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1

Critical temperatures of elements from their boiling points  

Microsoft Academic Search

A linear relation between critical temperature and boiling point is proposed for elements belonging to the same group in the periodic table. The validity of the relationship is demonstrated for the alkalies and the groups 16, 17 and 18. From this the critical temperature of tellurium is predicted as 2325?K and that for polonium as 2277?K.

Y. P. Varshni

2007-01-01

2

International Boiling Point Project  

NSDL National Science Digital Library

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

2009-01-01

3

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

NSDL National Science Digital Library

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

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

2001-01-01

4

Boiling Time and Temperature  

NSDL National Science Digital Library

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

Eberle, Francis; Tugel, Joyce; Keeley, Page

2007-01-01

5

Computer Procedures for Converting Distillation Temperatures Measured at Reduced Pressures to Normal Boiling Points for Undefined Hydrocarbon Mixtures.  

National Technical Information Service (NTIS)

Computer codes were devised for converting distillation temperatures measured at subatmospheric pressures to normal boiling points for undefined hydrocarbon mixtures based on the Maxwell-Bonnell correlation. The computer codes provide a solution for compu...

M. L. Weiss

1981-01-01

6

The International Boiling Point Project  

NSDL National Science Digital Library

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

7

Trends in Alkane Boiling Points  

NSDL National Science Digital Library

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

Woods, Paula

8

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

PubMed

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 T(g) is covered. We focus on low-T(g) 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" E(coop)(T) depending exponentially on temperature [Schmidtke et al., Phys. Rev. E 86, 041507 (2012)]. 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 E(coop)(T)/E? vs. T/E? plot and suggests that E? controls the energy scale of the glass transition phenomenon. PMID:24007015

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

2013-08-28

9

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

ERIC Educational Resources Information Center

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

Struyf, Jef

2011-01-01

10

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

Microsoft Academic Search

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

Antti Hukka

1996-01-01

11

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

E-print Network

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

Pimenova, Anastasiya V

2014-01-01

12

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

E-print Network

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

Anastasiya V. Pimenova; Denis S. Goldobin

2014-07-17

13

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

E-print Network

The phenomenon of the glass transition is an unresolved problem of condensed matter physics. Its prominent feature, the super-Arrhenius temperature dependence of the transport coefficients remains a challenge to be described over the full temperature range. For a series of molecular glass formers, we combined tau(T) from dielectric spectroscopy and dynamic light scattering covering the range 10_-12 s temperature regime characterized by an Arrhenius law with a constant activation energy E_inf and a low-temperature regime for which E_coop(T):= E(T) - E_inf increases while cooling. A two-parameter scaling is introduced, specifically E_coop(T)/E_inf = f[lambda(T/T_A -1)], where f is an exponential function, lambda a dimensionless parameter, and T_A a reference temperature proportional to E_inf. In order to describe tau(T), in addition, the attempt time tau_inf has to be specified. Thus, a single interaction parameter E_inf extracted from the high-temperature regime together with lambda controls the temperature dependence of low-temperature cooperative dynamics.

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

2012-04-27

14

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

PubMed

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

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

2012-10-01

15

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

SciTech Connect

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

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

1998-01-01

16

Uniform temperature, ultrahigh flux heat sinks using curved surface subcooled nucleate boiling  

Microsoft Academic Search

A novel type of heat exchange process is described for use in semiconductor heat sinks. It involves the use of subcooled, nucleate boiling at concave curved surfaces where radial acceleration can be used to develop significant and beneficial buoyancy forces. This system provides a heat transfer surface with a uniform temperature, i.e. the boiling point of the fluid, and requires

Arthur H. Iversen; Stephen Whitaker

1989-01-01

17

Life above the boiling point of water?  

Microsoft Academic Search

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

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

1986-01-01

18

Boiling points of the superheavy elements 117 and 118  

Microsoft Academic Search

It has been shown that the relativistic effect on the electrons reveal in the heavy element region.1–3 What kind of changes will appear in the heavy elements because of the relativistic effects? Can we observe the changes? We observed that the boiling points of astatine and radon are lower than that extrapolated values from lighter elements in the same groups.4,5

N. Takahashi

2002-01-01

19

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

20

THE FREEZING POINT DEPRESSION OF MAMMALIAN TISSUES AFTER SUDDEN HEATING IN BOILING DISTILLED WATER  

Microsoft Academic Search

The calculated freezing point depression of freshly excised boiled mammalian tissue is approximately the same as that of plasma. The boiling procedure was chosen to eliminate the influence of metabolism on the level of the freezing point depression. Problems created by the boiling, such as equilibrium between tissue and diluent, change in activity coefficient by dilution, and loss of CO~

J. W. Th. Appelboom; WILLIAM A. BRODSK; WILLIAM S. TUTTLE; ISRAEL DIAMOND

1958-01-01

21

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

22

Boiling at the boundary of two immiscible liquids below the bulk boiling temperature of each component  

NASA Astrophysics Data System (ADS)

The problem of vapor formation in the system of two immiscible liquids is considered at the temperatures that are lower than the bulk boiling temperature of each component and higher than the temperature at which the sum of the saturated vapor pressures of the components is equal to atmospheric pressure. In this situation, boiling occurs at the surface of direct contact between the two components. The kinetics of the vapor layer at the contact boundary is theoretically described, and a solution is obtained for the idealized case where the properties of the two liquids are close to each other. The relation between the solution for the vapor layer kinetics and the integral boiling characteristics of the system is considered, and the problem of cooling the system in the absence of a heat inflow is solved.

Pimenova, A. V.; Goldobin, D. S.

2014-07-01

23

MELTING POINT: 3,127C BOILING POINT: 5,303C  

E-print Network

208 Osmium MELTING POINT: 3,127°C BOILING POINT: 5,303°C DENSITY: 22.590 g/cm 3 MOST COMMON IONS: OsCl6 3­ , OsCl6 2­ The element osmium was discovered in 1804 by English chemist Smithson Tennant, and only four osmium-containing minerals, all extr emely rare, are known: erlich- manite, OsS2; omeiite

Girolami, Gregory S.

24

Design of Ultrasonically-Activatable Nanoparticles using Low Boiling Point Perfluorocarbons  

PubMed Central

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

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

2012-01-01

25

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

ERIC Educational Resources Information Center

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

Murphy, Peter M.

2007-01-01

26

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

E-print Network

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

Chickos, James S.

27

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

NSDL National Science Digital Library

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

28

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

PubMed

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

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

2012-08-21

29

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

30

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

SciTech Connect

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

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

2013-11-02

31

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

Microsoft Academic Search

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

Franklin D. Moore; Russell B. Mesler

1961-01-01

32

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

33

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

34

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

35

Influence of Fluid Concentration on the Elevation of Boiling Point of Blackberry Juice  

Microsoft Academic Search

The rise in boiling point of blackberry juice was experimentally measured at soluble solids concentrations in the range of 9.4 to 58.4°Brix and pressures between 4.9?×?10 and 9.0?×?10 Pa (abs.). Different approaches to representing experimental data, including the Dühring's rule, a model similar to Antoine equation and other empirical models proposed in the literature were tested. In the range of

A. L. Gabas; P. J. A. Sobral; C. A. Cardona-Alzate; V. R. N. Telis; J. Telis-Romero

2008-01-01

36

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

E-print Network

Experimental investigation of micro-scale temperature transients in sub-cooled flow boiling: Flow boiling Thin film thermocouple Microfabrication Nanofabrication Fast Fourier transform a b s t r a c t Surface temperature fluctuations that occur locally underneath departing bubbles in pool boiling

Banerjee, Debjyoti

37

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

SciTech Connect

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

Ohtake, Hiroyasu; Koizumi, Yasuo

1999-07-01

38

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

39

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

NASA Technical Reports Server (NTRS)

A simplified expression to estimate surface temperatures in forced convection boiling was developed using a liquid nitrogen data base. Using the principal of corresponding states and the Kutateladze relation for maximum pool boiling heat flux, the expression was normalized for use with other fluids. The expression was applied also to neon and water. For the neon data base, the agreement was acceptable with the exclusion of one set suspected to be in the transition boiling regime. For the water data base at reduced pressure greater than 0.05 the agreement is generally good. At lower reduced pressures, the water data scatter and the calculated temperature becomes a function of flow rate.

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

1977-01-01

40

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.

41

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

PubMed

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

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

2011-03-01

42

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

NASA Astrophysics Data System (ADS)

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

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

2012-07-01

43

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

44

Determination of the cross-sectional temperature distribution and boiling limitation of a heat pipe  

NASA Technical Reports Server (NTRS)

A computer model is developed and verified which is capable of determining the cross-sectional temperature distribution within a heat pipe with an attached radiator fin; such heat pipes would be plugged into contact heat exchangers designed to carry heat from a space station habitation module to the radiator elements through a centralized fluid loop. The model can furnish information for determining the susceptibility of the monogroove heat pipe to boiling, as well as the location and magnitude of that boiling.

Peterson, G. P.

1987-01-01

45

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

E-print Network

Numerical Study of Spatial Surface Temperature and Nucleation Site Density At High Heat Flux Pool method was developed to explore spatial and temporal variations on surface temperature. The results show Boiling, Surface Temperature, Nucleation Site Density INTRODUCTION The macrolayer is widely used

Maruyama, Shigeo

46

Molecular van der Waals symmetry affecting bulk properties of condensed phases: melting and boiling points  

Microsoft Academic Search

Qualitative analysis of the trends in melting temperatures T\\u000a \\u000a m\\u000a and boiling temperatures T\\u000a \\u000a b\\u000a of organic compounds and related substances supports a concept of van der Waals symmetry suggested earlier by the authors.\\u000a Data for substituted methanes, ethanes, ethylenes, benzenes and cyclohexanes, reveal linear T\\u000a \\u000a b\\u000a versus M\\u000a ? patterns but usually non-uniform T\\u000a \\u000a m\\u000a versus M\\u000a ? patterns

Yuri L. Slovokhotov; Andrei S. Batsanov; Judith A. K. Howard

2007-01-01

47

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

48

Pool boiling  

SciTech Connect

Heat transfer between a wall and a stagnant boiling liquid is reviewed in this paper. The effect of different parameters on the boiling curve is pointed out on the basis of experimental data from the literature. Augmentation of heat transfer by enhanced surfaces is described briefly. The available correlations for prediction of heat transfer coefficients are given for the entire boiling curve, i.e., nucleate, transitional, and film boiling, and critical points. These correlations are useful for the design and operation of various heat-exchange systems.

Lallemand, M. [Lab. d`Energetique et d`Automatique, Villeurbanne (France). Centre de Thermique

1993-10-01

49

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

50

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

NASA Astrophysics Data System (ADS)

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

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

2009-02-01

51

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

52

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

53

Time and space resolved wall temperature and heat flux measurements during nucleate boiling with constant  

E-print Network

Time and space resolved wall temperature and heat flux measurements during nucleate boiling used to measure heat transfer data are often on the order of, or larger than, the bubble characteristic al. [4]. Yaddanapudi and Kim [5] measured local heat trans- fer underneath single bubbles nucleating

Kim, Jungho

54

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

SciTech Connect

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

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

1982-07-01

55

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

SciTech Connect

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

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

2008-10-15

56

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

57

Recurrence calculations of organic compound boiling temperatures from data on preceding homologues  

Microsoft Academic Search

A new approach to calculating the temperatures of boiling at atmospheric pressure (T\\u000a b) of organic compounds from arbitrary homologous series is suggested. The approach is based on the linear dependence of these\\u000a values on T\\u000a b for the preceding homologues, T\\u000a b(n) = aTb(n ? 1) + b. This dependence, revealed for the first time, was used to obtain

I. G. Zenkevich

2006-01-01

58

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

Microsoft Academic Search

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

Fabiana Alves de Lima Ribeiro; Márcia Miguel Castro Ferreira

2003-01-01

59

Characterization of petroleum using near-infrared spectroscopy: Quantitative modeling for the true boiling point curve and specific gravity  

Microsoft Academic Search

This work describes a new approach to predict the true boiling point (TBP) curve and to estimate the API gravity in order to characterize the petroleum processed in refineries by using the information present in its absorbance spectrum obtained in the near-infrared region (NIR). The absorbance spectra were obtained in the range from 3700 to 10000cm?1 employing a CaF2 transmittance

Celio Pasquini; Aerenton Ferreira Bueno

2007-01-01

60

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

61

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

Microsoft Academic Search

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

D. J. Steinberg

1974-01-01

62

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

63

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

E-print Network

Application of the COSMO-SAC-BP Solvation Model to Predictions of Normal Boiling Temperatures reported the COSMO-SAC-BP model for predicting vapor pressure and its temperature derivative, the enthalpy of vaporization. This COSMO-SAC-BP model, which contains no compound specific parameters, is based on determining

Goddard III, William A.

64

Determination of the Latent Heats and Triple Point of Perfluorocyclobutane  

ERIC Educational Resources Information Center

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

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

1977-01-01

65

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

PubMed

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

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

2013-04-01

66

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

67

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

PubMed Central

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

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

2013-01-01

68

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

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

69

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

70

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

ERIC Educational Resources Information Center

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

Beauchamp, Guy

2005-01-01

71

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

Microsoft Academic Search

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

Rudolf Ladenstein; Garabed Antranikian

72

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

PubMed

It has become clear since about a decade ago, that the biosphere contains a variety of microorganisms that can live and grow in extreme environments. Hyperthermophilic microorganisms, present among Archaea and Bacteria, proliferate at temperatures of around 80-100 degrees C. The majority of the genera known to date are of marine origin, however, some of them have been found in continental hot springs and solfataric fields. Metabolic processes and specific biological functions of these organisms are mediated by enzymes and proteins that function optimally under these extreme conditions. We are now only starting to understand the structural, thermodynamic and kinetic basis for function and stability under conditions of high temperature, salt and extremes of pH. Insights gained from the study of such macromolecules help to extend our understanding of protein biochemistry and -biophysics and are becoming increasingly important for the investigation of fundamental problems in structure biology such as protein stability and protein folding. Extreme conditions in the biosphere require either the adaptation of the amino acid sequence of a protein by mutations, the optimization of weak interactions within the protein and at the protein-solvent boundary, the influence of extrinsic factors such as metabolites, cofactors, compatible solutes. Furthermore folding catalysts, known as chaperones, that assist the folding of proteins may be involved or increased protein protein synthesis in order to compensate for destruction by extreme conditions. The comparison of structure and stability of homologous proteins from mesophiles and hyperthermophiles has revealed important determinants of thermal stability of proteins. Rather than being the consequence of one dominant type of interactions or of a general stabilization strategy, it appears that the adaptation to high temperatures reflects a number of subtle interactions, often characteristic for each protein species, that minimize the surface energy and the hydration of apolar surface groups while burying hydrophobic residues and maximizing packing of the core as well as the energy due to charge-charge interactions and hydrogen bonds. In this article, mechanisms of intrinsic stabilization of proteins are reviewed. These mechanisms are found on different levels of structural organization. Among the extrinsic stabilization factors, emphasis is put on archaea chaperonins and their still strongly debated function. It will be shown, that optimization of weak protein-protein and protein-solvent interactions plays a key role in gaining thermostability. The difficulties in correlating suitable optimization criteria with real thermodynamic stability measures are due to experimental difficulties in measuring stabilization energies in large proteins or protein oligomers and will be discussed. Thus small single domain proteins or isolated domains of larger proteins may serve as model systems for large or multidomain proteins which due to the complexity of their thermal unfolding transitions cannot be analyzed by equilibrium thermodynamics. The analysis of the energetics of the thermal unfolding of a small, hyperthermostable DNA binding protein from Sulfolobus has revealed that a high melting temperature is not synonymous with a larger maximum thermodynamic stability. Finally, it is now well documented, that many thermophilic and hyperthermophilic proteins show a statistically increased number of salt bridges and salt bridge networks. However their contribution to thermodynamic and functional stability is still obscure. PMID:9670797

Ladenstein, R; Antranikian, G

1998-01-01

73

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

PubMed

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

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

2014-08-01

74

Time and space resolved wall temperature and heat flux measurements during nucleate boiling with constant heat flux boundary conditions  

Microsoft Academic Search

The lack of time and space resolved measurements under nucleating bubbles has complicated efforts to fully explain pool-boiling phenomena. In this work, time and space resolved temperature and heat flux distributions under nucleating bubbles on a constant heat flux surface were obtained using a 10×10 microheater array with 100?m resolution along with high-speed images. A numerical simulation was used to

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

2005-01-01

75

High flux film and transition boiling  

SciTech Connect

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

Witte, L.C.

1993-02-01

76

Boiling radial flow in fractures of varying wall porosity  

SciTech Connect

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

Barnitt, Robb Allan

2000-06-01

77

Local subcooled flow boiling model development  

SciTech Connect

Several existing heat transfer models for uniformly heated channels were examined to accurately represent the boiling curve and to characterize the local heat transfer coefficient under high-heat-flux (HHF) conditions. Comparisons with HHF data showed that major correlation modifications were needed in the subcooled partial nucleate boiling (SPNB) region. Because the slope of the boiling curve in this region is important to ensure continuity of the HHF trends into the fully developed boiling region and up to the critical heat flux, accurate characterization in the SPNB region is essential. Approximations for the asymptotic limits for the SPNB region have been obtained and have been used to develop an improved composite correlation. The developed correlation has been compared with 363 water data points. For the local heat transfer coefficient and wall temperature, the overall percent standard deviations with respect to the data were 19 and 3%, respectively, for the high-velocity water data. 14 refs., 3 figs., 3 tabs.

Boyd, R.D.; Meng, X. [Prairie View A& M Univ., TX (United States)

1996-07-01

78

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

NASA Astrophysics Data System (ADS)

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

Bloch, Gregor; Kuczaty, Julian; Sattelmayer, Thomas

2014-02-01

79

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

80

A novel refrigerator attaining temperature below ? point  

NASA Astrophysics Data System (ADS)

The present study proposes a novel refrigerator in theory, which uses 4He as working fluid to directly reach 2.3 K and uses a small amount of 3He to attain the temperature below 1.7 K. The compact and highly efficient new refrigerator works with the Vuilleumier cycle. The novel refrigerator is driven by a thermal compressor which creatively uses mix-refrigerants J-T refrigerator alternative to liquid nitrogen as the power source. Furthermore, the Vuilleumier cycle can be used to achieve temperature below liquid helium with the improvement of the ultra-low temperature regenerator material. A new method of reaching the temperature below 1.7 K is proposed on the regenerative refrigerator, which could be an important breakthrough for the cryogenic science and technology.

Zhou, Yuan; Xue, XiaoDai; Wang, JunJie; Gu, Chao

2012-08-01

81

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

E-print Network

-nearest neighbors, recurrence plots and space�time separation plots are obtained using the TISEAN package.7 in film boiling. False-nearest neighbor estimates and recurrence plots show that nucleate boiling may

Banerjee, Debjyoti

82

Ensemble Artificial Neural Networks for Prediction of Dew Point temperature  

Microsoft Academic Search

Dew point temperature is needed as an input to calculate various meteorological variables. In general, it contributes to human and animal comfort levels. The goal of this study was to develop artificial neural network (ANN) models for dew point temperature prediction to improve upon previous research. These improvements included optimizing the stopping criteria, comparing seasonal models to year-round models, and

D. B. Shank; Ronald W. Mcclendon; J. Paz; Gerrit Hoogenboom

2008-01-01

83

Aspects of subcooled boiling  

SciTech Connect

Subcooled boiling boiling refers to boiling from a solid surface where the bulk liquid temperature is below the saturation temperature (subcooled). Two classes are considered: (1) nucleate boiling, where, for large subcoolings, individual bubbles grow and collapse while remaining attached to the solid wall, and (2) film boiling, where a continuous vapor film separates the solid from the bulk liquid. One mechanism by which subcooled nucleate boiling results in very large surface heat transfer coefficient is thought to be latent heat transport within the bubble, resulting from simultaneous evaporation from a thin residual liquid layer at the bubble base, and condensation at the polar bubble cap. Another is the increased liquid microconvection around the oscillating bubble. Two related problems have been attacked. One is the rupture of a thin liquid film subject to attractive and repulsive dispersion forces, leading to the formation of mesoscopic drops, which then coalesce and evaporate. Another is the liquid motion in the vicinity of an oscillating contact line, where the bubble wall is idealized as a wedge of constant angle sliding on the solid wall. The subcooled film boiling problem has been attacked by deriving a general long-range nonlinear evolution equation for the local thickness of the vapor layer. Linear and weakly-nonlinear stability results have been obtained. A number of other related problems have been attacked.

