these experiments, 'designed' surfaces will be used. Visual observations and heat transfer data will be taken, but holography will not be used. The apparatus used for laboratory experiments will also be employed for experiments in the aircraft. Task 5: Experiments in the Space Shuttle. Effort will be devoted for defining a boiling experiment to be conducted on a 'designed' surface. The experiment will provide microgravity data on bubble growth and departure. These data are needed for development of a credible model for nucleate boiling heat fluxes under microgravity conditions. The heat transfer data will also be obtained and will be used to validate the models.

Dhir, Vijay K.; Hasan, M.

2003-01-01

292

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

293

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

294

Flow boiling in constructal tree-shaped minichannel network  

Microsoft Academic Search

Flow boiling in constructal tree-shaped minichannel network with an inlet diameter of 4mm is numerically investigated using a one-dimensional model, taking into consideration the minor losses at junctions. The pumping power requirement, pressure drop, temperature uniformity and coefficient of performance of the constructal tree-shaped minichannel network are all evaluated and compared with those of the corresponding traditional serpentine channel, and

Chengbin Zhang; Yongping Chen; Rui Wu; Mingheng Shi

2011-01-01

295

Experimental study of water droplet boiling on hot, non-porous surfaces  

Microsoft Academic Search

In this paper, the results of a series of experimental tests on single- and multi-droplet boiling systems are presented and\\u000a discussed. The main objectives of the present study are: a) to investigate experimentally the effect of the boiling onset\\u000a on the evaporation rate of water droplets; b) to measure the evolution of the solid surface temperature during evaporation;\\u000a c) to

P. Tartarini; G. Lorenzini; M. R. Randi

1999-01-01

296

Prediction and measurement of incipient boiling heat flux in micro-channel heat sinks  

Microsoft Academic Search

Experiments were performed to measure the incipient boiling heat flux in a heat sink containing 21 rectangular (231 ?m wide and 713 ?m deep) micro-channels. Tests were performed using deionized water with inlet liquid velocities of 0.131.44 m\\/s, inlet temperatures of 30, 60 and 90 C, and an outlet pressure of 1.2 bar. Using a microscope, boiling incipience was identified

Weilin Qu; Issam Mudawar

2002-01-01

297

[Cavitation and boiling of bubbles at the focal region during high intensity focused ultrasound exposure].  

PubMed

High intensity focused ultrasound (HIFU) is a very complex transient process and can cause tissue coagulation necrosis. The cavitation and boiling behaviour of bubbles in the focal region play very important roles throughout an injury process. This paper reviews the research done by domestic and foreign scholars on behaviours of bubbles in HIFU irradiation process and summarizes in the focal region bubble cavitation and boiling generation, related detective means and relationships with hyperecho, temperature rise of the focus and injury shape. PMID:23198445

Zhong, Mingsong; Ai, Huijian; Li, Faqi

2012-10-01

298

Boils  

MedlinePLUS

... 2/2017 2017 AOCD Spring Current Concepts in Dermatology Meeting more Latest News 6/9/2014 Medicare Complaint Form 4/3/2014 The Burning Truth 12/19/2013 Osteopathic Training Statement 7/2/2013 The Truth About Tanning 4/24/2013 Sun Safety IQ Online Surveys About AOCD The AOCD was recognized in ...

299

Effect of dry hydrocarbons and critical point temperature on the efficiencies of organic Rankine cycle  

Microsoft Academic Search

Higher efficiencies and optimal utilization of geothermal energy require a careful selection of the working fluid in organic Rankine cycles (ORC). The objectives of this study are to analyze and explain the effect of using alternative dry fluids on the efficiencies of the ORC and compare them with other refrigerants. In addition, the effect of the critical temperature on the

Isam H. Aljundi

2011-01-01

300

Temperature Temperature is the physical property of a  

E-print Network

interval between melting ice and boiling water under 1 atm pressure shall be 100. @ melting ice temperature temperature scale; boiling water to 373.15 degrees. The scale is named after Lord Kelvine, 1 degree Kelvine 1 atm presure @ saturated water vapor temp, 1 atm pressure p0 V0=RT 0 p1V 1=RT1= RT0100 #12;AbsoluteTemperature

Alexeenko, Alina

301

Synthesis and physical properties of novel perfluorinated methylene oxide oligomers. The ultimate low temperature fluids  

SciTech Connect

Perfluorinated polyethers are a class of substances which are extremely inert and have both extraordinary high temperature stability and low temperature properties. The synthesis of perfluorinated polyformaldehydes with the highest oxygen content was designed to give the maximum liquid range and low temperature properties. Novel low molecular weight perfluorinated polyformaldehydes with stable and unreactive perfluoro-n-butyl end groups were prepared by liquid-phase direct fluorination. The boiling point of these compounds increases by approximately 20{degree}C with the addition of each difluoromethylene oxide unit. This trend does not continue for longer chain lengths (n > 4) where the increase in boiling point per CF{sub 2}O unit diminishes. The average increase of melting temperature is approximately 1-2{degree}C as the perfluorinated polyformaldehyde chain increases one difluoromethylene oxide unit. The new perfluoropolyether fluids produced have melting points ranging from -145 to -152{degree}C. 33 refs., 3 tabs.

Sung, K.; Lagow, R.J. [Univ. of Texas, Austin, TX (United States)

1995-04-19

302

Enhancement of Pool Boiling Heat Transfer in Confined Space  

E-print Network

Pool boiling is an effective method used in many technical applications for a long time. Its highly efficient heat transfer performance results from not only the convection effect but also the phase change process in pool boiling. Pool boiling...

Hsu, Chia-Hsiang

2014-05-05

303

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

Microsoft Academic Search

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

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

2004-01-01

304

Temperature dependent droplet impact dynamics on flat and textured surfaces  

NASA Astrophysics Data System (ADS)

Droplet impact dynamics determines the performance of surfaces used in many applications such as anti-icing, condensation, boiling, and heat transfer. We study impact dynamics of water droplets on surfaces with chemistry/texture ranging from hydrophilic to superhydrophobic and across a temperature range spanning below freezing to near boiling conditions. Droplet retraction shows very strong temperature dependence especially on hydrophilic surfaces; it is seen that lower substrate temperatures lead to lesser retraction. Physics-based analyses show that the increased viscosity associated with lower temperatures combined with an increased work of adhesion can explain the decreased retraction. The present findings serve as a starting point to guide further studies of dynamic fluid-surface interaction at various temperatures.

Alizadeh, Azar; Bahadur, Vaibhav; Zhong, Sheng; Shang, Wen; Li, Ri; Ruud, James; Yamada, Masako; Ge, Liehui; Dhinojwala, Ali; Sohal, Manohar

2012-03-01

305

Nanosecond responses of proteins to ultra-high temperature pulses.  

PubMed

Observations of fast unfolding events in proteins are typically restricted to <100 degrees C. We use a novel apparatus to heat and cool enzymes within tens of nanoseconds to temperatures well in excess of the boiling point. The nanosecond temperature spikes are too fast to allow water to boil but can affect protein function. Spikes of 174 degrees C for catalase and approximately 290 degrees C for horseradish peroxidase are required to produce irreversible loss of enzyme activity. Similar temperature spikes have no effect when restricted to 100 degrees C or below. These results indicate that the "speed limit" for the thermal unfolding of large proteins is shorter than 10(-8) s. The unfolding rate at high temperature is consistent with extrapolation of low temperature rates over 12 orders of magnitude using the Arrhenius relation. PMID:16844754

Steel, Bradley C; McKenzie, David R; Bilek, Marcela M M; Nosworthy, Neil J; dos Remedios, Cristobal G

2006-09-15

306

Calculation of pitch point in the counter flow heat exchanger used in low-temperature waste heat powered Organic Rankine cycle  

Microsoft Academic Search

The calculation of pitch point in the counter flow heat exchanger used in low-temperature waste heat powered Organic Rankine cycle is investigated. Detailed calculations of a HRSG with binary mixture fluids of different composition have been done on the base of pinch point analysis. The influence of binary mixture composition on the temperature distribution in the counter flow heat recovery

Wang Hui-tao; Wang Hua

2010-01-01

307

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

308

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

309

AN ATOMIZATION MODEL FOR FLASH BOILING SPRAYS  

Microsoft Academic Search

This paper presents an atomization model for sprays under flash boiling conditions. The automization is represented by the secondary breakup of a bubble\\/droplet system, and the breakup is considered as the result of two competing mechanisms: aerodynamic force and bubble growth. The model was applied to predict the atomization of a hollow-cone spray from a pintle injector under flash boiling

YANGBING ZENG; CHIA-FON F. LEE

2001-01-01

310

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

311

Microgravity Heat Transfer in Flow Boiling  

Microsoft Academic Search

To investigate flow boiling in microgravity, test sections of transparent heated tube and transparent heating surface were developed, and heat transfer characteristics were directly related to the liquidvapor behaviors observed. The experiments were performed on board aircraft where the boiling system was exposed in series to normal, hyper and reduced gravity fields along a parabolic trajectory. In the experiments using

Haruhiko Ohta

2003-01-01

312

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

313

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

314

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

315

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

316

Challenging the distributed temperature sensing technique for estimating groundwater discharge to streams through controlled artificial point source experiment  

NASA Astrophysics Data System (ADS)

Spatially confined groundwater discharge can contribute significantly to stream discharge. Distributed fibre optic temperature sensing (DTS) of stream water has been successfully used to localize- and quantify groundwater discharge from this type "point sources" (PS) in small first-order streams. During periods when stream and groundwater temperatures differ PS appear as abrupt step in longitudinal stream water temperature distribution. Based on stream temperature observation up- and downstream of a point source and estimated or measured groundwater temperature the proportion of groundwater inflow to stream discharge can be quantified using simple mixing models. However so far this method has not been quantitatively verified, nor has a detailed uncertainty analysis of the method been conducted. The relative accuracy of this method is expected to decrease nonlinear with decreasing proportions of lateral inflow. Furthermore it depends on the temperature differences (?T) between groundwater and surface water and on the accuracy of temperature measurement itself. The latter could be affected by different sources of errors. For example it has been shown that a direct impact of solar radiation on fibre optic cables can lead to errors in temperature measurements in small streams due to low water depth. Considerable uncertainty might also be related to the determination of groundwater temperature through direct measurements or derived from the DTS signal. In order to directly validate the method and asses it's uncertainty we performed a set of artificial point source experiments with controlled lateral inflow rates to a natural stream. The experiments were carried out at the Vollnkirchener Bach, a small head water stream in Hessen, Germany in November and December 2011 during a low flow period. A DTS system was installed along a 1.2 km sub reach of the stream. Stream discharge was measured using a gauging flume installed directly upstream of the artificial PS. Lateral inflow was simulated using a pumping system connected to a 2 m3 water tank. Pumping rates were controlled using a magnetic inductive flowmeter and kept constant for a time period of 30 minutes to 1.5 hours depending on the simulated inflow rate. Different temperatures of lateral inflow were adjusted by heating the water in the tank (for summer experiments a cooling by ice cubes could be realized). With this setup, different proportions of lateral inflow to stream flow ranging from 2 to 20%, could be simulated for different ?T's (2-7 C) between stream- and inflowing water. Results indicate that the estimation of groundwater discharge through DTS is working properly, but that the method is very sensitive to the determination of the PS groundwater temperature. The span of adjusted ?T and inflow rates of the artificial system are currently used to perform a thorough uncertainty analysis of the DTS method and to derive thresholds for detection limits.

Lauer, F.; Frede, H.-G.; Breuer, L.

2012-04-01

317

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 90C 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

318

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

NASA Technical Reports Server (NTRS)

The temperature-plant pigment-optical structure of a mesoscale anticyclonic eddy consistently found in shipboard surveys and satellite-sensed data several hundred kilometers southwest of Point Conception, CA, is described on three different time scales (100-day mesoscale, annual, and several-year). The satellite coastal zone color scanner (CZCS) ocean color imagery detected the near-surface chlorophyll structure of the eddy, but in situ optical and plant pigment data suggest that such imagery does not provide a good estimate of the integrated chlorophyll field of the eddy. The temperature and plant pigment boundaries of the eddy, as determined from two-dimensional gradients of advanced very high resolution radiometer (AVHRR) and CZCS imagery, do not coincide spatially. This and in situ temperature, plant pigment, and optical structure provide additional evidence that some eddy systems in the California Current are not isolated vortex systems but rather continuously entrain waters of nonlocal origin laterally into their upper layers. Within the California Current a ratio of AVHRR/CZCS data is useful for separating inshore from oceanic water masses and following their surface entrainment by offshore vortices. The historical 28-year California Cooperative Oceanic Fisheries Investigations data for the Point Conception region of the California Current and remotely sensed data over this region show that the Point Conception eddy is a recurrent feature in the offshore California Current. Moreover, the available data provide evidence that a large number of warm-core mesoscale eddies occur simultaneously in a transition zone between coastal and oceanic regimes, that these features recur at preferred locations within the transition zone, and that this family of eddies should impose a significant offshore boundary condition on the flow of the California Current.

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

1986-01-01

319

Considerations in predicting burnout of cylinders in flow boiling  

SciTech Connect

Previous investigations of the critical heat flux in flow boiling have resulted in widely different hydrodynamic mechanisms for the occurrence of burnout. Results of the present study indicate that existing models are not completely realistic representations of the process. The present study sorts out the influences of the far-wake bubble breakoff and vapor sheet characteristics, gravity, surface wettability, and heater surface temperature distribution on the peak heat flux in flow boiling on cylindrical heaters. The results indicate that burnout is dictated by near-surface effects. The controlling factor appears to be the vapor escape pattern close to the heater surface. It is also shown that a deficiency of liquid at the downstream end of the heater surface is not the cause of burnout.

