Sample records for subcooled hydrothermal boiling

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

    NASA Astrophysics Data System (ADS)

    Leet, Robert C.

    1988-05-01

    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.

  2. Numerical simulation of subcooled flow boiling

    Microsoft Academic Search

    Won Cheol Park

    2003-01-01

    Sub-cooled flow boiling in a U-bend has been examined using numerical methods. An Eulerian\\/Eulerian mathematical description was used with a multiphase computational algorithm to predict several types of flows and to examine sub-cooled flow boiling. As a prelude to the study of sub-cooled boiling and two-phase flows, single-phase laminar and turbulent flows in a U-bend were investigated. Air-water bubbly up

  3. Subcooled convective boiling in structured surface microchannels

    Microsoft Academic Search

    Shou-Shing Hsieh; Chih-Yi Lin

    2010-01-01

    Experiments are performed to investigate subcooled flow boiling, on side wall cavities with angles of 60°, 90° and 120° with bottom-wall asymmetrical heating, for a microchannel heat sink containing 75 parallel 100 µm × 200 µm channels. The heated surface is made of a Cu metal sheet with\\/without 2 µm thickness diamond film. Tests and measurements are conducted with de-ionized

  4. Calcium sulphate scale formation during subcooled flow boiling

    Microsoft Academic Search

    S. H. Najibi; H. Müller-Steinhagen; M. Jamialahmadi

    1997-01-01

    Fouling of heat transfer surfaces during subcooled flow boiling is a frequent engineering problem in process industries. Nevertheless, only few experimental and theoretical investigations on this subject can be found in the literature. In this investigation the effect of operating parameters on the deposition of calcium sulphate on heat transfer surface during subcooled flow boiling was studied. A large number

  5. On numerical modelling of low-pressure subcooled boiling flows

    Microsoft Academic Search

    J. Y. Tu; G. H. Yeoh

    2002-01-01

    Although models of subcooled flow boiling at high pressure have been studied extensively, there are few equivalent studies for numerical modelling at low pressure. Recent experimental and numerical studies on subcooled boiling flow at low pressure have indicated that empirical models developed, and verified, for high-pressure situations are not valid at low pressures. A study has been conducted to extend

  6. Jet Flows Around Microbubbles In Subcooled Boiling , Xiaofeng Pengb

    E-print Network

    Kihm, IconKenneth David

    Jet Flows Around Microbubbles In Subcooled Boiling Hao Wanga , Xiaofeng Pengb , David M nucleate boiling. The flow velocities were visualized with high-speed photography and quantified with a PIV flow at cool regions on the bubble sides resulting from upward flow of subcooled liquid. Bubble-top jet

  7. Dynamic Bubble Behaviour during Microscale Subcooled Boiling

    NASA Astrophysics Data System (ADS)

    Wang, Hao; Peng, Xiao-Feng; David, Christopher M.

    2005-11-01

    Bubble cycles, including initiation, growth and departure, are the physical basis of nucleate boiling. The present investigation, however, reveals unusual bubble motions during subcooled nucleate boiling on microwires 25 or 100 ?m in diameter. Two types of bubble motions, bubble sweeping and bubble return, are observed in the experiments. Bubble sweeping describes a bubble moving back and forth along the wire, which is motion parallel to the wire. Bubble return is the bubble moving back to the wire after it has detached or leaping above the wire. Theoretical analyses and numerical simulations are conducted to investigate the driving mechanisms for both bubble sweeping and return. Marangoni flow from warm to cool regions along the bubble interface is found to produce the shear stresses needed to drive these unusual bubble movements.

  8. Critical heat flux in subcooled flow boiling

    NASA Astrophysics Data System (ADS)

    Hall, David Douglas

    The critical heat flux (CHF) phenomenon was investigated for water flow in tubes with particular emphasis on the development of methods for predicting CHF in the subcooled flow boiling regime. The Purdue University Boiling and Two-Phase Flow Laboratory (PU-BTPFL) CHF database for water flow in a uniformly heated tube was compiled from the world literature dating back to 1949 and represents the largest CHF database ever assembled with 32,544 data points from over 100 sources. The superiority of this database was proven via a detailed examination of previous databases. The PU-BTPFL CHF database is an invaluable tool for the development of CHF correlations and mechanistic models that are superior to existing ones developed with smaller, less comprehensive CHF databases. In response to the many inaccurate and inordinately complex correlations, two nondimensional, subcooled CHF correlations were formulated, containing only five adjustable constants and whose unique functional forms were determined without using a statistical analysis but rather using the parametric trends observed in less than 10% of the subcooled CHF data. The correlation based on inlet conditions (diameter, heated length, mass velocity, pressure, inlet quality) was by far the most accurate of all known subcooled CHF correlations, having mean absolute and root-mean-square (RMS) errors of 10.3% and 14.3%, respectively. The outlet (local) conditions correlation was the most accurate correlation based on local CHF conditions (diameter, mass velocity, pressure, outlet quality) and may be used with a nonuniform axial heat flux. Both correlations proved more accurate than a recent CHF look-up table commonly employed in nuclear reactor thermal hydraulic computer codes. An interfacial lift-off, subcooled CHF model was developed from a consideration of the instability of the vapor-liquid interface and the fraction of heat required for liquid-vapor conversion as opposed to that for bulk liquid heating. Severe vapor effusion in an upstream wetting front lifts the vapor-liquid interface off the surface, triggering CHF. Since the model is entirely based on physical observations, it has the potential to accurately predict CHF for other fluids and flow geometries which are beyond the conditions for which it was validated.

  9. Subcooled flow boiling and microbubble emission boiling phenomena in a partially heated microchannel

    Microsoft Academic Search

    Guodong Wang; Ping Cheng

    2009-01-01

    A simultaneous visualization and measurement study has been carried out to investigate subcooled flow boiling and microbubble emission boiling (MEB) phenomena of deionized water in a partially heated Pyrex glass microchannel, having a hydraulic diameter of 155?m, which was integrated with a Platinum microheater. Effects of mass flux, inlet water subcooling and surface condition of the microheater on subcooled flow

  10. Influence of subcooled boiling on out-of-phase oscillations in boiling water reactors

    Microsoft Academic Search

    J. L. Muñoz-Cobo; S. Chiva; A. Escrivá

    2005-01-01

    In this paper, we develop a reduced order model with modal kinetics for the study of the dynamic behavior of boiling water reactors. This model includes the subcooled boiling in the lower part of the reactor channels. New additional equations have been obtained for the following dynamics magnitudes: the effective inception length for subcooled boiling, the average void fraction in

  11. Pool boiling studies on nanotextured surfaces under highly subcooled conditions 

    E-print Network

    Sathyamurthi, Vijaykumar

    2009-05-15

    Subcooled pool boiling on nanotextured surfaces is explored in this study. The experiments are performed in an enclosed viewing chamber. Two silicon wafers are coated with Multiwalled Carbon Nanotubes (MWCNT), 9 microns (Type-A) and 25 microns (Type...

  12. RELAP5/MOD3 subcooled boiling model assessment

    SciTech Connect

    Devkin, A.S.; Podosenov, A.S. [Russian Research Center, Moscow (Russian Federation). Nuclear Safety Inst.

    1998-05-01

    This report presents the assessment of the RELAP5/Mod3 (5m5 version) code subcooled boiling process model which is based on a variety of experiments. The accuracy of the model is confirmed for a wide range of regime parameters for the case of uniform heating along the channel. The condensation rate is rather underpredicted, which may lead to considerable errors in void fraction behavior prediction in subcooled boiling regimes for nonuniformly or unheated channels.

  13. Improvements in Predicting Void Fraction in Subcooled Boiling

    SciTech Connect

    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

    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.

  14. Critical Heat Fluxes of Subcooled Water Flow Boiling Against Outlet Subcooling in Short Vertical Tube

    Microsoft Academic Search

    Koichi Hata; Toshiyuki Sato; Takeya Tanimoto; Masahiro Shiotsu; Nobuaki Noda

    2002-01-01

    The critical heat fluxes (CHFs) of subcooled water flow boiling are systematically measured for the flow velocities (u=4.0 to 13.3 m\\/s), the outlet sub-cooling (T{sub sub,out}=3 to 129 K) and the outlet pressure (P{sub out}=800 kPa). The SUS304 test tubes of 3, 6, 9 and 12 mm in inner-diameter, d, and 33, 66, 99 and 133 mm in length, L,

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

    E-print Network

    Kim, Jungho

    Abstract Measurements of space and time resolved subcooled pool boiling of FC-72 in low, earth, and high to increase in size with bulk fluid temperature. Boiling curves at various subcoolings and gravity levelsPool boiling heat transfer on small heaters: effect of gravity and subcooling Jungho Kim a,*, John

  16. Subcooled forced convection boiling of trichlorotrifluoroethane

    NASA Technical Reports Server (NTRS)

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

    1972-01-01

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

  17. Subcooled Boiling Near a Heated Wall

    SciTech Connect

    T.A. Trabold; C.C. Maneri; P.F. Vassallo; D.M. Considine

    2000-10-27

    Experimental measurements of void fraction, bubble frequency, and velocity are obtained in subcooled R-134a flowing over a heated flat plate near an unheated wall and compared to analytical predictions. The measurements were obtained for a fixed system pressure and mass flow rate (P = 2.4 MPa and w = 106 kg/hr) at various inlet liquid temperatures. During the experiments, electrical power was applied at a constant rate to one side of the test section. The local void fraction data, acquired with a hot-film anemometer probe, showed the existence of a significant peak near the heated wall and a smaller secondary peak near the unheated wall for the larger inlet subcoolings. Local vapor velocity data, taken with the hot-film probe and a laser Doppler velocimeter, showed broad maxima near the centerline between the heated and unheated plates. Significant temperature gradients near the heated wall were observed for large inlet subcooling. Bubble size data, inferred from measurements of void fraction, bubble frequency and vapor velocity, when combined with the measured bubble chord length distributions illustrate the transition from pure three dimensional spherical to two-dimensional planar bubble flow, the latter being initiated when the bubbles fill the gap between the plates. These various two-phase flow measurements were used for development of a multidimensional, four-field calculational method; comparisons of the data to the calculations show reasonable agreement.

  18. Effects of turbulence and secondary flows on subcooled flow boiling

    NASA Astrophysics Data System (ADS)

    Bloch, Gregor; Sattelmayer, Thomas

    2014-03-01

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

  19. Subcooled nucleate boiling heat transfer from a large diameter tube

    SciTech Connect

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

    1996-12-31

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

  20. Sub-Cooled Pool Boiling Enhancement with Nanofluids

    NASA Astrophysics Data System (ADS)

    Rice, Elliott Charles

    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 which engineers employ the advantages of boiling heat transfer, as they seek to improve heat transfer performance. Recent research efforts have experimentally shown that nanofluids can have significantly better heat transfer properties than those of the pure base fluids, such as water. The objective of this study is to improve the boiling curve of de-ionized water by adding aluminum oxide nanoparticles in 0.1%, 0.2%, 0.3% and 0.4% wt concentrations in a sub-cooled pool boiling apparatus. Enhancement to the boiling curve can be quantified in two ways: (i) the similar heat fluxes of de-ionized water at smaller excess temperature, indicating similar quantity of heat removal at lower temperatures and (ii) greater heat fluxes than de-ionized water at similar excess temperatures indicating better heat transfer at similar excess temperatures. In the same fashion, the secondary objective is to increase the convective heat transfer coefficient due to boiling by adding different concentrations of aluminum oxide nanoparticles.

  1. Experimental data on the mechanism of subcooled water boiling: high-speed video shooting

    NASA Astrophysics Data System (ADS)

    Zeigarnik, Yu. A.; Khodakov, K. A.; Shekhter, Yu. L.

    2014-06-01

    The article provides statistical data on the characteristics of subcooled liquid boiling and behavior of vapor and air bubbles resulted from high-speed shooting. The authors have described a number of new phenomena going along with water boiling.

  2. Subcooled and low quality film boiling of water in vertical flow at atmospheric pressure. [PWR; BWR

    Microsoft Academic Search

    Fung

    1981-01-01

    Subcooled and low quality film boiling is usually encountered in safety analyses of nuclear reactors. In most of the previous subcooled film boiling studies, cryogenic fluids were used either in a stagnant pool or a forced convective set-up. These data cannot be applied to reactor safety analysis without excessive conservatism or skepticism. In this study, a unique method is used

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

    Microsoft Academic Search

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

    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

  4. Critical heat flux of subcooled flow boiling with water for high heat flux application

    Microsoft Academic Search

    Fujio Inasaka; Hideki Nariai

    1993-01-01

    Subcooled flow boiling in water is thought to be advantageous in removing high heat load of more than 10 MW\\/m2. Characteristics of the critical heat flux (CHF), which determines the upper limit of heat removal, are very important for the design of cooling systems. In this paper, studies on subcooled flow boiling CHF, which have been conducted by the authors,

  5. The effects of orientation angle, subcooling, heat flux, mass flux, and pressure on bubble growth and detachment in subcooled flow boiling

    E-print Network

    Sugrue, Rosemary M

    2012-01-01

    The effects of orientation angle, subcooling, heat flux, mass flux, and pressure on bubble growth and detachment in subcooled flow boiling were studied using a high-speed video camera in conjunction with a two-phase flow ...

  6. A study of the effects of heater size, subcooling, and gravity level on pool boiling heat transfer

    E-print Network

    Kim, Jungho

    was measured. Steady- state boiling data in low-g and high-g were obtained for various bulk fluid subcoolings subcooling had a negligible impact on boiling performance and a characteristically low heat flux was observedA study of the effects of heater size, subcooling, and gravity level on pool boiling heat transfer

  7. Subcooled flow boiling heat transfer from microporous surfaces in a small channel

    Microsoft Academic Search

    Yan Sun; Li Zhang; Hong Xu; Xiaocheng Zhong

    2011-01-01

    The continuously increasing requirement for high heat transfer rate in a compact space can be met by combining the small channel\\/microchannel and heat transfer enhancement methods during fluid subcooled flow boiling. In this paper, the sintered microporous coating, as an efficient means of enhancing nucleate boiling, was applied to a horizontal, rectangular small channel. Water flow boiling heat transfer characteristics

  8. Critical heat flux for subcooled flow boiling in micro-channel heat sinks

    Microsoft Academic Search

    Jaeseon Lee; Issam Mudawar

    2009-01-01

    Critical heat flux (CHF) was measured and examined with high-speed video for subcooled flow boiling in micro-channel heat sinks using HFE 7100 as working fluid. High subcooling was achieved by pre-cooling the working fluid using a secondary low-temperature refrigeration system. The high subcooling greatly reduced both bubble departure diameter and void fraction, and precluded flow pattern transitions beyond the bubbly

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

    Microsoft Academic Search

    Ronald D. Boyd

    2000-01-01

    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

  10. Two-fluid modeling for low-pressure subcooled flow boiling

    Microsoft Academic Search

    J. L. Xu; T. N. Wong; X. Y. Huang

    2006-01-01

    In the advanced electronic packaging, low-pressure subcooled flow boiling has been applied in design of compact heat exchangers for the effective electronic cooling. Through literature survey it is noted that little studies were carried out on the low-pressure and low-flow velocity subcooled flow boiling. In this paper a one-dimensional, non-equilibrium two-fluid model is proposed. The model has been validated with

  11. Hysteresis Phenomena in Subcooled Flow Boiling of Well-Wetting Fluids

    Microsoft Academic Search

    G. R Celata; M. Cumo; T. Setaro

    1992-01-01

    Detailed knowledge of the physical phenomena involved in subcooled boiling is of great interest for the design of liquid-cooled heat-generating systems with high heat fluxes. An electrically heated stainless steel tube, 2.3 m long, with a 7.57-mm inner diameter, was used to study the incipience of flow boiling in subcooled, well-wetting fluids (R-12 and R-114) over a wide range of

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

    SciTech Connect

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

    1992-03-01

    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.

  13. Effects of water contamination on sub-cooled flow boiling heat transfer

    Microsoft Academic Search

    A. B. Helali

    2011-01-01

    An experimental investigation has been carried out to study the effect of adding four different contaminants to distilled water on heat transfer under sub-cooled flow boiling conditions. Flow boiling experimental test rig has been designed and constructed to study the effect of changing the contaminant concentration and flow velocity. Lube oil, Nile river water, tap water and sea water were

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

    Microsoft Academic Search

    Jean-Marie Le Corre

    2007-01-01

    Thermal performance of heat flux controlled boiling heat exchangers are usually limited by the Critical Heat Flux (CHF) above which the heat transfer degrades quickly, possibly leading to heater overheating and destruction. In an effort to better understand the phenomena, a literature review of CHF experimental visualizations under subcooled flow boiling conditions was performed and systematically analyzed. Three major types

  15. Subcooled flow boiling heat transfer of dilute alumina, zinc oxide, and diamond nanofluids at atmospheric pressure

    Microsoft Academic Search

    Sung Joong Kim; Tom McKrell; Jacopo Buongiorno; Lin-wen Hu

    2010-01-01

    A nanofluid is a colloidal suspension of nano-scale particles in water, or other base fluids. Previous pool boiling studies have shown that nanofluids can improve the critical heat flux (CHF) by as much as 200%. In a previous paper, we reported on subcooled flow boiling CHF experiments with low concentrations of alumina, zinc oxide, and diamond nanoparticles in water (?0.1%

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

    SciTech Connect

    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

    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.

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

    NASA Astrophysics Data System (ADS)

    Situ, Rong

    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.

  18. Nucleate pool boiling in subcooled liquid under microgravity: Results of TEXUS experimental investigations

    NASA Astrophysics Data System (ADS)

    Zell, M.; Straub, J.; Weinzierl, A.

    1984-12-01

    Experiments on subcooled nucleate pool boiling in microgravity were carried out to separate gravity driven effects on heat transfer within the boiling process. A ballistic trajectory by sounding rocket flight (TEXUS 5 and 10) achieved a gravity level of a/g = 0.0001 for 360 sec. For determination of geometrical effects on heat transport two different experimental configurations (platinum wire and flat plate) were employed. Boiling curves and bubble dynamics recorded by cinematography lead to gravity independent modelling of the boiling phenomena. The results ensure the applicability and high efficiency of nucleate pool boiling for heat exchangers in space laboratories.

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

    Microsoft Academic Search

    Wen Wu; Peipei Chen; Barclay G. Jones; Ty A. Newell

    2006-01-01

    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

  20. Highly subcooled pool boiling heat transfer at various gravity levels Jungho Kim a,*, John F. Benton b

    E-print Network

    Kim, Jungho

    the bubble was observed to develop in low-g, forming a ``jet'' of heated fluid into the bulk fluid. Ó 2002Highly subcooled pool boiling heat transfer at various gravity levels Jungho Kim a,*, John F camera was used to provide subcooled pool boiling heat transfer measurements at gravity levels ranging

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

    E-print Network

    Banerjee, Debjyoti

    Experimental investigation of micro-scale temperature transients in sub-cooled flow boiling: Flow boiling Thin film thermocouple Microfabrication Nanofabrication Fast Fourier transform a b s t r fluxes are associated with flow boiling than pool boiling under similar conditions of wall superheat

  2. Subcooled and saturated water flow boiling pressure drop in small diameter helical coils at low pressure

    SciTech Connect

    Cioncolini, Andrea; Santini, Lorenzo; Ricotti, Marco E. [Department of Nuclear Engineering, Politecnico di Milano, via Ponzio 34/3, 20133 Milano (Italy)

    2008-05-15

    Experimental pressure drop results on boiling water flow through three helical coils of tube inner diameter of 4.03 mm and 4.98 mm and coil diameter to tube diameter ratio of 26.1, 64.1 and 93.3 are presented. Both subcooled and saturated flow boiling are investigated, covering operating pressures from 120 to 660 kPa, mass fluxes from 290 to 690 kg m{sup -2} s{sup -1} and heat fluxes from 50 to 440 kW m{sup -2}. Existing correlations for subcooled flow pressure drop are found not capable to fit the present subcooled database, while the measurements in saturated flow conditions are successfully reproduced by existing correlations for both straight and coiled pipe two-phase flow. The experimental database is included in tabular form. (author)

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

    Microsoft Academic Search

    Vijaykumar Sathyamurthi; Debjyoti Banerjee

    2009-01-01

    The class of dynamics in pool boiling on a large-size heater is assessed under subcooled pool boiling conditions. Transient surface temperature measurements are obtained using surface micro-machined K-type thin film thermocouples (TFT) in 10°C subcooled pool boiling experiments on a 62.23mm diameter silicon wafer using PF-5060 as the test liquid. Surface temperature data is obtained at each steady state condition

  4. Wall Heat Flux Partitioning During Subcooled Flow Boiling: Part 1—Model Development

    Microsoft Academic Search

    Nilanjana Basu; Gopinath R. Warrier; Vijay K. Dhir

    2005-01-01

    In this work a mechanistic model has been developed for the wall heat flux partitioning during subcooled flow boiling. The premise of the proposed model is that the entire energy from the wall is first transferred to the superheated liquid layer adjacent to the wall. A fraction of this energy is then utilized for vapor generation, while the rest of

  5. Local nucleation propagation on heat transfer uniformity during subcooled convective boiling

    NASA Astrophysics Data System (ADS)

    Kim, Beom Seok; Yang, Gang Mo; Shin, Sangwoo; Choi, Geehong; Cho, Hyung Hee

    2015-01-01

    Convective boiling heat transfer is an efficient cooling mechanism to dissipate amount of thermal energy by accompanying the phase transition of the working fluids. Particularly, the amount of heat dissipation capacity can be readily extensible by increasing the degree of subcooling due to initial demands requiring for coolant saturation. Under severely subcooled condition of 60°, we investigate boiling heat transfer phenomena regarding spatial heat transfer uniformity and stability on a planar surface. Severe subcooling can induce locally concentrated thermal loads due to poor spatial uniformity of the heat transfer. For reliable cooling, a high degree of spatial uniformity of the heat transfer should be guaranteed with minimized spatial deviation of heat transfer characteristics. Under pre-requisite safeguards below CHF, we experimentally elucidate the principal factors affecting the spatial uniformity of the heat transfer for a flow/thermal boundary layer considering heat transfer domains from a single-phase regime to a fully-developed boiling regime. Based on the local heat transfer evaluation, we demonstrate that full nucleation boiling over the entire heat transfer surface under subcooling conditions is favorable in terms of the uniformity of heat dissipation through the phase-change of the working fluid.

  6. Forced convection and subcooled flow boiling heat transfer in asymmetrically heated ducts of T-section

    Microsoft Academic Search

    Hosny Z. Abou-Ziyan

    2004-01-01

    This paper presents the results of an experimental investigation of heat transfer from the heated bottom side of tee cross-section ducts to an internally flowing fluid. The idea of this work is derived from the cooling of critical areas in the cylinder heads of internal combustion engines. Fully developed single phase forced convection and subcooled flow boiling heat transfer data

  7. Mathematical modelling of mixed salt precipitation during convective heat transfer and sub-cooled flow boiling

    Microsoft Academic Search

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

    2005-01-01

    The main purpose of this investigation was to study the mechanisms of mixed salt crystallisation fouling on heat transfer surfaces during convective heat transfer and sub-cooled flow boiling conditions. In the present investigation, the effects of various operating parameters such as solution composition and hydrodynamics of the system, on crystallisation fouling of mixtures of calcium sulphate and calcium carbonate have

  8. Crystallisation Fouling Of Mixed Salts During Convective Heat Transfer And Sub-Cooled Flow Boiling Conditions

    Microsoft Academic Search

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

    2004-01-01

    The mechanisms of mixed salt crystallisation fouling on heat transfer surfaces have been investigated for convective and sub-cooled flow boiling heat transfer. Effects of various operating parameters such as solution composition and hydrodynamics of the system, on crystallisation fouling of mixtures of calcium sulphate and calcium carbonate have been studied experimentally. The results of the experiments were used to develop

  9. Assessment of dimensionless CHF correlations for subcooled flow boiling in microgravity and Earth gravity

    Microsoft Academic Search

    Hui Zhang; Issam Mudawar; Mohammad M. Hasan

    2007-01-01

    A comprehensive review and analysis of prior subcooled flow boiling CHF correlations was conducted to identify those correlations that provide the most accurate predictions for dielectric working fluids and small rectangular flow passages found in electronics cooling applications in both microgravity and Earth gravity. Since most prior correlations were derived from water databases, only those with dimensionless form were deemed

  10. Simulation of subcooled boiling at low pressure conditions with RELAP5-3D computer program

    E-print Network

    Reza, S.M. Mohsin

    2002-01-01

    Simulation of subcooled boiling was carried out using RELAP5 thermal hydraulic computer programs. Both one-dimensional and three-dimensional analyses were carried out with one-dimensional RELAP5/MOD3.2 and three-dimensional RELAP5-3D code...

  11. Simulation of subcooled boiling at low pressure conditions with RELAP5-3D computer program 

    E-print Network

    Reza, S.M. Mohsin

    2002-01-01

    Simulation of subcooled boiling was carried out using RELAP5 thermal hydraulic computer programs. Both one-dimensional and three-dimensional analyses were carried out with one-dimensional RELAP5/MOD3.2 and three-dimensional RELAP5-3D code...

  12. Static flow instability in subcooled flow boiling in parallel channels

    SciTech Connect

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

    1995-04-01

    A series of tests for static flow instability or flow excursion (FE) at conditions applicable to the proposed Advanced Neutron Source reactor was completed in parallel rectangular channels configuration with light water flowing vertically upward at very high velocities. True critical heat flux experiments under similar conditions were also conducted. The FE data reported in this study considerably extend the velocity range of data presently available worldwide. Out of the three correlations compared, the Saha and Zuber correlation had the best fit with the data. However, a modification was necessary to take into account the demonstrated dependence of the Stanton (St) and Nusselt (Nu) numbers on subcooling levels, especially in the low subcooling regime.

  13. Pool boiling studies on nanotextured surfaces under highly subcooled conditions

    E-print Network

    Sathyamurthi, Vijaykumar

    2009-05-15

    -B) in height. A third bare silicon wafer is used for control experiments. The test fluid is PF-5060, a fluoroinert with a boiling point of 56°C (Manufacturer: 3M Co.). The apparatus is of the constant heat flux type. Pool boiling experiments in nucleate...

  14. Experimental investigation of subcooled flow boiling using synchronized high speed video, infrared thermography, and particle image velocimetry

    E-print Network

    Phillips, Bren Andrew

    2014-01-01

    Subcooled flow boiling of water was experimentally investigated using high-speed video (HSV), infrared (IR) thermography, and particle image velocimetry (PIV) to generate a unique database of synchronized data. HSV allowed ...

  15. Multi-Scale Experiments in Turbulent Subcooled Boiling Flow Through a Square Channel with a Single Heated Wall 

    E-print Network

    Estrada Perez, Carlos Eduardo

    2014-12-12

    In this work, visualization experimental techniques that provide whole-field and multi-scale measurements of the liquid turbulence parameters, liquid and heater wall temperatures, and gas phase local parameters, were used to study subcooled boiling...

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

    Microsoft Academic Search

    Said Talebi; Farshad Abbasi; Hadi Davilu

    2009-01-01

    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

  17. Modeling of low-pressure subcooled boiling flow of water via the homogeneous MUSIG approach

    Microsoft Academic Search

    Erfeng Chen; Yanzhong Li; Xianghua Cheng; Lei Wang

    2009-01-01

    Applying a three-dimensional two-fluid model coupled with homogeneous multiple size group (MUSIG) approach, numerical simulations of upward subcooled boiling flow of water at low pressure were performed on the computational fluid dynamics (CFD) code CFX-10 with user defined FORTRAN program. A modified bubble departure diameter correlation based on the Unal's semi-mechanistic model and the empirical correlation of Tolubinski and Kostanchuk

  18. Numerical investigation of static flow instability in a low-pressure subcooled boiling channel

    Microsoft Academic Search

    Y. Li; G. H. Yeoh; J. Y. Tu

    2004-01-01

    A three-dimensional two-fluid model to predict subcooled boiling flow at low pressure is presented. The model is adopted to investigate the two-phase flow and heat transfer characteristics in a heated channel. The presence of bubbles as a consequence of heating flow through a vertical rectangular channel has a significant effect on the overall pressure drop along the channel. Numerical results

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

    SciTech Connect

    Barclay G. Jones

    2008-10-01

    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.

  20. The effect of the radiative heat transfer on subcooled film boiling

    NASA Astrophysics Data System (ADS)

    Nilsuwankosit, Sunchai

    A Monte-Carlo model for the radiative heat transport was constructed to simulate the absorption of radiative heat in various parts of a multiphase medium of different configurations. The results obtained from the simulations were used to construct a profile which could be used to calculate the intensity of radiative heat in a given system. Together with the data on the absorption coefficients of liquid water and steam, the obtained profile was used to evaluate the volumetric heat source due to absorption of radiative heat in the medium. This volumetric heat source was applied in the boundary layer equations for subcooled film boiling. With the results obtained by solving the boundary layer equations for subcooled film boiling over a heating planar surface and over a heating spherical surface, the correlations describing the fraction of radiative heat absorbed in the liquid boundary layer for subcooled film boiling were constructed. The mixing phase calculation of the fuel-coolant interaction (FCI) by the computer code TEXAS was improved with the obtained correlations to account for the effect of radiative heat transfer. This verified that part of the radiative heat lost from the system was due to the small absorption coefficient of the steam and the absorption of radiative heat at the wall of the vessel. Because liquid water has a much larger absorption coefficient, more radiative heat is absorbed in water which then results in a lower temperature for steam and a higher temperature for water compared to that calculated without the effect of the radiative heat.

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

    SciTech Connect

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

    1992-03-01

    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.

  2. Thermal Analysis on MonoBlock Type Divertor Based on Subcooled Flow Boiling Critical Heat Flux Data against Inlet Subcooling in Short Vertical Tube

    Microsoft Academic Search

    Koichi Hata; Masahiro Shiotsu; Nobuaki Noda

    2006-01-01

    The subcooled flow boiling critical heat fluxes (CHFs) and the heat transfer coefficients (HTCs) data for the tube length, L, of 49, 99 and 149 mm with 9-mm inner diameter were applied to thermal analysis on the Mono-block type divertor of LHD. Incident CHFs for the divertor with the cooling tube diameter, d, of 10 mm and the carbon armor

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

    SciTech Connect

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

    1995-02-01

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

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

    SciTech Connect

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

    1988-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Zou, Ling

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

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

    Microsoft Academic Search

    M. Sunder; D. Banerjee

    2009-01-01

    Surface temperature fluctuations that occur locally underneath departing bubbles in pool boiling are shown to result in local heat transfer coefficients ranging from 1 to 10kW\\/cm2. These estimates were reported in the literature involved both numerical and experimental approaches. Significantly higher heat fluxes are associated with flow boiling than pool boiling under similar conditions of wall superheat and liquid subcooling

  7. Static-flow-instability in subcooled flow boiling in wide rectangular parallel channels

    SciTech Connect

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

    1995-12-31

    The Advanced Neutron Source (ANS) is a state-of-the-art research reactor facility that will be built at the Oak Ridge National Laboratory (ORNL) and is designed to become the world`s most advanced thermal neutron flux source for scientific experiments. Therefore, the core of the ANS reactor (ANSR) must be designed to accommodate very high power densities using very high coolant mass fluxes and subcooling levels, The nominal average and peak heat fluxes in the ANSR are approximately 6 and 12 MW/M{sup 2}, respectively, with a nominal total thermal power of 303 MW. Highly subcooled heavy-water coolant (1.7 MPa and 85{degrees}C at the core exit) flows vertically upward at a very high mass flux of almost 27 Mg/M{sup 2}-s. The cooling channels in each fuel assembly are all parallel and share common inlet and outlet plenums, effectively imposing a common pressure drop across all the channels. This core configuration is subject to flow excursion (FE) and/or flow instability that may occur once boiling is initiated in any one of the channels. The FE phenomenon constitutes a different thermal limit than a true critical heat flux (CHF) or departure from nucleate boiling (DNB). In such a system, initiation of boiling in one of the channels (i.e., the hot channel) can result in flow redistribution to the other cooler channels. This report details testing to document this phenomenon.

  8. Local pressure gradients due to incipience of boiling in subcooled flows

    SciTech Connect

    Ruggles, A.E.; McDuffee, J.L. [Univ. of Tennessee, Knoxville, TN (United States)

    1995-09-01

    Models for vapor bubble behavior and nucleation site density during subcooled boiling are integrated with boundary layer theory in order to predict the local pressure gradient and heat transfer coefficient. Models for bubble growth rate and bubble departure diameter are used to scale the movement of displaced liquid in the laminar sublayer. An added shear stress, analogous to a turbulent shear stress, is derived by considering the liquid movement normal to the heated surface. The resulting mechanistic model has plausible functional dependence on wall superheat, mass flow, and heat flux and agrees well with data available in the literature.

  9. 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

    1985-01-01

    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

  10. Physical modeling and numerical simulation of subcooled boiling in one- and three-dimensional representation of bundle geometry

    SciTech Connect

    Bottoni, M.; Lyczkowski, R.; Ahuja, S.

    1995-07-01

    Numerical simulation of subcooled boiling in one-dimensional geometry with the Homogeneous Equilibrium Model (HEM) may yield difficulties related to the very low sonic velocity associated with the HEM. These difficulties do not arise with subcritical flow. Possible solutions of the problem include introducing a relaxation of the vapor production rate. Three-dimensional simulations of subcooled boiling in bundle geometry typical of fast reactors can be performed by using two systems of conservation equations, one for the HEM and the other for a Separated Phases Model (SPM), with a smooth transition between the two models.

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

    SciTech Connect

    Ling Zou; Barclay G. Jones

    2012-11-01

    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.

  12. Thermal Analysis on Flat-Plate-Type Divertor Based on Subcooled Flow Boiling Critical Heat Flux Data Against Inlet Subcooling in Short Vertical Tube

    Microsoft Academic Search

    Koichi Hata; Masahiro SHIOTSU

    2006-01-01

    The subcooled flow boiling critical heat fluxes (CHFs) and the heat transfer coefficients (HTCs) data for the tube length, L, of 49, 99 and 149mm with 9-mm inner diameter were applied to thermal analysis on the Mono-block type divertor of LHD. Incident CHFs for the divertor with the cooling tube diameter, d ,o f 10mm and the carbon armor outer

  13. A combined photographic/thermographic study of highly subcooled flow boiling in a narrow channel

    NASA Astrophysics Data System (ADS)

    Ozer, Arif Bilal

    Minichannels (those with channel spacing near 1 mm) offer an attractive scale range for technological applications of two-phase cooling. They are small enough to create large heat fluxes, but large enough to remove significant quantities of heat, and they do not present the same degree of fouling and maintenance issues anticipated for applications of true micro-scale channels. This study applies liquid crystal thermography in concert with high-speed video imaging of a two-phase flow field to study highly subcooled bubbly flow within a millimeter-scale channel. The experiments were conducted with a high-aspect-ratio (12x23 mm) rectangular, horizontal channel with one wide wall forming a uniform-heat-generation boundary and the other designed for optical access to the flow field. By using a thermochromic liquid crystal coating on the uniform-heat-generation boundary, wall temperature variations were obtained and the heat transfer characteristics were investigated. The experiments were focused on high inlet subcooling, typically 15--50 °C. The test surface temperature increases downstream until boiling initiates when a group of nucleation sites activate at a "boiling front." It is commonly thought that cooling of the surface downstream of the front would be dominated by active nucleation sites. However, few active sites were observed downstream of those near the current position of the boiling front. This observation provides strong evidence that it is the action of bubbles sliding in the confined channel that causes the enhancement of heat transfer, not the extensive nucleation of bubbles. A quenching/diffusion analytical model was developed to describe the heat process associated with sliding bubbles. The model is based on a transient conduction hypothesis. It is able to capture the elevated heat transfer rates measured in the channel without the need to consider nucleate boiling from the surface or microlayer evaporation from the sliding bubbles. Bubble speed and size enter the model through a Fourier number associated with the bubble passage frequency. The insight gathered from this experimental investigation provides the basis for a better understanding of the physics of subcooled bubbly flow in minichannels, and this understanding should lead to new models of this regime.

  14. Prediction of the local pressure gradient during partially developed subcooled boiling in research reactors of high power density

    Microsoft Academic Search

    J. L. McDuffee; A. E. Ruggles

    1997-01-01

    A model is presented for predicting the pressure gradient in partially developed subcooled boiling of water for velocities from 15 to 30 m\\/s and inlet peaked, nonuniform axial flux profiles with channel average flux values of 6 MW\\/m². The partially and fully developed boiling regions are considered separately, however, the same general modeling technique is used for both. several correlations

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

    Microsoft Academic Search

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

    1996-01-01

    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

  16. Modeling and experiments for wall heat flux partitioning during subcooled flow boiling of water at low pressures

    Microsoft Academic Search

    Nilanjana Basu

    2003-01-01

    Void fraction during subcooled flow boiling depends on the amount of vapor generated at the wall and condensation in the bulk. Partitioning of heat flux at the wall is required to determine the fraction of the energy that is utilized for vapor production. The wall heat flux models currently available in the literature were developed for high-pressure applications and have

  17. Ultrahigh critical heat flux (CHF) for subcooled water flow boiling—II: high-CHF database and design equations

    Microsoft Academic Search

    David D. Hall; Issam Mudawar

    1999-01-01

    A high-CHF (critical heat flux) database for subcooled flow boiling of water in tubes was compiled from the world literature. The bulk of the database is for high mass velocity flow (G ?5000 kg m?2 s?1) in small diameter tubes (D ? 3 mm) . Over half of the 1596 valid data points in the database had CHF values in

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

    Microsoft Academic Search

    Fujio Inasaka; Hideki Nariai

    1996-01-01

    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

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

    NASA Astrophysics Data System (ADS)

    Le Corre, Jean-Marie

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

  20. Statistical modeling support for calibration of a multiphysics model of subcooled boiling flows

    SciTech Connect

    Bui, A. V.; Dinh, N. T.; Nourgaliev, R. R. [Idaho National Laboratory, MS-3870, PO Box 1625, Idaho Falls, ID, 83415 (United States); Williams, B. J. [Los Alamos National Laboratory, MS-F600, PO Box 1663, Los Alamos, NM, 87545 (United States)

    2013-07-01

    Nuclear reactor system analyses rely on multiple complex models which describe the physics of reactor neutronics, thermal hydraulics, structural mechanics, coolant physico-chemistry, etc. Such coupled multiphysics models require extensive calibration and validation before they can be used in practical system safety study and/or design/technology optimization. This paper presents an application of statistical modeling and Bayesian inference in calibrating an example multiphysics model of subcooled boiling flows which is widely used in reactor thermal hydraulic analysis. The presence of complex coupling of physics in such a model together with the large number of model inputs, parameters and multidimensional outputs poses significant challenge to the model calibration method. However, the method proposed in this work is shown to be able to overcome these difficulties while allowing data (observation) uncertainty and model inadequacy to be taken into consideration. (authors)

  1. Experimental measurements and CFD simulation of convective boiling during subcooled developing flow of R-11 within vertical annulus

    NASA Astrophysics Data System (ADS)

    Bouaichaoui, Y.; Kibboua, R.; Matkovi?, M.

    2015-05-01

    In this paper a convective flow boiling of refrigerant R-11 in a vertical annular channel has been investigated. Measurements were performed under various conditions of mass flux, heat flux, and inlet subcooling, which enabled to study the influence of different boundary conditions on the development of local flow parameters. Also, some measurements have been compared to the predictions by the three-dimensional two-fluid model of subcooled boiling flow carried out with the computer code ANSYS-CFX-13. Simulation results successfully predict the main experimental tendencies associated with the heat flux and Reynolds number variation. A sensitivity analysis of several modelling parameters on the radial distribution of flow quantities has highlighted the importance of correct description of the boiling boundary layer. In general a good quantitative and qualitative agreement with experimental data was obtained.

  2. Wall nucleation and the two-fluid model in subcooled boiling flow

    NASA Astrophysics Data System (ADS)

    Brooks, Caleb S.

    In an effort to improve the prediction of two-phase flows in boiling systems, the wall nucleation phenomenon is studied in the context of the interfacial area transport equation for use with the two-fluid model. A complete review of the current modeling of the wall nucleation parameters including active nucleation site density, bubble departure diameter, and bubble departure frequency is presented along with the available database from literature. Wall nucleation experiments in an annulus channel are performed to extend the database of the bubble departure diameter and departure frequency. New models and modeling strategies are proposed for the bubble departure diameter and departure frequency. With the compiled database, the preliminary models are shown to improve the predictive capability of the wall nucleation source term in the interfacial area transport equation. The one-group area-averaged interfacial area transport equation is benchmarked in subcooled boiling flow, confirming the improvement of the new wall nucleation modeling. A low pressure and elevated pressure benchmark is discussed in detail along with a sensitivity study of important models and boundary conditions. The benchmark suggests accurate scale-up ability of the bubble departure diameter and departure frequency models to high pressure conditions.