Bankoff, S.G. [Northwestern Univ., Evanston, IL (United States)

1997-12-31

84

Thermal Resistance due to Point Defects at High Temperatures  

Microsoft Academic Search

An expression is obtained for the lattice thermal conductivity at high temperatures in the limit when the scattering of phonons by point defects is stronger than by umklapp processes. The latter limit the phonon mean free path at low frequencies and most of the heat is transported at frequencies such that the point defect and umklapp mean free paths are

P. G. Klemens

1960-01-01

85

Effects of Storage Temperature on Tyramine Production by Enterococcus faecalis R612Z1 in Water-Boiled Salted Ducks.  

PubMed

Tyramine production by Enterococcus faecalis R612Z1 in water-boiled salted ducks was evaluated during storage at different temperatures. The results showed that E. faecalis R612Z1 could produce tyramine in meat samples when the storage temperature was no less than 4°C. The E. faecalis R612Z1 counts of the meat samples reached 10(8) CFU/g on day 7 at 4°C and on day 4 at 10°C. However, the tyramine content of the meat samples stored at 10°C increased to 23.73 ?g/g (on day 10), which was greater than the level in the samples stored at 4°C (7.56 ?g/g). Reverse transcription quantitative PCR detection of the expression level of the tyrDC gene in E. faecalis R612Z1 in the meat samples revealed no significant changes at different storage temperatures. Thus, the changes in tyramine production of E. faecalis R612Z1 may be due to the different enzymatic activities at different storage temperatures. PMID:25285502

Liu, Fang; Du, Lihui; Wu, Haihong; Wang, Daoying; Zhu, Yongzhi; Geng, Zhiming; Zhang, Muhan; Xu, Weimin

2014-10-01

86

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 temperature

Bahrami, Majid

87

Bizarre Boiling  

NSDL National Science Digital Library

This NASA website has QuickTime videos that compare boiling water on Earth and in space. A photo shows the bubble that forms in space once some of the water is boiled. Text provides background information and explains how the experiments were performed.

2007-07-01

88

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

National Technical Information Service (NTIS)

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

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

1990-01-01

89

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

90

Forming of aluminium alloy at temperatures just below melting point  

Microsoft Academic Search

In order to improve the mechanical properties of products, a forming process of a solid material at a temperature just below the melting point is proposed. The material is deformed at the semi-solid temperature due to the heat generation caused by plastic deformation. The tensile strength, elongation, hardness and toughness of the aluminium alloy (Al–7%Si–0.3%Mg) billet extruded at temperatures between

M Shiomi; D Takano; K Osakada; M Otsu

2003-01-01

91

Electron temperature difference between the o-point and x-point of a magnetic island  

SciTech Connect

The electron temperature difference between the o-point and the x-point of a magnetic island is studied numerically by solving the two-dimensional energy transport equation. It is found that, even without a localized radio-frequency heating at the island's o-point, there is usually a temperature difference between these two points. This difference depends on the radial profile of the heating power deposition, the ratio between the parallel and the perpendicular heat conductivity and the island width, and it takes a minimum when the island width is about twice the local heat diffusion layer width. The effect of the temperature difference on the island growth is further studied, and the peaked heating power density profile at magnetic axis is found be destabilizing.

Yang Jinhong; Zhu Sizheng [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Center for Magnetic Fusion Theory, Chinese Academy of Sciences, Hefei 230031 (China); Yu Qingquan [Max-Planck-Institute fuer Plasmaphysik, EURATOM Association, 85748 Garching (Germany); Zhuang, G. [College of Electrical and Electronic Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China)

2009-09-15

92

One temperature step away from the critical point  

Microsoft Academic Search

The disappearance of a wide range of critical fluctuations following a sudden temperature step away from the critical point is investigated theoretically. The step switches off the strong interaction on length scales larger than the final state correlation radius. This results in a nonequilibrium free field with fluctuations much larger than those in the final equilibrium state. In the course

Alexander Z. Patashinski

1996-01-01

93

Complex saddle points in QCD at finite temperature and density  

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

94

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

95

Pointing and temperature retrieval from millimeter-submillimeter limb soundings  

NASA Astrophysics Data System (ADS)

Passive microwave limb sounding instruments like the Millimeter-Wave Atmospheric Sounder (MAS) or the Microwave Limb Sounder (MLS) observe dedicated oxygen lines for the derivation of temperature and pointing information, since these quantities are essential for the quality of the retrieval of the trace gas mixing ratio. Emission lines of oxygen are chosen because the volume mixing ratio (VMR) profile is known. In this paper, we demonstrate the capabilities of a new and innovative method by means of which accurate temperature and pointing information can be gathered from other strong spectral features like ozone lines, without including accurate knowledge of the VMR profile of these species. For this purpose, retrievals from two observation bands with a bandwidth of about 10 GHz each, one including an oxygen line, have been compared. A full error analysis was performed with respect to critical instrument and model parameters, such as uncertainties in the antenna pattern, calibration uncertainties, random pointing error, baseline ripples, baseline discontinuities, and spectroscopic parameters. The applied inversion algorithm was the optimal estimation method. For the selected scenario and instrumental specifications we find that the retrieval of a pointing offset and the atmospheric temperature profile can be achieved with a good accuracy. The retrieval precision of the pointing offset is better than 24 m. The retrieval precision of the temperature profile is better than 2 K for altitudes ranging from 10 to 40 km. Systematic errors (due to model parameter uncertainties) are somewhat larger than these purely statistical errors. Investigations carried out for different atmospheric states or different instrumental specifications show similar results.

Verdes, C.; Bühler, S.; von Engeln, A.; Kuhn, T.; Künzi, K.; Eriksson, P.; Sinnhuber, Björn-Martin

2002-08-01

96

Probability distributions of peak-clad temperature and cladding oxidation thickness in loss-of-coolant accidents for a typical boiling water reactor. [MOXY-EM calculations  

Microsoft Academic Search

The probability distributions of the peak-clad temperature (PCT) and of the maximum cladding oxidation thickness supposed to occur in the hypothetical loss-of-coolant accidents (LOCAs) for a typical boiling water reactor (BWR) are studied by a computer-simulated experiment, using the computer program MOXY-EM, one of the fuel heatup analysis codes for a BWR. To reduce the numbers of the computer runs,

T. Shimooke; K. Matsumoto

1977-01-01

97

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...

98

Thermodynamic temperature measurements of silver freezing point and HTFPs  

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

99

Characteristics of Transient Boiling Heat Transfer  

SciTech Connect

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

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

2002-07-01

100

Boiling on a straight pin fin  

SciTech Connect

In this study, Multimode boiling on a straight pin is theoretically investigated. Axial steady-state temperature distributions along the fin are numerically evaluated, as well as their linear stability characteristics. When film and transition boiling coexist on the fin surface, or only the transition boiling covers the entire fin, the operation remains stable only if the fin length is less than some critical value. When transition and nucleate boiling coexist on a fin, or the fin is in the three-mode boiling (film + transition + nucleate boiling), the entry of nucleate boiling at the fin tip stabilizes the boiling process. This study on base heat flow and fin efficiency with the stability criteria also suggests a new fin design methodology.

Lin, W.W.; Lee, D.J. [National Taiwan Univ., Taipei (Taiwan, Province of China). Dept. of Chemical Engineering] [National Taiwan Univ., Taipei (Taiwan, Province of China). Dept. of Chemical Engineering

1996-10-01

101

Phenomenology of boiling: A coupled map lattice model.  

PubMed

A minimal model for boiling is proposed. With increasing temperature of a bottom plate, the model shows three successive phases; conduction, nucleate, and film boiling. In the nucleate regime the heat flux increases with the temperature of the bottom plate, while it decreases in the film boiling regime. In the boiling phase, the maximum Lyapunov exponent is positive, implying that the boiling phenomena are spatiotemporally chaotic. PMID:12779984

Yanagita, Tatsuo

1992-07-01

102

Predictions of void fraction in convective subcooled boiling channels using a one-dimensional two-fluid model  

SciTech Connect

Subcooled nucleate boiling under forced convective conditions is of considerable interest for many disciplines, such as nuclear reactor technology and other energy conversion systems, due to its high heat transfer capability. For such applications, the liquid entering the heating channel is usually in a subcooled state and nucleate boiling is initiated at some distance from the entrance. Further downstream from the boiling incipient point, the bubbles may depart from the heating wall. The point of first bubble departure is called the net vapor generation (NVG) point, because after this point, significant void is present in the subcooled liquid and the void fraction rises very rapidly even though the bulk liquid may still be in a highly subcooled state. The presence of vapor bubbles, which are at a temperature near the saturation temperature, in a subcooled liquid shows the existence of thermal nonequilibrium, which complicates the analysis of this boiling regime. 13 refs., 4 figs.

Hu, Lin-Wen; Pan, Chin [National Tsing Hua Univ., Hsinchu (Taiwan, Province of China)

1995-08-01

103

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

104

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

NASA Technical Reports Server (NTRS)

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

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

1973-01-01

105

Onset of nucleate boiling in minichannels  

Microsoft Academic Search

Heat transfer characteristics during flow boiling in a minichannel were studied. For these investigations a thermographic measuring method was used. The axial distribution of the external wall temperature was measured, from which the internal wall temperatures and the local heat transfer coefficient are calculable. Detailed investigations were carried out in particular for the onset of nucleate boiling. The results of

Ingo Hapke; Hartwig Boye; Jürgen Schmidt

2000-01-01

106

FEASIBILITY STUDY FOR THE CONCEPTUAL DESIGN OF ADUAL-CORE BOILING SUPERHEAT REACTOR.  

E-print Network

??For research concerning economical applications of high temperature reactortechnology, a novel approach for creating a Boiling Superheat Reactor (BSR) byaugmenting an Advanced Boiling Water Reactor… (more)

Ross, Jacob

2009-01-01

107

Local Heat Transfer and CHF for Subcooled Flow Boiling - Annual Report 1994  

SciTech Connect

The physical phenomenon of forced convective boiling is probably one of the most interesting and complex transport phenomena. It has been under study for more than two centuries. Simply stated, forced convective subcooled boiling involves a locally boiling fluid: (1) whose mean temperature is below its saturation temperature, and (2) that flows over a surface exposed uniformly or non-uniformly to a high heat flux (HHF). The objective of this work is to assess and/or improve the present ability to predict local axial heat transfer distributions in the subcooled flow boiling regime for the case of uniformly heated coolant channels. This requires an accurate and complete representation of the boiling curve up to the CHF. The present. results will be useful for both heat transfer research and industrial design applications. Future refinements may result in the application of the results to non-uniformly heated channels or other geometries, and other fluids. Several existing heat transfer models for uniformly heated channels were examined for: (1) accurate representation of the boiling curve, and (2) characterizing the local heat transfer coefficient under high heat flux (HHF) conditions. Comparisons with HHF data showed that major correlation modifications were needed in the subcooled partial nucleate boiling (SPNB) region. Since the slope of boiling curve in this region is important to assure continuity of the HHF trends into the fully developed boiling region and up to the critical heat flux, accurate characterization in the SPNB region is essential. Approximations for the asymptotic limits for the SPNB region have been obtained and have been used to develop an improved composite correlation. The developed correlation has been compared with 363 water data points. For the local heat transfer coefficient and wall temperature, the over-all percent standard deviations with respect to the data were 19% and 3%, respectively, for the high velocity water data.

Dr. Ronald D. Boyd

2000-07-01

108

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

NASA Astrophysics Data System (ADS)

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

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

2013-07-01

109

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

110

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

SciTech Connect

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

Witte, L.C.

1993-02-01

111

Reduction of lattice thermal conductivity by point defects at intermediate temperatures  

Microsoft Academic Search

The lattice thermal conductivity is reduced by point defects because they scatter phonons. An analytic expression can be derived only in the limit of high temperatures; at lower temperatures one must have recourse to numerical calculations. Because the conductivity is due mainly to phonons of low frequencies when point-defect scattering is strong, the high-temperature approximation can be used at temperatures

F. L. Madarasz; P. G. Klemens

1987-01-01

112

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

113

Heat transfer in pool boiling under microgravity  

Microsoft Academic Search

Results are presented on parabolic-flight experiments performed on board ballistic rockets, designed to investigate the effect of system acceleration on the pool boiling curves for Freon 2. Measurements were carried out for a wide range of temperatures and pressures, and boiling curves were constructed for elevated gravity, earth gravity, and reduced gravity. It is demonstrated that, under reduced gravity conditions,

M. Zeii; J. Straub; B. Vogel

1990-01-01

114

Experimental study on multi-mode methanol flow boiling  

SciTech Connect

Flow boiling of methanol over a nonuniform, indirect conduction heating surface is investigated experimentally. An axial (discrete) heat flux distribution corresponding to a neutral stability region where nucleate and film boiling can coexist steadily is identified. Below such a heat flux distribution, nucleate boiling mode is more stable. Above this distribution, film boiling mode becomes more stable. An equal-area criterion based on difference between bottom heat flux and surface boiling heat flux and the surface temperature data is employed for interpreting the experimental data, and reasonable agreement is obtained. The differences between average and real transition boiling curves are discussed as well.

Lin, W.W.; Lee, D.J. [National Taiwan Univ., Taipei (Taiwan, Province of China). Dept. of Chemical Engineering

1996-12-31

115

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

116

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

117

Radiance temperature (at 653 nm) of tungsten at its melting point  

Microsoft Academic Search

The radiance temperature (at 653 nm) of tungsten at its melting point was measured using a subsecond-duration pulse-heating technique. Specimens in the form of strips with initially different surface roughnesses were used. The results do not indicate any dependence of radiance temperature (at the melting point) on initial surface or system operational conditions. The average radiance temperature (at 653 nm)

A. Cezairliyan; A. P. Miiller

1982-01-01

118

Atomistic simulation of point defects in silicon at high temperature  

Microsoft Academic Search

The Stillinger–Weber interatomic potential is used in molecular dynamics simulations to compute estimates of the equilibrium and transport properties of self-interstitials and vacancies in crystalline silicon at high temperature. Equilibrium configurations are predicted as a ?110? dumbbell for a self-interstitial, and as an inwardly relaxed configuration for a vacancy. Both structures show considerable delocalization with increasing temperature, which leads to

Talid Sinno; Z. Kurt Jiang; Robert A. Brown

1996-01-01

119

Main limitations in infrared temperature measurement of train hot points  

NASA Astrophysics Data System (ADS)

Nowadays, in order to guarantee the security in passenger and goods railway transport, fixed systems located in rails are used to measure axles, wheels and brake discs temperatures during train circulation so that abnormally high temperatures as a result of a malfunction can be detected. Measurement systems in this kind of application may be affected by different uncertainty sources, characteristic of infrared temperature measurements, which limit the accuracy of the estimated measurement. Uncertainty sources are specially important in these applications due to: (1) Extremely variable emissivity as a result of stain or different paints used on the surfaces. (2) Difficult evaluation of the environment's radiation as measurements are made outdoors. (3) Alarm temperatures are only about 40 degrees Celsius to 80 degrees Celsius above the environment temperature. The paper analyses the effects of these uncertainties. The results show that, in order to get the minimum uncertainty peaks in the estimated temperature, the proper duty waveband is 3 - 5 micrometer. They also show that, with a proper choice of the wavelength, the uncertainty due to solar radiation remains masked by the uncertainty due to the lens emissivity.

Meca Meca, Francisco J.; Rodriguez Sanchez, Francisco J.; Mazo Quintas, Manuel; Jimenez Calvo, Jose A.; Lillo Rodriguez, Diego; Ramos Sainz, Pablo

2000-06-01

120

Boiling of nuclear liquid in the micro-canonical ensemble  

E-print Network

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

121

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

122

Subcooled nucleate boiling heat transfer from a large diameter tube  

SciTech Connect

Nucleate boiling heat transfer from the outside of large-diameter tubes has not been well studied. There are many large-diameter horizontal tubes in the core of a CANDU{reg_sign} nuclear reactor, and it is important to quantify the different modes of heat transfer from the tubes (known as calandria tubes) to the heavy water moderator. This paper describes a series of experiments performed to study nucleate boiling heat transfer from the outside surface of a horizontal calandria tube to subcooled and pressurized light water. When the circulating pump was on, it caused an upflow of water in the vicinity of the tube, estimated to be an average of 0.3 m/s. The flow cooled the tube and increased the surface temperature fluctuations, in contrast to the relatively steady temperatures observed by Dowlati and Byrne (1995) in a test section of similar diameter, but made from a solid copper block. The cooling effect of the pumped flow was the greatest for high subcooling, low heat flux and high pressure. The magnitudes of these fluctuations are explained in terms of transient heat conduction when the surface alternates between nucleation and cooling by the cold liquid. The heat transfer from the bottom of the tube was modelled by a combination of pool boiling, global single-phase natural convection and stagnation-point single-phase forced-convection correlations. The experiments showed that Rohsenow`s pool boiling correlation (with a single-phase free convection component) successfully modelled the outer surface temperatures on the large-diameter horizontal tube when the circulating pump was off. Even at high water subcooling (60 C) and low heat flux (200 kW/m{sup 2}), nucleate boiling dominated the heat transfer.

Brown, M.J. [Atomic Energy of Canada Limited, Whiteshell, Manitoba (Canada). Whiteshell Labs.; Fung, K.K. [Ontario Hydro Nuclear, Toronto, Ontario (Canada); Byrne, T.P. [Ontario Hydro Technologies, Toronto, Ontario (Canada)

1996-12-31

123

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

E-print Network

of the temperature dependence of the shear moduli. The high-temperature anomalies of defect formation volume, tracer at high temperatures [21, 22], assuming that the Schottky defect formation parameters determined to withinDefect pressure, formation volume, and temperature dependence of formation properties of point

Boyer, Edmond

124

Numerical simulation of pool boiling for steady state and transient heating  

SciTech Connect

It's believed that the macrolayer plays an important role in nucleate and transition boiling heat transfer at high heat flux. Many experiments have been carried out to support the macrolayer evaporation model, however, little has been conducted in the numerical simulation of boiling heat transfer. In this study, based on the macrolayer evaporation model of Maruyama et al. (1992), a numerical simulation of pool boiling for steady state was carried out. The key points of the simulation are: (1) It is modeled that the macrolayer containing vapor stems occupies the region immediately next to the wall and that the vapor stems are formed on the active cavity sites. (2) Not only does the evaporation occur at the vapor bubble-macrolayer interface, but also at the liquid-vapor stem interface. (3) The macrolayers form periodically. No liquid is supplied to the macrolayers during the hovering period. While the vapor mass departs from the surface, the macrolayers replenish immediately despite the complicity of the transition period between the departures of two vapor masses. The major results are: (1) The boiling curves of water and FC-72 (C{sub 6}F{sub 14}) were reasonably predicted. (2) The temporal variations in surface temperature for different boiling regimes were obtained. Secondly, the simulation of transient pool boiling was conducted. It was realized with following assumptions: (1) The macrolayer evaporation model can be extended to the transient pool boiling. The macrolayer forms cyclically and its thickness is determined by the surface heat flux when the vapor mass takes off. (2) One-dimensional transient heat conduction within the heater coupled with the macrolayer model was considered. Being employed explicit FDM, the instantaneous surface temperature can be obtained. Therefore, the instantaneous heat flux can be calculated by applying the surface temperature into the macrolayer model. (3) In the transition-boiling regime, the initial thickness of macrolayer was determined by the extrapolated value of the obtained nucleate boiling curve. The simulated results showed that: (1) For lower transient heating rate, the boiling curve in the nucleate boiling regime almost remains the same as the steady-state curve. For higher transient heating rate, it deviates from the steady-state curve. (2) The critical heat flux increases with increasing heating transients. The investigation of the changes of macrolayer thickness and void fraction implies that the evaporation of macrolayer has a great effect on the increase of CHF under transient heating.

He, Ying; Shoji, Masahiro; Maruyama, Shigeo

1999-07-01

125

Boiling of Water Droplets Containing Dissolved Salts  

Microsoft Academic Search

We conducted experiments on the effect of dissolving three different salts (sodium chloride, sodium sulphate and magnesium sulphate) in water droplets boiling on a hot stainless steel surface. Substrate temperatures were varied from 100^oC to 300^oC. We photographed droplets as they evaporated, and recorded their evaporation time. At surface temperatures that were too low to initiate nucleate boiling, all three

Qiang Cui; Sanjeev Chandra; Susan McCahan

2000-01-01

126

On the Extended Point Defect Model in Si Crystals at High Temperature  

Microsoft Academic Search

We herein discuss Seeger and Chik's model of extended point defects in Si crystals at high temperature based on our experimental results on the diffusion constant of vacancies at high temperature and the vacancy formation energy. We also show that the application of the extended model to the recombination of a vacancy and an interstitial is unsuitable, by pointing out

Masashi Suezawa; Ichiro Yonenaga

2008-01-01

127

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

SciTech Connect

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

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

2007-04-07

128

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

E-print Network

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

McSharry, Patrick E.