Sadasivan, P.; Lienhard, J.H. (Univ. of Houston, TX (United States))

1992-02-01

320

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

321

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

PubMed Central

Extensive environment-dependent rearrangement of the helix-turn-helix DNA recognition region and adjacent l-tryptophan binding pocket is reported in the crystal structure of dimeric E. coli trp aporepressor with point mutation Leu75Phe. In one of two subunits, the eight residues immediately C-terminal to the mutation are shifted forward in helical register by three positions, and the five following residues form an extrahelical loop accommodating the register shift. In contrast, the second subunit has wildtype-like conformation, as do both subunits in an isomorphous wildtype control structure. Treated together as an ensemble pair, the distorted and wildtype-like conformations of the mutant apoprotein agree more fully than either conformation alone with previously reported NOE measurements, and account more completely for its diverse biochemical and biophysical properties. The register-shifted segment Ile79-Ala80-Thr81-Ile82-Thr83 is helical in both conformations despite low helical propensity, suggesting an important structural role for the steric constraints imposed by ?-branched residues in helical conformation. PMID:22057811

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

2012-01-01

322

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

323

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

324

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

325

Zero Boil Off Cryogen Storage for Future Launchers  

NASA Technical Reports Server (NTRS)

Zero boil off (ZBO) cryogen storage using both cryocoolers and passive insulation technologies will enable long-term exploration missions by allowing designers to optimize tankage without the need for excess cryogen storage to account for boil off. Studies of ZBO (zero boil off) have been on-going in the USA for several years. More recently, a review of the needs of advanced space propulsion took place in Europe. This showed the interest of the European community in cryogenic propulsion for planetary missions as well as the use of liquid hydrogen for large power electric propulsion (manned Mars missions). Although natural boiling could be acceptable for single leg missions, passive insulation techniques yield roughly a I% per month cryogen loss and this would not be cost effective for robotic planetary missions involving storage times greater than one year. To make economic sense, long-term exploration missions require lower tank capacity and longer storage times. Recent advances in cryocooler technology, resulting in vast improvements in both cooler efficiency and reliability, make ZBO is a clear choice for planetary exploration missions. Other, more near term applications of ZBO include boil-off reduction or elimination applied to first and upper stages of future earth-to-orbit (ETO) launchers. This would extend launch windows and reduce infrastructure costs. Successors to vehicles like Ariane 5 could greatly benefit by implementing ZBO. Zero Boil Off will only be successful in ETO launcher applications if it makes economic sense to implement. The energy cost is only a fraction of the total cost of buying liquid cryogen, the rest being transportation and other overhead. Because of this, higher boiling point cryogens will benefit more from on-board liquefaction, thus reducing the infrastructure costs. Since hydrogen requires a liquefier with at least a 17% efficiency just to break even from a cost standpoint, one approach for implementing ZBO in upper stages would be to actively cool the shield in the hydrogen tank to reduce the parasitic losses. This would allow the use of less expensive, presently available coolers (80 K vs. 20 K) and potentially simplify the system by requiring only a single compressor on the pad amd a single disconnect line. The compressor could be a hefty commercial unit, with only the cold head requiring expensive flight development and qualification. While this is actually a reduced boil off configuration rather than a zero-boil off case, if the cryogen loss could be cut significantly, the increase in hold time and reduced need for draining and refilling the propellant tanks could meet the vehicle operations needs in the majority of instances.Bearing in mind the potential benefits of ZBO, NASA AMES and SNECMA Moteurs decided to exchange their technical views on the subject. This paper will present a preliminary analysis for a multi-mission module using a fairly low thrust cryogenic engine and ZBO during cruise. Initial mass is 5.5. tons (in ETO). The cryogenic engine will be used near each periapsis in order to minimize the AV requirement. The payload obtained by this propulsion system is compared to a classical storable bipropellant propulsion system for several cases (e. g. Mars lander, Jupiter orbiter, Saturn orbiter). For the Jupiter and Saturn cases, the power source could be an RTG or a large parabolic mirror illuminating a solar panel. It is shown -that - due to its much larger specific impulse - the cryogenic ZBO solution provides much higher payloads, especially for exploration missions involving landing on planets, asteroids, comets, or other celestial bodies.

Valentian, D.; Plachta, D.; Kittel, P.; Hastings, L. J.; Salerno, Louis J.; Arnold, James O. (Technical Monitor)

2001-01-01

326

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

327

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

328

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

329

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

330

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

331

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.

332

Experiments on microgravity boiling heat transfer by using transparent heaters  

Microsoft Academic Search

To clarify the relation between the liquidvapor behavior and the heat transfer characteristics in the boiling phenomena, the structures of transparent heaters were developed for both flow boiling and pool boiling experiments and were applied to the microgravity environment realized by the parabolic flight of aircraft. In the flow boiling experiment, a transparent heated tube makes the heating, the observation

H Ohta

1997-01-01

333

Boiling and condensing pumped loop microgravity experiment  

SciTech Connect

Aircraft testing of a boiling and condensing (two-phase) pumped loop system was conducted to investigate transient induced by low gravity (Keplerian) maneuvers. The experiment, unchanged, will repeat a selected aircraft test sequence during its flight aboard a suborbital rocket. Such a test of a two-phase system has never been done. A comparison of aircraft and rocket data, particularly equilibrium conditions, may validate aircraft testing of similar systems: Aircraft testing has been completed and preliminary results indicate that local transients induced by Keplerian maneuvers do not generate sizeable or lasting feedback. System feedback, expected to damp exponentially with loop transit time, {theta}{sub loop} (20 s{lt}{theta}{sub loop}{lt}30 s) is negligible compared to local temperature transients having shorter equilibrium times, {theta}{sub local} (5{lt}{theta}{sub local}{lt}10 s). Since {theta}{sub local} is typically 2 to 5 times shorter than the duration of low gravity, {ital t}{sub 0{minus}{ital g}} (20 s{lt}t{sub 0{minus}{ital g}}{lt}25 s), equilibrium conditions are approximated. Transients following a transition from normal to low gravity resulted from destratification of hot and cold fluid, loss of the liquid convection component in laminar flows, and a reduction in condensing heat transfer.

Standley, V.H.; Fairchild, J.F. (Weapons Laboratory, Technology Assessment Directorate, Space Nuclear Power Branch, Kirtland AFB, New Mexico (USA))

1991-01-10

334

Terminology Poikilotherms body temperature = ambient  

E-print Network

to boiling ­ 584 cal (2443 J) to transfer 1 g of water to vapor at room temperature ­ 418 J (100 cal) to heat, or evaporation of water · Conductance ­ high to low, bodies in contact ­ Heat flow is dependent upon temperature 1 g of water from freezing to boiling · Various avenues for evaporation in animals, but they all

Jodice, Patrick

335

Description of boiling project burnout detector  

E-print Network

Introduction: In order to effectively utilize the high heat flux available through the mechanism of nucleate boiling in forced convection heat transfer, it is of primary importance that the maximum flux or "burnout" ...

Raymond, M. W.

1957-01-01

336

Void volumes in subcooled boiling systems  

E-print Network

Introduction: Knowledge of the pressure drop in a channel and the resulting flow redistribution is essential in predicting the performance of a nuclear reactor. The pressure drop in a channel which is experiencing boiling ...

Griffith, P.

1958-01-01

337

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

338

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

339

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

340

Fluids and parameters optimization for a novel cogeneration system driven by low-temperature geothermal sources  

Microsoft Academic Search

A novel cogeneration system was proposed and techno-economically investigated, consisting of a low-temperature geothermally-powered organic Rankine cycle (ORC) subsystem, an intermediate heat exchanger subsystem and a heat pump subsystem. The main purpose is to identify suitable working fluids (among 27 fluids with boiling point temperature ranging from ?47.69 to 47.59C) and optimized cycle parameters for the ORC-based power generation subsystem.

T. Guo; H. X. Wang; S. J. Zhang

2011-01-01

341

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

342

Effects of Temperature and pH on Reduction of Bacteria in a Point-of-Use Drinking Water Treatment Product for Emergency Relief  

PubMed Central

The effects of temperature and pH on the water treatment performance of a point-of-use (POU) coagulant/disinfectant product were evaluated. Cold temperatures (?5C) reduced the bactericidal efficiency of the product with regard to Escherichia coli and total coliform log10 reductions. PMID:23335762

Marois-Fiset, Jean-Thomas; Carabin, Anne; Lavoie, Audrey

2013-01-01

343

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

344

A two-dimensional model for boiling in an active particle bed: BOIL  

Microsoft Academic Search

In order to model two-dimensional boiling in an active particle bed, a two dimensional, steady state, isothermal model was assembled, starting from the mass, momentum, and energy conservation laws. The momentum balance includes capillary and gravity effects and two phase flow pressure losses. This physical description is translated into a mathematical model and implemented as a numerical code, BOIL, using

P. H. Theunissen; J. M. Buchlin

1984-01-01

345

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

346

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

347

High dryout quality film boiling and steam cooling heat transfer data from a rod bundle  

Microsoft Academic Search

A series of eight steady-state rod bundle tests has been performed in the Thermal Hydraulic Test Facility to gather data in both the low flow film boiling region and high flow steam cooling region. This test series includes experiments both with and without liquid entrainment above the dryout point. Bundle fluid conditions were calculated using steady-state energy and mass conservation

G. L. Yoder; T. M. Anklam; D. G. Morris; C. B. Mullins

1983-01-01

348

Heat and mass transfer in porous media phase separation at temperatures below the lambda-point of He-4  

NASA Technical Reports Server (NTRS)

Newtonian fluid motion, coupled to heat transfer via latent heat of phase transition, is well known from numerous studies of condensation and boiling. Considerably less knowledge is available for vapor-liquid phase separation in the absence of gravity effect on the transport phenomena. The present studies are focused on heat and mass transfer associated with vapor-liquid phase separation required for long-term storage of the cryogen liquid He II in space vessels. Though space conditions are the dominant mode of interest in advanced equipment, e.g. IR telescopes, the systems may be operated in principle during terrestrial conditions. The latter are considered in the present work. It emphasizes the linear regime including an extrapolation based on variable thermophysical properties. Data taken with a phase separation approach show departures from the linear regime prediction. They agree with a transport equation proposed for the nonlinear, turbulent regime.

Yuan, S. W. K.; Frederking, T. H. K.

1986-01-01

349

Assessing the microbiological performance and potential cost of boiling drinking water in urban Zambia.  

PubMed

Boiling is the most common method of disinfecting water in the home and the benchmark against which other point-of-use water treatment is measured. In a six-week study in peri-urban Zambia, we assessed the microbiological effectiveness and potential cost of boiling among 49 households without a water connection who reported "always" or "almost always" boiling their water before drinking it. Source and household drinking water samples were compared weekly for thermotolerant coliforms (TTC), an indicator of fecal contamination. Demographics, costs, and other information were collected through surveys and structured observations. Drinking water samples taken at the household (geometric mean 7.2 TTC/100 mL, 95% CI, 5.4-9.7) were actually worse in microbiological quality than source water (geometric mean 4.0 TTC/100 mL, 95% CI, 3.1-5.1) (p < 0.001), although both are relatively low levels of contamination. Only 60% of drinking water samples were reported to have actually been boiled at the time of collection from the home, suggesting over-reporting and inconsistent compliance. However, these samples were of no higher microbiological quality. Evidence suggests that water quality deteriorated after boiling due to lack of residual protection and unsafe storage and handling. The potential cost of fuel or electricity for boiling was estimated at 5% and 7% of income, respectively. In this setting where microbiological water quality was relatively good at the source, safe-storage practices that minimize recontamination may be more effective in managing the risk of disease from drinking water at a fraction of the cost of boiling. PMID:21650207

Psutka, Rebecca; Peletz, Rachel; Michelo, Sandford; Kelly, Paul; Clasen, Thomas

2011-07-15

350

Flow Boiling Heat Transfer to Lithium Bromide Aqueous Solution in Subcooled Region  

NASA Astrophysics Data System (ADS)

A theoretical prediction model of the boiling heat transfer coefficient in the subcooled region for water and lithium bromide aqueous solution flowing in a rectangular channel is proposed. In the present heat transfer model, a heat flux is assumed to consist of both the forced convective and the boiling effect components. The forced convective component is evaluated from the empirical correlation of convective heat transfer coefficient for single-phase flow considering the effect of increase of liquid velocity due to net vapor generation. Empirical correlations for determining the heat flux due to the boiling effect and the quality at the onset point of net vapor generation are obtained from the data presented in the first report1). Agreement between the present theoretical prediction and the experimental data is satisfactorily good both for water and lithium bromide aqueous solution.

Kaji, Masao; Furukawa, Masahiro; Nishizumi, Takeharu; Ozaki, Shinji; Sekoguchi, Kotohiko

351

Design and test of a compact optics system for the pool boiling experiment  

NASA Technical Reports Server (NTRS)

The experiment described seeks to improve the understanding of the fundamental mechanisms that constitute nucleate pool boiling. The vehicle for accomplishing this is an investigation, including tests to be conducted in microgravity and coupled with appropriate analyses, of the heat transfer and vapor bubble dynamics associated with nucleation, bubble growth/collapse and subsequent motion, considering the interrelations between buoyancy, momentum and surface tension which will govern the motion of the vapor and surrounding liquid, as a function of the heating rate at the heat transfer surface and the temperature level and distribution in the bulk liquid. The experiment is designed to be contained within the confines of a Get-Away-Special Canister (GAS Can) installed in the bay of the space shuttle. When the shuttle reaches orbit, the experiment will be turned on and testing will proceed automatically. In the proposed Pool Boiling Experiment a pool of liquid, initially at a precisely defined pressure and temperature, will be subjected to a step imposed heat flux from a semitransparent thin-film heater forming part of one wall of the container such that boiling is initiated and maintained for a defined period of time at a constant pressure level. Transient measurements of the heater surface and fluid temperatures near the surface will be made, noting especially the conditions at the onset of boiling, along with motion photography of the boiling process in two simultaneous views, from beneath the heating surface and from the side. The conduct of the experiment and the data acquisition will be completely automated and self-contained. For the initial flight, a total of nine tests are proposed, with three levels of heat flux and three levels of subcooling. The design process used in the development and check-out of the compact photographic/optics system for the Pool Boiling Experiment is documented.

Ling, Jerri S.; Laubenthal, James R.

1990-01-01

352

An experimental study of flow boiling instability in a single microchannel  

Microsoft Academic Search

A simultaneous visualization and measurement study has been carried out to investigate stable and unstable flow boiling phenomena of deionized water in a single microchannel having a hydraulic diameter of 155m with a bottom Pyrex glass wall. Fifteen platinum serpentine microheaters, bonded on the Pyrex glass wall, were used to measure local instantaneous wall temperatures. At low mass flux, a

Guodong Wang; Ping Cheng

2008-01-01

353

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 (0.30.52 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

354

The stress corrosion cracking behavior of austenitic stainless steels in boiling magnesium chloride solutions  

Microsoft Academic Search

The change in the mechanism of stress corrosion cracking with test temperature for Type 304, 310 and 316 austenitic stainless steels was investigated in boiling saturated magnesium chloride solutions using a constant load method. Three parameters (time to failure; tf, steady-state elongation rate; lss and transition time at which a linear increase in elongation starts to deviate; tss) obtained from

Osama M. Alyousif; Rokuro Nishimura

2007-01-01

355

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

356

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

357

Nucleate boiling with high gravity and large subcooling  

SciTech Connect

Measurements of the heater surface temperature are presented for pool boiling of distilled water in an accelerating system with various subcoolings and levels of heat flux. The ranges of the experimental variables are: heat flux between 0.19 MW/m{sup 2} and 1.5 MW/m{sup 2}, accelerations normal to the flat heating surface from 1 to 100 times earth gravity, and liquid subcoolings between 0 and K and 89 K. Increasing subcooling first produces an increase and then a decrease in wall superheat, with the eventual cessation of nucleate boiling for certain combinations of conditions. The increase in wall superheat is particularly enhanced at 10g, reaching a maximum value of 9 K at 1.05 MW/m{sup 2} with 60 K subcooling. This type of behavior is attributed to the interactions between the fluid temperature distribution in the immediate vicinity of the heater surface as it is influenced by natural convection, the activation of nucleation sites, and the influence of increased buoyancy on the heat transfer associated with each departing bubble.

