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1

Saturated and subcooled hydrothermal boiling in groundwater flow channels as a source of harmonic tremor  

NASA Astrophysics Data System (ADS)

The potential of hydrothermal boiling in groundwater flow channels for generating harmonic tremor (a relatively monochromatic ground vibration associated with volcanic activity) is examined. We use simple "organ pipe" theory of normal-mode fluid vibration and fundamental energy considerations to develop a first-order analytical model of a hydrothermal-boiling source of harmonic tremor. We use this model to estimate order-of-magnitude groundwater flow channel lengths and boiling heat transfer rates required to produce harmonic tremor with dominant frequencies in the range 0.5-5 Hz and surface wave reduced displacements of up to 100 cm2. Depending on groundwater sound speed, flow channel lengths of the order of 1-1000 m are required to produce fluid vibration eigenfrequencies in the range 0.5-5 Hz. The boiling heat transfer rate required to produce tremor with a given surface wave reduced displacement depends on the tremor frequency and on whether saturated boiling or subcooled boiling is the cause of the tremor. Saturated boiling produces groundwater vibration via steam bubble growth, whereas subcooled boiling produces groundwater vibration via steam bubble collapse. We find that subcooled hydrothermal boiling is from 102 to 104 times more efficient than saturated boiling in converting boiling "thermal" power to seismic power. For example, the boiling heat transfer rates required to produce 1-Hz tremor with reduced displacements of up to 100 cm2 via subcooled boiling are generally less than a few thousand megawatts; for saturated boiling, the required boiling heat transfer rates are several orders of magnitude larger than this. The highest values of heat flow reported in the literature for volcanic crater lakes and terrestrial and ocean floor geothermal areas are of the order of 1000 MW. Taking this value as a first-order estimate of an upper limit on possible boiling heat transfer rates in volcanic hydrothermal systems, our results suggest that saturated hydrothermal boiling is capable of generating only low-amplitude harmonic tremor, with surface wave reduced displacements no higher than a few square centimeters. However, subcooled hydrothermal boiling could potentially generate high-amplitude harmonic tremor, with reduced displacements as large as several hundred square centimeters. As a specific application of our model, we evaluate the potential of hydrothermal boiling for generating harmonic tremor at recently active Mount St. Helens and Nevado Del Ruiz volcanoes. We conclude that subcooled boiling likely could have produced the tremor episodes considered at both volcanoes. Saturated boiling also could explain the Nevado Del Ruiz tremor but probably not the more powerful Mount St. Helens tremor.

Leet, Robert C.

1988-05-01

2

Saturated and subcooled hydrothermal boiling in groundwater flow channels as a source of harmonic tremor  

Microsoft Academic Search

The potential of hydrothermal boiling in groundwater flow channels for generating harmonic tremor (a relatively monochromatic ground vibration associated with volcanic activity) is examined. We use simple ``organ pipe'' theory of normal-mode fluid vibration and fundamental energy considerations to develop a first-order analytical model of a hydrothermal-boiling souce of harmonic tremor. We use this model to estimate order-of-magnitude groundwater flow

Robert C. Leet

1988-01-01

3

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

SciTech Connect

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

Not Available

1989-01-01

4

Critical heat flowrates in subcooled flow boiling  

Microsoft Academic Search

Matters related to calculating critical heat flowrates during boiling in a highly subcooled flow are considered. Existing\\u000a data on heat transfer for swirl flow with one-sided heating are analyzed, and a formula for calculating critical heat flowrates\\u000a is proposed. The conditions under which the thermodynamic limit of boiling is reached are analyzed.

A. V. Dedov

2010-01-01

5

Improvements in Predicting Void Fraction in Subcooled Boiling  

SciTech Connect

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

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

2005-06-15

6

Microbubble Return Phenomena During Subcooled Boiling on Small Wires  

Microsoft Academic Search

An experimental investigation was conducted to explore the characteristics of subcooled boiling on microwires of 25 and 100 lm diameter. Microbubbles were observed to return to the wire surface after detachment, with two types of bubble return identified, i.e., isolated bubble return, and bubble return with liquid–vapor trailing jets. The former mode of bubble return occurred when isolated small bubbles

H Wang; X. F. Peng; S V Garimella; D. Christopher

2006-01-01

7

Microbubble return phenomena during subcooled boiling on small wires  

Microsoft Academic Search

An experimental investigation was conducted to explore the characteristics of subcooled boiling on microwires of 25 and 100?m diameter. Microbubbles were observed to return to the wire surface after detachment, with two types of bubble return identified, i.e., isolated bubble return, and bubble return with liquid–vapor trailing jets. The former mode of bubble return occurred when isolated small bubbles (of

Hao Wang; Xiaofeng Peng; Suresh V. Garimella; David M. Christopher

2007-01-01

8

Mechanistic modeling of CHF in forced-convection subcooled boiling  

SciTech Connect

Because of the complexity of phenomena governing boiling heat transfer, the approach to solve practical problems has traditionally been based on experimental correlations rather than mechanistic models. The recent progress in computational fluid dynamics (CFD), combined with improved experimental techniques in two-phase flow and heat transfer, makes the use of rigorous physically-based models a realistic alternative to the current simplistic phenomenological approach. The objective of this paper is to present a new CFD model for critical heat flux (CHF) in low quality (in particular, in subcooled boiling) forced-convection flows in heated channels.

Podowski, M.Z.; Alajbegovic, A.; Kurul, N.; Drew, D.A.; Lahey, R.T. Jr. [Rensselaer Polytechnic Inst., Troy, NY (United States). Center for Multiphase Research

1997-05-01

9

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

Microsoft Academic Search

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

L. K. T

1987-01-01

10

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

Microsoft Academic Search

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

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

11

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

SciTech Connect

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

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

2006-04-27

12

Effect of subcooled boiling on the dynamic instability of a natural circulation system.  

National Technical Information Service (NTIS)

The appearance of subcooled boiling is the beginning of the thermodynamic non-equilibrium that may lead a fluid flow system into low-quality instability region. The effect of subcooled boiling on the stability and transient behavior of a natural circulati...

C. Gao Z. Gao

1992-01-01

13

Thermocapillary convection during subcooled boiling in reduced gravity environments.  

PubMed

Complete understanding of the origin of thermocapillary convection during subcooled boiling remains elusive. Some recent studies have suggested that the presence of dissolved gas inside the vapor bubble leads to the formation of a localized concentration and temperature gradient along the liquid-vapor interface and thus to the onset of thermocapillary convection. These studies reported that the dissolved gas content determines the onset of thermocapillary convection and that no thermocapillary motion was observed for subcooled boiling with pure liquid. However, other experiments performed in reduced gravity suggest that the strength of the thermocapillary convection around the primary bubble in a gas-saturated fluid is much weaker than that in a degassed fluid. This paper presents a qualitative study of the effects of dissolved gas content, bubble shape and size, and heat transfer coefficient on the strength of thermocapillary convection and offers possible explanations for the existing confusion. Owing to the presence of different complex and interrelated mechanisms, we decoupled the individual mechanisms to study their overall effect on thermocapillary convection. The results indicate that variations in the heat transfer coefficient and in the shape and the size of the bubble play a major role in the development of thermocapillary motion. PMID:19426315

Raj, Rishi; Kim, Jungho

2009-04-01

14

Enhancement of heat transfer in subcooled flow boiling with microbubble emission  

Microsoft Academic Search

Subcooled flow boiling of water was tested for a large heating surface of 5cm length and 2cm width in a horizontal rectangular channel of 5mm height and 24mm width. Microbubble emission boiling occurred in transition boiling at 40K of liquid subcooling and 0.5m\\/s of liquid velocity and the maximum heat flux was higher than the ordinary critical heat flux. Maximum

Koichi Suzuki; Toshiyuki Kokubu; Masaki Nakano; Hiroshi Kawamura; Ichiro Ueno; Hiroya Shida; Osamu Ogawa

2005-01-01

15

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

SciTech Connect

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

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

2006-04-27

16

Wall heat flux partitioning during subcooled forced flow film boiling of water on a vertical surface  

Microsoft Academic Search

Subcooled flow film boiling experiments were conducted on a vertical flat plate, 30.5cm in height, and 3.175cm wide with forced convective upflow of subcooled water at atmospheric pressure. Data have been obtained for mass fluxes ranging from 0 to 700kg\\/m2s, inlet subcoolings ranging from 0 to 25°C and wall superheats ranging from 200 to 400°C. Correlations for wall heat transfer

Phani K. Meduri; Gopinath R. Warrier; Vijay K. Dhir

2009-01-01

17

Thermal interaction effect on nucleation site distribution in subcooled boiling  

SciTech Connect

An experimental work on subcooled boiling of refrigerant, R134a, to examine nucleation site distributions on both copper and stainless steel heating surfaces was performed. In order to obtain high fidelity active nucleation site density and distribution data, a high-speed digital camera was utilized to record bubble emission images from a view normal to heating surfaces. Statistical analyses on nucleation site data were done and their statistical distributions were obtained. Those experimentally observed nucleation site distributions were compared to the random spatial Poisson distribution. The comparisons showed that, rather than purely random, active nucleation site distributions on boiling surfaces are relatively more uniform. Experimental results also showed that on the copper heating surface, nucleation site distributions are slightly more uniform than on the stainless steel surface. This was concluded as the results of thermal interactions between nucleation sites with different solid thermal conductivities. A two dimensional thermal interaction model was then developed to quantitatively examine the thermal interactions between nucleation sites. The results give a reasonable explanation to the experimental observation on nucleation site distributions.

Ling Zou; Barclay Joned

2012-05-01

18

Prediction of critical heat flux for flow boiling in subcooled and saturated regimes  

Microsoft Academic Search

A systematic investigation on the effect of major variables on critical heat flux in forced convection of flow boiling was carried out using available world data for water in a vertical round tube. A new correlation was developed to predict the critical heat flux in both subcooled boiling and saturated boiling regimes. The correlation relates critical heat flux to only

Zhijian Deng

1998-01-01

19

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

20

Jet flows from bubbles during subcooled pool boiling on micro wires  

Microsoft Academic Search

An experimental investigation was conducted on subcooled nucleate boiling on ultra-small wires having diameters of 25–100\\u000a ?m. High-speed photography and laser PIV (Particle Image Velocimetry) technology were used to visually observe the bubble\\u000a dynamics. For highly subcooled boiling, at moderate heat fluxes, the bubbles generally remained attached to the micro heating\\u000a wires and bubble-top jet flows were clearly observed. Smaller

Hao Wang; D. M. Christopher; Xiaofeng Peng; Buxuan Wang

2005-01-01

21

Boiling.  

National Technical Information Service (NTIS)

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

G. Leppert C. C. Pitts

1964-01-01

22

Assessment of subcooled boiling model used in RELAP5/MOD2 (Cycle 36. 05, Version E03) against experimental data  

SciTech Connect

In order to test the ability of RELAP5/MOD2 to describe sub-cooled nucleate boiling under conditions similar to those anticipated during intact circuit fault scenarios in pressurized water reactors the code has been assessed against results of high pressure sub-cooled boiling experiments reported in literature. It is concluded that RELAP5/MOD2 can be applied with reasonable confidence to the prediction of sub-cooled boiling void fraction for conditions expected during PWR intact circuit faults.

Brain, C.R. (Central Electricity Generating Board, Barnwood (United Kingdom). Generation Development and Construction Div.)

1992-03-01

23

Pool boiling heat transfer on small heaters: effect of gravity and subcooling  

Microsoft Academic Search

Measurements of space and time resolved subcooled pool boiling of FC-72 in low, earth, and high gravity environments were made using a microscale heater array. Data from each heater in the array were synchronized with high-speed digital video. The boiling behavior was dominated by the formation of a large primary bubble on the surface which acted as a “sink” for

Jungho Kim; John F. Benton; Derek Wisniewski

2002-01-01

24

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

SciTech Connect

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

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

2004-06-23

25

Experimental and theoretical investigation of adiabatic bubbly flow and subcooled boiling flow in an annulus  

NASA Astrophysics Data System (ADS)

The two-fluid model is the most advanced thermal hydraulic model for the analysis of nuclear reactor systems. One of the closure relations for this model is the interfacial area transport equation. Subcooled boiling is of considerable interest to boiling water reactor safety. A robust mechanistic model does not exist yet for subcooled boiling. To develop a mechanistical constitutive relation for the subcooled boiling condition, a better understanding of the physical phenomenon and a solid, extensive database are essential. This thesis focuses on experimental and theoretical investigations on adiabatic bubbly flow and subcooled boiling flow in a BWR-scaled annular flow channel. A database of flow parameters and data sets of the liquid velocity are established for the adiabatic bubbly flow. Databases of flow parameters and boundary parameters, such as active nucleation site density, bubble lift-off diameter, and bubble lift-off frequency, are also obtained for subcooled convective boiling in the annular test section. The one-dimensional, one-group interfacial area transport equation is evaluated based on the experimental data in the adiabatic bubbly flow. The correlation of distribution parameter, drift velocity, and Sauter mean diameter are evaluated from data in both adiabatic bubbly flow and subcooled boiling flow. A bubble-layer thickness model is proposed to avoid various covariances in the cross-sectional area averaged interfacial area transport equation in the subcooled boiling flow. The newly-developed model can predict the bubble-layer thickness as well as the void fraction profile by assuming a square void peak in the bubble-layer region. In addition, the constitutive equation for the distribution parameter in the drift-flux model for boiling flow of an internally heated annulus is also developed based from the measured data. A constitutive relation for the bubble lift-off size is developed based on a force balance and turbulence analysis. The comparisons between the constitutive relation and the experimental data show good agreements. In addition, a preliminary constitutive relation of the bubble lift-off frequency is also obtained. The achievements will be used for the development of the interfacial area transport equation. This will provide a true, mechanistic model of the transfer mechanisms in subcooled convective boiling.

Situ, Rong

26

Influence of Test Tube Material on Subcooled Flow Boiling Critical Heat Flux in Short Vertical Tube  

Microsoft Academic Search

The steady state subcooled flow boiling critical heat flux (CHF) for the flow velocities (u = 4.0 to 13.3 m\\/s), the inlet subcooling (T{sub sub,in} = 48.6 to 154.7 K), the inlet pressure (P{sub in} = 735.2 to 969.0 kPa) and the increasing heat input (Q exp(t\\/t), t = 10, 20 and 33.3 s) are systematically measured with the experimental

Koichi Hata; Masahiro Shiotsu; Nobuaki Noda

2006-01-01

27

FLOW FILM BOILING ON A VERTICAL FLAT PLATE AT DIFFERENT SUBCOOLINGS AND FLOW VELOCITIES  

Microsoft Academic Search

Steady state film boiling experiments have been performed on a vertical flat plate, 0.305 m in height, and 3.175 cm wide with forced convective upflow of subcooled water at atmospheric pressure. Data have been obtained for mass flux ranging from 0 to 700 kg\\/m2s and inlet subcooling ranging from 0 to 25 °C. In addition to the wall heat transfer

Phani K. Meduri; Gopinath R. Warrier; Vijay K. Dhir

28

An experimental study of subcooled flow film boiling across horizontal cylinders  

Microsoft Academic Search

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

Gopinath Rama Warrier

1997-01-01

29

Bubble behavior in subcooled flow boiling of water at low pressures and low flow rates  

Microsoft Academic Search

This study presents experimental data for subcooled flow boiling of water at pressures from 1.05 to 3 bar, bulk liquid velocities ranging from 0.08 to 0.8 m\\/s, and subcooling from 10 to 30 K. Experiments were carried out on a vertical, annular test section with inner heating surface and upward water flow. High-speed photography at rates of 6000–8000 frames\\/s captured

V Prodanovic; D Fraser; M Salcudean

2002-01-01

30

Mechanistic model for the prediction of water-subcooled-flow-boiling critical heat flux at high liquid velocity and subcooling  

SciTech Connect

A new model is presented for the prediction of the critical heat flux (CHF) of subcooled flow boiling based on a liquid-sublayer dryout mechanism, i.e., the dryout of a thin, liquid layer beneath an intermittent vapor blanket due to the coalescence of small bubbles. The model focuses on the analysis of the CHF in subcooled flow boiling under conditions of very high mass flux and liquid subcooling, typical of fusion reactor thermal-hydraulic design, and is characterized by the absence of empirical constants always present in earlier models. Peripheral nonuniform heating and/or twisted-tape inserts are accounted for in the model, which was originally developed for uniform heating and straight flow. The simultaneous occurrence of the two events is also well predicted by the model. Although initially formulated for operating conditions typical of the thermal-hydraulic design of fusion reactor high-heat-flux components, the model is proven to be able to satisfactorily predict the CHF under more general conditions, provided local thermodynamic conditions of the bulk flow at the CHF are sufficiently far from the saturated state. 60 refs., 11 figs.

Celata, G.P.; Cumo, M.; Mariani, A.; Zummo, G. [ENEA, Rome (Italy)

1996-07-01

31

Peak pool boiling heat flux from horizontal cylinders in subcooled liquids  

SciTech Connect

The peak pool boiling heat flux is observed on horizontal cylindrical heaters in acetone, Freon-113, methanol, and isopropanol over ranges of subcooling from zero to 120/sup 0/C. Photographs, and the data themselves, reveal that there are three distinct burnout mechanisms at different levels of subcooling. Three interpretive models provide the basis for accurate correlations of the present data, and data from the literature, in each of the three regimes. Burnout is dictated by condensation on the walls of the vapor jets and columns at low subcooling. In the intermediate regime, burnout is limited by natural convection which becomes very effective as vapor near the heater reduces boundary layer resistance. Burnout in the high-subcooling regime is independent of the level of subcoooling and is limited by the process of molecular effusion.

Elkassabgi, Y.

1986-01-01

32

Visualization of Sub-Cooled Flow Film Boiling in Horizontal Channel on Flat Heat Exchangers  

SciTech Connect

The observation of sub-cooled flow film boiling was performed on a single-side-heated flat heat exchanger by using refrigerant R134a as the testing fluid. A stable vapor film was observed with the co-existence of sub-cooled bulk liquid. Vapor bubbles might release from the film, with the number and frequency changing under different conditions. The purpose of this paper is to describe these observations, and to provide a quantitative analysis of the phenomena. Results are compared with Berenson's model on horizontal heating surface, with discussion and suggestion made. (authors)

Wen Wu; Peipei Chen; Jones, Barclay G.; Newell, Ty A. [University of Illinois at Urbana-Champaign, Urbana, IL, 61801 (United States)

2006-07-01

33

The Characteristics of Steam Bubbles in Subcooled Boiling Flow  

SciTech Connect

In two-fluid modeling and three-fluid modeling, the accurate prediction of the interfacial area concentration, interfacial heat transfer and interfacial shear stress, were required. In this works, the axial profiles of void fraction, interfacial area concentration and interfacial heat transfer coefficient along the flow direction could be measured. For the steam bubbles whose diameter were less than 8 mm, the interfacial area concentration and the mean bubble diameter had a correlation with void fraction despite the variation of liquid flow rate and subcooling. In case the steam bubble collapse occurred due to an irregular bubble condensation and a turbulence of liquid flow, interfacial heat transfer coefficient with the bubble collapse was about twice of that without a bubble collapse. And the interfacial heat transfer coefficient without bubble collapse showed a good agreement with the correlation proposed by Akiyama. In addition, the supposed image processing method could be applied to the present experimental condition. (authors)

Takatoshi Takemoto; Asi Bunyajitradulya [Chulalongkom University, 254 Phyathai Road, Patumwan, Bangkok 10330 (Thailand); Mitsuo Matsuzaki; Hiroshige Kikura; Masanori Aritomi [Tokyo Institute of Technology, O-okayama, Meguro-ku, Tokyo 152 (Japan)

2002-07-01

34

A 2D numerical simulation of sub-cooled flow boiling at low-pressure and low-flow rates  

Microsoft Academic Search

The main purpose of this study is to apply a two-fluid mathematical model to numerical simulation of two-phase flow at low-pressure condition. Although models of sub-cooled boiling flow at one-dimension and high-pressure have been studied extensively, there are few equivalent studies for numerical simulation at two-dimension and low-pressure (1–2bar) conditions. Recent literature studies on sub-cooled boiling flow at low-pressure have

Said Talebi; Farshad Abbasi; Hadi Davilu

2009-01-01

35

Sub-Cooled Pool Boiling Enhancement with Nanofluids  

Microsoft Academic Search

Phase-change heat transfer is an important process used in many engineering thermal designs. Boiling is an important phase change phenomena as it is a common heat transfer process in many thermal systems. Phase change processes are critical to thermodynamic cycles as most closed loop systems have an evaporator, in which the phase change process occurs. There are many applications\\/processes in

Elliott Charles Rice

2011-01-01

36

EFFECTS OF DISSOLVED NITROGEN ON SUBCOOLED NUCLEATE BOILING IN SANTOWAX  

Microsoft Academic Search

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

1961-01-01

37

Critical heat flux correlation for subcooled boiling flow in narrow channels  

Microsoft Academic Search

The purpose of this study is to conduct the critical heat flux (CHF) correlation for narrow channels. The CHF of subcooled flow boiling of water in narrow rectangular channels under atmospheric pressure was measured parametrically. Experimental test channels were rectangular and heated from one side with the channel gap of 0.2–3.0 mm, channel width of 7–22 mm, and heated length

M Kureta; H Akimoto

2002-01-01

38

Analysis and Measurement of Bubble Dynamics and Associated Flow Field in Subcooled Nucleate Boiling Flows  

SciTech Connect

In recent years, subooled nucleate boiling (SNB) has attrcted expanding research interest owing to the emergence of axial offset anomaly (AOA) or crud-induced power shigt (CIPS) in many operating US PWRs, which is an unexpected deviation in the core axial power distribution from the predicted power curves. Research indicates that the formation of the crud, which directly leads to AOA phenomena, results from the presence of the subcooled nucleate boiling, and is especially realted to bubble motion occurring in the core region.

Barclay G. Jones

2008-10-01

39

An experimental investigation of critical heat flux performance of hypervapotron in subcooled boiling  

NASA Astrophysics Data System (ADS)

The successful use of subcooled flow boiling for high heat flux components requires that the critical heat flux (CHF), i.e., a fast reduction in the boiling heat transfer, must be avoided. Among the many techniques available to enhance CHF, particular attention has been focused on the hypervapotron concept. In this study, the CHF characteristics of the hypervapotron were experimentally investigated using a simulant fluid, R134a, which has been found to be an effective modeling fluid to simulate CHF in water-cooled environments. An experimental and modeling study of the subcooled boiling heat transfer on plain surface and hypervapotron has been conduced. A test facility was designed and constructed to perform required boiling heat transfer experiments. A high speed visualization system was utilized to give details of bubble formation and departure and of nucleation site density. Surface measurements of various specimens were performed to investigate the relationship between nucleation sites and surface microstructure. Full characterization of the hypervapotron effect as a function of fluid thermal hydraulic conditions was accomplished. A non-dimensional CHF correlation for smooth rectangular channels and the hypervapotron channel was developed and compared with experimental data in this work. In addition, a hot-spot model was developed to give predictions of critical heat flux on both plain and hypervapotron surfaces. It was developed on observations of bubble formation, departure and coalescence, and on the confirmation of nucleation structure on the heating surface. Finally, a numerical code was successfully developed to give CHF predictions for hypervapotron configurations. The simulation indicates that the better performance of CHF in hypervapotron configurations is a result of high conductivity material with augmented heating surfaces in subcooled boiling environment. Different fin dimensions were also tested numerically to compare the experimental results, and suggestions are provided with respect to the combination of performance and economy.

Chen, Peipei

40

Assessment of subcooled boiling model used in RELAP5/MOD2 (Cycle 36.05, Version E03) against experimental data. International agreement report  

SciTech Connect

In order to test the ability of RELAP5/MOD2 to describe sub-cooled nucleate boiling under conditions similar to those anticipated during intact circuit fault scenarios in pressurized water reactors the code has been assessed against results of high pressure sub-cooled boiling experiments reported in literature. It is concluded that RELAP5/MOD2 can be applied with reasonable confidence to the prediction of sub-cooled boiling void fraction for conditions expected during PWR intact circuit faults.

Brain, C.R. [Central Electricity Generating Board, Barnwood (United Kingdom). Generation Development and Construction Div.

1992-03-01

41

A theoretical prediction of critical heat flux in subcooled pool boiling during power transients  

SciTech Connect

Understanding and predicting critical heat flux (CHF) behavior during steady-state and transient conditions are of fundamenatal interest in the design, operation, safety of boiling and two-phase flow devices. This paper discusses the results of a comprehensive theoretical study made specifically to model transient CHF behavior in subcooled pool boiling. This study is based upon a simplified steady-state CHF model in terms of the vapor mass growth period. The results obtained from this theory indicate favorable agreement with the experimental data from cylindrical heaters with small radii. The statistical nature of the vapor mass behavior in transient boiling also is considered and upper and lower limits for the current theory are established. Various factors that affect the discrepancy between the data and the theory are discussed.

Pasamehmetoglu, K.O.; Nelson, R.A.; Gunnerson, F.S.

1988-01-01

42

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

NASA Astrophysics Data System (ADS)

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

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

43

A new mechanistic model of critical heat flux in forced-convection subcooled boiling  

SciTech Connect

Because of its practical importance and various industrial applications, the process of subcooled flow boiling has attracted a lot of attention in the research community in the past. However, the existing models are primarily phenomenological and are based on correlating experimental data rather than on a first-principle analysis of the governing physical phenomena. Even though the mechanisms leading to critical heat flux (CHF) are very complex, the recent progress in the understanding of local phenomena of multiphase flow and heat transfer, combined with the development of mathematical models and advanced Computational Fluid Dynamics (CFD) methods, makes analytical predictions of CHF quite feasible. Various mechanisms leading to CHF in subcooled boiling have been investigated. A new model for the predictions of the onset of CHF has been developed. This new model has been coupled with the overall boiling channel model, numerically implemented in the CFX 4 computer code, tested and validated against the experimental data of Hino and Ueda. The predicted critical heat flux for various channel operating conditions shows good agreement with the measurements using the aforementioned closure laws for the various local phenomena governing nucleation and bubble departure from the wall. The observed differences are consistent with typical uncertainties associated with CHF data.

Alajbegovic, A.; Kurul, N.; Podowski, M.Z.; Drew, D.A.; Lahey, R.T. Jr. [Rensselaer Polytechnic Inst., Troy, NY (United States). Center for Multiphase Research

1997-10-01

44

Subcooled flow boiling critical heat flux (CHF) and its application to fusion energy components. Part I. A review of fundamentals of CHF and related data base  

Microsoft Academic Search

The present understanding of critical heat flux (CHF) in subcooled flow boiling with water is reviewed and fusion reactor component high-heat flux (HHF) requirements are outlined. This survey (Parts I and II), which contains a representative coverage of the literature over the last 30 years, is concerned only with CHF in the subcooled flow boiling regime. CHF data base parameter

1985-01-01

45

Heating surface material’s effect on subcooled flow boiling heat transfer of R134a  

SciTech Connect

In this study, subcooled flow boiling of R134a on copper (Cu) and stainless steel (SS) heating surfaces was experimentally investigated from both macroscopic and microscopic points of view. By utilizing a high-speed digital camera, bubble growth rate, bubble departure size, and nucleation site density, were able to be observed and analyzed from the microscopic point of view. Macroscopic characteristics of the subcooled flow boiling, such as heat transfer coefficient, were able to be measured as well. Experimental results showed that there are no obvious difference between the copper and the stainless surface with respect to bubble dynamics, such as contact angle, growth rate and departure size. On the contrary, the results clearly showed a trend that the copper surface had a better performance than the stainless steel surface in terms of heat transfer coefficient. It was also observed that wall heat fluxes on both surfaces were found highly correlated with nucleation site density, as bubble hydrodynamics are similar on these two surfaces. The difference between these two surfaces was concluded as results of different surface thermal conductivities.

Ling Zou; Barclay G. Jones

2012-11-01

46

Origin and effect of thermocapillary convection in subcooled boiling: observations and conclusions from experiments performed at microgravity.  

PubMed

During the past two decades we have performed pool boiling experiments under microgravity conditions with saturated and subcooled liquids using various fluids, mostly fluorinated hydrocarbons, and various shapes of heaters. The common observation at subcooled boiling is the development of thermocapillary convection around bubbles. This convection forms jet streams above the head of the bubbles that carry the heat from the bubbles into the ambient liquid. Heat transfer measurements demonstrate that this flow does not directly contribute to the overall heat transfer itself, but that it is an important transport mechanism in subcooled boiling, not only at microgravity, but also under terrestrial conditions. The development of a thermocapillary flow is surprising, because it is well known that for this convection a temperature gradient along the interface of a bubble is necessary. However, it is also well known that the interfacial kinetics of evaporation and condensation is very strong. Thus, small temperature differences generate strong mass flow rates across the interface, coupled with high heat transfer rates that immediately equalize even moderate temperature gradients appearing along the bubble interface. This is confirmed by the observation that, during boiling in saturated liquids under microgravity conditions, thermocapillary convection was never observed, thus indicating uniformity of the temperature along the interface. From this we must conclude that the temperature difference of wall superheat, which generates boiling, cannot be the driving force for the observed thermocapillary flow even in subcooled liquids. Therefore, the question about the origin of this flow arises and is discussed in this paper. PMID:12446335

Straub, Johannes

2002-10-01

47

Film boiling heat transfer from a vertical cylinder in forced flow of liquids under saturated and subcooled conditions at pressures  

Microsoft Academic Search

Forced convection film boiling heat transfer on a vertical 3-mm diameter and 180-mm length platinum test cylinder located in the center of the 40-mm inner diameter test channel was measured. Saturated water, and saturated and subcooled R113 were used as the test liquids that flowed upward along the cylinder in the test channel. Flow velocities ranged from 0 to 3

M. Shiotsu; K. Hama

2000-01-01

48

Deposition of boron on fuel rod surface under sub-cooled boiling conditions—An approach toward understanding AOA occurrence  

Microsoft Academic Search

In PWR primary coolant, it has been assumed that Li and B ions deposited on fuel rod surface under sub-cooled boiling conditions and they changed their chemical forms by chemical reaction with nickel iron oxides on the fuel surface. Accumulated boron on the fuel led to axial offset anomaly (AOA). In the present paper, the amount of boron deposited on

Shunsuke Uchida; Yamato Asakura; Hiroaki Suzuki

2011-01-01

49

An experimental and numerical investigation of post-CHF heat transfer for one-sided heat load with highly sub-cooled flow boiling  

Microsoft Academic Search

One-sided high heat fluxes are very commonly found in fusion reactor plasma facing components for proposed long-pulse devices, such as ITER. Heat fluxes between 5 and 30 MW m?2 are removed by a highly sub-cooled flow of boiling water. For one-sided heat loads, all boiling regimes (single-phase, nucleate, fully developed sub-cooled, transition and film boiling) can be present under a

V. Divavin; V. Tanchuk; A. Shrubok; R. Watson; J. González

1996-01-01

50

Local Heat Transfer and CHF for Subcooled Flow Boiling - Annual Report 1993  

SciTech Connect

Subcooled flow boiling in heated coolant channels is an important heat transfer enhancement technique in the development of fusion reactor components, where high heat fluxes must be accommodated. As energy fluxes increase in magnitude, additional emphasis must be devoted to enhancing techniques such as sub cooling and enhanced surfaces. In addition to subcooling, other high heat flux alternatives such as high velocity helium and liquid metal cooling have been considered as serious contenders. Each technique has its advantages and disadvantages [1], which must be weighed as to reliability and reduced cost of fusion reactor components. Previous studies [2] have set the stage for the present work, which will concentrate on fundamental thermal hydraulic issues associated with the h-international Thermonuclear Experimental Reactor (ITER) and the Engineering Design Activity (EDA). This proposed work is intended to increase our understanding of high heat flux removal alternatives as well as our present capabilities by: (1) including single-side heating effects in models for local predictions of heat transfer and critical heat flux; (2) inspection of the US, Japanese, and other possible data sources for single-side heating, with the aim of exploring possible correlations for both CHF and local heat transfer; and (3) assessing the viability of various high heat flux removal techniques. The latter task includes: (a) sub-cooled water flow boiling with enhancements such as twisted tapes, and hypervapotrons, (b) high velocity helium cooling, and (c) other potential techniques such as liquid metal cooling. This assessment will increase our understanding of: (1) hypervapotron heat transfer via fins, flow recirculation, and flow oscillation, and (2) swirl flow. This progress report contains selective examples of ongoing work. Section II contains an extended abstract, which is part of and evolving technical paper on single-side f heating. Section III describes additional details which will be included in the first year of work. Section IV summarizes past and anticipated international interactions with investigators from other countries. Finally, Section V gives summaries of two conceptual experiments which are planned for the second and third years.

Dr. Ronald D. Boyd

2000-07-01

51

Critical heat fluxes of subcooled water flow boiling in a short vertical tube at high liquid Reynolds number  

Microsoft Academic Search

The steady state critical heat fluxes (CHFs) and the heat transfer of the subcooled water flow boiling for the flow velocities (u=17.2–42.4m\\/s), the inlet subcoolings (?Tsub,in=80.9–147.6K), the inlet pressures (Pin=812.1–1181.5kPa) and the exponentially increasing heat input (Q0exp(t\\/?), ?=8.5s) are systematically measured by the experimental water loop comprised of a new multi-stage canned-type circulation pump with high pump head. The SUS304

Koichi Hata; Suguru Masuzaki

2010-01-01

52

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

NASA Astrophysics Data System (ADS)

To improve the thermal performance of high temperature generator of absorption chiller/heater, heat transfer characteristics of flow boiling of lithium bromide aqueous solution in the subcooled region were experimentally investigated. Experiments were made for water and lithium bromide aqueous solution flowing in a rectangular channel (5 mm × 20 mm cross section) with one side wall heated. Boiling onset quality of lithium bromide aqueous solution is greater than that of water. The heat transfer coefficient of lithium bromide aqueous solution is about a half of that of water under the same experimental conditions of inlet velocity and heat flux. The experimental data of heat transfer coefficient for water are compared with the empirical correlation of Thom et al.11) and a fairly good agreement is obtained. The predictive calculations by the method of Sekoguchi et al.12) are compared with the data for water and lithium bromide aqueous solution. Agreement between them is good for water, while the results for lithium bromide aqueous solution are not satisfactory.

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

53

Complete Numerical Simulation of Subcooled Flow Boiling in the Presence of Thermal and Chemical Interactions  

SciTech Connect

At present, guidelines for fuel cycle designs to prevent axial offset anomalies (AOA) in pressurized water reactor (PWR) cores are based on empirical data from several operating reactors. Although the guidelines provide an ad-hoc solution to the problem, a unified approach based on simultaneous modeling of thermal-hydraulics, chemical, and nuclear interactions with vapor generation at the fuel cladding surface does not exist. As a result, the fuel designs are overly constrained with a resulting economic penalty. The objective of present project is to develop a numerical simulation model supported by laboratory experiments that can be used for fuel cycle design with respect to thermal duty of the fuel to avoid economic penalty, as well as, AOA. At first, two-dimensional numerical simulation of the growth and departure of a bubble in pool boiling with chemical interaction is considered. A finite difference scheme is used to solve the equations governing conservation of mass, momentum, energy, and species concentration. The Level Set method is used to capture the evolving liquid-vapor interface. A dilute aqueous boron solution is considered in the simulation. From numerical simulations, the dynamic change in concentration distribution of boron during the bubble growth shows that the precipitation of boron can occur near the advancing and receding liquid-vapor interface when the ambient boron concentration level is 3,000 ppm by weight. Secondly, a complete three-dimensional numerical simulation of inception, growth and departure of a single bubble subjected to forced flow parallel to the heater surface was developed. Experiments on a flat plate heater with water and with boron dissolved in the water were carried out. The heater was made out of well-polished silicon wafer. Numbers of nucleation sites and their locations were well controlled. Bubble dynamics in great details on an isolated nucleation site were obtained while varying the wall superheat, liquid subcooling and flow velocity parametrically. Concentration variation of boron near the liquid-vapor interface was detected successfully with a newly developed miniature concentration sensor. The measured concentration variations at different radial locations from the center of cavity have the same trend as given by the numerical simulations. The deposition of boron was found near the nucleation site on the heater surface, which validates the numerical simulation. Subcooled flow boiling experiments at three pressures were performed on a nine-rod bundle with water and with boron dissolved in the water. The test runs were conducted with a wide range of mass fluxes (186 to 2800 kg/m2s) and heat fluxes (1.0 to 30.0 W/ cm2). Not only the variables required to develop mechanistic models for subcooled flow boiling were measured, but also the crud formation during boiling and its effect on the heat transfer process were investigated. (B204)

V.K. Dhir

2003-04-28

54

SUBCOOLING DETECTOR  

DOEpatents

A system for detecting and measuring directly the subcooling margin in a liquid bulk coolant is described. A thermocouple sensor is electrically heated, and a small amount of nearly stagnant bulk coolant is heated to the boiling point by this heated thermocouple. The sequential measurement of the original ambient temperature, zeroing out this ambient temperature, and then measuring the boiling temperature of the coolant permits direct determination of the subcooling margin of the ambient liquid. (AEC)

McCann, J.A.

1963-12-17

55

Comparison of FLOWTRAN predictions of onset of significant voiding (OSV) to Savannah River Heat Transfer Laboratory subcooled boiling flow instability measurements, Part 1. Revision 1.  

National Technical Information Service (NTIS)

The onset of flow instability (OFI) was measured in the first of a scheduled series of subcooled boiling tests at the Savannah River Heat Transfer Laboratory (HTL). This report summarizes the benchmarking of predictions of the onset of significant voiding...

J. E. Laurinat

1988-01-01

56

A Procedure to Predict Subcooled-Water-Flow-Boiling CHF in Uniformly Heated Tubes for High-Heat-Flux Applications  

SciTech Connect

A model to predict critical heat flux (CHF) for high-heat-flux subcooled flow boiling in uniformly heated tubes is proposed. The present CHF model is based on the mechanism of wall-attached bubble coalescence. To take into account the enhanced condensation due to high subcooling and high mass velocity in small-diameter tubes, a mechanistic approach is adopted to evaluate the nonequilibrium flow quality and void fraction in the subcooled water flow boiling. Comparison of the model predictions against {approx}3100 subcooled water CHF data shows relatively good agreement over a wide range of parameters that covers the operating conditions of fusion reactor components. The operating ranges of the present database cover 0.33 {<=} D {<=} 37.5 mm, 0.002 {<=} L {<=} 4 m, 0.1 {<=} P {<=} 20 MPa, 0.37 {<=} G {<=} 134 Mg/m{sup 2}.s, 49 {<=} {delta}h{sub sub,in} {<=} 1659 kJ/kg, -1.25 {<=} x{sub em} < 0, and 1.05 {<=} q{sub CHF} {<=} 276 MW/m{sup 2}.

Kwon, Young Min [Korea Atomic Energy Research Institute (Korea, Republic of); Chang, Soon Heung [Korea Advanced Institute of Science and Technology (Korea, Republic of)

2000-06-15

57

Critical heat flux of subcooled flow boiling in swirl tubes relevant to high-heat-flux components  

SciTech Connect

It is necessary to accurately determine the critical heat flux (CHF) of cooling systems used in fusion reactors. Currently, sufficiently accurate CHF correlations for one-sided heating have not been established. A design method for subcooled boiling cooling systems using swirl tubes is described. From a review of existing work under uniform heating conditions, the correlations of Gunther and Nariai-Inasaka are recommended for smooth and swirl flow, respectively. The effects of thermal conductivity and geometry of the cooling sections on both the nouniformity factor and the peaking factor were investigated by solving a heat conduction equation. For swirl flow under one-sided heating, the CHF multiplier increases with the increasing nonuniformity factor. Design criteria for subcooled boiling swirl-tube cooling systems are presented. 33 refs., 13 figs., 4 tabs.

Inasaka, Fujio [Ship Research Inst., Tokyo (Japan); Nariai, Hideki [Univ. of Tsukuba, Ibaraki (Japan)

1996-07-01

58

Modeling and Thermal Performance Evaluation of Porous Curd Layers in Sub-Cooled Boiling Region of PWRs and Effects of Sub-Cooled Nucleate Boiling on Anomalous Porous Crud Deposition on Fuel Pin Surfaces  

SciTech Connect

A significant number of current PWRs around the world are experiencing anomalous crud deposition in the sub-cooled region of the core, resulting in an axial power shift or Axial Offset Anomaly (AOA), a condition that continues to elude prediction of occurrence and thermal/neutronic performance. This creates an operational difficulty of not being able to accurately determine power safety margin. In some cases this condition has required power ''down rating'' by as much as thirty percent and the concomitant considerable loss of revenue for the utility. This study examines two aspects of the issue: thermal performance of crud layer and effect of sub-cooled nucleate boiling on the solute concentration and its influence on initiation of crud deposition/formation on fuel pin surface.

Barclay Jones

2005-06-27

59

Chemical evolution and mineral deposition in boiling hydrothermal systems  

Microsoft Academic Search

A thermodynamic model of boiling hydrothermal solutions is developed and applied over a wide range of physical and chemical conditions. Vaporization of only a few percent of a solution can decrease the proton concentration by several orders of magnitude when the COâ\\/H..mu.. and COâ\\/..sigma..SOâ concentration ratios are initially high. The relationship between the proton, COâ, and ..sigma..SOâ concentrations prior to

S. E. Drummond; H. Ohmoto

1985-01-01

60

Burnout experiment in subcooled forced-convection boiling of water for beam dumps of a high power neutral beam injector  

SciTech Connect

Experimental studies were made on burnout heat flux in highly subcooled forced-convection boiling of water for the design of beam dumps of a high power neutral beam injector for Japan Atomic Energy Research Institute Tokamak-60. These dumps are composed of many circular tubes with two longitudinal fins. The tube was irradiated with nonuniformly distributed hydrogen ion beams of 120 to 200 kW for as long as 10 s. The coolant water was circulated at flow velocities of 3 to 7.5 m/s at exit pressures of 0.4 to 0.9 MPa. The burnout and film-boiling data were obtained at local heat fluxes of 8 to 15 MW/m/sup 2/. These values were as high as 2.5 times larger than those for the circumferentially uniform heat flux case with the same parameters. These data showed insensitivity to local subcooling as well as to pressure, and simple burnout correlations were derived. From these results, the beam dumps have been designed to receive energetic beam fluxes of as high as 5 MW/m/sup 2/ with a margin of a factor of 2 for burnout.