129

Transient behavior of superheated water jets boiling  

NASA Astrophysics Data System (ADS)

Superheated water flowing out from high-pressure chamber through short cylindrical and slot channel has been studied experimentally. Relation of vaporization mechanisms in superheated liquid (boiling in single, not interacting centers, intense heterogeneous vaporization, and homogeneous fluctuating nucleation) and respective forms of superheated water jets has been determined. Temperature intervals with transient behavior of boiling have been determined. It is shown that at transient behavior of boiling the amplitude of pulsations of jet parameters increases, and in the spectra of pulsation power, the low-frequency component 1/ f appears.

Reshetnikov, A. V.; Busov, K. A.; Mazheiko, N. A.; Skokov, V. N.; Koverda, V. P.

2012-06-01

130

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

131

Point defect and diffusion properties in oxides from high temperature creep  

Microsoft Academic Search

A study of high temperature creep properties of non-stoichiometric CU2O, CoO and NiO has been performed at various temperatures and oxygen activities (Po2). Creep rates are directly related to point defects responsible for the diffusion of the slowest species. These point defects have been tentatively identified by the Po2 dependence of creep rate which does not depend on the detailed

A. Dominguez-Rodriguez; J. Castaing

1983-01-01

132

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

NASA Technical Reports Server (NTRS)

Loop heat pipes (LHPs) have been used for thermal control of several NASA and commercial orbiting spacecraft. The LHP operating temperature is governed by the saturation temperature of its compensation chamber (CC). Most LHPs use the CC temperature for feedback control of its operating temperature. There exists a thermal resistance between the heat source to be cooled by the LHP and the LHP's CC. Even if the CC set point temperature is controlled precisely, the heat source temperature will still vary with its heat output. For most applications, controlling the heat source temperature is of most interest. A logical question to ask is: "Can the heat source temperature be used for feedback control of the LHP operation?" A test program has been implemented to answer the above question. Objective is to investigate the LHP performance using the CC temperature and the heat source temperature for feedback control

Ku, Jentung; Paiva, Kleber; Mantelli, Marcia

2011-01-01

133

Electron and ion temperature gradients and suprathermal tail strengths at Parker's solar wind sonic critical point  

Microsoft Academic Search

New constraints are placed on the electron and ion temperature gradients at Parker's sonic point, demonstrated here as the location for an ion where the force of gravity and the electric field parallel to the magnetic field are balanced. The equal- temperature, one-fluid versions of these results precisely recover Parker's necessary and sufficient conditions for the supersonic expansion. The two

J. D. Scudder

1996-01-01

134

Electron and ion temperature gradients and suprathermal tail strengths at Parker's solar wind sonic critical point  

Microsoft Academic Search

New constraints are placed on the electron and ion temperature gradients at Parker's sonic point, demonstrated here as the location for an ion where the force of gravity and the electric field parallel to the magnetic field are balanced. The equal-temperature, one-fluid versions of these results precisely recover Parker's necessary and sufficient conditions for the supersonic expansion. The two species

J. D. Scudder

1996-01-01

135

COMPARISON OF GLASS TRANSITION TEMPERATURE AND STICKY POINT TEMPERATURE FOR SKIM MILK POWDER  

Microsoft Academic Search

Wall deposition of particles in spray dryers is a key processing problem, and information about the glass transition temperature of the amorphous material that arises from spray drying can be used to guide the selection of operating conditions that may minimise wall deposition. The glass transition temperatures for skim milk powder with various moisture contents were determined using Differential Scanning

L. Ozmen; T. A. G. Langrish

2002-01-01

136

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

NASA Astrophysics Data System (ADS)

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

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

2008-06-01

137

Changes in skin surface temperature at an acupuncture point with moxibustion  

PubMed Central

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

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

2013-01-01

138

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.

2012-06-07

139

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

PubMed Central

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

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

2008-01-01

140

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

NASA Technical Reports Server (NTRS)

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

Bahrami, Parviz A.

2012-01-01

141

Boiling Temperature and Reversed Deliquescence Relative Humidity Measurements for Mineral Assemblages in the NaCl + NaNO3 + KNO3 + Ca(NO3)2 + H2O System  

SciTech Connect

Boiling temperature measurements have been made at ambient pressure for saturated ternary solutions of NaCl + KNO{sub 3} + H{sub 2}O, NaNO{sub 3} + KNO{sub 3} + H{sub 2}O, and NaCl + Ca(NO{sub 3}){sub 2} + H{sub 2}O over the full composition range, along with those of the single salt systems. Boiling temperatures were also measured for the four component NaCl + NaNO{sub 3} + KNO{sub 3} + H{sub 2}O and five component NaCl + NaNO{sub 3} + KNO{sub 3} + Ca(NO{sub 3}){sub 2} + H{sub 2}O mixtures, where the solute mole fraction of Ca(NO{sub 3}){sub 2}, x(Ca(NO{sub 3}){sub 2}), was varied between 0 and 0.25. The maximum boiling temperature found for the NaCl + KNO{sub 3} + H{sub 2}O system is {approx} 134.9 C; for the NaNO{sub 3} + KNO{sub 3} + H{sub 2}O system is {approx} 165.1 C at x(NaNO{sub 3}) {approx} 0.46 and x(KNO{sub 3}) {approx} 0.54; and for the NaCl + Ca(NO{sub 3}){sub 2} + H{sub 2}O system is 164.7 {+-} 0.6 C at x(NaCl) {approx} 0.25 and x(Ca(NO{sub 3}){sub 2}) {approx} 0.75. The NaCl + NaNO{sub 3} + KNO{sub 3} + Ca(NO{sub 3}){sub 2} + H{sub 2}O system forms molten salts below their maximum boiling temperatures, and the temperatures corresponding to the cessation of boiling (dry out temperatures) of these liquid mixtures were determined. These dry out temperatures range from {approx} 300 C when x(Ca(NO{sub 3}){sub 2}) = 0 to {ge} 400 C when x(Ca(NO{sub 3}){sub 2}) = 0.20 and 0.25. Mutual deliquescence/efflorescence relative humidity (MDRH/MERH) measurements were also made for the NaNO{sub 3} + KNO{sub 3} and NaCl + NaNO{sub 3} + KNO{sub 3} salt mixture from 120 to 180 C at ambient pressure. The NaNO{sub 3} and NaCl + NaNO{sub 3} + KNO{sub 3} salt mixture has a MDRH of 26.4% at 120 C and 20.0% at 150 C. This salt mixture also absorbs water at 180 C, which is higher than expected from the boiling temperature experiments. The NaCl + NaNO{sub 3} + KNO{sub 3} salt mixture was found to have a MDRH of 25.9% at 120 C and 10.5% at 180 C. The investigated mixture compositions correspond to some of the major mineral assemblages that are predicted to control brine composition due to the deliquescence of salts formed in dust deposited on waste canisters in the proposed nuclear repository at Yucca Mountain, Nevada.

Rard, J A; Staggs, K J; Day, S D; Carroll, S A

2005-12-01

142

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

143

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

EPA Science Inventory

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

144

Boiling of an emulsion in a yield stress fluid  

NASA Astrophysics Data System (ADS)

We report the boiling behavior of pentane emulsified in a yield stress fluid, a colloidal clay (Laponite) suspension. We have observed that a superheated state is easily reached: the emulsion, heated more than 50°C above the alkane boiling point, does not boil. Superheating is made possible by the suppression of heterogeneous nucleation in pentane, resulting from the emulsification process, a phenomenon evidenced decades ago in studies of the superheating of two phase fluids. We have furthermore studied the growth of isolated bubbles nucleated in the emulsion. The rate of increase of the bubble radius with time depends on both the temperature and emulsion volume fraction but, rather unexpectedly, does not depend on the fluid rheology. We show that the bubbles grow by diffusion of the alkane through the aqueous phase between liquid droplets and bubbles, analogously to an Ostwald ripening process. The peculiarity of the process reported here is that a layer depleted in oil droplets forms around the bubble, layer to which the alkane concentration gradient is confined. We successfully describe our experimental results with a simple transfer model.

Guéna, Geoffroy; Wang, Ji; D'Espinose, Jean-Baptiste; Lequeux, François; Talini, Laurence

2010-11-01

145

Investigation of Noises in Boiling on an Electrically Heated Wire  

Microsoft Academic Search

An experimental investigation of noises in boiling on an electrically heated wire in a water volume has been carried out. Its results point to the fact that the type of heating of the heat-exchange surface has a significant influence on the processes of boiling and the noises appearing as a result of them. It is shown that heating by a

A. V. Korolev; A. N. Litvin

2002-01-01

146

Upgrading of high boiling hydrocarbons  

SciTech Connect

A process is described for upgrading a high boiling hydrocarbon, comprising: deasphalting the high boiling hydrocarbon to recover as separate fractions, deasphalted oil, resin and pitch; upgrading the resin fraction to produce an effluent containing upgraded product and high boiling components; recovering high boiling components from the effluent; subjecting the deasphalting at least a portion of the recovered high boiling components to reject coke precursors in the (pitch fraction) high boiling components portion prior to recycle thereof to the upgrading with the resin fraction; and thereafter recycling the high boiling components portion with the resin fraction to the upgrading.

Van Driesen, R.P.; Friday, J.R.

1987-08-11

147

A Method to Improve the Temperature Distribution of Holder Around the Fixed-Point Cell Position  

NASA Astrophysics Data System (ADS)

The temperature profile along the furnaces used in heating high-temperature fixed points has a crucial impact on the quality and duration of melting plateaux, accordingly the accuracy of thermodynamic temperature determination of such fixed points. This paper describes a simple, yet efficient, approach for improving the temperature uniformity along a cell holder in high-temperature blackbody (HTBB) furnaces that use pyrolytic graphite rings as heating elements. The method has been applied on the KRISS' HTBB furnace. In this work, an ideal solution for arranging the heating elements inside the furnace is presented by which the temperature gradient across the cell holder can be kept as low as possible. Numerical calculations, based on a finite element method, have been carried out to find the best possible arrangement of the rings. This has been followed by measuring the temperature gradient along an empty cell holder to validate our calculations. A temperature gradient of 100 mK has been achieved at over a length of 50 mm within a cell holder of 10 cm in length. It has also been shown that for a 20 cm long holder surrounded by rings with an arbitrary resistance profile, the temperature uniformity can be improved by adding a few "hot" rings around the cell holder.

Lim, S. D.; Karmalawi, A. M.; Salim, S. G. R.; Soliman, M. A.; Kim, B. H.; Lee, D. H.; Yoo, Y. S.

2014-07-01

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

Pressure and Temperature Effects on Point-Defect Equilibria and Band Gap of ZnS  

Microsoft Academic Search

The pressure (100–200 MPa) and temperature (900–1100°C) effects on the equilibria of native point defects and background impurities in Zn-enriched ZnS are studied using cathodoluminescence and transmission spectra. The optimal conditions are found under which high pressures and temperatures accelerate migration of defects and impurities. The associated structural and compositional changes are studied by scanning electron microscopy. The increase in

N. K. Morozova; I. A. Karetnikov; K. V. Golub; E. M. Gavrishchuk; E. V. Yashina; V. G. Plotnichenko; V. G. Galstyan

2004-01-01

150

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

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

151

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

152

Temperature-Sensitive Inhibition of Development in Dictyostelium Due to a Point Mutation  

E-print Network

. The piaAHSB1 gene product displayed a partial inhibitory effect on wild-type cell development. We., 2000). During growth, Dictyostelium cells behave as free-living amoebae, which feed on bacteriaTemperature-Sensitive Inhibition of Development in Dictyostelium Due to a Point Mutation in the pia

Devreotes, Peter

153

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

SciTech Connect

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

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

1991-03-05

154

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

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

155

Numerical simulation of pool boiling of a Lennard-Jones liquid  

NASA Astrophysics Data System (ADS)

We performed a numerical simulation of pool boiling by a molecular dynamics model. In the simulation, a liquid composed of Lennard-Jones particles in a uniform gravitational field is heated by a heat source at the bottom of the system. The model successfully reproduces the change in regimes of boiling from nucleate boiling to film boiling with the increase of the heat source temperature. We present the pool boiling curve by the model, whose general behavior is consistent with those observed in experiments of pool boiling.

Inaoka, Hajime; Ito, Nobuyasu

2013-09-01

156

Boiling of multicomponent liquid mixtures  

SciTech Connect

This article reviews the significant advances in the understanding of the boiling process germane to mixtures. The scope of this review is limited to miscible systems. The effects of impurities (such as lubricating oils in refrigerants), surfactants, soluble salts, and dissolved gases are excluded from consideration. Both pool and convective boiling are addressed. The ultimate goals of the study of boiling of liquid mixtures are: to predict the superheat required for the inception of boiling, to predict their heat transfer coefficients with a reasonable degree of accuracy, and to predict the variation in the peak nucleate and dry out heat fluxes with composition. These goals are closer to being met for pool boiling than they are for convective boiling. The topics discussed in this survey are presented in much the same order as when an increasing heat flux is applied to a surface to cause boiling. Thus bubble nucleation or boiling incipience is considered first, since this defines the criteria required for boiling to commence. Then the growth of the vapor bubbles from vapor nuclei up to and including their departure from the surface is discussed. This is followed by a survey of the heat transfer mechanisms, resulting from the vaporization process, which affect the nucleate pool boiling curve, and this leads to a discussion of equations for predicting nucleate pool boiling heat transfer coefficients. The peak nucleate heat flux in pool boiling is examined prior to a description of film boiling. Several aspects of convective boiling are then presented.

Thome, J.R.; Shock, R.A.W.

1984-01-01

157

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

158

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

159

Optimization of the thermogauge furnace for realizing high temperature fixed points  

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

160

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

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

161

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

162

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

163

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

164

A Fundamental Study of Nucleate Pool Boiling Under Microgravity  

NASA Technical Reports Server (NTRS)

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

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

1996-01-01

165

A fundamental study of nucleate pool boiling under microgravity  

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

166

Stability of electric heaters in the boiling heat transfer process  

SciTech Connect

Boiling heat transfer from electrically heated wires and composite heaters was studied in the three boiling regimes; nucleate, transition, and film. The electrical input to the heaters was controlled by the heater temperature through the use of feedback control techniques. Particular attention was paid to the transition region of the boiling curve where the slope is negative and operation is unstable without proper control. Boiling curves produced by an x-ray plotter are presented for gold-plated tungsten wires and also for platinum wires. Stability conditions and transfer functions were developed for a complete composite heater system. Steady-state operation in the transition region of the boiling curve clearly demonstrates that there are two separate transition curves depending on whether the temperature is increasing or decreasing.

Loeffler, R.I.

1991-01-01

167

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

E-print Network

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

168

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

E-print Network

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

169

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

E-print Network

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

170

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

E-print Network

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

Paris-Sud XI, Université de

171

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

E-print Network

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

Kandlikar, Satish

172

Steadystate solutions in a nonlinear pool boiling model Michel Speetjens # , Arnold Reusken # , Wolfgang Marquardt +  

E-print Network

Steady­state solutions in a nonlinear pool boiling model Michel Speetjens # , Arnold Reusken a relatively simple model for pool boiling processes. This model in­ volves only the temperature distribution within the heater and desribes the heat exchange with the boiling fluid via a nonlinear boundary

173

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

E-print Network

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

Stevenson, Paul

174

In situ technique for measuring heat transfer from a power transistor to a boiling liquid  

Microsoft Academic Search

A technique for in situ measurement of temperature and heat flux in boiling heat transfer from electronic chips is described. The method was used to obtain accurate partial boiling curves for jet impingement and pool boiling in R-113. While the characteristics of the heat transfer behavior agree with previous data, the data in general lie below data obtained with specialized

C. L. Struble; L. C. Witte

1994-01-01

175

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

176

AC susceptibility and temperature modulation studies of gadolinium near the Curie point  

Microsoft Academic Search

Measurements of the ac susceptibility and temperature modulation studies of the ac and dc magnetic properties of polycrystalline gadolinium in the vicinity of the Curie point Tc are reported. Field-independent exchange-enhanced paramagnetism was observed above Tc. Below Tc the initial field-independent susceptibility was observed for applied fields < 8 A\\/m rms and exhibited a frequency dependence characteristic of a magnetic

K. R. Sydney; D. H. Chaplin; G. V. H. Wilson

1976-01-01

177

Point defect structure of CdTeCl crystals at high temperatures  

Microsoft Academic Search

High temperature Hall effect measurements in CdTeCl single crystals grown by THM and Bridgman techniques at 200-900 °C under well defined Cd and Te vapor pressure were made. Associates decay at heating from 500 to 700 °C in THM grown samples was observed. Cd vapour pressure influence on electron concentration [e-] in all samples was established. The main point defects

Petro Fochuk; Oleg Panchuk; Larysa Shcherbak; Paul Siffert

2005-01-01

178

Calculations of the effects of point defects on hubbard models of high temperature superconductivity  

Microsoft Academic Search

We describe studies of the effects of defects on Hubbard models of highT\\u000a \\u000a c\\u000a superconductors. We first present numerical mean field calculations on thet-J model in which disorder due to point defects in treated explicitly. Secondly, we describe variational Monte Carlo calculations\\u000a at zero temperature in which the full effects of the Gutzwiller projection are included in a calculation of

J W Halley; S Davis; P Samsel; Robert Joynt

1991-01-01

179

High-temperature electrical conductivity and point defects in lead zirconate-titanate  

Microsoft Academic Search

The electrical conductivity and thermoelectric power of lead zitconate-titanate Pb(Ti0.47Zr0.53)O3 (PZT) have been studied at temperatures up to 1000°C in gaseous ambients with controlled partial pressures of both volatile components: lead oxide and oxygen. The experimental results show the small polaron conduction mechanism in PZT. The predominant point defects, as obtained from the oxygen pressure dependences of the conductivity and

V. V. Prisedsky; V. I. Shishkovsky; V. V. Klimov

1977-01-01

180

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

181

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

182

Microbiological Effectiveness of Disinfecting Water by Boiling in Rural Guatemala  

PubMed Central

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

Rosa, Ghislaine; Miller, Laura; Clasen, Thomas

2010-01-01

183

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

184

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

NASA Astrophysics Data System (ADS)

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

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

2011-02-01

185

Convective nucleate boiling on a heated surface cooled by an impinging, planar jet of water  

SciTech Connect

Convective nucleate boiling has been studied on a flat, upward facing, constant heat flux surface cooled by a planar, impinging water jet. Surface temperature distributions are presented for jet velocities between 1.8 and 4.5 m/s, fluid temperatures of 30, 40, and 50C, and heat fluxes between 0.25 and 2.5 MW/m{sup 2}. Although the critical Reynolds number, Re{sub x{asterisk},c}, is independent of heat flux for q{double prime} < q{double prime}{sub ONB}, boiling incipience strongly affects the transition to a turbulent boundary layer. As the heat flux increases, vapor bubbles of 1 mm diameter first appear at the point of maximum surface temperature, which also marks the onset of boundary layer turbulence. The leading edge of these bubbles moves toward the stagnation line and Re{sub x{asterisk},c} decreases with further increases in heat flux. Acceleration in the stagnation region stabilizes the flow, however, so that boundary layer turbulence is restricted to x/w{sub j} {approx gt} 1.6. With increasing heat flux, vigorous nucleate boiling covers more of the heater and surface temperature variations decrease.

Vader, D.T.; Incropera, F.P.; Viskanta, R. (Purdue Univ., West Lafayette, IN (United States))

1992-02-01

186

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

187

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

NASA Astrophysics Data System (ADS)

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

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

2003-09-01

188

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

189

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

SciTech Connect

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; Amar, Jacques G. [Department of Physics and Astronomy, University of Toledo, Toledo, Ohio 43606 (United States); Callahan, Nathan B. [Department of Physics and Astronomy, University of Toledo, Toledo, Ohio 43606 (United States); Department of Physics, Indiana University, Bloomington, Indiana 47405 (United States)

2013-03-07

190

Boiling of Water Droplets Containing Dissolved Salts  

NASA Astrophysics Data System (ADS)

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

Cui, Qiang; Chandra, Sanjeev; McCahan, Susan

2000-11-01

191

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

192

Boiling heat transfer of impacting liquid sprays on solid surfaces  

SciTech Connect

The nucleate spray boiling region and the film spray boiling region were investigated. In the nucleate regime, an exploratory experimental investigation was carried out with a unique spray generator which allowed independent control over the spray parameters. The liquids used in the study were water and FC-72,a dielectric fluid, and the surface was copper. Parametric studies revealed that the liquid mass flux and the liquid subcooling were the main parameters which affect nucleate spray boiling, while droplet parameters had little effect. Even under peak heat flux conditions, a large fraction of the sprayed liquid remained unvaporized. However, peak heat fluxes obtained were much higher than those for pool boiling and seem to be of the same order as free impinging jet boiling. The problem of temperature overshoot at boiling incipience was carefully checked for impacting liquid sprays. No evidence of it was found. For the film boiling region of impacting sprays, analysis of this complex heat transfer process was attempted by separating the region into dilute and dense sprays. The heat transfer of an impacting dilute spray was analyzed by dividing the process into three identified subprocesses-drop contact heat transfer, bulk air convective heat transfer and radiative heat transfer. Since the dense spray film boiling region is complicated tremendously by the presence of interaction, the approach found successful was to identify, analyze and predict the asymptotic conditions.