Ulucakli, M.E. (Lafayette Coll., Easton, PA (United States)); Merte, H. Jr. (Univ. of Michigan, Ann Arbor (United States))

1990-05-01

358

A two-dimensional model for boiling in an active particle bed: BOIL  

NASA Astrophysics Data System (ADS)

In order to model two-dimensional boiling in an active particle bed, a two dimensional, steady state, isothermal model was assembled, starting from the mass, momentum, and energy conservation laws. The momentum balance includes capillary and gravity effects and two phase flow pressure losses. This physical description is translated into a mathematical model and implemented as a numerical code, BOIL, using an optimized numerical solving process. One and two-dimensional test cases are run to emphasize the effects of boundary conditions; heat source distribution; relative permeability laws; and Leverett function coefficient. Results allow a good level of confidence in BOIL. Two-dimensional effects of capillary forces are discussed.

Theunissen, P. H.; Buchlin, J. M.

1984-10-01

359

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

360

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

361

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

362

Nucleate pool boiling: High gravity to reduced gravity; liquid metals to cryogens  

NASA Technical Reports Server (NTRS)

Requirements for the proper functioning of equipment and personnel in reduced gravity associated with space platforms and future space station modules introduce unique problems in temperature control; power generation; energy dissipation; the storage, transfer, control and conditioning of fluids; and liquid-vapor separation. The phase change of boiling is significant in all of these. Although both pool and flow boiling would be involved, research results to date include only pool boiling because buoyancy effects are maximized for this case. The effective application of forced convection boiling heat transfer in the microgravity of space will require a well grounded and cogent understanding of the mechanisms involved. Experimental results are presented for pool boiling from a single geometrical configuration, a flat surface, covering a wide range of body forces from a/g = 20 to 1 to a/g = 0 to -1 for a cryogenic liquid, and from a/g = 20 to 1 for water and a liquid metal. Similarities in behavior are noted for these three fluids at the higher gravity levels, and may reasonably be expected to continue at reduced gravity levels.

Merte, Herman, Jr.

1988-01-01

363

Enhancing flow boiling heat transfer in microchannels for thermal management with monolithically-integrated silicon nanowires.  

PubMed

Thermal management has become a critical issue for high heat flux electronics and energy systems. Integrated two-phase microchannel liquid-cooling technology has been envisioned as a promising solution, but with great challenges in flow instability. In this work, silicon nanowires were synthesized in situ in parallel silicon microchannel arrays for the first time to suppress the flow instability and to augment flow boiling heat transfer. Significant enhancement in flow boiling heat transfer performance was demonstrated for the nanowire-coated microchannel heat sink, such as an early onset of nucleate boiling, a delayed onset of flow oscillation, suppressed oscillating amplitudes of temperature and pressure drop, and an increased heat transfer coefficient. PMID:22694316

Li, D; Wu, G S; Wang, W; Wang, Y D; Liu, Dong; Zhang, D C; Chen, Y F; Peterson, G P; Yang, Ronggui

2012-07-11

364

Boil-off experiments with the EIR-NEPTUN Facility: Analysis and code assessment overview report  

SciTech Connect

The NEPTUN data discussed in this report are from core uncovery (boil-off) experiments designed to investigate the mixture level decrease and the heat up of the fuel rod simulators above the mixture level for conditions simulating core boil-off for a nuclear reactor under small break loss-of-coolant accident conditions. The first series of experiments performed in the NEPTUN test facility consisted of ten boil-off (uncovery) and one adiabatic heat-up tests. In these tests three parameters were varied: rod power, system pressure and initial coolant subcooling. The NEPTUN experiments showed that the external surface thermocouples do not cause a significant cooling influence in the rods to which they are attached under boil-off conditions. The reflooding tests performed later on indicated that the external surface thermocouples have some effect during reflooding for NEPTUN electrically heated rod bundle. Peak cladding temperatures are reduced by about 30--40C and quench times occur 20--70 seconds earlier than rods with embedded thermocouples. Additionally, the external surface-thermocouples give readings up to 20 K lower than those obtained with internal surface thermocouples (in the absence of external thermocouples) in the peak cladding temperature zone. Some of the boil-off data obtained from the NEPTUN test facility are used for the assessment of the thermal-hydraulic transient computer codes. These calculations were performed extensively using the frozen version of TRAC-BD1/MOD1 (version 22). A limited number of assessment calculations were done with RELAP5/MOD2 (version 36.02). In this report the main results and conclusions of these calculations are presented with the identification of problem areas in relation to models relevant to boil-off phenomena. On the basis of further analysis and calculations done, changing some of the models such as the bubbly/slug flow interfacial friction correlation which eliminate some of the problems are recommended.

Aksan, S.N.; Stierli, F.; Analytis, G.T. [Paul Scherrer Inst. (PSI), Villigen (Switzerland). Lab. for Thermal-Hydraulics

1992-03-01

365

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

366

Boiling and condensing pumped loop microgravity experiment  

Microsoft Academic Search

Aircraft testing of a boiling and condensing (two-phase) pumped loop system was conducted to investigate transient induced by low gravity (Keplerian) maneuvers. The experiment, unchanged, will repeat a selected aircraft test sequence during its flight aboard a suborbital rocket. Such a test of a two-phase system has never been done. A comparison of aircraft and rocket data, particularly equilibrium conditions,

Vaughn H. Standley; Jerry F. Fairchild

1991-01-01

367

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

368

21 CFR 872.6710 - Boiling water sterilizer.  

Code of Federal Regulations, 2012 CFR

A boiling water sterilizer is an AC-powered device that consists of a container for boiling water. The device is intended to sterilize dental and surgical instruments by submersion in the boiling water in the container. (b) Classification. Class I (general controls). [55 FR 48439,...

2012-04-01

369

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

370

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

371

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

372

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

373

Models and Stability Analysis of Boiling Water Reactors  

SciTech Connect

We have studied the nuclear-coupled thermal-hydraulic stability of boiling water reactors (BWRs) using a model that includes: space-time modal neutron kinetics based on spatial w-modes; single- and two-phase flow in parallel boiling channels; fuel rod heat conduction dynamics; and a simple model of the recirculation loop. The BR model is represented by a set of time-dependent nonlinear ordinary differential equations, and is studied as a dynamical system using the modern bifurcation theory and nonlinear dynamical systems analysis. We first determine the stability boundary (SB) - or Hopf bifurcation set- in the most relevant parameter plane, the inlet-subcooling-number/external-pressure-drop plane, for a fixed control rod induced external reactivity equal to the 100% rod line value; then we transform the SB to the practical power-flow map used by BWR operating engineers and regulatory agencies. Using this SB, we show that the normal operating point at 100% power is very stable, that stability of points on the 100% rod line decreases as the flow rate is reduced, and that operating points in the low-flow/high-power region are least stable. We also determine the SB that results when the modal kinetics is replaced by simple point reactor kinetics, and we thereby show that the first harmonic mode does not have a significant effect on the SB. However, we later show that it nevertheless has a significant effect on stability because it affects the basin of attraction of stable operating points. Using numerical simulations we show that, in the important low-flow/high-power region, the Hopf bifurcation that occurs as the SB is crossed is subcritical; hence, growing oscillations can result following small finite perturbations of stable steady-states on the 100% rod line at points in the low-flow/high-power region. Numerical simulations are also performed to calculate the decay ratios (DRs) and frequencies of oscillations for various points on the 100% rod line. It is determined that the U.S. NRC requirement of DR is not rigorously satisfied in the low-flow/high-power region; hence, this region should be avoided during normal startup and shutdown operations. The frequency of oscillation is shown to decrease as the flow rate is reduced. Moreover, the simulation frequency of 0.5Hz determined in the low-flow/high-power region is consistent with those observed during actual instability incidents. Additional numerical simulations show that in the low-flow/high-power region, for the same initial conditions, the use of point kinetics leads to damped oscillations, whereas the model that includes the modal neutron kinetics equations results in growing nonlinear oscillations.

John Dorning

2002-04-15

374

ILD 7 Name: ____________________ Tutorial section _______ Heat & temperature: More reconciling  

E-print Network

temperature? A. Two hours before this lecture, a cup of boiling water and a cup of cold water from or at different temperatures? Why? 2. Would you expect the (formerly) boiling water to have a temperature greater temperature (20° C) is about to be dunked in ice water (0° C). After it's dunked, we'll continually measure

Maryland at College Park, University of

375

Nucleate boiling pressure drop in an annulus: Book 5  

SciTech Connect

The application of the work described in this report is the production reactors at the Savannah River Site, and the context is nuclear reactor safety. The Loss of Coolant Accident (LOCA) scenario considered involves a double-ended break of a primary coolant pipe in the reactor. During a LOCA, the flow through portions of the reactor may reverse direction or be greatly reduced, depending upon the location of the break. The reduced flow rate of coolant (D{sub 2}O) through the fuel assembly channels of the reactor -- downflow in this situation -- can lead to boiling and to the potential for flow instabilities which may cause some of the fuel assembly channels to overheat and melt. That situation is to be avoided. The experimental approach is to provide a test annulus which simulates geometry, materials, and flow conditions in a Mark-22 fuel assembly (Coolant Channel 3) to the extent possible. The key analysis approaches are: To compare the minima in the measured demand curves with analytical criteria, in particular the Saha-Zuber (1974) model; and to compare the pressure and temperature as a function of length in the annulus with an integral model for flow boiling in a heated channel. Nineteen test series and a total of 178 tests were performed. Testing addressed the effects of: Heat flux; pressure; helium gas; power tilt; ribs; asymmetric heat flux. This document consists solely of the plato file index from 11/87 to 11/90.

Not Available

1992-11-01

376

A new temperaturethermal conductivity relationship for predicting saturated liquid thermal conductivity  

Microsoft Academic Search

A new temperaturethermal conductivity relationship similar to the Rackett equation for saturated liquid densities is proposed. The first-order group contribution values proposed earlier for predicting the thermal conductivity at the normal boiling point [S.R.S. Sastri, K.K. Rao, Chem. Eng. 100(8) (1993) 106107] are revised. Combining these two, the thermal conductivities of organic liquids are predicted over the entire saturated liquid

S. R. S. Sastri; K. K. Rao

1999-01-01

377

Temperature dependent dielectric function and the E{sub 0} critical points of hexagonal GaN from 30 to 690 K  

SciTech Connect

The complex dielectric function ? and the E{sub 0} excitonic and band-edge critical-point structures of hexagonal GaN are reported for temperatures from 30 to 690 K and energies from 0.74 to 6.42 eV, obtained by rotating-compensator spectroscopic ellipsometry on a 1.9 ?m thick GaN film deposited on a c-plane (0001) sapphire substrate by molecular beam epitaxy. Direct inversion and B-splines in a multilayer-structure calculation were used to extract the optical properties of the film from the measured pseudodielectric function ???. At low temperature sharp E{sub 0} excitonic and critical-point interband transitions are separately observed. Their temperature dependences were determined by fitting the data to the empirical Varshni relation and the phenomenological expression that contains the Bose-Einstein statistical factor.

Kim, Tae Jung, E-mail: tjkim@khu.ac.kr; Hwang, Soon Yong; Byun, Jun Seok; Barange, Nilesh S.; Park, Han Gyeol; Dong Kim, Young, E-mail: ydkim@khu.ac.kr [Nano-Optical Property Laboratory and Department of Physics, Kyung Hee University, Seoul 130-701 (Korea, Republic of)

2014-02-15

378

(Investigation of subcooled hydrothermal boiling in ground water flow channels as a source of harmonic tremors)  

SciTech Connect

As a first step toward assessing the ability of hydrothermal boiling to explain geothermal ground noise and volcanic tremor observations, we are investigating the acoustic power spectrum of boiling (the source'' spectrum in the above model). We simulate boiling in the lab by injecting high pressure steam from a boiler into a pressure vessel filled with water. The water pressure fluctuations that result from the repeated formation and collapse of steam bubbles at the steam inlet vents are recorded by a hydrophone whose output is digitized at 2 {times} 10{sup 4} samples/second by a computer. The range of pressure and temperature conditions attainable within the pressure vessel is limited to <3.5 bars, <139{degree}C, due to the finite strength of observation windows affixed to the pressure vessel. Therefore, dimensional analysis will be used to correlate the experimental results with the pertinent experimental variables. Besides the overall shape of the boiling power spectrum, we are investigating the absolute spectral levels in frequency bands typical of geothermal ground noise and volcanic tremor (0.5 Hz-10 Hz), and the ratio of acoustic power liberated to total available power. The values of these parameters are critical to hydrothermal boiling's ability to generate ground motion amplitudes in accordance with observation. If it can be shown that the range of observed ground noise/tremor amplitudes can be accounted for by hydrothermal boiling at reasonable heat transfer rates, this knowledge would be invaluable to designers of seismic monitoring experiments who are interested in geothermal resource exploration/evaluation and volcanic eruption prediction.

Not Available

1989-01-01

379

Potential risk of bisphenol A migration from polycarbonate containers after heating, boiling, and microwaving.  