  3. A mechanistic model of critical heat flux under subcooled flow boiling conditions for application to one- and three-dimensional computer codes

    Microsoft Academic Search

    Jean-Marie Le Corre; Shi-Chune Yao; Cristina H. Amon

    2010-01-01

    Based on a review of visual observations at or near critical heat flux (CHF) under subcooled flow boiling conditions and consideration of CHF triggering mechanisms, presented in a companion paper [Le Corre, J.M., Yao, S.C., Amon, C.H., 2010. Two-phase flow regimes and mechanisms of critical heat flux under subcooled flow boiling conditions. Nucl. Eng. Des.], a model using a two-dimensional

  4. Effect of rolling motion on critical heat flux for subcooled flow boiling in vertical tube

    SciTech Connect

    Hwang, J. S.; Park, I. U.; Park, M. Y.; Park, G. C. [Dept. of Energy Systems Engineering, Seoul National Univ., 599 Gwanak-Ro, Gwanak-Gu, Seoul, 151-744 (Korea, Republic of)

    2012-07-01

    This paper presents defining characteristics of the critical heat flux (CHF) for the boiling of R-134a in vertical tube operation under rolling motion in marine reactor. It is important to predict CHF of marine reactor having the rolling motion in order to increase the safety of the reactor. Marine Reactor Moving Simulator (MARMS) tests are conducted to measure the critical heat flux using R-134a flowing upward in a uniformly heated vertical tube under rolling motion. MARMS was rotated by motor and mechanical power transmission gear. The CHF tests were performed in a 9.5 mm I.D. test section with heated length of 1 m. Mass fluxes range from 285 to 1300 kg m{sup -2}s{sup -1}, inlet subcooling from 3 to 38 deg. C and outlet pressures from 13 to 24 bar. Amplitudes of rolling range from 15 to 40 degrees and periods from 6 to 12 sec. To convert the test conditions of CHF test using R-134a in water, Katto's fluid-to-fluid modeling was used in present investigation. A CHF correlation is presented which accounts for the effects of pressure, mass flux, inlet subcooling and rolling angle over all conditions tested. Unlike existing transient CHF experiments, CHF ratio of certain mass flux and pressure are different in rolling motion. For the mass fluxes below 500 kg m{sup -2}s{sup -1} at 13, 16 (region of relative low mass flux), CHF ratio was decreased but was increased above that mass flux (region of relative high mass flux). Moreover, CHF tend to enhance in entire mass flux at 24 bar. (authors)

  5. Numerical Analysis of Nucleate Boiling on High Heat-Flux and High Subcooling Condition for Reactivity Initiation Accident

    SciTech Connect

    Heo, S.; Koshizuka, S.; Oka, Y. [Nuclear Engineering Research Laboratory, The University of Tokyo, 2-22 Shirane, Shirakata, Tokai-mura, Naka-gun, Ibaraki 319-1188 (Japan)

    2002-07-01

    This paper shows the numerical simulation study on the growth of the bubble in the transient pool boiling using MPS-MAFL method. The growth process of a bubble with the different initial radii is calculated in a high heat-flux and high subcooling condition expected in nuclear reactor core during RIA. The smaller initial radius is, the earlier the growth starts. The initial bubble radius has little effect on the growth initiation time and the bubble departure radius. (authors)

  6. ASTRID: A 3D Eulerian software for subcooled boiling modelling - comparison with experimental results in tubes and annuli

    SciTech Connect

    Briere, E.; Larrauri, D.; Olive, J. [Electricite de France, Chatou (France)

    1995-09-01

    For about four years, Electricite de France has been developing a 3-D computer code for the Eulerian simulation of two-phase flows. This code, named ASTRID, is based on the six-equation two-fluid model. Boiling water flows, such as those encountered in nuclear reactors, are among the main applications of ASTRID. In order to provide ASTRID with closure laws and boundary conditions suitable for boiling flows, a boiling model has been developed by EDF and the Institut de Mecanique des Fluides de Toulouse. In the fluid, the heat and mass transfer between a bubble and the liquid is being modelled. At the heating wall, the incipient boiling point is determined according to Hsu`s criterion and the boiling heat flux is split into three additive terms: a convective term, a quenching term and a vaporisation term. This model uses several correlations. EDF`s program in boiling two-phase flows also includes experimental studies, some of which are performed in collaboration with other laboratories. Refrigerant subcooled boiling both in tubular (DEBORA experiment, CEN Grenoble) and in annular geometry (Arizona State University Experiment) have been computed with ASTRID. The simulations show the satisfactory results already obtained on void fraction and liquid temperature. Ways of improvement of the model are drawn especially on the dynamical part.

  7. 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

    Barclay Jones

    2005-06-27

    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.

  8. Prediction of the local pressure gradient during partially developed subcooled boiling in research reactors of high power density

    SciTech Connect

    McDuffee, J.L. [JBF Associates, Knoxville, TN (United States); Ruggles, A.E. [Univ. of Tennessee, Knoxville, TN (United States)

    1997-02-01

    A model is presented for predicting the pressure gradient in partially developed subcooled boiling of water for velocities from 15 to 30 m/s and inlet peaked, nonuniform axial flux profiles with channel average flux values of 6 MW/m{sup 2}. The partially and fully developed boiling regions are considered separately, however, the same general modeling technique is used for both. several correlations for the void fraction at onset of significant void are considered, and their effect on the channel pressure drop is evaluated. The effect of nonuniform axial heat flux on the channel pressure drop is also evaluated. The model is compared with pressure drop data from the thermal-hydraulic test loop at Oak Ridge National Laboratory and is found to agree with the data within 24%.

  9. Effects of dissolved air on subcooled and saturated flow boiling of water in a small diameter tube at low pressure

    SciTech Connect

    Cioncolini, Andrea; Santini, Lorenzo; Ricotti, Marco E. [Department of Nuclear Engineering, Politecnico di Milano, via Ponzio 34/3, 20133 Milano (Italy)

    2007-10-15

    Experimental results on flow boiling of air saturated water flowing through a tube of inner diameter d{sub i} = 4.03 mm are presented. Both subcooled and saturated flow boiling are investigated, covering pressures from 177 to 519 kPa, mass fluxes from 478 to 839 kg m{sup -2} s{sup -1} and heat fluxes from 210 to 736 kW m{sup -2}. By comparing the measured results with existing prediction methods derived for degassed liquids the study concludes that the presence of dissolved air in the testing fluid can be regarded as a second order effect, and no special attention to dissolved air appears required. (author)

  10. Development of a flow boiling map for subcooled and saturated flow boiling of different fluids inside circular tubes

    Microsoft Academic Search

    S. G. Kandlikar

    1991-01-01

    The thermal behavior of a flow boiling system is represented by a flow boiling map to illustrate visually the relationships among various system parameter. An earlier flow boiling map by Collier (1981) does not include the effect of mass flux and is specific to water at low pressures. For other fluids, significant departures from the parametric trends displayed in Collier's

  11. Modeling and experiments for wall heat flux partitioning during subcooled flow boiling of water at low pressures

    NASA Astrophysics Data System (ADS)

    Basu, Nilanjana

    Void fraction during subcooled flow boiling depends on the amount of vapor generated at the wall and condensation in the bulk. Partitioning of heat flux at the wall is required to determine the fraction of the energy that is utilized for vapor production. The wall heat flux models currently available in the literature were developed for high-pressure applications and have too much empiricism built into them. As such their deficiencies become pronounced when applied to low pressures (1--5 bar), which are of interest in passively cooled advanced reactors (e.g., AP 600). In this work a mechanistic model for nucleate boiling heat flux as a function of wall superheat has been developed. The premise of the proposed model is that the entire energy from the wall is first transferred to the superheated liquid layer adjacent to the wall, either by transient conduction or forced convection. A fraction of this energy is then utilized for vapor generation. Contribution of each of the heat transfer mechanism---forced convection, transient conduction, and vapor generation, has been quantified in terms of nucleation site densities, bubble departure and lift off diameters, bubble release frequency, flow parameters like velocity, inlet subcooling, wall superheat, and fluid and surface properties, including system pressures. In this work, the vapor generation component at the wall is computed independently and not as factors of other wall heat flux components as has been done in most past studies. To support the model development, subcooled flow boiling experiments were conducted at pressures of 1.03 to 3.2 bar for a wide range of mass fluxes (124 kg/m2s to 926 kg/m2s ), heat fluxes (2.5 W/cm2 to 113 W/cm2) and for contact angles varying from 30° to 90°. These experiments were conducted using a vertical Copper plate and a Zircalloy-4 nine-rod bundle. Experimental data were also utilized for developing empirical correlations for nucleation site density, bubble departure and lift off diameters, and bubble release frequency. Model validation carried out with low-pressure data obtained from present work indicate that the wall heat flux predictions are within +/-30% of experimental values. Application of the model to other data available in literature also showed good agreement signifying that the model developed can be extended to all pressures, velocities and subcoolings.

  12. Thermal Analysis on Mono-Block Type Divertor Based on Subcooled Flow Boiling Critical Heat Flux Data against Inlet Subcooling in Short Vertical Tube

    NASA Astrophysics Data System (ADS)

    Hata, Koichi; Shiotsu, Masahiro; Noda, Nobuaki

    The subcooled flow boiling critical heat fluxes (CHFs) and the heat transfer coefficients (HTCs) data for the tube length, L, of 49, 99 and 149 mm with 9-mm inner diameter were applied to thermal analysis on the Mono-block type divertor of LHD. Incident CHFs for the divertor with the cooling tube diameter, d, of 10 mm and the carbon armor outer diameter, D, of 26 and 33 mm were numerically analyzed based on the measured CHFs and HTCs at the inlet pressure of around 800 kPa. The numerical solutions were also compared with those for the Flat-plate type divertor, which were numerically analyzed for the divertor with the cooling tube diameter d=10 mm and the divertor width, w, ranging from 16 to 30 mm. It is confirmed that the ratio of the one-side heating CHF data, qcr,inc, to the uniform heating CHF data, qcr,sub, can be represented as the simple equation based on the numerical solutions. The values of the qcr,inc for L=50, 100 and 150 mm were estimated with various D/d and w/d at higher pressures.

  13. Study on Enhancement of Sub-Cooled Flow Boiling Heat Transfer and Critical Heat Flux of Solid-Water Two-Phase Mixture

    Microsoft Academic Search

    Yasuo Koizumi; Hiroyasu Ohtake; Tomoyuki Suzuki

    2002-01-01

    The influence of particle introduction into a subcooled water flow on boiling heat transfer and critical heat flux (CHF) was examined. When the water velocity was low, the particles crowded on the bottom wall of the flow channel and flowed just like sliding on the wall. When the water velocity was high, the particles were well dispersed in the water

  14. Subcooled freon-11 flow boiling in top-heated finned coolant channels with and without a twisted tape

    NASA Astrophysics Data System (ADS)

    Smith, Alvin; Boyd, Ronald D., Sr.

    An experimental study was conducted in top-heated finned horizontal tubes to study the effect of enhancement devices on flow boiling heat transfer in coolant channels. The objectives are to examine the variations in both the mean and local (axial and circumferential) heat transfer coefficients for circular coolant channels with spiral finned walls and/or spiral fins with a twisted tape, and improve the data reduction technique of a previous investigator. The working fluid is freon-11 with an inlet temperature of 22.2 C (approximately 21 C subcooling). The coolant channel's exit pressure and mass velocity are 0.19 M Pa (absolute) and 0.21 Mg/sq. ms, respectively. Two tube configurations were examined; i.e., tubes had either 6.52 (small pitch) or 4.0 (large pitch) fins/cm of the circumferential length (26 and 16 fins, respectively). The large pitch fins were also examined with a twisted tape insert. The inside nominal diameter of the copper channels at the root of the fins was 1.0 cm. The results show that by adding enhancement devices, boiling occurs almost simultaneously at all axial locations. The case of spiral fins with large pitch resulted in larger mean (circumferentially averaged) heat transfer coefficients, h sub m, at all axial locations. Finally, when twisted tape is added to the tube with large-pitched fins, the power required for the onset of boiling is reduced at all axial and circumferential locations.

  15. Subcooled freon-11 flow boiling in top-heated finned coolant channels with and without a twisted tape

    NASA Technical Reports Server (NTRS)

    Smith, Alvin; Boyd, Ronald D., Sr.

    1989-01-01

    An experimental study was conducted in top-heated finned horizontal tubes to study the effect of enhancement devices on flow boiling heat transfer in coolant channels. The objectives are to examine the variations in both the mean and local (axial and circumferential) heat transfer coefficients for circular coolant channels with spiral finned walls and/or spiral fins with a twisted tape, and improve the data reduction technique of a previous investigator. The working fluid is freon-11 with an inlet temperature of 22.2 C (approximately 21 C subcooling). The coolant channel's exit pressure and mass velocity are 0.19 M Pa (absolute) and 0.21 Mg/sq. ms, respectively. Two tube configurations were examined; i.e., tubes had either 6.52 (small pitch) or 4.0 (large pitch) fins/cm of the circumferential length (26 and 16 fins, respectively). The large pitch fins were also examined with a twisted tape insert. The inside nominal diameter of the copper channels at the root of the fins was 1.0 cm. The results show that by adding enhancement devices, boiling occurs almost simultaneously at all axial locations. The case of spiral fins with large pitch resulted in larger mean (circumferentially averaged) heat transfer coefficients, h sub m, at all axial locations. Finally, when twisted tape is added to the tube with large-pitched fins, the power required for the onset of boiling is reduced at all axial and circumferential locations.

  16. 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

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

    2006-10-20

    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.

  17. Bubble behavior in subcooled flow boiling on surfaces of variable wettability

    E-print Network

    Tow, Emily W

    2012-01-01

    Flow boiling is important in energy conversion and thermal management due to its potential for very high heat fluxes. By improving understanding of the conditions leading to bubble departure, surfaces can be designed that ...

  18. FLOW REGIMES AND MECHANISTIC PREDICTIONS OF CRITICAL HEAT FLUX UNDER SUBCOOLED FLOW BOILING CONDITIONS

    Microsoft Academic Search

    Jean-Marie Le Corre

    Thermal performance of heat flux controlled boiling heat exchangers are usually limited by the Critical Heat Flux (CHF) above which the heat transfer degrades quickly, possibly leading to heater overheating and destruction. However, the commonly used empirical approach to CHF prediction has limited use to assess the CHF performance of new fuel design geometries and features at the development stage

  19. Critical Heat Flux for a Downwards Facing Disk in a Subcooled Pool Boiling Environment

    Microsoft Academic Search

    Marko Gocmanac

    2012-01-01

    An experimental investigation of the physical feasibility of thermal creep failure of the Calandria Vessel under a severe accident load is presented in this thesis. Thermal creep failure is postulated to occur if film boiling is instigated in the Shield Tank Water surrounding the Calandria Vessel. The objective of this experimental study is to measure the Critical Heat Flux (CHF)

  20. Heat transfer performance of engine coolants under sub-cooled boiling conditions

    SciTech Connect

    Bhowmick, S.; Branchi, C.; McAssey, E.V. Jr. [Villanova Univ., PA (United States). Dept. of Mechanical Engineering; Gollin, M. [ARCO Chemical Co., Newtown Square, PA (United States)

    1996-12-31

    An experimental program has been conducted to evaluate the heat transfer performance of two engine cooling fluid mixtures, propylene-glycol/water and ethylene-glycol/water. These tests were performed under conditions closely simulating normal engine operation. For both mixtures, results were obtained over a range of heat transfer regimes from single phase convection to saturated flow boiling. Tests showed that propylene-glycol/water and ethylene-glycol/water have very similar heat transfer performances. Performance is defined as the steady state wall temperature maintained for a given surface heat flux and test section inlet velocity. For the lowest velocity tested, the test section experienced saturated boiling over approximately one-half of its heated length. The experimental results were also compared to analytical predictions based upon the Chen correlation. At higher fluxes, the analytical methods under-predicted the test section wall temperature.

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

    SciTech Connect

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

    1995-12-31

    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.

  2. Subcooled flow boiling from the bottom of a large-diameter tube

    SciTech Connect

    Dowlati, R. [Purdue Univ., West Lafayette, IN (United States). School of Nuclear Engineering; Byrne, T.P. [Ontario Hydro Technologies, Toronto, Ontario (Canada)

    1995-12-31

    The temperature distribution in CANDU nuclear reactor fuel channels, after contact between the pressure tube and the calandria tube, is an important factor in evaluating pressure tube structural integrity. This report describes laboratory tests that were carried out to study the heat transfer on the outer surface of the calandria under boiling conditions that are similar to those expected in the reactor if the pressure tube comes in contact with the calandria tube during normal operation. The measured heat transfer is compared to predictions based on the correlation currently being used. It was observed that the moderator bulk temperature did not have a significant effect on the results once boiling was fully developed. The results are consistent with predictions from correlations in the open literature commonly used for pool boiling from small diameter cylinders with the entire surface heated. Although the current tests were performed using light water at approximately 112 kPa, only minor changes are expected for heavy water and higher pressures expected in the calandria.

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

    NASA Astrophysics Data System (ADS)

    Bloch, Gregor; Kuczaty, Julian; Sattelmayer, Thomas

    2014-02-01

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

  4. Subcooled Pool Boiling Heat Transfer Mechanisms in Microgravity: Terrier-improved Orion Sounding Rocket Experiment

    NASA Technical Reports Server (NTRS)

    Kim, Jungho; Benton, John; Kucner, Robert

    2000-01-01

    A microscale heater array was used to study boiling in earth gravity and microgravity. The heater array consisted of 96 serpentine heaters on a quartz substrate. Each heater was 0.27 square millimeters. Electronic feedback loops kept each heater's temperature at a specified value. The University of Maryland constructed an experiment for the Terrier-Improved Orion sounding rocket that was delivered to NASA Wallops and flown. About 200 s of high quality microgravity and heat transfer data were obtained. The VCR malfunctioned, and no video was acquired. Subsequently, the test package was redesigned to fly on the KC-135 to obtain both data and video. The pressure was held at atmospheric pressure and the bulk temperature was about 20 C. The wall temperature was varied from 85 to 65 C. Results show that gravity has little effect on boiling heat transfer at wall superheats below 25 C, despite vast differences in bubble behavior between gravity levels. In microgravity, a large primary bubble was surrounded by smaller bubbles, which eventually merged with the primary bubble. This bubble was formed by smaller bubbles coalescing, but had a constant size for a given superheat, indicating a balance between evaporation at the base and condensation on the cap. Most of the heaters under the bubble indicated low heat transfer, suggesting dryout at those heaters. High heat transfer occurred at the contact line surrounding the primary bubble. Marangoni convection formed a "jet" of fluid into the bulk fluid that forced the bubble onto the heater.

  5. Effect of nonuniformity of subcooled boiling flow on the onset of thermoacoustic vibrations

    SciTech Connect

    Gerliga, V.A.; Skalozubov, V.I.; Lesin, V.Y. (Odessa Polytechnic Inst. (SU))

    1991-01-01

    This paper develops the hypothesis that the factor responsible for the onset of thermoacoustic vibrations in two-phase bubble flow is positive work by bubbles condensing in the flow core. It is shown that the predicted threshold of generation of these vibrations depends strongly on the accuracy of description of the steady-state distribution of parameters of bubbles and the liquid. The results predicted on the basis of a two-zone nonequilibrium polydisperse model are compared with those given by the uniform-flow model and an equation representing the condition of applicability of one-dimensional models for predicting the steady-state parameters of nonequilibrium boiling flows is derived.

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

    E-print Network

    Banerjee, Debjyoti

    point Mutual information Chaos a b s t r a c t The class of dynamics in pool boiling on a large boiling on a horizontal disk Vijaykumar Sathyamurthi, Debjyoti Banerjee * Department of Mechanical 2009 Keywords: Boiling Thin film thermocouples Correlation dimension Critical heat flux Leidenfrost

  7. Effects of dissolved gases on subcooled flow boiling from small heated regions with and without streamwise concave curvature

    Microsoft Academic Search

    P. S. Wu; T. W. Simon

    1994-01-01

    Coolants such as fluorocarbon liquids usually contain high levels of dissolved gases. When heated, these gases are liberated from the liquid; if the liquid is boiling, these gases may influence the supply of liquid to the boiling surface. In this study, the effects of dissolved air in perfluorinated hydrocarbon, FC-72, on flow boiling heat transfer characteristics were experimentally investigated over

  8. Subcooled flow boiling heat transfer and critical heat flux in water-based nanofluids at low pressure

    E-print Network

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

    2009-01-01

    A nanofluid is a colloidal suspension of nano-scale particles in water, or other base fluids. Previous pool boiling studies have shown that nanofluids can improve the critical heat flux (CHF) by as much as 200%. In this ...

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

    Microsoft Academic Search

    Leet

    1991-01-01

    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

  10. Boils

    MedlinePLUS

    ... the boil is very bad or comes back. Antibacterial soaps and creams cannot help much once a ... following may help prevent the spread of infection: Antibacterial soaps Antiseptic (germ-killing) washes Keeping clean (such ...

  11. Geochemical processes in an active shallow submarine hydrothermal system, Bahía Concepción, México: mixing or boiling?

    Microsoft Academic Search

    Ruth Esther Villanueva-Estrada; Rosa María Prol-Ledesma; Augusto Antonio Rodríguez-Díaz; Carles Canet; Ignacio S. Torres-Alvarado; Eduardo González-Partida

    2011-01-01

    Hydrothermal activity at Bahía Concepción, on the western coast of the Gulf of California, is not linked to present volcanic activity. This site is a potential energy source; however, geothermal modelling of the system is needed in order to determine the processes that generated this activity. Two processes might lead to the formation of the secondary fluids that were sampled

  12. Geochemical processes in an active shallow submarine hydrothermal system, Bahía Concepción, México: mixing or boiling?

    Microsoft Academic Search

    Ruth Esther Villanueva-Estrada; Rosa María Prol-Ledesma; Augusto Antonio Rodríguez-Díaz; Carles Canet; Ignacio S. Torres-Alvarado; Eduardo González-Partida

    2012-01-01

    Hydrothermal activity at Bahía Concepción, on the western coast of the Gulf of California, is not linked to present volcanic activity. This site is a potential energy source; however, geothermal modelling of the system is needed in order to determine the processes that generated this activity. Two processes might lead to the formation of the secondary fluids that were sampled

  13. Influences of subcooling on burnout of horizontal cylindrical heaters

    SciTech Connect

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

    1988-05-01

    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.

  14. 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

    David A. Butterfield; Gary J. Massoth; Russell E. McDuff; John E. Lupton; Marvin D. Lilley

    1990-01-01

    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 (~60 m in diameter). Compositions range from a 300°C, gas-enriched (285 mmol\\/kg CO2), low-chlorinity (~33% of seawater) fluid to a 328°C, relatively gas-depleted (50 mmol\\/kg CO2), high-chlorinity (~116% of seawater) fluid. The entire range of

  15. 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

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

    1990-01-01

    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

  16. Boiling incipience and convective boiling of neon and nitrogen

    NASA Technical Reports Server (NTRS)

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

    1977-01-01

    Forced convection and subcooled boiling heat transfer data for liquid nitrogen and liquid neon were obtained in support of a design study for a 30 tesla cryomagnet cooled by forced convection of liquid neon. The cryogen data obtained over a range of system pressures, fluid flow rates, and applied heat fluxes were used to develop correlations for predicting boiling incipience and convective boiling heat transfer coefficients in uniformly heated flow channels. The accuracy of the correlating equations was then evaluated. A technique was also developed to calculate the position of boiling incipience in a uniformly heated flow channel. Comparisons made with the experimental data showed a prediction accuracy of + or - 15 percent.

  17. Design of Subcooled Pressurized Cryogenic Systems

    NASA Astrophysics Data System (ADS)

    McIntosh, G. E.

    2008-03-01

    High—temperature-superconducting power lines and various beamline targets require cooling with subcooled, non-boiling cryogens in the pressure range from 5 to 15 Bar. In conventional closed-loop refrigerated systems this is accomplished by using a pressurized ballast cryogen dewar to maintain the desired pressure. Although consumption is modest, cryogen flows continuously from the ballast dewar and periodic replenishment is necessary. This paper describes an innovative refrigerated system which eliminates the ballast dewar and operates continuously without cryogen or gaseous make-up after the initial fill.

  18. Flow Film Boiling Heat Transfer in Water and Freon-113

    NASA Astrophysics Data System (ADS)

    Liu, Qiusheng; Shiotsu, Masahiro; Sakurai, Akira

    Experimental apparatus and method for film boiling heat transfer measurement on a horizontal cylinder in forced flow of water and Freon-113 under pressurized and subcooled conditions were developed. The experiments of film boiling heat transfer from single horizontal cylinders with diameters ranging from 0.7 to 5mm in saturated and subcooled water and Freon-113 flowing upward perpendicular to the cylinders were carried out for the flow velocities ranging from 0 to 1m/s under system pressures ranging from 100 to 500kPa. Liquid subcoolings ranged from 0 to 50K, and the cylinder surface superheats were raised up to 800K for water and 400K for Freon-113. The film boiling heat transfer coefficients obtained were depended on surface superheats, flow velocities, liquid subcoolings, system pressures and cylinder diameters. The effects of these parameters were systematically investigated under wider ranges of experimental conditions. It was found that the heat transfer coefficients are higher for higher flow velocities, subcoolings, system pressures, and for smaller cylinder diameters. The observation results of film boiling phenomena were obtained by a high-speed video camera. A new correlation for subcooled flow film boiling heat transfer was derived by modifying authors' correlation for saturated flow film boiling heat transfer with authors' experimental data under wide subcooled conditions.

  19. Investigation of interfacial behavior during the flow boiling CHF transient

    Microsoft Academic Search

    Hui Zhang; Issam Mudawar; Mohammad M. Hasan

    2004-01-01

    Vertical upflow boiling experiments were performed in pursuit of identifying the trigger mechanism for subcooled flow boiling critical heat flux (CHF). While virtually all prior studies on flow boiling CHF concern the prediction or measurement of conditions that lead to CHF, this study is focused on events that take place during the CHF transient. High-speed video imaging and photomicrographic techniques

  20. Subseafloor Boiling Within the PACMANUS Hydrothermal System Indicated by Anhydrite-Hosted Fluid Inclusions from ODP Leg 193 Cores

    NASA Astrophysics Data System (ADS)

    Vanko, D. A.; Bach, W.; Scott, S. D.; Yeats, C.; Roberts, S.; Beaudoin, Y.

    2001-12-01

    Drilling during Leg 193 was in an area of active hydrothermal venting from dacitic rocks on Pual Ridge in the Manus Basin. All the cored rocks underlying the fresh surficial volcanic rocks are intensively hydrothermally altered. Primary fluid inclusions preserved in anhydrite veins provide unique fluid samples that provide direct evidence on the chemical and physical properties of hydrothermal fluids present beneath the seafloor. Site 1188 is located on Snowcap Knoll, an area of diffuse warm venting at a water depth of ~1645 m. Fluid inclusions have been studied from a coarse anhydrite +/- pyrite vein from ~123 m below the seafloor. The ambient hydrostatic pressure for this sample is calculated to be ~180 bars. The ambient temperature is unknown, but the T measured after 8 days of thermal rebound at a depth of 360 m in this hole was 313° C. Primary fluid inclusions measuring up to 100 ? m across are dominantly two-phase L + V inclusions, yet fluid inclusions with up to three daughter crystals are also observed. The largest daughter crystal is halite, commonly accompanied by a small transparent granular daughter crystal and an even smaller granular opaque crystal. Consequently, optical inspection alone demonstrates the co-occurrence of both hypersaline, multicomponent brines and less saline aqueous fluids. Ice melting temperatures for L+V inclusions vary from -0.1° to -14.5° C, with a strong mode at -2° C, corresponding to a seawater-like salinity. However, the range in Tm(ice) indicates that a significant number contain quite fresh water, and others contain quite saline water. Ice melting temperatures from the multiphase inclusions, measured in the presence of hydrohalite, range from -29.5° to -39.9° C, confirming their hypersaline composition. These data, as well as measured halite dissolution temperatures ranging from 125° to 257° C, indicate salinities of ~30+/-3 wt.% NaCl equivalent. Most two-phase inclusions homogenize to liquid between 191° C and 351° C. Two very low-salinity inclusions homogenize by critical behavior at 372° C and 385° C. A small subset of inclusions was crushed in oil, whereupon the vapor phase expanded, indicating an internal pressure >1 atm. This indicates the presence of a yet-to-be determined compressible gas component such as CO2 or CH4. During the formation of the anhydrite vein, primary fluid inclusions trapped samples of seawater-like fluid, saline brines, very low-salinity fluid, and mixtures between these three groups. The brines and very low-salinity fluids resulted from fluid phase separation at P>180 bars and T>=380° C.

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

    Microsoft Academic Search

    Francisco J. Collado

    2005-01-01

    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

  2. Effects of Carbon Nanotube Coating on Bubble Departure Diameter and Frequency in Pool Boiling on a Flat, Horizontal Heater

    E-print Network

    Glenn, Stephen T.

    2011-08-08

    The effects of a carbon nanotube (CNT) coating on bubble departure diameter and frequency in pool boiling experiments was investigated and compared to those on a bare silicon wafer. The pool boiling experiments were performed at liquid subcooling...

  3. Control Dewar Subcooler Heat Exchanger Calculations

    Microsoft Academic Search

    R. Rucinski

    1993-01-01

    The calculations done to size the control dewar subcooler were done to obtain a sufficient subcooler size based on some conservative assumptions. The final subcooler design proposed in the design report will work even better because (1) It has more tubing length, and (2) will have already subcooled liquid at the inlet due to the transfer line design. The subcooler

  4. High heat flux cooling by microbubble emission boiling.

    PubMed

    Suzuki, Koichi; Saitoh, Hiroshi; Matsumoto, Kazuaki

    2002-10-01

    In subcooled flow boiling of water in a horizontal rectangular channel, microbubble emission boiling occurred at higher subcooling of liquid in transition boiling, and the heat flux increased more than the critical heat flux. The maximum heat flux reached 10 MW/m(2) for a channel with 12 mm x 14mm cross-section at 40K liquid subcooling and 0.5 m/sec liquid velocity. For smaller rectangular channels with 14 mm x 5mm, 14mm x 3mm, and 14mm x 1mm cross-sections, the maximum heat flux was 7 MW/m(2)-more than 20 times the cooling limit of a present day CPU. Microbubble emission boiling is expected to realize high heat flux cooling for electronic devices. In convection boiling with subcooled water jet, the same boiling regime and heat flux were obtained for a downward heating surface and an upward heating surface. In subcooled flow boiling with strong convection, the hydrodynamic force is predominant for vapor-liquid exchange. Accordingly, microbubble emission boiling is expected for high heat flux cooling or high heat flux heat transfer in microgravity. PMID:12446336

  5. High flux film and transition boiling

    NASA Astrophysics Data System (ADS)

    Witte, L. C.

    1993-02-01

    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.

  6. High flux film and transition boiling

    SciTech Connect

    Witte, L.C.

    1993-02-01

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

  7. Interfacial instability of a condensing vapor bubble in a subcooled liquid

    NASA Astrophysics Data System (ADS)

    Ueno, I.; Ando, J.; Koiwa, Y.; Saiki, T.; Kaneko, T.

    2015-03-01

    A special attention is paid to the condensing and collapsing processes of vapor bubble injected into a subcooled pool. We try to extract the vapor-liquid interaction by employing a vapor generator that supplies vapor to the subcooled pool through an orifice instead of using a immersed heating surface to realize vapor bubbles by boiling phenomenon. This system enables ones to detect a spatio-temporal behavior of a single bubble of superheated vapor exposed to a subcooled liquid. In the present study, vapor of water is injected through an orifice at constant flow rate to the subcooled pool of water at the designated degree of subcooling under the atmospheric pressure. The degree of subcooling of the pool is ranged from 0 K to 70 K, and the vapor temperature is kept constant at 101 ?C. The behaviors of the injected vapor are captured by high-speed camera at frame rate up to 0.3 million frame per second (fps) to track the temporal variation of the vapor bubble shape. It is found that the abrupt collapse of the vapor bubble exposed to the subcooled pool takes place under the condition that the degree of subcooling is greater than around 30 K, and that the abrupt collapse always takes place accompanying the fine disturbances or instability emerged on the free surface. We then evaluate a temporal variation of the apparent `volume' of the bubble V under the assumption of the axisymmetric shape of the vapor bubble. It is also found that the instability emerges slightly after the volume of the vapor bubble reaches the maximum value. It is evaluated that the second derivative of the corresponding `radius' R of the vapor bubble is negative when the instability appears on the bubble surface, where R = 3? 3V/4?. We also illustrate that the wave number of the instability on the liquid-vapor interface increases as the degree of subcooling.

  8. 400°C hot Boiling Fluids From a Hydrothermal Field at 5°S on the Mid-Atlantic Ridge: Results of Meteor Cruise M64\\/1

    Microsoft Academic Search

    A. Koschinsky; D. Garbe-Schoenberg; R. Seifert; H. Strauss; S. Weber; H. Marbler

    2005-01-01

    Until recently, hydrothermal activity was unknown from the Mid-Atlantic Ridge (MAR) south of the Equator where the MAR is offset by several 100 km at the St. Paul's and Romanche fracture zones. During the British cruise CD 169 in Feb.\\/March 2005, an active hydrothermal vent field was discovered on the southern MAR at 5°S. During the German follow-up cruise M64\\/1

  9. 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

    Microsoft Academic Search

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

    1990-01-01

    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

  10. Microchannel flow boiling mechanisms leading to burnout

    SciTech Connect

    Landram, C.S.

    1994-03-01

    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.

  11. The bubble fossil record: insight into boiling nucleation using nanofluid pool-boiling

    NASA Astrophysics Data System (ADS)

    Huitink, David; Ontiveros, Elvis Efren Dominguez; Hassan, Yassin

    2012-02-01

    Subcooled pool boiling of Al2O3/water nanofluid (0.1 vol%) was investigated. Scanning electron microscopy and energy dispersive X-ray spectroscopy were used to observe surface features of the wire heater where nanoparticles had deposited. A layer of aggregated alumina particles collected on the heated surface, where evidence of fluid shear associated with bubble nucleation and departure was "fossilized" in the fluidized nano-porous surface coating. These structures contain evidence of the fluid forces present in the microlayer prior to departure and provide a unique understanding of boiling phenomena. A unique mode of heat transfer was identified in nanofluid pool boiling.

  12. Boiling of HFE-7100 on a straight pin fin

    NASA Astrophysics Data System (ADS)

    Liu, Z. W.; Lin, W. W.; Lee, D. J.; Hsu, J. P.

    2001-03-01

    This paper deals with an experimental investigation of pin fin boiling of saturated and subcooled HFE-7100 under atmospheric pressure. Fin base temperature and heat flux data are measured along with the fin tip temperature. The basic features of boiling stability of HFE-7100 boiling on pin fin had been reported for the first time. For a given liquid/heating surface combination there exist upper steady-state (USS) branch and lower steady-state (LSS) branch, and a large, unstable regime located in between. Zones with different stability characteristics are mapped according to boiling on fins with different aspect ratios. Liquid subcooling can largely enhance heat transfer performance. A longer fin can provide a safer operation.

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

    E-print Network

    Kandlikar, Satish

    AN EXPERIMENTAL INVESTIGATION ON FLOW BOILING OF ETHYLENE-GLYCOL/WATER MIXTURE Satish G. Kandlikar are used in cooling the engines in automotive applications. To avoid the two-phase flow in the engine essentially under subcooled flow boiling conditions. Very little information is available in the literature

  14. Prediction of the Pool Boiling Critical Heat Flux Using Artificial Neural Network

    Microsoft Academic Search

    H. Metin Ertunc

    2006-01-01

    This study deals with artificial neural network (ANN) based prediction of the pool boiling critical heat flux (CHF) for dielectric liquids under a variety of operating conditions. For this purpose, first, the effects of pressure and subcooling of the fluid on nucleate pool boiling and CHF on the surface of an integrated circuit (IC) immersed in a fluorocarbon FC-72 liquid

  15. Self-sustained hydrodynamic oscillations in a natural-circulation two-phase-flow boiling loop

    NASA Technical Reports Server (NTRS)

    Jain, K. C.

    1969-01-01

    Results of an experimental and theoretical study of factors affecting self-sustaining hydrodynamic oscillations in boiling-water loops are reported. Data on flow variables, and the effects of geometry, subcooling and pressure on the development of oscillatory behavior in a natural-circulation two-phase-flow boiling loop are included.

  16. Static flow instability in subcooled flow boiling in parallel channels

    Microsoft Academic Search

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

    1995-01-01

    A series of tests for static flow instability or flow excursion (FE) at conditions applicable to the proposed Advanced Neutron Source reactor was completed in parallel rectangular channels configuration with light water flowing vertically upward at very high velocities. True critical heat flux experiments under similar conditions were also conducted. The FE data reported in this study considerably extend the

  17. Manual for Subcooled Flow Boiling Code SCB-2

    Microsoft Academic Search

    Hoffman

    1990-01-01

    This manual has been written to give the user the basic instructions for using the code. The SCB-2 Code has been written to help engineers in the design of cooling systems required to handle high nonuniform axial heat fluxes. The code provides outputs of the pressure drop, pumping power required and the critical heat flux along with additional details of

  18. Forced flow boiling heat transfer of liquid hydrogen for superconductor cooling

    NASA Astrophysics Data System (ADS)

    Shirai, Yasuyuki; Tatsumoto, Hideki; Shiotsu, Masahiro; Hata, Koichi; Kobayashi, Hiroaki; Naruo, Yoshihiro; Inatani, Yoshifumi; Kinoshita, Katsuhiro

    2011-06-01

    Heat transfer from inner side of a heated vertical pipe to liquid hydrogen flowing upward was first measured at the pressure of 0.7 MPa for wide ranges of flow rates and liquid temperatures. The heat transfer coefficients in non-boiling regime for each flow velocity were well in agreement with the Dittus-Boelter equation. The heat fluxes at the inception of boiling and the departure from nucleate boiling (DNB) heat fluxes are higher for higher flow velocity and subcooling. It was found that the trend of dependence of the DNB heat flux on flow velocity was expressed by the correlation derived by Hata et al. based on their data for subcooled flow boiling of water, although it has different propensity to subcooling.

  19. A genetic algorithm model for high heat flux flow boiling

    Microsoft Academic Search

    Pasquale M. Sforza

    1997-01-01

    A new genetic algorithm model is introduced in a recently developed turbulent-boundary-layer scheme for the calculation of heat transfer in high heat flux subcooled boiling flows. Such flows, often desired for cooling of rocket nozzles and nuclear components, are characterized by high fluid velocities and extremely small bubbles that exist in a thin layer adjacent to the heated wall. The

  20. CFD simulation of convective flow boiling of refrigerant in a vertical annulus

    Microsoft Academic Search

    Boštjan Kon?ar; Eckhard Krepper

    2008-01-01

    In this paper a convective flow boiling of refrigerant R-113 in a vertical annular channel has been simulated by a CFD (Computational Fluid Dynamics) code CFX. The Arizona State University (ASU) boiling flow experiments [Roy, R.P., Kang, S., Zarate, J.A., Laporta, A., 2002. Turbulent subcooled boiling flow—experiments and simulations. J. Heat Transfer 124, 73–93] in annular channel were used to

  1. The bubble fossil record: insight into boiling nucleation using nanofluid pool-boiling

    Microsoft Academic Search

    David Huitink; Elvis Efren Dominguez Ontiveros; Yassin Hassan

    2011-01-01

    Subcooled pool boiling of Al2O3\\/water nanofluid (0.1 vol%) was investigated. Scanning electron microscopy and energy dispersive X-ray spectroscopy were used\\u000a to observe surface features of the wire heater where nanoparticles had deposited. A layer of aggregated alumina particles\\u000a collected on the heated surface, where evidence of fluid shear associated with bubble nucleation and departure was “fossilized”\\u000a in the fluidized nano-porous

  2. Pool boiling

    SciTech Connect

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

    1993-10-01

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

  3. Evaluation of engine coolants under flow boiling conditions

    SciTech Connect

    McAssey, E.V. Jr.; Stinson, C. [Villanova Univ., PA (United States). Dept. of Mechanical Engineering; Gollin, M. [ARCO Chemical Co., Newtown Square, PA (United States)

    1995-12-31

    An experimental program has been conducted to evaluate the heat transfer performance of two engine coolant mixtures, propylene-glycol/water and ethylene-glycol/water. In each mixture, the concentration was 50-50 by volume. Performance in this situation is defined as the ability to maintain a lower surface temperature for a given flux. The heat transfer regimes considered covered the range from single phase forced convection through saturated flow boiling. Results show that both coolants perform satisfactorily. However, in single phase convection, ethylene-glycol/water is slightly more effective. Conversely, for sub-cooled nucleate boiling and saturated boiling, propylene-glycol/water results in slightly lower metal temperatures.

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

    Microsoft Academic Search

    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

    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

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

    SciTech Connect

    Witte, L.C.

    1993-02-01

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

  6. Pool boiling

    Microsoft Academic Search

    Lallemand

    1993-01-01

    Heat transfer between a wall and a stagnant boiling liquid is reviewed in this paper. The effect of different parameters on the boiling curve is pointed out on the basis of experimental data from the literature. Augmentation of heat transfer by enhanced surfaces is described briefly. The available correlations for prediction of heat transfer coefficients are given for the entire

  7. Testing and evaluation of small cavitating venturis with water at low inlet subcooling

    NASA Astrophysics Data System (ADS)

    Liou, S. G.; Chen, I. Y.; Sheu, J. S.

    1998-01-01

    Cavitating venturi (CV) has been widely used as a flow control device in many different industries. In 1990, cavitating venturi was selected as the baseline flow control device in the Space Station Freedom's (SSF's) two-phase active thermal control system (ATCS). However, the design and the operation of the CVs used in SSF's ATCS is quite different in many ways from that typically used in the industry, such as low mass flow rate, small size, low pressure difference between inlet and outlet, and low inlet subcooling. During the prototypic ATCS' testing at NASA/Johnson Space Center, a phenomenon called overflow associated with throat superheat was observed. Although data was obtained and analyzed, no useful correlation for the superheat at rechoking was acquired. The objective of this study is to conduct a performance test on small CVs under low inlet subcooling. Water is used as the working fluid. Data acquisition and analysis are carried out under normal choked flow, over flow and recovery conditions. The effects of CV's size, fluid temperature, flow condition and inlet subcooling on CV performance are evaluated. Analysis of the test results showed that the superheat necessary for the onset of nucleation in pool boiling can be applied for the estimation of superheat required at rechoking for the CVs. With this postulated superheat and the predetermined CV loss coefficient, a equation as a function of inlet subcooling is recommended for predicting the pressure ratio at the recovery for the choked flow control in a mechanically pumped system.

  8. Thermodynamics of Flow Boiling Heat Transfer

    NASA Astrophysics Data System (ADS)

    Collado, F. J.