Horiike, Hiroshi; Kuriyama, Masaaki; Morita, Hiroaki

1982-10-01

61

Simulation of void fraction profile evolution in subcooled nucleate boiling flow in a vertical annulus using a bubble-tracking approach  

Microsoft Academic Search

A three-dimensional bubble-tracking model of subcooled nucleate boiling flow in a vertical channel at low-pressure conditions\\u000a is proposed with specific application to the case of boiling in an annulus with a central heating rod. Vapour is distributed\\u000a in the liquid in the form of individually tracked bubbles. The overall behaviour of the liquid–vapour system results from\\u000a motion, interaction, coalescence and

Ivo Kljenak; Borut Mavko

2006-01-01

62

Experimental Investigation on the Effects of Coolant Concentration on Sub-Cooled Boiling and Crud Deposition on Reactor Cladding at Prototypical PWR Operating Conditions  

SciTech Connect

Increasing demand for energy necessitates nuclear power units to increase power limits. This implies significant changes in the design of the core of the nuclear power units, therefore providing better performance and safety in operations. A major hindrance to the increase of nuclear reactor performance especially in Pressurized Deionized water Reactors (PWR) is Axial Offset Anomaly (AOA)--the unexpected change in the core axial power distribution during operation from the predicted distribution. This problem is thought to be occur because of precipitation and deposition of lithiated compounds like boric acid (H{sub 2}BO{sub 3}) and lithium metaborate (LiBO{sub 2}) on the fuel rod cladding. Deposited boron absorbs neutrons thereby affecting the total power distribution inside the reactor. AOA is thought to occur when there is sufficient build-up of crud deposits on the cladding during subcooled nucleate boiling. Predicting AOA is difficult as there is very little information regarding the heat and mass transfer during subcooled nucleate boiling. An experimental investigation was conducted to study the heat transfer characteristics during subcooled nucleate boiling at prototypical PWR conditions. Pool boiling tests were conducted with varying concentrations of lithium metaborate (LiBO{sub 2}) and boric acid (H{sub 2}BO{sub 3}) solutions in deionized water. The experimental data collected includes the effect of coolant concentration, subcooling, system pressure and heat flux on pool the boiling heat transfer coefficient. The analysis of particulate deposits formed on the fuel cladding surface during subcooled nucleate boiling was also performed. The results indicate that the pool boiling heat transfer coefficient degrades in the presence of boric acid and lithium metaborate compared to pure deionized water due to lesser nucleation. The pool boiling heat transfer coefficients decreased by about 24% for 5000 ppm concentrated boric acid solution and by 27% for 5000 ppm lithium metaborate solution respectively at the saturation temperature for 1000 psi (68.9 bar) coolant pressure. Boiling tests also revealed the formation of fine deposits of boron and lithium on the cladding surface which degraded the heat transfer rates. The boron and lithium metaborate precipitates after a 5 day test at 5000 ppm concentration and 1000 psi (68.9 bar) operating pressure reduced the heat transfer rate 21% and 30%, respectively for the two solutions.

Schultis, J., Kenneth; Fenton, Donald, L.

2006-10-20

63

EXPERIMENATL INVESTIGATION OF A SUBCOOLED BOILING IN ONE SIDE OF A HEATED RECTANGULAR CHANNEL  

Microsoft Academic Search

Downcomer boiling phenomena in a conventional pressurized water reactor have an important effect on the transient behavior of a postulated large-break LOCA (LBLOCA), because it can degrade the hydraulic head of the coolant in the downcomer and consequently affect the reflood flow rate for a core cooling. To investigate the thermal hydraulic behavior in the downcomer region, a test program

Byong Jo Yun; Dong Jin Euh; Chul Hwa Song

64

Bubble behavior of high subcooling flow boiling at different system pressure in vertical narrow channel  

Microsoft Academic Search

In the occasion of boiling heat transfer, system pressure has significant effects on the heat transfer characteristics through the impacts on bubble behaviors. In the applications such as nuclear engineering, refrigeration and thermal engineering, depending on the operating conditions, system pressure is the frequent altered parameter to change the work conditions of those facilities. In present work, a visualized study

De-wen Yuan; Liang-ming Pan; Deqi Chen; Hui Zhang; Jing-hua Wei; Yan-ping Huang

2011-01-01

65

Effect of pressure, subcooling, and dissolved gas on pool boiling heat transfer from microporous, square pin-finned surfaces in FC72  

Microsoft Academic Search

The present research is an experimental study of the effects of pressure, subcooling, and non-condensable gas (air) on the pool nucleate boiling heat transfer performance of microporous enhanced finned surfaces. The test surfaces, solid copper blocks with 1-cm2 bases and 5×5 square pin-fin arrays of 2, 4 and 8 mm fin lengths, were immersed in FC-72. The test conditions included

K. N Rainey; S. M You; S Lee

2003-01-01

66

Experimental study of static flow instability in subcooled flow boiling in parallel channels  

SciTech Connect

Experimental data for static flow instability or flow excursion (FE) at conditions applicable to the Advanced Neutron Source Reactor are very limited. A series of FE tests with light water flowing vertically upward was completed covering a local exit heat flux range of 0.7--18 MW/m{sup 2}, exit velocity range of 2.8--28.4 m/s, exit pressure range of 0.117--1.7 MPa, and inlet temperature range of 40-- 50{degrees}C. Most of the tests were performed in a ``stiff`` (constant flow) system where the instability threshold was detected through the minimum of the pressure-drop curve. A few tests were also conducted using as ``soft`` (constant pressure drop) a system as possible to secure a true FE phenomenon (actual secondary burnout). True critical heat flux experiments under similar conditions were also conducted using a stiff system. The FE data reported in this study considerably extend the velocity range of data presently available worldwide, most of which were obtained at velocities below 10 m/s. The Saha and Zuber correlation had the best fit with the data out of the three correlations compared. However, a modification was necessary to take into account the demonstrated dependence of the St and Nu numbers on subcooling levels, especially in the low subcooling regime. Comparison of Thermal Hydraulic Test Loop (THTL) data, as well as extensive data from other investigators, led to a proposed modification to the Saha and Zuber correlation for onset of significant void, applied to FE prediction. The mean and standard deviation of the THTL data were 0.95 and 15%, respectively, when comparing the THTL data with the original Saha and Zuber correlation, and 0.93 and 10% when comparing them with the modification. Comparison with the worldwide database showed a mean and standard deviation of 1.37 and 53%, respectively, for the original Saha and Zuber correlation and 1.0 and 27% for the modification.

Siman-Tov, M.; Felde, D.K.; McDuffee, J.L.; Yoder, G.L.

1995-12-31

67

Heat transfer and bubble detachment in subcooled pool boiling from a downward-facing microheater array in a nonuniform electric field.  

PubMed

The effects of a nonuniform electric field on vapor bubble detachment and heat transfer in subcooled pool boiling from a microheater array are investigated. The heater array faced downward to simulate a -1 g gravity condition and to eliminate the dominant masking effect of the buoyancy force. Experiments were conducted at different subcooling levels for various wall temperatures and electric field magnitudes. A dielectric fluid, FC-72, was used as the working fluid at ambient pressure. The array of 3 x 3 independently controlled microheaters was maintained at constant temperature and the rate of heat transfer from each heater was measured. Bubble images were recorded using a high-speed camera. The electric field was applied between the horizontal downward-facing microheater array, which was grounded, and a spherical, off-axis electrode beneath it. Boiling heat transfer results with and without the electric field are presented in this study. In the absence of the nonuniform electric field, compared to the same bulk fluid temperature and wall superheat settings in the +1 g situation, a much larger primary bubble was formed on the heater array, due to the coalescence of the secondary bubbles that nucleated on the heater array. The vapor bubble remained on the heater array surface and no bubble detachment was observed. With the nonuniform electric field applied, bubbles were lifted and sheared off from the heater array surface. The electric field was able to break up the primary bubble into several smaller bubbles--considerably greater heat transfer enhancement was measured than under similar conditions in +1 g. PMID:19426316

Liu, Zan; Herman, Cila; Kim, Jungho

2009-04-01

68

Mixing vs Boiling process in a shallow submarine hydrothermal system of Bahía Concepción, Mexico  

NASA Astrophysics Data System (ADS)

In this paper we use geochemical modeling and fluid inclusions to support the hypothesis that the main process that undergoes the fluid discharged by submarine vents in Bahia Concepcion is mixing rather than boiling. Mixing modeling of two different fluids: a high salinity fluid that is mixed with a deep thermal fluid of meteoric origin indicate that the thermal water responsible for the formation of the thermal EM of Bahía Concepción is composed by 20-30% of a HDF and 70-80% of a hot DF of meteoric origin. Boiling would be an alternate process; however, fluid inclusions petrography and microthermometry reveal no boiling evidence present in the samples, as breccias, bladed calcite, or coexisting liquid-rich and vapor-rich inclusions. Furthermore, the salinity of pseudosecondary and secondary fluid inclusions is similar to seawater. The mixing model is consistent with fluid inclusion data, which provide evidence that two different hydrothermal fluids are involved in barite deposition at veins related to the submarine manifestations of Bahía Concepción: a low salinity fluid (139°C and 3.2 wt % NaCl eq) and HSF (129°C and 10.6 wt % NaCl eq.) The trend observed between high- to low-salinity fluids shows the occurrence of mixing processes between both hydrothermal fluids.

Villanueva Estrada, R.; Prol-Ledesma, R.; Rodríguez, A.; Canet, C.; Torres, I.; González, E.

2009-12-01

69

Investigation of hydrothermal boiling and steam quenching as possible sources of volcanic tremor and geothermal ground noise  

Microsoft Academic Search

Volcanic tremor and geothermal ground noise are sustained seismic emissions associated with volcanic and geothermal activity. In this study I investigate whether such signals could be caused by boiling or steam quenching in liquid-dominated zones of subterranean hydrothermal systems. The framework for the study is a conceptual model that assumes: (1) the fundamental source of seismic energy is the growth\\/collapse

Leet

1991-01-01

70

A New Facility for Measurements of Three-Dimensional, Local Subcooled Flow Boiling Heat Flux and Related Critical Heat Flux for PFCs  

SciTech Connect

In the development of plasma-facing components for fusion reactors and high-heat-flux heat sinks (or components) for electronic applications, the components are usually subjected to a peripherally nonuniform heat flux. Even if the applied heat flux is uniform in the axial direction (which is unlikely), both intuition and recent investigations have clearly shown that both the local heat flux and the eventual critical heat flux (CHF) in this three-dimensional (3-D) case will differ significantly from similar quantities found in the voluminous body of data for uniformly heated flow channels. Although this latter case has been used in the past as an estimate for the former case, more study has become necessary to examine the 3-D temperature and heat flux distributions and related CHF. Work thus far has shown that the nonuniform peripheral heat flux condition enhances CHF in some cases.To avoid the excess costs associated with using electron or ion beams to produce the nonuniform heat flux, a new facility was developed that will allow 3-D conjugate heat transfer measurements and two-dimensional, local subcooled flow boiling heat flux and related CHF measurements.The configurations under study for this work consist of (a) a nonuniformly heated cylinder-like test section with a circular coolant channel bored through the center and (b) a monoblock that is a square cross-section parallelepiped with a circular drilled flow channel along the channel centerline. The theoretical or ideal cylinder-like test section would be a circular cylinder with half (-90 to 90 deg) of its outside boundary subjected to a uniform heat flux and the remaining half insulated. For the monoblock, a uniform heat flux is applied to one of the outside surfaces, and the remaining surfaces are insulated. The outside diameter of the cylinder-like test section is 30.0 mm, and its length is 200.0 mm. The monoblock square is 30.0 mm long. The inside diameter of the flow channel for both types of test sections is 10.0 mm. Water is the coolant. The inlet water temperature can be set at any level in the range from 26.0 to 130.0 deg. C, and the exit pressure can be set at any level in the range from 0.4 to 4.0 MPa. Thermocouples were placed at 48 locations inside the solid cylinder-like or monoblock test section to obtain 3-D wall temperature variations and related local heat flux. Finally, the mass velocity can be set at any level in the range from 0.4 to 10.0 Mg/m{sup 2}.s for the 10.0-mm-diam channel.

Boyd, Ronald D. Sr.; Cofie, Penrose; Li Qingyuan; Ekhlassi, Ali A

2002-01-15

71

Third heat transfer crisis at subcooling  

Microsoft Academic Search

The effect of liquid subcooling below the saturation temperature on the third heat transfer crisis was studied experimentally\\u000a at pool boiling. Experimental data on the threshold values of superheating and heat fluxes, above which the evaporation front\\u000a and third heat transfer crisis for acetone at subcooling from 0.3 to 10 K are formed, were shown. Formation of evaporation\\u000a fronts is

B. P. Avksentyuk; V. V. Ovchinnikov

2008-01-01

72

Influences of subcooling on burnout of horizontal cylindrical heaters  

SciTech Connect

The peak pool boiling heat flux is observed on horizontal cylindrical heaters in acetone, Freon-113, methanol, and isopropanol over ranges of subcooling from zero to 130C. Photographs, and the data themselves, revealed that there are three distinct burnout mechanisms at different levels of subcooling. Three interpretive models provide the basis for accurate correlations of the present data, and data from the literature, in each of the three regimes. Burnout is dictated by condensation on the walls of the vapor jets and columns at low subcooling. In the intermediate regime, burnout is limited by natural convection, which becomes very effective as vapor near the heater reduces boundary layer resistance. Burnout in the high-subcooling regime is independent of the level of subcooling, and is limited by the process of molecular effusion.

Elkassabgi, Y.; Lienhard, J.H. (Univ. of Houston, TX (USA))

1988-05-01

73

AN EXPERIMENTAL INVESTIGATION ON FLOW BOILING OF ETHYLENE-GLYCOL\\/WATER MIXTURE  

Microsoft Academic Search

Mixtures of ethylene glycol and water are used in cooling the engines in automotive applications. To avoid the two-phase flow in the engine, the mixture is subcooled in the radiator before entering the engine block. Heat transfer is therefore essentially under subcooled flow boiling conditions. Very little information is available in the literature on the subcooled flow boiling characteristics of

Satish G. Kandlikar; Murat Bulut

1999-01-01

74

Boiling incipience and convective boiling of neon and nitrogen  

Microsoft Academic Search

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

S. S. Papell; R. C. Hendricks

1977-01-01

75

Geochemistry of hydrothermal fluids from Axial Seamount Hydrothermal Emissions Study vent field, Juan de Fuca Ridge: Subseafloor boiling and subsequent fluid-rock interaction  

Microsoft Academic Search

Hydrothermal fluids collected from the ASHES vent field in 1986, 1987, and 1988 exhibit a very wide range of chemical composition over a small area (â¼ 60 m in diameter). Compositions range from a 300C, gas-enriched (285 mmol\\/kg COâ), low-chlorinity (â¼ 33% of seawater) fluid to a 328C, relatively gas-depleted (50 mmol\\/kg COâ), high-chlorinity (â¼ 116% of seawater) fluid. The

David A. Butterfield; R. E. McDuff; M. D. Lilley; G. J. Massoth; J. E. Lupton

1990-01-01

76

Local Heat Transfer and CHF for Subcoled Flow Boiling. 1994 Annual Report.  

National Technical Information Service (NTIS)

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 boilin...

R. D. Boyd

1994-01-01

77

Stable isotopic and fluid inclusion indications of large-scale hydrothermal paleoflow, boiling, and fluid mixing in the Keno Hill Ag-Pb-Zn district, Yukon Territory, Canada  

NASA Astrophysics Data System (ADS)

The Keno Hill vein system of the central Yukon is restricted predominantly to the highly fractured, graphitic Keno Hill Quartzite unit of Mississippian age. Hydrothermal mineral zoning is related spatially to a Cretaceous granitic pluton which intrudes the quartzite. During mineralization, the quartzite acted as a district-scale aquifer. Subsequent erosion has exposed a 40-km long vein system, from its plutonic roots, outward to polymetallic Ag-Pb-Zn veins, and further to assemblages of epithermal character. The ?18O quartz values from veins near the pluton increase outwards from +10.6 to +20.1%. as a result of cooling of the hydrothermal fluids and exchange with the quartzite. Contours of isotope values outline broad paths of fluid movement within the quartzite. Proceeding further from the pluton, ?18O quartz values decrease to +10.5%. at the outer edge of the system. The presence of meteoric water is indicated here, where late stage quartz has ?18O SMOW values as low as -7.l%. The outward decreasing trend appears to have been established by mixing of isotopically light meteoric water with exchanged fluids that were in isotopic equilibrium with the quartzite. Fluid inclusions from quartz in the orebodies demonstrate an evolving H 2O-CO 2-NaCl-CH 4 system. Loss of CO 2 and CH 4 during water vaporization coincides with increasing salinity and decreasing temperature resulting from high enthalpy steam loss. Depressurization during active faulting is the principal mechanism. Late stage fluids are represented by dilute aqueous inclusions with lower homogenization temperatures. Quartz from silver-rich veins has been shifted to higher ?18O values, by up to 4%. relative to adjacent silver-poor veins, the result of a minimum 10-25% adiabatic boiling and fractionation dominated by water vaporization and associated cooling. Graphite initially buffered the hydrothermal fluids to a high CO 2 content, with variable CH 4. Involvement of organic carbon from the host rocks is indicated by the negative ?13CPDB values for the carbonates, from -4.0 to -12.9%. Variations in the carbon isotopes result from fluctuating CO 2/CH 4 ratios, reflecting the contrasting volatility of the gas pair. Siderite formed as a late-stage product of the boiling event, and its formation coincides with a decreasing 18O trend in the water created by the equilibration of graphite and water in replacing exsolved CO 2. The formation of CH 4 during this stage had a reducing effect on the fluid, resulting in an increase in ?13C siderite values in association with the decreasing ?18O siderite values. A closed-system boiling model, together with calculations of water consumption during post-boiling CO 2 and CH 4 formation, indicates that greater than 50% of the original water in the ore fluid was removed. Relatively saline mineralizing fluids resulted.

Lynch, J. V. G.; Longstaffe, F. J.; Nesbitt, B. E.

1990-04-01

78

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

Microsoft Academic Search

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

Francisco J. Collado

2005-01-01

79

High flux film and transition boiling  

NASA Astrophysics Data System (ADS)

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

Witte, L. C.

1993-02-01

80

Film boiling on spheres in single- and two-phase flows. Final report  

Microsoft Academic Search

Film boiling on spheres in single- and two-phase flows was studied experimentally and theoretically with an emphasis on establishing the film boiling heat transfer closure law, which is useful in the analysis of nuclear reactor core melt accidents. Systematic experimentation of film boiling on spheres in single-phase water flows was carried out to investigate the effects of liquid subcooling (from

C. Liu; T. G. Theofanous

1994-01-01

81

Film boiling on spheres in single- and two-phase flows  

Microsoft Academic Search

Film boiling on spheres in single- and two-phase flows was studied experimentally and theoretically with an emphasis on establishing the film boiling heat transfer closure law, which is useful in the analysis of nuclear reactor core melt accidents. Systematic experimentation of film boiling on spheres in single-phase water flows was carried out to investigate the effects of liquid subcooling (from

C. Liu; T. G. Theofanous

2000-01-01

82

The Characteristics of Steam Bubbles in Subcooled Boiling Flow  

Microsoft Academic Search

In two-fluid modeling and three-fluid modeling, the accurate prediction of the interfacial area concentration, interfacial heat transfer and interfacial shear stress, were required. In this works, the axial profiles of void fraction, interfacial area concentration and interfacial heat transfer coefficient along the flow direction could be measured. For the steam bubbles whose diameter were less than 8 mm, the interfacial

Takatoshi Takemoto; Asi Bunyajitradulya; Mitsuo Matsuzaki; Hiroshige Kikura; Masanori Aritomi

2002-01-01

83

Microchannel flow boiling mechanisms leading to burnout  

SciTech Connect

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

Landram, C.S.

1994-03-01

84

Incipient boiling superheat and critical heat flux in liquid sodium. Effect of the pre-pressure on the heated surface.  

National Technical Information Service (NTIS)

Incipient boiling superheat and critical heat flux on a horizontal cylinder in liquid sodium have been systematically measured to know effects of the history of experimental condition, the cold-trap temperature, subcooling of the liquid sodium. The effect...

M. Shiotsu Y. Shirai K. Hata Y. Takeuchi K. Hama

1998-01-01

85

Condensing process of a single vapor bubble ejected in subcooled pool  

NASA Astrophysics Data System (ADS)

Behavior of growing/collapsing vapor bubble ejected to subcooled liquid bath was focused. Vapor bubble was produced by vapor generate system. With this system, heated container was carried out temperature control with a thermostat. This system enabled the authors to observe interaction between the vapor and the liquid in the condensing process extracted from the boiling phenomenon consisting of liquid-gas-solid interactions. The bubble behavior was detected by employing a high-speed camera with up to 100,000 fps. The instability emerged over the surface of the growing and collapsing vapor are discussed as functions of the degree of subcooling, and the temperature and ejection speed of vapor. The present study aims to understand and control the micro-bubble emission boiling known as MEB.

Ueno, Ichiro; Arima, Masayuki; Hattori, Yasusuke

86

An analysis of a flat-plate solar collector with internal boiling  

NASA Astrophysics Data System (ADS)

The extended mathematical model of a flat-plate solar collector-evaporator permits prediction of the effects of boiling of the working fluid in the collector tubes on the efficiency of the collector. The efficiency increases sharply and approaches the ideal on transition from single phase flow to the subcooled and saturated boiling regimes, regardless of the nature of the working fluid.

Abramzon, B.; Yaron, I.; Borde, I.

1983-11-01

87

CORRELATION OF VOID FRACTION FOR SANTOWAX-R DURING FORCED CIRCULATION BOILING AT LOW PRESSURE  

Microsoft Academic Search

The void fraction of Santowax-R was determined for nucleate boiling in ; upflow forced circulation. The investigation was conducted to obtain and ; correlate void fraction data for subcooled and bulk boiling in Santowax-R at low ; system pressures. The resulting data are analyzed. (J.R.D.);

F. Bergonzoli; F. J. Halfen

1962-01-01

88

Flow boiling in vertical down-flow  

SciTech Connect

An experimental program has been conducted to investigate the onset of Ledinegg instability in vertical down-flow. For three size uniformly heated test sections with L/D ratios from 100 to 150, the pressure drop under subcooled boiling conditions has been obtained for a wide range of operating parameters. The results are presented in non-dimensional forms which correlate the important variables and provide techniques for predicting the onset of flow instability. 3 refs.

Dougherty, T.; Fighetti, C.; Reddy, G.; Yang, B.; Jafri, T. (Columbia Univ., New York, NY (United States)); McAssey, E. (Villanova Univ., PA (United States)); Qureshi, Z. (Westinghouse Savannah River Co., Aiken, SC (United States))

1989-01-01

89

Flow boiling in vertical down-flow  

SciTech Connect

An experimental program has been conducted to investigate the onset of Ledinegg instability in vertical down-flow. For three size uniformly heated test sections with L/D ratios from 100 to 150, the pressure drop under subcooled boiling conditions has been obtained for a wide range of operating parameters. The results are presented in non-dimensional forms which correlate the important variables and provide techniques for predicting the onset of flow instability. 3 refs.

Dougherty, T.; Fighetti, C.; Reddy, G.; Yang, B.; Jafri, T. [Columbia Univ., New York, NY (United States); McAssey, E. [Villanova Univ., PA (United States); Qureshi, Z. [Westinghouse Savannah River Co., Aiken, SC (United States)

1989-12-31

90

Forced Convection Film Boiling Heat Transfer Over a Vertical Cylinder  

Microsoft Academic Search

The knowledge of subcooled film boiling heat transfer is important as the basis of understanding the reflooding phenomenon during emergency cooling in a nuclear reactor under a loss-of-coolant accident. In this study, forced convection film boiling heat transfer from a vertical cylinder in Freon-113 flowing upward along the cylinder was measured for the flow velocities ranging from 0 to 1.3

Q. S. Liu; K. Fukuda; M. Shiotsu

2011-01-01

91

Modeling of nucleate boiling in engine cylinder head cooling ducts  

Microsoft Academic Search

The merits of various existing 1D models for nucleate subcooled boiling heat transfer are assessed. The implementation of these models is occasionally not straightforward. Some physical inconsistencies have been identified in these models. Surprisingly, the Chen correlation predicts the measurements best, in particular for data sets with heat fluxes in the range of a diesel engine.

J. P. Kroes; Velthooven van E

2008-01-01

92

Chemical reaction path modeling of hydrothermal mineralization in the Tongonan geothermal field, Leyte (Philippines)  

Microsoft Academic Search

The study of hydrothermal processes in an active geothermal system provides an excellent opportunity to test the equilibrium between the hydrothermal mineral assemblage and present-day fluid. Simulations of selected hydrothermal processes in the Tongonan geothermal system were performed to ascertain the effectiveness of different depositional mechanisms for hydrothermal minerals. Hydrothermal processes, such as boiling, fluid mixing and water–rock interaction were

Maria Ines Rosana Balangue-Tarriela

2004-01-01

93

The flow and heat transfer in two-phase double-tube thermosiphons (the effect of subcooling)  

SciTech Connect

An experimental study was performed to investigate the effect of subcooling on the flow and heat transfer in two-phase double-tube thermosiphons with three types of inner tubes using water, ethanol, and Freon 113 as the working fluids. The same experiment for a single-tube thermosiphon was also carried out for comparison. As a result, a correlating expression for the heat-transfer coefficients in two-phase double- and single-tube thermosiphons is presented. The expression presented, by taking account of subcooling and the properties of working fluids, agreed well with the experimental data. The critical heat flux increased slightly with an increase in the degree of subcooling, and the rate of increase for double-tube thermosiphon was bigger than that for the single-tube one. The circulation mass velocity first increased and then decreased, as the heat flux increased. After that, it increased again at a certain heat flux. This behavior was observe for both saturated and subcooled boiling. However, this curve was shifted to the larger heat-flux direction as the degree of sub-cooling increased.

Yoshida, Masamichi; Imura, Hideaki; Ippohshi, Shigetoshi

1994-09-01

94

Thermodynamics of Flow Boiling Heat Transfer  

NASA Astrophysics Data System (ADS)

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

Collado, F. J.

2003-05-01

95

Variability in the microbial communities and hydrothermal fluid chemistry at the newly discovered Mariner hydrothermal field, southern Lau Basin  

Microsoft Academic Search

A newly discovered hydrothermal field called the Mariner field on the Valu Fa Ridge in the southern Lau Basin was explored and characterized with geochemical and microbiological analyses. The hydrothermal fluid discharging from the most vigorous vent (Snow Chimney, maximum discharge temperature 365°C) was boiling at the seafloor at a depth of 1908 m, and two distinct end-member hydrothermal fluids

Ken Takai; Takuro Nunoura; Jun-ichiro Ishibashi; John Lupton; Ryohei Suzuki; Hiroshi Hamasaki; Yuichiro Ueno; Shinsuke Kawagucci; Toshitaka Gamo; Yohey Suzuki; Hisako Hirayama; Koki Horikoshi

2008-01-01

96

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

97

Nonlinear dynamics in horizontal film boiling  

NASA Astrophysics Data System (ADS)

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

Panzarella, Charles Henry

1998-11-01

98

Survey of critical heat flux data for pool boiling of liquid metals and new correlations  

SciTech Connect

Experimental heat transfer data for critical heat flux (CHF) during pool boiling of liquid metals are surveyed. CHF is found to be related to the stability of boiling prior to CHF. A new correlation is given for stable saturated boiling CHF and is shown to give better agreement with data than earlier correlations. This correlation is also applicable to nonmetals. A new correlation is also given for the lower limit of CHF during unstable boiling. Included in the correlation are data on sodium, potassium, cesium, rubidium, and mercury, on plates and cylinders. The limited data available for subcooled CHF are grossly overpredicted by correlations that have been successful for ordinary fluids.

Shah, M.M.

1996-04-01

99

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

100

Effusivity-based correlation of surface property effects in pool boiling CHF of dielectric liquids  

Microsoft Academic Search

Although the effects of fluid properties, pressure, and subcooling, as well as heater geometry, on the pool boiling critical heat flux, or CHF, are relatively well established, explanations for the surface property effects remain controversial. Proposed formulations, embodying the dependence of CHF on the product of the heater thermal effusivity and thickness are described and compared with available data. A

Mehmet Arik; Avram Bar-Cohen

2003-01-01

101

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

Microsoft Academic Search

This work investigated pool boiling of the dielectric liquids HFE-7100 and FC-72 on plane copper and porous graphite and on copper surfaces with corner pins. The work investigated the effects of surface orientation and liquid subcooling and, for the copper surfaces with corner pins, the effect of surface roughness. In addition, investigations were made studying the heat transfer by natural

Jack L. Parker

2008-01-01

102

Hydrothermal Processing  

Microsoft Academic Search

This chapter is a contribution to a book on Thermochemical Conversion of Biomass being edited by Prof. Robert Brown of Iowa State University. It describes both hydrothermal liquefaction and hydrothermal gasification of biomass to fuels.

Douglas C

2011-01-01

103

Mechanisms of steady-state nucleate pool boiling in microgravity.  

PubMed

Research on nucleate pool boiling in microgravity using R-113 as a working fluid was conducted using a five-second drop tower and five space flights at a/g approximately 10(-4). A 19 x 38-mm flat gold film heater was used that allowed cine camera viewing both from the side and the bottom of the heater. It was concluded that for both subcooled and saturated liquids long-term steady-state pool boiling can take place in reduced gravity, but the effectiveness of the boiling heat transfer appears to depend on the heater geometry and on the size and the properties of fluids. Heat transfer is enhanced at lower heat flux levels and the CHF increases as the subcooling increases. It was found that several mechanisms are responsible for the steady-state nucleate pool boiling in the absence of buoyancy. The mechanisms considered here are defined and summarized as bubble removal, bubble coalescence, thermocapillary flow, bubble migration, and latent heat transport. PMID:12446341

Lee, Ho Sung

2002-10-01

104

Sub-cooled water detection in silicon dew point hygrometer  

Microsoft Academic Search

A new type of silicon dew point detector is presented in this paper. The fabricated detector structures contain a thermometer, two heaters, a capacitive interdigitated sensor for the detection of water, sub-cooled water, as well as ice. The test results of sub-cooled water recognition are carefully described. The theoretical model of the capacitive interdigitated sensor describing the principle of detection

R Jachowicz; J Weremczuk

2000-01-01

105

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

Microsoft Academic Search

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

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

1995-01-01

106

Scaling laws and design aspects of a natural-circulation-cooled simulated boiling water reactor fuel assembly  

Microsoft Academic Search

In order to study the thermohydraulic behavior of a natural-circulation-cooled boiling water reactor (BWR) fuel assembly, such as void drift, flow pattern distribution, and stability, a scaled loop geometry is designed. For modeling the steam\\/water flow in a BWR fuel assembly, scaling criteria are derived using the one-dimensional drift-flux model. Thermal equilibrium and subcooled boiling conditions are treated separately, resulting

R. Van De Graaf; T. H. J. J. Van Der Hagen; R. F. Mudde

1994-01-01

107

Dive and Discover's Deeper Discovery: Hydrothermal Vents  

NSDL National Science Digital Library

Dive and Discover is an interactive distance learning web site designed to immerse you in the excitement of discovery and exploration of the deep seafloor. On this particular website, Dive and Discover takes you on a deeper discovery of hydrothermal vents. This site features an introduction to hydrothermal vent systems, including vent basics, vents around the world, chemistry, boiling points, interactive diagrams, videos, a quiz, and links to selected Dive and Discover hydrothermal vent-related seafloor expeditions. This web page also provides links to other Deeper Discovery topics, Dive and Discover seafloor expeditions, a teacher's page, and further Dive and Discover information.

2010-04-12

108

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

109

Boiling Heat Transfer Around a Horizontal Cylinder and in Tube Bundles  

Microsoft Academic Search

From the analysis of a postulated loss-of-coolant and loss-of-emergency cooling accident in a typical horizontal pressure tube nuclear reactor, the need was established for a systematic investigation on the boiling heat transfer coefficient to be expected on a 12.7 cm diameter cylinder and a bundle of these cylinders under saturated and subcooled conditions. To accomplish this, a three-part experimental program

Jules Thibault

1978-01-01

110

Analytical model for the inverted annular film boiling region  

SciTech Connect

Inverted Annular Film Boiling (IAFB) is a phenomenon that is thought to occur during the reflood phase of a loss-of-coolant-accident (LOCA) in a pressurized water reactor. IAFB has been observed in simulated reflood experiments through externally heated quartz tubes. This boiling regime lies immediately upstream of the quench front. It is characterized by a vertical flowing liquid column separated from the hot fuel rods by a very thin vapor film. Its importance derives from the impact it has on the peak fuel rod temperature following a LOCA. This paper reviews past research on IAFB and present a new analytical model. It identifies recent advancements and areas needed for improvements and better understanding. A new analytical model is developed which overcomes some of the earlier shortcomings. Specifically, the new model results in a heat transfer coefficient which accounts for the effect of coolant subcooling and mass flux. Comparisons are made and good agreement is obtained with single tube reflood experiments.

Vreeland, D.G.

1989-01-01

111

Local Heat Transfer and CHF for Subcooled Flow Boiling - Annual Report 1996  

SciTech Connect

For the past decade, efforts have been growing in the development of high heat flux (HHF) components for many applications, including fusion and fission reactor components, advanced electronic components, synchrotrons and optical components, and other advanced HHF engineering applications. From a thermal prospective, work in the fusion reactor development arena has been underway in a number of areas including: (1) Plasma thermal, and electro-magnetics, and particle transport, (2) Fusion material, rheology, development, and expansion and selection; (3) High heat flux removal; and (4) Energy production and efficiency.

Dr. Ronald D. Boyd

2000-07-01

112

Local Heat Transfer and CHF for Subcooled Flow Boiling - Annual Report 1997  

SciTech Connect

The Thermal Science Research Center (TSRC) at Prairie View A&M University is involved in an international fusion reactor technology development program aimed at demonstrating the technical feasibility of magnetic fusion energy. This report highlights: (1) Recent accomplishments and pinpoints thermal hydraulic problem areas of immediate concern to the development of plasma-facing components, and (2) Next generation thermal hydraulic problems which must be addressed to insure safety and reliability in component operation. More specifically, the near-term thermal hydraulic problem entails: (1) generating an appropriate data base to insure the development of single-side heat flux correlations, and (2) evaluating previously developed single-side/uniform heated transformations and correlations to determine which can be used to relate the vast two-phase heat transfer and critical heat flux (CHF) technical literature for uniformly heated flow channels to single-side heated channels.

Dr. Ronald D. Boyd

2000-07-01

113

Subcooled water critical pressure and critical flow rate in a safety valve  

Microsoft Academic Search

Subcooled water critical flow phenomena in a safety valve are investigated experimentally at various subcoolings between 10 and 125 K, and about 1 MPa of the inlet pressure with three different disk lifts, 1, 2, and 3 mm. The purpose of this experiment is to find the effects of subcooling and disk lift and to visualize flow patterns in a

Se Won Kim; Hee Cheon No

2001-01-01

114

Applying mechanical subcooling to ejector refrigeration cycle for improving the coefficient of performance  

Microsoft Academic Search

This paper describes a new ejector refrigeration system with mechanical subcooling which uses an auxiliary liquid–gas ejector to enhance subcooling for the refrigerant from condenser. The new system can have larger subcooling degree when circulating pump consumes a little more power compared with conventional ejector refrigeration system. Based on the built mathematical model, the performance of the new ejector refrigeration

Jianlin Yu; Yunfeng Ren; Hua Chen; Yanzhong Li

2007-01-01

115

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

NASA Astrophysics Data System (ADS)

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

Furukawa, Masahiro; Enomoto, Eiichi; Sekoguchi, Kotohiko

116

Evaporation, Boiling and Bubbles  

ERIC Educational Resources Information Center

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

Goodwin, Alan

2012-01-01

117

A simple boiling module  

Microsoft Academic Search

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

Theodore Kim; Mark Carlson

2007-01-01

118

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

119

Macro-to-microchannel transition in two-phase flow: Part 2 – Flow boiling heat transfer and critical heat flux  

Microsoft Academic Search

This part of the paper presents the current experimental flow boiling heat transfer and CHF data acquired for R134a, R236fa and R245fa in single, horizontal channels of 1.03, 2.20 and 3.04mm diameters over a range of experimental conditions. The aim of this study is to investigate the effects of channel confinement, heat flux, flow pattern, saturation temperature, subcooling and working

C. L. Ong; J. R. Thome

2011-01-01

120

Evaluation of subcooled critical heat flux correlations using the PU-BTPFL CHF database for vertical upflow of water in a uniformly heated round tube  

SciTech Connect

A simple methodology for assessing the predictive ability of critical heat flux (CHF) correlations applicable to subcooled flow boiling in a uniformly heated vertical tube is developed. Popular correlations published in handbooks and review articles as well as the most recent correlations are analyzed with the PU-BTPFL CHF database, which contains 29,718 CHF data points. This database is the largest collection of CHF data (vertical upflow of water in a uniformly heated round tube) ever cited in the world literature. The parametric ranges of the CHF database are diameters from 0.3 to 45 mm, length-to-diameter ratios from 2 to 2484, mass velocities from 0.01 {times} 10{sup 3} to 138 {times} 10{sup 3} kg/m{sup 2}{center_dot}s, pressures from 1 to 223 bars, inlet subcoolings from 0 to 347 C, inlet qualities from {minus}2.63 to 0.00, outlet subcoolings from 0 to 305 C, outlet qualities from {minus}2.13 to 1.00, and CHFs from 0.05 {times} 10{sup 6} to 276 {times} 10{sup 6} W/m{sup 2}. The database contains 4,357 data points having a subcooled outlet condition at CHF. A correlation published elsewhere is the most accurate in both low- and high-mass velocity regions, having been developed with a larger database than most correlations. In general, CHF correlations developed from data covering a limited range of flow conditions cannot be extended to other flow conditions without much uncertainty.

Hall, D.D.; Mudawar, I. [Purdue Univ., West Lafayette, IN (United States)

1997-02-01

121

The hydrothermal system of Nevado del Ruiz volcano, Colombia  

Microsoft Academic Search

Hot springs and steam vents on the slopes of Nevado del Ruiz volcano provide evidence regarding the nature of hydrothermal activity within the summit and flanks of the volcano. At elevations below 3000 m, alkali-chloride water is discharged from two groups of boiling springs and several isolated warm springs on the western slope of Nevado del Ruiz. Chemical and isotopic

Neil C. Sturchio; Stanley N. Williams; Nestor P. Garcia; Adela C. Londono

1988-01-01

122

Analogue modeling of instabilities in crater lake hydrothermal systems  

Microsoft Academic Search

We carried out analogue experiments on two-phase boiling systems, using a porous vertical cylinder, saturated with water. The base of the cylinder was heated, and the top was cooled, as in a natural hydrothermal system. Previous work had shown that once the two-phase zone reached a certain level, thermal instabilities would develop. We made measurements of the acoustic energy related

Jean Vandemeulebrouck; Didier Stemmelen; Tony Hurst; Jacques Grangeon

2005-01-01

123

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

124

SATURATED-SUBCOOLED STRATIFIED FLOW IN HORIZONTAL PIPES  

SciTech Connect

Advanced light water reactor systems are designed to use passive emergency core cooling systems with horizontal pipes that provide highly subcooled water from water storage tanks or passive heat exchangers to the reactor vessel core under accident conditions. Because passive systems are driven by density gradients, the horizontal pipes often do not flow full and thus have a free surface that is exposed to saturated steam and stratified flow is present.

Richard Schultz

2010-08-01

125

Odd-Boiled Eggs  

ERIC Educational Resources Information Center

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

Kaminsky, Kenneth; Scheman, Naomi

2010-01-01

126

Odd-Boiled Eggs  

ERIC Educational Resources Information Center

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

Kaminsky, Kenneth; Scheman, Naomi

2010-01-01

127

Critical flashing flows in nozzles with subcooled inlet conditions  

SciTech Connect

Examination of a large number of experiments dealing with flashing flows in converging and converging-diverging nozzles reveals that knowledge of the flashing inception point is the key to the prediction of critical flow rates. An extension of the static flashing inception correlation of Jones (16) and Alamgir and Lienhard (17) to flowing systems has allowed the determination of the location of flashing inception in nozzle flows with subcooled inlet conditions. It is shown that in all the experiments examined with subcooled inlet regardless of the degree of inlet subcooling, flashing inception invariably occurred very close to the throat. A correlation is given to predict flashing inception in both pipes and nozzles which matches all data available, but is lacking verification in intermediate nozzle geometries where turbulence may be important. A consequence of this behavior is that the critical mass flux may be correlated to the pressure difference between the nozzle inlet and flashing inception, through a single phase liquid discharge coefficient and an accurate prediction of the flashing inception pressure at the throat. Comparison with the available experiments indicate that the predicted mass fluxes are within 5 percent of the measurements.

Abuaf, N.; Jones, O.C. Jr.; Wu, B.J.C.

1983-05-01

128

An experimental investigation of critical flow rates of subcooled water through short pipes with small diameters  

Microsoft Academic Search

Critical two-phase flow rates of subcooled water through short pipes (L < 400 mm) with small diameters (D < 7.15 mm) have been experimentally investigated for wide ranges of subcooling (0 ? 199 °C) and pressure (0.5 ? 2.0 MPa). To examine the effects of various parameters (i.e., the location of flashing inception, the degree of subcooling, the stagnation temperature

Jee-Won Park; C. K. Park; J. W. Park

1996-01-01

129

Cryogenic system with the sub-cooled liquid nitrogen for cooling HTS power cable  

Microsoft Academic Search

A 10m long, three-phase AC high-temperature superconducting (HTS) power cable had been fabricated and tested in China August 2003. The sub-cooled liquid nitrogen (LN2) was used to cool the HTS cable. The sub-cooled LN2 circulation was built by means of a centrifugal pump through a heat exchanger in the sub-cooler, the three-phase HTS cable cryostats and a LN2 gas–liquid separator.

Y. F. Fan; L. H. Gong; X. D. Xu; L. F. Li; L. Zhang; L. Y. Xiao

2005-01-01

130

Momentum effects in steady nucleate pool boiling during microgravity.  

PubMed

Pool boiling experiments were conducted in microgravity on five space shuttle flights, using a flat plate heater consisting of a semitransparent thin gold film deposited on a quartz substrate that also acted as a resistance thermometer. The test fluid was R-113, and the vapor bubble behavior at the heater surface was photographed from beneath as well as from the side. Each flight consisted of a matrix of three levels of heat flux and three levels of subcooling. In 26 of the total of 45 experiments conditions of steady-state pool boiling were achieved under certain combinations of heat flux and liquid subcooling. In many of the 26 cases, it was observed from the 16-mm movie films that a large vapor bubble formed, remaining slightly removed from the heater surface, and that subsequent vapor bubbles nucleate and grow on the heater surface. Coalescence occurs upon making contact with the large bubble, which thus acts as a vapor reservoir. Recently, measurements of the frequencies and sizes of the small vapor bubbles as they coalesced with the large bubble permitted computation of the associated momentum transfer. The transient forces obtained are presented here. Where these arise from the conversion of the surface energy in the small vapor bubble to kinetic energy acting away from the solid heater surface, they counter the Marangoni convection due to the temperature gradients normal to the heater surface. This Marangoni convection would otherwise impel the large vapor bubble toward the heater surface and result in dryout and unsteady heat transfer. PMID:15644357

Merte, Herman

2004-11-01

131

Physical interpretation of geysering phenomena and periodic boiling instability at low flows  

SciTech Connect

Over 30 years ago, Griffith showed that unstable and periodic initial boiling occurred in stagnant liquids in heated pipes coupled to a cooler or condensing plenum volume. This was called ``geysering``, and is a similar phenomenon to the rapid nucleation and voiding observed in tubes filled with superheated liquid. It is also called ``bumping`` when non-uniformly heated water or a chemical suddenly boils in laboratory glassware. In engineering, the stability and predictability has importance to the onset of bulk boiling in a natural and forced circulation loops. The latest available data show the observed stability and periodicity of the onset of boiling flow when there is a plenum, multiple heated channels, and a sustained subcooling in a circulating loop. We examine the available data, both old and new, and develop a new theory to illustrate the simple physics causing the observed periodicity of the flow. We examine the validity of the theory by comparison to all the geysering data, and develop a useful and simple correlation. We illustrate the equivalence of the onset of geysering to the onset of static instability in subcooled boiling. We also derive the stability boundary for geysering, utilizing turbulent transport analysis to determine the effects of pressure and other key parameters. This new result explains the greater stability region observed at higher pressures. The paper builds on the 30 years of quite independent thermal hydraulic work that is still fresh and useful today. We discuss the physical interpretation of geysering onset with a consistent theory, and show where refinements would be useful to the data correlations.