PubMed

The migration levels of bisphenol A (BPA) were analyzed in food samples by high-performance liquid chromatography (HPLC) from polycarbonate (PC) bottles subjected to simulated use by heating with microwave, heating in a boiling water bath, or filling them with boiling hot water (100 degrees C). Migration testing performed in PC bottles filled with steamed rice or hot cooked pork, standing at room temperature, or heated in a boiling water bath (100 degrees C) showed that BPA was not detected at the limit of detection (LOD) of 1 microg/L (ppb). In contrast, heating by microwaving to 100 degrees C for 9 min increased BPA migration levels from 6 to 18 ppb and from 5 to 15 ppb for steamed rice or for cooked pork, respectively. In addition, 3 different PC bottles were tested by filling them with boiling hot water (100 degrees C) and leaving them to stand at room temperature for up to 3 h. The mean BPA levels from the bottles increased in a time-dependent manner, with the range of not detected (ND) to 2.5 ppb after 60 min. However, none of the PC bottles released BPA at levels that exceed the recently established specific migration limits (SML) of 600 ppb established by European Union and Korea Food and Drug Administration (KFDA). Data suggest that the use of PC plastic bottles in our daily life is considered safe in Korea. PMID:20077198

Lim, Duck Soo; Kwack, Seung Jun; Kim, Kyu-Bong; Kim, Hyung Sik; Lee, Byung Mu

2009-01-01

380

Pressure drop, heat transfer, critical heat flux, and flow stability of two-phase flow boiling of water and ethylene glycol/water mixtures - final report for project "Efficent cooling in engines with nucleate boiling."  

SciTech Connect

Because of its order-of-magnitude higher heat transfer rates, there is interest in using controllable two-phase nucleate boiling instead of conventional single-phase forced convection in vehicular cooling systems to remove ever increasing heat loads and to eliminate potential hot spots in engines. However, the fundamental understanding of flow boiling mechanisms of a 50/50 ethylene glycol/water mixture under engineering application conditions is still limited. In addition, it is impractical to precisely maintain the volume concentration ratio of the ethylene glycol/water mixture coolant at 50/50. Therefore, any investigation into engine coolant characteristics should include a range of volume concentration ratios around the nominal 50/50 mark. In this study, the forced convective boiling heat transfer of distilled water and ethylene glycol/water mixtures with volume concentration ratios of 40/60, 50/50, and 60/40 in a 2.98-mm-inner-diameter circular tube has been investigated in both the horizontal flow and the vertical flow. The two-phase pressure drop, the forced convective boiling heat transfer coefficient, and the critical heat flux of the test fluids were determined experimentally over a range of the mass flux, the vapor mass quality, and the inlet subcooling through a new boiling data reduction procedure that allowed the analytical calculation of the fluid boiling temperatures along the experimental test section by applying the ideal mixture assumption and the equilibrium assumption along with Raoult's law. Based on the experimental data, predictive methods for the two-phase pressure drop, the forced convective boiling heat transfer coefficient, and the critical heat flux under engine application conditions were developed. The results summarized in this final project report provide the necessary information for designing and implementing nucleate-boiling vehicular cooling systems.

Yu, W.; France, D. M.; Routbort, J. L. (Energy Systems)

2011-01-19

381

A review of the deformation behavior of tungsten at temperatures less than 0.2 of the melting point /K/  

NASA Technical Reports Server (NTRS)

The deformation behavior of tungsten at temperatures below 0.2 times the absolute melting temperature is reviewed with primary emphasis on the temperature dependence of the yield stress and the ductile-brittle transition. It is concluded that a model based on the high Peierls stress of tungsten best accounts for the observed mechanical behavior at low temperatures. Recent research suggests an important role of electron concentration and bonding on the mechanical behavior of tungsten. Future research on tungsten should include studies to define more clearly the correlation between electron concentration and mechanical behavior of alloys of tungsten and other transition metal alloys.

Stephens, J. R.

1974-01-01

382

Conjugate thermal and hydrodynamic analyses of saturated film boiling from a horizontal surface  

SciTech Connect

Film boiling is characterized by the existence of a continuous vapor layer between a heated solid surface and a liquid layer. The evolution of the vapor-liquid interface during film boiling on a horizontal surface is determined by Rayleigh-Taylor instability. To predict the heat transfer rates in film boiling, many studies have been reported in literature. Early attempts to model this phenomenon had used semi-empirical correlations. Recent work on simulation of the evolution of vapor-liquid interface without assuming any empirical vapor-liquid interface shape and by assuming the solid surface temperature to be constant has shown that the convective heat transfer coefficients, associated with the interface, vary both spatially and temporally. Consequently, the assumption of constant solid surface temperature in film boiling is not strictly valid. In this work, saturated film boiling on a horizontal surface is simulated numerically. Finite difference method is used to simultaneously solve the equations governing conservation of mass, momentum and energy in the vapor and liquid layers. The equations for the two fluid phases are coupled through matching of normal and tangential stresses and continuity of mass and energy at the liquid vapor interface. Second order projection method is used along with numerical grid generation to construct a grid system which is aligned with the vapor-liquid interface. The heat conduction equation is solved separately in the solid, to obtain the wall temperature. The results show that for most surfaces little coupling takes place between thermal response of the solid substrate and hydrodynamics of evolution of the interface. However, for thin plate heaters of relatively low thermal conductivity materials, the thermal response of the solid can significantly affect the hydrodynamics of the interface and in turn the local heat transfer.

Banerjee, D.; Son, G.; Dhir, V.K. [Univ. of California, Los Angeles, CA (United States). Mechanical and Aerospace Engineering Dept.

1996-12-31

383

Enhancement of Pool Boiling Heat Transfer and Control of Bubble Motion in Microgravity Using Electric Fields - BCOEL  

NASA Technical Reports Server (NTRS)

The BCOEL project focuses on improving pool boiling heat transfer and bubble control in microgravity by exposing the fluid to electric fields. The electric fields induce a body force that can replace gravity in the low gravity environment, and enhance bubble removal from thc heated surface. A better understanding of microgravity effects on boiling with and without electric fields is critical to the proper design of the phase-change-heat-removal equipment for use in space-based applications. The microgravity experiments will focus on the visualization of bubble formation and shape during boiling. Heat fluxes on the boiling surface will be measured, and, together with the measured driving temperature differences, used to plot boiling curvcs for different electric field magnitudes. Bubble formation and boiling processes were found to be extremely sensitive to g-jitter. The duration of the experimental run is critical in order to achieve steady state in microgravity experiments. The International Space Station provides conditions suitable for such experiments. The experimental appararus to be used in the study is described in the paper. The apparatus will be tested in the KC-135 first, and microgravity experiments will be conducted on board of the International Space Station using the Microgravity Science Glovebox as the experimental platform.

Herman, Cila; Iacona, Estelle; Acquaviva, Tom; Coho, Bill; Grant, Nechelle; Nahra, Henry; Sankaran, Subramanian; Taylor, Al; Julian, Ed; Robinson, Dale; VanZandt, Dave

2001-01-01

384

Enhancement of Pool Boiling Heat Transfer and Control of Bubble Motion in Microgravity Using Electric Fields (BCOEL)  

NASA Technical Reports Server (NTRS)

The BCOEL project focuses on improving pool boiling heat transfer and bubble control in microgravity by exposing the fluid to electric fields. The electric fields induce a body force that can replace gravity in the low gravity environment, and enhance bubble removal from the heated surface. A better understanding of microgravity effects on boiling with and without electric fields is critical to the proper design of the phase-change-heat-removal equipment for use in spacebased applications. The microgravity experiments will focus on the visualization of bubble formation and shape during boiling. Heat fluxes on the boiling surface will be measured, and, together with the measured driving temperature differences, used to plot boiling curves for different electric field magnitudes. Bubble formation and boiling processes were found to be extremely sensitive to g-jitter. The duration of the experimental run is critical in order to achieve steady state in microgravity experiments. The International Space Station provides conditions suitable for such experiments. The experimental apparatus to be used in the study is described in the paper. The apparatus will be tested in the KC-135 first, and microgravity experiments will be conducted on board of the International Space Station using the Microgravity Science Glovebox as the experimental platform.

Herman, Cila; Iacona, Estelle; Acquaviva, Tom; Coho, Bill; Grant, Nechelle; Nahra, Henry; Taylor, Al; Julian, Ed; Robinson, Dale; VanZandt, Dave

2001-01-01

385

Observational study of pool boiling under microgravity  

Microsoft Academic Search

Pool boiling experiments under microgravity were conducted, utilizing parabolic flight maneuvers with a CNES Caravelle 6R aircraft. The experimental apparatus taken aboard the aircraft was constructed to enable simultaneous recording, by a video camera, of the side view of vapor bubbles generated on Joule-heated titanium foil immersed in a pool of n-pentane liquid, and the color pattern exhibited by a

Toshiharu Oka; Yoshiyuki Abe; Kotaro Tanaka; Yasuhiko H. Mori; Akira Nagashima

1992-01-01

386

Investigation of vapor film motion regularities at boiling liquids  

NASA Astrophysics Data System (ADS)

The experimental investigation of the saturated Freon-113 and distilled water film boiling on spheres with different diameters at atmospheric pressure under conditions of free convection is executed. With high-speed video average thickness and cumulative distribution function of vapor film as a function of the angle was measured. It was found that with increasing the angle the average thickness of vapor film can change by different laws depending on diameter of the sphere and the temperature difference. It was found also that the increase in the average vapor film thickness with increasing angle is more connected with the increase of large components of cumulative distribution function. It also noted the presence of quasi-periodic pulsations of the vapor film thickness in the lower part, which eventually largely determine the behavior of the interface at large angles.

Agaltsov, A.; Zeigarnik, Y. U.

2013-04-01

387

Wave soldering with a low melting point Bi-Sn Alloy: Effects of soldering temperatures and circuit board finishes  

Microsoft Academic Search

Wave soldering with low solid fluxes at temperatures as low as 175C on test boards with a Cu\\/Imidazole surface finish has\\u000a been shown to be feasible using a Pb-free, Bi-45%Sn-0.33%Ag solder that melts at temperatures of ?140?145C. Other surface\\u000a finishes such as Pd\\/Ni, Au\\/Ni, and Bi exhibit unacceptable soldering at temperatures below 210C. Intermediate in performance\\u000a are Sn surface finishes,

M. Mc Cormack; I. Artaki; S. Jin; A. M. Jackson; D. M. Machusak; G. W. Kammlott; D. W. Finley

1996-01-01

388

Mantle eclogites and garnet pyroxenites - the meaning of two-point isochrons, Sm-Nd and Lu-Hf closure temperatures and the cooling of the subcratonic mantle  

NASA Astrophysics Data System (ADS)

The Earth's mantle is a huge metamorphic complex which undergoes permanent changes ruled by plate tectonics. It also has enclaves underneath Archean crust which are exempt from the convecting mantle since at least 2.5 Ga. Since then, this mantle may cool slowly as a result of diminishing heat input from the asthenosphere, of declining heat production from radioactive decay and of denudation of the crust. Under such circumstances, two point garnet-clinopyroxene isochrons from mantle xenoliths (here garnet pyroxenites and eclogites) reflect either cooling ages or eruption ages depending on whether the mantle portion under consideration was below or above the closure temperature of a radiogenic system. Available literature data from the Slave and Kaapvaal craton for the Sm-Nd and Lu-Hf isotope systems and our own new data from Bellsbank (Kaapvaal) provide a whole range of two-point isochron ages from younger than the kimberlite eruption age to early Proterozoic. The meaning of ages other than the kimberlite eruption age is unclear. We use here a compilation of Sm-Nd and Lu-Hf two-point isochron age data from this study and the literature, to assess the meaning of such isochrons. This is achieved by plotting the temperature of last equilibration as derived from the Fe-Mg exchange between garnet and clinopyroxene versus the two-point isochron age. There is a low temperature alignment for both systems of increasing age with decreasing temperature and an alignment around the kimberlite eruption ages at high temperatures. We interpret the intersect between the low temperature limb and the kimberlite eruption age as closure temperature which gives about 920 C for the Lu-Hf system and about 850 C for the Sm-Nd system. The differences of the cooling ages between the two isotope systems for individual samples combined with the closure temperatures from this study are used to deduce the cooling of the Slave and Kaapvaal subcratonic mantle from the early Proterozoic until today. We deduce that the subcratonic mantle cooled since 2 Ga from a geothermal gradient of 46 mW/m to 38 mW/m at 120 Ma ago with a rate of around 0.1 C/Ma. This value is in agreement with previous estimates which were based on various geophysical and geological constraints, heat production by radioactive elements and diffusivity of radiogenic elements.

Shu, Qiao; Brey, Gerhard P.; Gerdes, Axel; Hoefer, Heidi E.

2014-03-01

389

Measurements of the Electric Field of Zero-Point Optical Phonons in GaAs Quantum Wells Support the Urbach Rule for Zero-Temperature Lifetime Broadening  

NASA Astrophysics Data System (ADS)

We study a specific type of lifetime broadening resulting in the well-known exponential "Urbach tail" density of states within the energy gap of an insulator. After establishing the frequency and temperature dependence of the Urbach edge in GaAs quantum wells, we show that the broadening due to the zero-point optical phonons is the fundamental limit to the Urbach slope in high-quality samples. In rough analogy with Welton's heuristic interpretation of the Lamb shift, the zero-temperature contribution to the Urbach slope can be thought of as arising from the electric field of the zero-point longitudinal-optical phonons. The value of this electric field is experimentally measured to be 3 kV cm-1 , in excellent agreement with the theoretical estimate.

Bhattacharya, Rupak; Mondal, Richarj; Khatua, Pradip; Rudra, Alok; Kapon, Eli; Malzer, Stefan; Dhler, Gottfried; Pal, Bipul; Bansal, Bhavtosh

2015-01-01

390

Critical boiling phenomena observed in microgravity  

NASA Astrophysics Data System (ADS)

Singular thermodynamic properties of pure fluids near their critical point (diverging specific heat and isothermal compressibility, vanishing thermal conductivity,...) lead to poor thermal diffusion, a large convective sensitivity, and a special heat transfer process through adiabatic compression, the so-called piston effect. The discovery and extensive study of the piston effect were performed in conditions of weightlessness to avoid convection. Although its mechanism in the supercritical range is now well understood, its coupling with an inhomogeneous density distribution and mass transport in the two-phase regime has been relatively less studied and remains puzzling. Recent experiments performed in the French Alice 2 facility built by CNES onboard the Mir station showed undoubtedly that when a liquid-vapor system of SF6 near its critical temperature is heated in microgravity, the apparent contact angle becomes very large (up to 110). In this slightly out-of-equilibrium configuration the gas appears to ``wet'' the solid surface. In addition, the temperature of the vapor becomes higher than that of the hot wall, whereas the temperature of the liquid evolves qualitatively as in the one-phase regime. Although the difference between the compressibility of liquid and vapor explains a higher vapor temperature compared to the liquid temperature, this paradoxical observation has not yet been modeled. Moreover, the phase distribution plays an important role in the efficiency of the heat transfer near the critical point. A three domains model valid at short time scale is presented. It is similar to the model of supercritical piston effect from Onuki, Hao and Ferrel (Onuki, 1990a), and takes into account the presence of a liquid wetting layer. Indeed, the thermal boundary layer only develops inside the liquid phase and compresses the vapor phase, in contrast to the situation in the one-phase regime. The leading characteristic time of the piston effect in the two-phase regime depends on the compressibility ratio between the two phases. It is larger than for a single liquid phase. Good agreement is obtained between the experimental and theoretical temperature evolution curves in both phases. .