    2003-05-01

    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.

  9. An experimental and theoretical investigation of multicomponent pool boiling on smooth and finned surfaces. (Volumes I and II)

    Microsoft Academic Search

    Bajorek

    1988-01-01

    A comprehensive experimental and theoretical study of the effect of mixture composition on nucleate pool-boiling heat transfer coefficients in multicomponent mixtures was performed. Measurements of saturated and subcooled pool-boiling heat transfer coefficients were made in mixtures with up to four components on conventional smooth and finned tubes. The effect of a component on the degradation in multicomponent pool-boiling heat transfer

  10. Visualization study on pool boiling heat transfer

    NASA Astrophysics Data System (ADS)

    Kamei, Shuya; Hirata, Masaru

    1991-04-01

    The visualized boiling phenomena were observed by means of high speed photographic shadowgraphy using a rotating prism camera (nac HIGH SPEED CAMERA model-16HD) with the speed of about 3500 frames per second. The photographs show that pool boiling heat transfer phenomena are varied for the boiling curve based on the experiments. Experiments have been carried out to investigate pool boiling heat transfer phenomena on a horizontal thin filament in subcooled and saturated distilled water. The experiments were performed for atmospheric pressure,for filament diameters of about 0.3 mm, for region of natural convection to film boiling. The color-film made by high speed movie camera are converted to high speed color video-tape. It is convenient to edit and show the tape for visualization with teaching the students. The high speed color video showed that the successive motion and shape of bubbles during their process of detachment varied with increasing heat flux on the heated surface of a filament. From these results, it was confirmed that the high speed phenomena of boiling by the slow motion video pictures could be estimated clearly.

  11. Boiling incipience in a reboiler tube

    SciTech Connect

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

    1991-03-01

    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.

  12. Forced Convection Heat Transfer of Subcooled Liquid Nitrogen in Horizontal Tube

    NASA Astrophysics Data System (ADS)

    Tatsumoto, H.; Shirai, Y.; Hata, K.; Kato, T.; Shiotsu, M.

    2008-03-01

    The knowledge of forced convection heat transfer of liquid hydrogen is important for the cooling design of a HTS superconducting magnet and a cold neutron moderator material. An experimental apparatus that could obtain forced flow without a pump was developed. As a first step of the study, the forced flow heat transfer of subcooled liquid nitrogen in a horizontal tube, instead of liquid hydrogen, was measured for the pressures ranging from 0.3 to 2.5 MPa. The inlet temperature was varied from 78 K to around its saturation temperature. The flow velocities were varied from 0.1 to 7 m/s. The heat transfer coefficients in the non-boiling region and the departure from nucleate boiling (DNB) heat fluxes were higher for higher flow velocity and higher subcooling. The measured values of Nu/Pr0.4 in the non-boiling region were proportional to Reynolds number (Re) to the power of 0.8. With a decrease in Re, Nu/Pr0.4 approached a constant value corresponding to that in a pool of liquid nitrogen. The correlation of DNB heat flux was derived that can describe the experimental data within ±15% difference.

  13. Relative stability of boiling of FC-72 and HFE-7100 with applications to electronic device cooling

    NASA Astrophysics Data System (ADS)

    Liu, Z. W.; Lin, W. W.; Lee, D. J.; Peng, X. F.

    2000-12-01

    This paper investigates the relative stability between nucleate and film boiling modes of FC-72 and HFE-7100, which have potential to electronic device cooling applications. Equilibrium heat flux, q c, which refers to as an index for measuring the relative stability of boiling, was obtained at a liquid subcooling of 0-20 K. Experimental results reveal that (1) q cincreases with liquid subcooling; (2) although the FC-72 exhibits a higher critical heat flux (CHF) than does the HFE-7100, somewhat unexpectedly, the equilibrium heat flux for the latter is greater than the former. Restated, at a prescribed heat flux, the risk to burnout for boiling of FC-72 is higher than that of HFE-7100. The shift in boiling curves interprets the experimental findings.

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

    SciTech Connect

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

    1997-12-31

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

  15. Pool boiling from rotating and stationary spheres in liquid nitrogen

    NASA Technical Reports Server (NTRS)

    Cuan, Winston M.; Schwartz, Sidney H.

    1988-01-01

    Results are presented for a preliminary experiment involving saturated pool boiling at 1 atm from rotating 2 and 3 in. diameter spheres which were immersed in liquid nitrogen (LN2). Additional results are presented for a stationary, 2 inch diameter sphere, quenched in LN2, which were obtained utilizing a more versatile and complete experimental apparatus that will eventually be used for additional rotating sphere experiments. The speed for the rotational tests was varied from 0 to 10,000 rpm. The stationary experiments parametrically varied pressure and subcooling levels from 0 to 600 psig and from 0 to 50 F, respectively. During the rotational tests, a high speed photographic analysis was undertaken to measure the thickness of the vapor film surrounding the sphere. The average Nusselt number over the cooling period was plotted against the rotational Reynolds number. Stationary sphere results included local boiling heat transfer coefficients at different latitudinal locations, for various pressure and subcooling levels.

  16. Boiling oxygen experimental studies in an electrically heated tube

    NASA Technical Reports Server (NTRS)

    Peroulias, C.; Pidcoke, L. H.; Schwartz, S. H.; Mussell, D. E.

    1988-01-01

    An experimental study was made of subcooled flow boiling with LOX; data were obtained with thermocouples attached to the walls of an electrically heated tube through which the LOX flowed. Pressure levels in the tube ranged from 200 psia to supercritical values, and the cooling level varied from the saturated condition to 50 F. Reynolds numbers ranged from 1.5 x 10 to 3.5 x 10 to the 5th. Results show that an increase in either pressure, subcooling level, or Reynolds number produces an increase in the film boiling heat transfer coefficient. Data for this range of parameters were found to correlate in terms of the Stanton number vs (T sub w - T sub s)/(T sub s - T sub b), where T is temperature, w is the wall, s is the saturated condition, and b is the bulk.

  17. Boiling Experiment Facility for Heat Transfer Studies in Microgravity

    NASA Technical Reports Server (NTRS)

    Delombard, Richard; McQuillen, John; Chao, David

    2008-01-01

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

  18. Enhanced flow boiling heat transfer of FC72 on micro-pin-finned surfaces

    Microsoft Academic Search

    Aixiang Ma; Jinjia Wei; Minzhe Yuan; Jiabin Fang

    2009-01-01

    For the purpose of cooling electronic components with high heat flux efficiently, some experiments were conducted to study the flow boiling heat transfer performance of FC-72 on silicon chips. Micro-pin-fins were fabricated on the chip surface using a dry etching technique to enhance boiling heat transfer. Three different fluid velocities (0.5, 1 and 2m\\/s) and three different liquid subcoolings (15,

  19. Confined boiling of FC72 and FC87 on a downward facing heating copper disk

    Microsoft Academic Search

    J. C. Passos; F. R. Hirata; L. F. B. Possamai; M. Balsamo; M. Misale

    2004-01-01

    This paper presents results for FC72 and FC87 saturated and subcooled nucleate pool boiling, at atmospheric pressure, on a downward facing surface and in confined spaces between a heated copper disk (diameter 12 mm and thickness 2 mm) and an unheated surface, for distances varying between 0.2 and 13 mm. At saturated boiling and low heat flux (?45 kW\\/m2) a

  20. Effects of gravity on the boiling of binary fluid mixtures

    Microsoft Academic Search

    S. Ahmed; V. P. Carey

    1998-01-01

    Experiments have been conducted with water\\/2-propanol mixtures under reduced gravity, normal gravity and high gravity in order to investigate Marangoni effects and their interaction with the gravitational effect in the pool boiling of binary mixtures. The system pressure was subatmospheric (? 8 kPa at lgn)and the bulk liquid temperature varied from low subcooling to near saturation. The molar concentrations of

  1. NATURAL CONVECTION OF SUBCOOLED LIQUID NITROGEN IN A VERTICAL CAVITY

    E-print Network

    Chang, Ho-Myung

    NATURAL CONVECTION OF SUBCOOLED LIQUID NITROGEN IN A VERTICAL CAVITY Yeon SukChoi \\ Steven W. Van to measure the natural convection of subcooled liquid nitrogen between two vertical plates has been performed power transformer cooled by natural convection of subcooled liquid nitrogen. A liquid nitrogen bath

  2. Effect of an Externally Applied Electric Field on Pool Film Boiling of FC72

    Microsoft Academic Search

    Massimiliano Cipriani; PAOLO DI MARCO; Walter Grassi

    2004-01-01

    The paper reports the results obtained during an experimental study on film boiling on wires in the presence of an externally imposed electrostatic field. The arrangement allowed to achieve various combinations of pressure and subcooling, independently of the environmental conditions. The test section was an electrically heated platinum wire with diameters of 0.1 and 0.2 mm. The working fluid was

  3. Study of spray cooling of a pressure vessel head of a boiling water reactor

    Microsoft Academic Search

    Henryk Anglart; Farid Alavyoon; Rémi Novarini

    2010-01-01

    The present paper deals with a theoretical analysis of the spray cooling of a Reactor Pressure Vessel (RPV) head in a Boiling Water Reactor (BWR). To this end a detailed computational model has been developed. The model predicts the trajectories, diameters and temperatures of subcooled droplets moving in saturated vapor. The model has been validated through comparison with experimental data,

  4. An experimental research on microbubble emission boiling

    NASA Astrophysics Data System (ADS)

    Tang, Jiguo; Zhu, Guangyu; Sun, Licheng; Cao, Xiaxin

    2013-07-01

    In the near future, heat transfer technology with higher performance surely has more application in the field of thermal engineering, such as electrical chip cooling, power regulating system, etc. Microbubble emission boiling (MEB) is getting more attentions by many researchers due to its extremely high heat dissipation capacity and potential application in the areas mentioned above. Despite that much work has been done to MEB, heat transfer characteristics and occurrence condition as well as formation mechanism involved MEB are not illustrated clearly by far. An experimental setup is built up to study MEB visually. The heating element is a cone copper block with its upper part of a 10mm diameter cylinder which is insulated from the water by a ceramic thimble. The different liquid subcooling is obtained by a water cooler combined with an electric heater. A high-speed video camera (Photron: Fastcam SA5) is employed for recording the scenario of MEB. Our experimental results are very similar to that from other researchers, and the maximum heat flux is about 9 MW/m2 at 60K subcooling. The presence of noncondensable gas in the vapor film and the liquid subcooling has obviously impact on MEB. Moreover, numerical simulation results show that marangoni convection is perhaps one of the reasons inducing the occurrence of MEB.

  5. Subcooled Liquid Oxygen Cryostat for Magneto-Archimedes Particle Separation by Density

    NASA Astrophysics Data System (ADS)

    Hilton, D. K.; Celik, D.; Van Sciver, S. W.

    2008-03-01

    An instrument for the separation of particles by density (sorting) is being developed that uses the magneto-archimedes effect in liquid oxygen. With liquid oxygen strongly paramagnetic, the magneto-archimedes effect is an extension of diamagnetic levitation in the sense of increasing the effective buoyancy of a particle. The instrument will be able to separate ensembles of particles from 100 ?m to 100 nm in size, and vertically map or mechanically deliver the separated particles. The instrument requires a column of liquid oxygen that is nearly isothermal, free of thermal convection, subcooled to prevent nucleate boiling, and supported against the strong magnetic field used. Thus, the unique cryostat design that meets these requirements is described in the present article. It consists in part of a column of liquid nitrogen below for cooling the liquid oxygen, with the liquid oxygen pressurized by helium gas to prevent nucleate boiling.

  6. Some parameter boundaries governing microgravity pool boiling modes.

    PubMed

    Merte, Herman

    2006-09-01

    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 imposed heat flux and three levels of initial bulk liquid subcooling. In many of the total of 45 experiments, steady nucleate boiling was observed from 16-mm movie films, where a large vapor bubble formed and remained slightly removed from the heater surface, with small vapor bubbles growing on the heater surface, and on contact coalescing with the large bubble. Computations of the forces associated with the momentum transfer in this process, which counters the Marangoni convection effects tending to impel the large bubble toward the heater surface, have been completed for all cases where applicable. The modes of pool boiling observed with successive increases in levels of heat flux in microgravity are categorized as: (i) minimum or incipient nucleate boiling; (ii) nucleate boiling with vigorous motion of the bubbles adjacent and parallel to the heater surface, impelled by Marangoni convection effects; (iii) nucleate boiling followed by coalescence with a neighboring large vapor bubble; (iv) partial dryout of the heater surface, in parallel with nucleate boiling; (v) complete dryout. The boundaries between these modes are delineated graphically as a function of the imposed heat flux and initial bulk liquid subcooling, together with the levels of the forces holding the large bubbles, acting as vapor reservoirs, away from the heater surface for the steady nucleate boiling mode. PMID:17124149

  7. 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.

  8. Dynamics of discrete bubble in nucleate pool boiling on thin wires in microgravity

    NASA Astrophysics Data System (ADS)

    Wan, Shixin; Zhao, Jianfu; Liu, Gang

    2009-03-01

    A space experiment on bubble behavior and heat transfer in subcooled pool boiling phenomenon has been performed utilizing the temperature-controlled pool boiling (TCPB) device both in normal gravity in the laboratory and in microgravity aboard the 22nd Chinese recoverable satellite. The fluid is degassed R113 at 0.1 MPa and subcooled by 26°C nominally. A thin platinum wire of 60 ?m in diameter and 30 mm in length is simultaneously used as heater and thermometer. Only the dynamics of the vapor bubbles, particularly the lateral motion and the departure of discrete vapor bubbles in nucleate pool boiling are reported and analyzed in the present paper. It’s found that these distinct behaviors can be explained by the Marangoni convection in the liquid surrounding vapor bubbles. The origin of the Marangoni effect is also discussed.

  9. Flow boiling critical heat flux on small heated regions

    NASA Astrophysics Data System (ADS)

    Simon, Terrence W.; Wu, Pey-Shey

    1993-11-01

    Often, in optical and electronic equipment, heating is concentrated in very small regions, and, because of materials constraints, cooled walls must be as thin as possible. Also, for efficiency, many high-flux cooling designs involve forced-convection boiling heat transfer. Though efficient, a design with boiling heat transfer can be difficult for it must properly account for the complexities of the boiling flux-temperature relationship. Of concern is locating the point of incipience to boiling and the point of maximum nucleate boiling heat flux, Critical Heat Flux (CHF), and describing the complex behaviors in the vicinities of these points. Characteristics of boiling near these points are discussed in terms of boundary layer behavior. Changes in either the heater size or the wall thickness affects the boiling curve, particularly the CHF behavior. Results from experiments which were conducted on small, heated regions are discussed in light of their application to the design of high-power optical and electronic devices. The effects of flow velocity, subcooling, pressure, heating length, dissolved gas content, and flow streamline curvature are addressed.

  10. Thermoeconomic optimization of subcooled and superheated vapor compression refrigeration cycle

    Microsoft Academic Search

    Re?at Selba?; Önder K?z?lkan; Arzu ?encan

    2006-01-01

    An exergy-based thermoeconomic optimization application is applied to a subcooled and superheated vapor compression refrigeration system. The advantage of using the exergy method of thermoeconomic optimization is that various elements of the system—i.e., condenser, evaporator, subcooling and superheating heat exchangers—can be optimized on their own. The application consists of determining the optimum heat exchanger areas with the corresponding optimum subcooling

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

    NSDL National Science Digital Library

    Math Forum

    2001-01-01

    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.

  12. Lateral Motion and Departure of Vapor Bubbles in Nucleate Pool Boiling on Thin Wires in Microgravity

    NASA Astrophysics Data System (ADS)

    Zhao, J. F.; Wan, S. X.; Liu, G.; Li, Z. D.; Lu, Y. H.; Yan, N.

    A space experiment on bubble behavior and heat transfer in subcooled pool boiling phenomenon has been performed utilizing the temperature-controlled pool boiling (TCPB) device both in normal gravity in the laboratory and in microgravity aboard the 22nd Chinese recoverable satellite. The fluid is R113 at 0.lMPa and subcooled by 26°C nominally. A thin platinum wire of 60µm in diameter and 30mm in length is simultaneously used as heater and thermometer. Only the lateral motion and the departure of discrete vapor bubbles in nucleate pool boiling are reported and analyzed in the present paper. A scale analysis on the Marangoni convection surrounding a bubble in the process of subcooled nucleate pool boiling leads to formulas of the characteristic velocity of the lateral motion and its observability. The predictions consist with the experimental observations. Considering the Marangoni effect, a new qualitative model is proposed to reveal the mechanism underlying the bubble departure processes and a quantitative agreement can also be acquired.

  13. CO2 transcritical vapor compression cycle with thermoelectric subcooler

    Microsoft Academic Search

    Jonathan Schoenfield; Yunho Hwang; Rienhard Radermacher

    2012-01-01

    In this article, the integration of two different cooling technologies: thermoelectric (TE) cooling and the vapor compression cycle (VCC), is investigated to enhance the performance of the latter. In the integrated system, the TE cooler is utilized as a subcooler of the VCC condenser or gas cooler. In this integration, the TE subcooler is operated at a small temperature lift

  14. CO2 Transcritical Vapor Compression Cycle with Thermoelectric Subcooler

    Microsoft Academic Search

    Jonathan Schoenfield; Yunho Hwang; Rienhard Radermacher

    2012-01-01

    In this paper, the integration of two different cooling technologies: thermoelectric (TE) cooling and the vapor compression cycle (VCC), is investigated to enhance the performance of the latter. In the integrated system, the TE cooler is utilized as a subcooler of the VCC condenser or gas cooler. In this integration, the TE subcooler is operated at a small temperature lift

  15. A Study of Nucleate Boiling with Forced Convection in Microgravity

    NASA Technical Reports Server (NTRS)

    Merte, Herman, Jr.

    1999-01-01

    The ultimate objective of basic studies of flow boiling in microgravity is to improve the understanding of the processes involved, as manifested by the ability to predict its behavior. This is not yet the case for boiling heat transfer even in earth gravity, despite the considerable research activity over the past 30 years. The elements that constitute the nucleate boiling process - nucleation, growth, motion, and collapse of the vapor bubbles (if the bulk liquid is subcooled) - are common to both pool and flow boiling. It is well known that the imposition of bulk liquid motion affects the vapor bubble behavior relative to pool boiling, but does not appear to significantly influence the heat transfer. Indeed, it has been recommended in the past that empirical correlations or experimental data of pool boiling be used for design purposes with forced convection nucleate boiling. It is anticipated that such will most certainly not be possible for boiling in microgravity, based on observations made with pool boiling in microgravity. In earth gravity buoyancy will act to remove the vapor bubbles from the vicinity of the heater surface regardless of how much the imposed bulk velocity is reduced, depending, of course, on the geometry of the system. Vapor bubbles have been observed to dramatically increase in size in pool boiling in microgravity, and the heat flux at which dryout took place was reduced considerably below what is generally termed the critical heat flux (CHF) in earth gravity, depending on the bulk liquid subcooling. However, at heat flux levels below dryout, the nucleate pool boiling process was enhanced considerably over that in earth gravity, in spite of the large vapor bubbles formed in microgravity and perhaps as a consequence. These large vapor bubbles tended to remain in the vicinity of the heater surface, and the enhanced heat transfer appeared to be associated with the presence of what variously has been referred to as a liquid microlayer between the bubble and the heater surface. The enhancement of the boiling process with low velocities in earth gravity for those orientations producing the formation of a liquid macrolayer described above, accompanied by "sliding" vapor bubbles, has been demonstrated. The enhancement was presented as a function of orientation, subcooling, and heated length, while a criterion for the heat transfer for mixed natural/forced convection nucleate boiling was given previously. A major unknown in the prediction and application of flow boiling heat transfer in microgravity is the upper limit of the heat flux for the onset of dryout (or critical heat flux - CHF), for given conditions of fluid-heater surfaces, including geometry, system pressure and bulk liquid subcooling. It is clearly understood that the behavior in microgravity will be no different than on earth with sufficiently high flow velocities, and would require no space experimentation. However, the boundary at which this takes place is still an unknown. Previous results of CHF measurements were presented for low velocity flow boiling at various orientations in earth gravity as a function of flow velocity and bulk liquid subcooling, along with preliminary measurements of bubble residence times on a flat heater surface. This showed promise as a parameter to be used in modeling the CHF, both in earth gravity and in microgravity. The objective of the work here is to draw attention to and show results of current modeling efforts for the CHF, with low velocities in earth gravity at different orientations and subcoolings. Many geometrical possibilities for a heater surface exist in flowing boiling, with boiling on the inner and outer surfaces of tubes perhaps being the most common. If the vapor bubble residence time on and departure size from the heater surface bear a relationship to the CHF, as results to be given indicate, it is important that visualization of and access to vapor bubble growth be conveniently available for research purposes. In addition, it is desirable to reduce the number of variables as much as p

  16. Simplified Model Predicting Contact-Line-Length Density at Critical Heat Flux Based on Direct Observation of Boiling Structure

    NASA Astrophysics Data System (ADS)

    Nishio, Shigefumi; Tanaka, Hiroaki

    Great efforts have been made to attain a good understanding of boiling heat transfer, but we have a poor understanding for the boiling structures in high heat-flux boiling. For example, there are still opposing opinions for the mechanism of the critical heat flux in saturated boiling and there are no rigorous models for that in subcooled boiling. In the present paper, the nucleation site density (NSD) was measured using high-speed video pictures and an image processing technique. The video pictures were taken from below the boiling surface made of single crystal sapphire with a total reflection technique. Based on the experimental results of NSD, a simplified model predicting the contact-line-length density (CLLD) at CHF is proposed.

  17. Natural Circulation Loop of Subcooled Liquid Nitrogen

    NASA Astrophysics Data System (ADS)

    Kim, M. J.; Chang, H. M.

    2008-03-01

    An experimental study is performed to investigate the thermal and flow characteristics of subcooled liquid nitrogen in a natural circulation loop. A round tube with uniform diameter is fabricated into a circulation loop and vertically located in a cryostat, where a GM cryocooler is heat sink at the top and an electrical heater is heat source nearly at the bottom. Steady flow of subcooled liquid nitrogen in the loop is successfully obtained by setting the heating power at a given level. Temperature is measured at several locations of the loop, and the mass flow rate through the loop is estimated from the local energy balance in terms of the measured temperatures. Experiment is repeated for various values of the heating power and the vertical height between the cryocooler and the heater. The experimental results are in agreement with existing data and correlations to take into account the buoyancy and viscous forces. It is verified that the heat transfer rate of the loop has a maximum at a certain value of loop height.

  18. Two-Phase Flow Instabilities in Boiling and Condensing Systems

    NASA Astrophysics Data System (ADS)

    Ruspini, Leonardo C.; Dorao, Carlos; Fernandino, Maria

    In this work Density Wave Oscillations (DWO) and Ledinegg instabilities are analyzed for boiling and condensing systems in a single tube. The analysis is based on a numerical model solved with a least squares spectral element method which is characterized by negligible numerical diffusion and high accuracy. Stability limits are constructed and compared with available correlations. The analysis is extended to sub-cooled, saturated and over-heated inlet conditions. Finally a discussion regarding the occurrence of these phenomena in condensing systems is presented.

  19. Net vapor generation point in boiling flow of trichlorotrifluoroethane at high pressures

    NASA Technical Reports Server (NTRS)

    Dougall, R. S.; Lippert, T. E.

    1973-01-01

    The conditions at which the void in subcooled boiling starts to undergo a rapid increase were studied experimentally. The experiments were performed in a 12.7 x 9.5 mm rectangular channel. Heating was from a 3.2 mm wide strip embedded in one wall. The pressure ranged from 9.45 to 20.7 bar, mass velocity from 600 to 7000 kg/sq m sec, and subcooling from 16 to 67 C. Photographs were used to determine when detached bubbles first appeared in the bulk flow. Measurements of bubble layer thickness along the wall were also made. Results showed that the point of net vapor generation is close to the occurrence of fully-developed boiling.

  20. Two-phase structure above hot surfaces in jet impingement boiling

    NASA Astrophysics Data System (ADS)

    Bogdanic, L.; Auracher, H.; Ziegler, F.

    2009-05-01

    Jet impingement boiling is very efficient in cooling of hot surfaces as a part of the impinging liquid evaporates. Several studies have been carried out to measure and correlate the heat transfer to impinging jets as a function of global parameters such as jet subcooling, jet velocity, nozzle size and distance to the surface, etc. If physically based mechanistic models are to be developed, studies on the fundamentals of two-phase dynamics near the hot surface are required. In the present study the vapor-liquid structures underneath a subcooled (20 K) planar (1 mm × 9 mm) water jet, impinging the heated plate vertically with a velocity of 0.4 m/s, were analyzed by means of a miniaturized optical probe. It has a tip diameter of app. 1.5 ?m and is moved toward the plate by a micrometer device. The temperature controlled experimental technique enabled steady-state experiments in all boiling regimes. The optical probe data provides information about the void fraction, the contact frequencies and the distribution of the vapor and liquid contact times as a function of the distance to the surface. The measured contact frequencies range from 40 Hz at the onset of nucleate boiling to nearly 20,000 Hz at the end of the transition boiling regime. Due to condensation in the subcooled jet vapor disappears at a distance to the surface of app. 1.2 mm in nucleate boiling. This vapor layer becomes smaller with increasing wall superheat. In film boiling a vapor film thickness of 8 ± 2 ?m was found.

  1. Development of NUFREQ-N, an analytical model for the stability analysis of nuclear coupled density-wave oscillations in boiling-water nuclear reactors

    Microsoft Academic Search

    G. C. Park; M. Podowski; M. Becker; Lahey R. T. Jr

    1983-01-01

    A state-of-the-art one-dimensional thermal-hydraulic model has been developed to be used for the linear analysis of nuclear-coupled density-wave oscillations in a boiling water nuclear reactor (BWR). The model accounts for phasic slip, distributed spacers, subcooled boiling, space\\/time-dependent power distributions and distributed heated wall dynamics. In addition to a parallel channel stability analysis, a detailed model was derived for the BWR

  2. Development of NUFREQ-N, an analytical model for the stability analysis of nuclear coupled density-wave oscillations in boiling water nuclear reactors

    Microsoft Academic Search

    1983-01-01

    A state-of-the-art one-dimensional thermal-hydraulic model has been developed to be used for the linear analysis of nuclear-coupled density-wave oscillations in a boiling water nuclear reactor (BWR). The model accounts for phasic slip, distributed spacers, subcooled boiling, space\\/time-dependent power distributions and distributed heated wall dynamics. In addition to a parallel channel stability analysis, a detailed model was derived for the BWR

  3. Nucleate Boiling Heat Transfer Studied Under Reduced-Gravity Conditions

    NASA Technical Reports Server (NTRS)

    Chao, David F.; Hasan, Mohammad M.

    2000-01-01

    Boiling is known to be a very efficient mode of heat transfer, and as such, it is employed in component cooling and in various energy-conversion systems. In space, boiling heat transfer may be used in thermal management, fluid handling and control, power systems, and on-orbit storage and supply systems for cryogenic propellants and life-support fluids. Recent interest in the exploration of Mars and other planets and in the concept of in situ resource utilization on the Martian and Lunar surfaces highlights the need to understand how gravity levels varying from the Earth's gravity to microgravity (1g = or > g/g(sub e) = or > 10(exp -6)g) affect boiling heat transfer. Because of the complex nature of the boiling process, no generalized prediction or procedure has been developed to describe the boiling heat transfer coefficient, particularly at reduced gravity levels. Recently, Professor Vijay K. Dhir of the University of California at Los Angeles proposed a novel building-block approach to investigate the boiling phenomena in low-gravity to microgravity environments. This approach experimentally investigates the complete process of bubble inception, growth, and departure for single bubbles formed at a well-defined and controllable nucleation site. Principal investigator Professor Vijay K. Dhir, with support from researchers from the NASA Glenn Research Center at Lewis Field, is performing a series of pool boiling experiments in the low-gravity environments of the KC 135 microgravity aircraft s parabolic flight to investigate the inception, growth, departure, and merger of bubbles from single- and multiple-nucleation sites as a function of the wall superheat and the liquid subcooling. Silicon wafers with single and multiple cavities of known characteristics are being used as test surfaces. Water and PF5060 (an inert liquid) were chosen as test liquids so that the role of surface wettability and the magnitude of the effect of interfacial tension on boiling in reduced gravity can be investigated.

  4. Electrohydrodynamically coupled film boiling

    Microsoft Academic Search

    T. B. Jones

    1976-01-01

    A strong nonuniform electric field is known to have a significant effect on convective, nucleate, and film boiling heat transfer. The principal electrohydrodynamic coupling mechanism in the film boiling regime of pool boiling is an interfacial mechanism which alters the surface wave dispersion. A theoretical model for this coupling is favorably compared to experiment for the insulating liquid, a-c electric

  5. Evidence of Ni 2FeBO 5 and m-ZrO 2 precipitates in fuel rod deposits in AOA-affected high boiling duty PWR core

    NASA Astrophysics Data System (ADS)

    Sawicki, Jerzy A.

    2008-02-01

    This paper describes the characteristics of corrosion product deposits found in upper regions of high axial offset anomaly (AOA) once-burnt fuel assemblies after Cycle 9 in the Callaway pressurized water reactor (PWR). The ˜100-?m-thick deposits consisted of a new type of highly porous and structured Ni-, Fe-, B-, and Zr-rich material. The analyses showed that deposits contain a large amount (about 50 wt%) of Ni-Fe oxyborate (Ni 2FeBO 5, mineral name bonaccordite), in the form of matted ˜0.1-?m-thick and ˜10-?m-long, needle-like particles. An especially high density of Ni 2FeBO 5 needles was found in a 30-40-?m-thick zone on the clad side of the deposits. This compound has not previously been reported as a component of PWR fuel crud. Common fuel crud components such as nickel ferrite and nickel oxide were observed only in small quantities (about 10 wt%). Reference samples of Ni 2FeBO 5 were obtained by hydrothermal reactions in alkaline aqueous solutions starting from about 400 °C, or by sintering at about 1000 °C. Formation of Ni 2FeBO 5 has been identified as a new mechanism for boron retention and neutron absorption on PWR fuel. Aggregates of apparently hydrothermally precipitated ˜0.1-0.3-?m-sized particles of monoclinic m-ZrO 2(˜30 wt%) were found in the deposits, which is indicative of a dissolution-precipitation process at the cladding surface. This process may be enhanced by a LiOH concentration mechanism in crud, which is a result of both sub-cooled nucleate boiling and 10B(n,?) 7Li reactions. Consistently, the isotopic abundance of 10B in Ni 2FeBO 5 in crud samples was reduced to about 10% of the total boron.

  6. Results of BDH experiment in TR-IA 1st flight - Results of pool boiling

    NASA Astrophysics Data System (ADS)

    Abe, Yoshiyuki; Iwasaki, Akira

    As the first experiment of BDH (Bubble Dynamics and Handing) module in TR-IA sounding rocket, a pool boiling experiment with a transparent glass heater and an interferometer was conducted under a relatively low heat flux. During six minutes of microgravity condition, boiling phenomena observation and interferometric observation were planned in addition to the acquisition of heat transfer data. The heat transfer characteristics showed a large influence due to liquid subcooling, and the interferometric observation implied the existence of a stationary microlayer under isolated bubbles.

  7. Numerical Analysis of Lead-Bismuth-Water Direct Contact Boiling Heat Transfer

    NASA Astrophysics Data System (ADS)

    Yamada, Yumi; Takahashi, Minoru

    Direct contact boiling heat transfer of sub-cooled water with lead-bismuth eutectic (Pb-Bi) was investigated for the evaluation of the performance of steam generation in direct contact of feed water with primary Pb-Bi coolant in upper plenum above the core in Pb-Bi-cooled direct contact boiling water fast reactor. An analytical two-fluid model was developed to estimate the heat transfer numerically. Numerical results were compared with experimental ones for verification of the model. The overall volumetric heat transfer coefficient was calculated from heat exchange rate in the chimney. It was confirmed that the calculated results agreed well with the experimental result.

  8. Flow boiling with enhancement devices for cold plate coolant channel design

    NASA Astrophysics Data System (ADS)

    Boyd, Ronald D., Sr.; Smith, Alvin

    1990-02-01

    The use of flow boiling for thermal energy transport is intended to provide an alternative for accommodating higher heat fluxes in commercial space systems. The objectives are to: (1) examine the variations in both the mean and local (axial and circumferential) heat transfer coefficients for a circular coolant channel with either smooth walls, spiral fins, or both spiral fins and a twisted tape; (2) examine the effects of channel diameter and subcooling; and (3) develop an improved reduction analysis and/or suggest possible heat transfer correlation of the present data. Freon-11 is the working fluid. Two-dimensional (circumferential and axial) wall temperature distributions were measured for coolant channels with the above noted internal geometries. The flow regimes which are being studied are: (1) single phase; (2) subcooled flow boiling; and (3) stratified flow boiling. The inside diameter of all test sections is near 1.0 cm. Cicumferentially averaged heat transfer coefficients at several axial locations were obtained for selected coolant channels for a mass velocity of 210 kg/sq m s, an exit pressure of 0.19 MPa (absolute), and an inlet subcooling of 20.8 C. Overall (averaged over the entire channel) heat transfer coefficients were compared for the above channel geometries. This comparison showed that the channel with large pitch spiral fins had higher heat transfer coefficients at all power levels.

  9. Flow boiling with enhancement devices for cold plate coolant channel design

    NASA Technical Reports Server (NTRS)

    Boyd, Ronald D., Sr.; Smith, Alvin

    1990-01-01

    The use of flow boiling for thermal energy transport is intended to provide an alternative for accommodating higher heat fluxes in commercial space systems. The objectives are to: (1) examine the variations in both the mean and local (axial and circumferential) heat transfer coefficients for a circular coolant channel with either smooth walls, spiral fins, or both spiral fins and a twisted tape; (2) examine the effects of channel diameter and subcooling; and (3) develop an improved reduction analysis and/or suggest possible heat transfer correlation of the present data. Freon-11 is the working fluid. Two-dimensional (circumferential and axial) wall temperature distributions were measured for coolant channels with the above noted internal geometries. The flow regimes which are being studied are: (1) single phase; (2) subcooled flow boiling; and (3) stratified flow boiling. The inside diameter of all test sections is near 1.0 cm. Cicumferentially averaged heat transfer coefficients at several axial locations were obtained for selected coolant channels for a mass velocity of 210 kg/sq m s, an exit pressure of 0.19 MPa (absolute), and an inlet subcooling of 20.8 C. Overall (averaged over the entire channel) heat transfer coefficients were compared for the above channel geometries. This comparison showed that the channel with large pitch spiral fins had higher heat transfer coefficients at all power levels.

  10. Large-scale boiling experiments of the flooded cavity concept for in-vessel core retention

    SciTech Connect

    Chu, T.Y.; Slezak, S.E.; Bentz, J.H. [Sandia National Labs., Albuquerque, NM (United States)] [Sandia National Labs., Albuquerque, NM (United States); Pasedag, W.F. [USDOE, Washington, DC (United States)] [USDOE, Washington, DC (United States)

    1994-03-01

    This paper presents results of ex-vessel boiling experiments performed in the CYBL (CYlindrical BoiLing) facility. CYBL is a reactor-scale facility for confirmatory research of the flooded cavity concept for accident management. CYBL has a tank-within-a-tank design; the inner tank simulates the reactor vessel and the outer tank simulates the reactor cavity. Experiments with uniform and edge-peaked heat flux distributions up to 20 W/cm{sup 2} across the vessel bottom were performed. Boiling outside the reactor vessel was found to be subcooled nucleate boiling. The subcooling is mainly due to the gravity head which results from flooding the sides of the reactor vessel. The boiling process exhibits a cyclic pattern with four distinct phases: direct liquid/solid contact, bubble nucleation and growth, coalescence, and vapor mass dispersion (ejection). The results suggest that under prototypic heat load and heat flux distributions, the flooded cavity in a passive pressurized water reactor like the AP-600 should be capable of cooling the reactor pressure vessel in the central region of the lower head that is addressed by these tests.

  11. Bubble — bubbles — boiling

    Microsoft Academic Search

    Johannes Straub

    2005-01-01

    A short overview of boiling research in microgravity performed during the past two decades is subject of this presentation.\\u000a The research was concentrated on pool boiling without applying any external forces. The objective of this research was to\\u000a answer the questions: Is boiling an appropriate mechanism of heat transfer in space applications, and how do heat transfer\\u000a and bubble dynamics

  12. A study of forced convection boiling under reduced gravity

    NASA Technical Reports Server (NTRS)

    Merte, Herman, Jr.

    1992-01-01

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

  13. Analogue modeling of instabilities in crater lake hydrothermal systems

    Microsoft Academic Search

    Jean Vandemeulebrouck; Didier Stemmelen; Tony Hurst; Jacques Grangeon

    2005-01-01

    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

  14. Marangoni Effects in the Boiling of Binary Fluid Mixtures

    NASA Technical Reports Server (NTRS)

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

    1996-01-01

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

  15. Effective cooling of electronic components by boiling phase transition in microgravity

    NASA Astrophysics Data System (ADS)

    Straub, J.; Picker, G.; Winter, J.; Zell, M.

    1997-01-01

    Boiling heat transfer on a miniature heater has been studied under microgravity conditions during the IML 2 Space Shuttle Mission in 1994. These experiments are simulations for the application of the direct cooling of small electronic devices by boiling heat transfer in space. This becomes very important due to high thermal loads of modern electronic components. The results of this investigations are: Even at microgravity the heat transfer coefficients are very high and are even higher compared with other heater geometry. A remarkable influence of the gravity on the nucleate boiling heat transfer could not be observed, only in the transition and film boiling region a reduction up to 50 % was found. Several boiling modes have been observed during the experimental runs depending on the subcooling of the liquid, the liquid state, and the overall heat flux. Surface tension, wetting behavior, coalescence processes, the momentum of bubble formation, and thermocapillary convection play the most important role in boiling. The general statement can be made: boiling can be applied for cooling processes in microgravity.

  16. Experimental Two-Phase Flow Characterization of Subcooled Boiling in a Rectangular Channel

    E-print Network

    Estrada Perez, Carlos E.

    2010-01-16

    101 a100a105a27a101a114a45 a101a110a99a101 a40TH a45 T1a41a46 : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : a49a55 a54 a87a97a108a108 a116a101a109a112a101a114a97a116a117a114a101 a99a111a109a112a97a114a105a115a111a110 a102a111a114 a100a105...40TH T1a41 : : : : : : : : : : : : a53a50 a50a50 a87a97a108a108 a116a101a109a112a101a114a97a116a117a114a101 a99a111a109a112a97a114a105a115a111a110 a102a111a114 a100a105a27a101a114a101a110a116 a105a108a108a117a109a105a110a97a116a105a111a110 a99a97a115a...

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

    Microsoft Academic Search

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

    1995-01-01

    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\\/m², exit velocity range of 2.8--28.4 m\\/s, exit pressure range of 0.117--1.7 MPa, and inlet temperature

  18. Static-flow-instability in subcooled flow boiling in wide rectangular parallel channels

    Microsoft Academic Search

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

    1995-01-01

    The Advanced Neutron Source (ANS) is a state-of-the-art research reactor facility that will be built at the Oak Ridge National Laboratory (ORNL) and is designed to become the world`s most advanced thermal neutron flux source for scientific experiments. Therefore, the core of the ANS reactor (ANSR) must be designed to accommodate very high power densities using very high coolant mass

  19. Experimental Two-Phase Flow Characterization of Subcooled Boiling in a Rectangular Channel 

    E-print Network

    Estrada Perez, Carlos E.

    2010-01-16

    channel with one heated wall. Measurements were performed at liquid Reynolds numbers of 3309, 9929 and 16549 over a wall heat flux range of 0.0 to 64.0 kW=m2. From the PTV measurements, liquid two dimensional turbulence statistics are available, such as...

  20. Effects of ultrasonic vibration on subcooled pool boiling critical heat flux

    Microsoft Academic Search

    J. H. Jeong; Y. C. Kwon

    2006-01-01

    The effects of ultrasonic vibration on critical heat flux (CHF) have been experimentally investigated under natural convection condition. Flat bakelite plates coated with thin copper layer and distilled water are used as heated specimens and working fluid, respectively. Measurements of CHF on flat heated surface were made with and without ultrasonic vibration applied to working fluid. An inclination angle of

  1. Evaporation, Boiling and Bubbles

    ERIC Educational Resources Information Center

    Goodwin, Alan

    2012-01-01

    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…

  2. Boiling Time and Temperature

    NSDL National Science Digital Library

    Francis Eberle

    2007-01-01

    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.

  3. New methods of subcooled water recognition in dew point hygrometers

    NASA Astrophysics Data System (ADS)

    Weremczuk, Jerzy; Jachowicz, Ryszard

    2001-08-01

    Two new methods of sub-cooled water recognition in dew point hygrometers are presented in this paper. The first one- impedance method use a new semiconductor mirror in which the dew point detector, the thermometer and the heaters were integrated all together. The second one an optical method based on a multi-section optical detector is discussed in the report. Experimental results of both methods are shown. New types of dew pont hydrometers of ability to recognized sub-cooled water were proposed.

  4. International Boiling Point Project

    NSDL National Science Digital Library

    2009-01-01

    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?

  5. Consideration of sub-cooled LN2 circulation system for HTS power machines

    NASA Astrophysics Data System (ADS)

    Yoshida, Shigeru; Hirai, Hirokazu; Nara, N.; Nagasaka, T.; Hirokawa, M.; Okamoto, H.; Hayashi, H.; Shiohara, Y.