Deb, S.

1988-01-01

193

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

194

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

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

195

Tympanic thermometer performance validation by use of a body-temperature fixed point blackbody  

NASA Astrophysics Data System (ADS)

The use of infrared tympanic thermometers within the medical community (and more generically in the public domain) has recently grown rapidly, displacing more traditional forms of thermometry such as mercury-in-glass. Besides the obvious health concerns over mercury the increase in the use of tympanic thermometers is related to a number of factors such as their speed and relatively non-invasive method of operation. The calibration and testing of such devices is covered by a number of international standards (ASTM1, prEN2, JIS3) which specify the design of calibration blackbodies. However these calibration sources are impractical for day-to-day in-situ validation purposes. In addition several studies (e.g. Modell et al4, Craig et al5) have thrown doubt on the accuracy of tympanic thermometers in clinical use. With this in mind the NPL is developing a practical, portable and robust primary reference fixed point source for tympanic thermometer validation. The aim of this simple device is to give the clinician a rapid way of validating the performance of their tympanic thermometer, enabling the detection of mal-functioning thermometers and giving confidence in the measurement to the clinician (and patient!) at point of use. The reference fixed point operates at a temperature of 36.3 °C (97.3 °F) with a repeatability of approximately +/- 20 mK. The fixed-point design has taken into consideration the optical characteristics of tympanic thermometers enabling wide-angled field of view devices to be successfully tested. The overall uncertainty of the device is estimated to be is less than 0.1°C. The paper gives a description of the fixed point, its design and construction as well as the results to date of validation tests.

Machin, Graham; Simpson, Robert

2003-04-01

196

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

NASA Astrophysics Data System (ADS)

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

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

2010-10-01

197

Vigilance system in rails for train hot point temperatures during circulation  

NASA Astrophysics Data System (ADS)

Wheels, hubs and brake discs in a train during its circulation are under mechanical strains that make its temperature increase above the environment temperature. Mechanical defects in those elements produce an excessive friction and, as a consequence of it, an important increment of its temperature in relation to normal values. Detecting these anomalies is essential to avoid accidents and it is performed by fixed systems located next to rails which make infrared temperature measurements of hot points and send them to a supervisory station that takes the proper steps. The paper introduces the most important problems which must be dealt with during the designing stage of the measurement system. It also explains the solutions taken by the authors in order to assure the minimum operative aims demanded by the application. These problems includes: the choice of the detector and measurement method, communication with the supervisory station, and the environment conditions. Finally, the research lines followed by the authors in order to improve and extend the system's capabilities are explained.

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

2000-06-01

198

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

199

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 temperatures for myo- and neo-inositol also compare very well to the experimentally obtained data. The glass, respectively, and the shape of the volume versus temperature plots produced are typical for a glass transition

de Gispert, Adrià

200

Nucleate boiling in drag-reducing polymer solutions  

SciTech Connect

Two types of experiment have been done to study the effects of polymer additives in nucleate boiling for plates and wires. Here, boiling on a flat surface is simulated by placing a flat unheated surface immediately underneath an electrically heated platinum wire. Saturated nucleate pool boiling curves were measured for water and solutions of six different polymers at various concentrations. For a bare wire and a simulated flat surface, the nucleate boiling curves are qualitatively similar. For equal heat fluxes, the temperature difference increases as the relative viscosity increases, although the temperature difference for the simulated flat surface is less than that for the bare wire. The observed changes in the nucleate boiling curves for polymer solutions are in qualitative agreement with those predicted using the Rohsenow correlation to account for change in the solution viscosity. These results show that for both wires and simulated flat surfaces, drag-reducing additives will reduce the heat transfer rate in nucleate boiling. Bubble dynamics on the heated wire and simulated flat surface were also measured using a high speed movie camera for water and Separan AP-30 at a relative viscosity of 1.16. The data were used to determine the relative contribution to the boiling heat flux of latent heat transport by bubbles, natural convection heat transfer, and enhanced convection heat transfer.

Jeun, G.

1986-01-01

201

The Evolution of the Celsius and Kelvin Temperature Scales and the State of the Art  

Microsoft Academic Search

A physical analysis is given of the evolution undergone by the Celsius and Kelvin temperature scales, from their definition to the present day. It is shown that in the temperature interval between the melting point of ice and the boiling point of water, the Celsius and Kelvin scales, both born centigrade by definition and actually become so afterwards by experimental

Julio Pellicer; M. Amparo Gilabert; Ernesto Lopez-Baeza

1999-01-01

202

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

203

Colour, myoglobin denaturation and storage stability of raw and cooked mutton chops at different end point cooking temperature.  

PubMed

In our study effect of different end point temperature (51 °C, 65 °C, 71 °C and 79 °C) on physicochemical and storage stability of mutton chops were evaluated. The L* (lightness) value and b* (yellowness) increased (P?point temperature increased. As internal cooking temperature increased soluble myoglobin content decreased with a corresponding increase in percent myoglobin denatured. Raw mutton chops (uncooked) had lower level of oxidation (less TBA values) than cooked mutton irrespective of storage length. Initial APC of raw and cooked mutton chops ranged from log 1.75 to log 3.73 and was lower in higher end point cooking temperature. It can be concluded that as end point temperature increased, mutton chops appear less red and raw mutton had lower level of oxidation than cooked mutton chops. PMID:24803706

Sen, A R; Naveena, B M; Muthukumar, M; Vaithiyanathan, S

2014-05-01

204

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

205

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

206

Experimental evidence of the vapor recoil mechanism in the boiling crisis.  

PubMed

Boiling crisis experiments are carried out in the vicinity of the liquid-gas critical point of H2. A magnetic gravity compensation setup is used to enable nucleate boiling at near critical pressure. The measurements of the critical heat flux that defines the threshold for the boiling crisis are carried out as a function of the distance from the critical point. The obtained power law behavior and the boiling crisis dynamics agree with the predictions of the vapor recoil mechanism and disagree with the classical vapor column mechanism. PMID:17155547

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

2006-11-01

207

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

208

Nucleate and transition boiling in narrow horizontal spaces  

NASA Astrophysics Data System (ADS)

Nucleate and transition boiling are performed in a horizontal narrow space between a heated upward-facing copper disk and an unheated surface for saturated n-pentane. The heat flux and the wall temperature are determined by mean of an inverse heat conduction method. The influence of the confinement on the boiling curves and the flow patterns are analysed. Characteristic instabilities are observed at low heat flux and during the transition regime.

Stutz, Benoit; Lallemand, Monique; Raimbault, Fabien; Passos, Julio

2009-05-01

209

Derivation of molecular species profiles, atmospheric temperature profile, and instrumental pointing from SMILES instrument  

NASA Astrophysics Data System (ADS)

Recent progress in sub-millimeter wave receiver technology gives the possibility to drastically improve the quality of limb sounding data by use of a superconductor-insulator-superconductor (SIS) mixer element. This receiver will detect molecular spectra with a signal-to-noise ratio one order of magnitude better than the conventional ambient--temperature Schottky receiver. SMILES (Superconductor Submillimeter-wave Limb-emission Sounder) is proposed by the Communications Research Laboratory and the National Space Agency of Japan, with technical support from the National Astronomical Observatory, and with scientific support from the University of Bremen, in order to demonstrate the new sub-millimeter wave technology in space, and to conduct the measurements of limb-emission sounding for a group of molecular species profiles. In order to anticipate the performance of the instrument, retrieval simulations are carried out. Synthetic measurements, as will be recorded by the SMILES instrument, are generated by the use of a forward model. These are then inverted, using an inversion model, in order to derive the variables of interest, such as molecular species profiles (e.g., O3, ClO, HCl), atmospheric temperature profile, or a first order instrumental pointing correction (i.e., a pointing offset). The applied inversion algorithm is the Optimal Estimation Method (OEM). The advantage of the OEM is that it allows a formal error analysis needed for a general error characterization of retrieval performance. The error analysis takes into consideration the total statistical error, the measurement error, the vertical altitude resolution, and the correlation between the retrieved quantities. The altitude domain of a good measurement sensibility is defined by the measurement response.

Verdes, Carmen; Buehler, Stefan; Kuenzi, Klaus

2003-04-01

210

The Influence of Operating Modes, Room Temperature Set Point and Curtain Styles on Energy Consumption of Room Air Conditioner  

E-print Network

A field investigation was carried out in an office building of Changsha city in winter and summer, the influence of different running modes, curtain styles and room temperature set point on energy consumption of room air conditioner (RAC...

Yu, J.; Yang, C.; Guo, R.; Wu, D.; Chen, H.

2006-01-01

211

Dissolution and precipitation of silica at low temperatures  

Microsoft Academic Search

The dissolution of amorphous silica as monosilicic acid and the establishment of solubility equilibrium with silica gel and with colloidal silica have been demonstrated in recent chemical papers. The rates of dissolution and precipitation are slow at ordinary temperatures; at temperatures near the boiling-point both solubilities and rates of dissolution are much higher. The solubility is little affected by pH

Konrad B. Krauskopf

1956-01-01

212

Enhanced pool boiling heat transfer with surface attachment  

SciTech Connect

This paper reports on a pool boiling experiment with either water or Freon-113 that was conducted to investigate nucleate boiling from a heated wall with either a spherical or a cylindrical attachment. The result revealed that nucleate boiling can be enhanced by applying a horizontal cylindrical attachment to a vertical heated wall, owing to the favorable thermal environment characterized by a small-gradient liquid temperature profile within the restricted regions between the attachment and the heated wall. Nucleate boiling is enhanced in terms of a lower wall superheat required for incipient boiling and more bubbles generated than from an open heated wall. As a result of the enhanced nucleate boiling, heat transfer of the vertical heated wall above the attachment was improved due to excessive bubbles moving upward along the heated wall, causing removal of the thermal layer near the wall and evaporation of the thin liquid film between the bubbles and the wall. The boiling curve hysteresis with Freon-113 was significantly reduced as a result. The effects of diameter, length, and surface roughness of the cylindrical attachment were also investigated.

Chyu, M.C.; Mghamis, A.M. (Dept. of Mechanical Engineering, Texas Technical Univ., Lubbock, TX (US))

1992-01-01

213

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

SciTech Connect

This report is one in the series of 'POINT' reports that over the years have presented temperature dependent cross sections for the then current version of ENDF/B [R1]. In each case I have used my personal computer at home and publicly available data and codes: (1) publicly available nuclear data (the current ENDF/B data, available on-line at the National Nuclear Data Center, Brookhaven National Laboratory, http://www.nndc.bnl.gov/) and, (2) publicly available computer codes (the current PREPRO codes, available on-line at the Nuclear Data Section, IAEA, Vienna, Austria, http://www-nds.iaea.or.at/ndspub/endf/prepro/) and, (3) My own personal computer located in my home. I have used these in combination to produce the temperature dependent cross sections used in applications and described in this report. I should mention that today anyone with a personal computer can produce these results: by its very nature I consider this data to be born in the public domain.

Cullen, D E

2012-02-26

214

Absolute Spectral Radiometric Determination of the Thermodynamic Temperatures of the Melting\\/Freezing Points of Gold, Silver and Aluminium  

Microsoft Academic Search

Narrow band filter radiometers have been used to measure the spectral radiance of black bodies held at the melting\\/freezing points of aluminium, silver and gold with an accuracy of 0,04%. Descriptions are given of the optical components and the techniques used for their characterization. As the measurements are absolute, the thermodynamic temperatures of these points can be calculated directly from

N. P. Fox; J. E. Martin; D. H. Nettleton

1991-01-01

215

A study of electrowetting-assisted boiling  

E-print Network

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

Bralower, Harrison L. (Harrison Louis)

2011-01-01

216

Boiling Fluids Behave Quite Differently in Space  

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...

217

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

218

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

219

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

E-print Network

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

220

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

E-print Network

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

221

Computations of Boiling in Microgravity  

NASA Technical Reports Server (NTRS)

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

Tryggvason, G.; Jacqmin, Dave

2000-01-01

222

Determination of the furnace effect of two high-temperature furnaces on metal-carbon eutectic points  

NASA Astrophysics Data System (ADS)

A method for the determination of the temperature distribution in the range from 1300 °C to 2500°C is introduced in this paper. This method was adapted to characterize the two high temperature furnaces used at LNE-Cnam: the Chino IR-R80 and the VNIIOFI HTBB 3200pg. Temperature profiles are given at three furnace temperatures, corresponding to the three most studied metal-carbon eutectic points: Co-C (1324 °C), Pt-C (1738 °C) and Re-C (2474 °C). These three fixed points were then studied in the two furnaces in different known temperature profiles, in order to determine their sensitivity to the temperature distribution. Finally, a discussion on what can be included in the term "furnace effect" is proposed.

Bourson, F.; Briaudeau, S.; Rougié, B.; Sadli, M.

2013-09-01

223

Boiling incipience in a reboiler tube  

SciTech Connect

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

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

1991-03-01

224

Boiling local heat transfer enhancement in minichannels using nanofluids.  

PubMed

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

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

2013-01-01

225

Zinc Oxide Nanowire Forest for Pool Boiling Heat Transfer  

NASA Astrophysics Data System (ADS)

Zinc oxide (ZnO) nanowire forest is applied for the electronics cooling by means of pool boiling heat transfer. The forest was composed of lengthwise grown backbone and branched nanowires, which were highly dense and tree-like hierarchical structures. The platinum heater and resistance temperature detector were fabricated by microfabrication on one side of silicon chips and nanowire forest was synthesized on the other side. The superheat and heat flux were evaluated at steady state while the voltage in the heater was increased gradually. The heat flux gradually increased linearly with superheat at the initial stage of heating due to convective heat transfer and abruptly increased once the coolant started to boil. It seemed that the nanowire forest played a role of increased bubble nucleation sites with superhydrophilic nature leading to enhancement of boiling heat transfer. This sheds light on application of nanostructured surface as an effective electronics cooling by boiling heat transfer.

Lee, Dongjin; Kim, Taehyun; Park, Sungsik; Lee, Seung Seob; Ko, Seung Hwan

2012-11-01

226

Point defect behavior in high temperature region in the B2-type intermetallic compound FeAl  

Microsoft Academic Search

The defect structure was investigated for B2-type Fe1 ? cAlc alloys (0.44 < c ? 0.51) by in-situ neutron diffraction measurements in the temperature range from room temperature to 1260–1300 K. Resulting point-defect behavior at high temperatures above about 800–1000 K where additional thermal vacancies are created is summarized as two common features: (1) thermal vacancies are formed on both

M. Kogachi; T. Haraguchi; S. M. Kim

1998-01-01

227

Thermodynamic temperature determinations of Co C, Pd C, Pt C and Ru C eutectic fixed-point cells  

NASA Astrophysics Data System (ADS)

Thermodynamic temperatures during the melt and the freeze of Co-C, Pd-C, Pt-C and Ru-C metal-carbon fixed-point cells manufactured by LNE-INM/CNAM, NMIJ and NPL were determined by absolutely calibrated filter radiometers traceable to the PTB cryogenic radiometer and a radiance comparison method using an IKE LP3 radiation thermometer. The measurement uncertainties were below 400 mK at temperatures up to 2250 K. The results are in agreement within the combined uncertainties with a study on relative temperature differences of the same set of fixed-point cells. For the fixed-point cells manufactured by NPL the results are compared with a previous thermodynamic temperature measurement.

Anhalt, K.; Hartmann, J.; Lowe, D.; Machin, G.; Sadli, M.; Yamada, Y.

2006-04-01

228

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

229

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

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

230

Using temperature gradient gas chromatography to determine or predict vapor pressures and linear solvation energy relationship parameters of highly boiling organic compounds  

Microsoft Academic Search

An isothermal chromatographic method allowing determination of ??2H and ??2H descriptors of the linear solvation energy relationship (LSER) was tested and results obtained are presented. This method is based on the use of four stationary phases of various polarity. On the other hand, it was demonstrated that the temperature gradient chromatography may be successfully used to determine LSER descriptors. Results

F Mutelet; M Rogalski

2003-01-01

231

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

232

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

PubMed

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

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

2013-01-01

233

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

234

Branching points in the low-temperature dipolar hard sphere fluid.  

PubMed

In this contribution, we investigate the low-temperature, low-density behaviour of dipolar hard-sphere (DHS) particles, i.e., hard spheres with dipoles embedded in their centre. We aim at describing the DHS fluid in terms of a network of chains and rings (the fundamental clusters) held together by branching points (defects) of different nature. We first introduce a systematic way of classifying inter-cluster connections according to their topology, and then employ this classification to analyse the geometric and thermodynamic properties of each class of defects, as extracted from state-of-the-art equilibrium Monte Carlo simulations. By computing the average density and energetic cost of each defect class, we find that the relevant contribution to inter-cluster interactions is indeed provided by (rare) three-way junctions and by four-way junctions arising from parallel or anti-parallel locally linear aggregates. All other (numerous) defects are either intra-cluster or associated to low cluster-cluster interaction energies, suggesting that these defects do not play a significant part in the thermodynamic description of the self-assembly processes of dipolar hard spheres. PMID:24116579

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

2013-10-01

235

Branching points in the low-temperature dipolar hard sphere fluid  

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

236

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

237

Technical and QA plan: Boiling behavior during flow instability  

SciTech Connect

The coolant flow in a nuclear reactor core under normal operating conditions is kept as a subcooled liquid. This coolant is evenly distributed throughout the multiple flow channels with a uniform pressure profile across each coolant flow channel. If the coolant flow is reduced, the flow through individual channels will also decrease. A decrease in coolant flow will result in higher coolant temperatures if the heat flux is not reduced. When flow is significantly decreased, localized boiling may occur. This localized boiling can restrict coolant flow and the ability to transfer heat out of the reactor system. The maximum operating power for the reactor may be limited by how the coolant system reacts to a flow instability. One of the methods to assure safe operation during a reducing flow transient, is to operate at a power level below that necessary to initiate a flow excursion. Several correlations have been used to predict the conditions which will proceed a flow excursion. These correlations rely on the steady state behavior of the coolant and are based on steady-state testing. There are two significant points which this project will try to identify. The first is when vapor first forms on the channel surface. This might be designated as the Nucleate Vapor Transition. (Steady state equivalent is ONB). The second is when the vapor formation rate is large enough to lead to flow instability and thermal excursion. This point might be designated as the Significant Vapor Transition. (Steady state equivalent is OSV). A correlation will be developed to relate established steady state relations with the behavior of transient systems.

Coutts, D.A.

1991-09-06

238

Experimental study of surfactant effects on pool boiling heat transfer  

SciTech Connect

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

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

1990-02-01

239

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

240

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. For these data, diffusion from the upper surface of the drop is 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

241

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

SciTech Connect

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

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

2013-10-15

242

High flux film and transition boiling  

SciTech Connect

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

Witte, L.C.