Garrabos, Yves; Wunenburger, Rgis; Hegseth, John; Lecoutre-Chabot, Carole; Beysens, Daniel

2000-01-01

391

Prospective Chemistry Teachers' Misconceptions about Colligative Properties: Boiling Point Elevation and Freezing Point Depression  

ERIC Educational Resources Information Center

This study aimed at identifying prospective chemistry teachers' misconceptions of colligative properties. In order to fulfill this aim, a diagnostic test composed of four open-ended questions was used. The test was administered to seventy-eight prospective chemistry teachers just before qualifying to teaching in secondary schools. Nine different

Pinarbasi, Tacettin; Sozbilir, Mustafa; Canpolat, Nurtac

2009-01-01

392

Novel system to interrogate distributed fiber strain sensors and point temperature sensors based on pulse correlation and FBGs  

Microsoft Academic Search

We are going to present and demonstrated the feasibility of a novel sensor interrogation scheme that combines the advantages of the distributed and point sensor systems using a robust interrogation technique. The experimental results show the high linearity and stability of the measurements. Also, our proposed scheme uses a tunable source with optical elements that have very few losses. Thus,

Antonio Bueno; Koji Nonaka; Salvador Sales

2009-01-01

393

High-temperature point-contact transistors and Schottky diodes formed on synthetic boron-doped diamond  

Microsoft Academic Search

Point-contact transistors and Schottky diodes have been formed on synthetic boron-doped diamond. This is the first report of diamond transistors that have power gain. Further, the transistors exhibited power gain at 510C and the Schottky diodes were operational at 700C.

M. W. Geis; D. D. Rathman; D. J. Ehrlich; R. A. Murphy; W. T. Lindley

1987-01-01

394

Determination of optimal converting point of color temperature conversion complied with ANSI C78. 377 for indoor solid-state lighting and display applications.  

PubMed

In recent years, displays and lighting require color temperature (CT) conversion function because observers have different preferences. This paper proposes effective methods to determine the optimal converting point of CT conversion for display and lighting application. For display application, the concepts of center of gravity and isotemperature line are applied to determine the optimal converting point. The maximal enhancement of luminance between the optimal and average is 18%. For lighting application, this paper proposes two methods to determine the optimal converting point in the CT quadrangle which complies with ANSI C78. 377. The enhancement of luminance in two CT modes (5700K and 6500K) are 14.2% and 23.6%, respectively. PMID:23037058

Hsieh, Yao-Fang; Ou-Yang, Mang; Huang, Ting-Wei; Lee, Cheng-Chung

2012-08-27

395

Experimental Investigation of Pool Boiling Heat Transfer Enhancement in Microgravity in the Presence of Electric Fields  

NASA Technical Reports Server (NTRS)

Boiling is an effective mode of heat transfer since high heat flux levels are possible driven by relatively small temperature differences. The high heat transfer coefficients associated with boiling have made the use of these processes increasingly attractive to aerospace engineering. Applications of this type include compact evaporators in the thermal control of aircraft avionics and spacecraft environments, heat pipes, and use of boiling to cool electronic equipment. In spite of its efficiency, cooling based on liquid-vapor phase change processes has not yet found wide application in aerospace engineering due to specific problems associated with the low gravity environment. After a heated surface has reached the superheat required for the initiation of nucleate boiling, bubbles will start forming at nucleation sites along the solid interface by evaporation of the liquid. Bubbles in contact with the wall will continue growing by this mechanism until they detach. In terrestrial conditions, bubble detachment is determined by the competition between body forces (e.g. buoyancy) and surface tension forces that act to anchor the bubble along the three phase contact line. For a given body force potential and a balance of tensions along the three phase contact line, bubbles must reach a critical size before the body force can cause them to detach from the wall. In a low gravity environment the critical bubble size for detachment is much larger than under terrestrial conditions, since buoyancy is a less effective means of bubble removal. Active techniques of heat transfer enhancement in single phase and phase change processes by utilizing electric fields have been the subject of intensive research during recent years. The field of electrohydrodynamics (EHD) deals with the interactions between electric fields, flow fields and temperature fields. Previous studies indicate that in terrestrial applications nucleate boiling heat transfer can be increased by a factor of 50 as compared to values obtained for the same system without electric fields. Imposing an external electric field holds the promise to improve pool boiling heat transfer in low gravity, since a phase separation force other than gravity is introduced. The goal of our research is to experimentally investigate the potential of EHD and the mechanisms responsible for EHD heat transfer enhancement in boiling in low gravity conditions.

Herman, Cila

1996-01-01

396

Single-bubble dynamics in pool boiling of one-component fluids.  

PubMed

We numerically investigate the pool boiling of one-component fluids with a focus on the effects of surface wettability on the single-bubble dynamics. We employed the dynamic van der Waals theory [Phys. Rev. E 75, 036304 (2007)], a diffuse-interface model for liquid-vapor flows involving liquid-vapor transition in nonuniform temperature fields. We first perform simulations for bubbles on homogeneous surfaces. We find that an increase in either the contact angle or the surface superheating can enhance the bubble spreading over the heating surface and increase the bubble departure diameter as well and therefore facilitate the transition into film boiling. We then examine the dynamics of bubbles on patterned surfaces, which incorporate the advantages of both hydrophobic and hydrophilic surfaces. The central hydrophobic region increases the thermodynamic probability of bubble nucleation while the surrounding hydrophilic region hinders the continuous bubble spreading by pinning the contact line at the hydrophobic-hydrophilic intersection. This leads to a small bubble departure diameter and therefore prevents the transition from nucleate boiling into film boiling. With the bubble nucleation probability increased and the bubble departure facilitated, the efficiency of heat transfer on such patterned surfaces is highly enhanced, as observed experimentally [Int. J. Heat Mass Transfer 57, 733 (2013)]. In addition, the stick-slip motion of contact line on patterned surfaces is demonstrated in one-component fluids, with the effect weakened by surface superheating. PMID:25019874

Xu, Xinpeng; Qian, Tiezheng

2014-06-01

397

Boiling heat transfer in reduced gravity during quenching of a hot surface with R-113  

SciTech Connect

An experimental study of the flow boiling heat transfer characteristics under microgravity conditions is presented. The experiments were conducted using R-113 by rewetting a heated bottom plate of a rectangular channel, 40 mm wide, 5 mm high and 200 mm long, aboard the KC-135 parabolic aircraft. The local surface heat flux and temperature were measured by a 2-{micro}m thick micro sensor directly fabricated on the surface of the heated plate. The film boiling heat transfer coefficients in microgravity were 70% to 80% of the values in normal gravity, and the results in both gravity conditions showed reasonable agreement with the predictions of Bromley (1953) correlation. Under microgravity, the flow rate had less effect but subcooling had a significant effect on nucleate boiling heat transfer. The effect of microgravity is similar to that due to the absence of subcooling in normal gravity, because both result in a thicker and more stable vapor layer. Also, the nucleate boiling regime covered a wider range of wall superheat below the maximum heat flux in the absence of gravity or subcooling than in the case of high subcooling and normal gravity.

Xu, J.J.; Adham-Khodaparast, K.; Kawaji, M. [Univ. of Toronto, Ontario (Canada). Dept. of Chemical Engineering and Applied Chemistry

1995-12-31

398

Bubble Departure from Metal-Graphite Composite Surfaces and Its Effects on Pool Boiling Heat Transfer  

NASA Technical Reports Server (NTRS)

The formation and growth processes of a bubble in the vicinity of graphite micro-fiber tips on metal-graphite composite boiling surfaces and their effects on boiling behavior are investigated. It is discovered that a large number of micro bubbles are formed first at the micro scratches and cavities on the metal matrix in pool boiling. By virtue of the non-wetting property of graphite, once the growing micro bubbles touch the graphite tips, the micro bubbles are sucked by the tips and merged into larger micro bubbles sitting on the end of the tips. The micro bubbles grow rapidly and coalesce to form macro bubbles, each spanning several tips. The necking process of a detaching macro bubble is analyzed. It is revealed that a liquid jet is produced by sudden break-off of the bubble throat. The composite surfaces not only have higher temperatures in micro- and macrolayers but also make higher frequency of the bubble departure, which increase the average heat fluxes in both the bubble growth stage and in the bubble departure period. Based on these analyses, the enhancement mechanism of pool boiling heat transfer on composite surfaces is clearly revealed.

Chao, David F.; Sankovic, John M.; Motil, Brian J.; Yang, W-J.; Zhang, Nengli

2010-01-01

399

A review on boiling heat transfer enhancement with nanofluids  

PubMed Central

There has been increasing interest of late in nanofluid boiling and its use in heat transfer enhancement. This article covers recent advances in the last decade by researchers in both pool boiling and convective boiling applications, with nanofluids as the working fluid. The available data in the literature is reviewed in terms of enhancements, and degradations in the nucleate boiling heat transfer and critical heat flux. Conflicting data have been presented in the literature on the effect that nanofluids have on the boiling heat-transfer coefficient; however, almost all researchers have noted an enhancement in the critical heat flux during nanofluid boiling. Several researchers have observed nanoparticle deposition at the heater surface, which they have related back to the critical heat flux enhancement. PMID:21711794

2011-01-01

400

Numerical Simulation on Single Bubble Pool Boiling with Influence of Heater Thermal Capacity  

NASA Astrophysics Data System (ADS)

The model of single bubble pool boiling is used to simulate nucleate pool boiling phenomenon in the present paper. Local convection and heat transfer around a single vapour bubble which is growing from a nucleus bubble planted artificially on the surface of heaters with different thicknesses, as well as transient heat conduction inside the heaters wall, are simulated numerically with sharp interface representation. Multi-cycle simulation is adopted to eliminate the effect of un-physical initial conditions. Its found that the thermal response of wall is found to affect the bubble growth and boiling heat transfer. During the process of bubble growth, a sharp temperature drop inside the solid wall is evident near the contact line underneath the growing bubble because of the strong evaporation in micro-region. The temperature and heat flux profiles change with the move of the contact line, and twice sharp temperature drops at a certain location are observed, which correspond to the expanding and recoiling processes, respectively. During the waiting period after the bubble detached from the wall, the temperature field is recovered by heat conduction inside the solid wall. As a part of preparation of the SOBER project onboard the Chinese recoverable satellite SJ-10, which will be launched in the end of 2015, the gravity influence is also studied.

Zhao, Jian-Fu; Zhang, Liang; Li, Zhen-Dong

401

Experimental Investigation of Pool Boiling Heat Transfer Enhancement in Microgravity in the Presence of Electric Fields  

NASA Technical Reports Server (NTRS)

In boiling high heat fluxes are possible driven by relatively small temperature differences, which make its use increasingly attractive in aerospace applications. The objective of the research is to develop ways to overcome specific problems associated with boiling in the low gravity environment by substituting the buoyancy force with the electric force to enhance bubble removal from the heated surface. Previous studies indicate that in terrestrial applications nucleate boiling heat transfer can be increased by a factor of 50, as compared to values obtained for the same system without electric fields. The goal of our research is to experimentally explore the mechanisms responsible for EHD heat transfer enhancement in boiling in low gravity conditions, by visualizing the temperature distributions in the vicinity of the heated surface and around the bubble during boiling using real-time holographic interferometry (HI) combined with high-speed cinematography. In the first phase of the project the influence of the electric field on a single bubble is investigated. Pool boiling is simulated by injecting a single bubble through a nozzle into the subcooled liquid or into the thermal boundary layer developed along the flat heater surface. Since the exact location of bubble formation is known, the optical equipment can be aligned and focused accurately, which is an essential requirement for precision measurements of bubble shape, size and deformation, as well as the visualization of temperature fields by HI. The size of the bubble and the frequency of bubble departure can be controlled by suitable selection of nozzle diameter and mass flow rate of vapor. In this approach effects due to the presence of the electric field can be separated from effects caused by the temperature gradients in the thermal boundary layer. The influence of the thermal boundary layer can be investigated after activating the heater at a later stage of the research. For the visualization experiments a test cell was developed. All four vertical walls of the test cell are transparent, and they allow transillumination with laser light for visualization experiments by HI. The bottom electrode is a copper cylinder, which is electrically grounded. The copper block is heated with a resistive heater and it is equipped with 6 thermocouples that provide reference temperatures for the measurements with HI. The top electrode is a mesh electrode. Bubbles are injected with a syringe into the test cell through the bottom electrode. The working fluids presently used in the interferometric visualization experiments, water and PF 5052, satisfy requirements regarding thermophysical, optical and electrical properties. A 30kV power supply equipped with a voltmeter allows to apply the electric field to the electrodes during the experiments. The magnitude of the applied voltage can be adjusted either manually or through the LabVIEW data acquisition and control system connected to a PC. Temperatures of the heated block are recorded using type-T thermocouples, whose output is read by a data acquisition system. Images of the bubbles are recorded with 35mm photographic and 16mm high-speed cameras, scanned and analyzed using various software packages. Visualized temperature fields HI allows the visualization of temperature fields in the vicinity of bubbles during boiling in the form of fringes. Typical visualized temperature distributions around the air bubbles injected into the thermal boundary layer in PF5052 are shown. The temperature of the heated surface is 35 C. The temperature difference for a pair of fringes is approximately 0.05 C. The heat flux applied to the bottom surface is moderate, and the fringe patterns are regular. In the image a bubble penetrating the thermal boundary layer is visible. Because of the axial symmetry of the problem, simplified reconstruction techniques can be applied to recover the temperature field. The thermal plume developing above the heated surface for more intensive heating is shown. The temperature distribution in the liquid is clearly 3D, and

Herman, Cila

1999-01-01

402

WALL-TO-FLUID TRANSFER MECHANISMS IN BOILING FLOWS  

Microsoft Academic Search

To better understand and predict the boiling flow processes, accurate two-fluid numerical models are needed. One of the important goals of the NURESIM project is to assess and improve the simulation capability of the three-dimensional two-fluid codes for prediction of local boiling flow processes. The boiling flow is strongly affected by local mechanisms in the turbulent boundary layer near the

Mavko Borut

2005-01-01

403

Resistivity During Boiling in the SB-15-D Core from the Geysers Geothermal Field: The Effects of Capillarity  

SciTech Connect

In a laboratory study of cores from borehole SB-15-D in The Geysers geothermal area, we measured the electrical resistivity of metashale with and without pore-pressure control, with confining pressures up to 100 bars and temperatures between 20 and 150 C, to determine how the pore-size distribution and capillarity affected boiling. We observed a gradual increase in resistivity when the downstream pore pressure or confining pressure decreased below the phase boundary of free water. For the conditions of this experiment, boiling, as indicated by an increase in resistivity, is initiated at pore pressures of approximately 0.5 to 1 bar (0.05 to 0.1 MPa) below the free-water boiling curve, and it continues to increase gradually as pressure is lowered to atmospheric. A simple model of the effects of capillarity suggests that at 145 C, less than 15% of the pore water can boil in these rocks. If subsequent experiments bear out these preliminary observations, then boiling within a geothermal reservoir is controlled not just by pressure and temperature but also by pore-size distribution. Thus, it may be possible to determine reservoir characteristics by monitoring changes in electrical resistivity as reservoir conditions change.