    2012-06-01

    We consider a sub-cooled liquid nitrogen (LN) circulation system for HTS power equipment. The planned circulation system consists of a sub-cool heat exchanger (subcooler) and a circulation pump. The sub-cooler will be connected to a neon turbo- Brayton cycle refrigerator with a cooling power of 2 kW at 65 K. Sub-cooled LN will be delivered into the sub-cooler by the pump and cooled within it. Sub-cooled LN is adequate fluid for cooling HTS power equipment, because its dielectric strength is high and it supports a large critical current. However, a possibility of LN solidification in the sub-cooler is a considerable issue. The refrigerator will produce cold neon gas of about 60 K, which is lower than the nitrogen freezing temperature of 63 K. Therefore, we designed two-stage heat exchangers which are based on a plate-fin type and a tube-intube type. Process simulations of those heat exchangers indicate that sub-cooled LN is not frozen in either sub-cooler. The plate-fin type sub-cooler is consequently adopted for its reliability and compactness. Furthermore, we found that a cooling system with a Brayton refrigerator has the same total cooling efficiency as a cooling system with a Stirling refrigerator.

  6. Enhancement of Nucleate Boiling Heat Flux on Macro/Micro-Structured Surfaces Cooled by Multiple Impinging Jets

    NASA Technical Reports Server (NTRS)

    Kugler, Scott Lee

    1997-01-01

    An experimental investigation of nucleate boiling heat transfer from modified surfaces cooled by multiple in-line impinging circular jets is reported and found to agree with single jet results. A copper block is heated from the back by two electrical arcs, and cooled on the opposite side by three identical liquid jets of distilled water at subcoolings of 25 C 50 C and 77 C and Freon 113 at 24 C subcooling. Liquid flow rates are held constant at 5, 10, and 15 GPH for each of the three jets with jet velocities ranging from 1.4 m/s to 1 1.2 m/s and jet diameters from 0.95 mm to 2.2 mm. To increase the maximum heat flux (CHF) and heat removal rate, the boiling surface was modified by both macro and micro enhancements. Macro modification consists of machined radial grooves in the boiling surface arranged in an optimally designed pattern to allow better liquid distribution along the surface. These grooves also reduce splashing of liquid droplets, and provide 'channels' to sweep away bubbles. Micro modification was achieved by flame spraying metal powder on the boiling surface, creating a porous, sintered surface. With the addition of both micro and macro structured enhancements, maximum heat flux and nucleate boiling can be enhanced by more than 200%. Examination of each surface modification separately and together indicates that at lower superheats, the micro structure provides the enhanced heat transfer by providing more nucleation sites, while for higher superheats the macro structure allows better liquid distribution and bubble removal. A correlation is presented to account for liquid subcoolings and surface enhancements, in addition to the geometrical and fluid properties previously reported in the literature.

  7. Nucleate pool boiling in the long duration low gravity environment of the space shuttle

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

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

  9. Enhanced Natural Convection in a Metal Layer Cooled by Boiling Water

    SciTech Connect

    Cho, Jae-Seon [Seoul National University (Korea, Republic of); Suh, Kune Y. [Seoul National University (Korea, Republic of); Chung, Chang-Hyun [Seoul National University (Korea, Republic of); Park, Rae-Joon [Korea Atomic Energy Research Institute (Korea, Republic of); Kim, Sang-Baik [Korea Atomic Energy Research Institute (Korea, Republic of)

    2004-12-15

    An experimental study is performed to investigate the natural convection heat transfer characteristics and the solidification of the molten metal pool concurrently with forced convective boiling of the overlying coolant to simulate a severe accident in a nuclear power plant. The relationship between the Nusselt number (Nu) and the Rayleigh number (Ra) in the molten metal pool region is determined and compared with the correlations in the literature and experimental data with subcooled water. Given the same Ra condition, the present experimental results for Nu of the liquid metal pool with coolant boiling are found to be higher than those predicted by the existing correlations or measured from the experiment with subcooled boiling. To quantify the observed effect of the external cooling on the natural convection heat transfer rate from the molten pool, it is proposed to include an additional dimensionless group characterizing the temperature gradients in the molten pool and in the external coolant region. Starting from the Globe and Dropkin correlation, engineering correlations are developed for the enhancement of heat transfer in the molten metal pool when cooled by an overlying coolant. The new correlations for predicting natural convection heat transfer are applicable to low-Prandtl-number (Pr) materials that are heated from below and solidified by the external coolant above. Results from this study may be used to modify the current model in severe accident analysis codes.

  10. Model for boiling and dryout in particle beds. [LMFBR

    SciTech Connect

    Lipinski, R. J.

    1982-06-01

    Over the last ten years experiments and modeling of dryout in particle beds have produced over fifty papers. Considering only volume-heated beds, over 250 dryout measurements have been made, and are listed in this work. In addition, fifteen models to predict dryout have been produced and are discussed. A model is developed in this report for one-dimensional boiling and dryout in a porous medium. It is based on conservation laws for mass, momentum, and energy. The initial coupled differential equations are reduced to a single first-order differential equation with an algebraic equation for the upper boundary condition. The model includes the effects of both laminar and turbulent flow, two-phase friction, and capillary force. The boundary condition at the bed bottom includes the possibility of inflowing liquid and either an adiabatic or a bottom-cooled support structure. The top of the bed may be either channeled or subcooled. In the first case the channel length and the saturation at the base of the channels are predicted. In the latter case, a criterion for penetration of the subcooled zone by channels is obtained.

  11. Flow boiling of water on nanocoated surfaces in a microchannel

    E-print Network

    Phan, Hai Trieu; Marty, Philippe; Colasson, Stéphane; Gavillet, Jérôme

    2010-01-01

    Experiments were performed to study the effects of surface wettability on flow boiling of water at atmospheric pressure. The test channel is a single rectangular channel 0.5 mm high, 5 mm wide and 180 mm long. The mass flux was set at 100 kg/m2 s and the base heat flux varied from 30 to 80 kW/m2. Water enters the test channel under subcooled conditions. The samples are silicone oxide (SiOx), titanium (Ti), diamond-like carbon (DLC) and carbon-doped silicon oxide (SiOC) surfaces with static contact angles of 26{\\deg}, 49{\\deg}, 63{\\deg} and 103{\\deg}, respectively. The results show significant impacts of surface wettability on heat transfer coefficient.

  12. Boiling inception in trichlorotrifluoroethane during forced convection at high pressures

    NASA Technical Reports Server (NTRS)

    Dougall, R. S.; Lippert, T. E.

    1972-01-01

    The inception of bubbles during forced convection was studied experimentally by using trichlorotrifluoroethane (R-113 or Freon-113). The experiments were performed in a rectangular channel, 12.7 x 9.5 mm in cross section. Heating was from a 3.2 mm wide strip embedded in the longer side of the channel. The pressures studied ranged from 3.6 to 20.7 bar, mass velocities from 700 to 600 kg/sq m/sec, and inlet subcoolings from 26 to 97 C. Photographs of the flow were used to determine when bubbles first appeared on the heated surface. These data were compared with wall temperature measurements and inception theories. A reasonable method for calculating the complete boiling curve was found to agree with these results.

  13. Sulfur speciation in natural hydrothermal waters, Iceland

    Microsoft Academic Search

    Hanna Kaasalainen; Andri Stefánsson

    2011-01-01

    The speciation of aqueous dissolved sulfur was determined in hydrothermal waters in Iceland. The waters sampled included hot springs, acid-sulfate pools and mud pots, sub-boiling well discharges and two-phase wells. The water temperatures ranged from 4 to 210°C, the pHT was between 2.20 and 9.30 at the discharge temperature and the SO4 and Cl concentrations were 0.020–52.7 and <0.01–10.0mmolkg?1, respectively.

  14. Momentum effects in steady nucleate pool boiling during microgravity.

    PubMed

    Merte, Herman

    2004-11-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

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

  16. Pool film boiling from rotating and stationary spheres in liquid nitrogen

    NASA Astrophysics Data System (ADS)

    Cuan, Winston M.; Schwartz, Sidney H.

    1988-07-01

    Results are presented for a preliminary experiment involving a saturated pool boiling at 1 atm from rotating 2 and 3 inch diameter spheres which were immersed in LN2. Additional results are presented for a stationary 2 inch diameter sphere quenched in LN2, which were obtained with a more versatile and complete experimental apparatus. The speed of the rotational tests varied from 0 to 10,000 rpm. The stationary experiments parametrically varied pressure and subcooling levels from 0 to 600 psig and from 0 to 50 F, respectively. During the rotational tests, a high speed photographic analysis was undertaken to measure the thickness of the vapor film surrounding the sphere.

  17. Condensing phenomena of a single vapor bubble into subcooled water

    SciTech Connect

    Kamei, S. (Dept. of Mechanical Engineering, Univ. of Tokyo, Tokyo (JP)); Hirata, M. (Research Center for Advanced Science and Technology, Univ. of Tokyo, Tokyo (JP))

    1990-01-01

    This paper reports on experiments carried out to investigated direct contact condensation of saturated vapor bubbles introduced into a quiescent subcooled water environment. The experiments were performed for a range of pressures from atmospheric to 1 MPa, for subcooling from 10 to 70 K, and for initial bubble diameters of about 10 mm. Flow visualization by high-speed motion pictures was based on a frame-by-frame analysis. The authors show that the successive shapes of the bubbles during their collapse histories proceeded from a sphere to a hemisphere, to an ellipsoid, to a sphere, and finally to collapse. They show that the cavities of the bubbles during their collapse histories proceeded from the bottom to the top. The time to collapse increased with increasing pressure difference. The rising velocities of the bubbles were essentially constant, with an overall range of 20--25 cm/s.

  18. SATURATED-SUBCOOLED STRATIFIED FLOW IN HORIZONTAL PIPES

    SciTech Connect

    Richard Schultz

    2010-08-01

    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.

  19. Design and rating of an integrated mechanical-subcooling vapor-compression refrigeration system

    Microsoft Academic Search

    Jameel-ur-Rehman Khan; Syed M. Zubair

    2000-01-01

    Subcooling of the refrigerant at the exit of the condenser in a simple vapor-compression refrigeration system allows the refrigerant to enter the main cycle evaporator with low quality. Thus, allowing the refrigerant to absorb more heat in the evaporator; thereby improving the coefficient of performance (COP) of the system. In an integrated mechanical-subcooling vapor-compression refrigeration system, the subcooling is performed

  20. Super eruption environments make for "super" hydrothermal explosions: Extreme hydrothermal explosions in Yellowstone National Park

    NASA Astrophysics Data System (ADS)

    Morgan, L. A.; Shanks, W. P.; Pierce, K. L.

    2006-12-01

    Hydrothermal explosions are violent events resulting in the rapid ejection of boiling water, steam, mud, and rock fragments over areas that range from a few meters in diameter up to several kilometers in diameter. Hydrothermal explosions occur where shallow interconnected reservoirs of steam-saturated fluids underlie thermal fields. Sudden reduction in pressure causes the fluids to flash to steam resulting in significant expansion, rock fragmentation, and debris ejection. In Yellowstone, at least 20 large (>100 meters in diameter) hydrothermal explosions have been identified, and the scale of the individual events dwarfs similar features in other hydrothermal and geothermal areas of the world. Large explosions in Yellowstone have occurred over the past 16 ka at an interval of ~1 per every 700 yrs and similar events are likely to occur in the future. Our studies of hydrothermal explosive events indicate: 1) none are associated with magmatic or volcanic events; 2) several have been triggered by seismic events coupled with other processes; 3) lithic clasts and matrix from explosion deposits are extensively altered, indicating long-term, extensive hydrothermal mineralization in areas that were incorporated into the explosion deposit; 4) many lithic clasts in explosion breccia deposits contain evidence of repeated fracturing and cementation; and 4) dimensions of many documented large hydrothermal explosion craters in Yellowstone are similar to the dimensions of currently active geyser basins or thermal areas in Yellowstone. The vast majority of active thermal areas in Yellowstone are characterized by 1) high-temperature hot-water systems in areas of high heat-flow, 2) extensive systems of hot springs, fumaroles, geysers, sinter terraces, mud pots, and, in places, small hydrothermal explosion craters, 3) widespread alteration of host rocks, 4) large areal dimensions (>several 100 m) and 5) intermittent but long-lived activity (40,000 to 300,000 years). Critical requirements for large hydrothermal explosions are an interconnected system of well-developed joints and fractures along which hydrothermal fluids flow and a water-saturated system close to or at boiling temperatures. Important factors are the active deformation of the Yellowstone caldera, active faults and moderate seismicity, high heat flow, climate changes, and regional stresses. Ascending fluids flow along fractures that develop in response to active deformation of the Yellowstone caldera and along edges of impermeable rhyolitic lava flows. Alteration, self sealing, and dissolution further constrain the distribution and development of hydrothermal fields. A partial impermeable cap can contribute to the final over-pressurization. An abrupt drop in pressure initiates steam-flashing and is instantly transmitted through interconnected fractures, resulting in a series of multiple large-scale explosions and excavation of an explosion crater. Strong similarities between large hydrothermal explosion craters and thermal fields in Yellowstone may indicate that catastrophic failures leading to large hydrothermal explosions represent a unique phase in the life cycle of a geyser basin.

  1. An investigation into the influence of different parameters on the onset of boiling in minichannels

    NASA Astrophysics Data System (ADS)

    Piasecka, Magdalena

    2011-11-01

    The paper presents experimental studies on boiling heat transfer in rectangular minichannels. The investigations focus on the transition from single phase forced convection to nucleate boiling, i.e., in the zone of boiling incipience. The experiment has been carried out with FC-72, R-123 and R-11 at the Reynolds number below 4700, corresponding to mass flow rate range 95-710 kg/(m s). The main part of the test section is a minichannel of pre-set depth from 0.7 to 2 mm and width (20, 40 and 60 mm), with different spatial orientations from vertical to horizontal and 30% inclination angle adjustment. The objective of the paper includes the impact of selected parameters (liquid flow velocity, pressure and inlet liquid subcooling, channel dimensions and spatial orientation) on the boiling incipience in minichannels. The investigations are intended to develop a correlation for the calculations of the Nusselt number under the conditions of boiling incipience in the minichannel as a function of changeable parameters.

  2. An investigation into the influence of different parameters on the onset of boiling in minichannels

    NASA Astrophysics Data System (ADS)

    Piasecka, Magdalena

    2013-02-01

    The paper presents experimental studies on boiling heat transfer in rectangular minichannels. The investigations focus on the transition from single phase forced convection to nucleate boiling, i.e., in the zone of boiling incipience. The experiment has been carried out with FC-72, R-123 and R-11 at the Reynolds number below 4700, corresponding to mass flow rate range 95-710 kg/(m s). The main part of the test section is a minichannel of pre-set depth from 0.7 to 2 mm and width (20, 40 and 60 mm), with different spatial orientations from vertical to horizontal and 30% inclination angle adjustment. The objective of the paper includes the impact of selected parameters (liquid flow velocity, pressure and inlet liquid subcooling, channel dimensions and spatial orientation) on the boiling incipience in minichannels. The investigations are intended to develop a correlation for the calculations of the Nusselt number under the conditions of boiling incipience in the minichannel as a function of changeable parameters.

  3. Using noble gases measured in spring discharge to trace hydrothermal processes in the Norris Geyser Basin, Yellowstone National Park, U.S.A.

    USGS Publications Warehouse

    Gardner, W.P.; Susong, D.D.; Solomon, D.K.; Heasler, H.P.

    2010-01-01

    Dissolved noble gas concentrations in springs are used to investigate boiling of hydrothermal water and mixing of hydrothermal and shallow cool water in the Norris Geyser Basin area. Noble gas concentrations in water are modeled for single stage and continuous steam removal. Limitations on boiling using noble gas concentrations are then used to estimate the isotopic effect of boiling on hydrothermal water, allowing the isotopic composition of the parent hydrothermal water to be determined from that measured in spring. In neutral chloride springs of the Norris Geyser Basin, steam loss since the last addition of noble gas charged water is less than 30% of the total hydrothermal discharge, which results in an isotopic shift due to boiling of ?? 2.5% ??D. Noble gas concentrations in water rapidly and predictably change in dual phase systems, making them invaluable tracers of gas-liquid interaction in hydrothermal systems. By combining traditional tracers of hydrothermal flow such as deuterium with dissolved noble gas measurements, more complex hydrothermal processes can be interpreted. ?? 2010 Elsevier B.V.

  4. Applications of Artificial Neural Network for the Prediction of Pool Boiling Curves

    SciTech Connect

    Su, Guanghui; Fukuda, K.; Morita, K. [Kyushu University, 6-10-1, Hakozaki, Higashi-ku, Fukuoka 812-81 (Japan)

    2002-07-01

    Artificial neural network (ANN) has the advantage that the best-fit correlations of experimental data will no longer be necessary for predicting unknowns from the known parameters. The ANN was applied to predict the pool boiling curves in this paper. The database of experimental data presented by Berenson, Dhuga et al., and Bui and Dhir etc. were used in the analysis. The database is subdivided in two subsets. The first subset is used to train the network and the second one is used to test the network after the training process. The input parameters of the ANN are: wall superheat {delta}T{sub w}, surface roughness, steady/transient heating/transient cooling, subcooling, Surface inclination and pressure. The output parameter is heat flux q. The proposed methodology allows us to achieve the accuracy that satisfies the user's convergence criterion and it is suitable for pool boiling curve data processing. (authors)

  5. Boiling on free-falling spheres; Drag and heat transfer coefficients

    SciTech Connect

    Zvirin, Y. (Technion-Israel Inst. of Tech., Haifa (Israel). Dept. of Mechanical Engineering); Hewitt, G.F. (Imperial Coll. of Science and Technology, London (UK). Dept. of Chemical Engineering and Chemical Technology); Kenning, D.B.R. (Oxford Univ. (UK). Dept. of Engineering Science)

    1990-01-01

    Experiments have been conducted to measure drag (c{sub D}) and heat transfer coefficients (h) and to study the boiling nature on heated spheres free-falling in saturated and subcooled water. Simultaneous measurements of the transient sphere velocity and temperature during the fall enabled calculation of c{sub D}, heat fluxes, and h values. It has been found that the drag decreases with the initial sphere temperature, T{sub 0}. The measured results, as well as still and motion photography, show that at T{sub 0} {gt} 450{degrees}C film boiling prevails, with low heat fluxes at the beginning of the transient. In some cases the film collapses, leading to a transition to disturbed-film and micro-bubble regimes, associated with larger heat fluxes and also solid-liquid interactions, with lateral motion of the sphere (shoot-off).

  6. Investigations of Mechanisms Associated with Nucleate Boiling Under Microgravity Conditions

    NASA Technical Reports Server (NTRS)

    Dhir, Vijay K.; Hasan, M.; Chao, David (Technical Monitor)

    2003-01-01

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

  7. Design inputs document: Boiling behavior during flow instability

    SciTech Connect

    Coutts, D.A.

    1991-12-31

    The coolant flow in a nuclear reactor core under normal operating conditions is kept as a subcooled liquid. This coolant is evenly distributed throughout the multiple flow channels with a uniform pressure profile across each coolant flow channel. If the coolant flow is reduced, the flow through individual channels will also decrease. A decrease in coolant flow will result in higher coolant temperatures if the heat flux is not reduced. When flow is significantly decreased, localized boiling may occur. This localized boiling can restrict coolant flow and the ability to transfer heat out of the reactor system. The maximum operating power for the reactor may be limited by how the coolant system reacts to a flow instability. One of the methods to assure safe operation during a reducing flow instability, is to operate at a power level below that necessary to initiate a flow excursion. Several correlations have been used to predict the conditions which precede a flow excursion. These correlations rely on the steady state behavior of the coolant and are based on steady state testing. This task will evaluate if there are any deviations between the actual transient flow excursion behavior and the flow excursion behavior based on steady state correlations (ONB, OSV, and CHF). Correlations will be developed which will allow a comparison between the time to excursive behavior predicted using steady state techniques and the actual time to excursive behavior.

  8. Design inputs document: Boiling behavior during flow instability

    SciTech Connect

    Coutts, D.A.

    1991-01-01

    The coolant flow in a nuclear reactor core under normal operating conditions is kept as a subcooled liquid. This coolant is evenly distributed throughout the multiple flow channels with a uniform pressure profile across each coolant flow channel. If the coolant flow is reduced, the flow through individual channels will also decrease. A decrease in coolant flow will result in higher coolant temperatures if the heat flux is not reduced. When flow is significantly decreased, localized boiling may occur. This localized boiling can restrict coolant flow and the ability to transfer heat out of the reactor system. The maximum operating power for the reactor may be limited by how the coolant system reacts to a flow instability. One of the methods to assure safe operation during a reducing flow instability, is to operate at a power level below that necessary to initiate a flow excursion. Several correlations have been used to predict the conditions which precede a flow excursion. These correlations rely on the steady state behavior of the coolant and are based on steady state testing. This task will evaluate if there are any deviations between the actual transient flow excursion behavior and the flow excursion behavior based on steady state correlations (ONB, OSV, and CHF). Correlations will be developed which will allow a comparison between the time to excursive behavior predicted using steady state techniques and the actual time to excursive behavior.

  9. Liquid metal boiling inception

    NASA Technical Reports Server (NTRS)

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

    1972-01-01

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

  10. Destabilization of film boiling

    Microsoft Academic Search

    S. G. Bankoff

    1980-01-01

    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

  11. Sub-cooled liquid nitrogen cryogenic system with neon turbo-refrigerator for HTS power equipment

    NASA Astrophysics Data System (ADS)

    Yoshida, S.; Hirai, H.; Nara, N.; Ozaki, S.; Hirokawa, M.; Eguchi, T.; Hayashi, H.; Iwakuma, M.; Shiohara, Y.

    2014-01-01

    We developed a prototype sub-cooled liquid nitrogen (LN) circulation system for HTS power equipment. The system consists of a neon turbo-Brayton refrigerator with a LN sub-cooler and LN circulation pump unit. The neon refrigerator has more than 2 kW cooling power at 65 K. The LN sub-cooler is a plate-fin type heat exchanger and is installed in a refrigerator cold box. In order to carry out the system performance tests, a dummy cryostat having an electric heater was set instead of a HTS power equipment. Sub-cooled LN is delivered into the sub-cooler by the LN circulation pump and cooled within it. After the sub-cooler, sub-cooled LN goes out from the cold box to the dummy cryostat, and comes back to the pump unit. The system can control an outlet sub-cooled LN temperature by adjusting refrigerator cooling power. The refrigerator cooling power is automatically controlled by the turbo-compressor rotational speed. In the performance tests, we increased an electric heater power from 200 W to 1300 W abruptly. We confirmed the temperature fluctuation was about ±1 K. We show the cryogenic system details and performance test results in this paper.

  12. Melting and resolidification of a subcooled metal powder particle subjected to nanosecond laser heating

    E-print Network

    Zhang, Yuwen

    of a subcooled spherical metal powder particle subjected to nanosecond laser heating are investigatedMelting and resolidification of a subcooled metal powder particle subjected to nanosecond laser heating Chad Konrad 1 , Yuwen Zhang *, Yu Shi Department of Mechanical and Aerospace Engineering

  13. Performance of extended surface from a cryocooler for subcooling liquid nitrogen by natural convection

    E-print Network

    Chang, Ho-Myung

    convection Yeon Suk Choi a,b , Ho-Myung Chang a,*, Steven W. Van Sciver b a Department of Mechanical May 2005; accepted 25 May 2005 Abstract Natural convection of subcooled liquid nitrogen under that subcooled liquid may generate cellular flow by natural convection. The temperature distributions

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

    SciTech Connect

    Amos, C N; Schrock, V E

    1983-09-01

    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.

  15. Hydrothermal Energy Conversion Technology

    Microsoft Academic Search

    David W. Robertson; Raymond J. LaSala

    1992-01-01

    The goal of the Hydrothermal Program is to develop concepts which allow better utilization of geothermal energy to reduce the life-cycle cost of producing electricity from liquid-dominated, hydrothermal resources. Research in the program is currently ongoing in three areas: (1) Heat Cycle Research, which is looking at methods to increase binary plant efficiencies; (2) Materials Development, which is developing materials

  16. A new hydrothermal scenario for the 2006 Lusi eruption, Indonesia. Insights from gas geochemistry

    E-print Network

    Mazzini, Adriano

    A new hydrothermal scenario for the 2006 Lusi eruption, Indonesia. Insights from gas geochemistry of May 2006 gas and mud eruptions suddenly appeared along the Watukosek fault in the north east of Java, Indonesia. Within a few weeks several villages were submerged by boiling mud. The most prominent eruption

  17. Sedimentation and convective boiling heat transfer of CuO-water/ethylene glycol nanofluids

    NASA Astrophysics Data System (ADS)

    Sarafraz, M. M.; Hormozi, F.; Kamalgharibi, M.

    2014-09-01

    The convective boiling characteristics of dilute dispersions of CuO nanoparticles in water/ethylene glycol as a base fluid were studied at different operating conditions of (heat fluxes up to 174 kW m-2, mass fluxes range of 353-1,059 kg m-2 s-1 and sub-cooling level of 343, 353 and 363 K) inside the annular duct. The convective boiling heat transfer coefficients of nanofluids in different concentrations (vol%) of nanoparticles (0.5, 1, and 1.5) were also experimentally quantified. Results demonstrated the significant augmentation of heat transfer coefficient inside the region with forced convection dominant mechanism and deterioration of heat transfer coefficient in region with nucleate boiling dominant heat transfer mechanism. Due to the scale formation around the heating section, fouling resistance was also experimentally measured. Experimental data showed that with increasing the heat and mass fluxes, the heat transfer coefficient and fouling resistance dramatically increase and rate of bubble formation clearly increases. Obtained results were then compared to some well-known correlations. Results of these comparisons demonstrated that experimental results represent the good agreement with those of obtained by the correlations. Consequently, Chen correlation is recommended for estimating the convective flow boiling heat transfer coefficient of dilute CuO-water/ethylene glycol based nanofluids.

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

    NASA Technical Reports Server (NTRS)

    Ling, Jerri S.; Laubenthal, James R.

    1990-01-01

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

  19. Liquid Acquisition Device Testing with Sub-Cooled Liquid Oxygen

    NASA Technical Reports Server (NTRS)

    Jurns, John M.; McQuillen, John B.

    2008-01-01

    When transferring propellant in space, it is most efficient to transfer single phase liquid from a propellant tank to an engine. In earth s gravity field or under acceleration, propellant transfer is fairly simple. However, in low gravity, withdrawing single-phase fluid becomes a challenge. A variety of propellant management devices (PMD) are used to ensure single-phase flow. One type of PMD, a liquid acquisition device (LAD) takes advantage of capillary flow and surface tension to acquire liquid. Previous experimental test programs conducted at NASA have collected LAD data for a number of cryogenic fluids, including: liquid nitrogen (LN2), liquid oxygen (LOX), liquid hydrogen (LH2), and liquid methane (LCH4). The present work reports on additional testing with sub-cooled LOX as part of NASA s continuing cryogenic LAD development program. Test results extend the range of LOX fluid conditions examined, and provide insight into factors affecting predicting LAD bubble point pressures.

  20. When water does not boil at the boiling point.

    PubMed

    Chang, Hasok

    2007-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2008-06-01

    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 were identified. The fluid chemistry of the typical Cl-enriched and Cl-depleted hydrothermal fluids was analyzed, as was the mineralogy of the host chimney structures. The variability in the fluid chemistry was potentially controlled by the subseafloor phase-separation (vapor loss process) and the microbial community activities. Microbial community structures in three chimney structures were investigated using culture-dependent and -independent techniques. The small subunit (SSU) rRNA gene clone analysis revealed that both bacterial and archaeal rRNA gene communities on the chimney surfaces differed among three chimneys. Cultivation analysis demonstrated significant variation in the culturability of various microbial components among the chimneys, particularly of thermophilic H2-oxidizing (and S-oxidizing) chemolithoautotrophs such as the genera Aquifex and Persephonella. The physical and chemical environments of chimney surface habitats are still unresolved and do not directly extrapolate the environments of possible subseafloor habitats. However, the variability in microbial community found in the chimneys also provides an insight into the different biogeochemical interactions potentially affected by the phase separation of the hydrothermal fluids in the subseafloor hydrothermal habitats. In addition, comparison with other deep-sea hydrothermal systems revealed that the Mariner field microbial communities have unusual characteristics.

  2. Film boiling of mercury droplets

    NASA Technical Reports Server (NTRS)

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

    1975-01-01

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

  3. Boiling Radial Flow in Fractures of Varying

    E-print Network

    Stanford University

    apply only to a finite radius around the point of injection, higher values of heat flux and a boilingSGP-TR-166 Boiling Radial Flow in Fractures of Varying Wall Porosity Robb Allan Barnitt June 2000 and boiling convective heat transfer, with boiling flow in a rock fracture. A series of experiments observed

  4. Multi-Scale Experiments in Turbulent Subcooled Boiling Flow Through a Square Channel with a Single Heated Wall

    E-print Network

    Estrada Perez, Carlos Eduardo

    2014-12-12

    .39 Variation of the fluorescence intensity dependent on temperature. . . 78 3.40 Ratio between two CCD camera’s output against temperature. . . . . 79 3.41 LIF analysis on density stratification (a) without correction, (b) with normalization correction.... . . . . . . . . . . . . 123 7.1 Liquid and bubbles velocity fields and profiles. . . . . . . . . . . . . . 125 7.2 Void residence time and velocity profiles. . . . . . . . . . . . . . . . . 127 7.3 Front view shadowgraphy experimental image from camera 2 at a resolution...

  5. Critical heat flux multiplier of subcooled flow boiling for non-uniform heating conditions in a swirl tube

    Microsoft Academic Search

    Fujio Inasaka; Hideki Nariai

    1995-01-01

    In this paper, two factors were proposed to examine the relation between the critical heat flux (CHF) enhancement in swirl tubes and the intensity of non-uniformity under non-uniform heating conditions. One is a CHF multiplier ? defined as a ratio of the peak heat flux at the CHF (qc,H) under non-uniform heating conditions to the CHF under uniform heating conditions.

  6. F-LE Boiling Water

    NSDL National Science Digital Library

    2013-10-30

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

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

    NASA Astrophysics Data System (ADS)

    Agaltsov, Andrey; Fedoseenko, Ivan

    2012-04-01

    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.

  8. Forced Convection Boiling and Critical Heat Flux of Ethanol in Electrically Heated Tube Tests

    NASA Technical Reports Server (NTRS)

    Meyer, Michael L.; Linne, Diane L.; Rousar, Donald C.

    1998-01-01

    Electrically heated tube tests were conducted to characterize the critical heat flux (transition from nucleate to film boiling) of subcritical ethanol flowing at conditions relevant to the design of a regeneratively cooled rocket engine thrust chamber. The coolant was SDA-3C alcohol (95% ethyl alcohol, 5% isopropyl alcohol by weight), and tests were conducted over the following ranges of conditions: pressure from 144 to 703 psia, flow velocities from 9.7 to 77 ft/s, coolant subcooling from 33 to 362 F, and critical heat fluxes up to 8.7 BTU/in(exp 2)/sec. For the data taken near 200 psia, critical heat flux was correlated as a function of the product of velocity and fluid subcooling to within +/- 20%. For data taken at higher pressures, an additional pressure term is needed to correlate the critical heat flux. It was also shown that at the higher test pressures and/or flow rates, exceeding the critical heat flux did not result in wall burnout. This result may significantly increase the engine heat flux design envelope for higher pressure conditions.

  9. Microgravity experiments on boiling and applications: research activity of advanced high heat flux cooling technology for electronic devices in Japan.

    PubMed

    Suzuki, Koichi; Kawamura, Hiroshi

    2004-11-01

    Research and development on advanced high heat flux cooling technology for electronic devices has been carried out as the Project of Fundamental Technology Development for Energy Conservation, promoted by the New Energy and Industrial Technology Development Organization of Japan (NEDO). Based on the microgravity experiments on boiling heat transfer, the following useful results have obtained for the cooling of electronic devices. In subcooled flow boiling in a small channel, heat flux increases considerably more than the ordinary critical heat flux with microbubble emission in transition boiling, and dry out of the heating surface is disturbed. Successful enhancement of heat transfer is achieved by a capillary effect from grooved surface dual subchannels on the liquid supply. The critical heat flux increases 30-40 percent more than for ordinary subchannels. A self-wetting mechanism has been proposed, following investigation of bubble behavior in pool boiling of binary mixtures under microgravity. Ideas and a new concept have been proposed for the design of future cooling system in power electronics. PMID:15644356

  10. Summary Results of the Neptun Boil-Off Experiments to Investigate the Accuracy and Cooling Influence of LOFT Cladding-Surface Thermocouples (System 00)

    SciTech Connect

    E. L. Tolman; S. N. Aksan

    1981-10-01

    Nine boil-off experiments were conducted in the Swiss NEPTUN Facility primarily to obtain experimental data for assessing the perturbation effects of LOFT thermocouples during simulated small-break core uncovery conditions. The data will also be useful in assessing computer model capability to predict thermal hydraulic response data for this type of experiment. System parameters that were varied for these experiments included heater rod power, system pressure, and initial coolant subcooling. The experiments showed that the LOFT thermocouples do not cause a significant cooling influence in the rods to which they are attached. Furthermore, the accuracy of the LOFT thermocouples is within 20 K at the peak cladding temperature zone.

  11. Implementation of the interfacial area transport equation in trace for boiling two-phase flows

    NASA Astrophysics Data System (ADS)

    Bernard, Matthew S.

    Correctly predicting the interfacial area concentration (a i) is vital to the overall accuracy of the two-fluid model because ai describes the amount of surface area that exists between the two-phases, and is therefore directly related to interfacial mass, momentum and energy transfer. The conventional method for specifying ai in the two-fluid model is through flow regime-based empirical correlations coupled with regime transition criteria. However, a more physically consistent approach to predicting ai is through the interfacial area transport equation (IATE), which can address the deficiencies of the flow regime-based approach. Some previous studies have been performed to demonstrate the feasibility of IATE in developmental versions of the nuclear reactor systems analysis code, TRACE. However, a full TRACE version capable of predicting boiling two-phase flows with the IATE has not been established. Therefore, the current work develops a version of TRACE that is capable of predicting boiling two-phase flows using the IATE. The development is carried out in stages. First, a version of TRACE which employs the two-group IATE for adiabatic, vertical upward, air-water conditions is developed. An in-depth assessment on the existing experimental database is performed to select reliable experimental data for code assessment. Then, the implementation is assessed against the qualified air-water two-phase flow experimental data. Good agreement is observed between the experimental data for ai and the TRACE code with an average error of +/-9% for all conditions. Following the initial development, one-group IATE models for vertical downward and horizontal two-phase flows are implemented and assessed against qualified data. Finally, IATE models capable of predicting subcooled boiling two-phase flows are implemented. An assessment of the models shows that TRACE is capable of generating ai in subcooled boiling two-phase flows with the IATE and that heat transfer effects dominate the evolution of ai in these flows. In parallel to developing a TRACE version with the IATE capability, an extensive study is performed to improve the capabilities of the four-sensor conductivity probe. These include improvements in both the signal processing software and processing schemes. Furthermore, experiments are performed in 14 additional test conditions. These test conditions are strategically chosen to establish database in flow conditions where specific bubble interaction mechanisms in the IATE are highlighted. The data established in the experiments are used to further assess and validate the IATE models available in TRACE.

  12. Transition from Pool to Flow Boiling: The Effect of Reduced Gravity

    NASA Technical Reports Server (NTRS)

    Dhir, Vijay K.

    2004-01-01

    Applications of boiling heat transfer in space can be found in the areas of thermal management, fluid handling and control, power systems, on-orbit storage and supply systems for cryogenic propellants and life support fluids, and for cooling of electronic packages for power systems associated with various instrumentation and control systems. Recent interest in exploration of Mars and other planets, and the concepts of in-situ resource utiliLation on Mars highlights the need to understand the effect of gravity on boiling heat transfer at gravity levels varying from 1>= g/g(sub e) >=10(exp -6). The objective of the proposed work was to develop a mechanistic understanding of nucleate boiling and critical heat flux under low and micro-gravity conditions when the velocity of the imposed flow is small. For pool boiling, the effect of reduced gravity is to stretch both the length scale as well as the time scale for the boiling process. At high flow velocities, the inertia of the liquid determines the time and the length scales and as such the gravitational acceleration plays little role. However, at low velocities and at low gravity levels both liquid inertia and buoyancy are of equal importance. At present, we have little understanding of the interacting roles of gravity and liquid inertia on the nucleate boiling process. Little data that has been reported in the literature does not have much practical value in that it can not serve as a basis for design of heat exchange components to be used in space. Both experimental and complete numerical simulations of the low velocity, low-gravity nucleate boiling process were carried out. A building block type of approach was used in that first the growth and detachment process of a single bubble and flow and heat transfer associated with the sliding motion of the bubble over the heater surface after detachment was studied. Liquid subcooling and flow velocity were varied parametrically. The experiments were conducted at 1 g(sub e), while varying the orientation of surface with respect to the gravity vector. In the laboratory experiments, holographic interferometry was used to obtain data on velocity and temperature fields associated with a bubble prior to, and after detachment and during sliding motion. A test rig for conducting experiments in the KC-135 was developed, but experiments could not be conducted due to the unavailability of the aircraft prior to completion of the project. Numerical simulations modeling the micro and macro regions of the bubble were carried out in three dimensions. The results of the experiments were used to validate analytical/numerical models.

  13. Characteristics of Transient Boiling Heat Transfer

    SciTech Connect

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

    2002-07-01

    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)

  14. Suppression of bubbles in subcooled liquid nitrogen under heat impulse Kwanwoo Nam a,*, Bok-Yeol Seok a

    E-print Network

    Chang, Ho-Myung

    between 77 K and 65 K. Two kinds of experiments are performed to scrutinize the thermal behavior of liquid is that the generation of bubbles is less active in subcooled state than in saturated state. The subcooling of liquid or exter- nal heat load. Since bubbles play a critical role in the degra- dation of electrical insulation

  15. Orientation and related buoyancy effects in low-velocity flow boiling.

    PubMed

    Merte, Herman; Schultz, William W; Liu, Quanyi; Keller, Robert B

    2009-04-01

    This work is an extension of experimental results reported previously, which might provide design guidance for approximating certain aspects of the flow boiling process in microgravity but taking place in Earth gravity. In that research the buoyancy effects on the bubble dynamics were minimized by the imposition of a liquid velocity parallel to a flat heater surface in the inverted horizontal position, or nearly horizontal (within +/-5 degrees ), thus holding the heated liquid and vapor formed close to the heater surface. For the fluid used, liquid velocities in the range U= 5-10 cm/s were judged to be critical for changes in the behavior of the flow boiling process. Using the hydraulic diameter of the rectangular duct used, with the heater surface embedded in one side, this velocity range gives rise to flow Reynolds numbers on the order of 4400-8800. It was subsequently judged to be of interest to extend the range of orientation of the flat heater surface relative to gravity to the full circular range of 0-360 degrees, in increments of 45 degrees, and the results of this work are presented here. A solid massive copper heater with a gold-plated boiling heat transfer surface 19 x 38 mm in size, previously used for critical heat flux measurements with boiling, provided a near-uniform surface temperature. Only steady measurements of heat flux and surface temperature were possible with the copper heater. R-113 was the fluid used; the velocity was varied over the interval of 4-28 cm/s; bulk liquid subcooling was varied over 5-11 degrees C; and heat flux varied over 0-10 w/cm(2). PMID:19426318

  16. Solid state and sub-cooled liquid vapour pressures of cyclic aliphatic dicarboxylic acids

    NASA Astrophysics Data System (ADS)

    Booth, A. M.; Montague, W. J.; Barley, M. H.; Topping, D. O.; McFiggans, G.; Garforth, A.; Percival, C. J.

    2010-10-01

    Knudsen Effusion Mass Spectrometry (KEMS) has been used to measure for the first time the solid state vapour pressures of a series of aliphatic cyclic dicarboxylic acids with increasing ring size. Additionally the atmospherically important compounds; cis-pinonic acid and levoglucosan were also measured. Differential Scanning Calorimetry (DSC) was used to measure melting points, enthalpies and entropies of fusion, which were used to determine sub-cooled liquid vapour pressures for the compounds. The sub-cooled liquid vapour pressure of straight chain, branched and cyclic dicarboxylic acids was compared to a selection of estimation methods.

  17. Solid state and sub-cooled liquid vapour pressures of cyclic aliphatic dicarboxylic acids

    NASA Astrophysics Data System (ADS)

    Booth, A. M.; Montague, W. J.; Barley, M. H.; Topping, D. O.; McFiggans, G.; Garforth, A.; Percival, C. J.

    2011-01-01

    Knudsen Effusion Mass Spectrometry (KEMS) has been used to measure for the first time the solid state vapour pressures of a series of aliphatic cyclic dicarboxylic acids with increasing ring size. Additionally the atmospherically important compounds; cis-pinonic acid and levoglucosan were also measured. Differential Scanning Calorimetry (DSC) was used to measure melting points, enthalpies and entropies of fusion, which were used to determine sub-cooled liquid vapour pressures for the compounds. The sub-cooled liquid vapour pressure of straight chain, branched and cyclic dicarboxylic acids was compared to a selection of estimation methods.

  18. Hydrothermal reactivity of saponite.

    USGS Publications Warehouse

    Whitney, G.

    1983-01-01

    The nature and extent of the reactions of synthetic Fe-free saponite have been investigated under experimental hydrothermal conditions as a first step towards understanding saponite reactivity under relatively simple conditions. Saponite crystallizes from amorphous gel of ideal saponite composition within 7 days at 300o-550oC under P = 1 kbar. Reactions subsequent to this initial crystallization depend on reaction T and interlayer cations. Saponite is found to react hydrothermally, over a period of 200 days, at T down to 400oC, at least 150oC lower than previously reported, but showed no signs of reaction below 400oC. At 450oC, a mixture of talc/saponite and saponite/phlogopite clays forms from K-saponite via intracrystalline layer transformations, while above 450oC the initial K-saponite dissolves, with talc and phlogopite forming as discrete phases. After 200 days reactions at 400-450oC were not complete, so that given sufficient time to reach equilibrium, a lower hydrothermal stability limit for saponite is possible. Further study of the Fe-bearing saponite system will be required before experimental results can be applied to natural systems.-D.F.B.