1990-01-01

243

Boiling Radial Flow in Fractures of Varying  

E-print Network

SGP-TR-166 Boiling Radial Flow in Fractures of Varying Wall Porosity Robb Allan Barnitt June 2000 and boiling convective heat transfer, with boiling flow in a rock fracture. A series of experiments observed. The experimental study involved boiling radial flow in a simulated fracture, bounded by a variety of materials

Stanford University

244

Jet flow phenomena during nucleate boiling  

Microsoft Academic Search

Boiling phenomena are with highly complex nonlinear and nonequilibrium characteristics, which cause diversity and complexity of boiling nucleation. In the present paper, an experimental investigation was conducted to investigate the nucleate boiling behavior on a very fine heating wire. Using zoom routine and CCD camera system, the dynamical process of nucleate boiling was visually observed and several modes of jet

H. Wang; X. F. Peng; B. X. Wang; D. J. Lee

2002-01-01

245

Polarized optical properties of forsterite from room temperature up to the melting point  

NASA Astrophysics Data System (ADS)

Olivines are the most abundant phases of the Earth's upper mantle. Determining their optical properties under extreme conditions is essential to investigate their lattice dynamics and related structural evolution and to quantify their thermophysical properties. Optical properties of forsterite were determined by acquiring infrared emittance spectra from room temperature up to the melting point along the [100], [010] and [001] polarization directions and over a wide spectral range, from 50 to 15000 cm-1. The fitting of the experimental data by using a semi-quantum dielectric function model provides new results on lattice vibrations and phonon-phonon interactions in forsterite. In particular, a sudden enhancement of anharmonicity at high temperature is observed and is concomitant with the disappearance or brutal change of some modes around 1000K. The normal modes involving Mg1 cation motions are the more impacted and some of them vanish around 1200K. The polarization along [001] direction is more specifically impacted and this change can be linked to the magnesium mobility within M1 sites. This result is consistent with ab initio calculations1 and experimental data on tracer diffusion2 in forsterite that show the presence of an enhanced diffusion of magnesium via M1 sites along [001] direction. These data contribute to explain literature results that show evidences of a change of vibrational behaviour around 1000K, and in particular a strenghtening of lattice anharmonicity 3,4. This vibrational change may impact some important geophysical properties that depends on ionic diffusion, such as creep or electrical conductivity, were magnesium diffusion plays a key role. Finally, absorption coefficient has been calculated over the whole IR range from optical indices, allowing for the evaluation of the contribution of heat transport by radiation in forsterite. 1. J. Brodholt, Am. Mineral. 82, 1049-1053 (1997). 2. S. Chakraborty, J. R. Farver, R. A. Yund, D. C. Rubie, Phys. Chem. Miner. 21, 489-500 (1994). 3. P. Gillet, P. Richet, F. Guyot, G. Fiquet, J. Geophys. Research. B7, 96: 11805-11816 (1991). 4. F. Guyot, Y. Wang, P. Gillet, Y. Ricard, Phys. Earth. Planet. Inter. 98, 17-29 (1996).

Eckes, M.; Gibert, B.; De Sousa Meneses, D.; Malki, M.; Echegut, P.

2012-12-01

246

POOL BOILING OF HIGH-FREQUENCY CONDUCTORS  

SciTech Connect

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

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

2001-01-01

247

Flow boiling test of GDP replacement coolants  

SciTech Connect

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

Park, S.H. [comp.

1995-08-01

248

Flow Boiling and Condensation Experiment  

NASA Video Gallery

The Flow Boiling and Condensation Experiment is another investigation that examines the flow of a mixture of liquids and the vapors they produce when in contact with hot space system equipment. Coo...

249

Subcooled flow boiling of fluorocarbons  

E-print Network

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

Murphy, Richard Walter

1971-01-01

250

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

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

251

Influence of N2O oxidation of silicon on point defect injection kinetics in the high temperature regime  

Microsoft Academic Search

In this work we investigate the influence of N2O oxidation on the kinetics of point defects at high temperatures. The interstitials that are injected during the oxidation process are monitored by the growth of preexisting oxidation stacking faults. We show that at high temperatures (1050–1150 °C), the supersaturation of self-interstitials in the silicon substrate is enhanced when oxidation is performed

C. Tsamis; D. N. Kouvatsos; D. Tsoukalas

1996-01-01

252

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

Microsoft Academic Search

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

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

2011-01-01

253

A Time Domain Mixed-Mode Temperature Sensor with Digital Set-Point Programming  

Microsoft Academic Search

To realize the on-chip temperature monitoring of VLSI chips, an accurate time domain mixed-mode CMOS temperature sensor based on delay lines is proposed. Without any bipolar transistor, a temperature sensor composed of single delay line is utilized to generate the delay time proportional to the measured temperature. A succeeding multiplexer (MUX), instead of conventional voltage\\/current DAC or external resistor, along

Poki Chen; Chun-Chi Chen; Tuo-Kuang Chen; Shi-Wei Chen

2006-01-01

254

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

NASA Astrophysics Data System (ADS)

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

Zounemat-Kermani, Mohammad

2012-08-01

255

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

Code of Federal Regulations, 2011 CFR

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

2011-10-01

256

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

Code of Federal Regulations, 2010 CFR

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

2010-10-01

257

Multi-mode methanol flow boiling under atmospheric and subatmospheric pressures  

SciTech Connect

This is a continuation work of Lin and Lee (1996 National Heat Transfer Conference, Houston) while reporting the experimental results of multi-mode methanol flow boiling under atmospheric and subatmospheric pressures. An axial (discrete) heat flux distribution with neutral stability at which nucleate and film boiling can coexist steadily is identified under various system pressures and crossflow rates. Below this heat flux distribution, nucleate boiling mode is more stable. Above this distribution, film boiling becomes the more stable mode. An equal-area criterion based on the difference between bottom heat flux and surface boiling heat flux, and the wall superheat temperature relationship is employed for interpreting the experimental data. Effects of system pressure, mass flowrate, liquid subcooling and bottom heat flux on the relative stability of nucleate and film boiling modes are discussed.

Lin, W.W.; Liao, Y.C.; Lee, D.J. [National Taiwan Univ., Taipei (Taiwan, Province of China). Dept. of Chemical Engineering

1996-12-31

258

Liquid phase stability under an extreme temperature gradient.  

PubMed

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

Liang, Zhi; Sasikumar, Kiran; Keblinski, Pawel

2013-11-27

259

Expert system for control rod programming of boiling water reactors  

Microsoft Academic Search

Control rod programming, one of the main tasks in reactor core management of boiling water reactors (BWRs), can be successfully accomplished by well-experienced engineers. By use of core performance evaluation codes, their knowledge plays the main role in searching through optimal control rod patterns and exposure points for adjusting notch positions and exchanging rod patterns. An expert system has been

T. Fukuzaki; K. Yoshida; Y. Kobayashi; H. Matsuura; K. Hoshi

1986-01-01

260

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

261

The gallium melting-point standard: its application and evaluation for temperature measurements in the clinical laboratory.  

PubMed

We are impressed with the ease and certainty of calibration electronic thermometers with thermistor probes to +/- 0.01 degree C at the gallium melting point, 29.771(4) degrees C. The IFCC reference method for measuring aspartate aminotransferase activity in serum was run at the reaction temperature of 29.771(4) degrees C. By constantly referencing to gallium as an integral part of the assay procedure, we determined the absolute reaction temperature to IPTS-68 (International Practical Temperature Scale of 1968) to +/- 0.02 degrees C. This unique temperature calibration standard near the center of the range of temperatures commonly used in the clinical laboratory is a valuable addition and can be expected to improve the accuracy of measurements, especially in clinical enzymology. PMID:844169

Bowers, G N; Inman, S R

1977-01-01

262

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

263

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...

264

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

265

The initiation of boiling during pressure transients. [water boiling on metal surfaces  

NASA Technical Reports Server (NTRS)

The initiation of boiling of water on metal surfaces during pressure transients has been investigated. The data were obtained by a new technique in which light beam fluctuations and a pressure signal were simultaneously recorded on a dual beam oscilloscope. The results obtained agreed with those obtained using high speed photography. It was found that, for water temperatures between 90-150 C, the wall superheat required to initiate boiling during a rapid pressure transient was significantly higher than required when the pressure was slowly reduced. This result is explained by assuming that a finite time is necessary for vapor to fill the cavity at which the bubble originates. Experimental measurements of this time are in reasonably good agreement with calculations based on the proposed theory. The theory includes a new procedure for estimating the coefficient of vaporization.

Weisman, J.; Bussell, G.; Jashnani, I. L.; Hsieh, T.

1973-01-01

266

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

NASA Technical Reports Server (NTRS)

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

McQuillen, John; Chao, David; Vergilii, Frank

2006-01-01

267

Temperature dependent vibrational lifetimes in supercritical fluids near the critical point  

E-print Network

of the temperature depen- dence changes dramatically with solvent. Vibrational lifetimes in dense media are dominated and density. For this rea- son, supercritical fluids SCFs are useful media for the study of vibrational

Fayer, Michael D.

268

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

269

High-temperature point defect equilibrium in CdTe modelling  

Microsoft Academic Search

High-temperature (673–1173K) electrical property (?,RH) measurements in undoped and In-doped (up to 1×1020at\\/cm3) CdTe were performed under different stoichiometric conditions. Cadmium (tellurium) vapor pressure or temperature electron (hole) density dependences were obtained. The results are described by a computed defect structure model, which optimizes the defect reaction constants. A new In incorporation defect reaction is proposed, explaining the dopant self-compensation

P. Fochuk; O Korovyanko; O Panchuk

1999-01-01

270

Point defects in optical ceramics; High-temperature absorption processes in lanthana-strengthened yttria  

Microsoft Academic Search

The optical transmission of transparent polycrystalline LaâOâ-strengthened YâOâ was measured in both the near-ultraviolet and infrared regions at temperatures between 20° and 1400°C. The absorption remains low until about 900°C, but rises almost exponentially thereafter. The magnitude of this increase is a function of the oxygen partial pressure ({ital P}{sub Oâ}) in the ambient atmosphere. The temperature-dependent absorption is lowest

Charles Brecher; George C. Wei; William H. Rhodes

1990-01-01

271

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

272

The origin of thermocapillary convection in subcooled nucleate pool boiling  

Microsoft Academic Search

The significance of noncondensibles as the origin of thermocapillary convection in subcooled pool boiling is demonstrated in this paper. The temperature gradients along the bubble interface inducing thermocapillary convection are caused by saturation pressure gradients due to a nonuniform accumulation of noncondensable gas along the interface. On the vapour side, the noncondensable gas inhibits the condensation of vapour. The corresponding

R. Marek; J. Straub

2001-01-01

273

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

SciTech Connect

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

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

2003-04-15

274

Point 2004 A Temperature Dependent ENDF/B-VI, Release 8 Cross Section Library  

SciTech Connect

The ENDF/B data library has recently been updated and is now freely available through the National Nuclear Data Center (NNDC), Brookhaven National Laboratory. This most recent library is identified as ENDF/B-VI, Release 8. Release 8 completely supersedes all preceding releases. Release 8 will be the last release of ENDF/B-VI; the next release of ENDF/B data will be for the new ENDF/B-VII library. As distributed the ENDF/B-VI, Release 8 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 applications this library has been processed into the form of temperature dependent cross sections at eight neutron reactor like temperatures, between 0 and 2100 Kelvin, in steps of 300 Kelvin. 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/B-VI character format [1], which allows the data to be easily transported between computers. In its processed form this library is approximately 4.3 gigabyte in size and is distributed on a single DVD.

Cullen, D E

2004-02-09

275

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

NASA Astrophysics Data System (ADS)

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

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

276

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

E-print Network

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

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

2011-10-25

277

Quantum point contact displacement transducer for a mechanical resonator at sub-Kelvin temperatures  

SciTech Connect

Highly sensitive displacement transduction of a 1.67 MHz mechanical resonator with a quantum point contact (QPC) formed in a GaAs heterostructure is demonstrated. By positioning the QPC at the point of maximum mechanical strain on the resonator and operating at 80 mK, a displacement responsivity of 3.81 A/m is measured, which represents a two order of magnitude improvement on the previous QPC based devices. By further analyzing the QPC transport characteristics, a sub-Poisson-noise-limited displacement sensitivity of 25 fm/Hz{sup 1/2} is determined which corresponds to a position resolution that is 23 times the standard quantum limit.

Okazaki, Yuma; Mahboob, Imran; Onomitsu, Koji; Sasaki, Satoshi; Yamaguchi, Hiroshi [NTT Basic Research Laboratories, NTT Corporation, 3-1 Morinosato-Wakamiya, Atsugi, Kanagawa 243-0198 (Japan)] [NTT Basic Research Laboratories, NTT Corporation, 3-1 Morinosato-Wakamiya, Atsugi, Kanagawa 243-0198 (Japan)

2013-11-04

278

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

Microsoft Academic Search

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

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

1986-01-01

279

Prediction of high-temperature point defect formation in TiO 2 from combined ab initio and thermodynamic calculations  

Microsoft Academic Search

A computational approach that integrates ab initio electronic structure and thermodynamic calculations is used to determine point defect stability in rutile TiO2 over a range of temperatures, oxygen partial pressures and stoichiometries. Both donors (titanium interstitials and oxygen vacancies) and acceptors (titanium vacancies) are predicted to have shallow defect transition levels in the electronic-structure calculations. The resulting defect formation energies

J. He; R. K. Behera; M. W. Finnis; X. Li; E. C. Dickey; S. R. Phillpot; S. B. Sinnott

2007-01-01

280

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

Microsoft Academic Search

The excess of implantation-induced point defects controls the oxygen redistribution in silicon during a high-temperature treatment, such as in separation-by-implanted-oxygen, and defines the energy-dose window for the formation of a perfect homogeneous and planar buried oxide layer. Quantitative relations are given between the distribution of the initially generated excess defects and the finally formed oxide layer. Implantation-induced defects also explain

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

2008-01-01

281

Low-temperature large-distance asymptotics of the transversal two-point functions of the XXZ chain  

E-print Network

We derive the low-temperature large-distance asymptotics of the transversal two-point functions of the XXZ chain by summing up the asymptotically dominant terms of their expansion into form factors of the quantum transfer matrix. Our asymptotic formulae are numerically efficient and match well with known results for vanishing magnetic field and for short distances and magnetic fields below the saturation field.

Maxime Dugave; Frank Göhmann; Karol K. Kozlowski

2014-01-16

282

A correlation of water solubility in jet fuels with API gravity: aniline point percent aromatics, and temperature.  

E-print Network

A CORRELATION OF WATER SOLUBILITY IN JET FUELS WITH API GRAVITY, ANILINE POINT PERCENT AROMATICS, AND TEMPERATURE A Thesis By ALONZO B YINGTON Submitted to the Graduate College of Texas A&M University in partial fulfillment... mechanisms and adversely affect fuel flow and engine performance. Long range, high altitude flights aggravate the proble~, and the use of micronic filters in fuel lines maximires the danger of plugging from any ice present. The solubility of water...

Byington, Alonzo

2012-06-07

283

Advances in Enhanced Boiling Heat Transfer From Electronic Components  

NASA Astrophysics Data System (ADS)

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

Honda, Hiroshi; Wei, Jinjia

284

Pool boiling on a large horizontal flat resistance heater  

SciTech Connect

Results are presented of experiments on n-pentane/Freon-113 system, carried out to investigate the film-transition boiling region where liquid-solid contacts contribute significantly to the local heat flux, using a large flat horizontal resistance heater mounted on a ceramic insulating substrate. After steady film boiling was reached, the heat flux was decreased and recorded simultaneously with the temperature measured by thermocouples attached to the lower side of the heater surface. It is shown that the observed data on the quasi-linear film boiling regime are better represented by Berenson's (1960) correlation than by Klimenko's (1981) correlation. Burnout values measured for Freon-113 compared reasonably well to available correlations for the flat plate geometry. 10 refs.

Reguillot, F.; Witte, L.; Lienhard, J.; Poniewski, M. (Houston, University, TX (United States) Kielce University of Technology, (Poland))

1992-08-01

285

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

286

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

SciTech Connect

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

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

1993-06-01

287

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

NASA Technical Reports Server (NTRS)

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

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

1984-01-01

288

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

E-print Network

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

289

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

290

Topological order in the phase diagram for high-temperature superconductors with point defects  

Microsoft Academic Search

Applying a Lindemann like criterion obtained previously by Kierfeld et al. [J. Kierfeld, T. Nattermann, T. Hwa, Phys. Rev. B 55 (1997) 626], we estimate the magnetic field and temperature for a high-Tc superconductor, at which a topologically ordered vortex glass phase becomes unstable with respect to a disorder-induced formation of dislocations. The employed criterion is shown to be equivalent

Jan Kierfeld

1998-01-01

291

Boiling heat transfer in compact heat exchangers  

SciTech Connect

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

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

1994-12-31

292

ON THE STABILITY OF BOILING HEAT TRANSFER  

Microsoft Academic Search

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

N. Zuber

1958-01-01

293

Boiling liquid engine cooling system  

Microsoft Academic Search

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

N. Miura; Y. Hayashi

1987-01-01

294

"Sand Boil" on Bay Bridge  

USGS Multimedia Gallery

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

2009-01-26

295

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

296

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

297

Evaluation of correlations of flow boiling heat transfer of R22 in horizontal channels.  

PubMed

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

Zhou, Zhanru; Fang, Xiande; Li, Dingkun

2013-01-01

298

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

299

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

300

Hydrolysis of animall fats by lipase at temperatures below their melting points  

Microsoft Academic Search

Summary We have studied the hydrolysis of high melting animal fats by the lipase fromCandidarugosa at temperatures between 20°C and 37°C without the addition of surfactants or organic solvents. To establish the practical applications of this process we investigated the optimal conditions of the reaction at high substrate concentrations (50% fat w\\/v) to achieve 95% hydrolysis (or better) in 24

Mertxe de Renobales; I. Agud; J. M. Lascaray; J. C. Múgica; L. C. Landeta; R. Solozábal

1992-01-01

301

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

Microsoft Academic Search

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

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

2009-01-01

302

Concentration of native point defects in Si single crystals at high temperatures  

Microsoft Academic Search

The concentration of dominant native defects in a float-zoned Si single crystal at high temperatures was directly determined from the difference between the macroscopic linear thermal expansion and the lattice-parameter thermal expansion. The concentration fraction of native defects in thermal equilibrium at 1300 K is (3.6+\\/-2.7)×10-7, or (1.8+\\/-1.3)×1016 atoms cm-3. It is found that vacancies are predominant over interstitial atoms

Yasumasa Okada

1990-01-01

303

Point defects in optical ceramics - High-temperature absorption processes in lanthana-strengthened yttria  

Microsoft Academic Search

Measurements of the optical transmission characteristics of transparent, polycrystalline, La2O3-strengthened Y2O3, conducted in the near-UV and IR regions at 20-1400 C, indicate that while transmission is low to about 900 C, it thenceforth increases exponentially; the magnitude of this increase is a function of oxygen partial pressure in the ambient atmosphere. Although the temperature dependence is significantly greater in the

Charles Brecher; George C. Wei; William H. Rhodes

1990-01-01

304

Point defects and high-temperature deformation of NiO  

Microsoft Academic Search

The steady-state flow stress tau(sub s) in nonstoichiometric NiO single crystals has been measured in the temperature range of 1428 to 1653 K with oxygen partial pressures p(O2) between 6 and 1 x 10 to the 5th power Pa. Strain rates epsilon were varied from 1 x 10 to the -5 power to 2 x 10 to the -3 power\\/sec.

K. C. Goretta; J. L. Routbort

1985-01-01

305

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

NASA Astrophysics Data System (ADS)

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

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

2012-09-01

306

A universal reduced glass transition temperature for liquids  

NASA Technical Reports Server (NTRS)

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

Fedors, R. F.

1979-01-01

307

A model for correlating flow boiling heat transfer in augmented tubes and compact evaporators  

SciTech Connect

The additive model for the convective and nucleate boiling components originally suggested by Bergles and Rohsenow (1964) for subcooled and low-quality regions was employed in the Kandlikar correlation (1990a) for flow boiling in smooth tubes. It is now extended to augmented tubes and compact evaporators. Two separate factors are introduced in the convective boiling and the nucleate boiling terms to account for the augmentation effects due to the respective mechanisms. The fin efficiency effects in the compact evaporator geometry are included through a reduction in the nucleate boiling component over the fins due to a lower fin surface temperature. The agreement between the model predictions and the data reported in the literature is within the uncertainty bounds of the experimental measurements.

Kandlikar, S.G. (Massachusetts Inst. of Tech., Cambridge (United States))

1991-11-01

308

Temperature and density relaxation close to the liquid-gas critical point: An analytical solution for cylindrical cells  

NASA Astrophysics Data System (ADS)

We present a study of the temperature and density equilibration near the liquid-gas critical point of a composite system consisting of a thin circular disk of near-critical fluid surrounded by a copper wall. This system is a simplified model for a proposed space experiment cell that would have 60 thin fluid layers separated by perforated copper plates to aid in equilibration. Upper and lower relaxation time limits that are based on radial and transverse diffusion through the fluid thickness are shown to be too significantly different for a reasonable estimate of the time required for the space experiment. We therefore have developed the first rigorous analytical solution of the piston effect in two dimensions for a cylindrically symmetric three-dimensional cell, including the finite conductivity of the copper wall. This solution covers the entire time evolution of the system after a boundary temperature step, from the early piston effect through the final diffusive equilibration. The calculation uses a quasistatic approximation for the copper and a Laplace-transform solution to the piston effect equation in the fluid. Laplace inversion is performed numerically. The results not only show that the equilibration is divided into three temporal regimes but also give an estimate of the amplitudes of the remaining temperature and density inhomogeneity in each regime. These results yield characteristic length scales for each of the regimes that are used to estimate the expected relaxation times in the one- and two-phase regions near the critical point.