Duffey, R.B.; Rohatgi, U.S.

1996-03-01

132

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

133

Critical discharge of initially subcooled water through slits. [PWR; BWR  

SciTech Connect

This report describes an experimental investigation into the critical flow of initially subcooled water through rectangular slits. The study of such flows is relevant to the prediction of leak flow rates from cracks in piping, or pressure vessels, which contain sufficient enthalpy that vaporization will occur if they are allowed to expand to the ambient pressure. Two new analytical models, which allow for the generation of a metastable liquid phase, are developed. Experimental results are compared with the predictions of both these new models and with a Fanno Homogeneous Equilibrium Model.

Amos, C N; Schrock, V E

1983-09-01

134

Critical flashing flows in nozzles with subcooled inlet conditions  

NASA Astrophysics Data System (ADS)

A unified theory is presented for the calculation of critical mass flow rates through converging-diverging nozzles with subcooled inlets. It is shown that the correlation of flashing inception leads to the determination that flashing onset occurs virtually at the throat (plane of minimum flow area) in nozzles. It is also shown how this observation, coupled with an accurate prediction for the under-pressure at inception based on Alagmir and Lienhard (1979), leads directly to an accurate computation of the critical discharge rates in nozzles. The mass fluxes predicted on the basis of the proposed theory are within 5 percent of the measurements.

Abuaf, N.; Jones, O. C., Jr.; Wu, B. J. C.

1983-05-01

135

Optical method of sub-cooled water recognition in dew point hygrometer  

Microsoft Academic Search

A new optical method of sub-cooled water recognition in dew point hygrometer is presented. The physical phenomenon of sub-cooled water and its influence on the hygrometer accuracy is described. A hypothesis relating scattering of light by water and ice layers is proposed. A new type of dew point hygrometer based on the silicone mirror with the embedded capacitive detector and

Jerzy Weremczuk

2000-01-01

136

Electrical Breakdown Characteristics of Superconducting Magnet System in Sub-Cooled Liquid Nitrogen  

Microsoft Academic Search

Dielectric characteristics of gaseous helium (GHe) injected into the cooling system to make sub-cooled nitrogen condition with constant pressure is found to be extraordinarily weak in dielectric strength by H. Mitsuii (1998). In high voltage superconducting machines using the sub-cooled nitrogen cooling system, the current lead part in GHe environment could be electrical weak points rather than the superconducting magnet

Hyoungku Kang; Chanjoo Lee; Tae Kuk Ko; Bok-Yeol Seok

2007-01-01

137

Destabilization of film boiling  

Microsoft Academic Search

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

S. G. Bankoff

1980-01-01

138

Initiation of Water Hammer in Horizontal or Nearly-Horizontal Pipes Containing Steam and Subcooled Water.  

National Technical Information Service (NTIS)

Water slug formation in a stratified countercurrent flow of steam and subcooled water in a horizontal or nearly horizontal pipe traps a large steam bubble, which then collapses rapidly and causes a water hammer. This water hammer initiating mechanism has ...

R. W. Bjorge

1983-01-01

139

Steam-air mixture condensation in a subcooled water pool  

NASA Astrophysics Data System (ADS)

In any conceptual reactor design under postulated accidental conditions, one parameter that is considered as being highly ranked in determining the thermal-hydraulic conditions of the reactor safety components is the system pressure. To obtain a satisfactory prediction of steam partial pressure, within reasonable uncertainty in the gas space of a confined SP (suppression pool) bounded to the steam source of the break flow, one must establish a means by which local phenomena associated with steam direct contact condensation in the subcooled water pool can be fully addressed to predict the global component thermal response. For this purpose a scaled down, reduced pressure, suppression pool was designed and built to study condensation and mixing phenomena. The scaled test facility represented an idealized trapezoidal cross section, 1/10 sector of the SP with scaled height ratio of 1/4.5 and volume ratio of 1/400. The design and test conditions were based on a hierarchical scaling principle that preserves the transfer of mass, momentum, energy and condensation phenomena. Distributed thermocouples within the pool provided a means to quantify the pool thermal response. The test loop was not only instrumented with thermocouples for monitoring pool stratification but also with high speed photography for flow visualization from which to build a comprehensive database to identify the regions of the pool that were thermally stratified or mixed. Data were obtained for different pool initial subcooling and steam/air mixture flow rates. Dimensionless boundary maps were plotted from several experimental runs of pure steam injection to determine conditions when the pool transits from being homogeneously mixed to being thermally stratified. Steam-air mixture injection cases for single horizontal venting indicated that above a pool temperature of 40°C with airmass flow rates below 0.1 g/s the pool can attain thermal stratification. Models of a single phase liquid-into-liquid buoyant jet and a two-phase vapor-into-liquid turbulent jet plume injected in horizontal orientation were developed from the Reynolds averaged Navier-Stokes equations in the cylindrical system for steady axisymmetric flow and incorporated the integral plume theory. The two-phase simplified model developed to predict the pool surface temperature to within less than 0.5°C in the majority of cases.

Norman, Timothy Linhurst

140

Film boiling on spheres in single- and two-phase flows.  

SciTech Connect

Film boiling on spheres in single- and two-phase flows was studied experimentally and theoretically with an emphasis on establishing the film boiling heat transfer closure law, which is useful in the analysis of nuclear reactor core melt accidents. Systematic experimentation of film boiling on spheres in single-phase water flows was carried out to investigate the effects of liquid subcooling (from 0 to 40 C), liquid velocity (from 0 to 2 m/s), sphere superheat (from 200 to 900 C), sphere diameter (from 6 to 19 mm), and sphere material (stainless steel and brass) on film boiling heat transfer. Based on the experimental data a general film boiling heat transfer correlation is developed. Utilizing a two-phase laminar boundary-layer model for the unseparated front film region and a turbulent eddy model for the separated rear region, a theoretical model was developed to predict the film boiling heat transfer in all single-phase regimes. The film boiling from a sphere in two-phase flows was investigated both in upward two-phase flows (with void fraction from 0.2 to 0.65, water velocity from 0.6 to 3.2 m/s, and steam velocity from 3.0 to 9.0 m/s) and in downward two-phase flows (with void fraction from 0.7 to 0.95, water velocity from 1.9 to 6.5 m/s, and steam velocity from 1.1 to 9.0 m/s). The saturated single-phase heat transfer correlation was found to be applicable to the two-phase film boiling data by making use of the actual water velocity (water phase velocity), and an adjustment factor of (1 - {alpha}){sup 1/4} (with a being the void fraction) for downward flow case only. Slight adjustments of the Reynolds number exponents in the correlation provided an even better interpretation of the two-phase data. Preliminary experiments were also conducted to address the influences of multi-sphere structure on the film boiling heat transfer in single- and two-phase flows.

Liu, C.; Theofanous, T. G.

2000-08-29

141

Effect of solid subcooling on natural convection melting of a pure metal  

SciTech Connect

A combined experimental and numerical study is reported of melting of a pure metal inside a vertical rectangular enclosure with natural convection in the liquid and conduction in the solid. The numerical model is successfully verified by conducting a series of experiments covering a wide range of hot and cold wall temperatures. It is found that solid subcooling significantly reduces the melting rate when compared to melting with the solid at the fusion temperature. Because the cooled wall is held below the fusion temperature of the metal, the solid/liquid interface eventually reaches a stationary position. For moderate values of the subcooling parameter the steady-state interface is almost vertical and parallel to the cold wall. Strong subcooling results in an early termination of the melting process, such that natural convection in the relatively small liquid region cannot fully develop. For moderate subcooling, correlations have been derived for the steady-state volume and heat transfer rates. While many aspects of melting with solid subcooling appear to be similar to ordinary nonmetallic solids, important differences in the local flow structures and heat transfer mechanisms are observed.

Beckermann, C. (Univ. of Iowa, Iowa City (United States)); Viskanta, R. (Purdue Univ., West Lafayette, IN (United States))

1989-05-01

142

Probability of Film Boiling Burnout.  

National Technical Information Service (NTIS)

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

R. H. Towell

1966-01-01

143

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

144

Flow Boiling and Condensation Experiment  

NASA Video Gallery

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

Kristine Rainey

2013-01-11

145

Experimental investigation of film boiling on spheres using high-speed video  

NASA Astrophysics Data System (ADS)

The experimental investigation of saturated Freon-113 film boiling on spheres with different diameters at atmospheric pressure under conditions of free convection is executed. It was found that with increasing diameter of the sphere and the temperature difference is changing the wave motion of the vapor film with two-dimensional to three-dimensional mode. Also, found that in a range of regime parameters at which observed a three-dimensional interface motion, the destruction method of two-dimensional wave is similar to a series of three or more waves. I.e. was some system memory. When the temperature difference close to critical after the passage of a wave are possible the local contacts of liquid with a heated surface of the sphere. However, these contacts do not lead to degradation of the wave motion of the interface, and the film boiling crisis of saturated Freon-113 occurs smoothly in contrast to the crisis at boiling of saturated and subcooled water.

Agaltsov, Andrey; Fedoseenko, Ivan

2012-04-01

146

On the subcooled critical flow model in RELAP5/MOD3  

SciTech Connect

An analysis of an anomaly in the subcooled critical flow model in the RELAP5/MOD3 computer code is presented. Specifically, the code produces a discontinuity in going from unchoked subcooled liquid flow (i.e., subsonic flow) to subcooled choked flow (i.e., sonic flow). The same anomaly has been reported elsewhere. The root cause for this anomaly has been analyzed, and it is found that the user-supplied junction loss coefficient and discharge coefficient play an important role in the occurrence of this anomaly. The analysis is verified by assessment against a test problem simulating single-phase liquid flow through a convergent nozzle with a fixed upstream pressure and a varying downstream pressure. A corrective measure to eliminate the discontinuity is suggested.

Yeung, W.S.; Shirkov, J. [Yankee Atomic Electric Co., Bolton, MA (United States)

1996-04-01

147

Dynamics of a two-dimensional vapor bubble confined between superheated or subcooled parallel plates.  

PubMed

The dynamics of a long, two-dimensional vapor bubble confined in the gap between two superheated or subcooled parallel plates is analyzed theoretically. The unsteady expansion and/or contraction of the bubble is driven by mass transfer between the liquid and the vapor. The analysis uses the approach developed by Wilson [J. Fluid Mech. 391, 1 (1999)] for a situation with "large" gaps and "small" superheating or subcooling to consider a situation with small gaps and large superheating or subcooling in which the mass transfer from or to the semicircular nose of the bubble is comparable to that from or to the thin liquid films on the plates. In order to permit a (semi-) analytical treatment the analysis is restricted to low Prandtl number liquids. When both plates are superheated the bubble always expands. In this case there are two possible constant-velocity continuous-film solutions for the expansion of the bubble, namely, an unstable fast mode and a stable slow mode. The evolution of the bubble is calculated numerically for a range of values of the parameters. In particular, these calculations show that eventually the bubble expands either with the constant velocity of the slow mode or exponentially. When both plates are subcooled the bubble always collapses to zero length in a finite time. When one plate is subcooled and the other plate is superheated the situation is rather more complicated. If the magnitude of the subcooling is less than that of the superheating then if the magnitude of the subcooling is greater than a critical value then a variety of complicated behaviors (including the possibility of an unexpected "waiting time" behavior in which the bubble remains almost stationary for a finite period of time) can occur before the bubble eventually collapses to a finite length in an infinite time, whereas if it is less than this critical value then the bubble always expands and eventually does so exponentially. If the magnitude of the subcooling is greater than that of the superheating then the bubble always collapses to zero length in a finite time. PMID:20481834

Das, Kausik S; Wilson, Stephen K

2010-04-22

148

The hydrothermal system of the Calabozos caldera, central Chilean Andes  

USGS Publications Warehouse

Active thermal springs associated with the late Pleistocene Calabozos caldera complex occur in two groups: the Colorado group which issues along structures related to caldera collapse and resurgence, and the Puesto Calabozos group, a nearby cluster that is chemically distinct and probably unrelated to the Colorado springs. Most of the Colorado group can be related to a hypothetical parent water containing ???400 ppm Cl at ???250??C by dilution with ???50% of cold meteoric water. The thermal springs in the most deeply eroded part of the caldera were derived from the same parent water by boiling. The hydrothermal system has probably been active for at least as long as 300,000 years, based on geologic evidence and calculations of paleo-heat flow. There is no evidence for economic mineralization at shallow depth. The Calabozos hydrothermal system would be an attractive geothermal prospect were its location not so remote. ?? 1987.

Grunder, A. L.; Thompson, J. M.; Hildreth, W.

1987-01-01

149

Heat transfer in a pipe under asymmetric heating under conditions of forced motion of subcooled liquid  

Microsoft Academic Search

Results are given of experimental investigations of heat transfer under conditions of forced convection of highly subcooled\\u000a water in a smooth pipe and with an internal twisted tape under asymmetric heating. A brief description is given of the approximate\\u000a model for the calculation of temperature fields, which simplifies the processing of experimental data

A. T. Komov; A. S. Barashkov; A. N. Varava; A. V. Dedov; A. S. Shcheglov

2000-01-01

150

Effect of solid subcooling on natural convection melting of a pure metal  

Microsoft Academic Search

A combined experimental and numerical study is reported of melting of a pure metal inside a vertical rectangular enclosure with natural convection in the liquid and conduction in the solid. The numerical model is successfully verified by conducting a series of experiments covering a wide range of hot and cold wall temperatures. It is found that solid subcooling significantly reduces

C. Beckermann; R. Viskanta

1989-01-01

151

An experimental analysis of subcooled leakage flow through slits from high pressure high temperature pipelines  

Microsoft Academic Search

The work presented here is an experimental investigation of the critical flashing flow of initially subcooled water through circumferential slits in pipes. The study provides first hand information about the prediction of leak flow rates in piping and pressure vessels retaining high temperature and high pressure. The dedicated experimental facility loop simulates the thermal hydraulic condition of Pressurized Heavy Water

Sandip Ghosh; Deb Mukhopadhyay; Samir Kumar Saha

2011-01-01

152

Initiation of water hammer in horizontal or nearly-horizontal pipes containing steam and subcooled water  

NASA Astrophysics Data System (ADS)

Water slug formation in a stratified countercurrent flow of steam and subcooled water in a horizontal or nearly horizontal pipe which traps a large steam bubble which then collapses rapidly and causes a water hammer is discussed. This water hammer initiating mechanism was studied.

1983-02-01

153

Study on condensation of a single vapor bubble into subcooled water-Part 2; Experimental analysis  

Microsoft Academic Search

This paper reports experimental analyses performed for the results of flow visualization in which saturated steam bubbles approximately 10 mm in diameter were injected into quiescent subcooled water. The patterns of bubble collapse were analyzed from photographs selected from a motion picture film and presented as the instantaneous bubble diameter vs. time. An upward motion was imparted to the bubbles

S. Kamei; M. Hirata

1990-01-01

154

Some Factors Affecting the Metering of Subcooled Water with a Choked Venturi.  

National Technical Information Service (NTIS)

A series of experiments was performed to characterize the subcooled choking process in a convergent-divergent nozzle with a constant-area throat. The experiments were conducted in a low-pressure flow loop capable of a maximum water flow rate of 5.5 L/s wi...

J. R. Fincke D. R. Collins

1981-01-01

155

A Compact Cryocooling System With Subcooled Liquid Nitrogen for Small HTS Magnets  

Microsoft Academic Search

A compact cryogenic cooling system is developed for small HTS magnets to be continuously refrigerated in subcooled liquid nitrogen at temperatures below 77 K by a cryocooler. This thermal design is particularly useful when electrical insulation and compactness are significant at the same time. HTS elements are immersed in a cylindrical liquid-nitrogen vessel, and a copper band is brazed around

Ho-Myung Chang; Min-Jee Kim; Jung Wook Sim; Bang-Wook Lee; Il-Sung Oh

2008-01-01

156

The study of passive flow control device performance at low inlet subcooling  

NASA Astrophysics Data System (ADS)

Passive flow control devices (PFCDs) are normally used for flow measurement and flow regulation in many liquid flow systems. The typical PFCDs are venturis, orifices, nozzles, and capillary tubes. The PFCDs have several advantages over active flow control valves in thermal-fluid systems. They require no electrical power, data, command signal for operation and are not subject to wear or breakage, as well as the need of feedback control. When liquid flow venturi cavitates, it has the ability to passively control the flow in thermal-fluid systems at the choked flow regime. However, when the cavitating venturi (CV) operates at low value of inlet subcooling to conserve electrical power, an all-liquid overflow phenomenon can occur. If cavitation cannot be guaranteed in CV, then the constant flow rate performance of CV could not be obtained. Then, the CV may not be the best choice for the thermal-fluid control systems. For this reason, the main objective of this study is to evaluate the performance of possible PFCDs at low inlet subcooling. Experiments were performed for the alternate PFCDs of orifice, nozzle, and capillary tube at low levels of inlet subcooling in order to explore the physical phenomena of the PFCD relevant to their operation parameters. The test results of PFCDs are compared with CV's performance, and recommendations are made for the best type of passive flow control device at low inlet subcooling for the industrial and aerospace thermal-fluid control system applications.

Liou, S. G.; Chen, I. Y.; Chang, S. K.

1999-01-01

157

Measurement of partial discharge inception characteristics in sub-cooled liquid nitrogen  

NASA Astrophysics Data System (ADS)

Partial discharge (PD) measurement is one of the effective diagnostic techniques to predict abnormal high voltage dielectric insulation conditions of the electric equipments. PD diagnostic techniques were also could be utilized to evaluate the conditions of cryogenic dielectric insulation media of high temperature superconducting electric equipment in liquid nitrogen. Generally, liquid nitrogen at 77 K is used as cryogenic and dielectric media for high temperature superconducting devices for high voltage electric power systems. But due to generation of bubbles during quench conditions which cause harmful effect on the properties of liquid nitrogen insulation, sub-cooled nitrogen under 77 K was also employed to suppress bubble formation. In this work, investigation of PD characteristics of sub-cooled liquid nitrogen was conducted in order to clarify the relation between PD inception and the temperature of liquid nitrogen. It was observed that measured PDIV (PD inception voltage) shows little differences according to the sub-cooled temperature of liquid nitrogen, but the magnitude and total numbers of PD has been slightly decreased according the decrease of cooled temperature of liquid nitrogen. From experimental results, it was deduced that the sub-cooled liquid nitrogen from 68 K to 77 K, could be applicable without any considerations of the variation of PDIV.

Koo, J. Y.; Lee, S. H.; Shin, W. J.; Khan, Umer A.; Oh, S. H.; Seong, J. K.; Lee, B. W.

2011-11-01

158

Bacteria at Hydrothermal Vents  

NSDL National Science Digital Library

This website provides information on thermophiles living in deep-sea vents, including their importance in biotechnology and extraterrestrial life research. The site also contains images of thermophiles at varying scales and a link to the "Hot Topics" main page including numerous links to further information on hydrothermal vents and research conducted in deep-sea environments.

Discover, Expeditions T.; Woods Hole Oceanographic Institution, National S.

159

Hydrothermal pretreatment of coal  

SciTech Connect

We are examining the effects on composition and behavior of Argonne-supplied Wyodak coal under both thermal (no added water/N{sub 2}) and hydrothermal (liquid water/N{sub 2}) conditions at 350{degree}C for periods of 30 min and 5 hr, with emphasis during this period on the longer treatment. Field ionization mass spectrometry (FIMS) of the untreated, thermally treated, and hydrothermally treated coals is conducted at conditions where the samples are heated from ambient to 500{degree}C at 2.5{degree}/min. In the 5 hr work the volatilities of the coals are 24%, 16%, and 25% respectively. Solvent swelling studies with the recovered coals do not demonstrate the expected lower degree of crosslinking in the hydrothermal case. Both the thermal and hydrothermal treatments yield products with a decreased swelling ratio, but the ratio for the product from the aqueous treatment is slightly lower than that from thermal treatment. At present we cannot reconcile this result with our other data. 4 refs., 6 figs.

Loo, Bock; Ross, D.S.

1990-08-14

160

Hydrothermal carbonization of microalgae  

Microsoft Academic Search

Hydrothermal carbonization is a process in which biomass is heated in water under pressure to create a char product. With higher plants, the chemistry of the process derives primarily from lignin, cellulose and hemicellulose components. In contrast, green and blue-green microalgae are not lignocellulosic in composition, and the chemistry is entirely different, involving proteins, lipids and carbohydrates (generally not cellulose).

Steven M. Heilmann; H. Ted Davis; Lindsey R. Jader; Paul A. Lefebvre; Michael J. Sadowsky; Frederick J. Schendel; Marc G. von Keitz; Kenneth J. Valentas

2010-01-01

161

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

162

"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

163

Thermosyphon boiling in vertical channels  

Microsoft Academic Search

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

A. Bar-Cohen; H. Schweitzer

1983-01-01

164

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

165

Effect of inclination on film boiling  

Microsoft Academic Search

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

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

1974-01-01

166

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

167

Boiling from the top and sides of a protruding simulated electronic chip  

NASA Astrophysics Data System (ADS)

Nucleate boiling and critical heat flux from the top and side surfaces of a block protruding into a rectangular channel has been studied. A dielectric fluorocarbon, FC-72 (3M Industrial Chemical Products Division) was used as a heat transfer fluid. Heat transfer, and thus boiling from the sides of the block is virtually eliminated by the use of a thin (0.025 mm) foil heater. Single-phase heat transfer and critical heat flux are markedly greater for a protrusion height of 0.71 mm as compared to results for a flush surface. This increase is seen for flow velocities greater than 1 m/s and a subcooling of 20 C. The results are compared to that for a copper block heated from below under similar fluid and geometry constraints. Additional results for the copper block with heat transfer from the front face obstructed were obtained. Conclusions pertaining to the direct immersion cooling of practical electronic chip configurations are made.

Leland, J. E.; Chow, L. C.

1993-07-01

168

Thermosyphon boiling in vertical channels  

NASA Astrophysics Data System (ADS)

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

Bar-Cohen, A.; Schweitzer, H.

169

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.

170

Study on condensation of a single vapor bubble into subcooled water-Part 2; Experimental analysis  

SciTech Connect

This paper reports experimental analyses performed for the results of flow visualization in which saturated steam bubbles approximately 10 mm in diameter were injected into quiescent subcooled water. The patterns of bubble collapse were analyzed from photographs selected from a motion picture film and presented as the instantaneous bubble diameter vs. time. An upward motion was imparted to the bubbles by buoyancy, and because of heat transfer and condensation at the liquid-vapor interface, the bubbles diminished in size as they ascended. The time variations of the bubble diameter and position were determined from detailed analysis of the photographs. The experiments were performed for pressure levels from atmospheric to 10{sup 6}Pa and for temperature differences between the saturated steam and subcooled water from 10 to 70{degrees}C. From these, the time for bubbler collapse and the average heat transfer coefficient are inferred.

Kamei, S.; Hirata, M. (Faculty of Engineering, Univ. of Tokyo (JP))

1990-01-01

171

A phenomenological model of the thermal hydraulics of convective boiling during the quenching of hot rod bundles  

SciTech Connect

In this paper, a phenomenological model of the thermal hydraulics of convective boiling in the post-critical-heat-flux (post-CHF) regime is developed and discussed. The model was implemented in the TRAC-PF1/MOD2 computer code (an advanced best-estimate computer program written for the analysis of pressurized water reactor systems). The model was built around the determination of flow regimes downstream of the quench front. The regimes were determined from the flow-regime map suggested by Ishii and his coworkers. Heat transfer in the transition boiling region was formulated as a position-dependent model. The propagation of the CHF point was strongly dependent on the length of the transition boiling region. Wall-to-fluid film boiling heat transfer was considered to consist of two components: first, a wall-to-vapor convective heat-transfer portion and, second, a wall-to-liquid heat transfer representing near-wall effects. Each contribution was considered separately in each of the inverted annular flow (IAF) regimes. The interfacial heat transfer was also formulated as flow-regime dependent. The interfacial drag coefficient model upstream of the CHF point was considered to be similar to flow through a roughened pipe. A free-stream contribution was calculated using Ishii's bubbly flow model for either fully developed subcooled or saturated nucleate boiling. For the drag in the smooth IAF region, a simple smooth-tube correlation for the interfacial friction factor was used. The drag coefficient for the rough-wavy IAF was formulated in the same way as for the smooth IAF model except that the roughness parameter was assumed to be proportional to liquid droplet diameter entrained from the wavy interface. The drag coefficient in the highly dispersed flow regime considered the combined effects of the liquid droplets within the channel and a liquid film on wet unheated walls. 431 refs., 6 figs., 4 tabs.

Nelson, R.A.; Unal, C.

1991-01-01

172

Compact counter-flow cooling system with subcooled gravity-fed circulating liquid nitrogen  

NASA Astrophysics Data System (ADS)

A liquid nitrogen (LN2) is usually used to keep the high-temperature superconducting (HTS) cable low temperature. A pump is utilized to circulate LN2 inside the cryopipes. In order to minimize heat leakage, a thermal siphon circulation scheme can be realized instead. Here, we discuss the effectiveness of thermal siphon with counter-flow circulation loop composed of cryogen flow channel and inner cable channel. The main feature of the system is the existence of essential parasitic heat exchange between upwards and downwards flows. Feasibility of the proposed scheme for cable up to 500 m in length has been investigated numerically. Calculated profiles of temperature and pressure show small differences of T and p in the inner and the outer flows at the same elevation, which allows not worrying about mechanical stability of the cable. In the case under consideration the thermal insulating properties of a conventional electrical insulating material (polypropylene laminated paper, PPLP) appear to be sufficient. Two interesting effects were disclosed due to analysis of subcooling of LN2. In case of highly inclined siphon subcooling causes significant increase of temperature maximum that can breakup of superconductivity. In case of slightly inclined siphon high heat flux from outer flow to inner flow causes condensation of nitrogen gas in outer channel. It leads to circulation loss. Results of numerical analyses indicate that counter-flow thermosiphon cooling system is a promising way to increase performance of short-length power transmission (PT) lines, but conventional subcooling technique should be applied carefully.

Ivanov, Yu.; Radovinsky, A.; Zhukovsky, A.; Sasaki, A.; Watanabe, H.; Kawahara, T.; Hamabe, M.; Yamaguchi, S.

2010-11-01

173

Fugacity coefficients of H sub 2 , CO sub 2 , CH sub 4 , H sub 2 O and of H sub 2 O-CO sub 2 -CH sub 4 mixtures: A virial equation treatment for moderate pressures and temperatures applicable to calculations of hydrothermal boiling  

SciTech Connect

Equations derived from a quadratic virial equation in pressure, with virial coefficients expressed as a function of temperature, are fitted to published P-V-T and solubility data to yield values of second and third virial coefficients for pure and mixed gases. These coefficients are not virial coefficients sensu stricto and are used to compute fugacity coefficients of pure H{sub 2}, H{sub 2}O, CO{sub 2} and CH{sub 4}, and of mixed H{sub 2}O, CO{sub 2} and CH{sub 4}, and to estimate enthalpies for these gases. For H{sub 2}, the P-T range of application is from 25 to 600 C and up to 3,000 bars, and for CH{sub 4}, from 16 to 350 C and up to 500 bars. For H{sub 2}O and CO{sub 2}, two P-T ranges are considered: below 350C, up to 500 bars, and from 450 to 1,000 C, up to 1,000 bars. The method presented here is limited to the P-T range of the fitted experimental data, and cannot represent accurately P-V-T data close to the critical region. This virial equation treatment yields simple analytical expressions that are suitable for multicomponent equilibrium calculations. Examples of equilibrium calculations between aqueous and gas phases show that ideal mixing of real gases is a sufficient approximation for modeling boiling in geothermal and epithermal systems. However, non-ideal mixing has to be considered for aqueous-gas systems at pressures much higher than the saturation pressure of pure water.

Spycher, N.F.; Reed, M.H. (Univ. of Oregon, Eugene (USA))

1988-03-01

174

Does Hydrothermal Circulation Matter?  

NASA Astrophysics Data System (ADS)

Determining Earth's energy budget and the sources and mechanisms for heat transfer within it depends largely on assumptions of the heat loss from the formation and cooling of oceanic lithosphere, which covers about 60% of Earth's surface. Recently Hofmeister and Criss (2005) have suggested that the total global heat flow is about 30 TW, about 25% less than previously estimated by Pollack et al. (1993). The main difference between the two estimates is whether the effects of heat transfer by hydrothermal circulation are included. Thermal models describe the evolution of the lithosphere by the conductive cooling of hot material as it moves away from spreading centers. The frequently used half-space (boundary layer) and "plate" models generally successfully represent heat flow, depth, and geoid values with age, and depth-dependent properties such as flexural thickness, maximum depth of intraplate earthquakes, and lithospheric thickness. However, such models overpredict the measured heat flow from ridge crest to about 65 Myr crust. This difference is generally assumed to reflect water flow in the crust transporting heat, as shown by the spectacular hot springs at midocean ridges. If so, the observed heat flow is lower than the model's predictions, which assume that all heat is transferred by conduction. Because hydrothermal heat transport is hard to quantify, heat flow is about 50% larger than directly measured. This estimate is consistent with observations of hydrothermal circulation which indicate that the discrepancy is largely a result of the water fluxing along the oceanic basement and upwelling at isolated basement highs and outcrops. Detailed studies at such areas often show high heat flow near these outcrops and low heat flow in the surrounding areas. Hence isolated measurements are biased towards lower values and underpredict the total heat flow.

Stein, C. A.; Stein, S.; von Herzen, R. P.; Fisher, A. T.

2006-05-01

175

Biocatalytic transformations of hydrothermal fluids  

NASA Astrophysics Data System (ADS)

The occurrence of copious animal populations at deep-sea vents indicates an effective microbial chemosynthetic biocatalysis of hydrothermal fluids on their emission into oxygenated ambient seawater. The large metabolic and physiological diversity of microbes found at these sites, including anaerobic and aerobic hyperthermophiles, reflects an even higher variety of biocatalytic or enzymatic reactions that greatly influence deep-sea hydrothermal geochemistry.

Jannasch, H. W.

176

Hydrothermal Liquefaction of Biomass  

SciTech Connect

Hydrothermal liquefaction technology is describes in its relationship to fast pyrolysis of biomass. The scope of work at PNNL is discussed and some intial results are presented. HydroThermal Liquefaction (HTL), called high-pressure liquefaction in earlier years, is an alternative process for conversion of biomass into liquid products. Some experts consider it to be pyrolysis in solvent phase. It is typically performed at about 350 C and 200 atm pressure such that the water carrier for biomass slurry is maintained in a liquid phase, i.e. below super-critical conditions. In some applications catalysts and/or reducing gases have been added to the system with the expectation of producing higher yields of higher quality products. Slurry agents ('carriers') evaluated have included water, various hydrocarbon oils and recycled bio-oil. High-pressure pumping of biomass slurry has been a major limitation in the process development. Process research in this field faded away in the 1990s except for the HydroThermal Upgrading (HTU) effort in the Netherlands, but has new resurgence with other renewable fuels in light of the increased oil prices and climate change concerns. Research restarted at Pacific Northwest National Laboratory (PNNL) in 2007 with a project, 'HydroThermal Liquefaction of Agricultural and Biorefinery Residues' with partners Archer-Daniels-Midland Company and ConocoPhillips. Through bench-scale experimentation in a continuous-flow system this project investigated the bio-oil yield and quality that could be achieved from a range of biomass feedstocks and derivatives. The project was completed earlier this year with the issuance of the final report. HydroThermal Liquefaction research continues within the National Advanced Biofuels Consortium with the effort focused at PNNL. The bench-scale reactor is being used for conversion of lignocellulosic biomass including pine forest residue and corn stover. A complementary project is an international collaboration with Canada to investigate kelp (seaweed) as a biomass feedstock. The collaborative project includes process testing of the kelp in HydroThermal Liquefaction in the bench-scale unit at PNNL. HydroThermal Liquefaction at PNNL is performed in the hydrothermal processing bench-scale reactor system. Slurries of biomass are prepared in the laboratory from whole ground biomass materials. Both wet processing and dry processing mills can be used, but the wet milling to final slurry is accomplished in a stirred ball mill filled with angle-cut stainless steel shot. The PNNL HTL system, as shown in the figure, is a continuous-flow system including a 1-litre stirred tank preheater/reactor, which can be connected to a 1-litre tubular reactor. The product is filtered at high-pressure to remove mineral precipitate before it is collected in the two high-pressure collectors, which allow the liquid products to be collected batchwise and recovered alternately from the process flow. The filter can be intermittently back-flushed as needed during the run to maintain operation. By-product gas is vented out the wet test meter for volume measurement and samples are collected for gas chromatography compositional analysis. The bio-oil product is analyzed for elemental content in order to calculate mass and elemental balances around the experiments. Detailed chemical analysis is performed by gas chromatography-mass spectrometry and 13-C nuclear magnetic resonance is used to evaluate functional group types in the bio-oil. Sufficient product is produced to allow subsequent catalytic hydroprocessing to produce liquid hydrocarbon fuels. The product bio-oil from hydrothermal liquefaction is typically a more viscous product compared to fast pyrolysis bio-oil. There are several reasons for this difference. The HTL bio-oil contains a lower level of oxygen because of more extensive secondary reaction of the pyrolysis products. There are less amounts of the many light oxygenates derived from the carbohydrate structures as they have been further reacted to phenolic Aldol condensation products. The bio-oil

Elliott, Douglas C.

2010-12-10

177

Cody hydrothermal system  

SciTech Connect

The hot springs of Colter's Hell are the surface manifestations of a much larger hydothermal system. That system has been studied to define its extent, maximum temperature, and mechanism of operation. The study area covers 2700 km/sup 2/ (1040 mi/sup 2/) in northwest Wyoming. Research and field work included locating and sampling the hot springs, geologic mapping, thermal logging of available wells, measuring thermal conductivities, analyzing over 200 oil and gas well bottom-hole temperatures, and compiling and analyzing hydrologic data. These data were used to generate a model for the hydrothermal system.

Heasler, H.P.

1982-01-01

178

EHD enhancement of nucleate boiling. [Electrohydrodynamic  

SciTech Connect

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

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

1990-05-01

179

Boiling radial flow in fractures of varying wall porosity  

Microsoft Academic Search

The focus of this report is the coupling of conductive heat transfer and boiling convective heat transfer, with boiling flow in a rock fracture. A series of experiments observed differences in boiling regimes and behavior, and attempted to quantify a boiling convection coefficient. The experimental study involved boiling radial flow in a simulated fracture, bounded by a variety of materials.

Robb Allan Barnitt; Robb Allan

2000-01-01

180

The Driving Force of Frost Boils and Hummocks Formation  

Microsoft Academic Search

Formation of frost boils has several aspects to be explained, including the bowl shape of boils, the formation of an organic layer at the periphery of the frost boils, the elevated center of the boils, and resistance of the soil surface to vegetation colonization. Genesis of frost boils and hummocks have been widely attributed to cryoturbation-a complex of seasonally interchanging

Y. Shur; C. Ping

2003-01-01

181

Process for upgrading high-boiling hydrocarbonaceous materials  

Microsoft Academic Search

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

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

1991-01-01

182

Hydrothermal processes at seafloor spreading centers,  

SciTech Connect

This chapter discusses the initial entry of hydrothermal seawater into deep levels of the oceanic crust, the effectiveness of hydrothermal circulation in cooling the crust, the geometry of hydrothermal circulation, the relationship between the hydrothermal circulation and the magma chamber, the reaction of the oceanic crust with the seawater, and the identification of the hydrothermal fluid which alters a rock sample. Topics considered include the crack front, observation relevant to the crack front, the limitations of the crack front hypothesis, the observed pattern of hydrothermal alteration, the nature of the hydrothermal fluid, the physics of large scale convection, and convection through crack zones. Knowledge of hydrothermal circulation at the ridge axis is based on sampling of the hydrothermal fluid, indirect geophysical measurements of the oceanic crust, and studies of rocks which are believed to have undergone hydrothermal alteration at the ridge axis. Includes 2 drawings.

Sleep, N.H.

1983-01-01

183

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

184

21 CFR 872.6710 - Boiling water sterilizer.  

Code of Federal Regulations, 2010 CFR

...2009-04-01 2009-04-01 false Boiling water sterilizer. 872.6710 Section... Miscellaneous Devices § 872.6710 Boiling water sterilizer. (a) Identification. A boiling water sterilizer is an AC-powered...

2009-04-01

185

POOL BOILING OF HIGH-FREQUENCY CONDUCTORS  

Microsoft Academic Search

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

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

2001-01-01

186

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

187

Modeling Hydrothermal Vents on Europa  

NASA Astrophysics Data System (ADS)

Simulations of potential hydrothermal vents at Europa's ocean floor are presented. The effects of differing initial rock composition and temperature are explored with respect to mineral formation and vent fluid composition.

Gavin, P.; Vance, S.

2012-03-01

188

Migration of hydrothermal systems in an evolving collisional orogen, New Zealand  

NASA Astrophysics Data System (ADS)

The Pacific-Australian tectonic plate boundary through the South Island of New Zealand consists of the transpressional Southern Alps mountain belt and the transcurrent Marlborough Fault System, both of which have active tectonically driven hydrothermal systems, with topographically driven meteoric incursion and warm springs. The Southern Alps hydrothermal system is relatively diffuse, with little or no fault control, and is channelled through scattered extensional sites beneath the mountains, where gold mineralisation is occurring locally. The hydrothermal activity along the Marlborough Fault System is controlled by the principal faults in well-defined valleys separated by narrow high ridges. Lateral evolution of Marlborough fault strands southwestwards into the Southern Alps has caused diversion of diffuse Southern Alps hydrothermal activity into the structural superimposition zone, where fluid flow is increasingly being controlled by faults. This hydrothermal diversion was accompanied by major topographic reorientation and river drainage reversal in the late Quaternary. Vein swarms now exposed in the remnants of the Southern Alps north of the superimposition zone formed at shallow levels, with some evidence for fluid boiling, from a mixture of meteoric and deep-sourced fluid. These veins, some of which contain gold, are part of an abandoned <1 million-year-old hydrothermal zone beneath the fossil topographic divide of the Southern Alps that has now been dismembered by lateral incursion of the Marlborough fault strands. Observations on this active plate boundary provide some insights into processes that controlled orogenic gold mineralisation in ancient belts, particularly with respect to relationships between hydrothermal fluid flow, structure and topography.

Craw, D.; Upton, P.; Horton, T.; Williams, J.

2013-02-01

189

Spray cooling heat-transfer with subcooled trichlorotrifluoroethane (Freon-113) for vertical constant heat flux surfaces  

SciTech Connect

Experiments were done using subcooled Freon-113 sprayed vertically downward. Local and average heat transfers were investigated fro Freon-113 sprays with 40 C subcooling, droplet sizes 200-1250{mu}m, and droplet breakup velocities 5-29 m/s. Full-cone type nozzles were used to generate the spray. Test assemblies consisted of 1 to 6 7.62 cm vertical constant heat flux surfaces parallel with each other and aligned horizontally. Distance between heated surfaces was varied from 6.35 to 76.2 mm. Steady state heat fluxes as high as 13 W/cm{sup 2} were achieved. Dependence on the surface distance from axial centerline of the spray was found. For surfaces sufficiently removed from centerline, local and average heat transfers were identical and correlated by a power relation of the form seen for normal-impact sprays which involves the Weber number, a nondimensionalized temperature difference, and a mass flux parameter. For surfaces closer to centerline, the local heat transfer depended on vertical location on the surface while the average heat transfer was described by a semi-log correlation involving the same parameters. The heat transfer was independent of the distance (gap) between the heated surfaces for the gaps investigated.

Kendall, C.M. [Lawrence Livermore National Lab., CA (United States); Holman, J.P. [Southern Methodist Univ., Dallas, TX (United States). Dept. of Mechanical Engineering

1996-06-06

190

Boiling Heat Transfer to Halogenated Hydrocarbon Refrigerants  

NASA Astrophysics Data System (ADS)

The current state of knowledge on heat transfer to boiling refrigerants (halogenated hydrocarbons) in a pool and flowing inside a horizontal tube is reviewed with an emphasis on information relevant to the design of refrigerant evaporators, and some recommendations are made for future research. The review covers two-phase flow pattern, heat transfer characteristics, correlation of heat transfer coefficient, influence of oil, heat transfer augmentation, boiling from tube-bundle, influence of return bend, burnout heat flux, film boiling, dryout and post-dryout heat transfer.

Yoshida, Suguru; Fujita, Yasunobu

191

Silica Transport and Distribution in Saline, Immiscible Fluids: Application to Subseafloor Hydrothermal Systems  

NASA Astrophysics Data System (ADS)

Quartz is a nearly ubiquitous gangue mineral in hydrothermal mineral deposits, most often constituting the bulk of hydrothermal mineralization. The dissolution, transport and precipitation of quartz is controlled by the solubility of silica; in particular, in hot hydrothermal fluids in contact with quartz, silica saturation can generally be assumed, as rates of dissolution and precipitation are generally much faster than fluid flow rates. The solubility of silica in aqueous fluids can be used to understand the evolution of hydrothermal systems by tracing the silica distribution in these systems through time. The solubility of quartz in an aqueous fluid is dependent upon the pressure, temperature and composition (PTX) of the fluid. Silica solubility in pure water as a function of pressure and temperature is well understood. However, natural fluids contain variable amounts of dissolved ionic species, thus it is necessary to include the effects of salinity on silica solubility to accurately predict quartz distribution in hydrothermal systems. In particular, addition of NaCl results in enhanced quartz solubility over a wide range of PT conditions. Furthermore, if phase separation occurs in saline fluids, silica is preferentially partitioned into the higher salinity brine phase; if vapor is removed from the system, the bulk salinity in the system evolves towards the brine end member, and overall silica solubility is enhanced. There is abundant evidence from natural fluid inclusions for fluid immiscibility in hydrothermal ore deposits. Additionally, recent hydrothermal models that include fluid phase equilibria effects predict that phase separation may be an important control on the distribution of dissolved components in seafloor hydrothermal systems. An empirical equation describing the solubility of silica in salt-bearing hydrothermal solutions over a wide range of PTX conditions has been incorporated into a multiphase fluid flow model for seafloor hydrothermal systems to predict the evolution of silica distribution in time and space in these systems. Preliminary runs illustrate a significant effect of salinity in the evolving and boiling system on silica solubility. The model predicts that silica solubility is progressively enhanced in the two-phase liquid-plus-vapor region as brine is concentrated by the preferential loss of vapor. The model also predicts that there is a narrow region of intense quartz deposition in the deep part of the upflow zone, where the fluid reenters the one-phase field. The model currently treats the wallrock as an infinite quartz reservoir, but future work will fully couple the quartz solubility and fluid flow models, to allow porosity adjustment and resultant permeability evolution by quartz dissolution and precipitation. This work was supported in part by the Institute for Critical Technology and Applied Sciences (ICTAS) at Virginia Tech

Steele-Macinnis, M.; Bodnar, R. J.; Lowell, R.; Rimstidt, J. D.