  19. Acoustically enhanced boiling heat transfer

    NASA Astrophysics Data System (ADS)

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

    2012-05-01

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

  20. Thermosyphon boiling in vertical channels

    Microsoft Academic Search

    A. Bar-Cohen; H. Schweitzer

    1983-01-01

    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

  1. The myth of the boiling point.

    PubMed

    Chang, Hasok

    2008-01-01

    Around 1800, many reputable scientists reported significant variations in the temperature of pure water boiling under normal atmospheric pressure. The reported variations included a difference of over 1 degree C between boiling in metallic and glass vessels (Gay-Lussac), and "superheating" up to 112 degrees C on extracting dissolved air out of water (De Luc). I have confirmed most of these observations in my own experiments, many of which are described in this paper. Water boils at the "boiling point" only under very particular circumstances. Our common-sense intuition about the fixedness of the boiling point is only sustained by our limited experience. PMID:18853575

  2. Performances of Stirling Type Pulse Tube Cryocooler for Sub-cooled Nitrogen System

    Microsoft Academic Search

    Y. Ohtani; T. Yazawa; T. Kuriyama; M. Urata; K. Inoue

    2006-01-01

    This paper describes performances of a Stirling type pulse tube cryocooler as a nitrogen sub-cooler. The main objective of this work is a demonstration of a cooling system for High Tc Superconducting (HTS) power applications such as fault current limiters, cables and transformers. Cooling capacity necessary for these applications is more than several hundred watts at 77 K level. High

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

    NASA Astrophysics Data System (ADS)

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

    1999-01-01

    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.

  4. Hypothetical Thermodynamic Properties. Subcooled Vaporization Enthalpies and Vapor Pressures of Polyaromatic Heterocycles and Related Compounds

    E-print Network

    Chickos, James S.

    Hypothetical Thermodynamic Properties. Subcooled Vaporization Enthalpies and Vapor Pressures The vaporization enthalpies and vapor pressures of the liqiud phase from T ) 298.15 K to T ) 500 K of a series. The vaporization enthalpies at T ) 298.15 K measured in kilojoules per mole include: tri-n-butylamine (62.7 ( 1

  5. Hypothetical Thermodynamic Properties. Subcooled Vaporization Enthalpies and Vapor Pressures of Polyaromatic Hydrocarbons

    E-print Network

    Chickos, James S.

    Hypothetical Thermodynamic Properties. Subcooled Vaporization Enthalpies and Vapor Pressures and Biochemistry, University of MissourisSt. Louis, St. Louis, Missouri 63121 The vaporization enthalpies and liquid vapor pressures from T ) 298.15 K to T ) 510 K of a series of polyaromatic hydrocarbons have been

  6. Cryogenic cooling system of HTS transformers by natural convection of subcooled liquid nitrogen

    E-print Network

    Chang, Ho-Myung

    Cryogenic cooling system of HTS transformers by natural convection of subcooled liquid nitrogen Ho-793, South Korea Abstract Heat transfer analysis on a newly proposed cryogenic cooling system is performed, and over-load operation. One of the key techniques to realize these advantages in practice is the cryogenic

  7. D0 Silicon Upgrade: ASME Code and Pressure Calculations for Liquid Nitrogen Subcooler

    SciTech Connect

    Kuwazaki, Andrew; Leicht, Todd; /Fermilab

    1995-10-04

    Included in this engineering note are three separate calculation divisions. The first calculations are the determination of the required thickness of the LN{sub 2} subcooler flat head according to ASME code. This section includes Appendix A-C. The minimum plate thickness determined was 0.563 in. The actual thickness chosen in fabrication was a 3/4-inch plate milled to 0.594-inch at the bolt circle. Along with the plate thickness, this section calculates the required reinforcement area at the top plate penetrations. It was found that a 1/4-inch fillet weld at each penetration was adequate. The next set of calculations were done to prove that the subcooler internal pressure will always be less than 15 psig and therefore will not be classified as a pressure vessel. The subcooler is always open to a vent pipe. Appendix D calculations show that the vent pipe has a capacity of 1042 lbs/hr if 15 psig is present at the subcooler. It goes on to show that the inlet piping would at that flow rate, see a pressure drop of 104 psig. The maximum supply pressure of the LN{sub 2} storage dewar is 50 psig. Appendix E addresses required flow rates for steady state, loss of vacuum, or fire conditions. Page E9 shows a summary which states the maximum pressure would be 1.50 psig at fire conditions and internal pressure.

  8. Application of thermal battery in the ice storage air-conditioning system as a subcooler

    Microsoft Academic Search

    Ming-Chao Huang; Bo-Ren Chen; Ming-Jer Hsiao; Sih-Li Chen

    2007-01-01

    This article experimentally investigates the thermal performance of a thermal battery used in the ice storage air-conditioning system as a subcooler. The thermal battery utilizes the superior heat transfer characteristics of two-phase closed thermosyphon and eliminates the drawbacks found in convectional energy storage systems. Experimental investigations are first conducted to study the thermal behavior of thermal battery under different charge

  9. The behavior of vapor bubbles during boiling enhanced with acoustics and open microchannels

    NASA Astrophysics Data System (ADS)

    Boziuk, Thomas; Smith, Marc K.; Glezer, Ari

    2012-11-01

    Boiling heat transfer on a submerged heated surface is enhanced by combining a grid of surface micromachined open channels and ultrasonic acoustic actuation to control the formation and evolution of vapor bubbles and to inhibit the instability that leads to film boiling at the critical heat flux (CHF). The microchannels provide nucleation sites for vapor bubble formation and enable the entrainment of bulk subcooled fluid to these sites for sustained evaporation. Acoustic actuation excites interfacial oscillations of the detached bubbles and leads to accelerated condensation in the bulk fluid, thereby limiting the formation of vapor columns that precede the CHF instability. The combined effects of microchannels and acoustic actuation are investigated experimentally with emphasis on bubble nucleation, growth, detachment, and condensation. It is shown that this hybrid approach leads to a significant increase in the critical heat flux, a reduction of the vapor mass above the surface, and the breakup of low-frequency vapor slug formation. A large-scale model of the microchannel grid reveals details of the flow near the nucleation site and shows that the presence of the microchannels decreases the surface superheat at a given heat flux. Supported by ONR.

  10. Does Hydrothermal Circulation Matter?

    NASA Astrophysics Data System (ADS)

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

    2006-05-01

    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.

  11. Life at Hydrothermal Vents

    NSDL National Science Digital Library

    Sohmer, Rachel.

    2002-01-01

    The first Web site is a NOVA Online Adventure from PBS (1). Into the Abyss decribes the "pitch darkness, poison gas, heavy metals, extreme acidity, and enormous pressure" found at hydrothermal vents, and offers a look at bizarre and fascinating creatures found in this environment. The next Web site from Exploring Earth, an online earth sciences text book, contains video clips taken during research expeditions along the Juan de Fuca Ridge (2). Ocean AdVENTure, a ThinkQuest Web site, offers a comprehensive and well-designed introduction to hydothermal vents from research tools to fauna to unsolved mysteries and more (3). Visitors can choose their own scientific adVENTure to explore hydrothermal vents in this interactive feature from the University of Washington School of Oceonagraphy Exploraquarium (4). 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." This Web site (5) extends a virtual invitation to join scientists aboard research cruises to the depth of the Pacific and Indian Oceans, providing daily logs, video, and other features for each expedition. The next Web site from the University of California-Berkeley offer a closer look at the "strange tube-dwelling worm" phylum found only near hydrothermal vents (6). Creature Features, provided by the University of Delaware Graduate College of Marine Science, contains descriptions and video clips of tubeworms, vent crabs, Pompeii crabs, and ancient bacteria found at deep sea vents (7). The last Web site (8) is a transcript of a June 1997 PBS NewsHour interview with science writer William Broad. Broad discusses his book The Universe Below: Discovering the Secrets of the Deep Sea, and relates the exciting opportunities for scientific exploration of the sea floor made possible by the end of the Cold War.

  12. 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.

  13. Thermosyphon boiling in vertical channels

    NASA Astrophysics Data System (ADS)

    Bar-Cohen, A.; Schweitzer, H.

    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.

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

    SciTech Connect

    Nelson, R.A.; Unal, C.

    1991-01-01

    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.

  15. Correlation of pool boiling curves for the homogeous group freons

    Microsoft Academic Search

    J. W. Westwater; J. C. Zinn; K. J. Brodbeck

    1989-01-01

    A knowledge of the complete boiling curve q verses ÎT for a liquid, including the regimes of nucleate boiling, transition boiling, and a film boiling is needed for the design and operation of various types of heat transfer equipment. No general method exists for predicting the complete curve. Most difficult is the prediction of the nucleate boiling curve, the transition

  16. Mechanisms of Boiling in Microchannels: Critical Assessment

    Microsoft Academic Search

    J. R. Thome; L. Consolini

    2010-01-01

    \\u000a Numerous characteristic trends and effects have been observed in published studies on two-phase micro-channel boiling heat\\u000a transfer. While macro-scale flow boiling heat transfer may be decomposed into nucleate and convective boiling contributions,\\u000a at the micro-scale the extent of these two important mechanisms remains unclear. Although many experimental studies have proposed\\u000a nucleate boiling as the dominant micro-scale mechanism, based on the

  17. Similarities and Differences Between Flow Boiling in Microchannels and Pool Boiling

    Microsoft Academic Search

    Satish G. Kandlikar

    2010-01-01

    Recent literature indicates that under certain conditions the heat transfer coefficient during flow boiling in microchannels is quite similar to that under pool boiling conditions. This is rather unexpected, as microchannels are believed to provide significant heat transfer enhancement under single-phase as well as flow boiling conditions. This article explores the underlying heat transfer mechanisms and illustrates the similarities and

  18. En Echelon Hydrothermal Systems

    NASA Astrophysics Data System (ADS)

    Ryan, M. P.; Carr, P. M.; Daniels, D. L.; Sutphin, D. M.

    2005-12-01

    En echelon hydrothermal systems develop within the porous rocks that surround, in three-dimensions, their distinctive plan-form and cross-sectional basaltic intrusion geometry. Examples that span several (self-similar) spatial scales include the en echelon off-set area of the East Rift Zone of Kilauea Volcano, Hawaii; the Northeast Rift Zone of Mauna Loa Volcano; the intrusive-eruptive fissures of the Krafla Central Volcano, Northeast Iceland; the ensemble of the three Icelandic central volcanoes Theistarekir-Krafla-Fremrinamur; major segments of the East Pacific Rise and the Mid-Atlantic Ridge; and several paleo-hydrothermal systems of the Mesozoic basins of eastern North America, including the Culpeper Basin. An en echelon hydrothermal system comprises two or more en echelon--arranged magma-filled fractures enclosed in a fluid-saturated porous matrix. Blocks of country rock between individual offset fracture segments are similarly porous and fluid-saturated. In 3-D, the system resembles the fan blades of a turbine rotor, with blades (dikes) emanating from a deep "master" fracture and turning smoothly in response to the local variations in the least compressive regional stress component. The primary geometric, hydrologic and thermal attributes of the system (on a horizontal plane) include dike thickness, dike-to-dike offset and overlap, the (initial) intrusion temperature, duration of magma flow, dike widths and lengths, the mean seepage velocity of regional subsurface aqueous fluid flow, and the mean flow azimuth in relationship to the plan-form geometry of the en echelon array. Finite element single phase models in horizontal cross-section have been developed for dike widths of 100 m, dike lengths of 1,500 m, overlaps of 500 m, dike-to-dike offsets of 500 m, intrusion temperatures of 1,200 C, horizontal seepage fluxes imposed at the sides of ~ 1,000 g cm-2 yr-1, and a matrix permeability of 10-14 m2. The regional flow field has been parameterized in dike-orthogonal, dike-parallel, and 45 degree angles of attack with respect to the major axes of the individual dikes within the en echelon array. Depending on the magnitudes and geometric arrangement of key system attributes, an en echelon hydrothermal system may either act as an efficient thermal radiator, effectively shedding heat to the surroundings, or may it act as an effective heater, thermally enhancing the environment between neighboring dikes in 3-D. Conditions that promote the efficient loss of heat include thin dikes of short length, large dike-to-dike offset, high matrix fluid velocities, and regional flow azimuths that are orthogonal to the individual dikes. Conditions that promote differential heating between the dikes include wide dikes with maximal overlap and minimal offset, low regional flow velocities and "angles of attack" of the regional flow field that provide for maximum hydrodynamic "shelter" for individual dikes within the interior of the en echelon array.

  19. The effect of refrigerant combinations on performance of a vapor compression refrigeration system with dedicated mechanical sub-cooling

    Microsoft Academic Search

    Bilal Ahmed Qureshi; Syed M. Zubair

    Performance characteristics due to use of different refrigerant combinations in vapor compression cycles with dedicated mechanical sub-cooling are investigated. For scratch designs, R134a used in both cycles produced the best results in terms of COP, COP gain and relative compressor sizing. In retrofit cases, considering the high sensitivity of COP to the relative size of heat exchangers in the sub-cooler

  20. An experimental investigation of liquid methane convection and boiling in rocket engine cooling channels

    NASA Astrophysics Data System (ADS)

    Trujillo, Abraham Gerardo

    In the past decades, interest in developing hydrocarbon-fueled rocket engines for deep spaceflight missions has continued to grow. In particular, liquid methane (LCH4) has been of interest due to the weight efficiency, storage, and handling advantages it offers over several currently used propellants. Deep space exploration requires reusable, long life rocket engines. Due to the high temperatures reached during combustion, the life of an engine is significantly impacted by the cooling system's efficiency. Regenerative (regen) cooling is presented as a viable alternative to common cooling methods such as film and dump cooling since it provides improved engine efficiency. Due to limited availability of experimental sub-critical liquid methane cooling data for regen engine design, there has been an interest in studying the heat transfer characteristics of the propellant. For this reason, recent experimental studies at the Center for Space Exploration Technology Research (cSETR) at the University of Texas at El Paso (UTEP) have focused on investigating the heat transfer characteristics of sub-critical CH4 flowing through sub-scale cooling channels. To conduct the experiments, the csETR developed a High Heat Flux Test Facility (HHFTF) where all the channels are heated using a conduction-based thermal concentrator. In this study, two smooth channels with cross sectional geometries of 1.8 mm x 4.1 mm and 3.2 mm x 3.2 mm were tested. In addition, three roughened channels all with a 3.2 mm x 3.2 mm square cross section were also tested. For the rectangular smooth channel, Reynolds numbers ranged between 68,000 and 131,000, while the Nusselt numbers were between 40 and 325. For the rough channels, Reynolds numbers ranged from 82,000 to 131,000, and Nusselt numbers were between 65 and 810. Sub-cooled film-boiling phenomena were confirmed for all the channels presented in this work. Film-boiling onset at Critical Heat Flux (CHF) was correlated to a Boiling Number (Bo) of approximately 0.1 for all channels. Convective Nusselt number follows predicted trends for Reynolds number with a wall temperature correction for both the boiling and non-boiling regimes.

  1. Oxygen and carbon isotope ratios of hydrothermal minerals from Yellowstone drill cores

    USGS Publications Warehouse

    Sturchio, N.C.; Keith, T.E.C.; Muehlenbachs, K.

    1990-01-01

    Oxygen and carbon isotope ratios were measured for hydrothermal minerals (silica, clay and calcite) from fractures and vugs in altered rhyolite, located between 28 and 129 m below surface (in situ temperatures ranging from 81 to 199??C) in Yellowstone drill holes. The purpose of this study was to investigate the mechanism of formation of these minerals. The ??18O values of the thirty-two analyzed silica samples (quartz, chalcedony, ??-cristobalite, and ??-cristobalite) range from -7.5 to +2.8???. About one third of the silica 7samples have ??18O values that are consistent with isotopic equilibrium with present thermal waters; most of the other silica samples appear to have precipitated from water enriched in 18O (up to 4.7???) relative to present thermal water, assuming precipitation at present in situ temperatures. Available data on fluid-inclusion homogenization temperatures in hydrothermal quartz indicate that silica precipitation occurred mostly at temperatures above those measured during drilling and imply that 15O enrichments in water during silica precipitation were generally larger than those estimated from present conditions. Similarly, clay minerals (celadonite and smectite) have ??18O values higher (by 3.5 to 7.9???) than equilibrium values under present conditions. In contrast, all eight analyzed calcite samples are close to isotopic equilibrium with present thermal waters. The frequent incidence of apparent 18O enrichment in thermal water from which the hydrothermal minerals precipitated may indicate that a higher proportion of strongly 18O-enriched deep hydrothermal fluid once circulated through shallow portions of the Yellowstone system, or that a recurring transient 18O-enrichment effect occurs at shallow depths and is caused either by sudden decompressional boiling or by isotopic exchange at low water/rock ratios in new fractures. The mineralogy and apparent 18O enrichments of hydrothermal fracture-filling minerals are consistent with deposition during transient boiling or rock-water exchange (fracturing) events. ?? 1990.

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

    NASA Video Gallery

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

  3. Enhancement of Pool Boiling Heat Transfer in Confined Space 

    E-print Network

    Hsu, Chia-Hsiang

    2014-05-05

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

  4. Sulfur speciation in natural hydrothermal waters, Iceland

    NASA Astrophysics Data System (ADS)

    Kaasalainen, Hanna; Stefánsson, Andri

    2011-05-01

    The speciation of aqueous dissolved sulfur was determined in hydrothermal waters in Iceland. The waters sampled included hot springs, acid-sulfate pools and mud pots, sub-boiling well discharges and two-phase wells. The water temperatures ranged from 4 to 210 °C, the pH T was between 2.20 and 9.30 at the discharge temperature and the SO 4 and Cl concentrations were 0.020-52.7 and <0.01-10.0 mmol kg -1, respectively. The analyses were carried out on-site within ˜10 min of sampling using ion chromatography (IC) for sulfate (SO 42-), thiosulfate (S 2O 32-) and polythionates (S xO 62-) and titration and/or colorimetry for total dissolved sulfide (S 2-). Sulfite (SO 32-) could also be determined in a few cases using IC. Alternatively, for few samples in remote locations the sulfur oxyanions were stabilized on a resin on site following elution and analysis by IC in the laboratory. Dissolved sulfate and with few exceptions also S 2- were detected in all samples with concentrations of 0.02-52.7 mmol kg -1 and <1-4100 ?mol kg -1, respectively. Thiosulfate was detected in 49 samples of the 73 analyzed with concentrations in the range of <1-394 ?mol kg -1 (S-equivalents). Sulfite was detected in few samples with concentrations in the range of <1-3 ?mol kg -1. Thiosulfate and SO 32- were not detected in <100 °C well waters and S 2O 32- was observed only at low concentrations (<1-8 ?mol kg -1) in ˜200 °C well waters. In alkaline and neutral pH hot springs, S 2O 32- was present in significant concentrations sometimes corresponding to up to 23% of total dissolved sulfur (S TOT). In steam-heated acid-sulfate waters, S 2O 32- was not a significant sulfur species. The results demonstrate that S 2O 32- and SO 32- do not occur in the deeper parts of <150 °C hydrothermal systems and only in trace concentrations in ˜200-300 °C systems. Upon ascent to the surface and mixing with oxygenated ground and surface waters and/or dissolution of atmospheric O 2, S 2- is degassed and oxidized to SO 32- and S 2O 32- and eventually to SO 42- at pH >8. In near-neutral hydrothermal waters the oxidation of S 2- and the interaction of S 2- and S 0 resulting in the formation of S x2- are considered important. At lower pH values the reactions seemed to proceed relatively rapidly to SO 42- and the sulfur chemistry of acid-sulfate pools was dominated by SO 42-, which corresponded to >99% of S TOT. The results suggest that the aqueous speciation of sulfur in natural hydrothermal waters is dynamic and both kinetically and source-controlled and cannot be estimated from thermodynamic speciation calculations.

  5. Stability characteristics of a cable-in-conduit conductor by subcooled supercritical helium

    NASA Astrophysics Data System (ADS)

    Wachi, Y.; Hanawa, S.; Ono, M.; Shimada, M.; Hamajima, T.; Takano, H.; Shinohara, H.; Takahata, K.; Yamamoto, J.; Motojima, O.

    1994-07-01

    The stability and limiting current of a NbTi forced-cooled superconducting coil have been investigated experimentally and analytically at the subcooled condition below 4.5 K. The test coil was wound in a one layer solenoid from a cable-in-conduit type conductor of critical current of 5.1 kA at 4.2 K and 6.5 T, whose total length was 10 m. It was installed in the bore of a back-up superconducting magnet that provided field 8 T at the test coil. The stability margin of the coil as a function of normalized current (transport current/critical current) was The results are compared with the formula proposed by Dresner and reported to predictions of stability margin and limiting current at subcooled condition below 4.5 K.

  6. Maximum two-phase flow rates of subcooled nitrogen through a sharp-edged orifice

    NASA Technical Reports Server (NTRS)

    Simoneau, R. J.

    1975-01-01

    Data are presented of an experiment in which subcooled liquid nitrogen was discharged through a sharp-edged orifice at flow rates near the maximum. The data covered a range of inlet stagnation pressures from slightly above saturation to twice the thermodynamic critical pressure. The data were taken along five separate inlet stagnation isotherms ranging from 0.75 to 1.035 times the thermodynamic critical temperature. The results indicate that subcooled liquids do not choke or approach maximum flow in an asymptotic manner even though the back pressure is well below saturation; and orifice flow coefficients are not constant as is frequently assumed. A metastable jet appears to exist which breaks down if the difference between back pressure and saturation pressure is large enough.

  7. Boils

    MedlinePLUS

    ... the American Osteopathic College of Dermatology. Community Search Search » Sign In Remember Me Forgot your password? Haven't registered yet? more Calendar 10/16/2015 » 10/18/2015 2015 AOCD Fall Meeting 3/30/2016 » 4/3/2016 2016 AOCD Spring Current Concepts in Dermatology Meeting 3/29/2017 » 4/2/ ...

  8. Core boiling during midloop operation

    SciTech Connect

    Fujita, N.; Rice, D.A. (Yankee Atomic Electric Co., Bolton, MA (US))

    1991-01-01

    The reactor coolant system (RCS) water level is reduced during each refueling at some plants. Decreasing the level below the top of the loop piping (midloop operation) may be necessary to work on unisolable RCS loop components. A loss of residual heat removal (RHR) under these conditions can be serious due to the reduced water inventory, air in the RCS, and openings in the RCS loops. Under certain conditions, a loss of RHR could lead to rapid core uncovery and potential fuel damage. Core boiling due to a loss of RHR during midloop operation has received little attention until recently. The transient involves complex phenomena induced by core boiling, such as inventory loss from RCS openings and differences between the downcomer and upper plenum water levels, with the reactor vessel acting like a manometer. These phenomena cannot be easily evaluated without a versatile thermal-hydraulic computer code such as RETRAN. This paper provides an analysis of these phenomena which reveals that the time to core uncovery is shortened by the loss of coolant through RCS openings and the manometer behavior of the reactor vessel water level. This analysis points out some limitations in applying the RETRAN code to this transient.

  9. Performance Assessment of 239 Series Helium SubCooling Heat Exchangers for the Large Hadron Collider

    Microsoft Academic Search

    N. Gilbert; P. Roussel; G. Riddone; R. Moracchioli; L. Tavian

    2006-01-01

    Helium sub-cooling heat exchangers of the counter-flow type are used to minimize the vapor fraction produced in the final expansion of the 1.9 K distributed cooling loops used for cooling the superconducting magnets of the Large Hadron Collider (LHC). These components are of compact design, featuring low-pressure drop and handling very low pressure vapor at low temperature. Following a qualification

  10. D0 Silicon Upgrade: ASME Code and Pressure Calculations for Liquid Nitrogen Subcooler

    Microsoft Academic Search

    Andrew Kuwazaki; Todd Leicht

    1995-01-01

    Included in this engineering note are three separate calculation divisions. The first calculations are the determination of the required thickness of the LN subcooler flat head according to ASME code. This section includes Appendix A-C. The minimum plate thickness determined was 0.563 in. The actual thickness chosen in fabrication was a 3\\/4-inch plate milled to 0.594-inch at the bolt circle.

  11. Second-law-based thermodynamic analysis of two-stage and mechanical-subcooling refrigeration cycles

    Microsoft Academic Search

    S. M Zubair; M Yaqub; S. H Khan

    1996-01-01

    Thermodynamic analysis of HFC-134a vapor-compression refrigeration cycles is investigated by both the first and second laws of thermodynamics. Second-law analysis is carried out for both two-stage and mechanical-subcooling refrigeration cycles. The analysis is performed on each of the system components to determine their individual contribution to the overall system irreversible losses. It is found that most of the losses are

  12. Nanowires for Enhanced Boiling Heat Transfer

    Microsoft Academic Search

    Renkun Chen; Ming-Chang Lu; Vinod Srinivasan; Zhijie Wang; Hyung Hee Cho; Arun Majumdar

    2009-01-01

    ABSTRACT Boiling is a common mechanism for liquid-vapor phase transition and is widely exploited in power generation and refrigeration devices and systems. The efficacy of boiling heat transfer is characterized by two parameters: (a) heat transfer coefficient (HTC) or the thermal conductance; (b) the critical heat flux (CHF) limit that demarcates the transition from high HTC to very low HTC.

  13. Nanofluid boiling: The effect of surface wettability

    Microsoft Academic Search

    Johnathan S. Coursey; Jungho Kim

    2008-01-01

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

  14. Stability monitoring for boiling water reactors

    Microsoft Academic Search

    Miguel Cecenas-Falcon

    1999-01-01

    A methodology is presented to evaluate the stability properties of Boiling Water Reactors based on a reduced order model, power measurements, and a non-linear estimation technique. For a Boiling Water Reactor, the feedback reactivity imposed by the thermal-hydraulics has an important effect in the system stability, where the dominant contribution to this feedback reactivity is provided by the void reactivity.

  15. SWR 1000: The Innovative Boiling Water Reactor

    Microsoft Academic Search

    Werner Brettschuh; Greg Hudson

    2004-01-01

    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

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

    PubMed

    Pimenova, Anastasiya V; Goldobin, Denis S

    2014-11-01

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

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

    E-print Network

    Anastasiya V. Pimenova; Denis S. Goldobin

    2014-10-20

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

  18. Cavitating venturi performance at low inlet subcooling: Normal operation, overflow and recovery of overflow

    SciTech Connect

    Ungar, E.K.; Dzenitis, J.M. [NASA Johnson Space Center, Houston, TX (United States). Crew and Thermal Systems Division; Sifuentes, R.T. [McDonnell Douglas Aerospace, Houston, TX (United States). Thermal Control Systems Dept.

    1994-12-31

    Cavitating venturis (CVs) were to have been used to passively control the flow of liquid ammonia to the evaporators in the Space Station Freedom (SSF) two-phase active thermal control system (ATCS). Because the head rise of the SSF ATCS pump was low to conserve electrical power, the inlet subcooling at the cavitating venturi would have been lower than is the case in normal CV applications. Testing at NASA/Johnson Space Center has shown that when cavitating venturis are operated at low values of inlet subcooling (on the order of 100 kPa or 15 psid), an overflow phenomenon can occur. Here the flow is liquid throughout the venturi and flows at a higher mass flow rate than the cavitation limit. Once overflow occurs, cavitation is reestablished only when the downstream pressure is decreased to a low value. Overflow test data were obtained for six cavitating venturis with throat diameters between 0.28 and 1.83 mm (0.011 and 0.072 in). Analysis of the test result showed that overflow could not be sustained beyond a critical value of the superheat pressure at the cavitating venturi throat. In the present work, the phenomenon of overflow is explored and its implications for cavitating venturis in general applications and for applications similar to SSF are discussed. Recommendations are made for predicting the mode of operation of a cavitating venturi at low values of the inlet subcooling.

  19. Performance of extended surface from a cryocooler for subcooling liquid nitrogen by natural convection

    NASA Astrophysics Data System (ADS)

    Choi, Yeon Suk; Chang, Ho-Myung; Van Sciver, Steven W.

    2006-05-01

    Natural convection of subcooled liquid nitrogen under a horizontal flat plate is measured by experiment. This study is motivated mainly by our recent development of cryocooling systems for HTS power devices without any forced circulation of liquid nitrogen. Since the cold surface of a GM cryocooler is very limited, the cooling plate immersed in subcooled liquid nitrogen is thermally anchored to the cryocooler located at the top in order to serve as an extended surface. A vertical plate generating uniform heat flux is placed at a given distance under the cooling plate so that subcooled liquid may generate cellular flow by natural convection. The temperature distributions on the plates and liquid are measured during the cool-down and in steady state, from which the heat transfer coefficients are calculated and compared with the existing correlations for a horizontal surface with uniform temperature. A fair agreement is observed between two data sets, when the heat flux is small or the plate temperatures are relatively uniform in horizontal direction. Some discrepancy at higher heat flux is explained by the cellular flow pattern and the fin efficiency of the extended surface, resulting in the non-uniformity of the horizontal plate.

  20. Analysis and measurement of thermal conductivity of polypropylene laminated paper impregnated with subcooled liquid nitrogen

    NASA Astrophysics Data System (ADS)

    Furuse, Mitsuho; Fuchino, Shuichiro

    2014-09-01

    We measured the thermal conductivity of polypropylene laminated paper (PPLP) impregnated with subcooled liquid nitrogen. PPLP is widely used for the electrical insulation of high-Tc superconducting (HTS) power transmission cables. Although the thermal conductivity of PPLP is an important factor in the design of HTS cables, there has been very limited work on its measurement in subcooled liquid nitrogen. We prepared PPLP samples and symmetrically stacked them on both sides of a heater. The stacked samples were immersed in liquid nitrogen in an open cryostat. A cryocooler mounted on the cryostat was used to maintain the subcooled temperature of the liquid nitrogen. The thermal conductivity of the stacked PPLPs was measured by the steady state method at a bath temperature of 65-75 K and was found to be 0.23-0.26 W/m K, which is about five times that measured in a vacuum as presented in available literature. We also discuss possible mechanisms for boosting the thermal conductivity of PPLP by liquid nitrogen impregnation.

  1. Dryout and Rewetting in the Pool Boiling Experiment Flown on STS-72 (PBE-2 B) and STS-77 (PBE-2 A)

    NASA Technical Reports Server (NTRS)

    Merte, Herman, Jr.; Lee, Ho Sung; Keller, Robert B.

    1998-01-01

    Experiments were conducted in the microgravity of space in which a pool of liquid (R-113), initially at a precisely defined pressure and temperature, is subjected to a step imposed heat flux from a semi-transparent thin-film heater forming part of one wall of the container such that boiling is initiated and maintained for a defined period of time at a constant pressure level. A total of nine tests were conducted at three levels of heat flux and three levels of subcooling in each of the two space experiments in a GAS canister on the STS-77, -72, respectively. Three (3) modes of propagation of boiling across the heater surface and subsequent vapor bubble growths were observed, in addition to the two (2) modes observed in the previous microgravity pool boiling space flights on STS-47, -57, and -60. Of particular interest were the extremely dynamic or "explosive" growths, which were determined to be the consequence of the large increase in the liquid-vapor interface area associated with the appearance of a corrugated or rough interface. Predictions of circumstances for its onset have been carried out. Assumptions were necessary regarding the character of disturbances necessary for the instabilities to grow. Also, a new vapor bubble phenomena was observed in which small vapor bubbles migrated toward a larger bubble, eventually coalescing with this larger bubble. The heat transfer was enhanced approximately 30% as a result of these migrating bubbles, which is believed to be a vapor bubble manifestation of Marangoni convection and/or molecular momentum effects, sometimes referred to as vapor recoil. The circumstances of heat flux and liquid subcooling necessary to produce heater surface dryout for an initially stagnant liquid subjected to an imposed heat flux have been more closely identified.

  2. Anomaly Geochemical Fields in Siberian Hydrothermal Gold Deposits

    NASA Astrophysics Data System (ADS)

    Voroshilov, V.; Savinova, O.; Ananev, Yu; Abramova, R.

    2014-08-01

    The composition and internal structure of geochemical fields associated to hydrothermal gold deposits within the Siberian territory were investigated. The concentric zonal structure of ore-forming geochemical fields embracing accumulations of Au, Ag, Bi, Pb, Zn, Cu, Te, As in ore bodies and their adjacent locations, and Ni, Co, V, Cr, Mn, Ba, Ti - within the external margin of gold ore formations were determined. The thermometric properties of gas-fluid inclusions in minerals of hydrothermal gold deposits were described. The results specified not only high-mineralized but also weakly-salted fluids are involved in the formation of the deposit. The latter is subjected to both retrogressive boiling and the mechanisms of direct and reverse osmosis. In this case, ascending and descending fluids produce eddy fluxes during Earth rotation, where minerals of different composition are formed in this flow path. Produced spiral mineral-geochemical fields can be observed on satellite images as hierarchy circular pattern system. Both the analysis of anomalous geochemical field structure and satellite images make it possible to predict the ore bodies of different grades in complicated landscape geological conditions.

  3. Subcritical water as reaction environment: fundamentals of hydrothermal biomass transformation.

    PubMed

    Möller, Maria; Nilges, Peter; Harnisch, Falk; Schröder, Uwe

    2011-05-23

    Subcritical water, that is, water above the boiling and below critical point, is a unique and sustainable reaction medium. Based on its solvent properties, in combination with the often considerable intrinsic water content of natural biomass, it is often considered as a potential solvent for biomass processing. Current knowledge on biomass transformation in subcritical water is, however, still rather scattered without providing a consistent picture. Concentrating on fundamental physical and chemical aspects, this review summarizes the current state of knowledge of hydrothermal biomass conversion in subcritical water. After briefly introducing subcritical water as a reaction medium, its advantages for biomass processing compared to other thermal processes are highlighted. Subsequently, the physical-chemical properties of subcritical water are discussed in the light of their impact on the occurring chemical reactions. The influence of major operational parameters, including temperature, pressure, and reactant concentration on hydrothermal biomass transformation processes are illustrated for selected carbohydrates. Major emphasis is put on the nature of the carbohydrate monomers, since the conversion of the respective polymers is analogous with the additional prior step of hydrolytic depolymerization. PMID:21322117

  4. Mo isotope fractionation during hydrothermal evolution of porphyry Cu systems

    NASA Astrophysics Data System (ADS)

    Shafiei, Behnam; Shamanian, GholamHossein; Mathur, Ryan; Mirnejad, Hassan

    2015-03-01

    We present Mo isotope compositions of molybdenite types from three successive stages of ore deposition in several porphyry copper deposits of the Kerman region, Iran. The data provide new insights into controlling processes on Mo isotope fractionation during the hydrothermal evolution of porphyry systems. The Mo isotope compositions of 27 molybdenite samples show wide variations in ?97Mo ranging from -0.37 to +0.92 ‰. The data reveal that molybdenites in the early and transitional stages of mineralization (preferentially 2H polytypes; ?97Mo mean = 0.35 ‰) have higher ?97Mo values than late stage (mainly 3R polytypes; ?97Mo mean = 0.02 ‰) molybdenites. This trend suggests that fractionation of Mo isotopes occurred in high-temperature stages of mineralization and that hydrothermal systems generally evolve towards precipitation of molybdenite with lower ?97Mo values. Taking into account the genetic models proposed for porphyry Cu deposits along with the temperature-dependent fractionation of Mo isotope ratios, it is proposed that large variations of Mo isotopes in the early and the transitional stages of ore deposition could be controlled by the separation of the immiscible ore-forming fluid phases with different density, pH, and ƒO2 properties (i.e., brine and vapor). The fractionation of Mo isotopes during fluid boiling and Rayleigh distillation processes likely dominates the Mo isotope budget of the remaining ore-forming fluids for the late stage of mineralization. The lower ?97Mo values in the late stage of mineralization can be explained by depletion of the late ore-forming hydrothermal solutions in 97Mo, as these fluids have moved to considerable distance from the source. Finally, the relationship observed between MoS2 polytypes (2H and 3R) and their Mo isotopic compositions can be explained by the molecular vibration theory, in which heavier isotopes are preferentially partitioned into denser primary 2H MoS2 crystals.

  5. Boiling Heat Transfer to Halogenated Hydrocarbon Refrigerants

    NASA Astrophysics Data System (ADS)

    Yoshida, Suguru; Fujita, Yasunobu

    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.

  6. Transient behavior of superheated water jets boiling

    NASA Astrophysics Data System (ADS)

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

    2012-06-01

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

  7. Boiling heat transfer from an excavated fin

    NASA Astrophysics Data System (ADS)

    Liaw, S. P.; Yeh, R. H.

    1992-04-01

    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 2D 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 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.

  8. Hydrothermal synthesis of ammonium illite

    USGS Publications Warehouse

    Sucha, V.; Elsass, F.; Eberl, D.D.; Kuchta, L'.; Madejova, J.; Gates, W.P.; Komadel, P.

    1998-01-01

    Synthetic gel and glass of illitic composition, natural kaolinite, and mixed-layer illite-smectite were used as starting materials for hydrothermal synthesis of ammonium illite. Ammonium illite was prepared from synthetic gel by hydrothermal treatment at 300??C. The onset of crystallization began within 3 h, and well-crystallized ammonium illite appeared at 24 h. Increasing reaction time (up to four weeks) led to many illite layers per crystal. In the presence of equivalent proportions of potassium and ammonium, the gel was transformed to illite with equimolar contents of K and NH4. In contrast, synthesis using glass under the same conditions resulted in a mixture of mixed-layer ammonium illite-smectite with large expandability and discrete illite. Hydrothermal treatments of the fine fractions of natural kaolinite and illite-smectite produced ammonium illite from kaolinite but the illite-smectite remained unchanged.

  9. Structure of a seafloor hydrothermal system in volcanic sediment: distribution of hydrothermal clay minerals, at the Iheya North Knoll, Okinawa Trough

    NASA Astrophysics Data System (ADS)

    Miyoshi, Y.; Ishibashi, J.; Faure, K.; Uehara, S.

    2012-12-01

    Detailed investigation of clay minerals in hydrothermal fields provides fundamental information for understanding the physical and geochemical conditions within a hydrothermal system. Moreover, stable isotope geochemistry of clay minerals provides constraints on formation temperature. We investigated the distribution of clay minerals by XRD and TEM-EDS in a seafloor hydrothermal field at Iheya North Knoll in the Okinawa Trough, using cored sediment obtained from the Integrated Ocean Drilling Program (IODP) Expedition 331. The chemical composition and isotope values of the representative clay minerals were analyzed to obtain information on the hydrothermal system beneath the seafloor. Vertically, two different clay mineral facies are present. The boundary between the facies was identified at 6 mbsf (meters below the seafloor) at Site C0013 (100 m east of hydrothermal mound) and at 23 mbsf at Site C0014 (450 m east of the mound). In the lower facies (6 - 28 mbsf and 45 mbsf at Site C0013, 23 - 114 mbsf at Site C0014), Mg-chlorite and/or Mg-chlorite-smectite mixed layer minerals are dominant. They are associated with sericite in deeper parts (45 mbsf at Site C0013 and 38 - 114 mbsf at Site C0014). The ?18O values of the clays range from +1.5 to +4.7 ‰ (VSMOW) and the formation temperatures of the Mg-chlorite are estimated to be 230 - 300 °C, assuming a value from 0 to +1.5 ‰ for ?18Owater. The original sediment in the Iheya North Knoll is considered to have been volcanic of felsic chemical composition, so alteration to Mg-rich chlorite would require supply of substantial amount of Mg. Abundant formation of Mg-chlorite is attributed to mixing of hydrothermal fluid and seawater. In the upper facies at both sites, Al-rich clay minerals (kaolinite and montmorillonite) dominate. The ?18O values of clays range between +9.6 and +13.3 ‰ and formation temperatures are estimated to range between 120 - 160 °C. As kaolinite formation is favorable under acidic conditions, the kaolinite may be related to the vapor phase component enriched in CO2 and H2S, which would be generated by boiling of the hydrothermal fluid below the seafloor. In summary, occurrence of different facies of hydrothermal clay minerals reflects substantial variation in both temperature and chemical conditions between the upper and lower sediment layer. This difference may be related to discrete fluid flow within these sediment layers.

  10. Origin of tonalites from the Boil Mountain ophiolitic complex, west-central Maine

    SciTech Connect

    Chow, J.S. (Boston Univ., MA (United States). Geology Dept.)

    1993-03-01

    The Boil Mountain ophiolitic complex, west-central Maine, marks the suture between the Boundary Mountain and Gander terranes that became amalgamated in the late Cambrian during a pre-Taconic collisional event known as the Penobscottian orogeny. This even formed a composite terrane that is believed to have collided with the proto-North American margin during the Ordovician Taconic orogeny. The ophiolite is unusual in that there is no associated tectonized ultramafic section; there is a lack of a sheeted dike sequence; and an intrusive tonalite layer comprises a significant volume of the complex. Preliminary major and trace element geochemical analysis of the tonalites indicates that this unit is derived by partial melting of the associated mafic volcanics. This melting may have been induced by stopping water-rich hydrothermally altered basalts into subcrustal magma chambers. The association of arc-like volcanics and plutonics of the Boil Mountain ophiolite with the adjacent Hurricane melange suggests that the Boil Mountain may be a fragment of a forearc supra-subduction zone complex. Similar interpretations have been made recently for the Late Proterozoic Bou Azzer ophiolite in Morocco and the Coast Range ophiolite.

  11. Boiling heat transfer in rectangular microchannels with reentrant cavities

    E-print Network

    Peles, Yoav

    been found to promote convective boiling, while Nucleate Boiling dominated at low Reynolds number transfer and fluid flow mechanisms governing boil- ing in microchannels, and has resulted in heat transferBoiling heat transfer in rectangular microchannels with reentrant cavities Ali Kosßar, Chih

  12. Boiling heat transfer on superhydrophilic, superhydrophobic, and superbiphilic surfaces

    E-print Network

    Attinger, Daniel

    , metallurgy, electronics cooling, and food processing. While flow boiling describes the boiling of liquidsBoiling heat transfer on superhydrophilic, superhydrophobic, and superbiphilic surfaces Amy Rachel Enhanced heat transfer Pool boiling Nucleation a b s t r a c t With recent advances in micro

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

    SciTech Connect

    Harris, M.