Carlès, Pierre; Zhong, Fang; Weilert, Mark; Barmatz, M.

2005-04-01

309

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

310

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

SciTech Connect

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

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

1995-02-01

311

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

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

312

Temperature and pressure dependence of the mode Grüneisen parameters close to the melting point in hexagonal ice.  

PubMed

We reexamine the Pippard relations in this study by relating the specific heat CP to the Raman frequency shifts 1/nu (partial differentialnu/partial differentialT) P and the thermal expansivity alphap to the 1/nu (partial differentialnu/partial differentialP) T, when the mode Grüneisen parameter depends on the temperature and pressure close to the melting point in hexagonal ice. From linear relations between them, the values of the slope dP/dT are deduced in this crystal. Our slope values calculated here do not change significantly compared to those obtained when the mode Grüneisen parameter is taken as a constant close to the melting point in hexagonal ice. PMID:16859963

Karacali, H; Yurtseven, H

2007-02-01

313

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

SciTech Connect

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

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

2007-07-01

314

The effects of freezing, boiling and degreasing on the microstructure of bone.  

PubMed

The histology of bone has been a useful tool in research. It is commonly used to estimate the age of an individual at death, to assess if the bone is of human or non-human origin and in trauma analysis. Factors that affect the histology of bone include age, sex, population affinity and burning to name but a few. Other factors expected to affect bone histology are freezing, boiling and degreasing but very little information is available for freezing and the effect thereof, and it is unknown if boiling and degreasing affects bone histology. The aim of this study was to assess the effects of freezing, freezing and boiling, and freezing, boiling and degreasing on the histological structure of compact bone. Five cadaver tibiae were frozen at -20°C for 21 days followed by segments being boiled in water for three days and degreased in trichloroethylene at 82°C for three days. Anterior midshaft sections were prepared as ground sections and for Scanning Electron Microscopy (SEM). Quantitatively, there were no significant differences between freezing, boiling and degreasing; however, qualitative differences were observed using SEM. After being frozen the bone displayed cracks and after boiling the bones displayed erosion pits on the surface. It is suggested that further research, using different durations and temperatures for boiling and freezing be undertaken on bone samples representing different ages and various skeletal elements. PMID:24331160

Lander, S L; Brits, D; Hosie, M

2014-04-01

315

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

316

Ellipsometric study of the temperature dependences of the dielectric function and the critical points of AlSb at temperatures from 300 to 803 K  

NASA Astrophysics Data System (ADS)

We report the complex pseudodielectric function < ? > = < ? 1 > + i < ? 2 > of an oxide-free AlSb film for energies from 0.7 to 5.0 eV and temperatures from 300 to 803 K. The 1.5- ?m-thick film was grown on a (001) GaAs substrate by using molecular beam epitaxy. We maintained the film in an ultrahigh vacuum to prevent oxidation artifacts and used a rotating-compensator ellipsometer to obtain the optical properties. Critical-point (CP) energies were obtained by numerically calculating second energy derivatives of the data. Blue shifts of the CP energies and sharper structures were observed with decreasing temperature. The calculated CP energies were fit to a linear equation.

Park, Han Gyeol; Kim, Tae Jung; Hwang, Soon Yong; Kim, Jun Young; Choi, Junho; Kim, Young Dong; Shin, Sang Hoon; Song, Jin Dong

2014-08-01

317

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

NASA Technical Reports Server (NTRS)

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

Luo, Xiaochun; Schramm, David N.

1993-01-01

318

Subcooled Flow Boiling and Condensation  

Microsoft Academic Search

Fundamental problems in two different flow regimes; subcooled water-steam bubbly condensing flow and subcooled flow boiling, in vertical conduits under low pressure and mass flux conditions, were investigated.\\u000aFor subcooled water-steam condensing bubbly flow, experiments were carried out to obtain a data base for the axial distribution of area-averaged void fraction, interfacial area concentration, interfacial condensation heat transfer and bubble

Obida M. Zeitoun

1994-01-01

319

Subcooled flow boiling and condensation  

Microsoft Academic Search

Fundamental problems in two different flow regimes, subcooled water-steam bubbly condensing flow and subcooled flow boiling, in vertical conduits under low pressure and mass flux conditions, were investigated.^ For subcooled water-steam condensing bubbly flow, experiments were carried out to obtain a database for the axial distribution of area-averaged void fraction, interfacial area concentration, interfacial condensation heat transfer and bubble relative

Obida M Zeitoun

1995-01-01

320

Two-point high repetition rate measurement of temperature and thermal dissipation in a turbulent non-premixed jet flame  

NASA Astrophysics Data System (ADS)

A high-repetition rate (10 kHz) laser Rayleigh scattering facility was developed and used to study the temperature fluctuations, power spectra, gradients and thermal dissipation rate characteristics of a nonpremixed turbulent jet flame at a Reynolds number of 15,200. The flame studied here is similar to the Turbulent Nonpremixed Flame Workshop simple jet flame (DLR_A flame). The radial temperature gradient was measured by a two-point technique, whereas the axial gradient was inferred from temperature time-series measurements combined with Taylor's hypothesis. Resolution and noise can greatly affect such measurements, and thus a model is proposed to account for the effects of resolution, noise, filtering and data processing on the measured dissipation. The model clearly shows the interplay between resolution and noise, and that noise will create an apparent dissipation (or bias), which will be more significant at high spatial resolution. Techniques to correct the measured mean dissipation for this bias are discussed for the two-point time-series thermal dissipation measurements reported here. A general technique to estimate the noise level for scalar dissipation measurements is also proposed. The resulting two-point time-resolved measurements in a turbulent flame show that the temperature power spectra along the jet centerline exhibit only a small inertial subrange due to the low local Reynolds number of the flow (Redelta ˜ 2,500), although a larger inertial subrange is present in the spectra at offcenterline locations. Furthermore, the power spectra collapse in the dissipation range when the frequencies are normalized by the Batchelor frequency. Probability density functions of the thermal dissipation are shown to deviate from lognormal in the low-dissipation portion of the distribution when only one component of the gradient is used; however, nearly lognormal distributions are obtained along the centerline when both axial and radial components are included. A procedure is developed for correcting the thermal dissipation for the apparent dissipation introduced by noise. This procedure uses redundant measurements, either temporally or spatially, to quantify the noise contribution on the mean dissipation. This analysis shows that noise has a dominating effect on the dissipation as the apparent dissipation can be as large as five times the actual dissipation on centerline. The corrected dissipation measurements show that the radial profile of the mean thermal dissipation exhibits a peak off centerline at all downstream locations. These results indicate that the underlying turbulence, as inferred from the temperature fluctuations, is in large part similar to that of nonreacting jet flows, provided the Reynolds number is properly modified to account for heat release.

Wang, Guanghua

321

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

NASA Astrophysics Data System (ADS)

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 Al2O3 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.; Escobedo-Cousin, E.; King, P. J.; Wright, N. G.; O'Neill, A. G.; Horsfall, A. B.; Goss, J. P.; Wells, G. H.; Hunt, M. R. C.

2014-10-01

322

Heat transfer in pool boiling of ammonia\\/water mixture  

Microsoft Academic Search

.   \\u000a The nonazeotropic binary mixtures such as, methanol\\/water, ethanol\\/water and ammonia\\/water, have variable boiling and dew\\u000a points, depending on the combination of substance and those mass fraction. It is expected to have a higher performance as\\u000a a result of decreasing the thermodynamically irreversible loss, when there is a relevant mass fraction. Therefore, ammonia\\/water\\u000a mixture is expected to use as

Hirofumi Arima; Masanori Monde; Yuhichi Mitsutake

2003-01-01

323

Correlations of velocity and temperature fluctuations in the stagnation-point flow of circular cylinder in turbulent flow  

NASA Technical Reports Server (NTRS)

Boundary layer flow and turbulence transport analyses to study the influence of the free-stream turbulence on the surface heat transfer rate and the skin friction around the stagnation point of a circular cylinder in a turbulent flow are presented. The analyses are formulated with the turbulent boundary layer equations, the Reynolds stress transport equations and the k - epsilon two-equation turbulence modeling. The analyses are used to calculate the time-averaged turbulence double correlations, the mean flow properties, the surface heat transfer rate and the skin friction with an isotropic turbulence in the freestream. The analytical results are described and compared with the existing experimental measurements. Depending on the free-stream turbulence properties, the turbulence kinetic energy can increase or decrease as the flow moves toward the surface. However, the turbulence kinetic energy induces large Reynolds normal stresses at the boundary layer edge. The Reynolds normal stresses change the boundary layer profiles of the time-averaged double correlations of the velocity and temperature fluctuations, the surface heat transfer rate and the skin friction. The free-stream turbulence dissipation rate can affect the stagnation-point heat transfer rate but the influence of the free-stream temperature fluctuation on the heat transfer rate is insignificant.

Wang, Chi R.

1988-01-01

324

Simulation of low-power, low-flow sodium boiling with a transparent, atmospheric pressure water loop  

SciTech Connect

Experiments have been performed in a transparent, single-tube boiling loop, using water as the working fluid, to simulate sodium boiling behavior in a similar geometry. Testing has been performed over a wide range of flows, powers, and temperatures to examine the onset of boiling, flow regimes, oscillatory flow behavior, and dryout. Analysis of experimental data has been aided by the use of high-speed motion pictures. Instrument data from selected tests are presented and discussed, as well as results from computer simulations of the experiments. The computer model is presented, and scaling laws for the comparison of water and sodium oscillatory boiling are discussed. Comparison of the data from this loop with sodium boiling data has shown that an atmospheric pressure, two-phase water system is a good simulant for boiling liquid sodium. 11 refs., 91 figs., 2 tabs.

Levin, A.E.; Montgomery, B.H.; Carbajo, J.J.; Wantland, J.L.

1984-03-01

325

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

326

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/so 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/so 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

327

Modeling acid-gas generation from boiling chloride brines  

PubMed Central

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

2009-01-01

328

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

329

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

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

330

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

331

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

E-print Network

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

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

2007-02-01

332

Effect of bubble frequency on bubble departure diameter in nucleate pool boiling  

SciTech Connect

A remarkably high heat flux can be obtained with a heat source of small temperature difference by generating a small amount of electrolytic hydrogen gas from a heating surface under nucleate boiling conditions. In order to elucidate the mechanisms involved in such a system and also in heat transfer in ordinary nucleate boiling, the diameter of escaping vapor bubble at the time of nucleate boiling under reduced pressure was investigated theoretically and experimentally. It was determined that an analytical model which considered the frequency of vapor bubble generation was able to explain relatively well the experimental values.

Nakayama, A.; Kano, M.

1983-07-01

333

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

NASA Astrophysics Data System (ADS)

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

Hanseth, E. J.

1981-12-01

334

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

NASA Technical Reports Server (NTRS)

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

Hanseth, E. J.

1981-01-01

335

CONVECTIVE HEAT TRANSFER OF BINARY MIXTURES UNDER FLOW BOILING CONDITIONS  

E-print Network

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

Kandlikar, Satish

336

A literature survey on available correlations for prediction of nucleate pool boiling heat transfer  

SciTech Connect

The nucleate pool boiling process is inherently a complex phenomenon. This complexity is in part related to the random behavior of the bubbles near the heating surface, strong property related boiling mechanism and other parameters such as the nucleation site density, bubble growth rates, bubble dimensions, and bubble rise velocity. To date no comprehensive model or correlation exists that can collectively represent all the characteristics of nucleate boiling. Most of the efforts for modeling the nucleate pool boiling phenomena invariably necessitate a fundamental knowledge of bubble frequency, bubble departure diameter, and nucleation site density. Due to irreproducibility of the boiling phenomena, it is very difficult to present these aspects by a general equation using parameters such as working fluid property or surface condition. From an engineering point of view, the demands are for practicality of a correlation while providing satisfactory accuracy. The objective of this paper is to provide a critical survey of the available design correlations on nucleate pool boiling heat transfer. The paper is given in two parts. Discussion of the most commonly known general correlations for nucleate pool boiling is given in part 1. In part 2 correlations with special use will be presented and discussed. Results for independent testing of selected correlations are also given in part 2.

Salehi, M.; Ohadi, M.M.; Blanford, M.; Dessiatoun, S.V. [Univ. of Maryland, College Park, MD (United States)

1996-12-31

337

Pool boiling on nano-finned surfaces  

E-print Network

to the surface of the liquid pool. Thus, there is a constant pumping action which is the principle of operation of these “ virtual thermosyphons” [4]. The advantage of pool boiling over flow boiling systems is that no external pumping source is required... to the surface of the liquid pool. Thus, there is a constant pumping action which is the principle of operation of these “ virtual thermosyphons” [4]. The advantage of pool boiling over flow boiling systems is that no external pumping source is required...

Sriraman, Sharan Ram

2008-10-10

338

Pool boiling on nano-finned surfaces  

E-print Network

to the surface of the liquid pool. Thus, there is a constant pumping action which is the principle of operation of these ? virtual thermosyphons? [4]. The advantage of pool boiling over flow boiling systems is that no external pumping source is required... to the surface of the liquid pool. Thus, there is a constant pumping action which is the principle of operation of these ? virtual thermosyphons? [4]. The advantage of pool boiling over flow boiling systems is that no external pumping source is required...

Sriraman, Sharan Ram

2009-05-15

339

Nucleate pool-boiling heat transfer. I: review of parametric effects of boiling surface  

Microsoft Academic Search

The objective of this paper is to assess the state-of-the-art of heat transfer in nucleate pool-boiling. Therefore, the paper consists of two parts: part I reviews and examines the effects of major boiling surface parameters affecting nucleate-boiling heat transfer, and part II reviews and examines the existing prediction methods to calculate the nucleate pool-boiling heat transfer coefficient (HTC).A literature review

I. L. Pioro; W. Rohsenow; S. S. Doerffer

2004-01-01

340

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

341

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

342

Dew Point  

NSDL National Science Digital Library

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

Consortium, The C.

2011-12-13

343

Induction heating pure vapor source of high temperature melting point materials on electron cyclotron resonance ion source.  

PubMed

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(-4)-10(-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. PMID:20192343

Kutsumi, Osamu; Kato, Yushi; Matsui, Yuuki; Kitagawa, Atsushi; Muramatsu, Masayuki; Uchida, Takashi; Yoshida, Yoshikazu; Sato, Fuminobu; Iida, Toshiyuki

2010-02-01

344

Indo-Pacific warm pool area expansion, Modoki activity, and tropical cold-point tropopause temperature variations.  

PubMed

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

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

2014-01-01

345

Nucleate boiling characteristics of R-113 in a small tube bundle  

SciTech Connect

Heat transfer measurements were made during nucleate boiling of R-113 from a bundle of 15 electrically heated, smooth copper tubes arranged in an equilateral triangular pitch. The bundle was designed to simulate a portion of a refrigeration system flooded-tube evaporator. The outside diameter of the tubes was 15.9 mm, and the tube pitch was 19.1 mm. Five of the tubes that were oriented in a vertical array on the centerline of the bundle were each instrumented with six wall thermocouples to obtain an average wall temperature and a resultant average heat transfer coefficient. All tests were performed at atmospheric pressure. The majority of the data were obtained with increasing heat flux to study the onset of nucleate boiling and the influence of surface history upon boiling heat transfer. Data taken during increasing heat flux showed that incipient boiling was dependent upon the number of tubes in operation. The operation of lower tubes in the bundle decreased the incipient boiling heat flux and wall superheat of the upper tubes, and generally increased the boiling heat transfer coefficients of the upper tubes at low heat fluxes where natural convection effects are important. The boiling data confirmed that the average heat transfer coefficient for a smooth-tube bundle is larger than obtained for a single tube.

Marto, P.J.; Anderson, C.L. (Naval Postgraduate School, Monterey, CA (United States))

1992-05-01

346

Solubility of Fullerene C60 and C70 in Toluene, o-Xylene and Carbon Disulfide at Various Temperatures  

Microsoft Academic Search

The solubilities of fullerene C60 and C70 in toluene, o-xylene and carbon disulfide between the melting point and boiling point of the solvents, respectively, have been measured. The temperature dependent solubility of C60 displays anomalous behaviors. A solubility maximum of C60 around 0 °C for toluene and carbon sulfide and around 30 °C for o-xylene was observed. The temperature-dependent solubility

Xflroang Zhou; Jianben Liu; Zhaoxia Jin; Zhennan Gu; Yongqing Wu; Yiliang Sun

1997-01-01

347

Temperature-dependent thermal conductivities of 1D semiconducting nanowires via four-point-probe 3-? method  

NASA Astrophysics Data System (ADS)

We report on a systematic study of the thermal transport characteristics of both as-grown zinc oxide and gallium nitride nanowires (NWs) via the four-point-probe 3-? method in the temperature range 130-300 K. Both as-grown NWs were synthesized by a vapor-liquid-solid growth mechanism, and show clear n-type semiconducting behavior without any defects, which enables both the NWs to be promising candidates for thermoelectric materials. To measure the thermal conductivities of both NWs with lower heat loss and measurement errors, the suspended structures were formed by a combination of an e-beam lithography process and a random dispersion method. The measured thermal conductivities of both NWs are greatly reduced compared to their bulk materials due to the enhanced phonon scattering via the size effect and dopants (impurities). Furthermore, we observed that the Umklapp peaks of both NWs are shifted to a higher temperature than those of their bulk counterparts, indicating that phonon-boundary scattering dominates over other phonon scattering due to the size effect.

Lee, Seung-Yong; Lee, Mi-Ri; Park, No-Won; Kim, Gil-Sung; Choi, Heon-Jin; Choi, Tae-Youl; Lee, Sang-Kwon

2013-12-01

348

Stability of active systems with a spatially periodic activity: Analysis of a simple model and application to the boiling crisis problem.  

PubMed

We investigate theoretically the possibility to control the transition between two metastable states in reactive systems by imposing a spatial modulation. In particular, we consider the technologically very important case of the transition between the low temperature (nucleate boiling) and the high temperature (film boiling) phases of boiling of a liquid over a heat generating element, also known as the boiling crisis. With the help of a simplified model, we demonstrate that the dangerous regime where the high temperature phase invades the whole system requires a larger heat power in a periodically spatially modulated system, than in a uniform system. The possibility that a local perturbation, such as a small gas bubble, may induce locally a transition to the film boiling state is also considered. We show that the transition to the film boiling regime is hindered in a spatially periodic system. (c) 2002 American Institute of Physics. PMID:12779590

Pumir, Alain; Barelko, Viktor V.

2002-09-01

349

21 CFR 872.6710 - Boiling water sterilizer.  

Code of Federal Regulations, 2011 CFR

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

2011-04-01

350

21 CFR 872.6710 - Boiling water sterilizer.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Boiling water sterilizer. 872.6710 Section... Miscellaneous Devices § 872.6710 Boiling water sterilizer. (a) Identification. A boiling water sterilizer is an AC-powered...

2010-04-01

351

Apparatus for pumping liquids at or below the boiling point  

DOEpatents

A pump comprises a housing having an inlet and an outlet. An impeller assembly mounted for rotation within the housing includes a first impeller piece having a first mating surface thereon and a second impeller piece having a second mating surface therein. The second mating surface of the second impeller piece includes at least one groove therein so that at least one flow channel is defined between the groove and the first mating surface of the first impeller piece. A drive system operatively associated with the impeller assembly rotates the impeller assembly within the housing.

Bingham, Dennis N. (Idaho Falls, ID)

2002-01-01

352

0-7803-XXXX-X/06/$20.00 2009 IEEE 25th IEEE SEMI-THERM Symposium Sub-Atmospheric Pressure Pool Boiling of Water on a Screen Laminate-Enhanced Extended  

E-print Network

Boiling of Water on a Screen Laminate-Enhanced Extended Surface Paul Laca and R. A. Wirtz Dept. of Mechanical Engineering/MS 312 University of Nevada Reno Reno, NV 89557 Abstract Pool boiling experiments temperature for water at pressures of 0.2, 0.3, 0.5 and 1.0 atm. Boiling performance of a vertical

Wirtz, Richard A.