2009-05-01

192

Liquid CO2 venting on the seafloor: Yonaguni Knoll IV hydrothermal system, Okinawa Trough  

NASA Astrophysics Data System (ADS)

In 2000, an active hydrothermal site, venting high-temperature fluid up to 300 oC, was discovered by Shinkai 6500 on the top of Yonaguni Knoll IV during YK 00-06 cruise in Okinawa Trough. During the subsequent subseafloor survey using Shinkai 6500 in 2003 (YK03-05), vents of liquid CO2 droplets were found at the site. Similar liquid CO2 droplets had previously been found at the active hydrothermal sites at JADE hydrothermal field, Okinawa Trough, during the extensive seafloor survey using submersibles in 1989 [Sakai et al., 1990]. Besides, similar liquid CO2 venting has also been recognized in NW Eifuku hydrothermal site on Izu-Bonin- Mariana arc. It thus appears that liquid CO2 venting might be usual phenomenon in some submarine arc volcanoes. The detailed relation between seafloor venting liquid CO2 and the surrounding high-temperature hydrothermal fluid, however, was not clarified in their studies. Furthermore, no definite evidence was obtained for the presence of CO2-hydrate in the subsurface. In this study, in order to discuss the subseafloor processes responsible for producing liquid CO2 at the Yonaguni Knoll IV site, as well as the possibility of the occurrence of solid CO2-hydrate within the sediments, we determined the chemical and isotopic compositions of the liquid CO2 found on the site, as well as those in hydrothermal fluid venting from the surrounding chimneys. In consequence, the ^13C of both CO2 and CH4 in the liquid CO2 almost coincide with those in the hydrothermal fluid, suggesting that the liquid CO2 must be derived from the hydrothermal fluid. While showing homogeneous ^13C, the hydrothermal fluids exhibit wide variation in gas contents. Active phase separation must be taking place within the conduits. Besides, H2-depletion in the liquid CO2 suggests formation of solid CO2-hydrate must also precede the venting of liquid CO2. In conclusion, liquid CO2 must be produced through following subseafloor processes: phase separation of hydrothermal fluid due to boiling, formation of solid CO2- hydrate due to cooling of vapor phase, and melting of the solid CO2-hydrate to liquid CO2 due to a temperature increase within the sedimentary layer.

Konno, U.; Tsunogai, U.; Nakagawa, F.; Nakaseama, M.; Ishibashi, J.; Nunoura, T.; Nakamura, K.

2006-12-01

193

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

194

Experimental Study on the Electrical Breakdown Characteristics of Sub-Cooled Liquid Nitrogen for Designing a High Voltage Superconducting Machine  

Microsoft Academic Search

The electrical breakdown characteristics of liquid nitrogen should be investigated for developing of a high voltage superconducting machine. This paper deals with the experimental study for the verification of dielectric characteristics of sub-cooled in accordance with utilization factors. AC dielectric experiments were carried out by using sphere-plane electrode systems. The utilization factors of simulated electrode systems were controlled by gap

Jin Bae Na; Hyoungku Kang; Young Jin Hwang; Seong Eun Yang; Dong Keun Park; Duck Kweon Bae; Tae Kuk Ko

2010-01-01

195

Mechanisms of Boiling in Microchannels: Critical Assessment  

NASA Astrophysics Data System (ADS)

Numerous characteristic trends and effects have been observed in published studies on two-phase micro-channel boiling heat transfer. While macro-scale flow boiling heat transfer may be decomposed into nucleate and convective boiling contributions, at the micro-scale the extent of these two important mechanisms remains unclear. Although many experimental studies have proposed nucleate boiling as the dominant micro-scale mechanism, based on the strong dependence of the heat transfer coefficient on the heat flux similar to nucleate pool boiling, they fall short when it comes to actual physical proof. A strong presence of nucleate boiling is reasonably associated to a flow of bubbles with sizes ranging from the microscopic scale to the magnitude of the channel diameter. The bubbly flow pattern, which well adapts to this description, is observed however only over an extremely limited range of low vapor qualities (typically for x <0.01-0.05). Furthermore, at intermediate and high vapor qualities, when the flow assumes the annular configuration and a convective behavior is expected to dominate the heat transfer process, the experimental evidence yields entirely counter intuitive results, with heat transfer coefficients often decreasing with increasing vapor quality rather than increasing as in macro-scale channels, and with a much diminished heat flux dependency as would be expected. In summary, convective boiling in micro-channels has revealed to be much more complex than originally thought. The present review aims at describing and analyzing the boiling mechanisms that have been proposed for two-phase micro-channel flows, confronting them with the available experimental heat transfer results, while highlighting those questions that, to date, remain unanswered.

Thome, J. R.; Consolini, L.

196

Hadronic matter near the boiling point  

Microsoft Academic Search

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

Rolf Hagedorn

1968-01-01

197

Hydrothermal pretreatment of coal  

SciTech Connect

We have examined changes in Argonne Premium samples of Wyodak coal following 30 min treatment in liquid water at autogenous pressures at 150{degrees}, 250{degrees}, and 350{degrees}C. In most runs the coal was initially dried at 60{degrees}C/1 torr/20 hr. The changes were monitored by pyrolysis field ionization mass spectrometry (py-FIMS) operating at 2.5{degrees}C/min from ambient to 500{degrees}C. We recorded the volatility patterns of the coal tars evolved over that temperature range, and in all cases the tar yields were 25%--30% of the starting coal on mass basis. There was essentially no change after the 150{degrees}C treatment. Small increases in volatility were seen following the 250{degrees}C treatment, but major effects were seen in the 350{degrees} work. The tar quantity remained unchanged; however, the volatility increased so the temperature of half volatility for the as-received coal of 400{degrees}C was reduced to 340{degrees}C. Control runs with no water showed some thermal effect, but the net effect from the presence of liquid water was clearly evident. The composition was unchanged after the 150{degrees} and 250{degrees}C treatments, but the 350{degrees} treatment brought about a 30% loss of oxygen. The change corresponded to loss of the elements of water, although loss of OH'' seemed to fit the analysis data somewhat better. The water loss takes place both in the presence and in the absence of added water, but it is noteworthy that the loss in the hydrothermal runs occurs at p(H{sub 2}O) = 160 atm. We conclude that the process must involve the dehydration solely of chemically bound elements of water, the dehydration of catechol is a specific, likely candidate.

Ross, D.S.

1989-12-21

198

Hydrothermal dealumination of faujasites  

SciTech Connect

Two faujasites (USY and REY) were hydrothermally treated at temperatures between 400 and 850/sup 0/C in 100% steam and up to 65 h to induce dealumination. The Al expulsion from the zeolite lattice was followed by X-ray diffraction (XRD) and by /sup 29/Si and /sup 27/Al nuclear magnetic resonance (NMR) spectroscopy. Both techniques showed large changes in crystal structure in less than 30 min while crystallinity losses were kept below 15% at temperatures up to 500/sup 0/C. The Al expulsion from the zeolite lattice is accompanied by Al diffusion through the channel network to the zeolite particle surface. The surface enrichment by Al was quantitatively measured by X-ray photoelectron spectroscopy (XPS or ESCA). The diffusion of Al to the particle surface takes place only in the presence of steam and the migrating species is speculated to be a hydroxylated Al ion. These studies were complemented by secondary ion mass spectrometry (SIMS) and scanning transmission electron microscopy (STEM). SIMS analysis demonstrated a very large enrichment of Al in the top 30 A of steamed zeolites. STEM measurements of Si/Al profiles on 800 A-thick microtomed sections confirmed the SIMS data, but indicated broader, less steep changes in the Si/Al ratio across zeolite particles. Because dealumination causes both structural changes (shrinkage of unit cell) and chemical changes (decrease in acidity) in a zeolite, it has profound implications on catalyst performance and on catalyst deactivation. For instance, dealuminated faujasites exhibit drastically reduced coking rates in the cumene cracking test reaction which is discussed in some detail.

Fleisch, T.H.; Meyers, B.L.; Ray, G.J.; Hall, J.B.; Marshall, C.L.

1986-05-01

199

Visualizational study on nucleate pool boiling phenomena  

NASA Astrophysics Data System (ADS)

It is important to visualize the intricate bubble behavior and the strong agitation of liquid near the heating surface to clarify the details concerning boiling mechanism. The visualization of nucleate pool boiling phenomena was confirmed by means of shadowgraphy using a still- camera (Nikon Photomic Camera) with the speed of 2000 frames per second. Illumination was provided by a photo spotlight or a stroboscope. The photographs show that the boiling phenomena and bubbles' behavior are varied for the heat flux of nucleate pool boiling based on the experiments. By considering the effect of revolving angle and the influence of a space between a tube and a tube, experiments have been carried out to investigate the nucleate pool boiling phenomena on horizontal stainless-steel-multi-tube in saturated distilled water. These experiments were performed for atmospheric pressure, for a stainless-tube diameter of 1.0 mm for a length of 80 mm, for a region of natural convection to nucleate boiling near burnout. From these results, photographs show that the successive motion and shape of bubbles during their process of detachment on the heating tube surface varied with increasing heat flux.

Kamei, Shuya

1993-01-01

200

Experimental studies of adiabatic flow boiling in fractal-like branching microchannels  

SciTech Connect

Experimental results of adiabatic boiling of water flowing through a fractal-like branching microchannel network are presented and compared to numerical model simulations. The goal is to assess the ability of current pressure loss models applied to a bifurcating flow geometry. The fractal-like branching channel network is based on channel length and width ratios between adjacent branching levels of 2{sup -1/2}. There are four branching sections for a total flow length of 18 mm, a channel height of 150 {mu}m and a terminal channel width of 100 {mu}m. The channels were Deep Reactive Ion Etched (DRIE) into a silicon disk. A Pyrex disk was anodically bonded to the silicon to form the channel top to allow visualization of the flow within the channels. The flow rates ranged from 100 to 225 g/min and the inlet subcooling levels varied from 0.5 to 6 C. Pressure drop along the flow network and time averaged void fraction in each branching level were measured for each of the test conditions. The measured pressure drop ranged from 20 to 90 kPa, and the measured void fraction ranged from 0.3 to 0.9. The measured pressure drop results agree well with separated flow model predictions accounting for the varying flow geometry. The measured void fraction results followed the same trends as the model; however, the scatter in the experimental results is rather large. (author)

Daniels, Brian J.; Liburdy, James A.; Pence, Deborah V. [Mechanical Engineering, Oregon State University, Corvallis, OR 97330 (United States)

2011-01-15

201

A new type of diabatic flow pattern map for boiling heat transfer in microchannels  

NASA Astrophysics Data System (ADS)

Flow pattern data and bubble measurements for two small diameter sight glass tubes are used to propose a new type of flow pattern map for evaporating flows in microchannels. Rather than segregating the observations into the traditional flow regimes and an adiabatic map, the new diabatic map classifies flows into three types: (i) the isolated bubble regime, where the bubble generation rate is much larger than the bubble coalescence rate and includes both bubbly and slug flows, (ii) the coalescing bubble regime, where the bubble coalescence rate is much larger than the bubble generation rate and exists up to the end of the coalescence process and (iii) the annular regime, whose extent is limited by the vapor quality at the onset of critical heat flux. This formulation is thought to be more useful for phenomenological modeling of the processes controlling boiling heat transfer and two-phase pressure drops in microchannels, and it also visually defines the feasible operating limit of microchannel heat spreaders at the critical vapor quality corresponding to critical heat flux (CHF). The database covers two refrigerants (R-134a and R-245fa) and two channel diameters (0.509 and 0.790 mm). The micro-evaporator length was varied from 20 to 70 mm, the inlet subcooling from 2 to 15 °C, the mass flux from 200 to 2000 kg m-2 s-1 and heat fluxes up to 597 kW m-2. Three different saturation temperatures were tested: 26, 30 and 35 °C.

Revellin, R.; Thome, J. R.

2007-04-01

202

Flow boiling heat transfer of R134a, R236fa and R245fa in a horizontal 1.030 mm circular channel  

SciTech Connect

This research focuses on acquiring accurate flow boiling heat transfer data and flow pattern visualization for three refrigerants, R134a, R236fa and R245fa in a 1.030 mm channel. We investigate trends in the data, and their possible mechanisms, for mass fluxes from 200 to 1600 kg/m{sup 2}s, heat fluxes from 2.3 kW/m{sup 2} to 250 kW/m{sup 2} at T{sub sat} = 31 C and {delta}T{sub sub} from 2 to 9 K. The local saturated flow boiling heat transfer coefficients display a heat flux and a mass flux dependency but no residual subcooling influence. The changes in heat transfer trends correspond well with flow regime transitions. These were segregated into the isolated bubble (IB) regime, the coalescing bubble (CB) regime, and the annular (A) regime for the three fluids. The importance of nucleate boiling and forced convection in these small channels is still relatively unclear and requires further research. (author)

Ong, Chin L.; Thome, John R. [Laboratory of Heat and Mass Transfer (LTCM), Ecole Polytechnique Federale de Lausanne (EPFL), ME G0 520 ME Station 9, Lausanne CH 1015 (Switzerland)

2009-04-15

203

On the evolution of convection in magmatic-hydrothermal systems  

NASA Astrophysics Data System (ADS)

Convective fluid circulation in continental magmatic-hydrothermal systems plays a fundamental role for the formation of ore deposits and geothermal systems. Two competing processes drive convection in continental magmatic-hydrothermal systems: gradients in temperature, which decrease the density of the fluid, and gradients in salinity, which increase the density of the fluid. While heat diffuses more rapidly than salt, salt is advected faster than heat and as a result, double-diffusive and double-advective instabilities can form which may lead to chaotic convection. Continental magmatic-hydrothermal systems can cover a wide PTX range (0 to 800 C, 0 to 500 MPa, and 0 to 1 XNaCl). Under these condition, the presence of salt in the fluid increases the PT regime during which boiling and phase-separation into a highly compressible, low-salinity vapour phase and a slightly compressible, high-salinity brine phase take place. This process of phase-separation is thought to have a profound effect on the evolution of convection cells in continental magmatic-hydrothermal systems but has not yet been studied. In order to understand the effect of double-advective, double-diffusive convection and phase separation in continental magmatic-hydrothermal, we have combined a higher order finite element-finite volume algorithm and a new equation of state for the system H2O-NaCl which provides a realistic thermodynamic representation of the fluid properties including the wide PTX range of liquid + vapour coexistence for the highly saline fluids. This allows us to realistically model multi-phase fluid flow, energy and component transport in continental magmatic-hydrothermal systems, including fluid and rock properties that vary over many orders of magnitude and the geometric complexities of such systems. We have conducted several simulations of a continental magmatic-hydrothermal systems in which a hot, saline magmatic fluid exsolves from a crystallizing magma and is injected into the surrounding rock. In the simulations, we have successively varied the following input parameters: Depth of intrusion, rate of magmatic fluid production, temperature of magmatic fluid, salinity of magmatic fluid, and permeability structure. First results show that the combination of the rate at which magmatic fluid is produced and the permeability structure of the system have the most profound effect on the evolution of convection in continental magmatic-hydrothermal systems. High permeabilities in combination with relatively low fluid production rates (long lived fluid production) lead to an effective cooling mechanism during which temperatures rarely exceed 150 C. Only if the permeabilities are sufficiently low and the fluid production rate is sufficiently fast (short lived fluid production), convection cells can form that produce temperatures where phase separation can take place and ore deposits can form.

Geiger, S.; Driesner, T.; Heinrich, C.; Matthai, S. K.

2003-04-01

204

Hydrothermal oxidation of radioactive combustible waste  

Microsoft Academic Search

A hydrothermal processing system was designed, built and tested for treatment of transuranic combustible material. The operation is performed in a plutonium glovebox. Presented in this paper are results from the study of the hydrothermal oxidation of plutonium and americium contaminated organic wastes. The use of thermal liquefaction, via pyrolysis, to prepare solid materials for hydrothermal processing was tested and

L. A Worl; S. J Buelow; D. M Harradine; R Lanning; D. D Padilla; J. H Roberts; X Shao

2000-01-01

205

Hydrothermal Vents: Thar She Blows!  

NSDL National Science Digital Library

In this lesson students will discover how the proximity of hot magma to cold ocean water creates new rocky structures around hydrothermal vents. During this activity, students will demonstrate an understanding of how the processes that result in the formation of hydrothermal vents create new ocean floor and how the transfer of energy effects solids and liquids. This hands-on activity uses online data resources and includes: focus questions, learning objectives, teaching time, audio/visual materials needed, background information, learning procedures, evaluations, extensions, as well as resources and student handouts.

206

Hydrothermal alteration in research drill hole Y-3, Lower Geyser Basin, Yellowstone National Park, Wyoming  

USGS Publications Warehouse

Y-3, a U.S. Geological Survey research diamond-drill hole in Lower Geyser Basin, Yellowstone National Park, Wyoming, reached a depth of 156.7 m. The recovered drill core consists of 42.2 m of surficial (mostly glacial) sediments and two rhyolite flows (Nez Perce Creek flow and an older, unnamed rhyolite flow) of the Central Plateau Member of the Pleistocene Plateau Rhyolite. Hydrothermal alteration is fairly extensive in most of the drill core. The surficial deposits are largely cemented by silica and zeolite minerals; and the two rhyolite flows are, in part, bleached by thermal water that deposited numerous hydrothermal minerals in cavities and fractures. Hydrothermal minerals containing sodium as a dominant cation (analcime, clinoptilolite, mordenite, Na-smectite, and aegirine) are more abundant than calcium-bearing minerals (calcite, fluorite, Ca-smectite, and pectolite) in the sedimentary section of the drill core. In the volcanic section of drill core Y-3, calcium-rich minerals (dachiardite, laumontite, yugawaralite, calcite, fluorite, Ca-smectite, pectolite, and truscottite) are predominant over sodium-bearing minerals (aegirine, mordenite, and Na-smectite). Hydrothermal minerals that contain significant amounts of potassium (alunite and lepidolite in the sediments and illitesmectite in the rhyolite flows) are found in the two drill-core intervals. Drill core y:.3 also contains hydrothermal silica minerals (opal, [3-cristobalite, chalcedony, and quartz), other clay minerals (allophane, halloysite, kaolinite, and chlorite), gypsum, pyrite, and hematite. The dominance of calcium-bearing hydrothermal minerals in the lower rhyolitic section of the y:.3 drill core appears to be due to loss of calcium, along with potassium, during adiabatic cooling of an ascending boiling water.

Bargar, Keith E.; Beeson, Melvin H.

1985-01-01

207

Some factors affecting the metering of subcooled water with a choked venturi  

NASA Astrophysics Data System (ADS)

A series of experiments characterizing the subcooled choking process in a convergent-divergent nozzle with a constant area throat is described. A low pressure flow loop capable of a maximum water flow rate of 5.5 L/s with a pressure head of 300 kPa and the pressure and temperature upstream of the nozzle in the flow loop adjusted between 90 and 300 kPa and 53 and 96 C. The flow rate, upstream pressure and temperature, and the axial wall pressure profiles in the nozzle were measured. Critical mass flow rate data were acquired along five isotherms as a function of stagnation pressure. Factors affecting metering performance are examined.

Fincke, J. R.; Collins, D. R.

1981-05-01

208

Hydrothermal alteration facies within the intrusive-hosted Salave gold prospect, NW Spain  

SciTech Connect

The Salave gold prospect occurs within an Hercynian granodioritic complex intruding Cambro-Ordovician metasediments and a heterogeneous gabbroic body. Mineralization consists mostly of disseminated and veinlet pyrite, arsenopyrite, molybdenite, stibnite, and lesser sphalerite associated with a zoned sequence of hydrothermal alteration. Gold occurs as free particles and/or intergrown with the sulfides. Mathematical appraisal of analytical data suggests that the hydrothermal alteration resulted from largely isochemical redistribution processes imposed on the mineralogy of the host granodiorite by influxes of sporadically boiling fluids rich in CO/sub 2/. Hydrothermal alteration is described in terms of a zonal sequence inward from unaltered host rock through (1) chlorite-sericite alteration-(2) propylitic to advanced propylitic alterations-(3)albitites-(4) an auriferous (greater than or equal to 1g/t Au) sericite-carbonate-albite-(+/-)quartz-sulfide cataclastic facies. The zonation corresponds to increasing carbonatization, sericitization, albitization, desilification, and destruction of the original igneous texture. Aventurine alteration is common and is thought to be the product of late stage hydrothermal oxidizing conditions. Potassic alteration in the form of K-feldspar or biotite was occasionally observed.

Harris, M.

1985-01-01

209

Hydrothermally stable periodic mesoporous ethane-silica and bimodal mesoporous nanostructures.  

PubMed

We report the hydrothermally stable organized periodic mesoporous organosilicas (PMOs) and bimodal mesoporous structures by using mixed templates of oligomeric alkyl-ethylene oxide and ionic surfactants under basic conditions. Oligomeric alkyl-ethylene oxide surfactant [(Polyoxyethylene (2) cetyl ether, structure is C16H33(OCH2CH2)nOH, n-2, hereafter known as B52) and ionic surfactant (cethyltrimethylammonium bromide (CTAB)) templating systems form mixed micelles that self-assemble into well-ordered hexagonal and bimodal mesostructures. The X-ray diffraction (XRD), transmission electron microscopy (TEM), BET, NMR and hydrothermal study have been used to investigate the effects of B52 on the formation of various PMOs. It is found that surface structural properties of mesostructures largely depend on the concentration of the B52 in the surfactant solution. The addition of B52 in the surfactant solution is not only improves mesostructural ordering and also enables to produces mesostructures with tuned surface structural properties. The final PMO structure shows good hydrothermal stability and can withstand for 72 h in boiling water, due to the hydrophobic pore wall chemistry in ethane-bridged PMO framework (triple bond Si-CH2-CH2-Si triple bond) and relatively more condensed framework such T3 supported by NMR spectrum. So, the lacking affinity for water through the favorable hydrophobic framework chemistry enhances the hydrothermal stability. PMID:22400212

Wahab, M Abdul; Chaobin, He

2011-10-01

210

Ocean ridge magmatic and hydrothermal geochemical processes  

NASA Astrophysics Data System (ADS)

The ocean ridge system as an interaction site linking the interior of the earth with the lithosphere, biosphere, and hydrosphere is characterized in a critical review of U.S. research from the period 1987-1990. Sections are devoted to magmatic and hydrothermal processes, with particular attention to the chemical variability of MORB, studies of magmatic segmentation in the East Pacific Rise, plans for sampling the Pacific-Antarctic Ridge, regional differences in the extent and pressure of melting, the diversity of oceanic plutonic rocks, observations of active hydrothermal venting, the composition of hydrothermal fluids, models of hydrothermal circulation, and the mineralogy and geochemistry of hydrothermal deposits. A comprehensive bibliography is provided.

Klein, Emily M.

211

Magmatic intrusions and hydrothermal systems  

Microsoft Academic Search

This dissertation investigates the possible role of hydrothermally driven ground-water outflow in the formation of fluvial valleys on Mars. Although these landforms have often been cited as evidence for a past warmer climate and denser atmosphere, recent theoretical modeling precludes such climatic conditions on early Mars when most fluvial valleys formed. Because fluvial valleys continued to form throughout Mars' geological

Virginia Claire Gulick

1993-01-01

212

Boiling inception in volume-heated liquids  

SciTech Connect

Analysis of the transition phase of a hypothetical core disruptive accident in an LMFBR has indicated that the core would probably consist of a boiling mixture of fuel and steel, temporarily confined by massive blockages of fuel and/or steel, both above and below. Recriticality of the core depends to a great extent upon the hydrodynamic state of the fuel/steel mixture. Experiments have been performed with non-reactor materials to determine the behavior of such pools, in particular the average and local distribution of vapor. These experiments indicate that one dimensional drift flux calculations are not satisfactory for determining void profiles in internally boiling liquids, since they neither predict the boiling onset and stratified behavior nor agree with measured void profile data. This observation casts serious doubt upon the applicability of hydrodynamic analog experiments for determination of void distribution behavior of volumetrically boiling liquids. Further analysis is underway to develop appropriate models for the prediction of vapor distribution in volume-heated liquids to include determination of boiling onset as well as subsequent void fraction distribution. 9 refs., 2 figs.

Greene, G.A.; Reilly, S.M.

1981-01-01

213

Hydrothermal synthesis of amino acids  

SciTech Connect

This study presents further evidence that amino acids can be synthesized rapidly in hydrothermal solutions from reactants that may have been present in primitive environments. Aqueous NH[sub 4]HCO[sub 3] solutions were reacted with C[sub 2]H[sub 2], H[sub 2], and O[sub 2] (formed in situ from CaC[sub 2], Ca, and H[sub 2]O[sub 2]) at 200-275[degrees]C over 0.2-2 h periods to synthesize several amino acids and abundant amines. These amino acid and amine producing reactions were not observed to occur below 150[degrees]C. Amino acids and amines also were synthesized at 210[degrees]C from solutions of NH[sub 4]OH, HCHO, NaCN, and H[sub 2]. When NH[sub 4]OH was replaced by NH[sub 4]HCO[sub 3], the syntheses predominantly confirmed the recent results of Hennet et al. (1992). Additionally, amino acids and amines were observed to form by reactions among NH[sub 4]OH, HCHO, and H[sub 2] at hydrothermal conditions, essentially confirming the results of Fox and Windsor (1970). Inclusion of both carbonate and O[sub 2] in these latter solutions greatly enhanced the production rate of amino acids. The amines synthesized hydrothermally could be significant if they are precursors in the amino acid syntheses either at hydrothermal or later at lower temperatures. These observations provide additional input to the current questions of synthesis, stability, and decomposition of amino acids at hydrothermal conditions, and their possible relevance to the origin of life.

Marshall, W.L. (Oak Ridge National Lab., TN (United States))

1994-05-01

214

QSPRs for the estimation of subcooled liquid vapor pressures of polycyclic aromatic hydrocarbons, and of polychlorinated benzenes, biphenyls, dibenzo-p-dioxins, and dibenzofurans at environmentally relevant temperatures.  

PubMed

This study aims to develop estimation procedures for subcooled liquid vapor pressures of polycyclic aromatic hydrocarbons (PAHs), and of polychlorinated benzenes, biphenyls (PCBs), dibenzo-p-dioxines (PCDDs), and dibenzofurans (PCDFs) based on quantitative structure-property relationships (QSPRs) for the subcooled liquid vaporization enthalpy and entropy in terms of simple molecular structure descriptors and the system temperature. It turned out that subcooled liquid vaporization enthalpies and entropies for these compound classes can be estimated from the number of carbon atoms, the number of chlorine atoms, the number of PCB ortho-chlorine atoms and the system temperature. Subcooled liquid vapor pressures at 298 K calculated from the estimated vaporization enthalpies and entropies were equal to directly measured experimental values as well as to experimental values determined by gas chromatographic methods within, on average, 0.15 and 0.12-0.3 log units, respectively. PMID:19709716

van Noort, Paul C M

2009-08-25

215

Boiling heat transfer from an excavated fin  

SciTech Connect

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

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

1992-03-01

216

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

PubMed Central

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

Brown, Joseph; Sobsey, Mark D.

2012-01-01

217

CONTINUOUS ANALYZER UTILIZING BOILING POINT DETERMINATION  

DOEpatents

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

Pappas, W.S.

1963-03-19

218

Hydrothermal brecciation in the Jemez fault zone, Valles Caldera, New Mexico: Results from continental Scientific Drilling Program core hole VC-1  

NASA Astrophysics Data System (ADS)

An unusual breccia sequence penetrated in the lower 30 m of Continental Scientific Drilling Program core hole VC-1 (total depth 856 m) records a complex hydrothermal history culminating in hydraulic rock rupture and associated alteration at the edge of the Quaternary Valles caldera. The breccias, both tectonic and hydrothermal in origin, were formed in the Jemez fault zone, near the intersection of this major regional structure with the caldera's ring-fracture margin. Tectonic breccias in the sequence are contorted, crushed, and sheared. Coexisting hydrothermal breccias lack such frictional textures but display matrix flow foliation and prominent clast rounding, features characteristic of fluidization. These hydrothermal breccias were intensely altered, during at least five major stages, to quartz-illite-phengite-pyrite aggregates; traces of molybdenite occur locally. This assemblage indicates interaction with hydrothermal fluid at temperatures in excess of 200°C. The extrapolated present maximum temperature of 184°C in the breccia zone therefore represents considerable cooling since these phases were formed. Fluid inclusions in the breccias also preserve evidence of the prior passage of hotter fluids. The inclusions are principally two phase, liquid rich, secondary in origin, and concentrated in hydrothermal quartz. Older, high-salinity inclusions, unrelated to brecciation, homogenize in the temperature range 189°-246°C. Younger inclusions, in part of interbreccia origin, are low-salinity and homogenize in the temperature range 230°-283°C; locally coexisting liquid- and vapor-rich inclusions document periodic boiling of the dilute fluids. These fluid-inclusion data, along with the probable age of the hydrothermal breccias (<1.5 Ma), the assumed depth at which they developed (about 515 m), and the contemporaneous state of stress (extensional) can be combined to model hydrothermal brecciation at the VC-1 site. The minimum fluid pressure (Pfr) required to hydrofracture these rocks was probably about 7.5 MPa (0.0146 MPa/m). A boiling point versus depth curve based on these Pfr values graphically defines the physical conditions prevailing when the breccias were formed. When fluid pressure at the assumed depth of brecciation exceeded that curve, in response to rapid release of confining pressure possibly augmented by renewed heating, flashing hydrothermal fluid fractured the enclosing rock. Large overpressures, most likely induced by sudden seismic cracking of a hydrothermally sealed portion of the Jemez fault zone, led to local fluidization of the resulting breccias. Late quartz veining, hydrothermal alteration, and molybdenite mineralization were probably produced by the fluids responsible for brecciation.

Hulen, Jeffrey B.; Nielson, Dennis L.

1988-06-01

219

A rapid, semiempirical method of calculating the stability margins of superconductors cooled with subcooled He-II: (Final report)  

SciTech Connect

A rapid, semiempirical method is presented for calculating the stability margins of superconductors cooled with subcooled He-II. Based on a model of Seyfert, the method takes into account both time-dependent Gorter-Mellink heat transport and the effects of interfacial Kapitza resistance. The method has been compared favorably with heat transfer data of Seyfert, stability data of Meuris, and stability data of Pfotenhauer and van Sciver. 4 refs., 7 figs., 1 tab.

Dresner, L.

1986-01-01

220

Sub-cooled and flashing liquid jets and droplet dispersion I. Overview and model implementation\\/validation  

Microsoft Academic Search

Many accidents involve two-phase releases of hazardous chemicals into the atmosphere. This paper describes the results of a third phase of a Joint Industry Project (JIP) on liquid jets and two-phase droplet dispersion. The aim of the project is to increase the understanding of the behaviour of sub-cooled non-flashing and superheated flashing liquid jets, and to improve the prediction of

Henk W. M. Witlox; Mike Harper; Adeyemi Oke; Philip J. Bowen; Peter Kay

2010-01-01

221

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

222

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

223

Effects of glacial ice on subsurface temperatures of hydrothermal systems in Yellowstone National Park, Wyoming: Fluid-inclusion evidence  

SciTech Connect

Hydrothermal quartz and fluorite crystals containing liquid-rich fluid inclusions (coexisting vapor-rich fluid inclusions were not observed) were found in drill cores from eight relatively shallow research holes drilled by the US Geological Survey in and near major geyser basins of Yellowstone National Park. Homogenization temperatures (T{sub h}) for mostly secondary fluid inclusions show variations in temperature that have occurred at give depths since precipitation of the host minerals. Within major hydrothermal upflow zones, fluid-inclusion T{sub h} values all were found to be equal to or higher (commonly 20-50 C and up to 155 C higher) than present temperatures at the depths sampled. During periods when thick glacial ice covered the Yellowstone National Park region, pore-fluid pressures in the underlying rock were increased in proportion to the weight of the overlying column of ice. Accordingly, theoretical reference boiling-point curves that reflect the maximum temperature attainable in a hot-water geothermal system at a given depth were elevated, and temperatures within zones of major hydrothermal upflow (drill holes Y-2, Y-3, Y-6, Y-11, Y-13, and upper part of Y-5) increased. The thicknesses of ice required to elevate boiling-point curves sufficiently to account for the observed fluid-inclusion T{sub h} values are within the ranges estimated by glacial geologic studies. At the margins of major hydrothermal upflow zones (drill holes Y-4 and Y-9), fluid-inclusion T{sub h} values at given depths range from 57 C lower to about the same as the current temperature measurements because of a previous decrease in the rate of discharge of warm water and/or an increase in the rate of recharge of cold water into the hydrothermal system.

Bargar, K.E.; Fournier, R.O. (Geological Survey, Menlo Park, CA (USA))

1988-12-01

224

Thermal analysis of a solar collector containing a boiling fluid  

SciTech Connect

The thermal performance of a flat-plate solar collector containing a boiling fluid is analyzed for steady-state thermosiphon operation. Collectors containing a boiling fluid have a thermal efficiency that is inherently greater than a non-boiling collector having the same value of the thermal parameter a (see Nomenclature). The general validity of the analysis is established by experimental data taken on an R-11 charged boiling collector in natural sunlight.

Al-Tamimi, A.I.; Clark, J.A.

1983-06-01

225

Boiling and condensing pumped loop microgravity experiment  

Microsoft Academic Search

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

Vaughn H. Standley; Jerry F. Fairchild

1991-01-01

226

Sampling System for a Boiling Reactor NPP.  

National Technical Information Service (NTIS)

Investigations and pilot running of the nuclear power plant with a VK-50 boiling reactor reveal the necessity of normalizing the design system of water sampling and of mandatory replacement of the needle-type throttle device by a helical one. A method for...

A. I. Zabelin E. D. Yakovleva Y. A. Solov'ev

1976-01-01

227

Big Bubbles in Boiling Liquids: Students' Views  

ERIC Educational Resources Information Center

|The aim of this study was to elicit students' conceptions about big bubbles in boiling liquids (water, ethanol and aqueous CuSO[subscript 4] solution). The study is based on twenty-four students at different ages and grades. The clinical interviews technique was conducted to solicit students' conceptions and the interviews were analyzed to…

Costu, Bayram

2008-01-01

228

THE HALDEN BOILING HEAVY WATER REACTOR  

Microsoft Academic Search

The project, officiaily designated as HBWR, was undertaken in 1956 by ; the Norwegian Institutt for Atomenergi as builder and owner. Project HBWR was ; conceived as a nuclear power experiment for the studying of the physical and ; technological aspects of a heavy water moderated reactor under boiling conditions ; at a power level above 10 Mw thermal. The

N. Hidle; O. Dahl

1959-01-01

229

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

230

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

231

Classic and Hard-Boiled Detective Fiction.  

ERIC Educational Resources Information Center

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

Reilly, John M.

232

Cryogenic Propellant Boil-Off Reduction System  

NASA Astrophysics Data System (ADS)

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

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

2008-03-01

233

Certain Results of a Cinematographic Study of Bulk Boiling.  

National Technical Information Service (NTIS)

Modern ideas on the boiling process are based on the surface mechanism of heat exchange between a heat-releasing surface and a fluid heat-receiving coolant. Boiling bubbles can form at the surface or in the liquid. If in the liquid, the boiling is called ...

E. G. Prokofev V. N. Drulis Y. P. Yakovlev

1972-01-01

234

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

235

Diversity of Archaeal Consortia in an Arsenic-Rich Hydrothermal System  

NASA Astrophysics Data System (ADS)

Characterizing microbial communities within their geochemical environment is essential to understanding microbial distribution and microbial adaptations to extreme physical and chemical conditions. The hydrothermal waters at El Tatio geyser field demonstrate extreme conditions, with water at local boiling (85°C), arsenic concentrations at 0.5 mM, and inorganic carbon concentrations as low as 0.02mM. Yet many of El Tatio's hundred plus hydrothermal features are associated with extensive microbial mat communities. Recent work has shown phylogenetic variation in the communities that correlates to variations in water chemistry between features. MPN analysis indicates variations in metabolic function between hydrothermal features, such as the ability of the community to fix nitrogen, and the presence of methanogens within the community. Methanogenic archaea, which are typical of hydrothermal environments, are found in very few of the sampled hydrothermal features at El Tatio. MPN enumeration shows that nonspecific microbial mat samples from sites with dissolved methane contain 106 cells of methanogenic archaea per gram while non-specific samples from sites lacking dissolved methane contain 100 cells per gram or less. An acetylene assay showed evidence for nitrogen fixation in a sample associated with methanogenesis, but microbial transformation of acetylene to ethylene did not occur in non-methanogenic sites. More specific sampling of microbial mats indicates that methanogenic archaea are dominated by microorganisms within the genus Methanospirillum and Methanobrevibacter. These microbes are associated with a number of unclassified archaea in the class Thermoplasmata Halobacteriales, and unclassifiec Crenarchaeota. In addition, preliminary results include an unclassified Thaumarchaeota clone, a member of the recently proposed third archaeal phylum Thaumarchaeota. Nonspecific microbial mat sample from a non- methanogenic site included only Crenarchaeal clones within the Desulfurococcales order of Thermoprotei.

Franks, M.; Bennett, P.; Omelon, C.; Engel, A.

2008-12-01

236

Mystery of the Megaplume: Hydrothermal Vent Chemistry  

NSDL National Science Digital Library

In this lesson, students will investigate hydrothermal vents to see how the chemistry of the water they emit provides clues to the location of the vents. They should be able to describe hydrothermal vents and characterize vent plumes in terms of physical and chemical properties; describe data gathering operations in which a towed instrument package ("tow-yo") measures conductivity, temperature, and depth; and interpret temperature anomaly data to recognize a plume emanating from a hydrothermal vent.

237

Boiling and acidification in epithermal systems: numerical modeling of transport and deposition of base, precious, and volatile metals  

SciTech Connect

Boiling and acidification of hydrothermal waters are important processes that lead to mineral precipitation in geothermal systems. In this study, numerical models of boiling and acidification are applied to a chemical system that contains base, precious and volatile metals. The numerical model incorporates simple newly-developed methods to account for heat balance and for the non-ideal behavior of gaseous H/sub 2/O, CO/sub 2/, CH/sub 4/, and H/sub 2/. Also, the stoichiometry and stability of arsenic and antimony thiosulfides at elevated temperature are evaluated, and included in an internally consistent set of thermodynamic data for arsenic and antimony aqueous species, minerals and gases. Equations derived from a quadratic virial equation in pressure are fitted to published P-V-T and solubility data to yield values of fugacity coefficients and enthalpies for several pure and mixed gases. The virial equation treatment and thermodynamic data for arsenic and antimony is used with existing software to simulate boiling and acidification of a Broadlands-type geothermal water that contains base, precious and volatile metals. The results indicate that the boiling leads to the precipitation of base metals, electrum and sulfosalts, and that acidification precipitates gold rich electrum or pure gold, along with sulfosalts and enargite at low temperatures. Below 100 C, acidification precipitates orpiment and stibnite. Upon boiling, mercury fractionates into the gas phase, but arsenic and antimony stay in the aqueous phase. In cooling of a dry gas phase, antimony stays in the gas down to 220 C where stibnite sublimates, and arsenic stays to 130 C where regular sublimates. Gas condensation below 100 C results in the precipitation of cinnabar.

Spycher, N.F.

1987-01-01

238

A new critical heat flux correlation for boiling liquid metals  

Microsoft Academic Search

This paper reports on correlations for the dryout heat flux for sodium in tube and grid bundles that have been developed based on experimental results and analytical considerations. The main feature of these correlations is that they are derived from thermal, hydrodynamic, and geometrical parameters. These parameters are the subcooling, the inlet and outlet vapor quality, the mass flow rate,

H. M. Kottowski; C. Savatteri; W. Hufschmidt

1991-01-01

239

Analogue modeling of instabilities in crater lake hydrothermal systems  

NASA Astrophysics Data System (ADS)

We carried out analogue experiments on two-phase boiling systems, using a porous vertical cylinder, saturated with water. The base of the cylinder was heated, and the top was cooled, as in a natural hydrothermal system. Previous work had shown that once the two-phase zone reached a certain level, thermal instabilities would develop. We made measurements of the acoustic energy related to boiling, and we found that high levels of acoustic noise were associated with the part of the cycle in which there was upward water movement. We repeated our experiments with a cooling water tank at the top of the system, representing a crater lake. This showed that periodic thermal instabilities still developed in this situation. We then compared our analogue measurements to two natural systems known to exhibit periodic behavior. There is good agreement between the thermal and acoustic cycling seen in our model and the observations made at Inferno Crater Lake in the Waimangu Geothermal area, New Zealand, whose level cycles by nearly 10 m, with a typical period of 38 days. Particularly notable is how in both systems high levels of acoustic noise are associated with rising water level. The much larger Ruapehu Crater Lake, also in New Zealand, cycled with a period of several months to a year for over a decade prior to the 1995 eruption. Strong acoustic and seismic energy usually occurred just before the lake temperature started to rise. This suggests a slightly different model, in which the increasing two-phase flow zone triggers more general convection once it reaches the base of the lake.

Vandemeulebrouck, Jean; Stemmelen, Didier; Hurst, Tony; Grangeon, Jacques

2005-02-01

240

Vapliq hydrothermal systems, and the vertical permeability of Los Azufres, Mexico, geothermal reservoir  

SciTech Connect

We identify a new category of natural hydrothermal systems intermediate between liquid- and vapor-dominated. This category is characterized by a “vapliq” vertical pressure profile, which is nearly vaporstatic in the shallower portion of the system, and nearly boiling-point-for-depth at depth. The prototype of these systems is the geothermal field of Los Azufres, Mexico. To explore the thermohydrological conditions conducent to this type of system, we propose a 1-D vertical scenario based on generally accepted conceptual models of liquid- and vapor-dominated geothermal reservoirs. We use the corresponding mass and thermal energy transport equations to establish that a necessary condition for the existence of 2-phase hydrothermal systems is that the absolute value of the vertical thermal flux must exceed Q{sub min}, a parameter that depends only on the values of the pressure and of the thermal conductivity at the boiling point of the system. The values of Q{sub min} are typically 1-4 times the average terrestrial flux. We also find that geothermal systems in which convective heat transport is accomplished by the well-known heat-pipe mechanism can exist only if the corresponding heat flux exceeds Q{sub min} and the permeability at the boiling point of the system is smaller than k{sub Bmax}, a parameter that depends only on the values of the pressure and of the thermal conductivity at the boiling point. Typical values of k{sub Bmax} are 1-3 {times} 10{sup -18} m{sup 2}, suggesting a reason for the fact that all vapor-dominated systems are associated with very-low matrix permeability formations. Applying these insights, and the mass and heat transport equations to Los Azufres, we conclude that a contrast of 1-3 orders of magnitude exists between the vertical permeability at the boiling point and that corresponding to the vapor-dominated portion of the system. We propose that similar permeability contrasts may be responsible for the characteristic composite pressure observed in other vapliq systems.

Iglesias, Eduardo R.; Arellano, Victor M.