    1985-01-01

    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.

  14. Pool boiling on nano-finned surfaces 

    E-print Network

    Sriraman, Sharan Ram

    2008-10-10

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

  15. Pool boiling on nano-finned surfaces 

    E-print Network

    Sriraman, Sharan Ram

    2009-05-15

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

  16. Pool boiling heat transfer characteristics of nanofluids

    E-print Network

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

    2007-01-01

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

  17. Description of boiling project burnout detector

    E-print Network

    Raymond, M. W.

    1957-01-01

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

  18. Conceptual design for spacelab pool boiling experiment

    NASA Technical Reports Server (NTRS)

    Lienhard, J. H.; Peck, R. E.

    1978-01-01

    A pool boiling heat transfer experiment to be incorporated with a larger two-phase flow experiment on Spacelab was designed to confirm (or alter) the results of earth-normal gravity experiments which indicate that the hydrodynamic peak and minimum pool boiling heat fluxes vanish at very low gravity. Twelve small sealed test cells containing water, methanol or Freon 113 and cylindrical heaters of various sizes are to be built. Each cell will be subjected to one or more 45 sec tests in which the surface heat flux on the heaters is increased linearly until the surface temperature reaches a limiting value of 500 C. The entire boiling process will be photographed in slow-motion. Boiling curves will be constructed from thermocouple and electric input data, for comparison with the motion picture records. The conduct of the experiment will require no more than a few hours of operator time.

  19. Nucleate boiling bubble growth and departure

    E-print Network

    Staniszewski, Bogumil E.

    1959-01-01

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

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

    E-print Network

    are conducted with HFE-7100 as this fluid has a low boiling temperature at the cabin pressure of the A300Boiling heat transfer in a vertical microchannel: Local estimation during flow boiling with a non the results of experimental and numerical studies concerning boiling heat transfer inside vertical

  1. Experimental and analytical study of stability characteristics of natural circulation boiling water reactors during startup transient

    NASA Astrophysics Data System (ADS)

    Woo, Kyoungsuk

    Two-phase natural circulation loops are unstable at low pressure operating conditions. New reactor design relying on natural circulation for both normal and abnormal core cooling is susceptible to different types of flow instabilities. In contrast to forced circulation boiling water reactor (BWR), natural circulation BWR is started up without recirculation pumps. The tall chimney placed on the top of the core makes the system susceptible to flashing during low pressure start-up. In addition, the considerable saturation temperature variation may induce complicated dynamic behavior driven by thermal non-equilibrium between the liquid and steam. The thermal-hydraulic problems in two-phase natural circulation systems at low pressure and low power conditions are investigated through experimental methods. Fuel heat conduction, neutron kinetics, flow kinematics, energetics and dynamics that govern the flow behavior at low pressure, are formulated. A dimensionless analysis is introduced to obtain governing dimensionless groups which are groundwork of the system scaling. Based on the robust scaling method and start-up procedures of a typical natural circulation BWR, the simulation strategies for the transient with and without void reactivity feedback is developed. Three different heat-up rates are applied to the transient simulations to study characteristics of the stability during the start-up. Reducing heat-up rate leads to increase in the period of flashing-induced density wave oscillation and decrease in the system pressurization rate. However, reducing the heat-up rate is unable to completely prevent flashing-induced oscillations. Five characteristic regions of stability are discovered at low pressure conditions. They are stable single-phase, flashing near the separator, intermittent oscillation, sinusoidal oscillation and low subcooling stable regions. Stability maps were acquired for system pressures ranging 100 kPa to 400 kPa. According to experimental investigation, the flow becomes stable below a certain heat flux regardless of the inlet subcooling at the core and system pressure. At higher heat flux, unstable phenomena were indentified within a certain range of inlet subcooling. The unstable region diminishes as the system pressure increases. In natural circulation BWRs, the significant gravitational pressure drop over the tall chimney section induces a Type-I instability. The Type-I instability becomes especially important during low power and pressure conditions during reactor start-up. Under these circumstances the effect of pressure variations on the saturation enthalpy becomes significant. An experimental study shows that the flashing phenomenon in the adiabatic chimney section is dominant during the start-up of a natural circulation BWR. Since flashing occurs outside the core, nuclear feedback effects on the stability are small. Furthermore, the thermal-hydraulic oscillation period is much longer than power fluctuation period caused by void reactivity feedback. In the natural circulation system increasing the inlet restriction reduces the natural circulation flow rate, shifting the unstable region to higher inlet subcooling.

  2. Hadronic matter near the boiling point

    Microsoft Academic Search

    Rolf Hagedorn

    1968-01-01

    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

  3. Feedback stabilization of transition boiling states

    Microsoft Academic Search

    Rob van Gils; Michel Speetjens; Henk Nijmeijer

    2010-01-01

    A nonlinear one-dimensional heat-transfer model for pool boiling systems is considered. The model involves only the temperature distribution within the heater and models the heat exchange with the boiling medium via a nonlinear boundary condition imposed at the fluid-heater interface. This compact model is employed for the design and analysis of a control strategy for the stabilization of unstable states

  4. Hydrothermal synthesis of perovskite nanotubes.

    PubMed

    Mao, Yuanbing; Banerjee, Sarbajit; Wong, Stanislaus S

    2003-02-01

    A low-temperature hydrothermal reaction has been utilized to generate crystalline barium titanate and strontium titanate nanotubes, which have been characterized by means of X-ray diffraction and transmission electron microscopy, coupled with energy dispersive X-ray analysis. PMID:12613636

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

    SciTech Connect

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

    2011-01-15

    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)

  6. Hydrothermal synthesis of amino acids

    SciTech Connect

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

    1994-05-01

    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.

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

    E-print Network

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

    2015-01-01

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

  8. Improvements to the prediction of boiling transition during boiling water reactor transients

    Microsoft Academic Search

    R. E. Phillips; R. W. Shumway; K. H. Chu

    1981-01-01

    The ability to accurately predict the time required to reach a boiling transition in postulated BWR (Boiling Water Reactor) loss of coolant accidents is an important step in analyzing the system response to these transients. As part of the effort to develop an advanced BWR system analysis computer code capable of simulating these postulated transients, a study has been undertaken

  9. A review of film boiling at cryogenic temperatures.

    NASA Technical Reports Server (NTRS)

    Hsu, Y. Y.

    1972-01-01

    Film boiling occurs in the quenching of metals, the chilling of biological species, the regenerative cooling of rockets, and the cooling down of a cryogenic fuel tank. Occasionally film boiling is also found in a nuclear reactor or in a cryomagnet. Aspects of film boiling involving an unconstrained liquid mass are considered, giving attention to the evaporation time, the Leidenfrost temperature, solid-liquid contacts, the thermal properties of the solid, effects of coating or scale, wettability, the metastable condition, and the velocity effect on drops. Developments discussed with regard to pool boiling are related to vertical surfaces, film boiling from horizontal surfaces, film boiling from a horizontal cylinder, film boiling from a sphere, and film boiling of helium. Processes of film boiling in a channel are also analyzed.

  10. Cryogenic Boil-Off Reduction System

    NASA Astrophysics Data System (ADS)

    Plachta, David W.; Guzik, Monica C.

    2014-03-01

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

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

    SciTech Connect

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

    1988-12-01

    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.

  12. Hydrothermal Monitoring in a Quiescent Volcanic Arc: Cascade Range, Northwestern United States

    NASA Astrophysics Data System (ADS)

    Gelwick, K.; Randolph-Flagg, N. G.; Crankshaw, I. M.; McCulloch, C. L.; Lundstrom, E. A.; Murveit, A. M.; Bergfeld, D.; Spicer, K.; Tucker, D.; Schmidt, M. E.; Mariner, R. H.; Evans, W.; Ingebritsen, S.

    2013-12-01

    Ongoing (1996-present) volcanic unrest near South Sister, Oregon, is accompanied by a striking set of hydrothermal anomalies, including elevated temperatures, elevated major-ion concentrations, and 3He/4He ratios as large as 8.6 RA in slightly thermal springs. These observations prompted the U.S. Geological Survey to begin a systematic hydrothermal-monitoring effort encompassing 25 sites and 10 of the highest-risk volcanoes in the Cascade Range volcanic arc, from Mount Baker near the Canadian border to Mount Lassen in northern California. A concerted effort was made to develop hourly records of temperature and (or) hydrothermal solute flux spanning multiple years, suitable for comparison with other continuous geophysical monitoring data. Monitored sites included summit-fumarole groups and springs/streams that show clear evidence of magmatic influence in the form of high 3He/4He ratios and (or) large fluxes of magmatic CO2 or heat. As of 2009-2012 measured summit-fumarole temperatures in the Cascade Range were generally near or below the local pure-water boiling point; the maximum observed superheat was <+2.5°C at Mount Baker. Temporal variability in ground-temperature records from the summit-fumarole sites is temperature-dependent, with the hottest sites tending to show less variability. Seasonal variability in the flux of hydrothermally sourced major anions from the springs varied from essentially undetectable to a factor of 5-10. This range of observed behavior owes mainly to the local climate regime, with strongly snowmelt-influenced springs and streams exhibiting more variability. As of the end of the 2012 field season, there had been 87 occurrences of local seismic energy densities ~>0.001 J/m3 during periods of hourly record. Hydrothermal responses to these small seismic stimuli were generally undetectable or ambiguous. Evaluation of multiyear to multi-decadal trends indicates that whereas the hydrothermal system at Mount St. Helens is still fast-evolving in response to the 1980-present eruptive cycle, there is no clear evidence of ongoing long-term trends in hydrothermal activity at other Cascade Range volcanoes that have been active or restless during the past century (Baker, South Sister, and Lassen). Experience gained during the Cascade Range hydrothermal-monitoring experiment informs ongoing efforts to capture entire unrest cycles at more active but generally less accessible volcanoes such as those in the Aleutian arc.

  13. Structural changes of malt proteins during boiling.

    PubMed

    Jin, Bei; Li, Lin; Liu, Guo-Qin; Li, Bing; Zhu, Yu-Kui; Liao, Liao-Ning

    2009-01-01

    Changes in the physicochemical properties and structure of proteins derived from two malt varieties (Baudin and Guangmai) during wort boiling were investigated by differential scanning calorimetry, SDS-PAGE, two-dimensional electrophoresis, gel filtration chromatography and circular dichroism spectroscopy. The results showed that both protein content and amino acid composition changed only slightly during boiling, and that boiling might cause a gradual unfolding of protein structures, as indicated by the decrease in surface hydrophobicity and free sulfhydryl content and enthalpy value, as well as reduced alpha-helix contents and markedly increased random coil contents. It was also found that major component of both worts was a boiling-resistant protein with a molecular mass of 40 kDa, and that according to the two-dimensional electrophoresis and SE-HPLC analyses, a small amount of soluble aggregates might be formed via hydrophobic interactions. It was thus concluded that changes of protein structure caused by boiling that might influence beer quality are largely independent of malt variety. PMID:19305362

  14. Enhancements of Nucleate Boiling Under Microgravity Conditions

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

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

  15. Boron isotope systematics of hydrothermal fluids from submarine hydrothermal systems

    NASA Astrophysics Data System (ADS)

    Yamaoka, K.; Hong, E.; Ishikawa, T.; Gamo, T.; Kawahata, H.

    2013-12-01

    Boron is highly mobile in submarine hydrothermal systems and useful to trace the process of water-rock reaction. In this study, we measured the boron content and isotopic composition of vent fluids collected from arc-backarc hydrothermal systems in the western Pacific. In sediment-starved hydrothermal systems (Manus Basin, Suiyo Seamount, and Mariana Trough), the boron content and isotopic composition of vent fluids are dependent on type of host rock. The end member fluids from MORB-like basalt-hosted Vienna Woods in the Manus Basin showed low boron content and high ?11B value (0.53 mM, 29.8‰), while dacite-hosted PACMANUS and the Suiyo Seamount showed high boron contents and low ?11B values (1.45 and 1.52 mM, 13.6 and 18.5‰, respectively). The Alice Springs and Forecast Vent field in the Mariana Trough showed values intermediate between them (0.72 and 0.63 mM, 19.9 and 24.0‰, respectively), reflecting reaction of seawater and basalt influenced by slab material. In phase separated hydrothermal systems (North Fiji Basin), boron content and isotopic composition of vent fluids (0.44-0.56 mM, 34.5-35.9‰) were similar to those in the Vienna Woods. Considering little fractionation of boron and boron isotope during phase separation demonstrated by the previous experimental studies, it is suggested that the host rock in the North Fiji Basin is MORB-like basalt. In sediment-hosted hydrothermal system (Okinawa Trough), the reaction with boron-enriched sediment following seawater-rock reaction resulted in significantly high boron contents and low ?11B values of vent fluids (4.4-5.9 mM, 1.5-2.6‰). The water-sediment ratio was estimated to be ~2. In spite of the different geological settings, the end member fuids from all vent fields are enriched in B relative to seawater (0.41 mM, 39.6‰) and the ?11B values are inversely propotional to the boron concentrations. It suggests that boron isotopic composition of vent fluid predominantly depends on the amount of boron originated from solid-phase.

  16. Predictive Microbiology in Hydrothermal Ecosystems

    Microsoft Academic Search

    E. L. Shock; M. E. Holland; D. Meyer-Dombard; J. P. Amend

    2004-01-01

    Metabolisms of high-temperature microorganisms are not revealed by molecular phylogenies, but, if known, could connect microbial and geochemical processes in hydrothermal ecosystems. Disequilibria among oxidation-reduction reactions, established by kinetic barriers to electron-transfer reactions, provide energy, and life provides the catalyst. In more-or-less closed systems, such as slowly-accumulating detrital sediments, life taps as much energy as conversion efficiency will allow, and

  17. Hydrothermal synthesis of zirconia nanomaterials

    Microsoft Academic Search

    R. R Piticescu; C Monty; D Taloi; A Motoc; S Axinte

    2001-01-01

    Yttria-stabilised zirconia powders and films have been obtained from Zr(IV) peroxides by hydrothermal crystallisation at temperatures in the range 125–200°C. The thermodynamic evaluation evidenced that formation of Zr(OH)5? in H2O2 solutions increases solubility of Zr (IV) hydrated species and improves the kinetics of the new phase formation by the solubilisation-reprecipitation process. Powders with crystallite sizes in the range 6–22 nm

  18. How does surface wettability influence nucleate boiling?

    NASA Astrophysics Data System (ADS)

    Phan, Hai Trieu; Caney, Nadia; Marty, Philippe; Colasson, Stéphane; Gavillet, Jérôme

    2009-05-01

    Although the boiling process has been a major subject of research for several decades, its physics still remain unclear and require further investigation. This study aims at highlighting the effects of surface wettability on pool boiling heat transfer. Nanocoating techniques were used to vary the water contact angle from 20° to 110° by modifying nanoscale surface topography and chemistry. The experimental results obtained disagree with the predictions of the classical models. A new approach of nucleation mechanism is established to clarify the nexus between the surface wettability and the nucleate boiling heat transfer. In this approach, we introduce the concept of macro- and micro-contact angles to explain the observed phenomenon. To cite this article: H.T. Phan et al., C. R. Mecanique 337 (2009).

  19. Phreatic and Hydrothermal Explosions: A Laboratory Approach

    NASA Astrophysics Data System (ADS)

    Scheu, B.; Dingwell, D. B.

    2010-12-01

    Phreatic eruptions are amongst the most common eruption types on earth. They might be precursory to another type of volcanic eruption but often they stand on their one. Despite being the most common eruption type, they also are one of the most diverse eruptions, in appearance as well as on eruption mechanism. Yet steam is the common fuel behind all phreatic eruptions. The steam-driven explosions occur when water beneath the ground or on the surface is heated by magma, lava, hot rocks, or fresh volcanic deposits (such as ignimbrites, tephra and pyroclastic-flow deposits) and result in crater, tuff rings and debris avalanches. The intense heat of such material may cause water to boil and flash to steam, thereby generating an explosion of steam, water, ash, blocks, and bombs. Another wide and important field affected by phreatic explosions are hydrothermal areas; here phreatic explosions occur every few months creating explosion craters and resemble a significant hazard to hydrothermal power plants. Despite of their hazard potential, phreatic explosions have so far been overlooked by the field of experimental volcanology. A part of their hazard potential in owned by the fact that phreatic explosions are hardly predictable in occurrence time and size as they have manifold triggers (variances in groundwater and heat systems, earthquakes, material fatigue, water level, etc..) A new set of experiments has been designed to focus on this phreatic type of steam explosion, whereas classical phreatomagmatic experiments use molten fuel-coolant interaction (e.g., Zimanowski, et al., 1991). The violent transition of the superheated water to vapour adds another degree of explosivity to the dry magmatic fragmentation, driven mostly by vesicle bursting due to internal gas overpressure. At low water fractions the fragmentation is strongly enforced by the mixture of these two effects and a large fraction of fine pyroclasts are produced, whereas at high water fraction in the sample the fragmentation is less violent as its dry counterpart. The experimental conditions used it this study (varying degree of water saturation, moderate overpressure, 200- 300°C) applies e.g. to volcanic rocks as well as country rocks at depth of about 100-800 m in a conduit or dome bearing a fraction of ground water and being heated from magma rising beneath (150-400°C). The diversity of phreatic eruptions at a volcanic system (vent) arises from the variety of host rocks, ways to seal the conduit, and to alter this material depending on the composition of volcanic gases. Here, we assess the influence of rapid decompression of the supercritical water phase in the pore space of samples, on the fragmentation behaviour. This will enable us to elucidate the characteristics of the different “fuels” for explosive fragmentation (gas overpressure, steam flashing), as well as their interplay.

  20. Hydrothermal synthesis of lithium iron phosphate cathodes

    Microsoft Academic Search

    Shoufeng Yang; Peter Y. Zavalij; M. Stanley Whittingham

    2001-01-01

    Hydrothermal methods have been successfully applied to the synthesis of lithium iron phosphates. Li3Fe2(PO4)3 was synthesized by heating at 700°C LiFePO4(OH), formed hydrothermally in an oxidizing environment. Crystalline LiFePO4 was formed in a direct hydrothermal reaction in just a few hours, and no impurities were detected. This result leads to the possibility of an easy scale-up to a commercial process.

  1. 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.

  2. Boiling on Microconfigured Composite Surfaces Enhanced

    NASA Technical Reports Server (NTRS)

    Chao, David F.

    2000-01-01

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

  3. Hydrodynamics and heat transfer during flow boiling instabilities in a single microchannel

    E-print Network

    Aussillous, Pascale

    Hydrodynamics and heat transfer during flow boiling instabilities in a single microchannel July 2008 Keywords: Boiling Microchannels Visualisation Flow boiling instabilities Heat transfer a b intensification heat removal. Flow boiling heat transfer in microchannel geometry and the associated flow

  4. Enhancement of subcooled flow boiling critical heat flux for water in tubes with internal twisted tapes under one-sided-heating conditions

    Microsoft Academic Search

    Fujio Inasak; Hideki Nariai

    1998-01-01

    The heat flux distributions, qw, at the inner cooled wall for the beam irradiated test data using swirl tubes were estimated by solving an unsteady heat conduction equation. The results were compared with the net vapor generation heat flux, qNVG. It was confirmed that the lowest heat flux at the cooled wall was lower than qNVG for all data and

  5. 1995 national heat transfer conference: Proceedings. Volume 12: Falling films; Fundamentals of subcooled flow boiling; Compact heat exchanger technology for the process industry; HTD-Volume 314

    Microsoft Academic Search

    V. Sernas; R. D. Boyd; M. K. Jensen

    1995-01-01

    The papers in the first section cover falling films and heat transfer. Papers in the second section address issues associated with heat exchangers, such as: plate-and-frame heat exchanger technology; thermal design issues; condensation; and single-phase flows. The papers in the third section deal with studies related to: the turbulent velocity field in a vertical annulus; the effects of curvature and

  6. The boiling point of stratospheric aerosols.

    NASA Technical Reports Server (NTRS)

    Rosen, J. M.

    1971-01-01

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

  7. A review on boiling heat transfer enhancement with nanofluids

    Microsoft Academic Search

    Jacqueline Barber; David Brutin; Lounes Tadrist

    2011-01-01

    There has been increasing interest of late in nanofluid boiling and its use in heat transfer enhancement. This article covers\\u000a recent advances in the last decade by researchers in both pool boiling and convective boiling applications, with nanofluids\\u000a as the working fluid. The available data in the literature is reviewed in terms of enhancements, and degradations in the nucleate\\u000a boiling

  8. Saturated pool and flow boiling from horizontal cylinders

    Microsoft Academic Search

    1987-01-01

    A study of pool and flow boiling from heated horizontal cylinders at atmospheric pressure is presented. Pool boiling heat flux vs. wall superheat boiling curves were obtained for 3.18-mm brass tubes heated by an internal flow of ethylene glycol. These curves were obtained in saturated Freon-113, n-pentane, acetone, benzene, ethanol, methanol, and isopropanol. Temperature limitations prevented operation in the film-boiling

  9. Mechanisms of Boiling in Micro-Channels: Critical Assessment

    Microsoft Academic Search

    John R. Thome; Lorenzo Consolini

    2010-01-01

    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

  10. Recent population expansion and connectivity in the hydrothermal shrimp

    E-print Network

    Teixeira, Sara

    ORIGINAL ARTICLE Recent population expansion and connectivity in the hydrothermal shrimp Rimicaris of the shrimp Rimicaris exoculata, which forms high-density local populations on hydrothermal vents along

  11. 21 CFR 872.6710 - Boiling water sterilizer.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

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

  12. CONVECTIVE HEAT TRANSFER OF BINARY MIXTURES UNDER FLOW BOILING CONDITIONS

    E-print Network

    Kandlikar, Satish

    B = binary CBD = convective boiling dominant conv = convective component f = bulk fluid fl = fluid is low-pressure flow boiling. Internal combustion engines are cooled with ethylene-glycol/water mixturesCONVECTIVE HEAT TRANSFER OF BINARY MIXTURES UNDER FLOW BOILING CONDITIONS E. V. McAssey Jr

  13. Flow boiling critical heat flux on small heated regions

    Microsoft Academic Search

    Terrence W. Simon; Pey-Shey Wu

    1993-01-01

    Often, in optical and electronic equipment, heating is concentrated in very small regions, and, because of materials constraints, cooled walls must be as thin as possible. Also, for efficiency, many high-flux cooling designs involve forced-convection boiling heat transfer. Though efficient, a design with boiling heat transfer can be difficult for it must properly account for the complexities of the boiling

  14. Fundamental issues related to flow boiling in minichannels and microchannels

    Microsoft Academic Search

    Satish G. Kandlikar

    2002-01-01

    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

  15. Performance Assessment of 239 Series Sub-cooling Heat Exchangers for the Large Hadron Collider

    E-print Network

    Riddone, G; Roussel, P; Moracchioli, R; Tavian, L

    2006-01-01

    Helium sub-cooling heat exchangers of the counter-flow type are used to minimize the vapor fraction produced in the final expansion of the 1.9 K distributed cooling loops used for cooling the superconducting magnets of the Large Hadron Collider (LHC). These components are of compact design, featuring low-pressure drop and handling very low pressure vapor at low temperature. Following a qualification phase of prototypes, a contract has been placed in European industry for the supply of 239 heat exchanger units. Different levels of extracted heat load require three different variants of heat exchangers. This paper will describe the manufacturing phase with emphasis on the main difficulties encountered to keep the production quality after a brief recall of the prototype phase. Finally, the acceptance tests performed at room temperature and at the nominal cryogenic condition at the factory and at CEA-Grenoble will be presented.

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

    E-print Network

    Iloeje, Onwuamaeze C.

    1972-01-01

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

  17. Melting Point, Boiling Point, and Symmetry

    Microsoft Academic Search

    Robert Abramowitz; Samuel H. Yalkowsky

    1990-01-01

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

  18. Boiling points of halogenated organic compounds

    Microsoft Academic Search

    Ari L. Horvath

    2001-01-01

    The normal boiling points of a number of halogenated organic compounds have been compiled from experimental measurements over three decades. Some of these chemicals have not been reported in the literature. The substances listed are halogenated aliphatic hydrocarbons, halogenated aliphatic ethers, halogenated ring (cyclic) hydrocarbons and other related compounds.

  19. Pool boiling heat transfer to electrolyte solutions

    Microsoft Academic Search

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

    2004-01-01

    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

  20. Nucleate boiling in thin liquid films

    Microsoft Academic Search

    P. J. Marto; D. K. MacKenzie; A. D. Rivers

    1977-01-01

    Experimental results are presented for distilled water, ethyl alcohol and Freon-113 at atmospheric pressure with liquid levels ranging from pool depths of 25 mm down to thin films near 0.5 mm. Pool boiling data compare favorably with the Rohsenow correlation. Temperature measurements with thermocouples and liquid crystals show that liquid level has little effect on the heat transfer coefficient above

  1. Big Bubbles in Boiling Liquids: Students' Views

    ERIC Educational Resources Information Center

    Costu, Bayram

    2008-01-01

    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…

  2. Operational control of boiling water reactor stability

    Microsoft Academic Search

    C. M. Mowry; I. Nir; D. W. Newkirk

    1995-01-01

    Boiling water reactor cores are susceptible to instabilities, which generate power oscillations. Specific reactor operating practices can provide a mechanism for control of the instability phenomenon. An axial separation of the core into a single-phase region and a two-phase region resolves the influence of axial flux shapes on core stability. This separation provides the means to derive a core stability

  3. Dynamic behavior of boiling water reactors

    Microsoft Academic Search

    March-Leuba

    1984-01-01

    A study of the basic processes involved in boiling water nuclear reactor dynamics is presented. The main emphasis of this research was placed on the physical interpretation of these processes. It is shown that this type of reactor has two regimes of operation: linear, during normal operation, and nonlinear, if they become unstable due to the thermohydraulic feedback. Both of

  4. The Plausibility of Boiling Geysers on Triton

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

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

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

    USGS Publications Warehouse

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

    1991-01-01

    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

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

    NASA Astrophysics Data System (ADS)

    Yang, Dongjiang; Xu, Yao; Wu, Dong; Sun, Yuhan

    2008-09-01

    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 °C distilled water for 300 h. The boiled mesoporous aluminosilicates have nearly the same N 2 adsorption-desorption isotherms and the same pore size distributions as those newly synthesized ones, indicating excellent hydrothermal stability. The 29Si MAS NMR spectra confirmed that PMHS and TEOS have jointly condensed and CH 3 groups have been introduced into the materials. The 27Al MAS NMR spectra indicated that Al atoms have been incorporated in the mesopore frameworks. The NH 3 temperature-programmed desorption showed strong acidity. Due to the existence of large amount of CH 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.

  7. Cryogenic Boil-Off Reduction System Testing

    NASA Technical Reports Server (NTRS)

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

    2014-01-01

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

  8. Hydrothermal Solute Flux from Ebeko Volcanic Center, Paramushir, Kuril Islands

    NASA Astrophysics Data System (ADS)

    Taran, Y.; Kalacheva, E.; Kotenko, T.; Chaplygin, I.

    2014-12-01

    Ebeko volcano on the northern part of Paramushir Island, Northern Kurils, is characterized by frequent phreatic eruptions, a strong low-temperature fumarolic activity at the summit and was the object of comprehensive volcanological and geochemical studies during the last half a century. The volcanic center is composed of several Pleistocene volcanic structures aadjacent to Ebeko and hosts a hydrothermal system with a high outflow rate of hot SO4-Cl acidic water (Upper Yurieva springs) with the current maximum temperature of ~85oC, pH 1.3 and TDS ~ 10 g/L. All discharging thermal waters are drained by the Yurieva River to the Sea of Okhotsk. The hot springs have been changing in time, generally decreasing their activity from near boiling in 1960s, with TDS ~ 20 g/L and the presence of a small steaming field at the upper part of the ~ 700 m long discharging area, to a much lower discharge rate of main vents, lower temperature and the absence of the steaming ground. The spring chemistry did not react to the Ebeko volcanic activity (14 strong phreato-magmatic events during the last 60 years).The total measured outputs of chloride and sulfur from the system last time (2006-2010) were estimated on average as 730 g/s and 980 g/s, respectively, which corresponds to the equivalent fluxes of 64 t/d of HCl and 169 t/d of SO2. These values are higher than the fumarolic volatile output from Ebeko. The estimated discharge rate of hot (85oC) water from the system with ~ 3500 ppm of chloride is about 0.3 m3/s which is much higher than the thermal water discharge from El Chichon or Copahue volcano-hydrothermal systems and among the highest hot water natural outputs ever measured for a volcano-hydrothermal system. We also report the chemical composition (major and ~ 60 trace elements including REE) of water from the main hot spring vents and the Yurieva river mouth.

  9. Hydrothermal reactions of fly ash

    SciTech Connect

    Brown, P.W.

    1991-01-01

    The reactions which occur when fly ash is treated under hydrothermal conditions will be investigated. Formation of four classes of compounds, which bracket likely fly ash compositional ranges, have been selected for study. These are calcium silicate hydrates, calcium silicosulfates, calcium aluminosulfates, and alkali aluminosilicates. The specific compounds fabricated will be determined and their stability regions assessed. As a part of stability assessment, the extent to which selected hazardous species are sequestered will be determined. Finally, the cementing properties of these compounds will be established.

  10. The Mantos Blancos copper deposit: an upper Jurassic breccia-style hydrothermal system in the Coastal Range of Northern Chile

    NASA Astrophysics Data System (ADS)

    Ramírez, L. E.; Palacios, C.; Townley, B.; Parada, M. A.; Sial, A. N.; Fernandez-Turiel, J. L.; Gimeno, D.; Garcia-Valles, M.; Lehmann, B.

    2006-06-01

    The Upper Jurassic Mantos Blancos copper deposit (500 Mt at 1.0% Cu), located in the Coastal Range of northern Chile, displays two superimposed hydrothermal events. An older phyllic alteration probably related to felsic magmatic-hydrothermal brecciation at ˜155 Ma, and younger (141-142 Ma) potassic, propylitic, and sodic alterations, coeval with dioritic and granodioritic stocks and sills, and dioritic dikes. Main ore formation is genetically related to the second hydrothermal event, and consists of hydrothermal breccias, disseminations and stockwork-style mineralization, associated with sodic alteration. Hypogene sulfide assemblages show distinctive vertical and lateral zoning, centered on magmatic and hydrothermal breccia bodies, which constitute the feeders to mineralization. A barren pyrite root zone is overlain by pyrite-chalcopyrite, and followed upwards and laterally by chalcopyrite-digenite or chalcopyrite-bornite. The assemblage digenite-supergene chalcocite characterizes the central portions of high-grade mineralization in the breccia bodies. Fluid inclusions show evidence of boiling during the potassic and sodic alteration events, which occurred at temperatures around 450-460°C and 350-410°C, and salinities between 3-53 and 13-45 wt% NaCl eq., respectively. The hydrothermal events occurred during episodic decompression due to fluid overpressuring, hydrofracturing, and sharp changes from lithostatic to hydrostatic conditions. Sulfur isotope results of hypogene sulfide minerals fall in a narrow range around 0 per mil, suggesting a dominance of magmatic sulfur. Carbon and oxygen isotopic data of calcites from propylitic alteration suggest a mantle-derived carbon and oxygen isotope fractionation due to low-temperature alteration.

  11. Hydrothermal reactions of fly ash

    SciTech Connect

    Brown, P.W.

    1992-01-01

    The reactions which occur when fly ash is treated under hydrothermal conditions will be investigated. This will be done for two 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 proposed study is that, depending on the composition of the ash and the presence of selected additives, it may 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, have been selected for study. These are calcium silicate hydrates, calcium silicosulfates, calcium aluminosulfates, and alkali aluminosilicates. The specific compounds fabricated will be determined and their stability regions assessed. As a part of stability assessment, the extent to which selected hazardous species are sequestered seal be determined. Finally, the cementing properties of these compounds will be established.

  12. Ongoing hydrothermal activities within Enceladus.

    PubMed

    Hsu, Hsiang-Wen; Postberg, Frank; Sekine, Yasuhito; Shibuya, Takazo; Kempf, Sascha; Horányi, Mihály; Juhász, Antal; Altobelli, Nicolas; Suzuki, Katsuhiko; Masaki, Yuka; Kuwatani, Tatsu; Tachibana, Shogo; Sirono, Sin-iti; Moragas-Klostermeyer, Georg; Srama, Ralf

    2015-03-12

    Detection of sodium-salt-rich ice grains emitted from the plume of the Saturnian moon Enceladus suggests that the grains formed as frozen droplets from a liquid water reservoir that is, or has been, in contact with rock. Gravitational field measurements suggest a regional south polar subsurface ocean of about 10 kilometres thickness located beneath an ice crust 30 to 40 kilometres thick. These findings imply rock-water interactions in regions surrounding the core of Enceladus. The resulting chemical 'footprints' are expected to be preserved in the liquid and subsequently transported upwards to the near-surface plume sources, where they eventually would be ejected and could be measured by a spacecraft. Here we report an analysis of silicon-rich, nanometre-sized dust particles (so-called stream particles) that stand out from the water-ice-dominated objects characteristic of Saturn. We interpret these grains as nanometre-sized SiO2 (silica) particles, initially embedded in icy grains emitted from Enceladus' subsurface waters and released by sputter erosion in Saturn's E ring. The composition and the limited size range (2 to 8 nanometres in radius) of stream particles indicate ongoing high-temperature (>90 °C) hydrothermal reactions associated with global-scale geothermal activity that quickly transports hydrothermal products from the ocean floor at a depth of at least 40 kilometres up to the plume of Enceladus. PMID:25762281

  13. Hydrothermal upgrading of algae paste in a continuous flow reactor.

    PubMed

    Patel, Bhavish; Hellgardt, Klaus

    2015-09-01

    This investigation demonstrates the utility of a novel laboratory scale continuous plug flow reactor for fast Hydrothermal Liquefaction (HTL) of microalgae in a quartz lined chamber. Reactions were carried out between 300 and 380°C and residence times of 0.5-4min. Cyclohexane was used as a co-solvent to enhance extraction and prevent char formation. Highest biocrude yield of 38wt.% was achieved at 380°C and 30s as well as Water Soluble Fraction containing up to 60wt.% matter recovered. Analysis of the biocrude showed that the extent of deoxygenation and denitrogenation after HTL varied and is dependent on the reaction conditions, Fourier Transform Infrared Spectroscopy analysis showed that biocrude contains similar functional moieties with only a small difference observed at different reaction conditions. Conversely, the Simulated Distillation and Size Exclusion Chromatography data showed that harsher conditions produced marginally better biocrude with improved boiling point profile and lower molecular weight compounds, respectively which was confirmed using Gas Chromatography-Mass Spectrometry. PMID:25908412

  14. Geochemistry of hot springs in the Tengchong hydrothermal areas, Southwestern China

    NASA Astrophysics Data System (ADS)

    Guo, Qinghai; Wang, Yanxin

    2012-02-01

    As an important volcanic geothermal region in China, Tengchong belongs to the Mediterranean-Himalayas geothermal belt and is characterized by wide distribution of volcanic rocks. Fifty-eight hydrothermal areas have been identified in Tengchong, among which the Rehai hydrothermal system is the most geothermally active. The geothermal waters from Rehai are mainly Na-HCO3-Cl and Na-HCO3 types, whereas those from the other hydrothermal areas are mainly Na-HCO3, Na-Ca-HCO3, Ca-HCO3, Ca-Mg-HCO3, Mg-Na-Ca-HCO3, and Mg-Ca-HCO3 types. Both quartz geothermometer and K-Mg geothermometer indicate that the Rehai geothermal field has higher subsurface temperatures than the other hydrothermal areas. Except for three Rehai samples, most geothermal water samples collected from Tengchong are far from the full equilibrium line in Giggenbach's triangular diagram, suggesting that the complete chemical re-equilibrium has not been achieved as these geothermal waters flow upward from reservoirs towards spring vents and possibly mix with cooler waters. Statistical analysis shows that Cl, B, Li, Rb, and Cs are the characteristic constituents of the Tengchong geothermal waters, and the good linear relations among these elements in the Rehai geothermal waters reflect the existence of a deep parent geothermal liquid (PGL) below Rehai. An enthalpy-chloride diagram of the Rehai geothermal waters suggests that the parent geothermal liquid has Cl-concentration of 291 mg/L and enthalpy of 1495 J/g. The PGL ascends to the surface through different channels and may cool by conduction of heat to reservoir host rocks, by boiling, or by mixing with cooler shallow groundwaters.

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

    SciTech Connect

    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

    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.

  16. Unorthodox bubbles when boiling in cold water.

    PubMed

    Parker, Scott; Granick, Steve

    2014-01-01

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

  17. Unorthodox bubbles when boiling in cold water

    NASA Astrophysics Data System (ADS)

    Parker, Scott; Granick, Steve

    2014-01-01

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

  18. Enhanced Droplet Control by Transition Boiling

    PubMed Central

    Grounds, Alex; Still, Richard; Takashina, Kei

    2012-01-01

    A droplet of water on a heated surface can levitate over a film of gas produced by its own evaporation in the Leidenfrost effect. When the surface is prepared with ratchet-like saw-teeth topography, these droplets can self-propel and can even climb uphill. However, the extent to which the droplets can be controlled is limited by the physics of the Leidenfrost effect. Here, we show that transition boiling can be induced even at very high surface temperatures and provide additional control over the droplets. Ratchets with acute protrusions enable droplets to climb steeper inclines while ratchets with sub-structures enable their direction of motion to be controlled by varying the temperature of the surface. The droplets' departure from the Leidenfrost regime is assessed by analysing the sound produced by their boiling. We anticipate these techniques will enable the development of more sophisticated methods for controlling small droplets and heat transfer. PMID:23056912

  19. Dynamics of the Yellowstone hydrothermal system

    USGS Publications Warehouse

    Hurwitz, Shaul; Lowenstern, Jacob B.

    2014-01-01

    The Yellowstone Plateau Volcanic Field is characterized by extensive seismicity, episodes of uplift and subsidence, and a hydrothermal system that comprises more than 10,000 thermal features, including geysers, fumaroles, mud pots, thermal springs, and hydrothermal explosion craters. The diverse chemical and isotopic compositions of waters and gases derive from mantle, crustal, and meteoric sources and extensive water-gas-rock interaction at variable pressures and temperatures. The thermal features are host to all domains of life that utilize diverse inorganic sources of energy for metabolism. The unique and exceptional features of the hydrothermal system have attracted numerous researchers to Yellowstone beginning with the Washburn and Hayden expeditions in the 1870s. Since a seminal review published a quarter of a century ago, research in many fields has greatly advanced our understanding of the many coupled processes operating in and on the hydrothermal system. Specific advances include more refined geophysical images of the magmatic system, better constraints on the time scale of magmatic processes, characterization of fluid sources and water-rock interactions, quantitative estimates of heat and magmatic volatile fluxes, discovering and quantifying the role of thermophile microorganisms in the geochemical cycle, defining the chronology of hydrothermal explosions and their relation to glacial cycles, defining possible links between hydrothermal activity, deformation, and seismicity; quantifying geyser dynamics; and the discovery of extensive hydrothermal activity in Yellowstone Lake. Discussion of these many advances forms the basis of this review.

  20. Surface effects on pool boiling CHF

    Microsoft Academic Search

    Klemen Ferjan?i?; Iztok Golobi?

    2002-01-01

    The influence of the surface of horizontally and vertically oriented ribbon heaters made of stainless steel 302 or steel 1010 on pool boiling CHF in FC-72 or H2O was studied. The ribbon was 50 mm long, 5 mm high and 76.4?m thick. Surface treatment was performed with different sandpapers and etching in diluted acid. In the centre line average Ra

  1. Numerical standards for flow-boiling analysis

    Microsoft Academic Search

    W. T. Hancox; S. Banerjee

    1977-01-01

    A strategy for flow-boiling analysis development is illustrated through application to the equal-velocity and equal-temperature model. Particular emphasis is placed on the role of benchmark solutions to standard problems selected to isolate effects associated with analyses of the blowdown and emergency cooling phases of postulated loss-of-coolant accidents in nuclear power reactors. A benchmark solution procedure, based on the method of

  2. Seawater bicarbonate removal during hydrothermal circulation

    NASA Astrophysics Data System (ADS)

    Proskurowski, G. K.; Seewald, J.; Sylva, S. P.; Reeves, E.; Lilley, M. D.

    2013-12-01

    High temperature fluids sampled at hydrothermal vents represent a complex alteration product of water-rock reactions on a multi-component mixture of source fluids. Sources to high-temperature hydrothermal samples include the 'original' seawater present in the recharge limb of circulation, magmatically influenced fluids added at depth as well as any seawater entrained during sampling. High-temperature hydrothermal fluids are typically enriched in magmatic volatiles, with CO2 the dominant species, characterized by concentrations of 10's-100's of mmol/kg (1, 2). Typically, the high concentration of CO2 relative to background seawater bicarbonate concentrations (~2.3 mmol/kg) obscures a full analysis of the fate of seawater bicarbonate during high-temperature hydrothermal circulation. Here we present data from a suite of samples collected over the past 15 years from high-temperature hydrothermal vents at 9N, Endeavour, Lau Basin, and the MAR that have endmember CO2 concentrations less than 10 mmol/kg. Using stable and radiocarbon isotope measurements these samples provide a unique opportunity to examine the balance between 'original' seawater bicarbonate and CO2 added from magmatic sources. Multiple lines of evidence from multiple hydrothermal settings consistently points to the removal of ~80% of the 'original' 2.3 mmol/kg seawater bicarbonate. Assuming that this removal occurs in the low-temperature, 'recharge' limb of hydrothermal circulation, this removal process is widely occurring and has important contributions to the global carbon cycle over geologic time. 1. Lilley MD, Butterfield DA, Lupton JE, & Olson EJ (2003) Magmatic events can produce rapid changes in hydrothermal vent chemistry. Nature 422(6934):878-881. 2. Seewald J, Cruse A, & Saccocia P (2003) Aqueous volatiles in hydrothermal fluids from the Main Endeavour Field, northern Juan de Fuca Ridge: temporal variability following earthquake activity. Earth and Planetary Science Letters 216(4):575-590.