353

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

354

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

355

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

356

Nanofluid boiling: The effect of surface wettability  

Microsoft Academic Search

Nanofluid boiling has shown potential to increase boiling heat transfer, but the mechanisms responsible are poorly understood. One likely mechanism for nanofluid enhancement is an improvement in surface wettability. This study is targeted towards investigating whether or not nanofluids improve the critical heat flux (CHF) by altering the surface energy as has been observed for pure fluids. The surface of

Johnathan S. Coursey; Jungho Kim

2008-01-01

357

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

PubMed Central

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

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

2013-01-01

358

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

359

Pool boiling heat transfer on thin wire in nitrogen-tetrafluoromethane mixtures  

SciTech Connect

Nucleate and film pool boiling heat transfer, critical heat fluxes, and minimum heat fluxes for nitrogen, tetrafluoromethane, and their mixtures were measured on a thin wire. The orientation of the wire was either horizontal or vertical. Critical heat fluxes and minimum heat fluxes for the mixtures in any concentration were larger than those for liquid nitrogen. The heat flux in nucleate boiling regimes for mixtures was represented well by an experimental formula. For a single-component liquid, transition from nucleate boiling to film boiling was observed for a stepwise heat input and rapid heating. It was found that there was no such transition for mixtures in contrast to the pure component. The nitrogen-tetrafluoromethane mixtures are recommended for use as cryogens of oxide superconductors having critical temperature higher than 110 K.

Amano, Toshiyuki

1993-09-01

360

Communication: High speed optical investigations of a character of boiling-up onset.  

PubMed

In this communication, we discuss the phenomenon of attainable superheat of liquid and the peculiarities of its release by spontaneous boiling-up. We have combined the apparatus for superheating, namely, bubble chamber, with a high speed micro-optical method for detailed monitoring of the initial stage of boiling-up. In experiments on the isothermal pressure drop, it was found that the boiling-up onset of n-hexane is accompanied by characteristic step signal. The signal has proved to be typical of the heterogeneous character of boiling-up onset in a whole range of superheating degrees. The performance of the method for investigation of the refractive index and density for superheated liquids as functions of temperature and pressure has been revealed. The experimental error is estimated to be 0.1%. PMID:22260557

Gurashkin, A L; Starostin, A A; Ermakov, G V; Skripov, P V

2012-01-14

361

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

362

Tipping Points  

Microsoft Academic Search

A climate tipping point, at least as I have used the phrase, refers to a situation in which a changing climate forcing has reached a point such that little additional forcing (or global temperature change) is needed to cause large, relatively rapid, climate change. Present examples include potential loss of all Arctic sea ice and instability of the West Antarctic

J. Hansen

2007-01-01

363

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

364

Heat transfer 1982; Proceedings of the Seventh International Conference, Technische Universitaet Muenchen, Munich, West Germany, September 6-10, 1982. Volume 4 - General papers: Pool boiling, flow boiling, measuring techniques  

NASA Astrophysics Data System (ADS)

Papers are presented on nucleate pool boiling in a microgravity environment; the influence of diameter on nucleate boiling outside tubes; burnout during flow across a small cylinder influenced by parallel cylinders; and the application of the swollen polymer technique to the study of heat transfer on film-cooled surfaces. Other topics include homogeneous nucleation in transient boiling; the heat transfer characteristics of the two-phase closed thermosyphon (wickless heat pipe); boiling heat transfer in annular flow; and the effect of rod bundle geometry (even-odd) on burnout. Attention is also given to wall temperature fluctuation of the evaporating tube at the dryout region, to the flow boiling of ethanol/cyclohexane mixtures, and to capillary flows around hemispherical bubbles. For individual items see A83-42758 to A83-42781

Grigull, U.; Straub, J.; Hahne, E.; Stephan, K.

365

Characteristics of nucleate pool boiling from porous metallic coatings  

Microsoft Academic Search

A study of pool boiling from a commercial porous metallic matrix surface is reported. The excellent steady boiling characteristics of this type of surface are confirmed; however, high wall superheats are required in most cases to initate boiling. The resultant boiling curve hysteresis does not appear to have been previously reported in the literature. This effect is indicated in recent

A. E. Bergles; M. C. Chyu

1982-01-01

366

Nucleate pool boiling enhancement by means of surfactant additives  

Microsoft Academic Search

While certain surfactant additives are well known to significantly enhance boiling heat transfer, the enhancement mechanism is still not so clear for the present. In order that more conclusive information of fundamental boiling phenomena in surfactant solutions can be collected, surfactant effects on interfacial properties at gas\\/liquid interface, nucleate boiling heat transfer, boiling incipience, and single vapor bubble growth dynamics

Wuu-Tsann Wu; Yu-Min Yang; Jer-Ru Maa

1998-01-01

367

A Study of Nucleate Boiling with Forced Convection in Microgravity  

NASA Technical Reports Server (NTRS)

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

Merte, Herman, Jr.

1996-01-01

368

High-temperature variable melting point Sn-Sb lead-free solder pastes using transient liquid-phase powder processing  

Microsoft Academic Search

During this investigation, a high-temperature, variable melting point (VMP) Sn-Sb solder paste was developed. The solder was\\u000a created by mixing pure Sn and Sb powders together with a flux to form a paste. The proper choice of flux composition and Sn\\u000a powder size resulted in a Sn-10wt.%Sb solder paste that had an initial melting point of 232C and solder ball

S. F. Corbin

2005-01-01

369

Nuclear fuel performance in boiling water reactors  

SciTech Connect

A major development program is described to improve the performance of Boiling Water Reactor fuel. This sustained program is described in four parts: 1) performance monitoring, 2) fuel design changes, 3) plant operating recommendations, and 4) advanced fuel programs.

Elkins, R.B.; Baily, W.E.; Proebstle, R.A.; Armijo, J.S.; Klepfer, H.H.

1981-08-01

370

Why Is NASA Boiling Fluids in Space?  

NASA Video Gallery

Convection and buoyancy work differently in space than on Earth. Learn how NASA uses this information and applies it to everyday life. Boiling fluids in space is easier than it is on Earth. Learn m...

371

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

372

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

373

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

374

Numerical modeling of a nucleate boiling surface  

SciTech Connect

A computer program developed to analyze nucleate boiling over a heated surface is described. The model solves the three-dimensional transient conduction equation within the heater. The conduction solution is coupled with closure relationships to mimic the bubble dynamics and the associated heat transfer coefficients. Sample problems are run using a copper surface subject to partial nucleate boiling in saturated water at atmospheric pressure. The results are shown to be in good qualitative agreement with the pertinent experimental observations.

Pasamehmetoglu, K.O. (Los Alamos National Lab., NM (United States). Nuclear Technology and Engineering Division)

1994-06-01

375

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

E-print Network

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

376

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

NASA Technical Reports Server (NTRS)

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

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

1998-01-01

377

Enhancement of nucleate pool boiling heat transfer to dilute binary mixtures using endothermic chemical reactions around the smoothed horizontal cylinder  

NASA Astrophysics Data System (ADS)

Experimental studies on enhancing the pool boiling heat transfer coefficient of binary dilute mixtures of water/glycerol, water/MEG (Mono-ethylene glycol) and water/DEG (di-ethylene glycol) have been carried out. Some particular endothermic chemical reactions related to ammonium salts were used to enhance the pool boiling heat transfer coefficient, simultaneously with occurrence of pool boiling heat transfer. Accordingly, 100 g of Ammonium nitrate, ammonium perborate and Ammonium sulfate were selected to dissolve into mixtures. High and extreme solution enthalpies of each of these ammonium salt powders are employed to reduce the surface temperature around the horizontal cylinder locally. Results demonstrated that presence of ammonium salts into the mixtures deteriorates the surface temperature of cylinder and as the result, higher pool boiling heat transfer coefficient is reported for tested solutions. Results are also reported and compared for different ammonium salts to find the influence of inducing different enthalpies of solution on pool boiling heat transfer coefficient. Obtained results also indicated that presence of endothermic reaction besides the pool boiling heat transfer enhances the heat transfer coefficients in comparison with nucleate pool boiling phenomenon solely.

Sarafraz, M. M.; Peyghambarzadeh, S. M.; Alavifazel, S. A.

2012-10-01

378

Experimental investigation of tube length effect on nucleate pool boiling heat transfer  

Microsoft Academic Search

The effect of a vertically installed tube length on the nucleate pool boiling heat transfer coefficient under atmospheric pressure has been empirically obtained using various combination of major parameters for application to advanced light water reactor design. The experimental data for q? versus ?T test are counted as 1,063 points and can cover the extent of D = 9.7 ?

Myeong-Gie Kang

1998-01-01

379

Study of the influence of the nonequilibrium point defect concentration gradient on the dopant flux during ion implantation in silicon at high temperatures  

Microsoft Academic Search

A relationship in a closed form for a dopant flux in silicon in the presence of the nonequilibrium point-defect concentration and its gradient is derived from the first principles on the basis of solving a simplified boundary value problem. The experimental dopant atom distributions (profiles) obtained after ion implantation of B and P into Si at high temperatures are treated

V. I. Kol'dyaev

1995-01-01

380

The effect of surface gas injection on film boiling heat transfer  

SciTech Connect

A database was developed for heat transfer from a horizontal 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. At the highest superficial gas velocity measured, approximately 8.5 cm/s, and for a constant surface temperature, the heat transfer increases by a factor of two over the heat transfer with no enhancement by gas flux. Further, as the superficial gas velocity approached zero, the data approach the stable film boiling asymptote. A semi-empirical model was developed and correlated to the database. The result is an equation which represents better than 90% of all the measured data within {plus_minus}15% bounds.

Duignan, M.R. [Westinghouse Savannah River Co., Aiken, SC (United States); Greene, G.A. [Brookhaven National Lab., Upton, NY (United States); Irvine, T.F. Jr. [State Univ. of New York, Stony Brook, NY (United States)

1991-12-31

381

The effect of surface gas injection on film boiling heat transfer  

SciTech Connect

A database was developed for heat transfer from a horizontal 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. At the highest superficial gas velocity measured, approximately 8.5 cm/s, and for a constant surface temperature, the heat transfer increases by a factor of two over the heat transfer with no enhancement by gas flux. Further, as the superficial gas velocity approached zero, the data approach the stable film boiling asymptote. A semi-empirical model was developed and correlated to the database. The result is an equation which represents better than 90% of all the measured data within {plus minus}15% bounds.

Duignan, M.R. (Westinghouse Savannah River Co., Aiken, SC (United States)); Greene, G.A. (Brookhaven National Lab., Upton, NY (United States)); Irvine, T.F. Jr. (State Univ. of New York, Stony Brook, NY (United States))

1991-01-01

382

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

383

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

NASA Astrophysics Data System (ADS)

Dy-Ba-Cu-O bulk superconductor has an excellent capability of trapping magnetic flux and lower heat conductivity at cryogenic temperatures as compared with Y-Ba-Cu-O bulk superconductor. The Young's modulus and the bending strength in the range from room temperature to 7 K were measured by the three-point bending tests using specimens cut from a melt-processed Dy-Ba-Cu-O bulk superconductor. They were tested in a helium gas flow type cryostat at Forschungszentrum Karlsruhe and in a liquid nitrogen bath at Iwate University. The Young's modulus was calculated by either the slope of stress-strain curve or that of the load-deflection curve of the specimen. Although the bending strength measured in the two institutes coincided well, there was a significant discrepancy in the Young's modulus. The Young's modulus and bending strength increased with decrease of temperature down to 7 K. The amount of increase in the Young's modulus and the bending strength were about 32% and 36% of those at room temperature, respectively. The scatter of data for each run was significant and did not depend on temperature. The temperature dependence of the Young's modulus coincided with that in Y-Ba-Cu-O obtained by ultrasonic velocity. The temperature dependence of the Young's modulus and the bending strength was discussed from the view point of interatomic distance of the bulk crystal.

Katagiri, K.; Nyilas, A.; Sato, T.; Hatakeyama, Y.; Hokari, T.; Teshima, H.; Iwamoto, A.; Mito, T.

2006-07-01

384

Tipping Points  

NASA Astrophysics Data System (ADS)

A climate tipping point, at least as I have used the phrase, refers to a situation in which a changing climate forcing has reached a point such that little additional forcing (or global temperature change) is needed to cause large, relatively rapid, climate change. Present examples include potential loss of all Arctic sea ice and instability of the West Antarctic and Greenland ice sheets. Tipping points are characterized by ready feedbacks that amplify the effect of forcings. The notion that these may be runaway feedbacks is a misconception. However, present "unrealized" global warming, due to the climate system's thermal inertia, exacerbates the difficulty of avoiding global warming tipping points. I argue that prompt efforts to slow CO2 emissions and absolutely reduce non-CO2 forcings are both essential if we are to avoid tipping points that would be disastrous for humanity and creation, the planet as civilization knows it.

Hansen, J.

2007-12-01

385

Pool boiling on a single-crystal sapphire surface -- A measuring method of quantities upon liquid-solid contacts  

SciTech Connect

In this study, a novel method for measuring the fundamental quantities upon liquid-solid contact in pool boiling is developed to obtain a better understanding of the mechanism of high-heat-flux nucleate boiling, the critical heat flux (CHF) point and transition boiling. The method consists of dynamic observations of liquid-solid contact and an image-processing technique. The liquid-solid contact situation was observed from below the heat-transfer surface and by a high-speed video camera. A single-crystal sapphire plate was chosen as the heat-transfer surface because of its high transparency and good thermal diffusivity. In dry areas on the surface, total reflections would occur, but not in wetted areas. Therefore, the authors could clearly distinguish between dry and wetted areas on the surface. Then, using an image-processing technique, the fundamental quantities on liquid-solid contact in pool boiling, as listed below, were obtained as a function of wall superheats: (i) the wetted-area fraction, (ii) nucleation-site density (the number density of dry areas), and (iii) the size and time scales of the fundamental macroscopic structure in boiling. These quantities may serve as important information to establish the physical models of nucleate boiling, CHF, and transition boiling.

Nagai, Niroh; Nishio, Shigefumi

1995-12-31

386

Nonlinear aspects of high heat flux nucleate boiling heat transfer  

SciTech Connect

This paper deals with potential nonlinear effects in nucleate boiling systems as a result of the behavior of individual nucleation sites on the heater surface. This requires detailed microscopic modeling of the surface. A computational model has been formulated for this purpose. The model addresses the three-dimensional transient conduction heat transfer process within the problem domain comprised of the macrolayer and heater. Hydrodynamic effects are represented through boundary conditions. Individual nucleation sites are activated or deactivated depending on the thermal conditions that prevail at the site. The model has been used to examine the behavior of sites on a realistic heater surface. The results indicate that significant spatial and temporal temperature variations can occur on the surface, and that thermal interactions among sites can result in some sites operating intermittently. Surface-averaged temperatures show nonlinear period-doubling behavior. A chaotic case was found. Qualitative comparisons are made to both local instantaneous temperature measurements and recent experiments that showed chaotic behavior. We believe that such nonlinear behavior is one of the reasons that mechanistic predictive capabilities for the boiling process have remained elusive. 29 refs., 8 figs., 2 tabs.

Sadasivan, P.; Unal, C.; Nelson, R. [Los Alamos National Lab., NM (United States)

1995-11-01

387

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

388

Algorithms to Estimate the Temperature and Effective Irradiance Level over a Photovoltaic Module using the Fixed Point Theorem  

Microsoft Academic Search

The purpose of this paper is to present four algorithms to calculate the effective irradiance level, Ei and temperature, T, of operation for a photovoltaic module, PVM. The main reasons to develop these algorithms are for monitoring climate conditions, the elimination of temperature and solar irradiance sensors, reductions in cost for a photovoltaic inverter system, and development of new algorithms

Eduardo I. Ortiz Rivera; F. Z. Peng

2006-01-01

389

The influence of oil on nucleate pool boiling heat transfer  

NASA Astrophysics Data System (ADS)

The influence of various oil contents in R134a is investigated for nucleate pool boiling on copper tubes either sandblasted or with enhanced heating surfaces (GEWA-B tube). Polyolester oils (POE) (Reniso Triton) with medium viscosity 55 cSt (SE55) and high viscosity 170 cSt (SE170) were used. Heat transfer coefficients were obtained for boiling temperatures between -28.6 and +20.1°C. The oil content varied from 0 to 5% mass fraction. For the sandblasted tube and the SE55 oil the heat transfer coefficients for the refrigerant/oil-mixture can be higher or lower than those for the pure refrigerant, depending on oil mass fraction, boiling temperature and heat flux. In some cases the highest heat transfer coefficients were obtained at a mass fraction of 3%. For the 170 cSt oil there is a clear decrease in heat transfer for all variations except for a heat flux 4,000 W/m2 and -10.1°C at 0.5% oil content. The heat transfer coefficients are compared to those in the literature for a smooth stainless steel tube and a platinum wire. For the enhanced tube and 55 cSt oil the heat transfer coefficients are clearly below those for pure refrigerant in all cases. The experimental results for the sandblasted tube are compared with the correlation by Jensen and Jackman. The calculated values are within +20 and -40% for the medium viscosity oil and between +50% and -40% for the high viscosity oil. A correlation for predicting oil-degradation effects on enhanced surfaces does not exist.

Spindler, Klaus; Hahne, Erich

2009-05-01

390

Curie Point  

NSDL National Science Digital Library

In this activity best suited as a demonstration, learners observe that when a piece of iron gets too hot, it loses its ability to be magnetized. The temperature at which this occurs is known as the Curie Point. This simple set-up involving a lantern battery and Tinkertoys⢠demonstrates this phenomenon. Adult supervision required, as the wire will get hot in this activity.

Exploratorium, The

2012-01-30

391

The influence of bubble evolution on the early characteristics of the boiling liquid expanding vapor explosion  

NASA Astrophysics Data System (ADS)

In the study of boiling liquid expanding vapor explosion (BLEVE), the critical point to interpret the mechanism of the disaster is to analyze the phase transition of the superheated liquid in the container and the motions of the medium during the first several or several tens of milliseconds after the explosion from the microscopic angle of view. In the study recorded in this paper, a BLEVE simulative device was made. Using high-speed camera, the instant explosive boiling in the liquor phase space and the formation and development of the high speed two-phase flow were observed at the moment of the container broken in explosion, the growing and moving speed of the bubble in the liquor phase space were measured, and the influence of the energy released by blasted bubble nucleate in the early stages on the boiling characteristics of the superheated liquid and the overpressure disciplines in the container were analyzed. The study shows that in a BLEVE process, the boiling of superheated liquid does not present in the form of volume boiling, but presents as a progressive process with several steps that starts from the surface and develops over time.

Chen, Sining; He, Xuechao; Sun, Jinhua

2008-11-01

392

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

NASA Astrophysics Data System (ADS)

Degassing of CO2 on the flanks of the active Erebus volcano is thought to occur mainly through fumarolic ice caves (FIC) and associated fumarolic ice towers. There is also minor CO2 degassing from isolated areas of warm ground. The mechanism supplying heat and CO2 gas into the FIC is poorly understood. To investigate this system, a fiber optic distributed temperature sensing (DTS) system was deployed in a FIC to obtain temperature measurements every meter. The DTS data reveal that localized gas vents (GV) supply heat to the FIC air mass and are an important component of the FIC microclimate. FIC temperature is anti-correlated with local atmospheric pressure, indicating barometric pumping of the GV. These results enable the use of FIC temperature as a proxy for flank degassing rate on Erebus, and represent the first application of DTS for monitoring an active volcano.

Curtis, Aaron; Kyle, Philip

2011-08-01

393

Enhanced Boiling on Micro-Configured Composite Surfaces Under Microgravity Conditions  

NASA Technical Reports Server (NTRS)

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

Zhang, Nengli; Chai, An-Ti

1999-01-01

394

Boiling as Household Water Treatment in Cambodia: A Longitudinal Study of Boiling Practice and Microbiological Effectiveness  

PubMed Central

This paper focuses on the consistency of use and microbiological effectiveness of boiling as it is practiced in one study site in peri-urban Cambodia. We followed 60 randomly selected households in Kandal Province over 6 months to collect longitudinal data on water boiling practices and effectiveness in reducing Escherichia coli in household drinking water. Despite > 90% of households reporting that they used boiling as a means of drinking water treatment, an average of only 31% of households had boiled water on hand at follow-up visits, suggesting that actual use may be lower than self-reported use. We collected 369 matched untreated and boiled water samples. Mean reduction of E. coli was 98.5%; 162 samples (44%) of boiled samples were free of E. coli (< 1 colony-forming unit [cfu]/100 mL), and 270 samples (73%) had < 10 cfu/100 mL. Storing boiled water in a covered container was associated with safer product water than storage in an uncovered container. PMID:22826487

Brown, Joseph; Sobsey, Mark D.