1988-01-01

241

A model for the formation of hydrothermal manganese crusts from the Pitcairn Island hotspot  

NASA Astrophysics Data System (ADS)

The distribution of elements in the hydrothermal Mn crusts from the Pitcairn Island hotspot can be explained by considering processes occurring within the hotspot volcano. These include the role of boiling of the ascending hydrothermal fluid which leads to sulphide deposition and seawater intrusion into the upper part of the volcano. This in turn results in the development of an oxycline above which FeOOH can precipitate. The high Mn/Fe ratios and low contents of Ni and Zn in the massive crusts are thought to reflect the rapid incorporation of the ore elements into sulphide minerals such that only a small proportion of these elements are available for incorporation in the crusts. The small positive Eu anomaly in the crusts on a NASC-normalized basis reflects the lower temperatures in the hydrothermal fluids at the Pitcairn Island hotspot (<25dgC) compared to those at mid-ocean ridges (c.350°C). The oxyanions (CrO 42-, VO 43- AsO 43- and PO 43-), the rare earth elements (REE), and Th are scavenged by FeOOH particles within the upper part of the seamount and can, therefore, be incorporated into the crusts associated with the Fe-rich phase. Molybdenum and uranium are scavenged in only negligible amounts by the FeOOH. Molybdenum is, therefore, most probably scavenged from seawater by manganese oxides during the actual formation of the Mn crusts. The alkali metals, Li, Rb, and Cs, remain in solution in the hydrothermal fluids and are selectively incorporated into the buserite structure of the Mn crusts in the absence of strong competition from the divalent transition metal ions. The compositional characteristics of the hydrothermal Mn crusts can, therefore, be explained in terms of a simple model of element scavenging and uptake occurring mainly within the seamount. A laser-ablation ICPMS profile in one of the hydrothermal crusts (DS 63-4) revealed varying REE concentrations and patterns in the different layers of the crust. These data indicate that the hydrothermal component was variable during the formation of the crust. It was calculated to be almost 100% in the upper 18.0 mm of this crust (apart from the samples at 6.0-8.0 mm) and about 80% in the lower layers.

Glasby, G. P.; Stüben, D.; Jeschke, G.; Stoffers, P.; Garbe-Schönberg, C.-D.

1997-11-01

242

Conditions leading to a recent small hydrothermal explosion at Yellowstone National Park  

USGS Publications Warehouse

Porkchop Geyser, in Yellowstone National Park, was the site of a small hydrothermal explosion on September 5, 1989. The geyser column suddenly rose to a height of 20-30 m, followed immediately by the explosive ejection of sinter blocks up to 1.88 m in maximum dimension and formation of an irregular crater 13.9 m long and 11.7 m wide. The ejected blocks show a variety of siliceous deposits indicative of changing environments of deposition with time, and possibly of prior hydrothermal explosive activity at this site. Water samples from Porkchop were collected and analyzed once in the 1920s, again in 1951, ten times between 1960 and mid-1989, and once in January 1990 after the explosion. It is hypothesized that a sudden breaking loose of the constriction at the exit of the geyser tube, likely triggered by a seasonal increase in subsurface boiling throughout Norris Basin, allowed water and steam to be discharged from Porkchop much more rapidly than previously. This resulted in a drop in pressure within the geyser tube, causing water in adjacent connected chambers to become superheated. An ensuing rapid flashing of superheated water to steam within relatively confined spaces resulted in the hydrothermal explosion. -after Authors

Fournier, R. O.; Thompson, J. M.; Cunningham, C. G.; Hutchinson, R. A.

1991-01-01

243

Large-scale in situ heater tests for hydrothermal characterization at Yucca Mountain  

SciTech Connect

To safely and permanently store high-level nuclear waste, the potential Yucca Mountain repository site must mitigate the release and transport of radionuclides for tens of thousands of years. In the failure scenario of greatest concern, water would contact a waste package, accelerate its failure rate, and eventually transport radionuclides to the water table. Our analyses indicate that the ambient hydrological system will be dominated by repository-heat-driven hydrothermal flow for tens of thousands of years. In situ heater tests are required to provide an understanding of coupled geomechanical-hydrothermal-geochemical behavior in the engineered and natural barriers under repository thermal loading conditions. In situ heater tests have been included in the Site Characterization Plan in response to regulatory requirements for site characterization and to support the validation of process models required to assess the total systems performance at the site. Because of limited time, some of the in situ tests will have to be accelerated relative to actual thermal loading conditions. We examine the trade-offs between the limited test duration and generating hydrothermal conditions applicable to repository performance during the entire thermal loading cycle, including heating (boiling and dry-out) and cooldown (re-wetting). For in situ heater tests to be applicable to actual repository conditions, a minimum heater test duration of 6-7 yr (including 4 yr of full-power heating) is required.

Buscheck, T.A.; Wilder, D.G.; Nitao, J.J.

1993-01-01

244

Hydrothermal clinopyroxenes of the Skaergaard intrusion  

Microsoft Academic Search

Magmatic augites reacted with high temperature aqueous solutions to form secondary calcic pyroxenes during the subsolidus cooling of the Skaergaard intrusion. Secondary, hydrothermal clinopyroxenes replace wall rock igneous augites at the margins of veins filled with calcic amphibole. These veins are up to several millimeters wide and tens of meters in length. Hydrothermal clinopyroxenes are a ubiquitous and characteristic phase

Craig E. Manning; Dennis K. Bird

1986-01-01

245

Frictional slip of granite at hydrothermal conditions  

Microsoft Academic Search

Sliding on faults in much of the continental crust likely occurs at hydrothermal conditions, i.e., at elevated temperature and elevated pressure of aqueous pore fluids, yet there have been few relevant laboratory studies. To measure the strength, sliding behavior, and friction constitutive properties of faults at hydrothermal conditions, we slid laboratory granite faults containing a layer of granite powder (simulated

Michael L. Blanpied; David A. Lockner; James D. Byerlee

1995-01-01

246

Hydrothermal conversion of carbohydrates and related compounds  

NASA Astrophysics Data System (ADS)

The research described in this thesis was aimed at the (partial) elucidation of the chemistry of the major decarboxylation pathways occurring in the hydrothermal conversion of carbohydrates. Knowledge of the chemical background of this hydrothermal decarboxylation might enable more effective processing of biomass with respect to minimizing the oxygen content of hydrothermolysis products.

Luijkx, Gerardus Christianus Antonius

247

Hydrothermal metamorphism in the Larderello Geothermal Field  

SciTech Connect

The various tectonic units underlying the Larderello-Travale geothermal region have undergone hydrothermal metamorphism. The hydrothermal mineral assemblages are generally consistent with the temperatures now measured in the wells, leading to the hypothesis that solid phases deposited from a liquid medium during a hot-water stage that preceded the vapor-dominated one. 61 refs.

Cavarretta, G.; Gianelli, G.; Puxeddu, M.

1980-01-01

248

EFFECTS OF EXTRATERRESTRIAL HYDROTHERMAL PROCESSES IN CHONDRITES  

Microsoft Academic Search

Hydrothermal reactions in terrestrial geological processes may be defined in a simplified form as those that cause numerous alterations of earlier formed rocks and minerals due to the action of hot aqueous solutions, usually in a postmagmatic stage. Under extraterrestrial conditions hydrothermal processes should occur probably less often because of the lack of the environments rich in such solutions. Only

Andrzej MANECK

249

Hydrothermal decomposition of esters under high pressure  

Microsoft Academic Search

The hydrothermal decomposition of two esters (methyl formate and ethyl formate) was studied in the absence of oxygen over the temperature range of 373 – 673 K at pressures from 15 to 35MPa for residence times between 72 and 600s. At hydrothermal conditions, the esters were hydrolyzed to formic acid and the corresponding alcohols in equilibrium yields of more than

Takashi Moriyoshi; Keisuke Sam; Yasuhiro Uosaki

2001-01-01

250

Enhanced Droplet Control by Transition Boiling  

PubMed Central

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

Grounds, Alex; Still, Richard; Takashina, Kei

2012-01-01

251

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

252

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

253

D0 Silicon Upgrade: Vapor Pressure Thermometry System Near LN2 Subcooler  

SciTech Connect

Fermi National Accelerator Laboratory (Fermilab) is in the process of upgrading its detectors. Among these upgrades is the need for more transfer lines containing both liquid nitrogen and helium gas. These two fluids are used to provide the necessary operating cryogenic temperatures for the various detectors, such as the Visible Light Photon Counter (VLPC) and the solenoid inside the detector's calorimeter. With additional piping, it is important to monitor the temperatures to assure that the detectors can operate correctly. This can be done two ways. The first method is to use a Resistance Temperature Device, called a RTD, which is made using either a carbon resistor or a platinum resistor and measures the temperature based on resistance. The second method is to use a vapor-pressure thermometry system. This design will focus on the second method. A nitrogen Vapor Pressure Thermometer (VPT) system is designed to determine the temperature of the liquid nitrogen (LN{sub 2}) supply line, after exiting the LN{sub 2} subcooler, inside the D-Zero Assembly Hall. The operating temperature range is designed from 77 to 300 Kelvin with an initial charge pressure of 100 psia. A cylindrical bulb with a 0.1875-inch diameter and 0.625-inch length allows for minimum cold and warm 1/4-inch O.D. SS 304L tubing lengths, 12-inch and 18-inch respectively, and maintains a liquid level of 50% inside the bulb during cold operation. The amount of nitrogen needed to fill the cylindrical bulb approximately half full is 0.149 grams. In order to conform to the conventional cold volume and warm volume VPT systems, we need to enlarge the existing 1/2-inch x 2-inch SCH. 10 LN{sub 2} supply line over a one foot section to 1-inch x 3-inch SCH. 10 piping.

Kuwazaki, Andrew; /Fermilab

1996-07-01

254

Hydrothermal synthesis of hydroxyapatite rods  

NASA Astrophysics Data System (ADS)

Hydroxyapatite (HAP) rods were synthesized from dicalcium phosphate anhydrous (CaHPO4, DCPA) and calcium carbonate (CaCO3) by the hydrothermal method from 120 to 180 °C. Both cuttlebone (aragonite polymorph of CaCO3) and CaCO3 chemical (calcite polymorph of CaCO3) were used as CaCO3 sources. The nucleation and growth of HAP rods mainly occurred on DCPA particles, while some HAP rods also grew from aragonite particles. The nucleation and growth of ?-tricalcium phosphate (?-TCP) particles on the surface of calcite particles were observed at the beginning of the reaction of DCPA and calcite, and some HAP rods were also found to grow out of ?-TCP particles. After the hydrothermal reaction at 140 °C for 24 h, most products are HAP with a small amount of ?-TCP synthesized as a byproduct. The HAP rods synthesized were ˜200 nm in width and several microns in length. The reaction mechanism and growth process of HAP rods are discussed.

Zhang, Xing; Vecchio, Kenneth S.

2007-10-01

255

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

256

Geochemistry of hydrothermal plume in the Suiyo Seamount Caldera  

Microsoft Academic Search

Chemical compounds of the hot basalt origin are discharged into the deep ocean via hydrothermal plume by the deep-sea hydrothermal activity. The hydrothermal plume is widely diffused to the ocean by mixing with ambient seawater. Chemical reactions and interactions with microorganisms in the diffusion process of the hydrothermal plume are important to comprehend the oceanic geochemical cycles. Recently, it has

K. Shitashima; Y. Maeda

2002-01-01

257

Arctic Ocean: hydrothermal activity on Gakkel Ridge.  

PubMed

In the hydrothermal circulation at mid-ocean ridges, sea water penetrates the fractured crust, becomes heated by its proximity to the hot magma, and returns to the sea floor as hot fluids enriched in various chemical elements. In contradiction to earlier results that predict diminishing hydrothermal activity with decreasing spreading rate, a survey of the ultra-slowly spreading Gakkel Ridge (Arctic Ocean) by Edmonds et al. and Michael et al. suggests that, instead of being rare, the hydrothermal activity is abundant--exceeding by at least a factor of two to three what would be expected by extrapolation from observation on faster spreading ridges. Here we use helium-3 (3He), a hydrothermal tracer, to show that this abundance of venting sites does not translate, as would be expected, into an anomalous hydrothermal 3He output from the ridge. Because of the wide implications of the submarine hydrothermal processes for mantle heat and mass fluxes to the ocean, these conflicting results call for clarification of the link between hydrothermal activity and crustal production at mid-ocean ridges. PMID:14999274

Jean-Baptiste, Philippe; Fourré, Elise

2004-03-01

258

Water boiling inside carbon nanotubes: toward efficient drug release.  

PubMed

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

Chaban, Vitaly V; Prezhdo, Oleg V

2011-06-13

259

One-step synthesis of hydrothermally stable mesoporous aluminosilicates with strong acidity  

SciTech Connect

Using tetraethylorthosilicate (TEOS), polymethylhydrosiloxane (PMHS) and aluminium isopropoxide (AIP) as the reactants, through a one-step nonsurfactant route based on PMHS-TEOS-AIP co-polycondensation, hydrothermally stable mesoporous aluminosilicates with different Si/Al molar ratios were successfully prepared. All samples exclusively showed narrow pore size distribution centered at 3.6 nm. To assess the hydrothermal stability, samples were subjected to 100 deg. C distilled water for 300 h. The boiled mesoporous aluminosilicates have nearly the same N{sub 2} adsorption-desorption isotherms and the same pore size distributions as those newly synthesized ones, indicating excellent hydrothermal stability. The {sup 29}Si MAS NMR spectra confirmed that PMHS and TEOS have jointly condensed and CH{sub 3} groups have been introduced into the materials. The {sup 27}Al MAS NMR spectra indicated that Al atoms have been incorporated in the mesopore frameworks. The NH{sub 3} temperature-programmed desorption showed strong acidity. Due to the existence of large amount of CH{sub 3} groups, the mesoporous aluminosilicates obtained good hydrophobicity. Owing to the relatively large pore and the strong acidity provided by the uniform four-coordinated Al atoms, the excellent catalytic performance for 1,3,5-triisopropylbenzene cracking was acquired easily. The materials may be a profitable complement for the synthesis of solid acid catalysts. - Graphical abstract: Based on the nonsurfactant method, a facile one-step synthesis route has been developed to prepare methyl-modified mesoporous aluminosilicates that possessed hydrothermal stability and strong acidity.

Yang Dongjiang [Chinese Academy of Sciences, State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Taiyuan 030001 (China); School of Physical and Chemical Sciences, Queensland University of Technology, Brisbane, QLD 4001 (Australia); Xu Yao [Chinese Academy of Sciences, State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Taiyuan 030001 (China)], E-mail: xuyao@sxicc.ac.cn; Wu Dong; Sun Yuhan [Chinese Academy of Sciences, State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Taiyuan 030001 (China)

2008-09-15

260

Wall function approach for boiling two-phase flows  

Microsoft Academic Search

One of the important goals of the NURESIM project is to assess and improve the simulation capability of the three-dimensional two-fluid codes for prediction of local boiling flow processes. The boiling flow is strongly affected by local mechanisms in the turbulent boundary layer near the heated wall. Wall-to-fluid transfer models for boiling flow with the emphasis on near-wall treatment are

Boštjan Kon?ar; Mavko Borut

2010-01-01

261

WALL-TO-FLUID TRANSFER MECHANISMS IN BOILING FLOWS  

Microsoft Academic Search

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

Mavko Borut

2005-01-01

262

Numerical study of high heat flux pool boiling heat transfer  

Microsoft Academic Search

A new numerical simulation model of boiling heat transfer is proposed based on a numerical macrolayer model [S. Maruyama, M. Shoji, S. Shimizu, A numerical simulation of transition boiling heat transfer, in: Proceedings of the Second JSME–KSME Thermal Engineering Conference, pp. 3-345-3-348, 1992]. In this model, the boiling curve is reproduced numerically by determining the macrolayer thickness. It is found

Ying He; Masahiro Shoji; Shigeo Maruyama

2001-01-01

263

Relationships between melting point and boiling point of organic compounds  

SciTech Connect

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

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

1994-07-01

264

Pb Bi-cooled direct contact boiling water small reactor  

Microsoft Academic Search

A design concept of PbBi cooled direct contact boiling water small fast reactor (PBWFR) has been formulated with some design parameters identified. Water is injected into hot PbBi above the core, and direct contact boiling takes place in chimneys. Boiling bubbles rise due to buoyancy effects, which works as a lift pump for PbBi circulation. The generated steam passes through

Minoru Takahashi; Shoji Uchida; Koji Hata; Takaharu Matsuzawa; Hiroo Osada; Yoshiyuki Kasahara; Naoki Sawa; Yoshiyuki Okubo; Toru Obara; Elin Yusibani

2005-01-01

265

Candy Chemosynthesis: Biochemistry of Hydrothermal Vents  

NSDL National Science Digital Library

In this activity, students will differentiate between requirements for life in extreme environments such as hydrothermal vents and other environments and will use soft candy as a model to create a visual image of chemicals involved in autotrophic nutrition. As they review the biochemistry of hydrothermal vents, they will discover what chemicals are used by autotrophs in extreme environments in the deep ocean and how these chemicals differ from those used by terrestrial autotrophs. They will also study a diagram showing how a hydrothermal vent (black smoker) acquires the elements and compounds that deep-sea autotrophs require.

266

Dissolved Organic Metals in the Hydrothermal Plume  

NASA Astrophysics Data System (ADS)

In the hydrothermal plume, there are the unique microbiological communities and the microorganism utilizes various chemical substances. The interactions between heavy metals and microorganisms in the hydrothermal plume are important to comprehend the oceanic geochemical cycles of heavy metals. It is considered that the heavy metals in hydrothermal plume are organically bound with dissolved organic matter derived from the hydrothermal microorganism. This study funded by the O`Archaean ParkO_L project of MEXT is a first attempt to observe the bioavailability of heavy metals in hydrothermal plume. The hydrothermal plume samples were taken from two different kinds of hydrothermal sites, the Suiyo Seamount caldera and the Central Indian Ridge. The mini CTDT-RMS mounted twelve 1.2L Niskin bottles was installed on the manned submersible, and the hydrothermal plume samples were collected by taking the distance from the hydrothermal vents gradually. The solid phase extraction technique in C18 Sep-Pak cartridge (Millipore Waters) was used to extract the dissolved organic matter from the hydrothermal plume samples. Dissolved heavy metals (Al, Mn, Fe, Cu, Zn, Co, Ni, As, Mo, Cd and Pb) bound with C18 Sep-Pak extractable organic matter, dissolved organic metals, were analyzed by GFAAS. In all measured heavy metals, the dissolved organic metals existed in the hydrothermal plume samples collected from two sites. The concentration of the dissolved organic metals ranged from 0.5nM to 30nM and was about 1/1000~1/100 of the total dissolved heavy metals concentration. It suggests that these heavy metals were bound with organic matter originated in the hydrothermal microorganism. Though the abundance of the organism in the Central Indian Ridge is larger than that in the Suiyo Seamount caldera, the concentration of the dissolved organic metals in the plume samples at the Suiyo Seamount caldera was higher than that at the Central Indian Ridge. These results indicate that the bioavailability of heavy metals is different in two sites.

Shitashima, K.

2003-12-01

267

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

SciTech Connect

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

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

2004-06-23

268

U and Th Concentration and Isotopic Composition of Hydrothermal Fluids at the Lost City Hydrothermal Field  

Microsoft Academic Search

Uranium and Th concentration and isotopic composition of hydrothermal fluids at the Lost City Hydrothermal Field (LCHF) were determined using multi-collector inductively coupled plasma mass spectrometry (MC-ICP- MS). The LCHF is an off-axis, serpentinite-hosted hydrothermal system located at 30°N near the Mid- Atlantic Ridge. Carbonate chimneys reaching 60 m in height vent alkaline (pH~10), calcium-rich fluids at 40- 91°C and

K. A. Ludwig; C. Shen; H. Cheng; R. Edwards; D. S. Kelley; D. A. Butterfield

2006-01-01

269

Hyperbaric hydrothermal atomic force microscope  

DOEpatents

A hyperbaric hydrothermal atomic force microscope (AFM) is provided to image solid surfaces in fluids, either liquid or gas, at pressures greater than normal atmospheric pressure. The sample can be heated and its surface imaged in aqueous solution at temperatures greater than 100.degree. C. with less than 1 nm vertical resolution. A gas pressurized microscope base chamber houses the stepper motor and piezoelectric scanner. A chemically inert, flexible membrane separates this base chamber from the sample cell environment and constrains a high temperature, pressurized liquid or gas in the sample cell while allowing movement of the scanner. The sample cell is designed for continuous flow of liquid or gas through the sample environment.

Knauss, Kevin G. (Livermore, CA); Boro, Carl O. (Milpitas, CA); Higgins, Steven R. (Laramie, WY); Eggleston, Carrick M. (Laramie, WY)

2002-01-01

270

Hyperbaric Hydrothermal Atomic Force Microscope  

DOEpatents

A hyperbaric hydrothermal atomic force microscope (AFM) is provided to image solid surfaces in fluids, either liquid or gas, at pressures greater than normal atmospheric pressure. The sample can be heated and its surface imaged in aqueous solution at temperatures greater than 100.degree. C. with less than 1 nm vertical resolution. A gas pressurized microscope base chamber houses the stepper motor and piezoelectric scanner. A chemically inert, flexible membrane separates this base chamber from the sample cell environment and constrains a high temperature, pressurized liquid or gas in the sample cell while allowing movement of the scanner. The sample cell is designed for continuous flow of liquid or gas through the sample environment.

Knauss, Kevin G. (Livermore, CA); Boro, Carl O. (Milpitas, CA); Higgins, Steven R. (Laramie, WY); Eggleston, Carrick M. (Laramie, WY)

2003-07-01

271

Hydrothermal carbonization of lignocellulosic biomass.  

PubMed

Hydrothermal carbonization (HTC) is a novel thermochemical conversion process to convert lignocellulosic biomass into value-added products. HTC processes were studied using two different biomass feedstocks: corn stalk and Tamarix ramosissima. The treatment brought an increase of the higher heating values up to 29.2 and 28.4 MJ/kg for corn stalk and T. ramosissima, respectively, corresponding to an increase of 66.8% and 58.3% as compared to those for the raw materials. The resulting lignite-like solid products contained mainly lignin with a high degree of aromatization and a large amount of oxygen-containing groups. Liquid products extracted with ethyl acetate were analyzed by gas chromatography-mass spectrometry. The identified degradation products were phenolic compounds and furan derivatives, which may be desirable feedstocks for biodiesel and chemical production. Based on these results, HTC is considered to be a potential treatment in a lignocellulosic biomass refinery. PMID:22698445

Xiao, Ling-Ping; Shi, Zheng-Jun; Xu, Feng; Sun, Run-Cang

2012-05-22

272

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

273

Boiling water reactor pressure vessel life extension  

SciTech Connect

The reactor pressure vessel (RPV) is one of the components which is critical to a potential nuclear power plant life extension. Previous EPRI research has indicated that plant life extension may be feasible, even assuming wholesale replacement of a pressurized water reactor RPV. This paper describes the results of a service life extension study for an operating boiling water reactor (BWR) vessel. The study was conducted under a BWR pilot plant program sponsored in part by EPRI and the Department of Energy. The purpose of the investigation was to identify the probable RPV life limiting effects, and the potential for extending life.

Gregor, F.E.; Hagan, K.A.

1986-04-01

274

Influence of Marangoni convection on pool boiling  

NASA Astrophysics Data System (ADS)

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

Vogel, B.; Straub, J.

1990-05-01

275

Understanding the boiling water reactor limit cycle  

SciTech Connect

This paper presents an interpretation of the physical mechanisms involved in the development of limit cycle oscillations in boiling water reactors (BWRs). Based on this interpretation, approximate correlations for some oscillation parameters are developed and shown to be largely independent of the particular reactor operating condition. The stability of the limit cycle is also studied in this paper. It is shown that the BWR limit cycle may become unstable and bifurcate. The bifurcation process leads to aperiodic (chaotic) behavior of the reactor power and causes the peak oscillation powers to be larger than those from a nonbifurcated limit cycle. 7 refs., 6 figs., 1 tab.

March-Leuba, J.

1989-01-01

276

Nonlinear dynamics of boiling water reactors  

SciTech Connect

Recent stability tests in Boiling Water Reactors (BWRs) have indicated that these reactors can exhibit the special nonlinear behavior of following a closed trajectory called limit cycle. The existence of a limit cycle corresponds to an oscillation of fixed amplitude and period. During these tests, such oscillations had their amplitudes limited to about +- 15% of the operating power. Since limit cycles are fairly insensitive to parameter variations, it is possible to operate a BWR under conditions that sustain a limit cycle (of fixed amplitude and period) over a finite range of reactor parameters.

March-Leuba, J.; Cacuci, D.G.; Perez, R.B.

1983-01-01

277

Melting of a solid adjacent to a heated vertical cylinder with or without subcooling of the solid  

NASA Astrophysics Data System (ADS)

Experiments were performed to provide quantitative heat transfer data corresponding to the problem of melting about a heated vertical cylinder embedded in a solid phase change material. The phase change material employed was 99 percent pure n-eicosane paraffin having an experimentally determined melting point of 36.4 C. Experiments were conducted with the solid phase either at the melting point or subcooled by 14.4 C. Measured transient cylinder wall temperatures demonstrate that the present melting problem is characterized by a conduction heat transfer regime at early times followed by a transition to a natural convection dominated regime. During the later stages of the natural convection regime, the cylinder wall temperatures reach a steady state condition. The steady state regime was defined to exist once the measured heat transfer coefficient had attained values within five percent of the final value. The correlations for the nonsubcooling tests are in good agreement with others corresponding to natural convection in vertical spaces. The correlations for the subcooling tests are not in good agreement indicating the presence of other participating transfer processes.

Kemink, R. G.

278

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

Microsoft Academic Search

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

J. L. Xu; Y. H. Gan

2007-01-01

279

Minerals produced during cooling and hydrothermal alteration of ash flow tuff from Yellowstone drill hole Y-5  

USGS Publications Warehouse

A rhyolitic ash-flow tuff in a hydrothermally active area within the Yellowstone caldera was drilled in 1967, and cores were studied to determine the nature and distribution of primary and secondary mineral phases. The rocks have undergone a complex history of crystallization and hydrothermal alteration since their emplacement 600,000 years ago. During cooling from magmatic temperatures, the glassy groundmass underwent either devitrification to alkali feldspar + ??-cristobalite ?? tridymite or granophyric crystallization to alkali feldspar + quartz. Associated with the zones of granophyric crystallization are prismatic quartz crystals in cavities similar to those termed miarolitic in plutonic rocks. Vapor-phase alkali feldspar, tridymite, magnetite, and sporadic ??-cristobalite were deposited in cavities and in void spaces of pumice fragments. Subsequently, some of the vapor-phase alkali feldspar crystals were replaced by microcrystalline quartz, and the vapor-phase minerals were frosted by a coating of saccharoidal quartz. Hydrothermal minerals occur primarily as linings and fillings of cavities and fractures and as altered mafic phenocrysts. Chalcedony is the dominant mineral related to the present hydrothermal regime and occurs as microcrystalline material mixed with various amounts of hematite and goethite. The chalcedony displays intricate layering and was apparently deposited as opal from silica-rich water. Hematite and goethite also replace both mafic phenocrysts and vapor-phase magnetite. Other conspicuous hydrothermal minerals include montmorillonite, pyrite, mordenite, calcite, and fluorite. Clinoptilolite, erionite, illite, kaolinite, and manganese oxides are sporadic. The hydrothermal minerals show little correlation with temperature, but bladed calcite is restricted to a zone of boiling in the tuff and clearly was deposited when CO2 was lost during boiling. Fractures and breccias filled with chalcedony are common throughout Y-5 and may have been produced by rapid disruption of rock caused by sudden decrease of fluid pressure in fractures, most likely a result of fracturing during resurgent doming in this part of the Yellowstone caldera. The chalcedony probably was deposited as opal or ??-cristobalite from a pre-existing silica floc that moved rapidly into the fractures and breccias immediately after the sudden pressure drop. ?? 1978.

Keith, T. E. C.; Muffler, L. J. P.

1978-01-01

280

Hydrothermal Syntheses of Some Derivatives of Tetraazatriphenylene  

Microsoft Academic Search

Some derivatives of tetraazatriphenylene can be synthesized readily by a hydrothermal synthetic method. Compared with the traditional technique, this method is effective and simple process, and much high yields of products with higher purity can be harvested.

Guangbo Che; Wenlian Li; Zhiguo Kong; Zisheng Su; Bei Chu; Bin Li; Zhiqiang Zhang; Zhizhi Hu; Haijun Chi

2006-01-01

281

Simulation of Submarine Hydrothermal Systems: IV. Fluid Flow in Active Arc-Related Volcanoes  

NASA Astrophysics Data System (ADS)

Fluid flow through submarine hydrothermal systems transports a major part of the Earth's heat to its surface and greatly impacts the chemistry of crust and overlying ocean. Seafloor high-temperature vent sites are manifestations of active ore-forming systems and can be regarded as modern analogues of massive sulfide deposits whose ancient equivalents have been exploited as world-class mines on land. Recent research cruises dedicated to seafloor hydrothermal activity along convergent plate boundaries, e.g. along the intra-oceanic Kermadec arc, have systematically surveyed and sampled numerous hydrothermal plumes. Follow-up submersible dives show venting that ranges from relatively high temperature (~300° C), metal-rich fluids to lower temperature, gas-rich and metal-poor fluids. Some of these vent sites show evidence for significant contributions from magmatic sources. The physics of such systems is complex because the seawater-derived hydrothermal fluid can mix with ambient seawater and phase-separate, either via boiling or condensation, into a low-salinity vapor and a high-salinity brine. In order to model the sub-seafloor hydrology with numerical transport simulation techniques, a newly developed pressure-enthalpy-salinity scheme has been used, which includes the full phase relations of the NaCl-H2O system up to 1000° C and accurately captures boiling, condensation, and salt precipitation. We have designed a new numerical model, based on observations in currently active arc-related systems, to assess the influence of first-order physical parameters (such as seafloor topography and the contribution of magmatic fluids) to fluid flow patterns, thermal structure, and phase-separation. Preliminary results of these simulations will be presented and compared with data recently obtained from simulations at mid-ocean ridge systems. In our ongoing project, we aim to predict the optimal conditions for which metal-rich magmatic vapor may cool and contract to an aqueous liquid, which in turn is likely to generate particularly Cu- and Au-rich mineralization on the seafloor.

Gruen, G.; Coumou, D.; Weis, P.; Driesner, T.; de Ronde, C.; Heinrich, C. A.

2008-12-01

282

Large-scale hydrothermal fluid discharges in the Norris-Mammoth corridor, Yellowstone National Park, USA  

USGS Publications Warehouse

Norris-Mammoth corridor is a complex subsidence structure that extends ~40 km northward from the 0.6 Ma Yellowstone caldera, and contains many hydrothermal features with high fluid discharges totaling ~1000 1/s. About 150-250 1/s of hydrothermal water, which attains boiling temperature at surface and 360??C at depth, discharge from the Norris Geyser Basin, adjacent to the caldera. The highest thermal water and gas discharges in the corridor are from Mammoth Hot Springs, where 500-600 1/s thermal water with surface temperatures of up to 73??C and calculated subsurface temperatures of ~100??C issue from ~100 hot springs scattered over a score of step-like travertine terraces that range in age from ~0.4 Ma to recent. All the thermal water is meteoric, likely recharged in the Gallatin Range at 2.5-3.0 km elevations. The isotopic and chemical compositions of thermal waters and solutes can be interpreted to indicate a common magmatic source for heat and volatile solutes located near Norris. However, the chemical and isotopic compositions of gases, especially the 3He/4He ratios, provide strong evidence for a separate magmatic source for the Mammoth system. (C) 2000 Elsevier Science B.V. All rights reserved.Norris-Mammoth corridor is a complex subsidence structure that extends approx. 40 km northward from the 0.6 Ma Yellowstone caldera, and contains many hydrothermal features with high fluid discharges totaling approx. 1000 l/s. About 150-250 l/s of hydrothermal water, which attains boiling temperature at surface and 360??C at depth, discharge from the Norris Geyser Basin, adjacent to the caldera. The highest thermal water and gas discharges in the corridor are from Mammoth Hot Springs, where 500-600 l/s thermal water with surface temperatures of up to 73??C and calculated subsurface temperatures of approx. 100??C issue from approx. 100 hot springs scattered over a score of step-like travertine terraces that range in age from approx. 0.4 Ma to recent. All the thermal water is meteoric, likely recharged in the Gallatin Range at 2.5-3.0 km elevations. The isotopic and chemical compositions of thermal waters and solutes can be interpreted to indicate a common magmatic source for heat and volatile solutes located near Norris. However, the chemical and isotopic compositions of gases, especially the 3He/4He ratios, provide strong evidence for a separate magmatic source for the Mammoth system.

Kharaka, Y. K.; Sorey, M. L.; Thordsen, J. J.

2000-01-01

283

Hydrothermal Manganese Mineralization Near the Samoan Hotspot  

NASA Astrophysics Data System (ADS)

The thickest beds of hydrothermal manganese oxides recovered to date from the global ocean were collected from a volcanic cone in the south Pacific. In April 2005, samples were dredged aboard the R.V. Kilo Moana from a volcanic cone on the lower flank of Tulaga seamount (about 2,700 m water depth; 14° 39.222' S; 170° 1.730' W), located 115 km SW of Vailulu'u, the volcanically and hydrothermally active center of the Samoan hotspot. Additional hydrothermal manganese samples were collected off Ofu Island (dredge Alia 107), 72 km to the WSW of Vailulu'u. Manganese-oxide beds up to 9 cm thick are composed of birnessite and 10 Å manganates. Some layers consist of Mn-oxide columnar structures 4 cm long and 1 cm wide, which have not been described previously. The mean Mn and Fe contents of 18 samples are 51 weight percent and 0.76 weight percent, respectively. Elevated concentrations of Li (mean 0.11 wt. percent) are indicators of a hydrothermal origin, and distinguishes these samples, along with the high Mn and low Fe contents, from hydrogenetic Fe-Mn crusts. Other enriched elements include Ba (mean 0.14 percent), Cu (249 ppm), Mo (451 ppm), Ni (400 ppm), Zn (394 ppm), V (214 ppm), and W (132 ppm). Chondrite-normalized REE patterns show large negative Ce anomalies and LREE enrichments, both characteristic of hydrothermal Mn deposits. Small negative Eu anomalies are not typical of hydrothermal deposits and can be explained either by the absence of leaching of plagioclase by the hydrothermal fluids or by the precipitation of Eu-rich minerals, such as barite and anhydrite, at depth. The high base-metal contents indicate that sulfides are not forming deeper in the hydrothermal system or that such deposits are being leached by the ascending fluids. Textures of the thickest Mn deposits indicate that the Mn oxides formed below the seabed from ascending fluids during multiple phases of waxing and waning hydrothermal pulses. The deposits were later exposed at the seafloor by erosional or mass wasting events; subsequently a thin layer of hydrogenetic Fe-Mn oxides accreted on the exposed surface. Mn-oxide filled veins may represent part of a feeder system. The thick sediment-free Mn-oxide layers locally grade into Mn-oxide cemented volcaniclastic beds. Our results indicate the extensive production of hydrothermal Mn on a regional basis, probably from multiple hydrothermal sources within the Samoan chain, and from the Tonga arc/back-arc system immediately to the west, as determined in previous studies.

Hein, J. R.; Staudigel, H.; Koppers, A.; Hart, S. R.; Dunham, R.

2006-12-01

284

Rare earth element systematics in hydrothermal fluids  

NASA Astrophysics Data System (ADS)

Rare earth element concentrations have been measured in hydrothermal solutions from geothermal fields in Italy, Dominica, Valles Caldera, Salton Sea and the Mid-Atlantic Ridge. The measured abundances show that hydrothermal activity is not expected to affect the REE balance of either continental or oceanic rocks. The REE enrichment of the solutions increases when the pH decreases. High-temperature solutions (>230°C) percolating through different rock types may show similar REE patterns.

Michard, Annie

1989-03-01

285

Rare earth element systematics in hydrothermal fluids  

SciTech Connect

Rare earth element concentrations have been measured in hydrothermal solutions from geothermal fields in Italy, Dominica, Valles Caldera, Salton Sea and the Mid-Atlantic Ridge. The measured abundances show that hydrothermal activity is not expected to affect the REE balance of either continental or oceanic rocks. The REE enrichment of the solutions increases when the pH decreases. High-temperature solutions (> 230{degree}C) percolating through different rock types may show similar REE patterns.

Michard, A. (Centre de Recherches Petrographiques et Geochimiques, Vandoeuvre-les-Nancy (France))

1989-03-01

286

Rare earth element systematics in hydrothermal fluids  

Microsoft Academic Search

Rare earth element concentrations have been measured in hydrothermal solutions from geothermal fields in Italy, Dominica, Valles Caldera, Salton Sea and the Mid-Atlantic Ridge. The measured abundances show that hydrothermal activity is not expected to affect the REE balance of either continental or oceanic rocks. The REE enrichment of the solutions increases when the pH decreases. High-temperature solutions (>230°C) percolating

Annie Michard

1989-01-01

287

Phosphorylation of Nucleotide Molecules in Hydrothermal Environments  

NASA Astrophysics Data System (ADS)

Phosphorylation of AMP into ADP and ATP, that can outrun their hydrolysis, was made possible in a simulated hydrothermal environment when trimetaphosphate was used as the phosphate source. The best yields of phosphorylated products were obtained when the reaction fluids whose temperature was set at about 100 degrees centigrade was injected into the cold environment maintained at 0 degree in a recycling manner. Hydrothermal environments in the primitive ocean could also have served as prebiotic sites for phosphorylation, among others.

Ozawa, Keita; Nemoto, Atsushi; Imai, Ei-ichi; Honda, Hajime; Hatori, Kuniyuki; Matsuno, Koichiro

2004-10-01

288

Hydrothermal industrialization: direct heat development. Final report  

SciTech Connect

A description of hydrothermal resources suitable for direct applications, their associated temperatures, geographic distribution and developable capacity are given. An overview of the hydrothermal direct-heat development infrastructure is presented. Development activity is highlighted by examining known and planned geothermal direct-use applications. Underlying assumptions and results for three studies conducted to determine direct-use market penetration of geothermal energy are discussed.

Not Available

1982-05-01

289

Relationships between lava types, seafloor morphology, and the occurrence of hydrothermal venting in the ASHES vent field of Axial Volcano. [Axial Seamount Hydrothermal Emission Study  

SciTech Connect

Deep-towed and submersible photographic surveys within the caldera of Axial Volcano have been integrated with high-resolution bathmetry to produce a geological map of the most active vent field in the caldera. Locations for over 2,000 photographs in and near the vent field were determined using a seafloor transponder network. Then each photograph was described utilizing a classification system which provides detailed information concerning lava type, hydrothermal activity, sediment cover, geological structure, and biology. Resulting data were entered into a digital data base, and computer-generated maps were created that portray spatial relationships between selected geological variables. In general, the entire ASHES field is characterized by pervasive low-temperature venting. The most vigorous venting is concentrated in an approximately 80 m {times} 80 m area where there are several high-temperature vents including some which are producing high-temperature vapor-phase fluids derived from a boiling hydrothermal system. Lava types within the ASHES vent field are grouped into three distinct morphologies: (1) smooth (flat-surfaced, ropy, and whorled) sheet flows, (2) lobate flows, and (3) jumbled-sheet flows. The most intense hydrothermal venting is concentrated in the smooth sheet flows and the lobate flows. The location of the ASHES field is mainly attributable to faulting which defines the southwest caldera wall, but the concentration of intense venting appears to be related also to the spatial distribution of lava types in the vent field and their contrasting permeabilities. Other structural trends of faults and fissures within the field also influence the location of individual events.

Hammond, S.R. (NOAA, Newport, OR (United States))

1990-08-10

290

(Boiling water reactor (BWR) CORA experiments)  

SciTech Connect

To participate in the 1990 CORA Workshop at Kernforschungszentrum Karlsruhe (KfK) GmbH, Karlsruhe, FRG, on October 1--4, and to participate in detailed discussions on October 5 with the KfK CORA Boiling Water Reactor (BWR) experiments. The traveler attended the 1990 CORA Workshop at KfK, FRG. Participation included the presentation of a paper on work performed by the Boiling Water Reactor Core Melt Progression Phenomena Program at Oak Ridge National Laboratory (ORNL) on posttest analyses of CORA BWR experiments. The Statement of Work (November 1989) for the BWR Core Melt Progression Phenomena Program provides for pretest and posttest analyses of the BWR CORA experiments performed at KfK. Additionally, it is intended that ORNL personnel participate in the planning process for future CORA BWR experiments. For these purposes, meetings were held with KfK staff to discuss such topics as (1) experimental test schedule, (2) BWR test conduct, (3) perceived BWR experimental needs, and (4) KfK operational staff needs with respect to ORNL support. 19 refs.

Ott, L.J.

1990-10-16

291

SWR 1000: The Innovative Boiling Water Reactor  

SciTech Connect

Framatome ANP has developed the boiling water reactor SWR 1000 in close cooperation with German nuclear utilities and with support from various European partners. This advanced reactor design marks a new era in the successful tradition of boiling water reactor technology and, with a gross electric output of between 1290 and 1330 MW, is aimed at assuring competitive power generating costs compared to gas- and coal-fired stations. At the same time, the SWR 1000 meets the highest safety standards, including control of a core melt accident these objectives are met by supplementing active safety systems with passive safety equipment of diverse design for accident detection and control and by simplifying systems needed for normal plant operation on the basis of past operating experience. The plant is also protected against airplane crash loads. A short construction period, flexible fuel cycle lengths of between 12 and 24 months and a high fuel discharge burn-up all contribute towards meeting economic goals. The SWR 1000 fulfills international nuclear regulatory requirements and has been offered to TVO for the fifth nuclear unit in Finland. (authors)

Brettschuh, Werner [Framatome ANP GmbH, Berlinerstrasse 295, 63067 Offenbach (Germany); Hudson, Greg [Framatome ANP Inc., 400 South Tyron Street, Charlotte, NC 28285 (United States)

2004-07-01

292

77 FR 36014 - Initial Test Program of Emergency Core Cooling Systems for Boiling-Water Reactors  

Federal Register 2010, 2011, 2012, 2013

...Cooling Systems for Boiling-Water Reactors AGENCY: Nuclear Regulatory Commission...Cooling Systems for Boiling- Water Reactors.'' This guide describes methods...systems (ECCSs) for boiling-water reactors (BWRs). DATES: Submit...

2012-06-15

293

77 FR 38339 - Dairyland Power Cooperative, La Crosse Boiling Water Reactor Exemption From Certain Security...  

Federal Register 2010, 2011, 2012, 2013

...Cooperative, La Crosse Boiling Water Reactor Exemption From Certain Security...Background The La Crosse Boiling Water Reactor (LACBWR) is owned and...forced-circulation, direct-cycle boiling water reactor as its heat source....

2012-06-27

294

77 FR 38338 - Dairyland Power Cooperative; La Crosse Boiling Water Reactor Exemption From Certain Security...  

Federal Register 2010, 2011, 2012, 2013

...Cooperative; La Crosse Boiling Water Reactor Exemption From Certain Security...Background The La Crosse Boiling Water Reactor (LACBWR) is owned and...forced-circulation, direct-cycle boiling water reactor as its heat source....