Roberts, J.; Duba, A.; Bonner, B.; Kasameyer, P.

1997-01-01

404

Prediction of Parameters Distribution of Upward Boiling Two-Phase Flow With Two-Fluid Models  

SciTech Connect

In this paper, a multidimensional two-fluid model with additional turbulence k - {epsilon} equations is used to predict the two-phase parameters distribution in freon R12 boiling flow. The 3D module of the CATHARE code is used for numerical calculation. The DEBORA experiment has been chosen to evaluate our models. The radial profiles of the outlet parameters were measured by means of an optical probe. The comparison of the radial profiles of void fraction, liquid temperature, gas velocity and volumetric interfacial area at the end of the heated section shows that the multidimensional two-fluid model with proper constitutive relations can yield reasonably predicted results in boiling conditions. Sensitivity tests show that the turbulent dispersion force, which involves the void fraction gradient, plays an important role in determining the void fraction distribution; and the turbulence eddy viscosity is a significant factor to influence the liquid temperature distribution. (authors)

Yao, Wei; Morel, Christophe [CEA Grenoble, 17 rue des Martyrs, 38054 Grenoble Cedex 9 (France)

2002-07-01

405

The heat-pipe resembling action of boiling bubbles in endovenous laser ablation  

PubMed Central

Endovenous laser ablation (EVLA) produces boiling bubbles emerging from pores within the hot fiber tip and traveling over a distal length of about 20mm before condensing. This evaporation-condensation mechanism makes the vein act like a heat pipe, where very efficient heat transport maintains a constant temperature, the saturation temperature of 100C, over the volume where these non-condensing bubbles exist. During EVLA the above-mentioned observations indicate that a venous cylindrical volume with a length of about 20mm is kept at 100C. Pullback velocities of a few mm/s then cause at least the upper part of the treated vein wall to remain close to 100C for a time sufficient to cause irreversible injury. In conclusion, we propose that the mechanism of action of boiling bubbles during EVLA is an efficient heat-pipe resembling way of heating of the vein wall. PMID:20644976

van den Bos, Renate R.; van Ruijven, Peter W. M.; Nijsten, Tamar; Neumann, H. A. Martino; van Gemert, Martin J. C.

2010-01-01

406

Boiling Experiment Facility for Heat Transfer Studies in Microgravity  

NASA Technical Reports Server (NTRS)

Pool boiling in microgravity is an area of both scientific and practical interest. By conducting tests in microgravity, it is possible to assess the effect of buoyancy on the overall boiling process and assess the relative magnitude of effects with regards to other "forces" and phenomena such as Marangoni forces, liquid momentum forces, and microlayer evaporation. The Boiling eXperiment Facility is now being built for the Microgravity Science Glovebox that will use normal perfluorohexane as a test fluid to extend the range of test conditions to include longer test durations and less liquid subcooling. Two experiments, the Microheater Array Boiling Experiment and the Nucleate Pool Boiling eXperiment will use the Boiling eXperiment Facility. The objectives of these studies are to determine the differences in local boiling heat transfer mechanisms in microgravity and normal gravity from nucleate boiling, through critical heat flux and into the transition boiling regime and to examine the bubble nucleation, growth, departure and coalescence processes. Custom-designed heaters will be utilized to achieve these objectives.

Delombard, Richard; McQuillen, John; Chao, David

2008-01-01

407

Rayleigh-Brillouin light scattering study of saturated n-butane between room temperature and the critical point  

Microsoft Academic Search

In the present investigation, photon correlation spectroscopy in an extended form has been used for studying both the Rayleigh and Brillouin components of a dense fluid including their intensity ratio (Landau-Placzek ratio). As for the Brillouin component this amounts to spectroscopy in the ultrasonic region. Results for both phases of saturated n-butane in a broad temperature range are reported. They

G. Simonsohn; F. Wagner

1991-01-01

408

Latent Heat storage characteristics of solid-liquid phase change Heat Storage Microcapsule Slurry by Boiling Heat Transfer under a Vacuum Condition  

NASA Astrophysics Data System (ADS)

Recently, the new heat transfer medium, which fulfills both functions of heat storage and heat transportation, has been developed in ah eat storage field. Solid-liquid latent heat microcapsule slurry would correspond to the topical medium, so-called functionally thermal fluid. The preset study has clarified the latent heat storage characteristics of microcapsule slurry by making heat transfer enlargement with the help of slurry water pool boiling phenomenon. The paraffin wax at a melting point of 62C was used as a phase change material which was packed into the microcapsule. The heating surface temperature and concentration of paraffin in the microcapsule slurry was selected as experimental parameters. As a result, the non-dimensional correlation equations of heat storage completion time and heat transfer were derived in terms of non-dimensional parameters.

Inaba, Hideo; Horibe, Akihiko; Haruki, Naoto; Katayama, Masatoshi; Manabe, Ken

409

Bubble departure size in flow boiling  

NASA Astrophysics Data System (ADS)

Flow boiling experiments were conducted in a vertical annular channel to study bubble departure characteristics. Deionized water was used as the working fluid, and the tests were performed at atmospheric pressure. Bubble departure diameters were obtained from the images which were captured by a high-speed digital camera. The relationship between bubble contact diameter and departure diameter was discussed. A new model base on force balance analysis, taking bubble contact diameter into account for predicting bubble departure diameter is proposed in this study. A good agreement between predicted and measured results is achieved.

Guan, Peng; Jia, Li; Yin, Liaofei; Tan, Zetao

2014-12-01

410

Experimental method for characterizing CVOC removal from fractured clays during boiling  

NASA Astrophysics Data System (ADS)

Conventional remediation methods that rely on contact with contaminants can be ineffective in fractured media, but thermal methods of remediation involving CVOC stripping at boiling temperature show promise. However, limited experimental data are available to characterize thermal remediation because of challenges associated with high temperature. This research reports an experimental method using uniformly contaminated clay packed into two types of experimental cells, a rigid-wall stainless steel tube and a flexible-wall Teflon tube in a pressurized chamber. Both tubes are 5 cm in diameter and approximately 25 cm long. This laboratory apparatus was developed as a 1D physical model for contaminant transport in a cylindrical matrix towards a fracture, which is represented by one end of the cylinder and serves as the outlet of vapor and contaminant. The clay was contaminated with dissolved 1,2-dichloroethane (DCA) and bromide, and the columns were heated to more than 100 C and then the top end was depressurized to atmospheric pressure to induce boiling. The outflow was condensed and analyzed for contaminant mass. The flexible-wall cell was confined to 100 kPa (gage), allowing equilibrium boiling temperatures of approximately 120 C to be maintained. The clay was sampled before and after heating and extracted to determine the DCA distribution along the length of the column. During a typical test in the rigid-wall cell, internal temperatures and pressures along the column during heating reached the saturated vapor pressure curve. DCA concentrations in the recovered condensate were up to 12 times of the initial pore concentration in the clay. Less than 5% of non-volatile bromide was recovered. Significant removal of DCA and water occurred along the entire length of the clay column. This suggests that boiling was occurring in the clay matrix.

Liu, Xiaoling; Tan, Tianwu; Falta, Ronald W.; Murdoch, Lawrence C.

2013-09-01

411

Potential profile near singularity point in kinetic Tonks-Langmuir discharges as a function of the ion sources temperature  

SciTech Connect

A plasma-sheath transition analysis requires a reliable mathematical expression for the plasma potential profile {Phi}(x) near the sheath edge x{sub s} in the limit {epsilon}{identical_to}{lambda}{sub D}/l=0 (where {lambda}{sub D} is the Debye length and l is a proper characteristic length of the discharge). Such expressions have been explicitly calculated for the fluid model and the singular (cold ion source) kinetic model, where exact analytic solutions for plasma equation ({epsilon}=0) are known, but not for the regular (warm ion source) kinetic model, where no analytic solution of the plasma equation has ever been obtained. For the latter case, Riemann [J. Phys. D: Appl. Phys. 24, 493 (1991)] only predicted a general formula assuming relatively high ion-source temperatures, i.e., much higher than the plasma-sheath potential drop. Riemann's formula, however, according to him, never was confirmed in explicit solutions of particular models (e.g., that of Bissell and Johnson [Phys. Fluids 30, 779 (1987)] and Scheuer and Emmert [Phys. Fluids 31, 3645 (1988)]) since ''the accuracy of the classical solutions is not sufficient to analyze the sheath vicinity''[Riemann, in Proceedings of the 62nd Annual Gaseous Electronic Conference, APS Meeting Abstracts, Vol. 54 (APS, 2009)]. Therefore, for many years, there has been a need for explicit calculation that might confirm the Riemann's general formula regarding the potential profile at the sheath edge in the cases of regular very warm ion sources. Fortunately, now we are able to achieve a very high accuracy of results [see, e.g., Kos et al., Phys. Plasmas 16, 093503 (2009)]. We perform this task by using both the analytic and the numerical method with explicit Maxwellian and ''water-bag'' ion source velocity distributions. We find the potential profile near the plasma-sheath edge in the whole range of ion source temperatures of general interest to plasma physics, from zero to ''practical infinity.'' While within limits of ''very low'' and ''relatively high'' ion source temperatures, the potential is proportional to the space coordinate powered by rational numbers {alpha}=1/2 and {alpha}=2/3, with medium ion source temperatures. We found {alpha} between these values being a non-rational number strongly dependent on the ion source temperature. The range of the non-rational power-law turns out to be a very narrow one, at the expense of the extension of {alpha}=2/3 region towards unexpectedly low ion source temperatures.

Kos, L.; Tskhakaya, D. D.; Jelic, N. [LECAD Laboratory, Faculty of Mechanical Engineering, University of Ljubljana, SI-1000 Ljubljana (Slovenia); Association EURATOM-OeAW, Institute for Theoretical Physics, University of Innsbruck, A-6020 Innsbruck (Austria)

2011-05-15

412

Temperature  

NSDL National Science Digital Library

This topic in depth begins with the About Temperature (1) Web site, written by Beverly T. Lynds of Unidata, which is a program that works to enable university researchers and educators to acquire and use atmospheric and related data. The one-page site explains what temperature is, the development of thermometers, heat and thermodynamics, and other related topics. The second site is maintained by the University of Execter's Centre for Innovation in Mathematics Teaching. Actually an online tool called Conversion Calculator for Units of Temperature (2), the site allows users to type in any value, choose a significant figure, press "convert it," and get that value in Kelvin, Celsius, Fahrenheit, r'aumur, and rankine units. The next site is a lesson plan from AskEric.com entitled Temperature: Is it Hot or Cold? (3). Written for 2nd graders, the lesson demonstrates to how to read thermometers, determine their rise or fall, record temperatures, and take temperatures of various items. The fourth site, Surface Temperature Analysis (4), is presented by NASA's Goddard Institute for Space Studies. Here, visitors can view graphs, maps, animations, and station data of global surface temperatures. For example, the animation covers 12-month means from 1971 to 1999. The History Behind the Thermometer (5) Web site, from About.com, explores what a thermometer is, how it works, and how it came into being. The sixth site, entitled Science Shack (6) and offered by the BBC, answers the question, Why do we have two different temperature scales, Celsius and Fahrenheit? The site explains how to create your own thermometer like Galileo's, tells how it works, and why we use other types today. The next site is provided by National Oceanic and Atmospheric Administration (NOAA) and presents US State temperature extremes and drought information (7). Visitors can see all-time temperature maximums and minimums by state, monthly temperatures by state, and more. The last site is an all-inclusive temperature site called Temperature World (8). Everything from news, science, organizations, general interest, games, and more -- all related to temperature -- can be found here.

Brieske, Joel A.

2002-01-01

413

Reconstruction of historical pressure patterns over Japan using two-point pressuretemperature datasets since the nineteenth century  

Microsoft Academic Search

The temperature and pressure differences between Tokyo and Nagasaki were used to reconstruct past climate conditions. January\\u000a and July in each available year since the 1820s were classified into several types with characteristic sea level atmospheric\\u000a pressure patterns. This results in 18years of pre-1881 data and a continuous series thereafter. The series indicate that\\u000a the warming after 1900 (after the

Masumi Zaiki; Gunther P. Knnen; Keiji Kimura; Takehiko Mikami; Togo Tsukahara

2009-01-01

414

Effect of Temperature of CO2 Injection on the pH and Freezing Point of Milks and Creams1  

Microsoft Academic Search

The objectives of this study were to measure the im- pact of CO2 injection temperature (0C and 40C) on thepHandfreezingpoint(FP)of(a)milkswithdifferent fat contents (i.e., 0, 15, 30%) and (b) creams with 15% fat but different fat characteristics. Skim milk and un- homogenized creams containing 15 and 30% fat were prepared from the same batch of whole milk and were carbonated at

Y. Ma; D. M. Barbano

2003-01-01

415

Improving low temperature properties of synthetic diesel fuels derived from oil shale. Alternative fuels utilization program  

SciTech Connect

The ability of additives to improve the cold flow properties of shale oil derived fuels boiling in the diesel fuel range was evaluated. Because a commercial shale oil industry did not exist to provide actual samples of finished fuels, a representative range of hydroprocessed shale oil fractions was prepared for use in the additive testing work. Crude oil shale from Occidental Shale Company was fractionated to give three liquids in the diesel fuel boiling range. The initial boiling point in each case was 325/sup 0/F (163/sup 0/C). The final boiling points were 640/sup 0/F (338/sup 0/C), 670/sup 0/F (354/sup 0/C) and 700/sup 0/F (371/sup 0/F). Each fraction was hydrotreated to three different severities (800, 1200 and 1500 psi total pressure) over a Shell 324 nickel molybdate on alumina catalyst at 710 to 750/sup 0/F to afford 9 different model fuels. A variety of commercial and experimental additives were evaluated as cold flow improvers in the model fuels at treat levels of 0.04 to 0.4 wt %. Both the standard pour point test (ASTM D97) and a more severe low temperature flow test (LTFT) were employed. Reductions in pour points of up to 70/sup 0/F and improvements in LTFT temperatures up to 16/sup 0/F were achieved. It is concluded that flow improver additives can play an important role in improving the cold flow properties of future synthetic fuels of the diesel type derived from oil shale.