  3. CFD simulation of DEBORA boiling experiments

    NASA Astrophysics Data System (ADS)

    Rzehak, Roland; Krepper, Eckhard

    2012-08-01

    In this work we investigate the present capabilities of computational fluid dynamics for wall boiling. The computational model used combines the Euler/Euler two-phase flow description with heat flux partitioning. This kind of modeling was previously applied to boiling water under high pressure conditions relevant to nuclear power systems. Similar conditions in terms of the relevant non-dimensional numbers have been realized in the DEBORA tests using dichlorodifluoromethane (R12) as the working fluid. This facilitated measurements of radial profiles for gas volume fraction, gas velocity, bubble size and liquid temperature as well as axial profiles of wall temperature. After reviewing the theoretical and experimental basis of correlations used in the ANSYS CFX model used for the calculations, we give a careful assessment of the necessary recalibrations to describe the DEBORA tests. The basic CFX model is validated by a detailed comparison to the experimental data for two selected test cases. Simulations with a single set of calibrated parameters are found to give reasonable quantitative agreement with the data for several tests within a certain range of conditions and reproduce the observed tendencies correctly. Several model refinements are then presented each of which is designed to improve one of the remaining deviations between simulation and measurements. Specifically we consider a homogeneous MUSIG model for the bubble size, modified bubble forces, a wall function for turbulent boiling flow and a partial slip boundary condition for the liquid phase. Finally, needs for further model developments are identified and promising directions discussed.

  4. POOL BOILING OF HIGH-FREQUENCY CONDUCTORS

    SciTech Connect

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

    2001-01-01

    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.

  5. Boiling radial flow in fractures of varying wall porosity

    SciTech Connect

    Barnitt, Robb Allan

    2000-06-01

    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.

  6. Catastrophic volcanic collapse: relation to hydrothermal processes.

    PubMed

    López, D L; Williams, S N

    1993-06-18

    Catastrophic volcanic collapse, without precursory magmatic activity, is characteristic of many volcanic disasters. The extent and locations of hydrothermal discharges at Nevado del Ruiz volcano, Colombia, suggest that at many volcanoes collapse may result from the interactions between hydrothermal fluids and the volcanic edifice. Rock dissolution and hydrothermal mineral alteration, combined with physical triggers such as earth-quakes, can produce volcanic collapse. Hot spring water compositions, residence times, and flow paths through faults were used to model potential collapse at Ruiz. Caldera dimensions, deposits, and alteration mineral volumes are consistent with parameters observed at other volcanoes. PMID:17793659

  7. Effect of Residual Noncondensables on Pressurization and Pressure Control of a Zero-Boil-Off Tank in Microgravity

    NASA Technical Reports Server (NTRS)

    Kassemi, Mohammad; Hylton, Sonya; Kartizova, Olga

    2013-01-01

    The Zero-Boil-Off Tank (ZBOT) Experiment is a small-scale experiment that uses a transparent ventless Dewar and a transparent simulant phase-change fluid to study sealed tank pressurization and pressure control with applications to on-surface and in-orbit storage of propellant cryogens. The experiment will be carried out under microgravity conditions aboard the International Space Station in the 2014 timeframe. This paper presents preliminary results from ZBOT's ground-based research that focuses on the effects of residual noncondensable gases in the ullage on both pressurization and pressure reduction trends in the sealed Dewar. Tank pressurization is accomplished through heating of the test cell wall in the wetted and un-wetted regions simultaneously or separately. Pressure control is established through mixing and destratification of the bulk liquid using a temperature controlled forced jet flow with different degrees of liquid jet subcooling. A Two-Dimensional axisymmetric two-phase CFD model for tank pressurization and pressure control is also presented. Numerical prediction of the model are compared to experimental 1g results to both validate the model and also indicate the effect of the noncondensable gas on evolution of pressure and temperature distributions in the ullage during pressurization and pressure control. Microgravity simulations case studies are also performed using the validated model to underscore and delineate the profound effect of the noncondensables on condensation rates and interfacial temperature distributions with serious implications for tank pressure control in reduced gravity.

  8. Hyperbaric Hydrothermal Atomic Force Microscope

    DOEpatents

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

    2003-07-01

    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.

  9. Hyperbaric hydrothermal atomic force microscope

    DOEpatents

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

    2002-01-01

    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.

  10. Stability monitoring for boiling water reactors

    NASA Astrophysics Data System (ADS)

    Cecenas-Falcon, Miguel

    1999-11-01

    A methodology is presented to evaluate the stability properties of Boiling Water Reactors based on a reduced order model, power measurements, and a non-linear estimation technique. For a Boiling Water Reactor, the feedback reactivity imposed by the thermal-hydraulics has an important effect in the system stability, where the dominant contribution to this feedback reactivity is provided by the void reactivity. The feedback reactivity is a function of the operating conditions of the system, and cannot be directly measured. However, power measurements are relatively easy to obtain from the nuclear instrumentation and process computer, and are used in conjunction with a reduced order model to estimate the gain of the thermal-hydraulics feedback using an Extended Kalman Filter. The reduced order model is obtained by estimating the thermal-hydraulic transfer function from the frequency-domain BWR code LAPUR, and the stability properties are evaluated based on the pair of complex conjugate eigenvalues. Because of the recursive nature of the Kalman Filter, an estimate of the decay ratio is generated every sampling time, allowing continuous estimation of the stability parameters. A test platform based on a nuclear-coupled boiling channel is developed to validate the capability of the BWR stability monitoring methodology. The thermal-hydraulics for the boiling channel is modeled and coupled with neutron kinetics to analyze the non-linear dynamics of the closed-loop system. The model uses point kinetics to study core-wide oscillations, and normalized modal kinetics are introduced to study out-of-phase oscillations. The coolant flow dynamics is dominant in the power fluctuations observed by in-core nuclear instrumentation, and additive white noise is added to the solution for the channel flow in the thermal-hydraulic model to generate noisy power time series. The operating conditions of the channel can be modified to accommodate a wide range of stability conditions. Autoregressive analysis performed with the computer-generated series agrees with the stability properties of the boiling channel and with the results of the reduced order model method. Finally, a method to separate the fundamental and first harmonic modes form LPRM readings is presented and tested with computer simulations and plant data.

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

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2008-12-01

    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.

  13. A review on boiling heat transfer enhancement with nanofluids

    PubMed Central

    2011-01-01

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

  14. Magmatic intrusions and hydrothermal systems on Mars

    NASA Technical Reports Server (NTRS)

    Gulick, V. C.

    1992-01-01

    We are continuing our investigation of Martian hydrothermal systems and the formation of fluvial valleys on Mars. Here we present our initial numerical modeling results of hydrothermal systems associated with magmatic intrusions on Mars. To model such hydrothermal systems, we consider single, cylindrical intrusions of 4 km height 2 km below the surface. Our preliminary results of modeling hydrothermal systems associated with magmatic intrusions in the Martian environment suggest that such systems, if associated with intrusions of several 10(exp 2) km(exp 3) or larger, in the presence of permeable, water-rich subsurface should be able to provide adequate discharges of water over the time periods needed to form fluvial valleys. However, it is important to note that the amount of water ultimately available for erosion also depends on the surface and subsurface lithology.

  15. Biomass reforming processes in hydrothermal media

    E-print Network

    Peterson, Andrew A

    2009-01-01

    While hydrothermal technologies offer distinct advantages in being able to process a wide variety of biomass feedstocks, the composition of the feedstock will have a large effect on the processing employed. This thesis ...

  16. Chemical environments of submarine hydrothermal systems

    NASA Technical Reports Server (NTRS)

    Shock, Everett L.

    1992-01-01

    Perhaps because black-smoker chimneys make tremendous subjects for magazine covers, the proposal that submarine hydrothermal systems were involved in the origin of life has caused many investigators to focus on the eye-catching hydrothermal vents. In much the same way that tourists rush to watch the spectacular eruptions of Old Faithful geyser with little regard for the hydrology of the Yellowstone basin, attention is focused on the spectacular, high-temperature hydrothermal vents to the near exclusion of the enormous underlying hydrothermal systems. Nevertheless, the magnitude and complexity of geologic structures, heat flow, and hydrologic parameters which characterize the geyser basins at Yellowstone also characterize submarine hydrothermal systems. However, in the submarine systems the scale can be considerably more vast. Like Old Faithful, submarine hydrothermal vents have a spectacular quality, but they are only one fascinating aspect of enormous geologic systems operating at seafloor spreading centers throughout all of the ocean basins. A critical study of the possible role of hydrothermal processes in the origin of life should include the full spectrum of probable environments. The goals of this chapter are to synthesize diverse information about the inorganic geochemistry of submarine hydrothermal systems, assemble a description of the fundamental physical and chemical attributes of these systems, and consider the implications of high-temperature, fluid-driven processes for organic synthesis. Information about submarine hydrothermal systems comes from many directions. Measurements made directly on venting fluids provide useful, but remarkably limited, clues about processes operating at depth. The oceanic crust has been drilled to approximately 2.0 km depth providing many other pieces of information, but drilling technology has not allowed the bore holes and core samples to reach the maximum depths to which aqueous fluids circulate in oceanic crust. Such determinations rely on studies of pieces of deep oceanic crust uplifted by tectonic forces such as along the Southwest Indian Ridge, or more complete sections of oceanic crust called ophiolite sequences which are presently exposed on continents owing to tectonic emplacement. Much of what is thought to happen in submarine hydrothermal systems is inferred from studies of ophiolite sequences, and especially from the better-exposed ophiolites in Oman, Cyprus and North America. The focus of much that follows is on a few general features: pressure, temperature, oxidation states, fluid composition and mineral alteration, because these features will control whether organic synthesis can occur in hydrothermal systems.

  17. Hydrothermal Manganese Mineralization Near the Samoan Hotspot

    NASA Astrophysics Data System (ADS)

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

    2006-12-01

    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.

  18. Pb Bi-cooled direct contact boiling water small reactor

    Microsoft Academic Search

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

    2005-01-01

    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

  19. Specific features of the modeling of boiling-fluid flows

    Microsoft Academic Search

    O. E. Ivashnev

    2008-01-01

    Experiments show that in low-and high-velocity flows the boiling process is fundamentally different: in the former, the fluid\\u000a boils on the walls, and in the latter in the volume. In high-velocity flows, the boiling intensity is orders of magnitude\\u000a greater. In modeling fast and slow flows, the number of bubbles, which is a free parameter of the model and must

  20. Pool Boiling Heat Transfer in Dilute Water\\/Triethyleneglycol Solutions

    Microsoft Academic Search

    S. A. Alavi Fazel; A. A. Safekordi; M. Jamialahmadi

    2009-01-01

    Boiling of water\\/triethyleneglycol (TEG) binary solution has a wide-ranging application in the gas processing engineering. Design, operation and optimization of the involved boilers require accurate prediction of boiling heat transfer coefficient between surface and solution. In this investigation, nucleate pool boiling heat transfer coefficient has been experimentally measured on a horizontal rod heater in water\\/TEG binary solutions in a wide

  1. Rare earth element systematics in hydrothermal fluids

    Microsoft Academic Search

    Annie Michard

    1989-01-01

    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

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

    Microsoft Academic Search

    J. L. Xu; Y. H. Gan

    2007-01-01

    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,

  3. THE EFFECTS OF NUCLEATE BOILING VERSUS FILM BOILING ON HEAT TRANSFER IN POWER BOILER TUBES

    Microsoft Academic Search

    H. S. Swenson; J. R. Carver; G. Szoeke

    1962-01-01

    In large, subcritical pressure, once-through power boilers, heat is ; transferred to steam and water mixtures ranging in steam quality from zero per ; cent at the bottom of the furnace to 100 per cent at the top. In order to ; provide design information for this type of boiler, heat-transfer coefficients ; for forced convection film boiling were determined

  4. Study of hydrothermal channels based on near-bottom magnetic prospecting: Application to Longqi hydrothermal area

    NASA Astrophysics Data System (ADS)

    Tao, W.; Tao, C.; Li, H.; Zhaocai, W.; Jinhui, Z.; Qinzhu, C.; Shili, L.

    2014-12-01

    Mid-ocean ridges, largely present far from the continental plates, are characterized by complex geological structures and numerous hydrothermal systems with complex controlling factors. Exploring seafloor sulfide resources for industrial and scientific applications is a challenge. With the advent of geophysical surveys for seabed investigation, near-bottom magnetic prospecting, which yields shallow geological structure, is an efficient method for investigating active and inactive hydrothermal fields and for researching the structure of hydrothermal systems (Tivey et al., 1993, 1996?German et al., 2008). We collected near-bottom magnetic data in the Longqi hydrothermal area, located in the southwest Indian ridge (49.6° E; Zhu et al., 2010; Tao et al., 2014), using the autonomous benthic explorer, an autonomous underwater vehicle, during the second leg of the Chinese cruise DY115-19 on board R/V DaYangYiHao. Based on the results of the intensity of the spatial differential vector method (Seaman et al., 1993), we outline the hydrothermal alternation zone. By building models, we subsequently infer a fault along the discovered hydrothermal vents; this fault line may be connected to a detachment fault (Zhao et al., 2013). In addition, we discuss the channels of the hydrothermal circulation system (Figure 1), and presume that heat was conducted to the sea subsurface by the detachment fault; the aqueous fluid that infiltrated the fault is heated and conveyed to the seafloor, promoting the circulation of the hydrothermal system.

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

    NASA Astrophysics Data System (ADS)

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

    2003-12-01

    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.

  6. Bubble departure size in flow boiling

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  7. 79 FR 61943 - Economic Simplified Boiling-Water Reactor Design Certification

    Federal Register 2010, 2011, 2012, 2013, 2014

    2014-10-15

    ...Economic Simplified Boiling Water Reactor Design Certification...Economic Simplified Boiling-Water Reactor Design Certification...General Electric Boiling Water Reactor Detect and Suppress Solution--Confirmation Density,''...

  8. A method of correlating heat transfer data for surface boiling of liquids

    E-print Network

    Rohsenow, Warren M.

    1951-01-01

    A method based an a logical uxplanation of the meani of beat transfer associated with the boiling process is presented for correlating heat transfer data for nucleate boiling of liquids for the case of pool boiling. Tbe ...

  9. Cooling of small electronic devices by boiling under microgravity

    NASA Astrophysics Data System (ADS)

    Straub, J.; Winter, J.; Picker, G.; Zell, M.

    The boiling heat transfer on a miniature heater has been measured under microgravity conditions during the IML 2 mission and under earth gravity after the mission in 1994. These experiments are simulations for the direct cooling of small electronic devices by boiling heat transfer, which becomes very important due to high thermal loads of modern electronic components.

  10. Prospects of confined flow boiling in thermal management of microsystems

    Microsoft Academic Search

    S. Lin; K. Sefiane; J. R. E. Christy

    2002-01-01

    This paper presents a review of prospects of confined flow boiling in future thermal management of microsystems such as microelectronics, optoelectronics, and microreactors. With the trend towards miniaturisation, heat removal has become the major bottleneck in microsystem development. In view of this we briefly discuss available cooling strategies, then assess studies of confined flow boiling and potential applications in heat

  11. Thermoelectric generator utilizing boiling-condensation (experiment and modeling)

    Microsoft Academic Search

    Ren Cai Chu; Kanichi KADOTANI; Toshiya SHINTANI; Toshinobu TANIMURA; Tsutomu HATANAKA; S. Nishio

    2003-01-01

    A thermoelectric generator utilizing boiling and condensation of thermal medium circulating between a boiler and condensers was proposed in this study. Fuluorinert (FC5312) was used as the thermal medium (working fluid). A vertical tube type boiler with an outside forced convective heat transfer and an inside natural convective boiling was chosen. In order to increase the hot side temperature of

  12. System for reliquefying boil-off vapor from liquefied gas

    Microsoft Academic Search

    Delahunty

    1973-01-01

    Apparatus and processes are described for recondensing boil-off vapor from an insulated storage tank containing a liquefied gas, such as liquefied natural gas, so that it continues to comprise a part of the stored liquefied gas. Boil-off vapor is recondensed by refrigeration obtained from expansion of a liquefied gas stream withdrawn from the storage tank. The expanded stream, as a

  13. Numerical simulations of pool-boiling heat transfer

    Microsoft Academic Search

    Vijay K. Dhir

    2001-01-01

    Boiling has been studied extensiely during the last half of the 20th century. Many correlations and semimechanistic models hae also been deeloped forarious modes of boiling. Howeer, due to the complexity inoled in modeling continuously eoling ¤apor ) liquid interfaces, unrealistic assumptions are often made in deelopingarious models. With the adances of recent years in the area of computational science

  14. Boiling helium heat transfer characteristics in narrow cooling channel

    Microsoft Academic Search

    M. Nishi; T. Ando; T. Hiyama; T. Kato; S. Shimamoto

    1983-01-01

    For design of a stable superconducting magnet with pool cooling method, the size of the cooling channel is one of the important factors to determine its overall current density. The authors measured the steady state boiling helium heat transfer characteristics in a 600 mm long vertical cooling channel. The result shows that heat transfer characteristics in film boiling region do

  15. Boiling heat transfer and bubble dynamics in microgravity

    Microsoft Academic Search

    Johannes Straub

    2001-01-01

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

  16. 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

  17. 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

  18. Explosive Boiling at Very Low Heat Fluxes: A Microgravity Phenomenon

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

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

  19. SIMULATED BOILING WATER REACTOR AND SUPERHEAT REACTOR CORROSION FACILITY

    Microsoft Academic Search

    M. D. Fitzsimmons; W. L. Pearl; M. Siegler

    1963-01-01

    A versatile boiling water and superheated steam facility was developed ; for out-of-pile corrosion testing of materials that are being used and considered ; for application in boiling water reactor (BWR) and superheat reactor (SHR) ; systems. The following capabilities were achieved: simulation of the various ; environments (other than irradiation) that would contact materials in a Dresden ; type

  20. 77 FR 3009 - Knowledge and Abilities Catalog for Nuclear Power Plant Operators: Advanced Boiling Water Reactors

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-20

    ...Abilities Catalog for Nuclear Power Plant Operators: Advanced Boiling Water Reactors AGENCY: Nuclear Regulatory Commission...Abilities Catalog for Nuclear Power Plant Operators: Advanced Boiling Water Reactors.'' DATES:...

  1. Hydrothermal alteration in the EPF replacement wells, Olkaria Geothermal field, Kenya

    SciTech Connect

    Mungania, J. [Kenya Power & Lighting Co. Ltd., Naivasha (Kenya)

    1996-12-31

    Olkaria Geothermal area is located in the central sector of the Kenya, Rift Valley. A 45MW Geothermal power station has been operational at Olkaria since 1985 supplied by 22 of the 26 wells drilled in the Eastern production field (EPF). Between 1988 and 1993, eight more wells referred to as {open_quote}replacement wells{close_quote} were drilled in the same field to boost steam supply to the station. Petrographic analyses of the drill cuttings is usually done to determine detail stratigraphy of the field, extends of hydrothermal activity, subsurface structures and other parameters which may influence production potential of a well. Analyses of the drill cuttings from the EPF wells show that: Variations in the whole rock alteration intensities correlate with differences in rocktypes. Permeable horizons, especially the productive feeder zones are well marked by enhanced hydrothermal minerals depositions, mainly quartz, calcite, pyrite and epidote. Other aspects of state of reservoir like boiling are signified by presence of bladed calcite.

  2. Ancient Hydrothermal Springs in Arabia Terra, Mars

    NASA Technical Reports Server (NTRS)

    Oehler, Dorothy Z.; Allen, Carlton C.

    2008-01-01

    Hydrothermal springs are important astrobiological sites for several reasons: 1) On Earth, molecular phylogeny suggests that many of the most primitive organisms are hyperthermophiles, implying that life on this planet may have arisen in hydrothermal settings; 2) on Mars, similar settings would have supplied energy- and nutrient-rich waters in which early martian life may have evolved; 3) such regions on Mars would have constituted oases of continued habitability providing warm, liquid water to primitive life forms as the planet became colder and drier; and 4) mineralization associated with hydrothermal settings could have preserved biosignatures from those martian life forms. Accordingly, if life ever developed on Mars, then hydrothermal spring deposits would be excellent localities in which to search for morphological or chemical remnants of that life. Previous attempts to identify martian spring deposits from orbit have been general or limited by resolution of available data. However, new satellite imagery from HiRISE has a resolution of 28 cm/pixel which allows detailed analysis of geologic structure and geomorphology. Based on these new data, we report several features in Vernal Crater, Arabia Terra that we interpret as ancient hydrothermal springs.

  3. Peptide synthesis in early Earth hydrothermal systems.

    PubMed

    Lemke, Kono H; Rosenbauer, Robert J; Bird, Dennis K

    2009-03-01

    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 degrees C with those obtained at more moderate temperatures (160 degrees 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. PMID:19371157

  4. Sample Return from Ancient Hydrothermal Springs

    NASA Technical Reports Server (NTRS)

    Allen, Carlton C.; Oehler, Dorothy Z.

    2008-01-01

    Hydrothermal spring deposits on Mars would make excellent candidates for sample return. Molecular phylogeny suggests that that life on Earth may have arisen in hydrothermal settings [1-3], and on Mars, such settings not only would have supplied energy-rich waters in which martian life may have evolved [4-7] but also would have provided warm, liquid water to martian life forms as the climate became colder and drier [8]. Since silica, sulfates, and clays associated with hydrothermal settings are known to preserve geochemical and morphological remains of ancient terrestrial life [9-11], such settings on Mars might similarly preserve evidence of martian life. Finally, because formation of hydrothermal springs includes surface and subsurface processes, martian spring deposits would offer the potential to assess astrobiological potential and hydrological history in a variety of settings, including surface mineralized terraces, associated stream deposits, and subsurface environments where organic remains may have been well protected from oxidation. Previous attempts to identify martian spring deposits from orbit have been general or limited by resolution of available data [12-14]. However, new satellite imagery from HiRISE has a resolution of 28 cm/pixel, and based on these new data, we have interpreted several features in Vernal Crater, Arabia Terra as ancient hydrothermal springs [15, 16].

  5. Permeability Reduction in Passively Degassing Seawater-dominated Volcanic-hydrothermal systems: Processes and Perils on Raoul Island, Kermadecs (NZ)

    NASA Astrophysics Data System (ADS)

    Christenson, B. W.; Reyes, A. G.

    2014-12-01

    The 2006 eruption from Raoul Island occurred apparently in response to local tectonic swarm activity, but without any precursory indication of volcanic unrest within the hydrothermal system on the island. The eruption released some 200 T of SO2, implicating the involvement of a deep magmatic vapor input into the system during/prior to the event. In the absence of any recognized juvenile material in the eruption products, previous explanations for this eruptive event focused on this vapor being a driving force for the eruption. In 2004, at least 80 T/d of CO2 was escaping from the hydrothermal system, but mainly through areas that did not correspond to the 2006 eruption vents. The lack of a pre-eruptive hydrothermal system response related to the seismic event in 2006 can be explained by the presence of a hydrothermal mineralogic seal in the vent area of the volcano. Evidence for the existence of such a seal was found in eruption deposits in the form of massive fracture fillings of aragonite, calcite and anhydrite. Fluid inclusion homogenization temperatures in these phases range from ca. 140 °C to 220 °C which, for pure water indicate boiling point depths of between 40 and 230 m assuming a cold hydrostatic pressure constraint. Elevated pressures behind this seal are consistent with the occurrence of CO2 clathrates in some inclusion fluids, indicating CO2 concentrations approaching 1 molal in the parent fluids. Reactive transport modeling of magmatic volatile inputs into what is effectively a seawater-dominated hydrothermal system provide valuable insights into seal formation. Carbonate mineral phases ultimately come to saturation along this flow path, but we suggest that focused deposition of the observed massive carbonate seal is facilitated by near-surface boiling of these CO2-enriched altered seawaters, leading to large degrees of supersaturation which are required for the formation of aragonite. As the seal grew and permeability declined, pore pressures increased until a state of critical stress was achieved. The eruption of 2006 was probably triggered by further deep release of magmatic volatiles brought about by intense shaking of the local tectonic swarm event, and the addition of these gases further increased pore pressures, and ultimately led to the failure of the already critically stressed seal.

  6. Hydrothermal origin of halogens at Home Plate, Gusev Crater

    USGS Publications Warehouse

    Schmidt, M.E.; Ruff, S.W.; McCoy, T.J.; Farrand, W.H.; Johnson, J.R.; Gellert, Ralf; Ming, D.W.; Morris, R.V.; Cabrol, N.; Lewis, K.W.; Schroeder, C.

    2008-01-01

    In the Inner Basin of the Columbia Hills, Gusev Crater is Home Plate, an 80 m platform of layered elastic rocks of the Barnhill class with microscopic and macroscopic textures, including a bomb sag, suggestive of a phreatomagmatic origin. We present data acquired by the Spirit Mars Exploration Rover by Alpha Particle X-Ray Spectrometer (APXS), Mo??ssbauer Spectrometer, Miniature Thermal Emission Spectrometer (Mini-TES), and Panoramic Camera (Pancam) for the Barnhill class rocks and nearby vesicular Irvine class basalts. In major element concentrations (e.g., SiO2, Al2O3, MgO, and FeO*), the two rock classes are similar, suggesting that they are derived from a similar magmatic source. The Barnhill class, however, has higher abundances of Cl, Br, Zn, and Ge with comparable SO3 to the Irvine basalts. Nanophase ferric oxide (np ox) and volcanic glass were detected in the Barnhill class rocks by Mo??ssbauer and Mini-TES, respectively, and imply greater alteration and cooling rates in the Barnhill than in the Irvine class rocks. The high volatile elements in the Barnhill class agree with volcanic textures that imply interaction with a briny groundwater during eruption and (or) by later alteration. Differences in composition between the Barnhill and Irvine classes allow the fingerprinting of a Na-Mg-Zn-Ge-Cl-Br (??Fe ?? Ca ?? CO2) brine with low S. Nearby sulfate salt soils of fumarolic origin may reflect fractionation of an acidic S-rich vapor during boiling of a hydrothermal brine at depth. Persistent groundwater was likely present during and after the formation of Home Plate. Copyright 2008 by the American Geophysical Union.

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

    PubMed

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

    2015-03-01

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

  8. Calibrated Hydrothermal Parameters, Barrow, Alaska, 2013

    DOE Data Explorer

    Atchley, Adam; Painter, Scott; Harp, Dylan; Coon, Ethan; Wilson, Cathy; Liljedahl, Anna; Romanovsky, Vladimir

    A model-observation-experiment process (ModEx) is used to generate three 1D models of characteristic micro-topographical land-formations, which are capable of simulating present active thaw layer (ALT) from current climate conditions. Each column was used in a coupled calibration to identify moss, peat and mineral soil hydrothermal properties to be used in up-scaled simulations. Observational soil temperature data from a tundra site located near Barrow, AK (Area C) is used to calibrate thermal properties of moss, peat, and sandy loam soil to be used in the multiphysics Advanced Terrestrial Simulator (ATS) models. Simulation results are a list of calibrated hydrothermal parameters for moss, peat, and mineral soil hydrothermal parameters.

  9. Hydrothermal Ni Prospectivity Analysis of Tasmania, Australia

    NASA Astrophysics Data System (ADS)

    Gonzalez-Alvalez, I.; Porwal, A.; McCuaig, T. C.

    2009-04-01

    Tasmania contains the largest hydrothermal Ni deposit in Australia: Avebury (118,000 Ni metal tonnes). This Devonian deposit was discovered in 1998 in the Dundas geological region, and represents an outstanding example of hydrothermal Nickel sulphide mineralization type. Avebury Ni deposit is a system of hydrothermal Ni ore bodies. It is hosted by an intensely altered and serpentinized Cambrian ultramafic suite in close proximity to major structural features. The mineralization is considered to be the result of hydrothermal scavenging and remobilization of the original nickel content of the mafic/ultramafic rocks in the area, and subsequent re-deposition in favourable structural traps. The mineralization is spatially and temporally related to a large granitic intrusion, the Heemskirk Granite, which is considered to be the source of the hydrothermal fluids as well as the necessary thermal gradients for the circulation of the fluids. Tasmania is largely covered by the Jurassic Ferrar Continental Flood basalt Province in the East and presents early Cambrian ultramafic-mafic complexes in the West. The Ferrar large igneous province (LIP) extends over to Antarctica and is related to the Karoo Province in southern Africa that comprises tholeiitic lava flows, sills, and dyke swarms. The Ferrar and Karoo provinces were associated with the same thermal anomaly that was involved in the break up of Gondwana. The presence of mafic/ultramafic rocks in favourable lithological packages and/or structural traps along the margins of the province, as well as several prospective reduced or reactive sedimentary packages within and around the Ferrar indicate that this LIP could represent a novel promising ground for Ni hydrothermal exploration. Based on this prospective geological background, a prospectivity analysis for hydrothermal Ni deposits was carried out on regional scale for the entire state of Tasmania. A conceptual model of hydrothermal nickel mineral system was used to identify the following as the most important exploration criteria for hydrothermal nickel deposits: (i) potential nickel sources, (ii) heat and fluid sources, (iii) permeable transportation channels for circulating hydrothermal fluids, and (iv) prospective lithological and structural traps conducive for sulphur saturation and deposition of nickel sulphides. Available public domain exploration datasets were processed using GIS functionalities to derive a series of derivative GIS layers that could be used as proxies for each of the above exploration criteria. These included komatiites/picrites/mafic-ultramafic rocks formed from magma with >7% MgO, large igneous province; major faults; crustal contamination, older sulphur bearing rock suites, redox gradients and/or reduced fluids highly concentrated in chloride etc.. A two-pronged approach involving GIS-assisted manual prospectivity analysis and GIS-based (automated) prospectivity analysis was used for identifying the most prospective ground for hydrothermal nickel deposits in Tasmania. The manual analysis involved a conceptual review of all geological regions of the state, while the GIS-based automated approach used a spatial fuzzy model. The results of the two analyses were subsequently integrated and, after a detailed geological follow-up study, were used to generate a hydrothermal nickel prospectivity map of the state. The methodology developed in this study could be potentially applied to frontier exploration grounds with similar geological setting, such as Papua New Guinea.

  10. Hydrothermal Ni Prospectivity Analysis of Tasmania, Australia

    NASA Astrophysics Data System (ADS)

    Gonzalez-Alvarez, I.; Porwal, A.; McCuaig, T. C.; Maier, W.

    2009-04-01

    Tasmania contains the largest hydrothermal Ni deposit in Australia: Avebury (118,000 Ni metal tonnes). This Devonian deposit was discovered in 1998 in the Dundas geological region, and consists of a system of hydrothermal Ni ore bodies. They are hosted by an intensely altered and serpentinized Cambrian ultramafic suite in close proximity to major structural features. The mineralization is considered to be the result of hydrothermal scavenging and remobilization of the original nickel content of mafic/ultramafic rocks in the area, and subsequent re-deposition in favourable structural traps. This is based on the low sulphur, low Cu and Platinum element content of the mineralization. The mineralization is spatially (at the edge) and temporally related to a large granitic intrusion, the Heemskirk Granite, which is considered to be the source of the hydrothermal fluids as well as the necessary thermal gradients for the circulation of the fluids. Tasmania is largely covered by the Jurassic Ferrar continental flood basalt province in the East and constrains a number of early Cambrian ultramafic-mafic complexes in the West. The Ferrar large igneous province (LIP) extends over to Antarctica and is temporally and genetically related to the Karoo igneous province in southern Africa that comprises tholeiitic lava flows, sills, and dyke swarms. The Ferrar and Karoo igneous provinces were associated with the same thermal anomaly that was responsible for the break up of eastern Gondwana at ca 180 Ma. Despite of timeframe differences between the Avebury Ni deposits and the Ferrar LIP emplacement, similar geological settings to the Avebury could be duplicated along the Ferrar LIP. The presence of mafic/ultramafic rocks in favourable lithological packages and/or structural traps along the margins of the province indicate that this LIP could represent a possible exploration target for Ni hydrothermal deposits. Based on this background, a prospectivity analysis for hydrothermal Ni deposits was carried out on a regional scale for the entire state of Tasmania to explore the prospectivity of for hydrothermal Ni deposits of this part of the Ferrar LIP for. A conceptual model of hydrothermal nickel mineral systems was used to identify the following as the most important exploration criteria for hydrothermal nickel deposits: (i) presence of potential nickel sources, (ii) heat and fluid sources, (iii) permeable transportation channels for circulating hydrothermal fluids, and (iv) prospective lithological and structural traps conducive for sulphur saturation and deposition of nickel sulphides. Available public domain exploration datasets were processed using GIS functionalities to derive a series of derivative GIS layers that could be used as proxies for each of the above exploration criteria. These included mafic-ultramafic rocks formed from magma with >7% MgO, large igneous province; major faults, and mineral alteration assemblages that could indicate redox gradients and/or reduced fluids highly concentrated in chloride etc. A two-pronged approach involving GIS-assisted manual prospectivity analysis and GIS-based (automated) prospectivity analysis was used for identifying the most prospective ground for hydrothermal nickel deposits in Tasmania. The manual analysis involved a conceptual review of all geological regions of the state, while the GIS-based automated approach used a spatial fuzzy model. The results of the two analyses were subsequently integrated and, after a detailed geological follow-up study, were used to generate a hydrothermal nickel prospectivity map of the state. The methodology developed in this study could be potentially applied to frontier exploration grounds with similar geological setting, such as Papua New Guinea.

  11. Hydrothermal plumes along segments of contrasting magmatic influence, 158888200

    E-print Network

    Langmuir, Charles H.

    ridges have emphasized a positive correlation between local magmatic budget and hydrothermal activity the segment-scale incongruity between hydrothermal activity and magmatic budget, the fraction of total ridge to predictions based on data from other Pacific ridges, hydrothermal plumes over the inflated 168N segment were

  12. Calcium Isotope Fractionation in mid-ocean ridge hydrothermal systems

    Microsoft Academic Search

    M. Sharma; C. Holmden

    2008-01-01

    The purpose of this study is to investigate Ca isotope fractionation during hydrothermal alteration of mid- ocean ridge basalts. Both high and low temperature hydrothermal fluids are enriched in calcium relative to seawater reflecting its derivation from the ocean crust. Indeed, hydrothermal alteration at ridge-crests and at ridge-flanks provides significant amounts of Ca and affects the Ca isotopic composition of

  13. Biogeochemistry of hydrothermally and adjacent non-altered soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    As a field/lab project, students in the Soil Biogeochemistry class of the University of Nevada, Reno described and characterized seven pedons, developed in hydrothermally and adjacent non-hydrothermally altered andesitic parent material near Reno, NV. Hydrothermally altered soils had considerably lo...

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

    NASA Technical Reports Server (NTRS)

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

    1973-01-01

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

  15. 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.

  16. Hydrothermal Venting at Kick'Em Jenny Submarine Volcano (West Indies)

    NASA Astrophysics Data System (ADS)

    Carey, S.; Croff Bell, K. L.; Dondin, F. J. Y.; Roman, C.; Smart, C.; Lilley, M. D.; Lupton, J. E.; Ballard, R. D.

    2014-12-01

    Kick'em Jenny is a frequently-erupting, shallow submarine volcano located ~8 km off the northwest coast of Grenada in the West Indies. The last eruption took place in 2001 but did not breach the sea surface. Focused and diffuse hydrothermal venting is taking place mainly within a small (~100 x 100 m) depression within the 300 m diameter crater of the volcano at depths of about 265 meters. Near the center of the depression clear fluids are being discharged from a focused mound-like vent at a maximum temperature of 180o C with the simultaneous discharge of numerous bubble streams. The gas consists of 93-96% CO2 with trace amounts of methane and hydrogen. A sulfur component likely contributes 1-4% of the gas total. Gas flux measurements on individual bubble streams ranged from 10 to 100 kg of CO2 per day. Diffuse venting with temperatures 5 to 35o C above ambient occurs throughout the depression and over large areas of the main crater. These zones are extensively colonized by reddish-yellow bacterial mats with the production of loose Fe-oxyhydroxides largely as a surface coating and in some cases, as fragile spires up to several meters in height. A high-resolution photo mosaic of the crater depression was constructed using the remotely operated vehicle Hercules on cruise NA039 of the E/V Nautilus. The image revealed prominent fluid flow patterns descending the sides of the depression towards the base. We speculate that the negatively buoyant fluid flow may be the result of second boiling of hydrothermal fluids at Kick'em Jenny generating a dense saline component that does not rise despite its elevated temperature. Increased density may also be the result of high dissolved CO2 content of the fluids, although we were not able to measure this directly. The low amount of sulphide mineralization on the crater floor suggests that deposition may be occurring mostly subsurface, in accord with models of second boiling mineralization from other hydrothermal vent systems.

  17. A new hydrothermal scenario for the 2006 Lusi eruption, Indonesia. Insights from gas geochemistry

    NASA Astrophysics Data System (ADS)

    Mazzini, Adriano; Etiope, Giuseppe; Svensen, Henrik

    2012-02-01

    The 29th of May 2006 gas and mud eruptions suddenly appeared along the Watukosek fault in the north east of Java, Indonesia. Within a few weeks several villages were submerged by boiling mud. The most prominent eruption site was named Lusi. To date (November 2011) Lusi is still active and a ~ 7 km2 area is covered by the burst mud breccia. The mechanisms responsible for this devastating eruption remain elusive. While there is consensus about the origin of the erupted mud, the source of water is uncertain, the origin of the gas is unknown and the trigger of the eruption is still debated. In order to shed light on these unknowns, we acquired a wide set of data of molecular and isotopic composition of gas sampled in several Lusi vents, in the surrounding mud volcanoes, in the closest natural gas field (Wunut), and in the hydrothermal vents at the neighbouring volcanic complex in the period 2006-2011. The boiling fluids erupted in the crater zone are apparently CO2-dominated, while colder CH4-dominated and C2-C3 bearing fluids are identified at several sites around the crater zone. Gas genetic diagrams, maturity plots and gas generation modelling suggest that the hydrocarbons are thermogenic (?13C1 up to - 35‰; ?13C2 up to - 20‰), deriving from marine kerogen with maturity of at least 1.5%Ro, for instance in the ~ 4400 m deep Ngimbang source rocks. CO2 released from the crater and surrounding seeps is also thermogenic (?13C from - 15 to - 24‰) related to kerogen decarboxylation or thermal CH4 oxidation in deep rocks, although three vents just outside the crater showed an apparent inorganic signature (- 7.5‰ < ?13C = - 0.5‰) associated to mantle helium (R/Ra up to 6.5). High CO2-CH4 equilibrium temperatures (200-400 °C) are typical of thermally altered hydrocarbons or organic matter. The data suggest mainly thermally altered organic sources for the erupted gases, deeper sourced than the mud and water (Upper Kalibeng shales). These results are consistent with a scenario of deep seated (> 4000 m) magmatic intrusions and hydrothermal fluids responsible for the enhanced heat that altered source rocks and/or gas reservoirs. The neighbouring magmatic Arjuno complex and its fluid-pressure system combined with high seismic activity could have played a key role in the Lusi genesis and evolution. Within this new model framework, Lusi is better understood as a sediment-hosted hydrothermal system rather than a mud volcano.

  18. The Physics of Boiling at Burnout

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

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

  19. Hybrid modelling of a sugar boiling process

    E-print Network

    Lauret, Alfred Jean Philippe; Gatina, Jean Claude

    2012-01-01

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

  20. Enceladus Plumes: A Boiling Liquid Model

    NASA Astrophysics Data System (ADS)

    Nakajima, Miki; Ingersoll, A. P.

    2012-10-01

    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.

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

    SciTech Connect

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

    1987-06-01

    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.

  2. Proposal for the award of a contract for the supply of sub-cooling helium heat exchangers for the LHC

    E-print Network

    2001-01-01

    This document concerns the award of a contract for the design, manufacture, testing and delivery of 252 sub-cooling helium heat exchangers of three different sizes for the LHC. Following a market survey carried out among 63 firms in fourteen Member States and a price enquiry for qualifying prototypes sent to eight firms in four Member States (DO-17367/LHC/LHC), a call for tenders (IT-2465/LHC/LHC) was sent on 24 April 2001 to three firms in two Member States. By the closing date, CERN had received tenders from all three firms. The Finance Committee is invited to agree to the negotiation of a contract with the firm DATE (FR), the lowest bidder, for the design, manufacture, assembly, testing and delivery of 252 sub-cooling helium heat exchangers, of three different sizes, for the LHC for a total amount of 1 179 126 euros (1 799 368 Swiss francs), not subject to revision, with an option for the supply of up to 10% additional heat exchangers, for a total amount of up to 117 912 euros (179 936 Swiss francs), not s...

  3. Transition boiling heat transfer and the film transition regime

    NASA Technical Reports Server (NTRS)

    Ramilison, J. M.; Lienhard, J. H.

    1987-01-01

    The Berenson (1960) flat-plate transition-boiling experiment has been recreated with a reduced thermal resistance in the heater, and an improved access to those portions of the transition boiling regime that have a steep negative slope. Tests have been made in Freon-113, acetone, benzene, and n-pentane boiling on horizontal flat copper heaters that have been mirror-polished, 'roughened', or teflon-coated. The resulting data reproduce and clarify certain features observed by Berenson: the modest surface finish dependence of boiling burnout, and the influence of surface chemistry on both the minimum heat flux and the mode of transition boiling, for example. A rational scheme of correlation yields a prediction of the heat flux in what Witte and Lienhard (1982) previously identified as the 'film-transition boiling' region. It is also shown how to calculate the heat flux at the boundary between the pure-film, and the film-transition, boiling regimes, as a function of the advancing contact angle.