2012-01-01

395

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

NASA Technical Reports Server (NTRS)

Coherent anti-Stokes Raman scattering (CARS) from the pure rotational Raman lines of N2 is employed to measure the instantaneous (approximately 10 ns) rotational temperature of N2 gas at room temperature and below with good spatial resolution (0.2 x 0.2 x 3.0 cu mm). A broad bandwidth dye laser is used to obtain the entire rotational spectrum from a single laser pulse; the CARS signal is then dispersed by a spectrograph and recorded on an optical multichannel analyzer. A best fit temperature is found in several seconds with the aid of a computer for each experimental spectrum by a least squares comparison with calculated spectra. The model used to calculate the theoretical spectra incorporates the temperature and pressure dependence of the pressure-broadened rotational Raman lines, includes the nonresonant background susceptibility, and assumes that the pump laser has a finite linewidth. Temperatures are fit to experimental spectra recorded over the temperature range of 135 to 296 K, and over the pressure range of .13 to 15.3 atm.

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

1983-01-01

396

6. View of first panel point from south end showing ...  

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

6. View of first panel point from south end showing chord, diagonals and vertical member connection at pin - Bridge No. 2.4, Spanning Boiling Fork Creek at Railroad Milepost JC-2.4, Decherd, Franklin County, TN

397

Marangoni effects on near-bubble microscale transport during boiling of binary fluid mixtures  

NASA Astrophysics Data System (ADS)

In this study, boiling experiments of 2-propanol/water mixtures in confined gap geometry under various levels of gravity were conducted to examine the Marangoni effects on near-bubble microscale transport. Full boiling curves were obtained and two boiling regimes---nucleate boiling and pseudo film boiling, and the transition condition, critical heat flux, identified. In the nucleate boiling regime, small bubbles were generated, condensed quickly in the bulk liquid, so that the agitation in the system resulted in great heat transfer performance. As the superheat level increased, the bubbles coalesced to a large vapor slug that was constrained by the gap geometry and started to blanket the heated surface. The maximum heat flux, (i.e. the critical heat flux, CHF), was then reached. The pseudo film boiling regime was reached by further increasing the superheat level, creating a slow, fluctuated bubble where boiling only occurred at its base perimeter because the heated surface was dried out. The temperature field created within the parallel plate gap resulted in evaporation over the portion of the vapor-liquid interface of the bubble near the heated surface, and condensation near the cold surface. This scenario produced a heat pipe effect inside the constrained bubble. For positive mixtures, Marangoni forces were proven to greatly enhance heat transfer under reduced and terrestrial gravity when compared with the boiling of distilled water. However, the presence of the gap geometry caused a premature occurrence of CHF conditions, and deteriorated heat transfer at high superheated temperatures. The influence of the confined space was particularly significant when greater Marangoni forces were presented under reduced gravity conditions. It caused the value of the CHF for x = 0.025, which corresponded to weaker Marangoni forces, to be greater than that of x = 0.015 with a 6.35 mm gap. This demonstrates the complex interaction that these three factors---Marangoni effects, gravity level, and gap size---have on heat transfer. A major contribution of this study is that it provides a parametric database, further expanding the knowledge in the field of heat transfer to make more optimal use of coolant composed of binary mixtures in various thermal applications.

Sun, Chen-Li

398

Modelling of crack chemistry in sensitized stainless steel in boiling water reactor environments  

Microsoft Academic Search

An advanced model has been used to predict the chemistry and potential in a stress corrosion crack in sensitized stainless steel in a boiling water reactor (BWR) environment. The model assumes trapezoidal crack geometry, incorporates anodic reaction and cathodic reduction within the crack, and takes into account the limited solubility of cations in high temperature water. The results indicate that

A. Turnbull

1997-01-01

399

Mechanical nonequilibrium considerations in homogeneous bubble nucleation for unsteady-state boiling  

Microsoft Academic Search

With thermal and mechanical nonequilbrium taken into consideration, the classical kinetic theory of boiling is modified to study unsteady-state homogeneous nucleation processes. Based on this newly developed model, the degree of superheat and the maximum nucleation rate corresponding to different rates of temperature rise in water are calculated and presented. For the first time, the initial nonequilibrium vapor pressure and

J. Li; G. P. Peterson; P. Cheng

2005-01-01

400

Mechanism supported by extensive experimental evidence to explain high heat fluxes observed during nucleate boiling  

Microsoft Academic Search

The mechanism responsible for high heat transfer rates occurring in nucleate boiling when liquid films exist on the heating surface is described. High-speed cinematography and simultaneous transient surface temperature measurements provide a basis for describing the mechanism. In a liquid film, bubbles grow and detach rapidly. The film is quickly renewed. A liquid microlayer exists beneath a bubble its entire

Russell Mesler

1976-01-01

401

Experimental study and modeling of nucleate boiling during free planar liquid jet impingement  

Microsoft Academic Search

Determination of boiling heat transfer rate during liquid jet impingement cooling (LJIC) depends on the intensity of bubble generation that is dependent on many flow and surface conditions such as jet velocity, liquid temperature, and surface superheat. Many empirical correlations have been developed previously to determine the total wall heat flux under various LJIC flow velocity, subcooling and surface superheat.

Ahmed M. T Omar

2010-01-01

402

A film boiling model for cryogenic chilldown at low mass flux inside a horizontal pipeline  

NASA Astrophysics Data System (ADS)

A film boiling heat transfer model is developed for cryogenic chilldown at low mass flux inside a horizontal pipeline. It incorporates the stratified flow structure and is based on conservation principles of mass, momentum, and energy. Simplifying assumptions lead to an expression for the local film boiling heat transfer coefficient which varies with the azimuthal angle. The efficacy of the model is assessed by comparing the predicted wall temperature histories with those measured at several azimuthal positions and various mass fluxes. Good agreement is observed at low flux, G = 13 54 kg/m2 s.

Liao, Jun; Mei, Renwei; Klausner, James F.

2006-08-01

403

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

404

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

405

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

406

A parametric study of nucleate boiling on structured surfaces. Part 1: Effect of tunnel dimensions  

SciTech Connect

This two-part experimental work identifies the effect of geometric dimensions on the boiling performance of tunneled enhanced boiling surfaces. The surface is formed on an integral-fin tube having a copper foil wrapped over the fin tips. Pores of known diameter and pitch are pierced in the foil cover. The resulting surface is similar to the Hitachi Thermoexcel-E tube. Tests were performed on a 19.1 mm diameter, horizontal tube using R-11 at 26.7 C for heat fluxes between 2-to-70 kW/m{sup 2}. The cylindrical glass test cell permitted viewing of the boiling process. The first part of the study defines the effect of the tunnel dimensions (fin height, fin pitch, and tunnel shape) for a limited range of pore diameters (0.12--0.28 mm) and pore pitches (0.75--3.0 mm). Data are provided for tubes having 35, 40, and 50 fins/in and fin heights between 0.5 and 1.5 mm. The data show that greater tunnel height and smaller tunnel pitch are preferred. Sharp tunnel corners having a small corner radius also provides greater enhancement. However, the pore diameter and pore pitch have the most significant effect on the boiling enhancement. The boiling performance for R-11 and R-123 are nearly equal at the same saturation temperature.

Chien, L.H.; Webb, R.L. [Pennsylvania State Univ., University Park, PA (United States). Dept. of Mechanical Engineering

1996-12-31

407

Cryogenic Boiling and Two-Phase Flow during Pipe Chilldown in Earth and Reduced Gravity  

NASA Astrophysics Data System (ADS)

For many industrial, medical and space technologies, cryogenic fluids play indispensable roles. An integral part of the cryogenic transport processes is the chilldown of the system components during initial applications. In this paper, we report experimental results for a chilldown process that is involved with the unsteady two-phase vapor-liquid flow and boiling heat transfer of the cryogen coupled with the transient heat conduction inside pipe walls. We have provided fundamental understanding on the physics of the two-phase flow and boiling heat transfer during cryogenic quenching through experimental observation, measurement and analysis. Based on the temperature measurement of the tube wall, the terrestrial cryogenic chilldown process is divided into three stages of film boiling, nucleate boiling and single-phase convection that bears a close similarity to the conventional pool boiling process. In earth gravity, cooling rate is non-uniform circumferentially due to a stratified flow pattern that gives rise to more cooling on the bottom wall by liquid filaments. In microgravity, there is no stratified flow and the absence of the gravitational force sends liquid filaments to the central core and replaces them by low thermal conductivity vapor that significantly reduces the heat transfer from the wall. Thus, the chilldown process is axisymmetric, but longer in microgravity.

Yuan, Kun; Ji, Yan; Chung, J. N.; Shyy, Wei

2008-01-01

408

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

409

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

E-print Network

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

J. Tõke; W. U. Schröder

2012-07-16

410

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

E-print Network

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

Tõke, J

2012-01-01

411

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

412

The effect of heated wall thickness and materials on nucleate boiling at high heat flux  

SciTech Connect

The nucleate boiling heat transfer at high heat flux is of significant importance in many applications. The present work is to numerically investigate the effect of heater side factors on the nucleate boiling at high heat flux, which is characterized by the existence of macrolayer. Two-region equations are proposed to study both thermo-capillary driven flow in the liquid layer and heat conduction in the solid wall. The numerical results indicate that the thermo-capillary driven flow in the macrolayer and evaporation at the vapor-liquid interface constitute a very efficient heat transfer mechanism to explain the high heat transfer coefficient of nucleate boiling heat transfer near CHF. For a very thin wall and/or wall with a poor thermal conductivity (heat side factors) are found to have significant effect on flow pattern in the liquid layer and the temperature distribution in the heated wall.

Ma, K.T.; Pan, C.

1999-11-01

413

Boiling sand springs, Dismal River, Nebraska: Agents for formation of vertical cylindrical structures and geomorphic change  

NASA Astrophysics Data System (ADS)

Boiling (motion, not temperature) sand springs fed by ground water moving upward along distinct conduits occur along the Dismal River in the Nebraska Sand Hills. The cylindrical conduits are developed in alluvium and are as large as 10 m in diameter and 44 m deep. Sides of the spring conduits are firm. Boiling sand is overlain in several places by a clear layer of water in the spring. Time-varying wave patterns and boils can be observed along the interface between these layers. Sediment within the conduits is generally well sorted, although some debris is present. Because of their large size, firm sides, and persistence in time, the conduits have the potential for preservation as vertical cylindrical structures comparable to those reported in sedimentary rocks of several ages. The discovery of preserved structures is evidence of paleo-ground-water discharge, and therefore the structures are a useful mapping tool for determining position in landscape evolution.

Guhman, Anne Irene; Pederson, Darryll T.

1992-01-01

414

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

E-print Network

-variate normal distribution. Using criteria limits of the coefficients of skewness (Yl ), and kurtosis (TZ) of each distribution, 18 of the original 48 variables were normally distributed at the 0. 05 significance level. Power transformations were applied... to the non-normal variables to derive normally distributed variables. Many of the original distributions were negatively skewed, indicating use of a power transform greater than unity. tv The dew point distribution could not be transformed for eight...

Zeitler, Jon William

2012-06-07

415

Effects of Cooking End-point Temperature and Muscle Part on Sensory 'Hardness' and 'Chewiness' Assessed Using Scales Presented in ISO11036:1994  

PubMed Central

Texture and ‘tenderness’ in particular, is an important sensory characteristic for consumers’ satisfaction of beef. Objective and detailed sensory measurements of beef texture have been needed for the evaluation and management of beef quality. This study aimed to apply the sensory scales defined in ISO11036:1994 to evaluate the texture of beef. Longissimus and Semitendinosus muscles of three Holstein steers cooked to end-point temperatures of 60°C and 72°C were subjected to sensory analyses by a sensory panel with expertise regarding the ISO11036 scales. For the sensory analysis, standard scales of ‘chewiness’ (9-points) and ‘hardness’ (7-points) were presented to the sensory panel with reference materials defined in ISO11036. As a result, both ‘chewiness’ and ‘hardness’ assessed according to the ISO11036 scales increased by increasing the cooking end-point temperature, and were different between Longissimus and Semitendinosus muscles. The sensory results were in good agreement with instrumental texture measurements. However, both texture ratings in this study were in a narrower range than the full ISO scales. For beef texture, ISO11036 scales for ‘chewiness’ and ‘hardness’ are useful for basic studies, but some alterations are needed for practical evaluation of muscle foods. PMID:25049732

Sasaki, Keisuke; Motoyama, Michiyo; Narita, Takumi; Chikuni, Koichi

2013-01-01

416

Reflectance measurement of the VUV spectrum of solid xenon and its temperature dependence up to the triple point  

E-print Network

L-339 Reflectance measurement of the VUV spectrum of solid xenon and its temperature dependence up disparition vers 135 K. Abstract. 2014 Accurate solid xenon reflectance measurements in the energy range 6 films (reflection or transmission), and also in a closed cell with LiF or MgF2 windows (reflection

Boyer, Edmond

417

An experimental study of subcooled flow film boiling across horizontal cylinders  

NASA Astrophysics Data System (ADS)

An experimental investigation of subcooled flow film boiling of Freon-113 over horizontal cylinders was undertaken. Experiments were performed for liquid velocities ranging from 0.78 m/s to 3.05 m/s, and for liquid subcooling ranging from 55.3°C to 72.6°C. Simultaneous wall temperature measurements were recorded using five miniature thermocouples embedded in the heater. A two-dimensional nonlinear inverse heat conduction problem (IHCP) was formulated based on the well-posed hyperbolic heat conduction equation, to estimate the surface heat flux, given measured heater temperatures. Based on the transient surface heat flux estimates and the measured wall temperature fluctuations, solid-liquid and pseudo contacts were identified. Contact parameters such as duration of contact, energy removed per contact, and wall temperature depression per contact were extracted from the data. The results showed that the contacts were not periodic. No clear trend was evident in the data. Correlation of the data was impossible due to the large scatter present. Boiling curves based on both "apparent" and "corrected" heat fluxes were compared to emphasize the importance of internal heat conduction in the heater. The effect of the thermal properties of the heater was investigated using computer simulations. It showed that the lava core was unaffected by short duration contacts. The lava core acts as an energy storage medium. Analysis of the nucleate-film boiling showed that the heater was capable of sustaining simultaneous nucleate and film boiling on its surface. An analytical flow film boiling model was also developed. Though this model does not include heat transfer in the wake of the heater and the effects of solid-liquid or pseudo contact, it is still a major improvement over all existing analytical models. However, these limitations of the model resulted in poor agreement between predicted wall temperatures and those experimentally measured.

Warrier, Gopinath Rama

418

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

419

A new fluorous\\/organic amphiphilic ether solvent, F-626: execution of fluorous and high temperature classical reactions with convenient biphase workup to separate product from high boiling solvent  

Microsoft Academic Search

A new fluorous\\/organic amphiphilic ether solvent, 1H,1H,2H,2H-perfluorooctyl 1,3-dimethylbutyl ether (F-626), is introduced. The basic properties of F-626, especially the partition coefficients with organic solvents\\/FC-72 (perfluorohexane), were investigated. F-626 was easy to remove by fluorous biphase treatment. Using F-626 as a solvent, LAH reduction, catalytic hydrogenation, and fluorous reductive radical reactions were successful. Classical high temperature reactions up to 200°C, such

Hiroshi Matsubara; Shinji Yasuda; Hiroyuki Sugiyama; Ilhyong Ryu; Yasuyuki Fujii; Katsumi Kita

2002-01-01

420

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

421

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

422

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

423

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

424

Boiling heat transfer on superhydrophilic, superhydrophobic, and superbiphilic surfaces  

E-print Network

Boiling heat transfer on superhydrophilic, superhydrophobic, and superbiphilic surfaces Amy Rachel Enhanced heat transfer Pool boiling Nucleation a b s t r a c t With recent advances in micro characterize pool boiling on surfaces with wettabilities varied from superhydrophobic to superhydrophilic

Attinger, Daniel

425

Nucleation characteristics and stability considerations during flow boiling in microchannels  

E-print Network

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

Kandlikar, Satish

426

ADVANCED POWER PLANT MODELING WITH APPLICATIONS TO THE ADVANCED BOILING  

E-print Network

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

Mitchell, John E.

427

EXPERIMENTAL INVESTIGATION OF BOILING HEAT CONVECTION IN A FRACTURE  

E-print Network

EXPERIMENTAL INVESTIGATION OF BOILING HEAT CONVECTION IN A FRACTURE A REPORT SUBMITTED between heat conduction and heat convection with boiling flow in a rock fracture. An experimental investigation attemped to analyze and quantify this coupling, which can be called a boiling convection

Stanford University

428

EFFECT OF SURFACE CHARACTERISTICS ON FLOW BOILING HEAT TRANSFER  

E-print Network

ABSTRACT It is well known that the surface structure affects the pool boiling heat transfer from a heater that the surface condition of the boiling surface affects the pool boiling heat transfer. Surface conditions and the overall heat flux. Enhancement techniques such as sintering and specially fabricated surface geometries

Kandlikar, Satish

429

Experimental study of surfactant effects on pool boiling heat transfer  

Microsoft Academic Search

In the first part of this work, nucleate boiling of aqueous solutions of sodium lauryl sulfate (SLS) over relatively wide ranges of concentration and heat flux was carried out in a pool boiling apparatus. The experimental results show that a small amount of surface active additive makes the nucleate boiling heat transfer coefficient h considerably higher, and that there is

Ying Liang Tzan; Yu Min Yang

1990-01-01

430

CFD simulation of refrigerant boiling in vertical annulus  

Microsoft Academic Search

In this paper a forced convective boiling of Refrigerant R-113 in a vertical annular channel has been simulated by the CFX-5 code. The employed subcooled boiling model uses a special treatment of the wall boiling boundary, which assures the grid invariant solution. The simulation results have been validated against the published experimental data (1). In general a good agreement with

Eckhard Krepper

431

CFD SIMULATION OF FORCED CONVECTIVE BOILING IN HEATED CHANNELS  

Microsoft Academic Search

In this paper a forced convective boiling of Refrigerant R-113 in a vertical annular channel has been simulated by a custom version of the CFX-5 code. The employed subcooled boiling model uses a special treatment of the wall boiling boundary, which assures the grid invariant solution. The simulation results have been validated against the published experimental data (1). In general

Eckhard Krepper

432

A dry-spot model of critical heat flux applicable to both pool boiling and subcooled forced convection boiling  

SciTech Connect

A study has been performed to predict CHF in pool boiling and subcooled forced convection boiling using the dry-spot model presented by the authors and existing correlations for heat transfer coefficient, active site density and bubble departure diameter in nucleate boiling. Comparisons of the model predictions with experimental data for pool boiling of water and subcooled upward forced convection boiling of water in vertical, uniformly-heated round tubes have been performed and the parametric trends of CHF have been investigated. The results of the present study strongly support the validity of physical feature of the present model on the CHF mechanism in pool boiling and subcooled forced convection boiling. To improve the prediction capability of the present model, further works on active site density, bubble departure diameter and suppression factor in subcooled boiling are needed.

Ha, S.J.; No, H.C.

1999-07-01

433

A new microstructure for pool boiling  

NASA Astrophysics Data System (ADS)

Combining electrocoating and etching processes, we have developed a new type of microstructure for nucleate boiling. The basic elements of the structure are cylindrically shaped; their density ranges up to 10 7 cm -2. To test the efficiency of the structure, the outer surface of a tube has been provided with such a structure and used in pool boiling experiments with the refrigerant R141b at atmospheric pressure. The results obtained show the heat flux to remain independent of the wall superheat in the fully developed boiling region. The behavior is novel. It is most probably associated with the density of active bubble nucleation sites. Activated at a certain wall superheat, the density of the sites generating bubbles remains apparently unaffected by raising the heat flux. Given that these preliminary results should be confirmed by further experiments, the microstructure developed will be suitable for nucleate boiling in general, but for keeping the heating surface largely isothermal, despite the variation of the heat flux, in particular.

Mitrovic, J.; Hartmann, F.

2004-03-01

434

Classic and Hard-Boiled Detective Fiction.  

ERIC Educational Resources Information Center

Through an analysis of several stories, this paper defines the similarities and differences between classic and hard-boiled detective fiction. The characters and plots of three stories are discussed: "The Red House" by A. A. Milne; "I, The Jury" by Mickey Spillane; and "League of Frightened Men" by Rex Stout. The classic detective story is defined…

Reilly, John M.

435

Pool boiling heat transfer to electrolyte solutions  

Microsoft Academic Search

Pool boiling heat transfer coefficients were measured for solutions of salts with positive solubility in water. The effect of the dissolved salts on nucleation site density, bubble departure diameter and bubble frequency was also investigated. The results show that at low heat fluxes heat transfer coefficients can be considerably lower than corresponding values for distilled water. At high heat fluxes

M. Jamialahmadi; A. Helalizadeh; H. Müller-Steinhagen

2004-01-01