Frankenfeld, J.W.; Taylor, W.F.

1980-11-01

416

Effect of nanopatterns on Kapitza resistance at a water-gold interface during boiling: A molecular dynamics study  

NASA Astrophysics Data System (ADS)

The effect of nanopatterns on Kapitza resistance of water boiling on a gold surface is examined via molecular dynamics simulations. The TIP4P-Ew potential for water, embedded-atom model for gold, and the calibrated Lennard-Jones parameters for water-gold interactions are used to accurately predict the boiling point of water and the wetting angle of water on gold. The results show that boiling of water does not affect the Kapitza resistance of the water-gold interface. The increase of the height of nanopatterns leads to a reduction of the Kapitza resistance by increasing the interaction energy per unit area at the water-gold interface. With the increase of the width-to-spacing ratio of nanopatterns, the Kapitza resistance reduces due to the decrease of the mismatch between the vibrational density of states of water and gold.

Hu, Han; Sun, Ying

2012-09-01

417

Wiedemann-Franz law and nonvanishing temperature scale across the field-tuned quantum critical point of YbRh2Si2  

NASA Astrophysics Data System (ADS)

The in-plane thermal conductivity ? and electrical resistivity ? of the heavy-fermion metal YbRh2Si2 were measured down to 50 mK for magnetic fields H parallel and perpendicular to the tetragonal c axis, through the field-tuned quantum critical point Hc, at which antiferromagnetic order ends. The thermal and electrical resistivities, w ?L0T/? and ?, show a linear temperature dependence below 1 K, typical of the non-Fermi-liquid behavior found near antiferromagnetic quantum critical points, but this dependence does not persist down to T =0. Below a characteristic temperature T?0.35 K, which depends weakly on H, w (T) and ? (T) both deviate downward and converge as T ?0. We propose that T marks the onset of short-range magnetic correlations, persisting beyond Hc. By comparing samples of different purity, we conclude that the Wiedemann-Franz law holds in YbRh2Si2, even at Hc, implying that no fundamental breakdown of quasiparticle behavior occurs in this material. The overall phenomenology of heat and charge transport in YbRh2Si2 is similar to that observed in the heavy-fermion metal CeCoIn5, near its own field-tuned quantum critical point.

Reid, J.-Ph.; Tanatar, M. A.; Daou, R.; Hu, Rongwei; Petrovic, C.; Taillefer, Louis

2014-01-01

418

Wiedemann-Franz law and nonvanishing temperature scale across the field-tuned quantum critical point of YbRh2Si2  

SciTech Connect

The in-plane thermal conductivity kappa and electrical resistivity rho of the heavy-fermion metal YbRh2Si2 were measured down to 50 mK for magnetic fields H parallel and perpendicular to the tetragonal c axis, through the field-tuned quantum critical point H-c, at which antiferromagnetic order ends. The thermal and electrical resistivities, w L0T/kappa and rho, show a linear temperature dependence below 1 K, typical of the non-Fermi-liquid behavior found near antiferromagnetic quantum critical points, but this dependence does not persist down to T = 0. Below a characteristic temperature T-star similar or equal to 0.35 K, which depends weakly on H, w(T) and rho(T) both deviate downward and converge as T -> 0. We propose that T-star marks the onset of short-range magnetic correlations, persisting beyond H-c. By comparing samples of different purity, we conclude that the Wiedemann-Franz law holds in YbRh2Si2, even at H-c, implying that no fundamental breakdown of quasiparticle behavior occurs in this material. The overall phenomenology of heat and charge transport in YbRh2Si2 is similar to that observed in the heavy-fermion metal CeCoIn5, near its own field-tuned quantum critical point.

Reid, J.-Ph. [Universite de Sherbrooke; Tanatar, Makariy [Ames Laboratory; Daou, R. [Universite de Sherbrooke; Hu, Rongwei [Brookhaven National Laboratory; Petrovic, C. [Brookhaven National Laboratory; Taillefer, Louis [Brookhaven National Laboratory

2014-01-23

419

Magnetic behavior of an amorphous ferromagnet for temperatures close to, and above, the Curie point: Structural relaxation effects  

NASA Astrophysics Data System (ADS)

Detailed bulk magnetization (ac susceptibility) measurements on the amorphous Fe16Ni64B19Si alloy have been performed in the temperature region 0.95TC-1.5TC (0.95TC<=T<=1.05TC) before and after it had undergone isothermal annealing at 400 K for 60 and 120 min. An elaborate analysis of the data so obtained, besides yielding accurate values for the asymptotic and leading ``correction-to-scaling'' (CTS) critical exponents and amplitudes, reveals that the structural relaxation consequent upon isothermal annealing does not have any influence on the asymptotic and CTS critical exponents and on the universal amplitude ratios m0/Ms(0) and Dm?0/h0, whose values are close to those theoretically predicted for a three-dimensional Heisenberg ferromagnet, but has profound effect on the ratio ?0h0/kBTC and the Curie temperature, TC. The fraction of spins actually involved in the transition at TC is small and reduces slowly with increasing annealing time. Consistent with the theoretical expectations, nonanalytic corrections (originating from the nonlinear irrelevant scaling fields) to the singular behavior at TC dominate over the analytic ones (arising on account of the nonlinear relevant scaling fields) in the critical region but the reverse is true for T>>TC. Regardless of whether the sample is annealed or not, the initial susceptibility follows the generalized Curie-Weiss law for as wide a temperature range as TC<=T<=1.5TC. The present results provide a strong evidence for weak itinerant ferromagnetism in the glassy alloy in question.

Kaul, S. N.; Mohan, Ch. V.

1994-09-01

420

Boiling Fluids Behave Quite Differently in Space - Duration: 0:19.  

NASA Video Gallery

The boiling process is really different in space, since the vapor phase of a boiling liquid does not rise via buoyancy. Spacecraft and Earth-based systems use boiling to efficiently remove large am...

421

A Portable, Pressure Driven, Room Temperature Nucleic Acid Extraction and Storage System for Point of Care Molecular Diagnostics  

PubMed Central

Many new and exciting portable HIV viral load testing technologies are emerging for use in global medicine. While the potential to provide fast, isothermal, and quantitative molecular diagnostic information to clinicians in the field will soon be a reality, many of these technologies lack a robust front end for sample clean up and nucleic acid preparation. Such a technology would enable many different downstream molecular assays. Here, we present a portable system for centrifuge-free room temperature nucleic acid extraction from small volumes of whole blood (70 L), using only thermally stable reagents compatible with storage and transport in low resource settings. Quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) analysis of simulated samples demonstrate a lower limit of detection of 1000 copies/ml, with the ability to detect differences in viral load across four orders of magnitude. The system can also be used to store extracted RNA on detachable cartridges for up to one week at ambient temperature, and can be operated using only hand generated air pressure. PMID:23914255

Byrnes, Samantha; Fan, Andy; Trueb, Jacob; Jareczek, Francis; Mazzochette, Mark; Sharon, Andre; Sauer-Budge, Alexis F.; Klapperich, Catherine M.

2013-01-01

422

Explosive Boiling at Very Low Heat Fluxes: A Microgravity Phenomenon  

NASA Technical Reports Server (NTRS)

The paper presents experimental observations of explosive boiling from a large (relative to bubble sizes) flat heating surface at very low heat fluxes in microgravity. The explosive boiling is characterized as either a rapid growth of vapor mass over the entire heating surface due to the flashing of superheated liquid or a violent boiling spread following the appearance of single bubbles on the heating surface. Pool boiling data with saturated Freon 113 was obtained in the microgravity environment of the space shuttle. The unique features of the experimental results are the sustainability of high liquid superheat for long periods and the occurrence of explosive boiling at low heat fluxes (0.2 to 1.2 kW/sq m). For a heat flux of 1.0 kW/sq m a wall superheat of 17.9 degrees C was attained in ten minutes of heating. This was followed by an explosive boiling accompanied with a pressure spike and a violent bulk liquid motion. However, at this heat flux the vapor blanketing the heating surface could not be sustained. Stable nucleate boiling continued following the explosive boiling.

Hasan, M. M.; Lin, C. S.; Knoll, R. H.; Bentz, M. D.

1993-01-01

423

Boiling treatment of ABS and PS plastics for flotation separation.  

PubMed

A new physical method, namely boiling treatment, was developed to aid flotation separation of acrylonitrile-butadiene-styrene (ABS) and polystyrene (PS) plastics. Boiling treatment was shown to be effective in producing a hydrophilic surface on ABS plastic. Fourier Transform Infrared analysis was conducted to investigate the mechanism of boiling treatment of ABS. Surface rearrangement of polymer may be responsible for surface change of boiling treated ABS, and the selective influence of boiling treatment on the floatability of boiling treated plastics may be attributed to the difference in the molecular mobility of polymer chains. The effects of flotation time, frother concentration and particle size on flotation behavior of simple plastic were investigated. Based on flotation behavior of simple plastic, flotation separation of boiling treatment ABS and PS with different particle sizes was achieved efficiently. The purity of ABS and PS was up to 99.78% and 95.80%, respectively; the recovery of ABS and PS was up to 95.81% and 99.82%, respectively. Boiling treatment promotes the industrial application of plastics flotation and facilitates plastic recycling. PMID:24602834

Wang, Chong-qing; Wang, Hui; Wu, Bao-xin; Liu, Qun

2014-07-01

424

Heat Transfer Mechanisms During Flow Boiling in Microchannels  

Microsoft Academic Search

The forces due to surface tension, inertia, and momentum change during evaporation in microchannel govern the two- phase flow patterns and the heat transfer characteristics during flow boiling. These forces are analyzed in this paper, and two new non-dimensional groups, K1 and K 2, relevant to flow boiling phenomenon are derived. These groups are able to represent some of the

Satish G. Kandlikar

2004-01-01

425

Modeling acid-gas generation from boiling chloride brines  

Microsoft Academic Search

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

Guoxiang Zhang; Nicolas Spycher; Eric Sonnenthal; Carl Steefel

2009-01-01

426

Boiling heat transfer and bubble dynamics in microgravity  

Microsoft Academic Search

This article presents results for pool boiling heat transfer under microgravity conditions that the author and his team have gained in a succession of experiments during the past two decades. The objective of the research work was to provide answers to the following questions: Is boiling an appropriate mechanism of heat transfer for space application? How do heat transfer and

Johannes Straub

2001-01-01

427

Investigations of Mechanisms Associated with Nucleate Boiling Under Microgravity Conditions  

Microsoft Academic Search

In this work a building block type of approach is used so that a basic understanding of the processes that contribute to nucleate boiling heat fluxes under microgravity conditions can be developed. This understanding will lead to development of a mechanistic model for nucleate boiling heat transfer which could eventually be used as a design tool in space applications. Task

Vijay K. Dhir; M. Hasan

2003-01-01

428

Experimental study of onset of subcooled annular flow boiling  

Microsoft Academic Search

An experimental study on the onset of nucleate boiling (ONB) is performed for water annular flow to provide a systematic database for low pressure and velocity conditions. A parametric study has been conducted to investigate the effect of pressure, inlet subcooling, heat and mass flux on flow boiling. The test section includes a Pyrex tube with 21mm inner diameter and

R. Ahmadi; A. Nouri-Borujerdi; J. Jafari; I. Tabatabaei

2009-01-01

429

Bubble dynamics in boiling under high heat flux pulse heating  

Microsoft Academic Search

A new theoretical model of bubble behavior in boiling water under high heat flux pulse is presented. The essence of the model is nucleation in the superheated liquid followed by instantaneous formation of a vapor film, rapid bubble growth due to the pressure impulse, and cavitation bubble collapse. To check the model, boiling of methanol under 5 50 MW

A. Asai

1991-01-01

430

Effect of acoustic cavitation on boiling heat transfer  

Microsoft Academic Search

Boiling heat transfer on a horizontal circular copper tube in an acoustical field is investigated experimentally and the relation between the liquid cavitation, the boiling and the micro bubble radii are analyzed theoretically. The results show that cavitation bubbles have an important influence on the nucleation, growth and collapse of vapor embryo within cavities on the heat transfer surface and

D. W. Zhou; D. Y. Liu; X. G. Hu; C. F. Ma

2002-01-01

431

Scaling Theory of the Mott Transition and Breakdown of the Gr"uneisen Scaling Near a Finite-Temperature Critical End Point  

NASA Astrophysics Data System (ADS)

We discuss a scaling theory of the lattice response in the vicinity of a finite-temperature critical end point. The thermal expansivity is shown to be more singular than the specific heat such that the Gr"uneisen ratio diverges as the critical point is approached, except for its immediate vicinity. More generally, we express the thermal expansivity in terms of a scaling function which we explicitly evaluate for the two-dimensional Ising universality class. Recent thermal expansivity measurements on the layered organic conductor ?-(BEDT-TTF)2X close to the Mott transition are well described by our theory.[2mm] [1] Lorenz Bartosch, Mariano de Souza, and Michael Lang, Physical Review Letters 104, 245701 (2010).

Bartosch, Lorenz

2012-02-01

432

Correlation of point defects in CdZnTe with charge transport:application to room-temperature x-ray and gamma-ray. Final Technical Report  

SciTech Connect

The primary goal of this project has been to characterize and identify point defects (e.g., impurities, vacancies, vacancy-impurity complexes, etc.) in CdZnTe and determine the mechanisms by which these defects influence the carrier {mu}{tau}products. Special attention is given to the role of shallow donors, shallow acceptors, and deeper acceptors. There are two experimental focus areas in the project: (1) liquid-helium photoluminescence (PL) and PL excitation spectroscopy are used to identify and characterize donors and acceptors and to determine zinc molar fraction; and (2) electron paramagnetic resonance (EPR) and photoinduced EPR experiments are performed at liquid-helium temperature to identify paramagnetic point defects and to determine the concentration of these defects. Results from the two experimental focus areas are correlated with detector performance parameters (e.g., electron and hole {mu}{tau} products), crystal growth conditions, and microstructure analyses.