  4. The chemistry of hydrothermal magnetite: a review

    USGS Publications Warehouse

    Nadoll, Patrick; Angerer, Thomas; Mauk, Jeffrey L.; French, David; Walshe, John

    2014-01-01

    Magnetite (Fe3O4) is a well-recognized petrogenetic indicator and is a common accessory mineral in many ore deposits and their host rocks. Recent years have seen an increased interest in the use of hydrothermal magnetite for provenance studies and as a pathfinder for mineral exploration. A number of studies have investigated how specific formation conditions are reflected in the composition of the respective magnetite. Two fundamental questions underlie these efforts — (i) How can the composition of igneous and, more importantly, hydrothermal magnetite be used to discriminate mineralized areas from barren host rocks, and (ii) how can this assist exploration geologists to target ore deposits at greater and greater distances from the main mineralization? Similar to igneous magnetite, the most important factors that govern compositional variations in hydrothermal magnetite are (A) temperature, (B) fluid composition — element availability, (C) oxygen and sulfur fugacity, (D) silicate and sulfide activity, (E) host rock buffering, (F) re-equilibration processes, and (G) intrinsic crystallographic controls such as ionic radius and charge balance. We discuss how specific formation conditions are reflected in the composition of magnetite and review studies that investigate the chemistry of hydrothermal and igneous magnetite from various mineral deposits and their host rocks. Furthermore, we discuss the redox-related alteration of magnetite (martitization and mushketovitization) and mineral inclusions in magnetite and their effect on chemical analyses. Our database includes published and previously unpublished magnetite minor and trace element data for magnetite from (1) banded iron formations (BIF) and related high-grade iron ore deposits in Western Australia, India, and Brazil, (2) Ag–Pb–Zn veins of the Coeur d'Alene district, United States, (3) porphyry Cu–(Au)–(Mo) deposits and associated (4) calcic and magnesian skarn deposits in the southwestern United States and Indonesia, and (5) plutonic igneous rocks from the Henderson Climax-type Mo deposit, United States, and the un-mineralized Inner Zone Batholith granodiorite, Japan. These five settings represent a diverse suite of geological settings and cover a wide range of formation conditions. The main discriminator elements for magnetite are Mg, Al, Ti, V, Cr, Mn, Co, Ni, Zn, and Ga. These elements are commonly present at detectable levels (10 to > 1000 ppm) and display systematic variations. We propose a combination of Ni/(Cr + Mn) vs. Ti + V, Al + Mn vs. Ti + V, Ti/V and Sn/Ga discriminant plots and upper threshold concentrations to discriminate hydrothermal from igneous magnetite and to fingerprint different hydrothermal ore deposits. The overall trends in upper threshold values for the different settings can be summarized as follows: (I) BIF (hydrothermal) — low Al, Ti, V, Cr, Mn, Co, Ni, Zn, Ga and Sn; (II) Ag–Pb–Zn veins (hydrothermal) — high Mn and low Ga and Sn; (III) Mg-skarn (hydrothermal) — high Mg and Mn and low Al, Ti, Cr, Co, Ni and Ga; (IV) skarn (hydrothermal) — high Mg, Al, Cr, Mn, Co, Ni and Zn and low Sn; (V) porphyry (hydrothermal) — high Ti and V and low Sn; (VI) porphyry (igneous) — high Ti, V and Cr and low Mg; and (VII) Climax-Mo (igneous) — high Al, Ga and Sn and low Mg and Cr.

  5. Characterizing preferential groundwater discharge through boils using temperature

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

  6. A fundamental study of nucleate pool boiling under microgravity

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

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

  7. A Fundamental Study of Nucleate Pool Boiling Under Microgravity

    NASA Technical Reports Server (NTRS)

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

    1996-01-01

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

  8. Hydrothermal crystallisation of metal (II) orotates (M=nickel, cobalt, manganese or zinc). Effect of 2,2-bipyridyl, 2,2-dipyridyl amine, 1-methyl-3-(2-pyridyl)pyrazole, phenanthroline and 2,9-dimethyl-1,10-phenanthroline upon structure

    Microsoft Academic Search

    M. John Plater; Mark R. St. J Foreman; Janet M. S Skakle; R. Alan Howie

    2002-01-01

    Hydrothermal synthesis of orotic acid (H3L) with Ni(OAc)2·4H2O gives a green 1D co-ordinative network of composition [Ni(HL)(H2O)3] (3). The kinetic product [Ni(HL)·(H2O)4]H2O (4) can be prepared by conventional crystallisation. When boiled in water it is transformed into the thermodynamically favoured trihydrate 3. An unstable blue phase 5 that could not be characterised was also observed. Hydrothermal synthesis of orotic acid

  9. Pool and flow boiling in variable and microgravity

    NASA Technical Reports Server (NTRS)

    Merte, Herman, Jr.

    1994-01-01

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

  10. ``Boiling'' in the water evaporating meniscus induced by Marangoni flow

    NASA Astrophysics Data System (ADS)

    Liu, Xiang; Guo, Dan; Xie, Guoxin; Liu, Shuhai; Luo, Jianbin

    2012-11-01

    A counterintuitive phenomenon, "boiling," was directly observed near the contact line of the pure water meniscus formed in a ball and disk configuration, when the ball temperature was far lower than the saturation temperature of water. The number of the emerging bubbles due to "boiling" increased with ball temperature rising; each bubble would expanse initially and then collapse. When two surfaces were heated to the same temperature, "boiling" disappeared. It was proposed that the temperature gradient between the two surfaces initiated Marangoni flow, which hindered flow toward the film, resulting in the negative pressure and cavitation in the liquid film.

  11. Relict hydrothermal zones in the TAG hydrothermal field, Mid-Atlantic Ridge 26°N, 45°W

    Microsoft Academic Search

    Peter A. Rona; Yury A. Bogdanov; Evengy G. Gurvich; Nick A. Rimski-Korsakov; Anatoly M. Sagalevitch; Mark D. Hannington; Geoffrey Thompson

    1993-01-01

    Two relict hydrothermal zones were delineated between water depths of 3400 and 3500 m at the lower part of the east wall of the rift valley of the Mid-Atlantic Ridge in the TAG hydrothermal field using a deep-towed side scan sonar tow and a camera-temperature tow along the northern 3 km of the wall, and a submersible transect. Named the

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

    ERIC Educational Resources Information Center

    Struyf, Jef

    2011-01-01

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

  13. Effects of dissolved gas content on pool boiling of a highly wetting fluid

    Microsoft Academic Search

    S. M. You; Y. S. Hong; T. W. Simon; A. Bar-Cohen

    1995-01-01

    Experimental results on pool boiling heat transfer from a horizontal cylinder in an electronic cooling fluid (FC-72) are presented. The effects on the boiling curve of having air dissolved in the fluid are documented, showing that fluid in the vicinity of the heating element is apparently liberated of dissolved gas during boiling. Dissolved gas was found to influence boiling incipience

  14. Towards a unifying heat transfer correlation for the entire boiling curve

    Microsoft Academic Search

    Torsten Lüttich; Wolfgang Marquardt; Martin Buchholz; Hein Auracher

    2004-01-01

    The mechanistic understanding of boiling processes is still inadequate. Major physical effects determining the heat transfer in high heat flux nucleate and transition boiling regions have not yet been captured adequately. Thus, existing design correlations are often valid only for one of the boiling regimes. In this paper, the wetting structure close to the boiling surface is identified using the

  15. Prediction of the Mixture Effect On Boiling in Vertical Thermosyphon Reboilers

    Microsoft Academic Search

    JOHN R. THOME

    1989-01-01

    The present study has investigated the effect of mixtures on the nucleate boiling contribution to flow boiling inside vertical tubes at low vapor qualities, operating conditions typical of vertical thermosyphon reboilers. The mass diffusion process created by the composition difference between the vapor and liquid phases was found to impede the boiling process and substantially reduce the nucleate boiling heat

  16. Fungal colonization of an Ordovician impact-induced hydrothermal system

    PubMed Central

    Ivarsson, Magnus; Broman, Curt; Sturkell, Erik; Ormö, Jens; Siljeström, Sandra; van Zuilen, Mark; Bengtson, Stefan

    2013-01-01

    Impacts are common geologic features on the terrestrial planets throughout the solar system, and on at least Earth and Mars impacts have induced hydrothermal convection. Impact-generated hydrothermal systems have been suggested to possess the same life supporting capability as hydrothermal systems associated with volcanic activity. However, evidence of fossil microbial colonization in impact-generated hydrothermal systems is scarce in the literature. Here we report of fossilized microorganisms in association with cavity-grown hydrothermal minerals from the 458?Ma Lockne impact structure, Sweden. Based on morphological characteristics the fossilized microorganisms are interpreted as fungi. We further infer the kerogenization of the microfossils, and thus the life span of the fungi, to be contemporaneous with the hydrothermal activity and migration of hydrocarbons in the system. Our results from the Lockne impact structure show that hydrothermal systems associated with impact structures can support colonization by microbial life. PMID:24336641

  17. Efficiencies of Power Plants Using Hydrothermal Oxidation

    Microsoft Academic Search

    Kazuma Hirosaka; Korakot Yuvamitra; Akira Ishikawa; Tatsuya Hasegawa

    2008-01-01

    Wet biomass is hard to handle as a fuel for power plants because it contains high moisture and its drying process needs more energy input than it produces. Hydrothermal oxidation could be one of the promising technologies to overcome this problem because this process does not need drying process at all. We focus on recovery of thermal energy produced by

  18. DRILLED HYDROTHERMAL ENERGY Drilling for seawater

    E-print Network

    Water Desalination Fuel Production Waste Water Treatment Increased CO2 Absorbtion Agriculture & Mari) of cold water pipe WAS LOST 3 TIMES before demonstrating power generation #12;DRILLED HYDROTHERMAL ENERGY BACKGROUND After a 2006 earthquake on the Big Island The NELHA cold water pipe cracked allowing warm water

  19. The Discovery of Marine Hydrothermal Vents

    NSDL National Science Digital Library

    OceanLink

    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.

  20. Hydrothermal gasification of biomass and organic wastes

    Microsoft Academic Search

    H. Schmieder; J. Abeln; N. Boukis; E. Dinjus; A. Kruse; M. Kluth; G. Petrich; E. Sadri; M. Schacht

    2000-01-01

    Wet biomass and organic wastes can be efficiently gasified under hydrothermal conditions to produce a hydrogen rich fuel gas. New experiments in two tubular flow reactors and in two batch autoclaves with carbohydrates, with aromatic compounds, with glycine as a model compound for proteins and with real biomass are reported for different residence times, temperatures and pressures. It was found

  1. Hydrothermal carbonization of municipal waste streams

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Hydrothermal carbonization (HTC) is a novel thermal conversion process that can be used to convert municipal waste streams into sterilized, value-added hydrochar. HTC has been mostly applied and studied on a limited number of feedstocks, ranging from pure substances to slightly more complex biomass ...

  2. CASE STUDIES OF FLUID TRANSIENTS IN SUBCOOLED Anton Bergant, Litostroj E.I. d.o.o., Slovenia, anton.bergant@litostroj-ei.si

    E-print Network

    Eindhoven, Technische Universiteit

    CASE STUDIES OF FLUID TRANSIENTS IN SUBCOOLED PIPE FLOW Anton Bergant, Litostroj E.I. d: Transient regimes may cause excessive water hammer, and possible column separation, slug flow, plug flow and fluid-structure interaction (FSI) in the system. Fluid transients may severely disturb operation

  3. Experimental constraints on hydrothermal activities in Enceladus

    NASA Astrophysics Data System (ADS)

    Sekine, Y.; Shibuya, T.; Suzuki, K.; Kuwatani, T.

    2012-12-01

    One of the most remarkable findings by the Cassini-Huygens mission is perhaps water-rich plumes erupting from the south-pole region of Enceladus [1]. Given such geological activity and the detection of sodium salts in the plume, the interior of Enceladus is highly likely to contain an interior ocean interacting with the rock core [2]. A primary question regarding astrobiology and planetary science is whether Enceladus has (or had) hydrothermal activities in the interior ocean. Because N2 might be formed by thermal dissociation of primordial NH3 [3], the presence of N2 in the plume may be a possible indicator for the presence of hydrothermal activities in Enceladus. However, the Cassini UVIS revealed that the plumes do not contain large amounts of N2 [4]. Although these observations may not support the presence of hydrothermal activities, whether NH3 dissociation proceeds strongly depends on the kinetics of hydrothermal reactions and interactions with the rock components, which remain largely unknown. Furthermore, the Cassini CDA recently showed that small amounts of SiO2 might have been included in the plume dusts [5]. Formation of amorphous SiO2 usually occurs when high-temperature and/or high-pH solution with high concentrations of dissolved SiO2 cools and/or is neutralized. Thus, the presence of SiO2 in the plume dusts may suggest the presence of a temperature and/or pH gradient in the ocean. However, no laboratory experiments have investigated what processes control pH and SiO2 concentrations in hydrothermal fluids possibly existing in Enceladus. Here, we show the results of laboratory experiments simulating hydrothermal systems on Enceladus. As the initial conditions, we used both aqueous solution of high concentrations (0.01-2%) of NH3 and NaHCO3 and powdered olivine as an analog for the rock components. Our experimental results show that formation of N2 from NH3 is kinetically and thermodynamically inhibited even under high temperature conditions (< 400°C). This is because NH3 decomposition proceeds inefficiently due to efficient H2 production via serpentinization. Our experimental results also suggest that SiO2 concentration dissolved in hydrothermal fluids simulating Enceladus' condition would be buffered by the serpentine-brucite system. The presence of NH3 in the hydrothermal conditions keeps pH of the solution high (pH 9-11). We suggest that under such conditions, SiO2 concentrations in the fluids would be 0.1 mmol/L or less for temperature < 350°C. Given the SiO2 solubility of 1-10 mmol/L at 0°C and pH 9-11, direct formation of amorphous SiO2 would not occur in Enceladus' hydrothermal systems. To produce amorphous SiO2, large-scale hydrothermal activities and subsequent concentration of dissolved SiO2 in the ocean (due to freezing and/or evaporation of liquid water) would be required, which is consistent with high concentrations of radiogenic Ar and sodium salts in the plume [2, 6]. [1] Porco et al., Science 311, 1393 (2006). [2] Postberg et al., Nature 459, 1098 (2009). [3] Matson et al., Icarus 187, 569 (2007). [4] Hansen t al., Geophs. Res. Lett. 38, L11202 (2011). [5] Hsu et al., EOS Trans. AGU, (2010). [6] Waite et al., Nature 460, 487 (2009).

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

    NASA Astrophysics Data System (ADS)

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

    2009-04-01

    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

  5. Hydrothermal systems in small ocean planets.

    PubMed

    Vance, Steve; Harnmeijer, Jelte; Kimura, Jun; Hussmann, Hauke; Demartin, Brian; Brown, J Michael

    2007-12-01

    We examine means for driving hydrothermal activity in extraterrestrial oceans on planets and satellites of less than one Earth mass, with implications for sustaining a low level of biological activity over geological timescales. Assuming ocean planets have olivine-dominated lithospheres, a model for cooling-induced thermal cracking shows how variation in planet size and internal thermal energy may drive variation in the dominant type of hydrothermal system-for example, high or low temperature system or chemically driven system. As radiogenic heating diminishes over time, progressive exposure of new rock continues to the current epoch. Where fluid-rock interactions propagate slowly into a deep brittle layer, thermal energy from serpentinization may be the primary cause of hydrothermal activity in small ocean planets. We show that the time-varying hydrostatic head of a tidally forced ice shell may drive hydrothermal fluid flow through the seafloor, which can generate moderate but potentially important heat through viscous interaction with the matrix of porous seafloor rock. Considering all presently known potential ocean planets-Mars, a number of icy satellites, Pluto, and other trans-neptunian objects-and applying Earth-like material properties and cooling rates, we find depths of circulation are more than an order of magnitude greater than in Earth. In Europa and Enceladus, tidal flexing may drive hydrothermal circulation and, in Europa, may generate heat on the same order as present-day radiogenic heat flux at Earth's surface. In all objects, progressive serpentinization generates heat on a globally averaged basis at a fraction of a percent of present-day radiogenic heating and hydrogen is produced at rates between 10(9) and 10(10) molecules cm(2) s(1). PMID:18163874

  6. Cinnabar, arsenian pyrite and thallium-enrichment in active shallow submarine hydrothermal vents at Paleochori Bay, Milos Island, Greece

    NASA Astrophysics Data System (ADS)

    Kati, Marianna; Voudouris, Panagiotis; Valsami-Jones, Eugenia; Magganas, Andreas; Baltatzis, Emmanouil; Kanellopoulos, Christos; Mavrogonatos, Constantinos

    2015-04-01

    We herein report the discovery of active cinnabar-depositing hydrothermal vents in a submarine setting at Paleochori Bay, within the offshore southeastern extension of the Milos Island Geothermal Field, South Aegean Active Volcanic Arc. Active, low temperature (up to 115 °C) hydrothermal venting through volcaniclastic material has led to a varied assemblage of sulfide and alteration mineral phases in an area of approximately 1 km2. Our samples recovered from Paleochori Bay are hydrothermal edifices composed of volcaniclastic detrital material cemented by pyrite, or pure sulfide (mainly massive pyrite) mounts. Besides pyrite and minor marcasite, the hydrothermal minerals include cinnabar, amorphous silica, hydrous ferric oxides, carbonates (aragonite and calcite), alunite-jarosite solid solution and Sr-rich barite. Among others, growth textures, sieve-textured pyrite associated with barite, alunite-jarosite solid solution and hydrous ferric oxides rims colloform-banded pyrite layers. Overgrowths of arsenian pyrite layers (up to 3.2 wt. % As and/or up to 1.1 wt. % Mn) onto As-free pyrite indicate fluctuation in As content of the hydrothermal fluid. Mercury, in the form of cinnabar, occurs in up to 5 ?m grains within arsenian pyrite layers, usually forming distinct cinnabar-enriched micro-layers. Hydrothermal Sr-rich barite (barite-celestine solid solution), pseudocubic alunite-jarosite solid solution and Mn- and Sr-enriched carbonates occur in various amounts and closely associated with pyrite and/or hydrous ferric oxides. Thallium-bearing sulfides and/or sulfosalts were not detected during our study; however, hydrous ferric oxides show thallium content of up to 0.5 wt. % Tl. The following scenarios may have played a role in pyrite precipitation at Paleochori: (a) H2S originally dissolved in the deep fluid but separated upon boiling could have reacted with oxygenated seawater under production of sulphuric acid, thus causing leaching and dissolution of primary iron-rich grains from the volcaniclastic components of the sediments and resulting in precipitation of pyrite; (b) the iron may also have been derived by the near-neutral reduced hydrothermal brines and precipitate metal sulfides as a result of cooling, mixing with seawaters; the necessary iron content to form sulfides is mostly derived from primary iron-rich components of the basement; (c) biological activity may have resulted in pyrite deposition (e.g. sulfur is provided by a biogenic reduction of marine sulphate). The mineralogy of hydrothermal precipitates considered in the present study resemble hydrothermal products from other shallow water venting areas elsewhere: Lihir and Ambitle Islands, Papua New Guinea, Kraternaya Bight, Kuriles, Russia, Punta Mita and Bahía Concepción, Mexico and Punta Banda at Baja California. The Paleochori vents contain the first documented occurrence of cinnabar on the sea floor in the Aegean area and provide an important link between offshore hydrothermal activity and the mercury-depositing mineralizing system on Milos Island. An interplay between bacterial activity, pH, Eh, temperature, precipitation rate and iron concentration resulted in precipitation of As-pyrite with interlayered cinnabar, hydrous ferric oxides enriched in thallium, alunite-jarosite solid solution and carbonates.

  7. Thermal boundary layer development in dispersed flow film boiling

    E-print Network

    Hull, Lawrence M.

    1982-01-01

    Dispersed flow film boiling consists of a dispersion of droplets which are carried over a very hot surface by their vapor. This process occurs in cryogenic equipment and wet steam turbines. It is also of interest in the ...

  8. Film Boiling on Downward Quenching Hemisphere of Varying Sizes

    SciTech Connect

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

    2004-04-01

    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.

  9. Infrared thermometry study of nanofluid pool boiling phenomena

    E-print Network

    Gerardi, Craig

    Abstract Infrared thermometry was used to obtain first-of-a-kind, time- and space-resolved data for pool boiling phenomena in water-based nanofluids with diamond and silica nanoparticles at low concentration (<0.1 vol.%). ...

  10. Determination of pool boiling Critical Heat Flux enhancement in nanofluids

    E-print Network

    Truong, Bao H. (Bao Hoai)

    2007-01-01

    Nanofluids are engineered colloids composed of nano-size particles dispersed in common fluids such as water or refrigerants. Using an electrically controlled wire heater, pool boiling Critical Heat Flux (CHF) of Alumina ...

  11. Burnout in forced convection nucleate boiling of water

    E-print Network

    Reynolds John Mitchell

    1957-01-01

    Data are presented for burnout in forced coivection nucleate boiling of water at pressures above 500 psia. A dimensionless correlation is devised for. the M.I.T. data which is found to be valid for certain recent data ...

  12. 21 CFR 872.6710 - Boiling water sterilizer.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6710 ...boiling water. The device is intended to sterilize dental and surgical instruments by submersion in the...

  13. 21 CFR 872.6710 - Boiling water sterilizer.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6710 ...boiling water. The device is intended to sterilize dental and surgical instruments by submersion in the...

  14. 21 CFR 872.6710 - Boiling water sterilizer.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6710 ...boiling water. The device is intended to sterilize dental and surgical instruments by submersion in the...

  15. 21 CFR 872.6710 - Boiling water sterilizer.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6710 ...boiling water. The device is intended to sterilize dental and surgical instruments by submersion in the...

  16. Why Is NASA Boiling Fluids in Space? - Duration: 59 seconds.

    NASA Video Gallery

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

  17. Boiling local heat transfer enhancement in minichannels using nanofluids.

    PubMed

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

    2013-01-01

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

  18. 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

  19. 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

  20. Flow Boiling and Condensation Experiment - Duration: 21 seconds.

    NASA Video Gallery

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

  1. Boiling local heat transfer enhancement in minichannels using nanofluids

    PubMed Central

    2013-01-01

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

  2. Hydrothermal Activity on ultraslow Spreading Ridge: new hydrothermal fields found on the Southwest Indian ridge

    NASA Astrophysics Data System (ADS)

    Tao, C.; Li, H.; Deng, X.; Lei, J.; Wang, Y.; Zhang, K.; Zhou, J.; Liu, W.

    2014-12-01

    Ultraslow spreading ridge makes up about 25% of global mid-ocean ridge length. Previous studies believed that hydrothermal activity is not widespread on the ultraslow spreading ridge owing to lower magma supply. Southwest Indian ridge (SWIR) with the spreading rate between 1.2cm/a to 1.4cm/a, represents the ultraslow spreading ridge. In 2007, Chinese Cruise (CC) 19th discovered the Dragon Flag deposit (DFD) on the SWIR, which is the first active hydrothermal field found on the ultraslow spreading ridge. In recent years, over 10 hydrothermal fields have been found on the SWIR between Indomed and Gallieni transform faults by the Chinese team. Tao et al. (2012) implied that the segment sections with excess heat from enhanced magmatism and suitable crustal permeability along slow and ultraslow ridges might be the most promising areas for searching for hydrothermal activities. In 2014, CC 30thdiscovered five hydrothermal fields and several hydrothermal anomalies on the SWIR. Dragon Horn Area (DHA). The DHA is located on the southern of segment 27 SWIR, with an area of about 400 km2. The geophysical studies indicated that the DHA belongs to the oceanic core complex (OCC), which is widespread on the slow spreading ridges (Zhao et al., 2013). The rocks, such as gabbro, serpentinized peridotite, and consolidated carbonate were collected in the DHA, which provide the direct evidence with the existence of the OCC. However, all rock samples gathered by three TV-grab stations are basalts on the top of the OCC. A hydrothermal anomaly area, centered at 49.66°E?37.80° S with a range of several kms, is detected in the DHA. It is probably comprised of several hydrothermal fields and controlled by a NW fault. New discovery of hydrothermal fields. From January to April 2014, five hydrothermal fields were discovered on the SWIR between 48°E to 50°E during the leg 2&3 of the CC 30th, which are the Su Causeway field (48.6°E, 38.1°S), Bai Causeway field (48.8°E, 37.9 °S), Dragon Well West field (49.6°E, 37.8°S), Dragon Well East field (49.8°E, 37.8°S), and Landing Stage field (51.0°E, 37.5°S), respectively.

  3. Relict hydrothermal zones in the TAG Hydrothermal Field, Mid-Atlantic Ridge 26°N, 45°W

    NASA Astrophysics Data System (ADS)

    Rona, Peter A.; Bogdanov, Yury A.; Gurvich, Evengy G.; Rimski-Korsakov, Nick A.; Sagalevitch, Anatoly M.; Hannington, Mark D.; Thompson, Geoffrey

    1993-06-01

    Two relict hydrothermal zones were delineated between water depths of 3400 and 3500 m at the lower part of the east wall of the rift valley of the Mid-Atlantic Ridge in the TAG hydrothermal field using a deep-towed side scan sonar tow and a camera-temperature tow along the northern 3 km of the wall, and a submersible transect. Named the North and MIR relict zones, they are located about 4 km and 2 km northeast, respectively, of the known active high-temperature sulfide mound between water depths of 3625 and 3670 m on the rift valley floor near the base of the east wall. The North zone extends about 2 km along the northern end of the lower east wall. The zone includes two moundlike features up to 30 m high by 200 m in diameter imaged by side scan sonar within a 2-km-long line of discontinuous hydrothermal deposits comprising inactive toppled and standing chimneys, layered material, and patchy dark stains on sediment photographed by the camera-temperature tow. Several other moundlike features were imaged with the side scan sonar outside of the photographic coverage. The MIR relict hydrothermal zone 2 km south of the North zone, named after the MIR submersible used to investigate it, consists of three subzones: (1) a 200-m-wide area of diverse types of hydrothermal materials exposed by normal faulting at its western margin; (2) a 400-m-wide by 700-m-long central area of discrete groups of toppled and standing inactive sulfide chimneys up to 25 m high on a substrate of red metalliferous sediment and carbonate lutite; spires sampled on the highest chimneys are composed of coarse-grained, recrystallized sulfides dominated by pyrite and chalcopyrite which contain the first primary, free gold grains (2-3 ?m diameter) found at a hydrothermal site on a mid-ocean ridge; and (3) a 150-m-wide hummocky area of layered hydrothermal material with the appearance of low temperature precipitates and carbonate lutite with patchy dark stains at its eastern margin. The active sulfide mound, the North zone, and the MIR zone are each located on the fractured western margins of gentle, dome-shaped areas of pillow flows typically 500 m in diameter interpreted as summits of volcanic centers that may have supplied heat to drive adjacent hydrothermal activity. The distribution and size of the active and inactive hydrothermal zones of the TAG field, the chronology, and the characteristics of relict samples recovered indicate a history of at least 100 ×103 years of high-temperature hydrothermal episodes with multiple overprinting stages of mineralization accompanied by alteration.

  4. Heat transfer near the contact line during boiling in microgravity

    Microsoft Academic Search

    A. J. Robinson

    2007-01-01

    Although significant progress has been made, the mechanisms of heat transfer responsible for enhancement during nucleate boiling\\u000a are not fully understood. The primary barriers to a complete understanding of the heat transfer during boiling are due to\\u000a difficulties associated with performing rapid microscale measurements, ambiguity due to the interaction of previous and neighbouring\\u000a bubbles, uncertainty with regard to gravitational effects

  5. Nanocoating characterization in pool boiling heat transfer of pure water

    Microsoft Academic Search

    Sang M. Kwark; Gilberto Moreno; Ratan Kumar; Hyejin Moon; Seung M. You

    2010-01-01

    The pool boiling behavior of nanoparticle coated surfaces is experimentally studied in pure water. Nanoparticle coatings were created during nanofluid pool boiling experiments (Al2O3–water\\/ethanol). The nanocoatings developed can significantly enhance the critical heat flux. Ethanol nanofluids created more uniform nanocoatings which outperformed nanocoatings created in water nanofluids. The wetting and wicking characteristics of the nanocoatings are investigated through contact angle

  6. Pool-Boiling Heat Transfer in Liquid Nitrogen

    Microsoft Academic Search

    Muneo KIDA; Yoshihiro KIKUCHCI; Osamu TAKAHASHI; Itaru MICHIYOSHI

    1981-01-01

    An experimental study was conducted on pool-boiling heat transfer from an electrically heated horizontal wire to saturated liquid nitrogen at atmospheric pressure. Experimental results of heat transfer characteristics in both nucleate- and film-boiling regimes, critical heat flux and minimum heat flux were analyzed and compared with various correlations. In addition, photography was used to obtain information concerning the vapor-bubble and

  7. Infrared thermometry study of nanofluid pool boiling phenomena

    NASA Astrophysics Data System (ADS)

    Gerardi, Craig; Buongiorno, Jacopo; Hu, Lin-Wen; McKrell, Thomas

    2011-12-01

    Infrared thermometry was used to obtain first-of-a-kind, time- and space-resolved data for pool boiling phenomena in water-based nanofluids with diamond and silica nanoparticles at low concentration (<0.1 vol.%). In addition to macroscopic parameters like the average heat transfer coefficient and critical heat flux [CHF] value, more fundamental parameters such as the bubble departure diameter and frequency, growth and wait times, and nucleation site density [NSD] were directly measured for a thin, resistively heated, indium-tin-oxide surface deposited onto a sapphire substrate. Consistent with other nanofluid studies, the nanoparticles caused deterioration in the nucleate boiling heat transfer (by as much as 50%) and an increase in the CHF (by as much as 100%). The bubble departure frequency and NSD were found to be lower in nanofluids compared with water for the same wall superheat. Furthermore, it was found that a porous layer of nanoparticles built up on the heater surface during nucleate boiling, which improved surface wettability compared with the water-boiled surfaces. Using the prevalent nucleate boiling models, it was possible to correlate this improved surface wettability to the experimentally observed reductions in the bubble departure frequency, NSD, and ultimately to the deterioration in the nucleate boiling heat transfer and the CHF enhancement.

  8. Film boiling of R-11 on liquid metal surfaces

    SciTech Connect

    Greene, G.A.; Irvine, T.F. Jr.

    1986-01-01

    An interesting problem is the effect of an immiscible liquid heating surface on the process of film boiling. Such surfaces raise questions concerning interface stability to disturbances, effects of gas bubbling, and vapor explosions in layered systems. The specific motivation for this study was to investigate film boiling from a liquid surface with application to cooling of molten reactor core debris by an overlying pool of reactor coolant. To investigate this phenomenon, and apparatus consisting of a nominal six-inch diameter steel vessel to hold the liquid metal and boiling fluid was constructed; coolant reservoirs, heaters, controllers, and allied instrumentation were attached. A transient energy balance was performed on the liquid metal pool by a submerged assembly of microthermocouples in the liquid metal and an array of thermocouples on the wall of the test vessel. The thermocouple data were used to determine the boiling heat flux as well as the boiling superheat. On an average basis, the deviation between the prediction of the Berenson model and the experimental data was less than one percent when Berenson was corrected for thermal radiation effects. Evidence from visualization tests of R-11 in film boiling over molten metal pools to superheats in excess of 600 K supports this conclusion. 13 refs.

  9. Infrared thermometry study of nanofluid pool boiling phenomena

    PubMed Central

    2011-01-01

    Infrared thermometry was used to obtain first-of-a-kind, time- and space-resolved data for pool boiling phenomena in water-based nanofluids with diamond and silica nanoparticles at low concentration (<0.1 vol.%). In addition to macroscopic parameters like the average heat transfer coefficient and critical heat flux [CHF] value, more fundamental parameters such as the bubble departure diameter and frequency, growth and wait times, and nucleation site density [NSD] were directly measured for a thin, resistively heated, indium-tin-oxide surface deposited onto a sapphire substrate. Consistent with other nanofluid studies, the nanoparticles caused deterioration in the nucleate boiling heat transfer (by as much as 50%) and an increase in the CHF (by as much as 100%). The bubble departure frequency and NSD were found to be lower in nanofluids compared with water for the same wall superheat. Furthermore, it was found that a porous layer of nanoparticles built up on the heater surface during nucleate boiling, which improved surface wettability compared with the water-boiled surfaces. Using the prevalent nucleate boiling models, it was possible to correlate this improved surface wettability to the experimentally observed reductions in the bubble departure frequency, NSD, and ultimately to the deterioration in the nucleate boiling heat transfer and the CHF enhancement. PMID:21711754

  10. A microgravity boiling and convective condensation experiment

    NASA Astrophysics Data System (ADS)

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

    1987-12-01

    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.

  11. Optimal boiling temperature for ORC installation

    NASA Astrophysics Data System (ADS)

    Mikielewicz, Jaros?aw; Mikielewicz, Dariusz

    2012-09-01

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

  12. Boiling incipience in plane rotating water films

    SciTech Connect

    Mudawwar, I. (Purdue Univ., Lafayette, IN (USA)); El-Masri, M.A. (Massachusetts Inst. of Tech., Cambridge (USA))

    1988-05-01

    Knowledge of heat transfer in rotating liquid films is of paramount importance for evaluating the thermal efficiency of gas turbines with water-cooled blades. Centrifugal forces constitute the primary driving forces for liquids flowing in radial rotating channels. Coriolis forces, on the other hand, tend to thin out the flow in the form of a film that covers one side of the channel. Fully developed motion of the film is determined by a balance between centrifugal and shear forces. Thus, rotating film motion resembles that of a free-falling gravity-driven film since both are characterized by a balance between shear and body forces. However, Coriolis forces can strongly influence interfacial waves and turbulent velocity fluctuations of rotating films. This is evident from the results of Kirkpatrick (1980), who compared film thickness measurements for the cases of free-falling and rotating films. His data indicate profound waviness at higher Reynolds numbers for the case of gravity-driven films. On the other hand, interfacial waves in rotating films were found to stabilize at Reynolds numbers in excess of 8,000. This paper focuses on the effects of Coriolis forces and wall roughness on the convective heat transfer coefficient and the incipient boiling heat flux in thin rotating films.

  13. Numerical study of low concentration nanofluids pool boiling, investigating of boiling parameters introducing nucleation site density ratio

    NASA Astrophysics Data System (ADS)

    Niknam, Pouriya H.; Haghighi, M.; Kasiri, N.; Khanof, M. H.

    2014-09-01

    The present study consists of a pool boiling model modified for nanofluids. The effect of particle size, surface roughness were considered in this work. Nucleation site density ratio was introduced and a correlation was derived based on literature experimental data. Moreover, heat flux partitioning model was employed to evaluate proposed model for boiling heat transfer. The validity was assessed by comparing the results with experimental data. Nucleation site density ratio can predict heat transfer enhancement of nanofluids.

  14. Evidence for Hydrothermal Vents as "Biogeobatteries" (Invited)

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

    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.

  15. Nuclear-coupled thermal-hydraulic stability analysis of boiling water reactors

    NASA Astrophysics Data System (ADS)

    Karve, Atul A.

    We have studied the nuclear-coupled thermal-hydraulic stability of boiling water reactors (BWRs) using a model we developed from: the space-time modal neutron kinetics equations based on spatial omega-modes, the equations for two-phase flow in parallel boiling channels, the fuel rod heat conduction equations, and a simple model for the recirculation loop. The model is represented as a dynamical system comprised of time-dependent nonlinear ordinary differential equations, and it is studied using stability analysis, modern bifurcation theory, and numerical simulations. We first determine the stability boundary (SB) in the most relevant parameter plane, the inlet-subcooling-number/external-pressure-drop plane, for a fixed control rod induced external reactivity equal to the 100% rod line value and then transform the SB to the practical power-flow map. Using this SB, we show that the normal operating point at 100% power is very stable, stability of points on the 100% rod line decreases as the flow rate is reduced, and that points are least stable in the low-flow/high-power region. We also determine the SB when the modal kinetics is replaced by simple point reactor kinetics and show that the first harmonic mode has no significant effect on the SB. Later we carry out the relevant numerical simulations where we first show that the Hopf bifurcation, that occurs as a parameter is varied across the SB is subcritical, and that, in the important low-flow/high-power region, growing oscillations can result following small finite perturbations of stable steady-states on the 100% rod line. Hence, a point on the 100% rod line in the low-flow/high-power region, although stable, may nevertheless be a point at which a BWR should not be operated. Numerical simulations are then done to calculate the decay ratios (DRs) and frequencies of oscillations for various points on the 100% rod line. It is determined that the NRC requirement of DR < 0.75-0.8 is not rigorously satisfied in the low-flow/high-power region and hence these points should be avoided during normal startup and shutdown operations. The frequency of oscillation is shown to decrease as the flow rate is reduced and the frequency of 0.5Hz observed in the low-flow/high-power region is consistent with those observed during actual instability incidents. Additional numerical simulations show that in the low-flow/high-power region, for the same initial conditions, the use of point kinetics leads to damped oscillations, whereas the model that includes the modal kinetics equations results in growing nonlinear oscillations. Thus, we show that side-by-side out-of-phase growing power oscillations result due to the very important first harmonic mode effect and that the use of point kinetics, which fails to predict these growing oscillations, leads to dramatically nonconservative results. Finally, the effect of a simple recirculation loop model that we develop is studied by carrying out additional stability analyses and additional numerical simulations. It is shown that the loop has a stabilizing effect on certain points on the 100% rod line for time delays equal to integer multiples of the natural period of oscillation, whereas it has a destabilizing effect for half-integer multiples. However, for more practical time delays, it is determined that the overall effect generally is destabilizing.

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

    NASA Astrophysics Data System (ADS)

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

    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.

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

    NASA Astrophysics Data System (ADS)

    Shitashima, K.

    2007-12-01

    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 just after erupting from a hydrothermal vent is effective. The mini CTDT-RMS was installed onto the submersible. The hydrothermal plume samples were collected with monitoring the anomalies of temperature and turbidity by taking the distance from the hydrothermal vent gradually. Unfiltered sample for total (particulate + dissolved) trace element concentration and filtered sample for dissolved trace element concentration were analyzed on land. In V, Ni, Cu, Mo, Cd, Pb and Zn, particulate form was predominant in the fluid. The elements that are easy to form a sulfide such as Cu, Cd and Pb were removed as a sulfide precipitate from the fluid before erupting to the deep ocean. Therefore, the concentration of these trace elements in the hydrothermal plume showed superiority of a dissolved form, and was slightly high or same concentration in the deep ocean. The concentration of Fe in the fluid was extremely higher (500 - 100,000 times) than that in the deep ocean, and showed a fifty-fifty partition between dissolved form and particulate form. In the hydrothermal plume, Fe formed hydroxide mainly and was removed gradually from the plume as a particulate form in dilution and diffusion process of the plume. These hydroxides may play a role of the precipitant that coprecipitate with absorbing the other trace elements. Because Mn is hard to deposit as a sulfide, dissolved form was predominant in the fluid and Mn showed extreme high concentration same as Fe. Mn was discharged to the deep ocean as a dissolved form and removed from the plume as an oxide with increasing the particulate form gradually in dilution and diffusion process of the plume. In addition, existence of an organic trace element as one of a chemical species of dissolved form was confirmed in the hydrothermal plume, and the relationship between the hydrothermal ecosystem and the organic trace elements is very interesting.

  18. Conversion of kraft lignin under hydrothermal conditions.

    PubMed

    Zhou, Xue-Fei

    2014-10-01

    The aim of this study is to explore hydrothermal conversion of kraft lignin for value-added products. With ranging between 5.4% and 10.6%, total oil yield decreased with the increase of temperature (130, 180, and 230°C), the longer reaction time (15-60min) led to increased total oil yield. Main compound of oils characterized by GC-MS was guaiacol (2-methoxy phenol) in the range of 19-78% of oil depending on different reaction conditions. Residual kraft lignins were characterized by GPC and FTIR with respect to the conversion mechanism of kraft lignin by this process. The conversion of kraft lignin under hydrothermal conditions had something to do with the degradation of ?-O-4 linkages, hydroxyl groups, carbonyl groups, aromatic rings resulting in the increased amount of phenolic OH groups in kraft lignin. PMID:25176169

  19. Hydrothermal phase transformation of hematite to magnetite

    PubMed Central

    2014-01-01

    Different phases of iron oxide were obtained by hydrothermal treatment of ferric solution at 200°C with the addition of either KOH, ethylenediamine (EDA), or KOH and EDA into the reaction system. As usually observed, the ?-Fe2O3 hexagonal plates and hexagonal bipyramids were obtained for reaction with KOH and EDA, respectively. When both KOH and EDA were added into the reaction system, we observed an interesting phase transformation from ?-Fe2O3 to Fe3O4 at low-temperature hydrothermal conditions. The phase transformation involves the formation of ?-Fe2O3 hexagonal plates, the dissolution of the ?-Fe2O3 hexagonal plates, the reduction of Fe3+ to Fe2+, and the nucleation and growth of new Fe3O4 polyhedral particles. PMID:24940172

  20. Resistivity methods in exploration for hydrothermal resources

    SciTech Connect

    Jiracek, G.R.; Ruscetta, C.A.; Foley, D. (eds.)

    1981-05-01

    The practical aspects of using dc resistivity in the exploration for hydrothermal resources are discussed. There are several reasons why low electrical resistivity is expected in hydrothermal aquifers but the association is not without pit falls. Besides outlining the reasons why resistivity has proven a successful geothermal exploration tool, a section on how resistivity is practiced is included. Here, the common electrode arrays are considered with their major advantages and disadvantages pointed out. The current status in resistivity interpretation schemes is touched upon with emphasis on computer modeling. Finally, a successful resistivity case history of a low-temperature resource at Las Alturas Estates, New Mexico is included to illustrate a specific resistivity exploration philosophy. The case history concludes with drilling results which are, of course, the ultimate test.