2012-06-27

295

18. RW Meyer Sugar Mill: 18761889. Boiling House Interior, 1878. ...  

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

18. RW Meyer Sugar Mill: 1876-1889. Boiling House Interior, 1878. View: Detail of floor with molasses pits below floor level. The remaining floor boards indicate the structure of the floor covering the entire inside of the boiling house. In the left background the base of the centrifugals are in view. - R. W. Meyer Sugar Mill, State Route 47, Kualapuu, Maui County, HI

296

17. RW Meyer Sugar Mill: 18761889. Boiling House, 1878. View: ...  

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

17. RW Meyer Sugar Mill: 1876-1889. Boiling House, 1878. View: Southwest corner of boiling house. The amimal-powered cane mill is located in the undergrowth in the right foreground, - R. W. Meyer Sugar Mill, State Route 47, Kualapuu, Maui County, HI

297

Pool boiling CHF on a laser heated thin plate  

Microsoft Academic Search

The technique of laser heating a thin metal foil was used to experimentally observe local phenomena in pool boiling CHF on a small flat surface. The experiments were performed with saturated water boiling on 25 ?m thick copper and titanium foils with heating surface diameters ranging from 2.27 to 9 mm. The number of simultaneously active nucleation sites depends on

Henrik Gjerkeš; Iztok Golobi?

2000-01-01

298

Effects of water in film boiling over liquid metal melts  

SciTech Connect

Liquid-liquid boiling experiments have been performed with H/sub 2/O and liquid metal melts in the 100-series test matrix (Runs 121, 126, 127) and the VE test matrix. Some of the pre-explosion unstable film boiling data as well as observations from the explosive series have been previously reported.

Greene, G.A.; Finfrock, C.; Burson, S.B.

1986-01-01

299

Characterization of nucleate pool boiling from smooth and rough surfaces  

Microsoft Academic Search

The effects of surface roughness on nucleate pool boiling heat transfer and bubble ebullition characteristics are studied using fluids with different wetting characteristics and surfaces with different roughness and surface structure. Heat transfer characteristics are described for pool boiling of deionized water and perfluorinated dielectric liquid HFE-7300 from novel porous copper evaporator surfaces with and without carbon nanotubes. A hybrid

John P McHale

2011-01-01

300

Bubble dynamics in boiling under high heat flux pulse heating  

Microsoft Academic Search

A new theoretical model of bubble behavior in boiling water under high heat flux pulse is presented. The essence of the model is nucleation in the superheated liquid followed by instantaneous formation of a vapor film, rapid bubble growth due to the pressure impulse, and cavitation bubble collapse. To check the model, boiling of methanol under 5 â¼ 50 MW

A. Asai

1991-01-01

301

VISUAL STUDY OF BOILING WATER AT HIGH PRESSURE  

Microsoft Academic Search

High-speed motion pictures were taken of boiling water flow in a ; rectanguiar channel. The tlow channel was 0.134 in. thick x 1.0 in. wide x 24 ; in. long heated on one side, the other three sides being used for observation of ; the boiling phenomena. The test section was so constructed that the images of ; the front

Hosler

1963-01-01

302

Investigations of Mechanisms Associated with Nucleate Boiling Under Microgravity Conditions  

Microsoft Academic Search

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

Vijay K. Dhir; M. Hasan

2003-01-01

303

Specifications and performance experience of pool boiling cooled magnets  

Microsoft Academic Search

Large superconducting magnets have three kinds of conductor-cooling methods; liquid helium pool boiling cooling, two-phase helium indirect cooling, or supercritical helium internal cooling. Practical superconducting magnets in their thirty years' history have had a lot of failure experiences. Electrical breakdown of insulation is the most fatal for pool boiling cooled magnets, because those magnets are unable to be utilized again,

T. Satow

1998-01-01

304

Boiling on the surface of a rotating disc  

Microsoft Academic Search

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

S. Yanniotis; D. Kolokotsa

1996-01-01

305

Hydrothermal Circulation in Europa's Mantle  

NASA Astrophysics Data System (ADS)

Features on the surface of Europa may reflect non-uniform heating in an underlying ocean due to variations in heat flux at the top of the mantle. Pore water convection can generate a spatially heterogeneous heat flux in a fractured, permeable mantle. Continual stressing of mantle material by gravitational tides, as well as occasional large-scale freezing and thawing that might be associated with changes in tidal resonance, and long-term hydration/dehydration processes, may allow significant permeability to exist despite the approximately 1 kbar confining overburden pressure at the mantle surface. We use a computational model of Europa to determine the impact of hydrothermal convection on overall heat transport, ice shell thickness, and heat flux heterogeneity and magnitude at the mantle/ocean and ocean/ice shell interfaces. Our model of Europa includes a core, a silicate mantle, an ocean layer, and an ice shell. Hydrothermal convection in the mantle, thermal diffusion, parameterized ocean flow and melting/freezing are the heat transport mechanisms included. Surface temperatures range sinusoidally from 52K at the poles to 110K at the equator. Total heating in the body consists of tidal dissipation in the mantle and core, radiogenic heating in the mantle, and tidal dissipation in the ice shell. Tidal heating is a function of ice viscosity and pressure-dependent melt temperature. Literature values for the total heating range from about 1 to 10 TW. Mantle and core heating are estimated to be equivalent to about 10 mW/m2 at the mantle surface. We assume that the outer few hundred kilometers of the mantle are permeable, and use an average value of 10 millidarcys, typical of the Earth at equivalent overburden depths. In 2-D and 3-D simulations, the ice shell thickness ranges from 20 km or less at the equator to about 40 km at the poles, with a slushy ice/water mixture below the ice cap in the polar regions. Transient, well-defined plumes are seen in the equatorial region (roughly +/- 30o) of the ocean layer, leading to enhanced heat flux below the ice cap there. Vigorous convection occurs in the mantle as a mix of plumes and linear features roughly 25-100 km wide and lengths up to several hundred kilometers. Changes in dynamics as a function of mantle permeability and heating rates are being explored. This work was supported by a grant from the Institute of Geophysics and Planetary Physics at Los Alamos National Laboratory and by the NASA Planetary Geology and Geophysics Program.

Travis, B.; Schubert, G.; Palguta, J.

2005-12-01

306

Removal of trace elements in hydrothermal plume at submarine volcanic arc hydrothermal systems  

Microsoft Academic Search

On the study of geochemical fluxes of trace elements from the hydrothermal system, it is necessary to collect not only samples by the hydro-cast from surface ship and fluid samples using a submersible but also temporally and spatially continuous samples ranging from a fluid to a hydrothermal plume. For that purpose, the sampling method along the diluting and rising plume

K. Shitashima

2007-01-01

307

Thermo-chemical variations of the hydrothermal fluids in the Berlin geothermal field (El Salvador)  

NASA Astrophysics Data System (ADS)

The liquid-dominated Berlin geothermal field is located about 110 km ESE of San Salvador, on the northern slope of the Berlin-Tecapa volcanic complex. The geothermal reservoir occurs within andesitic to basaltic lavas and tuffs. Measured temperatures in the production zones are in the 280-300Ë? C range, while in the reinjection zones are 245-250Ë? C. The reservoir fluids are NaCl waters with total dissolved solids of about 6000-10000 mg/kg and CO2 partial pressures of 0.049-0.460 MPa. A recent exploration project has been carried out by Enel GreenPower and LaGeo at the southern part of the field. A fluid inclusion studies have been carried out on core-samples from the recently explored area and from the production zone in order to obtain information on the thermo-chemical evolution of the geothermal fluids. In addition, isotopic data on hydrothermal epidote allowed to better constrain the sources of the water that circulated in the geothermal reservoir. The examined samples are mainly composed of volcanic rocks and breccias affected by hydrothermal alteration. The secondary minerals (mostly epidote, chlorite, quartz, adularia, albite, prehnite, calcite) occur either as replacement of primary minerals or within micro-fracture and voids. Fluid inclusions microthermometry has been performed on fluid inclusions found in hydrothermal and igneous quartz, albite, adularia, calcite, anhydrite and prehnite. Most of the observed inclusions are aqueous, two-phase liquid-rich inclusions; rare vapor-rich inclusions also occur in some samples. Fluid inclusion homogenization temperatures range is 191-344Ë? C; the inclusions with the highest homogenization values at each sampling depths were trapped at or close to boiling condition. A cooling process is recorded by the wide ranges of homogenization temperatures and is also evidenced by the comparison of present-day temperature at the sampling depths and fluid inclusion homogenization temperatures. In particular, a significant temperature decrease (up to 100Ë? C) occurred from the trapping of hottest fluid in the recently explored area to present-day condition at depths > 1.5 km below the ground level. Apparent salinities of many fluid inclusions are comparable to those of present-day fluids; however there are also fluid inclusions showing higher and lower salinities than present-day fluids. Low values of apparent salinity (down to 0.2 wt. % NaCl equiv.) can be related to the circulation of liquid water formed from steam condensation and/or in part to a decrease of the CO2 content in the geothermal fluid due to boiling processes. Whereas, the occurrence of inclusions in deep samples showing significantly high salinities (up to 21.2 wt.% NaCl equiv.) can be related to two processes: 1) open system fluid boiling with steam lost, or 2) injection of a high-salinity fluid in the system. The relatively high ^D values (up to -42 per mil) of the H2O in equilibrium with epidote is coherent with the sporadic input of saline fluids of magmatic derivation that mixed with geothermal fluid of meteoric origin in the deep part of the hydrothermal system. On the other hand, prolonged open system boiling processes at the temperatures indicated by fluid inclusions are not compatible with these isotopic values.

Ruggieri, G.; Dallai, L.; Nardini, I.; Torio Henriquez, E.

2009-04-01

308

Esterification of fatty acid catalyzed by hydrothermally stable propylsulfonic acid-functionalized mesoporous silica SBA-15.  

PubMed

Propylsulfonic acid-functionalized mesoporous silica SBA-15 has been synthesized via one-step strategy at 130°C based on the co-condensation of TEOS and MPTMS in the presence of Pluronic 123 polymer and H?O? in HCl aqueous solution. The synthesized solid exhibited hydrothermal stability in boiling water without significant change in textural properties. The catalytic performance of the synthesized solid was studied in the esterification of oleic acid with methanol. The experimental results revealed that the large mesopore structures of SBA-15-PrSO?H solid synthesized at 130°C could favor a facile access of oleic acid to the acid sites, making the comparable activity to that of phenyl ethyl sulfonic acid functionalized silica and higher than that of dry amberlyst-15. PMID:23728335

Mar, Win Win; Somsook, Ekasith

2013-01-01

309

Calcium Isotope Fractionation in Hydrothermal Systems  

NASA Astrophysics Data System (ADS)

We present measurements of stable Ca isotopes (?44/40Ca) from hydrothermal fluids (Long Valley, California) and epidote from fossil hydrothermal systems (Troodos and Betts Cove ophiolites). Hydrothermal fluids in Long Valley show a progressive increase in the heavy isotopes of Ca (?44/40Ca +0.56‰ relative to the initial thermal fluid) with decreasing temperature, Ca concentration, Ca/Sr and CO2 concentration. The increase in the ?44/40Ca along the hydrothermal fluid flow path is potentially consistent with the precipitation of hydrothermal calcite (which would be isotopically lighter) or mixing between the thermal fluid and meteoric water. We favor the former explanation because non-linear relationships between CO2 concentrations and noble gasses suggest that decreasing CO2 concentrations are primarily due to reservoir degassing, which would likely drive calcite precipitation (e.g. Arnorsson cont. min. pet, 1978). Epidote mineral separates from the Betts Cove (Newfoundland, early Ordovician) and Troodos (Cyprus, Cretaceous) ophiolites are isotopically light relative to bulk silicate earth (?44/40Ca ranges from -0.7 to 0.0‰). The epidote ?44/40Ca is not correlated with calculated fluid temperatures or 87Sr/86Sr measured in the epidote but is negatively correlated with the epidote Sr/Ca. Black smoker fluids, which are thought to be related to epidote formation in ophiolites, have ?44/40Ca of about 0-0.2‰, meaning that epidote Ca is consistently lighter than the inferred fluids from which they precipitate (Amini et al, GCA, 2008). To explain the complimentary Long Valley hydrothermal fluid and fossil epidote data there must be a mechanism for fractionating Ca isotopes at hydrothermal temperatures. Equilibrium fractionation of Ca isotopes should be close to 0‰ at high temperatures (100-400°C), implying that any Ca isotopic fractionation between fluid and hydrothermal minerals is likely a kinetic effect. Experimental data suggest that, for example, epidote equilibrium dissolution rates are about 0.3um/y (Wood and Walther, Science, 1983) while observations of epidote growth rates in geothermal systems are 73 um/y (Browne et al, Am Min, 1989). DePaolo (2009 Goldschmidt abstract) calculated that kinetic isotope fractionation between fluids and minerals should occur if net precipitation rates are greater than the equilibrium dissolution rate. If the estimates for dissolution and net precipitation rates for epidote are representative of most hydrothermal systems then epidote Ca should commonly have ?44/40Ca lighter than the associated fluid. Ocean ridge hydrothermal fluids should be slightly enriched in the heavy isotopes of Ca compared to oceanic crust as recently observed (Amini et al, GCA, 2008).

Brown, S. T.; Depaolo, D. J.; Turchyn, A. V.; Kennedy, B. M.; Alt, J.; Bedard, J. H.; Skulski, T.

2009-12-01

310

Geochemistry of hydrothermal fluids from the PACMANUS, Northeast Pual and Vienna Woods hydrothermal fields, Manus Basin, Papua New Guinea  

NASA Astrophysics Data System (ADS)

Processes controlling the composition of seafloor hydrothermal fluids in silicic back-arc or near-arc crustal settings remain poorly constrained despite growing evidence for extensive magmatic-hydrothermal activity in such environments. We conducted a survey of vent fluid compositions from two contrasting sites in the Manus back-arc basin, Papua New Guinea, to examine the influence of variations in host rock composition and magmatic inputs (both a function of arc proximity) on hydrothermal fluid chemistry. Fluid samples were collected from felsic-hosted hydrothermal vent fields located on Pual Ridge (PACMANUS and Northeast (NE) Pual) near the active New Britain Arc and a basalt-hosted vent field (Vienna Woods) located farther from the arc on the Manus Spreading Center. Vienna Woods fluids were characterized by relatively uniform endmember temperatures (273-285 °C) and major element compositions, low dissolved CO 2 concentrations (4.4 mmol/kg) and high measured pH (4.2-4.9 at 25 °C). Temperatures and compositions were highly variable at PACMANUS/NE Pual and a large, newly discovered vent area (Fenway) was observed to be vigorously venting boiling (358 °C) fluid. All PACMANUS fluids are characterized by negative ?DO values, in contrast to positive values at Vienna Woods, suggesting substantial magmatic water input to circulating fluids at Pual Ridge. Low measured pH (25 °C) values (˜2.6-2.7), high endmember CO 2 (up to 274 mmol/kg) and negative ?34SS values (down to -2.7‰) in some vent fluids are also consistent with degassing of acid-volatile species from evolved magma. Dissolved CO 2 at PACMANUS is more enriched in 13C (-4.1‰ to -2.3‰) than Vienna Woods (-5.2‰ to -5.7‰), suggesting a contribution of slab-derived carbon. The mobile elements (e.g. Li, K, Rb, Cs and B) are also greatly enriched in PACMANUS fluids reflecting increased abundances in the crust there relative to the Manus Spreading Center. Variations in alkali and dissolved gas abundances with Cl at PACMANUS and NE Pual suggest that phase separation has affected fluid chemistry despite the low temperatures of many vents. In further contrast to Vienna Woods, substantial modification of PACMANUS/NE Pual fluids has taken place as a result of seawater ingress into the upflow zone. Consistently high measured Mg concentrations as well as trends of increasingly non-conservative SO 4 behavior, decreasing endmember Ca/Cl and Sr/Cl ratios with increased Mg indicate extensive subsurface anhydrite deposition is occurring as a result of subsurface seawater entrainment. Decreased pH and endmember Fe/Mn ratios in higher Mg fluids indicate that the associated mixing/cooling gives rise to sulfide deposition and secondary acidity production. Several low temperature (?80 °C) fluids at PACMANUS/NE Pual also show evidence for anhydrite dissolution and water-rock interaction (fixation of B) subsequent to seawater entrainment. Hence, the evolution of fluid compositions at Pual Ridge reflects the cumulative effects of water/rock interaction, admixing and reaction of fluids exsolved from silicic magma, phase separation/segregation and seawater ingress into upflow zones.

Reeves, Eoghan P.; Seewald, Jeffrey S.; Saccocia, Peter; Bach, Wolfgang; Craddock, Paul R.; Shanks, Wayne C.; Sylva, Sean P.; Walsh, Emily; Pichler, Thomas; Rosner, Martin

2011-02-01

311

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

Microsoft Academic Search

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

Chen-Li Sun

2002-01-01

312

The Crater Lake and Hydrothermal System of Mount Pinatubo, Philippines: Evolution in the Decade After Eruption  

NASA Astrophysics Data System (ADS)

We document a decade of change in the lake and hydrothermal system of Mount Pinatubo, Philippines following the climactic eruption of 1991. A shallow lake formed by early Sept. 1991 and has shown a long-term trend of growth even during dry periods ( ~1 m/month). It was initially dominated by meteoric influx and the residuum of the pre-eruptive hydrothermal system, but quickly became more acid (pH ~2-3) as magmatic discharges continued to condense into the rapidly accumulating water. Acidity and rock dissolution peaked in late 1992, during and immediately after eruption of a lava dome on the crater floor (July-Oct. 1992). The pH of the lake remained ~3.0 to 3.3 from late 1992 to early 1999, whereas temperature showed a slow decline from ~40 to 30oC. Samples taken since cessation of dome growth suggest that magmatic degassing and rock dissolution have declined significantly relative to magmatic-hydrothermal brine and meteoric input. This is indicated by trends toward higher Cl, Na, K, Li and B and lower Mg, Ca, Fe, SO4 and F with time. Samples taken in 2001 indicate dilution, increase in pH (5.5), and decline in temperature ( ~27oC) resulting from a growing contribution of meteoric water. The rapid transition from a small and hot acid lake to moderately large and warm near-neutral pH lake is related to the rapid cessation of direct magmatic degassing, large size of the catchment, and large volume of hydrothermal input compared to lakes hosted by more restive andesitic volcanoes. The pre-existing hydrothermal system was invaded by an increased flux of magmatic gas and eventually by magma itself. As the impermeable caprock of the system was progressively fractured, extensive boiling and steam loss occurred. A dry conduit system that conducted volcanic gases and magma to the surface was maintained locally until late 1992. As the magmatic flux waned and the magmatic system plugged itself, a liquid hydrothermal system encroached on this direct pathway. Current hydrothermal input is neutral-Cl fluid that equilibrated with rocks at ~200oC and has similarities to geothermal fluids in wells drilled below the same area prior to eruption. This indicates that either very rapid fluid/rock interaction has occurred, or hydrothermal outflow that previously flowed south from the volcano now vents through the ruptured cap of the system. Considering evidence for declining magmatic input, edifice failure and due to rising lake-level and consequent lahars pose the greatest present risk to local populations. Two low areas on the crater rim, the Maraunot Notch and the O'Donnell River headwall are a few meters above lake level (late Aug. 2001), but the water level will probably top these points sometime in late 2001 or 2002. Several meters of ash deposits from the 1991 eruptions can be easily eroded from these areas if overtopping occurs. The most likely failure point is along structurally controlled zones of weakness and hydrothermal alteration that control the Maraunot Notch.

Stimac, J. A.; Goff, F.; Counce, D.; Larocque, A. C.; Hilton, D. R.; Morgenstern, U.

2001-12-01

313

Microbiological Effectiveness of Disinfecting Water by Boiling in Rural Guatemala  

PubMed Central

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

Rosa, Ghislaine; Miller, Laura; Clasen, Thomas

2010-01-01

314

Microbiological effectiveness of disinfecting water by boiling in rural Guatemala.  

PubMed

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

Rosa, Ghislaine; Miller, Laura; Clasen, Thomas

2010-03-01

315

Conversion of direct process high-boiling residue to monosilanes  

DOEpatents

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

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

2000-01-01

316

Heating surface thermal stabilization for pool boiling on porous coverings  

NASA Astrophysics Data System (ADS)

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

Wójcik, T. M.; Poniewski, M. E.

2012-11-01

317

Little low-power boiling never hurt anybody. [LMFBR  

SciTech Connect

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

Dunn, F.E.

1985-01-01

318

Analytical modeling of complete Nukiyama curves corresponding to expected low void fraction at high subcooling and flow rate  

SciTech Connect

On the basis of a new hypothesis of thermodynamic states (the superheated wall layer is not metastable but saturated at locally elevated pressure), an analytical estimation is presented of the whole boiling curve [except critical heat flux (CHF), but fixed at this point, known by experiments or correlation]. The curvature of the boiling curve (bubbly flow) is deduced from thermodynamics of irreversible processes. The wall temperature corresponding to departure from nucleate boiling is calculated from balances of momentum at the interfaces, based on the assumption that the speed of sound may be a limit for maximum evaporation mass flux and thereby heat flux, i.e., CHF. Heat flux during transition boiling is determined from balance of energy at the rewetting front. The Leidenfrost temperature, as well as wall temperature at CHF, can be calculated analytically without using empirical coefficients. Heat flux of bubbly flow and transition boiling can be matched at any empirical CHF point. All these results are determined from properties of state alone, i.e., the models can be verified for all fluids including water and liquid metals (so far at moderate heat fluxes). 52 refs., 11 figs., 2 tabs.

Schroeder-Richter, D. [Technische Universitaet Berlin (Germany)

1996-07-01

319

The peak boiling heat flux in saturated ethanol-water mixtures  

SciTech Connect

The present work provides original measurements of the burnout heat flux in saturated ethanol-water mixtures, over the full range of concentrations. These data were obtained at atmospheric pressure on horizontal cylinders, ranging from 0.51 to 2.16 mm in diameter. They reveal significant improvements of the peak heat flux for mixtures, over that which would be expected from pure fluids with the properties of the mixture. This improvement is most pronounced at low ethanol mass fractions. McEligot has suggested that the improved heat flux results from a subcooling created by selective distillation at the liquid-vapor interface. Combining this idea with a recent correlation of subcooled burnout, the authors estimate the extent of the effective subcooling qualitatively and discuss the use of this estimate to correlate burnout in binary mixtures. Two dimensionless groups are proposed to characterize this effective subcooling, both based on appropriate characterizations of the phase equilibrium diagram.

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

1989-05-01

320

Hydrothermal disturbances at the Norris Geyser Basin, Yellowstone National Park (USA) in 2003  

NASA Astrophysics Data System (ADS)

The Norris Geyser Basin in north-central Yellowstone National Park (YNP) experienced a series of notable changes during 2003, including formation of new hot springs and fumaroles, renewed activity of dormant geysers and elevated ground temperatures. This abstract provides a short synopsis of the new hydrothermal activity. In 2000, Yellowstone's tallest geyser, Steamboat, erupted after a dormant period of nearly 9 years. It erupted twice in 2002 and then again on 26 March and 27 April 2003. Surges in flux of thermal water preceding the eruptions (preplay) were recorded by a couplet of temperature data loggers placed in the outlet stream. The data indicated pulses of water flow with 1 and ~3 day intervals. On 10 July 2003, a new thermal feature was reported just west of Nymph Lake, ~ 3.5 km northwest of the Norris Museum. A linear series of vigorous fumaroles, about 75 m long had formed in a forested area, ~ 200 m up a hill on the lake's west shore. Fine particles of rock and mineral fragments coated nearby vegetation. Fumarole temperatures were around the local boiling temperature of water (92° C). After two months, somewhat reduced steam emission was accompanied by discharge of ~ 3-10 gallons per minute of near-neutral thermal water. Trees within 4 meters of the lineament were dead and were being slowly combusted. Porkchop Geyser in Norris' Back Basin had been dormant since it exploded in 1989, littering the nearby area with boulders up to over 1 m in diameter. Since that time, its water had remained well below the boiling temperature of water. From 1 April through 1 July `03, the temperature of waters in Porkchop's vent increased continuously from 67° to 88° C. Each Summer, Norris' Back Basin experiences an "annual disturbance" where individual hot springs and geysers typically show anomalous boiling, and have measurable increases in turbidity, acidity and SO4/Cl ratios. The disturbance has been linked to depressurization of the hydrothermal system as the hydrostatic pressure of the snowmelt-fed groundwater table wanes each summer. This year, the "Norris disturbance" is estimated to have begun on 11 July 2003,when pronounced changes were noted, including thermal pools that were boiled to dryness (e.g., Pearl Geyser), creating fumaroles. Porkchop Geyser erupted for the first time since 1989 on 16 July. New mud pots formed along the Back Basin Trail and increased ground temperatures were noted over an 500 x 300 m area. Park staff noted temperatures up to 94° C at 1 cm beneath the ground surface in areas that were previously cool. Vegetation in the area immediately died and began to break down due to the high temperatures. Yellowstone National Park closed the Back Basin Trail to all visitor travel on 22 July 2003. During the first week of August 2003, the Yellowstone Volcano Observatory installed a temporary monitoring network in the Norris Geyser Basin. University of Utah staff, with equipment and personnel made available by IRIS, UNAVCO, USGS and YNP, installed seven broadband seismometers and five continuous GPS receivers. In addition, YNP deployed a series of temperature data-loggers to record changes in flow from thermal features within the Norris Back Basin. The network is intended to identify ground motions associated with fluid flow within the geyser basin that may accompany eruptions of geysers, boiling episodes or events precursory to hydrothermal explosions. The monitoring network will remain operational for between four and twelve weeks.

Lowenstern, J. B.; Heasler, H.; Smith, R. B.

2003-12-01

321

Two types of hydrothermal fields in Atlantic  

NASA Astrophysics Data System (ADS)

Two principal types of the hydrothermal fields in Atlantic - central and flanked - could be established based on their structural setting in the rift zone of the Mid-Atlantic Ridge (MAR). The first (central) type is represented by Snake Pit, Broken Spur, Lucky Strike and Menez Gwen hydrothermal sites. All of these fields are connected with young axial effusive volcanism and related to large linear volcanic ridges or central volcanoes at the inner floor of the rift valley. The hydrothermal activity here is controlled by the intersection between longitudinal magma feeding faults and transversed weakened zones characterized by high permeability. The hydrothermal sites of the second (flanked) type (such as Logatchev, Reinbow, 24 grad. 30 min. N and possibly 13 grad. N and 16 grad. 45 min. N sites discovered recently) are related to large tectonic dislocations forming marginal scarps of the rift valley. The hydrothermal deposits of the first type are hosted by basalts meanwhile the flanked massive sulfides are represented mostly by ultramafic hosted deposits. There is no evident association of second type deposits with recent volcanics; the forming control by the transverse faults is dominated. Massive sulfides of the flanked type are characterized by the following features: § enrichment by Cu, heavy sulfur isotopes and radiogenic isotopes of Pb and depletion by Fe and S § presence of noble metal mineralization with native gold and platinum § presence of minerals of Co, Ni, As, Ag, Hg, U as well as intermetallides Hydrothermal fluides of the flanked type fields specified by high concentration of Cl, H2, CH4 and low content of H2S. We propose that all these features are determined by two genetically different types of hydrothermal systems, shallow- and deep-seated system.

Cherkashev, G.; Poroshina, I.; Stepanova, T.

2003-04-01

322

Boiling kinetics of superheated liquid helium-4  

SciTech Connect

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

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

1989-01-01

323

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.

324

Enceladus Plumes: A Boiling Liquid Model  

NASA Astrophysics Data System (ADS)

Following the discovery of H2O vapor and particle plumes from the tiger stripes at the south pole of Enceladus (Porco et al., 2006), observational and theoretical studies have been conducted to understand the plume mechanism (e.g., Schmidt et al., 2008; Kieffer et al., 2009; Ingersoll and Pankine, 2010). Although the “Ice Chamber Model”, which assumes that ice sublimation under the stripes causes the plumes, has successfully explained the plume mass flux (e.g., Nimmo et al., 2007; Ingersoll and Pankine, 2010), it cannot explain the high salinity in the plume (Postberg et al., 2009). Ice particles condensing from a vapor are relatively salt free, but ice particles derived from a salty liquid can have high salinity. Therefore we have investigated the “Boiling Liquid Model”, which assumes that liquid H2O under the stripes causes the plumes. With conservation of mass, momentum and energy, we built a simple atmospheric model that includes controlled boiling and gas-ice wall interaction. We first assumed that the heat radiated to space comes entirely from the heat generated by condensation of the gas onto the ice wall. We varied the width (0.1-1 m) and the height (5-4000 m) of the crack as parameters. We find that the escaping vapor flux can be relatively close to the observed value (250±100 kg/s, Hansen et al., 2006, 2008) but the radiated heat flux is only 1 GW, which is much less than the observed value (15.8 GW, Howett et al., 2011). Other models (Nimmo et al., 2007; Abramov and Spencer, 2009) also have the same difficulty accounting for the observed value. We then investigated the additional heat radiated by the particles after they come out of the crack. We built a simple model to estimate the size distributions of these condensed ice particles and their radiative properties.

Nakajima, Miki; Ingersoll, A. P.

2012-10-01

325

Boiling Performance of Antifreeze Solutions in a Saturate Pool Boiling System  

NASA Astrophysics Data System (ADS)

Nucleate boiling of binary mixtures is of particular importance in a various industries. The purpose of the present study is to provide experimental data and prediction method for nucleate boiling heat transfer of anti-freeze solutions, Propylene-glycol (PG)/water and Ethylene-glycol (EG)/water. The pool nucleate boiling experiments were carried out under a saturated and atmospheric condition. The platinum wire of 0.3 mm diameter was used as the heating surface. The mole fractions of solutions are varied from 0.85 to 1. It was found that the heat transfer coefficient gradually decreases with increasing fraction of anti-freeze to water. It was also shown that a small addition of propylene-glycol and ethylene-glycol also decreases the CHF value far below that of pure water. It is concluded that the correlation proposed by Fujita for several binary mixtures can well predict the heat transfer coefficients within almost ±5% accuracy for every concentration of present anti-freeze solutions.

Matsumura, Kunihito; Kaminaga, Fumito

326

The Effect of Subcooling on the Flow and Heat Transfer Characteristics in a Two-Phase Loop Thermosyphon  

NASA Astrophysics Data System (ADS)

A two-phase loop thermosyphon is used as a heat transfer device in an energy-saving heat transportation system and so forth, because it transports thermal energy without any external power supply such as a pump under a body force field. We previously performed a fundamental study on the flow and heat transfer characteristics in a two-phase loop thermosyphon installed with a single heated tube evaporator both experimentally and theoretically which was made under the condition of near saturation temperature of liquid in a reservoir. In the present study, the effects of liquid subcooling and the heat input on the circulation mass flow rates, pressure and temperature distributions, and heat transfer coefficients in the evaporator were examined experimentally using water, ethanol, benzene and Freon 113 as the working fluids. On the other hand, the circulation mass flow rates, pressure and temperature distributions were theoretically calculated and compared with the experimental results.

Imura, Hideaki; Takeshita, Kazuhiro; Doi, Kyoji; Noda, Ken-Ichi

327

Utilizing subcooled, superfluid He-II in the design of a 12-Tesla tandem-mirror experiment  

NASA Astrophysics Data System (ADS)

A design study of 12-T yin-yang coils for a conceptual tandem mirror next step (TMNS) facility was performed. The large magnets have major and minor radii of 3.7 and 1.5 m, 0.70 x 3.75 sq m cross section, 46.3 MA turns, and an overall current density of 1765 A/sq cm, obtained by the use of Nb3Sn and Nb-Ti superconductors. Each coil is composed of several subcoils separated by internal strengthening substructure to react the enormous electromagnetic forces. The size of the yin-yang coils, and hence the current density, was reduced by utilizing subcooled, superfluid He-II at 1.8 K for the coolant. The design study is reviewed with emphasis on He-II heat transport and conductor stability. Methods are also presented which allow the extension of Gorter-Mellink-channel calculations to encompass multiple, interconnecting coolant channels.

Hoard, R. W.; Cornish, D. N.; Baldi, R. W.; Taylor, W. D.

1981-11-01

328

Peptide synthesis in early earth hydrothermal systems  

USGS Publications Warehouse

We report here results from experiments and thermodynamic calculations that demonstrate a rapid, temperature-enhanced synthesis of oligopeptides from the condensation of aqueous glycine. Experiments were conducted in custom-made hydrothermal reactors, and organic compounds were characterized with ultraviolet-visible procedures. A comparison of peptide yields at 260??C with those obtained at more moderate temperatures (160??C) gives evidence of a significant (13 kJ ?? mol-1) exergonic shift. In contrast to previous hydrothermal studies, we demonstrate that peptide synthesis is favored in hydrothermal fluids and that rates of peptide hydrolysis are controlled by the stability of the parent amino acid, with a critical dependence on reactor surface composition. From our study, we predict that rapid recycling of product peptides from cool into near-supercritical fluids in mid-ocean ridge hydrothermal systems will enhance peptide chain elongation. It is anticipated that the abundant hydrothermal systems on early Earth could have provided a substantial source of biomolecules required for the origin of life. Astrobiology 9, 141-146. ?? 2009 Mary Ann Liebert, Inc. 2009.

Lemke, K. H.; Rosenbauer, R. J.; Bird, D. K.

2009-01-01

329

Fluid Flow Simulations of an Active Arc-Related Submarine Hydrothermal System  

NASA Astrophysics Data System (ADS)

Active high-temperature vents at the seafloor greatly contribute to the heat transport system at the Earth's surface and significantly influence the chemistry of crust and overlying ocean. While mid-ocean ridge systems have been intensely studied in the last decades, hydrothermal activity along convergent plate boundaries has received deeper attention only in the last few years. Brothers volcano is the most hydrothermally active volcano situated along the intra-oceanic Kermadec arc, northeast of North Island, New Zealand. Recent detailed surveys of hydrothermal plumes at Brothers volcano picture several distinct vent sites at different localities within the volcanic edifice. Venting ranges from lower temperature, gas-rich and metal-poor fluids to relatively high temperature (~300 °C), metal-rich fluids. However, the sub-surface structure of these systems and the contribution of magmatic sources are not well understood yet. In order to model the sub-seafloor hydrodynamics of Brothers volcano, a numerical transport scheme has been applied, using a combined finite element - finite volume method which computes multi-phase fluid flow and describes heat transport on basis of enthalpy, pressure, and salinity. Our process code covers the full phase relations of the binary NaCl-H2O system up to 1000 °C and accurately captures boiling, condensation, and salt precipitation. Numerical simulations for varying first-order physical parameters such as water depth and seafloor topography, rock permeability, and a heat source with or without a deep magmatic fluid source have been conducted. Our results show that seafloor topography controls the spatial distribution of venting sites and the input of a magmatic fluid source affects the style of hydrothermal venting. In this ongoing project, by combining simulation results with real observations in Brothers volcano and other currently active arc-related submarine volcanoes, we aim to present a new understanding of the sub-surface hydrology, the interaction of seawater with magmatic fluids, and subsequently the conditions to generate particularly Cu- and Au-rich mineralization within such magmatic-hydrothermal systems.

Gruen, G.; de Ronde, C. E.; Driesner, T.; Heinrich, C. A.

2009-12-01

330

Fluid Flow and Sound Generation at Hydrothermal Vent Fields.  

National Technical Information Service (NTIS)

Several experiments in this thesis examine methods to measure and monitor fluid flow from hydrothermal vent fields. Simultaneous velocity temperature, and conductivity data were collected in the convective flow emanating from a hydrothermal vent field loc...

S. A. Little

1988-01-01

331

Synthesis of hydrothermally stable, hierarchically mesoporous aluminosilicate Al-SBA-1 and their catalytic properties  

NASA Astrophysics Data System (ADS)

Hydrothermally stable mesoporous aluminosilicates Al-SBA-1 with hierarchical pore structure have been successfully synthesized under alkaline condition at 120 °C by employing organic mesomorphous complexes of polyelectrolyte (poly(acrylic acid) (PAA)) and cationic surfactant (hexadecyl pyridinium chloride (CPC)) as template. The Si/Al ratio could be as high as 5 and the incorporation of Al into the silica framework did not disturb the well-ordered cubic Pm3&cmb.macr;n mesostructure. Meanwhile, the incorporation of Al could greatly increase the specific surface area and pore volume of the samples. The Al-SBA-1 materials exhibited a high hydrothermal stability and remained stable even after being treated in boiling water for 10 days. The catalytic activity of the Al-SBA-1 materials was investigated by employing the Friedel-Crafts alkylation of toluene with benzyl alcohol as a model reaction and they exhibited excellent catalytic property due to the incorporated acid sites and the hierarchically mesoporous structure.

Li, Na; Wang, Jin-Gui; Xu, Jian-Xiong; Liu, Jin-Yu; Zhou, Hui-Jing; Sun, Ping-Chuan; Chen, Tie-Hong

2012-03-01

332

Phase separation, brine formation, and salinity variation at Black Smoker hydrothermal systems  

NASA Astrophysics Data System (ADS)

We present the first fully transient 2-D numerical simulations of black smoker hydrothermal systems using realistic fluid properties and allowing for all phase transitions possible in the system H2O-NaCl, including phase separation of convecting seawater into a low-salinity vapor and high-salinity brine. We investigate convection, multiphase flow, and phase segregation at pressures below, near, and above the critical point of seawater. Our simulations accurately predict the range in vent salinities, from 0.05 to 2.5 times seawater salinity measured at natural systems. In low-pressure systems at ˜1500 m water depth, phase separation occurs in boiling zones stretching from the bottom of the hydrothermal cell to the seafloor. Low-salinity vapors and high-salinity brines can vent simultaneously, and transient variations in vent fluid salinities can be rapid. In high-pressure systems at roughly ˜3500 m water depth, phase separation is limited to the region close to the underlying magma chamber, and vent fluids consist of a low-salinity vapor mixed with a seawater-like fluid. Therefore, vent salinities from these systems are much more uniform in time and always below seawater salinity as long as phase separation occurs in the subseafloor. Only by shutting down the heat source can, in the high-pressure case, the brine be mined, resulting in larger than seawater salinities. These numerical results are in good agreement with long-term observations from several natural black smoker systems.

Coumou, D.; Driesner, T.; Weis, P.; Heinrich, C. A.

2009-03-01

333

Synthesis of hydrothermally stable, hierarchically mesoporous aluminosilicate Al-SBA-1 and their catalytic properties.  

PubMed

Hydrothermally stable mesoporous aluminosilicates Al-SBA-1 with hierarchical pore structure have been successfully synthesized under alkaline condition at 120 °C by employing organic mesomorphous complexes of polyelectrolyte (poly(acrylic acid) (PAA)) and cationic surfactant (hexadecyl pyridinium chloride (CPC)) as template. The Si/Al ratio could be as high as 5 and the incorporation of Al into the silica framework did not disturb the well-ordered cubic Pm ?3n mesostructure. Meanwhile, the incorporation of Al could greatly increase the specific surface area and pore volume of the samples. The Al-SBA-1 materials exhibited a high hydrothermal stability and remained stable even after being treated in boiling water for 10 days. The catalytic activity of the Al-SBA-1 materials was investigated by employing the Friedel-Crafts alkylation of toluene with benzyl alcohol as a model reaction and they exhibited excellent catalytic property due to the incorporated acid sites and the hierarchically mesoporous structure. PMID:22327221

Li, Na; Wang, Jin-Gui; Xu, Jian-Xiong; Liu, Jin-Yu; Zhou, Hui-Jing; Sun, Ping-Chuan; Chen, Tie-Hong

2012-02-10

334

Seismicity and fluid geochemistry at Lassen Volcanic National Park, California: Evidence for two circulation cells in the hydrothermal system  

USGS Publications Warehouse

Seismic analysis and geochemical interpretations provide evidence that two separate hydrothermal cells circulate within the greater Lassen hydrothermal system. One cell originates south to SW of Lassen Peak and within the Brokeoff Volcano depression where it forms a reservoir of hot fluid (235-270 ??C) that boils to feed steam to the high-temperature fumarolic areas, and has a plume of degassed reservoir liquid that flows southward to emerge at Growler and Morgan Hot Springs. The second cell originates SSE to SE of Lassen Peak and flows southeastward along inferred faults of the Walker Lane belt (WLB) where it forms a reservoir of hot fluid (220-240 ??C) that boils beneath Devils Kitchen and Boiling Springs Lake, and has an outflow plume of degassed liquid that boils again beneath Terminal Geyser. Three distinct seismogenic zones (identified as the West, Middle, and East seismic clusters) occur at shallow depths (< 6 km) in Lassen Volcanic National Park, SW to SSE of Lassen Peak and adjacent to areas of high-temperature (??? 161 ??C) fumarolic activity (Sulphur Works, Pilot Pinnacle, Little Hot Springs Valley, and Bumpass Hell) and an area of cold, weak gas emissions (Cold Boiling Lake). The three zones are located within the inferred Rockland caldera in response to interactions between deeply circulating meteoric water and hot brittle rock that overlies residual magma associated with the Lassen Volcanic Center. Earthquake focal mechanisms and stress inversions indicate primarily N-S oriented normal faulting and E-W extension, with some oblique faulting and right lateral shear in the East cluster. The different focal mechanisms as well as spatial and temporal earthquake patterns for the East cluster indicate a greater influence by regional tectonics and inferred faults within the WLB. A fourth, deeper (5-10 km) seismogenic zone (the Devils Kitchen seismic cluster) occurs SE of the East cluster and trends NNW from Sifford Mountain toward the Devils Kitchen thermal area where fumarolic temperatures are ??? 123 ??C. Lassen fumaroles discharge geothermal gases that indicate mixing between a N2-rich, arc-type component and gases derived from air-saturated meteoric recharge water. Most gases have relatively weak isotopic indicators of upper mantle or volcanic components, except for gas from Sulphur Works where ??13C-CO2, ??34S-H2S, and ??15N-N2 values indicate a contribution from the mantle and a subducted sediment source in an arc volcanic setting.

Janik, C. J.; McLaren, M. K.

2010-01-01

335

Seismicity and fluid geochemistry at Lassen Volcanic National Park, California: Evidence for two circulation cells in the hydrothermal system  

NASA Astrophysics Data System (ADS)

Seismic analysis and geochemical interpretations provide evidence that two separate hydrothermal cells circulate within the greater Lassen hydrothermal system. One cell originates south to SW of Lassen Peak and within the Brokeoff Volcano depression where it forms a reservoir of hot fluid (235-270 °C) that boils to feed steam to the high-temperature fumarolic areas, and has a plume of degassed reservoir liquid that flows southward to emerge at Growler and Morgan Hot Springs. The second cell originates SSE to SE of Lassen Peak and flows southeastward along inferred faults of the Walker Lane belt (WLB) where it forms a reservoir of hot fluid (220-240 °C) that boils beneath Devils Kitchen and Boiling Springs Lake, and has an outflow plume of degassed liquid that boils again beneath Terminal Geyser. Three distinct seismogenic zones (identified as the West, Middle, and East seismic clusters) occur at shallow depths (< 6 km) in Lassen Volcanic National Park, SW to SSE of Lassen Peak and adjacent to areas of high-temperature (? 161 °C) fumarolic activity (Sulphur Works, Pilot Pinnacle, Little Hot Springs Valley, and Bumpass Hell) and an area of cold, weak gas emissions (Cold Boiling Lake). The three zones are located within the inferred Rockland caldera in response to interactions between deeply circulating meteoric water and hot brittle rock that overlies residual magma associated with the Lassen Volcanic Center. Earthquake focal mechanisms and stress inversions indicate primarily N-S oriented normal faulting and E-W extension, with some oblique faulting and right lateral shear in the East cluster. The different focal mechanisms as well as spatial and temporal earthquake patterns for the East cluster indicate a greater influence by regional tectonics and inferred faults within the WLB. A fourth, deeper (5-10 km) seismogenic zone (the Devils Kitchen seismic cluster) occurs SE of the East cluster and trends NNW from Sifford Mountain toward the Devils Kitchen thermal area where fumarolic temperatures are ? 123 °C. Lassen fumaroles discharge geothermal gases that indicate mixing between a N2-rich, arc-type component and gases derived from air-saturated meteoric recharge water. Most gases have relatively weak isotopic indicators of upper mantle or volcanic components, except for gas from Sulphur Works where ?13C-CO2, ?34S-H2S, and ?15N-N2 values indicate a contribution from the mantle and a subducted sediment source in an arc volcanic setting.