Giles, Nancy C.

2003-06-25

433

Experimental study on boiling heat transfer and two-phase frictional pressure drop characteristics of glycol-water solution in a vertical porous surface tube  

NASA Astrophysics Data System (ADS)

Although much research has been conducted on investigating the flow boiling heat transfer of low saturation temperature refrigerants, there are few experimental data and theory about the flow boiling heat transfer of high saturation temperature organic mixture which exists widely in the petrochemical industry. To investigate the characteristics of flow boiling heat transfer of high saturation temperature organic mixture, experiments of glycol-water solution flow boiling in a vertical porous surface tube and a vertical smooth tube are conducted. Test tubes are uniformly heated by electrical current with a heated length of 2,000 mm. The mass flux in the experiment ranges from 500 to 1,500t?h-1 and the heat flux on test tubes ranges from 10 to 40 kW?m-2. The flow boiling heat transfer coefficients and two-phase frictional pressure drops of the two types of tubes are obtained and compared. The results indicate that: the flow boiling heat transfer coefficient in the porous surface tube is 3.85.7 times of that in smooth tube and the pressure drop of the porous surface tube is 0.991.007 times of that in the smooth tube. The physical mechanisms of the enhanced heat transfer characteristics of flow boiling in the porous surface tube are analyzed. By the regression analysis of the experimental data, correlations predicting the flow boiling heat transfer coefficient and pressure drop of glycol-water solution within the error range of 20% are established. The experimental results can be used to guide the design of heat exchange equipment using the porous surface tube as heat transfer elements under these test conditions.

Qiao, Shouxu; Wang, Haijun; Gu, Hongfang; Luo, Yushan; Zhang, Lei; Xiong, Wei

2013-07-01

434

Conversion of direct process high-boiling residue to monosilanes  

DOEpatents

A process for the production of monosilanes from the high-boiling residue resulting from the reaction of hydrogen chloride with silicon metalloid in a process typically referred to as the "direct process." The process comprises contacting a high-boiling residue resulting from the reaction of hydrogen chloride and silicon metalloid, with hydrogen gas in the presence of a catalytic amount of aluminum trichloride effective in promoting conversion of the high-boiling residue to monosilanes. The present process results in conversion of the high-boiling residue to monosilanes. At least a portion of the aluminum trichloride catalyst required for conduct of the process may be formed in situ during conduct of the direct process and isolation of the high-boiling residue.

Brinson, Jonathan Ashley (Vale of Glamorgan, GB); Crum, Bruce Robert (Madison, IN); Jarvis, Jr., Robert Frank (Midland, MI)

2000-01-01

435

Boiling jet impingement cooling of simulated microelectronic chips  

NASA Astrophysics Data System (ADS)

Jet impingement cooling is a possible means of accommodating the high heat fluxes which result from testing miroelectronic chips at power levels well above those expected during normal operation. An apparatus is described for study of the heat transfer characteristics of chip-size electrically heated test sections with normally impinging circular submerged mets of saturated or subcooled R-113. Data were obtained for several jet velocities, with the jet directed at two positions on the heated surface. Free convection boiling data were taken for reference. The boiling curve hysteresis with jet boiling is less than with free convection. The fully developed saturated jet boiling data merge into an asymptote that coincides closely with the extrapolation of the pool boiling curve. The burnout heat flux is proportional to the cube root of jet velocity. Heat fluxes up to a million W/sq m were recorded.

Bergles, E.; Ma, C.-F.

436

Influence of working fluid evaporation temperature in the near-critical point region on the effectiveness of ORC power plant operation  

NASA Astrophysics Data System (ADS)

In the paper presented are definitions of specific indicators of power which characterize the operation of the organic Rankine cycle (ORC) plant. These quantities have been presented as function of evaporation temperature for selected working fluids of ORC installation. In the paper presented also is the procedure for selection of working fluid with the view of obtaining maximum power. In the procedure of selection of working fluid the mentioned above indicators are of primary importance. In order to obtain maximum power there ought to be selected such working fluids which evaporate close to critical conditions. The value of this indicator increases when evaporation enthalpy decreases and it is known that the latent heat of evaporation decreases with temperature and reaches a value of zero at the critical point.

Nowak, W?adys?aw; Borsukiewicz-Gozdur, Aleksandra; Wi?niewski, S?awomir

2012-09-01

437

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 densities. Indeed, microchannels are already attrac- tive in many domains such as: electronics cooling removal, and they have large heat dissipa- tion capabilities. Moreover, microchannels can be used

438

Environmental factors influencing stress corrosion cracking in boiling water reactors  

SciTech Connect

The mechanisms of intergranular stress corrosion cracking (IGSCC) of sensitized stainless steels in boiling water reactor (BWR) primary coolant are reviewed, with emphasis on the role the environment plays on both the initiation and propagation processes. Environmental factors discussed include oxygen (corrosion potential), temperature, and dissolved ions in the water and the range of strain rates at which IGSCC occurs. Both crack propagation rates and the range of strain rates at which IGSCC occurs decrease rapidly as temperature is increased above approximately 200/sup 0/C, in essentially the same manner as the solubility of magnetite decreases in acidic solutions. A mechanism of crack propagation is presented base on this observation. To establish water chemistry guidelines for crack-free operation of BWR's containing sensitized stainless steel, more information is needed on the role of absorption of impurities in the surface and deposited oxides and on the interaction between the oxygen and impurity levels required to maintain an electrochemical potential in a range where IGSCC is unlikely to occur. The relative effects of short bursts of impurities and longer term lower concentrations of these same impurities also need to be evaluated.

Weeks, J.R.

1984-01-01

439

Flow boiling of a new low-GWP refrigerant inside a single square cross section microchannel  

NASA Astrophysics Data System (ADS)

In this work new experimental heat transfer coefficients measured during flow boiling of HFO-1234ze(E) in a horizontally-assembled square cross section microchannel having an hydraulic diameter of 1.23 mm are presented. The test runs have been performed at around 30C saturation temperature, correspondent to 5.8 bar, with mass flux ranging between 300 kg m?2 s?1 and 500 kg m?2 s?1. As a peculiar characteristic of the present technique, the heat transfer coefficient is not measured by imposing the heat flux; instead, the boiling process is governed by controlling the inlet temperature of the heating secondary fluid. On this regard the present data is new and original since the large majority of data in the literature is taken by means of Joule effect heating. The heat transfer coefficients are compared against two predicting models available in the literature. Finally, the local heat transfer coefficients measured during flow boiling of R1234ze(E) inside the square cross section microchannel are compared against the values measured with the same refrigerant in a 0.96 mm diameter circular microchannel, with same surface roughness, with the aim of investigating the effect of channel shape on the heat transfer process.

Bortolin, S.; Del, D., Col

2014-11-01

440

Two-Dimensional Numerical Simulation of Boiling Two-Phase Flow of Liquid Nitrogen  

NASA Astrophysics Data System (ADS)

Two-dimensional characteristics of the boiling two-phase flow of liquid nitrogen in a duct flow are numerically investigated to contribute to the further development of new high-performance cryogenic engineering applications. First, the governing equations of the boiling two-phase flow of liquid nitrogen based on the unsteady drift-flux model are presented and several flow characteristics are numerically calculated taking account the effect of cryogenic flow states. Based on the numerical results, a two-dimensional structure of the boiling two-phase flow of liquid nitrogen is shown in detail, and it is found that the phase change of liquid nitrogen occurs in quite a short time interval compared with that of two-phase pressurized water at high temperature. Next, it is clarified that the distributions of pressure and the void fraction in a two-phase flow show a tendency different from those of fluids at room temperature because of the decrease in sound velocity due to large compressibility and the rapid phase change velocity in a cryogenic two-phase mixture flow. According to these numerical results, the fundamental characteristics of the cryogenic two-phase flow are predicted. The numerical results obtained will contribute to advanced cryogenic industrial applications.

Ishimoto, Jun; Oike, Mamoru; Kamijo, Kenjiro

441

Experiment and RELAP5 Analysis for the Downcomer Boiling of APR1400 under LBLOCA  

SciTech Connect

The direct vessel injection (DVI) mode of a safety injection system is adopted instead of a conventional cold leg injection (CLI) mode as one of the advanced design features of the APR1400 (Advanced Power Reactor 1400 MW). From the calculation results of RELAP5 with full plant, it is found out that the sudden boiling happens in the downcomer due to heat transfer from the reactor vessel wall and it can affect the reactor safety. In the present study, experimental tests are carried out to observe the actual boiling phenomena in the downcomer and to validate RELAP5. The heated wall of test section has its thickness of 8.2 cm and the same material as the prototype (APR1400) with chrome coating against rusting. From the experiment, we visually observe the vapor jetting near the heated wall with small bubble migration to the bulk region and liquid circulation. The data shows a rapid wall temperature drop generating a large amount of vapor initially. The calculation results of RELAP5 using the three nodal schemes are compared with experimental ones in aspects of water level, void fraction, wall temperatures and phase velocities. It turns out that the double nodal scheme with circulation produces better results than the nodal scheme without circulation to simulate the boiling phenomena in the downcomer. (authors)

Dong Won Lee; Hee Cheon No; Eu Hwak Lee [Korea Advanced Institute of Science and Technology, Gusong-Dong, Yusong-Gu 373-1, Daejon (Korea, Republic of); Seung Jong Oh [Korea Hydraulic and Nuclear Power Co., 103-16, Munji-dong, Yuseong-gu, Daejeon, 305-380 (Korea, Republic of); Chul-Hwa Song [Korea Atomic Energy Research Institute, Yuseong-gu P.O. Box 105, Daejeon, 305-600 (Korea, Republic of)

2004-07-01

442

High level disinfection of a home care device; to boil or not to boil?  

PubMed

We developed a percutaneous electrical transducer for home therapy of chronic pain, a device that requires high level disinfection between uses. The utility of boiling water to provide high level disinfection was evaluated by inoculating transducer pads with potential skin pathogens (Staphylococcus aureus, Mycobacterium terrae, Pseudomonas aeruginosa, Candida albicans) and subjecting them to full immersion in water boiling at 4200 feet elevation (95 C). Log10 reductions in colony-forming units (cfu) at 10 min were 7.1, >6.3 and >5.5 for S. aureus, P. aeruginosa and C. albicans, respectively, but only 4.6 for M. terrae. At 15 min the reductions had increased to 7.5, >6.8, >6.6 and >7.5 cfu, respectively. PMID:22277192

Winthrop, K L; Homestead, N

2012-03-01

443

Permeation of water through the polymeric components of boil-in-bag laminates.  

PubMed

Diffusion coefficients and equilibrium uptake have been measured for water and 3% acetic acid in film of PETP, lldpe, nylon 6 and nylon 66, and also in some isocyanate adhesives. These materials are used in the construction of boil-in-bags for food. The three methods of measurement used were permeation from a bag, mass uptake, and the use of a novel technique using isotopically labelled water. The principal temperature of investigation has been 100 degrees C. Differences in the permeation parameters for water and 3% acetic acid were small for PETP, but surprisingly large for an inert material such as lldpe. With the nylons differences could readily be ascribed to the fact that these materials are bases. When immersed in boiling water there was no change in the degree of crystallinity of PETP, but lldpe and nylon 66 showed small increases. PMID:2379652

Comyn, J; Cope, B C; Werrett, M R

1990-01-01

444

Zero Boil-Off System Design and Thermal Analysis of the Bimodal Thermal Nuclear Rocket  

SciTech Connect

Mars exploration studies at NASA are evaluating vehicles that incorporate Bimodal Nuclear Thermal Rocket (BNTR) propulsion which use a high temperature nuclear fission reactor and hydrogen to produce thermal propulsion. The hydrogen propellant is to be stored in liquid state for periods up to 18 months. To prevent boil-off of the liquid hydrogen, a system of passive and active components are needed to prevent heat from entering the tanks and to remove any heat that does. This report describes the design of the system components used for the BNTR Crew Transfer Vehicle and the thermal analysis performed. The results show that Zero Boil-Off (ZBO) can be achieved with the electrical power allocated for the ZBO system.

Christie, Robert J. [ZinTechnologies, 2001 Aerospace Parkway, Brook Park, OH 44142 (United States); Plachta, David W. [NASA Glenn Research Center, 21000 Brookpark Road, Cleveland, OH 44135 (United States)

2006-01-20

445

Hybrid modelling of a sugar boiling process  

E-print Network

The first and maybe the most important step in designing a model-based predictive controller is to develop a model that is as accurate as possible and that is valid under a wide range of operating conditions. The sugar boiling process is a strongly nonlinear and nonstationary process. The main process nonlinearities are represented by the crystal growth rate. This paper addresses the development of the crystal growth rate model according to two approaches. The first approach is classical and consists of determining the parameters of the empirical expressions of the growth rate through the use of a nonlinear programming optimization technique. The second is a novel modeling strategy that combines an artificial neural network (ANN) as an approximator of the growth rate with prior knowledge represented by the mass balance of sucrose crystals. The first results show that the first type of model performs local fitting while the second offers a greater flexibility. The two models were developed with industrial data...

Lauret, Alfred Jean Philippe; Gatina, Jean Claude

2012-01-01

446

Dense distributed temperature sensing to infer local seepage fluxes in coastal areas  

NASA Astrophysics Data System (ADS)

In many deltas, land surfaces are largely below sea level, and consequently suffering from saline groundwater seepage. This phenomenon affects the fresh water supply for, for example, agriculture and drinking water production. In many of those deltas, sea level rise and land subsidence enhance these problems. Depending on the geology, the seepage fluxes can occur both distributed and locally. Local seepage occurs through ancient channels that were filled with higher-conductive material at later times, but also works its way up via small vents through the soil. The latter is called boil seepage and usually is the most saline of the mentioned seepage types. Boils commonly appear in ditches and canals, since the pressure gradient is most of the time larger compared to the surrounding area. Although boils appear only as local point inflows, their high discharge and consequent salt flux can make them contribute for over 70% of the salt flux into lowland water systems (de Louw et al., 2010). Seepage measurement methods include the application of so-called seepage meters and tracers like temperature. Conventional methods using temperature differences between groundwater and surface water require drilling temperature sensors into the soil. Because the locations of boils are sensitive to disturbances of the soil, we measure the seepage flux by measuring a 3D temperature profile in the surface water above the boil instead. The seepage flux is inferred from a numerical surface water model that includes salt and temperature transport. Laboratory and field results show the onset of stratification because of the denser groundwater. In the winter situation, the <