Janik, Cathy J.; McLaren, Marcia K.

2010-01-01

336

Formation of a hydrothermal reservoir due to anhydrite precipitation in an arc volcano hydrothermal system  

NASA Astrophysics Data System (ADS)

Anhydrite precipitation strongly affects the circulation of hydrothermal systems by changing the permeability structure of the oceanic crust. For example, a hydrothermal reservoir capped by anhydrite precipitates was found beneath the caldera floor of Suiyo Seamount of the Izu-Bonin Arc. We interpret the precipitation to be due to alternating layers of lavas and tephras, typical of arc volcanos, because the layering gives rise to the mixing of high-temperature hydrothermal fluids with low-temperature seawater at layer boundaries. We thus perform two-dimensional numerical simulations of subseafloor fluid flow in a two-layer porous medium to model the shallowest part of the discharge zone near the summit of an arc volcano. The upper layer is set to be more permeable than the lower one. High-temperature Ca2+-rich hydrothermal fluid flows in from the bottom, and low-temperature SO42--rich seawater flows in from the seafloor. The two fluids meet at the layer boundary, precipitating anhydrite, which serves as the ceiling of a hydrothermal reservoir. Anhydrite precipitates form also in the upper layer, serving as conduit walls for upwelling hydrothermal fluid. When the permeability of the upper layer is in the range 10-10-10-12 m2, which is typical for unconsolidated volcanic pumice, the pattern of the circulation stabilizes in about 0.5-40 years. The circulation structure and the timescale of its formation are similar to those of the hydrothermal system on Suiyo Seamount.

Kawada, Yoshifumi; Yoshida, Shigeo

2010-11-01

337

Solidification of coal fly ash using hydrothermal processing method  

Microsoft Academic Search

Solidification of Coal Fly-ash (CFA) has been carried out using a hydrothermal processing method. In the hydrothermal processing,\\u000a the CFA was first compacted in a mold at 20 - 50 MPa, and then hydrothermally cured in an autoclave. The hydrothermal curing\\u000a was performed at 150 – 250C for 15 – 60 h. The experimental results showed that NaOH solution, Ca(OH)2

Z. Jing; N. Matsuoka; F. Jin; N. Yamasaki; K. Suzuki; T. Hashida

2006-01-01

338

Destruction of halogenated organics with hydrothermal processing  

NASA Astrophysics Data System (ADS)

Chemical reactions in high temperature water (hydrothermal processing) allow new avenues for effective waste treatment and radionuclide separation. Successful implementation of hydrothermal technologies offers the potential to effectively treat many types of radioactive waste and reduce the storage hazards and the disposal costs, while minimizing the generation of hazardous secondary waste streams.1-5 Halogenated hazardous organic liquids containing actinides are a difficult to treat category of TRU radioactive wastes. These liquids are typically used for degreasing operations or density measurements and can include trichlorethylene and bromobenzene. Experiments have demonstrated that hydrothermal processes can eliminate hazardous halogenated organics generated by the nuclear industry by the complete oxidation of the organic components to CO2 and H2O. .

Worl, Laura A.; Buelow, Steven J.; Harradine, David M.; Hill, Dallas; McInroy, Rhonda; Padilla, Dennis

2000-07-01

339

Hydrothermal pretreatment of bamboo and cellulose degradation.  

PubMed

A systematic hydrothermal pretreatment of bamboo chips had been conducted with an aim to trace the cellulose degradation. The results showed that cellulose chain cleavage basically occurred when the temperature exceeded 150°C. A slightly higher DP (degree of polymerization) than starting material had been observed at low temperature pretreatment. Treatment at higher temperature (?170°C) caused severe cleavage of cellulose and therefore gave rise to low DP with more soluble species. DP of cellulose declined drastically without additional hemicelluloses dissolution when hemicelluloses removal reached to the limit level. Cellulose degradation under hydrothermal pretreatment generally followed the zero reaction kinetics with the activity energy of 121.0kJ/mol. Besides, the increase of cellulose crystalline index and the conversion of I?-I? had also observed at the hydrothermal pretreatment. PMID:24077149

Ma, X J; Cao, S L; Lin, L; Luo, X L; Hu, H C; Chen, L H; Huang, L L

2013-09-13

340

Characterization of advanced preprocessed materials (Hydrothermal)  

SciTech Connect

The initial hydrothermal treatment parameters did not achieve the proposed objective of this effort; the reduction of intrinsic ash in the corn stover. However, liquid fractions from the 170°C treatments was indicative that some of the elements routinely found in the ash that negatively impact the biochemical conversion processes had been removed. After reviewing other options for facilitating ash removal, sodium-citrate (chelating agent) was included in the hydrothermal treatment process, resulting in a 69% reduction in the physiological ash. These results indicated that chelation –hydrothermal treatment is one possible approach that can be utilized to reduce the overall ash content of feedstock materials and having a positive impact on conversion performance.

Rachel Emerson; Garold Gresham

2012-09-01

341

Hydrothermal processing of radioactive combustible waste  

SciTech Connect

Hydrothermal processing has been demonstrated for the treatment of radioactive combustible materials for the US Department of Energy. A hydrothermal processing system was designed, built and tested for operation in a plutonium glovebox. Presented here are results from the study of the hydrothermal oxidation of plutonium and americium contaminated organic wastes. Experiments show the destruction of the organic component to CO{sub 2} and H{sub 2}O, with 30 wt.% H{sub 2}O{sub 2} as an oxidant, at 540 C and 46.2 MPa. The majority of the actinide component forms insoluble products that are easily separated by filtration. A titanium liner in the reactor and heat exchanger provide corrosion resistance for the oxidation of chlorinated organics. The treatment of solid material is accomplished by particle size reduction and the addition of a viscosity enhancing agent to generate a homogeneous pumpable mixture.

Worl, L.A.; Buelow, S.J.; Harradine, D.; Le, L.; Padilla, D.D.; Roberts, J.H.

1998-09-01

342

New equations predict boiling point from viscosity, gravity  

SciTech Connect

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

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

1996-10-07

343

Ecology of deep-sea hydrothermal vent communities: A review  

Microsoft Academic Search

The present article reviews studies of the past 15 years of active and inactive hydrothermal vents. The focus of the discussion is on the ecology of the biological communities inhabiting hydrothermal vents. These communities exhibit high densities and biomass, low species diversity, rapid growth rates, and high metabolic rates. The authors attempt to relate the biology of hydrothermal vent systems

Richard A. Lutz; Michael J. Kennish

1993-01-01

344

A hydrothermal hot-pressing method: Apparatus and application  

Microsoft Academic Search

Loose particles occurring in sediment are transformed into sedimentary rock by a process termed lithification, which is a chemical process that reduces the original porosity by compaction and cementation [1]. A hydrothermal hot-pressing method is intended for artificial lithification. In this study, silica powder including mineralizer solution is compressed under hydrothermal conditions from outside an autoclave for hydrothermal hot-pressing and

N. Yamasaki; K. Yanagisawa; M. Nishioka; S. Kanahara

1986-01-01

345

Zinc stable isotopes in seafloor hydrothermal vent fluids and chimneys  

Microsoft Academic Search

Many of the heaviest and lightest natural zinc (Zn) isotope ratios have been discovered in hydrothermal ore deposits. However, the processes responsible for fractionating Zn isotopes in hydrothermal systems are poorly understood. In order to better assess the total range of Zn isotopes in hydrothermal systems and to understand the factors which are responsible for this isotopic fractionation, we have

Seth G. John; Olivier J. Rouxel; Paul R. Craddock; Alison M. Engwall; Edward A. Boyle

2008-01-01

346

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

NASA Astrophysics Data System (ADS)

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

Özdemir, Mustafa; Pehlivan, Hüseyin

2008-05-01

347

A new critical heat flux correlation for boiling liquid metals  

SciTech Connect

This paper reports on correlations for the dryout heat flux for sodium in tube and grid bundles that have been developed based on experimental results and analytical considerations. The main feature of these correlations is that they are derived from thermal, hydrodynamic, and geometrical parameters. These parameters are the subcooling, the inlet and outlet vapor quality, the mass flow rate, the latent heat of vaporization, and the aspect ratio. The correlation proposed for tube geometries is developed from a data base of 170 data points compiled from 11 sources, and the correlation for flow through rod bundles is derived from the results of 13 tests.

Kottowski, H.M.; Savatteri, C.; Hufschmidt, W. (Commission of the European Communities, Joint Research Center, Ispra Establishment, 21020 Ispra (IT))

1991-08-01

348

Sonar images hydrothermal vents in seafloor observatory  

NASA Astrophysics Data System (ADS)

Hydrothermal plumes venting from black smokers and diffuse flow discharging from the surrounding area of the seafloor are important as agents of transfer of heat, chemicals, and biological material from the crust into the ocean in quantitatively significant amounts [Elderfield and Schultz, 1996]. An unprecedented time series of three-dimensional (3-D) volume images of plumes rising tens of meters from black smoker vents and of concurrent 2-D maps of diffuse flow discharging from surrounding areas of the seafloor illuminates the turbulent behavior of hydrothermal fluid transfer into the ocean (see Figure 1).

Rona, Peter; Light, Russ

2011-05-01

349

Synthesis of gadolinium silicate by hydrothermal method  

NASA Astrophysics Data System (ADS)

A simple method based on hydrothermal synthesis of materials to prepare gadolinium silicate has been prescribed. It is found that molar ratio of Gd(NO3)3: TEOS plays a crucial role in the formation of Gd2SiO5. The effect of calcinations, concentration of the precipitating agent and dopant atoms on composition and morphology of the synthesized materials has been investigated. The desired phase of Gd2SiO5 can be synthesized from hydrothermally grown powder after annealing at 1400°C.

Shinde, Seema; Ghosh, M.; Sen, Shashwati; Singh, S. G.; Gadkari, S. C.; Gupta, S. K.

2013-02-01

350

Critical boiling phenomena observed in microgravity  

NASA Astrophysics Data System (ADS)

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

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

1999-06-01

351

Critical Heat Flux for Downward Facing Boiling on a Coated Hemispherical Surface  

Microsoft Academic Search

An experimental study was performed to investigate the effect of surface coating on the critical heat flux for downward facing boiling on the outer surface of a hemispherical vessel. Steady-state boiling experiments were conducted in the subscale boundary layer boiling (SBLB) facility using test vessels with metallic microporous coatings to obtain the local boiling curves and the local critical heat

J. Yang; M. B. Dizon; F. B. Cheung; J. L. Rempe; K. Y. Suh; S. B. Kim

2005-01-01

352

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

ERIC Educational Resources Information Center

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

Struyf, Jef

2011-01-01

353

BOILING HOUSE, INTERIOR, SECOND FLOOR, CLARIFIERS, SIEP TO THE LEFT, ...  

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

BOILING HOUSE, INTERIOR, SECOND FLOOR, CLARIFIERS, SIEP TO THE LEFT, WITH CLARIFIER FLASH TANK ABOVE, SAMPLING STATION TO THE LEFT. VIEW FROM THE SOUTHEAST - Kekaha Sugar Company, Sugar Mill Building, 8315 Kekaha Road, Kekaha, Kauai County, HI

354

BOILING HOUSE, SECOND FLOOR, FROM TOP OF GARVER CLARIFIER, MUD ...  

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

BOILING HOUSE, SECOND FLOOR, FROM TOP OF GARVER CLARIFIER, MUD FILTERS AND CAUSTIC SODA TANKS TO THE LEFT. VIEW FROM THE EAST - Kekaha Sugar Company, Sugar Mill Building, 8315 Kekaha Road, Kekaha, Kauai County, HI

355

20. RW Meyer Sugar Mill: 18761889. Boiling House Interior, 1878. ...  

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

20. RW Meyer Sugar Mill: 1876-1889. Boiling House Interior, 1878. View: Remains of south wall. The molasses storage pits are below the floor in the foreground. The remaining piece of floor indicates the form of the entire floor. The sorghum pan and boiling range flue slope from left to right (east to west) and permitted batches of cane juice to flow through the boiling pan by gravity. The beams, joists, truss work are built of northwest pine. The sides and floor boards are built of redwood. The boiling range flue is built of fire-brick, masonry, and portland cement. The corrugated roof appears to be a later addition, not contemporary with mill operation. - R. W. Meyer Sugar Mill, State Route 47, Kualapuu, Maui County, HI

356

BOILING HOUSE, GROUND FLOOR, ABANDONED SUGAR BIN IN CENTER. IN ...  

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

BOILING HOUSE, GROUND FLOOR, ABANDONED SUGAR BIN IN CENTER. IN BACKGROUND, THE ELEVATOR AND STAIRS GOING UP. VIEW FROM SOUTHWEST - Lihue Plantation Company, Sugar Mill Building, Haleko Road, Lihue, Kauai County, HI

357

BOILING HOUSE, INTERIOR, SECOND FLOOR, GARVER CLARIFIER IN FOREGROUND, TOPS ...  

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

BOILING HOUSE, INTERIOR, SECOND FLOOR, GARVER CLARIFIER IN FOREGROUND, TOPS OF LONG TUBE EVAPORATORS IN BACKGROUND. VIEW FROM NORTHWEST - Kekaha Sugar Company, Sugar Mill Building, 8315 Kekaha Road, Kekaha, Kauai County, HI

358

BOILING HOUSE, INTERIOR, SECOND FLOOR, SYRUP TANKS IN RIGHT FOREGROUND, ...  

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

BOILING HOUSE, INTERIOR, SECOND FLOOR, SYRUP TANKS IN RIGHT FOREGROUND, HIGH GRADE VACUUM PANS BEYOND THE SYRUP TANKS. VIEW FROM THE SOUTH - Kekaha Sugar Company, Sugar Mill Building, 8315 Kekaha Road, Kekaha, Kauai County, HI

359

BOILING HOUSE, GROUND FLOOR. WAREHOUSE TO LEFT REAR, MASSECUITTE HEATERS ...  

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

BOILING HOUSE, GROUND FLOOR. WAREHOUSE TO LEFT REAR, MASSECUITTE HEATERS ABOVE RIGHT, LOW GRADE CENTRIFUGALS BELOW. CRYSTALLIZER HOT WATER TANK TO REAR. VIEW FROM NORTHEAST - Lihue Plantation Company, Sugar Mill Building, Haleko Road, Lihue, Kauai County, HI

360

Film Boiling on Downward Quenching Hemisphere of Varying Sizes  

SciTech Connect

Film boiling heat transfer coefficients for a downward-facing hemispherical surface are measured from the quenching tests in DELTA (Downward-boiling Experimental Laminar Transition Apparatus). Two test sections are made of copper to maintain low Biot numbers. The outer diameters of the hemispheres are 120 mm and 294 mm, respectively. The thickness of all the test sections is 30 mm. The effect of diameter on film boiling heat transfer is quantified utilizing results obtained from the test sections. The measured data are compared with the numerical predictions from laminar film boiling analysis. The measured heat transfer coefficients are found to be greater than those predicted by the conventional laminar flow theory on account of the interfacial wavy motion incurred by the Helmholtz instability. Incorporation of the wavy motion model considerably improves the agreement between the experimental and numerical results in terms of heat transfer coefficient. In addition, the interfacial wavy motion and the quenching process are visualized through a digital camera.

Chan S. Kim; Kune Y. Suh; Joy L. Rempe; Fan-Bill Cheung; Sang B. Kim

2004-04-01

361

EAST ELEVATION OF THE ELECTRIC SHOP. BOILING HOUSE AND POWER ...  

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

EAST ELEVATION OF THE ELECTRIC SHOP. BOILING HOUSE AND POWER HOUSE WING IN THE BACKGROUND. VIEW FROM THE SOUTHEAST - Lihue Plantation Company, Sugar Mill Building, Haleko Road, Lihue, Kauai County, HI

362

Release and evaporation of volatiles during boiling of unhopped wort.  

PubMed

The release and evaporation of volatile compounds was studied during boiling of wort. The observed parameters were boiling time, boiling intensity, wort pH, and wort density. The effect of every parameter was discussed and approached chemically, with an eye on beer-aging processes. The results indicated that pH highly influenced the release of flavor compounds and that the formation of Strecker aldehydes was linear with boiling time. However, because of evaporation of volatiles, information about the applied thermal load on wort is lost when using a volatile heat load indicator. The thiobarbituric acid (TBA) method, which includes the nonvolatile precursors of volatile aging compounds, proved to be a more reliable method to determine all kinds of heat load on wort. Finally, it was discussed how the obtained insights could help to understand the mechanism of beer aging. PMID:18547048

De Schutter, David P; Saison, Daan; Delvaux, Filip; Derdelinckx, Guy; Rock, Jean-Marie; Neven, Hedwig; Delvaux, Freddy R

2008-06-12

363

Hydrothermal brecciation in the Jemez Fault zone, Valles Caldera, New Mexico: Results from CSDP (Continental Scientific Drilling Program) corehole VC-1  

SciTech Connect

Paleozoic and Precambrian rocks intersected deep in Continental Scientific Drilling Program corehole VC-1, adjacent to the late Cenozoic Valles caldera complex, have been disrupted to form a spectacular breccia sequence. The breccias are of both tectonic and hydrothermal origin, and probably formed in the Jemez fault zone, a major regional structure with only normal displacement since mid-Miocene. Tectonic breccias are contorted, crushed, sheared, and granulated; slickensides are commmon. Hydrothermal breccias, by contrast, lack these frictional textures, but arej commonly characterized by fluidized matrix foliation and prominent clast rounding. Fluid inclusions in the hydrothermal breccias are dominantly two-phase, liquid-rich at room temperature, principally secondary, and form two distinctly different compositional groups. Older inclusions, unrelated to brecciation, are highly saline and homogenize to the liquid phase in the temperature range 189 to 246/sup 0/C. Younger inclusions, in part of interbreccia origin, are low-salinity and homogenize (also to liquid) in the range 230 to 283/sup 0/C. Vapor-rich inclusions locally trapped along with these dilute liquid-rich inclusions document periodic boiling. These fluid-inclusion data, together with alteration assemblages and textures as well as the local geologic history, have been combined to model hydrothermal brecciation at the VC-1 site.

Hulen, J.B.; Nielson, D.L.

1987-06-01

364

Boiling and condensing pumped loop microgravity experiment  

NASA Astrophysics Data System (ADS)

Aircraft testing of a boiling and condensing (two-phase) pumped loop system was conducted to investigate transient induced by low gravity (Keplerian) maneuvers. The experiment, unchanged, will repeat a selected aircraft test sequence during its flight aboard a suborbital rocket. Such a test of a two-phase system has never been done. A comparison of aircraft and rocket data, particularly equilibrium conditions, may validate aircraft testing of similar systems: Aircraft testing has been completed and preliminary results indicate that local transients induced by Keplerian maneuvers do not generate sizeable or lasting feedback. System feedback, expected to damp exponentially with loop transit time, ?loop (20 s

Standley, Vaughn H.; Fairchild, Jerry F.

1991-01-01

365

Boiling and condensing pumped loop microgravity experiment  

SciTech Connect

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

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

1991-01-10

366

A microgravity boiling and convective condensation experiment  

NASA Astrophysics Data System (ADS)

A boiling and condensing test article consisting of two straight tube boilers, one quartz and one stainless steel, and two 1.5 m long glass-in-glass heat exchangers, on 6 mm ID and one 10 mm ID, was flown on the NASA KC-135 0-G aircraft. Using water as the working fluid, the 5 kw boiler produces two phase mixtures of varying quality for mass flow rates between 0.005 and 0.1 kg/sec. The test section is instrumented at eight locations with absolute and differential pressure transducers and thermocouples. A gamma densitometer is used to measure void fraction, and high speed photography records the flow regimes. A three axis accelerometer provides aircraft acceleration data (+ or - 0.01G). Data are collected via an analog-to-digital conversion and data acquisition system. Bubbly, annular, and slug flow regimes were observed in the test section under microgravity conditions. Flow oscillations were observed for some operating conditions and the effect of the 2-G pullout prior to the 0-G period was observed by continuously recording data throughout the parabolas. A total fo 300 parabolas was flown.

Kachnik, Leo; Lee, Doojeong; Best, Frederick; Faget, Nanette

1987-12-01

367

Boiling of droplets on a hot surface in low gravity  

Microsoft Academic Search

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

Y. M. Qiao; S. Chandra

1996-01-01

368

16. RW Meyer Sugar Mill: 18761889. Boiling House Interior, 1878. ...  

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

16. RW Meyer Sugar Mill: 1876-1889. Boiling House Interior, 1878. View: Looking from west to east through boiling house. The sorghum pan is on the right. The beams; joists, and trusses are of northwest pine; side boards are of redwood. A foundation line of a loading dock and smokestack are in the foreground. Both end walls have deteriorated completely. - R. W. Meyer Sugar Mill, State Route 47, Kualapuu, Maui County, HI

369

Pool Boiling Heat Transfer of Aqueous Surfactant Solutions  

Microsoft Academic Search

for a range of heat flux (24.7-109.1 kW\\/m 2 ) and mass concentrations (50-8000 ppm for SDS and 20-1000 ppm for Triton X-114). The bubble observations show that, when compared with water, boiling in surfactant solutions is observed to be more vigorous with smaller-sized and fast departure frequency. The surfactant solutions of Triton X-114 is becoming cloudy during boiling at

Hu Zicheng; Gu Jiaqiang; Song Xinnan; Wang Qian

2011-01-01

370

Visualization and measurements of periodic boiling in silicon microchannels  

Microsoft Academic Search

A simultaneous visualization and measurement investigation has been carried out on flow boiling of water in parallel silicon microchannels of trapezoidal cross-section. Two sets of parallel microchannels, having hydraulic diameters of 158.8 and 82.8 ?m, respectively, were used. The visualization study shows that once boiling heat transfer is established, two-phase flow and single-phase liquid flow appear alternatively with time in

H. Y. Wu; Ping Cheng

2003-01-01

371

Electrohydrodynamically enhanced flow boiling in an eccentric horizontal cylindrical channel  

Microsoft Academic Search

Experimental and numerical investigations have been conducted to study the effect of electrode position in a 10.92 cm i.d. cylindrical flow channel on the electrohydrodynamically (EHD) enhanced flow boiling. The experiments were conducted for tube-side boiling of HFC-134a at dc voltage from 0 to 8 kV, liquid mass flux from 0 to 500 kg\\/m2s, inlet quality from 0 to 50%,

J. S. Cotton; J. S. Chang; M. Shoukri; T. Smith-Pollard

2002-01-01

372

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

373

Hydrothermal Growth of Crystals of LAALO3.  

National Technical Information Service (NTIS)

LaAlO3 has been successfully grown in a hydrothermal system below and above the transition temperature of 435C. Using small autoclaves, growth has been observed in the temperature range of 400C - 600C in 7 m K2CO3 at 10,000 to 20,000 psi. A high pressure ...

1964-01-01

374

The Discovery of Marine Hydrothermal Vents  

NSDL National Science Digital Library

As part of OceanLink, a website dedicated to ocean education, this site gives an overview of the discovery, geology and ecology of marine hydrothermal vents. The site also provides a menu of links to access other OceanLink pages for further ocean-related information.

Oceanlink

375

Soptimum Operation of a Hydrothermal System  

Microsoft Academic Search

Variational methods are used to develop co-ordination equations for use in the digital computer solution of the optimum operation of a hydrothermal system with series plants, multiple chains of plants, and intermediate reservoirs. These techniques have been applied in a program which integrates the hydroelectric and steam resources of the Southern California Edison Company for up to a week's period.

J. H. Drake; L. K. Kirchmayer; R. B. Mayall; H. Wood

1962-01-01

376

Merging Genomes with Geochemistry in Hydrothermal Ecosystems  

Microsoft Academic Search

Thermophilic microbial inhabitants of active seafloor and continental hot springs populate the deepest branches of the universal phylogenetic tree, making hydrothermal ecosystems the most ancient continuously inhabited ecosystems on Earth. Geochemical consequences of hot water-rock interactions render these environments habitable and supply a diverse array of energy sources. Clues to the strategies for how life thrives in these dynamic ecosystems

Anna-Louise Reysenbach; Everett Shock

2002-01-01

377

Hydrothermal reaction of fly ash. Final report  

Microsoft Academic Search

The reactions which occur when fly ash is treated under hydrothermal conditions were investigated. This was done for the following primary reasons. The first of these is to determine the nature of the phases that form to assess the stabilities of these phases in the ambient environment and, finally, to assess whether these phases are capable of sequestering hazardous species.

1994-01-01

378

Hydrothermal carbonization of distiller’s grains  

Microsoft Academic Search

Wet distiller’s grains are intermediate byproducts of ethanol manufacture that have high moisture contents and require significant energy for drying and conversion into dry distiller’s grains. Hydrothermal carbonization was investigated as a wet process to provide alternative products, and chars were obtained in moderate yield that possessed high heats of combustion. The mechanism of char formation was also investigated employing

Steven M. Heilmann; Lindsey R. Jader; Michael J. Sadowsky; Frederick J. Schendel; Marc G. von Keitz; Kenneth J. Valentas

2011-01-01

379

Numerical Simulations of Europa Hydrothermal Plumes  

Microsoft Academic Search

The liquid water interiors of Europa and other icy moons of the outer solar system are likely to be driven by geothermal heating from the sea floor, leading to the development of buoyant hydrothermal plumes. These plumes potentially control icy surface geomorphology, and are of interest to astrobiologists. We have performed a series of simulations of these plumes using the

J. C. Goodman; E. Lenferink

2009-01-01

380

Modern methods for hydrothermal synthesis of ZrO 2 -based nanocrystalline powders  

Microsoft Academic Search

Hydrothermal decomposition, hydrothermal crystallization, hydrothermal homogeneous precipitation, microwave hydrothermal synthesis,\\u000a ultrasonic-assisted hydrothermal synthesis, hydrothermal synthesis under supercritical conditions, which are used to produce\\u000a ZrO2-based nanocrystalline powders, are considered. It is established that the nucleation and particle growth can be controlled\\u000a in hydrothermal synthesis (through concentration change, increase or decrease in hydrolysis temperature, increase in hydrolysis\\u000a time, introduction of surface active

E. V. Dudnik

2009-01-01

381

VLA Shows "Boiling" in Atmosphere of Betelgeuse  

NASA Astrophysics Data System (ADS)

A team of astronomers says that observations with the National Science Foundation's Very Large Array (VLA) radio telescope show that a neighboring bloated star has giant convective plumes propelling gas from its surface (photosphere) up into the star's atmosphere. This new information contradicts long-held ideas that such stellar atmospheres are more uniform, and may resolve questions about how the star's atmosphere attains its enormous size as well as how dust and gas is driven away from the star. Jeremy Lim of the Academia Sinica Institute of Astronomy & Astrophysics in Taiwan; Chris Carilli, Anthony Beasley, and Ralph Marson of the National Radio Astronomy Observatory (NRAO) in Socorro, NM; and Stephen White of the University of Maryland studied the red-supergiant star Betelgeuse, about 430 light-years away in the constellation Orion. They reported their findings in the April 9 issue of the scientific journal Nature. "These radio-telescope images confirm that Betelgeuse -- already more than 600 times larger than our Sun -- has a dense atmosphere that extends to many times larger still than the star itself," said Lim. "The highest-resolution image shows the star's atmosphere to have a remarkably complex structure." "To our surprise," added White, "the images also show that most of the gas in the atmosphere is only about as hot as that on the surface. Previously, all of it was thought to be very much hotter." The astronomers used the VLA to make images of Betelgeuse at a variety of radio frequencies. The series of radio observations measured the temperature of the star's atmosphere at different heights. Previous observations with the Hubble Space Telescope (HST) at ultraviolet wavelengths showed that the star's atmosphere contains very hot gas at about twice the surface temperature. The VLA images showed that there also is lower-temperature gas throughout the atmosphere. This gas is near the surface temperature at low heights and decreases in temperature progressively outwards. Although its existence was not previously suspected, this lower-temperature gas turns out to be the most abundant constituent of Betelgeuse's atmosphere. "This alters our basic understanding of red-supergiant star atmospheres," explains Lim. "Instead of the star's atmosphere expanding uniformly because of gas heated to very high temperatures near its surface, it now appears that several giant convection cells propel gas from the star's surface into its atmosphere. This creates the complex structure we observe for Betelgeuse's atmosphere." Betelgeuse can be likened to an enormous "boiling" ball of gas heated by the release of energy from nuclear fusion in its core. The circulating boiling pattern -- convection -- appears as large regions of hot upwelling gas on the star's surface. "The idea that red-supergiant stars have enormous convection cells is not new," noted Marson. "This was suggested by Martin Schwarzschild more than 20 years ago, and was seen in optical images of Betelgeuse's surface in 1990." The new picture of Betelgeuse's atmosphere also helps resolve the mystery of how massive amounts of dust and gas are expelled from red supergiant stars, an important source of enrichment for the interstellar medium. If their atmospheres were entirely very hot at lower levels, dust grains would not be able to condense there. Dust grains could possibly condense at higher levels, but there they would not get enough "push" from the star's radiation to explain their outward movement. In the new picture, the relatively cool environment at lower levels allows dust grains to condense effectively; here they can be strongly propelled by the more-intense starlight, carrying gas with them. Indeed, dust has previously been inferred to form sporadically near Betelgeuse's surface, but its presence there was difficult to reconcile with the old picture. "This method for propelling the mass outflows of red giant and supergiant stars was proposed by Sun Kwok i

1998-04-01

382

Prediction of subcooled vapor pressures (log PL) of 399 polychlorinated trans-azoxybenzenes by using the QSPR and ANN approach.  

PubMed

Environmentally relevant partitioning properties such as the sub-cooled vapor pressures (log PL) have been predicted for 399 congeners of chloro-trans-azoxybenzene (C-t-AOBs) by two computational methods. The quantitative structure-property relationship (QSPR), an approach which is based on geometry optimalization and quantum-chemical structural descriptors in RM1 and DFT methods and artificial neural networks (ANNs), an approach that predicts abilities that give similar results of estimated log P(L) and the accuracy of the methods was also similar. The RM1 method was less time consuming and less costly compared to calculations by the DFT method. Estimated from the RM1 and DFT methods of log P(L) values of 399 Ct-AOBs varied between -1.98 to -0.93 and -1.83 to -0.79 for Mono-, 3.12 to -1.46 and -3.00 to -1.46 for Di-, -4.03 to -1.39 and -3.53 to -1.67 for Tri-, -4.75 to -2.33 and -4.59 to -1.91 for Tetra-, -5.37 to -2.59 and -5.42 to -2.09 for Penta-, -5.82 to -2.88 and -5.66 to -2.58 for Hexa-, -5.88 to -3.24 and -5.60 to -2.93 for Hepta-, -6.28 to -4.33 and -5.60 to -4.29 for Octa-, -6.54 to -5.28 and -5.66 to -4.93 for NonaCt-AOBs, and -6.59 and -5.61 for DecaCt-AOB. According to a common classification of environmental contaminants and by sub-cooled vapor pressure values, MonoCt-AOBs and a few of the Di- and TriCt-AOBs (log P(L)from -2 to 0) fall into the group of compounds that are relatively well mobile in the ambient environment, while most of the Di- to HeptaCt-AOBs (log P(L) < -4 to -2) mobility is relatively weak. Octa- and NonaCt-AOBs and DecaCt-AOB (log P(L) < -4) are also weak mobile contaminants. PMID:22320698

Piliszek, S?awomir; Wilczy?ska-Piliszek, Agata J; Falandysz, Jerzy

2012-01-01

383

The main factors controlling petrophysical alteration in hydrothermal systems of the Kuril-Kamchatka island arch  

NASA Astrophysics Data System (ADS)

This report is based on the results of petrophysical studies obtained on a number of hydrothermal systems in the Kuril-Kamchatka island arc (Pauzhetsky, Mutnovsky, Koshelevsky, Essovsky, a volcano of Ebeko, Oceansky). Mineral composition and pore-space structure of primary rocks change intensively during hydrothermal process, results in alteration of petrophysical properties - porosity, density, permeability, hygroscopy, sonic velocity, elastic modulus, mechanical properties, thermal and magnetic characteristics. Petrophysical alterations gradually lead to the change of the structure of hydrothermal system, and its hydrodynamic and temperature regime. The tendency of petrophysical alteration can be different. In some cases rocks "improvement" is observed i.e. consolidation, hardening, decrease of porosity and permeability, removal of hygroscopy. In other cases rocks "deterioration" occurs, i.e. formation of secondary porosity and permeability, a decrease of density, strength, and elastic modulus, and occurrence of hygroscopic moisture. The classical example of cardinal petrophysical alteration is the transformation of hard basalts to plastic clays. The opposite example is the transformation of only slightly consolidates porous tuffs to hard and dense secondary quartzite. The character of petrophysical alteration depends on a number of factors including peculiarities of primary rocks, temperature, pressure and composition of thermal fluids, duration of fluid-rock interaction, and condition of fluid (steam, water, boiling water). The contribution of each factor to change of volcanic rocks properties is considered and analyzed in details. In particular, primary rocks controls speed, intensity and character of petrophysical alterations. Factors favorable for alteration are high porosity and permeability, micro crakes, weak cementation, glassy structure, basaltic composition. Kuril-Kamchatka region represents the volcanic island arch so host rocks in hydrothermal systems are mainly volcanic or volcaniclastic types of Neogene-Quaternary age. Volcanic rocks (lava rocks) are dense with high strength and elastic modulus and low porosity and permeability. The speed of their alteration is low. Basically volcanic rocks form impermeable horizons in the structure of hydrothermal system. But sometimes they form fracture-type reservoir. The origin of fracturing can be various. Volcanoclastic rocks are characterized by lower physical and mechanical properties, higher porosity and permeability. Due to high porosity and permeability they are greatly exposed to thermal fluids so they are altered intensively. Volcaniclastic rocks are the most common host rocks of geothermal reservoirs. Typically they form porous or fracture-porous aquifers. But in some cases they form water confining layers. The well-studied example is Pauzhetskaya hydrothermal system. The main reservoir is composed of highly porous (30-40%) and permeable medium-grained tuffs. The caprock is composed of fine-grained argillized tuffs. They are highly porous but due to small pore size porosity is un-effective for fluid and permeability is low. The temperature and pressure in a hydrothermal system cardinally influence on rocks properties. High-temperature deep fluids (?>200C) cause the perfect tendency of petrophysical alteration - consolidation, hardening, a decrease of porosity and permeability, and removal of a hygroscopic moisture. This petrophysical tendency is observed independently of composition of fluids. This is the result of the development of high-temperature secondary minerals, which fill pores and cracks, and substitute matrix and phenocrystals. The contacts between grains become strong and dense, intergranular porosity is disappeared that reinforces cementation of rock. The petrophysical alteration caused by low-temperature subsurface fluids (?<150C) are more difficult and diverse. Depending on what process prevails - rocks leaching, sedimentation of secondary minerals in pores and cracks or replacement of primary minerals

Frolova, J.; Ladygin, V.; Rychagov, S.; Shanina, V.; Blyumkina, M.

2009-04-01

384

Geochemical and isotopic evidence for seawater contamination of the hydrothermal system of Taal Volcano, Luzon, the Philippines  

NASA Astrophysics Data System (ADS)

The hydrologic structure of Taal Volcano has favored development of an extensive hydrothermal system whose prominent feature is the acidic Main Crater Lake (pH<3) lying in the center of an active vent complex, which is surrounded by a slightly alkaline caldera lake (Lake Taal). This peculiar situation makes Taal prone to frequent, and sometimes catastrophic, hydrovolcanic eruptions. Fumaroles, hot springs, and lake waters were sampled in 1991, 1992, and 1995 in order to develop a geochemical model for the hydrothermal system. The low-temperature fumarole compositions indicate strong interaction of magmatic vapors with the hydrothermal system under relatively oxidizing conditions. The thermal waters consist of highly, moderately, and weakly mineralized solutions, but none of them corresponds to either water-rock equilibrium or rock dissolution. The concentrated discharges have high Na contents (>3500mg/kg) and low SO4/Cl ratios (<0.3). The Br/Cl ratio of most samples suggests incorporation of seawater into the hydrothermal system. Water and dissolved sulfate isotopic compositions reveal that the Main Crater Lake and spring discharges are derived from a deep parent fluid (T 300 °C), which is a mixture of seawater, volcanic water, and Lake Taal water. The volcanic endmember is probably produced in the magmatic-hydrothermal environment during absorption of high-temperature gases into groundwater. Boiling and mixing of the parent water give rise to the range of chemical and isotopic characteristics observed in the thermal discharges. Incursion of seawater from the coastal region to the central part of the volcano is supported by the low water levels of the lakes and by the fact that Lake Taal was directly connected to the China sea until the sixteenth century. The depth to the seawater-meteoric water interface is calculated to be 80 and 160m for the Main Crater Lake and Lake Taal, respectively. Additional data are required to infer the hydrologic structure of Taal. Geochemical surveillance of the Main Crater Lake using the SO4/Cl, Na/K, or Mg/Cl ratio cannot be applied straightforwardly due to the presence of seawater in the hydrothermal system.

Delmelle, Pierre; Kusakabe, Minoru; Bernard, Alain; Fischer, Tobias; de Brouwer, Simon; del Mundo, Esfeca

385

Geochemistry of the volcano-hydrothermal system of El Chichón Volcano, Chiapas, Mexico  

NASA Astrophysics Data System (ADS)

The 1982 eruption of El Chichón volcano ejected more than 1km3 of anhydrite-bearing trachyandesite pyroclastic material to form a new 1-km-wide and 300-m-deep crater and uncovered the upper 500m of an active volcano-hydrothermal system. Instead of the weak boiling-point temperature fumaroles of the former lava dome, a vigorously boiling crater spring now discharges / 20kg/s of Cl-rich ( 15 000mg/kg) and sulphur-poor ( / 200mg/kg of SO4), almost neutral (pHup to 6.7) water with an isotopic composition close to that of subduction-type magmatic water (?D=-15‰, ?18O=+6.5‰). This spring, as well as numerous Cl-free boiling springs discharging a mixture of meteoric water with fumarolic condensates, feed the crater lake, which, compared with values in 1983, is now much more diluted ( 3000mg/kg of Cl vs 24 030mg/kg), less acidic (pH=2.6 vs 0.56) and contains much lower amounts of S ( / 200mg/kg of SO4, vs 3550mg/kg) with ?34S=0.5-4.2‰ (+17‰ in 1983). Agua Caliente thermal waters, on the southeast slope of the volcano, have an outflow rate of approximately 100kg/s of 71 °C Na-Ca-Cl water and are five times more concentrated than before the eruption (B. R. Molina, unpublished data). Relative N2, Ar and He gas concentrations suggest extensional tectonics for the El Chichón volcanic centre. The 3He/4He and 4He/20Ne ratios in gases from the crater fumaroles (7.3Ra, 2560) and Agua Caliente hot springs (5.3Ra, 44) indicate a strong magmatic contribution. However, relative concentrations of reactive species are typical of equilibrium in a two-phase boiling aquifer. Sulphur and C isotopic data indicate highly reducing conditions within the system, probably associated with the presence of buried vegetation resulting from the 1982 eruption. All Cl-rich waters at El Chichón have a common source. This water has the appearence of a "partially matured" magmatic fluid: condensed magmatic vapour neutralized by interaction with fresh volcaniclastic deposits and depleted in S due to anhydrite precipitation. Shallow ground waters emerging around the volcano from the thick cover of fresh pumice deposits (Red waters) are Ca-SO4-rich and have a negative oxygen isotopic shift, probably due to ongoing formation of clay at low temperatures.

Taran, Yuri; Fischer, Tobias P.; Pokrovsky, Boris; Sano, Yuji; Armienta, Maria Aurora; Macias, Jose Luis

386

Mineralogy, geochemistry, and Nd isotope composition of the Rainbow hydrothermal field, Mid-Atlantic Ridge  

NASA Astrophysics Data System (ADS)

Petrological, geochemical, and Nd isotopic analyses have been carried out on rock samples from the Rainbow vent field to assess the evolution of the hydrothermal system. The Rainbow vent field is an ultramafic-hosted hydrothermal system located on the Mid-Atlantic Ridge characterized by vigorous high-temperature venting (˜365°C) and unique chemical composition of fluids: high chlorinity, low pH and very high Fe, and rare earth element (REE) contents (Douville et al., Chemical Geology 184:37-48, 2002). Serpentinization has occurred under a low-temperature (<270°C) retrograde regime, later overprinted by a higher temperature sulfide mineralization event. Retrograde serpentinization reactions alone cannot reproduce the reported heat and specific chemical features of Rainbow hydrothermal fluids. The following units were identified within the deposit: (1) nonmineralized serpentinite, (2) mineralized serpentinite—stockwork, (3) steatite, (4) semimassive sulfides, and (5) massive sulfides, which include Cu-rich massive sulfides (up to 28wt% Cu) and Zn-rich massive sulfide chimneys (up to 5wt% Zn). Sulfide mineralization has produced significant changes in the sulfide-bearing rocks including enrichment in transition metals (Cu, Zn, Fe, and Co) and light REE, increase in the Co/Ni ratios comparable to those of mafic Cu-rich volcanic-hosted massive sulfide deposits and different 143Nd/144Nd isotope ratios. Vent fluid chemistry data are indicative of acidic, reducing, and high temperature conditions at the subseafloor reaction zone where fluids undergo phase separation most likely under subcritical conditions (boiling). An explanation for the high chlorinity is not straightforward unless mixing with high salinity brine or direct contribution from a magmatic Cl-rich aqueous fluid is considered. This study adds new data, which, combined with the current knowledge of the Rainbow vent field, brings compelling evidence for the presence, at depth, of a magmatic body, most likely gabbroic, which provides heat and metals to the system. Co/Ni ratios proved to be good tools used to discriminate between rock units, degree of sulfide mineralization, and positioning within the hydrothermal system. Deeper units have Co/Ni <1 and subsurface and surface units have Co/Ni >1.

Marques, A. F. A.; Barriga, F.; Chavagnac, V.; Fouquet, Y.

2006-05-01

387

Hydrothermal pretreatment of coal. [Heat and hydrothermal treatment at 350 degrees C  

SciTech Connect

We recently examined Argonne supplied Wyodak coal under both thermal (no added water, under N{sub 2}) and hydrothermal (liquid water present, under N{sub 2}) conditions at 350{degrees}C for periods of 30 min. and 5 hr. We found that the coal produces a tar that is deposited on the reactor insert walls solely at hydrothermal conditions. The shift from 30 min. to 5 hr. yields a tar that is more volatile and has a slightly increased molecular weight. The coals recovered from thermal and hydrothermal treatments are different by pyrolysis-field ionization mass spectrometry (py-FIMS). Specifically, the hydrothermal condition yields py-FIMS volatiles with a higher weight average molecular weight and greater volatility. They are thus less polar, a conclusion consistent with other py-FIMS data showing that the volatiles from the hydrothermally treated coal are lower in phenolics. Our results show that the phenols and catechols in the coal behave very differently. Our data are consistent with a scheme in which the catechol units in the coal engage in condensation at thermal conditions, probably through a catalyzed process related to acidic sites on the mineral matter. The phenols in contrast are unreactive. At hydrothermal conditions, on the other hand, both are released hydrolytically. Thus it appears that the presence of added water decreases or eliminates thermally promoted crosslinking tied to catechol condensation. Unexpectedly, we see acetone and other simple ketones in the Wyodak pyrolysate from both the thermal and hydrothermal treatment. Acetone in some cases is the single most prominent product. These ketones are not seen, however, in the unconfined py-FIMS heating. The difference between confined and unconfined heating suggest that water evolved from the coal itself in confined heating acts in some hydrolytic fashion to liberate the ketones.

Ross, D.S.

1990-05-30

388

Evidence for Hydrothermal Vents as "Biogeobatteries" (Invited)  

NASA Astrophysics Data System (ADS)

Hydrothermal vents are unique systems that play an important role in oceanic biogeochemical cycles. As chemically reduced hydrothermal fluid mixes with cold oxic seawater, minerals precipitate out of solution resulting in chimney structures composed largely of metal sulfides and anhydrite. Pyrite, which is a natural semi-conductor, is the primary sulfide mineral, but other minerals within chimneys are also conductive (e.g. chalcopyrite, wurtzite, and some iron oxides). Sulfide chimneys are also known to host an extensive endolithic microbial community. Accordingly, submarine hydrothermal systems appear to be examples of biogeobatteries, wherein conductive mineral assemblages span naturally occuring redox gradients and enable anaerobic microbes to access oxygen as an oxidant via extracellular electron transfer (or EET). To test this hypothesis, we ran a series of electrochemical laboratory experiments in which pyrite was used as an anode (in a vessel flushed with hydrothermal-like fluid). When placed in continuity with a carbon fiber cathode, pyrite was found to accept and conduct electrons from both abiotic and biological processes (microbial EET). Specifically, electrical current increased 4-fold (5 nA/m2 to 20 nA/m2) in response to inoculation with a slurry prepared from a hydrothermal vent sample. Inspection of the pyrite anode with SEM revealed ubiquitous coverage by microbes. DNA was extracted from the anodes and the inoculum, and was subjected to pyrosequencing to examine prokaryotic diversity. These data suggest that key microbial phylotypes were enriched upon the pyrite, implicating them in EET. In addition, we deployed an in situ experiment based on microbial fuel cell architecture with a graphite anode inserted into a vent wall coupled to a carbon fiber cathode outside the vent. We observed current production over the course of one year, implying microbial EET in situ. Via pyrosequencing, we observed that the microbial community on the anode was significantly enriched in gammaproteobacteria (with respect to the community on an inert substrate deployed in the same vent, which was dominated by epsilonproteobacteria). The observation of electrical current and the enrichment of distinct microbial communities in both laboratory and in situ experiments provide evidence that hydrothermal vents enable microbes capable of EET to access molecular oxygen in the surrounding seawater as an oxidant. This geochemical and microbial phenomenon may influence the chemistry and mineralogy of vent systems, resulting in localized variations in pH that can influence metal mobilization on a global scale.

Nielsen, M. E.; Girguis, P. R.

2010-12-01

389

Utilizing subcooled, superfluid He-II in the design of a 12-tesla tandem-mirror experiment  

SciTech Connect

A design study of 12-T yin-yang coils for a conceptual Tandem Mirror Next Step (TMNS) facility has been recently performed by Lawrence Livermore National Laboratory in conjunction with the Convair Division of General Dynamics. The large magnets have major and minor radii of 3.7 and 1.5 m, 0.70 x 3.75 m/sup 2/ cross section, 46.3 MA turns, and an overall current density of 1765 A/cm/sup 2/, obtained by the use of Nb/sub 3/Sn and Nb-Ti superconductors. Each coil is composed of several subcoils separated by internal strengthening substructure to react the enormous electromagnetic forces. The size of the yin-yang coils, and hence the current density, was reduced by utilizing subcooled, superfluid He-II at 1.8 K for the coolant. This paper reviews the design study, with emphasis on He-II heat transport and conductor stability. Methods are also presented which allow the extension of Gorter-Mellink-channel calculations to encompass multiple, interconnecting coolant channels.

Hoard, R.W.; Cornish, D.N.; Baldi, R.W.; Taylor, W.D.

1981-11-11

390

Enhanced boiling heat transfer in horizontal test bundles  

SciTech Connect

Two-phase flow boiling from bundles of horizontal tubes with smooth and enhanced surfaces has been investigated. Experiments were conducted in pure refrigerant R-113, pure R-11, and mixtures of R-11 and R-113 of approximately 25, 50, and 75% of R-113 by mass. Tests were conducted in two staggered tube bundles consisting of fifteen rows and five columns laid out in equilateral triangular arrays with pitch-to-diameter ratios of 1.17 and 1.5. The enhanced surfaces tested included a knurled surface (Wolverine`s Turbo-B) and a porous surface (Linde`s High Flux). Pool boiling tests were conducted for each surface so that reference values of the heat transfer coefficient could be obtained. Boiling heat transfer experiments in the tube bundles were conducted at pressures of 2 and 6 bar, heat flux values from 5 to 80 kW/m{sup 2}s, and qualities from 0% to 80%, Values of the heat transfer coefficients for the enhanced surfaces were significantly larger than for the smooth tubes and were comparable to the values obtained in pool boiling. It was found that the performance of the enhanced tubes could be predicted using the pool boiling results. The degradation in the smooth tube heat transfer coefficients obtained in fluid mixtures was found to depend on the difference between the molar concentration in the liquid and vapor.

Trewin, R.R.; Jensen, M.K.; Bergles, A.E.

1994-08-01

391

Iridium material for hydrothermal oxidation environments  

SciTech Connect

A process is described for hydrothermal oxidation of combustible materials in which, during at least a part of the oxidation, corrosive material is present and makes contact with at least a portion of the apparatus over a contact area on the apparatus. At least a portion of the contact surface area comprises iridium, iridium oxide, an iridium alloy, or a base metal overlaid with an iridium coating. Iridium has been found to be highly resistant to environments encountered in the process of hydrothermal oxidation. Such environments typically contain greater than 50 mole percent water, together with oxygen, carbon dioxide, and a wide range of acids, bases and salts. Pressures are typically about 27.5 to about 1000 bar while temperatures range as high as 800 C. 1 fig.

Hong, G.T.; Zilberstein, V.A.

1996-06-18

392

Iridium material for hydrothermal oxidation environments  

DOEpatents

A process for hydrothermal oxidation of combustible materials in which, during at least a part of the oxidation, corrosive material is present and makes contact with at least a portion of the apparatus over a contact area on the apparatus. At least a portion of the contact surface area comprises iridium, iridium oxide, an iridium alloy, or a base metal overlaid with an iridium coating. Iridium has been found to be highly resistant to environments encountered in the process of hydrothermal oxidation. Such environments typically contain greater than 50 mole percent water, together with oxygen, carbon dioxide, and a wide range of acids, bases and salts. Pressures are typically about 27.5 to about 1000 bar while temperatures range as high as 800.degree. C.

Hong, Glenn T. (Tewksbury, MA); Zilberstein, Vladimir A. (Brookline, MA)

1996-01-01

393

Colorado's hydrothermal resource base: an assessment  

SciTech Connect

As part of its effort to more accurately describe the nations geothrmal resource potential, the US Department of Energy/Division of Geothermal Energy contracted with the Colorado Geological survey to appraise the hydrothermal (hot water) geothermal resources of Colorado. Part of this effort required that the amount of energy that could possibly be contained in the various hydrothermal systems in Colorado be estimated. The findings of that assessment are presented. To make these estimates the geothermometer reservoir temperatures estimated by Barrett and Pearl (1978) were used. In addition, the possible reservoir size and extent were estimated and used. This assessment shows that the total energy content of the thermal systems in Colorado could range from 4.872 x 10{sup 15} BTU's to 13.2386 x 10{sup 15} BTU's.

Pearl, R.H.

1981-01-01

394

Hydrothermal gold mineralization in the Witwatersrand basin  

NASA Astrophysics Data System (ADS)

The origin of the gold mineralization in the Witwaterstrand basin of South Africa-the largest known gold province-has been controversial for decades, with arguments favouring detrital1,2 (placer), modified placer3,4 and hydrothermal5,6 origins. Here we present the results of an extensive geological study of Witwatersrand rocks which show that the gold (and associated uranium) mineralization is hydrothermal in origin and postdates a regional high-temperature alteration event. Alteration processes identified on a small scale can be mapped out regionally as roughly strata-bound zones of acid metasomatism extending far into the basin: the fluid flow responsible for this alteration was concentrated in small-scale structures localized along lithological boundaries. We find that the gold precipitated as a consequence of interactions of the fluid with shale-derived hydrocarbons present within the basin.

Barnicoat, A. C.; Henderson, I. H. C.; Knipe, R. J.; Yardley, B. W. D.; Napier, R. W.; Fox, N. P. C.; Kenyon, A. K.; Muntingh, D. J.; Strydom, D.; Winkler, K. S.; Lawrence, S. R.; Cornford, C.

1997-04-01

395

Thermal Effects on Hydrothermal Biomass Liquefaction  

Microsoft Academic Search

Batch pressure vessels commonly used for hydrothermal liquefaction have typical heating times in the range of 30 to 60 min.\\u000a Thermodynamically, the complex set of reactions are path dependent, so that the heating rate can possibly affect yields and\\u000a the composition of the resultant liquid products. It is postulated that the mode of heat transfer becomes an uncontrolled\\u000a variable in kinetic

Bo Zhang; Marc von Keitz; Kenneth Valentas

2008-01-01

396

Thermal Effects on Hydrothermal Biomass Liquefaction  

Microsoft Academic Search

Batch pressure vessels commonly used for hydrothermal liquefaction have typical heating times in the range of 30 to 60 min.\\u000a Thermodynamically, the complex set of reactions are path dependent, so that the heating rate can possibly affect yields and\\u000a the composition of the resultant liquid products. It is postulated that the mode of heat transfer becomes an uncontrolled\\u000a variable in

Bo Zhang; Marc von Keitz; Kenneth Valentas

2008-01-01

397

The hydrothermal synthesis of low albite  

Microsoft Academic Search

Glasses on the join NaAlSi3O8-Na2Si2O5 were devitrified hydrothermally at pressures of 1 to 10 kb and at temperatures in the range 200 to 700° C to define more adequately the physical and chemical environments which favor crystallization of the fully ordered polymorph of albite. The presence of Na2Si2O5 allows the synthesis of low albite with an obliquity of 1.140° (Cu

Robert F. Martin

1969-01-01

398

Microbiology of deep-sea hydrothermal vents  

Microsoft Academic Search

Before the discovery of deep-sea hydrothermal vents in 1977, the deep sea was perceived as a cold, dark, high-pressure and nutrient-poor environment inhabited by psychrophilic, oligotrophic and barotolerant-to-barophilic microbial communities. By contrast, deep-sea-vent areas are warm-to-hot and inhabited by animal communities whose density may reach 50 kg m?2. Invertebrates living in these warm biotopes are in endosymbiotic relationships with autotrophic

Daniel Prieur

1997-01-01

399

Numerical modeling of oceanic crustal hydrothermal systems  

NASA Astrophysics Data System (ADS)

The oceanic crust is a complex rock-mineral formation which extends up to several kilometers below the sea floor and covers laterally about two thirds of the planet. Hydrothermal circulation within the crust is driven by magmatic sources and carried by the fluid residing in pores and cracks. Hydrothermal advection transfers about one quarter of the Earth's total heat power from the interior. Marine sediments are believed to be the largest repositories of solid ice-like methane clathrate hydrates. The compliance technique is an important tool for assessment of this resource. It makes use of the oceanic surface gravity waves to induce pressure variations on the sea floor and measure the corresponding vertical deformation. This thesis deals with the convective heat and mass transfer within the oceanic crust, as a fractured porous medium, and the elastic, quasi-static response of hydrated marine sediments to gravity wave loading. Both generic and site-specific applications are considered. Most applications are tackled numerically in three spatial dimensions. The major results are as follows. Fractures can trigger and maintain hydrothermal circulation. The permeability-thickness product in the direction of flow is an adequate parameter to represent the fracture if convection is not vigorous. A new temperature homogenization mechanism for the off-axial convection is proposed which is due to quasi-lateral circulation within a permeable zone between sediment cover and basalt. It explains both the observed correlation between surface heat flux and sediment thickness, as well as regular heat flux variations when no buried topography is present. A hydrothermal model for the CoAxial Segment of the Juan de Fuca Ridge predicts ridge-parallel convection with the low-temperature vents spaced 1 km apart. The compliance approach is feasible for a non-layered medium. The average compliance response depends on the bulk hydrate content, but not on a particular connectivity pattern. However, the lateral variation in compliance correlates with the size of a typical lateral inhomogeneity.

Latychev, Konstantin

400

Borehole plugging by hydrothermal transport. Final report  

Microsoft Academic Search

Calcium silicate--and aluminosilicate--compositions based on mixtures of fine grained quartz with various cements or calcium silicate compounds have been investigated under hydrothermal conditions in the temperature range 110-250°C and pressure range 1,000-10,000 psi, pressures which are always in excess of that required to maintain liquid HO, and approximate the confining pressures which might be anticipated in deep boreholes. All silicate

D. M. Roy; W. B. White

1976-01-01

401

Isotopic fronts in hydrothermally mineralized carbonate rocks  

Microsoft Academic Search

Advective-dispersive fluid flow through permeable and porous rock causes systematic alteration of the infiltrated rock. O and Sr isotopes can be used as tracers to monitor exchange processes between mineralizing hydrothermal solutions and carbonate host rocks. Fluid infiltration into rock of initially uniform isotopic composition leads to characteristic changes in d18O and ?87Sr in the rock, that depend on infiltration

H. E. Frimmel

1992-01-01

402

Hydrothermal carbonization of anaerobically digested maize silage  

Microsoft Academic Search

Hydrochars were prepared by hydrothermal carbonization (HTC) of maize silage previously treated at 55°C in a two-stage solid-state reactor system. The HTC was carried out in a 1-L stirred pressure reactor with pH regulation by citric acid. The treated silage carbonized at relatively mild conditions (190°C, 2h), and the hydrochars showed mainly amorphous macro-size features with a carbon content of

Jan Mumme; Lion Eckervogt; Judith Pielert; Mamadou Diakité; Fabian Rupp; Jürgen Kern

2011-01-01

403

ANALYSIS OF FLUID IN HYDROTHERMAL CARBON NANOTUBES  

Microsoft Academic Search

Understanding of the interaction of water-based liquids with carbon at the nanoscale is of great importance for exploring the potential of carbon nanotubes in nanofluidic applications. Using hydrothermal synthesis, hydrophilic multiwall carbon nanotubes filled with an aqueous fluid have been produced. These closed tubes were synthesized from an equilibrated C-H-O fluid, in the presence of Ni catalyst, at 730- 800°C

Y. Gogotsi; N. Naguib; H. Ye; A. G. Yazicioglu; C. M. Megaridis

2002-01-01

404

Numerical simulation of magmatic hydrothermal systems  

NASA Astrophysics Data System (ADS)

The dynamic behavior of magmatic hydrothermal systems entails coupled and nonlinear multiphase flow, heat and solute transport, and deformation in highly heterogeneous media. Thus, quantitative analysis of these systems depends mainly on numerical solution of coupled partial differential equations and complementary equations of state (EOS). The past 2 decades have seen steady growth of computational power and the development of numerical models that have eliminated or minimized the need for various simplifying assumptions. Considerable heuristic insight has been gained from process-oriented numerical modeling. Recent modeling efforts employing relatively complete EOS and accurate transport calculations have revealed dynamic behavior that was damped by linearized, less accurate models, including fluid property control of hydrothermal plume temperatures and three-dimensional geometries. Other recent modeling results have further elucidated the controlling role of permeability structure and revealed the potential for significant hydrothermally driven deformation. Key areas for future research include incorporation of accurate EOS for the complete H2O-NaCl-CO2 system, more realistic treatment of material heterogeneity in space and time, realistic description of large-scale relative permeability behavior, and intercode benchmarking comparisons.

Ingebritsen, S. E.; Geiger, S.; Hurwitz, S.; Driesner, T.

2010-03-01

405

Hydrothermal reaction of fly ash. Final report  

SciTech Connect

The reactions which occur when fly ash is treated under hydrothermal conditions were investigated. This was done for the following primary reasons. The first of these is to determine the nature of the phases that form to assess the stabilities of these phases in the ambient environment and, finally, to assess whether these phases are capable of sequestering hazardous species. The second reason for undertaking this study was whether, depending on the composition of the ash and the presence of selected additives, it would be possible under hydrothermal conditions to form compounds which have cementitious properties. Formation of four classes of compounds, which bracket likely fly ash compositional ranges, were selected for study. The classes are calcium silicate hydrates, calcium selenates, and calcium aluminosulfates, and silicate-based glasses. Specific compounds synthesized were determined and their stability regions assessed. As part of stability assessment, the extent to which selected hazardous species are sequestered was determined. Finally, the cementing properties of these compounds were established. The results obtained in this program have demonstrated that mild hydrothermal conditions can be employed to improve the reactivity of fly ash. Such improvements in reactivity can result in the formation of monolithic forms which may exhibit suitable mechanical properties for selected applications as building materials. If the ashes involved are considered hazardous, the mechanical properties exhibited indicated the forms could be handled in a manner which facilitates their disposal.

Brown, P.W.

1994-12-31

406

3. RW Meyer Sugar Mill: 18761889. Sorghum pan and boiling ...  

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

3. RW Meyer Sugar Mill: 1876-1889. Sorghum pan and boiling range flue. Manufactured by John Nott & Co., Honolulu, Hawaii, 1878. View: South side of sorghum pan and boiling range flue. In the sorghum pan heat was applied to the cane juice to clarify it, evaporate its water content, and concentrate the sugar crystals. Hot gasses moved through the flue underneath the entire copper bottom of the sorghum pan from the furnace (east) end to the smokestack (west) end of the boiling range. The sorghum pan sides are of redwood. The flue is built of fire-brick, masonry, and portland cement. - R. W. Meyer Sugar Mill, State Route 47, Kualapuu, Maui County, HI

407

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

408

Pool boiling on a large horizontal flat resistance heater  

NASA Astrophysics Data System (ADS)

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

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

1992-08-01

409

Study on the hydrothermal treatment of Shenhua coal  

Microsoft Academic Search

In this paper, the hydrothermal treatment of Shenhua coal was carried out under 0.1MPa (initial pressure) nitrogen and different temperature. Effects of hydrothermal treatment on the structure and the hydro-liquefaction activity of Shenhua coal were investigated by the ultimate and proximate analyses, the FTIR measurements and TG analyses of hydrothermally treated coals, and the characterizations of extraction and swelling properties,

Zhicai Wang; Hengfu Shui; Zhanning Pei; Jinsheng Gao

2008-01-01

410

Hydrothermal liquefaction of biomass: A review of subcritical water technologies  

Microsoft Academic Search

This article reviews the hydrothermal liquefaction of biomass with the aim of describing the current status of the technology. Hydrothermal liquefaction is a medium-temperature, high-pressure thermochemical process, which produces a liquid product, often called bio-oil or bi-crude. During the hydrothermal liquefaction process, the macromolecules of the biomass are first hydrolyzed and\\/or degraded into smaller molecules. Many of the produced molecules

Saqib Sohail Toor; Lasse Rosendahl; Andreas Rudolf

2011-01-01

411

Isotopic-geochemical characteristics of the lost city hydrothermal field  

Microsoft Academic Search

The isotopic (?D, ?18O, ?13C, and 87Sr\\/86Sr) and geochemical characteristics of hydrothermal solutions from the Mid-Atlantic Ridge and the material of brucite-carbonate\\u000a chimneys at the Lost City hydrothermal field at 30°N, MAR, were examined to assay the role of the major factors controlling\\u000a the genesis of the fluid and hydrothermal chimneys of the Lost City field. The values of ?D

E. O. Dubinina; I. V. Chernyshev; N. S. Bortnikov; A. Yu. Lein; A. M. Sagalevich; Yu. V. Gol’tsman; E. D. Bairova; A. V. Mokhov

2007-01-01

412

Extraction of edingtonite from a natural zeolite under hydrothermal conditions  

NASA Astrophysics Data System (ADS)

In the present study, edingtonite has been extracted from natural zeolite clinoptilolite by simulating the natural hydrothermal conditions in the laboratory, under the influence of solutions with different concentrations of Ba+2 and Na+, varying from 0.5 to 2.8 mol/L, at 150 °C. In this work, the essential hydrothermal conditions have been provided by hydrothermal autoclaves. The natural and laboratory prepared samples were characterized by XRD, XRF and SEM methods.

Tutti, F.; Kamyab, S. M.; Barghi, M. A.; Badiei, A.

2013-01-01

413

Separation of low boiling constituents from a mixed gas  

SciTech Connect

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

Perez, E.P.

1984-06-26

414

U and Th Concentration and Isotopic Composition of Hydrothermal Fluids at the Lost City Hydrothermal Field  

NASA Astrophysics Data System (ADS)

Uranium and Th concentration and isotopic composition of hydrothermal fluids at the Lost City Hydrothermal Field (LCHF) were determined using multi-collector inductively coupled plasma mass spectrometry (MC-ICP- MS). The LCHF is an off-axis, serpentinite-hosted hydrothermal system located at 30°N near the Mid- Atlantic Ridge. Carbonate chimneys reaching 60 m in height vent alkaline (pH~10), calcium-rich fluids at 40- 91°C and the towers are home to dense microbial communities. Vent fluid and seawater U and Th concentration and isotopic composition data provide critical information for constraining U-Th chimney ages. The increased sensitivity (1-2%) of MC-ICP-MS combined with an Aridus nebulization system allows the precise measurement of small quantities of sample (~150 ml) with low concentrations (<<1ng/g) of U and Th. In this study, we have developed MC-ICP-MS techniques to measure the U and Th concentration and isotopic composition (234U, 238U, 230Th, and 232Th) of eight hydrothermal fluid samples. Endmember fluids with ~1mmol/kg Mg have ~0.02 ng/g U, confirming that end-member fluids contain near-zero values of both Mg and U. Thorium concentrations of fluids are close to deep seawater values. U and Th isotopic compositions are reported at the permil level. These data may provide new insights into the role of serpentinite-hosted hydrothermal systems in the budgets of U and Th in the ocean. Techniques presented in this study may be applied to other hydrothermal and seep environments.

Ludwig, K. A.; Shen, C.; Cheng, H.; Edwards, R.; Kelley, D. S.; Butterfield, D. A.

2006-12-01

415

23. RW Meyer Sugar Mill: 18761889. Boiling House Interior, 1878. ...  

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

23. RW Meyer Sugar Mill: 1876-1889. Boiling House Interior, 1878. View: North Wall of boiling house. In the original structure the three windows on the right admitted light and air from the outside. A shed occupied the left side of the wall outside (hence no windows). in 1881 the construction of the cooling shed closed in the right three windows. The sorghum is in the foreground. The centrifugals are in the left rear. - R. W. Meyer Sugar Mill, State Route 47, Kualapuu, Maui County, HI

416

Boiling limits in heat pipes with annular gap wick structures  

NASA Astrophysics Data System (ADS)

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

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

1990-06-01

417

Validation of IVA Computer Code for Flow Boiling Stability Analysis  

SciTech Connect

IVA is a computer code for modeling of transient multiphase, multi-component, non-equilibrium flows in arbitrary geometry including flow boiling in 3D nuclear reactors. This work presents part of the verification procedure of the code. We analyze the stability of flow boiling in natural circulation loop. Experimental results collected on the AREVA/FANP KATHY loop regarding frequencies, mass flows and decay ratio of the oscillations are used for comparison. The comparison demonstrates the capability of the code to successfully simulate such class of processes. (author)

Ivanov Kolev, Nikolay [Framatome-ANP, PO Box 3220, D-91058, Erlangen (Germany)

2006-07-01

418

Hydrothermal synthesis map of bismuth titanates  

SciTech Connect

The hydrothermal synthesis of four bismuth titanate materials from common bismuth and titanium precursors under hydrothermal conditions is described. Reaction of NaBiO{sub 3}{center_dot}2H{sub 2}O and anatase TiO{sub 2} in concentrated NaOH solution at 240 Degree-Sign C is shown to produce perovskite and sillenite phases Na{sub 0.5}Bi{sub 0.5}TiO{sub 3} and Bi{sub 12}TiO{sub 20}, depending on the ratio of metal precursors used. When KOH solution is used and a 1:1 ratio of the same precursors, a pyrochlore Bi{sub 1.43}Ti{sub 2}O{sub 6}(OH){sub 0.29}(H{sub 2}O){sub 0.66} is formed. The use of a mixture of HNO{sub 3} and NaOH is shown to facilitate the formation of the Aurivillius-type bismuth titanate Bi{sub 4}Ti{sub 3}O{sub 12}. The phases have been isolated separately as phase-pure powders and profile refinement of powder X-ray diffraction data allows comparisons with comparable materials reported in the literature. Analysis of Bi L{sub III}-edge X-ray absorption near edge structure (XANES) spectra of the materials shows the oxidation state of bismuth is +3 in all of the hydrothermally derived products. - Graphical abstract: Use of NaBiO{sub 3}{center_dot}2H{sub 2}O and TiO{sub 2} as reagents under hydrothermal conditions allows the phase-pure preparation of four crystalline bismuth titanate materials. Highlights: Black-Right-Pointing-Pointer NaBiO{sub 3} and TiO{sub 2} under hydrothermal conditions allow formation of bismuth titanates. Black-Right-Pointing-Pointer Synthesis of four distint phases has been mapped. Black-Right-Pointing-Pointer Bi LIII-edge XANES shows Bi is reduced to oxidation state +3 in all materials. Black-Right-Pointing-Pointer A new hydrated bismuth titanate pyrochlore has been isolated.

Sardar, Kripasindhu [Department of Chemistry, University of Warwick, Coventry, CV4 7AL (United Kingdom); Walton, Richard I., E-mail: r.i.walton@warwick.ac.uk [Department of Chemistry, University of Warwick, Coventry, CV4 7AL (United Kingdom)

2012-05-15

419

10 CFR Appendix A to Part 52 - Design Certification Rule for the U.S. Advanced Boiling Water Reactor  

Code of Federal Regulations, 2013 CFR

...Advanced Boiling Water Reactor A Appendix A to Part 52 Energy NUCLEAR REGULATORY COMMISSION...Advanced Boiling Water Reactor Designâ (ABWR FSER...Evaluation ReportâThe STP Nuclear Operating Company Amendment...Advanced Boiling Water Reactor (ABWR) Design...

2013-01-01

420

10 CFR Appendix A to Part 52 - Design Certification Rule for the U.S. Advanced Boiling Water Reactor  

Code of Federal Regulations, 2010 CFR

...for the U.S. Advanced Boiling Water Reactor A Appendix A to Part 52 ...for the U.S. Advanced Boiling Water Reactor I. Introduction Appendix...for the U.S. Advanced Boiling Water Reactor (ABWR) design, in...

2009-01-01

421

10 CFR Appendix A to Part 52 - Design Certification Rule for the U.S. Advanced Boiling Water Reactor  

Code of Federal Regulations, 2010 CFR

...for the U.S. Advanced Boiling Water Reactor A Appendix A to Part 52 ...for the U.S. Advanced Boiling Water Reactor I. Introduction Appendix...for the U.S. Advanced Boiling Water Reactor (ABWR) design, in...

2010-01-01

422

Fluid-inclusion gas composition from an active magmatic-hydrothermal system: a case study of The Geysers, California geothermal field  

SciTech Connect

Hydrothermal alteration and the active vapor-dominated geothermal system at The Geysers, CA are related to a composite hypabyssal granitic pluton emplaced beneath the field 1.1 to 1.2 million years ago. Deep drill holes provide a complete transect across the thermal system and samples of the modem-day steam. The hydrothermal system was liquid-dominated prior to formation of the modem vapor-dominated regime at 0.25 to 0.28 Ma. Maximum temperatures and salinities ranged from 440 C and 44 wt. percent NaCl equivalent in the biotite hornfels adjacent to the pluton to 305 C and 5 wt. percent NaCl equivalent at distances of 1730 m from the intrusive contact. The major, minor, and noble gas compositions of fluid inclusions in the hydrothermally altered rocks were integrated with microthermometric and mineralogic data to determine their sources and the effects of mixing and boiling. Major and minor gaseous species were released from the inclusions by crushing or thermal decrepitation; noble gases were released by crushing. The samples were analyzed by mass spectrometry. The analyses document the presence of magmatic, crustal, and meteoric components in the trapped fluids. Hydrothermal fluids present during the liquid-dominated phase of the system contained gaseous species derived mainly from crustal and magmatic sources. At The Geysers, N-2/Ar ratios greater than 525 and He-3/He-4 ratios of 6-10.7 Ra are diagnostic of a magmatic component. Crustal gas has CO2/CH4 ratios less than 4, N-2/Ar ratios between 45 and 525, and low 3He/4He ratios (0.5 Ra). Meteoric fluids have CO2/CH4 ratios greater than 4 and N2/Ar ratios between 38 (air-saturated water) and 84 (air). However, N-2/Ar ratios between 15 and 110 can result from boiling. Ratios less than 15 reflect the incorporation of N-2 into NH3-bearing clay minerals. In the central Geysers, the incursion of meteoric fluids occurred during the transition from the liquid- to vapor-dominated regime. Variations in the relative CH4, CO2, and H-2 contents of the gas analyses demonstrate that boiling took place under open-system conditions. The gas data indicate that the inclusions have remained closed to the diffusion of He and H-2 since their formation.

Moore, Joseph N.; Norman, David I.; Kennedy, B. Mack.

2001-03-01

423

Sulfur geochemistry of hydrothermal waters in Yellowstone National Park: IV Acid-sulfate waters  

USGS Publications Warehouse

Many waters sampled in Yellowstone National Park, both high-temperature (30-94 ??C) and low-temperature (0-30 ??C), are acid-sulfate type with pH values of 1-5. Sulfuric acid is the dominant component, especially as pH values decrease below 3, and it forms from the oxidation of elemental S whose origin is H2S in hot gases derived from boiling of hydrothermal waters at depth. Four determinations of pH were obtained: (1) field pH at field temperature, (2) laboratory pH at laboratory temperature, (3) pH based on acidity titration, and (4) pH based on charge imbalance (at both laboratory and field temperatures). Laboratory pH, charge imbalance pH (at laboratory temperature), and acidity pH were in close agreement for pH ??10%, a selection process was used to compare acidity, laboratory, and charge balance pH to arrive at the best estimate. Differences between laboratory and field pH can be explained based on Fe oxidation, H2S or S2O3 oxidation, CO2 degassing, and the temperature-dependence of pK2 for H2SO4. Charge imbalances are shown to be dependent on a speciation model for pH values 350 mg/L Cl) decrease as the Cl- concentration increases from boiling which appears inconsistent with the hypothesis of H2S oxidation as a source of hydrothermal SO4. This trend is consistent with the alternate hypothesis of anhydrite solubility equilibrium. Acid-sulfate water analyses are occasionally high in As, Hg, and NH3 concentrations but in contrast to acid mine waters they are low to below detection in Cu, Zn, Cd, and Pb concentrations. Even concentrations of SO4, Fe, and Al are much lower in thermal waters than acid mine waters of the same pH. This difference in water chemistry may explain why certain species of fly larvae live comfortably in Yellowstone's acid waters but have not been observed in acid rock drainage of the same pH.

Kirk, Nordstrom, D.; Blaine, McCleskey, R.; Ball, J. W.

2009-01-01

424

78 FR 46378 - La Crosse Boiling Water Reactor, Environmental Assessment and Finding of No Significant Impact...  

Federal Register 2010, 2011, 2012, 2013

...No. 50-409; NRC-2013-0168] La Crosse Boiling Water Reactor, Environmental Assessment and Finding of No Significant...Federal Regulations (10 CFR) for the La Crosse Boiling Water Reactor (LACBWR) facility and Independent Spent Fuel...

2013-07-31

425

77 FR 27097 - LaCrosse Boiling Water Reactor, Exemption From Certain Requirements, Vernon County, WI  

Federal Register 2010, 2011, 2012, 2013

...No. 50-409, License DPR-045] LaCrosse Boiling Water Reactor, Exemption From Certain Requirements, Vernon County...Regulations (10 CFR) 73.55, for the LaCrosse Boiling Water Reactor (LACBWR). This Environmental Assessment (EA)...

2012-05-08

426

76 FR 14437 - Economic Simplified Boiling Water Reactor Standard Design: GE Hitachi Nuclear Energy; Issuance of...  

Federal Register 2010, 2011, 2012, 2013

...Boiling Water Reactor Standard Design: GE Hitachi Nuclear Energy; Issuance of Final Design Approval The U.S. Nuclear...issued a final design approval (FDA) to GE Hitachi Nuclear Energy (GEH) for the economic simplified boiling...

2011-03-16

427

62 FR 25800 - Standard Design Certification for the U.S. Advanced Boiling Water Reactor Design  

Federal Register 2010, 2011, 2012, 2013

...CFR Part 52 RIN 3150--AE87 Standard Design Certification for the U.S. Advanced Boiling Water Reactor Design AGENCY: Nuclear Regulatory Commission...Advanced Boiling Water Reactor (ABWR) design. The NRC is adding a new provision...

1997-05-12

428

Electromagnetic Control of High Heat-Flux Spray Impingement Boiling Under Microgravity Conditions.  

National Technical Information Service (NTIS)

The primary goal of this project was to discover how to most effectively use electromagnetic forces to enhance spray impingement boiling in microgravity (%g). This project was closely coordinated with the non- electromagnetic spray impingement boiling hea...

C. A. Hunnell D. D. Gray J. M. Kuhlman P. J. Kreitzer S. L. Glaspell

2007-01-01

429

Physical and chemical aspects of fluid evolution in hydrothermal ore systems  

SciTech Connect

A one-dimensional, physical model describing two-phase fluid flow is used to simulate the effect of boiling on silica precipitation in geothermal and epithermal precious metal systems. The extent to which decreasing temperature and fluid vaporization are responsible for quartz precipitation is dependent on three related factors-the temperature of the fluid entering the two-phase system, the change in fluid temperature with respect to distance of fluid travel, and the extent of fluid vaporization in regions of gradual temperature decline. Boiling contributes to significant quartz precipitation in systems with high-temperature basal fluids, and in deeper portions of systems in which extensive vaporization occurs. Temperature reduction is a dominate precipitation mechanism in near-surface regions where temperature reduction is rapid, and in systems with lower temperature fluids. Quartz precipitation is most intense in systems with high mass flux/permeability ratios and low initial fluid temperatures. Geothermal systems with high mass flux/permeability and moderately low initial fluid temperatures are most effective in producing epithermal systems with abundant gold. Fluid evolution during the magnetic-hydrothermal transition and coincident molybdenite precipitation at Questa, New Mexico, has been traced using fluid inclusion microthermometry. The lack of cogenetic liquid- and vapor-rich inclusions, plus final homogenization of most saline, liquid-rich inclusions by halite dissolution indicate that high-salinity fluids were generated by a mechanism other than fluid immiscibility. Pressure flucuations are capable of producing the observed fluids and inclusion behavior. Solubility data indicate that the crystallizing aplite porphyry generated fluids with salinates as high as 57 wt.% NaCl equivalent.

Cline, J.S.

1990-01-01

430

First hydrothermal active vent discovered on the Galapagos Microplate  

NASA Astrophysics Data System (ADS)

The Galapagos Microplate (GM) lies on the western Gaplapagos Spreading Center (GSC), representing one of the classic Ridge-Ridge-Ridge (R-R-R) plate boundaries of the Nazca, Cocos, and Pacific plates. The presence of the 'black smoke' and hydrothermal vent community were firstly confirmed on the GSC. Lots of hydrothermal fields were discovered on the center and eastern GSC, while the western GSC has not been well investigated. During 17th Oct. to 9th Nov. 2009, the 3rd leg of Chinese DY115-21 cruise with R/V Dayangyihao has been launched along 2°N-5°S near equatorial East Pacific Rise (EPR). Two new hydrothermal fields were confirmed. One is named 'Precious Stone Mountain', which is the first hydrothermal field on the GM. The other is found at 101.47°W, 0.84°S EPR. The 'Precious Stone Mountain' hydrothermal field (at 101.49°W, 1.22°N) is located at an off-axial seamount on the southern GM boundary, with a depth from 1,450 to 1,700m. Hydrothermal fluids emitting from the fissures and hydrothermal fauna were captured by deep-tow video. Few mineral clasts of pyrite and chalcopyrite were separated from one sediment sample, but no sulfide chimney was found yet. Hydrothermal fauna such as alive mussels, crabs, shrimps, tubeworms, giant clams, as well as rock samples were collected by TV-Grab. The study of the seafloor classification with Simrad EM120 multi-beam echosounder has been conducted on the 'Precious Stone Mountain' hydrothermal field. The result indicates that seafloor materials around the hydrothermal field can be characterized into three types, such as the fresh lava, hydrothermal sediment, and altered rock.

Tao, C.; Li, H.; Wu, G.; Su, X.; Zhang, G.; Chinese DY115-21 Leg 3 Scientific Party

2011-12-01

431

Thermal performance of sub-atmospheric loop thermosyphon with and without enhanced boiling surface  

Microsoft Academic Search

This experimental study comparatively examines the thermal performances of two-phase loop thermosyphons (TPLP) with and without enhanced boiling surface at sub-atmospheric pressures. The boiling instabilities along with the constituent and total thermal resistances of these TPLPs are analyzed with the aid of boiling flow structures imaged at sub-atmospheric pressures. Boiling heat flux (Q) and thermal resistance of condenser (Rth,con) are

S. W. Chang; K. F. Chiang; C.-C. Huang

2012-01-01

432

GE simplified boiling water reactor stability analysis in time domain  

Microsoft Academic Search

General Electric Simplified Boiling Water Reactor (SBWR) was designed as a next generation light water reactor. It uses natural circulation to remove the heat from the reactor core. Because of this unique in-vessel circulation feature, SBWR is expected to exhibit different stability behaviors. The main emphasis of this thesis is to study the SBWR stability behavior in the time domain.

Shanlai Lu

1997-01-01

433

An electronic instrument for registration of true boiling points  

Microsoft Academic Search

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

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

1982-01-01

434

Experimental demonstration of contaminant removal from fractured rock by boiling.  

PubMed

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

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

2010-08-15

435

Water inventory management in condenser pool of boiling water reactor  

Microsoft Academic Search

An improved system for managing the water inventory in the condenser pool of a boiling water reactor has means for raising the level of the upper surface of the condenser pool water without adding water to the isolation pool. A tank filled with water is installed in a chamber of the condenser pool. The water-filled tank contains one or more

Gluntz

1996-01-01

436

The dynamics of a boiling bubble before and after detachment  

Microsoft Academic Search

An overview is given of prediction methods for motion and deformation of a bubble that is created by boiling at a wall, at times before and after detachment, with a focus on added mass forces in the vicinity of the wall. The possibility to apply added mass coefficients derived in potential flows also to flows with vorticity is examined. An

2006-01-01

437

Small circular- and rectangular-channel boiling with two refrigerants  

Microsoft Academic Search

Boiling heat transfer experiments were performed in a small circular channel (d = 2.46) and a small rectangular channel (dh = 2.40 mm) with Refrigerant 12. The channel sizes are representative of flow passages in compact evaporators. An experimental technique minimized test section end effects which can be appreciable relative to the heat transfer in these small channels. Local heat

T. N. Tran; M. W. Wambsganss; D. M. France

1996-01-01

438

Effects of annular crevices on pool boiling heat transfer  

Microsoft Academic Search

Effects of gap sizes (3.9–44.3 mm) of vertical annuli on nucleate pool boiling heat transfer of water at atmospheric pressure have been obtained experimentally. Through the tests, the conditions of tube bottom confinement (open or closed) have also been investigated and the whole results are compared with those of a single unconfined tube. According to the results, the annular condition

Myeong-Gie Kang; Young-Hwan Han

2002-01-01

439

Pool boiling heat transfer in vertical annular crevices  

Microsoft Academic Search

Effects of vertical annuli on nucleate pool boiling heat transfer of water at atmospheric pressure have been obtained experimentally. Experiments were performed for annuli with a height of 570 mm and gap sizes of 3.9 and 15 mm. Through the tests, tube bottom confinement (open or closed) has been investigated, too, and the whole results are compared with a single

Myeong-Gie Kang

2002-01-01

440

Impurity concentration behaviors in a boiling tubesheet crevice  

Microsoft Academic Search

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

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

2003-01-01

441

Bubble Dynamics and Boiling Heat Transfer in Microscale  

Microsoft Academic Search

Bubble dynamics and boiling heat transfer are received great attention in recent years, due to the wide applications in micro devices or systems. The literature is becoming rich in conventional microchannels. One should be careful to apply these results in silicon microchannels, which have much smoother wall surface and smaller channel size. The fundamental issues related to non-dimensional parameters, bubble

J. L. Xu; W. ZHANG; C. X. ZHAO; Y. H. GAN; Q. C. SU

2005-01-01

442

Boiling in Narrow Crevices in Steam Generators. Final Report.  

National Technical Information Service (NTIS)

Objective is to understand the heat transfer characteristics and mechanisms associated with boiling in the annuli of the tube-tube support plate crevices which exist in steam generators. The approach is both analytical and experimental in nature, with a m...

H. Merte V. S. Arpaci S. Selamoglu S. Tieszen

1982-01-01

443

Boiling Patterns of Iso-asymmetric Nuclear Matter  

NASA Astrophysics Data System (ADS)

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

Tõke, Jan

2013-03-01

444

A new model for nucleate boiling heat transfer  

Microsoft Academic Search

A new model to calculate heat transfer coefficients in nucleate boiling is presented. Heat transfer and fluid flow around a single bubble are investigated taking into account the influence of meniscus curvature, adhesion forces and interfacial thermal resistance on the thermodynamic equilibrium at the gas-liquid interface. The model requires only bubble site densities and departure diameters. Further quantities except the

P. Stephan; J. Hammer

1994-01-01

445

Facilitating Conceptual Change in Students' Understanding of Boiling Concept  

ERIC Educational Resources Information Center

The objective of this study was to construct a teaching strategy for facilitating students' conceptual understanding of the boiling concept. The study is based on 52 freshman students in the primary science education department. Students' ideas were elicited by a test consisting of nine questions. Conceptual change strategy was designed based on…

Costu, Bayram; Ayas, Alipasa; Niaz, Mansoor; Unal, Suat; Calik, Muammer

2007-01-01